Positional deviation detecting method

Optics: measuring and testing – By alignment in lateral direction – With registration indicia

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G01B 1100

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active

054813638

ABSTRACT:
A method of detecting a relative positional deviation of a first object having a first grating mark with an optical power and a second object having a second grating mark with an optical power, is disclosed, wherein a projected radiation beam is diffracted by the first and second grating marks in sequence and, on the basis of a position of convergence on a light receiving surface of plural diffraction beams produced by the diffraction through the first and second grating marks and including a signal beam having been diffracted at a predetermined order by each of the first and second grating marks, the relative positional deviation is determined, a detection zone is defined on the light receiving surface, the signal beam is converged upon the detection zone, and a predetermined diffraction beam of the plural diffraction beams which, for a relative positional deviation of the first and second objects, shows displacement different from that of the signal beam is substantially prevented from being converged upon the detection zone.

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patent: 4514858 (1985-04-01), Novak
patent: 4870289 (1989-09-01), Sato et al.
patent: 5114235 (1992-05-01), Suda et al.
patent: 5148038 (1992-09-01), Nose et al.
patent: 5225892 (1993-07-01), Matsugu et al.

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