| 摘要 |
PROBLEM TO BE SOLVED: To prevent rear reflection of a transparent board, and to inspect its surface unevenness precisely, using a usual light source and a screen. SOLUTION: Influence by rear reflection of a transparent board 3 is prevented, by making the angle of incidence of a light source 1 to the transparent board 3 86-89 degrees by normal reference, or making the light source 1 P-polarized light or S-polarized light, and making its angle of incidence 60-89 degrees by normal reference by the use of a polarizing element (polarizing board 2) arranged between the light source 1 and the transparent board 3. And a reflected image projected to a screen 4 by the reflection of the front surface is visually observed directly, or a monitor image obtained by picking up the reflected image by a camera is visually observed, or the reflected image picked up by the camera is processed arithmetically as a shaded signal by a picture processor. Consequently, it becomes possible to inspect the surface roughness of the transparent board 3. |
