JPH05346320

PURPOSE:To provide a device which easily and accurately examine the rough remainder on the cross-hatch of inner peripheral surface of a circular bore of a cylindrical black caused by diamond and boring, in the peripheral direction, grain. CONSTITUTION:A circular bare 2 is provided with an optical unit 7 inserted in with both rotation and vertical movement permitted, an imaging device 8 and a picture processor 9. The optical unit 7 contains a laser beam irradiation system 5 which irradiates a bore inner peripheral surface 3 with laser slit beam 4 extending in the peripheral direction at a specified inclination angle theta and a mirror 6 which reflects and turns scattering light 4' of the laser slit beam 4, having been reflected on the inner peripheral surface 3 in the direction of bore radius, into the bore axis direction. The scattering light 4' coming from the inner peripheral surface 3 within a laser irradiation range m whose peripheral width is constant is reflected an the mirror 6, to be taken in by an imager 8. The picture data taken in is binarized by the picture processor 9, the number of pixels of the obtained dot-like picture is counted, and the roughness and surface nature of the inner peripheral surface 3 is judged based upon the number of pixels.