CN117280283A

CN117280283A - Optical system for floating holograms comprising a plurality of switchable optical channels

Info

Publication number: CN117280283A
Application number: CN202280030407.1A
Authority: CN
Inventors: 维克多·舒茨; 彼得·沃吉塞克; 西门·库尔; 马克·荣汉斯
Original assignee: Karzeisjena Co ltd
Current assignee: Karzeisjena Co ltd
Priority date: 2021-04-27
Filing date: 2022-04-27
Publication date: 2023-12-22
Also published as: CN117242406A; DE102021123515A1

Abstract

An optical system (110) includes a plurality of optical channels (31, 32). The control unit (901) can switch on and off the light sources (111, 111#) of these optical channels (31, 32), respectively. In this way, different image subjects (780-1, 780-2) of the hologram (150) may be illuminated by a plurality of different illumination sources of the at least one imaging holographic optical element (130).

Description

Optical system for floating holograms comprising a plurality of switchable optical channels

Technical Field

Various examples of the present disclosure relate to a system including a plurality of optical channels for generating a floating hologram. Each optical channel is individually controllable by a controller.

Background

Techniques for creating floating holograms by imaging Holographic Optical Elements (HOEs) are known. Such floating holograms are generated in a volume disposed outside the imaging HOE. This means that the hologram is reconstructed offset from the imaged HOE. This can create an optical "floating effect"; the hologram stands freely in space.

It is determined that the floating holograms of the corresponding optical systems may have a relatively static and less interactive form. Furthermore, such optical systems are often relatively large.

Disclosure of Invention

Accordingly, it is an object of the present invention to provide an optical system capable of producing a floating hologram. In particular, it is an object of the present invention to provide an optical system capable of providing one or more holograms dynamically. It is a further object of the invention to provide a compact optical system.

This object is achieved by the features of the independent patent claims. The features of the patent dependent claims define embodiments.

An optical system includes a plurality of optical channels that can be turned on and off, respectively. This means that light can in each case be selectively transmitted along one or more beam paths of the respective optical channel. Thus, the light sources may be controlled separately. Light is incident on one or more imaging HOEs, which respectively produce corresponding portions of a floating hologram. As a result, one or more image themes of the hologram may be turned on and off depending on which optical channel is controlled.

The optical system includes at least one imaging HOE. The at least one HOE is configured to generate a floating hologram based on the light. The floating hologram is reconstructed in a volume outside the at least one imaging HOE. Thus, the floating hologram is disposed in a volume outside the at least one imaging HOE. The optical system further includes a plurality of optical channels. The plurality of optical channels each include a light source and a beam path. The plurality of optical channels are configured to direct/conduct light along respective beam paths toward the at least one imaging HOE. The controller is configured to control the light sources for the plurality of optical channels, respectively.

Thus, controlling the light sources separately may mean that each light source may be turned on and off separately from the other light sources. This means that light can be selectively transmitted or not transmitted along the respective beam paths of the respective optical channels. In other words, this means that the individual optical channels can be controlled separately, that is to say switched separately.

Each optical channel may be associated with a different image theme of the hologram. These different image themes may provide different portions of the floating hologram. Different image themes may reproduce different geometries or images. Different image themes may also reproduce the same geometry or image, albeit in different colors.

A computer-implemented method includes separately controlling a plurality of light sources of an optical system. In this process, the plurality of light sources are controlled based on one or more decision criteria. Thus, depending on the result of the corresponding check of the one or more decision criteria, a certain light source of the plurality of light sources may be turned on or off, and another light source of the plurality of light sources may be turned off or on. Such an inspection may be performed separately for each light source.

In this case, the plurality of light sources are assigned to a plurality of optical channels of the optical system. Each of these optical channels includes an associated beam path. Each of the optical channels is configured to direct light emitted by a respective light source of the plurality of light sources toward at least one imaging HOE of the optical system. In this case, the at least one imaging HOE is configured to generate a floating hologram in a volume external to the at least one imaging HOE based on the light.

The features set forth above and those described below can be used not only in the corresponding combinations explicitly set forth, but also in other combinations or alone, without departing from the scope of the present invention.

Drawings

FIG. 1 is a schematic diagram of an optical system including an optical channel, a controller, and a depth sensor according to a number of different examples.

Fig. 2 illustrates an exemplary structural implementation of the optical system from fig. 1 according to a number of different examples.

Fig. 3 illustrates spectral filtering that may be provided by a light shaping HOE implementing a deflection element according to a number of different examples.

Fig. 4 illustrates an exemplary implementation of the optical system from fig. 1 according to a number of different examples.

Fig. 5 illustrates an exemplary implementation of the optical system from fig. 1 according to a number of different examples.

Fig. 6A illustrates an exemplary integration of an optical system with a mirror according to a number of different examples.

Fig. 6B is a perspective view of an exemplary implementation of an optical system according to fig. 2.

Fig. 7 is a flow chart of an exemplary method.

Fig. 8 is a schematic diagram of an optical system including an imaging HOE and an optical waveguide according to a number of different examples.

Fig. 9 is a perspective view of an exemplary implementation of the optical system from fig. 8 according to a number of different examples.

Fig. 10 is an implementation from fig. 9.

FIG. 11 is a schematic diagram of an optical system including a plurality of optical channels according to a number of different examples.

FIG. 12 is a schematic diagram of an optical system including a plurality of optical channels according to a number of different examples.

FIG. 13 is a schematic diagram of an optical system including a plurality of optical channels according to a number of different examples.

