WO2013030013A1

WO2013030013A1 - Illumination device of a holographic display

Info

Publication number: WO2013030013A1
Application number: PCT/EP2012/066089
Authority: WO
Inventors: Norbert Leister
Original assignee: Seereal Technologies S.A.
Priority date: 2011-08-26
Filing date: 2012-08-17
Publication date: 2013-03-07
Also published as: TW201314318A; DE102011053037A1

Abstract

The invention relates to an illumination device comprising an array of light sources for a holographic display having imaging elements and a light modulator, in which the brightness of reconstructions of a three-dimensional scene can be improved at discretionary positions of visibility areas. In the illumination device with a light source array, at least two light sources (LQ) can be selectively activated for each imaging element (AE), by way of which a visibility area having a total intensity (I) from a superposition of the intensity maximum of a diffraction order with part of an intensity maximum of at least one additional diffraction order can be generated. Reconstructions generated at the same location can be superimposed with said intensities, which can be seen as a reconstruction of the 3D scene having a brightness corresponding to the total intensity in the visibility area at positions of pupils (AP), by way of which the position of the light sources (LQ) to be selectively activated can be defined. The invention can be used in holographic displays and arrays for beam shaping or beam deflecting of light.

Description

LIGHTING DEVICE FOR A HOLOGRAPHIC DISPLAY

The invention relates to a lighting device comprising an array of light sources for a holographic display comprising at least imaging elements and a controllable spatial light modulator into which a 3D scene to be reconstructed is encoded, which can be perceived as lighter in a visibility region than with a comparable one

conventional lighting device. The invention also includes a holographic display comprising the lighting device according to the invention. Field of application of the illumination device according to the invention are not only holographic displays but also arrangements for beam shaping or beam deflection of light.

The applicant WO 2004/044659 (A2) discloses a holographic display for reconstructing a 3D scene with a viewer window, which can also be referred to as a visibility area. The holographic display has a

Lighting device with a light source, an imaging means and at least one controllable spatial light modulator (SLM), which is to be illuminated with sufficiently coherent light. For example, a 3D scene may be written into the controllable spatial light modulator as a hologram. In order to calculate controllable data or hologram values, for example, the 3D scene is computationally decomposed into many object points and sub-holograms calculated for the individual object points, their amplitude and / or phase values added up and written into the controllable spatial light modulator as hologram values become. The coded amplitude or phase values modulate the light which is guided as the wavefront of the 3D scene onto observer eyes, with which the generated reconstruction of the 3D scene in a visibility region can be perceived. With this principle, the

Visibility area for different possible positions of observer eyes are generated in the observer level. The brightness with which the reconstruction of a 3D scene is perceptible to a viewer depends, among other things, on how much light intensity reaches the visibility area. In this case, for example, the transmission of the spatial light modulator has an influence as well as the properties of the imaging elements of the lighting device or in the holographic display. For a given arrangement of lighting device, light modulator and imaging elements, for example, this brightness can be changed by changing the intensity of the light sources in the lighting device.

The brightness of the reconstruction can also be used for displaced eye positions within be perceived differently in the visibility region, for example, if the intensity of the reconstructed object points not with a predetermined target intensity of the reconstructed object points at different positions within the visibility range for

Observer eyes matches.

So-called tracking devices (tracking devices), with which a visibility range for eye pupils of at least one observer can be provided or generated in front of a display during its position change, are known e.g. from WO 2008/142108 A1 (electrowetting tracking) or, for example, WO 2006/119920 A1 (Lichtquellentracking) known. Providing the visibility area at different positions of eye pupils is often referred to as "shifting" the visibility area.

When light source tracking other light sources can be switched on for a newly determined position of observer eyes, the new position for this newly determined position

Provide visibility area. This can also be referred to as "moving" light sources to a new position, an example of which is a lighting device comprising at least one light source and a controllable spatial light modulator with a light source

Pixel matrix has. The pixels of the controllable light modulator, which is referred to as a shutter display, can be switched on in rows and / or columns so that they are transparent to incoming light and secondary row and / or columnar

Form light sources. With the intensity of the light source images of the secondary light sources, a reconstruction can be generated which can be seen with a certain brightness. If the reconstruction is to be seen brighter, the intensity of the primary light sources must be increased.

So that the highest possible energy efficiency of a lighting device can be achieved, the radiation angle and the shape of the light sources and the shape and extent of imaging elements for imaging the light sources should be coordinated as far as possible. For example, a shape of a light source is understood here to be approximately a punctiform or a line-shaped light source. In a holographic display with a light source array, e.g. Having approximately line-shaped light sources, an SLM can be most efficiently illuminated with a lenticular of cylindrical lenses. In a holographic display with a light source array, e.g. Having approximately point-shaped light sources, an SLM can be most effectively illuminated with a lens array of spherical lenses. Linear light sources are preferably used in combination with a single-parallax coding, referred to below as 1-D coding.

Point-shaped light sources are preferably used with a full-parallax coding, in Following 2D-coding called.

Creating the reconstruction of a 3D scene with a holographic display is e.g. from WO 2004/044659 (A2), and is shown in simplified form in FIG. 1 on the basis of an object point which is to represent a part of a 3D scene. To according to the

Reconstruction principle of WO 2004/044659 (A2) to illuminate a controllable spatial light modulator over a large area in which a 3D scene is encoded, the holographic display can be used e.g. a single light source and a large-sized lens, or a light source array and an array of imaging elements. With the light modulated in the controllable light modulator, reconstructions of the 3D scene and visibility regions in a viewer plane are generated in periodic continuation.

