摘要 |
A device, usable with an object having a layer, for measuring the thickness of the layer, includes a system for irradiating the object with light while changing its wavelength, the irradiating system having a light-emitting portion disposed opposed to the surface of the object, a photodetecting unit for detecting the light from the object irradiated by the irradiating system, the photodetecting unit having a light-receiving portion disposed opposed to the object, a system for detecting the thickness of the layer of the object on the basis of the detection by the photo-detecting unit, and a setting mechanism for positioning the object, relative to the light-emitting portion and the light-receiving portion, at a distance that substantially corresponds to an extremum of the quantity of light which is to be received by the light-receiving portion and which is variable with the positional relation of the object with the light-emitting portion and the light-receiving portion.
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