Henry Helvajian Micro Nanotechnology Department The ...THE AEROSPACE CORPORATION Selected Developments from the 2nd Int. Conf. on Laser Processes and Components (LPC) March 21-22,

Laser Material ProcessingLaser Material Processing

Henry HelvajianMicro Nanotechnology Department

The Aerospace CorporationLos Angeles, California

[email protected] of MicroNanotechnology 2007

THE AEROSPACECORPORATION

Laser Material Processing Industry in GermanyLaser Material Processing Industry in GermanyMarket Overview by the SwissMarket Overview by the Swiss**

Laser macro machining: cutting, welding, and labeling systems, – Aluminum can be cut up to 15 mm and stainless steel up to 25 mm thickness.

Laser micromachining: systems for manufacturing semiconductors, flat screens, electronic component, and PCBs.

Between 2000 and 2005 production value grew by about 32% for laser sources and about 35% for complete laser machining systems. In the same period laser source exports grew by 25%, and those for laser units even by 46% – and this in spite of the 30% rise in the Euro over the dollar in the years 2003 and 2004In 2004 laser macromachining had advanced by 23%, laser micromachining by 44% (both sectors together +28%). The world market for machining laser systems in 2005 reached a new record of € 4.8 billion, macromachining laser sector € 3.7 billion (a growth of 7% over 2004), micromachining laser sector € 1.1 billion.

*Optech Consulting (Tägerwilen, Switzerland ): Corporate consultancy specializing in laser technologies.





Selected Developments from the 2nd Int. Conf. on Laser Processes and Components (LPC)

March 21-22, 2007 Shanghai, China– Laser metal deposition in the development of aeronautical materials and in the

repair of turbine blades. LLaser synthesizing of Nb-Ti-Al alloys through blending of pure powders of Nb, Ti, Al.

Fabrication of a high temperature inter metallic composite laminated using a multi-layer deposition scheme.

– Using laser shock wave for metal forming of components that also have residual compressive stress.

Improvement of fatigue strength and stress corrosion performance while shaping the material.

– Improving physical properties of functional materials by laser irradiation. A novel transparent Ta2O5-based ceramic with maximum κ of 450 can be obtained at ambient conditions when sintered with a CO2 laser. Increase in electrical conductivity of Poly(vinylidene fluoride) induced by 248 nm excimer laser irradiation. Electrical conductivity increases (10-13 Ω-1 ·cm-1 to 10-4 Ω-1·cm-1, producing a transition in the material property from an insulator to a conductor. Significant improvement in the magneto transport properties of La0.67Ca0.33MnO3 thin films by CO2 irradiation in air.



Selected Developments from the LPC Continued

Slab lasers (INNOSLAB) being applied for Slab lasers (INNOSLAB) being applied for micro precision processing.micro precision processing.Disk laser powers to 8kW reported.Disk laser powers to 8kW reported.Lasers for micro cladding using Lasers for micro cladding using ““electronicelectronic””pastes to fabricate electronic components by pastes to fabricate electronic components by directdirect--write. write. Single mode laser diodes and the Single mode laser diodes and the commercialization of periodicallycommercialization of periodically--poled poled crystals have enabled new design possibilities crystals have enabled new design possibilities for visible solidfor visible solid--state lasers covering the 400 state lasers covering the 400 –– 650 nm wavelength range. 650 nm wavelength range. –– Design concepts of fiberDesign concepts of fiber--based telecombased telecom--style laser style laser

architectures for higharchitectures for high--volume, reproducible volume, reproducible manufacturing. manufacturing.



Technologies/Science in Micro/nanofabrication: Technologies/Science in Micro/nanofabrication: Selected ExamplesSelected Examples

Increasing use of diffractive optics.Increasing use of diffractive optics.–– e.g. variable beam intensity beam e.g. variable beam intensity beam

shaping optics for specific shaping optics for specific micromachining applications.micromachining applications.

Controlling of laser deposition of heat to Controlling of laser deposition of heat to affect a reversible phase change in glass affect a reversible phase change in glass ceramicsceramics

Controlling the formation of nm scale Controlling the formation of nm scale structures from structures from fsfs laser induced laser induced modification in transparent media for bio modification in transparent media for bio nanofluidics applicationsnanofluidics applications



Scripting the Laser Amplitude & Scripting the Laser Amplitude & Polarization for Optimum Material Polarization for Optimum Material

ProcessingProcessing



Laser Material Processing Using Modulated Pulse Sequences

Process

a] Ablation

b] Welding

c] Texturing

d] Dosing

Ablate DoseMaterial 1Material 2Material 3

Texture

Weld

Laser Pulse Structure Mat1 Laser Pulse Structure Mat2



What would the Ideal Processing “tool” LOOK like?

• I want to “script”, a priori, the photon delivery (power, number of shots applied, types of lasers (color, pulse structure) etc.) for every laser SPOT SIZE along the tool path based on the TYPE of Material Process that is to be Conducted.

• Without regard to the motion speed/direction (i.e. vector velocity) and regardless of the feature pattern.

• We assume that the sample substrate properties have been mapped in 3D, a priori.

• We assume that the material has “properties” that can be expressed via controlled deposition of light.

Laser Spot Size

Laser or Target Motion



Use of Digitally-Scripted Genotype Pulse PatternsGENOME = Sequence of concatenated genotypes

that define a “script”.“Script” contains attributes that are tobe expressed according to the specificsequencing.

