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Laser Safety Training
Environmental Health and Life Safety (EHLS)
713-743-5858
http://www.uh.edu/ehls
CourseThis course provides
Basic understanding of lasers and how they functionGeneral understanding of Laser hazardsGeneral instructions on how to work safely with lasers, and how to be protected from potentially harmful radiation An overall safety awareness in laser use labs. Based on the Texas Regulations for the Control of RadiationThis course covers basic laser radiation safety, physics, and biology and is not intended to be exhaustive on these subjects.
LASER LIGHT PROPERTIES
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Laser Light Properties
The light output of a laser differs from the output of ordinary light sources. Four properties characterize the laser’s output:
Small Divergence
Monochromatic
Coherence
High Intensity
Laser Light Properties
DivergenceWhen light emerges from the laser, it does not diverge (spread) very much at all. Thus the energy is not greatly dissipated as the beam travels.
MonochromaticLaser Light is very close to being monochromatic. The term “monochromatic” means one color, or one wavelength, of light. Actually, very few lasers produce only one wavelength of light.
Laser Light Properties
CoherenceCoherence is a term used to describe particular relationships between two wave forms. Two waves with the same frequency, phase, amplitude, and direction are termed spatially coherent.
High IntensityLaser light can be very intense. Energy is a measure of capacity for doing work and is measured in joules (J) in the metric system. Power is the rate at which work is being done and is measured in watts (W).
1 joule = 1 watt–second1 watt = 1 joule/second
A laser capable of emitting 10 joules per second can be termed a 10 watt laser. If the same 10 joules are emitted as a single pulse of 1/100th second duration, then the laser can be termed a 1,000 watt laser. Irradiance = W/cm2 Radiant Exposure = J/cm2
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FUNDAMENTAL DEFINITIONS
Definitions
Maximum Permissible Exposure Limit (MPE) – the level of laser radiation to which an unprotected person may be exposed without adverse biological changes in the eye or skin
Nominal Hazard Zone (NHZ) – the space within which the level of the direct, reflected, or scattered radiation may exceed the applicable MPE. Exposure levels beyond the boundary of the NHZ are below the appropriate MPE.
Definitions
CW Laser – a continuous wave laser whose output persists for a relatively long interrupted time interval, while the laser is turned on.
Pulsed Laser – a pulsed laser whose output occurs in short, interrupted time intervals, in contrast to a CW laser.
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Definitions
Beam Divergence – the increase in beam diameter with distance measured from the aperture of the laser.
Power Density – A term used to denote the power emitted per unit area per solid angle (watts per square centimeter per steradian). It is equivalent to the radiometric term “irradiance”.
L ight
A mplification by
S timulated
E mission of
R adiation
Laser-Professionals.com
BASICS OFLASERS AND LASER LIGHT
Thus the laser is a device which produces and amplifies light
Laser Components
Three components are necessary for laser construction and operation
An active lasing medium
An input energy source (Called a “Pump”)
An optical Resonator
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LASER COMPONENTS-Summary
High ReflectanceMirror (HR)
Output CouplerMirror (OC)
ActiveMedium
OutputBeam
Excitation Mechanism
Optical Resonator
All lasers have the same basic design.
Lasing Medium
Lasers can be classified according to the state of the lasing media
Solid state lasers employ a lasing material distributed in a solid matrix
Ex. Ruby laser
Gas lasers use a gas or mixture of gases within a glass tube
Ex. HeNe, CO2, Argon, and Krypton
Change energy levels
Lasing Medium
Liquid lasers are usually a complex organic dye with the most versatile feature of “tunability”; and proper choice of the dye and its concentration allows light production at almost any wavelength in or near the visible spectrum
Ex. Dye laser
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Energy input source-Pumps
Laser action can occur only when a population inversion has been established in the lasing medium. Several methods of pumping are commonly used.
Optical pumping is employed in solid state and liquid lasers. Xenon flashtubes are commonly used for solid state lasers and liquid lasers usually are pumped by a beam from another solid state laser.
Electron collision pumping is utilized in gas lasers. An electrical discharge is sent through the gas-filled tube.
Optical Cavity
Once the lasing medium has been pumped and a population inversion obtained, lasing action may begin. Without an optical cavity the direction of beam propagation would be produced in all directions leading to super-radiant lasing.
