| 摘要 |
PURPOSE:To measure the surface flatness of a specimen to be measured in a non-contact state, by detecting the pitch of a lattice image on the basis of the conversion signal from a photoelectric converting unit and calculating the standard deviation f the pitch according to a specific formula. CONSTITUTION:The light from a light source 1 becomes uniform intensity distribution by a diffusion plate 2 to illuminate a lattice 3. A projection lens 4 forms the light transmitted through the lattice 3 into an image on a photoelectric converting unit (CCD)5 through the surface 12 of a specimen to form the real image of the lattice 3. Next, a specimen arranging position judge circuit judges whether the surface 12 of the specimen to be measured is arranged at a predetermined position with respect to the lattice 3, a lens 4 and CCD5 on the basis of the conversion signal from CCD5 and outputs a result in a state separated into far, near, inclination and normality. Next, after normal arrangement is judged, a pitch signal processing circuit detects the pitch Pi of the lattice image on the basis of the conversion signal from CCD5 and calculates the standard deviation sigma of the pitch Pi from formula to output the same as the flatness of the surface 12 of the specimen to be measured.
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