WO2002075433A2

WO2002075433A2 - Method and device for the three-dimensional representation of image elements

Info

Publication number: WO2002075433A2
Application number: PCT/EP2002/002915
Authority: WO
Inventors: David P. Dickerson; Heinrich A. Eberl
Original assignee: Candy Optronic Gmbh
Priority date: 2001-03-16
Filing date: 2002-03-15
Publication date: 2002-09-26
Also published as: AU2002304863A1; DE10291111D2; WO2002075433A3

Abstract

The invention relates to a device for the three-dimensional representation of image elements. Said device comprises a plurality of holographic elements, each associated with one image element, and at least one optical projection device that allows for the three-dimensional representation of an image element to be represented by selectively illuminating at least one holographic element associated with the image element to be represented. A plurality of the holographic elements comprise one holographic recording each of a diffusely reflecting or a diffusely transmitting object.

Description

Method and device for displaying picture elements in three-dimensional space

Field of the Invention

The invention relates to a device for displaying picture elements in three-dimensional space and a corresponding method.

State of the art

Devices of this type, for example based on a rotating surface or a step-by-step fluorescence excitation, are known.

In this sense, DE 2622802 describes a method for three-dimensional imaging with an image beam deflected via a two-dimensional deflection surface on an areal screen, preferably made of translucent material, rotating around an axis of rotation coinciding with the optical axis of the deflection surface and designed as a geometric generator of an imaging space, and a device to practice this procedure.

With regard to the gradual excitation of fluorescence, it was observed in mercury vapor as early as 1920 that its atoms can be caused to afterglow (fluorescence) by successive irradiation with two different light pulses. In principle, the atoms must have three suitable energy levels: At the intersection of two crossed invisible infrared light beams, the atoms are excited from the first to the second level and from there to a third. When they return to the basic state, they emit visible light so that the intersection of the infrared rays shines. Experiments of this kind have been successful with an erbium-doped calcium fluoride crystal. In this way you have addressable luminous room points. The disadvantage, however, is that the glow is only perceptible in complete darkness. So far, the researchers have not found a more efficient medium.

WO 02/06864 discloses a holographic display for storing and reproducing a spatial structure, the holographic display being constructed from a plurality of holographic screens, each of which is associated with its own projection device. However, no device is disclosed there which is capable of producing a spatial visual perception similar to the observation of a real object by displaying image elements in three-dimensional space. Instead, the display disclosed there aims in principle to spatially shift the perceived display level of a κweimensional display.

The object of the present invention is to provide a method and a device for displaying picture elements in three-dimensional space, which as far as possible meet the expectations of a user due to the variety of commercially available two-dimensional display devices. In particular, it is a question of solving the problem of three-dimensional picture element display in a manner which allows the device to be designed in a cost-effective, compact, uncomplicated and / or portable manner.

Summary of the invention

According to the invention, this object is achieved by a device with a large number of holographic elements or a method using a large number of holographic elements. Each holographic element is preferably assigned to a picture element, it being particularly expedient for a color display if a plurality of holographic elements are assigned to a respective picture element.

A holographic element in the sense of the invention preferably comprises one or more holographic recordings (which corresponds to a "hologram") of an actual or virtually directly or indirectly computer-controlled exposure of the photo material on which the holographic recording is based, and is thus capable of refraction -, diffraction and / or reflection properties of this object to a certain extent under the specific circumstances of holographic reproduction. In particular, this allows information about the three-dimensional topology of the object to be recorded and reproduced.

The advantage here is that the holographic element itself does not have to have the topology recorded therein in its external form. For example, a flat holographic element could emulate the refractive, diffractive, and / or reflective properties of a curved object. A curved holographic element could also emulate the refraction, diffraction and / or reflection properties of a differently curved or flat object. A holographic element can also emulate the refraction, diffraction and / or reflection properties of different objects at different wavelengths.

While in a conventional photographic recording the intensity (in color photography depending on the color or wavelength) of the light falling on the photographic material is detected is, the fine-grained photo material detects the very fine interference pattern of the light waves falling on the photo material during a holographic recording. For this reason, the holographic reproduction, which corresponds to a refraction of light in the sense of the invention, generally depends strongly on the wavelength, the angle of incidence and the phase of the incident light.

About the technology of holographic recording and reproduction as well as about the possibilities that can be achieved and the respective restrictions of these techniques can be found, for example, in the published documents DE 197 03 592 AI and DE 197 00 162 AI as well as in the books and publications "Optical Holography: Principles, Techniques, and Applications (Cambridge Studies in Modern Optics) "by P. Hariharan (ISBN: 0521439655)," Introduction To Fourier Optics "by Joseph Goodman (ISBN: 0070242542)," Optical Information Processing and Holography "by W. Thomas Cathey, John Wiley & Sons, NY, 1974, "Computer Generated Holograms: Techniques and applicationsϊ by Wai-Hon Lee in E. Wolf, Progress in Optics XVI, 1978 and" Topics in Applied Physics, Vol. 20: Holography Recording Materials ", HM Smith, Edited by Springer-Verlag, Berlin, 1977 and the publications mentioned therein. The entire content of these books and publications is therefore expressly stated ch incorporated by reference into this application.

The propagation of light can be influenced via refraction, diffraction and / or reflection, the appropriate term being strongly context-dependent. In the previous section it became apparent that neither a list of the possible types of propagation change by name nor the term "change in light propagation" permits a concise, understandable wording. In the description, the term “refraction” or “breaking” is therefore used as a synonym with the actual generic term “change in propagation”.

