Major-minor phase discriminator based subdivision method of dual-frequency laser interferometer

Abstract

The invention relates to a method for subdividing dual-frequency laser interferometers on the basis of a main phase discriminator and an auxiliary phase discriminator, which comprises the following steps: firstly, pretreating two paths, namely a reference path and a measurement path, of photoelectric signals of the laser interferometer, inputting the photoelectric signals into a reversible counter for signal acquisition, performing eight frequency division on the pretreated signals, inputting the signals into the main phase discriminator for data acquisition, performing phase shift on models of the reference path, and inputting the models of the reference path with Fm_8 into the auxiliary phase discriminator for data acquisition; secondly, resetting the reversible counter, and making an initial phase angle of the main phase discriminator operated within an interval of 0.5+ / -0.125 and a phase angle of the auxiliary phase discriminator operated within an interval of 0.62+ / -0.125; thirdly, making a CPU enter a sampling interruption program when a timing signal arrives to latch data; fourthly, performing error judgment on the data acquired in the third step; and fifthly, performing error elimination and synthesis on the data. The dual-frequency laser interferometers have the characteristics of quick measuring speed, high resolution and multi-frequency phase locking frequency tracing bandwidth during actual measurement.

Description

technical field

[0001] The invention relates to a phase subdivision method of a laser interferometer, in particular to a subdivision method of a dual-frequency laser interferometer based on a main and auxiliary phase detector. Background technique

[0002] The dual-frequency laser interferometer can achieve high-magnification subdivision and high measurement resolution through the principles of optics and electronics. Only relying on the optical system, ordinary interferometers can only achieve half-wavelength resolution, that is, on the order of 0.1 μm. The current interferometer improves the measurement resolution through electronic subdivision. Products from foreign companies such as Agilent and ZYGO can achieve 2048 Subdivision, the maximum resolution reaches 0.15nm. At present, there is no good instrument in China as a benchmark for nanoscale measurement.

[0003] Realization of laser high-resolution measurement: The high-resolution of laser interferometer is realized...