REVISED TO INCLUDE CONTENT FROM ANSI Z136.1-2014

ONLINE SEGMENTLASER SAFETY TRAINING

INTRODUCTION

The following topics are discussed in this presentation:• Fundamentals of laser operation and laser characteristics • Biological effects of laser radiation on the eye and skin• Significance of specular and diffuse reflections• Non-beam hazards of lasers• Laser and laser system classification• Control measures• Common causes of laser injuries and safe work practices• Responsibilities of the Principal Investigator and laser user

• Laser safety at Purdue University is managed by the Laser Safety Officer (LSO) and Radiological and Environmental Management (REM)

• Purdue’s laser safety program is overseen by the Laser Safety Committee (LSC)− This committee is mostly faculty and

safety personnel, from multiple departments.

− The LSC is empowered by Purdue Executive Memorandum D-2

LASER SAFETY AT PURDUE

• Occupational Safety and Health Administration (OSHA) is the regulatory body in the United States that oversees laser safety− OSHA adopts the American National

Standards Institute (ANSI) standards, using the General Duty Clause

− Laser regulations come from ANSI Z136.1 – American National Standard for Safe Use of Lasers

− Purdue University has committed to follow the ANSI Z136.1 standard

LASER SAFETY AT PURDUE

FUNDAMENTALS OF LASEROPERATION AND LASER CHARACTERISTICSThis section describes laser theory, characteristics, design and operation.

• LASER: an acronym for Light Amplification by Stimulated Emission of Radiation

• Lasers owe their unique properties and usefulness to a quantum mechanical process called stimulated emission.− If an electron is already in an excited state, then an incoming photon

can “stimulate” the transition of the electron to the ground state producing a second photon of the same wavelength and phase.

− These photons go on to stimulate further photon emissions, resulting in light amplification.

BASICS OF LASERS

• Laser light is:− Monochromatic – laser light consists of essentially one wavelength− Collimated – laser beams are very narrow and do not spread out

(diverge) much− Coherent – laser light waves are in phase which interferes

constructively to intensify the focal spot and make it smaller

• This means that laser light can be concentrated on the retina of the eye by as much as 100 times more than ordinary light. Thus, even relatively low levels of laser light can produce significant eye hazards.

CHARACTERISTICS OF LASER LIGHT

LASER COMPONENTS

• Active Medium – contains atoms which produce laser light by stimulated emission− Can be be a crystal, gas,

semiconductor, or dye• Excitation mechanism – a

source of energy to excite atomic electrons of the active medium to excited energy states− Can be a flash lamp or a diode

laser • Optical resonators – mirrors that

reflect the laser beam through the active medium for amplification

LASER MODES

• Lasers can be operated in various modes:

− Continuous Wave (CW) – a continuous laser beam that maintains a steady power output measured in Watts.

− Repetitively Pulsed – emits laser pulses at a particular frequency (Hertz). Laser output is measured by energy per pulse (Joules/pulse) and/or average power (Watts).

− Single Pulse – emits a single laser pulse where output is measured in energy (Joules)

𝑃𝑜𝑤𝑒𝑟 𝑝𝑒𝑎𝑘=𝐸𝑛𝑒𝑟𝑔𝑦𝑇𝑖𝑚𝑒

For example, a 1x10-3 Joule pulse with a pulse duration of 1x10-15 seconds has a peak power of 1x1012 Watts!

• The area under the pulse curves represents the energy per pulse

• As pulse duration (t) decreases, peak power increases according to the power equation

• Therefore, pulsed lasers can emit very high-intensity laser pulses.

• Q-switched lasers can achieve nanosecond pulse durations

• Mode-locked lasers can achieve femtosecond pulse durations

PULSED LASERS

BIOLOGICAL EFFECTS OF LASER RADIATION ON THE EYE AND SKINThis section outlines the health risks associated with laser beam exposure.

EYE ANATOMY

Macula: area of eye most responsible for color vision and high vision acuity. Laser induced damage to the macula will result in the greatest loss of vision.

Retina: a light-sensitive layer of tissue lining the inner surface of the eye responsible for vision. Laser induced damage to the retina will result in vision loss or impairment.

Cornea: transparent outside layer of the eye. It provides 2/3 of the eye’s focusing power.

Lens: focuses light onto the retina

LASER SPECTRUM

• Lasers operate in the ultraviolet (UV), visible, near infrared (Near IR) and far infrared (Far IR) regions of the electromagnetic spectrum.

• Visible light has a wavelength range of 400-700 nm and can be seen by the eye. This can help you avoid hazardous exposures.

