"Infrared"

[John Roberts <roberts@xxxxxxxxxxxxxxxxx>]

>Date: Thu, 22 Feb 1996 10:07:42 -0600
>From: Ronald J Beck 840196 <rbeck@xxxxxxxxxxxxxxxx>
>Subject: Re: PHOTO-3D digest 1190 

>I think you'll find that a lot of the imaging systems used in warfare 
>these days is infrared.  And don't think that this means those hard-to-see 
>reddish hued displays that everyone sees on TV.  The images I've seen on 
>demo units they've set up in the hall is almost like watching tv in black 
>& white.  It even showed the outline of a person's hand that they had 
>placed against their pants leg and then removed.  During another demo I 
>was able to read license plate numbers on cars in the parking lot in the 
>middle of the night with no lights in the area!

>I would love to see this technology combined with some sort of stereo 
>vision unit (binoculars maybe?, stereo video w/ lcd glasses?).

>P.S. Texas Instruments is one of the leaders in night vision technology.  
>We make more than calculators & computer chips! :-)

Your post didn't entirely differentiate three major night vision technologies:

1) Image amplification: this can use visible-wavelength light, but it's
   converted to electrical signals, which are amplified many thousand-fold
   to permit viewing by ambient light. (Found on some surplus Russian equipment
   which has reached the US market, also includes the "starlight scopes" sold
   to amateur astronomers.) From your description of the demo in which license
   plates on parked cars were read, it sounds like they may have used this
   approach - cars that have been parked at night for a long time shouldn't
   have large enough thermal variations to permit imaging by radiated IR.

2) Imaging by near-infrared (wavelength only slightly longer than that of
   visible red light). Typically an IR light source is used - this is the
   old "sniperscope" approach. This system does not permit the viewing of
   thermal patterns, but is not dependent on ambient sources.

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.

I've seen Russian night vision binoculars (at Price/Costco), but I had the
impression that they don't really produce stereo.

Note: I don't have any access to classified information on imaging systems.
A number of imaging technologies with military origins have started to appear
in non-military applications, to the considerable benefit of astronomers, among
others.

John R


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