| 摘要 |
Apparatus which measures temperature in the high voltage environment of an electrical generator includes a temperature sensing element which includes a polarizing filter rotatable as a function of temperature. Light from a source is passed through the filter and the polarized light is again polarized through the use of a constantly rotating second polarizing filter behind which is a detector operable to provide an AC signal as a function of the doubly polarized light intensity. A reference beam is passed through the second rotating filter as well as a manually rotatable polarizing filter and is detected so as to provide a second AC signal. After an initialization, the AC signals are compared in phase, with the phase difference between them being a function of the temperature being measured.
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