• UV (190-400 nm), Near IR (700-1400 nm) and Far IR (1400-10600 nm) light cannot be seen by the eye.

EYE INJURY MECHANISM – THERMAL BURNHOW LASER INJURIES OCCUR

• Thermal Burns:− Burns caused by elevated temperature after absorption of laser energy− Injury to both eyes and skin− Occurs at all wavelengths− Dominant eye injury for continuous wave and long pulse lasers

EYE INJURY MECHANISM - MICROCAVITATIONHOW LASER INJURIES OCCUR

• Microcavitation:− Small volumes of tissue are instantly heated when short pulses are absorbed in

the retina, resulting in a steam explosion− The explosion shockwave ruptures blood vessels leading to hemorrhaging within

the retinal layers and retinal detachment. Usually results in severe loss of vision− Occurs when pulse duration is less than 5 μs for visible or 13 μs for near infrared

(NIR)

Microcavities

EYE INJURY MECHANISM - PHOTOCHEMICALHOW LASER INJURIES OCCUR

• Photochemical:− The chemical reactions in eye tissue after absorption of UV light can result in

cataracts, welder’s flash and retinal injury that is similar to sunburn on skin, except that the retina never recovers.

− Results in injuries to the cornea and lens of eye− Occurs only with wavelengths less than 600 nm− Dominant effect for blue & ultraviolet wavelengths for exposures greater than 10 s

EYE INJURIES AT VARIOUS WAVELENGTHS

Wavelength (nm) Type of Injury

180-400 Thermal, photochemical injury to cornea (e.g., photo keratitis or welder’s flash), and photochemical injury to lens (e.g. cataracts), retinal injury.

400-1400 Microcavitation to retina

400-600 Thermal, and photochemical injury to retina(Greater blue light retinal hazard at shorter wavelengths)

600-1400 Thermal injury to retina

1400-2600 Thermal injury to cornea or lens

2600-1,000,000 Thermal injury to cornea (Mostly surface burns)

IMPORTANT

• Lasers have the potential to cause permanent eye injury and loss of vision

• Laser injuries can occur very quickly (e.g., thermal burns and microcavitation), or they can occur over time (e.g. cataract formation)

• Lasers emitting in the UV, Near IR, and Far IR regions of the electromagnetic spectrum present an invisible eye hazard which people do not usually realize until their vision has been severely damaged

• Therefore, the best way to prevent injuries is by having the LSO perform hazard evaluations and applying essential laser control measures. These will be discussed later.

MECHANISMS OF SKIN INJURY

• Thermal Burns:− Surface burns (i.e., first, second and third degree burns) from high

power beams− Deeper burn penetration at 1000 nm wavelengths− Tissue vaporization by focused beams resulting in penetrating

burns. o Depending on the laser, the wound may be cauterized or it

may result in a cut and profuse bleeding

• Photochemical skin injuries:− Sunburn from scattered UV− Increased risk of skin cancer from UV exposure

THERMAL SKIN BURNS

TISSUE VAPORIZATION

A laser user’s finger after a very bad day. The injury occurred while attaching a piece of paper to the nozzle of a CO2 laser of a few hundred watts for alignment and the beam inadvertently fired. The neat circular hole in the nail is the exit. The entry hole was elongated when the individual (understandably) removed his finger. This was extremely painful.

SIGNIFICANCE OF SPECULAR AND DIFFUSE REFLECTIONThis section discusses the different ways that hazardous laser exposures can occur. Some practices for preventing these types of exposures are presented.

INTRABEAM VIEWING

• Intrabeam viewing is the situation where a collimated laser beam enters the eye, producing the smallest focused spot on the retina and the greatest eye hazard.

• Intrabeam viewing can be prevented by:− Not looking directly into or placing any part of the body into the beam path− Applying proper laser control measures − Ensuring that laser beams are not eye level (e.g. level with an individual’s

eyes while seated at a computer)

SPECULAR REFLECTION

• A specular (mirror) reflection of the beam into the eye produces the same results and same level of hazard as intrabeam viewing.

• Specular reflection can be prevented by:− Applying proper laser control measures− Remove and/or avoid using objects that could provide a reflective surface

(e.g., wrist watches, metallic tools, etc.)

DIFFUSE REFLECTION

• Much higher power (i.e. Class 4) lasers are required for a diffuse reflection to be hazardous. In this case most of the scattered light does not enter the eye. However, if the diffuse reflection is too intense, an eye injury can result.

• Diffuse reflections can be prevented by:− Applying proper laser control measures

NON-BEAM HAZARDS OF LASERS

This section describes the various health hazards that are not caused by exposure to laser light. These non-beam hazards range from minor irritation to death.

