EHLS Radiation Safety Contact Numbers EHLS Main Line (713) 7435858 - - PDF document

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Radiation Safety Office Environmental Health & Life Safety Department University of Houston

713‐743‐5858 www.uh.edu/ehls

ONLINE HANDOUTS: www.uh.edu/ehls/train/course‐info/eh23

EHLS Radiation Safety Contact Numbers

• EHLS Main Line

(713) 743‐5858

• UHPD (Emergencies)

(713) 743‐3333

• Radiation Safety Officer

(713) 743‐5867 (RSO)

• Assistant RSO

(713) 743‐5870

• Safety Specialist

(713) 743‐5860

WHY ARE YOU HERE?

1. COMPLIANCE – State of Texas regulations 2. SAFETY – keep yourself and others safe from laser radiation effects 3. KNOWLEDGE – Ignorance leads to unsafe work practices

Introduction

• High powered lasers are capable of causing severe injuries
• However, they are used for teaching and research at UH
• Possession and use is regulated under a Certificate of Registration

from Texas Department of State Health Services

• Laser Safety Program assists with safety and regulatory compliance
• Laser Safety Course provides safety education to help users work

safely with high powered lasers and maintain compliance with regulations governing laser usage.

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Course Outline

• Introduction & Course Objectives
• Laser Safety Program at University of Houston
• Basics of Lasers and Laser Light
• Laser Hazard Classification
• Hazards Associated with Lasers (Laser Beam Injuries)
• Laser Safety Regulations and Standards
• Laser Hazard Analysis & Laser Control Measures
• UH Laser Program Requirements (Administrative Controls)
• Basic Rules Working with Lasers

REGULATORY AGENCIES

• Texas Department of State Health Services (DSHS)

(Agreement State)

• Occupational Safety and Health Administration (OSHA)
• Food and Drug Administration (FDA)
• Environmental Protection Agency (EPA)
• Texas Commission on Environmental Quality (TCEQ)
• Nuclear Regulatory Commission (NRC)

UH RADIATION SAFETY MANUAL UH RADIATION SAFETY MANUAL

http://www.uh.edu/ehls/research‐ lab/radiation‐safety/manual/ Required reading for all Laser Principal Investigators and Users. Describes the Laser Safety Program at the University of Houston. Assists personnel, students, and management to understand and comply with Texas State laser regulations. Not a fully comprehensive reference. Consult the Laser Safety Officer for further advice.

Laser Safety Program

• Sets forth controls and safety guidelines for research and teaching using

lasers

• Organization:
• VC/VP of Research & Technology Transfer
• Radiation Safety Committee
• Laser Safety Officer
• EHLS Radiation Safety Staff
• Principal Investigators (PIs) & Authorized Users (AUs)
• Laser registration, Training requirements for AUs and PIs
• Program Enforcement for Non‐compliance

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TRAINING REQUIREMENTS

• Completion is not enough to become an Authorized User and start laser work.
• You must be specifically added by your Principal Investigator to the Laser

Subregistration!

• Refresher Trainings – Required annually for all PIs and AUs for lasers. Course is

available online at www.uh.edu/ehls/training/eh23w/

• All PIs and AUs of lasers MUST attend

and pass the UH classroom course EH23‐ Laser Safety.

• Test ‐ Requires at least 70% to pass.

NOTICE: The online UH General Lab Safety Course (EH06) is also a requirement for ALL lab workers at UH! http://www.uh.edu/ehls/training/eh06/

PI RESPONSIBILITIES

• Enforce laboratory safety requirements
• Inform laboratory personnel of potential hazards
• Adopt and post written safety guidelines (SOPs) in the laboratory, as necessary.
• Ensure laboratory personnel complete required training.
• Provide necessary personnel protective equipment (PPE).
• Ensure laser is used properly.
• Provide prompt notifications to EHLS Radiation Safety in case of:
• Spills, incidents, or accidents
• New or missing lasers (procurement, donations, disposal, etc.)
• Authorized User additions, deletions, or transfers
• Laboratory relocation, additions or deletions
• Wavelength or power changes/ proposed modification to lasers
• Laser procedure changes

AU RESPONSIBILITIES

• Wear and appropriately store laser safety glasses.
• Complete refresher laser safety training on an annual basis.
• Report any unusual events to your PI and/or EHLS

immediately.

• Work safely with the laser you are

approved to use at approved labs.

• Comply with all laser regulations,

and follow laser SOPs.

LASER PERMIT PROCESS

PI notifies LSO of intent to use Laser PI completes application for Laser Sublicense PI submits application to RSC (via LSO) Interim or final RSC approval

• btained

PI facilities/labs setup for Laser use Final Installation Review for approval

• All laser use at the UH must be approved by the RSO and authorized by the RSC.
• Subregistration application must include all lasers, user names, and locations, intended

use procedures.

