Waveguide-based imaging system

Abstract

An imaging system includes a waveguide and at least two diffractive coupling-in elements configured to deflect at least some of the light incident on the coupling-in elements within the waveguide, the at least two coupling-in elements being inclined relative to each other at an inclination angle that is not equal to 0 DEG.

Description

1. Technical Field This invention relates to waveguide-based imaging systems, for example, for RGB holographic imaging cameras. An example of the invention is an imaging system based on diffractive input coupling elements for coupling incident light inputs into a waveguide.

[0002] 2. Existing Technology Diffractive optical elements (such as gratings or holograms) are preferably used to deflect light incident on a waveguide within the waveguide. For example, this allows for the creation of, for instance, custom imaging systems.

[0003] Although waveguides can be configured in many different ways, in some applications they may be implemented, for example, as one or more window panes, or integrated into window panes. Examples of multiple window panes may include, for example, laminated glass, which may comprise at least two glass panes that can be connected to each other, in their respective cases, by, for example, an interlayer made of, for example, plastic, cast resin, and / or a composite film. For example, light incident on the waveguide (e.g., the window pane) at a first location can thus be guided internally via the waveguide to another second location on the waveguide (e.g., the window pane), from which the light can then be redirected to, for example, a camera and / or an image sensor. Thus, for example, the camera may be positioned at a location different from the first location, and at that location, the camera is, for example, not visible from the outside.

[0004] In this context, diffractive optical elements can exhibit angle dependence in the spectral distribution of the deflected light. Therefore, if a diffractive element is used to collect light in an imaging system, in some cases, true-color imaging of the imaging system may only be achieved within a small area where the field of view (FOV) of the diffractive element is theoretically available. For incident angles of light outside this range of the FOV, there may be angle-dependent blue or red shifts. Diffractive optical elements typically have an FOV that encompasses a solid angle range within which incident light can be received and / or deflected by the optical element. Essentially, this may perform well at a single wavelength. For example, a monochromatic hologram is configured to deflect light of a specific wavelength from a predetermined direction (e.g., along the center of the FOV) by a specific angle. However, if the incident angle of the light deviates from the predetermined direction, an example of a hologram might cause a color different from the actual color the hologram was designed for to be deflected along the predetermined direction. If such diffractive elements are used in an imaging system, unwanted spectral angle dependence may occur: depending on the angle, only a portion of the full spectrum may be imaged, resulting in a missing spectral range. Therefore, colors different from the desired colors may be imaged in the image representation. In RGB optics, this effect may result in a white light image representation or full spectrum within a portion of the field of view (FOV), while a more significant redshift or blueshift may be present at the edges of the FOV.

[0005] Therefore, the problem solved by the present invention is to at least partially improve the corresponding imaging system, system, and associated method. 3. Summary of the Invention This objective is achieved, at least in part, through the aspects described herein.

[0007] The first aspect relates to an imaging system comprising a waveguide and at least two diffractive input coupling elements (ICEs). The at least two ICEs are configured to deflect light incident on them at least partially within the waveguide, wherein the at least two ICEs are tilted relative to each other at a tilt angle not equal to 0°.

[0008] Imaging systems with multiple ICEs (each with a field of view) have a larger field of view (FOV) compared to imaging systems with only one ICE, and furthermore, at least partially decouple the spectral angle dependence of the deflected light relative to the ICEs tilted towards each other, as described herein. This can improve the color quality and fidelity of images that can be recorded by the imaging system. This allows for an expansion of the usable area of ​​the imaging system's FOV.

[0009] General principles will refer to Figures 1a to 1d and Figures 2a to 2b To explain.

[0010] Figures 1a to 1dThis relates to an imaging system 10 with only one ICE 20, and is used to explain the fundamental problem.

[0011] Figure 1a An imaging system 10 is schematically shown in the xz plane, having an ICE 20 and an output coupling element OCE 40. The imaging system 10 also includes a waveguide 30 and a detection system 50, the waveguide having an elongated rectangular cross-section in the z-direction in the xz plane. The detection system may include, for example, a sensor and a lens. The ICE 20 is located at the upper end of the waveguide 30, to the left of the waveguide 30, and the OCE 40 is located at the lower end of the waveguide 30, to the right of the waveguide 30.

[0012] ICE 20 has a vertical field of view (v-FOV). Light incident from the v-FOV is deflected by ICE 20 into waveguide 30, as schematically shown by the black arrows. Within the waveguide, the deflected light reaches OCE 40 via total internal reflection. In other exemplary embodiments, for example, light may reach OCE 40 after undergoing more, less, or even no reflection within waveguide 30. ICE 20, waveguide 30, and OCE 40 are matched to each other in their respective shapes, extents, relative positions, and / or relative orientations such that the deflected light from ICE 20 reaches OCE 40 as efficiently as possible, and the deflected light is at least partially output from OCE and coupled to detection system 50, as schematically shown by the black arrows.

[0013] v-FOV includes aperture angle α v , among which, Figure 1a In the example, α v = 0 describes light incident perpendicularly to the surface of waveguide 30.

[0014] In principle, the deflection of light by ICE 20 and OCE 40 can depend on the incident angle of the incident light, for example, the degree of which is such that the deflection angle of the deflected light and / or the spectral distribution depends on the incident angle and / or only a portion of the light reaches OCE 40.

[0015] Figure 1b Schematally shown in the xy plane Figure 1a The cross-sectional view of the imaging system 10 allows for the display of the horizontal field of view (h-FOV) of the ICE 10. According to Figure 2b The horizontal input coupling to ICE 20 and the horizontal output coupling from OCE 40 to detection system 50 are evident, while Figure 1a The vertical component is best described.

[0016] Figure 1c Schematally shown in the yz plane Figure 1a and Figure 1bA cross-sectional view of the imaging system 10. It is evident that the ICE 20 is elongated in one direction (along the y-axis in this example) and has a shorter length in the plane of the waveguide 30 in a direction perpendicular to that direction (along the z-axis in this example). The elongated rectangular cross-section of the ICE defines the region where light incident on the ICE 20 is at least partially deflected within the waveguide 30. Since the area of ​​the OCE 40 in the plane of the waveguide 30 is smaller than that of the ICE 20, all paths along which light is deflected from the ICE 20 to the OCE 40 extend in the projection of the light onto the yz plane within a light gray trapezoidal region between the ICE 20 and the OCE 40. Light extending at least partially outside this trapezoid does not originate from the ICE 20 and / or is not incident on the OCE 40, and therefore does not play a decisive role in the imaging of the imaging system 10.

[0017] In existing technologies, such as Figures 1a to 1c The imaging systems described herein are sometimes modified to use multiple parallel holograms as ICEs and / or to use RGB holograms instead of simple monochrome holograms as ICEs. However, even such imaging systems are still plagued by the problem of spectral angle dependence, as described below by way of example: Figure 1d The diagram schematically illustrates the spectral distribution of deflected light across the entire field of view (FOV) of three parallel holograms H3 (red), H2 (green), and H1 (blue). For example, the basic arrangement of holograms H1, H2, and H3 could include parallel holograms H1, H2, and H3, which are shifted parallel to each other along an axis, for example, perpendicular to the extent of holograms H1, H2, and H3.

[0018] Holograms H1, H2, and H3 are monochrome holograms. Hologram H1 is exposed to blue light and configured to deflect the blue light at a predetermined deflection angle α. v = 0 incident on hologram H1. For example, from Figure 1a It is evident in this example that α v =0 corresponds to light incident perpendicular to the surface of the waveguide and ICE. If the incident angle deviates from α... v = 0, then it will be green or red light (in α). v >0 time) or ultraviolet light (α) v <0) Deflection occurs along the predetermined deflection angle. This is a direct consequence of the ICE being a diffractive element (in which such angle-dependent spectral shifts may occur).