Depending on the general conditions of the design, several holographic elements can be designed as separate units or as an integral unit.

The method and the device according to the invention preferably comprise one or more optical projection devices. In the sense of the invention, an optical projection device is any device that is capable of emitting optical signals or emitting light in a controllable manner. (Both the emitting of optical signals and the controlled emission of light are often referred to as "projection" in the rest of the application for the sake of simplicity.) The former includes, for example, lasers, laser diodes, LEDs, OLEDs, etc. The latter could be, for example Combination of a light source, one often referred to as "light valve" in technical terminology. designated modulator and a light guide arrangement that guides the light generated by the light source to the modulator. Preferably, the optical projection device itself or in cooperation with a further device is able to project light which can be determined with regard to its intensity, direction of propagation, polarization, phase, spectral composition, in particular its wavelength, and / or another of its parameters. If the parameters of the light are changed over time, this is referred to in technical jargon as "modulation".

The propagation of light is typically referred to as radiation-like. Detected or projected light is therefore often referred to in the application as a detected or projected "light beam" or "scanning beam" or "projection beam". This is particularly the case in discussions about the beam path, the beam diameter, the spectral composition and similar properties of the detected or projected light, which are often associated with the concept of a light beam.

For the purpose of guiding or shaping a detected or projected light beam, an optical scanning device or projection device according to the invention can have a light guiding device and / or a light design device. Examples of such devices, the demarcation of which is not always clear, are controllable and non-controllable mirrors, splitter mirrors, acousto-optical modulators, holographic elements, diaphragms, filters, lenses, light guides, etc.

Depending on the general conditions of the configuration, several optical signal converters, optical projection devices, light guide devices and / or light design devices can be combined with one another as separate units or integral units.

According to the invention, the projection device can in particular be used to effect the display of a picture element in three-dimensional space by illuminating at least one holographic element assigned to the respective picture element. Such illumination of a holographic element is preferably carried out selectively in order to bring about a controlled display of the respective image element. According to the invention, "selective lighting" can include both illuminating and non-illuminating and, in the case of illuminating a holographic element, illuminating such that the holographic conditions inherent in the holographic element are met, that is to say that due to the illumination the holographic element falling light is refracted according to the interference pattern recorded in the holographic element, or is not met. For the purposes of the invention, the term “picture elements” is understood to mean any physical, virtual and conceptual elements that can give an optical, “visual” impression. The invention preferably only uses those picture elements which can give rise to a multitude of optical, "pictorial" impressions. The picture elements according to the invention can include both conventional picture elements, such as pixels (two-dimensional image points) or voxels (three-dimensional spatial image points), as well as novel image elements, such as lines, surfaces, bars or cubes. Although the invention prefers picture elements of certain shapes, the invention places no limits on the shape of the picture elements ab initio.

Many features of the invention are explained in the course of this description, both in general and in the close context of a respective, specifically illustrated exemplary embodiment. Of course, each individual feature of the invention can be combined with any other feature, provided that the resulting combination does not lead to a result which the person skilled in the art can immediately recognize as nonsensical. This includes the interchangeability of a feature mentioned in the singular with a respective plurality of this feature, unless the possibility of such a singularity or plurality has not been explicitly excluded. Those modifications and alternatives of the described features and combinations of features that the person skilled in the art adds to the inventive concept and scope of the invention also belong to the invention. These statements do not relate to the determination of the commercial scope of this patent application / patent if a scope of protection is conferred by the claims under applicable law.

Features of a method are described in the present application where appropriate. A device that is suitable for carrying out the proposed method is always expressly disclosed, for example a suitably programmed computer, sensors that are able to deliver the necessary signals, signal processing devices that are able to process these signals appropriately , Etc.

It should also be explicitly pointed out that all of the described device features can be used analogously in a corresponding method for representing picture elements in three-dimensional space.

Some further preferred features and combinations of features of the invention are briefly explained below. Preferably, all or more of the holographic elements each comprise a holographic image of a difϊus reflecting or a difϊus transmitting object.

If light falls on a holographic image of an object while observing the holographic conditions, a spatial light pattern arises as if the object itself had been illuminated under the lighting conditions prevailing during the holographic image. In particular, the spatial arrangement of the object, i.e. the distance and the orientation of the object to the photo plate, recorded in the holographic image.

Difϊus reflecting or difϊus transmitting objects, such as umbrellas, are characterized by the fact that they evenly (back) scatter light falling on them over a wide angle. Ideally, this scatter is essentially independent of the wavelength. Diffusely reflecting or diffusely transmitting objects thus represent an excellent basis for the representation of mono- or multispectral picture elements. While the use of screens for the representation of pictures is known, for example, from cinema technology, pixel-by-pixel picture representation using appropriate "men screens" " unusual. The same applies to other diffusely reflecting or diffusely transmitting objects.

All or more of the holographic elements of the device according to the invention preferably each comprise a holographic image of a difϊusly reflecting or a difϊusly transmitting object, in particular a two-dimensional screen.

The advantages of such holographic recordings are described in the previous section. More information on the production and use of such holographic recordings is disclosed, for example, in the aforementioned publications DE 197 03 592 AI and DE 197 00 162 AI.

• Preferably, several of the holographic elements each comprise a holographic image of a difϊus reflecting or a difϊus transmitting surface or a difϊus reflecting or a difϊus transmitting rod, each surface and each rod corresponding to the cube surfaces or the cube edges of a coherent three-dimensional grid-shaped arrangement. The use of difϊus reflecting or difϊus transmitting screens as a template for holographic recordings for the display of picture elements according to the invention in three-dimensional space has the disadvantage that only a flat picture element corresponding to the screen surface is perceptible in a holographic display of the screen. Because of this "zero dimensionality" of a screen surface in the direction perpendicular to it, it is expensive to effect a continuously acting pictorial representation in a direction perpendicular to the holographic representation of the screen surface.

