WO2007101670A1 - Method and arrangement for spatial representation using a holographic projection screen - Google Patents

Abstract

The invention relates to a method for the spatial representation of a scene for at least one observer (3), according to which a plurality of views of a scene are imaged onto a holographic projection screen (2), each view being imaged onto the holographic projection screen (2) in an imaging direction which is different from the imaging directions for the other views. Light hitting the holographic projection screen (2) is diffracted according to the imaging directions such that an observer (3) perceives different quantities of views respectively with the left eye and the right eye and a spatial impression is created. The invention also relates to a corresponding arrangement characterised in that, for each view, the diffracted light is radiated in a plurality of first-order diffraction corridors in respectively median radiation directions according to the imaging direction, diffraction images in the form of diffraction fringes extending essentially parallel to each other are produced in a plane parallel to the projection screen (2), at a pre-defined observation distance, and between two diffraction fringes associated with a view, a diffraction fringe of each of the other views is produced.

Description

PROCEDURE AND ARRANGEMENT FOR SPATIAL DISPLAY WITH HOLOGRAPHIC PROJECTION SCREEN

The invention relates to a method for the spatial representation of a scene for one or more observers, in which a plurality of views of the scene are imaged on a holographic projection screen, wherein each of the views in the one imaging direction, which is different from the imaging directions for the other views, on the Holographic Projektioπsschirm is mapped, and the holographic projection screen incident light is diffracted depending on the imaging directions, so that a viewer with the left and right eye each perceive different sets of views and creates a spatial impression.

The invention also relates to an arrangement for spatial representation of a scene for one or more observers, which comprises a holographic Projektioπsschirm, and an imaging optics, with the several views of the scene are mapped onto the Projektioπsschirm, each of the views in a Bildjurung, the is different from the imaging directions for the other views, is projected onto the projection screen, and wherein the projection screen diffracts incident light depending on the imaging directions, so that a viewer with the left and right eyes respectively perceives different sets of views and creates a spatial impression ,

The invention relates to the problem of spatial representation by means of a holographic projection screen for a plurality of viewers.

Autostereoscopic display methods and arrangements based on holographic projection systems have been known for some time in the prior art. So

For example, US Pat. No. 4,799,739 discloses a holographic projection screen in which different views of different horizontally offset projectors are imaged onto a holographic optical element (HOE). The HOE diffracts a diffraction strip in a viewing space for each of the views. With appropriate arrangement of the projectors, these diffraction strips all adjoin one another. The width of the strips can be adjusted so that a viewer located at a given viewing distance sees with one eye a different view than with the other eye. Each of the diffraction strips appears exactly once, with the width of the strips depending on the number of projectors used and the width of the screen on which they are to be displayed. If only a few projectors are used, the three-dimensional impression will only appear in a few places in the viewing area. However, the use of many projectors is not least a question of cost.

WO 82/04327 describes an arrangement in which information from a focal plane with a lens is imaged via a HOE into the pupil of a viewer. The HOE is designed so that it deflects the light from any position of the HOE in the pupil of a view. Depending on the angle of incidence, the incoming rays are therefore diffracted differently with respect to their direction, whereby the rays impinging at a larger angle of incidence are deflected more strongly, so that a viewer can position himself as uninfluenced by the zeroth, undeflected order and still perceives a bright image

The object of the present invention is to develop a method and an arrangement using a holographic projection screen, which simultaneously allow multiple viewers in a viewing space as large as possible to perceive a three-dimensional representation, wherein the views to be displayed a scene with the highest possible brightness and highest possible Resolution to be displayed.

This object is achieved in a method of the type described above in that for each view, the diffracted light is emitted into a plurality of diffraction corridors of the first order, each with average radiation directions depending on the imaging direction, and in a plane parallel to the projection screen at a predetermined viewing distance diffraction images in Form of substantially parallel to each other Beuguπgleisten be generated, wherein between two diffraction strips associated with a view are generated one diffraction strip of each of the other views

Thus, when the views are projected onto the projection screen as a real image by a projector, even though the real image of the view occupies the entire screen, a viewer sees this view as a virtual image only in a small strip. These stripes are repeated at a distance When one uses n views, where n is a natural number, the distance between two first order diffraction fringes for the same view - measured from the center of the strip - is n times the stripe width

