Research Of Sub-aperture Stitching Algorithm In Cylinder Surface Testing

As a non-rotationally symmetrical optical surface,cylindrical mirror plays an irreplaceable role in the optical system.With the continuous progress of modern optical technology,higher requirements are also put forward due to the higher testing accuracy of cylindrical lens.In the process of optical element production,the surface shape depends on the testing accuracy.In the testing of large-caliber or large angular aperture cylindrical lens,compensation lens with the same or larger diameter are usually required,which increase the testing cost and preparation difficulty.Based on the Computer-generated holograms testing method,this paper proposes to use the sub-aperture stitching method for testing cylindrical lens.The testing accuracy is improved and the aperture size of the compensation lens is reduced.At the same time,the testing cost is also reduced.In the sub-aperture stitching method,many error factors need to be considered,including the offset error that affects the zeroing of the interference fringes,the position error caused by insufficient mechanical positioning accuracy,and the Gaussian noise caused by unavoidable factors such as the environment.These factors will affect the stitching result.Existing sub-aperture stitching methods for cylindrical lens do not explicitly compensate for those errors.In view of this,this paper has done the following researches:1.Starting from the mathematical model of the cylinder,the mathematical expression of the main aberration of the cylindrical mirror is calculated when the Legendre polynomial is used to fit the surface shape,and through the simulation analysis,the offset error main form of expression of cylindrical mirrors is analyzed.By simulating the testing optical path and adding the offset error,the offset error caused by the tilt and decenter in the three directions can be analyzed.The rotation of the Z axis is the most sensitive in testing,and there is a linear transformation with the fifth term polynomial,which verifies the reliability of the mathematical model.2.The traditional sub-aperture splicing algorithm is extended.According to the special features of the cylinder and the sub-aperture testing path,a fractional step stitching algorithm suitable for the detection of the cylinder is proposed,and through computer simulation of the offset error in actual testing,and the proposed algorithm is tested by the sub-aperture stitching test software.The results show that the fractional step stitching algorithm has a good compensation for the offset error of the cylinder.3.The positioning error and its traditional compensation method in sub-aperture stitching are introduced,and the mathematical model of the positioning error is constructed.Based on the randomness of the error,a random optimization algorithm is proposed to compensate the positioning error.The random optimization algorithm program is written,and the feasibility of the algorithm is verified by testing software.4.The experimental optical path is built,and the comparison experiment is designed for the measurement of the full aperture and sub-apertures.The sub-aperture stitching software was programmed.The cutting error and pixel error occurred in the process of processing real data are analyzed and calculated.This experiment verifies the feasibility and effectiveness of the sub-aperture stitching algorithm and the random optimization algorithm proposed in this paper.