Lasers and Laser Safety - University College Cork Sa… · Laser Safety Causes of Laser Accidents...

ROINN NA FISICE Department of

Physics

Lasers andLaser Safety

PY3108

Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland 1

UCCLaser Safety

• Basics of Lasers and Laser Light• Laser Beam Injuries• Laser Hazard Classes• Laser Safety Standards• Laser Control Measures and Procedures• Calculations and Estimates Quantifying Laser Safety

Contents

Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland

ROINN NA FISICE

Department of Physics 2

UCCLaser Safety

L ight

A mplification by

S timulated

E mission of

R adiation

Basics of Lasers and Laser Light


ROINN NA FISICE


UCCLaser Safety

Light is an electromagnetic wave.

Different wavelengths in the visible

spectrum are seen by the eye as

different colors.

λλλλWavelength

Red: λ λ λ λ = 700 nm

Blue: λ λ λ λ = 400 nm

Wave nature of light


ROINN NA FISICE


UCCLaser Safety

Radio

Long WavelengthShort Wavelength

Gamma Ray X-ray Ultraviolet Infrared Microwaves

Visible

Lasers operate in the ultraviolet, visible, and infrared.

Radio

Electromagnetic Spectrum


ROINN NA FISICE


UCCLaser Safety

Incident Photon

Excited Atom

Laser-Professionals.com

Stimulated Photonsame wavelength

same directionin phase

Incident Photon

Stimulated Mission


ROINN NA FISICE


UCCLaser Safety

MONOCHROMATIC

DIRECTIONAL

COHERENT

The combination of these three properties makes laser light focus 100 times better than ordinary light

Laser Light - Characteristics


ROINN NA FISICE


UCCLaser Safety

Monochromatic


ROINN NA FISICE


one colour

UCCLaser Safety

Directional


ROINN NA FISICE


UCCLaser Safety

Coherent


ROINN NA FISICE


UCCLaser Safety

High ReflectanceMirror (HR)

Output CouplerMirror (OC)

ActiveMedium

OutputBeam

Excitation Mechanism

Optical Resonator

Laser Components


ROINN NA FISICE


UCCLaser Safety

Helium-Neon Gas Laser


ROINN NA FISICE


UCCLaser Safety

Rear Mirror

Adjustment Knobs

Safety Shutter Polarizer Assembly (optional)

CoolantBeamTube

AdjustmentKnob

OutputMirror

Beam

Beam Tube

HarmonicGenerator (optional)

Laser Cavity

PumpCavity

Flashlamps

Nd:YAGLaser Rod

Q-switch(optional)

Courtesy of Los Alamos National LaboratoryCourtesy of Los Alamos National Laboratory


Neodymium YAG Laser


ROINN NA FISICE


UCCLaser Safety

Feedback

Physics, Photonics & Ethics November 11, 2009

amplifier

speaker

microphone

UCCLaser Safety

Introduction to Laser Physics

Physics, Photonics & Ethics November 11, 2009

Start with one unit of

optical power

End with r2g2 units of

optical power after one

round trip.

Gain or Amplification

RegionMirror with

Reflectivity = r

Mirror with Reflectivity = r

1g

(1-r)g

rgrg2

r2g2

(1-r)rg2

3 possibilities : r2g2 < 1 optical field decays

r2g2 = 1 stable optical field(so called lasing condition)

r2g2 > 1 optical field increases

UCCLaser Safety

10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 1 10 102

LASERS

200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 10600

Ultraviolet Visible Near Infrared Far Infrared

Gamma Rays X-Rays Ultra- Visible Infrared Micro- Radar TV Radioviolet waves waves waves waves

Wavelength (m)

Wavelength (nm)

Nd:YAG1064

GaAs905

HeNe633

Ar488/515

CO2

10600XeCl308

KrF248

2ωωωω

Nd:YAG532

Retinal Hazard Region

ArF193

CommunicationDiode1550

Ruby694


Alexandrite755

Laser Spectrum


ROINN NA FISICE


UCCLaser Safety

Laser Beam Injuries

High power lasers can cause skin burns.

Lasers can cause severe eye injuries resulting in permanent vision loss.


