DE102008040581B4 - Controllable light modulation device - Google Patents

Controllable light modulation device

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Publication number
DE102008040581B4
DE102008040581B4 DE102008040581.7A DE102008040581A DE102008040581B4 DE 102008040581 B4 DE102008040581 B4 DE 102008040581B4 DE 102008040581 A DE102008040581 A DE 102008040581A DE 102008040581 B4 DE102008040581 B4 DE 102008040581B4
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Germany
Prior art keywords
light
grid
modulator
modulation device
eye
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DE102008040581.7A
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German (de)
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DE102008040581A1 (en
Inventor
Dr. Fütterer Gerald
Dr. Häussler Ralf
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SeeReal Technologies SA
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SeeReal Technologies SA
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    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03HHOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00Holographic processes or apparatus using light, infra-red or ultra-violet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/22Processes or apparatus for obtaining an optical image from holograms
    • G03H1/2294Addressing the hologram to an active spatial light modulator
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03HHOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00Holographic processes or apparatus using light, infra-red or ultra-violet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/02Details of features involved during the holographic process; Replication of holograms without interference recording
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03HHOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00Holographic processes or apparatus using light, infra-red or ultra-violet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/22Processes or apparatus for obtaining an optical image from holograms
    • G03H1/2286Particular reconstruction light ; Beam properties
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03HHOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00Holographic processes or apparatus using light, infra-red or ultra-violet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/02Details of features involved during the holographic process; Replication of holograms without interference recording
    • G03H2001/0208Individual components other than the hologram
    • G03H2001/0224Active addressable light modulator, i.e. Spatial Light Modulator [SLM]
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03HHOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00Holographic processes or apparatus using light, infra-red or ultra-violet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/22Processes or apparatus for obtaining an optical image from holograms
    • G03H1/2202Reconstruction geometries or arrangements
    • G03H2001/2236Details of the viewing window
    • G03H2001/2242Multiple viewing windows
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03HHOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H2226/00Electro-optic or electronic components relating to digital holography
    • G03H2226/05Means for tracking the observer

Abstract

A controllable light modulation device having a light modulator matrix (SLM), in which modulator cells are arranged in a first grid (R1) and diffracting coherent light beams arriving from light sources which are projected into a defined visibility range (SB) at a determined eye position (AP n) in a viewer plane (BE1 , BE2) having light source images in a second grid (R2), the defined visibility area (SB) being positionable between two light source images (LB), and control means (CM) for controlling a position detection system (PE) and the light modulation, characterized in that the modulator cells in the first grid (R1) are arranged such that in the observer plane (BE1, BE2) with the diffracted light beams, the second grid (R2) can be generated with areas without or with very low intensity at locations of observer eyes, which are adjacent to the positioned visibility region (SB), the regions He is generated with a rotational movement of the light modulator matrix (SLM), which is controllably rotatable with a maximum angular range, can be generated.

Description

  • The invention relates to a controllable light modulation device which has a light modulator matrix with modulator cells arranged in a first raster and is connected to control means. The modulator cells modulate the coherent light beams emitted by light sources, which are superimposed within a defined visibility range in a viewer plane in a determined observer eye. The observer plane contains light source images arranged in a second grid, wherein the visibility region is positioned between two light source images.
  • The controllable light modulation device is applicable in a holographic display, which can be configured as a direct view or projection display. A 3D scene encoded in the light modulator matrix can be holographically reconstructed with coherent light for at least one observer. The observer sees the reconstruction when his eyes coincide with the visibility area in the observer plane created for his position. If the observer changes his distance from the display or moves laterally in front of the display, he is tracked to the visibility area. For this purpose, a position detection system determines the observer's eyes, and thus also the deflection angle of the light bundles from the optical axis of the display device to the observer eye, and updates the position data. The position detection system is connected to the light modulator via control means.