The reconstruction of the 3D scene is with eye pupils in a visibility area

perceptible, which is determined within a single diffraction order in the observer level. Normally the diffraction order with the highest intensity is selected, ie the 0th diffraction order, so that the reconstruction is visible with a brightness corresponding to this intensity.

According to the reconstruction shown schematically in FIG. 1, an almost coherent light bundle of a light source LQ switched on per imaging element AE illuminates a spatial light modulator ME, the light being diffracted by the pixel matrix. In at least one region of the pixel matrix, a hologram SH of an object point O OP is encoded, which the modulated light reconstructs in the viewer's space. In a visibility range VW, the reconstruction is seen at the position of an eye pupil AP having a brightness that depends on the intensity of the modulated light of the light source. The visibility range is in

Intensity maximum of the 0th diffraction order, with which the reconstruction of the object point 0 OP is generated. Its reconstruction continues periodically in the viewer's room with lower intensities, the same applies to the continuation of the diffraction orders of the light source in the observer plane. The object points +1 OP and -1 OP generated with lower intensities of the + - 1st diffraction orders, which are shown with lower line width, are in the

Visibility range with the eye pupil AP imperceptible. In comparison to

Reconstruction with the intensity of the 0th order of diffraction, the object points +1 OP and -1 PO would be seen with a lower brightness, if the eye pupil in the observer plane in the +1. or -1. Diffraction order would be positioned. The diffraction orders are shown in the viewer plane in Fig. 1 with double arrows.

Starting from the intensity maximum of the O. diffraction order of an activated light source The relative intensities (secondary maxima) in the first and higher diffraction orders usually have a decreasing course on both sides. The intensity maximum of

Diffraction orders are generally determined by the transmission curve in the pixels, that is to say by the pixel aperture and by a possible change in the transmission in the aperture, even if the transmission characteristics of the pixels of the SLM are determined, for example. With an apodization function optimized, intensities of at least one further order of diffraction greater than zero can generally still be present. Cosine function apodized pixels can be e.g.

Suppress intensities from the second diffraction order, but reinforce the intensities of the first diffraction orders in the observer plane. Furthermore, apodization often causes the transmission to decrease and the intensity of the 0th diffraction order and the 1.

Diffraction orders are reduced, whereby the brightness with which the reconstruction is visible, is also reduced. As a result, the contrast can also be reduced, as a result of which details such as, for example, brightness gradients in the reconstruction are not easily recognizable. The intensity in the visibility area should be as large as possible for the object points of a 3D scene to be reconstructed.

Since, as a rule, the intensity already decreases towards the edge of the central diffraction order, e.g. the brightness of the reconstruction are perceived differently, e.g. also deviating from a predetermined target intensity of the object points when the position of the observer's eye is moved within the visibility range.

Usually, an observer tracking takes place in such a way that the center of the

Visibility range is brought into agreement with the position of an eye pupil. Due to inaccuracies of the tracking or by very fast eye movements but may occur the case that a viewer eye briefly outside the center of the

Visibility area is located. Therefore, it is desirable if, for such a shifted eye position, the intensity with which the reconstruction is perceived does not change.

Illumination devices for holographic displays for generating reconstructions of three-dimensional scenes can have controllable light sources which can emit light variably up to a maximum possible intensity. Do you want the brightness of

Reconstructions e.g. With light sources of higher intensity, components in the holographic display can be affected by high heat development in their proper use.

It is therefore an object of the invention to provide a lighting device with which the brightness of reconstructions of a 3D scene at arbitrary positions of Visibility areas can be improved.

The invention is based on a lighting device with a light source array for a holographic display, which has a controllable spatial light modulator in which a 3D scene is inscribed, and imaging elements each having a number of switchable light sources whose diffraction orders are repeated periodically in a viewer plane a diffraction order with an intensity maximum as

Visibility is set, in which one generated with the intensity maximum

Reconstruction of the 3D scene is visible, the light sources are switched on with controls of control systems depending on positions of the eye pupil.

According to the invention, the object is achieved by the lighting device according to patent claim 1 and / or by the fact that at least two light sources are activated for each imaging element, which generate a visibility range with intensities of superimposed diffraction orders, which results in a total intensity of an overlay of one

Intensity maximum of a diffraction order with a part of an intensity maximum of at least one other diffraction order, which can be generated with these intensities in the same place superimposed reconstructions, which is to be seen as a reconstruction of the 3D scene with a total intensity in the visibility region corresponding brightness at positions of the eye pupil which the position of the controllable

einschaltenden light sources can be specified.

Since each light source image in the observer plane with diffraction orders propagates periodically, intensities of diffraction orders and / or at least intensities of parts of the diffraction orders of light source images can be switched on

Light sources are superimposed when the light sources are controllably turned on at predetermined intervals. Likewise, with these intensities, reconstructions can be generated and superimposed at the same location, whereby superimposed intensities result in a superimposed reconstruction, which with an increased brightness in the visibility range

can be perceived. The visibility area shows the overall intensity of the superimposed intensities.

According to the invention, the visibility range at changing positions before the

controllable spatial light modulator can be generated with variable distances or angles of emission of light sources to be switched on.

Control systems of the invention include, for example, control elements that are set up according to the invention in such a way that light sources with a predefinable number, or / and predefinable Distances or adjustable radiation angles can be activated or deactivated, that is to say switched on or off, the from the position of the to be generated

Visibility range whose position is detected with position data

Eye pupil is specifiable.

