WO2009145256A1

WO2009145256A1 - Optical system, head-mounted type projector, and recursive penetrating element

Info

Publication number: WO2009145256A1
Application number: PCT/JP2009/059772
Authority: WO
Inventors: 竜吾木島
Original assignee: 国立大学法人岐阜大学
Priority date: 2008-05-30
Filing date: 2009-05-28
Publication date: 2009-12-03
Also published as: JP2009288696A

Abstract

Provided is an optical system comprising a projector (20) and a recursive penetrating element (13) arranged to face the projector (20). The optical system causes the incident light of an unreal image projected from the projector (20), to penetrate recursively through the recursive penetrating element (13). As a result, a virtual image is formed on the side opposite to the incidence face of the recursive penetrating element (13) by the light having recursively penetrated. An observer can observe the optical beam caused to penetrate recursively by the recursive penetrating element (13), as a virtual image.

Description

Optical system, head mounted projector, and retrotransmissive element

The present invention relates to an optical system, a head-mounted projector, and a retrotransmissive element.

The optical elements can be generally divided into refractive optical systems and reflective optical systems except for special ones such as hologram optical elements. In order to construct an optical system or to design in detail using simulation, a theoretical system is established centering on the refractive and reflective optical systems that are the basic elements, and each of the above basic elements is used independently. Various optical devices configured by combining or combining them have been proposed. However, the point that the optical element is limited to these two types of systems is the biggest restriction when the optical system is configured.

A refractive optical system is a system in which optical elements are arranged in a line and light is passed through them in order. In the case of a refractive optical system, the traveling direction of light does not change. On the other hand, the reflective optical system can change the traveling direction of light. For the design of optical equipment, after determining the operating principle, the two optical systems are combined, and the position of each optical element is determined so as not to interfere in space. A technique related to this application is disclosed in Non-Patent Document 1.

As in the case of machines, spatial interference greatly restricts the positional relationship between multiple optical elements. For this reason, even if the operating principle of the optical device is determined, there are cases where the optical elements cannot be arranged at desired positions. In order to solve and alleviate this, a beam splitter composed of a half mirror or a prism may be used.

For example, as shown in FIG. 15, in a head mounted projector (HMD), if the projector 10 is placed at a human viewpoint position 12 and an image can be projected onto the screen 14, the shape of the screen 14 is a curved surface. This is advantageous because the observed image is not distorted. However, in practice, the projector 10 and the human viewpoint interfere with each other, so that the exit pupil of the projector 10 cannot be installed at the viewpoint position 12. In that regard, as shown in FIG. 16, if the beam splitter 16 is placed in front of the human eye, that is, in front of the observation viewpoint A, the interference in the space is eliminated. Conventionally, head-mounted projectors arranged in this way are known.

Here, the beam splitter 16, that is, a transmissive mirror such as a half mirror folds the space. Since the projector 10 overlaps the human pupil (observation viewpoint A) in the folded space, the above operation principle is satisfied. Even in this case, it is necessary to devise arrangement of the optical elements. FIG. 17 shows the same operating principle as FIG. However, since the light path to the screen 14 is blocked by the projector 10, a complete real image cannot be observed.

In the case of an optical system having a conventional projector, it is necessary to consider not only the screen but also the installation location of the screen. For this reason, an optical system that does not require a screen is required in an optical system that uses a projector.

An object of the present invention is suitable for a novel optical system, a head-mounted projector, and the optical system described above, in which a screen is not required by converting a virtual image despite the use of a projector for forming a real image. It is to provide a retrotransmissive element that can be used.

In order to solve the above problems, according to a first aspect of the present invention, there is provided a projector and a retrotransmissive element disposed so as to face the projector, and is a surface opposite to the incident surface of the retrotransmissive element. When transmitting incident light, a retro-transmission element that changes the direction of the light in a direction symmetric with respect to the retro-transmission axis and emits the light, and incident light of an unreal image projected from the projector is transmitted through the retro-transmission element. Thus, an optical system in which an image is formed can be provided.

When the image formation position of the real image is set on the side opposite to the incident surface of the light beam (a position away from the surface opposite to the incident surface), the light beam incident on the incident surface from the projector is still a real image. Not. For this reason, the light beam before forming a real image is called an “unreal image”.

In addition, the light rays incident on the retrotransmissive material pass through the material. However, when compared with the case where there is no retrotransmissive material, the light emitted from the retrotransmissive material is axisymmetric with respect to the incident light. The axis at this time is a retro-transmission axis. For example, in the structure using the retroreflective element 32 and the planar beam splitter (semi-reflective layer 40) shown in FIGS. 4 to 6, the normal line G of the beam splitter is the retrotransmission axis. If the beam splitter is a semi-transparent curved mirror, the normal line at each position of the curved surface is the retrotransmission axis. Further, when the curved mirror is miniaturized and formed as a Fresnel reflecting mirror, the normal line of each reflecting mirror is the retrotransmission axis. In the case of the structure using the orthogonal two-sided mirror (corner mirror) shown in FIGS. 7 and 8, the intersection line of the two orthogonal mirrors is the retrotransmission axis. Further, in this case, as shown in FIG. 13, by changing the arrangement of the retrotransmission axes depending on the location, the same optical effect as in the case of the curved mirror can be obtained.

With the above configuration, the projector makes the light flux (unreal image) incident on the retrotransmissive element. The group of rays that are converging toward the real image position are spread apart by the retrotransmission element, but allow the rays to pass to the side opposite to the incident surface of the retrotransmission element. In this sense, the traveling direction of light does not change. Conversely, the angle for convergence is the angle for spreading. For this reason, these ray bundles, conversely, form a virtual image. This virtual image exists in a symmetrical position with respect to the original real image and the retrotransmissive surface. In other words, the retrotransmissive element does not change the traveling direction of the light flux despite the fact that the space is folded and the real image is converted into the virtual image. For this reason, light enters the observer's pupil. Therefore, the observer can observe the image.

