Intracavity Doubled, Diode-Pumped Nd:YLF Laser · will be performed by a Spectra-Physics ... 2-1 Optical Safety Precautions ... Chapter 4: Controls

EvolutionIntracavity Doubled, Diode-Pumped Nd:YLF Laser

User’s Manual

Models II and X

1335 Terra Bella AvenueMountain View, CA 94043

Part Number 0000-297A, Rev. AJanuary 2003

iii

Preface

This manual provides information regarding the operation and maintenanceof the Evolution II and Evolution X laser systems. The initial installationwill be performed by a Spectra-Physics representative. Spectra-Physicswill not guarantee the performance unless the Evolution is installed by anauthorized Spectra-Physics representative.

The “Introduction” contains a brief description of the Evolution II and Evo-lution X laser systems. Following that section is an important chapter onlaser safety. These two laser systems contain Class IV lasers and, as such,emit laser radiation that can permanently damage eyes and skin. This sec-tion contains information about these hazards and offers suggestions onhow to safeguard against them. To minimize the risk of injury or expensiverepairs, be sure to read this chapter—then carefully follow the instructions.

“Laser Description” contains a short section on laser theory regarding thecavity design and pump mechanism used in the Evolution II and EvolutionX laser systems. It is followed by a more detailed description of these twolaser systems, and concludes with system specifications and outline draw-ngs.

The next few chapters describe the connections and controls of these sys-tems, then guide you through a summary installation (not initial installa-tion) and operation. The last part of the manual covers maintenance andservice and includes a replacement parts list.

“Service” is intended to help you guide your Spectra-Physics field serviceengineer to the source of any problems. Do not attempt repairs yourselfwhile the unit is still under warranty; instead, report all problems to Spectra-Physics for warranty repair.

Should you experience any problems with any equipment purchased fromSpectra-Physics, or you are in need of technical information or support,please contact Spectra-Physics as described in “Customer Service.” Thischapter contains a list of world-wide Spectra-Physics Service Centers youcan call if you need help.

These products have been tested and found to conform to “Directive 89/336/EEC for Electromagnetic Compatibility.” Class A compliance wasdemonstrated for “EN 50081-2:1993 Emissions” and “EN 50082-1:1992Immunity” as listed in the official Journal of the European Communities.They also meet the intent of “Directive 73/23/EEC for Low Voltage.” ClassA compliance was demonstrated for “EN 61010-1:1993 Safety Require-ments for Electrical Equipment for Measurement, Control and Laboratoryuse” and “EN 60825-1:1992 Radiation Safety for Laser Products.” Refer tothe “CE Declaration of Conformity” in Chapter 2, Laser Safety.

Evolution Intracavity Doubled, Diode-Pumped Nd:YLF Laser

iv

These products conform to the requirements of 21 CFR 1040.10 CDRHand are compliant to Underwriters Laboratory UL1950 and are listed asULR for recognized components. This equipment has been designed andtested to comply with the limits for a Class A digital device pursuant to Part15 of the FCC Rules.

Every effort has been made to ensure that the information in this manual isaccurate. All information in this document is subject to change withoutnotice. Spectra-Physics makes no representation or warranty, either expressor implied with respect to this document. In no event will Spectra-Physicsbe liable for any direct, indirect, special, incidental or consequential dam-ages resulting from any defects in this documentation.

Finally, if you encounter any difficulty with the content or style of thismanual, please let us know. The last page is a form to aid in bringing suchproblems to our attention.

Thank you for your purchase of Spectra-Physics instruments.

v

Environmental Specifications

CE Electrical Equipment Requirements

For information regarding the equipment needed to provide the electricalservice listed under “Service Requirements” at the end of Chapter 3, pleaserefer to specification EN-309, “Plug, Outlet and Socket Couplers for Indus-trial Uses,” listed in the official Journal of the European Communities.

Environmental Specifications

The environmental conditions under which the laser system will functionare listed below:

Indoor useAltitude: up to 2000 mTemperatures: 10° C to 40° CMaximum relative humidity: 80% non-condensing for temperatures up to

31° C.Mains supply voltage: do not exceed ±10% of the nominal voltageInsulation category: IIPollution degree: 2

FCC Regulations

This equipment has been tested and found to comply with the limits for aClass A digital device pursuant to Part 15 of the FCC Rules. These limitsare designed to provide reasonable protection against harmful interferencewhen the equipment is operated in a commercial environment. This equip-ment generates, uses and can radiate radio frequency energy and, if notinstalled and used in accordance with the instruction manual, may causeharmful interference to radio communications. Operation of this equipmentin a residential area is likely to cause harmful interference in which casethe user will be required to correct the interference at his own expense.

Modifications to the laser system not expressly approved by Spectra-Physicscould void your right to operate the equipment.

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Table of Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Environmental Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vCE Electrical Equipment Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vEnvironmental Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vFCC Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Warning Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

Standard Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii

Abbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

Unpacking and Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviiUnpacking Your Laser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviiSystem Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviiiAccessory Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviii

Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1Laser Head Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1Power Supply Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2Closed-Loop Chiller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Chapter 2: Laser Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1Hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1Optical Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1Protective Eye Wear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3Electrical Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3CDRH Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4Safety Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Key Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4Remote Interlock Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4Protective Laser Enclosure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5Cover Safety Interlock, Laser Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5Emission Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6Beam Safety Shutter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7Beam Attenuator (Output Port) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7System Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7Warning Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

CE/CDRH Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8


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CD/CDRH Warning Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-11CDRH Requirements and RS-232 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-12Maintenance Required for CDRH Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-13Sources for Additional Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-14

Laser Safety Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-14Equipment and Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-15

Chapter 3: System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1Diode Pumping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1Nd:YLF Laser Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2Acousto-Optic Q-Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2Intracavity Frequency Doubling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3Laser Head Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4Laser Head Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5

Laser Pump Chamber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5AOM Q-Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5LBO Crystal and Temperature Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5

Power Supply Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-6The Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-6Diode Laser Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-6Diode Laser Temperature Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-6Q-Switch Driver and Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-6LBO Crystal Temperature Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-7

Performance Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-7

Chapter 4: Controls, Indicators and Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1The Laser Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1The Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1

Power Supply, Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1Power Supply, Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3

The Evolution Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4The Evolution Chiller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5

Chapter 5: Preparing for System Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1Pumping a Spitfire Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1Required Utilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1Installing the Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-2Preparing to Install the Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-2Preparing to Install the Laser Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-3Preparing to Install the Chiller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-3Mechanical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-4

Chapter 6: System Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1Electrical Current Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1Startup Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-2Shutdown Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-3Long Term Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-3

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Chapter 7: Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1Lasing Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

Cavity Mirror Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1LBO Crystal Temperature Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4

Cleaning the Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5Routine Maintenance, Cooling Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6

Chapter 8: Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1

Symptom: Laser will not start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1Symptom: Emission light comes on but no output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1Symptom: Variations in output power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2Symptom: Power is below specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2Symptom: Laser does not emit Q-switched or CW output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3

Customer Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3Return of the Instrument for Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4

Service Centers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5

Appendix A: Optishield Algaecide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1Filling the Chiller for First Time Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1Periodic Changing of Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1MSDS Sheet for Optishield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3

Appendix B: Computer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1RS-232 Connector Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1RS-232 Communication Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1Command/Query/Response Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1Command Quick Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2Full Command Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2Typical Command Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-5

Notes

Report Form for Problems and Solutions


x

List of FiguresFigure 2-1: These CE and CDRH standard safety warning labels would be appropriate for use

as entry warning signs (EN 60825-1, ANSI 4.3.10.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2Figure 2-2: Folded Metal Beam Target . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3Figure 2-3: Power supply front panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4Figure 2-4: Remote Interlock Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5Figure 2-5: The laser head cover safety interlock switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5Figure 2-6: The Scientific laser head emission indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-6Figure 2-7: CE/CDRH Radiation Control Drawing: Scientific Version . . . . . . . . . . . . . . . . . . . . . . . . .2-8Figure 2-8: CE/CDRH Radiation Control Drawing: OEM Version . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-9Figure 2-9: CDRH/CE Radiation Control Drawing: Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-10Figure 2-10: CE/CDRH Warning Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-11Figure 3-1: Acousto-Optic Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3Figure 3-2: Evolution Component Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4Figure 4-1: Power Supply Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1Figure 4-2: Interlock Connector Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3Figure 4-3: Power Supply Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3Figure 4-4: The Controller Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4Figure 5-1: Evolution Scientific Laser Head Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-4Figure 5-2: Evolution OEM Laser Head Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-5Figure 5-3: Evolution Power Supply and Controller Outline Drawings . . . . . . . . . . . . . . . . . . . . . . . . .5-5Figure 7-1: Interlock by-pass plates shown “parked” inside the rear of the laser head. . . . . . . . . . . . .7-2Figure 7-2: Interlock switch and by-pass plate mounting position. . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-2

List of TablesTable 2-1 : Label Translations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-12Table 3-1 : Specifications, Evolution II/X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-7Table 4-1: Evolution Fuse Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3Table 5-1: Utility Requirement for the Evolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-2Table 5-2: Component Weights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-4Table B-1: Evolution Status Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-3Table B-2: Evolution Status Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-4Table B-3: Evolution Interlock Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-4

xi

Warning Conventions

The following warnings are used throughout this manual to draw yourattention to situations or procedures that require extra attention. They warnof hazards to your health, damage to equipment, sensitive procedures, andexceptional circumstances. All messages are set apart by a thin line aboveand below the text as shown here.

Warning!ESD

Laser radiation is present.

Condition or action may present a hazard to personal safety.

Condition or action may cause damage to equipment.

Condition or action may cause poor performance or error.

Text describes exceptional circumstances or makes a special refer-ence.

Do not touch.

Appropriate laser safety eyewear should be worn during this opera-tion.

Danger!

Warning!

Don'tTouch!

EyewearRequired

Note

Condition or action may present an electrical hazard to personalsafety.

Refer to the enclosed documents and manual before operating orusing this device.

Action may cause electrostatic discharge and cause damage to equip-ment.

Danger!Laser Radiation

Caution!

Danger!

xiii

Standard Units

The following units, abbreviations, and prefixes are used in this Spectra-Physics manual:

Quantity Unit Abbreviation

mass kilogram kg

length meter m

time second s

frequency hertz Hz

force newton N

energy joule J

power watt W

electric current ampere A

electric charge coulomb C

electric potential volt V

resistance ohm Ωinductance henry H

magnetic flux weber Wb

magnetic flux density tesla T

luminous intensity candela cd

temperature celcius C

pressure pascal Pa

capacitance farad F

angle radian rad

Prefixes

tera (1012) T deci (10-1) d nano (10-9) n

giga (109) G centi (10-2) c pico (10-12) p

mega (106) M mill (10-3) m femto (10-15) f

kilo (103) k micro (10-6) µ atto (10-18) a

xv

Abbreviations

These abbreviations are used in this manual:

ac alternating current

AOM acousto-optic modulator

APM active pulse mode locking

AR anti reflection

bi-fi birefringent filter

CDRH Center of Devices and Radiological Health

CPM colliding pulse mode-locking

CW continuous wave

dc direct current

E/O electro-optic

fs femtosecond or 10-15 second

GTI Gires-Toutnois Interferometer

GVD group velocity dispersion

HR high reflector

IR infrared

OC output coupler

ps picosecond or 10-12 second

PZT piezo-electric transducer

RF radio frequency

SBR saturable Bragg reflector

SCFH standard cubic feet per hour

SPM self phase modulation

TEM transverse electromagnetic mode

Ti:sapphire Titanium-doped Sapphire

UV ultraviolet

λ wavelength

xvii

Unpacking and Inspection

Unpacking Your Laser

Your Evolution laser was packed with great care, and its container wasinspected prior to shipment. If any major damage was noticed at the time ofreceipt (holes in the containers, water damage, crushing, etc.), please notifythe carrier.

Carefully inspect the laser system as you unpack it. If any damage is evi-dent, such as dents or scratches on the covers or broken parts, immediatelynotify the carrier and your Spectra-Physics sales representative.

Keep the shipping containers. If you file a damage claim, you may needthem to demonstrate that the damage occurred as a result of shipping. Ifyou need to return the system for service at a later date, the speciallydesigned container assures adequate protection.

The Evolution system is shipped in two crates. Carefully open and unpackboth crates in a clean, dry area and inspect each component as you unpackit. To open a crate, remove the clamps from the bottom edge of the crateand lift off the top section.

In the main crate, the top level contains the laser head with attached umbil-ical; the lower level contains the power supply, also with umbilicalattached. Also present is a small accessory box (refer to “Accessory Kit”below).

The Evolution laser head is cradled between foam blocks. Remove the laserhead and its attached umbilical cord, taking care not to lift the unit by the

It is recommended that you wait for your Spectra-Physics representativeto unpack your system. In no event should you attempt to install thelaser yourself or remove the lid sealing the laser cavity. Either action, ifunauthorized, will void your warranty, and you will be charged for therepair of any damage that may result. Refer to Chapter 5, “Preparing forSystem Installation.”

Warning!

Do not turn the crates upside-down or on their sides. Once the laser headand chiller are out of their crates, do not turn them upside-down or ontheir sides. Damage to these units may result.

Warning!


xviii

umbilical cord or its attachment. Remove any tie-wraps or tape holding theumbilical cable in place. Put the foam blocks back in the shipping crate forstorage.

