Standard classification for lasers
From: wellison@kuhub.cc.ukans.edu
Newsgroups: sci.electronics
Subject: CDRH Laser regulations
Date: 28 Feb 94 10:33:39 CST
Organization: University of Kansas Academic Computing Services
As posted by the Center for Devices and Radiological Health (CDRH) regulation
21 CFR 1040.10 and 21 CFR 1040.11, the standard classification for lasers are
as follows:
Class I laser product
No known biological hazard. The light is shielded from
any possible viewing by a person and the laser system is interlocked to prevent
the laser from being on when exposed.
(large laser printers such as the DEC LPS-40 has a 10mW HeNe driving it which
is a Class IIIb laser, but the printer is interlocked so as to prevent any
contact with the exposed laser beam, hence the device produces no known
biological hazard, even though the actual laser is Class IIIb. This would also
apply to CD players and small laser printers, as they are Class I devices).
Class II laser products
Power up to 1 milliwatt. These lasers are not
considered a optically dangerous device as the eye reflex will prevent any
occular damage. (I.E. when the eye is hit with a bright light, the eye lid will
automatically blink or the person will turn thier head so as to remove the
bright light. This is called the reflex action or time. Class II lasers won't
cause eye damage in this time period. Still, one wouldn't want to look at it
for an extended period of time.) Caution labels (yellow) should be placed on
the laser equipment. No known skin exposure hazard exist and no fire hazard
exist.
Class IIIa laser products
Power output between 1 milliwatt and 5 milliwatt.
These lasers can produce spot blindness under the right conditions and other
possible eye injuries. Products that have a Class IIIa laser should have a
laser emission indicator to tell when the laser is in operation. They should
also have a Danger label and output aperature label attatched to the laser
and/or equipment. A key operated power switch SHOULD be used to prevent
unauthorized use. No known skin hazard of fire hazard exist.
Class IIIb laser products
Power output from 5 milliwatts to 500 milliwatts.
These lasers are considered a definate eye hazard, particularly at the higher
power levels, which WILL cause eye damage. These lasers MUST have a key switch
to prevent unathorized use, a laser emission indicator, a 3 to 5 second time
delay after power is applied to allow the operator to move away from the beam
path and a mechanical shutter to turn the beam off during use. Skin may be
burned at the higher levels of power output as well as the flash point of some
materials which could catch fire. (I have seen 250mW argons set a piece of red
paper on fire in less than 2 seconds exposure time !) A red DANGER label and
aperature label MUST be affixed to the laser.
Class IV laser products
Power output >500 milliwatts. These CAN and WILL cause
eye damage. The Class IV range CAN and WILL cause materials to burn on contact
as well as skin and clothing to burn. These laser systems MUST have:
A key lockout switch to prevent unauthorized use
Inter-locks to prevent the system from being used with the protective covers
off
Emission indicators to show that the laser is in use
Mechanical shutters to block the beam
Red DANGER labels and aperature labels affixed to the laser
The reflected beam should be considered as dangerous as the primary beam.
(again, I have seen a 1,000 watt CO2 laser blast a hole through a piece of
steel, so imagine what it would do to your eye !)
Registration of laser systems
Any laser system that has a power output of greater than 5 milliwatts MUST be
registered with the FDA and Center for Devices and Radiological Health if it
has an exposed beam, such as for entertainment (I.E. Laser light shows) or for
medical use (such as surgery) where someone other than the operator may come in
contact with it. (this is called a 'varience' and I have filled them out and
submitted them and they ARE a royal pain in the backside !)