WO1982000911A1

WO1982000911A1 - Real image projection device

Info

Publication number: WO1982000911A1
Application number: PCT/NL1981/000020
Authority: WO
Inventors: M Kassies
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-08-29
Filing date: 1981-08-12
Publication date: 1982-03-18
Anticipated expiration: 1983-02-28
Also published as: MX152353A; IT8149184A0; CA1163481A; ZA815690B; AU7536581A; EP0065954A1; BE890123A; IT1143424B

Abstract

La lumiere reflechie ou emanant d'un objet est projetee au travers d'un dispositif a image symetrique. Le dispositif a image symetrique contient un plan de reference (24, 60, 65) ou la direction de la lumiere venant heurter ce plan de reference est changee ou modifiee. Le dispositif a image symetrique par rapport au plan de reference ou de symetrie possede des proprietes optiques (20, 43, 45) limitant le rayon transmis par le dispositif a image symetrique pour rester dans un plan normal contenant le rayon incident et la normale au plan de reference au point d'incidence. L'angle d'incidence est egal a l'angle de transmission, mais il est contenu du meme cote de la normale (ou l'angle d'incidence est l'angle entre le rayon de lumiere incident et la normale, l'angle de transmission est l'angle entre le rayon de lumiere reflechi et la normale). En ce qui concerne l'aspect de retro-reflexion de cette invention, chaque rayon de lumiere est reflechi exactement sur lui-meme avant ou apres reflexion speculaire de ce rayon de lumiere par un milieu partiellement transparent dont la surface coincide generalement avec le plan de reference susmentionne. En ce qui concerne la forme de deflexion de la lumiere de l'invention qui utilise soit la deflexion soit la reflexion soit une combinaison de ces aspects de transmission, le dispositif possede une forme plane (108, 110) plutot qu'une forme de boite et la lumiere provenant d'un objet d'un cote du dispositif est projetee sur le cote oppose du dispositif plutot que lateralement par rapport au dispositif dans les deux cas. Dans l'un ou l'autre des cas, la lumiere projetee par le dispositif forme des images d'objets dans l'espace. Dans le cas d'un dispositif a retro-reflexion, la lumiere doit etre deviee par un diviseur de rayons, pour produire une image symetrique capable d'avoir des qualites dimensionnelles.The light reflected or emanating from an object is projected through a symmetrical image device. The symmetrical image device contains a reference plane (24, 60, 65) where the direction of the light striking this reference plane is changed or modified. The image device symmetrical with respect to the reference or symmetry plane has optical properties (20, 43, 45) limiting the radius transmitted by the image symmetric device to remain in a normal plane containing the incident ray and the normal to the plane of reference at the point of incidence. The angle of incidence is equal to the angle of transmission, but it is contained on the same side of the normal (where the angle of incidence is the angle between the ray of incident light and the normal, the angle transmission angle is the angle between the reflected ray of light and normal). With regard to the retro-reflection aspect of this invention, each ray of light is reflected exactly on itself before or after specular reflection of this ray of light by a partially transparent medium whose surface generally coincides with the plane of reference above. Regarding the form of deflection of the light of the invention which uses either deflection or reflection or a combination of these transmission aspects, the device has a planar shape (108, 110) rather than a box shape and the light coming from an object on one side of the device is projected on the opposite side of the device rather than laterally with respect to the device in both cases. In either case, the light projected by the device forms images of objects in space. In the case of a retro-reflection device, the light must be deflected by a ray divider, to produce a symmetrical image capable of having dimensional qualities.

Description

REAL IMAGE PRO JECTION DEVICE .

An objact of this invention is to disclose the projaction of an image utilizing the raflected light from an objact such as that seen in the real world. According to this aspect of the invention, the object is conventionally illuminated, for example either by front illumination in the case of an opaque object or by rear illumination in the case of a translucent object. Light from the object is projected through a symmetrical imaging device. The symmetrical imaging device has a reference plane where light incident upon the device has its direction changed and the light with changed direction is transmitted from the device. All points on the reference plane are active over the surface of the reference plane in accordance with the following rule.

The symmetrical imaging device relative to the reference plane has optical properties restricting the transmitted ray from the symme trical imaging device to a normal plane containing the incident ray and the normal to the reference plane to the point of iπoidanca. The angle of incidence is equal to the angle of transmission but is contained an tne same side of the normal (where the angle of incidence is the angle between the incident light ray and a normal and the angle of transmission is the angle between the reflected light ray and a normal).

