Frequently Asked Questions
Emergency Contacts
Laser Classifications
Summary of basic
biological effects of light
Eye Protection
Wes McMinn – Safety and Health Officer -
Dial: (931) 393-7313 or local ext. 313
There are five laser hazard classes:
- Class 1 lasers and laser
systems cannot emit accessible levels of radiation that are capable of
causing eye injury under any normal operating condition. (A more hazardous
laser may be embedded in a Class 1 product that is not accessible during
normal operating conditions, but may be during service and maintenance.)
- Class 2 lasers and laser
systems are visible lasers with an accessible output ≤ 1 mW. Class 2 lasers
and laser systems are incapable of causing eye injury unless intentionally
viewed directly for an extended period. The normal aversion response to
bright light (blinking) protects the eye from a momentary exposure.
- Class 3a lasers and laser
systems have an accessible output between 1-5 mW and do not pose a serious
eye hazard unless viewed through optical instruments.
- Class 3b lasers and laser
systems have an accessible output between 5-500 mW for continuous wave
lasers and < 0.125 J within 0.25 second for a pulsed laser. Class 3b lasers
and laser systems pose a serious eye hazard from viewing the direct beam or
specular reflections.
- Class 4
lasers and laser systems have an accessible output > 500 mW
for a continuous wave laser and > 0.125 J within 0.25 second for a pulsed
laser. Class 4 lasers and laser systems pose a serious eye hazard from
viewing the direct beam, specular reflections and diffuse reflections. Class
4 lasers and laser systems also pose skin and fire hazards.
|
LASER CLASSIFICATIONS--SUMMARY OF HAZARDS |
|
|
Applies to
--- wavelength ranges --- |
|
------------ Hazards ------------ |
|
Class
|
UV
|
VIS
|
NIR
|
IR
|
|
Direct ocular
|
Diffuse ocular
|
Fire
|
|
I |
X |
X |
X |
X |
|
No |
No |
No |
|
IA |
-- |
X* |
-- |
-- |
|
Only after
1000 sec |
No |
No |
|
II |
-- |
X |
-- |
-- |
|
Only after
0.25 sec |
No |
No |
|
IIIA |
X |
X** |
X |
X |
|
Yes |
No |
No |
|
IIIB |
X |
X |
X |
X |
|
Yes |
Only when laser
output is near
Class IIIB limit
of 0.5 Watt |
No |
|
IV |
X |
X |
X |
X |
|
Yes |
Yes |
Yes |
|
|
|
Key: |
X
*
** |
=
=
= |
Indicates class applies in wavelength range.
Class IA applicable to lasers
"not intended for viewing" ONLY.
CDRH Standard assigns Class IIIA
to visible wavelengths ONLY. ANSI Z 136.1 assigns Class IIIA
to all wavelength ranges. |
|
|
SUMMARY OF BASIC BIOLOGICAL EFFECTS OF LIGHT |
|
Photobiological spectral domain
|
Eye effects
|
Skin effects
|
|
Ultraviolet C (0.200-0.280 µm) |
Photokeratitis |
Erythema (sunburn)
Skin cancer |
|
Ultraviolet B (0.280-315 µm) |
Photokeratitis |
Accelerated skin aging
Increased pigmentation |
|
Ultraviolet A (0.315-0.400 µm) |
Photochemical UV cataract |
Pigment darkening
Skin burn |
|
Visible (0.400-0.780 µm) |
Photochemical and thermal retinal injury |
Photosensitive reactions
Skin burn |
|
Infrared A (0.780-1.400 µm) |
Cataract, retinal burns |
Skin burn |
|
Infrared B (1.400-3.00 µm) |
Corneal burn
Aqueous flare
IR cataract |
Skin burn |
|
Infrared C (3.00-1000 µm) |
Corneal burn only |
Skin burn |
|
 |