[0019] Similarly, this also applies to hologram H2 for green light and hologram H3 for red light. Light deflected along a specific direction at αv A redshift occurs when the value is >0, and at α v Blue shift occurs when the angle α is less than 0. v The vertical angle representing the FOV of the hologram, and in Figure 1d Draw along the vertical axis.

[0020] Three individual holograms H1, H2, and H3 can also be written into a joint RGB hologram S with the same spectral angle dependence. Furthermore, S schematically represents the interaction of holograms H1, H2, and H3: The spectral superposition S of the deflected light from all three holograms H1, H2, H3 (or from the corresponding RGB holograms) is directly derived from the spectral angle dependence described in this paper: for the range α v Within the field of view >0, there is no blue spectral range, and for α v In cases where the value is less than 0, there is no red spectral range. In principle, the field of view (FOV) can be described not only in angular coordinates but also, for example, in Cartesian coordinates, to determine location within the FOV by position / distance. Conventionally, Figure 1d The axial direction of the vertical Cartesian axis in the middle will be the same as that of the vertical Cartesian axis in the middle. Figure 1d Angle α in v The directions are opposite.

[0021] therefore, Figure 1d This illustrates the problem upon which the present invention is based: if holograms H1, H2, and H3 are used for imaging purposes, then at a deviation from α... v It is difficult to perform true color imaging across the entire spectrum when the value is 0.

[0022] about Figures 1a to 1c For the imaging system 10 in the image, this may mean that the ICE 20 can be configured to be able to be incident at a specific angle (e.g., α). v = 0) Light of a specific color incident on the ICE is deflected to OCE 40. If the incident angle deviates from α v If = 0, then in some cases, ICE 20 may no longer be able to deflect light of that wavelength to OCE 40. Light of different wavelengths may instead satisfy the spectral conditions for deflection from ICE 20 to OCE. This relationship causes an angle-dependent redshift or blueshift in the image representation produced by the imaging system as described in this paper. Therefore, the area of ​​the imaging system's FOV cannot be imaged with the desired color, but only with a redshift or blueshift.

[0023] The inventors have recognized this problem and have at least partially remedied it using the aspects described herein, such as by using... Figure 2a and Figure 2b Described through examples: Figure 2a An exemplary imaging system 10 with three ICEs 21, 22, 23 tilted relative to each other is shown, which can at least partially solve the aforementioned problem. The relative tilt causes the following situation: if light travels at an angle α... v If the light incident on one of the ICEs 21, 22, or 23 is not equal to zero, then the spectral shift of the deflected light from the other two ICEs can be smaller or even shifted in opposite directions at some angles, and thus the spectral shifts of the individual ICEs are reduced or may even cancel each other out. Overall, this allows for an increase in the size of the field of view (FOV) and a greater proportion of the FOV that can be imaged with a reduced spectral shift.

[0024] Similar to Figure 1c The illustration shows that the three ICEs 21, 22, and 23 have rectangular fields of view (FOVs) due to their rectangular cross-sectional shapes. Each is tilted at 60° relative to the others. Therefore, the superposition of the three FOVs can be described by a hexagonal FOV (see [reference]). Figure 2b ).

[0025] Figure 2b The diagram schematically illustrates the spectral distribution of deflected light across the entire field of view (FOV) of three holograms H1, H2, and H3 (each tilted 60° relative to the others in its respective case). The three different colored stripes in the left-hand view of the FOV represent the relative positions of the light rays. Figure 1d Describes the spectral distribution within the FOV of each RGB hologram. Each hologram has a rectangular FOV. The superposition of three FOVs tilted 60° relative to each other produces... Figure 2b The hexagonal field of view (FOV) is used. Different regions within the hexagonal FOV correspond to different directions of light incident on the holograms H1, H2, and H3. Due to the different directions of the incident light, after being deflected by the holograms H1, H2, and H3, different redshifts and / or blueshifts occur. Figure 1d In contrast to the proposed scheme, the color shift did not occur equally in all three holograms H1, H2, and H3; instead, the following color reproduction appeared on the hexagonal FOV: Due to the tilt, the spectral superposition S of the deflected light from all three holograms H1, H2, and H3 does not only have a central fringe (as shown in the image). Figure 1d Instead of the case where all three colors are present in the central stripe and therefore white light is present, there are three stripes covering a large area of ​​the FOV that are tilted 60° relative to each other. Within this large area, all three colors (red, green, and blue) are deflected in a direction with a predetermined deflection angle according to the exposure of the hologram. Regions with chromatic aberration are only found in the corners of the hexagonal FOV. The diamond-shaped areas defined by dashed lines in the left and right corners of the hexagon represent regions where red and blue light are deflected, but green light is not. However, recalibration can be performed here using white balance. For example, white balance may include a (e.g., digital) image processing procedure following recording, during which, in particular, measurements corresponding to neutral white and / or gray are determined, thereby avoiding, for example, unwanted tones.

[0026] The area immediately above the FOV represents the region where the incident light is imaged by redshift, and the area immediately below represents the region where the incident light is imaged by blueshift.

[0027] The imaging of light incident at an angle corresponding to the lower corner of the hexagonal FOV is affected by redshift. The imaging of light incident at an angle corresponding to the upper corner of the hexagonal FOV is affected by blueshift.

[0028] Overall, the tilt of holograms H1, H2, and H3 thus makes them more similar to... Figures 1a to 1d Compared to the parallel arrangement in the previous example, this greatly increases the area where all colors are properly deflected.

[0029] In some examples, the tilt of the hologram may be accompanied by beam paths (e.g., central rays) between the two ICEs and their respective associated OCEs not being parallel to each other. Therefore, tilt can also involve, for example, the tilt of the central ray from the first ICE to the OCE relative to the central ray from the second ICE to that OCE (or to another OCE). In some examples, the central rays may be tilted but still remain substantially in a plane.

[0030] Typically, a diffractive ICE can be configured to at least partially deflect light incident on the ICE (e.g., transmitted from an object intended for imaging) into a waveguide, where the light can be transmitted, for example, by (total internal) reflection. Deflection can include a simple change in the direction of the light and / or, for example, focusing, collimation, and / or scattering of the incident light. This effect on the light can be caused as a whole by a single element of the ICE, or the ICE can include multiple components, each of which determines one of these effects. The ICE can include, for example, transmissive or reflective diffractive structures, transmissive or reflective volumetric holograms, mirrors, prisms, and / or transmissive or reflective relief gratings.

[0031] ICEs can be attached to the outside of the waveguide, integrated into the waveguide, etc. ICEs can be attached to different sides or the same side of the waveguide. Furthermore, a protective layer can be applied to the side of the ICE facing away from the waveguide. For example, this protective layer can substantially cover the entire surface of the waveguide, cover only a portion of the waveguide, or just barely cover the ICE. ICEs can have at least partially overlapping fields of view (FOV), only in this case is it possible to consider them as components of a (single) imaging system.

[0032] Waveguides can comprise any medium that is, in principle, suitable for transmitting light of at least one wavelength. For example, they can serve additional functions, such as as screens, windows, or windshields in vehicles. Therefore, waveguides can provide a substantially transparent body to which an ICE (Instrument, Circuit, and Equipment) can be attached. For example, waveguides can comprise glass or plastic.

