US Patent 7894138 Display optical system and image display apparatus including the same

At least one exemplary embodiment is directed to a display optical system which includes a first optical system configured to form a magnified image of an image displayed on an image display element, the first optical system including an optical member, a second optical system configured to magnify and guide light of the magnified image from the first optical system to one of an observer or a projection surface, the second optical system including a decentered reflecting surface, and an adjusting mechanism configured to displace the optical member of the first optical system in such a way as to have a component in a direction perpendicular to an optical axis of the first optical system.