The Basic Research On Optical Manufacture Of Glass Ceramic And Silicon Carbide Mirror

With the rapid development of space astronomical optics,satellite remote sensing technology and large foundation optical system,more and more strict requirements are raised on image resolution,thermal stability and system quality.Glass ceramic and silicon carbide are the main materials of astronomical telescopes because of their excellent optical and physical characters.Lapping and polishing are two essential steps for them to be qualified optical elements.Lapping is used to remove the scratches,rough particles left by grinding and large surface errors can be corrected in this step.Polishing is used to remove surface damage left by former lapping and at the same time surface figure accuracy and roughness are improved in the process.This thesis is based on experiments of lapping and polishing on glass ceramic and silicon carbide.The major research efforts include the following points.1.The depths of lapping damage layer on glass ceramic caused by different sizes of abrasives and different lapping discs are measured after polishing step by step.Two conclusions are as follows: the depth of lapping damage layer is about 1.4 times of abrasive size and the depth is larger with lapping of harder lapping discs.2.The depths of lapping damage layer of RB silicon carbide caused by different sizes of boron carbide abrasives are measured after polishing step by step.Then an empirical formula is successfully set up between the depth of lapping damage layer and abrasive models.From this formula the lapping surface damage depth caused by boron carbide with model W20 is estimated.3.The polishing abrasives and steps are determined after a series of experiments onRB silicon carbide.4.An optimized scheme on optical manufacture of RB silicon carbide is set up and through this a qualified mirror with good surface roughness of silicon carbide is processing out.So through the research conclusions and experimental data of this thesis,the choice of abrasive size,abrasive tool and removal depth of polishing can all be guided in optical manufacture of glass ceramic and silicon carbide mirror.