Fig. 14 is a perspective view of an exemplary implementation of an optical system from one of fig. 11-13 according to a number of different examples.

Fig. 15 is a perspective view of an exemplary implementation of an optical system from one of fig. 11-13 according to a number of different examples.

Fig. 16 is a side view of an exemplary implementation of an optical system from one of fig. 11-13 according to a number of different examples.

Fig. 17 is a perspective view of an implementation of the optical system from fig. 16.

Fig. 18 is a perspective view of an exemplary implementation of an optical system from one of fig. 11-13 according to a number of different examples.

Fig. 19 is a perspective view of an implementation of the optical system from fig. 18.

Fig. 20 schematically illustrates a controller for a plurality of optical channels according to a number of different examples.

Fig. 21 is a flow chart of an exemplary method.

FIG. 22 schematically illustrates menu levels of a GUI according to a number of different examples.

Detailed Description

The above-described features, and advantages of the present invention, as well as the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of exemplary embodiments, which are to be construed in greater detail in conjunction with the accompanying drawings.

The invention is explained in more detail below with reference to the drawings, based on preferred embodiments. In the drawings, like reference numerals designate identical or similar elements. The drawings are schematic representations of different embodiments of the invention. Elements illustrated in the figures are not necessarily shown to scale. Instead, the different elements shown in the drawings are presented in a manner that makes their function and general use readily apparent to those skilled in the art.

Techniques capable of producing floating holograms are described below. The hologram may reproduce an image theme, such as a button or an information sign. Holograms can also reproduce multiple image subjects. For example, one image may be composed of a plurality of image subjects, or separate image subjects may be reproduced.

For this purpose, an optical system including a plurality of optical channels is used. Each optical channel may have an assigned light source and beam path, respectively. The optical channels are configured to transmit light along respective beam paths toward at least one imaging HOE. The at least one imaging HOE is configured to generate a floating hologram based on the light. This floating hologram is reconstructed or arranged in a volume outside the at least one imaging HOE.

Holograms produced by the corresponding optical system may have a particularly high flying height and/or a particularly large depth effect. For example, the distance between the volume depicting the hologram and the at least one imaging HOE with appropriate illumination of the at least one imaging HOE may be no less than 60% of the lateral dimension (perpendicular to the distance) of the refractive index modulation region of the at least one imaging HOE.

In principle, a hologram may have one or more image subjects. Individual image subjects may be generated from light passing through different beam paths or assigned to different optical channels.

The at least one imaging HOE may be implemented as a volumetric HOE, that is, it may have a 3D refractive index variation. The corresponding refractive index modulation region has a 3D range. This refractive index change refracts light in a diffraction mode, thereby forming a hologram. The volume HOE is different from the surface HOE in that modulation of the surface of the substrate produces a diffraction pattern. For example, the surface may be wavy.

The at least one imaging HOE may be implemented as a transmissive HOE or a reflective HOE. In the case of a transmissive HOE, the refractive index modulated region is illuminated from one side and a hologram is created in the volume facing the opposite side. In the case of a reflective HOE, the refractive index modulated region is illuminated from one side and a hologram is created in the volume facing the same side.

For example, the beam path of light may be incident on the imaging HOE in a side-entry geometry (edge lit geometry). This means that the at least one imaging HOE comprises a substrate (made of a transparent material having an optical density greater than air) to which the refractive index modulation region has been applied. The corresponding beam path is coupled into the substrate on the narrow side and then passes through the substrate, for example glass or polymethyl methacrylate, before being incident on the refractive index modulation region. Typically, the layer thickness of the substrate is significantly greater than the layer thickness of the refractive index modulation region. The reconstruction angle means an angle at which light is incident on the refractive index modulation region. The refractive index modulation region may be disposed along a surface of the at least one imaging HOE. To create the hologram, light not diffracted by the refractive index modulated regions may then undergo total internal reflection at the surface of the at least one imaging HOE and be reflected back into the substrate.

In some variations, it is conceivable that the absorbing material absorbs such reflected light (beam dump); as a result, the reconstruction of the hologram is not disturbed by the "background light". However, in other examples, substrates for implementing optical waveguides are also contemplated. Light reflected back at the surface of the at least one imaging HOE is then reflected at the other surface of the optical waveguide and is again incident on the at least one imaging HOE. Thus, the optical waveguide may be disposed below and extend along the at least one imaging HOE, and light propagating in the optical waveguide may be used to fully illuminate the at least one imaging HOE. In this case, the at least one imaging HOE is applied to the outer surface of the optical waveguide. The use of an optical waveguide enables a particularly compact design, since the thickness of the substrate forming the optical waveguide can be smaller than the lateral dimension of the at least one imaging HOE. For example, it is contemplated that the thickness of the optical waveguide perpendicular to the at least one imaging HOE (i.e., in a direction extending away from the imaging HOE) does not exceed 20% of the length of the at least one imaging HOE along the optical waveguide.

For example, multiple imaging HOEs may be attached to a common optical waveguide through which light of multiple optical channels extends. One optical waveguide may also be used for each optical channel.

The light source used preferably emits light in the visible spectrum, in particular between 380nm and 780 nm. In various examples described herein, one or more light emitting diodes may be used as the light source. Light emitting diodes are particularly simple, durable and inexpensive and have sufficient optical properties with respect to a plurality of illumination functions, in particular holographic illumination functions, in particular with respect to the coherence of the emitted light. Light emitting diodes are particularly effective. For example, the light emitting diode may include a size of 0.5X0.5 mm ² And 1X 1mm ² Light emitters (active area emitting photons). In particular, for the aforementioned applications, it may be advantageous to use a small emitter surface.

