Micro Angle Measurement Method And Experimental Research Based On F-P Etalon

Aiming at the problem that the accuracy of micro-angle measurement technology is obviously lagging behind the developed countries and the traceability is poor,a new method of self-calibrating micro-angle measurement is studied by using the relative measurement principle which based on the Fabry-Perot(F-P)etalon multibeam interference.The standard conical beam emerging from the F-P etalon is used as the measuring beam.According to the characteristics of the imaging concentric interference ring,the new plane array pixel information processing technology is used to accurately measure the small angle.The research work mainly includes the following parts:(1)Research on the principle and method of micro angle measurement based on F-P etalon.According to the multi-beam interference characteristics,the standard conical beam with the cone angle law of the F-P etalon is used as the measuring beam,so that the accurate measurement of the micro angle can be realized according to the center displacement of the concentric interference ring and the focal length of the imaging objective.Using the massive data of imaging concentric rings,combined with the new plane array information processing technology to accurately and effectively process the image information of the area array.Using the relative measurement principle,the mathematical model of the micro-angle measurement and the uncertainty is deduced by the mathematical statistics method.(2)Aiming at the accurate measurement of the displacement of the center of the circle,a multi-chord averaging method is proposed for the calculation of the coordinates of the center of the center of the concentric interference ring.The laser phase-shift differential interferometer is used to compare the linearity of the center-of-center displacement.The extended uncertainty of the linear fitting of the center-of-center displacement is about 94nm,which ensures the additive component of the uncertainty of the micro-angle measurement less than 0.15".(3)Micro angle measurement experiments and uncertainty assessment.A microangle measuring experimental device is built,and an imaging angle objective lens with a focal length of about 75 mm and an F-P etalon with a spacing of about approximately 2 mm,3 mm,and 5 mm are used to perform a micro-angle measurement experiment in the range of 300".The results show that the three spaced F-P etalons can be used for small angle measurements,where the etalon spacing is approximately 2 mm,the measurement uncertainty of the small angle a to be measured is U(?)=0.13”+3.3×10-4·|?|.(4)Research on self-calibration characteristics of micro angle measurements.According to the optical characteristics of the F-P etalon and the micro-angle measurement principle,the micro-angle measurement results can be traced back to the interval d of the F-P etalon.The experiment uses the three-wavelength excess fractional method to accurately measure the F-P etalon interval d.Obtaining the F-P etalon interval d=(2009.96191±0.00006)?m,and its rough estimate of the relative uncertainty is U?/k0=9.8×10-7,which enables the micro-angle measurement self-calibration function to be realized and has good traceability.