TYPES OF NON-BEAM HAZARDS

• There are multiple non-beam hazards associated with laser usage:

− Electrical hazards

− Laser Generated Air Contaminants (LGACs)

− Mechanical hazards

− Process radiation

− Pump lamp light

− Chemical hazards

ELECTRICAL HAZARDS

• Oftentimes contain high voltages and energy storage capacitors.

• This can present an electric shock hazard. Several fatalities have occurred.

• Equipment shall not be operated with protective housings removed and electrical hazards exposed.

• Only qualified personnel should work with energized laser power supplies and capacitors.

LASER GENERATED AIR CONTAMINANTS• The use of lasers for cutting, welding,

engraving, materials processing applications, and various medical procedures can generate air contaminants (e.g., smoke, fumes, particulates, and biohazards).

• Breathing these contaminants is a respiratory hazardous even if they are not composed of hazardous substances.

• Processing non-metals usually produces hazardous chemical vapors.

LASER GENERATED AIR CONTAMINANTS• Vaporizing wood and plastic products can

produce many carcinogens (e.g., benzene, formaldehyde, etc.)

• Vaporizing biological media can result in airborne biological hazards

• Radiological and Environmental Management (REM) operates an air quality program that will assist with LGAC removal (e.g. exhaust systems) or filtering (e.g., N95 and respirators).

• If you suspect that your laser may generate LGACs, please notify the LSO.

Exhaust system to remove LGACs generated by the laser engraver/cutter

LASER PROCESS RADIATION

• Certain laser applications can generate plasmas which emit bright visible and UV light.− Capable of causing the

same injuries as those from laser beams

• Protective eyewear and clothing can offer protection.

• Consult the LSO if you suspect the presence of process radiation.

PUMP LAMP LIGHT

• The intense light from laser optical excitation sources produces a white light optical hazard.

• Laser optical pumping lamps shall not be operated with protective housing removed.

• If such operation is required, consult the LSO.

LASER AND LASER SYSTEM CLASSIFICATION

This section describes the different laser classifications. Lasers are classified according to the potential hazard of the laser beam. The laser classification ranges from Class 1 (no hazard) to Class 4 (very high hazard)

CLASS 1 AND CLASS 1M

• Class 1 lasers are either:− Very low power lasers; or− Higher class lasers with the beam fully

enclosed (e.g., confocal microscopes and laser engravers/cutters)

• Class 1 lasers are incapable of causing an injury during normal use

• Beam enclosures and interlocks should not be removed or defeated

• Only qualified individuals should open the beam enclosures to perform maintenance.

• A Class 1M laser is Class 1 unless magnifying optics are used− If magnifying optics are used, Class

1M lasers pose a eye hazard

CLASS 2 AND CLASS 2M

• Class 2 lasers must:− Be visible; and− Have a maximum continuous wave

(CW) power of 1 mW, • The natural aversion response to bright

light (i.e. turning head away and/or closing eyes) is sufficient to protect an individual from eye injury

• Eye injury can occur if an individual overcomes the aversion response and stares into the beam.

• A Class 2M laser is Class 2 unless magnifying optics are used− If magnifying optics are used, Class

2M lasers pose a eye hazard

CLASS 3R (FORMERLY 3A)

• Class 3R lasers have a maximum CW power of 5 mW

• The aversion response is not adequate protection for intrabeam viewing or specular reflection.

• The only precautions required for safe use are that the laser user must avoid direct eye exposure.

CLASS 3B

• Class 3B lasers have a maximum CW power of 500 mW

• Intrabeam viewing and specular reflection of the beam is a eye hazard

• Aversion response does not protect against eye injury

• Most 3B lasers do not produce diffuse reflection hazards.

• 3B lasers may produce minor skin hazards. However, this is not usually a real concern

CLASS 4

• Class 4 lasers have a CW power of > 500 mW

• Intrabeam viewing, specular reflection, and diffuse reflection of the beam are eye hazards

• Aversion response does not protect against eye injury

• Exposure to direct beam and scattered light is a skin hazard

• May be a fire hazard

• Capable of producing LGACs

LASER CLASS IDENTIFICATION

• Laser manufacturers are required by Federal law to classify every laser that they sell.

• The laser class can be identified on a label affixed to the outer casing of a laser.

• For ‘homemade’ and unlabeled lasers, Purdue REM can classify the laser using manufacturer specifications and/or measurements with their power meter.

CONTROL MEASURES

The American National Standard for Safe Use of Lasers (ANSI Z136.1) REQUIRES the application of control measures to prevent the occurrence of harmful laser exposures. This section presents the various control measures and their required application.