The Evolution power supply is strapped to the shipping crate. Remove thestraps and remove any tie-wraps or tape holding the umbilical cable inplace. Carefully lift the power supply off the crate and onto the floor.

The second crate contains the chiller and attached hoses. These arestrapped to the base of the crate. Remove the straps and carefully lift thechiller off the base of the crate.

The system can now be moved into the laboratory for installation.

System Components

• Laser Head• Power Supply• Controller with connecting cable• Chiller with hoses, attachments, etc.• Accessory Kit

Accessory Kit

• beam tube(s)• 4 adjusting feet for laser head (installed)• set of Allen-head drivers

1-1

Chapter 1 Introduction

The Evolution system is an intracavity-doubled, diode-pumped Nd:YLFlaser with a green output wavelength at 527 nm. The Q-switched output ispulsed at repetition rates controlled by the user, typically between 1 and10 kHz. The user can select to have the laser beam exit the laser headthrough either the front or side panel via an internal removable mirror. TheEvolution laser offers high efficiency, low maintenance and excellent beamquality.

The Evolution system comprises four main elements:

• Laser head assembly• Power supply assembly• Controller• Closed-loop chiller

Optional computer control through the RS-232 interface is available.

Laser Head Assembly

The laser head is a sealed aluminum chassis that contains the followingcomponents:

• Diode-pumped laser chamber• Optical resonator assembly• Acousto-optic Q-switch• Frequency doubling crystal and temperature-controlled oven• Safety shutter

The Evolution laser head is available in two versions: OEM and Scientific.The OEM version is enclosed in a small aluminum chassis to minimize itsfootprint and to allow simple integration with other instruments. The Scien-tific version houses the OEM chassis in a secondary external housing thatincludes an emission indicator and four mounting feet. The latter allowadjustment of the beam height.

The Evolution was designed to provide optimum performance with min-imal user intervention. Normal operation should not require the laserhead cover to be opened. Removing the laser head cover without priorauthorization by Spectra-Physics will void the warranty.

Caution!


1-2

Power Supply Assembly

The power supply assembly includes a master control pc board and all theelectronics required to drive the diode lasers, stabilize the temperature ofthe doubling crystal and diode lasers, Q-switch the laser and monitor theinterlocks. The power supply connects to the laser head through a perma-nently attached, 3-meter long umbilical cable. The power supply containsthe following components:

• Master control electronics• Diode laser power supply• Diode laser and doubling crystal temperature controllers, and heater

relay circuitry• Q-switch RF power supply• DC power supply

Controller

The hand-held controller contains the electronics used to control the laserfunctions, such as output power level and Q-switch frequency, and to dis-play the status of the safety interlocks. Control menus are displayed on anLCD screen. The controller attaches to the front of the power supply via a9-pin D-sub serial cable.

Closed-Loop Chiller

A small closed-loop chiller is provided with the Evolution to remove wasteheat from the laser system. In addition, it is part of a sub-system that stabi-lizes the wavelength of the diode lasers to ensure maximum absorption ofthe pump light in the gain medium. The chiller has two hoses with quick-release connectors and an internal or external pressure regulator valve toreduce the water pressure at the laser head. A chemical additive in the dis-tilled water coolant prevents algae growth and corrosion.

The Evolution system is further described in Chapter 3, “System Over-view.” Operating the Evolution, including the use of the controller, isdescribed in Chapter 6, “System Operation.”

See Appendix B for information about operating the Evolution system viathe RS-232 interface.

2-1

Chapter 2 Laser Safety

This safety section should be reviewed thoroughly prior to operating theEvolution laser system, and the safety precautions listed herein should befollowed carefully.

Hazards

Hazards associated with lasers generally fall into the following categories:

• Exposure to laser radiation which may result in damage to the eyes orskin

• Exposure to chemical hazards such as particulate matter or gaseoussubstances released as a result of laser material processing, or as by-products of the lasing process itself

• Electrical hazards generated in the laser power supply or associatedcircuits

• Secondary hazards such as:

X-radiation from faulty power suppliesPressurized lamps, hoses, cylinders, etc.Pressurized liquids and gasses

Optical Safety Precautions

The special nature of laser light poses safety hazards not associated withlight from conventional sources. The safety precautions listed below are tobe read and observed by anyone working with the laser. At all times, ensurethat personnel who operate, maintain or service the laser are protected fromaccidental or unnecessary exposure to laser radiation exceeding the acces-

This user information is in compliance with section 1040.10 of theCDRH Laser Products Performance Standards from the Health andSafety Act of 1968. Use of controls or adjustments, or performance ofprocedures other than those specified herein, may result in hazardousradiation exposure.

Warning!

The Evolution system is a Class IV High Power Laser whose beam is asafety and fire hazard. Take precautions to prevent exposure to direct orreflected beams. Diffuse as well as specular reflections can cause severeeye or skin damage.



2-2

sible emission limits listed in “Performance Standards for Laser Products,”United States Code of Federal Regulations, 21CFR1040 10(d).

The following safety precautions are to be observed at all times:

• Wear protective eyewear at all times; selection depends on the wave-length and intensity of the radiation, the conditions of use, and thevisual function required. Protective eyewear vendors are listed in theLaser Focus World, Lasers and Optronics, and Photonics Spectrabuyer’s guides. Consult the ANSI, ACGIH, or OSHA standards listedat the end of this section for guidance.

• Avoid wearing jewelry or other objects that may reflect or scatter thebeam while using the laser.

• Work in high ambient illumination whenever possible. This keeps theeye’s pupil constricted, thus reducing the possibility of eye damage.

• Never look directly into the laser beam.• Avoid looking at the beam; even diffuse reflections are hazardous.• Use an infrared detector to ascertain whether the laser beam is on or

off before working on the laser.• Work with the lowest beam intensity consistent with the application.• Operate lasers only in well-marked areas with controlled access. Be

sure to post appropriate warning signs, clearly visible (Figure 2-1).• Limit access to the laser system to qualified personnel who are essen-

tial to its operation and who have been trained in the safety principles.When not in use, lasers should be shut down completely and desig-nated off-limits to unauthorized personnel.

• Provide enclosures for beam paths whenever possible.• Terminate the laser beam with an appropriate energy-absorbing target

(Figure 2-2).• Shield unnecessary reflections and scattered laser radiation.• Avoid blocking the output beam or any reflections with any part of

your body.• Set up the laser so that the beam height is either well above or well

below eye level.

Figure 2-1: These CE and CDRH standard safety warning labels wouldbe appropriate for use as entry warning signs (EN 60825-1, ANSI 4.3.10.1).

VISIBLE AND/OR INVISIBLE LASER RADIATIONAVOID EYE OR SKIN EXPOSURE TO DIRECT

OR SCATTERED RADIATION.CLASS IV LASER PRODUCT

MAX OUT5PUT < 50WWAVELENGTH 527NMPULSELENGTH 200NS

808-5326

Laser Safety

2-3

Figure 2-2: Folded Metal Beam Target

Protective Eye Wear

It is recommended that laser-safe eye wear be worn at all times when theEvolution laser is on. The eye wear should protect against at least the fol-lowing wavelength ranges:

• 1047 – 1053 nm covers the fundamental operation wavelength• 523 – 527 nm covers the second harmonic wavelength• 794 – 810 nm covers the wavelength emitted by the diode lasers

During normal operation, the operator will not be exposed directly to haz-ardous diode laser emission. However, removing the mechanical housingcover will not only invalidate the warranty, but will also expose the opera-tor to hazardous diode laser radiation.

Electrical Safety Precautions

The following precautions should be observed by anyone working withpotentially hazardous electrical circuitry:

• Disconnect main power lines before working on any electrical equip-ment when it is not necessary for the equipment to be operating.

• Do not short or ground the power supply output. Protection againstpossible hazards requires proper connection of the ground terminal onthe power cable, and an adequate external ground. Check these con-nections at the time of installation, and periodically thereafter.

• Never work on electrical equipment unless there is another personnearby who is familiar with the operation and hazards of the equip-ment, and who is competent to administer first aid.

• When possible, keep one hand away from the equipment to reduce thedanger of current flowing through the body if a live circuit is touchedaccidentally.

• Always use approved, insulated tools when working on equipment.

Normal operation of the Evolution laser should not require access to thepower supply circuitry. Removing the power supply cover will exposethe user to potentially lethal electrical hazards. Contact an authorizedservice representative before attempting to correct any problem with thepower supply.


2-4

• Special measurement techniques are required for this system. Groundreferences must be selected by a technician who has a complete under-standing of the system operation and associated electronics.

CDRH Compliance

The safety features listed below have been incorporated into the Scientificversion of the Evolution to conform to Federal performance standards asrequired by United States Code of Federal Regulations, section 21 CFR1040.10(h)(1)(iv). Any modification or use of the Evolution laser thatchanges, disables, or overrides the function of the engineering controls andsafety features invalidates the Class IV certification of this laser.

Safety Devices

Figure 2-3: Power supply front panel

Key Switch

A separate key switch is provided on the power supply to enable power tothe laser. The key cannot be removed from the switch except in the OFFposition. This prevents use of the laser by unauthorized personnel.

Remote Interlock Connector

The remote INTERLOCK connector on the power supply front panel is usedto connect to an external CDRH safety interlock. For example, when con-nected to a normally-closed door switch, laser action is terminated whenthe door is opened to prevent accidental exposure to laser radiation. Onceterminated, lasing can only be resumed by closing the contacts again andthen cycling the key switch off and on to reset the interlock function.

AC POWER ON

LASER ENABLE

INTERLOCK

ON

– USER– QS SYNC

– QS VAR SYNC

– QS TRIG

– COVER

– DIODE TEMP

– XSTAL TEMP

– TEMP SENSOR

– FLOW

– PS ERROR

– DIODE ERROR

I

0

Interlock Display

Laser Enable On Lamp

Laser Enable Keyswitch

Remote Interlock Connector

AC Power On Lamp

AC Power Switch

Laser Safety

2-5

To connect the interlock switch, remove the shorting jumper plug providedwith the system and either rewire the connector according to the wiring dia-gram in Figure 2-4 or use a similarly wired plug.

Figure 2-4: Remote Interlock Connector

Protective Laser Enclosure

The laser head housing encloses the laser beam path until the beam exits atthe front or side output port. The laser pump chamber is also enclosed toshield the user from stray diode laser light and to protect the diode lasersfrom exposure to dust and electrostatic discharge.

Cover Safety Interlock, Laser Head

Figure 2-5: The laser head cover safety interlock switches.

Cover interlock switches ensure that the OEM Evolution cannot be oper-ated if the metal cover protecting the optical cavity is removed or is not inplace or, in the scientific version, if the external sheet metal cover is not inplace. If either cover is removed, the laser is immediately turned off.

INTERLOCK

ON

LASER ENABLE

J1J3

DOOR SWITCH


Do not operate the laser with the cover removed!

Interlock Switch (typical)

Rear Panel

By-pass PlateMounting Position


2-6

Emission Indicators

Figure 2-6: The Scientific laser head emission indicator

After a start command has been issued by either pressing the ON/OFF but-ton on the controller or by issuing a software command, an emission indi-cator on the laser head turns on about 5 seconds later to warn that the laseremission is imminent.

Scientific Evolution

The emission indicator light on the front of the scientific laser housingturns on whenever current is supplied to the diode lasers to warn that haz-ardous laser radiation is imminent or present. Note that when the emissionindicator is on, diode laser light is present inside the housing even thoughthe laser cavity may not be emitting green or infrared laser radiation (forexample, if cavity optics are misaligned).

OEM Evolution

A detachable emission indicator supplied with the OEM laser can bemounted on the laser head or in a remote location. It functions the same asthe permanent indicator on the scientific version. To comply with CDRHrequirements, it must be placed in a clearly visible location no more than10 feet (3 m) from the Evolution output port. A detachable indicator is par-ticularly useful if the OEM laser is installed in an instrument where an indi-cator attached to the laser head would not be clearly visible.

All emission indicators remain on as long as the laser is capable of lasing.They illuminate approximately 5 seconds prior to actual emission to givenearby personnel time to avoid exposure.

Do not operate the Evolution laser with any of its covers removed exceptwhen necessary during required service. Removing covers may exposepersonnel to hazardous voltages and radiation, and it also increases therate of optical surface contamination. Unauthorized removal of thecover protecting the optical cavity will void the warranty.


Output End View

AVOID EXPOSUREVISIBLE AND/ORINVISIBLE LASER

RADIATION IS EMITTEDFROM THIS APERTURE

808-

5276

Emission Indicator

Laser Safety

2-7

Beam Safety Shutter

A solenoid-activated safety shutter is mounted in the optical cavity to inter-rupt laser action when necessary.

The shutter interlock fault and fail-safe position is closed. When the laser isturned on, either by pressing the ON/OFF button on the controller or byissuing a software command, the shutter is opened.

Beam Attenuator (Output Port)

The beam from the laser output port can be blocked by a manually operatedshutter. If the optional side port is used, a metal disc (supplied) can beinserted into that port to block emission.

System Controls

The controller supplied with the Evolution laser system contains all thecontrols necessary for normal operation. It can be moved up to 10 feet (3 m)from the laser power supply to prevent exposure to laser radiation duringoperation. The Evolution system may also be operated remotely via a com-puter using a program written by you using the commands outlined inAppendix B. Connection to the computer is via the RS-232 port on the frontof the power supply.

