| With the increase of the requirements for the surface shape of optical components in the precision manufacturing industry,the calibration of interferometer system errors is becoming more and more important.Among them,the detection using the liquid surface as a reference surface is a highly accurate absolute inspection method.In this paper,combined with dynamic fizeau interferometer based on lateral displacements of the point sources,static and dynamic liquid level absolute inspection schemes are studied,and the systematic error measurement is achieved.First of all,designed a dynamic Fizeau interferometer based on off-axis point light source,due to the fluidity of the liquid surface,the traditional method of promoting the phase shift of piezoelectric ceramics is no longer applicable.Therefore,the vertical dynamic Fizeau interference system is studied in this paper.In order to realize the transient measurement,a point light source array is constructed.Interferograms with different phase shift amounts are obtained by the point light source offset from the main optical axis.Combined with this dynamic interferometer,this paper proposes a method of absolute liquid level absolute test,and explores a method of dynamic liquid level absolute test based on the principle of random averaging.Then,the key technologies of the static liquid surface absolute inspection method based on silicone oil are discussed.The liquid surface stability evaluation index was established to investigate the stability of liquids with different viscosity and thickness.This liquid has a certain impact resistance.Through multiple experiments and analysis,the thickness of the liquid required for the liquid level absolute test is obtained.In order to obtain a liquid surface with better flatness,the conditions of the container holding the liquid are analyzed,and the influence of various factors such as the shape,size,support method and self-weight of the container on the flatness and stability of the liquid surface are investigated,and the experimental verification was carried out.The method of absolute liquid level inspection has very high requirements on the external environment.The specific control conditions are analyzed in terms of temperature,air flow,vibration and cleanliness.In addition,this paper also explores a dynamic liquid surface absolute inspection method based on crop-based liquid metal,and uses a new type of non-toxic liquid metal.In order to solve the problem of matching the light intensity,a model of the sieve diffraction is calculated,and an appropriate sieve is selected to obtain an interference pattern with good contrast.The vibration morphology of liquid metal was explored,and a suitable random average experiment number was selected to obtain stable calibration test results.At the same time,the experimental repeatability and reproducibility were verified,and the effects of system error and experimental error were analyzed.At the end of the article,the same interferometer was used to calibrate the system error.The static liquid level absolute test method and the dynamic liquid level absolute test method were used.In order to verify the accuracy of the results,a comparison experiment was designed.The comparison experiment based on the four-step rotation method based on the parity function was used.A comparative analysis of the results of the liquid level absolute test method proves the accuracy of the liquid level absolute test method.Finally,the PV measurement value of the static liquid surface absolute test method was 22.1nm.The PV measurement value of the dynamic liquid surface absolute test method was 20.2nm.The PV measurement value of the four-step rotation method based on the parity function was 21.5nm.The residuals obtained by the three absolute test methods are all below 1.5nm. |
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