ROINN NA FISICE


UCCLaser Safety

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

Skin Burn from CO2 Laser


ROINN NA FISICE


UCCLaser Safety

EYE

INTRABEAM VIEWING

LASER

MIRROR

SPECULAR REFLECTION

LASER

REFLECTED BEAM

DIFFUSE REFLECTION

LASER

SCATTERED LIGHT

ROUGHSURFACE

Types of Laser Eye Exposure


ROINN NA FISICE


UCCLaser Safety

Choroid

Aqueous

Cornea

Macula

Optic Nerve

Sclera

Vitreous

RetinaLens

Human Eye


ROINN NA FISICE


UCCLaser Safety

The Retinal Hazard Region


ROINN NA FISICE


400-1400 nmAffects the retina

UCCLaser Safety

UV-C (100-280nm)Cornea surface

UV-A (315-400nm)Affects the lens

UV-B (280-315nm)Absorbed by the cornea

Ultraviolet Light


ROINN NA FISICE


UCCLaser Safety

Far IRAffects cornea and aqueous humor

Near IR (< 1400nm)Affects the retina

Infra-red Region


ROINN NA FISICE


UCCLaser Safety

25 µ

Photo courtesy of U S Air Force

THERMAL BURNSON

PRIMATE RETINA


ROINN NA FISICE

Department of Physics


UCCLaser Safety

Multiple Pulse Retinal Injury


ROINN NA FISICE


UCCLaser Safety

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

Q-Switched Laser Injury


ROINN NA FISICE


UCCLaser Safety

Causes of Laser Accidents

Studies of laser accidents have shown that there are usually

several contributing factors. The following are common

causes of laser injuries:

Inadequate training of laser personnel

Alignment performed without adequate procedures

Failure to block beams or stray reflections

Failure to wear eye protection in hazardous situations

Failure to follow approved standard operating procedures

or safe work practices


ROINN NA FISICE


UCCLaser Safety

Lasers are classified according to the

level of laser radiation that is

accessible during normal operation.

Laser Hazard Classes


ROINN NA FISICE


UCCLaser Safety

Important terminology

Maximum Permissible Exposure (MPE)

Accessible Emission Limits (AEL)

Nominal Ocular Hazard Distance (NOHD)


ROINN NA FISICE


UCCLaser Safety

Class 1 MPE less than 7 microwatts of visible radiation.

A Class 1 laser is considered “safe” under reasonably

foreseeable conditions of operation and they present no

hazard to the eye or skin.

This Class also includes laser systems which cannot emit

hazardous levels of laser radiation because of the

inherent design of the product.

Note that there may be a more hazardous laser system

embedded in the product and additional precautions

would be necessary if the system is opened up.


ROINN NA FISICE


UCCLaser Safety

Class 1M

Exceed accessible emission limits for Class 1 but,

because of the geometrical spread of the emitted

radiation, the laser does not cause harmful levels

of exposure to the unaided eye.

Safe limit can be exceeded, and injury can occur, if

magnifying viewing instruments are used, eg

binoculars, telescopes, magnifying glasses,

microscopes.


ROINN NA FISICE


UCCLaser Safety

Class 2 MPE less than 1 mW of visible radiation.

A Class 2 laser or laser system must only emit a visible

laser beam.

Momentary viewing of a Class 2 laser beam is not

considered hazardous since the upper limit for this type

of device is less than the maximum permissible exposure

(MPE) for momentary exposures of 0.25 second or less -

the so-called “blink reflex”.

Intentional extended viewing is considered hazardous.


ROINN NA FISICE


UCCLaser Safety

Class 2M Laser products which exceed the permitted accessible

limits for Class 2 but, because of the geometric spread of

the emitted radiation, protection of the unaided eye is

normally afforded by natural aversion responses to bright

light.

The use of magnifying viewing instruments can give rise

to higher levels of exposure and injury can occur. These

instruments include: binoculars; telescopes; magnifying

lenses; and microscopes.


ROINN NA FISICE


UCCLaser Safety

Class 3R

Laser products having a level of accessible

emission up to five times the limits for Class 1 (if

invisible) or Class 2 (if visible).

The maximum permissible exposure may be

exceeded but the risk of injury is low.


ROINN NA FISICE


UCCLaser Safety

Class 3B

Less than 500 mW of visible radiation

note that Class 3B also covers pulsed lasers and invisible

radiation. Reference should be made to the MPE limits

contained in the British Standard in order to verify

classification.

Direct intra-beam viewing is always hazardous.

Viewing diffuse reflections from a distance is

normally safe provided the exposure duration is

less than 10 seconds.


ROINN NA FISICE


UCCLaser Safety

Class 4 Over 500 mW visible radiation

note that Class 4 also covers pulsed lasers and invisible radiation.