The diffracted light is emitted by the screen into several first-order diffraction corridors. These boundary surfaces of the corridors generally do not run parallel to one another, but open at more or less narrow angles, the aperture angles depending on the viewing distance, in particular to the longitudinal sides of the diffraction strips is radiated in a corridor thus in dependence on the Bildπππππτπι in many directions, which give the diffraction corridor in their entirety, wherein the average emission direction is the averaged over all directions Abstrahlπchtung

The substantially parallel strips arise when using a diffraction grating-based projection screen from the superposition of many individual diffraction streaks, some of which may also have a slight curvature, but on average for a viewer is no longer or barely perceptible

The diffraction strips preferably extend in the vertical direction substantially parallel to one another, so that a standing or seated observer does not need to turn the head in order to obtain a three-dimensional impression. Preferably, the width of the strips is - which, of course, because the diffraction corridors have a certain opening angle 65 mm, which is the average pupillary distance of a human As a viewing distance for a larger projection screen that allows multiple viewers a good perception, for example, a viewing distance of 2 to 4 m as needed the viewing distances can also be smaller, z 8 for individual workstations with a computer Bildschirrn or even larger, such as in Ktno The stripes are usually shown side by side, but since the brightness drops in a stiffener towards its edges, overlap tπ a Favor th variant, the strip something to allow a viewer a more pleasant transition between two views in a horizontal movement

For each view, the imaging direction with the flat normal of the projection screen in a plane perpendicular to the projection screen and parallel to the longitudinal direction of the diffraction strips preferably includes a non-zero diffraction or projection angle φ. This has the advantage that the zeroth undeflected and very bright order, or the real image of the viewer is not disturbing wahrgenommer ». The term "imaging direction" should be understood to mean the direction corresponding to the optical axis of the beam path for a view to be imaged, or the axis connecting the center of a projection objective to the center of the holographic projection screen corresponds to the emission directions, of which there are several for each view The emission direction must not be in the plane of the beam because it is also perpendicular to the projection screen. However, it does have a component in the plane of the beam. The component lying in the plane of the beam preferably stands in this case the emission direction perpendicular to the projection screen This has the advantage that a projection screen can be easily aligned, because it can be placed in a viewing room, for example, as a conventional Juckpro- jektionsgerat course are also other Abstrahl πchtu conceivable in which the component lying in the beam plane is slightly tilted downwards or upwards, this is advantageous, for example, when the projection screen is mounted above or below the average viewing height - eg the average height of the viewer

Abbildπchtung and flat normal of the projection screen include in the beam plane preferably a diffraction angle φ between 10 'and 80', preferably 37 'extreme angles are possible under certain circumstances The smaller the diffraction angle, the more disturbing is the real image of the zeroth unflexed order notice bar, the larger the angle, the lower the brightness In practice, an angle between 20 ^' and 60', preferably 37 "proved to be a good compromise Especially when using multiple projectors, however, a restriction to only one angle is hardly possible Since the projection screen is a diffraction grating, the focal length for the strips depends on the wavelength. For long-wave radiation, the distance between the diffraction strips and the projection screen is shorter than for short-wave radiation. Therefore, the views are preferably linearly varying with superposition views then, instead of the original views, the overlay views are mapped - superimposed so as to correct a color blur error of the projection screen for a given viewing distance. In all other viewing distances, however, this error will still be noticeable. For example, is a viewer aware of the wavelength Green given, correct viewing distance, so he sees the green portion of the image over the entire width of the projection screen The blue and the red portion of the displayed image can be seen in each case only in a smaller width the observer therefore sees these two colors as an image which is composed of several views shifted by the linearly varying superimposition to overlay views. which are ultimately displayed, the color error can be corrected at least for a viewing distance

The object is achieved with respect to an arrangement of the type described above in that the holographic projection screen has at least one diffraction grating such that for each view the diffracted light is emitted into a plurality of diffraction corridors of the first order, each with medium radiation directions depending on the imaging direction so that in a plane parallel to the projection screen »plane diffraction images are generated in the form of substantially parallel to each other Seυgungsstreifen, wherein between two a view associated diffraction strips depending on a diffraction diffraction FEN each of the other views are generated