  • The visibility area is generated in a viewer plane before the display by superposition of light bundles and referred to in other documents of the applicant as Viewer window. If it is as large as an eye pupil, the right and left views of the holographic reconstruction of the scene are time sequentially generated for each eye, and the viewer sees the entire reconstruction with the correct view of his eye position. The range of visibility could also be so large that it contains both eyes at the same time. Diffraction of light at the modulator cells produces different orders of diffraction, which are visible in the observer plane as intensity maxima and represent the images of the light sources. They have a grid which is predetermined by the grid of the modulator cells. The visibility range of a detected observer eye is specified for a region between two adjacent diffraction orders and thus two adjacent light source images. This prevents that an intensity maximum lies in this eye and disturbs the viewing of the reconstruction. In contrast, the shape of the aperture of the modulator cell determines the distribution of the total intensity of a light source to its generated individual light source images.
  • In 1 the influence of the intensity of the light source images on two pairs of eyes positioned at different distances from the light modulator matrix is shown. In general, in the invention, the 0th diffraction order coincides approximately with the optical axis of the display device. The visibility ranges SB are usually between the 0th and the +1. or -1. Diffraction order. Since the neighboring eye is located laterally and / or axially in more distant, higher orders of diffraction m, correspondingly weaker intensities occur there. It comes to a crosstalk of the intensities in the neighboring eye. However, the crosstalk is only visible and disturbing if the intensities of these orders of diffraction m exceed a certain value, for example 5% of the intensity present in the field of visibility of the currently detected eye. On the other hand, as the viewer becomes closer to the display, the pitches of the light source images also change, and the viewer window becomes larger. As a result, there is less crosstalk for the eye position AP 1 than for the eye position AP 2. The diffraction pattern of the entire light modulator results from the superimposition of the diffraction patterns of the individual modulator cells in the visibility range of the currently determined eye. The position of the neighboring eye is also determined, but this eye currently does not receive a visibility area.
  • The crosstalk of the intensities or the perception of diffraction orders in an eye adjacent to the currently generated visibility region can be reduced or completely suppressed, for example by pixel apodization. The term "pixel" is to be understood here as a modulator cell. Pixel apodization can be performed by various methods using an apodization profile t SLM pixel (x, y). If the filling factor FF of the individual modulator cell is, for example, FF> 0.5 and the area of the modulator cell is not too small, a targeted selection of the course of the transmission of the individual modulator cell can ensure that the intensities of the diffraction orders do not disturb the neighboring eye. When using optical components which are intended to realize a tracking function in the display and light bundles track the observer's eyes within a large angular range, this measure alone is not sufficient. By using a light modulator with larger modulator cells, an improvement would still be achieved. These modulator cells produce diffraction patterns with more closely spaced diffraction orders, thereby focusing the intensities of the sub-maxima into a narrower space. However, using larger modulator cells results in a holographic display that the visibility range for certain wavelengths, eg for λ = 450 nm, becomes too small for a safe tracking.
  • When using electrowetting cells with adjustable microprisms for light beam deflection, the incident light bundles are increasingly compressed with increasing deflection angle. The fill factor FF of modulator cells associated with the prism cells appears to be reduced, although the effective effective area of a modulator cell does not change. This disadvantage means that the intensities of the light source images are distributed to a larger area with increasing deflection, so that the intensity components also increase in the secondary maxima of the adjacent diffraction orders or light source images and are perceived as disturbing crosstalk in the neighboring eye. Realizing larger deflection angles for tracking the visibility area when moving a viewer is prevented.
  • The WO 2007/073731 A1 describes a controllable light modulation device with modulator cells arranged in a raster, which direct the light diffracted at the light modulator to a specific eye position.
  • From the WO 2004/044659 A2 a light modulation device is known, wherein the arranged in a first grid light modulator cells are imaged in a viewer plane in a second grid. Crosstalk of the individual raster sections at the location of the observer's eye is avoided by virtue of the fact that higher diffraction orders have an intensity minimum at locations of observer eyes which are adjacent to the positioned visibility region.
  • The object of the invention is to design a controllable light modulation device with which the occurrence of light source images in viewer eyes, which lie adjacent to viewer eyes with a visibility region, is largely suppressed in a viewer plane. Thereby, preferably in a holographic display device, the perception of a reconstruction, which can see a plurality of viewers in their associated visibility areas, is improved. In general, to eliminate the crosstalk of the intensities, measures can be taken in the object plane or in the image plane. A combination of measures on both levels can solve the problem. The present invention relates to measures initiated directly in the object plane to influence the location of the light source images in the image plane so as not to disturb adjacent viewer eyes. Object level is here the level of the light modulator to understand.
