Making Accurate Measurements - General IRT105 Manuel De L'utilisateur

MAKING ACCURATE MEASUREMENTS

The IRT105 has a distance-to-spot (D:S) ratio of 6:1. This
means that the target area (spot) whose infrared radiation
(temperature) is being measured increases in diameter by
1 inch for every 6 inches you move away from the target.
Conversely, the diameter of the target area measured
decreases by 1 inch for every 6 inches you move closer to
the target.
All IR thermometers (IRTs), including the IRT105, take the
average temperature of all objects within a circular target
area (spot). Although the distance "D" in the D:S ratio is
defined as a linear value and the "S" defines the diameter of
the spot (see Fig. 4), the critical parameter is the target area.
Depending on the distance to the target (the object whose
temperature you want to measure), the target area may
include both the target and background objects near or
behind the thermometer's field of view, which defines the
target area or spot.
Fig. 4. The IRT105's field of view
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