TYPES OF CONTROL MEASURESLASER CONTROL HIERARCHY

• Engineering: − Should be the first line of defense against laser hazards− Generally more reliable and should be given priority

• Administrative (Procedural):− The second line of defense against laser hazards− If engineering controls are impractical or inadequate, an effective

combination of administrative and personal protective equipment shall be used.

• Personal Protective Equipment (PPE):− Last line of defense against laser hazards− Use when engineering and administrative control measures cannot

adequately prevent laser hazards

LASER CONTROLLED AREAENGINEERING CONTROLS

• Laser Controlled Area (LCA) – an area where there is potential exposure to a laser beam that could result in laser injury. − May be the entire room or an enclosure

within the room. − Only authorized users may enter a LCA

during laser operation.− LCA classification is determined by the

highest laser classification. For example, a lab containing Class 3B and 4 lasers is a Class 4 laser controlled area.

− The LSO will determine what constitutes a LCA.

This enclosure of laser curtains prevents harmful laser light from exiting. By definition, this enclosure constitutes a laser controlled area.

AREA WARNING SIGNENGINEERING CONTROLS

• Area Warning Sign – Warning sign that provides safety information. Sign must be conspicuously posted at all entryways to Class 3B and 4 laser controlled areas. REM will provide these signs. Notify REM if signs are missing, defaced, incorrect, or outdated.

PROTECTIVE HOUSING

Lasers may present an electric shock and pump lamp hazard.

Question:

How do we protect ourselves from electrical shock and pump lamp hazards?

Answer:

Protective Housing and Interlocks

Protects against electrical shock and pump lamp light exposure. There are interlocks that trip when the housing is opened, turning off the laser. Do not attempt to defeat interlocks.

ENGINEERING CONTROLS

Protective housing (interlocks are internal)

BEAM DUMPS

Class 4 laser beams are capable of injuring eyes and skin, igniting fires, and damaging valuable property.

Question:

When designing your laser setup, what is the best way to terminate high powered laser beams?

Answer:

Beam Dumps

Provide a safe method to terminate high-powered laser beams. They can be air or water cooled.

ENGINEERING CONTROLS

Beam dumps are a safe place for Class 4 laser

beams to end

EMISSION WARNING DEVICE

Many lasers emit invisible laser radiation (e.g., UV, Near IR, Far IR) which presents an invisible laser hazard since you cannot see the beam.

Question:

How do I know that the laser is emitting laser radiation.

Answer:

Laser Radiation Emission Warning Device Audio or visual device that ensures people in the LCA are aware that the laser is or about to emit laser radiation.

ENGINEERING CONTROLS

Laser Radiation Emission Warning Device

AREA WARNING DEVICE

Question:

What is the best way to inform people coming into the LCA that my laser is operating?

Answer:

Area Warning Device

Can be a visual or audible device that indicates when the laser is operating. Visual devices may be a single lamp or a laser warning sign that is illuminated or flashes when the laser is operating. If a simple light is used, a sign must be placed next to the light stating, “Laser in Use.”

ENGINEERING CONTROLS

LaserIn

Use

LASER BARRIERS AND CURTAINSStray laser beams (from intrabeam viewing, specular and diffuse reflection) can cause injury and damage valuable property.

Question:

How can I block stray laser beams resulting from misalignments and other accidents?

Answer:

Laser Barriers and Curtains

Specially designed and tested equipment rated to withstand a particular laser irradiance (e.g., 250 W/cm2 for 100 seconds)

ENGINEERING CONTROLS

LASER BARRIERS AND CURTAINS (CONT.)Laser barriers and curtains:• Come in a variety of sizes and shapes• May be freestanding (bottom), hanging, or

tabletop (right).• Substitutions must be approved by the LSO • Flammable or non laser-rated material (e.g.,

cardboard, blackout fabric, etc.) should never be used.

ENGINEERING CONTROLS

Freestanding Barriers

Tabletop Barriers

ENTRYWAY CONTROL

Class 4 lasers have the highest potential to do harm.

Question:

How else can I make it safe for people entering the LCA when using Class 4 lasers?

Answer:

Entryway Controls

Prevents the possibility of exposure to laser radiation to individuals entering the LCA. The next three slides show the three entryway controls options

ENGINEERING CONTROLS

ENGINEERING CONTROLS

1. Non-defeatable Entryway Controls− Doorway interlock is non-defeatable.

Interlocks trip when door to LCA is opened, causing the laser to power down.

