HSE-LS-15_Laser_Safety_Training.pdf

8/9/2019 HSE-LS-15_Laser_Safety_Training.pdf

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The Petroleum Institute

30 hr Lab Safety Training

HSE/LS 15: Laser Safety Training

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LASER

LASERstands for:

Light

Amplification by the

Stimulated

Emission of

Radiation

Upon completion of thismodule, the attendee will:

Be able to describe the operation of lasers;

Explain why laser radiation is more hazardous that other

forms of radiation in the same wavelengths;

Recognize the various laser classes;

Describe engineering controls for laser hazards;

Describe the administrative controls for laser hazards; and

Describe the personal protective equipment that should be

worn when working with various classes of laser.


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Laser Light

Laser light is monochromatic, unlike ordinary light which is made

of a spectrum of many wavelengths. Because the lightis all of the same wavelength, the light waves are saidto be synchronous.

is directionaland focused so that it does not spread outfrom the point of origin.

Synchronous,monochromatic, directional

light waves

Asynchronous, multi-directional light.

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Uses of Lasers

Lasers are used in industry,communications, military, research andmedical applications.

At PI, lasers are principally used inresearch.

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How a Laser Works

A laser consists of an opticalcavity, a pumping system,and a lasing medium.

The optical cavitycontains the media to be excited withmirrors to redirect the produced photons back along the samegeneral path.

The pumping systemuses various methods to raise themedia to the lasing state.

Thelaser mediumcan be a solid (state), gas, liquid dye, orsemiconductor.

Source: OSHA Technical Manual, Section III: Chapter 6, Laser Hazards.


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Laser Media

There are different safety hazards associated withthe various laser media.

1. Solid statelasers

2.Gaslasers

3. Excimerlasers (a combination of the termsexcitedand dimers) use reactive gases mixedwith inert gases.

4. Dye lasers(complex organic dyes)

5. Semiconductorlasers (also called diodelasers)

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Types of Lasers

which part of the electromagnetic spectrum isrepresented:

Infrared

Visible Spectrum

Ultraviolet

the length of time the beam is active:

Continuous Wave

Pulsed Ultra-short Pulsed

Lasers can be described by:

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Electromagnetic Spectrum

10-12 10-10 10-8 10-6 10-4 10-2 100 102 104 106 108

x-raysgamma rays

Ultra-violet Infrared Radar

Radiowaves

Electr icwaves

The Electromagnetic Spectrum

IonizingRadiation

Wavelength (cm)

Laser wavelengths are usually in the Ultraviolet, Visible orInfrared Regions of the Electromagnetic Spectrum.


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Common Ultraviolet Lasers

Ultraviolet (UV) radiation ranges from 200-400 nm.

10-12 10-10 10-8 10-6 10-4 10-2 100 102 104 106 108

x-raysgamma rays


Radiowaves

Elect r icwaves

IonizingRadiation

Wavelength (cm)


Argonfluoride

Kryptonchloride

Kryptonfluoride

Xenonchloride

Heliumcadmium

NitrogenXenonfluoride

193 nm 222 nm 248 nm 308 nm 325 nm 337 nm 351 nm

Ultra-violetUltra-violet


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Common Infrared Lasers

10-12 10-10 10-8 10-6 10-4 10-2 100 102 104 106 108

x-raysgamma rays


Radiowaves

Elect r icwaves

IonizingRadiation

Wavelength (cm)

Infrared radiation ranges from 760-10,000 nm.

