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How does an Infared Thermometer work?

Discussion in 'Electronic Design' started by [email protected], Nov 16, 2012.

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  1. Guest

    How does an Infared Thermometer work?

  2. whit3rd

    whit3rd Guest

    There's an optical system that couples a small thermistor to incoming
    light. Then, there's a low-noise sense amplifier that amplifies t he
    resistance deviation, and an anticipation circuit or algorithm that
    compensates for the sluggish response of the thermistor's temperature
    to its heat source. And there's a calibration curve.

    Basically, it's like warming your hands at the fire. The hotter the
    fire, the warmer your hands get. Put a pinhole in front of the
    fire to keep the fire's size from affecting the result...
  3. Grant

    Grant Guest

    High temperature pyrometers use a thermocouple stack (well, they did back
    in late '70s when I worked with them). A water cooled jacket establishes
    the cold end of the thermocouple and cools the lens. Low temperature ones
    can work on same principle, but use exotic lens material like arsenic
    trisulfide or germanium to pass the longer infrared wavelengths.

    Motor driven optical choppers were used back then too, for trans-ambient

    PIRs work by utilising a segmented lens to create the chopper effect
    to contrast the moving body from the background temperature.

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