The beam of propagation can be controlled by placing the lasing medium in an optical cavity formed by two reflectors facing each other along a central axis.
Photon beams which are produced along that cavity are reflected 1800 at each reflection and travel once more through the lasing medium causing more stimulated emission. Thus the beam grows in magnitude with each traverse of the lasing medium.
Optical Cavity• Reflectors may consist of plane mirrors,
curved mirrors, or prisms.• Reflectors are not 100% reflective,
• Some photons may be lost by transmission through the mirrors with each passage.
• With continuous pumping, a state of equilibrium will soon be reached• between the number of photons produced by
atoms raised to the excited state and the number of photons emitted and lost.
• Result: a continuous laser output, usually used only with low power input levels.
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Higher power inputs usually are achieved in the form of a pulse form.
• One of the mirrors in the system is usually made more transparent than the other and the output, pulsed or continuous, is obtained through the reflector.A Q-switch is a device which interrupts the optical cavity for a short period of time during pumping. Q-switching is used to produce an exceptionally high-power output pulse.
All lasers have the same basic design.
• The active medium contains the atoms that produce laser light by stimulated emission - This can be a solid crystal, a gas, a semiconductor junction, or a liquid.
• The excitation mechanism is the source of energy that excites the atoms to the proper energy level for stimulated emission to occur.
• Solid state lasers use optical sources for excitation; gas lasers use electrical excitation.
• The active medium and excitation mechanism together form an optical amplifier. Laser light entering one end of the amplifier will be amplified by stimulated emission as it travels through the active medium.
• The optical resonator is a pair of mirrors at the ends of the active medium. These mirrors are aligned to reflect the laser light back and forth through the active medium.
• The output coupler has a lower reflectance and allows some of the laser light to pass through to form the output beam.
• The fraction of the light that is allowed to pass through the output coupler depends on the type of laser.
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VIDEO
Slides Covered or Supplemental to Video
Laser Spectrum• Lasers operate in the ultraviolet, visible, near infrared, and far
infrared regions of the spectrum.
• Visible light has a wavelength range of 400 – 700 nm• It and can be seen by the eye. • The fact that you can see this light helps you avoid hazardous
exposures.
• The near infrared has a range of 700 – 1400 nm. • It cannot be seen because the retinal receptors do not work at
these wavelengths. However, the optical elements of the eye transmit the NIR and focus these wavelengths on the retina.
• This produces an invisible retinal hazard and the potential for serious eye injury in the near IR.
• The most stringent laser safety precautions are required in this wavelength range. It also contains several of the most useful lasers.
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Ultraviolet – below 400 nm
Ocular Focus – 400 to 1400 nmretinal hazards which contain two distinct subranges400 to 700 nm – visible portion of spectrum and provides the light the eye uses to see withColors - Blue 450 nm
Green 500 nmYellow 550 nmOrange 600 nmRed 700 nm
700 to 1400 nm – also permitted by ocular components except that the retina, which also absorbs this range of wavelengths does not “see” them (invisible)
Infrared – above 1400 mmUV and IR wavelengths are not transmitted through the cornea and other exterior parts of the eye. Not focused on the retina and therefore magnification of laser light energy is not possible
LASER SPECTRUM
10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 1 10 102
LASERS
200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 10600
Ultraviolet Visible Near Infrared Far Infrared
Gamma Rays X-Rays Ultra- Visible Infrared Micro- Radar TV Radioviolet waves waves waves waves
Wavelength (m)
Wavelength (nm)
Nd:YAG1064
GaAs905
HeNe633
Ar488/515
CO2
10600XeCl308
KrF248
2Nd:YAG
532
Retinal Hazard Region
ArF193
CommunicationDiode1550
Ruby694
Laser-Professionals.com
Alexandrite755
Laser Classification
ANSI Z136.1 emphasizes that “It must be recognized that this classification scheme relates specifically to the laser device and its potential hazard, based on operating characteristics.
However, the conditions under which the laser is used, the level of safety training of persons using the laser, and other environmental and personnel factors are important considerations in determining the full extent of safety control measures.”