[0033] There are various options for defining the tilt angle of the two ICEs relative to each other (equivalent in various exemplary embodiments): As described herein, the tilt of an ICE relative to each other can be correlated with the tilt of the ICE in the plane of the waveguide surface. For example, this could include tilting about an axis of rotation, wherein the axis of rotation is perpendicular to the waveguide surface and / or perpendicular to the surface of the corresponding ICE at the location of the respective ICE. This definition of the tilt angle may be sufficient, for example, for planar waveguides.

[0034] In some examples, it is also conceivable to define the tilt by the function of the ICE, for example in the case of curved waveguides, irregular waveguides, and / or waveguides with variable thickness. If, as described herein, the ICE comprises a hologram written, for example, by two exposures from two different directions, the first exposure defines a first direction: if light from this first direction is incident on the ICE, the ICE deflects the light in the direction of the second exposure. These two directions span a plane in space, and this allows defining characteristic axes of the ICE, which are perpendicular to the plane containing the first and second exposures of the hologram of the ICE. The tilt of the two ICEs can then be measured based on the relative tilt of the two axes relative to each other: for the two characteristic axes... and tilt angle Depend on Definition. Therefore, the tilt angle between two ICEs can be defined for waveguides of any desired shape (i.e., also for ICEs of arbitrary shape, curved and / or bent).

[0035] Another possible aspect of the tilt angle can be coupled to the joint FOV of the imaging system's ICE. For example, the effective viewing direction of the ICE can be defined. In this case, the tilt of the ICE can have, for example, a rotation angle about the effective viewing direction.

[0036] Alternatively, or in an alternative, the longitudinal axis of a typical ICE can be defined based on its geometry, such as for an ICE with a long, narrow rectangular shape. In this case, the tilt can, for example, correspond to the angle between the longitudinal axes.

[0037] In an exemplary embodiment, tilting may include tilting about an axis of rotation that may be perpendicular to the waveguide surface.

[0038] This allows for the advantageous implementation of the directions of the most obvious redshift and / or blueshift (e.g., as regarding...). Figure 2b The components described are not parallel to each other. This can reduce the unwanted effects of redshift and / or blueshift.

[0039] For example, each ICE can have its own longitudinal axis. For example, the tilt angle can correspond to the angle between the longitudinal axes.

[0040] Therefore, the advantages described in this paper can be achieved (e.g., under the same ICE) through simple tilting.

[0041] In the example, each of the ICEs may have a longitudinal axis as described herein, wherein the ICEs may be configured to deflect light incident upon them in substantially the same manner relative to the respective longitudinal axis.

[0042] The essentially identical deflection allows the use of compatible ICEs that can compensate for mutual angle-dependent spectral shifts within their respective fields of view (FOV). Furthermore, this allows for substantially symmetrical and / or regular arrangement of ICEs within the imaging system, thereby achieving approximately constant imaging quality over a larger portion of the FOV.

[0043] This deflection can occur spatially, for example, as follows: if a longitudinal axis (along the y-axis in this example) is defined for an ICE (which is rectangular in this example), the ICE can have a first length, for example, along the longitudinal axis, and a shorter second length along a second axis (along the z-axis in this example, where the y-axis and z-axis are perpendicular to each other). If light is now incident on the ICE, for example, along an x-axis perpendicular to the yz plane, the ICE can be configured to deflect the light at least partially in the z-direction, for example, so that the light is efficiently transmitted in the z-direction by internal reflection in the waveguide.

[0044] In the examples, at least one of the ICEs may include a hologram. Holograms are particularly well-suited as ICEs because they are efficient at deflecting incident light; they can exist as thin layers and thus save space. Furthermore, holograms can be adapted for their specific use in the respective imaging system through appropriate writing / exposure as described herein.

[0045] For example, the holograms described herein may include transmission holograms, reflection holograms, volumetric holograms (based on transmission or reflection), etc. Various exposure methods can be used to generate, for example, Denisjuk holograms, image plane holograms, rainbow holograms, color holograms, multiple holograms, computer-generated holograms, and / or digital holograms. This also applies to the OCEs of the exemplary embodiments described below.

[0046] In the context of the imaging system according to the invention, a hologram can therefore be used as a component of the imaging optical unit, the function of which includes deflecting incident light into the waveguide.

[0047] For example, a hologram can be recorded / exposed using two (coherent) light sources: the first and second exposures are superimposed on a medium and interfere at that medium. As a result, the intensity distribution of the two superimposed waves is a function of the phase difference between the two waves. Thus, an interference pattern corresponding to the phase information is formed. The medium may include, for example, a photosensitive plate, which chemically reacts (e.g., darkens) with the intensity distribution / interference pattern that appears on the plate due to the interference of the first and second exposures. As a result, the interference pattern is written into the photosensitive plate, thus creating a hologram. For example, darkening may occur at locations of constructive interference, while darkening is not present at locations of destructive interference.

[0048] If a hologram written in this manner is illuminated with the same reference wave as the first exposure, the original wave field will be reconstructed from the interference pattern stored in the hologram. That is, the pattern written into the medium causes the light of the reference wave to diffract, such that the beam direction of the light corresponds to the direction of the light in the second exposure.

[0049] For example, the ICE can be configured, for example, for the angle and / or point of the FOV and / or the object, to deflect incident light of at least two wavelengths at least partially within the waveguide.

[0050] While the ICE can theoretically be configured to deflect only a specific wavelength of light, in this exemplary embodiment, the ICE is capable of selectively deflecting at least one additional wavelength into the waveguide, for example, when the ICE comprises a hologram exposed at two wavelengths. This has the advantage that more colors can be imaged, and this can improve the color diversity and quality of the image representation.

[0051] As described herein, for the purpose of writing a hologram, the hologram can be exposed not only in a monochrome manner, but also, for example, in multiple wavelengths, and thus the hologram is configured to (depending on the exposure) shift between multiple wavelengths.

[0052] In the example, at least one of the ICEs may include a hologram with three or more colors (e.g., four or more), preferably an RGB hologram.

[0053] Multicolor holograms are particularly well-suited for enabling imaging and producing (near) original colors across the widest possible color gamut. Imaging with good color reproduction can be achieved, in particular, with RGB holograms, which offer advantageous exposure color selection for writing the hologram.

[0054] ICEs can include, for example, holograms. As described herein, these holograms can be written into a suitable medium (e.g., a photosensitive plate), for example, by means of monochromatic light. If, in their respective cases, monochromatic first and second exposures (as described herein) are not used, but multicolor (coherent) light is used, red, green, and blue exposures can be superimposed, for example, in each of the first and second exposures, to write a so-called RGB hologram. In this case, two, three, or more beams of different wavelengths can be spatially superimposed, for example, using a dichroic mirror. Wavelengths represented as red can include, for example, a spectral range from 650 nm to 750 nm. Wavelengths represented as green can include, for example, a spectral range from 490 nm to 575 nm. Wavelengths represented as blue can include, for example, a spectral range from 420 nm to 490 nm. Exemplary combinations can include, for example, first and second exposures using 450 nm, 540 nm, and 650 nm respectively. Alternatively, or in addition to these, exposures in other wavelength ranges can be used, such as ultraviolet (shorter than 380 nm), violet (380 nm to 420 nm), yellow (575 nm to 585 nm), orange (585 nm to 650 nm), or infrared (longer than 750 nm). Instead of multicolor exposures, two or more holograms exposed to a single color can be combined to form a hologram stack, such as an RGB stack under appropriate exposure conditions.

[0055] If multiple colors are used to write into a hologram as described in this article, the hologram will deflect incident light of multiple wavelengths depending on the exposure.