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LASER PERMIT PROCESS

• Authorized PIs making changes to their Laser Sublicense must submit a Sublicense Amendment

Form for review by the RSO.

• The Laser Safety Officer submits all amendments to the Radiation Safety Committee for

approval.

• Anyone not trained AND listed on the Laser Permit MUST NOT be

allowed to work with Class 3B or 4 Lasers for any reason!

• Add/delete a new laser use lab
• Move laser use to different lab

Location Changes

• Add a new Authorized User
• Delete an Authorized User

User Changes

• Add a laser
• Delete a laser

Laser Changes

• Implement a new experiment

process for the laser

Procedure Changes A M E N D M E N T

BASICS OF LASERS AND LASER LIGHT

LASER ACRONYM WAVE NATURE OF LIGHT

 Wavelength Red: = 700 nm Blue: = 400 nm Light is an electromagnetic wave. Different wavelengths in the visible spectrum are seen by the eye as different colors.

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ELECTROMAGNETIC SPECTRUM

Lasers operate in the ultraviolet, visible, and infrared portions. Lasers in each spectral region present unique safety challenges

CHARACTERISTICS OF LASER LIGHT

MONOCHROMATIC DIRECTIONAL COHERENT

The combination of these three properties makes laser light more intensely focused than ordinary light

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HIGH INTENSITY

These properties make laser light different from the output of ordinary light sources.

Laser Light Properties

Divergence When 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. Monochromatic Laser light is very close to being monochromatic. The term “monochromatic” means

• ne color, or one wavelength, of light. Actually, very few lasers produce only one

wavelength of light. Coherence Coherence 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 Intensity Laser light can be very intense, more than normal light, i.e. higher energy and power.

Safety View of Laser Light Characteristics

• Each laser light characteristic reduces the size of the focused spot.
• Monochromatic light focuses better than light of multiple wavelengths.
• The more directional a beam is, the smaller the focal spot.
• Coherent light interferes constructively to intensify the focal spot
• The lens of the eye concentrates laser light on the retina by as much as 100

times more than ordinary light.

• Thus, relatively low levels of laser light can produce significant eye

hazards.

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BASIC LASER COMPONENTS

LASER COMPONENTS

ACTIVE MEDIUM Solid (Crystal) Gas Semiconductor (Diode) Liquid (Dye) EXCITATION MECHANISM Optical Electrical Chemical OPTICAL RESONATOR HR Mirror and Output Coupler The Active Medium contains atoms which can emit light by stimulated emission. The Excitation Mechanism is a source of energy to excite the atoms to the proper energy state (PUMP) The Optical Resonator reflects the laser beam through the active medium for amplification.

High Reflectance Mirror (HR) Output Coupler Mirror (OC)

Active Medium

Output Beam

Excitation Mechanism Optical Resonator

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Mechanisms of Stimulated Emission

Under certain circumstances, a photon incident upon a material can generate a second photon of

• Exactly the same energy (frequency), Phase, Polarization, Direction of

propagation

• In other words, a coherent beam resulted.

˜ Albert Einstein, 1917

Stimulated Emission

Excited Atom Incident Photon Stimulated photon‐ same wavelength, same direction and in phase

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STIMULATED EMISSION

Incident Photon Excited Atom

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Stimulated Photon same wavelength same direction in phase Incident Photon

Population Inversion

Population Inversion is the precondition for the light amplification which occurs in a LASER Since the emitted photons have a definite time and phase relation to each other, the light has a high degree of coherence. The process of attaining a population inversion is called pumping and the objective is to obtain a non-thermal equilibrium.

LASER COMPONENTS (RECAP)

ACTIVE MEDIUM Solid (Crystal) Gas Semiconductor (Diode) Liquid (Dye) EXCITATION MECHANISM Optical Electrical Chemical OPTICAL RESONATOR HR Mirror and Output Coupler The Active Medium contains atoms which can emit light by stimulated emission. The Excitation Mechanism is a source of energy to excite the atoms to the proper energy state (PUMP) The Optical Resonator reflects the laser beam through the active medium for amplification.

High Reflectance Mirror (HR) Output Coupler Mirror (OC)

Active Medium

Output Beam

Excitation Mechanism Optical Resonator

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Laser Outputs

• Continuous Wave (CW) –output fairly constant with time
• Pulsed Lasers‐More hazardous from high peak power of the pulse.

Shorter pulses result in higher peak powers and greater hazards.

• Q‐switched lasers –peak powers of few Megawatts
• Mode‐Locked Laser Pulses‐ the technique of active or passive mode

locking is applied, emitting a periodic train of ultrashort pulses. Powers of Terawatts of more

• Repetitive Pulsed Laser‐ scanning lasers operating at fixed (or

variable) pulse rates

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• Output

remains fairly constant with time

• degrades

with long term use

• Normal pulse

lasers typically have peak powers

• f a few

kilowatts.

