Optical system and projection-type image display device

摘要

An optical system includes a first prism having a first surface and a second surface forming an acute angle therebetween, and a second prism having a third surface. The first prism and the second prism form an air gap between the second surface and the third surface. The air gap formed by the second surface and the third surface has a cross section perpendicular to the first surface and the second surface which is a wedge shape which is wide at a part thereof near the first surface and narrower at a part thereof more distant from the first surface.