To highly accurately inspect the state of beveling work and convex work and to inspect the state of flat plate work by the same light source.
A composite light source comprised of a light source 10 for dark-field observation and a light source 20 for polarized-light observation is used. Light from the light source 20 for polarized-light observation is diffused by a diffusing plate 2, polarized by a polarizer 3, and shone to a crystal blank B on which beveling work or convex work is performed. Simultaneously with this, the crystal blank B is also irradiated with light from the light source 10 for dark-field observation. Light transmitted through the crystal blank B or scattered and diffracted at the crystal blank B is extracted by a polarizer 4 as light in a polarized state at a predetermined angle. By picking up the image of the light in the polarized state by an image pickup means 30, it is possible to observe contour lines due to the light source 10 for dark-field observation in addition to interference fringes due to the light source 20 for polarized- light observation. The image signals are transmitted to an image processing device 40, and the shapes of beveling work and convex work are inspected from the location of the interference fringes to the contour lines.
TAKAHASHI NOBORU
KAWABE YOSHIHISA
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