Research On Mechanical Tiling Methods Of Three Atypical Gratings

Diffraction gratings have become one of the most important optical elements in modern experimental science due to their excellent capabilities of dispersion.Largescale gratings play an extremely important role in some fields.However,there are still technical and cost issues while fabricating meter scale gratings.Therefore,researchers have carried out a lot of research on gratings tiling technology in the past three decades,a technique that places two or more relatively small-scale gratings adjacent to each other,modifying spatial error between each other to a reasonable range and making the overall performance of the grating assembly equivalent to a large grating of the same area.Researchers have established basic theory of grating tiling errors.A variety of mosaic error correction technologies have been developed for different application scenarios.However,there are still some blank space in mosaic theory of some special types of gratings.Therefore,research in this thesis were carried out on echelle gratings,varied linespace gratings and dual-blaze gratings.The specific research contents are as follows:Firstly,analysis on grating mosaic theory.The mathematical model of the relationship between the mosaic error and the diffracted wavefront was derived.The principles of two error detection and correction techniques,the far-field diffraction spot diagram method and the near-field interference fringe method were analyzed.Secondly,research on echelle gratings tilling technique.A rule was proposed concerning wavefront observing on high diffraction orders,which is observations must be carried out on two different orders.A tilling method based on lateral shearing interferometers was proposed for echelle gratings.A mosaic device was designed and built.Two echelle gratings of 50mm×50mm、79gr/mm were used for principle verification experiments.A shifting accuracy of 10 nm and rotation accuracy of 1arcsec was achieved.Thirdly,research on planar varied line-space grating mosaic technique.The issue of line bending due to the manufacture technique using two spherical waves was analyzed.A new manufacture procedure with parallel tilling of two half-width gratings was proposed.A UV band grating design was used to analyze spectral imaging qualities.Optical path function method and ray tracing method were applied.Mosaic error detecting methods were also discussed theoretically.Fourthly,research on dual-blaze gratings.A method for manufacturing muti-blaze gratings using mechanical mosaicking was proposed to achieve a uniform diffraction efficiency on a broad band.The surface of a normal blaze grating was divided into different sectors with the same groove density and different blaze angles.Each sector was manufactured independently and combined using mechanical tilling.A UV-visible band dual-blaze example grating was fabricated and tested.Wavefronts of the mosaic grating was better than 0.4（ =632.8nm）,diffraction efficiency on 90% of the working band was better than 20%.