• Q‐switching:

delivers energetic short (but not ultrashort) pulses from a laser

• Q‐Switched

lasers often have peak powers of a few megawatts. Mode‐locked laser pulses can have powers of terawatts or more.

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REPETITIVE PULSED LASER POWER AND ENERGY

max = t Qp Qp = PRF avg PRT: Pulse Repetition Time PRF: Pulse Repetition Frequency PRF = PRT 1 = PRT t max avg TIME (s) Peak Power Average Power POWER (W) max avg PRT t Qp

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Laser Power and Energy

• The average power of a repetitive pulses laser (Watts) can be

measured with a power meter.

• The pulse duration of an individual pulse (seconds) can be measured

with a photodiode and an oscilloscope.

• The pulse repetition frequency (Hertz) can be determined by

measuring the pulse repetition time and finding the inverse.

• The energy per pulse (Joules) is determined by dividing the average

power by the PRF.

Examples

A laser has an average power of 100 W, a PRF of 10 Hz, and a pulse duration of 1 ms. The energy per pulse is 10 J. (average power divided by the PRF.) The peak power is 10 KW. (average power divided by PRF)

Commonly Used Lasers

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HELIUM-NEON GAS LASER

Laser-Professionals.com Courtesy of Metrologic, Inc.

Gas lasers use gas atoms in a tube as an active medium. Excitation mechanism ‐ usually an electric current through the gas. The current excites gas atoms to the right energy level for lasing to occur. Mirrors (Optical Resonator) on each end of the tube are aligned to reflect the laser beam through the active medium

SOLID STATE LASER

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High Reflectance Mirror (HR) Output Coupler Mirror (OC) Elliptical Reflector Power Supply Solid State Rod Arc or Flash Lamp

Single Lamp Double Lamp

Active Medium‐ Solid Crystalline rod containing the lasing atoms Excitation Mechanism‐ Flash lamp (Pulsed output) or Arc lamp (Continuous Output) Optical Cavity‐ High reflector mirror and an Output coupler

Rear Mirror Adjustment Knobs Safety Shutter Polarizer Assembly (optional) Coolant Beam Tube Adjustment Knob Output Mirror Beam Beam Tube Harmonic Generator (optional) Laser Cavity Pump Cavity Flashlamps Nd:YAG Laser Rod Q-switch

(optional) Courtesy of Los Alamos National Laboratory

NEODYMIUM YAG LASER

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Active medium ‐ crystalline rod made of Yttrium Aluminum Garnett (YAG) with about 0.5% of the rare earth metal neodymium (Nd) included as an impurity. The Nd atoms do the lasing. The transparent YAG crystal holds the Nd atoms in place at the necessary density. Excitation Source: Arc lamps produce constant pumping and continuous beams. Flash lamps produce pulsed beams.

Nd‐YAG LASER

• Cooling the rods is always important in Nd:YAG lasers
• Lamp‐pumped solid state lasers: water cooled
• Lower power, diode pumped solid state (DPSS) lasers: air ‐cooled
• Welding‐ pulsed Nd:YAG with pulse durations of a few milliseconds
• “frequency doublers”‐ some Nd:YAG lasers have to change the laser

wavelength from 1064 nm (near IR) to 532 nm (green light).

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LASER SPECTRUM-where they operate

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 Radio violet waves waves waves waves Wavelength (m) Wavelength (nm) Nd:YAG 1064 GaAs 905 HeNe 633 Ar 488/515 CO2 10600 XeCl 308 KrF 248 2 Nd:YAG 532

Retinal Hazard Region

ArF 193 Communication Diode 1550 Ruby 694 Laser-Professionals.com Alexandrite 755

Safety Remarks

• Visible: 400‐700 nm

ability to see this light helps avoid hazardous exposures.

• Near infrared: 700 – 1400 nm

cannot be seen because the retinal receptors do not work at these wavelengths. The optical elements of the eye transmit the NIR and focus these wavelengths on retina. This produces an invisible retinal hazard and potential for eye injury.

• Several of the most useful lasers operate in Visible and NIR regions
• Most stringent eye safety precautions required for these lasers.

Safety Remarks

• Far infrared: 1400‐10600 nm
• completely absorbed before any of the light reaches the retina.
• This protects the retina from damage.
• These wavelengths can damage other parts of the eye, but the absorption is

spread over a larger area resulting in a larger allowed exposure.

• Ultraviolet: 180‐ 400nm
• has potential for photochemical damage to both eyes and skin.
• must be controlled to avoid long term hazardous exposures at low levels.

