Tim
Thanks, that all makes sense. It is a delight to read an authority
on a subject.
BTW, the para below reflects the attempts being made some years ago
to make dual-band sensors that would be able to "look through" poor
visibility, but that would also be suitably sensitive when the
conditions were better.
Chris
Usually the IR detectors used for high temperatures are chosen to
be sensitive to shorter wavelengths than the 8uM used for low temperatures
because both the detector sensitivity and the energy emitted can be many
orders of magnitude better at those wavelengths. There are a variety of
semiconductor detectors that are used, some using exotic materials and these
are what are probably used in the weapon systems you are familiar with.
Silicon photocells (without the filters used for camera cells) will work
quite well at near IR wavelengths up to 950nM or so. Glass lenses of course
filter out long IR wavelengths so that even if the film worked for much
longer wavelengths and the other problems of storage etc were overcome the
lenses would be opaque and not work.
Regards,
Tim Hughes
>>hi100@xxxxxxx<<
--
<|_:-)_|>
Chris Barker
imagopus@xxxxxxxxxxxxxxxx
... a nascent photo library.
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