Title:
METHOD AND SYSTEM FOR MEASURING INTERFERENCE OF TWO-DEGREE-OF-FREEDOM HETERODYNE OPTICAL GRATING HAVING HIGH TOLERANCE
Document Type and Number:
WIPO Patent Application WO/2020/133820
Kind Code:
A1
Abstract:
A method and system for measuring the interference of a two-degree-of-freedom heterodyne optical grating having high tolerance, the system comprising a separate modulation heterodyne laser module (1), an optical grating interference mirror group (23) and a photoelectric detection and signal processing unit (4); the separate modulation heterodyne laser module (1) simultaneously outputs two lasers having different frequencies, which are incident in parallel to a first optical splitting surface so as to be optically split, and then a part thereof is incident to a backward reflector (233) to produce reference beams (53a, 53b), which are incident to a third optical splitting surface, and the other part traverses a secondary diffraction structure formed by a measured grating (3) and backward reflectors (234a, 234b) to obtain two measured beams (59a, 59b); and the lasers incident to a second optical splitting surface are divided into two parts, wherein one part is optically combined to form a first interference beam (61), and the other part is incident to the third optical splitting surface and is optically combined with the corresponding reference beams (53a, 53b) to form second and third interference beams (62, 63); optical beat frequency signals of the three interference beams (61, 62, 63) are subject to photoelectric detection and signal processing to calculate horizontal and vertical displacement information of the optical grating. The present measurement method and system improve the deflection angle tolerance of the optical grating (3) while increasing the optical subdivision number.
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Inventors:
HU PENGCHENG (CN)
CHANG DI (CN)
TAN JIUBIN (CN)
CHANG DI (CN)
TAN JIUBIN (CN)
Application Number:
PCT/CN2019/083131
Publication Date:
July 02, 2020
Filing Date:
April 18, 2019
Export Citation:
Assignee:
HARBIN INST TECHNOLOGY (CN)
International Classes:
G01B9/02; G01B9/00; G01B11/00; G01B11/02
Foreign References:
| CN109579694A | 2019-04-05 | |||
| CN108627100A | 2018-10-09 | |||
| CN103604376A | 2014-02-26 | |||
| CN104634254A | 2015-05-20 | |||
| CN106289068A | 2017-01-04 | |||
| JPH085329A | 1996-01-12 |
Attorney, Agent or Firm:
KINGSOUND & PARTNERS (CN)
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