The beam splitter 16 mentioned in the background art is the same as the retrotransmissive element of the present invention in that the space is folded back, but is different from the retrotransmissive element of the present invention in that the traveling direction of the light beam is changed. It is preferable that all the optical systems in the present embodiment are composed of reflective elements.

According to the above optical system, it is possible to convert a non-real image (light bundle) into a real image / virtual image by the retrotransmissive element, although a projector for forming a real image is used. For this reason, the observer can observe the light beam retroreflected by the retrotransmissive element as a virtual image, and can eliminate the need for a screen.

In the above optical system, the retrotransmissive element is preferably curved.
According to the above optical system, since the retrotransmissive element is curved, the focal position of the virtual image can be moved distally or proximally as compared with the case where the retrotransmissive element is not curved, A wide field of view or a narrow field of view can be obtained.

In order to solve the above problem, according to the second aspect of the present invention, the optical system is provided on a support body mounted on the user's head, and the user visually recognizes a virtual image due to retroreflected light. In order to be able to do so, there is provided a head mounted projector in which a retrotransmissive element is arranged with respect to a support.

According to the above head-mounted projector, it is possible to convert a non-real image (light bundle) into a real image / virtual image by the retrotransmissive element, even though a projector for forming a real image is used. For this reason, the observer can observe the light beam retroreflected by the retrotransparent element as a virtual image. Therefore, a screen can be dispensed with.

In order to solve the above problems, according to the third aspect of the present invention, the transparent layer, the first surface of the transparent layer, or the semi-reflective layer provided inside the transparent layer, and the first of the transparent layer are provided. And a plurality of retroreflective elements provided in the second surface opposite to the surface of the transparent surface and reflecting the light toward the semi-reflective layer. The retroreflective elements are discretely arranged. A retrotransparent element is provided.

According to the retrotransmissive element, when the incident light is transmitted to the surface opposite to the incident surface of the retrotransmissive element, the traveling direction of the light beam is changed to a direction symmetric with respect to the retrotransmissive axis. It can be ejected from the element. By using such retro-transparency, it is possible to provide a retro-transmission element that can be suitably used in the above-described optical system and head-mounted projector.

In addition, the retrotransmissive element described above folds the space, passes a part of the incident light beam, and passes it to the surface opposite to the incident surface. From this point, the retrotransmissive element is a new optical element that does not change the traveling direction of incident light and converts an unreal image (light bundle) before imaging into a virtual image. Therefore, a new element can be added as an element constituting the optical system.

In the retrotransmissive element, the semi-reflective layer is preferably curved.
According to the retrotransmissive element, the focal position of the virtual image when the non-real image (light bundle) incident on the retrotransmissive element passes to the side opposite to the incident surface because the semi-reflective layer is curved. Can be moved distally or proximally, and a wide or narrow field of view can be obtained.

In the retroreflective element, the semi-reflective layer is curved in a concave shape, the reflective surface of the semi-reflective layer is formed as a concave mirror, and the light beam that passes through the semi-reflective layer and is reflected by the retroreflective element is reflected on the reflective surface. Preferably, the light is reflected, passes through the transparent layer, and is emitted to the outside.

According to the retroreflective element, the semi-reflective layer is curved in a concave shape, the reflective surface of the semi-reflective layer is formed into a concave mirror, and the light reflected by the retroreflective element after passing through the semi-reflective layer is reflected. The light is further reflected by the surface, passes through the transparent layer, and is emitted to the outside. Thereby, an effect equivalent to said retrotransmissive element can be realized.

In the retroreflective element, the semi-reflective layer is curved into a convex shape, the reflective surface of the semi-reflective layer is formed as a convex mirror, and the light incident on the transparent layer is reflected by the reflective surface. Preferably, the light is reflected, passes through the semi-reflective layer, and is emitted to the outside.

According to the retrotransmissive element, the semi-reflective layer is curved in a convex shape, the reflective surface of the semi-reflective layer is formed on the convex mirror, and the light incident on the transparent layer is reflected by the reflective surface, and further retroreflective. The light is reflected by the conductive element, passes through the semi-reflective layer, and is emitted to the outside. Thereby, an effect equivalent to said retrotransmissive element can be realized.

In order to solve the above-described problem, according to the fourth aspect of the present invention, the plate-shaped element body is formed with a void group in which a plurality of voids are arranged in a dotted line and a circle, There is provided a retrotransmissive element in which a plurality of gap groups are arranged concentrically and the wall surface of the gap is a mirror surface.

In order to solve the above problems, according to the fifth aspect of the present invention, a plurality of circular gaps having different diameters are formed concentrically with respect to the plate-shaped element body, and the wall surfaces of the gaps are mirror surfaces. There is provided a retrotransmissive element in which the gap has a pair of open ends opened on both sides of the element body, and at least one of the open ends is closed.

In the retrotransmissive element, the void is preferably a through hole.
In order to solve the above problems, according to the sixth aspect of the present invention, a plurality of gaps extending in the thickness direction of the element body are randomly arranged in the plate-like element body, and two surfaces are provided on the inner surface of the gap. An orthogonal mirror is formed, and the two-surface orthogonal mirror is composed of a first mirror surface and a second mirror surface that are orthogonal to each other, and an intersection line between the first mirror surface and the second mirror surface is arranged along the thickness direction of the element body. A retrotransparent element is provided.

In the retrotransmissive element, the void is preferably a through hole.
In the retrotransmissive element, it is preferable that the element body has a curved surface, and the intersecting line of the two-surface orthogonal matching mirror is arranged along the normal direction of the curved surface.

In the retrotransparent element, a two-plane orthogonal mirror is arranged in the element body, and the retrotransmission axis is set according to the location. It is preferable to add.

Here, “folding” regarding a mirror, a retroreflective element, and an element having retrotransparency (hereinafter referred to as a retrotransmissive element) will be described.
(Space wrapping)
The mirror folds the space symmetrically with respect to the mirror surface. This is because the mirror folds the incident light beam in the normal direction of the mirror surface. For this reason, both the real object in front of the mirror as viewed from the observer and the real image projected by the projector are observed as a virtual image existing on the opposite side of the observer with respect to the mirror. The virtual image that can be observed by the observer is observed as a virtual image on the side opposite to the observer with respect to the mirror.