With this lighting device according to the invention, for at least one observer in the room in front of e.g. a holographic display with an inventive

Lighting device can be generated at changing positions a visibility area in which a generated reconstruction is perceptible.

The light sources switched to an imaging element may be at a distance from one another, with which the intensity maxima of the diffraction orders of the light source images are offset by an integer multiple of the interval of a diffraction order to the intensity maximum of the visibility region, wherein the interval is an integer greater than or equal to 1. Thus, the distance of at least two light sources which can be activated to form an imaging element corresponds on the illumination side to the integer multiple of the distance from

Intensity maxima of the illumination orders of the light source images to the maximum intensity of the visibility range image side. Furthermore, the lighting device may have light sources whose distances from the

Generating the visibility range depending on a 1 D or 2D encoding of the 3D scene in the vertical or / and horizontal direction are driven variable switched on. By repeating the diffraction orders of the light sources turned on, depending on the method of encoding, e.g. Burckhardt or two-phase coding, superimposed in the visibility range periodic repetitions of intensities, with which a reconstruction can be generated.

According to one exemplary embodiment of the illumination device, preferably at least three light sources per imaging element can be controllably switched on, wherein the intensity maximum of the visibility region can be overlaid with an additional intensity component of at least two additionally switched on light sources, wherein the additional intensity component superimposed intensities of a part of a diffraction order or the entire diffraction order and the same Part of at least one other diffraction order or the entire diffraction order has. The intensity maximum of each one light source, preferably the 0th diffraction order, is in the present embodiment as

Visibility range set. A further embodiment of the illumination device can be an overall intensity of a visibility zone for a viewer plane with a programmed one

Be predetermined far field diffraction pattern for the light sources per imaging element with a programmed start pattern of controls are switched on controllable.

To generate the visibility region, an illumination device can have real or virtual light sources which can be actuated or deactivated in a controllable manner and which can be arranged in a matrix. The light propagation of the switched-on light sources can be controlled at least one-dimensionally in the horizontal or vertical direction, the 3D scene being coded at least one-dimensionally horizontally or vertically.

The invention further comprises a holographic display comprising a lighting device according to one of claims 1 to 8. In particular, the holographic display has a matrix of light sources, as well as imaging elements and a controllable spatial

Light modulator, in which a 3D scene is inscribed, the generated reconstruction is visible in a visibility area having intensities of at least two different diffraction orders, which form by overlapping a total intensity with which a reconstruction of the 3D scene from at least two superimposed reconstructions can be generated wherein, when changing the position of eye pupils with control systems, the position of the visibility region is variable with a number of variably predefinable activatable light sources per imaging element.

The holographic display can furthermore be configured in such a way that the light sources can be switched on and off in variable manner with distances and / or emission angles, wherein the control of light sources in relation to a respective position of eye pupils in any observer plane before the controllable spatial light modulator for generating a respective visibility range he follows. The visibility regions are usually producible in different viewing planes within a predefined depth range or a distance range from the controllable spatial light modulator or from the holographic display, which can be, for example, between 70 and 120 cm.

With regular arrangement of the pixels, i. of the center-to-center distance of two immediately adjacent pixels (hereinafter called pixel pitch), the pitch of the diffraction orders in the observer plane is normally proportional to the reciprocal of the pixel pitch

Pixel matrix. Furthermore, the distance of the diffraction orders to each other is proportional to the distance between the observer plane and light modulator. To make reconstruction errors at

Reconstructing the 3D scene or an object point as small as possible is the size the visibility range within a diffraction order given slightly larger than the diameter of an eye pupil. The pixel pitch of the light modulator is usually selected according to these requirements, ie the size of the visibility range. For distances of viewing planes to the light modulator of about 70 -120 cm, the pixel pitch of the pixel matrix should be, for example, a value between 30 μηη and 50 μηη.

The holographic display can have a lenticular array with imaging elements, to each of which light sources can be assigned, which can be variably activated to generate the visibility area, wherein a 3D scene in the controllable spatial light modulator is preferably coded one-dimensionally.

Optionally, the holographic display can also have a two-dimensional arrangement of spherical imaging elements which can each be associated with light sources which can be variably activated to generate the visibility region, wherein a 3D scene in the controllable spatial light modulator is preferably written two-dimensionally coded.

A further embodiment of a holographic display can contain a lighting device whose light sources can be switched on at different positions and / or with different radiation angles for different wavelengths of the light used for the reconstruction of the 3D scene.

For the purposes of this document, a light source can be regarded as sufficiently coherent if its light is spatially coherent so far that it is capable of interfering, so that at least one one-dimensional or two-dimensional holographic reconstruction can have a sufficiently high resolution. These requirements also meet conventional light sources whose light radiates through a sufficiently narrow gap. A line-shaped light source can be considered perpendicular to its length as a point. The light is then coherent in this direction and incoherent perpendicular to it. To ensure temporal coherence, the spectrum of the light source must be sufficiently narrowband.

The color information can be monochromatically, time-sequentially or spatially divided into spectral components by filter means. Matrix-arranged, electronically controllable pixels in which e.g. a hologram of the 3D scene or of an object point can be coded, modulate the amplitude and / or phase of the interference-capable light when triggered.

For example, a holographic display for the reconstruction of a colored 3d scene Red, green and blue light sources use time-sequential red, green and blue holograms. The invention can be applied to such a display by mutatis mutandis for each individual color, the intensities of diffraction orders of multiple light sources of this color are superimposed.

The invention may e.g. be used in a holographic display in which the

Light sources, based on one imaging element, for changing positions of

Eye pupil in different combinations of positions and / or number to each other controllable switched.