InfraredInfrared

Common Infrared Lasers

Near Infrared Far Infrared

TiSapphire

Heliumneon

Nd:YAG Heliumneon

Erbium Hydrogenfluoride

Heliumneon

Carbondioxide

Carbondioxide

800nm

840 nm 1,064nm

1,150nm

1,504nm

2,700nm

3,390nm

9,600nm

10,600nm

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Common Visible Light Lasers

Violet Helium cadmium 441 nm

BlueKrypton 476 nm

Argon 488 nm

Green

Copper vapor 510 nm

Argon 514 nm

Krypton 528 nm

Frequency doubled Nd YAG 532 nm

Helium neon 543 nm

Yellow

Krypton 568 nm

Copper vapor 570 nm

Rohodamine 6G dye (tunable) 570 nm

Helium neon 594 nm

Orange Helium neon 610 nm

Red

Gold vapor 627 nm

Helium neon 633 nm

Krypton 647 nm

Rohodamine 6G dye 650 nm

Ruby (CrAlO3) 694 nm

The wavelengthrange for light thatis visibleto the eyeranges from400-760 nm.


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Light Reflection Hazards

Types of Reflections

Specular reflectionis a reflection from a mirror-likesurface. A laser beam will retain all of its original

power when reflected in this manner.Note that surfaces which appear dull to the eye may bespecular reflectors of IR wavelengths.

Diffuse reflectionis a reflection from a dull surface.Note that surfaces that appear shiny to the eye may bediffuse reflectors of UV wavelengths.

Diffuse laser light reflection from a high poweredlaser can result in an eye injury.

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Biology of the Eye

Cornea

Lens

Fovea(focal point)

Retina

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Retinal Hazard Region

The wavelength range of light that can enter the eye is400 to 1400 nm, though the range that we canactually see is only 400 760 nm.

The eye can focus a collimated beam of light to aspot 20 microns in diameter on the retina (called the focal point).

This focusing ability places the retina at risk when exposed to laser lightin the wavelength range that will penetrate to the retina, because evenfairly low wattage laser light can impact the retina with 100,000 times

the radiant power that entered the eye. Because of this optical gain,laser light in the 400 1400 nm is referred to as the Retinal HazardRegion.

This is important to remember when working with infrared lasers,because the retina can be injured even though the laser is invisible.


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Retinal Hazard Region Eye Injury

Visible and Near-Infrared

Far-Infrared and Far-Ultraviolet

Near Ultraviolet

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Biological Hazards - Retina

Thermal damageto the retina occurs in theRetinal Hazard Region (from 400 nm 1400 nm).Thermal damage is not cumulative, as long as theretina cools down between exposures.

Photochemical damageis severe at shorter visiblewavelengths (violet & blue) and is cumulativeover a working day.

Acoustic shockfrom exposure to high energypulsed lasers results in physical tissue damage.

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Biological Hazards Cornea & Lens

Inflammation injury to the cornea is caused by ultraviolet(UV) wavelengths (200-400 nm). This is the same type

of injury that is caused by snow blindness. Chronic exposure can cause cataract formation in the lens

of the eye just as UV from the sun does.

Cornea

Lens


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Biological Hazards - Skin

Ultraviolet (UV)

UV can cause skin injuries comparable to sun burn.

As with damage from the sun, there is an increased riskfor developing skin cancer from UV laser exposure.

Thermal Injuries

High powered (Class 4) lasers, especially from theinfrared (IR) and visible range of the spectrum, canburn the skin and even set clothes on fire.

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Laser Safety Regulations

Occupational Safety & Health Administration(OSHA)

No specific laser safety regulations, but will citesafety issues under the General Duty Clauseand will enforce the ANSI standard for lasersafety.

American National Standards Institute (ANSI)

ANSI Z136.1 (2007) Safe Use of Lasers

ANSI Z136.2-6 Specific references

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Laser Hazard Classes

The ANSI Laser

Safety standard hasdefined LaserHazard Classes,which are based onthe relative dangersassociated withusing these lasers.

Class 1

Class 1M

Class 2

Class 2M

Class 3R

Class 3B

Class 4

Most Hazardous

Least Hazardous


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Class 1 Lasers

Considered incapable of producingdamaging radiation levels during operation.

Any laser that has been renderedintrinsically safedue to the laser havingbeen completely enclosed so that nohazardous radiation can escape and causeinjury.

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Class 2 Lasers

These lasers are visiblelight (400-760 nm) continuouswave or pulsed lasers which can emit energy greater thanthe limit for Class I lasers and radiation power not above1 mW.

