| 摘要 |
<p>A projection optical system having a good optical performance without being substantially affected by double refraction even if an optical material having an intrinsic double refraction such as fluorite is used. An projection optical system (400) for forming the reduction image of a first plane (R) onto a second plane (W), comprising a first-group light transmitting member formed to provide an approximate agreement of a crystal axis [100] with an optical axis, and a second-group light transmitting member formed to provide an approximate agreement of a crystal axis [100] with an optical axis. The first-group and second-group light transmitting members are so positionally related that one is rotated 45° from the other around the optical axis, and they are both disposed on an optical path between a pupil position (20) on the second plane side and the second plane.</p> |