There are various possibilities for designing and developing the illumination device according to the invention in an advantageous manner. Reference is made to the subordinate to the patent claim 1 dependent claims and to the explanations of the preferred embodiments of the invention with reference to drawings. In the drawings show in schematic representation

1 is a plan view of a simplified representation of a part of a 3D

Scene with a light source, according to the prior art,

FIG. 2 is a plan view of a simplified representation of a part of a 3D

Scene according to the invention,

2a shows an embodiment for generating diffraction orders of two

Light source images in an image plane,

2b shows an embodiment of the reconstruction of an object point, with a

Visibility range with superimposed far-field diffraction patterns, according to the invention,

3 shows a diagram of superimposed intensity profiles in a visibility region which has superimposed diffraction orders of three light sources, according to the invention, FIG.

4 shows an embodiment of a reconstruction of a part of a 3D scene which is coded with a Burckhardt hologram, and

5 shows an example for determining the positions of light sources to be turned on

Illumination device of FIG. 4.

In FIGS. 1 to 5, the same components have been designated by the same reference numerals. The embodiments of the invention described below relate to

Lighting devices, e.g. may have real or virtual light sources, which may also be secondary light sources. Secondary light sources are, for example, controllable apertures of a shutter display, which e.g. be illuminated with an array of conventional light sources. A real approximately punctiform light source can

for example, be a laser.

The invention makes use of the diffraction of light at a matrix of openings, which may be a controllable light modulator in a lighting device, wherein intensities of

Diffraction orders are repeated periodically in a viewer plane. At the position of an eye pupil, an intensity maximum of a diffraction order of a first light source is set as the visibility range.

The size of a visibility area is defined by the pixel pitch p of the controllable spatial light modulator used, by the wavelength λ of the light used and by the distance D of the eye position of a viewer to the pixels of the pixel matrix of FIG

Light modulator with

SB = λ / ρ D

Are defined. The invention is based on the idea with a lighting device a

Visibility area with a superposition of intensities of different

To produce diffraction orders or at least parts of intensities of these diffraction orders of multiple light sources switched on. The positions of the light sources relative to one another can be variably switched on by control elements in order to generate a visibility region at predetermined positions of eye pupils in different observer planes. For at least one imaging element, at least two light sources can be controllably switched on, whose diffraction orders in the visibility region have an overall intensity which consists of a superposition of at least two different intensities. These intensities may be the intensity maximum of a diffraction order of a first light source and the intensity maximum / the intensity maxima of at least one other

Be diffraction order of at least one second switched-light source. Preferably, the intensities of further diffraction orders of switched-on light sources are to be superimposed in each case with the intensity maximum of the visibility range. Since intensities of at least two diffraction orders can be superimposed to form a total intensity in the visibility range, at least two reconstructions of the 3D scene produced at the same location with different intensities can be superimposed on a reconstruction. This reconstruction can be perceived with a brightness equal to the total intensity overlaid intensities in the visibility range.

The term brightness is generally understood to mean the intensity of the radiation acting on an observer. Brightness is the perception of the intensity of light.

With the lighting device according to the invention, a so-called light source tracking can be performed three-dimensionally. A reconstruction of a 3D scene can be seen by multiple viewers when reconstructions e.g. can be generated sequentially for observer eyes of different observers. The observers should stay in one area or in different levels of a viewer's room whose size can be specified by technical parameters of a holographic display. However, the invention is also applicable to other tracking methods, e.g. for imaging elements, which should lead with Elektrowettingzellen light to eye pupils. Embodiments of the lighting device according to the invention will be described in more detail according to the representations of Figures 2 to 5. The intensity maximum of 0.

Diffraction order of a first light source should always be usable as a visibility area. A lighting device should be executable, for example, with real or virtual light sources, wherein the number of light sources LQ, LQ1 to LQn may be per imaging element. Instead of a reconstructed 3D scene, a single reconstructed one is schematically illustrated

Object point shown in the figures. The reconstruction of an object point is also to be understood in the description as a reconstruction of a 3D scene.

FIG. 2 shows a top view of a lighting device with light sources LQ1, LQ2 and LQ3 switched on, as well as an imaging element AE and a visibility region VW. An object point OP2, which is intended to represent a part of a 3D scene by way of example, is coded in at least one area of a controllable spatial light modulator ME with a hologram SH. The light modulator and the light sources LQ1, LQ2, LQ3 are connected to controls CE which are controllable by control systems. For example, three light sources LQ1, LQ2, LQ3 are turned on, which when activated with a

Imaging element AE to be imaged in a viewer plane in which modulated light continues with diffraction orders of the three light sources with periodic repetitions. The light sources LQ1, LQ2 and LQ3 have positions with each other, with which the

Intensities of the diffraction orders of these light sources can form overlays. With the 0th diffraction order of the middle light source LQ2, the visibility range is normally specified, since this diffraction order has the highest intensity (the intensity maximum). The intensities -1 LQ1 of the minus first diffraction order of the light source LQ1 and +1 LQ3, plus the first diffraction order of the light source LQ3 are superimposed in the visibility range with the intensity 0 LQ2 zeroth diffraction order of the light source LQ2 to a total intensity. The superimposition of the intensities of the three light sources continues in further diffraction orders outside the visibility range in the observer plane.

