| 摘要 |
PROBLEM TO BE SOLVED: To provide a flat surface usable in an ultraviolet ray region by one setup by performing the polishing while supplying a first abrasive material including abrasive grain between an optical element and an abrasive tool, stopping the supply of the first abrasive material, and continuously performing the polishing while supplying a second abrasive material including colloidal silica. SOLUTION: An abrasive device comprising a rotary shaft 1 on its lower part and an oscillating shaft 2 on its upper part, is used, an abrasive tool 3 is mounted on the rotary shaft 1, and an optical element 4 is held by the oscillating shaft 2. The polishing is performed while supplying an abrasive material 6 including the abrasive grain 5 between an abrasive tool 3 and an optical element 4 from an abrasive grain supply mechanism 6a. Then the supplying of the abrasive material 6 including the abrasive grain 5 is stopped, and then a lens is finished continuously thereafter while supplying a colloidal silica abrasive material 7 from a colloidal silica supply mechanism 7a. A coarse surface is removed as a pre-machining by the abrasive grain of high abrasive quantity, then the fine scratches or the like newly mede by the abrasive are removed by both of the abrasive grain 5 and the colloidal silica 7, and the surface is smoothened by the colloidal silica 7 in one setup.
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