Beam Reflections – laser beams are reflected to some extent from any surface contacted. Essentially all reflections of laser beams result in spreading the beam or beam divergence
Specular – If reflecting surface is shiny like a mirrorDiffuse – If reflecting surface is not shiny
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Laser Classes; ANSI Z136.1 (2007)
Class 1 (I)
Class I M
Class 2 (II)
Class 2 M
Class 3 R (Class 3a)
Class 3B
Class 4
Class 1
Class 1 - Exempt Lasers– Produce levels of radiation that have not been found
to cause biological damage– This group is normally limited to gallium-arsenide
lasers or certain enclosed lasers– Incorporated into consumer or office machine
equipment
Safety Precautions– No laser specific rules, however general lab safety
rules still apply
Class 2
Class 2 - Low power and low risk– Produce radiation that could cause eye damage after
direct, long term exposure– Hazardous only if viewer overcomes natural aversion
response to bright light and continuously stares into source. Like blinding oneself by forcing oneself to stare at the sun for more than 10 to 20 seconds.
– Example lasers: grocery laser scanners
Safety Precautions– Never permit a person to stare into the laser source– Never point the laser at an individuals eye
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Class 3 (A and R)
Class 3 - Moderate Risk or Medium Power– Produce radiation powerful enough to injure human
tissue with 1 short exposure to the direct beam or its direct reflections off a shiny surface.
– However, not capable of causing serious skin injury or hazardous diffuse reflections under normal use.
Class 3B
Safety Precautions for Class 3B
– Do not aim the laser at an individuals eye
– Permit only experienced personnel to operate the laser
– Enclose the beam path as much as possible.
– Even a transparent enclosure will prevent individuals from placing their head or reflecting objects within the beam path
– Termination should be used at the end of the useful paths of the direct and any secondary beams
– Operate the laser only in a restricted area
Class 3B Continued
– Place the laser beam path well above or well below the eye level of any sitting or standing observers whenever possible
– The laser should be mounted firmly to assure that the beam travels only along its intended path
– Always use proper laser eye protection for the direct beam or a specular reflection
– Key switch to prevent tampering by unauthorized individuals
– Remove all unnecessary mirror-like surfaces from within the vicinity of the laser beam path
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Class 4
Class 4 - High Power, High risk of injury and can cause combustion of flammable materials.– May also cause diffuse reflections that are eye hazards
and may also cause serious skin injury from direct exposure
Safety Precautions– Class 3B safety precautions and;– Should only be operated within a localized enclosure or in
a controlled workplace– If complete local enclosure is not possible, Interlocking of
room– Eye wear is needed for all individuals working within the
controlled area– Backstops should be diffusely reflecting - fire resistant
target materials
Laser Radiation Hazards
LASER BEAM INJURIES
High power lasers can cause skin burns. E.g. CO2 Laser used for medical applications
Lasers can cause severe eye injuriesresulting in permanent vision loss.
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CAUSES OF LASER ACCIDENTSStudies of laser accidents have shown that there are usually several contributing factors. The following are common causes of laser injuries:
• Inadequate training of laser personnel
• Alignment performed without adequate procedures
• Failure to block beams or stray reflections
• Failure to wear eye protection in hazardous situations
• Failure to follow approved standard operatingprocedures or safe work practices
TYPES OF LASER EYE EXPOSURE
EYE
INTRABEAM VIEWING
LASER
DIFFUSE REFLECTION
LASER
SCATTERED LIGHT
MIRROR
SPECULAR REFLECTION
LASER
REFLECTED BEAM
ROUGHSURFACE
Biological Effects
Laser light can cause damage to living tissue. The extent of damage to living tissue caused by laser light depends primarily upon:
Frequency of the lightPower density of the beamExposure timeType of tissue struck by the beam
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Biological EffectsDamage can occur through 2 mechanisms of interactions:
Thermal EffectAbsorbed energy produces heat
The rapid rise in temperature can denature the protein materials of tissue, much as an egg white is coagulated when cooked
Light absorption in tissue is not homogeneous and the thermal stress is greatest around those portions of tissue that are the most efficient absorbers
Elastic or Acoustic Transient or Pressure WaveMechanical compression wave, can rip and tear tissue
Biological Effects
HazardsLaser light is usually only a hazard to those tissues through which the light beam can penetrate and which will absorb the wavelength involved
We are concerned primarily with two organs, the eyes and the skin
Of the two, the eye is often far more vulnerable to injury than the skin from visible and near-infrared laser radiation, thus it is considered the organ most important to protect from all wavelengths of laser radiation
Biological Effects
Skin Anatomy
The other area of concern is the skin. It is not as sensitive as the eye, and if damaged, most injuries are more easily repaired. However it too is subject to great damage from laser impact when energy densities approach several J/cm2.
