In article , Jeff Keller <jrk_om@xxxxxxxxxxx> writes
I believe the IC manufacturers kept going to higher light frequencies to
increase resolution of the image they used to etch their wafers. Is
there ultra high resolution film responding to UV?
Very vague memories - Wasn't someone taking pictures of animals at night
using infrared?
I wonder what an infrared picture of a Christmas tree would look like if
it were taken right after turning off the lights ... If someone down
under is celebrating Christmas in the winter maybe they could post some
pictures...
It wouldn't look much different from how it does in the visible band.
The "infrared" band usually used in photography, and certainly used by
the image convertor tube on a Nokta or similar is limited to below 1um
in wavelength. Looking at Planck's Law, black body radiation peaks at
1um for temperatures of about 3200degC, and your Christmas tree lights
cool down from that temperature within a fraction of a second when they
are turned off.
Lots of folk use this near infrared band for "covert" surveillance and
animal photography at night is one such application - but you do need a
source of illumination, such as a spotlight or flash, and that means it
isn't covert for anyone who has a similar camera. If you look at most
building security video cameras (especially the external types) they
will have a deep red spotlight next to them. That is because the
response of a silicon CCD expends into this band - silicon will go up to
900nm easily and can be extended to almost 1.2um if suitably treated at
manufacture. If you look at such spotlights at night there is a faint
visible red glow, due to a small amount of light in the visible band
being emitted.
Now, if you had the technology to go out to 5um or even 14um then its a
different story. No illumination source needed because peak emissions
occur for objects around normal terrestrial temperatures. This is real
covert surveillance - with obvious uses.
I work with stuff operating at these wavelengths every day, in fact i
have been designing a lot of it for a few decades, and you might see the
lights on the Christmas tree several HOURS after they are turned off. In
fact, you would be able to see the heat from your finger on the light
switch for several minutes after they had turned off. And see your hot
footprints on the floor where you walked over to the switch and where
you walked afterwards!
A fun trick I show folk that have never seen such cameras is the
telephone directory demo. Put your open hand on the front cover of a
telephone directory for about 10 seconds and then open it about 50-100
pages in - there is the image from the heat of your hand, with fingers
clearly visible. Wait a few seconds and then go another 50 pages - the
image is there as well. If you time it just right you can catch the
thermal wave as it propagates right through from the front cover to the
back although it gets less distinct after a thousand pages or more.
A lot of my colleagues refer to the sub-1um band as "infra-pink" - its
just barely infrared at all. ;-)
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's pissed.
Python Philosophers
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