Safety Remarks

• UVA Rays (Ultraviolet A) easily remembered as "UV Aging rays”: cause of long term skin

damage & photo‐aging ‐ premature aging, wrinkles and sun spots.

• UVB Rays (Ultraviolet B) often referred to as "UV Burning rays”: cause of sunburn. Unlike

UVA, they have different strengths year round. UVB rays are the common cause of most skin cancers.

• UVC Rays ‐ (Ultraviolet C) is the strongest and most deadly of solar rays, however the ozone

layer stops these from reaching the Earth

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LASER CLASSIFICATION

• Class I: no beam hazard
• Class II: no realistic hazard (optical aids, longer exposure time)
• Class IIIa:
• CAUTION label: normally no eye hazard within 0.25s; may present hazard via

magnifying optics

• DANGER label: may exceed MPE in 0.25s; still low hazard
• Class IIIb: Hazardous to view directly or specular reflection; normally

no diffuse reflection or skin hazard

• Class IV: Hazardous to view beam or specular or diffuse reflection; also

skin hazard & fire hazard. Most health care laser systems are Class 4

IEC Laser Classification

• Lasers manufactured overseas or sold internationally may be labeled

with slightly different International Electrotechnical Commission (IEC) classification scheme

• ANSI Z136 Standards has adopted IEC classification scheme thus:
• IEC Class 1 & 1 M: similar to Class 1
• IEC Class 2 & 2M: similar to Class 2
• IEC Class 3R: similar to Class 3a
• IEC Class 3B: same as Class 3b
• IC Class 4: same as Class 4

Laser Registration

• Class 3b lasers are rated at 5 mW to 500 mW
• Class 4 lasers have power above 500 mW
• Class 3b and 4 lasers at UH must be registered with the State of Texas

via Radiation Safety Office

• High power = Higher hazards
• Other laser classes : registration not required. Use with caution,

especially with magnifying optics.

Do not use lasers on humans‐ It is the law

Signal Words on Laser Labels

• CAUTION

 Class 2 and 3a lasers that don’t exceed appropriate MPE

• DANGER

Class 3a that exceed appropriate MPE “All” Class 3b and 4

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Class 2

• LASER RADIATION‐DO NOT STARE INTO BEAM

Class 3a

• LASER RADIATION‐DO NOT STATE INTO BEAM OR VIEW DIRECTLY

WITH OPTICAL INSTRUMENTS

Class 3a (above MPE)

• LASER RADIATION‐AVOID DIRECT EYE EXPOSURE

Class 3b

• LASER RADIATION‐ AVOID DIRECT EYE EXPOSURE

Class 4

• LASER RADIATION‐ AVOID EYE OR SKIN EXPOSURE to DIRECT or

SCATTERED RADIATION

Additional Information on Labels

Laser Product vs. Laser Systems

Laser Product

• any device that incorporates a

laser, or is intended to incorporate a laser

• Some laser products have

additional special requirements depending on their intended

• use. e.g. lasers used for

lightshows or information display

Laser System (laser)

• the optical head and power

supply used together to generate laser light

• A laser system is an integral part
• f every laser product
• Laser systems and laser products

are regulated differently

Don’t Purchase Unclassified Lasers (FLPPS)

• Certification‐ a statement on each laser product indicating that the

product is in compliance with the legal requirements for laser products

• All lasers must be certified by manufacturer
• Imported products must also meet above requirements
• Laser Classification Regulations ‐ enforced by the Center for Devices

and Radiological Health (CDRH) of the U.S. Food & Drug Administration

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Laser Protection Terminologies

• MPE [Maximum Permissible Exposure]‐ laser radiation level that will

not cause hazardous or adverse effects to the exposed person’s eye or skin

• AEL‐ The maximum accessible emission level permitted within a

particular laser hazard class; e. g. Class 3b less than 500 mW

• NHZ [Nominal Hazard Zone]‐ The space or region within which the

potential exposure exceeds the applicable MPE.

NOMINAL HAZARD ZONE

Intrabeam Nominal Hazard Zone Diffuse Reflection Nominal Hazard Zone

Laser Hazard Evaluation

• Hazard evaluation must consider Beam & Non‐beam hazards
• Eye & skin, wavelength and output, MPE in units of energy or power…
• Environmental factors where the laser is used (electrical, fire, etc..)
• Personnel that will use the laser or be directly exposed to laser radiation
• Personnel that may be around the vicinity, but not working with the laser
• Knowledge of MPE, NHZ, laser classification, etc. allows for proper

hazard classification and control measures.

• Registration of Class 3b and 4 lasers due to high hazard

HAZARDS ASSOCIATED WITH LASERS

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Hazards Associated with Lasers

Lasers cause injury in two different ways

• Biological Effects of Laser Radiation
• Injury to the Eyes and Skin from direct laser beam
• Non‐Beam Hazards‐ those arising from factors other than direct

human exposure to a laser beam e.g. Fire, electrical, chemical, mechanical, etc.