[0056] Holograms can be written into, for example, thin layers, such as photosensitive emulsions and / or photopolymers (photopolymers containing one or more photosensitive molecular groups that respond to exposure, specifically through photoinduced functional group rearrangements leading to changes in, for example, optical and / or mechanical properties) used to coat the surface of a photosensitive plate. In this case, the thin layer may include, for example, a substrate, such as gelatin with embedded photosensitive halides (e.g., silver chloride, silver bromide, or silver iodide). Incident photons may cause a chemical reaction of the halide, within which metallic silver is formed. Alternatively, this reaction can be facilitated by coating the halide with dye molecules. Thus, exposure of such a film can enable the permanent writing of holograms using exposure as described herein.

[0057] In the exemplary imaging system, the tilt angle can be between 50° and 70°. As described herein, tilting can involve tilting within the waveguide material or in a plane on the waveguide surface.

[0058] It was found that when combining, for example, three ICEs, a tilt of approximately 60° (a deviation of 10° in one direction or the other) is particularly advantageous. In such an embodiment, the spectral angular dependence of the utilized ICEs relative to each other can be well compensated for with very little cost and still a relatively small number of ICEs, and thus imaging of the desired color can be achieved over a relatively wide range of the combined FOV. Furthermore, this allows for maximizing the size of the FOV by spanning the overall FOV of the hexagon.

[0059] Similarly, more than three ICEs (or fewer) can be used in alternative solutions. For example, if six ICEs are used, they can be arranged in a substantially circular pattern around the central OCE area, as described in this article.

[0060] For example, the imaging system may also include at least one diffractive OCE, wherein the at least one OCE may be configured to output couple at least partially to deflected light from the waveguide.

[0061] If at least one diffractive OCE is used in combination with these diffractive ICEs, they can be particularly advantageously matched to each other if the ICEs and OCEs are manufactured in a similar or identical manner. For example, this could have a positive impact on the light deflection efficiency of the entire imaging system.

[0062] The at least one OCE can be attached to the outside of the waveguide, integrated into the waveguide, etc. The OCE can be attached to different sides or the same side of the waveguide. Furthermore, a protective layer for protecting the at least one OCE can be applied to the side of the OCE facing away from the waveguide. For example, such a protective layer can substantially cover the entire surface of the waveguide, cover only a portion of the waveguide, or just cover at least one OCE.

[0063] The at least one OCE may include, for example, a transmissive or reflective diffraction structure, a transmissive or reflective volumetric hologram, a mirror, a prism, and / or a transmissive or reflective relief grating.

[0064] In the example, the ICE can be configured to at least partially deflect light incident on the ICE to the at least one OCE.

[0065] In this exemplary embodiment, the ICE and the at least one OCE interact efficiently to achieve efficient input and output coupling of light, such that as large a component of the light collected by the ICE is available after being coupled to, for example, a sensor by the output of one or more OCEs. This can have a positive impact on the image quality of the image representation (e.g., contrast, sharpness, color quality, etc.).

[0066] The at least one OCE can be positioned and / or oriented on the waveguide relative to the waveguide and the ICE, such that light deflected from the ICE into the waveguide is incident on at least one OCE and then coupled out of the waveguide via at least one OCE, for example, at the location of the corresponding OCE in a direction substantially perpendicular to the waveguide surface.

[0067] For example, the at least one OCE may include a hologram.

[0068] Because holograms are efficient in output coupling of incident light, they are particularly well-suited as OCEs (Optical Characteristic Electrode), as they can exist as thin layers and thus save space. Furthermore, holograms can be adapted to their specific application in the corresponding imaging system and to the ICE (Instrumentation Equipment) utilized through appropriate writing / exposure, as described herein.

[0069] In principle, statements regarding all functionalities related to the ICE described herein apply similarly to one or more OCEs. If an OCE includes a hologram, then such OCEs can be similarly exposed or written to and, in principle, possess the same properties.

[0070] An ICE can be configured to at least partially deflect incident light of at least two wavelengths to at least one OCE.

[0071] To achieve the highest possible color quality in the image representation produced by the imaging system, it may be advantageous to use ICEs that are not merely suitable for deflecting a wavelength in a targeted manner to at least one OCE (e.g., directly or via reflection within a waveguide). This ensures good reproduction of at least two colors within at least a portion of the FOV.

[0072] For example, if a hologram is used as an ICE, this feature can be achieved by writing the ICE with at least two exposures of different wavelengths to generate the hologram, as described herein. Similarly, the at least one OCE can be configured to at least partially couple incident light of at least two wavelengths outward in a suitable direction, for example, by being written with at least two exposures of different wavelengths as described herein, such as output coupling to a detection system and / or sensor. Alternatively, a stack of monochromatic holograms can be used to achieve the same or similar functionality as the ICE and / or OCE, as described herein.

[0073] In an exemplary imaging system with at least two OCEs, the corresponding ICE and the corresponding OCE can form a pair.

[0074] Paired arrangements can represent simple and efficient configurations, where each ICE has an assigned OCE, forming a pair with it. Imaging systems can include multiple pairs and / or different pairs with substantially the same design tilted relative to each other. These different pairs can be adapted, for example, in terms of their size, position, and / or orientation, according to their desired function, so as to optimize the overall efficiency of the imaging system.

[0075] For example, the paired arrangement allows for initial internal optimization of the interaction between the ICE and OCE in a pair, and these pairs can be matched individually in terms of the interaction of each pair in the imaging system in the generation of image representation, such as matching for color quality of imaging over the largest possible area of ​​the FOV.

[0076] For example, as described herein, an ICE in a pair can be configured to deflect at least some of the light incident on the ICE in the pair to the OCE in the pair.

[0077] If an ICE and an OCE are used as a pair in their respective cases, the ICE in the pair can be configured to deflect light to the corresponding OCE in the pair in a targeted manner, and the OCE can be configured to couple the incident deflected light output out of the waveguide. This allows for precise matching between the ICE and the OCE in the pair, and vice versa, and has a positive impact on the efficiency of optical input coupling, optical deflection, and optical output coupling within the imaging system.

[0078] For example, the OCEs in a pair can be arranged substantially parallel to the ICEs in that pair. Therefore, and generally, the orientation or tilt of the OCEs can be defined in the manner described herein for the ICEs.

[0079] Parallel arrangement can achieve particularly efficient light deflection, for example by the fact that the OCE can present as large an area as possible to the light deflected by the ICE in a direction perpendicular to its effective beam path.

[0080] If, in the example, the ICE and OCE in a pair include holograms, then feature axes perpendicular to the first and second exposure directions can be defined in their respective cases, the holograms being written by means of these exposure directions, as described herein. For typical ICEs and / or OCEs, a longitudinal axis can also be geometrically defined, for example, for ICEs and / or OCEs with elongated rectangular shapes, the longitudinal axis is the perpendicular bisector along the longitudinal extent of the rectangle.

[0081] For example, in the case of parallel ICE and OCE, these characteristic axes and / or longitudinal axes can be parallel. This principle can be applied in the same way to all other possible axes that can be defined similarly for a pair of ICE and OCE.

[0082] The ICE and OCE in a pair can be implemented, for example, such that the beam path between the ICE and OCE extends substantially axially symmetrically.

[0083] Compared to, for example, an asymmetric beam path, this axisymmetric beam path from ICE to OCE can achieve more uniform light deflection efficiency across the entire imaging range because, for example, absorption losses in the beam path occur approximately uniformly across all paths the light takes. This can, for example, optimize imaging uniformity within the imaging field of view (FOV).

