4-3 Measurement Field Distance/Spot ( D/S ) value
The object must large than spot size calculated by the
measurement Distance/Spot ratio ( Distance Factor, refer to
page 4 ). For accurate measurement, a 1.5 times distance/spot
size is recommended.
Careful collimating is required when the object is not
large enough, if the temperature of the object or a part of
it is higher ( or lower ) than the ambient temperature.
After the direction of the probe ( little move the probe ),
the ideal collimating is obtained the display registers the
maximum ( or minimum ) reading. However the emissivity
of the object and its ambient must be roughly the same.
4-4 Disturbance
Objects with low emissivity or objects with a low
temperature but high emissivity, emit little infrared energy.
Fig. 2
9