The skin is not a homogeneous mixture. It is a specialized, layered structure with numerous odd inclusions, such as blood vessels and hair follicles.
The skin is relatively transparent to laser light and absorption in the skin occurs, for the most part, in the pigment granules and the blood vessels.
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Thermal & Photochemical
Thermal-injuries are caused by heating of the tissue as a result of the absorption of laser energy– Micro-cavitation-a type of thermal effect that
occurs when a short laser pulse is focused onto the retina (can ruptures blood vessels in the retina)
Photochemical- injuries occur because high energy photons break molecular bonds inside living cells
SKIN BURN FROM CO2 LASER EXPOSURE
Accidental exposure to partial reflection of 2000 W CO2 laser beamfrom metal surface during cutting
Other Photochemical effects
Other UV photochemical effects include – “welder’s flash” (Phtokeratitis),
– cataracts,
– and skin cancer from long term low level exposures.
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Biological EffectsEye Damage
The portion of the eye affected by the laser is dependent upon the wavelength of the light.
Injury to the anterior portion of the eyeCornea is sensitive to very short wavelengths UV and long wavelengths in the IR range such as the 10,600 nm output of carbon dioxide lasers
Other anterior structures such as the iris and lens are sensitive to wavelengths between 315 and 400 nm.
Important note to remember is that exposures to the lens one day may cause effects which will not become evident for many years
Biological Effects
Biological Effects
Injury to posterior portion of eyeThe retina can be damaged by lasers that operate in the visible and invisible range such as:
Ruby – 694.3 nmHeNe – 632.8 nmKr – 488-650 nmAr – 455-529 nm Nd:YAG – 1064 nm, 532 nmTi:Sapphire – 650-1100 nmHe:Ne – 543-1152 nm
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Photo courtesy of U S Air Force
THERMAL BURNSON
PRIMATE RETINA
Laser-Professionals.com
Photo courtesy of U S Army Center for Health Promotion and Preventive Medicine
EYE INJURY BY Q-SWITCHED LASERRetinal Injury produced by four pulses from a Nd:YAG laser range finder.
MULTIPLE PULSE RETINAL INJURY
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Eye Protection
Protective eyewear shall be worn by all individuals with access to Class 3b and/or Class 4 levels of laser radiation.
Protective eyewear devices shall provide a comfortable and appropriate fit all around the area of the eye; be in proper condition to ensure the optical filter(s) and holder provide the required optical density or greater at the desired wavelengths and retain all protective properties during its use; be suitable for the specific wavelength of the laser and be of optical density adequate for the energy involved; have the optical density or densities and associated wavelengths(s) permanently labeled on the filters or eyewear; and examined, at intervals not to exceed 12 months, to ensure the reliability of the protective filters and integrity of the protective filter frames.
Unreliable eyewear shall be discarded.
Laser Eyewear
Laser Eyewear
Laser eyewear is not for direct viewing.
>10 W power, eyewear will protect for about 3 seconds. >100 W power will burn the eyewear almost instantly.
EXTREME EYE SAFETY HAZARD, uncoated polycarbonate transmits 10,600 nm CO2 laser light (ABSOLUTELY will NOT protect the eyes): Acrylic (most versions) stops 10,600 nm wavelength.
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Skin Protection
When there is a possibility of exposure to laser radiation that exceeds the MPE limits for the skin, the registrant shall require the appropriate use of protective gloves, clothing, or shields.