On the other hand, the retroreflective element forms the light flux emitted from the object and the projected real image as a real image at the original position, despite the fact that the incident light is folded back in the normal direction in the same manner as the mirror. The difference between the retroreflection and the mirror is that the light beam is folded in a plane that is in-plane folding, that is, in a plane orthogonal to the normal of the incident surface of the retroreflective element. Thus, since the space is also folded by the in-plane folding, the space is folded twice in total. Therefore, the retroreflective element has an effect of not folding the space.

“Folding in the plane” changes the beam bundle concentrated at the image point to a divergent beam beam like light emitted from the image point, and conversely concentrates the beam beam emitted from the object or image point. Has the effect of image formation.
FIG. 1 shows the presence / absence of “in-plane folding” and “folding in the normal H direction” in the transparent plate 10, the mirror 11, the retroreflective element 12, and the retrotransmissive element 13.

In-plane folding refers to folding of light rays in a plane orthogonal to the normal H of the incident surface. The normal H direction refers to the normal direction on the incident surface of each member.
In FIG. 1, “× (+1)” indicates no folding, and “× (−1)” indicates folding. In FIG. 1, (a), (b), and (c) in the transparent plate 10, the mirror 11, the retroreflective element 12, and the retrotransmissive element 13 show a perspective view, a plan view, and a side view of each member. In the perspective view, the plan view, and the side view, the traveling direction of the light ray K in each member is shown. A black circle in FIG. 1B indicates an incident point of the light ray K in each member.

(Row, Column) = (1, 1) is the transparent plate 10 that is not folded in any of the in-plane and normal directions.
(Row, Column) = (1, −1) is a mirror that has no in-plane fold and has fold (simple reflection) in the normal H direction. As a result, the mirror converts the real image into a virtual image.

(Row, column) = (− 1, −1) indicates the retroreflective element 12 with in-plane folding and with normal H-direction folding. In this case, as described above, because of the in-plane folding, the concentrated light and the diffused light are converted without folding the space as a result. For this reason, the real image is formed again at the original position. The virtual image that can be observed when viewed from the retroreflective element 12 forms a real image at the virtual image position.

(Row, column) = (− 1, 1) indicates the retrotransmissive element 13. As shown in FIGS. 1 and 2, the retrotransmissive element 13 performs only in-plane folding without performing folding in the normal H direction.

(Real image to virtual image conversion)
When the imaging position of the real image is set on the side opposite to the incident surface of the light beam (a position away from the surface opposite to the incident surface), the light beam incident on the incident surface is not yet a real image. For this reason, the light bundle before forming a real image is described below as an “unreal image” for convenience of explanation.

In the case of the mirror 11, the unreal image is folded back by the mirror surface that is the incident surface, and a real image is formed in front of the mirror surface as viewed from the observer.
In the case of the retroreflective element 12 and the retrotransmissive element 13, the unreal image is converted into concentration and spread by folding in-plane, and forms a virtual image after being folded. Thus, the effect | action which an unreal image is converted into a virtual image is described below as real image virtual image conversion.

In the case of the retroreflective element 12, the light bundle of the unreal image travels in the direction opposite to the incident direction. Then, a virtual image is formed at the original position where the real image existed when there was no retroreflective element. Further, in the case of the retrotransmissive element 13, the light beam of the unreal image is formed at a position where the plane orthogonal to the normal line of the retrotransmissive element 13 is folded back symmetrically to form a virtual image.

The retroreflective element can be suitably used for the optical system and the head-mounted projector. In addition, the retrotransmissive element described above folds back the space, allows a part of the incident light beam to pass therethrough, and passes it to the side surface opposite to the incident surface. From this point, the retrotransmissive element is a new optical element that does not change the traveling direction of light and converts an unreal image (light bundle) before image formation into a virtual image. As a result, a new element can be added as an element constituting the optical system.

It is explanatory drawing of the presence or absence of the folding | turning of the space of a transparent plate, a mirror, a retroreflective element, and a retrotransmissive element, (a) is a perspective view of each member, (b) is a top view of each member, (c) is The side view of each member. The perspective view for demonstrating the return of the space by a retroreflective element. (A) is explanatory drawing of the optical system which concerns on 1st Embodiment of this invention, (b) is explanatory drawing of the optical system which concerns on 2nd Embodiment of this invention. (A), (b), (c) is sectional drawing which shows the outline of a retrotransmissive element. (A), (b) is a fragmentary sectional view of a retrotransmissive element. (A), (b) is a fragmentary sectional view of the retroreflective element which concerns on other embodiment. The perspective view which shows the outline of the retrotransmissive element which concerns on 3rd Embodiment of this invention. (A), (b) is explanatory drawing of the optical path in the retrotransmissive element of 3rd Embodiment. (A) is a perspective view which shows the outline of the retrotransmissive element based on 4th Embodiment of this invention, (b) is explanatory drawing of an optical path. (A) is a perspective view which shows the outline of the retrotransmissive element which concerns on the modification of 4th Embodiment, (b) is explanatory drawing of an optical path. (A), (b) is sectional drawing which shows the outline of the retrotransmissive element which concerns on other embodiment of a retrotransmissive element. (A) is explanatory drawing of the optical path by the retrotransmissive element which concerns on 3rd Embodiment, (b), (c) is explanatory drawing of the optical path by the retrotransmissive element which concerns on other embodiment. Sectional drawing which shows the outline of the retrotransmissive element which concerns on other embodiment. (A) is a top view of the head mounted projector which concerns on 8th Embodiment of this invention, (b) is explanatory drawing of an optical system. Explanatory drawing which shows the outline of the conventional head mounted projector. Explanatory drawing which shows the outline of the conventional head mounted projector. Explanatory drawing which shows the outline of the conventional head mounted projector.

