US 6,310,736 B1Granted

Image-forming optical system and viewing optical system

AssigneeOlympus Optical Co., Ltd.

InventorTakayoshi Togino

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Abstract

A viewing optical system and image-forming optical system in which an intermediate image is formed once and two decentered prisms, i.e. first and second prisms, are arranged to correct each other's decentration aberrations, thereby attaining a wide viewing field angle and a short focal length. The second prism is placed closer to the object side than the first prism and has three optical surfaces, of which a first surface is an entrance surface also serving as a reflecting surface, a second surface is a reflecting surface, and a third surface is an exit surface. At least one of the first and second surfaces has a rotationally asymmetric surface configuration that gives a power to a light beam and corrects aberrations due to decentration. The first prism has a reflecting surface, an entrance surface, and an exit surface. The reflecting surface has a rotationally asymmetric surface configuration that gives a power to a light beam and corrects aberrations due to decentration. An intermediate image surface is formed between the first surface of the second prism and the exit surface of the first prism.

Claims82

Dependent claims

An image-forming optical system for forming an image of an object, said image-forming optical system comprising:

a first prism and a second prism, each of said first prism and second prism being formed from a medium having a refractive index (n) larger than 1 (n>1), said second prism being placed closer to the object than said first prism;
said second prism having three optical surfaces that transmit or reflect a light beam, said three optical surfaces including:
a first surface through which a light beam from an object side of said second prism enters said second prism;
a second surface that reflects the light beam entering through said first surface in said second prism;
said first surface also reflecting the light beam reflected from said second surface in said second prism;
and
a third surface through which the light beam reflected from said first surface exits from said second prism;
wherein at least one of said first surface and second 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;
said first prism having at least:
a decentered reflecting surface having a curved surface configuration and internally reflecting a light beam in said medium, said reflecting surface having a rotationally asymmetric surface configuration that gives a power to a light beam and corrects aberrations due to decentration;
an entrance surface through which a light beam enters said first prism;
and
an exit surface through which the light beam exits from said first prism;
wherein an intermediate image surface is formed between the first surface of said second prism and the exit surface of said first prism.

11 more elements

A viewing optical system that forms an exit pupil for viewing an observation image, said viewing optical system comprising:

a first prism and a second prism, each of said first prism and second prism being formed from a medium having a refractive index (n) larger than 1 (n>1);
said second prism being placed closer to said exit pupil than said first prism;
said first prism having at least:
a decentered reflecting surface having a curved surface configuration and internally reflecting a light beam in said medium, said reflecting surface having a rotationally asymmetric surface configuration that gives a power to a light beam and corrects aberrations due to decentration;
an entrance surface through which a light beam from said observation image enters said first prism;
and
an exit surface through which the light beam exits from said first prism;
said second prism having three optical surfaces that transmit or reflect a light beam, said three optical surfaces including:
a third surface through which the light beam exiting from said first prism enters said second prism;
a first surface that reflects the light beam entering through said third surface in said second prism;
a second surface that reflects the light beam reflected from said first surface in said second prism;
and
said first surface also allowing the light beam reflected from said second surface to exit from said second prism;
wherein at least one of said first surface and said second 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 an intermediate image surface is formed between the first surface of said second prism and the entrance surface of said first prism.

12 more elements

Dependencies are inferred from the claim text.