Non Beam Laser Radiation Hazards
Non Beam Hazards– Chemical Hazards
– Physical Hazards
– Biological Hazards
– Human Factors
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Non-Beam Hazards
Mostly from High powered Lasers– Applications like material processing, medical
procedures, etc give rise to respiratory hazards
– Laser welding, cutting and drilling procedures generate potentially hazardous fumes and vapors
– Plume from laser tissue interactions- hazard during laser surgery
Non-Beam Hazards Continued
Electrical shock/electrocution– Use proper controls when working with
dangerous high voltage
Noise hazards up to 140 dB
Cryogenic coolants e.g. nitrogen
Non-Beam Hazards Continued
LGAC (Laser generated airborne contaminants)• Benzene, Toluene, HCl, Naphthalene, carbon
monoxide, Fluorine, etc.• Aerosols – Metal Oxides, Organic, Biologicals
Dust, mist, fume, fog, smoke, smog, Laser Dyes and Solvents
Dyes – some are toxic, mutagenicSolvents – irritation, anesthetics, maybe
flammable Potential for contaminated parts
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Non-Beam Hazards Continued
Collateral and Plazma Radiation
• X-ray – may require shieling if above 15kV: Thyratronswitched in pulse lasers and free electron lasers
• UV – Plasma radiation, from material processing on metals: Nd:YAG and CO2
• Visible – brightness, blue light hazards(possible damage to retina): Nd:YAG and CO2
• Infrared – Interact with stainless steel and generate bright blue wavelength (plasma)
Non-Beam Hazards Continued
• Radio Frequency – Pulsed Nd:YAG and CO2
• Extremely Low Frequency – Pulsed Nd:YAG, class IIIR HeNe
Fire
• Normally limited to combustion of flammable materials such as paper by CW lasers operating with an output greater than 0.5 W, class 4
• Class IIIB laser will ignite dust in dusty environment• Depends on enclosure materials, construction materials,
target materials, laser gases, vapors, LGAC
Non-Beam Hazards Continued
Explosion
• May exist due to high pressure arc lamps, filament lamps, target, dust collection explosion, etc.
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Non-Beam Hazards ContinuedCompressed Gas Cylinders
• Do not drop cylinders or permit them to strike each other violently• Where caps are provided for valve protection, keep such caps in
place except when the cylinders are in use• Do not force connections that do not fit• Never lubricate, modify, force, or tamper with a cylinder valve• Chain or strap cylinders securely in place so they will not fall over
When cylinders are not in use, keep valves tightly closed• Handle empty cylinders as though they were full; Keep them
chained or strapped, and store them away from full cylinders• Transport cylinders with cap in place and use a hand truck to which
they can be strapped or chained• Make sure cylinders are labeled to identify the contents• Know the identity of the gas you are using, and be familiar with its
properties
Break
10 minutes
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Laser Safety Standards and Regulations
Regulatory Agencies/Standards
• Texas Department of State Health Services (DSHS)
• [Regulates university of Houston through a Certificate of Laser Registration]
• Food and Drug Administration (FDA)
• The American National Standard for Safe Use of Lasers (ANSI Z136.1)
• This is a VOLUNTARY Standard that applies to the use of lasers.
• It is “recognized by” : The Occupational Safety and Health
Administration (OSHA)
• IEC 60825 International Standard
Laser RegulationsRadiation Safety Requirements for Class 3b and 4 Lasers
• Individuals shall not use lasers on humans unless under the supervision of a licensed practitioner of the healing arts and unless the use of lasers is within the scope of practice of their professional license.
• Individuals shall not be intentionally exposed to radiation above the maximum permissible exposure (MPE) unless such exposure has been authorized by a licensed practitioner of the healing arts.
• Exposure of an individual for training, demonstration or other non-healing arts purposes is prohibited unless authorized by a licensed practitioner of the healing arts.
• Exposure of an individual for the purpose of healing arts screening is prohibited, except as authorized by the Texas Department of State Health Services.
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Laser Regulations
• Exposure of an individual for the purpose of research is prohibited, except as authorized in research studies.
• Any research using radiation producing devices on humans must be approved by an Institutional Review Board (IRB) as required by the Code of Federal Regulations.
• The IRB must include at least one practitioner of the healing arts to direct use of the laser.
• These requirements apply to lasers that operate at wavelengths between 180 nm and 1 mm.
Registration Requirements
The registrant shall notify the agency in writing within 30 days of any increase in the number of lasers authorized by the Registration.
An application for healing arts shall be signed by a licensed practitioner of the healing arts.
