| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a projection optical system that prevents a rise in cost and has superior imaging performance by reducing an influence of birefringence due to a crystal structure. <P>SOLUTION: The present invention provides a projection optical system which projects an image on a first object plane onto a second object plane, comprising a plurality of optical members inserted in turn from a side of the second object plane, the plurality of optical members being made of an isotropic crystal and including a first optical member and second optical member in each of which <1 1 1> crystal axes are oriented in a direction of an optical axis and a third optical member in which <1 0 0> crystal axes are oriented in the direction of the optical axis, wherein maximum angles θ1, θ2, and θ3 between the optical axis and light beams passing through the first optical member, the second optical member, and the third optical member, respectively, satisfy ¾θi-θj¾<5° (i, j =1, 2, 3). <P>COPYRIGHT: (C)2008,JPO&INPIT |
