PROJECTION OPTICAL SYSTEM AND PROJECTION TYPE IMAGE DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To secure sufficient production margin while coping with an environmental change such as a temperature change while achieving downsizing. SOLUTION: The projection optical system enlarges and projects light from a primary image surface P on a reduction side to a secondary image surface S on an enlargement side, and is equipped with: a first optical system L1 forming an intermediate image on the primary image surface P and constituted of three groups having negative, positive and positive refractive power from the intermediate image side from a diaphragm; and a second optical system L2 having one concave reflection surface formed nearer to the secondary image surface S side than the intermediate image. The respective surfaces constituting the first optical system L1 and the second optical system L2 are constituted of rotationally symmetric surfaces with a common optical axis as center. A light beam leading to the center of the secondary image surface S from the center of the primary image surface P crosses the optical axis, then it is reflected on the concave reflection surface and crosses the optical axis again to reach the secondary image surface S. The projection optical system satisfies conditional expressions (1) 0.5<ϕ1/ϕ2<3, (2) 1