An application for veterinary medicine shall be signed by a licensed veterinarian.
Each new use of a Class 3b or Class 4 laser in the healing arts or for animal use shall be submitted to the agency within 30 days after beginning operation of the laser.
Registration Continued
No person shall make, sell, lease, transfer, or lend lasers unless such machines and equipment, when properly placed in operation and used, shall meet the applicable requirements.
Each registrant shall inventory all Class 3b and Class 4 lasers in their possession at an interval not to exceed one year.
The inventory shall be maintained for inspection and include:
Manufacturer’s NameModel and Serial Number of the laserDescription of the laserLocation of the laser
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Registration Continued
The Registrant shall maintain records of receipt, transfer, and disposal of Class 3b and Class 4 lasers for inspection to include:
Manufacturer’s NameModel and Serial Number of the laserDate of receipt, transfer, and disposalName and address of person laser(s) received from, transferred to, or disposed byName of individual recording the information
Laser Regulations
Each registrant or user of any laser shall not permit any individual to be exposed to levels of laser or collateral radiation higher than the Maximum Permissible Exposure (MPE) limits.
Personnel operating each laser shall be provided with written instructions for safe use, including clear warnings and precautions to avoid possible exposure to laser or collateral radiation in excess of the MPE.
Engineering Controls
Measures necessary for controlling laser hazards normally concentrate upon making the beam path inaccessible, such as enclosing the laser in a box or controlled room to prevent unauthorized access.
As this is not always possible, other Administrative and Engineering Controls are used to lessen the possibility of injury.
The Safety Procedures necessary for any laser operation vary with 3 aspects:– Laser hazard classification– Environment where the laser is used (outside vs. inside a
controlled area)– People operating or within the vicinity of the laser beam (Desks
in lab)
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Performance Standards (Regulatory)
Engineering Controls
Protective Housing
Each laser shall have a protective housing that prevents human access during the operation of the laser and
collateral radiation that exceeds the limits of Class 1.
Safety Interlocks
A safety interlock, that shall ensure that radiation is not accessible above the MPE limits, shall be provided for any portion of the protective housing that by design can be removed or displaced during normal operation or maintenance, and thereby allows access to radiation above the MPE limits.
Adjustment during operation, service, testing, or maintenance of a laser containing interlocks shall not cause the interlocks to become inoperative or the radiation to exceed MPE limits outside protective housing except where a laser controlled area is established.
Safety Interlocks (pulsed laser)
For pulsed lasers, interlocks shall be designed so as to prevent firing of the laser; for example, by dumping the stored energy into a dummy load.
For continuous wave lasers, the interlocks shall turn off the power supply or interrupt the beam; for example, by means of shutters.
An interlock shall not allow automatic accessibility of radiation emission above MPE limits when the interlock is closed.
Either multiple safety interlocks or a means to preclude removal or displacement of the interlocked portion of the protective housing upon interlock failure shall be provided, if failure of a single interlock would allow human access to high levels of laser radiation.
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Viewing Optics and Windows
All viewing ports, viewing optics, or display screens included as an integral part of an enclosed laser or laser product shall incorporate suitable means, such as interlocks, filters, or attenuators, to maintain the laser radiation at the viewing position at or below the applicable MPE under any conditions of operation of the laser
All collecting optics, such as lenses, telescopes, microscopes, endoscopes, etc., intended for viewing use with a laser shall incorporate suitable means, such as interlocks, filters, or attenuators, to maintain the laser radiation transmitted through the collecting optics to levels at or below the appropriate MPE.
Normal or prescription eyewear is not considered collecting optics.
Warning SystemsEach class 3b, or 4 laser or laser product shall provide visual or audible indication during the emission of accessible laser radiation. For class 3b lasers and class 4 lasers, this indication shall be sufficient prior to emission of such radiation to allow appropriate action to avoid exposure.
Any visible indicator shall be clearly visible through protective eyewear designed specifically for the wavelength(s) of the emitted laser radiation.
If the laser and laser energy source are housed separately and can be operated at a separation distance of greater than two meters, both laser and laser energy source shall incorporate visual or audible indicators.
The visual indicators shall be positioned so that viewing does not require human access to laser radiation in excess of the MPE.