[0084] In an exemplary embodiment, the ICE and OCE can be arranged such that each ICE and OCE has its own axis of symmetry, and further such that they are positioned and oriented relative to each other in such a way that the ICE and OCE pair have a joint axis of symmetry. In such a configuration, the path of the deflected light from the ICE to the OCE can, for example, pass through the waveguide approximately in the trapezoidal region between the ICE and the OCE. The axis of symmetry of this trapezoid can define the effective beam path of the deflected light from the ICE to the OCE, and in this example, the beam path extends axially symmetrically.

[0085] In an example where the imaging system comprises n pairs, the tilt angle can range from (180° / n - 10°) to (180° / n + 10°).

[0086] If these n pairs are arranged according to this rule, they can cover the 180° angular range as evenly as possible, and this will cause particularly advantageous mutual compensation for the spectral angular dependence of each pair when the light is deflected from different directions in the FOV of each pair.

[0087] For example, two pairs can be arranged at approximately a 90° angle to each other, three pairs can be arranged at a 60° angle to each other, and four pairs can be arranged at a 45° angle to each other, etc.

[0088] Furthermore, if the OCEs are placed as close to each other as possible, such as in the preferred embodiment described herein, the ICEs can form a generally semicircle around the location of the OCEs. The more pairs used, the finer this semicircle can be occupied by a single ICE.

[0089] The ICEs can also be arranged in a circle around the position of the OCE. In the example of 3 pairs, the OCEs can be arranged next to each other, and the ICE tilted at 0° can be located below the OCE, the ICE tilted at 60° can be located to the upper right of the OCE, and the ICE tilted at -60° can be located to the upper left of the OCE.

[0090] For example, the imaging system can be configured such that the ICE and at least one OCE are arranged substantially axially symmetrically about an axis of symmetry.

[0091] In principle, arranging the entire imaging system symmetrically may be advantageous, as this can achieve the most uniform imaging quality across the field of view (FOV) in many applications. An exemplary preferred symmetrical embodiment is described herein.

[0092] For example, at least one OCE can have a smaller surface area than one of the ICEs.

[0093] In principle, a large ICE can be larger than an OCE in order to collect as much light as possible, as this can have a positive impact on imaging quality and the size of the field of view (FOV). The light collected in this way can then be deflected to a relatively small OCE, which, due to its smaller size, can be coupled in a concentrated form to, for example, a sensor.

[0094] The size of the ICE and / or OCE can be assessed, for example, by its area, volume, and / or extent along the characteristic axis.

[0095] In an exemplary imaging system comprising at least two OCEs, the distance between the first OCE and the second OCE may be less than the distance between the first OCE and the ICE.

[0096] The distance between the ICE and OCE allows for appropriate positioning of the input coupling and output coupling points (i.e., the location of the detection system) to achieve ideal functionality for both components depending on the application of the imaging system (e.g., for windows, windshields, screens, etc.). Furthermore, the OCEs can be arranged close to each other to couple light inputs from all OCEs into the same detection system with the smallest possible aperture.

[0097] The distances mentioned in this article can be, for example, the distance between the geometric centroids of ICE and / or OCE.

[0098] In the example, the geometric centroid of the ICE may be spaced apart from the geometric centroid of the OCE, preferably by at least 10% of the minimum distance between the ICE and at least one OCE.

[0099] In such an exemplary configuration, the OCE can be located close together in a position where, for example, a sensor or detection system can be advantageously positioned. For instance, if the imaging system is mounted in the screen, the ICE can be placed in an area of ​​the screen, and the OCE can be placed outside the usable area of ​​the screen, for example, so that the normally visible detection system can be hidden within the screen's bezel.

[0100] As described in this paper, distance can refer to the distance between the geometric centroids of the individual ICEs and / or OCEs, and / or the distance between other characteristic features of the ICEs and / or OCEs.

[0101] In contrast, when the ICE is arranged in a circle around the OCE, which is also arranged in a circle, the geometric centroid of the ICE can coincide with the geometric centroid of the OCE.

[0102] For example, a waveguide may include a first surface and a second surface opposite to the first surface, the surfaces being spaced apart from each other by a substantially constant layer thickness.

[0103] Therefore, such waveguides are particularly well-suited for guiding deflected light from the ICE to the OCE in a controlled manner with low loss via total internal reflection, which has a positive impact on the efficiency of the imaging system and the image quality.

[0104] In an exemplary imaging system, at least one of the ICEs may be substantially disposed on a first surface of the waveguide, and / or at least one OCE may be substantially disposed on a second surface of the waveguide, i.e., they are disposed on opposite sides of the waveguide. In another exemplary imaging system, at least one of the ICEs and / or at least one OCE may alternatively be substantially disposed on the same (first or second) surface of the waveguide.

[0105] If the ICE and OCE are arranged on opposite sides of the waveguide, light can be deflected from the ICE to the OCE without reflection or by means of reflection within the waveguide.

[0106] In such an exemplary embodiment, the ICE and OCE can be positioned and oriented relative to each other in the waveguide plane in order to optimize the deflection from the ICE to the OCE.

[0107] For example, ICE and OCE can be attached to the outside of the waveguide, integrated into the waveguide, etc.

[0108] In examples of holograms included in ICE and / or OCE, all holograms can be transmission holograms and / or reflection holograms, and can also be embedded in window glass or between two window panes (e.g., laminated glass).

[0109] Another aspect of the invention relates to a system comprising an imaging system as described herein and including a sensor, wherein the imaging system includes at least one OCE configured to at least partially couple a deflected light output to the sensor.

[0110] A sensor can be a suitable component that directly matches an imaging system and allows for the digital recording of the image representation created by the imaging system. This enables digital post-processing and / or stitching of the contributions of light collected and deflected by different ICEs.

[0111] The superposition of identical and / or similar points in the image representation on the sensor based on light from different ICEs can be digitally post-processed in this way and used to optionally create the final image representation by performing image post-correction. For example, displacement, distortion, different scaling ratios, etc., can be compensated for by means of this digital processing, and thus a consistent joint image can be produced.

[0112] For example, the system may also include a lens, wherein the lens may be configured to at least partially couple an optical input coupled by at least one OCE output to the sensor.

[0113] Lenses can compensate for imaging aberrations and thus improve image quality.

[0114] The lens's function can also be partially integrated into, for example, at least one OCE, for instance, by the OCE not only deflecting light (i.e., modifying the direction of the deflected light so that its output is coupled to the sensor), but also having, for example, focusing and / or diverging functions, such that the OCE, alone or in combination with the lens, applies light to the sensor in a suitable manner. In exemplary embodiments, this can be similarly applied to at least one ICE.

[0115] For example, an OCE can define an OCE aperture, and a lens can have a lens aperture whose area substantially corresponds to the area of ​​the OCE aperture.

[0116] Because of this fit, the lens aperture can be kept small.

[0117] For example, the OCE aperture can be defined as described herein with respect to the preferred embodiment, and can substantially include the region in which the OCE is attached to the waveguide.

[0118] Typically, it is advantageous to find a trade-off between sensor aperture size, waveguide thickness, ICE and / or OCE size and FOV in order to optimize the imaging system, for example, in terms of planned image representation, installation space requirements, etc.

[0119] Another aspect of the invention relates to a method for producing an imaging system, the method comprising the steps of: providing a waveguide, and preferably generating at least two diffractive ICEs on the waveguide by means of holographic exposure, the ICEs being configured to deflect light incident on these ICEs at least partially within the waveguide, wherein the generation is performed such that the at least two ICEs are tilted relative to each other at a tilt angle not equal to 0°.

[0120] For example, the method may further include generating at least one diffractive OCE on the waveguide by means of holographic exposure, wherein the at least one OCE may be configured to couple at least partially the light output deflected by the at least two ICEs to the outside of the waveguide.