− Used when there is a laser radiation hazard at the entry

− Training of authorized users only

Doorway Interlocks

Interlock Circuit

Laser Barrier

ENTRYWAY CONTROL OPTIONS

ENGINEERING CONTROLS

2. Defeatable Entryway Controls− Doorway interlock is defeatable, allowing

user into LCA without causing laser to power down.o Used when it is evident that there is no

laser radiation hazard at the entry− Training of all personnel with access− Full-height laser barrier/curtain and laser eye

protection at door

Doorway Interlocks

Interlock Circuit

Laser Barrier

ENTRYWAY CONTROL OPTIONS

ENGINEERING CONTROLS

3. Procedural Entryway Controls − No doorway interlock− Training of all personnel with

access− Full-height laser barrier and

laser eye protection at door− Visible or audible area

warning device

ENTRYWAY CONTROL OPTIONS (CONT.)

ENCLOSED BEAMENGINEERING CONTROLS

Question:

What is best thing that I can do to prevent exposure to lasers?

Answer:

Keep the laser beam enclosed through the use of:• Laser Beam Tubes • Laser Fiber Optics • Laser Enclosures

EMERGENCY STOPENGINEERING CONTROLS

Question:

In an emergency, is there a quick way to shut off Class 4 lasers?

Answer:

The red “emergency stop” button is the quickest way to shut off a laser. These buttons are installed on laser systems where laser injuries are either highly probable or severe.

ENGINEERING CONTROL REQUIREMENTSENGINEERING CONTROLS

• The table below lists the engineering control requirements per LCA classification. Those engineering controls with a SHALL requirement are NOT OPTIONAL.

Engineering Control Measures Classification3B 4

Laser Controlled Area X XLaser Warning Sign X XProtective Housing X XProtective Housing Interlocks X XArea Warning Device • XLaser Radiation Emission Warning Device • XEntryway Controls − XProtective Barriers and Curtains • •Beam Dumps − •

Legend:X Shall• Should− No Requirement

STANDARD OPERATING PROCEDURES ADMINISTRATIVE CONTROLS

Question:

What is the best way to ensure laser users know how to safely operate, maintain, and service the laser in order to avoid injury, and damage to expensive equipment?

Answer:

Standard Operating Procedures (SOP)

Step-by-step procedures for the safe operation, maintenance, and servicing of lasers and laser systems. All SOPs should be written by competent and experienced individuals, and approved by the LSO. The SOP should also specify the type of laser eye protection required.

ALIGNMENT PROCEDURESADMINISTRATIVE CONTROLS

Question:

How do I safely perform laser beam alignments? What’s the best way to guide other laser users with laser alignments?

Answer:

Alignment Procedures

Step-by-step procedures and methods for the safe alignment of laser beams. The alignment procedures should also describe methods to view invisible laser beams. Alignment procedures should be written by competent and experienced individuals.

Student using a viewing card to view beam

AUTHORIZED PERSONNELADMINISTRATIVE CONTROLS

Question:

Who is allowed to use lasers at Purdue University?

Answer:

Authorized Personnel

laser and laser systems shall only be operated, maintained and serviced by authorized personnel.• Authorization requires training, and approval from both Principal

Investigator (PI) and LSO.• Only authorized users may be present in a LCA during laser operation.• There are two classes of authorized personnel:

1. Unrestricted User: authorized to operate lasers unsupervised

2. Restricted User: requires supervision by unrestricted user or PI to operate lasers.

SAFETY TRAININGADMINISTRATIVE CONTROLS

Question:

What type of training is required to be a laser user?

Answer:

There are four types of laser training:

1. Initial Online Laser Safety Training − (This presentation)

2. Initial Classroom Laser Safety Training − Review laser safety principles and provides opportunity for questions (only required

for individuals who want to be an unrestricted user)

3. On-The-Job Training − Administered by the Principal Investigator (PI) or designee, this training is specific

to the laser, laser system, and experimental setup.− This shall include laser safety specifically for the particular laser, laser system, and

experimental setup in use.

4. Biennial Laser Safety Retraining − Periodic refresher training to maintain an appropriate level of laser safety

proficiency.

AUTHORIZED PERSONNEL REQUIREMENTSADMINISTRATIVE CONTROLS

• The requirements of becoming an authorized personnel is summarized in the following table. Those engineering controls with a SHALL requirement are NOT OPTIONAL.

Authorization Requirements User Class

Restricted Unrestricted

Submit Completed LU-2 Form X X

Online Laser Safety Training X X

Classroom Laser Safety Training − X

On-The-Job Training X X

Biennial Laser Safety Training X X

LEGEND: X Shall• Should− No Requirement

ADMINISTRATIVE CONTROL REQUIREMENTSADMINISTRATIVE CONTROLS

• The table below lists the administrative (procedural) control requirements per LCA classification. Those administrative (procedural) controls with a SHALL requirement are NOT OPTIONAL.