This disadvantage can be avoided, for example, by using objects with a three-dimensional dimension as a template for the holographic images encompassed by the holographic elements. Because of their radiation properties as described above, difϊus reflecting and difϊus transmitting objects with three-dimensional dimensions are particularly advantageous.

In particular, if three-dimensional structures are to be represented by selective, holographic reproduction of individual elements in space, the use of surfaces and bars corresponding to the cube surfaces and cube edges of a three-dimensional grid arrangement lends itself as a template for the holographic recordings to be reproduced. As will be explained in more detail below, only three orthogonal surfaces and edges of a respective cube have to be recorded in order to enable a complete reproduction of the lattice and surface structure of the lattice-like arrangement.

• The optical projection device is preferably able to illuminate at least one of the holographic elements with light of the wavelength with which a holographic image encompassed by the respective holographic element was taken.

According to the invention, selected holographic elements can be selectively illuminated by an optical projection device. Such a selection can be achieved, for example, in part by coordinating the wavelength of the light projected by the optical projection device for illuminating certain holographic elements. This could be used in particular in the case of a multispectral (for example red, green, blue) display in which, for example, holographic elements designed for the display of red picture elements are illuminated by a red light source, while holographic designed for the display of blue or green picture elements Elements are illuminated by a respective blue or green light source.

A coordination between the wavelength of the light projected by the optical projection device and the respective holographic recordings can also contribute to the fact that projected light is refracted as completely as possible from the respective holographic elements. In this way, a high luminosity of the picture elements represented in this way can be made possible, which contributes to the daylight suitability of the device according to the invention.

• The plurality of holographic elements preferably comprises a plurality of identical holographic elements.

A particularly inexpensive manufacture of the device can be achieved in that many of the holographic elements are identical. Existing holographic elements can be used as templates for the production of further elements, as is known to the person skilled in the art of holography. In this way, the number of holographic recordings required to produce the device can be reduced considerably.

The standardization of the holographic elements brings with them both advantages and disadvantages. The uniformity of the holographic elements can be advantageous, since this can give a uniform visual impression in the case of holographic reproduction by means of the identical holographic elements. The identity of the holographic elements can be disadvantageous in that they lack the details necessary for a perspective correct reproduction. This disadvantage would appear, for example, in a device according to the invention, in which a three-dimensional, array-like arrangement of objects is represented by a large number of holographic elements, in which all objects of a respective “depth” are represented by a two-dimensional array of identical holographic elements. The holographic elements therefore did not contain any suitable information as to whether the object to be displayed is on the left, right, above or below.

The selective illumination of holographic elements preferably comprises a spatial selection and / or a selection based on the phase, the wavelength, the angle of incidence and / or the polarization of the light projected onto the respective holographic element.

In the selective illumination of holographic elements, it is particularly important that the selection can be carried out specifically, reliably and with as little effort as possible.

The selection is preferably carried out on a spatial basis. This means that the respective holographic elements are spatially separated from one another, so that selective illumination of the respective areas, be it by light beam deflection, covering, or the like, is selective Illumination of a respective holographic element corresponds. A spatial separation of the individual holographic elements is useful, among other things, if several holographic elements are to be combined in a single holographic element, for example if a volume hologram is to contain a large number of holographic recordings, since the spatial separation prevents optical crosstalk between the individual holographic elements ,

Nevertheless, the selective illumination can take place selectively in the sense of a selective fulfillment of the holographic conditions. This can be done by selectively adjusting one or more parameters that are decisive for the fulfillment of the holographic condition, for example the phase, the wavelength, the angle of incidence or the polarization, of the light incident on the respective holographic element. This can be achieved by means known to those skilled in the art, for example filters, deflection devices, LCD elements, acoustic-optical modulators, etc. With active lighting, it is possible to modulate the light accordingly when it is generated.

• The device according to the invention preferably has only one projection device which illuminates the multiplicity of holographic elements.

In this way, the size and the overall complexity of the device can be reduced. This is particularly advantageous for portable or so-called low-budget applications. A prerequisite for such an embodiment is that the projection device, possibly in cooperation with a corresponding light processing device, is capable of carrying out the selective illumination of holographic elements according to the invention.

• The device according to the invention preferably has a multiplicity of projection devices, each of which illuminates a mutually exclusive multiplicity of holographic elements.

The use of a large number of projection devices is particularly expedient if a multispectral display is to take place or if a very large number of holographic elements are to be illuminated selectively. A large number of projection devices can also be useful in order to be able to precisely illuminate spatially separated holographic elements, for example in order to enable the image elements to be displayed for different, relatively far apart viewing angles. The device according to the invention preferably comprises an optical sensor device, the output signals of which are used to calibrate the selection process.

A modern high-resolution screen represents approximately one million pixels. If a similarly high-resolution, but three-dimensional, voxel-based display is to be achieved by the invention, then precise illumination of selected holographic elements from approximately one billion such elements would have to be carried out. Accordingly, it makes sense to provide the device according to the invention with an optical sensor device, the output signals of which can be used to calibrate the selection process.

The device according to the invention preferably comprises a multiplicity of marking holographic elements which distinguishably distinguish light incident thereon by refraction.

