Method and apparatus for detecting positional deviation by using

Details Method and apparatus for detecting positional deviation by using Method and apparatus for detecting positional deviation by using

1994-12-02

1996-03-12

Westin, Edward P.

Radiant energy

Photocells; circuits and apparatus

Photocell controls its own optical systems

356356, G01N 2186

Patent

active

054988780

ABSTRACT:
A method and apparatus for measuring relative positional deviation between first and second diffraction gratings formed on an object is disclosed, wherein, in detection of a signal corresponding to the relative positional deviation between the first and second diffraction gratings, a suitable delay is determined in accordance with a signal corresponding to a relative positional deviation between third and fourth diffraction gratings formed on the object and having a predetected relative positional deviation, and wherein the measurement of the positional deviation between the first and second diffraction grating is done on the basis of a signal corresponding to that deviation and of the delay thus determined.

REFERENCES:
patent: 4710026 (1987-12-01), Magome et al.
patent: 5070250 (1991-12-01), Komatsu et al.
patent: 5268744 (1993-12-01), Mori et al.
patent: 5309197 (1994-05-01), Mori et al.
patent: 5333050 (1995-07-01), Nose et al.
patent: 5432603 (1995-07-01), Sentoku et al.

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