Operating Instructions

All instructions for the safe operation and maintenance of the Evolutionlaser safely are provided in this user’s manual. Read the entire manual,especially this chapter, before operating your laser.

Warning Labels

Certification and warning labels are affixed to the Evolution laser to verifycompliance with 21 CFR 1040, to provide information on the wavelengthand power emitted, and to warn the user against accidental exposure tolaser radiation. The location and type of warning labels used on the scien-tific and OEM versions of the Evolution laser head are shown in Figure 2-7and Figure 2-8, respectively. Locations of the labels for the power supplyare shown in Figure 2-9, and the labels themselves are shown in Figure 2-10.

Translations of the warning labels are provided in Table 2-1 for non-English speaking users. The numbers in the laser illustrations correspond tothe various numbered labels in Figure 2-10.


2-8

CE/CDRH DrawingsLabels are on page 2-11

Figure 2-7: CE/CDRH Radiation Control Drawing: Scientific Version

IN

OUT

Rear View Output End View

Emission Indicator

Top View

Right Side View

Left Side View

MANUFACTURED:

MONTH

MODEL

YEAR

S/N

THIS LASER PRODUCT COMPLIESWITH 21 CFR 1040 AS APPLICABLE.

MADE IN U.S.A.

Spectra-Physics Lasers, Inc.1344 Terra Bella Avenue

Mountain View, California 94039

0420-7840

1 4



808-

5276

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808-

5276



808-

5276AVOID EXPOSURE

VISIBLE AND/ORINVISIBLE LASER


808-

5276

4 1

45984

MANUFACTURED:

MONTH

MODEL

YEAR

S/N


MADE IN U.S.A.



0420-7840

CAUTIONVISIBLE, INVISIBLE ANDRF ELECTROMAGNETICRADIATION WHEN OPEN.

808-7099

DANGERVISIBLE AND/OR INVISIBLE LASER RADIATION

WHEN OPEN AND INTERLOCK DEFEATED.AVOID EYE OR SKIN EXPOSURE TO DIRECT

OR SCATTERED RADIATION.CLASS 4 LASER PRODUCT

VORSICHTSICHTBARE UND/ODER UNSICHTBARE

LASERSTRAHLUNG, WENN ABDECKUNGGEOFFNET UND SICHERHEITSVERRIEGLUNG

UBERBRUCKT.BESTRAHLUNG VON AUGEN ODER HAUTDURCH DIREKTE OER STREUSTRAHLUNG

VERMEIDEN.LASER KLASSE 4

DANGERRAYONNEMENT LASER VISIBLE ET/OU

INVISIBLE DANGEREUSE EN CAS D'ORVERTURENEUTRALISEE.

EXPOSITION DANGEREUSE DE L'OEIL OU DELA PEAU AU RAYONNEMENT DIRECT OU

DIFFUS.LASER CLASSE 4

808-7098

VISIBLE AND/OR INVISIBLE LASER RADIATION.AVOID EYE OR SKIN EXPOSURE TO DIRECT


MAX OUTPUT < 50 WWAVELENGTH 527 nmPULSELENGTH 200 nm

808-5326

Laser Safety

2-9

Figure 2-8: CE/CDRH Radiation Control Drawing: OEM Version

Rear View Output End View

Top View

Right Side View

Left Side View

4



808-

5276

6 2 37

4

808-

5326

VIS

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808-

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808-

5276AVOID EXPOSURE

VISIBLE AND/ORINVISIBLE LASER


808-

5276

4 1

45984

MANUFACTURED:

MONTH

MODEL

YEAR

S/N


MADE IN U.S.A.



0420-7840

CAUTIONVISIBLE, INVISIBLE ANDRF ELECTROMAGNETIC

RADIATION WHEN OPEN.808-7099












808-7098



MAX OUTPUT < 50 WWAVELENGTH 527 nmPULSELENGTH 200 nm

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RF2

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5276


2-10

Figure 2-9: CDRH/CE Radiation Control Drawing: Power Supply

Refer to the user’s manual supplied with the chiller for safety informationon the chiller.

F1 F2

AC IN

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MONTH

MODEL

YEAR

S/N


MADE IN U.S.A.



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MAX OUTPUT < 50 WWAVELENGTH 527 nmPULSE LENGTH 200 µs

808-53265

1

67

Laser Safety

2-11

CD/CDRH Warning Labels

Figure 2-10: CE/CDRH Warning Labels

MANUFACTURED:

MONTH

MODEL

YEAR

S/N


MADE IN U.S.A.



0420-7840

Identificaiton/CertificationLabel (1)

Danger Laser BeamLabel, Laser Head (2)

Danger LabelLaser Output Specifications (5)

Aperture LabelLaser Head (4)

CE Warning LabelInterlock Defeated (9)

CE Warning LabelPower Supply (10)

Caution Label RF Energy Present (8)

Caution Label (7)

Caution LabelHigh Voltage (6)

Interlocked CoverLabel, Laser Head (3)

VISIBLE AND/OR INVISIBLELASER RADIATION WHENOPEN AND INTERLOCK

DEFEATED!AVOID EYE OR SKIN

EXPOSURE TO DIRECTOR SCATTERED RADIATION.CLASS IV LASER PRODUCT

808-7255












808-7098

DANGERVISIBLE AND/OR INVISIBLE LASER RADIATION.

AVOID EYE OR SKIN EXPOSURE TO DIRECTOR SCATTERED RADIATION. CONSULT

INSTRUCTION MANUAL.CLASS 4 LASER PRODUCT


LASERSTRAHLUNG.BESTRAHLUNG VON AUGEN ODER HAUTDURCH DIREKTE OER STREUSTRAHLUNG

VERMEIDEN.NAHERE INFORMATIONEN: SIEHE

BEDIENUNGSANLEITUNG.LASER KLASSE 4

DANGERRAYONNEMENT LASER VISIBLE ET/OUINVISIBLE. EXPOSITION DANGEREUSE

DE L'OEIL OU DE LA PEAU AURAYONNEMENT DIRECT OU DIFFUS.

CONSULTER LE MANUEL D'INSTALLATION.LASER CLASSE 4

808-7097

CAUTIONVISIBLE, INVISIBLE ANDRF ELECTROMAGNETICRADIATION WHEN OPEN.

808-7099



808-

5276



MAX OUTPUT < 50 WWAVELENGTH 527 nmPULSE LENGTH 200 µs 808-5326

808-5326

VISIBLE AND/OR INVISIBLE LASER RADIATIONWHEN OPEN AND INTERLOCK DEFEATED!

AVOID EYE OR SKIN EXPOSURE TO DIRECTOR SCATTERED RADIATION.CLASS IV LASER RADIATION


2-12

CDRH Requirements and RS-232 Control

The Evolution laser and its power supply comply with all applicable CDRHsafety standards when operated with the supplied controller. The laser mayalso be operated via RS-232 commands sent to the RS-232 connector on thefront of the power supply. When this is this case, the controller is not usedand the user must supply an emission indicator in order to satisfy CDRHregulations. When on, it indicates that laser energy is present or can beaccessed. It may be a “power-on” lamp, a computer display that flashes astatement to this effect, or an indicator on the control equipment for thispurpose. It need not be marked as an emission indicator so long as its func-tion is obvious. This indicator is required on any control panel that effectslaser output, including a computer display panel.

Table 2-1: Label Translations

Label # French German Spanish Dutch

ApertureLabel

(4)

Exposition Dan-gereuse! Rayonne-ment visible et/ou invisible est emis par cette ouverture

Austritt von sicht-barer und unsicht-barer Laser-strahlung. Bestrahl-ung vermeiden!

Por esta abertura se emite radiacion laser visible e invisible; evite la exposicion

Vanuit dit apertuur wordt zichtbare en onzichtbare lasers-traling geemiteerd! Vermijd blootstelling!

Interlocked Cover Label

(3)

Danger! Rayonne-ment Laser Visible et/ou Invisible en Cas D’Ouverture et lorsque la securité est neutralisée; exposition danger-euse de l’oeil ou de la peau au rayonne-ment direct ou diffus. Laser de Classe 4.

Vorsicht! Sichtbare und/oder unsicht-bare Laserstrahlung wenn geöffnet und Sicherheitsverrie-gelung überbruckt. Bestrahlung von Augen oder Haut durch direkt oder Streustrahlung ver-meiden. Laser Klasse 4.

Peligro! Al abrir y retirar el dispositivo de seguridad exist radiacion laser visi-ble y invisible; evite que los ojos o la piel queden expuestos tanto a la radiacion directa como a la dispersa. Producto laser clase 4.

Gevaar! Zichtbare en onzichtbare lasers-traling! Vermijd bloot-stelling van oog of huid ann direkte straling of terug-kaatsingen daarvan! Klas 4 laser produkt.

Laser Safety

2-13

Maintenance Required for CDRH Compliance

This section lists the maintenance required to keep this laser product incompliance with CDRH regulations.

This laser product complies with Title 21 of the United States Code of Fed-eral Regulations, Chapter 1, Sub-chapter J, Parts 1040.10 and 1040.11, asapplicable. To maintain compliance, verify the operation of all featureslisted below, either annually or whenever the product has been subjected toadverse environmental conditions (e.g. fire, flood, mechanical shock,spilled solvents). This maintenance is to be performed by:

• verifying that removing the laser cover closes the intracavity shutterand illuminates the interlock LED on the remote box and on the laserpower supply,

• verifying that, when the cover interlock is defeated, the defeat mecha-nisms are clearly visible and prevent installation of the cover until theyare removed,

• verifying that all the warning labels listed in Figure 2-10 are presentand firmly affixed in the correct locations.

• verifying that removing the interlock connector plug on the front of thepower supply or by opening any switch wired to it prevents operationof the laser,

• verifying that the time delay between illumination of the emissionindicator and start of laser emission gives enough warning to allowpersonnel to avoid exposure to the radiation,

• verifying that the beam attenuator (shutter):

a operates properly when the laser is turned off from the controlleror remote computer controller,

b closes when the key switch is turned off, and

c blocks access to laser radiation.


2-14

Sources for Additional Information

The following are some sources for additional information on laser safetystandards, safety equipment, and training.

Laser Safety Standards

Safe Use of Lasers (Z136.1: 1993)American National Standards Institute (ANSI)11 West 42nd StreetNew York, NY 10036Tel: (212) 642-4900

Occupational Safety and Health Administration (Publication 8.1-7)U. S. Department of Labor200 Constitution Avenue N. W., Room N3647Washington, DC 20210Tel: (202) 693-1999

A Guide for Control of Laser Hazards, 4th Edition, Publication #0165American Conference of Governmental andIndustrial Hygienists (ACGIH)1330 Kemper Meadow DriveCincinnati, OH 45240Tel: (513) 742-2020Internet: www.acgih.org/home.htm

Laser Institute of America13501 Ingenuity Drive, Suite 128Orlando, FL 32826Tel: (800) 345-2737Internet: www.laserinstitute.org

Compliance Engineering70 Codman Hill RoadBoxborough, MA 01719Tel: (978) 635-8580

International Electrotechnical CommissionJournal of the European CommunitiesEN60825-1 TR3 Ed.1.0—Laser Safety Measurement and InstrumentationIEC-309—Plug, Outlet and Socket Coupler for Industrial UsesTel: +41 22-919-0211Fax: +41 22-919-0300Internet: http://ftp.iec.c.h/

CenelecEuropean Committee for Electrotechnical StandardizationCentral Secretariatrue de Stassart 35B-1050 Brussels

Document Center1504 Industrial Way, Unit 9Belmont, CA 94002-4044Tel: (415) 591-7600

Laser Safety

2-15

Equipment and Training

Laser Safety GuideLaser Institute of America12424 Research Parkway, Suite 125Orlando, FL 32826Tel: (407) 380-1553

Laser Focus World Buyer's GuideLaser Focus WorldPenwell Publishing10 Tara Blvd., 5th FloorNashua, NH 03062Tel: (603) 891-0123

Lasers and Optronics Buyer's GuideLasers and OptronicsGordon Publications301 Gibraltar DriveP.O. Box 650Morris Plains, NJ 07950-0650Tel: (973) 292-5100

Photonics Spectra Buyer's GuidePhotonics SpectraLaurin PublicationsBerkshire CommonPO Box 4949Pittsfield, MA 01202-4949Tel: (413) 499-0514


2-16

3-1

Chapter 3 System Overview

The heart of the Evolution system is an Nd:YLF laser rod that is pumped byfour AlGaAs diode laser arrays. The laser light produced by the Nd:YLFlaser rod is converted to 527 nm green light and emitted as energetic Q-switched pulses.

The laser pump chamber contains the Nd:YLF laser rod and diode lasers.The diode lasers “pump” the Nd:YLF rod; that is, their output excites theelectrons of the neodymium atoms in the YLF crystal, which emit the1053 nm light that is characteristic of their laser transition. The mirrors inthe Evolution laser cavity are all highly ref1ective at the 1053 nm wave-length to contain this light entirely inside of the resonator.

