User Manual
93
Non-uniformity appears in the image. Perform a
non-uniformity calibration
Temperature measurement is
inaccurate
Emissivity setting is incorrect. Check and amend the
emissivity setting.
Filter range is inappropriate. Select a filter range that is
suitable for the target temperature being measured.
The target is not in focus. Adjust focus.
Condensation on camera lens. Place camera in a dry
area at room temperature until condensation evaporates.
Non-uniformity is severe. Press non-uniformity
calibration.
Emissivity
What Is Emissivity?
The standard of radiation is "blackbody" radiation which exists in any enclosure whose walls
are at a uniform temperature. The shape of the enclosure and the wall material have no effect
on this radiation, it being a function of temperature alone.
A small hole in such an enclosure only affects this radiation level very slightly. The area of the
hole should not exceed 5% of the area of the walls of the enclosure, when the radiation passing
through the hole is within about one part in a thousand of the blackbody radiation level defined
by the wall temperature. Such a device is fairly easy to build and forms the source on which all
thermometers are calibrated.
A surface always emits less radiation than would a black body at the same temperature by a
factor called the "emissivity" of the surface.
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