SONEL KT-640 THERMAL IMAGER
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9. Accurate temperature measurement
The accuracy of temperature measurement depends mainly on the following factors. Dur-
ing measurement, the camera makes corrections based on signals from its sensors.
However, in certain situations, manual correction of parameters might be necessary.
Emissivity
. Infrared radiation measurements are based on reception of infrared radiation
emitted by objects. The amount of radiated energy depends on two base factors: the tem-
perature and the emissivity of the surface of an object. Default value of the emissivity coeffi-
cient is 0.98 and it is applicable to most surfaces.
Values of the emissivity coefficient for some materials are presented in the emissivity table
(see chapter 14).
Improper value of the emissivity coefficient can cause significant errors of the temperature
readout, therefore the camera allows for adjustment of the emissivity coefficient value within
the range of 0.01...1.00 (see section 4.5 and 8.2).
When changing the emissivity coefficient value, it is crucial to check the readout of ambient
temperature in the camera (see below).
Accuracy of measurement also depends on
ambient temperature
. By default, the tempera-
ture measured by the camera is used, however it might be improper, especially during op-
eration in low temperature or measurements from a location of temperature differing from
ambient temperature of the examined object. In order to maintain accuracy of measure-
ments, proper value of ambient temperature should be accounted for -
especially, if the
emissivity coefficient is changed or these changes will be performed by processing a
thermal image with computer program
. This value should be changed manually in order
to determine proper relation of the examined object temperature and the temperature of cer-
tain types of surroundings (e.g. the sky, snow).
Adjustment of ambient temperature is described in section 8.2.
The influence of
distance
from the examined object onto the accuracy of measurement can
be significant, depending on the medium the object is placed in (air, for, smoke, etc.) and its
reducing properties related to thermal radiation. It is possible to correct the default value (1.8
m) within the range of 0.1...30 m. The method of adjustment is described in section 8.2.
Relative humidity
can also influence the accuracy of measurement; the default value (70%)
can be changed to any value within the range of 0...100% (this function is described in sec-
tion 8.2).
Additionally, to achieve an accurate temperature readout, hold the camera stably and adjust
focus properly. Before capturing the image, it is recommended to invoke the auto-calibration
of the camera (by pressing and holding
button for 3 seconds
– see section 3.1).
Summary of Contents for KT-640
Page 14: ...SONEL KT 640 THERMAL IMAGER 14 Available colour palettes 1 2 3 4 5 6 7 8...
Page 49: ...USER MANUAL 49 3 in the next window select General and then Restart now 4 go to Troubleshoot...
Page 50: ...SONEL KT 640 THERMAL IMAGER 50 5 go to advanced options 6 select Startup settings...
Page 54: ...SONEL KT 640 THERMAL IMAGER 54 And select an option as below...