The optical system may include one light source for each optical channel. The light source is configured to emit light along a respective beam path to the at least one imaging HOE. For example, the beam path may be defined by the optical axis of a corresponding optical channel with optical components. The light propagates along the beam path to the at least one imaging HOE.

For example, it is conceivable to assign a corresponding imaging HOE to each optical channel.

However, it is also conceivable to assign a single imaging HOE to multiple optical channels. Thus, this means that a continuous refractive index modulation region of the imaged HOE is present (which is phase coherently exposed) and illuminated by light from multiple beam paths. However, different techniques may be used to generate different image themes of holograms through the respective optical channels. These techniques are summarized below in the context of tables.

1.

Table 1: different variants of joint use ("multiplexing") of a common imaging HOE with light assigned to different optical channels. Thus, light may be incident on the imaging HOE from different directions. As a result, different image subjects can be produced by the individual optical channels. Since the optical channels can be switched separately, holograms can be flexibly put together by individual image subjects.

The plurality of different examples are based on the following recognition: by using at least one optical deflection element, a particularly compact structure of the corresponding optical system can be achieved. This means that light is emitted by the light source along the respective beam path and is then deflected by the optical deflecting element towards the at least one imaging HOE. This allows the light source to be arranged near or behind the at least one imaging HOE. In other words: at least one of the at least one imaging HOE may be disposed between the volume (in which the hologram is reconstructed) and the corresponding light source. What is achieved due to the optical deflection element is that the light source does not emit light directly to the at least one imaging HOE, but initially emits light to the deflection element. This may enable illumination of the refractive index modulated region of the at least one imaging HOE over a larger area than would be the case with direct illumination. A flatter reconstruction angle may be obtained. This improves the representation of the image theme of the hologram.

Such a deflection element may be implemented, for example, as a mirror. The deflecting element may also be embodied as an optical prism or by means of an optical waveguide which guides the light in the optically dense medium by means of total internal reflection.

More complex implementations of the deflection element are also conceivable. In particular, deflection element implementations are conceivable which provide other light shaping functions in addition to the deflection of the light. For this purpose, HOEs, hereinafter referred to as light shaping HOEs, may also be used.

A number of different examples are based on this recognition: further improvements in the illumination of the imaging HOE may be achieved by using a light shaping HOE that is disposed in the beam path between the light source and the imaging HOE and that deflects light in addition to the light shaping function. Thus, the light shaping HOE may implement a reversing element.

Some of such light shaping functions that a light shaping HOE may provide are described below in the context of table 2.

Table 2: the light shaping HOE may provide a plurality of different light shaping functions. By such a light shaping function, a uniform angular and wavelength spectrum of the illumination of the imaging HOE can be obtained, and thus a hologram can be reconstructed that is a large distance from the refractive index modulation region of the at least one imaging HOE and has a large depth of field.

In principle, many different implementations of the light-shaping HOE are conceivable. For example, the light shaping HOE may deflect the beam path in a reflective geometry. That is, a reflective HOE may be used. The reflected HOE is wavelength selective, that is, only light from a narrow wavelength spectrum is effectively diffracted for a particular exit angle. As a result, spectral filtering according to example I of table 2 can be achieved. For example, after spectral filtering, a full width at half maximum of the wavelength spectrum of light of not more than 10nm, in particular not more than 5nm, can be obtained. As a result, a better reconstruction of the image in the form of a hologram can be achieved, since smearing and ghosting, which would otherwise occur in the case of broadband illumination of the at least one imaging HOE, is avoided.

Similar to that described above in the context of the at least one imaging HOE, it is contemplated to attach the light shaping HOE to the outer surface of the optical waveguide. The light shaping HOE and the imaging HOE may be applied to different outer surfaces of the optical waveguide.

For example, each optical channel may have an assigned deflecting element, in particular an assigned light shaping HOE. The light-shaping HOE of the different optical channels may be formed from a common grating structure, that is, different regions of the common grating structure are illuminated by light from the different optical channels. However, a separate grating structure may also be used.

In general, there are different placement options for the optical channels. The channels may be arranged adjacent to each other, thus enabling row-by-row or column-by-column reconstruction. This means that the beam paths of the individual optical channels extend parallel or perpendicular to each other at least in sections. The optical channels may also be arranged in a grating structure, thus providing a row-by-row and column-by-column reconstruction. Furthermore, the channels may also be arranged diagonally or in a further azimuth with respect to each other. Thus, the angle between the beam paths may be in the range of 45 ° to 90 °, for example.

The beam paths may be separated by diaphragm elements. This means that the beam path may be defined, for example, by the optical axis of a particular optical element of the respective optical channel, for example, by a corresponding collimating lens.

The optical system may include a controller. This controller can switch the individual optical channels. This means that the controller may be configured to control the light sources for the plurality of optical channels, respectively.

For example, the controller may include a processor, such as a microprocessor, an application specific integrated circuit, or a field programmable switchable array. Based on the program code, the controller can perform one or more techniques for switching the optical channels.

For example, it is conceivable to configure the controller to control the light sources for the plurality of optical channels based on measurement signals of depth sensors (sometimes also referred to as distance sensors) in the optical system. The depth sensor may be configured to detect objects in or near the volume and output corresponding measurement signals.

For example, from the perspective of the user, a depth sensor may be disposed behind the imaging HOE. This means that the imaging HOE can be arranged between the volume (in which the hologram is reconstructed) and the depth sensor.