In the visibility range, the intensity maximum of the 0th diffraction order of the light source LQ2 becomes +1. Diffraction order of the light source LQ3 and an intensity of the - 1st diffraction order of the light source LQ1 superimposed. The periodic repetitions of the intensities of diffraction orders occur both with respect to the observer plane and the reconstruction of the object point, e.g. in the form of the object points OP1, OP3. Be per imaging element, the positions or angles of a number einzaltender

Controlled light sources so that intensities of diffraction orders are superimposed, then both in the visibility range intensities are superimposed as well as with the intensities generated reconstructions. A reconstruction of the object point OP2 therefore has three superimposed superimposed reconstructions, one reconstruction of each light source LQ1, LQ2 and LQ3, which can be generated at different intensities at the same location. The same applies to other object points of a 3D scene OP1 and OP3.

The eye pupil AP can perceive a reconstruction of a 3D scene with a corresponding brightness in the visibility region that corresponds to the overall intensity of the superimposed reconstructions.

It is preferable to use light sources which emit each coherent light of sufficient coherence, but the different light sources are not coherent with each other. Then the intensities of the respective diffraction orders of the individual light sources add up in the visibility range. A viewer with his eye in the visibility area then sees a correspondingly brighter reconstruction than would be the case with a single light source.

This embodiment of a lighting device can be applied in a holographic display in which in the spatial light modulator a corresponding

calculated hologram of a 3D scene is encoded with complex values and in which the reconstruction of the 3D scene has overlays of three reconstructions. The thus reconstructed 3D scene is perceptible with a brightness in the visibility range which corresponds to the superimposed total intensity in the visibility range. Another one

Embodiment will be later with reference to a Burckhardt coding with Figs. 4 and 5

described.

FIG. 2 a shows two switched on light sources LQ 1, LQ 2 and one imaging element AE, with the light sources LQ1, LQ2 are imaged in an imaging plane, wherein the light is diffracted at a matrix G1 of regularly aligned openings, so that

Light source images in periodic continuation in the imaging plane arise. The matrix G1 acts like a diffraction grating with a multiplicity of openings, which in their arrangement correspond to a pixel structure of an SLM in which no complex values of a 3D scene

are inscribed.

The light sources are at a predeterminable distance from each other and / or with a

predetermined radiation angle turned on, so that the intensities of the light source images in the image plane offset from each other and are superimposed. In the example, the intensities are offset from one another by a diffraction order. There may be more light sources depending

Imaging element can be switched on with predeterminable combinations of distances and / or emission angles, so that superimpositions with further intensities of the further switched-on light sources can arise in different viewing planes.

Fig. 2b shows in a simplified representation a lighting device with two light sources LQ1, LQ2 for e.g. a holographic display.

Light sources LQ1, LQ2 of a light source array, which can be switched on with control elements CE, are assigned to an imaging element AE for imaging the light sources LQ1, LQ2. The light sources LQ1, LQ2 in the array have two-dimensional data that can be used to determine their positions in the array. The position data can be used to switch on the light sources for a determined position of eye pupils.

The light source LQ1 should be arranged centrally to the optical axis of the imaging element AE, the light source LQ2 is arranged offset by a distance d. When controlling the

Light sources LQ1, LQ2 illuminates the light a controllable spatial light modulator ME, in which a hologram SH is inscribed for an object point as part of a 3D scene. The control element CE also controls the light modulator ME or writes the hologram SH into the controllable spatial light modulator ME. In place of the light source images of FIG. 2a, in a viewer plane, which is the image plane in FIG. 2a,

Intensity distributions IV1, IV2 of diffraction orders of the inscribed hologram SH, with which a visibility range at the position of an eye pupil AP can be generated. The observer plane is the far field of the light sources, so that the intensity distributions IV1, IV2 are also referred to as far field diffraction patterns.

If both light sources LQ1, LQ2 are switched on activated, then the visibility region is generated at the eye pupil AP with a total intensity which is the intensity maximum of 0. Diffraction order of the first light source LQ1 having a part of the intensity of +1. Diffraction order of the second light source LQ2 is superimposed.

In the field of visibility, a reconstruction of the object point OP1 is visible with the eye pupil AP, which is a superposition of the with the intensity of the 0th diffraction order and the +1.

Diffraction order is generated reconstructions. With a superimposition of the intensities in the visibility region, the object point OP1 is to be seen with a brightness which is the same as that of the object

Total intensity in the visibility area is equivalent. As a result of this superimposition, the overall brightness of a reconstruction can be increased in comparison with the use of only one light source per imaging element AE.

Depending on the width of the imaging element AE, more than two light sources per imaging element can be switched on to trigger a reconstruction. The light sources to be switched on may also have such a distance from each other that light source images in the observer plane are offset from one another by, for example, 2 or 3 or a different number of diffraction orders. The positions of light sources to be driven may be corresponding to a current position of eye pupils for generating the light source

Visibility area software-programmed in storage means present. Furthermore, in the exemplary embodiment, the light sources for generating the visibility region can be variably activated at positions which are dependent on a 1D or 2D coding of the 3D scene in the vertical or / and horizontal direction.

The determination of a distance d of the light sources to be switched on relative to one another or the position of the light sources to be switched on is described below. The size of the

Visibility area in which the 3D scene is reconstructed was defined above with SB = λ / ρ D. A diffraction order of the light modulator ME then has the distance D

Extension D * K / p.

According to the prior art is at a holographic display with at least

Light source array, imaging elements and SLM the light source imaged in the observer plane. Further light sources to be switched on are to be arranged according to the invention in such a way that their light source image in the observer plane is shifted by an integer multiple of an interval of the extension of the diffraction order of the pixel matrix, ie by N * D * λ / ρ, where N is an integer.