(First embodiment)
Hereinafter, an embodiment embodying the optical system of the present invention will be described with reference to FIGS.

As shown in FIG. 3A, the optical system is composed of a projector 20 and a plate-like retro-transmissive element 13 disposed to face the projector 20. The retrotransmissive element 13 is arranged between the position where the light beam projected by the projector 20 forms an image and the projector 20. The projection point 20a of the projector 20 is a position optically conjugate with the observer's observation viewpoint A, and is disposed outside the observer's visual field.

The projector 20 originally forms a real image in the direction in which the real image is projected. According to the present invention, the retrotransmissive element 13 is disposed between the image forming position of the real image and the projector 20. From this, the observer can observe the light beam projected from the projector 20 as a virtual image on the projector 20 side of the retro-transmissive element 13 from the observation viewpoint A by space folding and real image virtual image conversion.

As shown in FIG. 4A and FIG. 5A, the retrotransmissive element 13 includes a transparent solid layer 30 as a transparent layer, a plurality of retroreflective elements 32, and a flat semi-reflective layer 40. It consists of. The transparent solid layer 30 is formed in a flat plate shape. The retroreflective elements 32 are discretely arranged on the first surface of the transparent solid layer 30. The semi-reflective layer 40 is composed of a half mirror, and is formed as a beam splitter laminated on the second surface of the transparent solid layer 30. In the present embodiment, the normal line of the semi-reflective layer 40 (half mirror) is the retro-transmission axis G of the retro-transmission element 13. The semi-reflective layer 40 is provided on the boundary surface with the transparent solid layer 30, but may be provided inside the transparent solid layer 30. For convenience of explanation, in FIG. 4A, the configuration of the retrotransmissive element 13 is simplified to show the optical path of the light beam K.

The transparent solid layer 30 is made of a transparent material. As a transparent material, transparent plastics, such as an acrylic resin, or glass can be mentioned, for example.
The retroreflective element 32 is composed of a corner cube prism. The corner cube prism is made of the same transparent material as the transparent solid layer 30 and has retroreflectivity. The size of the corner cube prism is preferably set to a minute size of mm units or micro units.

In order to form the corner cube prism on the transparent solid layer 30, a fine processing technique such as known photolithography, LIGA using X-rays, or nanoimprinting is used. On the outer surface of the corner cube prism, a coating layer 33 made of a metal film is formed by aluminum vapor deposition or the like in order to improve the total reflection of light rays. The coating layer 33 may be formed of a silver vapor deposition film or a chromium vapor deposition film in addition to the aluminum vapor deposition film. The accuracy of retroreflection by the retroreflective element 32 is the accuracy of retrotransmission. On the transparent solid layer 30, the degree of freedom of arrangement of the retroreflective elements 32 is extremely high.

A part of the light beam K (incident light) incident on the surface (incident surface) of the semi-reflective layer 40 is transmitted through the semi-reflective layer 40 and enters the transparent solid layer 30, and the retroreflective element 32 (corner cube). Retroreflects on the reflective surface. A part of the retroreflected light beam K is further reflected by the semi-reflective layer 40. Thereafter, a part of the retroreflected light beam K passes through the transparent solid layer 30 and is emitted from the surface between the adjacent retroreflective elements 32 to the outside from the surface opposite to the incident surface of the retrotransmissive element 13. .

The case where the light ray K is incident from the surface of the semi-reflective layer 40 has been described above with reference to FIG. However, as shown in FIG. 4B, when the light beam K is incident on the surface (incident surface) of the transparent solid layer 30, the properties of the retrotransmissive element 13 are as follows. For convenience of explanation, in FIG. 4B, the configuration of the retrotransmissive element 13 is simplified to show the optical path of the light beam K. That is, the light ray K (incident light) incident between the adjacent retroreflective elements 32 passes through the transparent solid layer 30 and travels toward the semi-reflective layer 40. Subsequently, a part of the light beam K is reflected by the reflecting surface of the semi-reflective layer 40 and then retroreflected by the retroreflective element 32 on the transparent solid layer 30. A part of the retroreflected light beam K passes through the transparent solid layer 30 and the semi-reflective layer 40 and is emitted to the outside from the surface opposite to the incident surface of the retrotransmissive element 13. As described above, the surface of the retrotransmissive element 13 facing the projector 20 may be either the transparent solid layer 30 or the semi-reflective layer 40.

In this way, the light beam K (incident light) projected from the projector 20 is folded back by the retroreflective element 32 and the semi-reflective layer 40 of the retrotransmissive element 13. That is, the light ray K is retro-transmitted by the retroreflective element 32 and the semi-reflective layer 40, and the reflected light is imaged on the side opposite to the incident surface of the retrotransmissive element 13.

According to the optical system and the retrotransmissive element 13, the following effects can be obtained.
(1) The optical system includes a projector 20 and a retrotransmissive element 13 disposed so as to face the projector 20. According to this optical system, the incident light of the unreal image projected from the projector 20 is retro-transmitted through the retro-transmissive element 13. Thereby, a virtual image is formed on the side opposite to the incident surface of the retrotransmissive element 13 by the retroreflective light. As described above, it is possible to convert an unreal image (light bundle) into a real image / virtual image by the retrotransmissive element 13 in spite of using the projector 20 for forming a real image. For this reason, the observer can observe the light beam retroreflected by the retrotransmissive element 13 as a virtual image. As a result, a screen can be made unnecessary even though the projector is used.

(2) The retrotransmissive element 13 includes a transparent solid layer 30 (transparent layer) and a semi-reflective layer 40 provided on the first surface of the transparent solid layer 30. The transparent solid layer 30 has a second surface opposite to the first surface. A plurality of retroreflective elements 32 are discretely formed on the second surface of the transparent solid layer 30 in order to reflect light rays toward the semi-reflective layer 40.

According to this configuration, the retrotransmissive element 13 changes the direction of incident light in a symmetric direction with respect to the retrotransmission axis G when transmitting incident light (incident light) to a surface opposite to the incident surface. (Retro-transparency). As a result, the retrotransmissive element 13 of the present embodiment can be suitably employed in the above-described optical system.

