Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/18—Diffraction gratings
  • G02B5/1876—Diffractive Fresnel lenses; Zone plates; Kinoforms
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/04—Processes or apparatus for producing holograms
  • G03H1/08—Synthesising holograms, i.e. holograms synthesized from objects or objects from holograms
  • G03H1/0866—Digital holographic imaging, i.e. synthesizing holobjects from holograms
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N5/00—Details of television systems
  • H04N5/74—Projection arrangements for image reproduction, e.g. using eidophor
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/04—Processes or apparatus for producing holograms
  • G03H1/16—Processes or apparatus for producing holograms using Fourier transform
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
  • G03H1/2202—Reconstruction geometries or arrangements
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
  • G03H1/2294—Addressing the hologram to an active spatial light modulator
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
  • G03H1/2249—Holobject properties
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/04—Processes or apparatus for producing holograms
  • G03H1/08—Synthesising holograms, i.e. holograms synthesized from objects or objects from holograms
  • G03H1/0866—Digital holographic imaging, i.e. synthesizing holobjects from holograms
  • G03H2001/0883—Reconstruction aspect, e.g. numerical focusing
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
  • G03H1/2202—Reconstruction geometries or arrangements
  • G03H1/2205—Reconstruction geometries or arrangements using downstream optical component
  • G03H2001/221—Element having optical power, e.g. field lens
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
  • G03H1/2202—Reconstruction geometries or arrangements
  • G03H2001/2236—Details of the viewing window
  • G03H2001/2239—Enlarging the viewing window
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
  • G03H1/2202—Reconstruction geometries or arrangements
  • G03H2001/2236—Details of the viewing window
  • G03H2001/2242—Multiple viewing windows
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
  • G03H1/2249—Holobject properties
  • G03H2001/2252—Location of the holobject
  • G03H2001/226—Virtual or real
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
  • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
  • G03H1/2249—Holobject properties
  • G03H2001/2263—Multicoloured holobject
  • G03H2001/2271—RGB holobject
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H2210/00—Object characteristics
  • G03H2210/30—3D object
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H2222/00—Light sources or light beam properties
  • G03H2222/50—Geometrical property of the irradiating beam
  • G03H2222/54—Convergent beam
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H2223/00—Optical components
  • G03H2223/18—Prism
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H2223/00—Optical components
  • G03H2223/19—Microoptic array, e.g. lens array
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H2223/00—Optical components
  • G03H2223/24—Reflector; Mirror
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H2225/00—Active addressable light modulator
  • G03H2225/52—Reflective modulator
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H2225/00—Active addressable light modulator
  • G03H2225/60—Multiple SLMs
  • G03H2225/61—Multiple SLMs for multicolour processing
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
  • G03H2226/00—Electro-optic or electronic components relating to digital holography
  • G03H2226/05—Means for tracking the observer

Definitions

• the invention relates to a projection device for holographic reconstruction of scenes with a spatial light modulator, an imaging system with at least two imaging means and a lighting device with at least one light source with sufficiently coherent light for illuminating a hologram coded in the light modulator. Furthermore, the invention also relates to a method for holographic reconstruction of scenes.
• the stereo effect is generally utilized, wherein the light producing the stereo impression is reflected or emitted by a plane.
• the light emanating from the hologram interferes with the object points of the scene from where it naturally propagates.
• Holographic representations realize object substitution.
• stereoscopic representations in still form (stills) or in moving form in arbitrary forms of representation are not object substitution. They provide two flat images for the left and right eyes that correspond to the eye positions. The three-dimensional effect is created by the parallax in the two pictures.
• the holographic representation eliminates the problems known from stereoscopy, such as fatigue or eye and head pain, since in principle there is no difference in viewing holographic reconstructed scenes and natural scenes.
• Holography is generally differentiated into static and dynamic methods.
• static holography photographic media are often used
• an interference image is recorded on the photographic medium by means of a reference beam, which is superimposed with a light beam carrying the object information.
• This static object information is holographically reconstructed with a beam similar or similar to the reference beam.
• the entertainment industry as well as the medical and
• micro-displays are used, as they are also used in projection devices.