[0121] This method can provide an imaging system according to the invention, and the system can have the advantages described above.

[0122] Producing at least two diffractive ICEs and / or at least one OCE on a waveguide may include, for example, producing directly at the final location of the ICE and / or OCE, and / or producing the ICE and / or OCE separately and attaching the ICE and / or OCE to the waveguide. 4. Description of the attached drawings Figure 1a A schematic view of an imaging system with input coupling elements and output coupling elements is shown in the xz plane.

[0124] Figure 1b A schematic view of an imaging system with input coupling elements and output coupling elements is shown in the xy plane.

[0125] Figure 1c A schematic view of an imaging system with input coupling elements and output coupling elements is shown in the yz plane.

[0126] Figure 1d The spectral distribution of deflected light from three parallel holograms (red, green, and blue) across the entire field of view of the three holograms is schematically shown.

[0127] Figure 2a An exemplary imaging system with three input coupling elements tilted relative to each other is shown.

[0128] Figure 2bThe spectral distribution of the deflected light of the three holograms across the entire field of view of the three holograms is schematically shown, with each hologram tilted 60° relative to the others in its respective case.

[0129] Figure 3a A view schematically shown in the waveguide plane illustrates a first exemplary configuration of an imaging system having three input coupling elements and three output coupling elements.

[0130] Figure 3b A second exemplary configuration of the imaging system is schematically shown in the waveguide plane, the imaging system having three input coupling elements and three output coupling elements.

[0131] Figure 3c A view schematically illustrating a third exemplary configuration of an imaging system is shown in the waveguide plane, the system having three input coupling elements and three output coupling elements.

[0132] Figure 3d A view schematically shown in the waveguide plane illustrates a fourth exemplary configuration of the imaging system, which has three input coupling elements and three output coupling elements.

[0133] Figure 3e A view schematically illustrating a fifth exemplary configuration of an imaging system is shown in the waveguide plane, the system having three input coupling elements and three output coupling elements.

[0134] Figure 4a A view schematically illustrating an exemplary configuration of an imaging system with three input coupling elements and a combined output coupling element is shown in the waveguide plane.

[0135] Figure 4b The schematic diagram illustrates the effect of a prism on... Figure 4a An exemplary exposure process for the output coupling element of an imaging system.

[0136] Figure 5 A view schematically illustrating an exemplary configuration of an imaging system with two input coupling elements and two output coupling elements is shown in the waveguide plane.

[0137] Figure 6a A schematic view of an imaging system is shown in the xz plane, which has an input coupling element, an output coupling element, and a waveguide with a wedge-shaped cross section.

[0138] Figure 6b A schematic view of an imaging system is shown in the xz plane, which has an input coupling element, an output coupling element, and a waveguide that bends in the xz plane. 5. Detailed Implementation Figures 3a to 3e Cross-sections of various exemplary embodiments of the imaging system 10 are shown, each imaging system having three ICEs 21, 22, 23 and three OCEs 41, 42, 43. For clarity, only ICEs 21, 22, 23 and OCEs 41, 42, 43 are shown here. For example, the imaging system 10 may also include, for example, waveguides (not shown) and optionally detection systems (not shown), as described herein. Figures 1a to 1c , Figure 6a and Figure 6b As described. Figures 3a to 3e The imaging systems in each pair comprise three pairs, each pair including one ICE and one OCE: pair 1 with ICE 21 and OCE 41, pair 2 with ICE 22 and OCE 42, and pair 3 with ICE 23 and OCE 43. In this configuration, ICE 21, 22, and 23 in each pair can always be configured to at least partially deflect the incident light through the waveguide to the corresponding OCE 41, 42, and 43 in that pair, as schematically illustrated by light gray trapezoids. Figures 3a to 3e The observation direction in the middle corresponds to Figure 1c The direction of observation. In the following text, the waveguide plane (for a cuboid waveguide) should be understood as... Figure 1c The yz plane.

[0140] The tilt angles of the ICE and OCE in this paper refer to the relative tilt between the ICE and / or between the OCE, such as tilt relative to their longitudinal axes (in the waveguide plane and / or in the projection plane (e.g., in the case of curved waveguides and / or waveguides with non-parallel surfaces)). For each ICE, there exists an effective direction along which the ICE deflects light to the associated OCE. For example, this can be geometrically defined as an axis extending through the geometric centroids of the ICE and the OCE. Therefore, relative tilt can also include relative tilt through axes passing through the respective geometric centroids (e.g., ...). Figure 3a (As shown by the dashed line in the diagram). If the ICE and OCE are arranged symmetrically with respect to each other, the axis can coincide with the axis of symmetry of the pair consisting of the ICE and OCE, and extend centrally through the trapezoid, as described herein, which is covered by all beam paths from the ICE to the OCE.

[0141] Figure 3a A view schematically shown in the waveguide plane is a first exemplary configuration of the imaging system 10, which has three ICEs 21, 22, 23 and three OCEs 41, 42, 43. Figure 3aAll three pairs include identical ICEs 21, 22, 23 and OCEs 41, 42, 43, which differ only in their relative positioning and orientation. The first pair, 21, 41, is tilted -60° relative to the second pair, 22, 42, in the waveguide plane, and the third pair, 23, 43, is tilted +60° relative to the second pair, 22, 42, in the waveguide plane. OCEs 41, 42, 43 are arranged such that their corners pointing towards the ICEs 21, 22, 23 in their respective pairs are approximately located on a common circular path. Figure 3a On the dashed circular path in the middle, and in their respective cases, they touch (or are close to) the corners of adjacent OCEs (OCE 41 and OCE 42, and OCE 42 and OCE 43).

[0142] The first pair, 21, 41, has an axis of symmetry S1; the second pair, 22, 42, has an axis of symmetry S2; and the third pair, 23, 43, has an axis of symmetry S3. In each pair, ICEs 21, 22, 23 and OCEs 41, 42, 43 are designed such that the trapezoid (shown in light gray) crossed by the beam path between ICEs 21, 22, 23 and OCEs 41, 42, 43 extends substantially axially symmetrically with respect to the corresponding axes of symmetry S1, S2, S3 described herein. Due to the symmetrical arrangement of these three pairs, axis S2 also represents the axis of symmetry of the entire imaging system 10.

[0143] OCE 41, 42, and 43 can define the OCE aperture, for example... Figure 3a The region within the dashed circular path in the diagram. Other definitions of the OCE aperture are also possible, such as the smallest possible circle, the smallest possible hexagon, pentagon, quadrilateral, triangle, and / or other possible geometries and / or configurations that can be drawn around the OCE in the waveguide plane. In principle, optional detection systems (not shown; see, for example, see...) Figure 1a and Figure 1b This may include a lens aperture. To ensure the components of the system are fitted together, the area of ​​the lens aperture may substantially correspond to the area of ​​the OCE aperture. See section 3b below. Figure 3e Exemplary embodiments are shown, and these exemplary embodiments are related to Figure 3a Compared to the previous embodiment, the area of ​​the OCE aperture is particularly reduced.

[0144] Figure 3b A second exemplary configuration of the imaging system 10, having three ICEs 21, 22, 23 and three OCEs 41, 42, 43, is schematically shown in the waveguide plane. Figure 3aCompared to their counterparts in the imaging system 10, pair 1, with ICE 21 and OCE 41, is closer to pair 3, with ICE 23 and OCE 43, and therefore the corners of OCE 41 and OCE 43 located closest to the center of the imaging system 10 are in contact (or nearly in contact). Otherwise, pair 1 and pair 3 have... Figure 3a The same size and relative positioning as the imaging system 10 in the middle.