Administrative Control Measures Classification

3B 4

Standard Operating Procedures • X

Education and Training X X

Authorized Personnel X X

Alignment Procedures X X

LEGEND: X Shall• Should− No Requirement

LASER EYE PROTECTION PERSONAL PROTECTIVE EQUIPMENT

Question:

How can I protect my eyes from harmful laser radiation?

Answer:

Laser Eye Protection (LEP)

Specialized safety eyewear used to protect eyes from hazardous laser radiation. The proper selection of LEP is crucial to ensuring user safety. Two characteristics must be considered when selecting LEP: • Wavelength• Optical Density (OD)

LASER EYE PROTECTION PROPERTIES • Wavelength:

− The lenses contain special dyes that absorb specific wavelengths, allowing all other to pass through

− Therefore, LEP is wavelength specific; it only offers protection at specific wavelengths.

• Optical Density (OD):− The OD specifies the percent of

incident laser radiation that will be transmitted (see table)

− The OD varies with the wavelength (see figure on next page)

PERSONAL PROTECTIVE EQUIPMENT

OD Percent Transmitted0 100%1 10%2 1%3 0.1%4 0.01%5 0.001%6 0.0001%7 0.00001%

SELECTING LASER EYE PROTECTIONQuestion:

How do I properly select LEP?

Answer:

The wavelength and OD requirements for LEP are dependent on the operating parameters of the laser. Therefore, different lasers may require different LEP. There is no one-size-fits-all. • The LSO can perform calculations to

determine the wavelength and OD requirements.

• The LEP used MUST meet or exceed the wavelength and OD requirements in order to provide sufficient protection.

PERSONAL PROTECTIVE EQUIPMENT

No protection at these wavelengths

SELECTING LASER EYE PROTECTION (CONT.)• The wavelengths and ODs MUST be

INSCRIBED on the lenses or frame − LEP that don’t meet this

requirement WILL NOT provide sufficient protection. These SHALL NOT be used, but they MUST be disposed to avoid confusion.

• DO NOT use LEP that is broken or damaged. When in doubt ask the LSO.

• Before using LEP, ALWAYS ensure that the wavelength and OD requirements are met and that its in good working order.

PERSONAL PROTECTIVE EQUIPMENT

SYSTEM CHANGES

Question:

Do I need to do inform the LSO before changing the operating parameters (i.e., emitted wavelength, energy per pulse, power, etc.) of a particular laser, modifying a laser, or drastically changing a laser setup?

Answer:

Yes. These changes can increase or change the laser hazard. The LSO will need perform a short analysis of the changes to determine what controls are necessary.

PERSONAL PROTECTIVE EQUIPMENT

ARE CHEAP SUBSTITUTIONS ALLOWED?PERSONAL PROTECTIVE EQUIPMENT

Question:

I heard that polycarbonate can block UV and far IR laser light. Can I use a pair of polycarbonate safety glasses as LEP?

Answer:

No. Laser eye protection needs to be rated with the wavelengths and OD specified by the manufacturer. Polycarbonate safety glasses are not designed to protect against laser light. If cost is an issue, contact REM.

X

SKIN PROTECTIONPERSONAL PROTECTIVE EQUIPMENT

Skin injuries are really only a problem when working with Class 4 and UV lasers. Class 4 lasers can result in thermal skin burns while UV lasers can cause photochemical changes in the skin which can result in sunburns and skin cancer.

Question:

What should I do to protect my skin from laser injuries?

Answer:

Skin Protection and Protective Clothing

Offers protection to the skin and body from laser radiation (see next slide for examples).

SKIN PROTECTION (CONT.)PERSONAL PROTECTIVE EQUIPMENT

• In some cases a laboratory jacket or coat may fulfill the requirement, although tightly-woven, flame-retardant fabrics provide the best protection for Class 4 lasers.

• Most gloves will provide some protection against scattered laser radiation, although opaque, flame-retardant gloves (e.g. welder’s gloves) provide the best protection for Class 4 lasers.

• When working with UV lasers, skin protection should be used if frequent exposures are likely.

PERSONAL PROTECTIVE EQUIPMENT

• The table below lists the personal protective equipment requirements per LCA classification. Those personal protective equipment with a SHALL requirement are NOT OPTIONAL.