Images from objects projected further apart from the device than the object versus distance to the device will also become visible and appear to be reversed left-right and upsidedown.

Other than for viewing or projecting images, the devices can be used for the multiple functions usually performed by lenses and parabolic mirrors.

A further object o f this inventions is to disclose a screen far transmitting from one side of the screen an image of an object to the opposite side of the screen. This is previously called the deflective form of the device. In this aspect of the invention, the image from the device is a precise reciprocal of the object of the device. for example, an image of what is essentially a convex human contour would appear reciprocally as an image of a concave human contour.

An advantage of this invention is that tha image, unlike that proαduced through a positive spherical lens or parabolic mirror, is at the same distance from the retroimaging device as the object whan the refaranca plans is reflected.

Thus, by increasing the distance of the object from the retroimaging device, one can increase the distance from the image and retroimaging device, For example, utilizing this invention a three-dimensional reciprocal image of an object can be easily cast out into the street through a storafront window.

A further advantage is that by using reciprocal objects, one can cast an image of a real world object. For example, by imaging the concave features of the human mask, one can image with reverse parity the exterior of a human face.

A further function of one part of this invention is to adopt a beam splitter to a retroreflecting screen to the casting of such images. According to this aspect of the invention, the beam splitter is placed at an angle between an illuminated object and a retroreflecting screen. Light imainging upon the beam splitter from the retroreflecting screen is detoured outwardly and away from the screen path back to the object. Being so detoured, a reciprocal image is formed. The formed reciprocal image may then be viewed as being real, and out in space in front of the viewer.

Other objects, features and advantages at this invention will become more apparent after referring to the following specification and attached drawings;

Fig. 1 is a three-dimensional view of the projection device in this invention utilizing a retroreflecting screen and beam splitter to create a specular reciprocal image of the letters "ABC";

fig. 2 is a side perspective view of fig. 1 illustrating the property of the invention whereby the image is thrown some distance from the projection device; fig. 3 is an embodiment of this invention si.milar to fig. 1, the embodiment therein illustrating a retroprojection device, which retroprojection device throws the reciprocal of the letters to a new location;

figs. 4, 5, 6. are all embodiments of specialized screens which can be used with the embodiment of fig. 3;

fig. 7 is an embodiment of the invention wherein two symmetrical imaging devices ara used so as to project the image of the object (leftmost face) into space so that the image (rightmost face) appears the same as the object.

Referring to fig. 1, an object 100 is illuminated by a light source 99 which light source is only schematically shown. In the view of fig.1, the object happens to be transparent or translucent. The light thus can be projected from the rear thereof.

Referring to the view of fig, 2, the light from the object passes to a retroreflecting screen 20 mounted an the base of a three-sided box 22. Light from the retroreflecting screen returns directly to the object 100. As those having skill in the art know , a retroreflecting screen returns the light, impinging upon it with the precise angularity as the light is received from an object. Thus, and assuming no beam splitter 24 intermediate the object 100 and retroreflecting screen 20, one would expect that the light would reflect back upon and enhance precisely with a real image the real world object 100. Interposition of the beam splitter 24 at a preferred 45 degree angle changes this. Specifically, the beam splitter causes at least some of the converging light to be detoured to an image plans 101. At the image plane 101 the image of the object (here shown as the letters "ABC") is recreated. As the image is recreated, a viewer having a perspective from a solid angle of projection equal to the solid angle of projection of the retroreflecting screen and the beam splitter can see the letters ABC projected in space. In actual fact, the retroreflecting screen could be mounted on the and wall 25 of the box 22. However, in this location a viewer of the imaga 101 such as that schematically shown by the eye 30 would in fig. 2 have a bright and illuminated back - ground against which to view the image. As a bright and illuminated background would detract from the intensity of the image it is usually preferred to mount the retroreflecting screen 20 so that the viewer has light passed to his view with a relatively dark background. Typically end wall 25 is painted with a dark, light absorbative coating such as non-glossy black paint and the like. It is also important to distinguish this invention from that of the conventional law of reflection. Taking the case of a retroimaging screen, it will be understood that the screen has a theoretical reference plane in which light changes its direction. This screen has optical properties restricting the transmitting ray to the retroreflecting screen to a normal plane containing the incident ray and the normal to the reference plane within the screen at the point of incidence. The angle of incident is equal to the angle of transmission, but is contained an the same side of the normal. The angle of incidence is defined as the angle between the incident light ray and a normal and the angle of transmission or reflection is defined as the angle between the reflected ray and a normal.