Thus, when the views are projected onto the projection screen as a real image by a projector, even though the real image of the view occupies the entire screen, a viewer sees this view as a virtual image only in a small strip. These stripes are repeated at a distance Depending on the number of views to be projected Using π views, where π is a natural number, the distance between two first-order diffraction fringes for the same view - measured from the center of the strip - is n times the stripe width The boundary light of the corridors generally does not run parallel to one another, but open at more or less narrow angles, the opening angles in particular to the longitudinal sides of the Diffraction Strips Depend on the Viewing Distance The light is radiated in a corridor that is dependent on the imaging density in many directions, which in their entirety result in the diffraction corridor, the mean emission direction being the direction of emission averaged over all directions

The substantially parallel strips arise when using a diffraction grating-based projection screen of the superposition of many individual diffraction streaks, each of which may also have a slight curvature, but in the superposition On the average for a viewer is no longer or barely perceptible

Several diffraction strips for a view can be generated z B by the diffraction grating in the projection screen as a superposition multiple grids is designed one behind the other, for example, five or seven grids to allow in a wide space as possible a three-dimensional view at five diffraction gratings, for example, to the left and generated five stripes to the right of the flat normal of the screen

The diffraction strips preferably extend in the vertical direction substantially parallel to one another, so that a standing or sitting observer does not need to turn his head in order to obtain a three-dimensional impression. The diffraction strips or diffraction corridors are relatively narrow. which, of course, because the diffraction corridors have a certain opening angle, increases with the distance from the screen - at the given viewing distance about 65 mm, which is the average pupillary distance of a human as viewing distance for a larger projection screen that allows multiple viewers a good perception, for example a viewing distance of 2 to 4 m Depending on requirements, the viewing distances may also be smaller, for example for individual workstations with a computer screen, or even larger, such as in the cinema. Generally, for smaller screens irrespective of the size of a computer screen, smaller viewing distances are suitable, correspondingly larger viewing distances for larger screens In a beam plane perpendicular to this and parallel to the longitudinal direction of the diffraction strips, the imaging directions with the flat normal of the projection screen preferably include a diffraction or projection angle φ different from zero. This has the advantage that the zeroth, undeflected and very bright order or Real image is not distractingly perceived by the viewer. Image direction is understood as the direction corresponding to the optical axis of the beam path for a view to be imaged, or the axis connecting the center of a projection objective to the center of the holographic projection screen , of which there are several for each view, also correspond in each case to a middle direction or an optical axis in which is radiated From the Abstrahlπchtung must not / n the beam plane lie, as this is also perpendicular to the screen projection, however, it points anyway s a grain component in the jet plane

The diffraction grating can be generated, for example, by means of photolithographic scanner technology from superimposing or superimposing individual gratings. The three-dimensional impression of a multiplicity of viewers is produced by the arrangement of several parallel diffraction gratings. The distance between two diffraction gratings depends on the number of views used n views are shown, the distance between the center lines of two diffraction strips belonging to the same view is exactly n times the width of the strip, which is the same for all views. In this case, the strips do not overlap, but it is also conceivable to construct the diffraction grating in this way. In this way, the brightness of the streamer strips decreases towards the edges, thus allowing a more pleasant transition between two views for a viewer moving horizontally

The lying in the beam plane component of the emission preferably is perpendicular to the projection screen Thus, a viewer can look at the projection screen in a natural way and when viewed for example directly from the front best impression This also has the advantage that a projection screen can be easily aligned, because it can be placed in a viewing room, for example, as a conventional Rückprojektionsgerat course, other radiation directions are conceivable in which the lying in the beam plane component is tilted slightly up or down, dtes is advantageous, for example, if Projection screen above or below the average viewing height - z B the average size of the viewer - attached radiation direction and imaging direction only, as already introduced above, mean directions In Bildπππungung the component in the beam plane should not be perpendicular to the projection screen to the Although horizontal deviations from the normal to the projection screen are possible and are also required to a limited extent in order to produce different imaging patterns at maximum brightness, the imaging direction and the normal to the plane of the projection screen in the beam plane preferably enclose an angle between 1 and 80 ^', preferably 37 ^"or equivalent to {1 43" depending on the approach) a in this manner, the zero order can be hidden and projected onto a light absorbing ceiling also possible for relatively large projection screens, without da she had a disturbing impression on the viewer or Again, variations are possible and also necessary if, for example, a plurality of projectors used The mean angle should but then are still at 37 '