Controlled Area
For class 3b lasers or class 4 lasers, a controlled area shall be established when exposure to the laser radiation in excess of the MPE or the collateral limits is possible.
Each controlled area shall be posted by proper laser signage and access to the controlled area shall be restricted.
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Indoor controlled areas
For Class 4 indoor controlled areas, latches, interlocks, or other appropriate means shall be used to prevent unauthorized entry into controlled areas.
Where safety latches or interlocks are not feasible or are inappropriate, for example during medical procedures, the following shall apply:
All authorized personnel shall be trained in laser safety and appropriate personnel protective equipment shall be provided upon entry;
A door blocking barrier, screen, or curtains shall be used to block, screen, or attenuate the laser radiation at the entryway.
The level at the exterior of these devices shall not exceed the applicable MPE, nor shall personnel experience any exposure above the MPE immediately upon entry.
At the entryway there shall be a visible or audible signal indicating that the laser is energized and operating at Class 4 levels.
Class 4 Indoor Controlled Area
For Class 4 indoor controlled areas, during tests requiring continuous operation, the individual in charge of the controlled area shall be permitted to momentarily override the safety interlocks to allow access to other authorized personnel if it is clearly evident that there is no optical radiation at the point of entry, and if necessary protective devices are being worn by the entering personnel.
For Class 4 indoor controlled areas, optical paths from an indoor facility shall be controlled in such a manner as to reduce the transmitted values of the laser radiation to levels at or below the appropriate MPE and the collateral limits.
Temporary Controlled Area
When the removal of panels or protective covers and/or overriding the interlocks becomes necessary, such as for servicing, testing, or maintenance, and accessible laser radiation exceeds the MPE and the collateral limits, a temporary controlled area shall be established.
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Nominal Hazard Zone (NHZ)
Where applicable, in the presence of unenclosed Class 3b and Class 4 laser beam paths an NHZ shall be established.
If the beam of an unenclosed Class 3b and Class 4 laser is contained within a region by adequate control measures to protect personnel from exposure to levels of radiation above the appropriate MPE, that region may be considered to be the NHZ.
Key Control
Each Class 3b and Class 4 laser shall incorporate a key-actuated or computer-actuated master control.
The key shall be removable and the Class 3b and Class 4 laser shall not be operable when the key is removed.
When not being prepared for operation or is unattended, the key will be removed from the device and stored in a location away from the machine.
Additional Requirements for Safe Operation
Infrared Laser
The beam from an infrared laser shall be terminated in a fire-resistant material where necessary.
Inspection intervals of absorbent material and actions to be taken in the event or evidence of degradation shall be specified in the operating and safety procedures.
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Radiation Signage and Postings
Radiation Signage and Postings
Radiation Signage and Postings
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Radiation Signage and Postings
Radiation Signage and Postings
Radiation Signage and Postings
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Radiation Signage and Postings
Audits/Inspections
Lasers inspections are conducted by Radiation Safety to ensure regulatory compliance at intervals not to exceed 12 months.
The inspections include a determination that all laser protective devices are labeled correctly, and functioning within the design specifications, and properly chosen for lasers in use; a determination that all warning devices are functioning within their design specifications; a determination that the controlled area is properly controlled and posted with accurate warning signs; a re-evaluation of potential hazards from surfaces that may be associated with beam paths; and additional surveys that may be required to evaluate the primary and collateral radiation hazard incident to the use of lasers.
Records & Documentation
Records
Radiation Safety will maintain compliance records for regulatory review.
Applicable records must be submitted to Radiation Safety upon request.
Injury or Medical Event
The Laser Safety Officer shall immediately seek appropriate medical attention for the individual and notify the agency by telephone of any injury involving a laser possessed by the registrant, other than intentional exposure of patients for medical purposes, that has or may have caused an injury to an individual that involves the partial or total loss of sight in either eye; or an injury to an individual that involves perforation of the skin or other serious injury exclusive of eye injury.
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Regulatory Reporting
The Laser Safety Officer shall, within 24 hours of discovery of an injury, report to the agency each injury involving any laser possessed by the registrant, other than intentional exposure of patients for medical purposes, that may have caused, or threatens to cause, an exposure to an individual with second or third-degree burns to the skin or potential injury and partial loss of sight.