Reference should be made to the MPE limits contained in the

British Standard in order to verify classification.

These lasers are very powerful and may also be a fire

hazard.

Exposure of the skin to the beam may cause injury.

Even diffuse reflections are hazardous.

Very stringent control measures are required.

UCCLaser Safety

Some Examples & Numbers


ROINN NA FISICE


UCCLaser Safety

Engineering controls Engineering controls remove the dependence to follow

rigorous procedures and the possibility of failure of

personal protective equipment.

Engineering controls all the safety features built into the

design of the laser and its associated equipment.

Examples of Engineering Controls include:

key control;

remote interlock;

beam enclosures;

protective filter installations.


ROINN NA FISICE


UCCLaser Safety

Administrative controls Administrative and Procedural Controls are intended to

supplement Engineering Controls to ensure that laser

personnel are fully protected from laser hazards.

Administrative/Procedural Controls include:

information, instruction and training;

signage;

protocols

arrangements for maintenance;

arrangements for servicing.


ROINN NA FISICE


UCCLaser Safety

Signage


ROINN NA FISICE


Class 1

CLASS 1 LASER PRODUCT

Class 2 LASER RADIATION

DO NOT STARE INTO BEAM


Class 2M LASER RADIATION

DO NOT STARE INTO BEAM OR VIEW

DIRECTLY WITH OPTICAL INSTRUMENTS

CLASS 2M LASER PRODUCT

Class 3B LASER RADIATION

AVOID EXPOSURE TO BEAM

CLASS 3B LASER PRODUCT

Class 4 LASER RADIATION

AVOID EYE OR SKIN EXPOSURE TO

DIRECT OR SCATTERED RADIATION


UCCLaser Safety

Symbol and Border: BlackBackground: Yellow

Legend and Border: BlackBackground: Yellow

INVISIBLE LASER RADIATIONAVOID EYE OR SKIN EXPOSURE

TO DIRECT OR SCATTERED RADIATIONCLASS 4 LASER PRODUCT

WAVELENGTH 10,600 nmMAX LASER POWER 200 W

EN60825-1 1998

International LaserWarning Labels


ROINN NA FISICE


UCCLaser Safety

Personal Protective Equipment

Personal protective equipment should only be

used when the above measures do not provide

sufficient control.

Personal protective equipment includes:

protective eyewear; and

protective clothing.


ROINN NA FISICE


UCCLaser Safety

Laser eye protection


ROINN NA FISICE


Selection of eyewear should be based

on:

wavelength(s) being used;

radiant exposure;

maximum permissible exposure (MPE);

optical density of eyewear;

visible light transmission requirements;

adequate peripheral vision; prescription

lenses; and,

comfort.

UCCLaser Safety

Optical Density


ROINN NA FISICE


−=

in

out

I

IA 10logλ

λA

inoutII

−×=→ 10

Example 1:000,000,1

1=

in

out

I

I

Example 1: 3=λA1000

10 3 in

inout

III =×=→ −

6000,000,1

1log 10 =

−=λA

UCCLaser Safety

Eyewear Labels

All eyewear must be labeled with wavelength and optical

density.Guidelines in EN208

(Handout)


ROINN NA FISICE


UCCLaser Safety

Example: Plastic Eyewear Characteristics

10

9

8

7

6

5

4

3

2

1

0

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

Wavelength (µµµµm)

Op

tical

Den

sit

y

GreenNd:YAG filter

Orange2ωωωω Nd:YAG

filter


ROINN NA FISICE


UCCLaser Safety

The person operating the laseralways has the primary

responsibility for all hazards associated with laser use.

Who has the primary responsibility for laser safety any time a CLASS 3 or

CLASS 4 laser is operated?


ROINN NA FISICE


UCCLaser Safety

Suggested Format forStandard Operating Procedures (SOP)

1. Introduction – Description of laserType and wavelength; Intended application & LocationAverage power or energy per pulsePulse duration and repetition rate for pulsed lasers

2. Hazards – List all hazards associated with laserEye and skin hazards from direct and diffuse exposuresElectrical hazardsLaser generated air contaminantsOther recognized hazards

3. Control Measures – List control measures for each hazardInclude the following:

Eyewear requirement, include wavelength and ODDescription of controlled area and entry controlsReference to equipment manualAlignment procedures (or guidelines)

4. Authorized Personnel

5. Emergency Procedures


ROINN NA FISICE


UCCLaser Safety

• Most beam injuries occur during alignment.

