optris Bottom-Up GIS 450i G7, Operator'S Manual

Page: 50 / 57

-
50
-
5.3 Hardening of glass sheets
•
Temperature has a direct influence on glass quality
•
Testing for the heating profile (temperature distribution)
Linescan function (line scanning) with PI camera from below.
Direct effects: Defective or inhomogeneous surfaces can be detected by the measurement.
Tempering: Change of the heating/cooling degree depending on the temperature distribution
5.4 Angle dependency
The angle dependence is another important factor to be considered when measuring temperature.
On the uncoated side the values are constant up to an angle of 45°.
On the coated side (low-E) the 60° optics is preferred, since the influence of the emissivity change is
negligible here.
The following two figures show the emissivity as a function of angle (G5, G7, LT) for Low-E glass at 250 °C.
Once for coated glass and once for uncoated glass.