  • The invention is based on a controllable light modulation device with a light modulator matrix in which modulator cells are regularly arranged in a first grid and modulate coherent light bundles emanating from light sources with encoded values which are superimposed in a determined eye position in a sequentially generated, defined visibility region of a viewer plane. In the observer plane, the images of the light sources are also shown in a second grid whose position and grid dimensions also depend on the grid of the modulator cells of the light modulator matrix. The defined visibility area is positioned between two light source images. Furthermore, the light modulation device comprises a position detection system for the observer eyes to be determined and control means which control the light modulation.
  • The object is achieved according to the invention in that the modulator cells in the light modulator matrix are arranged in the first raster such that the light bundles diffracted at the modulator cells generate regions without or with very low intensity of the light source images in the observer plane in the observer plane in the observer plane, which are adjacent to the positioned visibility area. The first and second rasters are preferably generated as a function of the system components used or for a maximum angular range or for a predefined depth of the observer's eyes to the light modulator matrix.
  • In a first embodiment, the light modulator matrix having a checkerboard-like first grid is designed to be rotatable about its system axis, wherein the control means controls the rotation within a defined angular range depending on a signal of the position detection system. As soon as the rotational angle of the light modulator matrix to be set is greater than the defined angular range, a coding means receives control signals for changing the coding. The coding means expediently provide correction values for changing the coding, which are precalculated and stored in a look-up table as a function of the angle of rotation and the position of the respective viewer's eye. The correction values are precalculated in such a way that the rotation of the coded object resulting from the rotation of the light modulator matrix is compensated such that the observer does not perceive the rotation.
  • In a second embodiment of the light modulator matrix, it has a first raster with adjacent cells symmetrically about one cell half mutually staggered, preferably quadrangular, modulator cells on.
  • In a third embodiment, the light modulator matrix has a first grid with modulator cells, which are arranged hexagonally and are preferably hexagonal. Optimal information content of the modulator cells is obtained by the viewer's eyes, even if the visibility range is hexagonal.
  • In a further embodiment, the light modulator matrix can comprise coded sub-holograms of individual object points of a three-dimensional object, which can be shifted in the light modulator matrix for changing the coding. The shift takes place with coding values which compensate the rotation of the light modulator matrix again. The three-dimensional object is perceived in the reconstruction space as a fixed reconstruction, the rotation does not appear visibly.
  • In a further embodiment of the controllable light modulation device, which has one of the first raster according to one of the preceding embodiments, the first raster in the horizontal direction is additionally compressed in such a way that the light bundles diffracted at the modulator cells generate a visibility region which corresponds to the statistically dynamic form of the residence of one Eye pupil is adjusted during eye movements in the visibility area. The invention may suitably be embodied by a variable magnification imaging optical system arranged in the optical path, which is actuated by actuators controlled by control means. As a result, the distances of the light source images in the second raster can be scaled proportionally to each other. The imaging optical system with variable magnification can also be combined with the previously described embodiments of the invention in order to additionally make a scaling if necessary.
  • In a further embodiment, the embodiments according to the invention may additionally contain large-area optical deflection means which are actuated by control means controlled further actuators. As a result, the second raster can be additionally displaced laterally virtually over a comparatively relatively large area compared to the change in the position of the light source images.
  • A further embodiment of the controllable light modulation device can advantageously have a deflection field which deflects and superimposes the light bundles on a respective determined observer eye in the visibility region, the control means controlling the adjustment of the deflection in a predetermined angular range. The deflection field preferably contains, according to the electrowetting principle, functioning matrix-shaped deflection cells with at least one interface, wherein the interfaces are adjusted by means for controlling electrodes with an angle of inclination. The angle of inclination is determined by the determined eye position.
  • With the mentioned embodiments it is achieved that the generated light source images do not strike the eyes adjacent to the visibility range of a determined current eye position. A major advantage of the invention is further that the embodiments do not require additional optical means in the light path to suppress crosstalk.
  • The invention also relates here not listed grid of modulator cells that solve the above problem in a comparably designed light modulation device. The controllable light modulation device can be designed to be transmissive or reflective. The invention further comprises a holographic display device having a controllable light modulation device according to at least one of the embodiments.
