| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a detector for detecting the run-off of a wafer surely regardless of the type of the wafer. <P>SOLUTION: Optical fibers 21 and 22 are disposed at the upper end of the opening of a cassette 10 containing wafers 1 while being directed directly downward, a mirror 51 is disposed at the lower end of the opening directly under the optical fiber 21, and a mirror 52 is disposed directly under the optical fiber 22. The mirrors 51 and 52 are arranged in a V-shape such that reflection planes thereof face each other while inclining by 45°. Light is projected from the projection optical fiber 21 toward the first mirror 51 and reflected toward the second mirror thence reflected on the second mirror before entering the light receiving optical fiber 22. In other words, an optical path is formed of the projection optical fiber 21, the light receiving optical fiber 22, and the mirrors 51 and 52. Consequently, the optical path is formed of the optical fiber 21, the light receiving optical fiber 22, the first mirror 51 and the second mirror 52. <P>COPYRIGHT: (C)2003,JPO</p> |
