| 摘要 |
Disclosed is a method and apparatus for detecting a relative positional deviation between first and second objects. In one preferred form of the invention, the detecting method includes the steps of (i) providing the first and second objects with diffraction gratings, respectively, each having a grating pitch larger than a wavelength of a light source used, (ii) placing the first and second objects so that a dielectric material layer having a thickness smaller than the wavelength of the light source used is interposed between the first and second objects, and so that the diffraction gratings of the first and second objects are opposed to each other, (iii) projecting light from the light source onto the diffraction gratings of the first and second objects, and (iv) detecting the relative positional deviation between the first and second objects on the basis of diffraction light projected from the diffraction gratings to a space.
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