| 摘要 |
PURPOSE:To make it possible to adjust rotary asymmetrical optical properties against an optical axis of a projection optical system which remains in the projection optical system without controlling strictly discrete component accuracy or assembling accuracy by laying out an optical means having a rotary asymmetrical power to the optical axis of the projection optical system. CONSTITUTION:A toric type optical member having different powers in the orthogonal directions as an optical means having rotary asymmetric power to the optical axis of the projection lens 36 is laid out between a reticle 35 and a projection lens 36. A cylindrical lens 1 having negative power and a cylindrical lens having positive power are installed rotatively to the toric type optical member, centering on the optical axis of the projection lens 36 respectively. And the rotary asymmetric optical properties remaining on the projection lens 36 are corrected with the amount of relative rotation. This construction makes it possible to prevent a drop in the performance of the projection optical system due to manufacturing errors and provide a projection optical system as designed. |
