| With the development of modern technology and especially the improvement of equipment performances, more and more higher precision is demanded on key optical components in various optical systems. High precision spherical optical components are playing important roles in precise measuring instruments, inertial confinement fusion systems and high precision gyroscopes, where the spherical form accuracy is required very high and becomes the critical factor responsible for system performances. How to measure and estimate the three-dimension (3D) surface error and develop deterministic and high-precision corrective figuring technologies come to be the key problems to be solved, which may provide theoretical support and technological foundation for improving the manufacture of the spherical optics. It is both scientifically and practically significant.Ion beam figuring (IBF) provides an ultra-precision machining method for spherical optics based on the CCOS (Computer Controlling Optics Shaping) principle with the ion sputtering effect to remove material at atomic scale. It is deterministic, highly stable and non-contact with advantages over conventional figuring technology. The normal material removal characteristic and the removal function being insensitive to surface curvature make IBF advantageous for machining of spherical components. This thesis mainly discusses subaperture stitching interferometry to obtain the global surface error of spherical optics, and then addresses the key problems including the material removal characteristics and corrective figuring technologies according to Sigmund sputtering theory and CCOS principle, which forms a novel method and technology for spherical optics. The major research efforts include the following points.1. Based on the Sigmund sputtering theory, the material removal characteristics at different incidence angles are studied to obtain the changing ruler of removal rate in dependence of different incidence angles and build the corresponding theoretical and experimental models of the removal function in IBF process. Meanwhile, the normal material removal characteristic and the removal function being insensitive to surface curvature are analyzed. When the process parameters of ion source are invariable, the deduced result shows that the removal rate is a function of the single variable of incidence angle. Based on the evolvement mechanism of surface roughness in IBF, the method of oblique-incidence figuring and sacrificial coating layer technology are proposed to obtain ultra-smooth optical surfaces. These figuring methods extend the machining capability of IBF.2. Based on the CCOS principle and the material removal characteristics in IBF, the traditional convolution equation is revised to model the dwell time for high slope surface. Then the weighted Lucy-Richardson calculation method is introduced, and the modified pulse iterative method and the algorithm based on compensation are proposed to solve the model. Since the projection distortion of hemisphere is big and the full-sphere is undevelopable, the non-linear developing method and the zonal projection, according to cartographical theory, are applied for the stitching processing of the high slope spherical surfaces.3. To solve the problems of measurement and evaluation of the spherical components, subaperture stitching interferometry is studied. The adjustment equipments are designed for various spherical components, and testing of hemispheres and full spheres are implemented. Then 3D surface error of spherical components is reconstructed via cartographical projection. These technologies provide IBF with measurement and evaluation method.4. Based on above discussions, figuring experiments on spherical components were carried out to validate the feasibility of the proposed algorithm for dwell time and the effectiveness of the process flow. Finally nanometer-precision machining of spherical components was realized. |
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