  • The various embodiments of the invention are applicable in a holographic display device, preferably in a projection structure. Such formed display devices are versatile, e.g. in vehicles, home video equipment, large format advertisements, airplanes, etc.
  • The invention will be explained in more detail with reference to embodiments. In the accompanying drawings show in a schematic representation
  • 1 Propagation of a light beam with higher diffraction orders, which strike two pairs of eyes positioned at different distances from the light modulator matrix,
  • 2a . 2 B a light modulator matrix in a first embodiment and the position of two adjacent eyes in the periodic continuation of light source images in a grid,
  • 3a . 3b a light modulator matrix in a second embodiment and the position of two adjacent eyes in the periodic continuation of light source images in a grid,
  • 4a - 4d different rasters R1 of intensity distributions of individual modulator cells of the light modulator matrix and the corresponding arrangements of modulator cells in the grid R1,
  • 5 a hexagonal arrangement of hexagonal modulator cells with the largest possible eye pupil of a viewer's eye,
  • 6 the grid R1 of 4d with modulator cells compressed in the horizontal direction, and
  • 7 a range of visibility adapted to the statistically dynamic shape of the eye pupil's presence during eye movement in the area of visibility.
  • The controllable light modulation device comprises at least one controllable light modulator, coherent light emitting light sources, optical imaging and / or deflection means, a position detection system and computing and control means for executing and controlling the individual components and processes. Shown in the 1 to 4 but only the components necessary for understanding the invention.
  • Light sources illuminate, in a known manner, a light modulator matrix which has a regular arrangement of modulator cells in a raster, completely with coherent light. When passing the light modulator matrix, the light is modulated with encoded hologram values, for example a 3D scene. The light beams emanating from all modulator cells generate images of the light sources in a viewer plane, which likewise lie in a grid. This raster is not identical to the raster of the modulator cells, but is dependent on the arrangement of the modulator cells and the imaging behavior of the optical imaging and deflection means in the overall system. In the document, the regular arrangement of the modulator cells in the light modulator matrix is referred to as first grid R1 and the arrangement of the imaged light sources in a viewer plane as second grid R2.
  • To understand the invention, the 1 , which has already been briefly explained in the prior art, explained in more detail here. A coherent light beam incident on a modulator cell of the light modulator matrix SLM propagates further in the direction of the viewer's eyes. The direction is indicated by an arrow. After passing through the light beam is bent and continues in space with different orders of diffraction m periodically. By way of example, a range of m = ± 4 diffraction orders is shown. In the light path, two pairs of observer eyes with the eye positions AP 1 and AP 2 are positioned at different distances within a predetermined area in front of the light modulator matrix SLM. It is assumed that the eyes of a viewer lie in a horizontal plane, so the head is not held at an angle. The diffraction orders m appear in the corresponding viewer planes BE 1 and BE 2 as light source images, which periodically continue there in a grid with different intensities. The light source image itself has the highest intensity in the zeroth diffraction order as the main maximum. The continuations of the light source images, ie the secondary maxima, have periodically decreasing intensities. The secondary maxima are known as the higher diffraction orders. In a holographic display in which the light sequentially generates a defined visibility area SB for each observer's eye, the secondary maxima of the defined visibility area SB of the detected eye usually have a disruptive effect in at least one adjacent eye.
  • The diffraction orders have among themselves the diffraction angle θ m, n , which results from the grid equation. It characterizes the dependence of the position of the light source images on the angle of incidence of the light bundles. By way of example, the diffraction angle θ 1 is shown. The grating equation is sin (θ m) = mλ / (nΛ) + sin (θ 0), where m is the number of orders of diffraction, λ the wavelength of the incident light, n the refractive index of the surrounding medium, Λ is the grating period, and θ 0 is the angle of incidence the light bundles are.
  • The required position data for each eye position AP 1 and AP 2 determines a position detection system PE successively and forwards them to the control means CM. The position data defines a visibility area SB for this position.
