Patent ID: 6961162

Claim:
An image observation optical system comprising: an image display element; and an eyepiece optical system which introduces an image displayed on the image display element to an observer side without forming an intermediate image, so as to allow an observer to observe the image as a virtual image, wherein the eyepiece optical system is constructed and arranged to bend an optical axis using reflecting surfaces so as to be compact, the optical axis lying in a plane, wherein the eyepiece optical system is symmetrically formed with respect to the plane and includes an optical element, wherein the optical element includes optical surfaces that transmit or reflect light, wherein the optical surfaces consist of an entrance surface that transmits the light a curved reflecting surface that reflects the light, and a curved exit surface that reflects and transmits the light, at least one of the surfaces that reflect light being provided with a volume hologram (HOE), and wherein the surface provided with the HOE has a rotationally asymmetric power.