US 12,259,473 B2
Optical measurement device and measurement method
Hidemi Tsuchida, Tsukuba (JP)
Assigned to NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY, (JP)
Appl. No. 17/293,066
Filed by NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY, Tokyo (JP)
PCT Filed Nov. 15, 2019, PCT No. PCT/JP2019/044883
§ 371(c)(1), (2) Date May 12, 2021,
PCT Pub. No. WO2020/110779, PCT Pub. Date Jun. 4, 2020.
Claims priority of application No. 2018-222416 (JP), filed on Nov. 28, 2018.
Prior Publication US 2021/0405194 A1, Dec. 30, 2021
Int. Cl. G01S 17/34 (2020.01); G01S 7/48 (2006.01); G01S 17/58 (2006.01)
CPC G01S 17/34 (2020.01) [G01S 7/4808 (2013.01); G01S 17/58 (2013.01)] 10 Claims
OG exemplary drawing
 
1. An optical measurement device comprising:
a laser that outputs light of which a first frequency is modulated;
a photodetector;
a heterodyne optical system that splits output light of the laser into two components, uses one as probe light, uses the other as reference light, adds a frequency shift to one of the probe light and the reference light, applies the probe light to an object, combines scattered light from the object and the reference light, and causes the combined light to be incident on the photodetector;
an IQ demodulator that removes a component of the frequency shift, and outputs an in-phase component I and an orthogonal component Q by receiving a beat signal and an output of the heterodyne optical system as an input; and
an arithmetic operation processor that calculates a phase and a second frequency of the beat signal from the in-phase component I and the orthogonal component Q and excludes a component of a Doppler shift from the phase, calculates the average value of absolute values of one modulation period, and calculates the distance to the object on the basis of a proportional relationship between the distance and the average value of the absolute values of the phase which has been calibrated in advance.