| 摘要 |
A dual-frequency grating interferometer displacement measurement system, comprises a dual-frequency laser, an interferometer, a measurement grating and an electronic signal processing component. The measurement system realizes displacement measurement based on grating diffraction, optical Doppler effect and optical beat frequency theory. Dual-frequency laser light is emitted from the dual-frequency laser and split into reference light and measurement light via a polarization spectroscope. The measurement light is incident to the measurement grating to generate positive and negative first-order diffraction. The diffraction light and the reference light form a beat frequency signal containing displacement information about two directions at a photo-detection unit, and linear displacement output is realized after signal processing. The measurement system can realize sub-nanometer and even higher resolution and accuracy, and is able to measure long horizontal displacement and vertical displacement at the same time. |
| 主权项 |
1. A dual-frequency grating interferometer displacement measurement system, comprising a dual-frequency laser (1), an interferometer (2), a measurement grating (3) and an electronic signal processing component (4), and wherein the interferometer (2) comprises a polarization beam splitter (21), a wave plate, a refraction element (23), a reflector (24), an analyzer (25) and a photoelectric detector;
dual-frequency laser light is emitted from the dual-frequency laser (1) and transmitted through an optical fiber and is split into reference light and measurement light by the polarization beam splitter (21), the reference light passes through a reference arm quarter-wave plate (22′) and is reflected by the reflector (24) so as to generate two beams of parallel reference light which transmit through the reference arm quarter-wave plate (22′), the polarization beam splitter (21), the analyzer (25) and then are incident to a first photoelectric detector (26) and a second photoelectric detector (27) respectively; the measurement light transmits through a measuring arm quarter-wave plate (22) and the refraction element (23) and then is incident to the measurement grating (3) to diffract, positive and negative first-order diffracted measurement light transmit through the refraction element (23), the measuring arm quarter-wave plate (22), the polarization beam splitter (21), the analyzer (25) and then are incident to the first photoelectric detector (26) and the second photoelectric detector (27); the two beams of parallel reference light along with the two beams of diffracted measurement light form beat frequency electric signals through the first photoelectric detector (26) and the second photoelectric detector (27), which beat frequency electric signals are then transmitted to the electronic signal processing component (4) to be processed; meanwhile, the dual-frequency laser (1) outputs a reference signal to the electronic signal processing component (4); when the interferometer (2) and the measurement grating (3) move relatively in x and z directions, linear displacements in two directions are output by the electronic signal processing component (4). |
