LumaSense Technologies MC320 Manual - Manual (Page 25)

MC320 Thermal Imager Manual Principle of Thermal Imaging 25
4.6 Background Noise
When measuring the temperature of an object by a radiation
thermometer, it is important to take into consideration the
above-mentioned emissivity correction as well as the
environmental conditions where the measurements will be
performed.
Infrared rays enter the thermal imager from the measuring object
as well as all other objects nearby. Therefore, in order to avoid
this influence, a function of environment reflection correction,
etc. is required. Also, when accurate data is required, it is
necessary to minimize the influence by shortening the
transmission route of the infrared ray, for example.
The following methods may be useful to reduce background
noise.
1. Shorten the distance between the measured object and
of the thermal imager. Please keep a safe distance to
protect the operator as well as the instrument.
2. Have no high temperature object behind the measured
object, such as the sun shining on the back of the
measured object.
3. Do not allow direct sunlight to strike thermal imager.
4. Do not allow obstacles such as dust or vapor (which
attenuates the infrared signal) between the measured
object and the thermal imager.
4.7 Practical Measurement
There are a number of methods for correcting emissivity in order
to obtain the true temperature. The correction procedure with
each method will be explained next.
1. Method of comparison or direct measurement with
emissivity equal to approximately 1.0
1. Stabilize the temperature of the measured object or
similar material.
2. Open a very small hole (hereafter called blackbody
part) in the object which the thermal imager must
measure as to satisfy blackbody conditions.
3. Then set the emissivity correcting function of thermal
imager so that the temperature of the blackbody part
and the measured surface will be the same. The
obtained emissivity will be the emissivity of the
measured surface.
Note:
For low temperatures,
masking tape or
cornstarch can be used.
Note:
If you already know the
emissivity, you can
make thermal imaging
measurements
immediately.