Genotype 1 2 3 4

Laser Pulse “Script”

Laser-processing programmer developsa pulse “script”

“Script” is synchronously matched withthe laser tool path

“Script” can be altered on a per laserspot basis

Feed rate can be “throttled” to controlspeed, exposure and resolution

Ultrafast and high repetition rate lasers are ideallysuited for digitally-scripted laser processing

Laser Tool Path

Laser Pulse Script

M-Codeshold informationon type of desired

process

G-Codeshold information

on Cartesian space

Link pulse scriptwith tool path

xy



System is designed to deliver a prescribed number of laser pulses with a given amplitude distribution for each defined path segment along a pattern tool path.

In example above: the defined path segment length is 3 microns = laser spot size.



1

1

2

23

34

4

Script 1: 28 pulses Script 2: 20 pulses Script 3: 8 pulses Script 4: 1 pulse

Laser pulse script can be altered for each spotMultiple process steps can be achieved per spot

• Ablation / Melting• Annealing / Polishing• Crystallization / Nucleation

10 μm500 μm

1400 Å Au / 100 Å Cr / Quartz



Ablation of Glass Using Modulatedfs Laser Pulses at 400 nm

Not scripted

Spallation and debris formationFractures and thermal-induced stress

Debris

Scripted

10 μm offset

3 μm spotdiameter

Localized material removalPatterns are clean and well defined



Exposure of Photosensitive Glass UsingModulated fs Laser Pulses at 400 nm

10x

50x

Digitally Scripted Genotype Processing OFF

Over-exposure

Multi-pulse regions

10x

50x

Uniform exposure

30 pulses/spot

Digitally Scripted Genotype Processing ON



Employed different pulse scripts to synchronously control number of laser pulses delivered to each spot during continuous concentric patterning

Formation of variable wavelength attenuatorsand embedded cut-off filters

RW-memory in voxels using optical defect states (bit-data information storage in glass)

1 mm

1 mm

Laser Raster

3 μm

Formation of ND Filters in Photosensitive Glass via Pulse Scripting



A

B

C

= Transition to new script

Region A: 29 pulses/spot

Region B: 153 pulses/spot

Region C: 305 pulses/spot

What we are really interested in exploring is the affect of the pulse-amplitude distribution to alter select physical properties in photoactive materials*.

*F. E. Livingston and H. Helvajian, J. Photochem, Photobiol. A (2006) p310.



Utilization of pulse scripts with varying pulse number (equivalent photon dose)

• Trapped defect state density decreaseswith increasing pulse number

• Selective modification of optical transmission properties

• Controlled variation in lithium metasilicate (Li2SiO3) density

3000

2500

2000

1500

1000

500

0

Inte

nsity

(cou

nts)

806040202-Theta (degrees)

3000

2500

2000

1500

1000

30282624

(111)

A

B

C

Optical Spectroscopy and XRD Results FollowingLaser Exposure and Thermal Treatment

Li2SiO3

1.5

1.0

0.5

0

Abs

orba

nce

1000800600400200

Wavelength (nm)

A=29 pulses/spot

B=153 pulses/spot

C=305 pulses/spot

Latent State

500°C 1hr, 605°C 1 hr



5000

4000

3000

2000

1000

0

Inte

nsity

(cou

nts)


10000

7500

5000

2500

0

Inte

nsity

(cou

nts)


ABC

Predominant formationof Li2Si2O5

5000

4000

3000

2000

1000

0

Inte

nsity

(cou

nts)


(311)(002)(021)

Extreme preferredorientation for Li2SiO3

(A)

(B)(C)

XRD Results Following Laser Exposureand High-T Thermal Treatment

Mixed-phase system

Li2Si2O5

Li2SiO3

500°C 1hr, 800°C 1 hr

The Laser Microengineering Experimental Station (LMES) The Laser Microengineering Experimental Station (LMES) at JLABat JLAB

Unique Tool Unique Tool Designed for the Controlled Delivery Designed for the Controlled Delivery of the FEL Light to a Moving Targetof the FEL Light to a Moving Target



• A laser beam delivery system for processing in the UV and IR at processing speeds approaching 450 mm/sec.

• Automated sequencing of tool changes (e.g. color, focusing objective).

• A coordinated three-axis motion system, XY motion range of >100mm.

• An automated means for laser power and repetition rate control.

• A vision system for process control.• CAD software for solid modeling of patterns.• CAM software for generating 3 axes tool-path

and visual verification of geometry.• Software for converting the tool-path geometry

into motion language.

System Attributes



The LMESAfter

InstallationAugust 2005



An Experiment to Demonstrate Remote Operation of An Experiment to Demonstrate Remote Operation of the LMES Performed in December 2006the LMES Performed in December 2006

Machining Tool in Newport News, VA

Lee Steffeney the tool “operator”in Los Angeles, CA

controlling

• Establish remote connection.• Select viewing cameras for run.• Move platform to

initialize/calibrate axis.• Insure that the laser beam focus

on the target is < 5 μ. • Monitor laser beam for optimum

spatial intensity profile.• Monitor/change the laser beam

power for metered dose exposure.• Initiate the tool path pattern JOB.



Hope to Conduct Further Remote Operation Experimentson the LMES

Experiment repeated on two separate days.

Results successful.

Patterned structures for a glass ceramic nanosatellite fuel tank.

There is enough video and control lines in the LMES architecture to provide a USER support from a remote location.



Thank YouThank You

Documents

Henry Helvajian Micro Nanotechnology Department The ...THE AEROSPACE CORPORATION Selected Developments from the 2nd Int. Conf. on Laser Processes and Components (LPC) March 21-22,