Analogous to the previous explanations, it is also advisable to provide the device according to the invention with marking holographic elements which refract the incident light in such a way that they can be distinguished from the other holographic elements by appropriate detection and evaluation of this refracted light, so that these marking holographic elements Elements can also be used to calibrate the selection process.

• The device according to the invention preferably comprises a

Viewing angle detection device that detects a user's viewing angle on the plurality of holographic elements and determines the selection of selectively illuminated holographic elements according to the viewing angle.

Although the device according to the invention is able to display picture elements in such a way that a spatial picture impression is created, this picture impression differs from the natural perception of an object in that the picture elements shown are merely a virtual appearance and are consequently translucent. If a realistic representation of an object is to be carried out by displaying individual picture elements, the device must ensure that picture elements remain hidden, ie are not shown, that are supposed to be "hidden" from the viewer's point of view, even if the viewer changes his point of view. This task is preferably performed by the above-mentioned viewing angle detection device. • The device according to the invention preferably comprises a controllable suspension which is able to specifically change the position and orientation of one or more components of the device.

An additional possibility of granting a perspective, three-dimensional representation is to change the position and / or orientation of one or more of the components of the device representing the picture elements vis-a-vis a predetermined viewing angle and the representation of picture elements at the same time as the change adjust accordingly. The above-mentioned controllable suspension preferably contributes to the accomplishment of this task.

The size of each picture element of the device according to the invention can preferably be represented in such a way that the respective picture element appears with a correct perspective in relation to a given viewing perspective and the perceptible position of the picture element in three-dimensional space.

When representing a picture element in three-dimensional space, many factors play a role in perspective perception. Among other things, the perceived size of an object plays a major role in the partly unconscious estimation of its distance from the viewer. It is therefore important to correctly represent the size of a picture element in perspective, so as not to cause a perspective contradiction in the viewer.

Individual features of the invention are discussed below. For the sake of clarity, the discussion of the features is structured according to subject areas.

1. General

The purpose of the device according to the invention is to display picture elements in three-dimensional space. Preferably, only a sum of the picture elements shown results in a predetermined visual content. That is, a desired visual content is composed of individual picture elements. Normally, the visual impression that results from the representation of several picture elements will differ significantly from the visual impression of a single picture element. This is comparable to the display of a full-color image on the LCD monitor compared to the display of a single pixel.

It has already been mentioned above that the picture elements according to the invention are not limited to pixels (picture elements) and voxels (spatial picture elements), but can give rise to any visual impression. The display of picture elements according to the invention is preferably effected in that an optical projection device selectively illuminates a holographic element assigned to the picture element to be displayed. The holographic element in turn preferably comprises a holographic image of a diffusely reflecting or a diffusely transmitting object. Of course, this does not exclude that a respective holographic recording also includes other objects, for example an optical lens, a mirror or another light beam changing device. For example, the holographic recording of the diffusely reflecting or diffusely transmitting object could take place through an optical lens, for example to reduce or enlarge the virtual distance of the object from the holographic photo plate or the virtual size of the object as desired.

As these examples make clear, the geometric shape of a holographically recorded object preferably corresponds to the desired geometric shape of the respective object

Image element, at least above that used in the holographic recording

Photo plate captured viewing angle. The color of one represented by holographic rendering

Image element, on the other hand, essentially corresponds to the wavelength of that for holographic

Playback used light, which in turn in accordance with the wavelength of the light used in the respective holographic recording or with that for a holographic

Playback mandatory holographic conditions must be selected. Preferably, several holographic elements recorded at corresponding wavelengths become one

Object illuminated with light of a respective primary color in order to bring about a virtual representation of an image element in any color by adding the respective primary colors.

2 perspective view

When displaying picture elements in three-dimensional space, perspective display difficulties arise which the invention overcomes by various means.

2.1 redundant holographic elements

A hologram can be compared to a window with the same dimensions and the same topology. In other words, a hologram can at best capture the insights that would be made possible by a window used instead of the hologram. From this analogy it can be seen that a single holographic element can only present a representation of an object that is very limited in comparison to reality. There is also a hologram in no way able to optimally reproduce its pictorial content across all viewing angles. The range of the best reproduction is limited to approx. ± 30 ° around a line of sight running perpendicularly through the hologram.

In order to overcome the difficulties mentioned above, the invention preferably provides for the use of a plurality of holographic elements to represent a respective picture element, each of these holographic elements preferably comprising a holographic recording of the same object on which the picture element is based from a different perspective. Taking into account the viewing angle of a viewer, the appropriate holographic element is selectively illuminated in order to ensure the perceptibility of the holographic representation from the current point of view. The determination of the viewing angle of an observer is described in more detail below.

2.2 Determining the viewing angle

From his natural environment, a viewer is used to being able to change his perspective on an object. Since the present invention wishes to comply with natural perception as much as possible, the device according to the invention preferably determines the eye position and / or the viewing direction of an observer in order to ensure the observer an optionally adapted, perspective-correct representation of the image elements in three-dimensional space.

The invention provides two preferred options for determining the eye position and / or the viewing direction of a viewer.

2.2.1 "Eye Tracking"

A very flexible way of determining the eye position and / or the direction of gaze of a viewer is the so-called "eye tracking". Retinal, corneal is used to record preferably optical signals from the viewer's eye or other characteristics of the eye. The position and / or the orientation of the eye can then be calculated on the basis of the position changes of these characteristics. The data obtained in this way can be meaningfully supplemented by using active or passive detector devices to determine the position and / or the orientation of the viewer more closely or additionally. Those skilled in the art with the international patent classification A61B 3/113 are familiar with such eye tracking devices.