It is important to distinguish this projection system from that of a conventional lens. Specifically, in the case of a lens, a reciprocal image moves, Whera the object is far away, the image moves to the focal point of the lens. Conversely, where tine objact approaches the focal length of the lens, the image is projected at increasing distances. A reciprocal relationship results. Here, between the image and the object there is a direct relationship. Specifically, the relationship is that the object to symmetry imaging device distance will always ramain the same as the image to symmetry imaging device distance.When the symmetry of plane is chosen to be nonreflecting, e.g. by use of curved beam splitter, or by use of a curved rear deflector, the image will be deformed according to the same rules of symmetry. This latter rule produces on images some effects which are nor immediately apparent. Take, for instance, the image of a human face. Typically, the nose of a human face will be closer to the projection screen than the ears of the human face. The projection of a reciprocal imaga will give an αpposita result. Specifically, the human imaga will have the nose clαsar to the projection device than the ears. Thus, images projected by the device will be reciprocal. It will be as if one is viewing a mask from the inside. An expedient to correct this reversal of distance parity is to utilize for the object a mask. Thereafter, the projected image will be a real life image.

As will hereinafter be briefly discussed, and in the case of stereoscopic projection, it is necessary to reverse the right-left parity to prevent pseudoscopic images.

Having discussed an embodiment of this invention utilizing a retroreflecting screen, attention now can be given to the projection of an image using rstroprojsction devices such as illustrated in Figs. 4, 5 and 6. This will first be αiscussad with respect to Fig. 3.

Referring to Fig. 3, a light source 103 illuminates an object in the farm of letters ABC deflective is a projection. A device 104 is illustrated. The property of device 104 is exactly similar to that of the retroreflecting screen 20. Specifically, reflected or emanating light will diverge from each point on object

(letters ABC). It will impinge upon the screen device 104. Light will be projected from the screen device 104, converging to an image 105 of the letters ABC in the same, exact and identical angularity as light projected from the letters ABC onto the screen device 104. There results projected in space a reciprocal image of letters ABC.

The construction of the projection device 104 can take several forms, which forms can all ba easily understood with reference to Figs. 4, 3, and 5,

Referring to Fig. 4, a device 106 is shown consisting of glass bead lenses 40 aligned in a matrix 41 in one side of screen 50 and glass bead lenses 50 aligned in a matrix 51 an the opposite side af screen 50. A rear projection screen 50 sits intermediate the lens matrixes 41, 51. The resulting projection system is easy to understand. Specifically, light from all angles is imaged through matrix 41 onto the rear projection screen 60. At the rear projection screen 60, the light is then seen by the matrix of lenses 51 and each individual lens 50 causes light to emanate from the rear side of the rear projection screen 60 with the exact same and precise angularity as the light was received. There will result a recreation of the images as described. The same effect can be produced using pinholes. A device utilizing pinholes is illustrated in Fig. 5.

In Fig. 5, a rear projection screen 60 is shown having a series of individual pinhαlas 42 aligned in a matrix 43. Conversely and at the opposite side there are pinholes 52 aligned in a matrix 53. The result is the same. Specifically, light enters and forms an image on the rear projection screen 50. This image is seen at each of the pinholes with the light exiting through the pinholes. The angularity assigned to an outgoing ray is the reciprocal of the light to an incoming ray. Therefore, an image can be formed in themanner illustrated in Fig. 3.

It will ba apparent that if matrixes differ in size, enlargement is possible. Therefore, it is mentioned that the idea must be interpreted as wide as possible.

Referring to Fig. 5, yet another emodiment is illustrated. In particualar, a matrix of positive spherical lenses 51 is illustrated, each lens is aligned between paired pinholes 44 towards the object and 54 towards the image. As before, these respective lenses 61, pinholes 44, 54 are aligned in respective matrixes, 45, 55. It will be seen that the separation between the matrix of pinholes 45 and the matrix of pinholes 55 is chosen to be the exact focal length of each of the lenses 61 of the lens matrix 65. With this property, the light rays pass along the illustrated path and each entering light ray enters with an angle equal and opposite to each exiting lignt ray. Again, the screen illustrated in Fig. 5 will produce a symmetry imaging characteristic such as that previously illustrated. Reviewing the device of Figs. 4, 5 and 5, again it can be seen how the generic definition of symmetrical imaging devices aptly describe their function. Each device has a plane where the light changes direction. The symmetrical imaging device relative to its reference plane has optical properties restricting the transmitted ray from the symmetrical imaging device to a normal plans containing the incident ray and the normal to the reference plane at the point of the incidence. The angle of incidence is equal to tha angle of transmission, but is contained on tha same side of the normal. The angle of incidence is the angle between the incident light ray and the normal and the angle of transmission is the angle between the transmitted ray and a normal, Where transmission of a light image of the object occurs from one sids of the device to the opposite side of the device, it will be seen that there results an image. It will be seen and realized that the images created are not those conventionally created by spherical lenses. Plαreαver, the imaga is to ba distinguished frcm any illuminated object merely placed in front of a retroreflecting screen, where an illuminated object is placed in front of a retroreflecting screen, an imags of that object is cast right back precisely upon the object itself. Here and in this invention, the image of the object must be cast somewhere other than back upon the αbjact itself. It is the realization that the image exists that is one of the important aspects of this invention.

