🚀 go-pugleaf

ACTIVITIES 3 and 4  (addendum)
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The safety aspect of using low power He-N lasers in physics labs was not
mentioned in my descriptions. According to Metrologic Instruments Inc.
(Coles Rd at Rte 42, Blackwood, NJ 08012) a one-milliwatt laser is "judged
to be eye-safe, except possibly in the case of deliberate long-term direct
staring into the beam". The power rating of common demonstration lasers is
often 2 or 3 mW and precautions should be taken to prevent injuries.

The light intensity can be lowered with an ordinary polarizer. It can also
be lowered by splitting the beam and by absorbing the unused component. For
example, about 15% of light can be reflected from an ordinary glass surface
(assuming the beam is polarized) when the angle of incidence is 60 degrees.
Activities 3 and 4 can be performed at low levels of laser beam intensities,
preferably in partial darkness.

           Ludwik Kowalski         kowalski@apollo.montclair.edu