| 摘要 |
PROBLEM TO BE SOLVED: To permit inspecting of finished condition in convex working quickly and as total inspection. SOLUTION: Light from a monochromatic light source 26 is applied to a crystal blank 1 subjected to a convex working once polarized by a polarizer 21 and the light polarized at a specified angle to the polarization thereof is let to pass by an analyzer 22 out of the light passing through the crystal blank 1 so that a phase difference is made visible corresponding to the difference of the thickness of the crystal blank 1 by causing a polarization-oriented interference. Then, photographing is performed. A ring-like interference fringe appears on an image of the blank surface of the crystal blank 1 taken to allow discrimination of the finished condition in working. An image processor 14 further performs a processing to intensify the contrast of the interference fringe by binary coding. The resulting binary coding data undergoes a statistical processing to be conducive to the standardization of the convex working evaluation and a GO/NO GO inspection.
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