| 摘要 |
PURPOSE:To constantly maintain and detect accurate optical information as desired with stable detection accuracy even if there is a tilt in return light by a method wherein a toric lens is provided at a pupil or its vicinity. CONSTITUTION:A pupil conjugate plane ep'0 conjugating with a pupil ep of projection optical system (injecting pupil or emitting pupil) is provided by alignment optical system (detection optical system). At the position of the pupil conjugate plate ep'0 or its vicinity, a toric lens 19 which has refractive power with respect to at least one-dimensional direction which intersects the direction of position change of optical direction in the pupil conjugate caused by change in tilting of the optical information (telecentric error) from a pattern (alignment mark). A photoelectric detector 20 whose light receiving face is located at the focus of the toric lens 19 or its vicinity is additionally provided. This enables correction so as to generate no difference in position with respect to the light receiving system even if there is difference in position of optical information caused when the detecting position for alignment is changed. |