As described above, the retrotransmissive element 13 turns back the space, passes a part of the incident light beam, and passes it to the surface opposite to the incident surface. From this point, the retrotransmissive element 13 is a new optical element that does not change the traveling direction of incident light and converts an unreal image (light bundle) before image formation into a virtual image. Therefore, a new element can be added as an element constituting the optical system.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In the following embodiments including this embodiment, the same reference numerals are given to the same or similar configurations as those of the other embodiments already described, and detailed description thereof will be omitted.

In the first embodiment, the projector 20 is disposed outside the observer's field of view, but may be disposed within the observer's field of view. For example, as shown in FIG. 3B, even if the projector 20 is arranged in the field of view of the observer, the light beam projected from the projector 20 is converted into a real image / virtual image by the retrotransmissive element 13. As a result, the observer can see a complete virtual image without blocking the light beam projected from the projector 20. Compared with the conventional example shown in FIG. 17 in which only an incomplete real image can be observed, this embodiment is advantageous in that a complete virtual image that is not obstructed can be observed. In the example of FIG. 3B, the observation viewpoint A of the observer is arranged on the optical axis of the projector 20, but in actuality, the observer is coaxial with the exit pupil of the projector 20 so as not to dazzle the observer. The eyes are arranged. The projector 20 shown in FIG. 3B is shown large for convenience of explanation, but the diameter of the penlight is sufficient.

(Third embodiment)
Next, another embodiment of the retrotransmissive element 13 according to the third embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 7, the retrotransmissive element 13 has a flat element body 41. The element body 41 is formed with a plurality of through holes 42 as voids. The through hole 42 is formed of a minute hole having a right-angled triangle in cross section. The through holes 42 penetrate the element body 41 in the thickness direction and are randomly arranged. The element body 41 may be either a transparent body or a non-transparent body.

As shown in FIG. 8A, a corner mirror 43 is formed on the inner surface of the through hole 42. The corner mirror 43 is a two-surface orthogonal mirror that includes a first mirror surface 44 and a second mirror surface 45 that are orthogonal to each other. The corner mirror 43 is formed as a surface mirror by the metal film described in the first embodiment.

The intersecting line (recursive transmission axis G) between the first mirror surface 44 and the second mirror surface 45 is arranged along the thickness direction of the element body 41. The retrotransmission axis G is arranged orthogonal to the plane of the element body 41. The direction of the retrotransmission axis G coincides with the normal direction of the surface of the element body 41. The size of the through hole 42 is preferably set to a minute size of mm units or micro units.

As shown in FIG. 8A, the light beam incident from the first surface of the element body 41 is reflected in the order of the first mirror surface 44 and the second mirror surface 45 or in the order of the second mirror surface 45 and the first mirror surface 44. Then, the light is emitted from the second surface of the element body 41 to the outside. FIG. 8B is an enlarged view of the through hole 42 of the element body 41 in plan view. The light beam incident on the element body 41 is reflected as shown by the arrow in FIG. That is, the retrotransmissive element 13 provided with the corner mirror 43 exhibits retrotransparency.

The effects exhibited by this embodiment will be described below.
(1) The retrotransmissive element 13 has a flat element body 41. In the element body 41, a plurality of through holes 42 (air gaps) penetrating in the thickness direction of the element body 41 are randomly arranged. On the inner surface of the through-hole 42, a corner mirror 43 (two-surface orthogonal alignment mirror) composed of a first mirror surface 44 and a second mirror surface 45 that are orthogonal to each other is formed. Further, an intersection line (recursive transmission axis G) between the first mirror surface 44 and the second mirror surface 45 is arranged along the thickness direction of the element body 41.

The retrotransmissive element 13 turns back the space, passes a part of the incident light beam, and passes it to the surface opposite to the incident surface. From this point, the retrotransmissive element 13 is a new optical element that does not change the traveling direction of incident light and converts an unreal image (light bundle) before image formation into a virtual image. As a result, a new element can be added as an element constituting the optical system.

In addition, since the through holes 42 are randomly arranged, the retrotransmissive element 13 of this embodiment is employed in the optical system of the first embodiment as compared to the case where the through holes 42 are not randomly arranged. Thus, the degree of freedom of the arrangement relationship between the projector 20 and the retrotransmissive element 13 is improved.

(Fourth embodiment)
Next, another embodiment of the retrotransmissive element 13 according to the fourth embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 9A, the retrotransmissive element 13 has a flat element body 41. A plurality of voids 50, that is, through holes are formed in the element body 41. The plurality of gaps 50 are arranged in a dotted line shape and in a circular shape. Thereby, a plurality of gap groups 52 are formed in the element body 41. The plurality of gap groups 52 are all arranged concentrically. The gap 50 has a wall surface 54 formed on a mirror surface. The size of the gap 50 is preferably set to a minute size of mm units or micro units. The interval between adjacent gap groups 52 is preferably set to mm units or micro units. The mirror surface of the wall surface 54 is formed as a surface mirror by the metal film described in the first embodiment.

In the present embodiment, the optical system employing the retrotransmissive element 13 is premised on passing the light beam projected from the projector 20 through a small region such as the exit pupil of the projector 20 or the observer's pupil. Therefore, the projector 20 and the retrotransmissive element 13 are arranged so that the optical axis of the projector 20 and the concentric axis of the gap group 52 are coaxial. In this case, the concentric axis of the gap group 52 is the retrotransmission axis G.

FIG. 9B is a cross-sectional view showing the gap 50 of the element body 41 in an enlarged manner.
When the optical system is formed as described above, the light incident from the first surface of the element body 41 is reflected by the wall surface 54 (mirror surface) of each gap 50 as shown by the arrow in FIG. The light is emitted from the second surface of the element body 41 to the outside. In this way, the retrotransmissive element 13 exhibits retrotransparency.

