Research On The Sub-aperture Stitching Testing Technology For Cylindrical Lens

Cylindrical lens is widely used in high power laser systems,scanning imaging systems and holographic projection systems because of its unique line focusing characteristics.With the continuous development of science and technology,people have put forward higher requirements on the accuracy and caliber of cylindrical lens.When testing cylindrical lens accurately,a standard cylindrical lens with the same or larger caliber is usually needed.However,for large-caliber or large angular aperture cylindrical lens,it is precisely because of its non-rotational symmetry that makes the manufacture of high-precision standard cylindrical lens difficult and costly.The sub-aperture stitching technology adopts the principle of "little stitching big".Dividing the measured surface into several overlapping sub-apertures to test one by one,and then using algorithms to stitch all sub-apertures to get the full-aperture map.The existing sub-aperture stitching algorithms cannot completely compensate the cylindrical misalignment errors,and are sensitive to the position errors.In view of this,this paper has done the following researches:1.For the non-rotational properties of cylinder,the Chebyshev polynomials are proposed to construct the compensation model of misalignment errors in cylindrical stitching testing.On this basis,the principles,advantages and disadvantages of various stitching algorithms are analyzed,and finally the error equalization algorithm is selected to compensate the misalignment errors.The applicable range of the circular and rectangular sub-aperture is analyzed,and the rectangular sub-aperture is selected to complete the measurement of single aperture.2.The traditional compensation algorithms of position errors are studied,and a sub-aperture stitching algorithm based on particle swarm optimization is proposed to overcome their shortcomings.According to the optimization objective of this paper,the traditional particle swarm optimization algorithm is improved.Based on this,the sub-aperture stitching program is compiled,and the stitching results are evaluated by three evaluation parameters.The results show that the proposed algorithm has higher stitching accuracy when the misalignment error is large.3.we put forward the insights into the path planning of cylindrical sub-aperture stitching testing and conducts a series of studies on the optical path which used in the whole experiment.For a cylindrical len with specific parameters,the design of testing and calibrating optical path based on Computer-generated holography is completed.Finally,the drawing program of Computer-generated hologram(CGH)is compiled.4.The experimental optical path is built to complete the surface measurement of the full-aperture and each sub-aperture.The test data is brought into the stitching program for full-aperture stitching.The feasibility and effectiveness of the proposed algorithm are verified by comparing the stitching result with the measurement of full-aperture surface information.Finally,the influence of various factors in the measurement and stitching process and the improvement method are analyzed.