US 6,124,989 AGranted

Image-forming optical system

AssigneeOlympus Optical Co., Ltd.

InventorsHisashi Oode, Takayoshi Togino

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Abstract

A high-performance image-forming optical system made compact and thin by folding an optical path using reflecting surfaces arranged to minimize the number of reflections. The image-forming optical system has only one prism member. The prism member has a first surface through which a light beam enters the prism member, a second surface reflecting the incident light beam in the prism member, a third surface reflecting the reflected light beam in the prism member, and a fourth surface through which the light beam exits from the prism member. At least one of the second and third surfaces has a curved surface configuration that gives a power to a light beam. The curved surface configuration has a rotationally asymmetric surface configuration that corrects aberrations due to decentration. A pupil is provided between the first and fourth surfaces, for example, on the second surface.

Claims28

Dependent claims

An image-forming optical system having a positive refracting power as a whole for forming an object image, said image-forming optical system comprising:

only one prism member formed from a medium having a refractive index (n) larger than 1 (n>1),
said prism member having:
a first surface through which a light beam enters said prism member;
a second surface that reflects the light beam in said prism member;
a third surface that reflects the light beam reflected by said second surface in said prism member;
and
a fourth surface through which the light beam reflected by said third surface exits from said prism member;
wherein at least one of said second surface and said third surface has a curved surface configuration that gives a power to a light beam, said curved surface configuration having a rotationally asymmetric surface configuration that corrects aberrations due to decentration;
wherein a pupil is provided between said first surface and fourth surface of said prism member.

6 more elements

Dependencies are inferred from the claim text.