• micro-displays are LCoS (Liquid Crystal on Silicon), transmissive LCD or MEMS (Micro Electro Mechanical Systems). Since their pixel pitch, so the distance between the pixel centers, compared to other displays is small, a comparatively large diffraction angle is achieved.
• LCoS Liquid Crystal on Silicon
• MEMS Micro Electro Mechanical Systems
• Micro displays and similar light modulators have a size of a few inches and despite the relatively small pitch still such a small diffraction angle that a two-eyed viewing is hardly possible.
• transmissive and reflective light modulators are used in holographic reconstruction devices based on technologies such as TFT, LCoS, MEMS, DMD (digital micromirror device), OASLM (optically addressed spatial light modulator), EASLM (Electronically Addressed Spatial Light Modulator), FLCD (Ferroelectric Liquid Crystal Display) or other based.
• Such light modulators can be designed in one or two dimensions.
• the reason for the use of reflective light modulators lies in their low-cost production, the large filling factor for a high light efficiency, the short switching time and the low light losses due to absorption compared to transmissive displays. However, the small spatial dimensions must be accepted.
• WO 03/060612 From WO 03/060612 a reflective LC display with a resolution of about 12 microns and a reflectance up to 90% for the color real-time display of holograms is known.
• the reconstruction is done with the collimated light of one or more LEDs via a field lens.
• viewing at a distance of about 1 m is only possible within a range of about 3 cm, whereby the reconstructed scene can not be viewed simultaneously with both eyes, ie in three dimensions.
• WO 02/095503 describes a holographic 3D projection device which uses a DMD chip for the hologram representation.
• the high reflectivity and the short switching time of the light modulator can be here for the same reasons as to the WO
• WO 00/75699 describes a holographic display which reconstructs a video hologram with the aid of partial holograms.
• This method is also known by the term tiling.
• partial holograms coded using a very fast Electronically Addressable Spatial Light Modulator (EASLM) are sequentially imaged into an intermediate layer, the process taking place so rapidly that an observer perceives the reconstructions of all partial holograms as a single reconstruction of a 3D object.
• EASLM Electronically Addressable Spatial Light Modulator
• a special illumination and imaging system is used, for example with a shutter which is controlled synchronously with the EASLM and only reads through the respective sub-hologram and in particular blocks out the unused diffraction orders.
• the requirements for the dynamic properties of the SLM used to display the partial holograms are considerable and a flat design is hardly possible.
• the object of the present invention is therefore to provide a projection apparatus for holographic reconstruction of two- and three-dimensional scenes, which eliminates the mentioned disadvantages of the prior art and reconstructs scenes of any size and visible within a large reconstruction space, so that with a small number of optical elements can be reconstructed simply, inexpensively and with high quality spatially extended moving scenes.
• the object is achieved by a projection device for the holographic reconstruction of scenes, wherein a light modulator illuminated with sufficiently coherent light, which has a coded hologram, can be visually enlarged.
• the projection device advantageously also has an imaging system with the first and the second imaging means in addition to the light modulator and the illumination device for emitting sufficiently coherent light.
• the light modulator is a low expansion spatial light modulator and will therefore be referred to hereinafter as a micro SLM.
• the micro SLM is magnified by the first imaging means onto the second imaging means, the spatial frequency spectrum (Fourier spectrum) of the micro SLM being imaged into the viewer window by means of the second imaging means.
• the observer window is thus the image of the diffraction order used in the Fourier plane of the hologram.
• the first imaging means In order for the first imaging means to image the entire micro SLM onto the second imaging means, all contributions of a desired diffraction order must be detected by the first imaging means.
• the micro-SLM can be illuminated with a wave that converges in the light direction after the micro-SLM. Consequently, the plane of the spatial frequency spectrum contains the Fourier plane of the micro SLM and, at the same time, the first imaging means.
• the second imaging means together with the observer window, defines a frustoconical reconstruction space, also referred to as frustration.
• a reconstructed scene advantageously one reconstructed three-dimensional scene presented to one or more observers.
• the reconstruction space continues at will far beyond the second imaging means. Through the observer window, the observer can thus observe the reconstructed scene in the large reconstruction space. Under sufficiently coherent light here light is understood, which is capable of interfering with the representation of a three-dimensional scene.
