LumaSense Technologies MC320 Manual - Manual (Page 26)

26 Principle of Thermal Imaging MC320 Thermal Imager Manual
4. Thereafter when measuring the same type object, it is
unnecessary to change the emissivity setting.
2. Method of direct measurement of emissivity
If a hole cannot be made as in method 1, then apply black
high emissivity paint and carry out the same procedures
to obtain the emissivity. Since the black paint will not
provide a perfect blackbody, first set the emissivity of the
black paint and then measure the temperature.
3. Indirect measurement
Measure a sample similar to the measured object, and
place it in a condition able to be heated by a heater, etc.
Then measure the object and the sample alternately with
the camera and when the indicated values are identical,
measure the sample with a contact-type thermometer.
Adjust the emissivity of the thermal imager to cause the
temperature readout to match that of the contact
measurement. The resulting emissivity is that of the
sample.
4. Measuring by Wedge effect
With this method, the emissivity of the measured surface
itself is enhanced through use of the wedge or semi-
wedge effect. But one must be careful about the number
of reflections and/or the measuring angle.
A small change in angle will reduce the emissivity
enhancement.
Measuring by Wedge
effect