  • It can also be seen that, for different distances of the observer's eyes from the light modulator matrix SLM, the spacings of the light source images in the corresponding observer planes change proportionally to one another. At the eye position AP 1, the position data of the right eye are determined and to the corresponding visibility range SB between the 0 and the -1. Diffraction order in the observer plane BE 1 generated. The adjacent left eye of the eye is the intensity of the -4. Diffraction order taken. At the eye position AP 2, the position data of the left eye are determined and a visibility range SB is generated for this eye. The right eye is hit here by the brighter intensity of the 3rd order of diffraction. In both positions there is a crosstalk of the intensities in the visibility range of the neighboring viewer's eye. In this case, the viewer further away in the viewer plane BE 2 is more disturbed than the viewer who is closer to the light modulator matrix SLM. The visibility areas SB for the adjacent eyes are generated sequentially.
  • The 2 B shows in a schematically illustrated section the periodic continuations of the light source images LB after diffraction at the modulator cells, which in the light modulator matrix SLM in a checkerboard pattern R1 (FIG. 2a ) are arranged. The light source images LB continue in a grid R2 quasi in the form of a cross, their position resulting from the checkerboard pattern R1. If a visibility range SB is generated for the currently determined eye position AP 1, then 2 B the adjacent eye is impaired at the eye position AP 1 ', for example, by the intensity of the 4th diffraction order. The intensities of the light source images LB decrease with increasing distance to the 0th diffraction order. But they are still perceived by the neighboring eye as a disorder.
  • Since the interfering light source images in the neighboring eye are to be eliminated, the invention provides for a change in the position of the grid of the light source images preferably to be realized by measures in the object plane. The 3 and 4 describe such solutions.
  • In a first exemplary embodiment, the light modulator matrix SLM is designed to be variably rotatable about its optical axis. The 3a schematically shows a part of the light modulator matrix SLM of 2a in slightly turned condition. As a result of the rotation, the raster R2 of the light source images LB in the observer plane becomes 3b rotated such that light source images LB of the visibility range SB generated for the eye position AP 1 do not reach the adjacent eye position AP 1 '. The rotation can be variable within a relatively small, fixed angle range between 1 ° and 5 ° depending on the signal of the position detection system not shown here. In this area, the rotation of an object coded in the modulator cells is tolerable or barely perceived by the observer. If the angle of rotation exceeds the limit of 5 °, then the rotation of the light modulator matrix SLM must also be taken into account in the coding. Correction values must be integrated into the coding, which computationally cause an opposite rotation of the coded object and thus compensate for the rotation performed. In this case, a coding means receives control signals for changing the coding. The correction values are stored in a look-up table as a function of the angle of rotation and a multiplicity of eye positions AP n precalculated. The rotated three-dimensional object can also be easily recalculated and coded in a further embodiment. Depending on the determined eye position, the data of which are transmitted to the control means, the control means actuators. These rotate the light modulator matrix according to the transmitted signals.
  • In the 4a to 4d On the right side, various possible embodiments of grids R1 of the modulator cells in a light modulator matrix SLM are shown in fragmentary form. On the left are the intensity distributions in the grid R1 of, for example, 10 × 10 modulator cells that appear when illuminated with coherent light. The rasters R1 generate raster images of light source images in view planes at eye positions such that no interfering light source images fall into adjacent observer eyes.
  • In 4a is this already off 2a Known grid-like grid R1 of modulator cells (right) with the associated intensity distributions (left) shown, which also form a grid. An optimization of the position of the light source images is effected by a rotation of the light modulator matrix, the result in 3b you can see. The 4b shows a grid R1, in which every other row of modulator cells is arranged symmetrically offset by one cell half to the adjacent line. The arrangement of the modulator cells in this grid R1 is also referred to as shear. In 4c For example, the light modulator matrix has a grid R1 of modulator cells 4a which was turned 45 °. On the left you can see the intensity distributions in this grid R1. Both 4a to 4c the modulator cells are shown by way of example square. Of course, rectangular modulator cells can also be used. The decisive factor is always the raster of the modulator cells, which generates a corresponding grid of intensity distributions.