Using an acousto-optic modulator (AOM), this light is Q-switched at repe-tition rates from 1 to 10 kHz, as selected by the user, to produce pulsesfrom 50 to 150 ns long. The pulse duration depends on the pulse repetitionrate and the pump laser used.

The fundamental 1053 nm wavelength of the Nd:YLF laser is frequency-doubled to produce green output at 527 nm. This is accomplished by pass-ing the Nd:YLF light through a lithium triborate (LBO) crystal. In order tomaximize the conversion of the fundamental wavelength to the green har-monic, the LBO crystal is placed inside the laser cavity where the funda-mental beam is most intense (the conversion efficiency of frequencydoubling increases rapidly with the intensity of the fundamental lightinput). LBO offers excellent efficiency and a higher damage threshold thanother commonly used crystals.

These 527 nm pulses exit the laser head from the forward output port, orfrom the side output port if the internal turning mirror is removed. TheEvolution is ideally suited for pumping Ti:sapphire ultrafast amplifiers, andit has been optimized as a pump source for the Spectra-Physics Spitfire andHurricane Ti:sapphire amplifier systems.

Diode Pumping

The narrow spectral emission of diode lasers allows extremely efficientpumping of laser materials with little or no diode light falling outside of theabsorption band of the gain medium. This results in negligible waste heatgeneration and low electrical and cooling utility requirements. Such lowwaste heat generation also results in negligible deleterious thermal effectsin the laser rod, such as thermal lensing and depolarization. Another keyadvantage of diode laser pumping is that diodes have lifetimes of manythousands of hours, compared to only hundreds of hours for arc-lamps.


3-2

Nd:YLF Laser Material

The Evolution uses neodymium-doped lithium yttrium fluoride (Nd:LiYF4,most commonly abbreviated as Nd:YLF) as its gain medium. Its longupper-state lifetime (470 µs) provides efficient energy storage for highpulse energy operation at low repetition rates. The low thermal lensing andnatural birefringence of Nd:YLF enable scaling to higher power withoutthe loss of beam quality or the need for complex resonator designs.

As a birefringent material, Nd:YLF lases at two principle wavelengths: the1047 nm (extraordinary) or the 1053 nm (ordinary) transition. Both linesoriginate on the same Stark split 4F3/2 upper level. The good thermal con-ductivity of Nd:YLF allows efficient heat extraction, and its natural bire-fringence overwhelms thermally induced birefringence, eliminating thethermal depolarization problems of optically isotropic hosts like Nd:YAG.

The 1053 nm transition is used in the Evolution because of the somewhathigher absorption of the pump light by this transition, resulting in lowerheat generation and therefore lower thermal lensing.

Acousto-Optic Q-Switching

The AOM is a block of transparent fused silica material that acts as an opti-cal phase grating when vibrated by an ultrasonic wave. The photoelasticeffect couples the strain field of the ultrasonic wave to the optical index ofrefraction in the block. The resultant optical grating has a period set by theacoustic (sound) wavelength and an amplitude proportional to the soundamplitude.

When a light beam is incident upon this grating, a portion of the intensity isdiffracted out of the beam. By choosing beam parameters properly, a por-tion of any laser beam that attempts to circulate within the resonator experi-ences a diffraction loss that is sufficient to spoil the “Q” of the cavity andprevent lasing (i.e., there is no circulating beam).

With no circulating laser light available to pass through the laser medium,the pump energy builds up the gain to a higher level than would otherwisebe present. (The long lifetime of the upper-state laser level of Nd:YLF isvery beneficial at this point).

The ultrasonic wave is impressed on the AOM by a piezo-electric trans-ducer. Switching off the driving voltage to the transducer returns the AOMto its passive state of high optical transmission, and the laser resonator isreturned to its high Q-state. The internal beam is no longer deflected but,instead, is amplified by the high gain now available in the Nd:YLF rod, anda powerful “Q-switched” laser pulse is emitted.

Re-applying voltage to the AOM with the transducer again spoils the cavityQ, prevents lasing and allows the gain to rebuild to a high level in the rod.This process (the pulse frequency) is repeated at the rate set by the user, butwithin the limits set by the characteristics of the laser.

System Overview

3-3

Figure 3-1: Acousto-Optic Modulation

Intracavity Frequency Doubling

Efficient frequency doubling requires power densities that are not normallyavailable from a CW-pumped laser. Placing the nonlinear doubling crystalinside the resonator exposes it to high circulating power density. Power iscoupled out of the resonator at the second harmonic wavelength by usingan output mirror that is 100% reflective at the fundamental wavelength buttransmits the second harmonic wavelength.

Intracavity frequency doubling itself behaves in a manner that is somewhatanalogous to an output coupler in a normal laser. It is only necessary thatthe conversion efficiency equals the theoretical optimum mirror transmis-sion in order to completely convert the fundamental 1053 nm Nd:YLFwavelength into the green 527 nm second harmonic.

In order to achieve frequency-doubled output, the fundamental and secondharmonic light must be “phase-matched” within the crystal; that is, the1053 nm and the 527 nm waves must be together, in phase, over a reason-able length of the crystal. However since the wavelengths are substantiallydifferent, the two beams will be out of phase since they have different val-ues for the index of refraction in the crystal, unless special techniques areemployed. Non-critical phase matching relies on the temperature depen-dence of the dispersion of the crystal to provide a match in the refractiveindex at the two wavelengths. As the name implies, non-critical phasematching is much less sensitive to the alignment of the crystal than otherphase-matching schemes.

LBO is a nonlinear optical crystal characterized by a relatively high opticaldamage threshold and a moderate nonlinear optical coefficient, as well asexcellent material properties. A small birefringence in the crystal allows fornon-critical phase matching and provides a larger acceptance angle for highefficiency frequency conversion. The crystal must be heated and tempera-ture-stabilized to maintain good conversion efficiency.

CavityEndMirror

Piezo-ElectricTransducer


3-4

Laser Head Configuration

The Evolution laser head component layout is shown in Figure 3-2. Thelaser resonator is a folded design, which reduces the overall size of theEvolution while simultaneously providing for efficient output coupling ofthe second harmonic light.

Both the Evolution II and the Evolution X share the save cavity layout. Thelaser resonator contains the following components:

1 Nd:YLF curved high reflecting (HR) mirror. This forms one end of thelaser resonator.

2 AOM Q-switch; described below.

3 Diode laser pumped Nd:YLF laser chamber; described below.

4 45° intracavity dichroic folding mirror; a high reflector at 1053 nm;highly transmissive at 527 nm. This mirror serves to confine theNd:YLF fundamental wavelength in the cavity while emitting thegreen output beam.

5 LBO frequency-doubling crystal in a temperature-stabilized oven;described below.

6 Intracavity safety shutter.

7 Curved end mirror; a high reflector at both 1053 nm and 527 nm. Thismirror forms the other end of the laser resonator and directs frequency-doubled light back toward the dichroic output mirror.

8 Removable extracavity 527 nm mirror. When removed, it allows theoutput beam to exit through the side panel of the laser head.

Figure 3-2: Evolution Component Layout

Nd:YLF CurvedCavity HR Mirror

AOM Q-Switch Diode Laser-PumpedNd:YLF Laser Chamber

Dichroic Output Mirror 4

IntracavityShutter

LBO DoublingCrystal

HR Cavity Mirror1057 nm and 527 nm

Removable TurningMirror 527 nm

5

7

8

1 2 3 6

Laser Head Components

Laser Pump Chamber

The laser pump chamber contains the Nd:YLF laser rod and diode lasers.The chamber is mounted to the laser head by a mechanically indexedbracket that allows for easy extraction and insertion of the chamber. Thelaser rod is held in place with O-rings in a water flow tube that is sur-rounded by a gold coated reflector. Slits in the reflector transmit the pumplight from the diode lasers. Both the laser rod and diode lasers are watercooled in parallel by the internal cooling system that enters the pumpchamber through manifolds in the side of the chamber.

Each of the four high-power diode laser bars has its own water-cooled heat-sink, and each heatsink has its own electric heater for fine temperature con-trol. The diode laser bars are individually wired to separate channels of thediode laser driver using high-current connectors.

AOM Q-Switch

The AOM Q-switch is enclosed in a metal housing and is mounted on ariser block with a coarse azimuthal adjustment. The Q-switch is made of ahigh quality fused silica to which an RF transducer is bonded. The fusedsilica is cut and polished to be optically oriented at Brewster’s angle for“s” polarized intracavity laser radiation.

Approximately 40 to 50 watts of RF power are delivered to the Q-switchthrough a BNC cable. The Q-switch is water cooled and has a built-in tem-perature interlock to shut off the RF power if an over-temperature conditionoccurs. The power supply for the Q-switch is located in the Evolutionpower supply chassis.

LBO Crystal and Temperature Controller

The LBO crystal is located in an oven that maintains its temperaturebetween 315° and 340°F (set at the factory), to within 0.1°F. At this fac-tory-set temperature, the crystal is non-critically phase matched for con-verting the intracavity 1053 nm wavelength efficiently to the secondharmonic. The crystal should be constantly stabilized in this temperaturerange, even when the laser is not in use. If necessary, the crystal can beramped down to room temperature for long-term storage of the laser (seeChapter 6). The LBO crystal is anti-reflection coated for both 1053 nm and527 nm.

The temperature controller is a pre-programmed microprocessor-baseddevice. If the LBO temperature is not maintained to within ± 3°F of thefactory set point, an indicator lamp will come on and an interlock will pre-vent operation of the laser.


3-6

Power Supply Configuration

The power supply is a two-tiered assembly that resides inside a ruggedsteel frame. The power supply contains the master control board, diodelaser power supply, diode temperature controller, Q-switch RF driver, LBOcrystal temperature controller, control electronics and a DC power supply.In general, it should not be necessary to access any components inside thepower supply.

See Chapter 4 for a detailed description of the controls, connections, andindicator lights of the power supply.

The Controller

Operating the Evolution system is via the controller provided with the sys-tem and attached to the power supply at the 9-pin REMOTE connector.

See Chapter 4 for a detailed description of the controls, connections, andindicator lights of the controller.

Diode Laser Power Supply

The diode laser power supply is located on the lower level of the two-tierpower supply. It is a self-contained unit that is enclosed in a metal housingfor safety and to protect components during service. The power supply iscontrolled via the controller attached to it or, optionally, by means of soft-ware commands from a remote source attached to the RS-232 interface.

Diode Laser Temperature Controller

The temperature of the laser diodes must be regulated to ensure that theiremission wavelengths are tuned to the absorption band of the Nd:YLF rod.A 4-channel temperature controller is used in conjunction with heating ele-ments and temperature sensors in a closed-loop feedback system. Thisallows the diode laser temperatures to be stabilized independently for opti-mum output power.

Q-Switch Driver and Power Supply

The Q-switch driver provides RF power to the Q-switch in the laser head. Itis an all solid-state electronics device consisting of a crystal-controlledoscillator, double-balanced modulator, pulse generator with gate andbroadband power amplifier. It is packaged with its power supply, RFI linefilter and line switch.

Potentially lethal voltages and currents are contained in the power sup-ply. Removing the power supply cover will expose these hazards. Nor-mal operation of the Evolution should not require access to the powersupply circuitry. Contact an authorized service representative beforeattempting to correct any problem with the power supply.

Danger!

System Overview

3-7

The linear broadband RF power amplifier will provide >40 watts of powerinto a 50Ω load. The carrier LEVEL control adjusts the RF amplitude at theRF OUTPUT connector. The RF output port can withstand any mismatchcondition, whether it consists of a short, an open, or a complex load imped-ance.

An INTERLOCK input and a momentary switch with illuminated indicatorare provided. The INTERLOCK is connected by a cable to a normally-closedthermal switch mounted inside the Q-switch.

Access to the Q-switch driver is not required to operate the Evolution.

LBO Crystal Temperature Controller

The LBO doubling crystal is housed in a temperature-stabilized oven. Thiscrystal is temperature tuned for non-critical phase matching. A resistiveheating element combined with a local temperature sensor is used with theheater controller to stabilize the crystal temperature to within ± 0.1°F. Theheater controller is programmed to limit the rate at which the crystal tem-perature is changed (typically no faster than 10°F per minute) to preventcracking of the crystal anti-reflection coatings.

The power for the temperature controller is wired directly to the ac lines sothat the crystal is kept heated even when the front-panel circuit breaker isturned off. The LBO crystal temperature should be ramped down beforedisconnecting power to the chassis. See Chapter 6, “System Operation.” forinstructions.

Performance Specifications

The table below lists performance specifications for the Evolution II/Xlaser systems. The environmental specifications are listed in the front ofthis manual. Utility requirements and mechanical specifications are listedin Chapter 4, “System Installation.”

Table 3-1: Specifications, Evolution II/X

Output Characteristics1

1 Due to our continuous product improvement program, specifications may change with-out notice.

Evolution II Evolution X

Energy per Pulse 1 kHz5 kHz

6.0 mJ2.0 mJ

10 mJ3.0 mJ

Beam Diameter 3 mm (nominal)

Energy Stability2

2 Rms with near Gaussian distribution.

1% RMS

Polarization Linear, horizontal

Transverse Mode3

3 Optimized for pumping Ti:Sapphire amplifiers.

Mulitmode

Wavelength 527 nm

Repetition Rate 1 to 10 kHz


3-8

4-1

Chapter 4 Controls, Indicators and Connections

The Laser Head

There are no user controls on the laser head other than a means to fasten itin place. The OEM laser head has one forked foot centered on each endthrough which M6 or ¼-20 bolts fasten the laser to the table. The scientificlaser head has adjustable feet that screw up and down to set laser headheight, with foot clamps to fasten them in place.