In order to correct a color aberration of a projection screen for a given viewing distance, the views in one embodiment of the invention are composed of linearly varying superimposed top layer views. These overlay views are then shown

To generate the views or overlay views, one or more imaging arrays with individually controllable optical elements are expediently provided in the imaging optical system. DMDs or FLCDs which can be switched quickly are particularly suitable for the imaging arrays. However, slower arrays such as LCOS can also be used For this purpose, the imaging optics expediently a number of projection lenses corresponding to at most the number of views for specifying the Abbildungsπchtung on an image-forming array and a projection lens can be combined to form a unit, a projector So be For example, eight eights shown, so you can use eight projectors The projectors or projection lenses are horizontally and / or vertically offset from each other, so as to different Specify Abbildungsπchtungen In a preferred embodiment of the invention, the projection lenses are arranged on an imaginary spherical shell, wherein the radius of the ball corresponds to the distance to the center of the projection screen with respect to the beam path. In this way it is achieved that the images are always imaged on the Projektioπsschirm that arise on the same size images in this way, a correction of the Hohendispaπtat is unnecessary Also, the correction of an irregular keystone distortion, which is caused by the imaging of non-zero diffraction angle , is relieved

Since the projection screen has a chromatic aberration due to its construction as a diffraction grating, means for optically correcting this color aberration are expediently provided in the imaging optics. For example, for each view three projectors can be used, each of which creates an image of the view in one of the three basic colors R (red), C (green) and B (blue) and images on the projection screen in the arrangement just described on a The spherical aberration can be corrected for the color fringe error, since for each of the three primary colors a different spherical shell is used according to the color fringe error

Another possibility is then to provide beam splitters for splitting the views into images of the three primary colors R, G and B, and beam combiner for Strahlzusammenfuhrung the corresponding images between splitting and Zusammenfuhrung the images while optical paths are provided with different paths for the three primary colors

Yet another possibility is to arrange a Fresnellmse with the operation of a rod lens between imaging optics and projection screen, as close to the projection screen. If the focal length of the Fresnel is equal to the distance between the projector and the projection screen, the light will be parallelized by the projector in front of the projection screen, which will otherwise reduce the angle to the outside. This also leads to a reduction in color aberration, which decreases with decreasing grid lines and rising In addition, the Fresnellmse can image the lens in the observer distance, so that the projection screen only the diffraction into the viewer space and the generation of a stripe width takes over This is particularly advantageous if the three-dimensional impression achieved only in a small area must be, and this area can also be flexible Even if the projectors are not arranged on a spherical shell, each of the views of individual images in each of the three basic colors R (red), C (green) and B (blue) can be composed for each of the primary colors for each view own projection lens be provided, the projection lenses have in this case also for the three basic colors each different distances to the screen.

The larger the projection screen is, the further the projectors must be fundamentally removed from the project in order to image a correspondingly large image on the screen. One or more mirrors are therefore preferably arranged in the beam path between the imaging optics and the projection Reasons - z 6. for enlargement - curved mirrors are used, but these mirrors are preferred even, so they are the cheapest to manufacture

In particular, when the mirror surfaces are arranged parallel to each other in the form of a light shaft, so let the depth of the device greatly verkurzen, of course, must be taken to ensure that the entire path that covers the light from the projector, with and without the use of mirrors is identical. If, for example, a beam of light displaces a distance from the projector to the projection screen of 2 m without a mirror, then the path must be identical when using mirrors. Even when using a mirror, the depth can be shortened to half, ie 1 m. Of course, for other light paths, the mirrors can also be tilted relative to one another and arranged to the projection screen

In a further preferred embodiment of the invention, the projection screen is tilted with respect to the normal direction of a surface in the viewing space in which one or more observers are tilted by an angle δ. This allows several people standing behind each other to obtain a three-dimensional impression of the projection screen

While the projection screen generally works transmissively, in a preferred embodiment of the invention it is designed to be reflexive, while still making the ideal viewing slope dependent on the viewer's vertical position is so let such a projection screen, for example, in a cinema for a variety of viewers use

The invention will be explained in more detail below with reference to exemplary embodiments in the accompanying drawings

Fig. J a is a side view of a first basic embodiment of the invention,

FIG. 1b is a plan view of the same embodiment;

