Projection system and projector with intermediate image formed between first and second optical systems

Abstract

A projection system includes a first optical system and a second optical system sequentially arranged from a reduction side toward an enlargement side. The second optical system includes an optical element having a concave reflection surface and a first lens having negative power, the optical element and the first lens sequentially arranged from the reduction side toward the enlargement side. The projection system satisfies Conditional Expressions (1) and (2) below, where LL represents the largest radius of the first lens, MR represents the largest radius of the reflection surface, imy represents a first distance from an optical axis to the largest image height at an image formation device, M represents a projection magnification that is the quotient of division of a second distance from the optical axis to the largest image height of an enlarged image by the first distance imy, TR represents a throw ratio that is the quotient of division of a projection distance by the second distance, and NA represents the numerical aperture of the image formation device.