The Power Supply

Power Supply, Front Panel

The panel shown in Figure 4-1 is described from left to right, top to bottomwithin the functional groups.

Figure 4-1: Power Supply Front Panel

Potentially lethal voltages and currents are contained in the power sup-ply. Removing the power supply cover will expose these hazards. Nor-mal operation of the Evolution should not require access to the powersupply circuitry. Contact an authorized service representative beforeattempting to correct any problem with the power supply.

Danger!

AC POWER ON

LASER ENABLE

INTERLOCK

ON

– USER– QS SYNC

– QS VAR SYNC

– QS TRIG

– REMOTE

– RS-232

– COVER

– DIODE TEMP

– XSTAL TEMP

– TEMP SENSOR

– FLOW

– PS ERROR

– DIODE ERROR

HOURS

I 0

8888888


4-2

HOURS meter—(non-resetting) records the total time the laser is on.

REMOTE connector (15-pin female D-sub)—provides attachment for thetable-top controller.

RS232 connector (9-pin male D-sub)—provides attachment for a com-puter for remote control of the laser.

QS SYNC connector—provides a fixed TTL synchronization signal that iscoincident with the triggering of the Q-switch.

QS VAR SYNC connector—provides a synchronization signal that may beadjusted ±1 µs relative to the Q-switch trigger time, thus providing a pre- orpost-trigger signal.

QS TRIG connector—can be used to trigger the Q-switch externally byapplying a TTL signal that is capable of driving a 50 Ω load. External trig-gering from 10 Hz to 10 kHz is possible. To use this mode, select the EXTtrigger mode on the controller.

Interlock indicator display—is a bank of lights that show the status ofvarious interlock functions. If any interlock function is tripped, the corre-sponding will illuminate on the Remote Control Box, and the appropriatered LED will illuminate on the chassis front panel. Interlocks may becleared only after the fault has been corrected and the keyswitch has beencycled. The various interlocks are described below:

USER—turns on whenever the contacts of the interlock connector arenot shorted.

COVER— turns on whenever the laser head cover is removed.

DIODE TEMP— turns on whenever the temperature(s) of the diodelasers drift more than 15°F from the values stored in the controller.

XSTAL TEMP—turns on whenever the LBO crystal temperature driftsmore than ±3°F from the factory-set value stored in the power supply.

TEMP SENSOR—turns on when any of the thermocouples that monitorthe diode laser temperatures fail.

FLOW—turns on whenever coolant flow drops below 0.5 gpm. Flow ismeasured by a flow switch inside the Evolution laser head.

PS ERROR—turns on if the diode laser power supply has an electricalfault.

DIODE ERROR—turns on whenever an over-voltage (compliance) orshort circuit problem is detected in the diode laser power supply.

LASER ENABLE indicator (red)—when on, indicates that all interlocksare cleared and that the laser emission is present or imminent (once the“on” command is given).

LASER ENABLE keyswitch—is an interlock that prevents operation of thelaser when the switch is turned off and the key is removed. The key can beremoved only when the switch is in the off position. If an interlock is setdue to a fault (and the system shuts off), once the fault is corrected, turningthe keyswitch off then back on resets the interlock so that the laser canresume operation.

Controls, Indicators and Connections

4-3

INTERLOCKconnector—provides the user with an external interlock thatshuts down the laser diodes when the circuit is opened (Figure 4-2). It mayalso be used to connect several different interlock switches in series (suchas an external flow interlock, if supplied). If this NOT to be used, the jum-pered connector must be attached.

Figure 4-2: Interlock Connector Wiring

AC POWER ON indicator (red)—turns on when ac power is applied to thesystem.

AC power switch—applies ac line power to the power supply.

Power Supply, Rear Panel

Figure 4-3: Power Supply Rear Panel

F1, F2—provide safety fusing for the chassis. Table 4-1 lists the fuse speci-fications.

AC IN—provides connection for a power cord that attaches to facility linepower. AC power must be in the range 100 to 240 Vac ±10%, 50/60 Hz.

Table 4-1: Evolution Fuse Specifications

Line Voltage / VAC F1/F2: 3AG SLO BLO

200–240100–120

10A/10A15A/15A

INTERLOCK

AC power to the LBO crystal heater circuit in the power supply isalways present, even when the ac power switch on the front panel isturned off.

Danger!

F1 F2

AC IN


4-4

The Evolution Controller

The Evolution controller shown in Figure 4-4 allows the user to operate theEvolution within a distance of about 10 feet (3 meters) of the laser. Thecontrol cable exits the right side of the controller and attaches to theREMOTE connector on the front the power supply. The controls aredescribed in detail below from left to right, top to bottom. System operationis described in Chapter 6.

Figure 4-4: The Controller Front Panel

Main Functions

Up/Down buttons—provide a means to scroll up and down to view infor-mation on the screen to the right.

Menu display—shows various Set or Info menus.

LASER ON/OFF switch—turns the laser on and off. For safety, this switchmust be held down for 5 seconds to activate the laser. Pressing this switchwhile the laser is running closes the intracavity shutter and ramps down thediode laser currents (turns off the laser).

EMISSION indicator (green)—turns on after the LASER ON/OFF button hasbeen pressed for 5 seconds to indicate laser emission is present or immi-nent. The intracavity shutter will also open at this time.

This power supply is not auto-switching, and must only be operated atthe ac input voltage for which it was configured at the factory.

Warning!

Note that the laser head is permanently attached to the rear of the powersupply chassis via a 10-foot long (3-meter) umbilical that contains fourcables: a 4-pin high-current cable, a 26-pin signal cable, and two BNCcables that attach to the RF OUT and INTERLOCK connectors on the frontof the power supply.

Note

Q-SWITCHkHz

FREQVARSYNCEXT

OFF

INT

LASERON/OFF

EMISSION

INTERLOCKS

W

POWER

Controls, Indicators and Connections

4-5

INTERLOCK indicator (red)—turns on if any interlock circuit is tripped oropened. Inspect the bank of interlock LEDs on the power supply frontpanel to find out which interlock function(s) have tripped.

POWER display—shows diode laser pump power in Watts.

POWER dial—allows the user to set the percentage of full diode laserpower from 0 to 100%. This can be pre-selected before activating the diodelasers or adjusted while the Evolution is running.

Controller Q-Switch Functions

EXT/OFF/INT mode selector—provides a means to select the Q-switch trig-ger input. The EXT setting allows the laser repetition rate to be controlledby an external trigger source. The OFF position prevents laser action byleaving the AOM on constantly, i.e., the AOM does not function as a Q-switch but rather as a loss element within the cavity that prevents intracav-ity laser light from being generated. The INT setting activates the internallytriggered mode where the laser will Q-switch at the repetition rate dis-played on the Q-SWITCH: FREQ display.

Switching positions while the laser is running will cause the intracavityshutter to close and the diode lasers to ramp down (turn off). The Q-switchwill then activate according to the new setting and the diode lasers willramp back to the original set point. This feature prevents large initial Q-switching transients that can cause optical damage.

VAR SYNC control—sets the timing for a TTL synchronization signal rela-tive to the Q-switch trigger time ±1 µs, providing a pre- or post-trigger sig-nal. Normal control changes the timing in small steps; depressing this knobwhile turning it changes the timing in large steps.

This synchronization signal is accessed via the QS VAR SYNC BNC connec-tor on the power supply. When the LBO temperature is displayed in themain window, this knob adjusts the LBO crystal temperature.

FREQ dial—provides a means to select the Q-switch repetition rate from0.010 to 9.999 kHz, which is displayed in the window to the right of it.

Q-SWITCH FREQ display—indicates the internal Q-switch frequency set-ting (in kHz) when the mode selector switch is set to INT or OFF. When theswitch is set to EXT, the display is blank.

The Evolution Chiller

Various chillers are supplied with the Evolution laser system. For a descrip-tion of the chiller, refer to the chiller manual shipped with the system.


4-6

5-1

Chapter 5 Preparing for System Installation

Installation of the Evolution system must be performed by an authorizedSpectra-Physics representative. Please read this section thoroughly before-hand to prepare your site for installation.

Please call your authorized service representative to arrange an installationappointment, which is included as part of your purchase agreement. Youmay, however, unpack the laser and locate it in the area where it will beused. Refer to the instructions near the beginning of this manual.

Location

Select a suitable location for the Evolution before the service technicianarrives. It is recommended the laser be located in a laboratory type environ-ment that is free from dust and drafts, has low humidity (<50%), and doesnot undergo temperature fluctuations of greater than ± 5ºC.

Pumping a Spitfire Amplifier

If used to pump a Spitfire amplifier, the Evolution should be placed rela-tively close to the Spitfire. The optimal distance between the two units isdetermined at the factory during the final test procedure. Deviations ofgreater than 6 inches from this distance can affect the overall performanceof the system. Also, for safety, do not allow an exposed laser beam to travela long distance. Consult with your service representative if necessary.

Required Utilities

Do not attempt to install the laser yourself or remove the cover that sealsthe laser cavity. Either action, if unauthorized, will void your warranty,and you will be charged to repair any damage that may result.

Warning!

Do not apply ac power to the power supply chassis at this time. Doing sowill activate the LBO crystal heater. Improper programming of the crys-tal heater and subsequent crystal heating will permanently damage thecrystal, and such damage will not be covered under the warranty. Again,installation of the Evolution laser should be performed only by a Spec-tra-Physics representative.

Warning!


5-2

Installing the Controller

A controller is supplied to operate the Evolution. Alternatively, the systemcan be controlled by means of RS-232 commands from a remote computeror terminal, either using your own software or an optional LabVIEW® pro-gram available from Spectra-Physics.

The cable for the controller plugs into the 9-pin socket marked REMOTE onthe front panel of the Evolution power supply. If you choose to operate thelaser remotely via RS-232 commands, attach your computer or terminal tothe Evolution 9-pin RS-232 connector on the front panel of the power sup-ply using a 9-wire serial cable. Make sure that the fastening screws on allcontrol cables are tightened to prevent the plug(s) from disengaging.

Please refer to Appendix B for instructions on how to use RS-232 program-ming commands.

Preparing to Install the Power Supply

• The power supply must be placed within 10 ft (3 m) of the laser headto avoid straining the umbilical.

• For proper airflow, allow 6 in. (15 cm) of clearance to the front andback panels of the power supply cabinet and 3 in. (8 cm) on each side.

• Take measures to prevent the heated air exhaust from the back panelfans from returning to the intake on the sides of the power supply, orfrom flowing toward the laser head. Failure to do so may cause over-heating in the power supply and instability in the laser output.

• Verify that the interlock jumper plug is in place on the front panel ofthe power supply. If you intend to use the laser in a limited access area,remove the jumper in the plug and wire the plug to a safety switch sothat when the device is activated (for example, a door is opened) theswitch opens and turns off the laser (see Chapter 2).

Table 5-1: Utility Requirement for the Evolution

Destination Acceptable Line Voltage/ Frequency (Vac/Hz)

Current Requirements (A)

Laser Chiller

USA 110 ±10 Vac, 60 Hz 15 15

Japan 110 ±10 Vac, 50/60 Hz 15 15

or* 220 ±20 Vac, 50 Hz 10 10

Europe 220 ±20 Vac, 50 Hz 10 10

* The Evolution cannot operate interchangeably between 110 and 220Vac line voltage. The laser and chiller are configured at the factory tooperate with the customer-specified line voltage and frequency. Do notattempt to operate the chiller at a different voltage or frequency underany circumstances.

Warning!

Preparing for System Installation

5-3

• Verify the local line frequency and voltage are within the acceptableinput ranges for the Evolution and the chiller as ordered.

• Ensure that the umbilical and all electrical cables can be safely routedand are without strain or compression.

• Verify the power cable is screwed tightly into the ac connector on thepower supply chassis.

Preparing to Install the Laser Head

Secure the laser head on an optical table or other flat mounting surfaceas follows:

OEM Evolution:

Two slots are provided at the center of the front and back of the laserhousing for securing the laser head to the table using standard tablescrews (M6 or ¼-20).

The arm at the front of the laser that allows for thermal expansion orcontraction of the housing is bolted in place last. Secure the back armfirst. Securing the front arm first will defeat its purpose.

Scientific Evolution:Place the laser head on the table and adjust the four mounting feet tothe correct height, making sure that the laser head is level. The heightof the feet can be locked using the locking ring on each leg. Secure thelaser head to the table using a mounting clamp (supplied) on each foot.

Preparing to Install the Chiller

The following requirements should be considered to prepare for the chillerinstallation:

• Verify that the local line frequency and voltage are within the accept-able input ranges for the chiller.

• The chiller will be located on the floor close enough to the Evolution that the cooling hoses will reach without strain.

• Do not be place the chiller above the laser or power supply. If a leakdeveloped in the chiller, dripping water could damage a unit below it.

Take care that the weight of the umbilical cable does not drag the laserhead off the table.

Warning!