3 shows a side view of an embodiment in which a plurality of projectors are arranged on a spherical shell; FIG. 4 shows an embodiment of the invention in which the screen is tilted by an angle δ;

5 shows an embodiment with a reflexive holographic projection screen FIG. 6 shows an example of a variation of the given viewing distance with the height, and FIG. 7a, b shows the composition of the views on interference control for correcting a far-end aberration of the projection screen

The operation of the holographic projection screen according to the invention is shown in FIGS. 1a and 1b. FIG. 1a shows a side view of an arrangement of a projector 1 and a holographic projection screen 2. FIG. 2b shows a plan view of the same arrangement. The projector 1 projects a view or a projection Image of the view as a real image under the diffraction or projection angle <p on the holographic projection screen 2 The diffraction angle φ is determined with respect to the Bildbildungsπchtung, ie the direction of the optical axis to the center of the screen 2 and the middle direction, from the Light from the projector 1 on the holographic projection screen 2 falls The projector is located at a distance d from the holographic projection screen 2 The distance d _p is chosen so that a real image is produced in sufficient Crofee on the projection screen 2, wherein it trapezoidal distortions of the image can come, but can be corrected

Pro _j ector point 1 and 2 is a projection screen High distance on u, which is due to the condition that the light at the diffraction angle φ of the projection The projection screen 2 has a height h Typical values are, for example, u =) to 2 m and h = 30 cm to 1 50 m Smaller and larger values are possible depending on the design

Since the light strikes the projection screen 2 at an angle φ, the zeroth, undeflected order also emerges again from the projection screen 2 at this angle, which in the present example is designed to be transmissive, but can also be embodied in an equivalent manner as an observer a viewing distance d _^ from the projection screen 2 aufhalt, the real image of the zeroth diffraction order thus does not see this image, for example, to the ceiling of a room in which the assembly is projected, in order to avoid disturbances of the viewer by this, the blanket let designed, for example, light-absorbing

In FIGS. 1a and 1b, the zeroth diffraction order is drawn with solid lines on the viewer side. The beam path of the first diffraction order is indicated by dotted lines. In contrast to the zeroth order of diffraction, the first diffraction order is radiated almost perpendicularly from the projection screen 2 in the direction of the observer 3. ie the direction in which the first diffraction order is radiated in the middle is indicated by dashed lines in the shaded areas. If one defines a radiation plane perpendicular to the projection screen and parallel to the longitudinal direction of the diffraction strips, which run vertically here, the example in FIG Of course, the ge called component does not necessarily have to be perpendicular to the screen, other directions are - depending on the use of the arrangement - possible, for example For example, it can be tilted slightly up or down when the projection screen is mounted above or below the viewers, as indicated particularly in reflective projection screens for use in the cinema

Since, as seen in plan view in FIG. 1B, a plurality of first-order diffraction gratings are emitted, there are also several emission directions for each view

The distance between two diffraction strips or their center lines amounts to np in the present example ₍ n defines the number of views that are projected together from a total of n projectors 1 onto the projection screen 2. For the sake of clarity, a representation of the remaining projectors 1 was used here ziehtet P _j is the m edium interpupillary distance of a human and amounts to about 65 mm The other projectors are n then at least horizontally mutually offset so that i hre fringes the intermediate space between the positions shown fringes fill Here, exactly projects a diffraction fringes in the space between each projector , so that for each view in the space exactly a diffraction patrol n emerges in this way, an observer is given an autostereoscopic impression, as each eye sees the image of another projector Since the strips repeat the autostereoscopic impression can be offered to a large audience without the Increase number of projectors excessively In the present example, the diffraction stripes do not overlap each other, they have a substantially uniform brightness along the entire width substantially according to a rectangular function, which falls off steeply at the edge. Other brightness modulations si nd possible, eg those with a brightness distribution over the stripe width in the manner of a Gaussian function or a trapezoidal function Here, the brightness of the diffraction strips differs to the edge hm. Then, the projection screen 2 can also be embodied or the projectors can also be arranged such that In this way, for a viewer who moves horizontally, a more pleasant transition between the individual views created condition, however, is that more than two views are used, otherwise the three-dimensional A Printing suffers from white light as a source of light for the projector, in order to produce as full a color image as possible. However, monochrome light sources are also conceivable, depending on the field of application

