| 摘要 |
PURPOSE:To make it possible to reliably detect even a defect having a strong directivity in the direction of the reflected light, such as a knot, by scanning an object to be inspected with scanning light beams from two directions opposite to each othr to effect a defect detection. CONSTITUTION:A light source 15 is turned ON, and a polygon mirror 17 is rotated by a motor. When an object 11 to be inspected is transferred under this state, the light projected from the light source 15 is converted into a parallel light beam by a collimater lens 16 and is then reflected by the polygon mirror 17. While being condensed by an Ftheta mirror (scanning means) 18, the reflected light is made to scan a spectroscopic means 19 along a ridgeline 19c thereof. This light is divided by reflecting mirrors 19a, 19b into the light traveling toward the transfer front side and the light traveling toward the transfer rear side, respectively, which are reflected by totally reflecting mirrors 20a, 20b, respectively, to scan the object 11 along an inspecting line 24 obliquely from two directions opposite to each other. The light 25 irregularly reflected by the object 11 is received by a light-receiving element 21 and binary-coded in a defect detecting circuit, from which a defect signal is drawn out. |
