[time-nuts] Thoughts on IR thermometers?

Neville Michie namichie at gmail.com
Wed May 28 05:08:02 EDT 2008

A point of clarification on Infrared.
Thermal infrared is used to measure temperatures. Wavelength about 10  
Lenses made of strange materials like germanium or some polymers.  
Sensors are also strange materials, lead teluride?
Most cameras used scanning optics, often mirrors. Radiation from  
objects at room temperature can be detected.
A large and expensive setup.

Near infrared has wavelength of 1 micrometre, Lenses made of selected  
glasses, sensor
can be sensitive film or silicon sensor. Radiation is only detectable  
from objects at 500 degrees or more.
Main use is photography by reflection from incandescent or LED lights.
A digital camera can see an IR LED.

Cheers, Neville Michie

On 28/05/2008, at 6:32 PM, Hal Murray wrote:

>> I found a cheap IR sensor (not a spot meter) useful to identify the
>> one IC that's warmer than the others in a fully populated PWB.
> I usually use my fingers for that sort of test.  :)
> Warning.  Don't try it on really hot chips!  I have a small lump on  
> my thumb
> leftover from touching a chip that was trying to self-destruct.   
> (bus clash)
> Does anybody know of a low cost camera that works in IR?  I expect  
> somebody
> probably makes a slightly modified version of one of the USB  
> cameras for just
> this sort of work.
> I found this while poking around.  How to modify your webcam:
>   http://www.hoagieshouse.com/IR/
> Basically, take it apart, remove IR filter, add visible filter (old  
> slide
> film), put it back together.
> -- 
> These are my opinions, not necessarily my employer's.  I hate spam.
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