Key Technologies On Polishing Of Aspherical Optics Surfaces

Aspherical optical components are extensively used in many fields such as aerospace, national defense, photoelectron, medical treatment, and so on. Because of the geometrically complex features of aspherical surfaces, traditional manufacture methods can not meet the needs on the form accuracy and surface quality. Therefore it is of very important significance to propose an improved processing method with a higher form accuracy and surface roughness.Both the status and development trend of the existing research on the machining technology of aspherical optics and its ultra-precision machines are summarized. By analyzing the geometrical characteristics of aspherical optics and machining principle, a new method of solving the best-fit sphere of aspherical surface based on iteration is present. Using the proposed method, both the feeding model and the residual error model of rotationally symmetric aspheric surface are studied based on a polishing mechanism newly developed in our group.According to the machining characteristics of rotationally symmetric aspheric surface, the optimized method of choosing aspherical polishing tools is proposed on the basis of curvature analysis. The polishing tools selected by the proposed optimization method can be well matched to residual error of subsequent processing,By analyzing the mutual position relationship between the workpiece and polishing tools during the polishing process, on the basis of Preston theory, this paper deduces a new polishing removal function model, controlling with the swinging angular variation to determine the quantitative removal, the removing curve is close to Gaussian curve, the form errors converge very quickly.The non-rotational symmetrical aspheric surface is also discussed in this paper. Taking off-axis aspherical surface as an example, a new method of solving the best-fit asphere is deduced based on iterative principle. Through controlling the step size and space of polishing tool trajectory, higher form accuracy can be achieved.The research conducted in this paper provides a theoretical and technological basis to the high precision polishing of both rotationally symmetric and non-rotationally symmetric surfaces.