5 - Measuring parameters

The bolometer (left) measures the temperature difference caused in the absorbent by radiation. It uses thermistor for it. The thermopile (right) measures the temperature different with thermoelemets in serial connection.

A room temperature operating thermal imaging camera can be built up using pyroelectric materials. The photocatode of a conventional vidicon camera is replaced by a pyroelectric film, which generates electrical charge superimposed to the thermal image. The face of the receiving tube is an infrared transmitting window. Imaging radiation impinges on the pyroelectric film and an electron beam reads out the charge created. The charge density is than displayed simultaneously to the scanning. The disadvantages of PEV are its complicated and large structure sensitive to mechanical effects due to the piezoelectric behavior.