In particular, the depth sensor may thus be configured to determine the lateral position (X-Y-position) and the distance (Z-position) of the object. The light sources for the individual optical channels may then be controlled based on these characteristics.

In principle, different implementations of the depth sensor may be used. For example, a time-of-flight based sensor (TOF sensor) may be used that determines the depth position of the object based on a time-of-flight measurement of the light pulses. Laser light may also be used, that is to say laser radar (light detection and ranging) sensors may be used. In principle, the use of radar sensors which determine the depth position of an object on the basis of radar waves is also conceivable. Also, it is conceivable to use an ultrasonic sensor to determine the depth position of the object based on ultrasonic waves. When an optical depth sensor is used, it can be provided in particular that the wavelength of the light used for determining the depth position is different from the wavelength of the light used for generating the floating hologram. For example, for a depth sensor, light from the infrared range may be used, and for a floating hologram, light from the visible range may be used. By using different wavelengths, in particular the influence of the depth sensor by the hologram can be avoided. Thus, in or near the volume of the reconstructed hologram, the object can be detected with greater reliability. In particular, the lateral position and distance of the object can be determined more accurately.

The controller may be configured to use the measurement signal as a basis for determining state data indicative of user actuation of an interactive element displayed by the hologram as an image theme.

Thus, this means that image subjects reconstructed from light from different optical channels may represent interactive elements of a Graphical User Interface (GUI), such as buttons, sliders, etc. Different interactive elements may be displayed by different optical channels. Measurement signals from the depth sensor may then be used to determine whether the user is actuating one of the interactive elements.

In this process, different factors may be considered within the scope of such determination of user actuation. For example, it may be checked whether the user's fingertip is in a corresponding partial region of the volume where the interactive element is arranged (e.g. whether the user "presses" a button). For example, it is conceivable to determine such status data based on the orientation of the finger with respect to the volume. That is, it may be checked whether the finger points to the corresponding interactive element or is facing away from the interactive element. In particular, it is conceivable, for example, to determine the parallax of the observer of the hologram during the corresponding actuation. In particular, the parallax of an observer can be understood to mean the viewing direction of the observer relative to the hologram. That is, it can be checked whether the user views the hologram from a particularly oblique angle and thus the finger is also directed obliquely to the volume, as a result of which the traction element is arranged offset with respect to the spatial position of the traction element perceived therein at a relatively perpendicular angle to the observer. This may be determined, for example, by determining whether the orientation of the finger is tilted or vertical with respect to the volume. In general, the viewer's parallax may be determined based on the orientation of the fingers. Alternatively or in addition, the viewing angle of the observer can also be determined by identifying eyes in images captured by the surrounding cameras.

In particular, the depth sensor may be configured to determine the position and orientation of the finger. For example, the depth sensor may be configured to detect a finger located in a volume of about 15cm by 3 cm. In an example, the spatial resolution of the depth sensor may be 10 by 10 pixels. Such low resolution may be sufficient to determine the orientation of the finger. Further, a depth sensor may be provided that allows detecting a finger or determining its orientation at regular time intervals (e.g. every 100 ms). For example, the movement of a finger may be identified in this manner.

The controller may be configured to identify a gesture of a user's finger or hand based on the measurement signal of the depth sensor. For example, exemplary gestures are "double click", "swipe", and the like. In this case, the gesture may be determined relative to the volume. This means that a "double click" must have a specific position with respect to the volume, for example in particular with respect to the partial area in which the interactive element is displayed, in order to be recognized as a gesture.

Algorithms known in principle to those skilled in the art can be used to identify objects, orientations of objects (such as fingers) and/or gestures. Machine learning algorithms may also be used. The particular implementation of these algorithms is not critical to the functionality of the techniques described herein and, therefore, no additional details are specified.

In general, the optical systems described herein may be integrated into different applications. For example, it is conceivable that the system comprises an optical system and a mirror having a mirror surface which extends along the at least one imaging HOE and is arranged between the at least one imaging HOE and the volume from which the floating hologram is generated. For example, a graphical user interface may be generated having a plurality of interactive elements that "float" in front of the mirror surface. For example, radio buttons, or image reproduction of electronic visual displays integrated in the mirror at different positions, can be controlled in this way.

For example, another application is integration into electronic visual displays. Accordingly, a system may include an optical system and an electronic visual display extending along the at least one imaging HOE. Thus, the at least one imaging HOE may be disposed between the electronic visual display and the volume. In this way, a graphical user interface with a plurality of interactive elements may be implemented, for example, that floats on an electronic visual display of a television or computer display.

Fig. 1 illustrates various aspects related to an optical system 110. Fig. 1 is a schematic diagram of an optical system 110 configured to produce a hologram 150. Hologram 150 includes a single image theme 780, in this case a button that is an interactive element of the GUI.

In fig. 1, for example, a single optical channel 31 is shown for purposes of explaining the function. However, the optical system may have other optical channels configured similarly to the optical channel 31.

The optical system 110 includes a light source 111. The light source 111 may be implemented by one or more light emitting diodes. The light source 111 is configured to emit light 90 along a beam path 81. The light 90 is used to create a hologram 150. This defines a corresponding optical channel 31.

Various optical components 171, 120, 130 are arranged along the beam path 81.

For example, refractive or mirrored optical elements 171, 172 may be disposed in the beam path 81 between the light sources 81 adjacent to the light source 111. The refractive or mirrored optical element is configured to collect light 90. As a result, a larger light output can be obtained.