This class is hazardous only if you stare directly into thebeam for a long time, which would be similar to staringdirectly at the sun.

Because class 2 lasers include only visible wavelengths,the aversion reactionwill usually prevent us frompermanently damaging our eyes. The aversion reaction

refers to our tendency to look away from bright light.

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Class 1M and 2M Lasers

Classification for 1M and 2M Lasers are

identical to the requirements for 1 and 2respectively, however there is the potentialfor hazardous exposure if optical viewingaids are used.

Only requirements for Class 1 and 2 are toprevent potentially hazardous opticallyaided viewing.


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Class 3R Lasers

This class of intermediate power lasersincludes any wavelength.

Potentially hazardous under direct andspecular viewing, under very specificviewing criteria. However, injury probabilityis small.

This class will not cause thermal skin burnor cause fires.

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Class 3B Lasers

Any laser that is considered hazardousunder direct and specular viewing.

This class will not cause thermal skin burnor cause fires.

Requires a Laser Safety Officer and writtenStandard Operating Procedures.

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Class 4 Lasers

Visible and near-IR lasers will cause severeretinal injuryand burn the skin. Even diffuse reflections can causeretinal injuries.

UV and far-IR lasers of this class can cause injury to thesurface of the eye and the skin from the direct beam andspecular reflections.

Even a diffuse reflection can cause injury.

May also produce laser generated air contaminants(LGAC).

This class of laser can cause fires.

Requires written Standard Operating Procedures.


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Authority for Laser Safety on Campus

The HSE Department of PI is authority to monitorand enforce the control of laser hazards.

Specific requirements will vary according to thelaser in question and local individual in charge willusually be a faculty member or operator who hasprimary responsibility for routine work.

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Experimental Setup

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Maximum Permissible Exposure (MPE)

The Maximum Permissible Exposure (MPE) is thehighest level of radiation to which a person can beexposed without hazardous effects.

The MPE is specified in W/cm2for continuouswave lasers and in J/cm2for pulsed lasers. Thevalue depends on wavelength, exposure durationand pulse repetition frequency.

Exposure to radiation levels in excess of the MPEmay result in adverse biological effects, such asinjury to the skin and/or eyes.


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Nominal Hazard Zones (NHZ)

The Nominal Hazard Zone (NHZ)is the locationaround the laser within which a person can be

exposed to radiation in excess of the MPE. When Class 3b and 4 lasers are unenclosed, the

faculty member must establish a NHZ.

People may be injured if they are within theperimeter of this zone while the laser is inoperation.

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Non-Beam Hazards

Non-beam hazards refer to anything other than thelaser itself that can create a hazard. This type ofhazard includes:

Electrical Hazards

Fire Hazards

Laser Generated Air Contaminants (LGAC)

Compressed Gases

Chemical Hazards

Collateral and Plasma Radiation

Noise

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Non-Beam Hazards Electric Shock and Fire

Electric ShockUse caution when working on or near the

high-voltage power supplies used for high-power Class 3 and 4 lasers; there is sufficientvoltage in these power supplies to injure orkill.

FireHigh powered Class 4 lasers will easily igniteflammable materials (such as paper orflammable liquids). You musthave a fireextinguisher if you have a class 4 laser. Insome circumstances, Class 3B lasers couldalso ignite flammable liquids.


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Laser Generated Air Contaminants (LGAC)

Air contaminated due to interaction of laser beam with target materialcan result in the production of toxic chemicals.

During surgical procedures, biohazardous aerosols containingbloodborne pathogens are created.

The OSHA web site provides information on biohazardous aircontaminants produced during surgery. Visit:http://www.osha.gov/SLTC/laserelectrosurgeryplume/index.html

To prevent personnel from inhaling the LGAC and to prevent therelease of LGAC to the environment, exhaust ventilation with specialfilters may be needed.

If you are concerned that hazardous air contaminants may begenerated by your laser, contact the HSE Office.