• Only trained personnel may align class 3 or class 4

lasers (NO EXCEPTIONS!)

• Laser safety eyewear is required for class 3 and

class 4 beam alignment.

• ANSI REQUIRES approved, written alignment

procedures for ALL class 4 laser alignment activities

and recommends them for class 3.

Safe Beam Alignment


ROINN NA FISICE


UCCLaser Safety

1. Exclude unnecessary personnel from the laser area during alignment.

2. Where possible, use low-power visible lasers for path simulation of high power visible or invisible lasers.

3. Wear protective eyewear during alignment. Use special alignment eyewear when circumstances permit

their use.

4. When aligning invisible beams, use beam display devices such as image converter viewers or phosphor

cards to locate beams.

5. Perform alignment tasks using high-power lasers at the lowest possible power level.

6. Use a shutter or beam block to block high-power beams at their source except when actually needed

during the alignment process.

7. Use a laser rated beam block to terminate high-power beams downstream of the optics being aligned.

8. Use beam blocks and/or laser protective barriers in conditions where alignment beams could stray into

areas with uninvolved personnel.

9. Place beam blocks behind optics to terminate beams that might miss mirrors during alignment.

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

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

12. Alignments should be done only by those who have received laser safety training.

Alignment Guidelines forClass 3 and 4 lasers


ROINN NA FISICE


UCCLaser Safety

• 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 view a Class 3 (or any higher power) laser with optical instruments.

• Never direct the beam toward people.

• Operate lasers only in the area designed 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.

• Position the laser so that it is well above or below eye level.

• Only block the beam with appropriate (enclosing or diffuse reflecting) beam blocks/shutters.

• Always enclose laser beams as much as possible with appropriate materials.

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

include items of jewelry and tools.

• Do not enter a designated Class 3b or Class 4 laser area (posted with a DANGER sign)

without approval from a qualified laser operator. Eye protection is required in these areas.

• Always wear laser safety eyewear in designated areas.

Safe Work Practices


ROINN NA FISICE


UCCLaser Safety

Keys to a successful laser safety program

Active involvement and support of laser users

Effective oversight by local (Departmental ) Laser Safety Officers

Support from management at all levels


ROINN NA FISICE


UCCLaser Safety

Safety Calculations

Maximum Permissible Exposure (MPE)

Wavelength

Exposure

CW or Pulsed

And ANSI Standards


Area of limiting aperture

MPE

Nominal Ocular Hazard Distance (NOHD)


ROINN NA FISICE


UCCLaser Safety

What is the duration time - t?

What is the duration time?

a. Is it intentional viewing? Duration time = exposure time.

b. Is it accidental exposure? i. Visible (400-700 nm), ocular

Duration time = 0.25 s

ii. <400 nm, ocular Duration time = 30000 s

iii. >700 nm, ocular Duration time = 100 s

iv. Visible or invisible, skin Duration time = 10 to 100 s


ROINN NA FISICE


MPE: λ=10.6µm?

UCCLaser Safety

MPE: λ=10.6µm

55

21000600,106.10 −⇒= Wmnmmµ

100 sec

λ=10.6µm?

UCCLaser Safety










ROINN NA FISICE


MPE: λ=980nm?

UCCLaser Safety

MPE: λ=980nm CW


ROINN NA FISICE


What is C4?

100 sec

λ=980nm

UCCLaser Safety

MPE: λ=980nm – page 36


ROINN NA FISICE


2275.0

4 21206618 −− === WmJmtCMPE

( ) ( )

63.310

1010

56.0

500/280500/700980

4

==

== −C st 100=

UCCLaser Safety

How about laser pointers?What is the duration time?

a. Is it intentional viewing? NO Duration time = exposure time.

b. Is it accidental exposure? YES i. Visible (400-700 nm), ocular YES

Duration time = 0.25 s t=0.25s





ROINN NA FISICE


UCCLaser Safety

How about laser pointers?


ROINN NA FISICE


22 5.2536.6 −− == WmJmMPE

UCCLaser Safety

Angle of Apparent Source


ROINN NA FISICE


UCCLaser Safety

Angle of Apparent Source


ROINN NA FISICE


UCCLaser Safety


Area of limiting aperture MPE


ROINN NA FISICE


LAAMPEAEL ×=

UCCLaser Safety

10.6µm Laser


ROINN NA FISICE


21000 −= WmMPE

221000 rWmAEL π×= −

mWm

1002

01101000

2

≈

=

.π

UCCLaser Safety

980nm Laser


ROINN NA FISICE


221 −= WmMPE

2221 rWmAEL π×= −

mWm

802

007021

2

..