2.2.2 movable frame The eye position and / or the viewing direction of a viewer relative to a picture element to be represented by the device according to the invention can also be determined by the device specifying the absolute eye position of the viewer. A change in the viewing perspective can then be realized in that the light-projecting or "refractive components of the device are partially or entirely mounted on a movable frame which is moved in accordance with the desired change in the viewing perspective. Preferably, the frame is suspended with a drive such that a precisely controllable rotational movement around three orthogonal axes is possible.

The use of a movable frame is particularly advantageous when non-spherical picture elements are used, since differently shaped picture elements have asymmetries that are in a fixed angular relationship to the holographic element. Accordingly, any finely selectable rotation of the representation of such an element either requires a large number of holographic elements which can represent the image element in the respective numerous positions, or a possibility of rotating the holographic element in relation to the viewer.

3 control

The device according to the invention preferably comprises a controller. This can provide both a perspective correct as well as a representation as close as possible to the desired visual impression.

The area of responsibility of the control system can include that the control system selects the image elements to be displayed on the basis of predetermined image data that correspond to the desired visual impression. These can be, for example, the CAD data of an architect's design. If a three-dimensional object is to be displayed, the controller could use user input to determine whether the object appears opaque, transparent or partially transparent. This is determined both by the fact that certain picture elements appear or not appear, and by the relative brightness of the respective picture elements shown. In the case of an opaque object, “hidden” picture elements, for example, are not shown from the current point of view. With a transparent object, "hidden" picture elements can be displayed darker than "non-hidden" picture elements. Other display features such as color, line width, etc. can also be determined by the control to achieve the desired visual impression. The choice of the image element to be displayed can also play a role here. For example, the device include sheet-like, rod-shaped and spherical picture elements. The use of rod-shaped picture elements would be appropriate for a representation of outlines. For a representation of homogeneous areas, the use of area-like picture elements would make sense. The spherical image elements would be helpful for displaying individual points in space.

The control can also be used to change the viewing perspective shown or perceived. If, for example, a viewer would otherwise change his actual viewing perspective of the display caused by the device according to the invention without the display changing, perspective contradictions could arise which confuse the viewer. For example, "visible" picture elements could remain hidden, while "hidden" picture elements are still visible.

A change in the viewpoint perspective shown or perceived can take place both by changing the selection of picture elements to be displayed in order to give the impression of a changed desired perspective and by changing the selection of picture elements to be displayed in order to match the display adjust the actual perspective.

A controller can also be used to control and / or calibrate the projection process. For example, the controller could be contained in a signal circuit having the projection device, a light guide device and / or a light design device and an optical sensor, with which light is projected onto holographic elements. The light is optionally refracted characteristically by markings provided in the holographic element and at least partially detected by the optical sensor, which transmits corresponding signals to the control. The control can control and / or calibrate the projection device, a light guiding device and / or a light design device in a targeted manner from the signals which are characteristic on the basis of the characteristic refraction, possibly with knowledge of the properties of the emitted light.

The present invention is described below with reference to the description of exemplary embodiments with reference to the drawings. Show it:

Figure 1 is a schematic representation of both conceptual and real objects, which can be based on a pictorial representation in three-dimensional space according to a first embodiment of the invention. 2 shows a schematic representation of a pictorial representation of a staircase-like structure in three-dimensional space according to a first exemplary embodiment of the invention;

3 shows a schematic representation of a pictorial representation in three-dimensional space according to a first exemplary embodiment of the invention;

Fig. 4 is a schematic representation of the structure and function of a device according to a second embodiment of the invention;

5 is a schematic illustration of a conventional holographic recording technique;

6A is a schematic representation of a conventional holographic recording technique;

6B is a schematic illustration of a conventional holographic rendering technique;

Fig. 7 is a schematic representation of the structure and function of a device according to a third embodiment of the invention, in which several holographic elements are assigned to a picture element.

Fig. 1

FIG. 1 schematically shows both conceptual and real objects that are based on a pictorial representation in three-dimensional space according to a first exemplary embodiment of the invention. Image elements are represented in three-dimensional space according to a three-dimensional grid arrangement, which corresponds to an arrangement of conceptual cubes 100. From the perspective modeled in FIG. 1, three surfaces 101X, 101Y and 101Z of the cube 100 are visible. The surface 101X is perpendicular to the X axis shown in the figure, while the surface 101Y or 101Z is perpendicular to the Y or Z axis shown in the figure.

According to the first exemplary embodiment of the invention, the surfaces 101X, 101 Y and 101Z are designed as separate, difϊus reflecting plates. Three holographic recordings of each of these plates are made from the same perspective with red, green and blue light. A laser light beam of the corresponding wavelength is divided into an object beam and a reference beam by means of a splitter mirror. The reference beam is directed almost directly onto a photo plate (possibly via an expansion lens to illuminate the entire photo plate), while the object beam hits the plate and is reflected by it on the photo plate. The resultant between the reference beam and the object beam Interference pattern is captured by the photo plate. This recording technique is shown schematically in Figure 5. During the recording, the plate is supported in its respective position in a manner invisible from the recording perspective, so that only the respective plate becomes the object of the recording.

The recordings can be made on common or on different photographic material, taking into account possible crosstalk of the respective recordings. It is important that the recordings differ in such a way that selective playback is possible. Such distinctive character can be achieved, for example, by taking the pictures on different areas of the photographic material and / or by individually setting the angle of incidence, the phase, the polarization and / or the wavelength of the reference beam for each picture.

After all of the plates have been holographically recorded in their respective current positions in each basic color, another series of analogue recordings takes place from the same perspective, in which the plates are shifted by one cube width, height and / or "depth. As above, the recordings can be made take place on the previous, on common or on different photo material.

