4.3.5 Reference Temperature
The detector of the thermal imager has a thermal drift over the time and must be corrected by self referenc-
ing. At applications where a high measurement accuracy is needed, the thermal image can be corrected
permanently by setting a reference temperature. Using the menu Tools, Configuration, Device and
Reference temperature several options for manual or automatic correction can be set.
Fig. 36 View Reference Temperature
If there is an area within a thermal image having a constant temperature value (e.g. black body) the Source
can be defined as a Fixed value. By the option Compare with measuring area the area with constant
temperatures can be determined. The known reference value can be set within Fixed value. If the temper-
atures are changing slightly within the defined area due to a thermal drift, the whole image will be corrected
by a certain factor.
Alternatively, the correction can be done by an external value (e.g. via connected pyrometer) by choosing the
process interface PIF in, see Chap. 4.5.
There are several Fitting modes to adjust the thermal image.
Auto The software is choosing the best way of correcting the image (offset or gain).
Offset This kind of correction is recommended if there are big temperature differences between the
reference temperature value and the thermal image.
Gain This kind of correction is recommended if there are small temperature differences between
the reference temperature value and the thermal image.
The option Consider flag is decreasing the influence of the cameras correction (high temperature steps)
onto the display of the reference temperature. It is recommended to activate this option.
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