Also in this embodiment, the retrotransmissive element 13 turns back the space, passes a part of the incident light beam, and passes it to the surface opposite to the incident surface. From this point, the retrotransmissive element 13 is a new optical element that does not change the traveling direction of incident light and converts an unreal image (light bundle) before image formation into a virtual image. As a result, a new element can be added as an element constituting an optical system that is combined in a line.

(Fifth embodiment)
Next, a fifth embodiment of the present invention, which is a modification of the fourth embodiment, will be described with reference to FIGS. 10 (a) and 10 (b).

As shown in FIG. 10A, the retrotransmissive element 13 has an element body 41. A plurality of circular voids 60 are formed in the element body 41. The plurality of gaps 60 have different diameters and are formed concentrically. The gap 60 has a wall surface 62 formed on a mirror surface. The mirror surface should just be formed in the wall surface 62 of a larger diameter at least among a pair of wall surface which forms each space | gap 60. FIG.

The width in the radial direction of the gap is preferably set to a minute size of mm units or micro units. The interval between adjacent gaps 60 is preferably set to mm units or micro units. The mirror surface of the wall surface 62 is formed as a surface mirror by the metal film described in the first embodiment. A transparent plate 64 that closes the first opening end of the gap 60 is laminated on the element body 41. In the present embodiment, the first open end of the gap 60 is closed by the transparent plate 64. Instead of this, a pair of transparent plates may be laminated on both surfaces of the element body 41 to close both of the pair of open ends of the gap 60.

In the present embodiment, the optical system that employs the retrotransmissive element 13 transmits the light bundle projected from the projector 20 to a small area such as the exit pupil of the projector 20 or the observer's pupil, as in the fourth embodiment. It is assumed that you pass. Therefore, the projector 20 and the retrotransmissive element 13 are arranged so that the optical axis of the projector 20 and the concentric axis of the gap group 52 are coaxial.

FIG. 10B is an enlarged sectional view showing the gap 60 of the element body 41.
When the optical system is formed as described above, the light beam incident from the first surface of the element body 41 is reflected by the wall surface 62 (mirror surface) of each gap 60 as shown by the arrow in FIG. Later, the light is emitted from the second surface of the element body 41 to the outside through the transparent plate 64. In this way, the retrotransmissive element 13 exhibits retrotransparency.

The operational effects of the retrotransmissive element 13 of the present embodiment are the same as those of the fourth embodiment.
(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIG. This embodiment embodies claim 6. In the present embodiment, the retrotransmissive element 13 described with reference to FIGS. 5A, 5B, 6A, and 6B is curved. For this reason, the transparent solid layer 30 and the semi-reflective layer 40 constituting the retrotransmissive element 13 are both curved. 11A and 11B, for convenience of explanation, a cross-sectional view of the retrotransmissive element 13 is simply shown as in FIGS. 4A and 4B.

As shown in FIG. 11A, the retrotransmissive element 13 is arranged with the semi-reflective layer 40 facing the projector 20. Both the semi-reflective layer 40 and the transparent solid layer 30 of the retrotransmissive element 13 are curved in a convex shape toward the projector 20. As a result, the reflective surface (mirror surface) of the semi-reflective layer 40 becomes concave, and functions as a concave mirror in which the surface facing the observation viewpoint A is recessed.

In this case, the light beam incident on the retrotransmissive element 13 from the projector 20 is retroreflected by the retroreflective element 32 and then reflected by the reflection surface of the semi-reflective layer 40 functioning as a concave mirror. According to the concave mirror function, the focal point of the virtual image is moved more distally than in the case where the retrotransmissive element 13 has a planar shape. For this reason, the observer can see a virtual image with a wide visual field.

As the curved surface in this case, it is possible to use a spherical surface, a rotating hyperboloid, a paraboloid, or the like that easily obtains optical conjugation between the exit pupil of the projector 20 and the human pupil. The curved surface of the present embodiment has an effect of moving the focal position distally (distantly). For this reason, in order to suppress the disturbance of the imaging, it is preferable that the curvature of the curved surface is uniform in the distribution region of the light bundle that constitutes the pixel and is incident on the observer's pupil.

Thus, since both the transparent solid layer 30 and the semi-reflective layer 40 of the retrotransmissive element 13 are curved along the same direction, some of the light rays that have passed through the semi-reflective layer 40 are retroreflective element 32. When the light is retroreflected, the retroreflected light beam is reflected by the reflecting surface (concave mirror), passes through the transparent solid layer 30, and is emitted from the retrotransmissive element 13 toward the observation viewpoint A. The

For this reason, the focal position of the virtual image formed by passing the unreal image (light bundle) incident on the retrotransmissive element 13 through the surface opposite to the incident surface can be moved distally. Therefore, a wide visual field can be obtained.

(Seventh embodiment)
Next, a seventh embodiment of the present invention will be described with reference to FIG. This embodiment embodies claim 7. Also in this embodiment, the transparent solid layer 30 and the semi-reflective layer 40 of the retrotransmissive element 13 described in FIGS. 5A, 5B, 6A, and 6B are both curved. Yes.

As the curved surface in this case, it is possible to use a spherical surface, a rotating hyperboloid, a paraboloid, or the like that easily obtains optical conjugation between the exit pupil of the projector 20 and the human pupil. The curved surface of this embodiment has the effect of moving the focal position far away. For this reason, it is preferable to make the curvature of the curved surface uniform from the viewpoint of not disturbing the image formation in the distribution region of the light bundle that constitutes the pixel and enters the pupil of the observer.

As shown in FIG. 11B, the retrotransmissive element 13 is arranged with the transparent solid layer 30 facing the projector 20. The retrotransmissive element 13 has the semi-reflective layer 40 and the transparent solid layer 30 curved in a convex shape toward the projector 20. For this reason, the reflective surface of the semi-reflective layer 40 is formed as a convex mirror. In the present embodiment, the optical system is formed with the convex surface of the retrotransmissive element 13 facing the projector 20.

