Research On Surface Registration Method Of Optical Element Based On ICP Algorithm Improvement

In recent years,technology in the field of optics has developed rapidly,enabling high-precision optical systems to be used in a wide range of applications,not only in military and scientific research.Optical components are the core components of high-precision optical systems,and their surface quality affects the performance of the entire high-precision optical system.The process of surface quality inspection of optical components is a key part of the process,and surface alignment based techniques are mainstream in the inspection technology.Due to the inevitable systematic errors in the measurement process,this poses certain challenges for surface inspection and surface alignment.The main work is to improve the nearest point iterative search method of the ICP algorithm using the KDTree method and to optimise the selection of the initial values of the flush transformation matrix of the improved ICP algorithm using the whale optimisation algorithm,in order to address the problems in the alignment of optical elements on surfaces.First,this paper provides a brief introduction to the surface alignment problem,leading to the definition of the surface alignment problem.This is followed by an analysis of the advantages and disadvantages of the ICP algorithm,and a mathematical model of the problem is developed and the objective function is defined.The KDTree method is used as the nearest point iterative search method of choice to improve on the slow convergence rate of the alignment process in the presence of large amounts of data.A comparison is made before and after the incorporation of the KDTree method for free-form surfaces and aspheres respectively,and it is concluded that the method can improve the running speed algorithm running time.Secondly,for the problem of selecting the initial points in the ICP algorithm,the Whale Optimisation Algorithm is proposed to optimise the improved ICP algorithm,transforming the problem into an unconstrained optimisation problem solved using the Whale Optimisation Algorithm.The effectiveness and stability of the improved ICP algorithm are verified by using the whale optimization algorithm with NSGA-II for free-surface and aspheric surfaces,respectively.The alignment results show that the Whale Optimisation algorithm has higher iteration accuracy and shorter iteration time under the same conditions,and no local optimisation occurs,with good overall consistency.Finally,to verify the effectiveness and stability of the improved ICP algorithm based on the whale optimisation algorithm proposed in this paper.The proposed algorithm is experimentally verified by measuring the free-form surface and aspheric surface after single-point diamond turning process.The search time of the ICP algorithm before and after the incorporation of the KDTree method and the iteration accuracy before and after the incorporation of the Whale Optimisation Algorithm or NSGA-II were compared,respectively,for iteration time.The alignment results show the effectiveness and stability of the improved ICP algorithm based on the whale optimisation algorithm proposed in this paper.