5. Technical Information
5-1 Distance to Spot Ratio
The D:S Ratio is the ratio of the distance from the target to
the target diameter (spot). This is determined by the optics
of the unit. The smaller the target, the closer you should be
to it. For an accurate measurement, the target must
completely fill the spot. Failure to fill the spot will result in an
inaccurate measurement, due to the averaging of the target
with the surrounding areas.
5-2 Emissivity
Emissivity is the relative ability of an object to emit energy by
radiation. Perfect emitters have an emissivity of 1, emitting
100% of incident energy. An object with an emissivity of
0.8 will absorb 80% and reflect 20% of the incident energy.
Emissivity is defined as the ratio of the energy radiated by
an object at a given temperature, to the energy emitted by
a perfect radiator at the same temperature. All values of
emissivity fall between 0.0 and 1.00.
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