Laser Module 2
Laser Module 2
Laser Module 2
www.riskmanagement.ubc.ca
Skin Sensitivity:
- Epidermis (UV-B, UV-C)
- Dermis (IR-A)
Visual Response
Laser Spectrum
Gamma Rays
10-13
10-12
10-11
X-Rays
10-10
10-9
Ultra- Visible
violet
10-8
10-7
Infrared
10-6
10-5
Microwaves
10-4
10-3
10-2
Radar
waves
10-1
TV
waves
Radio
waves
10
102
Wavelength (m)
LASERS
200
300
Visible
400
500
600
Near Infrared
700
800
900
1000
1100
Far Infrared
1200
1300
1400
1500
10600
Wavelength (nm)
ArF
193
XeCl
308
KrF
248
Ar
488/515
HeNe Ruby
633 694
2w Alexandrite GaAs
Nd:YAG
755
905
532
Nd:YAG
1064
CO2
Communication
10600
Diode
1550
Lasers operate in the ultraviolet, visible, near infrared, and far infrared regions of the spectrum.
400-1400nm
Affects the retina
1 - 280 nm
UV-B (Far)
280 - 315 nm
UV-A (Near)
315 - 380 nm
Visible Light
380 - 780 nm
Near IR (IR-A)
780 - 4000 nm
Middle IR (IR-B)
4um - 14 um
Far IR (IR-C)
14um 100 um
Ultraviolet region
UV-C (100280nm)
Cornea surface
UV-A (315400nm)
Affects the lens
UV-B (280-315nm)
Absorbed by the cornea
% UV
nm Absorption
100
280
6
92
300
16
45
320
37
340
14
12
34
360
2
36
48
52
1
1
2
Infra-red Region
Near IR
(< 1400nm)
Affects the retina
Far IR
Affects cornea and aqueous humor
25 m
THERMAL BURNS
ON PRIMATE RETINA
Photo courtesy of U S Air Force
This image shows the macula of the eye of a rhesus monkey. The light spots on this retina were produced
by 0.25 s exposures to a green laser beam with a power of 10 mW. Each of these exposures heated the
retinal tissue to the point that the protein cooked, producing a white burn.
This is the most common type of laser eye injury in humans. It is likely that thousands of people have
received these small retinal burns. They are permanent blind spots. If the burn is outside the macula, the
effect on vision is small. If the burn is inside the macula, the effect is much greater. One such burn in the
center of the macula will mean that you cannot thread a needle using that eye. A slightly larger spot or
multiple spots will make reading difficult.
This type of injury can be prevented by wearing laser safety eyewear.
This is an image of the retina of a human who experienced an eye injury from a repetitive pulse near
infrared laser. The beam was invisible. In such cases people do not usually realize they are being exposed
until their vision has been severely effected. The persons eye was moving during this exposure. This
resulted in a line of laser burns on the retina. This is a color enhanced image to better show the laser
damage.
The macula of the eye is located out of the photo to the lower left. This individual was lucky that the
damage did not extend into the macula.
The correct laser safety eyewear would have prevented this injury.
This is a human eye injury resulting from four pulses into the macular region from an AN/GVS-5 Nd:YAG
laser rangefinder. The pulse duration was about 20 ns and the pulse energy was about 15 J. The safe
exposure limit for this pulse duration is 2 mJ per pulse. Thus, this exposure was 7500 times the safe level.
Short pulse lasers produce the greatest eye hazards. Each short pulse results in a tiny explosion in the
retina. The resulting shockwave causes severe damage to the retinal tissue.
This photo was taken three weeks after the exposure. It shows the permanent destruction of the macular
region. Visual acuity in the eye is approximately 20/400 and will not improve.
This is a surface burn on the cornea of a rabbits eye caused by exposure to a CO 2 laser beam of a few
watts. All the laser energy was absorbed by water on the surface of the cornea. This heated the cornea
causing the protein in the corneal tissue to cook.
Human eye injuries from far infrared lasers have been rare, but they have occurred.