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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
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Department of Physics 2
UCCLaser Safety
L ight
A mplification by
S timulated
E mission of
R adiation
Basics of Lasers and Laser Light
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
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Department of Physics 3
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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
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Department of Physics 4
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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
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Department of Physics 5
UCCLaser Safety
Incident Photon
Excited Atom
Laser-Professionals.com
Stimulated Photonsame wavelength
same directionin phase
Incident Photon
Stimulated Mission
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Department of Physics 6
UCCLaser Safety
MONOCHROMATIC
DIRECTIONAL
COHERENT
The combination of these three properties makes laser light focus 100 times better than ordinary light
Laser Light - Characteristics
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
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Department of Physics 7
UCCLaser Safety
Monochromatic
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Department of Physics 8
one colour
UCCLaser Safety
Directional
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Department of Physics 9
UCCLaser Safety
Coherent
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Department of Physics 10
UCCLaser Safety
High ReflectanceMirror (HR)
Output CouplerMirror (OC)
ActiveMedium
OutputBeam
Excitation Mechanism
Optical Resonator
Laser Components
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Department of Physics 11
UCCLaser Safety
Helium-Neon Gas Laser
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Department of Physics 12
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
Laser-Professionals.com
Neodymium YAG Laser
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
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Department of Physics 13
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
Laser-Professionals.com
Alexandrite755
Laser Spectrum
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UCCLaser Safety
Laser Beam Injuries
High power lasers can cause skin burns.
Lasers can cause severe eye injuries resulting in permanent vision loss.
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Department of Physics 17
UCCLaser Safety
Accidental exposure to partial reflection of 2000 W CO2 laser beamfrom metal surface during cutting
Skin Burn from CO2 Laser
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
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Department of Physics 18
UCCLaser Safety
EYE
INTRABEAM VIEWING
LASER
MIRROR
SPECULAR REFLECTION
LASER
REFLECTED BEAM
DIFFUSE REFLECTION
LASER
SCATTERED LIGHT
ROUGHSURFACE
Types of Laser Eye Exposure
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Department of Physics 19
UCCLaser Safety
Choroid
Aqueous
Cornea
Macula
Optic Nerve
Sclera
Vitreous
RetinaLens
Human Eye
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UCCLaser Safety
The Retinal Hazard Region
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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
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UCCLaser Safety
Far IRAffects cornea and aqueous humor
Near IR (< 1400nm)Affects the retina
Infra-red Region
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Department of Physics 23
UCCLaser Safety
25 µ
Photo courtesy of U S Air Force
THERMAL BURNSON
PRIMATE RETINA
Laser-Professionals.com
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Department of Physics
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland 24
UCCLaser Safety
Multiple Pulse Retinal Injury
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Department of Physics 25
UCCLaser Safety
Retinal Injury produced by four pulses from a Nd:YAG laser range finder.
Q-Switched Laser Injury
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Department of Physics 26
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
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Department of Physics 27
UCCLaser Safety
Lasers are classified according to the
level of laser radiation that is
accessible during normal operation.
Laser Hazard Classes
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UCCLaser Safety
Important terminology
Maximum Permissible Exposure (MPE)
Accessible Emission Limits (AEL)
Nominal Ocular Hazard Distance (NOHD)
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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.
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Department of Physics 30
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.
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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.
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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.
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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.
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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.
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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
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Department of Physics 37
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.
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Department of Physics 38
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.
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Department of Physics 39
UCCLaser Safety
Signage
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Department of Physics 40
Class 1
CLASS 1 LASER PRODUCT
Class 2 LASER RADIATION
DO NOT STARE INTO BEAM
CLASS 2 LASER PRODUCT
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
CLASS 4 LASER PRODUCT
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
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Department of Physics 41
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.
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
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Department of Physics 42
UCCLaser Safety
Laser eye protection
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
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Department of Physics 43
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
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Department of Physics 44
−=
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)
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Department of Physics 45
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
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Department of Physics 46
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?
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Department of Physics 47
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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
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Department of Physics 48
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
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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
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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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
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Department of Physics 51
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
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Department of Physics 52
UCCLaser Safety
Safety Calculations
Maximum Permissible Exposure (MPE)
Wavelength
Exposure
CW or Pulsed
And ANSI Standards
Accessible Emission Limits (AEL)
Area of limiting aperture
MPE
Nominal Ocular Hazard Distance (NOHD)
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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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
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Department of Physics 54
MPE: λ=10.6µm?
UCCLaser Safety
MPE: λ=10.6µm
55
21000600,106.10 −⇒= Wmnmmµ
100 sec
λ=10.6µm?
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
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MPE: λ=980nm?
UCCLaser Safety
MPE: λ=980nm CW
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What is C4?
100 sec
λ=980nm
UCCLaser Safety
MPE: λ=980nm – page 36
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Department of Physics 58
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
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
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Department of Physics 59
UCCLaser Safety
How about laser pointers?
