Patent ID: 6760169
Filing Date: 2004-07-06
Classification: G02B

Abstract:
An image observation apparatus comprising image forming means and an ocular optical system having an action by which an image formed by said image forming means is led to an eyeball of an observer,wherein said ocular optical system includes at least a prism member, said prism member having at least four optical surfaces having a transmitting or reflecting optical action, wherein a space surrounded by said at least four optical surfaces is filled with a single medium having a refractive index (n) larger than 1 (n>1), said at least four optical surfaces including a first surface having both a transmitting action and a reflecting action and disposed on a side of said prism member that is closer to said observer's eyeball; a second surface having a reflecting action and disposed to face said first surface across said medium, said second surface being at least decentered or tilted with respect to an observer's visual axis; a third surface having a reflecting action and disposed to face said first surface across said medium at a position substantially adjacent to said second surface; and a fourth surface disposed such that one end thereof is substantially adjacent to said first surface, and the other end thereof is substantially close to said third surface, wherein at least said third surface has a totally reflecting action, and said first surface, said single medium and said third surface are arranged to have an external-scene observation action by which an external scene can be observed through said first surface, said single medium and said third surface, and wherein the first surface is identical in surface shape with the third surface.