公开(公告)号：US20220090907A1

公开(公告)日：2022-03-24

申请号：US17417925

申请日：2019-04-18

Applicant: HARBIN INSTITUTE OF TECHNOLOGY

Inventor： Pengcheng HU ,  Di CHANG ,  Jiubin TAN

IPC: G01B9/02

Abstract: Present disclosure relates to a heterodyne grating interferometric method and system for two-degree-of-freedom with high tolerance. The system comprises a separately modulated heterodyne laser (1), an optical prism (23) and a photoelectric detection and signal processing unit (4). The separately modulated heterodyne laser (1) simultaneously outputs two laser beams at different frequencies, which are incident in parallel to a first beamsplitting surface so as to be split, and then a part thereof is incident to a retro-reflector (233) to produce reference beams (53a, 53b), which are incident to a third beamsplitting surface, and the other part traverses a double-diffraction structure formed by a measured grating (3) and retro-reflectors (234a, 234b) to obtain two measured beams (59a, 59b), which are incident to a second beamsplitting surface and then are divided into two parts. Wherein one part is converged to form a first interference beam (61), and the other part is incident to the third beamsplitting surface and is converged with the corresponding reference beams (53a, 53b) to form second and third interference beams (62, 63). Photoelectric detection and signal processing is performed on the interference signals of the three interference beams (61, 62, 63), so as to calculate horizontal and vertical displacement of the grating (3). The present measurement method and system improve the angular tolerance of tip and tilt of the optical grating (3) while increasing the fold factors.

公开(公告)号：US20230061358A1

公开(公告)日：2023-03-02

申请号：US17706343

申请日：2022-03-28

Applicant: Harbin Institute of Technology

Inventor： Hongxing YANG ,  Ziqi YIN ,  Pengcheng HU ,  Jiubin TAN

IPC: G01B9/02001 ,  G02B27/28 ,  G02B5/30 ,  G02F1/11

Abstract: The present disclosure provides a multi-frequency hybrid heterodyne laser tracker system based on a single light source. According to the laser tracking system proposed in the present disclosure, multi-frequency laser is obtained by conducting multi-acousto-optic frequency shift on a dual-longitudinal-mode laser unit, and an absolute ranging precision gauge is constructed by using a dual-longitudinal-mode interval of a light source. With the frequency shift difference of a multi-acousto-optic frequency shifter, an absolute ranging roughness gauge is constructed, and the relative displacement measurement of dual-frequency light interference is achieved. Meanwhile, by utilizing the reflection of multiple reflectors and light splitting and combining of polarization prisms, synchronous measurement of multi-wavelength absolute distance, relative displacement and PSD position is achieved, resolving the problem that an existing laser tracker uses multiple light sources, which leads to difference in measurement datum, and consequently to the difficultly in traceback.

公开(公告)号：US20210203121A1

公开(公告)日：2021-07-01

申请号：US17022343

申请日：2020-09-16

Applicant: Harbin Institute of Technology

Inventor： Hongxing YANG ,  Yun ZOU ,  Ziqi YIN ,  Jing LI ,  Pengcheng HU ,  Jiubin TAN

IPC: H01S3/131 ,  G01K1/02 ,  H05B1/02 ,  H01S3/13

Abstract: The disclosure provides a high-frequency-reproducibility laser frequency stabilization method and device based on multi-point acquisition of laser tube temperature. The laser frequency stabilization device includes: a frequency stabilization control circuit. The frequency stabilization control circuit includes a polarizing beam splitter, an optical power conversion circuit, an A/D conversion circuit, a temperature measuring circuit, a microprocessor, a D/A converter and a heating film driver. The polarizing beam splitter is disposed outside any one of laser transmitting holes. The optical power conversion circuit is disposed on reflection and refraction optical paths of the polarizing beam splitter. The optical power conversion circuit, the A/D conversion circuit, the microprocessor, the D/A converter, the heating film driver and a plurality of groups of heating films are sequentially in one-way connection. Temperature sensors, the temperature measuring circuit and the microprocessor are sequentially in one-way connection. The method of the disclosure can increase the frequency reproducibility of a laser device from 10−8 to 10−9. The device of the disclosure can effectively avoid the drift of a final frequency stabilization temperature point.