≈

= π

UCCLaser Safety

Laser Pointers


ROINN NA FISICE


25.25 −= WmMPE

22525 rWmAEL π×= −.

mWm

12

0070525

2

≈

=

.. π

UCCLaser Safety

Beam Type


ROINN NA FISICE


UCCLaser Safety

Beam Type


ROINN NA FISICE


UCCLaser Safety

Beam Type


ROINN NA FISICE


UCCLaser Safety

Angular Measures


ROINN NA FISICE


Hint: look up steradian

UCCLaser Safety

The Steradian


ROINN NA FISICE


A graphical representation of 1

steradian. The sphere has

radius r, and in this case the area

of the patch on the surface

is A = r2. The solid angle

is Ω = A/r2 so in this case Ω = 1.

The entire sphere has a solid

angle of 4π sr ≈ 12.56637 sr.

http://en.wikipedia.org/wiki/Steradian

UCCLaser Safety

Analog to Radians


ROINN NA FISICE


http://en.wikipedia.org/wiki/Steradian

θrL =

rL

Ω= 2rA

steradians−Ω

r

A

UCCLaser Safety

Steradian


ROINN NA FISICE


r

A

What is the area?

=

44 22 θπ sinr

∫ ∫=π

θ

φθθ2

0

2

0

2ddrA sin

[ ] 20

22θ

θπ cos−= r

−=

212 2 θ

π cosr

2

2

44

≈

θπr

2

2

2

≈

θπrFor small angles:

θLarge

angles

UCCLaser Safety

Surface Irradiance


ROINN NA FISICE


Emits into all angles:

40W light bulb: 5W light

1 metre away:

22

25.0

4

5

4

5 −− ≈=== WmWmr

W

A

PI

ππ

[ ]ππ cos12 2 −= rA

24 rπ=

UCCLaser Safety

Surface Irradiance


ROINN NA FISICE


1 mW, Collimated

1 metre away:

22

22300

)001.0(

001.01 −− ≈=== WmWmr

mW

A

PI

ππ

2mm diameter beam2

rA π=→

UCCLaser Safety

Surface Irradiance


ROINN NA FISICE


UCCLaser Safety

Spatial Coherence


ROINN NA FISICE


UCCLaser Safety

Retinal Irradiance


ROINN NA FISICE


UCCLaser Safety

Power Through Apertures


ROINN NA FISICE


UCCLaser Safety

Gaussian


ROINN NA FISICE


UCCLaser Safety

Gaussian Cross-section


ROINN NA FISICE


UCCLaser Safety

Large Beam


ROINN NA FISICE


UCCLaser Safety

Small Beam


ROINN NA FISICE


UCCLaser Safety

Intermediate Beam


ROINN NA FISICE


UCCLaser Safety

Optical Fibre


ROINN NA FISICE


0

63

22

πω

λθ

zzd ==

71

263

.

zNAzd == θ

UCCLaser Safety

Power through Aperture


ROINN NA FISICE


UCCLaser Safety

Bare Diode Laser


ROINN NA FISICE


UCCLaser Safety

Nominal Ocular HazardDistance (NOHD)


ROINN NA FISICE


UCCLaser Safety

NOHD


ROINN NA FISICE


UCCLaser Safety

Collimated


ROINN NA FISICE


UCCLaser Safety

Focussed


ROINN NA FISICE


UCCLaser Safety

Calculating NOHD


ROINN NA FISICE


21 θθ ,

Emitted Power = P Beam Divergence = θ

Divergence Angles =

Beam Area:

2

2

2

=

θπrA

Irradiance:

21

2

4

θθπz

P

A

PI ==

⇒

22

212 θθπz

For small angles!

UCCLaser Safety

Calculating NOHD


ROINN NA FISICE


Insert: MPE for I Insert NOHD for z

( ) 21

2

4

θθπ NOHD

PMPE =→

21

2θπθMPE

PNOHD =

21

2

4

θθπz

PI =

UCCLaser Safety

12mW at 980nm


ROINN NA FISICE


221 −= WmMPE

100 mm

300 mm

UCCLaser Safety

12mW at 980nm


ROINN NA FISICE


Therefore:0

63

22

πω

λθ

zzd ==

( )( )

radm

m0880

10

9802222

0

..