In order to make the spatial impression accessible to a large group of people, it is necessary to use a holographic projection screen 2 as large as possible so that the views on this can be displayed with sufficient size who is the Llchτweg between projector 1 and projection screen 2 is quite long at a Projektioπsschirm 2, which has a vertical extension of about 1 m, the projector must be set up, for example, at a horizontal distance d of about 2.70 m. This requires a rather large overall depth, which makes the arrangement quickly become unwieldy and unsuitable for smaller display rooms Advantageously, therefore, as shown in Figure 2, provide mirrors 4, which reduce the depth, but leave the length of the light path as well as the diffraction angle with respect to the im Bildπchtung untouched This is shown in Figure 2 Without mirror of the projector. 1 is placed at a distance d ^ and se in light along the dashed lines on the projection screen 2 throws when using two mirrors 4, the horizontal distance of a projector 1 'from the screen 2 can be shortened to one third Depending on the number of mirrors used, the depth can be correspondingly shortened by this number of reflections In Fig. 2, the mirrors 4 are also oriented vertically and parallel to each other, so that the image is directed to the projection screen in a light well. Instead of using a large mirror surface for a mirror 4, many small mirror surfaces can also be used. However, this may require somewhat more effort in terms of mounting and adjustment

3 shows an example in which the projectors 1 are arranged on a spherical shell. In the side view two projectors 1 are shown, which are arranged slightly offset one above the other. Perpendicular to the image plane, further projectors 1 can be arranged around the number of views to be displayed The diffraction angle is also aimed at the center M of the projection screen 2, which is at a distance d ₀ horizontally from the point at which a projector would ideally be placed the angle φ = 37 "amounts to, the angle φ ₀ for the upper projector, for example, 1 34 61 'and the angle ψ _υ for the lower projector 1, for example, 39.47' by the arrangement of the projectors on a spherical shell is ensured that the image always throws so that on the screen gl The size of the bullet is equal to the distance to the center of the screen. The projectors are here relatively close to each other, but are also wider Arrangements which are distant from one another are possible in which, for example, the projectors are arranged laterally or overhead. Finally, a chromatic aberration of the holographic projection screen 2 can also be corrected by producing images of different colors for each one and thrown from different projectors 1 onto the projection screen 2 where the projectors for the different colors are on spherical shells with different radii

FIG. 4 shows an arrangement in which the projection screen 2 is opposite the direction of the normals of a surface 5 in the viewing space, on which one or more With such an arrangement, the projectors 1 for the purpose of maintaining the length of the light path and the diffraction angle φ relative to the projection screen 2 no longer need to be placed directly above the floor when the projection screen 2 The viewer can see the inclination 3, especially smaller persons, at least almost vertically on the projection screen. With their slightly raised faces, they are once again in the emission range of the diffraction images

FIG. 5 shows an arrangement according to the invention in which a holographic, reflective projection screen 6 is used instead of a holographic, trans missive projection screen 2. The reflection hologram generates spatially separate viewing areas from the average eye distance p _ύ by projection of n images from different spatial directions of a human at a defined viewing distance d _m Of course, the projectors 1 can also be arranged differently here. The diffraction images of the images are directly next to each other and repeat themselves after πp _d. In FIG. 5, the beam path for three views _{is shown} by solid, dashed and dotted lines are shown here too, it may be advantageous if there are slight overlays between the views. The advantage of using a reflexive projection screen 6 in relation to a transmission screen is the considerably smaller overall depth, as the project ovens can be mounted behind the viewers The reflexio mogram m can thus be hung directly on the wall Here as well as in the other cases, of course, the same view can be displayed everywhere, so that then creates a two-dimensional impression in the viewer

Both the Trans mission and the reflection hologram, the viewer distance can be vertically aligned in various ways In the simplest case, the views or their diffraction images in a vertical direction spread homogeneously with a large opening angle The viewer distance d _# is then everywhere the same in the vertical direction This is the Normal case It is also conceivable, however, to construct the transmissive projection screen 2 or the reflective projection screen 6 in such a way that the viewing distance d varies for different viewing heights of a viewer 3. This is illustrated in FIG. 6 by the example of a reflective projection screen 6 by tilting the object plane or adaptation of the grating structure of the reflection hologram, the image plane is tilted With the gaze height h of the observer 3 increases in an interval Δh the distance of the observer is continuously linear with a slope m an, d = mh The increase m for the high distance relations can be calculated from the minimum distance d, and the maximum distance d as m = (d - d) / Δh