Biological Effects of Laser Radiation

• Dependent upon
• Wavelength
• Output Energy (J) or Power (W)
• Exposure Duration
• For pulsed lasers, pulse characteristics‐pulse duration, energy and repetition

rate

• Radiant Exposure (Jcm‐2) or Irradiance (Wcm‐2)

Radiant Exposure [H, in J/cm²] – Energy per unit area; like “dose”; appropriate for photochemical effects & pulsed lasers Irradiance [E, in W/cm²] – Power per unit area; like “dose rate”; appropriate for thermal effects

Photochemical Effects

• Examples: Welder’s flash (Photokeratitis), cataracts, etc.
• Photochemical injuries occur because high energy photons break

molecular bonds inside living cells

• Photon absorption excites molecules, which may react to form

unwanted chemical products, causing erythema and vesiculation (formation of vesicles, blistering)

• Most photochemical tissue effect are cumulative; dependent on total

laser energy absorbed.

Thermal Effects on Biological Tissue

• Thermal injuries are caused by heating of the tissue as a result of the

absorption of laser energy

• Occur at all wavelengths, but very predominant in the infrared region
• Laser energy absorption heats up tissue‐ denaturing protein
• It depends on the energy absorption rate (power) compared to the

tissue’s ability to dissipate heat

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EYE INJURIES EYE INJURIES

Aversion Response (Blink reflex)

• For visible laser beams (400‐700 nm), aversion response (blink reflex

with movement of the eye and head) limits exposure duration to approximately 0.25 seconds

• When exposed to a laser,
• do not deliberately overcome aversion response;
• never stare into a laser beam

WARNING!!!!!!!!!!!!!!!!

• Aversion response offers no protection from UV and IR lasers
• Invisible lasers require special precautions

TYPES OF LASER EYE EXPOSURE

EYE

INTRABEAM VIEWING LASER DIFFUSE REFLECTION LASER

SCATTERED LIGHT MIRROR

SPECULAR REFLECTION LASER

REFLECTED BEAM ROUGH SURFACE

Eye Structure & Ocular Penetration by Wavelength

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• Portion of eye damaged is wavelength dependent
• Anterior portion

Cornea sensitive to very short UV (<400 nm) and long IR range (10600 nm) Iris & lens sensitive to wavelengths between 315‐400 nm

• Posterior portion

Retina damage from lasers in visible & invisible range, e.g. Ruby 694.3 nm, HeNe (632.8 nm), Ti:Sapphire (650‐ 1100 nm)

Biological Effects

25  Photo courtesy of U S Air Force

THERMAL BURNS ON PRIMATE RETINA

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0.25 s exposure to a 10 mW green laser beam

Photo courtesy of U S Army Center for Health Promotion and Preventive Medicine Photo courtesy of U S Army Center for Health Promotion and Preventive Medicine

EYE INJURY BY Q‐SWITCHED LASER

Retinal Injury produced by four pulses from a Nd:YAG laser range finder.

20 ns , 15 mJ pulse energy

PHOTOCHEMICAL INJURY

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MULTIPLE PULSE RETINAL INJURY

THERMAL BURNS ON HUMAN RETINA

Safety Implications

• Maximum human aversion response to bright light is always less than

0.25 s.

• Some lasers are invisible to the eye, which makes them dangerous

since your blink reflex will not happen

SKIN INJURIES

How Does Laser Light Affect the Skin?

Different wavelengths of light penetrate the skin in different ways.

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Skin penetration & Color of Light

• Skin layers‐ stratum corneum,

epidermis & dermis in different colors

• Colors of light and wavelength
• UVB laser (295 and 308 nm)
• UVA laser (365 nm)
• Blue laser (405 nm)
• Green laser (532 nm)
• Red laser (635 nm)

Source: Mustafa, F. H. and M. S. Jaafar. "Comparison Of Wavelength‐Dependent Penetration Depths Of Lasers In Different Types Of Skin In Photodynamic Therapy". Indian Journal of Physics 87.3 (2012): 203‐

• 209. Web. 14 Mar. 2017.

Source: Mustafa, F. H. and M. S. Jaafar. "Comparison Of Wavelength‐Dependent Penetration Depths Of Lasers In Different Types Of Skin In Photodynamic Therapy". Indian Journal of Physics 87.3 (2012): 203‐

• 209. Web. 14 Mar. 2017.

