公开(公告)号：US20190257641A1

公开(公告)日：2019-08-22

申请号：US16340164

申请日：2017-10-11

Applicant: NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY

Inventor： Hidemi TSUCHIDA

IPC: G01B9/02 ,  G01J9/02 ,  G01S17/08 ,  G01S7/481

Abstract: An apparatus and a method which enable, in optical angle modulation, measurement of laser light, to measure by a delayed self-heterodyne method, accurate measurement of a temporal waveform of optical angle modulation, without any influence by light intensity modulation, without necessity of for calibration, and without necessity for stabilizing an interferometer. In an optical angle modulation measurement apparatus using a delayed self-heterodyne method, a heterodyne interferometer that is fed with laser light to be measured; a photodetector that receives output light of the heterodyne interferometer and performs heterodyne detection of the output light to output a beat signal; using a phase demodulator that is configured to demodulate a phase of a beat signal; and a temporal waveform analyzer that is configured to obtain a temporal waveform of optical angle modulation, from the phase of the beat signal. In an optical angle modulation measurement method by a delayed self-heterodyne method, laser light to be measured, which is optical-angle modulated is input to a heterodyne interferometer, heterodyne detection of the output light is performed by a photodetector, and a temporal waveform of optical angle modulation is obtained by demodulating a phase of the beat signal.

公开(公告)号：US20230052690A1

公开(公告)日：2023-02-16

申请号：US17788366

申请日：2020-10-29

Applicant: NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY

Inventor： Hidemi TSUCHIDA

IPC: G01S7/493 ,  G01S17/32 ,  G01S17/58 ,  G01S7/4912 ,  G01S7/48

Abstract: An optical measurement device includes at least a multi-frequency laser configured to simultaneously generate a frequency-fixed carrier and at least one frequency-modulated subcarrier, an optical branching element, a dual frequency beat signal generator, a difference signal generator, and an arithmetic processing unit. Either the carrier or the subcarrier within the output light of the multi-frequency laser is used as first measurement light and either the carrier or the subcarrier having a frequency different from that of the first measurement light is used as second measurement light. The dual frequency beat signal generator separates and outputs a first complex beat signal derived from the first measurement light and a second complex beat signal derived from the second measurement light. The difference signal generator outputs a difference signal between the first complex beat signal and the second complex beat signal.