Projection optical system and image display device with refractive optical system to form an image on a receiving surface

Abstract

The present invention aims to provide a projection optical system that projects an image displayed on an image display surface of an image display element in an enlarged manner on a projection receiving surface as a projection image, the projection optical system comprising: a refractive optical system and a refractive/reflective optical element arranged in sequence from near the image display surface toward the projection receiving surface, wherein the refractive optical system includes a plurality of lenses, wherein the refractive/reflective optical element includes an optical element unit that includes a reflection surface member including a reflection surface, and a refractive medium portion that is in tight contact with the reflection surface, the refractive medium portion includes an incidence surface and an emergence surface, and the reflection surface is a curved surface having refractive power, and wherein an image-forming light beam emerging from the refractive optical system is caused to enter the refractive/reflective optical element from the incidence surface of the refractive medium portion, reflected by the reflection surface, caused to emerge from the emergence surface of the refractive medium portion, and formed into an image on the projection receiving surface as the enlarged image.