According to the geometric optics applies to the light source and the imaging element a

Imaging equation. The magnification of a lens is generally defined as the factor Image BW by object size GW. Thus, the light source images in the observer plane for two light sources so by N ^* D ^* λ / ρ can be offset from each other, the light sources must have a lateral distance GW / BW ^* N ^* D ^* λ / ρ to each other. In general, the imaging element is close to the light modulator ME, then the image width BW is approximately equal to the observer distance D, and the equation simplifies to N ^* GW ^* λ / ρ for the distance between two light sources to be switched per imaging element. The distance between the light sources to each other still depends on the wavelength of light. For a holographic color display, different distances for red, green and blue light sources would have to be selected to reconstruct a bright 3D scene.

In general, a controllable spatial light modulator may also have rectangular pixels with a different pixel pitch in the horizontal and vertical directions. Then, in the above equations, optionally for p, insert a horizontal or a vertical pitch to

determine horizontal or vertical distances of the light sources.

The light sources of the array can be arranged vertically one above the other to the

Crosstalk other diffraction orders in a neighboring eye of the observer does not increase. In a 2D coding, driving the light sources in two dimensions, e.g. in the form of a cross, beneficial.

If the array of light sources used in combination with a lenticular of superposed lenses, for each imaging element, that is, for each lens of the lenticular, several light sources are switched on at least vertically controlled. For each imaging element, at least two light sources can be switched on vertically one above the other or horizontally next to one another, with pixel columns or pixel lines of one pixel

Shutter displays are controllable as strip-shaped secondary light sources.

In a further embodiment, light sources for each lens of the lenticular can be controlled, which are arranged horizontally and vertically in the form of a cross.

For example, the lighting device can light sources with a regular

Have arrangement. It may, for example, have a light source array with advantageously striped or punctiform light sources. Strip-shaped light sources can be formed by column or line-wise control of the light sources per imaging element for a strip-shaped illumination when an optical imaging means with strip-shaped imaging elements, such as a lenticular, to be used in the beam path. The imaging elements should have a given number of individual For example, light sources can form a visibility area at different positions. The hologram of an object point to be reconstructed can optionally remain fixedly coded or re-encoded in observer tracking. Because the position of the

Reconstructing object point can change depending on the position of the eye pupil, intensities of at least two orders of diffraction of the switched light sources, which are assigned to an imaging element, can be superimposed on this eye position. The order of diffraction fixed for reconstructing the object point for one of

Light sources preferably has the greatest intensity for the reconstruction produced in the

Comparison to other diffraction orders. The superposition of the reconstruction of several light sources corresponds to an addition of the intensities at the same location.

Since intensities of at least two diffraction orders can be superimposed to a total intensity at the location of the visibility area, these intensities at the same location can be used to create and superimpose at least two reconstructions of the 3D scene, with the total intensity of the visibility area as a generated reconstruction of the 3D scene with corresponding brightness is perceptible in the eye pupil. This reconstruction of the 3D scene can be perceived in the field of visibility with a brightness that the

Total intensity in the visibility range. Fig. 3 shows a diagram of the intensity distributions of the diffraction orders of

Light source images of three switched-light sources of a lighting device according to the invention, and the envelope or their superposition of the intensities in the far field, which corresponds to the location of the visibility range VW. The envelope is given for a single pixel with a fill factor or aperture of 70% of the pixel pitch in one direction and with a transmission path of a rectangular pixel. The graph refers to the three light sources LQ1, LQ2, LQ3 shown in FIG. The limits of the visibility range VW, which is set to a diffraction order, are indicated in FIG. 3 in the middle of the 0th order of diffraction with vertical lines. The intensity maxima of the three intensity distributions 11, 12, 13 of the light sources LQ1, LQ2, LQ3 are approximately equal in size and offset from one another at the spacing of a diffraction order. The

Intensity maximum of two light sources LQ1, LQ3 is outside the

Visibility region. The combined curve of the envelope shows a beneficial increase in intensities to a total intensity (one increased on average over the visibility range by 50%

Overall intensity), as well as a more consistent course over the visibility range Total intensity compared to the single intensity 12 from the light source LQ2.

The envelope indicates the total intensity of three incoherently added intensities 11, 12, 13 of switched-on light sources LQ1, LQ2, LQ3. According to the graph, the

Visibility range for three switched on light sources LQ1, LQ2, LQ3 (ie 300% intensity of the light sources) a total intensity of 150% compared to the intensity of a single light source on. Although the efficiency of the power of the switched-on light sources decreases, the brightness of a reconstruction of a 3D scene, which in the

Visibility range is perceptible with an eye pupil.

The invention further comprises a holographic display comprising a lighting device with a light source array according to claim 1, as well as imaging elements and a controllable spatial light modulator ME into which a hologram of a 3D scene can be inscribed, which in a visibility region comprises at least two

superimposed reconstructions with an overall intensity can be generated, which results from added intensities of at least two superimposed diffraction orders of light source images switched light sources, wherein for changing the position of the visibility range, a number of light sources per imaging element with control systems can be variably preset activated or deactivated. The controllable spatial light modulator preferably has a pixel matrix.

