US 6,788,343 B1Granted

Image-forming optical system

AssigneeOlympus Corporation

InventorTakayoshi Togino

Life of this patent

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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 a single prism. When image-side three surfaces of the prism are defined as a surface A, a surface B and a surface C in order from the image plane side thereof, at least one of the surfaces B and C has a rotationally asymmetric curved surface configuration that gives a power to a light beam and corrects aberrations due to decentration. The optical system leads light rays from an object to the image plane without forming an image in the prism and has a pupil in the prism. The surface A is a transmitting surface through which rays exit from the prism. The surfaces B and C are internally reflecting surfaces, which are positioned to face each other to form a Z-shaped optical path.

Claims29

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:

at least one prism formed from a medium having a refractive index (n) larger than 1.3 (n>1.3),
wherein said prism has at least four optical surfaces that transmit or reflect a light beam, and when image-side three surfaces of the at least four optical surfaces are defined as a surface A, a surface B and a surface C in order from an image plane side of said prism, at least one of said surface B and said surface C 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 image-forming optical system being adapted to lead light rays from an object to an image plane without forming an image in said prism, and said image-forming optical system having a pupil in said prism,
said surface A having a transmitting action by which rays internally reflected from said surface B are allowed to exit from said prism,
said surface B having a reflecting action to reflect rays internally reflected from said surface C, and said surface C having a reflecting action.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/417,914Filed 13 Oct 1999
Priority: JP 10-3472847 Dec 1998
Granted: 7 Sep 2004
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G02B 17/086
Comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors: wherein the system…
G02B 17/0848
Using more than three curved mirrors: off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry,…
H04N 23/55
Constructional details: optical parts specially adapted for electronic image sensors; Mounting thereof
H04N 23/63
Control of cameras or camera modules: by using electronic viewfinders