Skin Hazards

• Ultraviolet “Sunburn”‐ Immediate Effects
• Erythema (reddening) from UV‐B and UV‐C
• Sunburn from excessive levels of actinic (short wavelength) UV‐radiation
• Ultraviolet Radiation Delayed Effects
• Skin cancer from long‐term level (chronic) UV exposure
• Accelerated skin aging from UV‐A
• Thermal Skin burns
• Typical of IR lasers, e.g. CO2 laser (10600 nm)
• Micro‐cavitation: thermal effect from short laser pulse focused onto the skin

(dermal blood vessels rupture)

SKIN BURN FROM CO2 LASER EXPOSURE

Accidental exposure to partial reflection of 2000 W CO2 laser beam from metal surface during cutting

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NON BEAM HAZARDS

Non Beam Hazards (NBH)

• Four types: Hazards arising from:
• Exposing materials to beam (e.g. fire)
• Exposure to laser system components (e.g. capacitors),
• Lasing media (e.g. dye, hazardous or compressed gas),
• How the system is used (e.g. mechanical, limited space, etc.)
• Laser beams RARELY injure people, non beam hazards often do.
• NBH cause most serious laser‐related injuries than DIRECT beams
• NBH incur greater regulatory compliance burden than beam hazards
• Controls for NBH are different from direct beam hazards

Physical Agents

• Electrical Hazards
• Electric shock/ electrocution
• Resistive Heating
• Electric Spark Ignition of Flammable Materials
• Arc Flash
• Potential Problem Areas
• Uncovered & improperly insulated terminals; non‐grounded
• Electrical Power warning lights not clearly visible
• Lack of proper training (e.g. electrical safety, etc.)
• Failure to properly discharge ground capacitors
• No lock out‐tag out standard or procedures
• Excessive wires and cables on the floor creating fall, trip or slip hazards

Non‐Laser Radiation Hazard

• X‐ray from electronic components
• high‐voltage vacuum tubes > 15kV
• plasmas from pulsed laser beams with peak irradiance > 1016 Wcm‐2
• Collateral UV from laser discharge tubes and pump lamps, etc.
• Microwave radiation, ELF and Static Magnetic Fields from power

supplies, and associated electrical equipment

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Fire Hazards

• Class 4 laser beams present a fire hazard
• Possible ignition hazard at above 0.5 W (per NFPA 115)
• Under some situations where flammable compounds exist, it is

possible that fires can be initiated by Class 3b lasers

• Laser barriers designed to offer a range of protection must be used to

block the laser beam from exiting the work area during certain

• perations

Chemical Agents

• Laser Generated Airborne Contaminants (LGAC)
• Compressed gases
• Require appropriate safety measures
• Sensors and alarms for hazardous gas cabinets e.g. HF
• Laser dyes and solvents
• Chemical agent control measures
• Exhaust Ventilation
• Process isolation
• Respiratory protection, etc.,…

Others

• Biological Agents‐ bacteria, viral organisms, infected tissue being

imaged

• Human factors:
• Ergonomics‐ poor workstation layout, poor illumination, etc.
• limited work space e.g. working near high voltage equipment
• work patterns‐extended or extensive work hours, fatigue, lone worker
• Noise e.g. high levels from pulsed excimer lasers.
• Fiber optic fragment hazards can cause allergy, irritation of airways
• Nanoparticles‐ increasing use of nanoparticles
• Explosion hazards‐ high filament lamps, capacitor banks, etc.

LASER CONTROL MEASURES

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Safety Standards & Regulations

• International
• International Electrotechnical Commission (IEC)
• US
• FDA/CDRH‐ U.S. Federal Laser Product Performance Standard (FLPPS) in CFR

21 Subchapter J, Part I sections 1002 – 1040.11 requires all lasers, laser systems and laser products and manufacturers to comply with specific laser regulations

• OSHA General Duty Clause requires employers to protect employees against

recognized safety hazards. OSHA Construction standard (29 CFR 1926) addresses lasers

Safety Standards & Regulations (cont’d)

• ANSI Z136 Standards –guidance for safe use of lasers & laser systems
• Incorporated by reference by various state regulations
• 25 Texas Administrative Code, Chapter 289‐ Registration and

Radiation Safety Requirements for Lasers and Intense‐Pulsed Light Devices

• UH Radiation Safety Manual – Laser Safety Section

Control Measures‐ Engineering

• Enclosures (Protective Housing) for all classes of lasers
• Interlocks on removable protective housing
• Service access panel‐either interlocked or with appropriate warning label on

panel

• Equipment labels‐ appropriate warning labels required
• Key Control (Class 3b & 4): physical key or computer password
• Viewing windows and diffuse display screens‐ must maintain laser

radiation at viewing position at or below applicable MPE

• Facility window protection‐ transmitted levels at or below MPE

Laser Safety Curtains

THIS KIND: NOT THIS KIND:

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Control Measures‐ Engineering (cont.)