• Such a projection device thus has only a small number of optical elements for holographic reconstruction. To the quality of the optical elements are compared with known optical
• a spatial frequency filter in the plane in which the spatial frequency spectrum of the light modulator is present is arranged.
• a spatial frequency filter here in particular a diaphragm, can advantageously be arranged in this plane, which allows only the diffraction order used to pass.
• the individual diffraction orders overlap so that the shutter cuts off information or allows unwanted information to pass.
• the individual diffraction orders can be separated from one another, thereby excluding clipping of the information by the shutter.
• the aperture can be generalized as spatial frequency filter, which filters out the desired diffraction order, quantization error or blocks off other errors of the micro SLM or modulates the wave field in any other suitable way, for example to compensate for aberrations of the projection device. This happens, for example, by the spatial frequency filter adding an aspherical lens function.
• Another advantage is that the reduction of the spatial frequency spectrum to a diffraction order and the imaging of this diffraction order and the aperture as a viewer window prevent any crosstalk that usually occurs in reconstructions using matrix-shaped light modulators.
• a left and right eye of a viewer can be successively operated without crosstalk.
• a multiplex method for several people is only possible.
• the Fourier plane also contains no periodicity. An aperture can thus be omitted.
• Such light modulators are for example OASLM.
• a third imaging means may be included, which is arranged near the light modulator.
• the third imaging means generates the spatial frequency spectrum as a Fourier transform of the hologram encoded in the micro SLM in its image-side focal plane.
• the use of a third imaging means is particularly advantageous in collimated illumination, since without this imaging means only light with a correspondingly large diffraction angle reaches the first imaging means.
• the third imaging means may be arranged in front of or behind the micro SLM. Accordingly, the third imaging means focuses the light emanating from the micro SLM or the outgoing wave into its image-side focal plane. But it is also possible that emanates from the micro-SLM a slightly converging wave, the focus is enhanced by the use of another imaging means.
• the third imaging means need not be present in the illumination with a converging wave, because advantageously the reconstruction wave falling on the micro SLM can be adjusted to be approximately in-plane of the first imaging means converges. In all cases, however, there is always a focal plane, the Fourier plane of the micro-SLM, in which the first imaging means is also arranged.
• a position detection system for determining an eye position of at least one observer when observing a reconstructed scene may be included.
• the position detection system detects the eye positions or pupil positions of the viewer (s) while observing the reconstructed scene. According to the eye position of the viewer, the scene is encoded. Then the viewer window can be tracked according to the new position of the eyes.
• space-solid representations are provided with a realistic change of perspective and representations with exaggerated change of perspective. By this is meant that the angular and positional change of the scene is greater than the angular and positional change of the observer.
• At least one deflection element is in the
• Such deflecting elements may be mechanical, electrical or optical elements.
• the deflection element may, for example, be arranged in the plane of the first imaging means as a controllable optical element which, like a prism, virtually shifts the spectrum.
• a deflection element near the second imaging means This deflecting element then has the effect of a prism and optionally the action of a lens.
• This arrangement of the deflector near the second imaging means is particularly advantageous because the entire imaging system is static from the light source to the second imaging means. That is, the beam path to the second imaging means always remains constant. Firstly, this minimizes the demands on this part of the optical system because the entrance opening of the first and second imaging means is minimal can be kept.
• the entrance opening of the first and second imaging means would otherwise have to be always larger. This significantly reduces the requirements for the second imaging agent. Second, this static part of the optical system can be optimally corrected in its imaging properties.
• mapping of the micro SLM on the second imaging means does not shift.
• the position of the reconstruction of a two-dimensional scene on the second imaging means is independent of the observer position.
• the object is further achieved by a method for holographic reconstruction of scenes, wherein in a first step in a plane of a first imaging means a spatial frequency spectrum as a Fourier transform of the coded hologram is formed, which in a second step, the first imaging means the light modulator in a plane a second imaging means, wherein the second imaging means images the spatial frequency spectrum from the plane of the first imaging means into at least one observer window of the observer plane, whereby a reconstructed scene is displayed enlarged in at least one observer in a reconstruction space spanned by the second imaging means and the observer window Illustration of the light modulator of the reconstruction space is expanded in size.
• the spatial frequency spectrum is used as a Fourier transform of the im
• Light modulator here a micro-SLM, encoded hologram formed.
