PURPOSE: To detect a surface defect highly efficiently and highly accurately by rotating a body to be tested having a circular section around an axis, scanning the surface of the body to be tested by laser light in the axial direction, detecting diffused and reflected light and processing its detecting signal.
CONSTITUTION: The body 1 to be tested which is supported by a chuck 10 is rotated by a DC motor 11 in the arrow A direction. A rotational position signal SA of the body 1 to be tested is outputted from a rotary encoder 12 to an operation control part 8. A motor 17 is simultaneously started, a rotary polyhedral mirror 16 is rotated in the arrow C direction, a rotational position signal SB from the rotary encoder 18 is sent to the control part 8, and laser light is oscillated from a light source part 4. The laser light is deflected by a deflection part 5 and the deflected light scans the surface of the body 1 to be tested in the arrow B direction. The diffused and reflected light based upon a defect on the surface is transmitted to a photoelectronic amplifier tube 20 through optical fibers 19 on both the ends of a light collecting part 3. The output of the amplifier tube 20 is processed by a control part 8 through an AD convertion part 7 and the surface defect is detected highly accurately.
YAMAJI HIROSHI
OGAWA SHIGERU
KOMARU MINORU
