Optical-modulation-type sensor and process instrumentation apparatus employing the same

摘要

An optical-modulation-type sensor comprises an input condenser lens for collecting light from a light source, a polarizer for linearly polarizing the light from the input condenser lens, a light-transmissive piezo-oscillator which is provided with an oscillator circuit and to which the linearly polarized light is introduced from the polarizer, an analyzer for linearly polarizing the light from the piezo-oscillator, and an output condenser lens for converging the linearly polarized light from the analyzer. A process instrumentation apparatus using the sensor of the structure described above further comprises an optical fiber for transmitting the light from the light source to the optical-modulation-type sensor, a photoelectric converter operatively connected to an output side of the optical-modulation-type sensor for converting to an electrical signal the transmitted light which is intensity modulated with the oscillation frequency of the piezo-oscillator, and a signal processing unit for acquiring a process quantity based on the frequency of an output signal from the photoelectric converter.