[0145] also, Figure 3b The imaging system includes a second pair with ICE 22 and OCE 42. OCE 42 has been moved downwards so that its two upper corners are in contact (or nearly in contact) with the corners of OCE 41 and OCE 43, respectively. Therefore, the OCE aperture (dashed circular path) is smaller than... Figure 3a The aperture in the middle (see the comparison of the dashed circular path). Similar to OCE 42 in the second pair, ICE 22 in the second pair has been relative to... Figure 3a Its position in the middle is moved downwards, and it is also reduced in its longitudinal range (see Having Figure 3a (Compare the size of the dashed rectangle to that of ICE 22). This reduction in size is necessary so that ICE 22 is not located within the trapezoidal region where light is deflected within the waveguide from ICE 21 to OCE 41 or from ICE 23 to OCE 43. Otherwise, the deflected light might be incident on ICE 22 and undesirable from there, thus resulting in imaging loss.

[0146] Therefore, all three pairs themselves, as well as the entire imaging system 10, are in Figure 3b The imaging system 10 is axially symmetric.

[0147] Therefore, with Figure 3a Compared to imaging systems, Figure 3b The imaging system 10 has relatively large ICEs 21, 22, 23 and OCEs 41, 42, 43 relative to the OCE aperture, which has a favorable effect on the contrast and vignetting (darkening of the image representation at the edges of the FOV). However, since the size of ICE 22 needs to be reduced, the FOV and / or color information of ICE 22, and thus the entire imaging system 10, will be reduced.

[0148] Figure 3c A third exemplary configuration of the imaging system 10 is schematically shown in the waveguide plane, the imaging system having three ICEs 21, 22, 23 and three OCEs 41, 42, 43. OCEs 41, 42, 43 are connected to... Figure 3b They are arranged in the same way as in other vehicles. However, ICE 21, 22, and 23 are different from... Figure 3bThe ICE in the imaging system 10 differs in the following ways: ICE 22 has its full size, for example, an image Figure 3a Similar to the previous model, the longitudinal range of ICE 21 and 23 is reduced on the side facing ICE 22 in their respective cases (see [reference needed]). Figure 3a (The size of ICE 21 and 23 is represented by a dashed rectangle). This reduction in size is necessary so that ICE 22 is not located within the trapezoidal regions where light is deflected from ICE 21 and ICE 23 to OCE 41 and OCE 43 within the waveguide, respectively, and this reduction represents a change in size. Figure 3b The described alternative procedure for reducing the length of ICE 22. Otherwise, the deflected light may be incident on ICE 22 and is not expected to be deflected from there, thus resulting in imaging loss.

[0149] Therefore, the two external pairs 1 21, 41 and 3 23, 43 are not axisymmetric in the imaging system 10 of 3c, but the internal pairs 2 22, 42 and the entire imaging system 10 are axisymmetric.

[0150] The result is that Figure 3c Imaging system 10 has appeared with Figure 3b Imaging system 10 (with) Figure 3a Compared to imaging systems, it has similar advantages and disadvantages.

[0151] Figure 3d A fourth exemplary configuration of the imaging system 10, having three ICEs 21, 22, 23 and three OCEs 41, 42, 43, is schematically shown in the waveguide plane.

[0152] OCEs 41, 42, and 43 are arranged relative to each other such that two corners on one of their short edges are in contact (or nearly in contact) with corners on one of the short edges of the two adjacent OCEs. Figures 3a to 3c Similarly, ICEs 21, 22, and 23 are equidistant from their corresponding OCEs 41, 42, and 43 in their respective pairs. To prevent ICEs 22 and 23 from overlapping, both are reduced in their longitudinal extent (see [reference needed]). Figure 3a (Compare the dashed rectangles of size ICE 22 and 23). As a result, the entire imaging system 10, as well as 2 22, 42 and 3 23, 43 themselves, are not symmetrical. Only 1 21, 41 itself is axially symmetrical.

[0153] Figure 3eA fifth exemplary configuration of the imaging system 10, having three ICEs 21, 22, 23 and three OCEs 41, 42, 43, is schematically shown in the waveguide plane.

[0154] and Figures 3a to 3d In comparison, the sizes of OCE 21 and 23 are slightly reduced, so that OCE 41, 42, and 43 are arranged in a compact manner within the dashed circle (OCE aperture) without needing to reduce the size of any of ICE 21, 22, and 23.

[0155] therefore, Figure 3e The configuration of the imaging system 10 allows for a small OCE aperture while maintaining a large size for ICEs 21, 22, and 23. The reduction in the size of OCEs 41 and 43 only negatively impacts color information, contrast, and the quality of image representation (in terms of vignetting).

[0156] Figure 4a A schematic view of an exemplary configuration of an imaging system is shown, having three ICEs 21, 22, 23 and a combined OCE 40, which can be arranged, for example, in a waveguide plane. In this case, ICEs 21, 22, 23 are configured to deflect light incident on ICEs 21, 22, 23 at least partially within the waveguide to OCE 40. In this case, one OCE 40 is configured to couple at least partially the deflected light output from the three ICEs 21, 22, 23 outside the waveguide to a detection system (not shown). If OCE 40 includes, for example, a hologram, this hologram can be written through its exposure, enabling this functionality. Figure 4b The text describes in detail one possibility for performing such exposure.

[0157] Essentially, Figure 4a OCE 40 in the middle simultaneously achieved Figures 3a to 3e The three functions of OCE. Suitable production of OCE 40 (e.g.) Figure 4b (As illustrated in the example) This allows for the avoidance of filtering effects that would otherwise occur when multiple OCEs are arranged one after the other along the output coupling direction of the deflection light. Therefore, for example, with Figure 3a The OCE aperture of the imaging system 10 is compared (see the dashed circle for comparison). Figure 4a The imaging system 10 has a particularly small OCE aperture (dashed circle), and for example, there is no need to reduce the size of ICE 21, 22, 23 to avoid possible overlap between and / or with the beam paths of adjacent ICE 21, 22, 23.

[0158] Figure 4b Schematic illustration of 60 pairs of prisms Figure 4a An exemplary exposure process for the OCE 40 of the imaging system 10. For this purpose, as described herein, three first exposures B1-1, B1-2, and B1-3 are applied to the OCE 40 in a combined manner via the exposure of the prism 60 to write a hologram into the OCE. Additionally, second exposures B2-1, B2-2, and B2-3 are also directed to the OCE 40 of all three first exposures B1-1, B1-2, and B1-3, causing interference to occur there, and will... Figures 3a to 3e The functions originally distributed among the three OCEs are written into the joint OCE 40. The hologram produced in this way can be configured to couple / deflect the deflected light outputs from three different directions (directions of the first exposure B1-1, B1-2, B1-3) to the joint direction (direction of the second exposure B2-1, B2-2, B2-3). For example, as described herein, the first exposure B1-1, B1-2, B1-3 and / or the second exposure B2-1, B2-2, B2-3 can be monochromatic or multicolor (e.g., RGB).

[0159] In addition to imaging systems with three ICEs (such as...) Figures 3a to 4a In addition to (as shown in the example), imaging systems with more or fewer ICEs are also possible.

[0160] Figure 5 An exemplary configuration of imaging system 10, having two ICEs 21, 22 and two OCEs 41, 42, is schematically shown in the waveguide plane: The two ICEs 21 and 22 are tilted 90° relative to each other in the plane of the waveguide (not shown). The same applies to OCE41 and 42. Essentially, the imaging system 10 comprises two pairs: pair 1, which includes ICE 21 and OCE 41, and pair 2, which includes ICE 22 and OCE42.