Personal Protective Equipment Control Measures

Classification

3B 4

Laser Eye Protection X X

Skin Protection • •

Protective Clothing • •

LEGEND: X Shall• Should− No Requirement

PPE REQUIREMENTS

COMMON CAUSES OF LASER INJURIES AND SAFE WORK PRACTICESThis section outlines common causes of laser accidents that you should avoid and/or eliminate in your laser lab. This section also outlines good practices and safe alignment practices that you should implement.

COMMON CAUSES OF LASER INJURIES• Misaligned optics and upwardly

directed beams

• Unanticipated eye exposure during alignment

• Available laser eye protection (LEP) not used

• Equipment malfunction

• Improper methods of handling high voltage

Stray laser beam from misaligned optic

COMMON CAUSES OF LASER INJURIES (2)• LEP worn not appropriate for laser in

use

• Intentional exposure of unprotected personnel

• Operators unfamiliar with laser equipment

• Lack of protection from non-beam hazards

• Improper restoration of equipment following service

Don’t assume that a pair of LEP works for a laser. Always verify that the LEP meets the OD and wavelength requirements for the laser being used. If you don’t know the OD and wavelength requirements for a laser, ask the LSO for help.

COMMON CAUSES OF LASER INJURIES (3)• Improper barriers (e.g., substituting

laser rated barriers with cardboard, blackout fabric, etc.)

• Unattended laser operation

• Failure to follow standard operating procedures (SOPs)

• Poor working conditions (e.g., long/unusual hours, poor housekeeping and ergonomics).

Proper laser barriers/curtains will be laser rated and certify compliance with ANSI Z136.7

SAFE WORK PRACTICES

• Position the laser so that it is well above or below eye level. Never place computer monitors on the same level as laser beams.

• Do not view a Class 3R (or higher) laser with optical instruments

• Operate lasers only in the area designated for their use and be certain that the beam is terminated at the end of its use path. Never allow a laser beam to escape its designated area of use.

Computer monitor is not on the same level as the laser beam

SAFE WORK PRACTICES (2)

• All stray reflections should be eliminated or blocked as near their source as possible.

• Unless the beam is entirely enclosed, always wear LEP when in the LCA and the laser is operating. Even if the laser system has been aligned, NEVER assume the system is safe.

• Do not enter a designated Class 3B or 4 laser area without approval from a qualified laser operator. Laser eye protection is required in these areas.

Stray reflections blocked with table top barriers

SAFE WORK PRACTICES (3)

• Remove all unnecessary reflective objects from the area near the beam’s path. This may include tools and jewelry.

• Always wear laser eye protection (LEP) when lasers are operating and the laser beam is not fully enclosed. − Do not remove LEP to view

computer monitors, equipment, or the experiment. Optical table free of reflective objects

and tools.

SAFE WORK PRACTICES (4)

• Never intentionally look directly into a laser. Do not stare at the light from any laser. Allow yourself to blink if the light is too bright.

• Never direct the beam toward other people

• As much as possible, enclose the beam with laser curtains/barriers, fiber optics, and laser beam tubes

SAFE LASER ALIGNMENT PRINCIPLES• Only trained personnel may align class 3B and 4

lasers, NO EXCEPTIONS!• Exclude unnecessary personnel from the laser lab

during alignments.• Where possible, use low-power (Class 3R or lower)

visible lasers for path simulation of high power visible or invisible lasers.

• Always anticipate the possibility of an uncontrolled beam or reflection and protect yourself and others by using beam barriers and wearing appropriate LEP.

• When aligning invisible beams, use beam display devices such as UV and IR viewers or laser viewing cards to locate laser beams.

SAFE LASER ALIGNMENT PRINCIPLES (CONT.)• Perform alignment tasks using high-power

lasers at the lowest power level possible.• Place table barriers behind optics to terminate

beams that might miss mirrors during alignment.

• Locate and block all stray reflections before proceeding to the next optical component or section

• Be sure all beams and reflections are properly terminated before high-power operation

• NEVER remove laser eye protection (LEP) to view the laser beam. Instead use laser viewing cards and other techniques that can emit visible light, not filtered out by the LEP

For example, let’s assume we are aligning a 532 nm (green) laser. Our LEP will filter all 532 nm light, making it impossible to see the beam during alignment. However, if we use the laser viewing card above, the 532 nm beam will be absorbed by the photosensitive region and 600-750 nm (red) light will be emitted. The red light will not be filtered by our LEP, making it possible for us to view the beam while wearing our LEP.

RESPONSIBILITIES OF THE PRINCIPAL INVESTIGATOR AND LASER USERThis section explains the responsibilities the Principal Investigator (PI) and laser user in maintaining a safe laser environment.

