Measurement method of modulation degree and initial phase used for sinusoidal phase modulating interference measurement

Abstract

The invention relates to measurement of the modulation degree and the initial phase of sinusoidal phase modulating interference measurement. The object of the invention is to propose a method for overcoming the defect of complicated measuring process of the modulation degree in the sinusoidal phase modulating interference measurement, the method is simple and feasible, and the calculated modulation degree value avoids errors in the principle. According to the technical scheme, the measurement method of the modulation degree and the initial phase of sinusoidal phase modulating interference measurement includes: light splitting of light beams emitted by a laser is performed by employing a light-splitting apparatus to construct a Michelson interferometer, and sine modulation is performed on an interference phase by employing an external modulation technology or an internal modulation technology; and a photoelectric conversion module receives modulated Michelson interference signals, the Michelson interference signals are input to a signal processing module after analog-to-digital conversion, a fourth harmonic amplitude is extracted, and the modulation degree and the initial phase are solved through calculation. The method is mainly applicable to occasions of modulation interference measurement.

Description

Technical field [0001] The present invention relates to modulation degree and initial phase measurement of sinusoidal phase modulation interferometry, in particular to a modulation degree and initial phase measurement method for sinusoidal phase modulation interferometry. Background technique [0002] As a non-contact, high-precision displacement and topography measurement method, optical phase profiling is not only a research hotspot for scholars, but its results have also been widely used in metrology, manufacturing and other industries. As an important branch of optical phase profilometry, sinusoidal phase modulation interferometry has the advantages of simple modulation, no distortion, and high modulation frequency compared with step-by-step phase shifting and triangular wave modulation. In sinusoidal phase modulation interferometry, the accuracy of modulation and initial phase directly affects the accuracy of displacement and topography measurement. On the one hand, the exp...

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Problems solved by technology

[0003] In order to overcome the deficiencies of the prior art, the present invention aims to propose a method for overcoming the cumbersome shortcomings of the modulation degree measurement process in sinusoidal phase modulation interferometry, which is simple and easy to implement, and the obtained modulation degree value has no error in principle , for this reason, the technical scheme that the present invention adopts is, is used for the degree of modulation and initial phase measurement method of sinusoidal phase modulation interferometry, utilizes the spectroscopic device to split the light beam emitted by the laser to build a Michelson interferometer, and then use external modulation technology or internal The modulation technology performs sinusoidal modulation on the interference phase; the photoelectric conversion module receives the modulated Michelson interference signal, and after analog-to-digital conversion, it is input to the signal processing module to extract the fourth harmonic amplitude, and then calculate the modulation degree and initial phase

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