• This is followed, in a second step, by imaging the micro SLM into a plane on the second imaging means by means of the first imaging means, thereby increasing the micro SLM.
• the mapping of the micro SLM to the second imaging means means that the micro SLM can also be imaged in close proximity to the second imaging means.
• the spatial frequency spectrum is imaged from the plane of the first imaging means via the second imaging means into the observer plane and forms a viewer window in the observer plane.
• the reconstruction space which through Accordingly, the viewer window and the second imaging means is spanned and in which the reconstructed scene is presented enlarged to one or more viewers, is likewise designed to be enlarged. It should be noted that the reconstruction space is not bounded by the second imaging means and the viewer window but extends rearwardly beyond the second imaging means.
• two-dimensional and / or three-dimensional scenes of high quality can thus be displayed simultaneously or sequentially in a large reconstruction space for observation.
• the plane of the 2D representation can advantageously be placed in the second imaging means. In this plane then appears the enlarged image of the micro-SLM, which in this case is encoded with the two-dimensional image.
• the two-dimensional image can also be moved toward the observer or moved away from him.
• aberrations of the imaging means are taken into account in the calculation of the hologram and compensated by the light modulator.
• Focusing causes a minimal lateral extent of the first imaging means for imaging. This can ensure that aberrations of the first imaging means are minimized. In addition, it must be ensured that the first imaging agent images the micro-SLM completely and homogeneously in its illumination to the second imaging agent. Aberrations of the second and possibly further imaging means can also be compensated by the micro-SLM. The phase errors occurring in aberrations can be easily corrected by a corresponding additional phase deviation. It is also possible that a spatial frequency filter compensates aberrations of the imaging means used in the projection device.
• Figure 1 is a schematic representation of a projection device according to the invention for the holographic reconstruction of scenes with an imaging system
• FIG. 2 shows a detail of the projection device shown in FIG.
• FIG. 3 shows a detail of the projection apparatus shown in FIG. 1 when a converging wave impinges on the light modulator;
• FIG. 4 shows a further embodiment of the projection device according to the invention with a reflective light modulator and a beam splitter element
• FIG. 5 shows a deflection element contained in the projection device for tracking a viewer window
• Figure 6 shows another possibility for tracking the viewer window in the projection device
• FIG. 7 shows a further embodiment of the projection device according to the invention with a concave mirror as second imaging means; and FIG. 8 shows the projection apparatus shown in FIG. 1 viewing a single reconstructed point of the scene.
• the projection device is shown in principle, wherein an imaging system 3 images an illumination device 1, in this case a punctiform light source, into a viewer plane 6.
• the imaging system 3 has a first imaging means 4 and a second imaging means 5.
• the light source 1 generates coherent or sufficiently coherent light, which is required for a holographic reconstruction of a scene.
• a light source 1 can laser, LED (s) or other light sources are used, with a color filtering can be made.
• a wave emitted from the light source 1 is converted to a plane wave 7 by means of a collimator lens L.
• the wave 7 thus emanating from the light source 1 and passing through the collimator lens L as previously assumed, impinges perpendicularly on a transmissive spatial light modulator 8 with regularly arranged pixels comprising a coded dynamic hologram 2, e.g. a CGH, wherein the wavefront of the plane wave 7 is modulated at equidistant locations in the spatial light modulator 8 to a desired wavefront.
• the spatial light modulator 8 has a small extension and is therefore referred to below as a micro-SLM.
• a third imaging means 9 is arranged in the beam direction after the micro SLM 8.
• the spatial frequency spectrum can also be called a Fourier spectrum.
• the focal plane 10 shifts along an optical axis eleventh E2006 / 000896
• the first imaging means 4 is arranged in the immediate vicinity of the focal plane 10 of the third imaging means 9.
• This first imaging means 4 images the micro-SLM in a plane 12 onto the second imaging means 5 or in the immediate vicinity of it.
• the second imaging means 5 here is a lens which, in comparison to the other imaging means 4 and 9, is made substantially larger in order to reconstruct the largest possible scene 13 in a reconstruction space (frustrum) 14.
• a virtual viewer window 15 is formed which is physically absent and whose extent corresponds to the mapping of a period of the spatial frequency spectrum.
