Method and device for calibrating morphology compensation type four-optical-axis linear displacement laser interferometer

Abstract

The invention relates to a method and a device for calibrating a morphology compensation type four-optical-axis linear displacement laser interferometer and belongs to the technical field of laser measurement. According to the invention, a measurement beam of the calibrated laser interferometer passes through a middle through hole of a four-axis hollow laser interference mirror set and the measurement beam of the calibrated laser interferometer is placed in parallel at the middle position among four parallel standard measurement beams distributed in a side edge form of a regular quadrangular prism; in a plane vertical to the four standard measurement beams and in a square region formed by projection points of the four standard measurement beams in the plane, difference between the degrees that the four standard measurement beams and the measurement beam of the calibrated laser interferometer are interfered by the environment is small and the average value of the air refractive indexes of the four standard measurement beams is approximate to the value of the air refractive index of the measurement beam of the calibrated laser interferometer; a measurement error caused by the surface morphology of the reflecting surface of a target reflector is compensated into a linear displacement measurement result so as to ensure accuracy of a linear displacement measurement value.

Description

technical field [0001] The invention belongs to the technical field of laser measurement, and mainly relates to a laser interferometer calibration method and device. Background technique [0002] Laser interferometry linear displacement technology is a standard measurement technology with high precision. It is widely used in precision and ultra-precision machining, microelectronics equipment, nanotechnology industrial equipment and national defense equipment. In order to ensure the accuracy of laser interferometer measurement of linear displacement , requires a scientific and effective linear displacement laser interferometer calibration method and device. The general idea of ​​calibrating a linear displacement laser interferometer is to use a linear displacement laser interferometer with a higher level of precision for calibration. When the accuracy of the two is similar, it is called comparison. In the actual calibration work, most of the linear displacement laser interfe...

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Problems solved by technology

Since the two sets of laser interferometers are placed in parallel, the two paths of light are similarly affected by the environment, and the refractive index of air has little influence on the two paths of light. Big error

[0004] figure 2 It is a schematic diagram of the face-to-face laser interferometer calibration device. The standard measuring mirror and the calibrated measuring mirror are installed on the moving platform face to face. The advantage is that the measuring beam axes of the two sets of laser interferometers can be adjusted to almost the same measuring axis. The Abbe error is very small. The disadvantage is that the near end of one interferometer is the far end of the other.

[0005] In 2011, the National Institute of Metrology established the first 80-meter long-length laser interferometer measurement device in China (Leng Yuguo, Tao Lei, Xu Jian. Analysis of the accuracy and influencing factors of the dual-frequency laser interferometer system based on the 80-meter measurement device. Metrology and Testing Technology, 2011, 38(9): 47-49), the standard device used is to place three Agilent5530 long-distance dual-frequency laser interferometers in parallel to form a three-way laser interferometer, and the calibrated laser interferometer The instrument is placed between them for calibration and calibration. This scheme is a derivative of the parallel calibration method, and since three-way light is used for simultaneous measurement, it can compensate for the Abbe error during measurement. However, since three lasers are placed in parallel Therefore, the spatial position of the three-way standard measurement light is relatively far away, and the distance between the measurement light of the calibrated laser interferometer and each standard measurement light is also relatively long. All measurement light paths are affected by the environment differently, and the air refractive index has inconsistent effects on all measurement light paths. , resulting in inaccurate calibration measurements

Since the two sets of laser interferometers share one interferometer group and measuring mirror, it is impossible to determine whether the shared interferometer group and measuring mirror belong to the standard laser interferometer part or the calibrated standard laser interferometer part. Therefore, it is not exactly two sets Calibration of the laser interferometer for calibration

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