Re: "Infrared"

[wier@xxxxxxxxxxxxxxx (Bob Wier)]

>
>3) Imaging by thermal infrared (very long wavelength, for instance one might
>   image the predominant wavelengths given off by humans or vehicles). An
>   interesting feature of these systems is that they usually employ optics
>   made of semiconductor such as germanium - imagine a lens that appears to
>   be carved out of a chunk of metal. It is traditionally required that the
>   imager be cooled to very low (i.e. cryogenic) temperatures, but there *may*
>   be non-classified systems that don't require such extreme cooling.
>

These seem to be pretty interesting. I've exchanged notes with a fellow
who had the loan of a $30K version of one of these. He pointed it at his
PC when he turned it on and watched the components heat up as they ran
for awhile - it graphically demonstrated the need for some heat sinking
on the cpu...

I'm kinda assuming that there are non-cryogenic systems now since a similar
development has occurred on amplifiers used in Satellite tv reception. When
I got my first satellite system, the amplifier out on the dish was rated
at (I think) 200 degrees noise temperature - and it was *extremely* expensive
to better that figure. Later on there was a breakthru (HEMT devices) and
today you can buy a replacement which is effectively in the 25 degree noise
range at a reasonable cost, but doesn't require liquid nitrogen to run it 
:-)

THANKS

    -------- Bob Wier ----- wier@xxxxxxxxxxxxxxx -----
  East Texas State University Computer Science Dept.
   keeper of the Motorola MC68HC11, ICOM Radio, and
   Overland-Trails mailing lists and the LDS Genealogy
               State Research Outlines 
         "Congress - n. - the antonym of Progress"



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