Combinations of a varying observer distance d _{# which} is constant over certain high ranges are of course possible

In FIGS. 7a and 7b, it is finally shown how views are assembled into overlay views in order to correct a longitudinal chromatic aberration of the holographic projection screen. Due to this color slant error, a viewer sees the image error-free only for the wavelengths whose viewing distance d (λ) The width of the diffraction stripes is determined by the actual to the calculated viewing distance and the considered wavelength. For example, if the observer is at a viewing distance d _^ (λ = 532 nm), in which the stripe width is 65 mm, the stripe width b _{λ is} calculated on the projection screen according to the formula

λ _R denotes a reference wavelength, which is used as the basis for the correction. For the viewer distance d, a color and view correction can now be made, but this is limited to the distance

The viewer is at a distance d _^ to the projection screen in the green wavelength is mapped correctly, he sees the green portion of a view n correctly and over the entire width of the screen, the red and the blue portion of the autostereoskoptschen image is for each projector However, to see only in a range of width b _x A viewer sees therefore for the red and the blue wavelength, an image which is composed of several views to the green correctly represented view n composed It may lead to double images To avoid this it is it is necessary to rebuild the images for each projector and overlay the views to overlay views. To compensate for the false view, instead of the view n, an overlay view is displayed in a stripe area k from the views n _k . The views to be superimposed are calculated according to the formula "* =", - k (2) h \

k is a numbering for the strip order on the projection screen and is paid negative to the left and positive to the right P "(\) and d ^) are Pupiflenabstand and viewer distance at the reference wavelength λ _o . For the smoothest possible transition between the views, it makes sense to generate a linearly increasing and decreasing intensity progression of the individual views in the superposition view. In order to represent suitable reference points for the different course of the views within an overlay view m _p , the spatial zone becomes dependent k on the projection screen the starting points S _k , maximum points P ₁ and end points E _k defined-

p_k -A_{+ k}M ₍₄₎

p _k -A _{+ k} M ₍₄₎

* 2 b _{Et =} L _{+ (k +))} M ( ₅ )

1 D

b is the screen width. or the width of the image in which the viewer sees the image correctly for the green wavelength. Between these points, the local intensity of the individual views for a color on the projection screen becomes the formulas

for S _k <X ≦ P _k If = ((X - S _k ) (6)

for P _t ≤ X <E _k I _k ^Fε = ~ (£ * - X) ⁽ 7)

calculated X is the Laufvaπable, I ₁ "is the Intensitatsverlauf between the starting ^¬ point S and the maximum point P _1, l _k ⁿ describes the course between the maximum ^¬ value P and the final value E A viewer perceives the correction of the image after the 7a and 7b, the projection screen is observed from the center of a diffraction strip, in FIG. 7b from the position of a transition between two views. These two positions describe the boundaries in a horizontal movement of the viewer parallel to the projection screen Since, as shown in FIG. 7b, the transition between two views takes place in the region of high intensities, image disturbances such as banding may occur, which however can be corrected by damping, for example

