Patent ID: 7352521

Claim:
An optical system which guides a displaying luminous flux from a display device to an eye of an observer, comprising: a first optical element and a second optical element in order from the side of an exit pupil of the optical system to the side of the display device, wherein a combined optical power provided by an emergent surface of the second optical element and an incident surface of the first optical element is a negative optical power, and the optical system forms an intermediate image with the displaying luminous flux in the first optical element; and wherein the first optical element includes at least a first surface which has a reflecting action and a second surface which reflects the displaying luminous flux reflected by the first surface back toward the first surface such that a central principal ray of the displaying luminous flux incident again on the first surface is reflected and travels in a direction substantially opposite to a reflecting direction in the previous reflection at the first surface with respect to a normal to the first surface at a hit point of the central principal ray.