How does an Infared Thermometer work?
Thanks
How does an Infared Thermometer work?
Thanks
There is a heap of information on just that topic here:
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...
Bolometer?
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 measurement.
PIRs work by utilising a segmented lens to create the chopper effect to contrast the moving body from the background temperature.
Grant.
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