• the observer or even the observers can observe the reconstructed scene 13 through the observer window 15.
• the reconstruction of the scene 13 is formed in the truncated pyramid-shaped reconstruction space 14, which is spanned between the edges of the observer window 15 and the second imaging means 5.
• the reconstruction space 14 can also extend as far as desired back beyond the second imaging means 5.
• the micro-SLM 8 Due to the equidistant scanning of the information by the micro-SLM 8, which is assumed to be in the form of a matrix, the latter generates a plurality of diffraction orders in the focal plane 10 of the third imaging means 9 in periodic continuation.
• This periodic repetition has a periodicity interval in the focal plane 10 whose magnitude is reciprocal to the pitch of the micro SLM 8.
• the pitch corresponds to the distance of the scanning locations in the micro-SLM 8.
• the second imaging means 5 forms the periodic distribution in the focal plane 10 into the observer plane 6.
• An observer within a diffraction order in the observer plane 6 would indeed see the reconstructed scene 13 undisturbed with one eye, but the other eye of the observer could simultaneously perceive the higher diffraction orders as disturbances.
• the periodicity angle can be described in approximation by ( ⁇ / pitch).
• Wavelength of ⁇ 500 nm and a pitch of 10 microns in the micro-SLM 8, a diffraction angle of about ⁇ 1/20 rad would be achieved.
• This angle corresponds to a focal length of the third imaging means 9 of 20 mm, a lateral extent of the periodicity interval of about 1 mm.
• a diaphragm 16 is arranged in the focal plane 10 behind the first imaging means 4, which transmits only one periodicity interval or only the desired diffraction order.
• the aperture acts as a low, high or band pass filter in this case.
• the aperture 16 is imaged via the second imaging means 5 in the observer plane 6 and forms there the observer window 15.
• the advantage of the presence of the aperture 16 in the projection device is that prevents crosstalk of other periods to the other eye or eyes of another observer becomes.
• a prerequisite for this, however, is a band-limited spatial frequency spectrum of the micro-SLM 8.
• OASLM Optically addressable light modulators
• the three-dimensional scene in the focal plane 10 will therefore be continued periodically.
• the three-dimensional scene will require coding of the hologram 2 on the micro SLM 8 whose spatial frequency spectrum is greater than the periodicity interval in the focal plane 10. This then leads to overlaps of the diffraction orders.
• the diaphragm 16 in this focal plane 10 would then cut off an information-carrying part of the diffraction order used and, on the other hand, allow higher diffraction orders to pass.
• the three-dimensional scene in the spatial frequency spectrum of the focal plane 10 can be limited by preceding filtering.
• the previous filtering or the limitation of the bandwidth is already taken into account in the calculation of the hologram 2 and included in the calculation.
• the aperture 16 in the focal plane 10 then blocks the higher diffraction orders without limiting the selected diffraction order.
• the previously caused crosstalk to the other eye or eyes of another observer is suppressed or prevented.
• the aperture 16 can also be extended to a spatial frequency filter.
• the spatial frequency filter is a complex-valued modulation element that changes the incident wave in its amplitude and / or phase.
• the spatial frequency filter still serves other functions, e.g. for suppressing aberrations of the third imaging means 9.
• a position detection system 17 is included in the projection device for tracking the observer window 15, which detects the current eye position of the
• the coding of the hologram 2 on the micro SLM 8 can thus be adapted according to the current eye position.
• the reconstructed scene 13 is thereby recoded in such a way that it is shifted horizontally and / or vertically as a function of the position of the observer and / or becomes visible at an angle.
• space-solid representations are provided with a realistic change of perspective and representations with exaggerated change of perspective. The latter is understood to mean that the angle and position change of the object is greater than the angle and position change of the observer.
• the projection device has a deflection element, not shown here in FIG. 1, which is shown in more detail in FIG.
• the observer window 15 does not permit the simultaneous observation of the reconstructed scene 13 with both eyes.
• the other eye of the viewer can then be controlled sequentially in another viewer window or simultaneously in a parallel beam path.
• sufficiently high resolution of the micro SLM 8 can be achieved by spatial Multiplexing the holograms for the right and the left eye are encoded on a micro SLM.
