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From: nahshon@dan.haifa.ibm.com (Itai Nahshon)
Subject: Re: Who makes CCD cameras for IR light?
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In-Reply-To: vdbergen@aix1.uottawa.ca's message of 17 Aug 1994 01:07:59 GMT
Date: Wed, 17 Aug 1994 12:21:59 GMT
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In article <32rntf$bs6@csi0.csi.UOttawa.CA> vdbergen@aix1.uottawa.ca (Herman Van Den Bergen) writes:

> ... stuff deleted ...

>Thanks for the replies. It appears CCDs are not sensitive in the 'far
>IR' spectrum - unless I want to spend a lot of money.

>Somebody asked why I want to use IR. I was hoping to pick up the
>animal's location like a hot spot so that no fancy video analysis
>would be required. I believe CCD shift out their data? That would

> ... stuff deleted ...

>Herman.

Herman,
You are looking for a voery long wavelength camera. I think it's called
"Thermo Imaging". There are such cameras but they are not simple not
cheap.

Thing of just two details:
1. Glass lenses are not transparent to the wavelength you are
talking about. I think they make the lenses of Germanium (which is
opaque to ordinary light.
2. The average wavelength emitted by a warm body (that works well for
the sun, normal light bulbs, Infra-red heaters and animal bodies) is a
function of the bodies' temperature. The ambient temperature may be
near 300 degrees (Kelvin) and the animals skin is just a few degrees
warmer. The sensor is supposed to detect that difference.
Now remember that camera circuits are emitting heat themselves (call that
internal "noise"). The internal noise has to be reduced by cooling the
sensors with liquid nitrogen.

Itai Nahshon


 

reduce internal noise in the sensors they should be much cooler than

nitrogen)