The imaging elements may be a regular lens array of a lens array. The control systems include controls for e.g. the light sources of

Lighting device for generating a visibility area are controlled, or controls with which the light modulation of a light modulator is controllable. The

Positional tracking of observer eyes can be performed continuously to constantly generate a visibility area for currently detected positions of eye pupils. A position finder acquires the position data of the eye pupils of a viewer. The

Control systems send and receive data to and from the controls of the individual display components using sensing and control systems of the present invention

holographic displays. Real or virtual light sources, which can be switched on individually controllable side by side in the horizontal and / or vertical direction, and which are assigned to an imaging element can, for example, one-dimensional with respect to their lateral distance from each other or the radiation angle, in they illuminate the controllable light modulator, are combined so that the diffraction orders assigned to the individual light sources are offset in an observer plane by an integer multiple - an integer greater than or equal to 1 - the interval of a single diffraction order to each other.

If a 3D scene consisting of at least one object point is to be reconstructed with the holographic display, first the positions of the eye pupils are to be determined in order to generate a visibility region for these positions. Of a

Position detection system which constantly detects the position of eye pupils transmits to control systems the position data with which controls in the lighting device in a light source array turn on a predetermined number of light sources. With the

Control elements are switched with a software program, the light sources per imaging element, which can be generated for the position of the eye pupil of the visibility range, each with an intensity maximum, the intensities for

Visibility area are superimposed in the observer level. The intensity of the

Visibility area is superimposed with intensity of light sources switched per imaging element in the visibility area to a total intensity. The light of the light sources is influenced by the controllable light modulator with the hologram of the encoded 3D scene, whereby a reconstruction of the 3D scene can be generated, to which superimposed with the individual intensities reconstructions are superimposed.

When changing the position of the observer, the control systems, depending on the transmitted position data of the observer, light sources are controlled such that with new control values, a reconstruction of the 3D scene at the position of a newly generated

Visibility area can be seen. The positions of the light sources to be switched on are to be selected so that intensities of at least part of a diffraction order of a first light source with at least part of a further diffraction order of at least one second light source can be superimposed both for the reconstruction of the object point and in the visibility region of the observer plane.

The invention is optionally in holographic displays with different types of

Light modulators (for example, amplitude or phase modulator) and different coding methods applicable, such. with a coding of complex values, one

Phase coding, a Burckhardt coding, etc. In the coding process, it should be noted that the diffraction orders offset in relation to each other in the observer plane in the

Visibility area have superimposed periodic repeats with a modulated 3D scene, and not such areas, with which, for example, in Burckhardt coding spatially inverted reconstructions are generated.

The Burckhardt coding will be explained with reference to FIGS. 4 and 5.

FIG. 4 schematically shows a controllable light modulator ME into which a hologram SH of a 3D scene illuminated by a single light source LQ is coded.

In the Burckhardt coding, a complex value is encoded in each case in three pixels of the light modulator in the form of amplitude values.

The light modulated with the hologram SH is focused to a position at which an object point OP can be reconstructed in FIG. 4, the light generating a visibility region for an eye pupil AP from this position. In a visibility region X, a reconstruction of a 3D scene is visible for an eye pupil. An eye pupil in the area Y would not perceive any holographic reconstruction, an eye pupil in the area Z would see a 3D scene with the object points (not shown) lying in front and behind with respect to the depth. are reversed. An eye pupil AP in subarea Z in FIG. 4 would perceive the reconstructed object point behind the display, while it would be perceptible in the visibility region X in front of the display. The entire array X, Y, Z repeats periodically in the observer plane.

A part of the light of the light source LQ is in the viewer plane to the point PY in the

Subarea Y focused. This corresponds to a light source image, which in the case of Burckhardt coding is also visible in the hologram inscribed in the light modulator. This light source image repeats periodically in further diffraction orders.

Only in the visibility region X can a reconstruction of the object point OP be perceptible with an eye pupil. This reconstruction can e.g. be superimposed with a reconstruction that can be generated with an intensity of another switched-light source. The intensity of subregion X should be e.g. according to Fig. 5 with the repetition of the partial area X 'or Y' of another light source which can be superimposed e.g. Having intensities in the sub-areas X ', Y' and Z 'in periodic continuation in the observer plane.

The distance of an imaging element associated light sources in one

Lighting device of the invention is to be selected in this coding so that for a light source of the partial area X in the observer plane preferably superimposed with a repetition of the partial area X of another light source. Thus, intensities of two diffraction orders of two different light source images can be superimposed, and two with Object reconstructions generated at these intensities are superimposed into a single reconstruction, which is thereby perceptible with a brightness corresponding to the total intensity.

In order to find the position of the light sources to be switched on, first of all, as in FIG. 5

is shown schematically, the light path from the light source image PY in the subregion Y are traced through the center of the hologram SH and further through the imaging element AE to the light source LQ2 of the light source array. Accordingly, the light path of the

Light source images PY 'and PY ", the periodic repetitions of PY traced by the same position in the hologram as for PY and by the imaging element AE., This leads to the position of the light sources LQ1 and LQ3 The switched light sources LQ1 to LQ3, for example, columns columns of light sources of a light source array if lenticular lenses are to be used as imaging elements AE The determination of the light sources LQ1 and LQ3 as a function of the eye position can be programmable by software or stored, for example, in the form of a look-up table.

Here, according to the invention, a part of a diffraction order (namely, the part X of the diffraction order in the observer plane which extends in total over the regions X, Y and Z) of an activated light source, e.g. LQ1, and the same part of at least one other, different diffraction order of another light source, e.g. LQ3, one

Overlay in the visibility area.