• the reconstruction will be done only vertically.
• the spatial frequency spectrum of the spatial light modulator in the focal plane 10 only in the vertical direction on a periodic repetition.
• the light wave leaving the one-dimensional spatial light modulator expands accordingly in the horizontal direction.
• a focusing perpendicular to the reconstruction direction is therefore to be carried out by additional focusing optical elements, for example cylindrical lenses.
• FIG. 2 shows a section of the projection device shown in FIG. This section shows the micro-SLM 8 with the imaging means 4 and 9 and the diaphragm 16.
• an inclined planar wavefront 18 is used in this embodiment. This is particularly advantageous if the detour phase coding is applied in hologram 2.
• the detour phase coding that is with a pure amplitude hologram, the inclined wave hits adjacent pixels with the required phases. For example, with proper choice of wavefront tilt, all third pixels in their phases match (Burckhardt coding). Three pixels each encode a complex value.
• the detour-phase coding blocks except the most used 1st or -1. Diffraction order all other diffraction orders.
• FIG. 3 likewise shows a section of the projection device shown in FIG. 1, wherein a converging shaft 19 is used for the reconstruction instead of the plane wave incident perpendicularly.
• the third imaging means 9 can be dispensed with if the converging shaft 19 is adjusted so that the first imaging means 4 is arranged in the focus of the converging wave 19, and the spatial frequency spectrum of the radiation beam on the focal plane 10 SLM 8 encoded hologram 2 is created. As the convergence of the incident wave changes, the point of convergence shifts along the optical axis 11 accordingly.
• FIG. 4 shows a further embodiment of the projection device according to the invention with a reflective micro SLM 8 and a beam splitter element 20.
• the beam splitter element 20 is arranged between the third imaging means 9 and the first imaging means 4 for beam guidance of the impinging plane wave 7.
• the beam splitter element 20 may be a simple or dichroic splitter cube, a semitransparent mirror, or another beam injection means.
• the micro-SLM 8 in this embodiment is a reflective micro-SLM and thus must be covered by the reflection of a double path of the light, the coding of the hologram 2 is adjusted accordingly.
• the coupling of the light wave 7 via a dichroic beam splitter is particularly advantageous in the case of sequential reconstruction of the scene 13 in the three primary colors RGB (red-green-blue).
• the three light sources for the individual primary colors are not shown in this embodiment.
• the reconstruction of the scene is carried out as described for FIG.
• the particular advantage of the sequential reconstruction lies in the identical optical beam path. Only the coding has to be adapted to the reconstruction with different wavelengths ⁇ .
• a further development of this exemplary embodiment can be that a separate channel is created for each of the three primary colors RGB, which contains a light source in a specific base color, a micro SLM 8, imaging means 4 and 9 and a diaphragm 16 or a spatial frequency filter.
• the third imaging means 9 omitted in converging waves of lighting.
• beam splitter elements can also be used beam splitter elements.
• a beam splitter element can be provided which is made up of four juxtaposed individual prisms, between which are dichroic layers with different wavelength-dependent transmission and reflection.
• the light of the channel of a base color is coupled, the superimposed emerges on the fourth side surface. This combined light from the three primary colors then passes to the second imaging means 5 to reconstruct the colored scene.
• the second imaging means 5 can be shared for all three channels. In this way, the color reconstruction of the scene takes place simultaneously.
• each channel contains a monochromatic light source of a primary color, a micro-SLM 8, imaging means 4 and 9 and a diaphragm 16.
• the second imaging means 5 can also be shared here for both channels. The two channels form their viewer window on the eyes of the beholder.
• each channel containing three channels corresponding to the three basic colors RGB is also possible.
• the observer window 15 can be tracked according to the eye position when the observer moves.
• the tracking of the observer window 15 is shown in principle.
• Baffle elements 21 may be mechanical deflection elements, such as polygon mirrors, galvanomirrors, prisms, or also optical deflection elements, such as controllable gratings or other diffraction elements, are used.
• the deflecting element 21 has a function of a controllable prism.
• the deflection element 21 is arranged near the second imaging means 5, ie in the beam direction in front of or behind it, or integrated into the imaging means 5 itself.