For example, the optical elements 171, 172 may be implemented by concave mirrors or lenses (i.e., collimating lenses).

Light 90 continues along beam path 81 in the direction of deflecting element 120. For example, the deflecting element 120 may be implemented as a light shaping HOE 120. A number of different light shaping functions that the light shaping HOE 120 may provide have been described above in the context of table 2.

Light 90, after being deflected by deflecting element 120 (not shown in the schematic of fig. 1), then continues along beam path 81 to imaging HOE 130. The imaging HOE 130 is configured to generate a floating hologram 150 based on the light 90.

The optical system further includes a controller 901. The controller 901 is configured to control the light source 111. This means that the controller 901 can turn the light source 111 on or off.

In this case, the controller 901 may be configured to control the light sources of a plurality of optical channels (only one optical channel 31 is shown in fig. 1) respectively. In this way, light can be selectively transmitted along the respective beam paths of the plurality of optical channels, and different image subjects 780 of the hologram 150 can be turned on or off.

In general, different decision criteria are conceivable here regarding switching on or off different light sources. For example, it is conceivable that the controller 101 is configured to control the light sources for the plurality of optical channels based on the measurement signal from the depth sensor 950. The depth sensor 950 is configured to detect an object 790, in or near the volume in which the hologram 150 is displayed, in this case a user's finger, and output a measurement signal to the controller 901.

Various structural implementations of the beam path 31 are conceivable. Some implementations are described below, for example, in the context of fig. 2.

Fig. 2 illustrates aspects related to the optical system 110. In particular, fig. 2 illustrates an exemplary structural implementation of the optical channel 31. In the example of fig. 2, the optical system 110 does not include refractive or mirrored optical elements disposed in the beam path 81 between the light source 111 and the light shaping HOE 120.

The light source 111 emits light 90 that is significantly divergent, that is to say light having a relatively wide angular spectrum. For example, fig. 2 shows light rays 90 ("ray tracing") along a beam path 81 that defines the optical channel 31.

Light 90 is incident on light shaping HOE 120. The light shaping HOE 120 includes a substrate 122 and refractive index modulation regions 121. The light shaping HOE 120 deflects the light 90 along the beam path in a reflective geometry. In addition, spectral filtering is implemented. Due to the spectral filtering, the light 90 incident on the imaging HOE 130 is more narrowband than the light 90 emitted by the light source 111 (fig. 3 shows the spectrum 601 of unfiltered light and the spectrum 602 of filtered light, and the respective associated full width at half maximum 611, 612).

Fig. 2 also depicts the reflection angle 125 at which the light shaping HOE 120 reflects light along the beam path 81. Furthermore, the angle of incidence 126 of the light 90 on the light shaping HOE 120 is also depicted. In this case, these angles 125, 126 correspond to the angles at which the reference light is incident on the imaging HOE 120 during exposure of the light shaping HOE 120 from two different laser sources.

Fig. 2 also depicts a so-called reconstruction angle 135. Reconstruction angle 135 represents the direction along which light 90 along beam path 81 is incident on index modulated region 131 of imaging HOE 130. This reconstruction angle 135 is defined by the reflection angle 125, the relative arrangement of the light shaping HOE 120 with respect to the imaging HOE 130, and the refraction at the interface of air and the substrate 132.

Next, a hologram 150 is generated in a volume 159 based on the light 90, the volume being arranged at a distance 155 from the refractive index modulation region 131 of the imaging HOE 130. Thus, a floating hologram 150 is produced.

In the example of fig. 2, the thickness 134 of the substrate 132 is sized to be relatively large. In particular, the thickness 134 of the substrate 132 is sized such that the light 90 illuminates the entire lateral surface of the refractive index modulated region 131 of the imaging HOE 130 without being reflected at the back 139 of the substrate 132 away from the imaging HOE 130. This means that in the illustrated example of fig. 2, the substrate 132 does not perform an optical waveguide function. For example, a light absorbing material (a so-called "beam dump") may be attached to the back surface 139.

In a number of different examples, one or more additional beam shaping components may be disposed along the beam path 81 between the light source 111 and the light shaping HOE 120. For example, a lens 171 (see fig. 4) or a mirror 172 (see fig. 5) may be used. As a result, the light output may be increased, that is, a greater amount of light 90 emitted by the light source 111 may be used to illuminate the imaging HOE 130.

Fig. 6A illustrates an exemplary embodiment of an optical system 110 in combination with a mirror 791, thereby defining a corresponding system 40. The mirror 791 includes a specular surface 793, for example, implemented as a thin metal backside coating of the substrate 799. Also provided in the mirrored surface 793 is a cutout 792 disposed adjacent the imaging HOE 130. Light 90 may pass through the cutout 792. For example, a partially reflective layer may be located in the cutout 792, the layer allowing light 90 in the wavelength range of the light source 111 to pass through and reflecting ambient light. A bandpass filter may be used.

As can be seen in fig. 6A, imaging HOE 130 extends along specular surface 793. In this case, the specular surface 793 is disposed between the volume forming the hologram 150 and the imaging HOE 130. The imaging HOE 130 is in turn disposed between the mirrored surface 793 and the light source 111, with the aperture 959 provided therein.

A depth sensor 950 is also provided in the example of fig. 6A. In this case, the imaging HOE 130 is disposed between the volume of the reconstructed hologram 150 and the depth sensor 950.

