Re: gEDA-user: sparkfun 4 layer boards To: gEDA

["John E. Perry" <j.e.perry@xxxxxxx>]

John Doty says:

> Nope. Quantum efficiency of silicon detectors drops like a rock just
> beyond 1 ?m wavelength: the radiation just goes right through without
> interacting. Indeed, Si wafers make excellent entrance windows for
> for thermal IR detectors.
v
> A 350 K blackbody emits ~271 ?W/mm2 of thermal radiation, but only
> ~4.4 fW/mm2 of that is short of 1 ?m. With very fast optics,
> cryogenic temperatures, a state of the art scientific CCD, the
> extremely low noise video chains I design for astronomy, and rigorous
> exclusion of every optical photon, you might be able to see
> something. With commercial/industrial technology, not a chance.
>
> On the other hand, a 350 K component is pretty easy to find with your
> finger...

So how do they do this (answer in the last URL)?

http://www.x20.org/thermal/
http://www.temperatures.com/tivendors.html
http://www.opticsplanet.net/heat-seekers-termal-imagers.html
http://en.wikipedia.org/wiki/Thermography


John Perry


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