Message Board Thread - "reflected apparent temperature"

Back to Threads | Back to Forums

TitleByPosted On
reflected apparent temperature Ben10 4/11/2008
HI.

How does the reflected apparent temperature settings affect the reading and do you always change this setting or just leave it at 20C.
 
Re:reflected apparent temperature Doctir bob 4/11/2008
For opaque targets, the IR camera receives both emitted and reflected IR energy from the target. With knowledge of target emissivity and reflected apparent temperature, the camera can calculate the true target temperature. It does this by taking the reflected apparent temperature and using it to calculate the reflected energy. It subtracts this from the total energy measured, to get the emitted energy. Then it divides the result by the emissivity to get the blackbody equivalent energy and finds the equivalent target temperature in the calibration lookup tables stored in the IR camera. That is the temperature displayed on your IR camera.

If you put in the proper emissivity and reflected apparent temperature values, you get a correct reading for target temperature within the calibration accuracy of the IR camera. If you don't put in the correct values, the errors can range from small to very large depending on emissivity and reflected apparent temperature values.

For high emissivities and indoor targets, reflected apparent temperature has less effect than for medium emissivity targets outdoors where for a clear, dry sky the reflected apparent temperature can be -60F. Then the effect will be large.

We recommend Building Science or, for predictive maintenance applications, our Level I thermography training courses for more information on this important topic.

 
Re:reflected apparent temperature Ben10 4/11/2008
Thanks Doc,

I have just completed the free BCAM Basics course. Along with your info, it is clearer now. Lets do some testing.
 
Re:reflected apparent temperature KRG 5/12/2008
Doctir bob wrote:
que targets, the IR camera receives both emitted and reflected IR energy from the target. With knowledge of target emissivity and reflected apparent temperature, the camera can calculate the true target temperature. It does this by taking the reflected apparent temperature and using it to calculate the reflected energy. It subtracts this from the total energy measured, to get the emitted energy. Then it divides the result by the emissivity to get the blackbody equivalent energy and finds the equivalent target temperature in the calibration lookup tables stored in the IR camera. That is the temperature displayed on your IR camera.

If you put in the proper emissivity and reflected apparent temperature values, you get a correct reading for target temperature within the calibration accuracy of the IR camera. If you don't put in the correct values, the errors can range from small to very large depending on emissivity and reflected apparent temperature values.

For high emissivities and indoor targets, reflected apparent temperature has less effect than for medium emissivity targets outdoors where for a clear, dry sky the reflected apparent temperature can be -60F. Then the effect will be large.

We recommend Building Science or, for predictive maintenance applications, our Level I thermography training courses for more information on this important topic.

Doct "IR",
The IR Community knew we could count on you for your vast knowledge concerning Infrared Thermography.
Great Explanation.
 


  • Back to Threads
  • Back to Forums

     

  •   Copyright © FLIR Systems, Inc 2012