| 摘要 |
A fiber optical measuring apparatus in accordance with the invention utilizes the thermal shift of the absorption edge in doped insulators such as colored glass filters. A radiant energy source is operable in a first, normal mode for temperature measurement, and is selectively operable in a second mode for calibration purposes. In the first mode, the source emits light at a wavelength extending into the absorption edge, and in the second mode emits light at a wavelength removed from the absorption edge and at which transmission of the light through the sensing element is not affected by temperature shift. A reference photodetector coupled to the radiant energy source to receive light directly therefrom provides a correcting signal to correct for variations in source intensity. Means are provided for compensation for variations in the temperature of the source.
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