In this case, the light beam incident on the transparent solid layer 30 from the projector 20 is reflected by the reflective surface of the semi-reflective layer 40 that is a convex mirror, and then retroreflected by the retroreflective element 32. A part of the retroreflected light beam passes through the semi-reflective layer 40 and is emitted from the retrotransmissive element 13 toward the observation viewpoint A.

Since the focal point of the virtual image is moved far away by this convex mirror function, the observer can see the virtual image in a wide field of view.
(Eighth embodiment)
Next, an eighth embodiment of the present invention will be described with reference to FIGS. 14 (a) and 14 (b). Here, the optical system of the present invention is embodied in a head-mounted projector.

As shown in FIG. 14A, the head-mounted projector 100 is provided on the spectacle frame 110. The eyeglass frame 110 includes a pair of rims 112 that support the pair of retro-transmissive elements 13, a bridge 114 that connects the rims 112, and a temple 118 that is attached to the rim 112 via a hinge 116. A projector 20 is attached to each rim 112 via a bracket 120. The projector 20 is disposed in front of the rim 12 (direction seen by the observer). The projector 20 is disposed at a position optically conjugate with the observation viewpoint A of the observer with respect to the retrotransmissive element 13. Further, as shown in FIG. 14B, the projector 20 is disposed outside the visual field of the observer when viewed from the observation viewpoint A. In the retrotransmissive element 13 of the present embodiment, the same configuration as that of the sixth embodiment is adopted, but the same configuration as that of the seventh embodiment may be adopted, or other than the sixth and seventh embodiments. You may employ | adopt the structure of embodiment.

The head-mounted projector includes a spectacle frame 110 attached to the user's head as a support. The optical system is supported on the spectacle frame 110. The retrotransmissive element 13 is arranged on the eyeglass frame 110 (support) so that a virtual image by the retroreflective light can be visually recognized by the user. As a result, the head-mounted projector 100 can eliminate the need for a screen by performing virtual image conversion in spite of using a projector for forming a real image.

In addition, you may change each said embodiment as follows.
In the embodiment shown in FIG. 5A, a corner cube prism is provided as the retroreflective element 32 on the surface of the transparent solid layer 30 of the retrotransmissive element 13. Instead, a plurality of glass beads may be discretely formed on the transparent solid layer 30 as shown in FIG. In this case, part of the glass beads is embedded in the transparent solid layer 30. In this case, the refractive index of the glass beads is preferably a high optical refractive index of about 2. A coating layer 33 is formed on the outer surface of the glass beads. The coating layer 33 is formed by vapor-depositing a metal thin film made of the same material as the metal thin film formed on the outer surface of the corner cube. In this case as well, the glass beads retroreflect light rays as in the corner cube.

As shown in FIG. 6A, the entire corner cube prism may be embedded in the transparent solid layer 30. Further, as shown in FIG. 6B, the entire glass beads may be embedded in the transparent solid layer 30.

4 and 5, as shown in FIG. 4C, a retrotransmissive element 13 in which the transparent solid layer 30 is omitted may be used. Specifically, the retroreflective elements 32 are supported in a state where the retroreflective elements 32 are discretely arranged by a lattice-like or net-like support member 70. Further, a gap layer 65 as a transparent layer is provided between the retroreflective element 32 and the semi-reflective layer 40 (beam splitter). In this case, an interval holding member 80 is provided between the support member 70 and the semi-reflective layer 40 to ensure an appropriate interval therebetween. Thereby, a gap layer 65 is formed between the retroreflective element 32 and the semi-reflective layer 40.

In the embodiment shown in FIG. 7, the cross-sectional shape of the through hole 42 is a right triangle. However, if a corner mirror is formed on the inner surface of the through hole, the cross-sectional shape of the through hole 42 is a square cross section or a multi-section cross section. You may change to a square. In short, the cross-sectional shape of the through hole 42 may be a cross-sectional shape in which at least two mirror surfaces are orthogonal to each other.

In the embodiment shown in FIG. 7, a hole (bore) blocking the first opening end of the through hole 42 is used instead of the through hole 42 as a gap in the element body 41, or both open ends of the through hole 42 are formed. It may be closed with a transparent plate. In either case, since the corner mirror is formed on the wall surface surrounding the gap, the same effects as in FIG.

In the sixth embodiment, the retrotransmissive element 13 is curved in order to obtain a wide field of view. However, in order to obtain a narrow field of view, the retrotransmissive element 13 may be curved in the opposite direction to FIG. . In this case, the focal position of the virtual image is moved proximally with respect to the retrotransmissive element 13 as compared with the flat retrotransparent element 13. For this reason, a virtual image can be enlarged. Specifically, the retrotransmissive element 13 is arranged with the semi-reflective layer 40 facing the projector 20, and the semi-reflective layer 40 and the transparent solid layer 30 are curved in a convex shape toward the observation viewpoint A. Yes. As a result, the reflective surface (mirror surface) of the semi-reflective layer 40 functions as a convex mirror.

In the seventh embodiment, the retrotransmissive element 13 is curved in order to obtain a wide field of view. However, in order to obtain a narrow field of view, the retrotransmissive element 13 may be curved in the direction opposite to that in FIG. . Also in this case, the focal position of the virtual image is moved proximally with respect to the retrotransmissive element 13 as compared with the flat retrotransmissive element 13. For this reason, a virtual image can be enlarged. Specifically, the retrotransmissive element 13 is arranged with the transparent solid layer 30 facing the projector 20 and curved in a convex shape with the semi-reflective layer 40 and the transparent solid layer 30 facing the observation viewpoint A. ing. As a result, the reflective surface (mirror surface) of the semi-reflective layer 40 functions as a concave mirror.