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22 5.2536.6 −− == WmJmMPE
UCCLaser Safety
Angle of Apparent Source
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UCCLaser Safety
Angle of Apparent Source
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UCCLaser Safety
Accessible Emission Limits (AEL)
Area of limiting aperture MPE
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Department of Physics 63
LAAMPEAEL ×=
UCCLaser Safety
10.6µm Laser
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Department of Physics 64
21000 −= WmMPE
221000 rWmAEL π×= −
mWm
1002
01101000
2
≈
=
.π
UCCLaser Safety
980nm Laser
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Department of Physics 65
221 −= WmMPE
2221 rWmAEL π×= −
mWm
802
007021
2
..
≈
= π
UCCLaser Safety
Laser Pointers
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Department of Physics 66
25.25 −= WmMPE
22525 rWmAEL π×= −.
mWm
12
0070525
2
≈
=
.. π
UCCLaser Safety
Beam Type
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Department of Physics 67
UCCLaser Safety
Beam Type
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Department of Physics 68
UCCLaser Safety
Beam Type
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Department of Physics 69
UCCLaser Safety
Angular Measures
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Department of Physics 70
Hint: look up steradian
UCCLaser Safety
The Steradian
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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
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http://en.wikipedia.org/wiki/Steradian
θrL =
rL
Ω= 2rA
steradians−Ω
r
A
UCCLaser Safety
Steradian
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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
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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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 75
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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 76
UCCLaser Safety
Spatial Coherence
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 77
UCCLaser Safety
Retinal Irradiance
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 78
UCCLaser Safety
Power Through Apertures
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 79
UCCLaser Safety
Gaussian
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 80
UCCLaser Safety
Gaussian Cross-section
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 81
UCCLaser Safety
Large Beam
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 82
UCCLaser Safety
Small Beam
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 83
UCCLaser Safety
Intermediate Beam
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 84
UCCLaser Safety
Optical Fibre
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 85
0
63
22
πω
λθ
zzd ==
71
263
.
zNAzd == θ
UCCLaser Safety
Power through Aperture
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 86
UCCLaser Safety
Bare Diode Laser
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 87
UCCLaser Safety
Nominal Ocular HazardDistance (NOHD)
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 88
UCCLaser Safety
NOHD
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 89
UCCLaser Safety
Collimated
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 90
UCCLaser Safety
Focussed
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 91
UCCLaser Safety
Calculating NOHD
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 92
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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 93
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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 94
221 −= WmMPE
100 mm
300 mm
UCCLaser Safety
12mW at 980nm
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 95
Therefore:0
63
22
πω
λθ
zzd ==
( )( )
radm
m0880
10
9802222
0
..
===µπ
µ
πω
λθ
2
2
2
=
θπrA
UCCLaser Safety
Calculating NOHD
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 96
m30.=
( )22088021
012022
.
.
ππθ==
MPE
PNOHD
UCCLaser Safety
12mW at 980nm
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 97
100 mm
300 mm
mWAEL 80.=
UCCLaser Safety
12mW at 980nm
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 98
Therefore:
526
828
63
63
.
.
=→
=→
d
d
0
63
22
πω
λθ
zzd ==
300
100
=
=
z
z
UCCLaser Safety
12mW at 980nm
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 99
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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 100
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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 101
300 mm
What about safety to Class 1M?
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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 102
MPE: λ=980nm?
UCCLaser Safety
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 103
WCAEL 4
41021 −×= .
UCCLaser Safety
Class 1 @ λ=980nm
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 104
( ) ( ) 633101010 560500280500700980
4 ..// ==== −
C
mWAEL 4360.=
WCAEL 4
41021 −×= .
mWP 4360.= 0363012
4360.
.==→
mW
mWη
UCCLaser Safety
Class 1 @ λ=980nm
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 105
( )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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 106
mm412=
0
63
22
πω
λzd =
λ
πω
22
063dz =→
( ) ( )( )m
mmmz
µ
µπ
98022
10436
.
.=
UCCLaser Safety
12mW at 980nm
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 107
mmz 412=
mWAEL 4360.=
?? mm
Class 1 @ λ=980nm
UCCLaser Safety
An Easier Way!!
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 108
Calculate using MPE!
LAAMPEAEL ×=
LAA
AELMPE =→
2
2
3
2211
2
0070
104360 −−
=
×= Wm
WMPE .
.
.
π
UCCLaser Safety
An Easier Way
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 109
λ=980nm
Or, use the MPE table with the long viewing time
UCCLaser Safety
Class 1 @ λ=980nm
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 110
( ) ( ) 633101010 560500280500700980
4 ..// ==== −
C
26.11 −= WmMPE
2
42.3 −= WmCMPE
Previously calculated 11.22
UCCLaser Safety
An Easier Way!!
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 111
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
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
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 112
UCCLaser Safety
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 113
WCAEL 3
71093 −×= .
UCCLaser Safety
Class 1 Laser
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland
ROINN NA FISICE
Department of Physics 114
WAEL µ866.=
( )
nm
C
6335817
10 5500150
3
==
= −
λ
λ
@.
.
WAEL µ390.=nm532=λ@
UCCLaser Safety
Coláiste na hOllscoile Corcaigh, Éire University College Cork, Ireland 115
ROINN NA FISICE
Department of Physics
Class 1
And, this is consistent with the numbers provided
in the laser safety manual
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