Optical element and compound display apparatus using the same

An image pickup optical system having a first optical element having on the same medium an incidence surface, an emergence surface and a plurality of eccentric reflecting surfaces eccentric relative to a reference ray Ri and having power, at least one of said plurality of eccentric reflecting surfaces being a dual purpose surface used as a transmitting surface and reflecting surface, wherein a beam incident from said incidence surface is reflected by said plurality of eccentric reflecting surfaces to thereby fold an optical path and is caused to emerge from said emergence surface, and the meridional section composite power is negative, a stop, and a compound lens unit having at least one rotation-asymmetrical lens of which the opposite surfaces comprise a rotation-asymmetrical surface and a rotation-symmetrical surface, respectively, and a plurality of rotation-symmetrical lenses, all of the optical axis of the rotation-symmetrical surface of said rotation-asymmetrical lens and the optical axes of said rotation-symmetrical lenses being substantially coincident with one another, characterized in that design is made such that light from the external world is caused to be incident from the incidence surface of said first optical element, is reflected by said plurality of eccentric reflecting surfaces to thereby fold the optical path and is caused to emerge from said emergence surface, and is passed through said stop, and thereafter is refracted by said compound lens unit and is imaged on an image pickup element.

An image pickup optical system having a first optical element having on the same medium an incidence surface, an emergence surface and a plurality of eccentric reflecting surfaces eccentric relative to a reference ray Ri and having power, at least one of said plurality of eccentric reflecting surfaces being a dual purpose surface used as a transmitting surface and reflecting surface, wherein a beam incident from said incidence surface is reflected by said plurality of eccentric reflecting surfaces to thereby fold an optical path and is caused to emerge from said emergence surface, and at least one of said plurality of eccentric reflecting surfaces is a rotation-asymmetrical surface, and design is made such that the local meridional section focal length fypout and local sagittal section focal length fxpout of said emergence surface and meridional section composite focal length fyp and sagittal section composite focal length fxp of said first optical element satisfy the following conditional expressions:

• |fyp/fypout|<2 (1″)|fxp/fxpout|<2, (2″)
• a stop, and a compound lens unit having at least one rotation-asymmetrical lens of which the opposite surfaces comprise a rotation-asymmetrical surface and a rotation-symmetrical surface, respectively, and a plurality of rotation-symmetrical lenses, all of the optical axis of the rotation-symmetrical surface of said rotation-asymmetrical lens and the optical axes of said rotation-symmetrical lenses being substantially coincident with one another, characterized in that design is made such that light from the external world is caused to be incident from the incidence surface of said first optical element and is reflected by said plurality of eccentric reflecting surfaces to thereby fold the optical path and is caused to emerge from said emergence surface, and is passed through said stop, and thereafter is refracted by said compound lens unit and is imaged on an image pickup element.