This process is repeated until images of the plates are available in all primary colors for each cube of the grid arrangement.

In the lower part of FIG. 1, a cube 100 is shown in which the edges of the cube 100 “visible” from the perspective emulated in FIG. 1 are designed as separate, difϊusly reflecting rods 102X, 102Y and 102Z. The longitudinal axis of rod 102X is parallel to the X axis shown in the figure, while rods 101 Y and 101Z are oriented parallel to the Y and Z axes shown in the figure.

According to the first exemplary embodiment of the invention, holographic recordings are made of the respective rods analogously to the procedure described above with regard to the plates, so that recordings of the rods are also available in all primary colors for each cube of the grid arrangement.

The photographs of the rods are suitable for representing outlines; the recordings of the plates are suitable for displaying surfaces. This is illustrated in the following two figures.

Fig. 2 Figure 2 schematically shows a pictorial representation of a stair-like structure in three-dimensional space according to a first embodiment of the invention. Here, too, image elements are represented in three-dimensional space according to a three-dimensional grid arrangement, which corresponds to an arrangement of cubes 200. In line with the matrix-like arrangement of the cubes, they are provided in brackets with X, Y and Z coordinates.

According to the first exemplary embodiment of the invention, the stair-like structure is visualized for a viewer by selectively illuminating holographic recordings of corresponding objects. As a result of the selective lighting, picture elements appear, i.e. virtual holographic images of the respective objects, in three-dimensional space, which together give the viewer the impression of the desired, in some cases staircase-like structure. The step-like structure of Figure 2 consists of 7 picture elements. The illustration shown corresponds to a holographic representation of the following objects: plate 201Y of the cube 200 (3.1.1), plate 201Z of the cube 200 (3.1.1), plate 201Z of the cube 200 (3.2.1), plate 201Z of Cube 200 (2,2,1), plate 201Z of Cube 200 (1,2,1), plate 201Y of Cube 200 (1,3,2) and plate 201Z of Cube 200 (1,3,2) ,

The hatching used in FIG. 2 serves to identify the picture elements visible by holographic reproduction and is accordingly not to be understood as a patterning of the picture elements. Due to the holographic recording and reproduction of the object on which the picture element is based, the picture element has a pattern which corresponds to the refraction or reflection properties of the object at the wavelength used in the holographic recording. According to the first embodiment, difϊus reflecting plates and / or rods serve as the basis for the picture elements. Accordingly, the holographically reproduced picture elements appear to have a rough surface similar to a sheet of frosted glass.

The perceived color of a picture element essentially depends on the wavelength and the intensity of the light used for the holographic representation of the picture element. Because of the wavelength specificity of holographic recordings, the first exemplary embodiment of the invention, as described above, assigns three holographic recordings to a respective picture element in order to enable the picture element to be represented in each of the three basic colors. (Both here and elsewhere in the application, a "picture element" can comprise several sub-elements - here the individual color representations - or simply correspond to such a "sub-element" - ie each color representation is to be understood as an independent picture element. In line with that in display technology The usual nomenclature, according to which the term "pixel" is used to represent three subpixels in each of the primary colors, is the The term "picture element" here refers to a possibly multispectral element. ") The light falling on a respective holographic element is controlled in its effective, that is to say perceptible to an observer, such that the picture element appears to illuminate in the desired color the perceived picture element in reality from three color-different, precisely overlapping holographic representations of an object.

Kg. 3

Figure 3 shows a schematic representation of a line-like structure in three-dimensional space according to a first embodiment of the invention. Here, too, image elements are represented in three-dimensional space according to a three-dimensional grid arrangement, which corresponds to an arrangement of cubes 200. In line with the matrix-like arrangement of the cubes, they are provided in brackets with X, Y and Z coordinates.

According to the first exemplary embodiment of the invention, the line-like structure is visualized for a viewer by selectively illuminating holographic recordings of corresponding objects. As a result of the selective lighting, picture elements appear, i.e. virtual holographic images of the respective objects, in three-dimensional space, which together give the viewer the impression of the desired, line-like structure in the example. The line-like structure of FIG. 3 consists of 7 picture elements. The representation shown corresponds to a holographic representation of the following items: rod 202Z of the cube 300 (3.1.1), rod 302Y of the cube 300 (3.1.1), rod 302X of the cube 300 (3.2.1), rod 302X of Cube 300 (2,2,1), Bar 302Y of Cube 300 (1,2,1), Bar 302Z of Cube 300 (1,3,2) and Bar 302Y of Cube 300 (1,3,2) ,

In comparison with FIG. 2, FIG. 3 illustrates above all the different impression that can be created by the selective illumination of different image elements. Of course, the invention also provides for the simultaneous illumination of picture elements of different types, provided that this makes sense for the desired display.

Fig. 4

FIG. 4 shows a schematic representation of the structure and function of a device according to a second exemplary embodiment of the invention, in which a virtual three-dimensional matrix-like arrangement of screen-like picture elements is used to represent voxels in three-dimensional space. Not all picture elements are in the figure, but only four image elements of a respective level 400 (1) to 400 (4) of the arrangement lying in a row are shown.

According to the second exemplary embodiment of the invention, a laser 410 projects a light beam 413 onto a first controllably movable mirror 411, which directs the light beam 413 in the direction of a second controllably movable mirror 412. Via the second mirror 412, the light beam 413 is projected onto a pane 420 which comprises a large number of holographic elements arranged in the two-dimensional array. Due to the changeable path of the light beam 413 via the two controllably movable mirrors 411, 412, holographic elements of the pane 420 can be selectively illuminated.