The chiller must be located so that warm air exhaust from its back panelis not drawn into the laser power supply, which could affect the stabilityof the laser. Allow 6 in. (15 cm) of clearance between the chiller and theEvolution power supply to prevent hot air from one unit being drawninto the other.

Caution!


5-4

• The hose connectors are attached so that the feed line (marked with anarrow pointing toward the laser head) is attached to the lower hoseconnector on the laser head. This will ensure that any air is purgedupward and out of the laser head. (Connecting the chiller hoses inreverse would trip a flow interlock.)

Refer to Appendix A, “Optishield Additive,” for instructions on filling thechiller for first time use.

Mechanical Specifications

Figure 5-1: Evolution Scientific Laser Head Outline Drawing

Table 5-2: Component Weights

Component Weight

Laser Head, Scientific 35.2 lb (16.0 kg)

Laser Head, OEM 28.6 lb (13.0 kg)

Power Supply 99.0 lb (45.0 kg)

Controller 1.76 lb (0.8 kg)

Chiller (dry, typical) 97.0 lb (44.0 kg)

Before handling the Optishield water treatment chemical, read the Mate-rial Safety Data Sheet included in Appendix A that describes the poten-tial hazards and handling precautions associated with this chemical.This chemical can be harmful if swallowed, inhaled or absorbed throughthe skin or eyes. Instructions for adding the Optishield treatment aregiven in this appendix as well.

Danger!

Use only steam-distilled water in the Evolution cooling system. Theuse of de-ionized water may cause corrosion damage.

Caution!

19.25489,0

0.6516,5

3.7294,5

inchesmm

11.62295,1

3.94100,1

4.88124,0

3.2382,0

6.20157,5

7.14181,4

2.3860,3

9.00228,6

1.3133,3

13.00330,2

Dimensions in

Preparing for System Installation

5-5

Figure 5-2: Evolution OEM Laser Head Outline Drawing

Figure 5-3: Evolution Power Supply and Controller Outline Drawings

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MANUFACTURED:

MONTH

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YEAR

S/N


MADE IN U.S.A.



0420-7840

3.5790,7

5.43138,0

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AC POWER ON

LASER ENABLE

ON

– USER– QS SYNC

– QS VAR SYNC

– QS TRIG

– REMOTE

– RE-232

– COVER

– DIODE TEMP

– XSTAL TEMP

– TEMP SENSOR

– FLOW

– PS ERROR

– DIODE ERROR

HOURS

Power Supply

Controller

Q-SWITCHkHz

FREQVARSYNCEXT

OFF

INT

LASERON/OFF

EMISSION

INTERLOCKS

W

POWER

All dimensions in inches

mm


5-6

A number of manufacturers produce chillers that are suitable for use withthe Evolution laser system. Consult the chiller manual included with thesystem for specifics about your chiller.

6-1

Chapter 6 System Operation

Overview

The Evolution is typically operated via the Evolution controller, which con-trols the laser head and power supply. Familiarize yourself with the detailsof operation given below before proceeding to the start-up procedures.

Electrical Current Settings

Your Evolution laser comes with a set of performance data that shows thefactory-measured output power as a function of diode laser current at thenominal Q-switch repetition rate that was specified when the laser wasordered. Your authorized service representative will verify these measure-ments when the laser is installed.

It is useful to establish at least three nominal current settings for low,medium and high output (for example, 30, 50 and 100% of rated output) ata standard 1 kHz setting. If you will not normally be operating the Evolu-tion at its maximum specified output power, scale these settings appropri-ately when following the procedures in this chapter or when following anytroubleshooting procedures.

After several hundred hours of operation, the diode laser output power willdecrease slightly. This is the normal “burn-in” cycle. The maximum possi-ble current is set at the factory to ensure that your laser will meet its speci-fication power for thousands of hours of operation.

Safety glasses covering all lasing wavelengths must be worn at all timeswhen operating this laser system. Consult your laser safety officer toselect appropriate safety glasses. You MUST read Chapter 2, “LaserSafety,” before using the laser the first time.

Refer to Appendix B for instructions on operating the Evolution usingthe RS-232 interface.

Note

The following procedures will result in laser beam emission from theEvolution output port. Ensure that all persons in the room are wearingadequate eye protection. Ensure that the anticipated beam is safely ter-minated into a high power beam block or power meter.



6-2

Startup Procedure

The following procedures should be used during normal startup and opera-tion of the Evolution laser system.

1. Turn on the chiller (refer to the chiller manual).

2. If the Evolution controller has been disconnected, connect the cable ofthe controller to the connector labeled REMOTE on the front panel ofthe power supply.

3. Set the main power switch on the power supply to the ON position.

4. Insert the key switch and turn to the ON position.

The display of the controller will read “Warming Up” as the diodelasers are heated to their operating temperatures. During this warm-upperiod, the laser cannot be started.

After the diode lasers have reached operating temperature, the displaywill read “Standby Mode”. If the red INTERLOCKS LED on the con-troller is illuminated, check the front panel to determine what inter-locks are latched. Occasionally, the DIODE TEMPERATURE interlockwill be latched during warm-up. To clear latched interlocks, turn thekey switch from ON to OFF and back to ON. An interlock will not clearif the condition causing the interlock has not been fixed. See the trouble-shooting guide for assistance in clearing the interlocks.

When all interlocks are cleared, the red interlock LEDs will be off onboth the power supply and controller.

5. Set the power level on the controller to the value chosen for low power(e.g. 30%) with the large POWER knob.

6. If the Evolution is to be internally Q-switched, set the Q-switch fre-quency to the desired repetition rate (e.g. 1.000 kHz) with the FREQknob on the controller, and set the Q-switch rocker switch to INT.

7. If the Evolution is to be externally Q-switched:

a. Connect a TTL-level signal (at least 1 µs duration) at the desiredfrequency to the QS TRIG connector on the power supply frontpanel. The QS TRIG input is terminated into 50 Ω.

b. Set the Q-switch rocker switch to EXT. Q-switch operation is syn-chronized to the rising edge of the input pulse.

8. Rotate the Evolution output shutter open on the front or side (depend-ing on which port is being used). Ensure that the laser output will bedirected into an appropriate termination (e.g., a beam dump, powermeter, Spitfire, etc.).

9. Press and hold the LASER ON/OFF button for 5 seconds until you hearthe internal shutter open and the green EMISSION LED on the control-

Your Evolution was optimized at a specific Q-switch repetition rate.Operating the laser at a significantly different rate may result indecreased performance or damage to the instrument.

Caution!

System Operation

6-3

ler illuminate. The controller will display “Setpoint = x” (the percent-age of maximum diode power).

After 5 seconds, the laser will turn on rapidly and emit laser output atlow power. Measure the output power with a meter capable of measur-ing 10 watts maximum. Within several minutes, 527 nm power shouldbe the same as, or close to, the power that was previously measured forthe low setting.

10. Increase power to the medium setting, followed by the high setting,and verify the power is the same as, or close to, the previous valuesselected for medium and high settings.

At 100% power, output power should be at least 6 W for the Evolution IIor 10 W for the Evolution X, at a 1 kHz Q-switch repetition rate. Ifpower is low, wait 10 to 20 minutes for the chiller to stabilize the lasertemperature. If the beam does not reach operating power, it may benecessary to optimize the lasing output as described in Chapter 7,“Maintenance.”

If the laser is used frequently, leaving the chiller on between periods ofuse will eliminate this stabilization period. If the laser is used infre-quently, turn the chiller off between periods of use.

Shutdown Procedure

1. Press the LASER ON/OFF button on the controller. The shutter willclose and the diodes will shut off immediately.

2. Turn the main keyswitch to OFF.

3. Remove the key from the keyswitch.

4. Turn off the main power switch.

5. Turn off the chiller if the system is used infrequently.

Long Term Shutdown

If the Evolution will be disconnected from line voltage for an extendedperiod of time (greater than a few minutes), the LBO crystal temperaturemust slowly be ramped down to room temperature to avoid thermal shockto the crystal. Use the following procedure to ramp down the crystal tem-perature:

1. With the power supply turned on, scroll to the LBO temperature menuon the controller. Use the VAR SYNC knob to change the setpoint to itslowest setting (3°F below the factory-set temperature).

2. Continue turning the VAR SYNC knob counter-clockwise for severalturns until the USER temperature reads 75.0°F.

3. Allow the crystal temperature to ramp down until it reaches 75°F.

4. Turn off the Evolution power supply and disconnect the power cord.

5. To return the Evolution to normal operation, plug in power cord to thepower supply and turn on the supply. The LBO crystal temperaturewill automatically ramp up to the factory-set temperature, at whichpoint the laser can be operated normally.


6-4

7-1

Chapter 7 Maintenance

The Evolution has been designed for minimal maintenance. The routineprocedures described in this chapter are recommended to keep the systemin good working condition. For further information, contact your Spectra-Physics service representative.

Lasing Optimization

Cavity Mirror Adjustments

All of the optical mounts in the Evolution are securely fastened to the rigidbase plate of the laser head, which is temperature stabilized. Nevertheless,the mirrors may become slightly misaligned due to changes in room tem-perature, bumps or other stresses on the laser head. If this happens, the endmirrors of the laser cavity may require adjustment.

Use the following procedure to optimize the cavity mirrors:

Materials required:

• Laser safety goggles• Infrared (IR) viewer or card• Two 1/8-inch ball-tipped Allen wrenches (one of which is >8 in. long)• A calibrated power meter capable of measuring at least 10 W (20 W

for the Evolution X)

Procedure:

1. If the Evolution is lasing, stop the output by pressing the LASER ON/OFF button on the controller. It is not necessary to turn off power to thepower supply.

Improper adjustment of the Evolution laser can result in damage to thelaser rod, LBO crystal or Q-switch. Do not attempt to adjust the Evolu-tion mirrors until you have read this section. If you are uncertain aboutthis procedure, contact your service representative for assistance.

Warning!

Protective eyewear MUST be worn for protection from all wavelengthsemitted by the Evolution. Refer to Chapter 2, “Laser Safety.”

EyewearRequired


7-2

2. [Scientific Evolution only]: lift the sheet metal cover from the laserhead.

3. [Scientific Evolution only]: locate the two or four interlock by-passplates (similar to those shown in Figure 7-1) that are screwed into theirparking positions and use them to lock down the cover interlockswitches by screwing them into place to hold down the switch lever.This defeats the switches and allows the laser to be operated with thesheet metal cover removed. Reverse this procedure and replace thecover as soon as the optimization procedure has been completed.

Figure 7-1: Interlock by-pass plates shown “parked” inside the rear ofthe laser head.

Figure 7-2: Interlock switch and by-pass plate mounting position.

By-pass Platesin Parking Position

Interlock Switch (typical)

Rear Panel

By-pass PlateMounting Position

Maintenance

7-3

4. Cycle the power supply keyswitch off and on to clear the cover inter-lock circuit.

5. Place the power meter at the Evolution output.

6. Set the Q-switch to INT and the QSW frequency to 1.000 kHz.

7. Start the laser at low power, allow the power to stabilize, and makenote of the stable power level.

8. Verify that the power meter reads 1.0 watt or less. (Use the controllerto slowly turn down the power if necessary. It may be useful to changethe power meter to a more sensitive scale.) Allow the power to stabi-lize and make note of the stable power level shown on the meter andthe pump power setting on the controller.

9. Remove the setscrews covering the mirror adjustment ports (two areon the rear end-plate of the laser), and put the screws in a safe place.

10. Using the hex wrenches, carefully adjust the vertical screw of each endmirror while monitoring output power. Make very small adjustments(< ½ turn total travel on each mirror), alternating between the two mir-rors in order to “walk” the mode in the cavity. Use this process to max-imize output power, then note the maximum stable power obtained.

11. Using the same procedure, carefully adjust the horizontal screws whilemonitoring the power. Again, make very small adjustments (< ½ turntotal travel on each mirror), alternating between the two mirrors inorder to “walk” the mode in the cavity. Use this process to maximizeoutput power, then note the maximum stable power obtained.

12. Set the Q-switch selector to OFF. This will initiate the following auto-matic sequence of events that will take about 15 seconds to complete:

• laser diodes will turn off• shutter will close• Q-switch trigger generation will stop• shutter will open• diodes will turn on

13. At the end of the previous step, there should be no laser output. Checkfor visible laser output. Also check for IR output with an IR viewer orcard. Set the power meter to its most sensitive reading and start theEvolution to ensure there is no visible or invisible laser output. If thereis any output, stop, turn off the laser, and contact your service repre-sentative for assistance.

14. Slowly turn the laser current back up to 100% while monitoring thelaser power. The power level should remain at zero as the currentramps all the way up to 100%. As in the previous step, verify that thereis no visible or infrared output, and if any is detected, stop, turn offthe laser, and contact your service representative for assistance.

15. If no lasing was measured in the preceding steps, turn down the laserpower to the level at which the mirrors were optimized.


7-4

LBO Crystal Temperature Optimization

Depending on environmental conditions, the optimum temperature of theLBO crystal for efficient intracavity doubling may vary from the factorysetpoint. You may vary the LBO crystal temperature by ±1.5°F around thefactory-set temperature to compensate for environmental effects.

