Patent ID: 8174707
Filing Date: 2012-05-08
Classification: G02B,G03F

Abstract:
1. An optical element positioning apparatus comprising: a moving unit including a mirror; a driving unit configured to drive the moving unit; a measuring unit configured to measure a position of the mirror; and a control unit configured to control the driving unit based on a measurement result by the measuring unit, wherein an incident position at which a principal ray of a central field enters the minor is displaced from an optical axis of an optical system including the minor, and wherein the measuring unit measures the incident position in an optical axis direction based on at least three measurement points in a state in which the incident position is displaced from the optical axis, and wherein the measuring unit is provided so that, when at least three measurement points are projected onto a plane perpendicular to the optical axis, a position where the incident position is projected onto the plane and a position of center of gravity of a polygon whose vertices are formed by the projected measurement points coincide with each other.