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re IR filter source

Mike Arman <armanmik@n-jcenter.com> wrote:

I seem to remember a discussion about Lidar jammers (?) which relied on an
IR filter which turned out to be very expensive and hard to get.

Got a catalog yesterday from "Electronic Goldmine" 1-800-445-0697 which
offers Kodak type 87C IR filters, 75mm square, new in factory sealed
envelopes, for $3.49 each, their part number G9935. If this is what you're
looking for, here it is.
The 87C has about 0.55% transmission at 790 nm, and 3% at 800 nm.  This
would make the jammer output visible at night to some people with good red
response, if the filtered source was not too close to the headlights, but
probably invisible in the daytime.  Note, however, that Kodak filters are
generally produced as gels and acetates, and need to be protected from heat
and moisture.  I suspect this is the case here, given the price.  One might
want to use one or more for countermeasure experimentation, if one has a
LIDAR to perform experiments with (possibly available on the highways for
modest but accelerating cost).  A visibility test would also be useful, once
a source was selected.

                .... Kirby   (Kirby A. Smith)
                              2 x 1988 90q
                          New Hampshire USA