• This deflecting element 21 optionally has the effect of a lens in addition to the action of a prism. As a result, a lateral and optionally an axial tracking of the observer window 15 is achieved.
• Such a deflecting element 21 with a prismatic function can be produced, for example, by embedding prism-shaped elements filled with birefringent liquid crystals in a substrate of transparent material or being surrounded by a substrate having a different refractive index than the elements.
• the angle through which a light beam is deflected by one of these elements depends on the ratio of refractive indices of the substrate material and the liquid crystal. With an electric field applied to these elements, the alignment of the liquid crystals and thus the effective refractive index are controlled. In this way, the deflection angle can be controlled with an electric field and thus the observer window 15 can be tracked to the observer.
• the first imaging means 4 and the aperture 16 must be moved in accordance with the new position of the focal point in the focal plane 10.
• the zeroth diffraction order of the micro-SLM 8 is arranged around the focal point in the focal plane 10 around.
• FIG. 7 shows a further embodiment of the invention
• the procedure of the reconstruction corresponds to that described in Figure 1 way.
• the first imaging means 4 does not form the micro SLM 8 in the plane 12 but in a plane 23 on the concave mirror 22 or in the immediate vicinity.
• the viewer window 15 is formed in accordance with this reflection.
• the reconstruction space 14 in which the reconstructed scene 13 is to be observed is formed between the viewer window 15 and the concave mirror 22.
• the reconstruction space 14 may, as already mentioned, extend rearwardly as far as possible beyond the concave mirror 22. In this way, a more compact projection device can be created.
• Another advantage of the use of the concave mirror 22 is the better achievable aberration, simpler manufacturing and low weight in contrast to the use of a lens.
• This imaging means 5 may be implemented as a holographic optical element (HOE) or diffractive optical element (DOE).
• the imaging means 5 has a phase pattern which, after reflection, converges the reconstruction wave into the viewer window 15.
• the imaging means 5 embodied as HOE or DOE fulfills the same function as the concave mirror 22.
• the advantage of a HOE or a DOE lies in a flat configuration and in a cost-effective production.
• Such mirrors may be prepared by known methods, e.g. interferometrically, lithographically, by embossing, molding and then curing, extruding, or otherwise prepared. They consist of photo or resist material, of polymers, of metal, glass or other substrates. You can also have reflective layers on a relief.
• FIG. 8 shows the projection device according to FIG. 1 when viewing a reconstructed point 24 of the scene 13.
• the relatively large second imaging means 5 in contrast to the two imaging means 4 and 9 need only be aberration-free in small areas.
• only a reconstructed point 24 of the scene 13 is considered, which is made up of many points. The point 24 is visible only within the viewer window 15.
• Observer window 15 serves as a window through which the observer can observe the reconstructed scene 13. So that no overlaps arise from higher diffraction orders, the bandwidth-limited coding of the hologram 2 has already been described. It ensures that the diffraction orders in level 10 do not overlap. The same applies to the image in the observer plane 6.
• Each point of the reconstructed scene 13 is generated only by a part of the micro-SLM 8 on the second imaging means 5.
• the corresponding projection of the edge rays of the observer window 15 through the point 24 onto the second imaging means 5 clearly shows a small area of the imaging means 5, which contributes to the reconstruction of the point 24. That is, such an area is limited to each scene point on the imaging means 5.
• the projection apparatus not only utilizes the micro SLM 8 to reconstruct very large two- and three-dimensional scenes 13 formed by the viewer window 15 in the reconstruction space 14, but also advantageously uses it for corrections of the optical imaging means 4, 5, and 9
• aberration-free imaging agents should be used. Examples of the corrections of the aberrations will be described below.
• Aberrations of the third imaging means 9 manifest themselves as phase errors by which the wavefront deviates from the ideal wave.
• the wave should be diffraction-limited focused in the plane 10, in which the first imaging means 4 and a spatial frequency filter 16 as an aperture for suppressing unwanted orders and for other functions , how to correct aberrations.
• the greatly enlarged image of the micro SLM 8 by the first imaging means 4 on the second imaging means 5 is regularly subject to aberrations.