PI RESPONSIBILITIES

• Complete laser safety training• Will not permit operation of a laser unless control measures are

adequate.• Issues appropriate instruction and training material on laser hazards

of their specific laser• Ensures that all laser users have completed the laser safety training

provided by REM, the on-the-job training, and have submitted a LU-2 form prior to working with lasers.

• Ensures that operation of the laser meets all safety requirements, both for the lab members and anyone else who may enter the lab (e.g., custodial staff, visitors, etc.)

• Inform REM when the area warning sign posted at the laser control area entrance is no longer accurate

PI RESPONSIBILITIES (2)

• Notifies the LSO of any known or suspected injuries− If necessary, ensures appropriate medical attention is received

• Will not permit operation of a new or modified Class 3B or 4 laser under his/her authority without LSO approval.

• Shall ensure that SOPs are available for each laser.• Ensure every laser is registered with REM by completing the LS-1

form• Ensure every laser lab is registered with REM by completing the LF-1

form

LASER USER RESPONSIBILITIES

• Complete laser safety training prior to use

• Maintain a safe laser environment by adhering to all laser safety principles, rules and practices

• Inform your PI and REM of any safety hazards or concerns

• Inform REM when the area warning sign posted at the laser control area entrance is no longer accurate

LASER USER RESPONSIBILITIES (2)• Ensure all control measures (i.e., engineering, administrative

procedural, and PPE) are in place and/or activated prior to using the laser

• Ensure that all individuals within the lab are aware that the laser is in use, and follow safe laser practices.

• Energize or work with lasers only when authorized to do so.

• Notify supervisor or LSO in case of potential accident or injury.

PRIMARY RESPONSIBILITY FOR SAFETY Question:

Who has primary responsibility for laser safety any time a Class 3B or Class 4 laser is operated?

Answer:

The person operating the laser always has the primary responsibility for all hazards associated with laser use

You have the duty to report unsafe conditions and practices to the Principal Investigator (PI). If the situation is not resolved within a reasonable time, contact REM.

SYSTEM CHANGES

Question:

Do I need to do inform the LSO before changing the operating parameters (i.e., emitted wavelength, energy per pulse, power, etc.) of a particular laser, modifying a laser, or drastically changing a laser setup?

Answer:

YES! These changes can increase or change the laser hazard. The LSO will need perform a brief analysis to determine what control measures are necessary.

PERSONAL PROTECTIVE EQUIPMENT

MAINTAIN A SAFE LAB ENVIRONMENT• Safety should never be sacrificed for

convenience, or to save time and money.− You can do breakthrough research without

compromising on safety. REM can help! • Laser accidents can result in laser lab closures,

and a loss of thousands of dollars of research grants.

• Laser safety equipment can be expensive. However, REM has a cost sharing program which can pay up to 50% of the total cost.− Must receive LSO’s approval prior to

purchase.− REM also has equipment that can be

loaned.

INJURY

• If a laser-related injury occurs:− Turn off the laser system− Contact medical personnel (call 911). Inform them of the accident.− If injured personnel requires medical assistance, don appropriate

personal protective equipment (e.g. gloves), and provide minimum assistance, as needed. Ensure someone remains with the victim until medical personnel arrive

− Inform REM (765-494-6371)− Complete an incident report and a First Report of Injury.− If a suspected or actual laser-induced injury occurs, a medical

surveillance must be performed as soon as possible, but no later than 48 hours after the incident

− Do not operate the laser again until the LSO has evaluated the incident and corrective actions have been taken.

• If a fire starts in the laser controlled area:− Turn off the laser system− Sound the fire alarm− Contact fire department (call 911) and inform them of the incident− If the fire has gone out, call the Purdue University Fire Department

(PUFD) at the non-emergency number (765-494-6919)− Evacuate area− Contact REM (765-494-6371)− Complete incident report

FIRE

CONTACT INFORMATIONREM LASER SAFETY STAFF

• Zach Tribbett, Laser Safety Officer− 765-494-1478− ztribbet@purdue.edu

• Matthew Tang, Deputy Laser Safety Officer− 765-494-2721− mmtang@purdue.edu

• Jerry Gibbs, Laser Training and Authorization Information− 765-494-0207− jjgibbs@purdue.edu

• Main Office− 765-494-6371

Click here to begin the test.

• This concludes the PowerPoint portion of the training.• Complete the test indicated below. You must have 75% of correct

responses to pass.− Your results will be emailed to you, and will constitute as your certification

of your successful completion of the online portion of your training, if you have passed.

• Submit a completed Form LU-2 (make sure that both you AND your Principal Investigator have signed the form), and send through campus mail to: Zach Tribbett/REM/HAMP

END OF TRAINING MODULE