Particularly advantageous is the invention in one embodiment with a

Lighting device can be realized using a shutter display, in which the

light sources according to the invention are secondary light sources. In this illumination device, light sources can be generated with very little effort, in that rows or columns of pixels in the shutter display per imaging element can be controlled transparently. For example, the spacing of the individual lines to be switched on may be slightly more than 2 mm in order to produce a visibility area with superimposed intensities using a shutter display, as well as a reconstruction of a 3D scene with superimposed reconstructions in it

Visibility area visible. The power of the individual light sources of the primary lighting unit would not have to be changed. The reconstruction of a 3D scene can be seen with the same primary illumination with a greater brightness.

Light sources of the illumination device can be switched on in a predeterminable number, and / or predeterminable positions to each other and / or predeterminable radiation angles variable controllable. This is true if, according to the invention, at varying positions of eye pupils of at least two observers in different observer planes, a visibility region to be viewed for viewing a reconstruction of a 3D scene. By controlling different combinations of light sources to be switched on per imaging element, the visibility region with the same overall intensity can be generated at different positions, whereby a superimposition of reconstructions, which can be generated with additive intensities, results in a single reconstruction.

Another embodiment of the invention may be used with a holographic display having an electrowetting unit for deflecting light to changing positions of eye pupils. Such a display thus includes one

Lighting unit, at least one imaging element, a light modulator, and a controllable deflection, for example, an array of Elektrowetting prisms for viewer tracking.

For such an arrangement, a deflection angle is set on the controllable deflection element such that the visibility range of a pupil position of a viewer is tracked. Again, several light sources can be turned on so that in

Visibility range of a superposition of the intensities of a diffraction order of a first light source with at least one further diffraction order of at least one second light source results. The position of the light sources can also be determined here by the optical path of light source images in the observer plane through the optical system

is traced back. In particular, the distance of the light sources from one another would change with the position of the visibility region due to the non-linearities of the adjustable prism angles relative to the deflection angles.

Claims

claims

1 . Lighting device with a light source array (LQ) having light source array for a holographic display, which has a controllable spatial

Light modulator and imaging elements, each having a number of

is associated with controllable light sources of the light source array, whose light source images are repeated periodically with diffraction orders in a viewer plane, in the one

Visibility is set with an intensity maximum, with which a reconstruction of a written in the controllable spatial light modulator 3D scene can be generated, the light sources are activated with controls for a detected position of the eye pupil of a viewer, characterized in that

for at least one light-emitting element (AE), at least two light sources (LQ) are activatable, with which a visibility range can be generated upon actuation, which has an overall intensity (I) from a superposition of the intensity maximum of a diffraction order with a part of an intensity maximum of at least one further diffraction order, wherein reconstructions generated with these intensities at the same location are superimposable, which is a reconstruction of the 3D scene with one of the total intensity in the

Visibility area corresponding brightness at a position of an eye pupil (AP) can be seen, with which the position of the controllably activatable light sources (LQ) can be specified.

2. The lighting device according to claim 1, wherein the variable positions of light sources to be switched on (LQ, LQn) can be generated in different viewing planes with intensities superimposed visibility ranges whose position in the respective

Viewer level is variable, with a reconstruction is visible in the respective position with a brightness that overlaid a total intensity (I) of the same place

Reconstructions of the 3D scene corresponds.

3. Lighting device according to claim 1 or 2, are arranged in the controls (CE), light sources (LQ) with a number, and / or positions to each other and / or radiation angles, which are predetermined with the position of the visibility region to be generated, whose position with position data detected eye pupil (AP) is given.

4. Lighting device according to one of claims 1 to 3, wherein at a

Imaging element (AE) switched light sources (LQ) have a distance to each other, with the intensity maxima of the diffraction orders of the light source images to Intensity maximum of the visibility range are offset by an interval equal to or greater than a multiple greater diffraction order in a viewer plane to each other.

5. Lighting device according to one of claims 1 to 4, wherein the positions of the light sources (LQ) for generating the visibility range depending on a 1 D or 2D

Coding of the 3D scene in the vertical and / or horizontal direction are driven variable switched on.

6. Lighting device according to one of claims 1 to 5, wherein the

Intensity maximum of the visibility range with intensities of at least two other switched light sources (LQ) is superimposed, with the intensities superimposed

Intensities of a part of a diffraction order or the entire diffraction order and the same part of at least one other diffraction order or the whole

Have diffraction order.

7. Lighting device according to one of claims 1 to 6, wherein a

Total intensity (I) of a visibility level for a viewer level with a

programmed far field diffraction pattern can be specified for the light sources (LQ) each

Imaging element (AE) can be switched on with a programmed switch-on pattern of control elements.

8. Lighting device according to one of claims 1 to 7, wherein the array of light sources comprises real or virtual light sources.

9. Holographic display having a lighting device according to at least one of the preceding claims.

10. Holographic display with a lighting device with controllably switchable light sources according to at least one of claims 1 to 8, the at least

Having imaging elements (AE) and a controllable spatial light modulator (ME) with a hologram of a 3D scene, wherein the positions and / or radiation angle of the light sources (LQ) are switched to each other controllably switched on, and wherein the

Control of light sources (LQ) depending on a respective position of the eye pupil (AP) in front of the controllable spatial light modulator (ME) for generating one each

Visibility range, with which the 3D scene is at least twice superimposable constructed.

1 1. Holographic display according to claim 9 or 10, the imaging elements (AE) lens elements of a lenticular array, each of which light sources (LQ) are assigned, which can be switched to generate the visibility area variably controlled, wherein a 3D scene in the controllable spatial light modulator (ME) preferably one-dimensional is inscribed.

12. Holographic display according to claim 10, wherein the positions of the light sources to be switched on (LQ) to each other, or their emission angle, the wavelength of the

Reconstruction of the 3D scene depending on the light to be used.