FUNCTIONALIZED WAVE CONDUCTOR FOR A DETECTOR SYSTEM

Description

[0001] The present invention relates to a functionalized waveguide for a detector system having the features of the preamble of claim 1.

[0002] Transparent surfaces made of glass or plastic, such as windows or windshields in cars, have a transparent base and generally serve only to protect people or objects from environmental influences such as wind, temperature, particles or radiation.

[0003] There is a growing interest in providing such a transparent base body that offers additional optical functionality.

[0004] A functionalized waveguide of the type mentioned above is known from US 5,991,480 A. US 2006 / 132914 A1 describes functionalized waveguides with sawtooth relief grids.

[0005] It is therefore an object of the invention to provide a functionalized waveguide of the type mentioned above with an additional optical functionality.

[0006] The invention is defined in independent claim 1. Advantageous embodiments are specified in the dependent claims.

[0007] In the functionalized waveguide according to the invention, a partially transparent input region and an output region spaced apart from it in a first direction are provided or formed in the transparent base body. The partially transparent input region comprises a diffractive structure in the form of an input relief grating, with which the transparency of the input region is maintained under normal viewing conditions over a wide angular and wavelength range. Thus, only a portion of the radiation incident on a front face of the transparent base body can be deflected by means of the transparent input region, such that the deflected portion propagates as coupled radiation into the base body by reflection until it reaches the output region.

[0008] The transparency of the coupling region depends on the efficiency of the radiation coupling. As the coupling efficiency increases, the transparency in the coupling region of the functionalized waveguide decreases.

[0009] The semi-transparent coupling region can be configured such that the coupling efficiency is, for example, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In particular, the coupling efficiency can be in the range of 2% to 50%, so that the transparency of the coupling region is in the range of 50% to 98%. The coupling region(s) of the further embodiments can also exhibit such coupling efficiencies or such transmissive properties.

[0010] The transparent coupling area is preferably designed such that the deflection of the deflected part of the radiation striking the front of the transparent base body occurs as a pure deflection, which is free of an imaging optical function (e.g. free of a focusing effect).

[0011] The reflections can be, in particular, total internal reflections at the front and / or back of the transparent base body. However, it is also possible that reflective layers or coatings, or partially reflective layers or coatings, are used for this purpose.

[0012] The front and back sides of the semi-transparent body can be designed as flat surfaces. For example, the semi-transparent base body can be designed as a plane-parallel plate.

[0013] However, it is also possible that the front and / or back are curved.

[0014] The semi-transparent base body can be made of glass and / or plastic. It can be a single piece or have a multi-layered structure.

[0015] In particular, the transparent base body can be transparent to radiation or light from the visible wavelength range. Furthermore, it can exhibit transparency to the near-infrared and / or infrared range.

[0016] The output coupling area of ​​the transparent base body can deflect at least a portion of the incident radiation such that the deflected portion exits the base body. This preferably occurs via the front or back of the transparent base body.

[0017] The extraction area can be semi-transparent. In particular, the extraction efficiency of the extraction area can be, for example, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. Specifically, the extraction efficiency of the extraction area can be in the range of 2% to 50%, so that the transparency of the extraction area is in the range of 50% to 98%. The extraction area(s) of the further embodiments can also exhibit such extraction efficiencies or such transmissive properties.

[0018] However, it is also possible that the output coupling area has maximum output coupling efficiency. This can be achieved, for example, by mirroring (preferably complete mirroring).

[0019] The coupling and decoupling regions can be designed such that, apart from deflection, they do not provide any optical imaging function. However, it is also possible for the coupling and / or decoupling regions to provide an optical imaging function in addition to deflection, thus producing an optical image. For example, the optical imaging function can function as a converging or diverging lens, or as a concave or convex mirror, where the curved surfaces (centered or decentered) can be spherically curved or aspherically curved.

[0020] The diffractive structure of the coupling region can be realized as a buried diffractive structure, as a diffractive structure between two substrates, or as a diffractive structure formed on the front or back side.

[0021] Furthermore, the output coupling area can have a diffractive structure. The diffractive structure of the output coupling area can be configured as a buried diffractive structure or as a diffractive structure on the front or back side.

[0022] A relief grid is provided as the diffractive structure of the input and output coupling regions. The relief grid can be a transmissive or reflective relief grid.

