Study On The Errors Analysis Of Large-area Grating Fabricated By Exposure Mosaic Basted On Measuring The Initial Phase Of Diffraction Wave

Large-area pulse compression grating of high-quality diffraction wavefronts is an important optical element in pulse compression system. But its fabrication is difficult and costly. These factors restrict the development of large-area pulse compression gratings. For the current state of domestic technology, holographic exposure mosaic technology is the best solution of large-area grating’s fabrication. This paper analyzes the problems of mosaic and low success rate which exist in latent image grating splicing. To solve these two problems, the mosaic method of developing region by region and the mosaic method of etching region by region are proposed by our lab. Before the end of the fabrication, the mosaic errors of the large-area grating should be tested. The dislocation of the diffraction wavefront can be generated because of the difference of grating topography, which can be superimposed on the phase change caused by the lateral displacement error and interfere the judge of the lateral displacement error. Therefore, the computational problems of initial phase of diffraction light generated by different grating topography and the application of initial phase of diffraction light in the testing of grating mosaic errors are discussed in this paper. So the main contents are follows:Firstly, the background of large-area grating and research status are introduced, exposure mosaic principle is described. The mosaic method of developing region by region and the mosaic method of etching region by region are presented. The necessity of calculating the initial phase of different grating topography is proposed.Second, phase calculation numerical code based on the rigorous coupled-wave analysis(RCWA) is written by MATLAB software which is verified theoretically and experimentally.Thirdly, the method of obtain grating groove by measuring the phase indirectly is proposed according to the law of the phase distribution. The phase distribution of reflective and transmissive diffraction wave generated by grating on K9 glass substrate calculated. The applicable conditions and the error of the method are analyzed. The feasibility of the method is verified experimentally.Last, the method of calculating phase difference of the 1st order diffraction wave generated by the multilayer dielectric grating of which the grating duty cycle is can’t be known accurately are given. The method is calculating the phase difference of the 1st order diffraction wave by that of 0 order diffraction wave and is verified experimentally.