45
GB
Background radiation
Objects with low emissivity reflect
radiation emitted from nearby objects.
This additional reflected energy can
falsify mesaruement results. Generally
background radiaion equals the ambient
temperature.
If significantly warmer objects are in the surrounding area of the target object (heating,
machinery) this background radiation has to be compensated for. If the value of
background radiation is unknown you can determine it as follows:
- Set emissivity to 1.0.
- Adjust the lense focus to closest setting.
- Aim the imager 180° away form the target image and take a thermal image.
- Determine the average temperature of the image. This avarage is your background
radiation.
- Adjust the value for background radiation as described above.
Leather
0.75 to 0.80
Coal dust
0.96
Lacquer, glossy
0.80 to 0.95
Lacquer, matt
0.97
Black rubber
0.94
Plastic
0.85 to 0.95
Wood
0.90
Chromium oxides
0.81
Copper oxides
0,78
Iron oxides
0.78 to 0.82
Textiles
0.90
reflected
radiation
emitted
radiation
