Studies On Ultra-precision Optical Manufacturing Technology Of Q-type Polynomial Free-form Surface

Freeform optical elements have been widely used in optical engineering fields such as aerospace,defense,and military,playing an important role.As the free-form surface is a complex and irregular special surface shape,it brings certain difficulties to the optimal design and processing of the optical system.Combining the certain advantages of free-from surfaces characterized by Q-type function polynomials in design and processing,this paper mainly studies the ultra-precision optical manufacturing technology of Q-type polynomial freeform surfaces.The main research work is as follows:First,the working principle of single-point diamond turning technology and the mathematical model construction process and characteristics of three expression forms of Qtype function polynomials are studied.The advantages of the Q-type surface shape in design and processing are explained by using a lens of a mobile phone designed with a Q-type function polynomial.Secondly,according to the theoretical model of Q-type function polynomial characterization of free-form surface,its basic surface shape is simulated and analyzed.Diamond materials,tool types and tool geometries are introduced.Starting from the noninterference phenomenon between the workpiece and the tool,the optimization of tool geometric parameters is discussed,and Q-type polynomial freeform tool parameter selection is performed for example analysis.Then,the principle of tool path generation is analyzed,and the turning process parameters that affect the surface quality of workpieces are studied.Based on the analysis of turning trajectory linearization errors and the characteristics of linearization errors of the common constant-arc method and constant-angle method,a combined tool path optimization method of constant–arc and constant-angle is proposed.The selection of the connection point is optimized by polynomial fitting.Finally,ultra-precision machining and inspection of Q-type freeform surfaces were performed.The process required for single-point diamond turning of Q-type freeform surface was designed and researched,and the surface shape of the workpiece was measured using a white light interferometer.The surface roughness of the workpiece was 6.58 nm.Compared with the original method,the machining accuracy is higher,which verifies the rationality of the turning parameter and the effectiveness of the turning trajectory optimization method.