For example, if the depth sensor 950 uses light (rather than microwaves), light from a spectral range that is not affected by the refractive index modulation region 131 of the imaging HOE 130 may be used. For example, the light 90 used to reconstruct the hologram 150 may be in the visible spectrum, while the light from the depth sensor 950 may be in the infrared range.

The combination of the optical system 110 and the mirror 791 is only one example. It is also contemplated to form a system having an electronic visual display extending along the imaging HOE 130. In this case, the imaging HOE 130 may then be disposed between the electronic visual display and the volume, that is, the electronic visual display may be disposed behind the imaging HOE 130 (from the perspective of the viewer).

Fig. 6B is a perspective view of the beam path 31. Fig. 6B depicts the fly height 155 of the image theme 780 (on/off button) above the HOE 130. Furthermore, a deflecting element 120, such as a light shaping HOE, is visible.

Fig. 7 shows a flow chart of an exemplary method for producing an optical system. For example, the method of fig. 7 may be used to fabricate an optical system 110 according to any of the examples discussed above. The optional blocks are depicted in fig. 7 using dashed lines.

The imaging HOE is initially provided in block 3005. For example, imaging HOE 130 may be implemented according to the examples described above.

For example, block 3005 may include exposing imaging HOE 130 with reference light from a plurality of interfering laser light sources. In this way, the refractive index modulation region can be formed on the corresponding substrate. Thereby defining a reconstruction angle 135.

In principle, the person skilled in the art knows the techniques for exposing the imaged HOE and therefore a detailed description is not necessary here.

In block 3010, a light shaping HOE is provided. For example, the light shaping HOE 120 may be provided according to the examples described above.

Block 3010 may include exposing the light shaping HOE 120 to reference light from a plurality of interfering laser light sources.

In block 3015, a light source may be provided. In particular, this light source may be arranged at a suitable distance from the light shaping HOE.

The optical system thus obtained may then optionally be integrated into another unit, such as a mirror of a motor vehicle, an electronic visual display or an interior trim panel, in block 3020.

Fig. 8 illustrates aspects related to the optical system 110. Fig. 8 is a schematic diagram of an optical system 110 configured to produce a hologram 150. In principle, the optical system 110 of fig. 8 corresponds to the optical system 110 of fig. 1. However, optical system 110 in fig. 8 also includes optical waveguide 301. Optical waveguide 301 directs a beam path 81 of light 90 (generally) to imaging HOE 130. In the illustrated example, optical waveguide 301 also directs light 90 to deflecting element HOE 120 and from deflecting element 120 on to imaging HOE 130. Optical waveguide 301 may direct light to a surrounding optically thinner medium, for example, by total internal reflection at its interface.

This means that the in-coupling surface 302 of the optical waveguide 301 is arranged between the refractive or mirrored optical element 171 (e.g. a collimating lens) and the light-shaping HOE 120. For example, if a refractive collimating lens is used, the in-coupling surface 302 may be oriented perpendicular to the optical axis of the collimating lens.

However, it is also conceivable in principle for the in-coupling surface 302 to be arranged, for example, between the light-shaping HOE 120 and the imaging HOE 130.

By using the optical waveguide 301, a particularly compact structure of the optical system 110 can be achieved. For example, optical waveguide 301 may implement substrate 132 with imaging HOE 130 disposed thereon. By guiding light 90 in optical waveguide 301 and along index modulated regions 131, substrate 132 or thickness 134 of optical waveguide 301 can be sized relatively small (e.g., as compared to the case of fig. 2). This is depicted in fig. 9 and 10 for an exemplary structural implementation.

Fig. 9 is a perspective view of an exemplary structural implementation of optical system 110 of fig. 8 with optical waveguide 301. Fig. 10 is a side view of a structural implementation of the optical system 110 of fig. 9.

As is apparent from fig. 9 and 10, optical waveguide 301 is formed from a bulk material (e.g., glass or plastic). Optical waveguide 301 may be implemented as optical block 350. The deflecting element (here implemented as light shaping HOE 120) is applied to an outer surface 308 of optical waveguide 301 and imaging HOE 130 is applied to an outer surface 309 of optical waveguide 301 perpendicular to the outer surface. In general, the light shaping HOE and the imaging HOE 130 may be disposed on different outer surfaces.

As is apparent from fig. 9 (unlike fig. 2), light is incident on the refractive index modulation region 131 of the imaging HOE 130 multiple times due to reflection in the optical waveguide 301, as the optical waveguide 301 extends below the imaging HOE 130 and implements its substrate. Thus, thickness 134 is much smaller than lateral dimension 136, or in particular much smaller than the length along optical waveguide 301. In general, thickness 134 may be no greater than 20% of imaging HOE 130 along the length of optical waveguide 130.

The beam cross-section of light 90 may also decrease as thickness 134 decreases. Thus, the lateral extent of the light shaping HOE 120 may be reduced, making the design of the optical system 110 more compact.

Various aspects of the optical system 110 regarding the use of multiple optical channels are described below.

Fig. 11 illustrates various aspects related to an optical system 110. Fig. 11 is a schematic diagram of an optical system 110 configured to produce a hologram 150. The optical system 110 in the example of fig. 11 comprises two optical channels 31, 32.

The optical channel 31 corresponds to the example of fig. 8 and has been discussed in the context of fig. 8.

The optical system 110 also includes another optical channel 32. The further optical channel is realized in a similar way as the optical channel 31, that is to say it comprises a light source 111#, a light shaping HOE 171#, and an optical waveguide 301# with a corresponding input coupling surface 302 #.