• Protective Barrier and Curtains‐ can block or filter laser radiation
• Collecting Optics‐ e.g. lenses, telescopes, microscopes used with

lasers shall incorporate interlocks, filters, attenuators to maintain laser radiation at or below MPE

• Beam Path Controls can be accomplished as follows:
• Enclosed beam path‐ entire beam enclosed‐ no further controls needed.
• Limited open‐ requires hazard analysis to ensure proper controls
• Fully open‐ requires hazard evaluation to determine appropriate controls

Warning Systems

• Purpose: to ensure persons about to enter the laser controlled area

are aware that a laser in on or about to start emission

• These could be:
• Area warning device‐ must be visible prior to entry to the area for Class 3b or

Class 4 lasers

• Visible warning device, e.g. single lamp or lighted laser warning sign that is

lighted or flashes when laser is operating

• Audible warning device‐ may be used to warn individuals in a greater space

beyond immediate laser area. Works best for visually impaired

Laser Controlled Area‐Restricted Access

• Access to Class 3b and 4 lasers must be
• secure
• allow for rapid egress by laser personnel at all times
• allow admittance to the controlled area under emergency conditions.
• Class 4 laser controlled area shall incorporate one of the following:
• Non‐defeatable area interlocks to deactivate lasers or reduce output below

MPE level e.g. electrical switches, pressure sensitive floor mats

• If no laser radiation hazard at point of entry, defeatable area or entryway

safety controls can be used e.g. safety latches,

• Procedural area or entryway controls when interlocks or safety latches are not

feasible (provided personnel are trained, curtain is used, etc.)

Emergency Conditions

• Need ability to deactivate the laser or reduce the output levels at or

below applicable MPE

• A clearly marked “Emergency Stop” or other device, e.g. switch

suitable for the intended purpose

• This should be clearly described in SOP under “Emergency” section

6/29/2017 24

Administrative Controls

• Procurement Controls & Registration
• Pre approval for 3b & 4 lasers
• Laser Registration
• Standard Operating Procedures (SOP):
• Required for class 3b and 4 lasers.
• Templates available on EHLS website.
• SOP must be read and acknowledged by all users
• Education & Training:
• Provided by EHLS Radiation Safety for intended laser users
• Hands‐on training using the SOP to be provided by PI or designee

Administrative Controls contd.

• Personnel Authorization:
• Class 3b or 4 lasers must be operated/ maintained by authorized personnel

ONLY.

• Alignment:
• Eye injuries very common during alignment procedures.
• Written SOPs and specialized training required.
• Alignment must be performed by designated and trained personnel ONLY.
• Service Personnel:
• State registrations required to perform the service.
• Notify Radiation Safety prior to performing service on class 3b or 4 laser
• Indoor use of lasers require prior

authorization.

• Outdoor operations or lasers‐ e.g.

laser light show require prior authorization.

• Use of lasers in Navigable Airspace

are prohibited.

• Aiming a laser at an aircraft is a

Federal Crime Video https://youtu.be/lVxp‐RKMp88

Controlled Operations

Laser pointer Hazards

• Laser pointers travel far, especially

at night

• Aircrafts pilots are mostly affected
• 260 ft‐ flash blindness hazard
• 1200 ft‐ Glare and disruption of

vision

• 3700 ft‐ Vision is distracted
• Up to 11,700 ft, may cause

distraction to glare, distraction,

• No distraction beyond 11,700 feet.
• May cause accidents during take
• ff, descent and landing

6/29/2017 25

Don’t aim lasers at aircraft

Ways to reduce laser pointer incidents

Personal Protective Equipment

• Personal Protective Equipment (PPE)‐ When protective housing and
• ther controls are not adequate, protective eyewear must be used to

provide protection against laser radiation.

• PPE includes
• Laser eye protection (googles with proper ratings)
• Protective clothing, gloves specifically selected for suitable protection against

laser radiation

• Note: PPE may have serious limitations around high‐powered Class 4

lasers or laser systems.

LASER EYEWEAR

Laser Eyewear

6/29/2017 26

Eye Protection

• Protective eyewear shall be worn by all individuals with access

to Class 3b and/or Class 4 levels of laser radiation. Checkpoints!!!!!!!!!!!!!!!!!! Visible Light Transmission (VLT) Proper comfort and fit Check for defects , i.e. scratches, dents, degraded filter material, etc. Ensure the optical filters are in adequate condition Discard unreliable eyewear, they can’t protect you

Eyewear

• Check for proper Optical Density (OD)
• Check for proper labelling‐ wavelength, OD, VLT,
• When unable to see the beam, don’t be tempted to peek.
• Use appropriate beam card e.g. phosphor card to spot the beam
• Store eyewear in appropriate containers to prevent scratches;
• don’t place it face down on table
• Notify RSO if
• PI does not provide appropriate eyewear, OR
• PI fails to replace existing eyewear when defective

Laser Eyewear‐WARNING!

