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Electronics Technician Volume 9-Electro-Optics | Next
MARKERS/DESIGNATORS |
LASER CLASSIFICATION
As lasers became more numerous and more
widely used, the need to warn users of laser hazards
became apparent. To meet this need, laser classifi-
cations were established. Current classification
levels vary from optically safe, requiring no controls
(Class 1) to very hazardous, requiring strict controls
(Class 4).
CLASS 1
A Class 1 laser or laser system emits levels of
optical energy that are eye-safe and consequently
require no controls. An example of this class of laser
system is the checkout scanning device found in most
grocery stores.
CLASS 2 AND CLASS 3A
Class 2 and Class 3A lasers emit visible,
continuous-wave (CW) optical radiation levels
slightly above the maximum permissible exposure
(MPE) level.
Although these lasers can cause eye
damage, their brightness usually causes observers to
look away or blink before eye damage occurs. These
lasers have strict administrative controls requiring
placement of signs warning personnel not to stare
directly into the beam (figure 2-7).
WARNING
Class 3A lasers must not be
optically-aided devices.
CLASS 3B
viewed with
Class 3B lasers, and Class 3A lasers with outputs
of 2.5mW, are hazardous to personnel who are within
the beam path and look at the beam source directly or
by specular reflection. These lasers cannot produce
hazardous diffuse reflections.
Personnel working with these lasers should wear
appropriate protective eyewear during any operation
of the laser. Class 3B lasers have both administrative
and physical controls to protect personnel. Physical
controls include limited access work areas. Adminis-
trative controls include special warning signs posted
outside the entrances to the laser work spaces and
lights outside the entrances that warn personnel when
the lasers are in use. Figure 2-8 illustrates a laser
maintenance area warning sign.
CLASS 4
Class 4 lasers are high-power lasers that will
cause damage to unprotected eyes and skin through
intra-beam viewing and specular or diffuse
reflections. Consequently, no personnel should be in
a room where a Class 4 laser is operating without
Figure 2-7.—Examples of laser warning labels: A. Class 2; B.
Class 3A visible and near infrared; C. Class 3A infrared
and ultraviolet.
2-4
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