Research On Optical Plane Absolute Detection Based On N - Bit Rotation Measurement

The most commonly used method for measuring the surface profile of plane optical elements is to use interferometric measurements with respect to the reference plane, the measurement accuracy of which is highly restricted by the quality of the reference plane surface of the interferometer. Absolute testing technique has the capability of obtaining the absolute profile of the surface by removing the reference surface error from measurement data. In this thesis, the problems encountered in the application of three-flat testing method on the absolute measurement of the optical plane surfaces were investigated.First of all, the principles, advantages and disadvantages of the algorithms of some three-flat testing methods commonly used were analyzed. In order to obtain the full-aperture and full-frequency range absolute surface profiles of plane optical flats, an absolute testing based on N-position rotations has been proposed, which is based on the traditional four measurements and has the capability of measuring the whole surfaces by adding a set of measurement data of N-position rotations and using odd even function theory. The formulae were derived. Algorithm simulation and error analysis were performed to demonstrate the methods. The measurements were carried out on 4D interferometer and data processing was done. In addition, two groups of contrast experiments were designed innovatively, the results of which demonstrated the feasibility and accuracy of this method from practice.After accomplishing absolute testing, a novel method is proposed for evaluating influence of interferometer system error on component PSD1. By applying actual surface shape data of the reference mirror obtained by absolute detection to the interferometer, absolute surface shape of components could be obtained. On comparison of the results with the relative test results can give the influence of system error on components PSD1. The procedure for processing the mid-frequency wavefront error was discussed in detail and corresponding software was written. The simulation analysis of the absolute testing based on N-position rotations to recovery the mid-frequency information was carried out. The influence of system error on components PSD1 was analyzed from two aspects and the experimental results demonstrated method. The results obtained in this work can provide important guidance for PSD1 detection performance evaluation of interferometer.