Patent ID: 9639000
Date: 2017-05-02
CPC Classifications: G01B,G03B,G03F

Claim:
1. A position detector which detects a position of a mark on an object to be detected, the detector comprising: an image pickup unit configured to pick up an image of the object to be detected; an optical system configured to form an image of the object to be detected on an image pickup surface of said image pickup unit; and a noise processing unit configured to obtain noise information of an electrical signal in an image of a region other than the mark using said optical system and said image pickup unit and configured to decrease, using the obtained noise information, noise of the image of the mark obtained using said optical system and said image pickup unit, wherein said noise processing unit updates the noise information used for decreasing the noise of the image of the mark after adjustment of said optical system by moving an optical member included in said optical system, and wherein the noise processing unit decreases the noise of the image of the mark using the updated noise information.