In the sixth and seventh embodiments, as shown in FIG. 13, the mirror may be further miniaturized using a Fresnel reflecting mirror (Fresnel semi-transmissive mirror 90). In this case, according to the fine structure, the physical shape and the optical shape can be considered separately. For this reason, the freedom degree of design improves. That is, instead of using the semi-reflective layer 40 as a curved mirror as shown in FIGS. 11A and 11B, a Fresnel semi-transmissive mirror 90 is used as a semi-reflective layer (beam splitter) as shown in FIG. it can. In this case, the same optical effect as when the semi-reflective layer 40 is curved, that is, the spread or convergence of light rays can be obtained. The Fresnel semi-transmissive mirror 90 is formed with a plurality of miniaturized annular zone surfaces 90a. For this reason, the Fresnel semi-transmission mirror 90 has a retro-transmission axis G that faces in different directions on each annular surface 90a.

In the third embodiment shown in FIG. 7 and FIG. 8, as shown in FIG. 12A, the intersection line (recursive transmission axis G) of each corner mirror 43 is arranged so as to be orthogonal to the plane of the element body 41. ing. In this case, like the plane mirror, the space is simply folded as shown by the arrow in FIG. The retrotransmissive element 13 shown in FIGS. 12A to 12C is simply indicated by a straight line or a curve for convenience of explanation.

In the third embodiment, an element body 41 having a curved surface may be used instead of the flat element body 41. As the curved surface in this case, a spherical surface, a rotating hyperboloid, a paraboloid, or the like that can easily obtain optical conjugation between the exit pupil of the projector 20 and the human pupil can be used. As a result, as shown in FIG. 12B, for example, when the element body 41 has the spherical surface U, the light rays from the outside are reflected by the spherical surface U along the retrotransmission axis G perpendicular to the spherical surface U. It has an optical path. Similarly, the light beam from the inside (from the lower side of FIG. 12B) has an optical path as reflected by the spherical surface U.

As described above, the plurality of corner mirrors 43 (corner mirror array) arranged along the curved surface and having the retro-transmission axis G perpendicular to the curved surface allows the light rays incident on the retro-transmission element 13 to pass through the thickness of the retro-transmission element 13. It is made to pass in the direction and to the surface opposite to the incident surface. From this point, the corner mirror 43 does not change the traveling direction of the incident light. However, the traveling direction of the light beam in this case is opposite to that of the curved mirror. The arrow indicated by the dotted line in FIG. 12B indicates the traveling direction of the light beam in the case of the curved mirror, that is, the reflection direction of the light beam reflected by the curved surface.

Further, although not shown in FIG. 12C, the retrotransmissive element 13 is not shown in FIG. 12C, even if the incident surface of the retrotransmissive element 13 is a plane or a curved surface. The direction of the axis G may be set to an arbitrary direction. In this case, like the Fresnel lens and the reflecting mirror, the physical shape and the shape in the optical sense can be considered separately.

In the eighth embodiment, the present invention is embodied in the spectacle frame 110 as a support for supporting the optical system, but may be embodied in a helmet or the like, for example. In this case, the retrotransmissive element 13 and the projector 20 are attached to the helmet. In addition to the helmet, the present invention may be embodied in a member attached to the head such as a headgear or a headband.

Claims

A projector,
A retro-transmissive element disposed opposite to the projector, wherein when incident light is transmitted through a surface opposite to the incident surface of the retro-transmissive element, the direction of the light is symmetric with respect to the retro-transmission axis. With retro-transparent elements to change and inject,
An optical system characterized in that an image is formed by retroreflecting incident light of an unreal image projected from the projector through the retrotransmissive element.
The optical system according to claim 1, wherein the retrotransmissive element is curved.
The optical system according to claim 1 or 2 is provided on a support body to be mounted on a user's head,
A head-mounted projector, wherein the retrotransmissive element is disposed on the support so that the user can visually recognize a virtual image by the retrotransmissive light.
A transparent layer,
A first surface of the transparent layer, or a semi-reflective layer provided inside the transparent layer;
A second surface opposite to the first surface of the transparent layer, or a plurality of retroreflective elements provided inside the transparent layer and reflecting light rays toward the semi-reflective layer;
The retrotransmissive element is characterized in that the retroreflective elements are discretely arranged.
The retrotransmissive element according to claim 4, wherein the semi-reflective layer is curved.
The semi-reflective layer is curved in a concave shape, and the reflective surface of the semi-reflective layer is formed as a concave mirror;
The light beam reflected by the retroreflective element after passing through the semi-reflective layer is reflected by the reflective surface, passes through the transparent layer, and is emitted to the outside. Transparent element.
The semi-reflective layer is curved into a convex shape, and the reflective surface of the semi-reflective layer is formed as a convex mirror;
The light beam incident on the transparent layer is reflected by the reflective surface, further reflected by the retroreflective element, passes through the semi-reflective layer, and is emitted to the outside. Transparent element.
In the plate-shaped element body, a plurality of voids are formed in a dotted line shape and a circular shape, and a plurality of void groups are concentrically arranged, and the wall surface of the void is a mirror surface. A retrotransparent element characterized by being.
A plurality of circular gaps having different diameters are formed concentrically with respect to the plate-shaped element body, the wall surface of the gap is a mirror surface, and the gap has a pair of opening ends that open on both sides of the element body. And at least one of the open ends is closed.
The retrotransmissive element according to claim 8, wherein the void is a through hole.
In the plate-shaped element body, a plurality of gaps extending in the thickness direction of the element body are randomly arranged,
A two-surface orthogonal mirror is formed on the inner surface of the gap, and the two-surface orthogonal mirror is composed of a first mirror surface and a second mirror surface that are orthogonal to each other, and the line of intersection between the first mirror surface and the second mirror surface is A retrotransmissible element, which is disposed along the thickness direction of the element body.
The retrotransmissive element according to claim 11, wherein the void is a through hole.
The retrotransmissivity according to claim 11 or 12, wherein the element body has a curved surface, and an intersecting line of the two-plane orthogonal alignment mirrors is arranged along a normal direction of the curved surface. element.
The two-plane orthogonal mirror is disposed in the element body, and the retrotransmission axis is set according to the location, so that in addition to the retrotransmission, optical characteristics of light spreading or convergence are added. The retrotransparent element according to any one of claims 11 to 13.