optris Top-down GIS, Operator'S Manual

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Basics of glass measurement 37
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5 Basics of glass measurement
In general, non-contact temperature measurement on glass is very suitable. However, the following points
should be considered:
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Angle of view
•
Emissivity
•
Coatings
•
Correct sensors
•
Heat and dust
Also pay attention to the measuring depths:
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1,0 to 3.9 µm for deep layers
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5.0 and 7.9 µm for surface
5.1 Reflection and transmission
Reflection and transmission must be considered:
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For long wavelength devices 8-
14 µm (LT) the emissivity ε is about 0.85.
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For devices with a wavelength range of 5.0 µm (G5) or 7.9 µm (G7) t
he emissivity ε is > 0.90 and there
is a low angular dependence of the reflectivity ρ