To optimize the LBO temperature, do the following:

1. Turn on the laser and monitor output power with a power meter.

2. Scroll to the LBO temperature menu by pressing the down button onthe controller.

3. Note the current USER temperature setting.

4. Use the VAR SYNC knob to change the USER setpoint. The USER set-point is stored through power cycles.

5. When output power is maximized, make a note of the temperature set-ting for future reference.

If at any time while optimizing the LBO temperature at the medium cur-rent setting, the Evolution output power drops by more than 20%, turnoff the laser immediately. (Optical damage could occur if the LBOtemperature is severely detuned and insufficient second harmonic lightis coupled out of the optical resonator.) Perform the optimization proce-dure described below. If you are uncertain about this procedure, contactyour authorized Spectra-Physics service representative for assistance.

Warning!

If you change the LBO USER setpoint to a value more than 3° higher orlower than the temperature reading, the CRYSTAL TEMPERATURE inter-lock will trip and the laser will shut off. The laser can be restarted afterresetting the interlocks and waiting for the LBO crystal temperature toreturn to within 1° of the setpoint.

Note

If you adjust the LBO USER setpoint to its minimum value and continueto turn the VAR SYNC knob, you may put the crystal into ramp-downmode (75°F). If this occurs, cycle the power on the power supply off andon to reset the factory temperature.

Note

Maintenance

7-5

Cleaning the Optics

The Evolution is sealed against dust and debris but, depending on the clean-liness of the environment, it is possible that some dust may get into thelaser head. If this happens, clean the optics.

Materials required

• Safety goggles• Clean plastic gloves or finger cots• Scientific-grade lens-cleaning tissue (Kodak brand or equivalent quality)• Reagent-grade methanol or acetone• Eye dropper• Hemostat (surgical pliers)• English hex-wrench set• Bright lamp or flashlight

Accessing the Evolution optics

1. Turn off the Evolution power supply.

2. [Scientific Evolution only]: remove the external sheet metal cover.

Cleaning the optics requires opening the optical cavity. This procedureshould not be executed without prior approval of your authorized ser-vice representative. Unauthorized opening will void your warranty andmight damage your laser.

Warning!

The Evolution is assembled with chemically-cleaned parts. To preventcontamination, wear plastic gloves or finger cots while working insidethe housing.

Warning!

Cleaning the optics may result in misalignment of the laser cavity. Aftercleaning, the cavity should be realigned using the procedures under“Lasing Optimization” earlier in this chapter.

Caution!

The LBO crystal is kept above 320°F (160°C). Prolonged contact withthe LBO crystal housing can burn skin, melt plastic and ignite flamma-ble material.

Danger!

Never attempt to clean the LBO crystal or the Nd:YLF laser rod in thissystem. Optical damage will occur and your warranty will be voided ifyou have tampered with either of these two optics. If you feel that opti-cal damage has occurred or cleaning of these optics is necessary, contactyour authorized Spectra-Physics service representative.

Warning!


7-6

3. Remove the screws holding the machined metal cover in place. Put thescrews in a safe place.

4. Remove the machined cover and place it on a clean surface.

Mirrors

Mirrors should be carefully cleaned with soft optical tissue and reagentgrade methanol or acetone as described below.

1. Wear clean finger cots or gloves.

2. Fold a piece of lens tissue repeatedly to form a pad approximately1 cm wide.

3. Hold the pad with the hemostat so that about 3 mm of the folded edgeprotrudes from the hemostat blades.

4. Saturate the pad with methanol or acetone and shake to remove excesssolvent.

5. Reach slightly below the center of the optic and, in a single motion,wipe the surface of the optic toward the outside. Be careful the hemo-stat blades do not scratch the optic.

6. If cleaning the intracavity dichroic mirror, repeat Step 5 with a cleantissue on the other optic surface.

Q-switch

The Q-switch can be difficult to clean; attempt to clean it only if dust ordebris are clearly visible. When cleaning the Q-switch crystal faces, it isnecessary to remove the U-shaped cover around the Q-switch in order togain unobstructed access to the quartz faces. Do not touch the transducerconnections.

Routine Maintenance, Cooling Water

To prevent metal corrosion and the growth of algae in the closed-loop cool-ing water system of the Evolution, the use of Optishield corrosion inhibitoris recommended. This chemical treatment prevents galvanic corrosion fromdissimilar metals, prevents oxidation of ferrous metals, and acts as an effec-tive algaecide. The first application of Optishield is normally performed atthe factory. Thereafter, the Optishield solution should be changed once ayear, according to the procedures in Appendix A.

Before handling Optishield water treatment chemical, read the MaterialSafety Data Sheet included in Appendix A, which describes the poten-tial hazards and handling precautions associated with this chemical.This chemical can be harmful if swallowed, inhaled or absorbed throughthe skin or eyes.

Danger!


Caution!

8-1

Chapter 8 Troubleshooting

Troubleshooting Guide

This general purpose troubleshooting guide is provided to assist you in iso-lating some of the problems that might arise during use of the Evolution,for example if performance drops unexpectedly. A complete repair proce-dure is beyond the scope of this manual, and should be addressed by yourauthorized Spectra-Physics service representative.

Symptom: Laser will not start

Symptom: Emission light comes on, but no output

Possible Cause: Corrective Action:

No ac power Check whether red AC POWER LED is lit. If not, verify that the circuitbreaker on the front of the power supply is in the correct position; verifythat the power cord at the rear of the supply is tightly fastened to the chas-sis; check fuses F1 and F2.

Interlocks are not closed Check the interlock display on the power supply. If there are interlock LEDsare on, turn the keyswitch off and on to clear the latched interlocks. Inves-tigate any interlocks that are not cleared by this action. For example, verifythat the chiller is turned on and that the hoses are not constricted; verifythe cover is on; verify the user interlock plug is in place, etc. Refer to Chap-ter 2, “Laser Safety,” for more information on interlocks.

Keyswitch is not in ON position Turn the keyswitch to the ON position (vertical). The key cannot be removedwhen it is in this position.


Output shutter is closed If the front port is being used, rotate the shutter open. If the side port isbeing used, verify the black disc has been removed.

Q-switch is set to OFF or EXT Check the Q-switch setting on the controller. If using an external Q-switchfrequency source, verify the signal level is at least 2 V into 50 Ω.

Chiller is turned on after the power supply

The diode driver will not turn on until both the chiller and power supply havebeen turned on. If the chiller is turned on after power supply, the diodedriver may not respond to commands from the controller. With the chilleron, turn the power supply off and then on again.

Cavity optics are out of align-ment.

If the cavity optics are so far out of alignment that the laser will not start,contact your authorized service representative.


8-2

Symptom: Variations in output power

Symptom: Power is below specification


LBO crystal temperature has drifted

Check the output power across the tuning range of the LBO crystal for thehighest output power as described in Chapter 7, “Maintenance.”

Water temperature varies Verify the water chiller temperature is adjusted to the temperature that wasset when it was installed (typically in the range of 18 to 27°C).

Cavity optics are out of align-ment

Adjusting the cavity mirrors slightly may optimize output power. Read thedetailed instructions in Chapter 7, “Maintenance,” before attempting toadjust the mirrors.

Optics are dirty Inspect the optics for dirt or contamination. If dirty, clean them as describedin Chapter 7, “Maintenance.”

Q-switch breakthrough With the laser at 100% output power, turn the Q-switch mode selector to theOFF position and turn the laser on. Using an infrared viewer or card, verifythere is no infrared and/or visible output beam from the laser. If there is anoutput beam, then the Q-switch is malfunctioning or misaligned. Contactyour authorized service representative.


Diode current is set too low With the laser at 100% output power (80 W on the LED display), use apower meter to verify output power at 1 kHz Q-switch frequency is at least6 W (10 W for Evolution X).

Q-switch frequency is set higher or lower than 1 kHz

Power output depends on Q-switch frequency. If the Evolution is operated ata Q-switch frequency different than that specified when the system wasordered, contact Spectra-Physics to get the power specification at the newfrequency.

Cavity optics are out of align-ment

Adjusting the cavity mirrors slightly may optimize the output power. Read thedetailed instructions in Chapter 7, “Maintenance,” before attempting toadjust the mirrors.

LBO crystal temperature has drifted

At low pump power, check output power across the 4-degree tuning range ofthe LBO crystal for the highest output power.

There is algae growth in the cooling water

Follow the maintenance procedure in Chapter 7, “Maintenance.”

Diode laser power is low After several thousand hours of operation, the optical power of the diodelasers decreases and the current to the diodes must be increased to com-pensate. Contact your service representative if you have questions.

Troubleshooting

8-3

Symptom: Laser does not emit Q-switched or CW output

Customer Service

At Spectra-Physics, we take great pride in the reliability of our products.Considerable emphasis has been placed on controlled manufacturing meth-ods and quality control throughout the manufacturing process. Neverthe-less, even the finest precision instruments will need occasional service. Wefeel our instruments have excellent service records compared to competi-tive products, and we hope to demonstrate, in the long run, that we provideexcellent service to our customers in two ways: first by providing the bestequipment for the money, and second, by offering service facilities that getyour instrument repaired and back to you as soon as possible.

Spectra-Physics maintains major service centers in the United States,Europe, and Japan. Additionally, there are field service offices in majorUnited States cities. When calling for service inside the United States, dialour toll free number: 1 (800) 456-2552. To phone for service in other coun-tries, refer to the “Service Centers” listing located at the end of this section.

Order replacement parts directly from Spectra-Physics. For ordering orshipping instructions, or for assistance of any kind, contact your nearestsales office or service center. You will need your instrument model andserial numbers available when you call. Service data or shipping instruc-tions will be promptly supplied.

To order optional items or other system components, or for general salesassistance, dial 1 (800) SPL-LASER in the United States, or 1 (650) 961-2550 from anywhere else.

Warranty

All parts and assemblies manufactured by Spectra-Physics are uncondition-ally warranted to be free of defects in workmanship and materials for theperiod of time listed in the sales contract following delivery of the equip-ment to the F.O.B. point.

Liability under this warranty is limited to repairing, replacing, or givingcredit for the purchase price of any equipment that proves defective duringthe warranty period, provided prior authorization for such return has been


External Q-switch input is not valid

If an external Q-switch signal is being used, verify the signal is at least 2 Vinto a 50 Ω load, and at least 1 µs wide; also verify the frequency is actu-ally set to the desired value (between 1–10 kHz).

Q-switch driver is turned off or has tripped off

Removing the power supply cover willexpose the user to potentially lethal volt-ages and currents. See Chapter 2, “LaserSafety.”

Slide back the top cover of the power supply to see if the green interlocklight on the front panel of the Q-switch driver is on. If not, verify the coolingwater is turned on and that the thermal interlock cable is connected to theQ-switch in the laser head. Cycle the power off and on to reset the Q-switch thermal interlock.

Danger!


8-4

given by an authorized representative of Spectra-Physics. Spectra-Physicswill provide at its expense all parts and labor and one-way return shippingof the defective part or instrument (if required). In-warranty repaired orreplaced equipment is warranted only for the remaining portion of the orig-inal warranty period applicable to the repaired or replaced equipment.

This warranty does not apply to any instrument or component not manufac-tured by Spectra-Physics. When products manufactured by others areincluded in Spectra-Physics equipment, the original manufacturer's war-ranty is extended to Spectra-Physics customers. When products manufac-tured by others are used in conjunction with Spectra-Physics equipment,this warranty is extended only to the equipment manufactured by Spectra-Physics.

This warranty also does not apply to equipment or components that, uponinspection by Spectra-Physics, discloses to be defective or unworkable dueto abuse, mishandling, misuse, alteration, negligence, improper installa-tion, unauthorized modification, damage in transit, or other causes beyondthe control of Spectra-Physics.

This warranty is in lieu of all other warranties, expressed or implied, anddoes not cover incidental or consequential loss.

The above warranty is valid for units purchased and used in the UnitedStates only. Products shipped outside the United States are subject to a war-ranty surcharge.

Return of the Instrument for Repair

Contact your nearest Spectra-Physics field sales office, service center, orlocal distributor for shipping instructions or an on-site service appointment.You are responsible for one-way shipment of the defective part or instru-ment to Spectra-Physics.

We encourage you to use the original packing boxes to secure instrumentsduring shipment. If shipping boxes have been lost or destroyed, we recom-mend that you order new ones. We can return instruments only in Spectra-Physics containers.

Troubleshooting

8-5

Service Centers

Benelux

Telephone: (31) 40 265 99 59

France

Telephone: (33) 1-69 18 63 10

Germany and Export Countries1

Spectra-Physics GmbHGuerickeweg 7D-64291 DarmstadtTelephone: (49) 06151 708-0Fax: (49) 06151 79102

Japan (East)

Spectra-Physics KKEast Regional OfficeDaiwa-Nakameguro Building4-6-1 NakameguroMeguro-ku, Tokyo 153Telephone: (81) 3-3794-5511Fax: (81) 3-3794-5510

Japan (West)

Spectra-Physics KKWest Regional OfficeNishi-honmachi Solar Building3-1-43 Nishi-honmachiNishi-ku, Osaka 550-0005Telephone: (81) 6-4390-6770Fax: (81) 6-4390-2760e-mail: [email protected]

United Kingdom

Telephone: (44) 1442-258100

United States and Export Countries2

Spectra-Physics1330 Terra Bella AvenueMountain View, CA 94043Telephone: (800) 456-2552 (Service) or

(800) SPL-LASER (Sales) or(800) 775-5273 (Sales) or(650) 961-2550 (Operator)

Fax: (650) 964-3584e-mail: [email protected]

[email protected]: www.spectra-physics.com

1 And all European and Middle Eastern countries not included on this list.2 And all non-European or Middle Eastern countries not included on this list.