  • A particularly advantageous embodiment of a grid R1 can be according to 4d reach with a hexagonal arrangement of modulator cells, which also lead to a hexagonal arrangement of the intensities in the illuminated light modulator matrix SLM. Resulting light source images always provide areas for the neighboring observer eyes in the observer plane in which no or only a very low intensity occurs. The first grid R1 with the in the 4b to 4d shown arrangements of modulator cells generate in a viewer plane, a second grid R2 of light source images, with which a crosstalk of intensities of the defined visibility range is prevented to adjacent observer eyes.
  • The grid R1 in 4d has for the application in a light modulator matrix of a holographic display but still other advantages. A visibility area is generated at a detected eye position and contains at least the eye pupil. Since the eye pupil is round and the visibility range is square by default of commonly used square modulator cells Information from the corner areas not the viewer's eye. When using a light modulator matrix with a hexagonal array of modulator cells, the Fourier transform of this arrangement is again a hexagonal array. In the observer plane of the holographic display, this leads to a likewise hexagonal visibility region. This form is known that round bodies, so the eye pupil, can be arranged there with the least amount of space lost. For an eye pupil, the greatest information content of a hexagonal modulator cell is displayed in a hexagonal visibility region compared to the square modulator cell. This will be in 5 shown schematically. It shows a section of the hexagonal arrangement of hexagonal modulator cells in a light modulator matrix SLM 4d , The eye pupil EP of a viewer's eye can be seen as a circle in the middle modulator cell. This circle indicates the maximum size of the eye pupil EP. The unused area between the circle and the modulator cell is smaller than with rectangular modulator cells. Such a trained light modulator matrix has the highest packing density. It can be used advantageously for a colored reconstruction of spatially interlaced views in a holographic display, since one needs a larger number of modulator cells compared to the single-color representation.
  • In 6 is an embodiment of a compressed in the horizontal direction hexagonal grid R1 of modulator cells after 4d shown. Due to the compressed shape of the modulator cells, the visibility range can be better adapted to the eye movement.
  • To further increase the optical power detected by the eye, according to 7 another, also optimally adapted to the eye shape of the visibility range SB are generated. This shape corresponds to the statistically dynamic form of the stay of the eye pupil AP during the eye movement in the visibility area SB. The directions of movement of the eye pupil AP are indicated by arrows. The shape of a modulator cell in the light modulator matrix SLM, which generates this visibility region, is shown in dashed lines. The grid R1 in the SLM would have modulator cells that are as close to each other as possible, similar to a honeycomb shape.
  • The background for this form is as follows: The eye executes movements that lead to a distribution of the probability of the pupil AP, which is horizontally greater than vertical for a fixed value of the probability of residence. Lines of equal probabilities can be approximated by ellipses that are horizontally wider than vertically high, i. by ellipses, whose longer main axis lies in the horizontal. The ratio of the two principal axes may e.g. with horizontal 16 to vertical 9 according to natural vision. The statistically dynamic probability of the eye pupil staying within a small time interval is widened horizontally. That is, the requirements for a system for determining the pupil position and the tracking of the light to the detected pupil position are horizontally and vertically different. If the error .DELTA.x / .DELTA.t of this system is rotationally symmetrical, it is advantageous to generate a further extended in the horizontal visibility range. Accordingly, the adjusted visibility area will be an ellipse with a horizontal major axis. This visibility area is created by diffracting the light at a modulator cell which is vertically larger than horizontal. Following the example, the modulator cell will then optimally have an elliptical shape with an aspect ratio horizontal to vertical of 9:16. Since the eye pupil performs more horizontal than vertical movements, this elliptical shape is optimally suited for eye tracking. The proportion of optical power no longer detected by the eye in the elliptical visibility region can be reduced compared to visibility regions which are generated by other forms of modulator cells.
  • Analogous to 6 can also be the arrangements of the modulator cells of 4a to 4d upset to realize a width to height ratio of the modulator cells of 9:16. This again leads to a visibility range in the observer level, which has a ratio of width to height of 16: 9.
  • In the 4a to 4d described solutions can be extended with additional optical components in the light modulation device for special applications. For example, the light modulator arrays may be combined with a variable magnification imaging optical system. It is actuated by actuators controlled by the control means in order to additionally be able to scale the distances of the light source images in the observer plane proportionally to one another. This may be true if eye positions are determined at depths deviating significantly from the average observer distance to the SLM. This corresponds to a distance-dependent tracking of the grid of the light source images. However, the variable magnification imaging optical system can also be used alone as a stand-alone measure for changing the position of the light source images in the light modulation device.
