On Sun, 11 Nov 2007 15:04:47 GMT, aemeijers wrote:

Some digital cameras and webcams already respond to IR.

There are various instructions around on how to convert them into IR cameras.
http://www.metacafe.com/watch/395292...igital_camera/

No thanks are necessary. Just send me the C-note.

Don


Interesting- a 'Red Green' solar eclipse/welding viewer. Too bad my toy
digital doesn't have a protruding lens. I'll have to stare at my digital
camera and my box of old odd fittings from my collection of 'real' (aka
film) cameras and see if anything jumps out at me.

The IR response of a digital camera is useless for thermal imaging. This response
maybe extends as far downward as 1.2 microns. Thermal imaging cameras respond to
very long wave IR in the 8 to 14 micron range. The usual imager is an array of
microbolometers that measures actual heating at each pixel and not a CCD or CMOS
device. The better ones use cooled arrays to reduce ambient thermal noise.

The reason thermal imagers are so expensive is that glass cannot be used for lens
material, as it doesn't pass longwave radiation. The traditional lens material is
pure germanium. Just the lens for the thermal imager I used to own cost almost $20k.
I understand that calcium fluoride has become a popular lens material and is
responsible for driving the cost down.

One other comment while I'm here. Handheld or fixed mount IR imaging cameras are NOT
FLIR, though there is a company that as adopted the military acronym as its name.
Forward Looking InfraRed refers to the technology used on planes and helicopters. The
imaging system used in these applications is as much different from the handheld
units as a handycam is to an HiDef studio camera.

I once bought two FLIRs for one of the "B" bombers (B1 or B2, I can't recall now) at
a DMRO surplus sale. Probably one of those sales of strategically sensitive
technology that Congress got its panties in a wad about.

This thing was over 4 ft long and probably 2 ft in diameter and required a forklift
to move. All the optics were germanium including the massive objective lens that was
probably a foot in diameter. It had cooled gold-plated copper AZ-EL mirrors on
frighteningly fast servo mechanisms. The imager itself was cooled somehow -
thermoelectric or sterling, probably. My casual testing showed that it could resolve
a half a degree F between two bodies.

The output was incredible. No smearing or blooming like civilian imagers. Razor
sharp crispness. Full 30 hz frame rate. It had several video output formats
including composite which I used to drive a B&W monitor.

I played with one of them for awhile and then sold them for mucho $$$ to a PCB
manufacturing company that used them for high speed inspection of boards during
burn-in.

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com -- best little blog on the net!
Tellico Plains, Occupied TN
Risk: $20 hooker, year old condom.