| 摘要 |
<p>PURPOSE:To attain to enhance the detecting accuracy of a flaw in longitudinal and lateral directions, by elongating one of the shapes of the beam spots of laser beam for scanning a material to be inspected in the longitudinal direction of the material to be inspected while elongating the other one to the lateral direction of said material to be inspected. CONSTITUTION:Laser beams 6 divided into two routes of A- and B-directions are respectively incident to a first beam molding optical system 9 and a second beam molding optical system 11 to be molded into a beam spot 4-1 elongated in the longitudinal direction and a beam spot 4-2 elongated in the lateral direction. These beam spots are irradiated while alternately changed over at every scanning to scan the surface of a material 1 to be inspected. Because the detection of a surface flow is performed as mentioned above, even if the material 1 to be inspected has a flaw long in the longitudinal direction and a flaw long in the lateral direction, the detection accuracy of the flaw is enhanced be either one of laser beams. The laser beam reflected by the material 1 to be inspected is condensed to a beam receiving device 23 from a condensing lens 22 to be converted to a voltage signal which is, in turn, inputted to a signal processing circuit 24 to output a flaw signal.</p> |
