Laser Safety, Standards & Regulations

R. Timothy Hitchcock, CIH, CLSOLightRay Consulting, Inc.

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Ted Maiman Born 1927

Detail of first laser

1960: First working laserT. Maiman, Hughes Research Labs

Historical Events...

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Electromagnetic Wave

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The Electromagnetic Spectrum

X-RaysRadio Waves

Gamma Rays

Ultr

a V

iole

t

Infr

a R

ed

Mic

row

aves

NonNon--Ionizing RadiationIonizing RadiationIonizing RadiationIonizing Radiation

Vis

ible

Lig

ht

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Nonionizing Radiation: Wavelength (λ)

1 λ

λ = distance between two points in the same phase of consecutive wave cycles; otherwise, 1 complete cycle of a wave

units of length: nanometer (nm, 10-9

meter) or micrometer (μm, 10-6 m)

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Laser Scanner Radiation: Described by Wavelength (nm)

532 nm - frequency-doubled Nd:YAGGreen beam

690 nm – red diode laser785 nm - invisible IR1500 nm – invisible IR1550 nm – invisible IR

Photo courtesy ofFARO Technologies, Inc.

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Characteristics of Laser Beams

DirectionalMonochromaticCoherentBright

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Laser Beams Are Directional

a

φbeam

φ - beam divergence (milliradians, mrad)

a – emergent beam diameter (mm)

Laser

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Practical Application of Divergence

Astronauts from Apollo 11, 14 and 15 left retroreflectors on the moon. Laser ranging using beams from ruby or Nd:YAG lasers has been used to study Moon-Earth separation distance and effects of tides on Moon’s orbit.

Photos: Univ. of Texas

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Monochromatic

Means one color or wavelength.

Non-laser sources of light are polychromatic.

Comparison of output of HeNe laser and quartz-halogen lamp

Pow

er400 600 800 1000 1200 1400 1600 1800

Wavelength [nm]

Comparison of Spectraof QTH Lamp and HeNe Laser

HeNe Laser

QTH Lamp

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CoherenceLaser radiation is spatially and temporally coherent. Simply, spatial coherence means that the waves are in phase (in step), and temporal coherence means that the waves are the same wavelength.

Other sources of radiation are incoherent in that the waves are not necessarily in phase or of the same wavelength.

λ

In phase

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Temporal Operation

Time (sec)

Continuous wave (CW) - output for time ≥ 0.25 secΦ

(wat

ts)

0.25 0.50 0.75

1

10

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Temporal OperationPulsed emissions - output for time < 0.25 sec

Time (sec)

Φav

g(w

atts

)

0.25 0.50 0.75

1

10

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Quantities Used to Describe Laser Output

Radiant energy (Q) – the ability to do work with units of joules (J); by convention used for pulsed lasers.

Radiant power (Φ) – the rate at which energy is utilized with units of watts (W); by convention use for CW lasers.

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Quantities Used to Describe Exposure

Radiant exposure (H) – radiant energy in a cross sectional area with units of joules per square centimeter (J/cm2).

Irradiance (E) – radiant power in a cross sectional area with units of watts per square centimeter (W/cm2).

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Illustration of Irradiance1-W laser

1 ft 10 ft 100 ft

Distance Irradiance

(cm) (ft)

30.48 1 127

304.8 10 12

3048 100 0.14

(W/cm2)

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Target Organs

Eye: cornea, lens, retinaSkin: epidermis & dermisEye is more vulnerable due to potential for debilitating effects.

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UV-C – Cornea

UV-B – Cornea, lens

UV-A – Cornea, lens, retina

Visible – Retina

IR-A - Retina

IR-B – Cornea, lens

IR-C - Cornea

Ocular Anatomy & Wavelength Dependence

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Retinal Hazard Region

400 nm to 1400 nm

Visible radiation: 400 nm to ~ 770 nm

IR-A: 770 nm to 1400 nm

400 Wavelength (nm) 1400

0

Tran

smitt

ance

1.0

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Retinal Lesion

Threshold lesion

Thermal effect – increase in total energy of system resulting in increase in heat which coagulates and denatures protein and inactivates enzymes.

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Relative Sensitivity of the Eye

• Photopic vision: daylight vision controlled by cones.

• Scotopic vision: dim light vision controlled by rods.

*

*

* = green scanner (532 nm); * = red scanner (690 nm)

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Visual Interference

Transient, non-debilitating effects

Includes:StartleVeiling glareAfterimageFlash blindness

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Visual Interference

ANSI Z136.6-2005:

“Visual interference with critical tasks by low-power visible lasers (Class 3R or less) is possible, if they are intentionally used at dusk or at night, near roads or airports.”

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Laser Accidents: Classes 2 & 3a

3 documented overexposures in U.S.

