Canon Kabushiki Kaisha

Kazuyuki Oda

Naoki Ayata

Hideo Hata

Yoshikiyo Yui

Koji Uda

Yoshiharu Kataoka

A distance calculating device includes a plurality of distance measuring systems for measuring the distance between a surface of an object and a predetermined plane, a storing element having portions corresponding respectively to the plurality of measuring systems, for storing therein information as to effectiveness/ineffectiveness of each of values detected, as the result of measurement by the plurality of measuring systems, respectively, in accordance with points of measurement on the surface of the object, and an element for calculating the distance between the surface of the object and the predetermined plane by reference to the storing element and by use of only an effective value, of the detected values, in accordance with the points of measurement on the surface of the object.

Method and apparatus for automatic focusing

An alignment and exposure apparatus in which sequential operations of pattern projection for projecting a pattern of a first object, at a reduced ratio, onto a second object through an optical system, stepwise movement for moving the second object stepwise relative to the first object, detection for detecting any positional deviation between the first and second objects at a position at which the stepwise movement of the second object is terminated, and correction for correcting the positional relation between the first and second objects on the basis of the detected positional deviation, are repeated relative to the second object to thereby print the patterns onto the second object in a reduced scale. Upon correction of the positional relation between the first and second objects, at least one of the first and second objects is displaced in accordance with the magnitude of the detected positional deviation and/or, upon stepwise movement of the second object, the amount of stepwise movement to be made is corrected in accordance with the detected positional deviation with respect to the position at which the preceding stepwise movement of the second object is terminated. By this, the time required for repetitions of exposures is reduced.

Growing community of inventors

Kawasaki, Japan

Kazuyuki Oda