• Magnifying optics for the imaging means 4 are, for example, projection optics, as used in rear-projection TVs and are also commercially available. Image sharpness is an important criterion, so that mainly spherical aberrations, but also coma and astigmatism for these optics are already largely suppressed. Although residual distortion and field curvature are tolerable to the viewer of such devices in the projection, these aberrations in the present holographic projection device create significant distortions in the reconstruction.
• the distortion of the first imaging means 4 means a lateral geometric deviation of the magnified image of the micro SLM 8 onto the imaging means 5. The waves emanating from the second imaging means 5 then no longer converge at the intended position of the reconstructed object point, but are displaced.
• a serious aberration is the curvature of the image when the micro SLM 8 is imaged onto the second imaging means 5.
• the curvature of the image primarily means that the required phase values on the imaging means 5 are distorted, which has the effect of three-dimensional distortion, ie lateral and axial .
• Both effects, field curvature and distortion, as well as coma and astigmatism can indeed be kept sufficiently small with a corresponding design and low manufacturing tolerances of the first imaging means 4, but only with increased effort.
• the phase distortion due to the field curvature in the projection device can be compensated by the micro SLM 8. These phase errors can be corrected by an additional phase deviation.
• coma and astigmatism can be reduced by coding.
• the distortion can be compensated, for example, by selecting the pixels of the micro SLM 8 by encoding the hologram values on the pixel positions determined in consideration of the distortion.
• the aberrations of the second imaging means 5 are also compensated by means of the micro SLM 8.
• the deviations of the waves emanating from the second imaging means 5 must generally be well below ⁇ / 10. This in turn requires significant expenses.
• the aberrations with respect to the second imaging means 5 can thus be corrected simply by corresponding coding.
• all aberrations at the imaging means 4, 5 and 9 can be reduced or compensated by the micro SLM 8.
• the aberrations are determined appropriately before reconstruction.
• the thus calculated phase errors can be corrected by a corresponding additional phase deviation of the micro SLM 8.
• the present projection apparatus allows low-expansion spatial light modulators to be used for reconstruction and viewing of large two- or three-dimensional scenes.
• the viewer (s) can move in the observer plane 6 while observing a reconstructed scene.
• Two- and three-dimensional scenes can be displayed simultaneously or one after the other.
• the projection device consists of commercially available optical elements with relatively low manufacturing accuracy and aberration requirements.
• the imaging means 4 and 5 can be corrected by the micro SLM 8 and, secondly, require only a small wavefront distortion over a small area of the large imaging means 5.
• the projection takes place near or on the imaging means 5.
• the hologram 2 is calculated in such a way that a two-dimensional scene is reconstructed in the plane 12 or 23 of the second imaging means 5.
• the observer can shift a plane in which a reconstruction of the two-dimensional scene takes place by observing the scene by recalculating the hologram 2 axially. This means that the presentation can be consulted or moved away from the viewer. Likewise, details can be extracted to be more closely watched by the viewer. These actions can be interactively made by the respective viewer himself.
• Possible fields of application of the holographic projection device can be displays for a two- and / or three-dimensional representation for the private and work area, such as for example computers, television, electronic games, automotive industry for the display of information or entertainment, medical technology, in particular for Minimally invasive surgery or the spatial representation of tomographically acquired data or even for military technology for the representation of terrain profiles.
• the present projection device can also be used in other areas not mentioned here.

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• 2006
  • 2006-05-12 CN CN2006800165633A patent/CN101176043B/zh not_active Expired - Fee Related
  • 2006-05-12 WO PCT/DE2006/000896 patent/WO2006119760A2/de not_active Ceased
  • 2006-05-12 US US11/914,278 patent/US9116505B2/en active Active
  • 2006-05-12 EP EP06742375A patent/EP1880252B1/de not_active Not-in-force
  • 2006-05-12 KR KR1020077029200A patent/KR101277370B1/ko active Active
  • 2006-05-12 AT AT06742375T patent/ATE410719T1/de not_active IP Right Cessation
  • 2006-05-12 JP JP2008510405A patent/JP5015913B2/ja active Active
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  • 2006-05-12 DE DE502006001767T patent/DE502006001767D1/de active Active
  • 2006-05-12 CA CA002608290A patent/CA2608290A1/en not_active Abandoned
• 2015
  • 2015-08-18 US US14/828,973 patent/US9513599B2/en active Active

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