Abstract: A system for measuring temperature within a region to be tested includes a sensor means responsive to the temperature within the region for transmitting light energy along an optically-transmissive path and detector and amplifier means responsive to the light energy for producing an output signal which represents the intensity of the light energy. A signal processor electronically calculates a display signal from the output signal which represents the temperature within the test region. The signal processor performs this calcuation by solving Planck's equation, and a successive bisection technique is utilized to achieve extremely fine resolution of the temperature.

Abstract: An optical fiber thermometer system utilizing the laws of blackbody radiation includes a sensor responsive to the temperature within a region to be tested for transmitting light energy generated as a function of the temperature according to Planck's equation along an optical transmission line, and a detector responsive to the light energy for producing an electrical current. The current is amplified by a linear amplifier having provision for automatically controlling the gain of the amplifier, depending upon the magnitude of the input current, to reduce the dynamic range of the input current. The output of the linear amplifier is a voltage which is used by a signal processing network to yield an accurate indication of the temperature within the region to be tested by solving the Planck equation between two predetermined wavelengths representing upper and lower limits of an optical filter which filters light energy entering the detector.