| 摘要 |
PROBLEM TO BE SOLVED: To detect magnetic disc projection defects and make a frictional test promptly, at high sensitivity, and at a high response speed. SOLUTION: In a detector for detecting magnetic disc surface defects by using a change of a reflection angle of laser beams from a test head, an optical system support member is provided in a support arm for positioning a record reproducing magnetic head, and the optical system support member is arranged with a laser light source, a lens for condensing laser beams generated from the laser light source on the inspecting head, and a photodiode which is divided into a plurality of parts for detecting a direction of the laser beams reflected from the inspecting bead. And, this magnetic disc surface detects detector is provided with a filtering function of discriminating between a high frequency oscillation generated due to the magnetic disc projection defects based on a signal from the photodiode which is divided into the plurality of parts and an oscillation generated by a magnetic disc swell or rotation drive system. An oscillation of a gimbal spring is detected instead of the test head.
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