Prism optical element, image observation apparatus and image display apparatus
First Claim
1. A prism optical element comprising a plurality of surfaces facing each other across a medium having a refractive index (n) larger than 1 (n>
- 1), wherein said plurality of surfaces include a first surface having both a transmitting action through which light rays enter said prism optical element or exit therefrom and a reflecting action by which light rays are internally reflected in said prism optical element;
a second surface disposed to face said first surface across said medium and having a reflecting action by which light rays are internally reflected in said prism optical element;
a third surface disposed substantially close to said second surface to face said first surface across said medium and having a reflecting action by which light rays are internally reflected in said prism optical element; and
a fourth surface having such a transmitting action that when said first surface has an action through which light rays enter said prism optical element, said fourth surface has an action through which light rays exit from said prism optical element, whereas, when said first surface has an action through which light rays exit from said prism optical element, said fourth surface has an action through which light rays enter said prism optical element, and wherein the following condition is satisfied;
sin−
1(1/nd)≦
θ
r3≦
60°
(1) where nd is a refractive index for the spectral d-line of said medium, and θ
r3 is an angle of internal reflection of an arbitrary light ray at said third surface.
2 Assignments
0 Petitions
Accused Products
Abstract
An extremely compact prism optical element, image observation apparatus and image display apparatus which are capable of providing an observation image that is clear and has minimal aberration and minimal distortion even at a wide field angle. Light rays emitted from an image display device (7) enter an ocular optical system (12) through a fourth surface (6) and are totally reflected toward an observer'"'"'s pupil (1) by a third surface (5). The reflected light rays are reflected by a first surface (3) disposed immediately in front of the observer'"'"'s pupil (1) and then reflected toward the observer'"'"'s pupil (1) by a second surface (4). The reflected light rays pass through the first surface (3) and are projected into an observer'"'"'s eyeball (15) with the observer'"'"'s iris position as an exit pupil (1). When an external-scene image is observed, light rays from an object point in,the external scene enter the ocular optical system (12) through the third surface (5), pass through the first surface (3) and are projected into the observer'"'"'s eyeball (15). Assuming that the angle of internal reflection of an arbitrary light ray at the third surface (5) is θr3, the ocular optical system (12) satisfies the condition of sin−1(1/nd)≦θr3≦60°, where nd is the refractive index for the spectral d-line of the medium of the ocular optical system (12).
-
Citations
53 Claims
-
1. A prism optical element comprising a plurality of surfaces facing each other across a medium having a refractive index (n) larger than 1 (n>
- 1), wherein said plurality of surfaces include a first surface having both a transmitting action through which light rays enter said prism optical element or exit therefrom and a reflecting action by which light rays are internally reflected in said prism optical element;
a second surface disposed to face said first surface across said medium and having a reflecting action by which light rays are internally reflected in said prism optical element;
a third surface disposed substantially close to said second surface to face said first surface across said medium and having a reflecting action by which light rays are internally reflected in said prism optical element; and
a fourth surface having such a transmitting action that when said first surface has an action through which light rays enter said prism optical element, said fourth surface has an action through which light rays exit from said prism optical element, whereas, when said first surface has an action through which light rays exit from said prism optical element, said fourth surface has an action through which light rays enter said prism optical element, and wherein the following condition is satisfied;
sin−
1(1/nd)≦
θ
r3≦
60°
(1)where nd is a refractive index for the spectral d-line of said medium, and θ
r3 is an angle of internal reflection of an arbitrary light ray at said third surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 33, 34, 35, 36, 37)
- 1), wherein said plurality of surfaces include a first surface having both a transmitting action through which light rays enter said prism optical element or exit therefrom and a reflecting action by which light rays are internally reflected in said prism optical element;
-
11. 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 a prism member having at least three surfaces, wherein a space between said at least three surfaces is filled with a single medium having a refractive index (n) larger than 1 (n> - 1),
said prism member having an action by which light rays emitted from said image forming means are internally reflected at least three times, wherein at least two of the at least three internal reflections are total reflections, and wherein at least one of the at least two total reflections is performed by a surface disposed on a side of said single medium that is closer to said observer, said surface being curved so as to correct aberrations produced by the internal reflections in said prism member, and wherein at least two of the at least three surfaces of said prism member are disposed to face each other such that an external scene can be observed through said at least two surfaces, and that a distortion produced when the external scene is observed through said single medium is minimized.
- 1),
-
12-32. -32. (canceled)
-
38. An image display apparatus comprising an image display device and an ocular optical system for leading an image formed by said image display device to an eyeball of an observer such that said image can be observed as a virtual image,
wherein said ocular optical system includes: -
a decentered prism in which a space formed by at least two surfaces is filled with a medium having a refractive index larger than 1, said at least two surfaces including a first surface positioned immediately in front of the observer'"'"'s eyeball, and a second surface which is a reflecting surface facing said first surface, at least one of said at least two surfaces being a curved surface decentered or tilted with respect to an observer'"'"'s visual axis, and aberration correcting means disposed outside said second surface to correct aberrations due to decentration produced by said first and second surfaces with respect to light from an external scene. - View Dependent Claims (39, 40, 41, 42, 43, 48, 49, 50, 51)
-
-
44. An image display apparatus comprising an image display device and an ocular optical system for leading an image formed by said image display device to an eyeball of an observer such that said image can be observed as a virtual image,
wherein said ocular optical system includes a decentered prism in which a space formed by at least three surfaces is filled with a medium having a refractive index larger than 1; -
said at least three surfaces including;
a refracting and internally reflecting surface positioned immediately in front of said observer'"'"'s eyeball;
an outside world-side internally reflecting surface disposed on an outside world side of said ocular optical system to face said refracting and internally reflecting surface; and
a refracting surface through which a bundle of light rays emitted from said image display device enters said decentered prism, wherein at least one of said at least three surfaces is decentered or tilted with respect to an observer'"'"'s visual axis, and said at least three surfaces are arranged to perform at least three internal reflections, said ocular optical system further includes a second optical element that cancels a power produced by said refracting and internally reflecting surface, which is positioned immediately in front of said observer'"'"'s eyeball, and said outside world-side internally reflecting surface with respect to external light when an external scene is observed through said two surfaces, said second optical element being disposed on an outside world side of said outside world-side internally reflecting surface. - View Dependent Claims (45, 46, 47)
-
-
52. An optical system comprising:
-
a decentered prism having at least two surfaces, wherein a space formed by said at least two surfaces is filled with a medium having a refractive index larger than 1; and
aberration correcting means provided at a position separate from said decentered prism;
wherein at least one of said at least two surfaces is a curved surface decentered or tilted with respect to a predetermined axis, and wherein said aberration correcting means is provided so that light that has passed through said aberration correcting means passes through said decentered prism.
-
-
53. An optical system comprising:
-
a decentered prism having at least three surfaces, wherein a space formed by said at least three surfaces is filled with a medium having a refractive index larger than 1; and
a second optical element provided at a position separate from said decentered prism;
wherein at least one of said at least three surfaces is a curved surface decentered or tilted with respect to a predetermined axis;
said at least three surfaces including a first surface and a second surface;
said second surface being positioned closest to said second optical element;
said first surface being positioned to face said second optical element across said second surface; and
wherein said second optical element is provided so that light that has passed through said second optical element passes through said decentered prism, and said second optical element cancels a power produced by said second surface.
-
Specification