Each of the holographic elements comprises a holographic image of a diffusely reflecting screen, the screen assigned to the respective holographic element being placed opposite the receiving photoplate during the holographic image in such a way that the entirety of the holographic elements encompassed by the disk 420 are images of a three-dimensional matrix-like arrangement of Screens covered. This arrangement provided for the holographic recording corresponds to the desired virtual three-dimensional matrix-like arrangement of screen-like picture elements in the case of a holographic reproduction. Thus, according to a three-dimensional matrix-like arrangement, picture elements, here voxels, can be represented virtually by selectively illuminating the holographic elements of the disk 420 assigned to the respective picture elements.

According to the figure, the light beam 413 will be refracted by a holographic element of the disk 420 such that a refracted light beam 423 strikes the eye 499 of an observer. The eye 499 lies in the limited radiation area 421 of the respective holographic element.

So that the voxels perceived by the representation of the picture elements appear to be of the same size from the viewing perspective shown, the size of the picture elements of a respective level 400 (1) to 400 (4) of the three-dimensional matrix-like arrangement decreases with increasing proximity to the viewer. Thus, the picture elements of level 400 (1) are larger than the picture elements of level 400 (2). The same applies to the levels 400 (3) and 400 (4). Accordingly, the real screens on which the virtual picture elements of level 400 (3) are based are larger than the real screens on which the virtual picture elements of level 400 (4) are based. The arrangement of the holographic elements comprised by the disk 420 need not be similar to the virtual arrangement of the picture elements. It is important that the position of a real object to be reproduced holographically as a virtual image element, which is optically recorded during the holographic recording, is selected in accordance with the position of the holographic element which will later emerge relative to the desired position of the virtual image element. In addition, the relationship between the arrangement of the holographic elements and the respective image elements of the device according to the invention would have to be known or ascertainable by the device according to the invention so that a desired display of image elements is possible at all by correctly selectively illuminating assigned holographic elements. For this purpose, markings can be provided, for example, which sensibly identify the holographic elements.

The arrangement of the holographic elements encompassed by the disk 420 could differ from the virtual arrangement of the picture elements in particular if, instead of a spatial separation, other means (for example the phase or wavelength of the light projected onto the holographic elements) are used to holographic Selectively illuminate elements.

Fig. 5

5 shows a schematic representation of a conventional holographic recording technique.

According to the figure, a laser 540 projects a light beam 530, which is split into a reference beam 531 and an object beam 532 by a splitter mirror 541. The reference beam 531 and the object beam 532 are steered by means of flat mirrors 542 in each case a suitable beam direction and then expanded via a respective lens 543. The expanded reference beam 531 'strikes a light-sensitive photo plate 550 immediately after the expansion, while the expanded object beam 532' strikes the object 500 to be recorded holographically. According to the location-dependent light refraction properties of the object 500, the expanded object beam 532 'falling on the object 500 is partially deflected as a broken object beam 532 "in the direction of the photoplate 550. The result is on the photoplate 550 between the expanded reference beam 531' and the refracted object beam 532" Interference pattern photographically captured by the photoplate 550. An interference pattern recorded in this way is referred to as a hologram.

Fig. 6 FIG. 6A shows a schematic representation of a conventional holographic recording technique analogous to the recording technique shown in FIG. 5, while FIG. 6B contains a schematic representation of a conventional holographic reproduction technique.

FIG. 6A shows an object 600 to be recorded, a reference beam 631, an object beam 632 ″ refracted on the object 600 and a photo plate 650.

Figure 6b shows a holographic representation of the object 600 holographically recorded according to Figure 6A as holographic, i.e. virtual, depicted object 600 '. According to the figure, a reproduction beam 633 is irradiated onto the photo plate 650 containing the interference pattern for holographic reproduction. Due to the interference pattern contained by the photo plate 650, light of the reproduction beam 633, which corresponds to the reference beam 631 used in the holographic recording, is refracted in such a way that a reconstructed object beam 634 is produced, which corresponds to an extension of the broken object beam 632 ″ occurring during the holographic recording The extension 634 'of the reconstructed object beam 634 on the left-hand side of the photo plate 650 in the figure thus results in a virtual object 600' for a viewer 699 of the reconstructed object beam 634 at a position corresponding to the recording position opposite the photo plate 650.

Since the interference pattern is at best able to refract the reproduction beam 633 so that it acts as an extension of the refracted object beam 632 "falling on the photoplate 650 during holographic recording, the range in which the object 600 as a virtual object is limited 600 'can be reproduced holographically. The hologram acts like a window. For an observer 699' who is outside this restricted area, the virtual object 600 'is imperceptible.

Fig. 7

FIG. 7 shows a schematic illustration of the structure and function of a device according to a third exemplary embodiment of the invention, in which a plurality of holographic elements 750A to 750E are assigned to one picture element.

According to the third exemplary embodiment, a plurality of holographic elements 750A to 750E are assigned to a picture element in order to expand the area in which holographic reproduction of a virtual object 700 ′ corresponding to the picture element is possible. As previously mentioned, the holographic element has a restricted area in which holographic reproduction of an object captured by the holographic element is possible. This is shown schematically in the figure using the holographic element 750B with a restricted area 751B.

In Fig. 7, it is assumed that each of the holographic elements 750A to 750E comprises a holographic image of the same object to be reproduced holographically, each holographic image of the object being made from a position corresponding to the later arrangement of the holographic elements. That is, the holographic recordings are made in such a way that the virtual objects 700 'that can be represented by the respective holographic elements spatially match despite the spatial arrangement of the holographic elements.

