Message Board Thread - "IR sensor"

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IR sensor Biswajit 11/17/2005
can anybody tell me why IR cameras used for night vision or general purpose survillence can not be used for thermography ie spatial temperature measurement
chak
 
Re:IR sensor Gary Orlove 11/17/2005
Night vision goggles amplify small amounts of visible light (and sometimes near infrared light) thousands of times so objects can be seen at night. These only work if some light is present ie. moonlight or starlight. Thermal imaging works by detecting the heat energy being radiated by objects and requires absolutely no light. One advantage of thermography over night vision technologies is that night vision goggles can be easily blinded just by shining a flashlight at them. Since thermal imager only look at the heat they are totally unaffected by light sources.

Since night vision sensors are not sensing emitted heat, they cannot display thermal patterns or temperatures about an object.

For more information on this and answers to common questions about IR thermography see http://www.infraredtraining.com/ir_primer.asp .

Gary Orlove
Infrared Training Center
 
Re:IR sensor Biswajit 11/17/2005
Thanks for your reply
Regards
Chak
 
Re:IR sensor JKostrzewa 12/6/2005
The answer about night-vision goggles is correct; these are not senstive to heat but are rather amplifying light. There are also IR cameras that are not suitable for temperature measurement. The reason is simply that they are not calibrated and/or sufficiently repeatable to measure absolute temperature accurately. A suitable analogy is your eyes response to visible light. You can tell white from black and discriminate lots of gray shades in between. But very few of us are sufficiently calibrated to tell the photometric brightness of a given source.
 


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