How To Make Accurate Ir Measurements - General IRT657 Manual Del Usuario

mm
S
inches
D
D:S=12:1
Fig. 3. The IRT657's thermometer's field of view
HOW TO MAKE ACCURATE IR
MEASUREMENTS
The IRT657 has a distance-to-spot (D:S) ratio of 12:1. This
means that the target area (spot) whose infrared radiation
(temperature) is being measured increases in diameter by
1 inch for every 12 inches you move away from the target.
Conversely, the diameter of the target area measured
decreases by 1 inch for every 12 inches you move closer
to the target.
All IR thermometers (IRTs), including the IRT657, 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. 3), 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.
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