8-6

A-1

Appendix A Optishield Algaecide

At the end of this section is the material safety data sheet supplied by thevendor of the Optishield® algaecide used in the Evolution closed-loop cool-ing system. Please read this information before handling or disposing of thechemical or any cooling water containing it.

The information does not pertain to, and may not be appropriate for, largerquantities of the chemical than those described. The product is intended foruse by personnel with sufficient technical skill and qualification to use thematerial correctly and understand the risks in handling any potentially haz-ardous chemical.

Filling the Chiller for First Time Use

1. Flush the cooling circuit with distilled water.

2. The chiller reservoir has a 1-gallon capacity. Fill it with 1 pint ofOptishield fluid and the remaining volume (7 pints) of steam-distilledwater.

3. Circulate this solution for about 30 minutes.

4. Drain the fluid. Do not rinse. Continue as for periodic changing ofsolution (see below).

Periodic Changing of Solution

1. After draining the fluid, refill the reservoir with 1 pints of Optishieldfluid and the remaining volume (7 pints) of steam-distilled water.

Optishield is a registered trademark of Opti Temp, Inc.

This information, obtained from the manufacturer, is believed to be reli-able and accurate but has not been verified independently by Spectra-Physics. Accordingly, no representation or warranty, expressed orimplied, with respect to merchantability and fitness for a particular pur-pose is made in this data sheet. For further information, contact the man-ufacturer at the address listed.

Warning!


Caution!


A-2

2. Turn on the chiller and verify that water is flowing. Inspect for leaks atthe hose connections between the laser head and chiller.

3. Turn off the chiller.

Please note that it takes the chiller about 15 minutes to stabilize the temper-ature of the laser head cold plate and, thus, the output of the laser. If thelaser is used frequently, leaving the chiller on between periods of use willeliminate this stabilization period. If the laser is used infrequently, turn thechiller off between periods of use.

Optishield Algaecide

A-3

MSDS Sheet for Optishield

MATERIAL SAFETY DATA SHEET

OPTISHIELD®

Page 1 of 2 DATE REVIEWED: July, 2001

DISTRIBUTOR:OPTI TEMP INC. Telephone: 231-946-2931 P.O. Box 5246 Emergency Hot Line Traverse City, Michigan Chem-Tel 800-255-3924 49696 International 813-977-3668 (Collect)

USE OF PRODUCT: Treatment of select cooling water systems.

SECTION I - Product Identification

Special Components Chemical Names This is a proprietary blend which contains the following components:

Name % In Product Sodium Nitrate <1%Sodium Molybdate 1-2%Sodium Hydroxide 1-2%Phosphoric Acid <1.5%Triazole <2.5%

The Hazardous Materials Index Rating is as follows: Health=1; Flamability=0; Reactivity=1

SECTION II- Physical Data % Volatiles: Nil Color: Light Golden-Yellow Odor: Mild Specific Gravity: 1.03 Solubility: 100% in water pH of 100% solution (concentrated) 11 to 12; typical 11.5

SECTION III - Fire and Explosion Hazard Non-FlammableFlash Point: Unknown

SECTION IV - Reactivity Data Stability: Stable Polymerization: None Exposure to Other Chemicals: Keep away from concentrated acids Reactivity in Water: None


A-4

Page 2 of 2 SECTION V - Shipping Information Regulation: This material is not a DOT regulated material.

This product is a freezable liquid when and where applicable.

SECTION VI –Spill Small spills: Small spills may be soaked up using common absorbent material, and

using appropriate safety equipment. Dispose of and handle in accordance with local, state, and federal regulations.

Large spills: Large spills should be pumped into suitable containers located in diked areas. Residual material should be cleaned up with water. Dispose of and handle in accordance with local, state, and federal regulations.

SECTION VII - First Aid Ingestion: Give milk or water, induce vomiting, get medical attention.

Skin: Flush with fresh water, wash with soap and water. Remove contaminated clothes and shoes.

Eyes: Flush with fresh water for at least 15 minutes. Get medical attention.

Inhalation: Inhalation should not occur during normal operation. However, should it occur, close container and move to well-ventilated area. If irritation persists, get medical attention.

SECTION VIII - Special Instructions Do NOT pressurize container.

Keep container closed at all times when not in use.

Store in cool area above 60˚F. Do not allow fluid to freeze.

Use in well-ventilated area. Do not breathe mist or vapor.

Wash hands thoroughly after handling product.

Protect eyes with safety goggles or glasses with side shields.

B-1

Appendix B Computer Control

The Evolution can be completely controlled by any computer with a stan-dard RS-232 serial port. The Evolution command syntax is designed to rep-licate the functions of the Evolution controller and to monitor the status ofall of the components of the laser. A simple, comprehensive LabVIEW-based control program is available for the Evolution.

In addition, the individual LabVIEW routines are available as a startingpoint for users wishing to write their own control programs. Contact Spectra-Physics for more information.

RS-232 Connector Wiring

The Evolution RS-232 serial port accepts a standard 9-pin D-sub male/female extension cable. Only three pins are used for serial communica-tions:

RS-232 Communication Protocols

The Evolution uses the following communication protocols that must beset, accordingly, in the communications control program of the computer:

Command/Query/Response Format

All Evolution RS-232 commands, queries, and responses are in ASCII for-mat. Each command or query must be terminated with a carriage return<CR> or line feed <LF>. Commands that have a numerical argument must besent with all of the digits present, preceded with zeros if necessary. Com-

Pin Number Function

2 Evolution transmit data, computer receive data

3 Evolution receive data, computer transmit data

5 Signal ground

Setting Value

Rate 9600 bps

Data bits 8

Parity None

Stop Bits 1

Flow Control None


B-2

mands must be sent in all uppercase. All queries end with a question mark(?). Responses are terminated with a carriage return <CR>, followed by anangle bracket (>).

Command Quick Reference

Full Command Description

ON

Turns on the pump laser diodes if the Evolution is in Standby mode and thefront panel key is in the ON position. This command is equivalent to push-ing the ON/OFF button on the controller when the diodes are off.

OFF

Turns off the pump laser diodes if the Evolution is in Laser Running mode.This command is equivalent to pushing the ON/OFF button on the controllerwhen the diodes are on.

POW ###

Sets the percentage of laser diode pump power between 0% and 100%. Theargument must be a three-digit number between 000 and 100. This com-mand will work in any laser mode. This setting is equivalent to turning thePOWER knob on the controller.

LBO ###.#

Sets the USER setting of the LBO crystal temperature. The argument mustbe a four-digit number with a decimal point between the third and forthdigits (e.g., 1.234). The temperature must be within ±3°F of the factorytemperature setpoint, or the command is ignored. Note that if the differencebetween the USER temperature and the actual temperature reading is >3°F,a DIODE TEMP interlock will occur. Also note that the LBO USER tempera-ture is not stored in non-volatile Evolution memory until the diodes are

Command Parameter Function

ON none Turns on the laser diodes

OFF none Turns off the laser diodes

POW ### 000 to 100 Sets the percentage of diode pump power

LBO ###.# 300.0 to 380.0 Sets the LBO USER temperature setpointin °F

QSW # 0, 1, 2 Sets the Q-switch trigger source

FRQ #### 0010 to 9999 Sets the internal Q-switch frequency inHertz

DEL #### 0000 to 1791 Sets the timing delay of the VAR SYNCoutput in ns

*INT C none Clears latched interlocks

ON? none Returns the complete status of the Evolu-tion laser

Computer Control

B-3

turned on and off at least once. This setting is equivalent to changing theVAR SYNC knob on the controller when the LBO temperature is displayedon the LCD screen.

QSW #

Sets the source of the Q-switch triggers. The argument must be 0, 1, or 2,which corresponds to OFF (no Q-switch triggers), INTernal (internally gen-erated triggers at the FRQ frequency), or EXTernal. This command is equiv-alent to setting the Q-switch rocker switch on the controller. If thecontroller is attached and is detected when the Evolution is powered on, thecontroller setting will override this command.

FRQ ####

Sets the frequency of the internal Q-switch triggers. The argument must bea four-digit number in the range of 0010 to 9999. Not all frequencies withinthis range can be generated by the Evolution. If an inaccessible frequencyis set, the nearest available frequency will be used. This setting is equiva-lent to changing the FREQ knob on the controller.

DEL ####

Sets the delay of the QS VAR SYNC output on the front panel of the Evolu-tion. The argument must be a four-digit number in the range 0000 to 1791(nanoseconds). When the value is set to 0896, the VAR SYNC output has thesame timing as the fixed QS SYNC output.

*INT C

Resets any latched interlocks, provided that the interlock conditions havebeen met. This command is equivalent to cycling the LASER ENABLE keyon the power supply front panel off and on. Note that the laser will onlyoperate if the key is in the ON position.

ON?

Returns the status of the Evolution laser as a comprehensive list of comma-delimited values in the order listed in Table B-1:

Table B-1: Evolution Status Report

Parameter Value

Evolution status byte See Table B-2.

Evolution interlock byte See Table B-3.

Key state 0 (OFF) or 1 (ON)

Laser pump diode state 0 (OFF) or 1 (ON)

Laser pump diode power setting 000 to 100% of maximum

Q-switch trigger state 0 (OFF) or 1 (INTERNAL)or 2 (EXTERNAL)

Q-switch frequency 0010 to 9999 Hertz

VAR SYNC Delay 0000 to 1791 nanoseconds


B-4

The first comma-delimited parameter from the ON? query is a 2-characterhexadecimal value between $1D and $22. The value of this byte gives thestate of the laser as listed in the table below:

The second comma-delimited parameter from the ON? query is a 2-charac-ter hexadecimal value that represents the Evolution interlock state. Each bitin the hexadecimal byte corresponds to one of the eight interlocks as listedin the table below. To interpret the hex byte, translate it into binary: each bitindicates which interlock is open. For example, 00h = 00000000b = allinterlocks are closed; 40h = 01000000 = the Cover interlock is open; 84h =10000100 = the User and Flow interlocks are open.

Hours counter 00001 to 99999 hours

LBO factory temperature set point 300.0 to 340.0 °F

LBO user temperature set point 300.0 to 340.0 °F

LBO temperature reading 300.0 to 340.0 °F

Diode temperature readings (diodes 1-4) 60 to 99 °F

Diode temperature settings (diodes 1-4) 60 to 99 °F

Diode current readings (diodes 1-4) 00.0 to 40.0 Amp

Diode current settings (diodes 1-4) 00.0 to 40.0 Amp

Diode threshold current (diodes 1-4) 00.0 to 40.0 Amp

Diode maximum current (diodes 1-4) 00.0 to 40.0 Amp

Table B-2: Evolution Status Byte

Evolution Status Byte Value (Hexadecimal)

Interpretation

1D Shutdown mode

1E Cold Start mode

1F Standby mode

20 Warm Start mode

21 Laser Running mode

22 Q-switch changing mode

Table B-3: Evolution Interlock Byte

Evolution Interlock byte bit number Interpretation

8 (MSB) User

7 Cover

6 Diode Temp

5 LBO Temp

4 Temp Sensor

3 Flow

2 PS Error

1 (LSB) Diode Error

Table B-1: Evolution Status Report

Computer Control

B-5

Typical Command Usage

The control flow of an Evolution program might look like this:

1. Turn on the system, then wait approximately 15 seconds for the com-puter to initialize.

2. Issue an ON? command and parse the response to determine that allinterlocks are met, that the key is in the ON position and that the laseris in Standby mode. If the laser is in Warm Start mode, reissue an ON?command until the laser is in Standby mode.

3. Set the output power. For example, by issuing a POW 085 command, itis set to 85% of maximum power.

4. Turn on the laser by issuing an ON command.

5. Monitor the laser status by periodically issuing an ON? command.


B-6

Notes-1

Notes


Notes-2

Notes

Notes-3


Notes-4

Notes

Notes-5


Notes-6

Report Form for Problems and Solutions

We have provided this form to encourage you to tell us about any difficul-ties you have experienced in using your Spectra-Physics instrument or itsmanual—problems that did not require a formal call or letter to our servicedepartment, but that you feel should be remedied. We are always interestedin improving our products and manuals, and we appreciate all suggestions.

Thank you.

From:

Name

Company or Institution

Department

Address

Instrument Model Number Serial Number

Problem:

Suggested Solution(s):

Mail To: FAX to:

Spectra-Physics, Inc. Attention: SSL Quality ManagerSSL Quality Manager (650) 961-71011330 Terra Bella Avenue, M/S 15-50Post Office Box 7013Mountain View, CA 94039-7013U.S.A.

E-mail: [email protected]

Documents

Intracavity Doubled, Diode-Pumped Nd:YLF Laser · will be performed by a Spectra-Physics ... 2-1 Optical Safety Precautions ... Chapter 4: Controls