Referring to Fig. 7, a symmetrical imaging device for transmitting an image is shown. An object 107, hers in the form af the human face, is placed on one side of a first transmission device 108. It casts a reciprocal image in the form of a mask 109 on the opposite side thereof. The image of mask 109 is then taken by a second image transmission device 110. This image transmission device forms an image of the human face at 111. It can ba seen that with the above- described reciprocal imaging device, the device of the face may be reproduced. It is seen that as the object 107 is moved toward the right the imaga 111 will also move toward the right. Further, both object and image will move at the same speed.

I have just finished illustrating with respect to Fig. 7 two symmetrical imaging devices wherein an image from an object on one side of the device is relayed to the opposite side. This image is in turn re-relayed by a second symmetrical imaging device to produce a real parity image. Those having skill in the art will realize that the retroreflecting scheme that I have illustrated with respect to Figs. 1 and 2 could as wall be used twice to restore parity to the image.

It will be apparent to those that the invention contained herein is limited only by the following claims.

Claims

1. A symmetrical imaging device for imaging an illuminated object at a preselected distance from said imaging device, said symmetrical imaging device comprising optic material (20, 43, 45) an at least One side of a reference plane (24, 50, 55) for deflecting light fram a matrix of points on said reference plane, said optic material disposed to change direction of light incident upon said material relative to light transmitted from said material, said change of direction occuring at a reference plane (24, 50, 65); means in said optical material (20, 43, 53) far transmitting rays from said reference plans (24, 50, 65), so that rays are contained within a normal plane having the incident ray and a normal to the reference plane and the angle of incidence relative to said reference plane is equal to the angle of transmission relative to said reference plane (24, 50, 65) but is contained an the same side of the normal; means for imaging said image at a place other than said object.

2. The invention of claim 1 and wherein said symmetrical imaging devica comprises a retroreflector (20) and wherein there is disposed between said retroimaging device and object means for deflecting portion of the light being transmitted from said symmetrical imaging device to a location other than on said object for imaging said light.

3. Apparatus for projecting an image of an object comprising in combination an object; a symmetrical imaging device for receiving natural light from said object, said symmetrcial imaging device including a plane (24, 50, 65) having optical material (20, 43, 53) an at least one side thereof; said optical material arranged and disposed with respect to said reference plane for causing the direction of the transmitted ray to change direction at said reference plane relative to an incident ray the direction ofsaid transmitted ray relative to said incident ray passing in a normal plans containing the incident ray relative to said reference plane with the angle of incidence equal tα the angle of transmission but with both angles being on the same side of the normal; and means for projecting an image at a place other than the object.

4. The invention of claim 3 and wherein said projecting means includes a beam splitter (24).

5. The invention of claim 3 and wherein said projecting means includes optical material on the opposite side (25) of said reference plane.

6. A method for projecting an image of an object utilizing natural light emanating from said object, said method comprising the steps of receiving said natural light rays at a reference plane at a preselected distance from said object; changing the direction of said rays at said reference plane, said rays having said direction changed so that a plane normal to said reference plane contains the incident ray and the normal to the reference plane and the transmitted ray, the angle of said incident ray being equal to the angle of said transmitted ray but on the same side of the normal; permitting said transmitted ray is to form an image at a distance equal to distance of said object from said plane; and means for forming an image of said object at a place other than on said object.

7. The invention of claim 6 and wherein said symmetrical imaging device constitutes a retroreflecting screen (20, 43, 33) and a beam splitter.

3. The invention of claim and wherein said means for forming an image at a place other than said object includes an optical coating (41,45) on sides of the reference plans (50,55).