ee5391aa%triton.unm.edu@ariel.unm.edu (Duke McMullan n5gax) (02/05/91)
From: ee5391aa%triton.unm.edu@ariel.unm.edu (Duke McMullan n5gax)
There are three principal methods of seeing in the "dark":
The oldest: sniperscopes. These required illumination in the very-near-inf-
rared to work. They have an image tube which is sensitive to infrared and
produces a version of the image of the scene on a small phosphor screen. The
biggest problem was (is) the IR light source. If THE ENEMY is using one of
these things, your IR light source makes a beautiful target. These were used
in WWII with good effect. A very common application was as a rifle sight.
Like most neat things, they're restricted in California.
Next: starlight scopes. Vietnam-era. These were actually "light amplifiers"
which would take a very low-level illumination and raise it up to something
human eyes could see. These also display on a phosphor screen. As would be
expected, the most recent ones give the best-quality images (and probably have
the most bugs ;^). They also respond to near-infrared, and a dark scene can
be illuminated with IR as with sniperscopes. They're expensive and restricted
in California.
(Parenthetical remark: Although they haven't nearly the sensitivity of a true
light amplifier, many camcorders are sensitive in the near-infrared, and can
be used with (I'm told) an IR illuminator for "dark viewing". I don't think
California has figured this out yet; you can still buy camcorders in and ship
camcorders into CA.)
Last: passive infrared imagers. I've never seen one of these or read detail-
ed info, so perhaps someone else can fill in the gaping holes. The heavy and
cumbersome devices will pick up and transform the infrared light emitted by
the objects in a scene into a viewable image. I know the 1550th Airborne has
these in some of their Super Jolly Green Giants (helicopters) which they use
for night landings. There are, of course, limitations. Soon after sundown,
while ground temperatures of things are different, and still somewhat higher
than the surrounding air, these work very well. In the predawn hours, when
everything is at nearly the same temperature, they're nearly useless -- just
like staring into a dense fog.
These boxes require cryogenic cooling (liquid nitrogen, I believe) to prevent
the viewer's own IR emissions from fouling things up. Similarly, you probably
can't use them effectively through a 'copter window; it's glowing actively in
the near infrared.
These will spot warm objects on the ground effectively in those predawn hours.
I don't know how effective they are at spotting bunker vents, personnel on the
ground, etc. I imagine some of the capabilities are classified.
These gadgets are extremely expensive. I don't think California has even
bothered to proscribe them.
That's all I know about these. Further info would be appreciated.
d
PS -- If you wanna be sticky, radar, sonar, etc., are also "seeing in the
dark. I don't feel like being sticky.
d
--
"Got to slap these Goddamn Third World nations around, Flynn," he said,
"until they learn some manners." -- Gregory MacDonald, from _Flynn_
Duke McMullan n5gax nss13429r phon505-255-4642 ee5391aa@triton.cirt.unm.eduedremy@elaine33.stanford.edu (eric remy) (02/06/91)
From: edremy@elaine33.stanford.edu (eric remy) In article <1991Feb5.041807.5114@cbnews.att.com> ee5391aa%triton.unm.edu@ariel.unm.edu (Duke McMullan n5gax) writes: > >Last: passive infrared imagers. I've never seen one of these or read detail- >ed info, so perhaps someone else can fill in the gaping holes. Passive thermal sights are one of the best things to come down the road in a long time. All modern US tanks are equipped with one; (M1, M1A1, and M60A3 with TTS (Tank Thermal Sight.)) my experience is with the 60A3 TTS. Effectiveness: Very. Since they work from the heat given off by objects, anything warm blooded or powered machinery are picked up no matter what time of the day. Other objects (rocks, trees) are warmed by the sun, and so late in the day and just before dawn are indeed the two worst times, however, you can still see reasonably well. Under ideal conditions, I've picked up rabbits and foxes at distances of >1 kilometer. Thermal sights have the additional advantage that they see through most forms of camoflage and smoke. The image can be degraded by rain, snow, or certain types of smoke such as white phosphorous. Picking up people is no problem: close enough and you can tell what they're wearing, skin color, etc. Air vents and such wouldn't be a problem if they were giving off heat of some kind. I'm not certain exactly how they're cooled. The TTS in a 60 has a small refrigerator which makes a horrible racket, but I don't really know what the cooling fluid is. They do have to be chilled to cryogenic temps to work well. Cost: I'm not really sure here. My instructor on the TOW missile told me that the thermal sight for a TOW runs about $50,000. I've never been given a price on the TTS: be assured that it's in the tens of thousands. It's also worth every penny. It makes night fighting a realistic possibility, increases chances of finding a target at any time of the day, and is generally the neatest toy on the tank... Hope this helps. -- ------------------------------------------------------------------------- Eric R. edremy@d31ha2.Stanford.EDU Deparment of Chemistry "Any desired property can be calculated from the Schrodinger equation of the system. The solution is left as an exercise for the reader." JIR, 3rd ed.