| 摘要 |
PROBLEM TO BE SOLVED: To confirm a very minute defect by radiating a laser beam in a spot state to the surface of a drum-like photoreceptor base material along the center shaft of the drum from an oblique direction and detecting scattered light from the surface. SOLUTION: While the drum base material 1 is rotated at fixed circumferential speed by a rotating motor 2, a laser light source 3 and a photoelectric conversion element 4 are moved in the shaft direction of the base material 1 at the fixed speed by a moving stage 5. A distance by which the stage 5 is moved while the base material 1 is rotated once is made smaller than the spot diameter of the laser beam, desirably, equal to or under the half of the spot diameter, so as to uniformly scan all the positions of the surface of the base material. While scanning, an electrical signal from the element 4 is recorded by a data processing part 5. In the case the defect exists on the base material 1, the electrical signal from the element 4 is increased by the scattered light from the defect, so that the defect is detected according to the change of the signal. |
