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Dear Hazel,
In the US, all laser devices are classified as Class I, II, IIIA, IIIB,
or IV. The laser manufacturer must identify their lasers as such. Only
Class I and II can be operated without eye protection. The lasers you
describe are probably Class III or maybe even IV. When the flow
cytometer cabinet is equipped with the appropriate safegards such as
automatic shutters, it a safe device to operate.
Instrument alignment with exposed laser beams is generally considered a
"service" procedure to be performed by a trained "professional".
Regulations state that eye-protection MUST be worn, and all entry to the
room be blocked and posted with warning signs. Parts of the procedure
sometimes require visualization of the beam and eye protection cannot be
used. In such cases, extreme care should be taken, ESPECIALLY with
invisible UV beams. Eye damage may take place without any awareness by
the victim. The principal danger is direct exposure to the beam, but
stray reflections from a chrome-plated screwdriver or lens surface are
also hazardous. Damage can be inflicted to the skin as well, but
usually the effects are less disasterous (the skin can heal; eye damage
is usually permanent).
At our University, laser safety is taken very seriously and I never expose
the laser beams unless absolutely necessary and I follow the regulations
as much as possible. The safety officers acknowledge that sometimes the
eye protection cannot be used, but they are very uneasy about that situation;
however, there is no alternative they can offer except educating personnel
to the pertinent dangers. Instrument service personnel are often very
cavalier about exposed laser beams and should not be used as an example -
there are plenty of tales of partially blind service technicians.
Arc lamps are also dangerous, but are unregulated. However, arc lamps do
not produce coherent light and intensity falls off rapidly with distance.
Even so, I would place some kind of UV absorbing material between the
operator and UV source.
-- Neal Benson Phone: (904) 392-0008 Department of Pathology FAX : (904) 392-4693 Box 100275 Email: nbenson@nervm.nerdc.ufl.edu, or University of Florida neal@cell.pathology.ufl.edu Gainesville, FL 32610 USA
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