The Laser Safety Officer shall make a report in writing to the agency within 30 days and a notice to the individual shall be transmitted at the same time.
The LSO shall also notify the agency of any medical event involving a patient as required.
UNIVERSITY OF HOUSTON RADIATION SAFETY PROGRAM
Purpose
Protection of the university population, general public, and environment against radiation hazards associated with UH’s possession, use, transportation, and disposal of radioactive material.
Provide for compliance with TDSHS and other applicable radiation protection regulations.
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Laser Safety Manual
PurposeThe purpose of the Laser Safety Manual is to assist personnel, students, and management in complying with the State Radiation Regulations and the Laser Safety Program.
IntentThis Laser Safety Manual is not intended to be an exhaustive or fully comprehensive reference, but rather a guide for Principal Investigators and Authorized Users.
AuthorityThe Laser Safety Manual is an enforceable component of the Radioactive Material Broad Scope License and Radiation Producing Devices Registrations under which the University of Houston is authorized.
Training Requirements
All PIs and Authorized Users of Class 3b and 4 lasers must attend and pass the laser safety training
Testing- requires at least 70% to pass. This test is used to fulfill the requirement for users to demonstrate competence.
Upon completion, be added to a sub-registration through an amendment.
Online Annual Refresher Training. Testing requires at least 80% to pass
Laser Safety Officer (LSO) duties
Ensure that users of lasers are trained in laser safety, as applicable for the class and type of lasers the individual uses.
Assume control and have authority to institute corrective actions including shutdown of operations when necessary in emergency situations or unsafe conditions.
Laser Light Shows CDRH Requirements
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LSO Duties Continued
Ensure maintenance and other practices required for the safe operation of the lasers are performed.
Ensure the proper use of protective eyewear and other safety measures.
Ensure compliance with the laser requirements and with any engineering or operational controls specified by the registrant.
Radiation Safety Responsibilities
Radiation Safety Committee - Technical Expertise,Approve Facilities and Usage, Review Radiation Safety Program, Support RSO Authority
Radiation Safety Officer and Staff - Radiation Safety Manuals, Audits and Lab Reviews, Incident Investigations, Health Physics Services, PI Consultations and Technical Support
Principal Investigators – Compliance, AUs Safety and Instruction
Authorized Users - Work Safely and follow the Rules
Administration Process (mainly for PIs)
Laser Subregistration Application and Amendment
Location changes
Standard Operating Procedures
Change services
Laser purchasing, transfer, and disposal
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Radiation Safety ViolationsRadiation Safety performs routine internal audits/inspections
These help assure compliance with the UH Laser Registration and prevent a Notice of Violation (NOV) as a result of a state inspection
If a violation is found by a state inspector during the inspection, the person committing the violation will be named on the NOV and not the RSO
At UH, a Principal Investigator will be cited by Radiation Safety for violations which include any aspect of their subregistration conditions
Chronic violations of subregistration conditions can jeopardize a Principal Investigator’s authorization to use lasers
Incident Notification
Individuals working with radiation must assume the responsibility for their own safety and must ensure that their actions do not result in a hazard to others.
In the event of a suspected or know exposure, immediately stop work and notify your Principal Investigator and the Radiation Safety Officer.
If it is determined that there is an acute localized exposure, seek medical attention as soon as possible.
Emergency Information
EHLS office hours: Monday through Friday, 8:00 a.m. - 5:00 p.m.For assistance with a radiation emergency or incident during normal office hours call EHLS. In the event of an after hours radiation emergency, contact the UHDPS. EHLS maintains an on-call mechanism to provide expertise in the event of an after hours situation requiring assistance.Radioactive material spills and emergency information is available in the Radiation Safety Manual at http://www.uh.edu/ehlsIf you call after normal office hours about a non-emergency incident, you may leave pertinent information on EHLS telephone voicemail system.
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Emergency Telephone Numbers
EHLS – Main Line (713) 743-5858
RSO/CLSO - Otu (713) 743-5867
ARSO/CLSO - Sangho (713) 743-5870
Health Physicist - Darla (713) 743-5860
Health Center (713) 743-5151
DPS (Emergency) 911
DPS (Non-Emergency) (713) 743-3333
Exam
GOOD LUCK!