===µπ

µ

πω

λθ

2

2

2

=

θπrA

UCCLaser Safety

Calculating NOHD


ROINN NA FISICE


m30.=

( )22088021

012022

.

.

ππθ==

MPE

PNOHD

UCCLaser Safety

12mW at 980nm


ROINN NA FISICE


100 mm

300 mm

mWAEL 80.=

UCCLaser Safety

12mW at 980nm


ROINN NA FISICE


Therefore:

526

828

63

63

.

.

=→

=→

d

d

0

63

22

πω

λθ

zzd ==

300

100

=

=

z

z

UCCLaser Safety

12mW at 980nm


ROINN NA FISICE


Therefore:

( )2631

dde

−−=η

0680

4670

.

.

=→

=→

η

η

( )mmd 7=

526

828

63

63

.

.

=→

=→

d

d

300

100

=

=

z

z

UCCLaser Safety

12mW at 980nm


ROINN NA FISICE


0680

4670

.

.

=→

=→

η

η

526

828

63

63

.

.

=→

=→

d

d

300

100

=

=

z

z

mWP

mWP

80

65

.

.

=→

=→

mWAEL 80.=

100 mm

300 mm

UCCLaser Safety

12mW at 980nm


ROINN NA FISICE


300 mm

What about safety to Class 1M?

UCCLaser Safety










ROINN NA FISICE


MPE: λ=980nm?

UCCLaser Safety


ROINN NA FISICE


WCAEL 4

41021 −×= .

UCCLaser Safety

Class 1 @ λ=980nm


ROINN NA FISICE


( ) ( ) 633101010 560500280500700980

4 ..// ==== −

C

mWAEL 4360.=

WCAEL 4

41021 −×= .

mWP 4360.= 0363012

4360.

.==→

mW

mWη

UCCLaser Safety

Class 1 @ λ=980nm


ROINN NA FISICE


( )2631

dde

−−=η

( ) ( )η−=−→ 12

63 lndd

( ) η−=→ −1

263dd

e

( )η−−=→

163

ln

dd

( )mm

mm436

036301

7.

.ln=

−−=

UCCLaser Safety

Class 1 @ λ=980nm


ROINN NA FISICE


mm412=

0

63

22

πω

λzd =

λ

πω

22

063dz =→

( ) ( )( )m

mmmz

µ

µπ

98022

10436

.

.=

UCCLaser Safety

12mW at 980nm


ROINN NA FISICE


mmz 412=

mWAEL 4360.=

?? mm

Class 1 @ λ=980nm

UCCLaser Safety

An Easier Way!!


ROINN NA FISICE


Calculate using MPE!

LAAMPEAEL ×=

LAA

AELMPE =→

2

2

3

2211

2

0070

104360 −−

=

×= Wm

WMPE .

.

.

π

UCCLaser Safety

An Easier Way


ROINN NA FISICE


λ=980nm

Or, use the MPE table with the long viewing time

UCCLaser Safety

Class 1 @ λ=980nm


ROINN NA FISICE


( ) ( ) 633101010 560500280500700980

4 ..// ==== −

C

26.11 −= WmMPE

2

42.3 −= WmCMPE

Previously calculated 11.22

UCCLaser Safety

An Easier Way!!


ROINN NA FISICE


mmm 420420 == .

( )208802211

01202

..

.

π=

22

πθMPE

PNOHD = Already know: θ

UCCLaser Safety

How about laser pointers?What is the duration time?

a. Is it intentional viewing? NO Duration time = exposure time.

b. Is it accidental exposure? YES i. Visible (400-700 nm), ocular YES






ROINN NA FISICE


UCCLaser Safety


ROINN NA FISICE


WCAEL 3

71093 −×= .

UCCLaser Safety

Class 1 Laser


ROINN NA FISICE


WAEL µ866.=

( )

nm

C

6335817

10 5500150

3

==

= −

λ

λ

@.

.

WAEL µ390.=nm532=λ@

UCCLaser Safety


ROINN NA FISICE

Department of Physics

Class 1

And, this is consistent with the numbers provided

in the laser safety manual

Date post:	14-Jun-2020
Category:	Documents
Upload:	others
View:	8 times
Download:	1 times

Lasers and Laser Safety - University College Cork Sa… · Laser Safety Causes of Laser Accidents...

Documents