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Chemical Hazards

Lasers use a variety of lasing mediums, and some of theseare comprised of toxic chemicals, such as dyes, solvents andhazardous gases.

Many laser dyes and solvents are toxic and carcinogenic.

A few of the hazardous gases which may be part of your lasing systeminclude chlorine, fluorine, hydrogen chloride and hydrogen fluoride.Please contact HSE for assistance with the special ventilation

precautions required for these gases.

As with all hazardous chemicals, you should review the Material SafetyData Sheet (MSDS) for the chemicals which are used in or aroundyour laser.

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Compressed Gases

Compressed gas must besecured with approved cylindersupports

Usage area must be wellventilated

Prior approval of usage shouldbe obtained

Empty containers still haveresidual gas inside, do not throwcontainers away or attempt toempty them completely
http://www.osha.gov/SLTC/laserelectrosurgeryplume/index.htmlhttp://www.osha.gov/SLTC/laserelectrosurgeryplume/index.html


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Collateral & Plasma Radiation

Collateral radiationrefers to radiation that is notassociated with the primary laser beam. This collateralradiation may be produced by power supplies, discharge

lamps and plasma tubes. This radiation can be any typeof EM radiation, from x-rays to radio waves.

High powered lasers can also produce Plasma Radiationfrom the interaction of the laser beam with the targetmaterial, especially when these lasers are used to weldmetals. Plasma radiation maycontain enough UV and/or blue light torequire additional protective measures.

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Noise

Noise generated by the laser system that isat 85 decibels or higher requires hearingprotection.

If you have reason to believe that yourlaser is creating a noise hazard duringoperation, HSE can perform noise levelmonitoring to determine whether or not thenoise associated with your laser is at thislevel.

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Control Measures

There are several measures that can be

taken to prevent injury from lasers. Thesemeasures include:

Engineering Controls

Administrative Controls

Personnel Protective Equipment

Warning Signs and Labels


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Engineering Controls

Engineering controls are measures that are incorporatedinto the laser system and are designed to prevent injuryto personnel. Engineered safety controls are preferable toPPE or Administrative controls.

Examples include Protective housings

Interlocks on Removable protective housings

Service access panels

Key control master switch (Class 3B & 4)

Viewing Windows, Display Screens, Collecting Optics

Beam path enclosures

Remote interlock connectors (Class 3B & 4)

Beam Stop or attenuator (Class 3B & 4)

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Administrative Controls

Designation of Nominal Hazard Zones (NHZ).

Written Standard Operating Procedures (SOPs)which are enforced by the HSE and faculty members.

Warning signs at entrances to room.

Training for all personnel who will be operating a laseror in the vicinity of the laser while it is in operation.(Training is also required for those using Class 2 and3R lasers.)

Allow only authorized, trained personnel in the vicinityof the laser during operation.

Class 4Laser

StandardOperating

Procedures

Administrative controls are procedures that are designed toprevent personnel from injury. Examples of administrativecontrols required for Class 3B & 4 lasers include:

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PPE for Skin

Ultraviolet lasers and laser welding/cuttingoperations may require that tightly woven fabricsbe worn to protect arms and hands. Sun screenmay also be used to provide some additionalprotection.

For lasers with wavelengths > 1400 nm, largearea exposures to the skin can result in drynessand even heat stress.

Personnel Protective Equipment (PPE) for Skinexposed to Class 3B or 4 lasers:


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PPE for Eyes

PPE is not required for class 2 or 3R lasers unlessintentional direct viewing > 0.25 seconds is necessary.

Personnel Protective Equipment (PPE) for eyes exposed to

Class 3B or 4 lasers is mandatory. Eyewear with sideprotection is best. Consider these factors when selectingeyewear:

Optical Density (OD) of the eyewear

Laser Power and/or pulse energy

Laser Wavelength(s)

Exposure time criteria

Maximum Permissible Exposure (MPE)

Filter characteristics, such as transient bleaching

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Protect Your Eyes!

