Abstract: A pattern detecting apparatus is disclosed which comprises, in order to detect the center of a positioning pattern on a sample with high accuracy in a wide range, means for illuminating the positioning pattern, means for defining an illumination range in which the positioning pattern is illuminated, means for focusing reflected light from the positioning pattern on a predetermined image plane, means for electrically detecting a bright and dark image on the image plane in accordance with positions on the image plane, means for removing a signal corresponding to the outside of the illumination range from the output signal of the detecting means and for holding, in place of the removed signal, a level of the output signal produced within the illumination range, and means for detecting a position of the center of the positioning pattern from the output signal of the holding means.

Abstract: An improved optical exposure apparatus for use in exposing a workpiece to a desired light pattern with a high alignment accuracy and a high operational speed is disclosed. The apparatus comprises a moving table on which a workpiece to be exposed is disposed, a movable holder on which a mask having an original pattern is disposed, a light source for irradiating said mask, a reduction lens for projecting a reduced pattern of said original pattern onto said workpiece, means for positioning said moving table to a predetermined position, means for detecting the error of said table positioning, means for calculating a value of the error of positioning the workpiece divided by the reduction rate of the reduction lens, and means for automatically shifting said movable holder by the calculated value so as to cancel said error.