Patent ID: 8182098

Claim:
A projection optical system comprising: a first optical part that comprises at least one optical lens, and projects and displays light beams; a second optical part that comprises an image forming element and at least one optical lens, and emits incident light beams as light beams with images; and a third optical part that comprises a light source unit and a deflector that is located between the first and second optical parts, such that the deflector reflects light beams emitted from the light source unit to the at least one lens of the second optical part and the light beams with images emitted from the image forming element and through the at least one lens of the second optical part are transmitted through the deflector to the first optical part; wherein the second optical part, which comprises at least one optical lens located between the image forming element and the deflector, comprises: a meniscus lens that has a concave surface facing the plane of the image forming element; and a triplet lens.