[0161] Although for the sake of simplicity Figures 1a to 1c An imaging system with a waveguide that is essentially a cuboid is shown, but other waveguide shapes are also possible: For example, Figure 6a A view of the imaging system 10, which has an ICE 20, an OCE 40, and a waveguide 30 with a wedge-shaped cross-section, is shown in the xz plane. In this case, the two sides of the waveguide 30 (to which the ICE 20 or OCE 40 is attached, in their respective cases) are not parallel to each other. As described herein, the OCE 40 couples the deflected light output to the detection system 50.

[0162] Figure 6bAn imaging system 10 is schematically shown in the xz plane, comprising an ICE 20, an OCE 40, and a waveguide 30 curved in the xz plane. The exemplary waveguide 30 has a constant thickness and curvature in the xz plane. Alternatively, the waveguide 30 may also have curvature in the xy and / or yz planes. The corresponding curvature on different segments of the waveguide 30 may be uniform or non-uniform, even reaching completely irregular curvature. As described herein, the OCE 40 couples the deflected light output to the detection system 50.

[0163] Figure 6a The relative tilt of the two sides of waveguide 30 and Figure 6b The curvature of the waveguides will not impede the functionality of the imaging system 10. The functionality described in this paper can be transferred to... Figure 6a and Figure 6b The imaging system 10 is coupled to the output of the corresponding detection system 50 as described herein.

Claims

1. An imaging system (10), comprising: a waveguide (30); and at least two diffractive in-coupling elements, ICEs (21, 22, 23); wherein the at least two ICEs (21, 22, 23) are configured to at least partially deflect light incident on the ICEs (21, 22, 23) within the waveguide (30); wherein the at least two ICEs (21, 22, 23) are tilted with respect to each other by a tilt angle which is not equal to 0°. The tilt comprises a tilt around an axis of rotation perpendicular to a waveguide surface.

2. The imaging system (10) of claim 1, wherein, The ICEs (21, 22, 23) each have a longitudinal axis, and the tilt angle corresponds to an angle between the longitudinal axes.

3. The imaging system (10) of claim 1 or 2, wherein The ICEs (21, 22, 23) each have a longitudinal axis, and wherein the ICEs (21, 22, 23) are configured to deflect light incident on the ICEs with respect to the respective longitudinal axis in substantially the same way.

4. The imaging system (10) of any one of claims 1 to 3, wherein, At least one of the ICEs (21, 22, 23) comprises a hologram.

5. The imaging system (10) of any one of claims 1 to 4, wherein, The ICEs (21, 22, 23) are configured to at least partially deflect light of at least two wavelengths within the waveguide (30).

6. The imaging system (10) of any one of claims 1 to 5, wherein, At least one of the ICEs (21, 22, 23) comprises a hologram having three or more colors, preferably an RGB hologram.

7. The imaging system (10) of any one of claims 1 to 6, wherein, The tilt angle is between 50° and 70°.

8. The imaging system (10) of any one of claims 1 to 7, wherein, The at least one OCE (41, 42, 43) is configured to at least partially out-couple deflected light from the waveguide (30).

9. The imaging system (10) according to any one of claims 1 to 8, further comprising at least one diffractive output coupling element OCE (41, 42, 43), wherein, The ICEs (21, 22, 23) are configured to at least partially deflect light incident on the ICEs (21, 22, 23) to the at least one OCE (41, 42, 43).

10. The imaging system (10) of claim 9, wherein, The at least one OCE (41, 42, 43) comprises a hologram.

11. The imaging system (10) of any one of claims 9 and 10, wherein, The ICEs (21, 22, 23) are configured to at least partially deflect light of at least two wavelengths to the at least one OCE (41, 42, 43).

12. The imaging system (10) of any one of claims 9 to 11, wherein, A respective ICE (21, 22, 23) and a respective OCE (41, 42, 43) form a pair.

13. The imaging system (10) of any one of claims 9 to 12, having at least two OCEs (41, 42, 43), wherein, An ICE (21, 22, 23) in a pair is configured to deflect at least some of the light incident on the ICE (21, 22, 23) in the pair to an OCE (41, 42, 43) in the pair.

14. The imaging system (10) of claim 13, wherein, An OCE (41, 42, 43) in a pair is arranged substantially parallel to an ICE (21, 22, 23) in the pair.

15. The imaging system (10) of any one of claims 13 and 14, wherein, An ICE (21, 22, 23) and an OCE (41, 42, 43) in a pair are implemented such that a beam path between the ICE (21, 22, 23) and the OCE (41, 42, 43) extends substantially axially symmetrically.

16. The imaging system (10) of any one of claims 13 to 15, wherein, The imaging system (10) comprises n pairs, and the tilt angle is in the range from (180° / n - 10°) to (180° / n + 10°).

17. The imaging system (10) of any one of claims 13 to 16, wherein, ​ 18. The imaging system (10) of any one of claims 9 to 17, wherein, The ICEs (21, 22, 23) and the at least one OCE (41, 42, 43) are arranged substantially axially symmetric around a symmetry axis.

19. The imaging system (10) of any one of claims 9 to 18, wherein, The at least one OCE (41, 42, 43) has a smaller surface than one of the ICEs (21, 22, 23).

20. The imaging system (10) of any one of claims 9 to 19, comprising at least two OCEs (41, 42, 43), wherein, The distance between a first OCE (41, 42, 43) and a second OCE (41, 42, 43) is smaller than the distance between the first OCE (41, 42, 43) and an ICE (21, 22, 23).

21. The imaging system (10) of any one of claims 9 to 20, wherein, The geometrical center of mass of the ICEs (21, 22, 23) is spaced apart from the geometrical center of mass of the OCEs (41, 42, 43), preferably by at least 10% of the smallest distance between an ICE (21, 22, 23) and the at least one OCE (41, 42, 43).

22. The imaging system (10) of any one of claims 1 to 21, wherein, The waveguide (30) comprises a first surface and a second surface opposite to the first surface, the surfaces being spaced apart from each other by a substantially constant layer thickness.

23. The imaging system (10) of claim 22 when referring back to any one of claims 9 to 21, wherein at least one of the ICEs (21, 22, 23) is arranged substantially on the first surface of the waveguide (30); and / or the at least one OCE (41, 42, 43) is arranged substantially on the second surface of the waveguide (30).

24. A system comprising: the imaging system (10) of any one of claims 1 to 23, and a sensor; wherein the imaging system (10) comprises at least one diffractive out-coupling element OCE (41, 42, 43) configured to at least partially out-couple the deflected light to the sensor.

25. The system of claim 24, further comprising a lens, wherein the lens is configured to at least partially in-couple light out-coupled by the at least one OCE (41, 42, 43) into the sensor (50).

26. The system of claim 25, wherein, The OCE (41, 42, 43) defines an OCE aperture; and wherein the lens has a lens aperture, an area of the lens aperture substantially corresponding to an area of the OCE aperture.

27. A method for producing an imaging system (10), the method comprising the steps of: providing a waveguide (30); and generating at least two diffractive in-coupling elements ICEs (21, 22, 23) on the waveguide (30), preferably by means of a holographic exposure, the ICEs being configured to at least partially deflect light incident on the ICEs (21, 22, 23) within the waveguide (30); wherein the generating is implemented such that the at least two ICEs (21, 22, 23) are tilted with respect to each other by a tilt angle not equal to 0°.

28. The method of claim 27, further comprising: generating at least one diffractive out-coupling element OCE (41, 42, 43) on the waveguide (30), preferably by means of a holographic exposure; wherein the at least one OCE (41, 42, 43) is configured to out-couple light deflected by the at least two ICEs (21, 22, 23) at least partially out of the waveguide (30).

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