  • Another application involves expanding the viewer area to provide information to viewers further apart. Then, in addition, large-area optical deflection means are brought into the light path which additionally laterally shift the second grid of light source images virtually over a comparatively relatively large area. This can e.g. used in vehicles or aircraft to provide information to the driver and passengers with a holographic display. The information is transmitted via appropriately installed optical deflection means, e.g. Mirror, distracted to the respective viewer's eyes.
  • In order not to immediately trigger tracking of the visibility range by the control means in the case of slight movements of the viewer's eye, the visibility range can be limitedly increased at the position of the determined viewer's eye. This can be achieved by additionally performing a fast periodic, lateral deflection of the generated visibility range at this eye position. For this purpose, the control means additionally generate control signals which are added as phase signals and / or as amplitude signals to the values coded in the light modulator and / or to the control values of the prism cells. The additional control signals are determined as a function of the determined deflection angle of the observer's eyes and an angle which corresponds to the localized deflection. Concretely, e.g. the prism signal, e.g. sinusoidal voltage signal modulated.
  • In a further embodiment, the light modulation device can be combined with a deflection field for tracking visibility ranges for observer eyes in two directions. The deflection field has cells which function according to the electrowetting principle. The deflection of light bundles in these cells increasingly shifts intensities into the higher diffraction orders. Therefore, the invention is also important for such tracking devices, especially when there is a direct assignment of a deflection cell to a modulator cell. The light bundles are deflected and superimposed by adjustable boundary surfaces in the deflection field onto respectively determined observer eye in the visibility region, the control means controlling the setting of inclination angles of the boundary surfaces in a predetermined angular range. The light modulation device therefore also has means for controlling electrodes which adjust the angles of inclination of the boundary surfaces of the deflection field as a function of the detected eye position. In the case of a hexagonal arrangement of hexagonal modulator cells, the cells of the deflection field should expediently also be hexagonal.
  • A holographic display with a controllable light modulation device according to one of the embodiments can successfully suppress disturbing diffraction orders in eyes adjacent to the determined observer eye, whereby the display quality of the generated holographic reconstruction is improved.

Claims (13)

  1. A controllable light modulation device having a light modulator matrix (SLM), in which modulator cells are arranged in a first grid (R1) and diffracting coherent light beams arriving from light sources which are projected into a defined visibility range (SB) at a determined eye position (AP n) in a viewer plane (BE1 , BE2) having light source images in a second grid (R2), the defined visibility area (SB) being positionable between two light source images (LB), and control means (CM) for controlling a position detection system (PE) and the light modulation, characterized in that the modulator cells in the first grid (R1) are arranged such that in the observer plane (BE1, BE2) with the diffracted light beams, the second grid (R2) can be generated with areas without or with very low intensity at locations of observer eyes, which are adjacent to the positioned visibility region (SB), the regions He is generated with a rotational movement of the light modulator matrix (SLM), which is controllably rotatable with a maximum angular range, can be generated.
  2. A controllable light modulation device having a light modulator matrix (SLM), in which modulator cells are arranged in a first grid (R1) and diffracting coherent light beams arriving from light sources which are projected into a defined visibility range (SB) at a determined eye position (AP n) in a viewer plane (BE1 , BE2) having light source images in a second grid (R2), the defined visibility area (SB) being positionable between two light source images (LB), and control means (CM) for controlling a position detection system (PE) and the light modulation, characterized in that the modulator cells in the first grid (R1) are arranged such that in the observer plane (BE1, BE2) with the diffracted light beams, the second grid (R2) can be generated with areas without or with very low intensity at locations of observer eyes, which are adjacent to the positioned visibility region (SB), the light m is combined with a variable magnification imaging optical system and the areas for a given depth position of the observer eyes to the light modulator matrix (SLM) can be generated.
  3. Controllable light modulation device according to claim 1 or 2, wherein the light modulator matrix (SLM) is designed to be rotatable about its optical axis, wherein the rotation, depending on a signal of the position detection system (PE) controllable, takes place in a defined angular range.