Optionally, the optical system 110 may further comprise a diaphragm element 39 arranged between the optical channels 31, 32 and avoiding optical crosstalk between the optical channels 31, 32. The diaphragm element 39 may be made of a light absorbing material. The diaphragm element 39 may for example extend between the respective light sources 111, 111# up to the collimator lenses 171, 171# (or typically to refractive or mirrored optical elements as described above). After collimation, the diaphragm may be omitted.

The optical channels 31, 32 are configured accordingly in fig. 11. In general, the optical channels 31, 32 may be configured differently with respect to the arrangement and/or presence of optical elements. Several exemplary variations are listed below:

first modification: for example, optical waveguide 301 and/or optical waveguide 301# may be omitted in a manner similar to optical channel 31 in the case of fig. 1.

Second modification: although fig. 11 and the subsequent figures each show two optical channels 31, 32, in principle a greater number of optical channels can be realized.

Third modification: in the example of FIG. 11, the optical channels 31, 32 address different imaging HOEs 130, 130#, which each reconstruct the corresponding image theme 780-1, 780-2 of the hologram 150 by light 90, 90#. However, variants in which the optical channels 31, 32 address the same imaging HOE 130 (e.g., in different or overlapping regions) are also conceivable. Examples of this are shown in fig. 12 and 13.

In the example of fig. 12, the first optical channel 31 is configured to illuminate a region 801 of the imaging HOE with light 90, and the second optical channel 32 is configured to illuminate a region 802 of the imaging HOE 130 with light 90 #. The region 801 and the region 802 are arranged adjacent to each other. As a result, if both optical channels 31, 32 are activated simultaneously, a common image theme 780 can be reconstructed by light 90 and light 90 #. As a result, the corresponding image subject may have an embodiment with a particularly large area.

Instead of the implementation of the two optical channels 31, 32 in which the adjacently arranged regions 801, 802 are realized as shown in fig. 12, it is also conceivable that the optical channel 31 illuminates a first region of the imaging HOE 130 with light 90 and the optical channel 32 illuminates a second region of the imaging HOE 130 with light 90#, wherein the first region and the second region have a common overlap region. Such an example is depicted in fig. 13.

In the example of fig. 13, optical channel 31 is thus configured to illuminate region 811 of imaging HOE 130 with light 90, and optical channel 32 is configured to illuminate region 812 of imaging HOE 130 with light 90 #. Region 801 and region 802 have an overlap region 813, which is thus served by two optical channels.

In the example illustrated in FIG. 13, light 90 is used to generate image subject 780-1 within the confines of hologram 150 and light 90# is used to generate image subject 780-2 within the confines of hologram 150. These image subjects may be arranged in the same spatial region, i.e. in overlapping fashion in the volume of the hologram 150 (this is not shown in the schematic diagram of fig. 13). For example, interactive elements (e.g. buttons) may thus be displayed in the same spatial area, depending on whether the optical channel 31 or the optical channel 32 is activated.

This therefore allows changing the image theme (e.g. interactive elements of the GUI) to be displayed at the same location depending on which optical channel 31, 32 is activated. It is also possible to realize image subjects having different colors in one area (in the case where the light 90 and the light 90# are reconstructed using different wavelengths). This geometry is particularly advantageous because it allows the image subject matter to be separated in both wavelength and reconstruction angle, and this enables crosstalk between optical channels to be avoided. It is also conceivable to switch the brightness incrementally by adding separate optical channels (with the same image theme and color).

To produce different image subjects 780-1, 780-2, the corresponding separation of the optical channels may be accomplished in different ways; see table 1.

Exemplary structural implementations of optical system 110 having multiple optical channels are discussed below.

Fig. 14 is a perspective view of a device having three optical channels 31, 32, 33 with beam paths 81, 81# and 81# extending parallel to each other, respectively. A combination of light guiding elements 301, 301# # in the form of optical blocks 350 is used. For example, the collimator lenses 171, 171# are also integrally formed as a lens array. For example, the collimating lenses 171, 171# # may be manufactured in a co-injection molding process or a co-3D printing process.

Fig. 15 is an enhancement of the example of fig. 14. In fig. 15 a total of six optical channels 31-36 are used, wherein the optical channels 31-33 and 34-36, respectively, are arranged perpendicular to each other (i.e. the corresponding beam paths comprise an angle of 90 °). Channels 31-33 correspond to the example of fig. 14; channels 34-36 also correspond to the example of fig. 14.

In this manner, a row-column array may be formed for different imaging HOEs 130, or at least for different regions of a common imaging HOE. A row-column array of different image subjects may be reconstructed.

In general, the beam paths of the plurality of different optical channels may form different angles with each other, for example from 45 ° to 90 °.

Fig. 16 is another example of a possible implementation of an optical system 110 with two optical channels 31, 32 whose beam paths 81, 81# are parallel to each other, in particular at an angle of 180 ° to each other. Thus, the reconstruction angles differ by 180 ° in azimuth direction. Fig. 17 is a corresponding perspective view of the optical system of fig. 16.

Fig. 18 and 19 show the optical system 110 in two different perspective views, which is an enhancement of the optical system 110 of fig. 16 and 17. The optical system 110 in fig. 18 and 19 uses four optical channels 31-34, two of which have beam paths extending parallel to each other and correspond to the optical system 110 of fig. 16 or 17, respectively.

