| 摘要 |
<P>PROBLEM TO BE SOLVED: To achieve reduction of cost and miniaturization, by having a wide angle to be excellent in optical performance and having a small number of lenses, in a projection optical system of a type in which an intermediate image is formed between a mirror and a refraction lens part. <P>SOLUTION: The projection optical system, enlarging and projecting an original image on a conjugate surface on a reduction side onto a conjugate surface on an enlargement side, is configured by disposing, in order from the reduction side: a first optical system 1 having positive refractive power, which forms the intermediate image conjugated to the original image (image display surface 3); and a second optical system 2 being a converging reflection system which forms a final image conjugated to the intermediate image onto the conjugate surface (screen 5) on the enlargement side. The first optical system 1 comprises five lenses L<SB>1</SB>to L<SB>5</SB>, and the second optical system 2 comprises a reflection mirror 4 formed in a concave shape. Also, it is desirable that at least one surface of the lens L<SB>1</SB>nearest to the enlargement side in the first optical system 1 and a mirror surface of the reflection mirror 4 of the second optical system 2 are set as an aspherical surface or a free curved surface. <P>COPYRIGHT: (C)2011,JPO&INPIT |
