| 摘要 |
PROBLEM TO BE SOLVED: To provide a projection optical system which is well corrected for aberrations, has a long lens back, and offers a wider view angle and compactness, and to provide a projector having the same.SOLUTION: A projection optical system LN includes a first optical system LN1 and a second optical system LN2 in order from the magnification side, where the second optical system LN2 forms an intermediate image IM1 and the first optical system LN1 magnifies and projects the intermediate image IM1. In the second optical system LN2, a lens surface on the most intermediate image IM1 side is a concave surface and a lens element closest to an intersection of a most off-axis principal ray with an optical axis AX on the magnification side has negative power. The system satisfies a conditional expression: 6.0≤LB/|f|, where LB represents a lens back (i.e., an air-equivalent back focus from a lens surface on the most reduction side to an image plane on the reduction side in the projection optical system) of the projection optical system, and f represents the entire focal length.SELECTED DRAWING: Figure 1 |