Claims

Patent claims Method for the spatial representation of a scene for one or more viewers (3), in which several views of the scene are imaged on a holographic projection screen (2), each of the views having an imaging direction that is different from the imaging directions for the other views , is imaged on the holographic projection screen (2) and on the projection screen (2) incident light is diffracted depending on the imaging directions, so that an observer (3) perceives different sets of views with the left and right eyes and creates a spatial impression, characterized in that the diffracted light is divided into several for each view First-order diffraction corridors, each with average radiation levels in Dependence on the imaging direction is emitted, and in a plane parallel to the project (2) in a predetermined plane Viewing distance diffraction images are generated in the form of diffraction strips running essentially parallel to one another, with a diffraction strip of each of the other views being generated between two diffraction strips assigned to a view Method according to claim 1, characterized in that the diffraction strips run essentially parallel in the vertical direction Method according to one of the preceding claims, characterized in that the diffraction strips at the predetermined viewing distance have a width that corresponds to the average pupil distance of a human, preferably 65 mm 4. Method according to one of the preceding claims, characterized in that each imaging direction with the surface normal of the projection screen (2) in a beam plane perpendicular to the projection screen (2) and parallel to the longitudinal direction of the diffraction strips includes a non-zero diffraction angle (φ). 5 Method according to claim 4, characterized in that the diffraction angle (φ) is between 10° and 80°, preferably 37° 6 Method according to one of claims 4 or 5, characterized in that the component of the radiation direction lying in the beam plane is perpendicular to the projection screen. 7. Method according to one of the preceding claims, characterized in that the views are superimposed in a linearly varying manner to form overlay views and these are displayed, so that a longitudinal color error of the projection screen (2) is corrected for a predetermined viewing distance Arrangement for the spatial representation of a scene for one or more viewers (3), comprising a holographic projection screen (2) and imaging optics with which multiple views of the scene are imaged on the projection screen (2), each of the views in one imaging direction , which is different from the imaging directions for the other views, is imaged on the projection screen, the projection screen (2) diffracting incident light depending on the imaging directions, so that an observer (3) with the left and right eyes sees different amounts of perceives views and a spatial impression is created, characterized in that the holographic projection screen (2) has at least one diffraction grating in such a way that for each view the diffracted light is emitted into several first-order diffraction cells, each with central radiation directions depending on the imaging quality, so that Diffraction images are generated in the form of diffraction stripes running essentially parallel to one another in a plane parallel to the projection screen (2) at a predetermined viewing distance, wherein between two diffraction stripes assigned to a view, a diffraction stripe of each of the other views is generated Arrangement according to claim S, characterized in that the diffraction strips are parallel in the vertical direction Arrangement according to one of claims 8 or 9, characterized in that the diffraction strips have a width at the predetermined viewing distance which corresponds to the average interpupillary distance of a human being Arrangement according to one of claims 8 to 1 0, characterized in that each imaging direction with the surface normal of the projection screen (2) in a beam plane perpendicular to the projection screen (2) and parallel to the longitudinal direction of the diffraction strips includes a non-zero diffraction angle (φ). Arrangement according to claim 1 1, characterized in that the diffraction angle is between 10° and 80°. preferably 37". Arrangement according to claim 1 1 or 1 2, characterized in that the component of the radiation direction lying in the beam plane is perpendicular to the projection screen (2). Arrangement according to one of claims 8 to 1 3, characterized in that one or more image-generating arrays with individually controllable optical elements, preferably DMDs, LCOS or FLCOs, are provided in the imaging optics for generating the views Arrangement according to one of claims 8 to 1 4, characterized in that the imaging optics has a maximum number of projection lenses corresponding to the number of views for specifying the imaging direction Arrangement according to claim 1 5, characterized in that the projection lenses are arranged horizontally and/or vertically offset from one another Arrangement according to claim IS or ) 6, characterized in that the projection lenses are arranged on an imaginary spherical shell, with the radius us of the sphere corresponds to the distance to the center of the projection screen (2) with respect to the beam path 1 8 Arrangement according to one of claims 1 5 to 1 7, characterized in that means for optically correcting a longitudinal color error of the projection screen (2) are provided in the imaging optics 1 9 Arrangement according to claim 1 8, characterized in that the means for optical correction comprises beam plates for dividing the views into images of three primary colors R, C, and B as well as beam combiners for merging the images, with optical paths with different ones between dividing and merging Pathways for which three basic colors are provided. 20. Arrangement according to claim 1 8, characterized in that the means for optical correction comprise a Fresnel lens arranged between the imaging optics and the projection screen (2) and operating like a rod lens. 21. Arrangement according to one of claims 1 5 to 1 8, characterized in that each of the views is composed of individual images in one of three primary colors R, G, B, a separate projection lens being provided for each of the primary colors for each view, and the projection lenses for the three primary colors each have different distances from the projection screen. 22 Arrangement according to one of claims 8 to 21, characterized in that one or more, preferably flat mirrors (4) are arranged in the beam path between the imaging optics and projection screen (2). 23. Arrangement according to claim 22, characterized in that the surfaces of the mirrors (4) are arranged parallel to one another in the form of a light shaft. 24 Arrangement according to one of claims 8 to 24, characterized in that the projection screen (2) is arranged tilted at an angle (δ) relative to the normal direction of a surface (5) in the viewing space on which one or more observers (3) are located is. 5 Arrangement according to one of claims 8 to 24, characterized in that the holographic projection screen (6) is designed to be reflective.