| 摘要 |
PROBLEM TO BE SOLVED: To achieve secure and reliable detection by optically detecting sides where two objects face to each other by using two light receivers, and assigning pixel data being recorded at one light receiver to that being recorded at the other light receiver. SOLUTION: Light receivers 12 and 13 are located at a side where objects 11 face to each other, and the objects 11 are provided with transparent outer layers 14 and 15 at two sides and a middle layer 16 arranged between the layers. In this configuration, for example, defects 17, 18, and 19 exist at the middle layer 16, the outer layer 14, and the outer layer 15 facing the outside, respectively. The objects 11 are exposed to line light, and are rotated at right angle for the layer with a rotary axis 20 as a center, thus completely detecting both flat surfaces and forming an image. The images of the light receivers 12 and 13 are picked up independently, and the defects 18 and 19 appear at the outer layers 14 and 15, respectively. Also, the light receivers 12 and 13 are connected via allocation devices 21, thus uniquely detecting the defect 17 of the middle layer 16.
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