• Laser eyewear is not for direct viewing of the

beam.

>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.

CO2 laser with regular glasses

6/29/2017 27

WORKING IN LASER LABS LASER LAB SAFETY LASER LAB SAFETY

Laser Lab Worker and PI Training:

• All users and PIs in Laser labs must attend and pass the UH

classroom Laser Safety Training course.

• Online Annual Refresher Training is required for all PIs and

AUs using Lasers. There is a test with each course which requires at least an 80% to pass.

NOTICE: The online UH General Lab Safety course (EH06) is also a requirement for ALL lab workers at UH! http://www.uh.edu/ehls/training/eh06/

PI must provide training on specific laser systems and procedures to users prior to initial use Training record must be on file User must acknowledge SOP

LASER LAB SETUP

*Lasers must be used ONLY in facilities/rooms approved by the Radiation Safety Committee*

6/29/2017 28

LASER LAB SETUP

Postings

Class 4 Laser

Class 3b Laser

LASER LAB SETUP

CONSIDERATIONS FOR A LASER LAB:

• Laser Curtains –flame retardant and /or non‐reflective materials. Rated for laser

power and wavelength

• Terminator – primary and secondary beams must be adequately terminated.

(matte black spray paint, non‐reflective materials)

• Height of Laser – the installation should be designed to minimalize the possibility
• f laser being directed at eyes (i.e. standing, or sitting)
• Log Book – operation log books must be created to track laser usage
• Eye Wear – ensure you have adequate eyewear (quantity and quality)
• Mounting – ensure lasers and equipment are properly secured to the table to

prevent them from being knocked over or misaligned

• SOP – a Standard Operating Procedure must be developed and posted near the

laser setup.

LASER LAB SETUP

Properly secured Appropriate beam termination Laser Safety Goggles Clutter free Minimal reflective surfaces

6/29/2017 29

LASER LAB SAFETY

• When using the laser, ensure that it is annotated in the log

book designated for that laser

• Plan work ahead whenever possible, and perform alignments
• nly when wearing appropriate PPE
• NEVER leave active lasers unsecured or unattended!
• If an issue is discovered, let your P.I. know or contact EHLS

Radiation Safety for assistance (713‐743‐5858).

• Ensure that the “LASER IN USE” light is always on while the

laser is firing.

LASER LAB SAFETY

General lab safety principles apply to laser labs:

• Wear your lab coat and keep it

closed

• Wear gloves and appropriate

laser safety glasses

• Wear closed toe shoes and

long pants

• Leave your PPE in the lab

Do not eat, drink, apply lip balm or cosmetics in the lab

The UH lab dress code policy is described in the UH Chemical Hygiene Plan online on the www.uh.edu/ehls website.

VIDEO

Laser safety video by Coherent

Environmental Health & Safety Concerns

• Workplace conditions or actions that can cause harm to faculty, staff,

students, etc. or to the environment

• Lack of, or poor condition of equipment, tools, personal protective

equipment (PPE) required to perform work safely

• Violations of University policies or governmental regulations

applicable to Environmental & Occupational Health and/or Life Safety

6/29/2017 30

Non‐Emergency Concerns‐What Can I Do?

• Observed concerns can be resolved as follows:
• Self (if you are capable of addressing or resolving the concern)
• Notify the appropriate person or UH department e.g. Work Request to

Facilities Management via FAMIS

• If you are unable to resolve the concern, then:
• Seek departmental help (Notify supervisor, or department administrator)
• Department should initiate the resolution process for safety concerns
• Contact EHLS Department at ehs@uh.edu or 713‐743‐5858
• For assistance with concerns that cannot be resolved by your Department or

Supervisor

Reporting‐Accident & Incident/Near Miss

• For Accidents or Injuries
• Notify Risk Management at 713‐743‐0414
• For Workplace Incidents or Near Misses
• Notify EHLS Department at ehs@uh.edu or 713‐743‐5858

For Emergencies, call the UHPD at 713‐743‐3333

MySafeCampus Reporting Hotline

• 24‐hour, 7‐days/week incident reporting system
• Completely confidential and anonymous
• For Campus Safety Concerns and Compliance/Regulation Violations

www.MySafeCampus.com 1‐800‐716‐9007

EHLS CONTACT NUMBERS

• EHLS Main Line

(713) 743‐5858

• Radiation Safety Officer

(713) 743‐5867 (RSO)

• Assistant RSO

(713) 743‐5870

• Safety Specialist

(713) 743‐5860

6/29/2017 31

RADIATION SAFETY TEST

 Must score ≥ 70% to pass.  You may use your notes as a reference.  Your certificate will be sent via UH e‐mail.  Refresher training online.