Handheld laser pointers with CW output2 with Class 3a pointers (1-5 mW)1 with Class 2 pointer (< 1 mW)

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Laser Incidents: Eye Injury

Purposeful self-exposure

Overcame aversion response & stared into beam for 10-30 seconds

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Classification of Lasers

Numerical scheme used to group lasers on basis of optical power & potential hazard

Common to “embed” a higher class laser in a lower class (e.g., Class I) laser product

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FDA Classification SchemeClass Relative Beam Power Relative Hazard

I Extremely low None known

IIa Very, very low Very, very low

II Very low Very low

IIIa Low Low

IIIb Moderate Moderate

IV High High

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Other Classification Schemes

American National Standard for Safe Use of Lasers (ANSI Z136.1-2000)

International Electrotechnical Commission – IEC 60825-1 Edition 1.2, 2001-08

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Classification of Lasers

IEC adopted a new classification scheme

Differences exist among these standards

Global trade is driving harmonization

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Classification: Comparison of Schemes

US FDA ANSI Z136.1 IEC 60825-1I 1 1--- --- 1MIIa --- ---II 2 2--- --- 2MIIIa 3a 3RIIIb 3b 3BIV 4 4

M = magnification; R = reduced requirements

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Classes: 3D Laser Scanners

Classes 1, 1M, 2, 2M, 3R

For same wavelength, higher class number = higher output power

Higher output power usually means greater range

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Laser Regulations and Standards

RegulationsOccupational Safety and Health Administration (OSHA)Food and Drug Administration (FDA)State regulations & municipal ordinances

StandardsAmerican National Standards Institute (ANSI)

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Laser Regulations and Standards

International StandardsInternational Electrotechnical Commission (IEC)International Commission on Non-Ionizing Radiation Protection (ICNIRP)

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Laser Regulations: US Food and Drug Administration (FDA)

21 CFR Subchapter J – Federal Laser Product Performance Standard (FLPPS)

Applies to laser product manufacturers and those modifying laser products

Promulgated by FDA agency: Center for Devices and Radiological Health (CDRH)

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FDA: Performance Standard

States how product must perform

3 major parts: performance; labeling; information

Requires certification of laser products, and 1st step is classification

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FDA-IEC Harmonization:Laser Notice 50

Allows manufacturers to introduce laser products into US commerce that comply with certain provisions of IEC 60825-1 (laser products) & IEC 60601-2-22 (medical electrical equipment).

Takes the “least-burdensome approach.”

Photo courtesy of HICAD America

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Certification of Laser Products

Manufacturer self-certification of laser products1st step is classification, as certification requirements are class-dependentManufacturer submits “product report” to FDA Certification label is

legal requirement

Class designation and warning label

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Laser Regulations (OSHA)29 CFR 1910: Standards for General Industry

Main body of regulationsDoes not use the word laser

29 CFR 1926: Standards for Construction Industry

Mentions laser in sections on PPE and nonionizing radiation

CFR = Code of Federal Regulations

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Laser Regulations (OSHA)

Limited regulations specific to lasers

Inspectors may cite Z136.1 under General Duty Clause (Section 5(a) of the OSH Act of 1970)

May utilize other standards applicable to laser safety

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OSHA Eye and Face Protection eTool

On-line assistance to comply with PPE requirements at …http://www.osha.gov/SLTC/etools/eyeandface/ppe/light_radiation.html

Or www.osha.gov/ then select eye and face eTools and work through to optical radiation section

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Laser Regulations: Various States & MunicipalitiesComprehensive regulations: Alaska, Arizona, Arkansas, Florida, Illinois, Georgia, Massachusetts, New York, Texas, WashingtonLaser pointer regulations: Arkansas, California, Hawaii, Kansas, Illinois, Maine, Maryland, Massachusetts, Michigan, New Jersey, New York, North Carolina, Rhode Island, Tennessee, Texas, Virginia, and WashingtonLocal ordinances restrict purchase by minors and/or restrict use

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ANSI Z136 Family of Standards

5 published standards1 draft standard1 published recommended practiceApplies to lasers operating between 180 nm and 1 mmApplies to the laser use environment vs. manufacturer’s requirements with 1 exception

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Two ANSI Standards Apply …

ANS for Safe Use of Lasers ANSI Z136.1-2000

ANS for Safe Use of Lasers OutdoorsANSI Z136.6-2005

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ANSI Z136.1-2000

Main (horizontal) standard

Applies to the use of 3D scanners indoors

Requires LSO and laser safety program for Class 3b and 4 lasers & laser systems

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ANSI Z136.6-2005

RequiresLSO for Class 3B & 4Hazard evaluation for > Class 3R

Control measures not required for construction lasers:

Class 3R-visible beams Class 1-invisible beams

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IEC 60825-1 – User’s guide

Class 1M, 2M collimated beams and 3R invisible beams: terminate beam at end of useful pathLSO, eye protection for Class 3R invisible beamsTraining, posting: operation of Class 1M, 2M collimated beams and Class 3R

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EYE PROTECTION:Factors to Consider

Wavelength compatibilityAttenuation at that wavelengthVisual light transmittanceComfort and fitTrainingInspectionStorage

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Wavelength Compatibility

Visible beam was transmitted through lens and damaged carbon paper.

IR-C beam was absorbed by and damaged plastic lens, while carbon paper is intact.

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Optical Density (OD)

Eyewear must be marked with OD as a function of wavelength.Laser eyewear is not for direct viewing of the beam.Some manufacturers mark eyewear “DVO”for “diffuse viewing only.”

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Optical DensityOD Attenuation Transmission

1 10 0.1

2 100 0.01

3 1000 0.001

4 10,000 0.0001

5 100,000 0.00001

6 1,000,000 0.000001

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Rules to (safely) lase by:Control Axioms

Eye safe = Class 1 regardless of wavelengthPurchase and use certified Class 1 laser products when possible.Enclose as much of the beam as possible.Don’t direct beam toward doors/windows.

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Rules to (safely) lase by:Control Axioms (cont'd)

Don’t locate beam at eye level.Utilize surfaces that scatter radiation and minimize specular reflection.Make sure warning/indicator lights can be seen through protective filters.