| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to measure the thickness of film even in the case that a film, the object to be measured is not in a stationary state, or treatment liquid exists on the surface of the film, the object to be measured. SOLUTION: Light from an optical fiber for projecting light 51 is reflected by a half mirror 73 and guided to the surface of a wafer W. Reflecting light from the surface of the wafer W passes through an achromatic lens 72 and the half mirror 73, is reflected by a totally reflective mirror 74, is diffused and unformed by a diffuser 75 and enters an optical fiber for receiving light 54. Therefore, the light with stable intensity can enter the optical fiber for receiving light 54 even in the case the wafer W is rotating, or the treatment liquid exists on the surface of the wafer W.
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