Physical quantity sensor and physical quantity measuring method

摘要

A physical quantity sensor includes a semiconductor laser for irradiating an object with a laser beam, and a laser driver for operating the semiconductor laser in such a way that a first oscillation period for which the oscillation wavelength increases and/or a second oscillation period for which the oscillation wavelength decreases is repetitively present. The sensor further includes a photodiode and a current-voltage conversion amplifying unit both for detecting an MHP containing an interference waveform formed by the self-coupling effect between the laser beam and the returning light beam from the object, a MHP extracting unit for measuring the period of the interference waveform contained in the output signal from the current-voltage conversion amplifying unit each time the interference waveform is inputted, and a computing unit for computing the displacement and/or the speed of the object from the measured individual period MHP extracting unit.

主权项

1. A physical quantity sensor comprising:
a semiconductor laser emitting a laser beam toward an object to be measured; an oscillating wavelength modulator causing the semiconductor laser to operate so that there is at least a first oscillating period wherein an oscillating wavelength continuously increases monotonically and a second oscillating period wherein the oscillating wavelength continuously decreases monotonically; a detector detecting a mode hop pulse that includes an interference waveform that is produced through the self-coupling effect between the laser beam that is emitted from the semiconductor laser and return light from the object being measured; a mode hop pulse extractor measuring, each time an interference waveform is inputted, a period of the interference waveform that is included in the output signal from the detector; and a calculator calculating at least a displacement or a velocity of the object being measured, based on the individual periods measured by the mode hop pulse extractor, wherein the calculator calculates at least one of the displacement and the velocity of the object from the frequency of the sampling clock for measuring the period of the interference waveform, a reference period, an average wavelength for the semiconductor laser, and an amount of change in the period measured by the mode hop pulse extractor relative to the reference period.