  4.  Controllable light modulation device according to claim 1 or 2, wherein the light modulator matrix (SLM) is coded with hologram values of a 3D scene, which are changeable as soon as the rotational angle of the light modulator matrix (SLM) to be set is greater than the defined angular range.
  5.  A controllable light modulation device according to claim 4, wherein correction values are pre-calculated depending on the rotation angle and a plurality of eye positions (AP n) for changing the coding in a look-up table.
  6.  Controllable light modulation device according to claim 4, wherein in the modulator cells coded sub-holograms of individual object points of the 3D scene for changing the coding in the light modulator matrix (SLM) are displaceable, wherein the displacement of the rotation of the light modulator matrix (SLM) is compensated.
  7.  Controllable light modulation device according to claim 1 or 2, wherein the first grid (R1) of the light modulator matrix (SLM) has modulator cells, which are arranged hexagonally and regularly formed.
  8.  A controllable light modulation device with a first grid (R1) according to one of claims 1 to 7, which additionally has a compression in the horizontal direction, with which a visibility region (SB) can be generated, which is the statistically dynamic form of the presence of an eye pupil during eye movement in the visibility region (SB) is adjusted.
  9.  Controllable light modulation device according to claim 1 or 2, wherein in the optical path, a variable-magnification imaging optical system is actuated by actuators for scaling the distances of the light source images (LB) proportional to each other in the second grid (R2), wherein the actuators by control means (CM) are controllable.
  10.  Controllable light modulation device according to claim 9, wherein for the additional lateral displacement of the second grid (R2) of virtual light source images (LB) over a large area large-area optical deflection means are provided.
  11.  Controllable light modulation device according to one of Claims 1 to 10, having a deflection field with which light beams can be deflected and superimposed onto a respective observer eye in the visibility region (SB), with the deflection of which light source images (LB) can be displaced into higher diffraction orders.
  12.  Controllable light modulation device according to claim 11, in which the deflection field according to the electrowetting principle has functioning matrix-shaped deflection cells which contain at least one interface which are adjustable in a predetermined angular range.
  13.  Controllable light modulation device according to at least one of the preceding claims for use in a holographic display.
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FR2992743A1 (en) * 2012-07-02 2014-01-03 Peugeot Citroen Automobiles Sa Device for providing information about collision risk to driver of car following another car, has analyzing unit determining projection angle of holographic image based on average height position of eyes of driver of following car
DE102016204703A1 (en) * 2016-03-22 2017-09-28 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Apparatus and method for generating an optical pattern of pixels in an image plane
DE102016207236A1 (en) * 2016-04-28 2017-11-02 Robert Bosch Gmbh projection system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5661591A (en) * 1995-09-29 1997-08-26 Texas Instruments Incorporated Optical switch having an analog beam for steering light
WO2004044659A2 (en) * 2002-11-13 2004-05-27 Seereal Technologies Gmbh Video hologram and device for reconstructing video holograms
WO2007073731A1 (en) * 2005-12-22 2007-07-05 Seereal Technologies S.A. Method for the multimodal representation of image contents on a display unit for video holograms, and multimodal display unit
WO2007131817A1 (en) * 2006-05-12 2007-11-22 Seereal Technologies S.A. Device for the holographic reconstruction of scenes, comprising a tracking system
WO2008025844A1 (en) * 2006-09-01 2008-03-06 Seereal Technologies S.A. Method for generating computer-generated video holograms in real time by means of propagation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5661591A (en) * 1995-09-29 1997-08-26 Texas Instruments Incorporated Optical switch having an analog beam for steering light
WO2004044659A2 (en) * 2002-11-13 2004-05-27 Seereal Technologies Gmbh Video hologram and device for reconstructing video holograms
WO2007073731A1 (en) * 2005-12-22 2007-07-05 Seereal Technologies S.A. Method for the multimodal representation of image contents on a display unit for video holograms, and multimodal display unit
WO2007131817A1 (en) * 2006-05-12 2007-11-22 Seereal Technologies S.A. Device for the holographic reconstruction of scenes, comprising a tracking system
WO2008025844A1 (en) * 2006-09-01 2008-03-06 Seereal Technologies S.A. Method for generating computer-generated video holograms in real time by means of propagation

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