The arrangement of the holographic elements 750A to 750E preferably results in an overlap region between adjacent holographic elements in which holographic reproduction can be perceived both by the one holographic element and by the adjacent holographic element. Such an overlap area 752 between the holographic elements 750B and 750C is explicitly shown in the figure.

The display can either take place in such a way that all associated holographic elements are selectively illuminated synchronously, or in such a way that only a holographic element assigned to the current viewing angle of a viewer is selectively illuminated. The latter requires a corresponding device for detecting the viewing angle and a corresponding design and control of the projection device.

Summary

In the following, the essential points are summarized again on the basis of groups of features, each of which characterizes the invention in a special way individually and in combination with one another:

1. Device for displaying picture elements in three-dimensional space, with

a plurality of holographic elements each assigned to a picture element, and

- At least one optical projection device which causes the display of a picture element to be displayed in three-dimensional space in that it selectively illuminates at least one holographic element associated with the image element to be displayed.

2. Device according to item 1, wherein several of the holographic elements each have a holographic image of a difϊus reflecting or a difϊus transmitting

Include item.

3. Device according to item 1 or 2, wherein several of the holographic elements each comprise a holographic image of a diffusely reflecting or a diffusely transmitting screen.

4. Device according to one of the preceding points, wherein a plurality of the holographic elements each comprise a holographic image of a diffusely reflecting or a diffusely transmitting surface or a diffusely reflecting or a diffusely transmitting rod, wherein each surface and each rod corresponds to the cube surfaces or the cube edges of one Corresponding three-dimensional lattice-like arrangement.

5. Device according to one of the preceding points, wherein the optical projection device is capable of illuminating at least one of the holographic elements with light of the wavelength with which a holographic recording encompassed by the respective holographic element was made.

6. Device according to one of the preceding points, wherein the plurality of holographic elements comprises a plurality of identical holographic elements.

7. Device according to one of the preceding points, wherein the selective illumination of holographic elements comprises a spatial selection and / or a selection based on the phase, the wavelength, the angle of incidence and / or the polarization of the light projected onto the respective holographic element.

8. Device according to one of the preceding points, wherein the device has only one projection device which illuminates the plurality of holographic elements.

9. Device according to one of the preceding points, wherein the device has a plurality of projection devices, each of which illuminates a mutually exclusive plurality of holographic elements. 10. Device according to one of the preceding points, with an optical sensor device, the output signals of which are used to calibrate the selection process.

11. Device according to one of the preceding points, with a large number of marking holographic elements which distinguishably distinguish light incident thereon by refraction.

12. Device according to one of the preceding points, with a viewing angle detection device which detects the viewing angle of a user on the plurality of holographic elements and determines the selection of selectively illuminated holographic elements according to the viewing angle.

13. Device according to one of the preceding points, with a controllable suspension which is able to specifically change the position and orientation of one or more components of the device.

14. Device according to one of the preceding points, wherein the size of each picture element can be represented in such a way that the respective picture element appears with a correct size in perspective in relation to a predetermined viewing perspective and the perceived position of the picture element in three-dimensional space.

Claims

Expectations

1. Device for displaying picture elements in three-dimensional space, with - a multiplicity of holographic elements each assigned to a picture element, and

- At least one optical projection device which effects the display of a picture element to be displayed in three-dimensional space by selectively illuminating at least one holographic element assigned to the picture element to be displayed, wherein

- Several of the holographic elements each include a holographic image of a difϊus reflecting or a difϊus transmitting object.

2. Device according to claim 1, wherein several of the holographic elements each have a holographic image of a diffusely reflecting or a diffusely transmitting

Cover.

3. Device according to claim 1 or 2, wherein a plurality of the holographic elements each comprise a holographic image of a diffusely reflecting or a difϊus transmitting surface or a diffusely reflecting or a diffusely transmitting rod, each surface and each rod representing the cube surfaces or the cube edges Corresponding three-dimensional lattice-shaped arrangement.

4. Device according to one of the preceding claims, wherein the optical projection device is capable of having at least one of the holographic elements

To illuminate light of the wavelength with which a holographic image encompassed by the respective holographic element was taken.

5. Device according to one of the preceding claims, wherein the plurality of holographic elements comprises a plurality of identical holographic elements.

6. Device according to one of the preceding claims, wherein the selective illumination of holographic elements comprises a spatial selection and / or a selection based on the phase, the wavelength, the angle of incidence and / or the polarization of the light projected onto the respective holographic element.

7. Device according to one of the preceding claims, wherein the device has only a projection device that illuminates the plurality of holographic elements.

8. Device according to one of the preceding claims, wherein the device comprises a plurality of projection devices, each of which illuminates a mutually exclusive plurality of holographic elements.

9. Device according to one of the preceding claims, with an optical sensor device, the output signals of which are used to calibrate the selection process.

10. Device according to one of the preceding claims, with a plurality of marking holographic elements, which distinguishable incident light by refraction.

11. Device according to one of the preceding claims, with a viewing angle detection device that detects the viewing angle of a user on the plurality of holographic elements and determines the selection of selectively illuminated holographic elements according to the viewing angle.

12. Device according to one of the preceding claims, with a controllable suspension, which is able to specifically change the position and orientation of one or more components of the device.

13. Device according to one of the preceding claims, wherein the size of each picture element can be represented in such a way that the respective picture element appears with a correct size in perspective in relation to a predetermined viewing perspective and the perceived position of the picture element in three-dimensional space.