IR Cam brochure..

  • For those interested in IR cam, this document is well made
    http://www.optris.fr/telecharg…ds/Zubehoer/IR-Basics.pdf


    it is done by the manufacturer of the Optris cam used by Lugano test.


    IR cam are according toe the documentation array of microbolometers (FPA, field plane array bolometers), so they measure radiated heat in the chosen bandwidth, 7.5-13µm for our case.

  • Here is on article cted in lugano report
    http://gis.ess.washington.edu/keck/aster/IEEE97.htm
    A Temperature and Emissivity Separation Algorithm for Advanced Spaceborne Thermal Emisssiona and Reflection Radiometer (ASTER) Images


    Here is also the patent cited
    http://www.google.com/patents/EP0129150A2?cl=en
    Method for the contactless radiation measurement of the temperature of an object independent of its emissivity, and device for carrying out this method

  • Hi


    I have tried to judge of the possibility that Lugano test result is endangered by Emissivity uncertainty


    From the manufacturer documentation it appears that IR cam just measure the energy received in the wavelength range


    I have made a spreadsheet


    https://docs.google.com/spread…UiL5sJFg/edit?usp=sharing


    the idea is that for temperatures and wavelength I estimated by the Planck law,
    I averaged (flat distribution, maybe not the good one, but this is approximation) the luminance over the 7.5-13um and i obtain a measurement which is what I estimate the IRcam received if the body was black.


    I adjusted the result to account from what the physicist have entered as the emissivity/temperature curve assuming rey body. I compare the value with the one at 450C (assuming the calibration is correct at 450C).



    one thing I found is that the luminance on the IR cam range is nearly linear with the temperature...



    the result is that it seems that the IR cam recieved 2.8 more energy at perceived 1400C, because it assume the emissivity was nearly halved... 2.5x radiated energy at 1250.


    this shows that an error in emissivity could reduce greatly the real temperature.
    imagining that the emissivity is the same at 800-900W (perceived 1250/1400C) than at 450W/450 then the temperature may only be 850C and 925C (800-900W).


    it is a great error, however anyway the total radiated energy is anyway
    5.8x and 8x assuming that the faulty emissivity is stable as assumed to explain the IR cam error...
    This is to compare with the 1.75 and 2x power in on the active run.


    thus it seems that what the emissivity error cause as error on the temperature, it correct on the total boltzman law power radiated.
    Emissivity error seems not to be an excuse for the skeptic position, it is on the opposite increasing the result.
    Note that lowering the emissivity is not possible as the temperature would be too huge, and i1400C is already hard to swallow... and skeptics don't swallow it.


    the weakness of my quick spreadsheet is that I did not add the estimated convection power.
    As I have understood of the report it is linear with temperature, not T^4, and it is about the same range as radiation around 450C.


    It seems I neglected too many factors in my sheet, because the apparent COP from the temperature is much more huge than the 3.6 given by the physicists


    If someone can correct , and extend with convection factors.


    if someone could also estimate what should be the emissivity to have COP=1, if possible..


    Here is my curve of the luminance averaged over 7.5um-13um depending on celsius temperature, with the linear curve fitting with 91%*(T-218°C)


    maybe that estimated approximation of temperature to IRcam response can allow to make good estimation if the impact of emissivity