| 摘要 |
PURPOSE:To detect surface defect at high precision without using expensive optical device, by disposing plural photoelectric elements across the reflected diffracted light of coherent light such as laser beam. CONSTITUTION:Photoelectric transducers 31, 32 of array form are disposed opposedly across the principal relfected light of reflected light 10 of laser beam 8 entering the object being inspected 4. The length of transducers 31, 32 should be more than the width of object being inspected 4, and the transducers are located at equal distance from the point of reflection, being parallel to a scanning locus 9. The laser beam 8 emitted from a laser beam source 1 is reflected by a rotating mirror 2 and a stationary mirror 3 to enter the surface 4a of the object being inspected, and draws a scanning locus 9 due to the rotation of the rotating mirror 2. The laser beam thus entering the surface is scattered and diffracted variously depending on the surface conditions, and its reflected light 10 contains the surface information. Since the transducers 31, 32 are disposed on both sides of the principal reflected light of the principal reflected light 10, only the light corresponding to the diffraction pattern 23 caused by flow or defect may be detected by the transducers 31, 32. The outputs of transducers 31, 32 are processed in a signal processing part 33, and flaw signal is outputted. |