Fig. 20 schematically illustrates a controller according to a number of different examples. Fig. 20 shows a data processing device 901 comprising a processor 902 and a memory 903. The data processing apparatus 901 implements the controller capable of controlling a plurality of optical channels of the optical system as described above. To this end, the processor 902 may load and execute program code from the memory 903. The processor 902 is then able to turn on and off, respectively, the individual light sources associated with the different optical channels of the optical system by means of appropriate instructions output via the interface 904. Thus, the processor 902 is able to control multiple light sources from different channels separately.

An exemplary method for controlling an optical system is described below in the context of fig. 21.

Fig. 21 is a flow chart of an exemplary method. The method of fig. 21 is used to control an optical device having a plurality of optical channels. For example, the optical system 110 may be controlled as described above.

The method of fig. 21 may be performed by a controller, e.g. by the processor 902 of the data processing device 901, based on program code from the memory 903 (see fig. 20).

In block 920, a check is performed as to whether the first optical channel should be opened. For example, a check can be made for this purpose as to whether a specific image theme of the floating hologram should be displayed, wherein the image theme intended for display is produced by the first optical channel.

The check in block 920 may take into account different decision criteria. Some exemplary decision criteria are described in table 3.

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Table 3: different decision criteria may be considered separately or cumulatively in block 920.

If the first optical channel is on, then in block 925, a first light source associated with the first optical channel is turned on.

In block 930, an inspection corresponding to the inspection in block 920 is performed, but for another optical channel. Next, block 935 again corresponds to block 925, but for another optical channel. Thus, the optical channels can be controlled separately.

It goes without saying that the features of the embodiments and aspects of the invention described above can be combined with one another. In particular, these features may be used not only in the described combinations, but also in other combinations or alone, without departing from the scope of the invention.

Claims

1. An optical system, comprising:

at least one imaging Holographic Optical Element (HOE) (130) configured to generate a floating hologram (150) based on light (90), said hologram being reconstructed in a volume outside the at least one imaging HOE (130),

-a plurality of optical channels (31), each optical channel comprising a light source and a beam path configured to direct the light (90) along a respective beam path to the at least one imaging HOE (130), and

-a controller (901) configured to control the light sources (111) for the plurality of optical channels (31), respectively.

2. The optical system of claim 1, further comprising:

-a depth sensor (950) configured to detect an object (790) in or near the volume and to output a corresponding measurement signal.

3. The optical system according to claim 2,

Wherein the depth sensor (950) is configured to detect the object (790) using light having a wavelength different from the wavelength of light used to generate the floating hologram (150).

4. The optical system according to claim 2 and 3,

wherein the controller (901) is configured to control the light sources (111) for the plurality of optical channels (31) based on the measurement signal.

5. The optical system according to claim 2 to 4,

wherein the controller (901) is configured to use the measurement signal as a basis for determining status data indicative of a user actuation of an interactive element displayed by the hologram (150) as an image theme (780).

6. The optical system according to claim 5,

wherein the controller (901) is configured to determine the status data based on an orientation of the finger (790) relative to the volume.

7. The optical system according to claim 5 or 6,

wherein the controller (901) is configured to determine the status data depending on a parallax of an observer of the hologram (150).

8. The optical system according to claim 2 to 7,

wherein the at least one imaging HOE (130) is disposed between the depth sensor (950) and the volume.

9. The optical system according to claim,

wherein the hologram (150) is configured to display a plurality of interactive elements as image subjects (780-1, 780-2),

wherein the image subjects (780-1, 780-2) of the plurality of interactive elements are generated by illuminating the at least one HOE (130) with the light (90) from the respective beam paths (81, 81 #).

10. The optical system according to claim 9,

wherein at least two of the plurality of interactive elements (780-1, 780-2, 780-3, 780-4, 780-5) are arranged in the volume in an overlapping manner.

11. The optical system according to claim 10,

wherein the controller (901) is configured to display different ones of the at least two of the plurality of interactive elements depending on an operational state of a control algorithm.

12. The optical system according to claim 10 or 11,

wherein the controller (901) is configured to display different interactive elements of the plurality of interactive elements depending on a parameterization of a control algorithm.

13. The optical system of any of the preceding claims, further comprising:

-at least one deflecting element (120) configured to deflect the beam paths of the plurality of optical channels (31) towards the imaging HOE (130).

14. A system (40) comprising:

-an optical system (100) according to any one of the preceding claims, and

-a specular surface (793) extending along the at least one imaging HOE (130) and arranged between the at least one imaging HOE (130) and the volume.

15. The system (40) of claim 14, further comprising:

-a cutout (792) in the mirror surface (793) arranged in the vicinity of the imaging HOE (130).

16. The system (40) of claim 15, further comprising:

-a partially reflective layer allowing the light (90) to pass through and reflect ambient light.

17. A system, comprising:

-an optical system according to any one of claims 1 to 16, and

an electronic visual display extending along the at least one imaging HOE (130),

wherein the at least one imaging HOE (130) is disposed between the electronic visual display and the volume.

18. A computer-implemented method, comprising:

individually controlling a plurality of light sources in the optical system based on one or more decision criteria,

wherein the plurality of light sources are assigned to a plurality of optical channels of the optical system, each optical channel comprising an associated beam path and being configured to direct light emitted by a respective light source of the plurality of light sources towards at least one imaging Holographic Optical Element (HOE) of the optical system,

Wherein the at least one imaging HOE is configured to generate a floating hologram in a volume external to the at least one imaging HOE based on the light.

19. The computer-implemented method of claim 18,

wherein the one or more decision criteria include a measurement signal from a depth sensor configured to detect an object (790) in or near the volume and output a corresponding measurement signal.