| 摘要 |
PROBLEM TO BE SOLVED: To accurately measure thickness by eliminating the deviation of upper/ lower sensors and dealing with the fluctuation of pass line and the fluctuation of pass angle of an object to be measured. SOLUTION: The optical thickness gauge 7 is composed of a light source 1 for irradiating the object to be measured 6, a photo detector 3 for detecting the distribution of detected light in the absence of the object to be measured 6 and the distribution of detected light corresponding to the refractive index of the object to be measured 6 in the presence of the object to be measured 6, and a calculating analyzer 5 for obtaining the thickness of the object to be measured 6 from the aspect ratio of the distribution of detected light, which corresponds to the refractive index of the object to be measured 6 in the presence of the object to be measured 6, to the distribution of detected light in the absence of the object to be measured 6. The light source 1 and the photo detector 3 have prescribed slopes relative to the object to be measured, and the thickness of the object to be measured 6 is measured by utilizing a change of distribution of light passing through the object to be measured 6 caused by the refractive index and by capturing the change of distribution.
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