In a fraction of asecond, yourvision can godark.

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Other PPE

PPE may also be required to provide

protection from hazardous chemicals andgases. Consult with HSE if you needassistance with determining the appropriatePPE for use with your laser.


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Warning Labels

Class 2:Laser Radiation Do Not Stare into Beam.

Class 2M:Laser Radiation Do not Stare into Beam orView Directly with Optical Instruments.

Class 3R:Laser Radiation Avoid Direct Eye Exposure.

Class 3B:

Laser Radiation Avoid Direct Exposure to Beam

Class 4:Laser Radiation Avoid Eye or Skin Exposureto Direct or Scattered Radiation.

Only Class 1 lasers require no labels. All other lasers mustbe labeled at the beams point of origin.

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Warning Signs

Warn of the presence of a laser hazard in the area

Indicate specific laser safety policies

Indicate the relative hazard such as the LaserClass and the location of the Nominal HazardZone

Indicate precautions needed such as PPErequirements for eyewear, etc.

All rooms with class 3R, 3B or 4 lasers must haveappropriate signs posted at all entrances. Signsmust:

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Laser Warning Signs

DANGER indicates a very dangerous situation that couldresult in serious injury or death. This sign should be used

for Class 3R, 3B, and 4 lasers.

CAUTION indicates a potentially hazardous situationwhich could cause a less serious injury. This sign shouldbe used for Class 2 and 2M lasers.

NOTICE does notindicate a hazardous situation. Thissign should only be used to make people aware of facilitypolicies regarding laser safety and/or to indicate that aservice operation is in progress.


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CAUTION Warning Sign

CAUTION

Laser Class and system go here

Type of Laser, emittedwavelength, pulse duration,and maximum output go here

Safety Instructions may

include:

Eyewear Required

Invisible laserradiation

Knock Before Entering

Do Not Enter WhenLight is On

Restricted Area

Safety Instructions go here

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DANGER Warning Sign

DANGER



Safety Instructions mayinclude:

Eyewear Required




Restricted Area

Safety Instructions go here

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NOTICE Sign for Laser Repair

NOTICESafety Instructions go here(such as Laser Repair inProgress)



Safety Instructions mayinclude:

Eyewear Required




Restricted Area

NOTICE Sign for Laser Repair


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Additional Warnings for 3B & 4Lasers

The Nominal Hazard Zone (NHZ) must bemarked so that the boundary of the NHZ is

clearly defined. An audible alarm, warning light or a verbalcountdown is required before activation.

A visible warning light should flash whenthe laser is in operation and the lightshould be readily visible through protectiveeyewear.

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Leading Causes of LaserAccidents

Unanticipated eye exposure during alignment

Available eye protection not used

Equipment malfunction

Improper methods for handling high voltage(This type of injury has resulted in death.)

Inadequate training

Failure to follow SOP

Failure to provide non-beam hazard protection.

Equipment improperly restored following service

Incorrect eyewear selection and/or eyewear failure

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Medical Surveillance

Medical surveillance may be available through thedepartment for individuals who work with oraround Class 3B and 4 lasers.

Contact PI HSE office for assistance in arranging amedical evaluation.

Currently there is no routine medical surveillancenecessary on campus for laser operators.

Emergencies and Accidents

Get medical treatment immediatelyfor all injuries andexposures - at PI Medical Clinic

PI Clinic Contact no: 22022

ASAP notify your supervisor and HSE Dept (75-473).

Take Laser Equipment unit out of service to preventinjuries to others.

Provide information during the incident investigation


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For More Information

The ANSI Z136.1 Laser Safety Standard is the bestreference to consult for laser safety information.

You can also purchase a copy of the standard through the LaserInstitute of America web site (http://www.laserinstitute.org).

Call PI HSE at 75937 if you have additional questionsabout laser safety.
http://www.laserinstitute.org/http://www.laserinstitute.org/

Documents

HSE-LS-15_Laser_Safety_Training.pdf