[0023] In embodiments not part of the claimed invention, the output coupling area may further comprise a mirror surface, a prism, and / or a reflective or transmissive Fresnel structure. These variants may be provided as an alternative to, or in addition to, the diffractive structure of the output coupling area. Furthermore, a detector system with a functionalized waveguide according to the invention (including all further developments) is provided. The detector system, hereinafter also referred to as the detection system, may comprise a detector onto which the portion of the radiation deflected by the output coupling area strikes. The detector may be connected to the front or rear of the base body. In particular, a direct connection may be provided. The detector may be a digital image sensor (e.g., a CCD sensor or a CMOS sensor), a detector array, or, e.g., a solar cell.

[0024] Furthermore, the detector system can be designed such that at least one optical imaging element is arranged in the area between the detector and the front or back surface. This at least one optical imaging element can be, for example, a lens, a refractive lens, or a refractive camera lens. It is also possible for the area between the detector and the front or back surface to be free of imaging optical elements. In other words, the radiation coupled out from the output coupling area reaches the detector without having passed through any further optical imaging elements. In this case, it is advantageous if the output coupling area, in addition to its deflection function, also possesses an optical imaging property.

[0025] The functionalized waveguide can be configured to perform an infinity-to-infinity mapping. However, it is also possible for it to perform a finite-to-infinity mapping, an infinite-to-finite mapping, or a finite-to-finite mapping.

[0026] The detector system can, of course, also be designed such that at least one optical imaging element is arranged between the detector and the front or back surface. This at least one optical imaging element serves, in particular, to guide the portion of the radiation deflected by the output coupling area and can, for example, be designed as a lens. The at least one optical imaging element can, for example, be designed as an objective lens, a refractive objective lens, or a refractive camera lens.

[0027] In a functionalized waveguide, the extent of the coupling region in a second direction perpendicular to the first direction can be larger than the extent of the output coupling region in the same direction. The extent (or, for example, width) of the coupling region here refers specifically to the effectively utilized extent or the optically utilized extent. This is, for example, the extent of the portion of the coupling region from which the deflected radiation reaches the detector system. Similarly, the extent (or, for example, width) of the output coupling region refers specifically to the effectively utilized extent or the optically utilized extent. This is, for example, the extent of the portion of the output coupling region from which the deflected radiation reaches the detector system.

[0028] Furthermore, the coupling area and the coupling area can be arranged centered relative to each other in the second direction.

[0029] However, it is also possible that the coupling area and the coupling area are arranged decentered to each other in the second direction.

[0030] Several decoupling areas can be provided, arranged side by side in the second direction. At least one of the decoupling areas can additionally have the function of deflection perpendicular to the first direction.

[0031] The field of view (hereinafter referred to as "FoV") of the functionalized waveguide can be matched to the FoV of the detector (or the detector with the at least one optical imaging element, e.g., a lens). This can be achieved, in particular, by adjusting the spacing between the input and output coupling areas along the first direction and the extent of the input and output coupling areas perpendicular to the first direction. Matching the FoV of the detector (or the detector with the at least one optical imaging element) to the FoV of the functionalized waveguide can be accomplished by adjusting the lens focal length and / or the size of the detector. Preferably, the FoV of the functionalized waveguide corresponds to the FoV of the detector (or the detector with the at least one optical imaging element).This can be achieved by selectively adjusting the FoV of the functionalized waveguide and / or selectively adjusting the FoV of the detector (or the detector with at least one optically imaging element).

[0032] Furthermore, a functionalized waveguide for an illumination and / or projection system is provided, wherein the waveguide has a transparent base body with a front and a back. The transparent base body can, in principle, be designed and further developed in the same way as the transparent base body for the functionalized waveguide for the detector system.

[0033] The base body can thus have an input coupling area and an output coupling area spaced apart from it in a first direction. The input coupling area deflects at least a portion of the radiation coming from the light or image source of the illumination and / or projection system and striking the input coupling area in such a way that the deflected portion propagates as coupled radiation within the base body by reflection to the output coupling area and strikes it. The output coupling area can comprise a structure, e.g., a diffractive structure, that deflects the coupled radiation striking it so that the deflected portion exits the base body via the front and back surfaces. The diffractive structure can be adapted to the wavelengths of the radiation coming from the light or image source in such a way that as much radiation as possible is reflected. Nevertheless, the diffractive structure can still exhibit the desired transparency, e.g., when looking through it.Furthermore, it is possible that the diffractive structure only deflects a portion of the radiation from the light or image source.

[0034] In embodiments that are not part of the claimed invention, the Bie structure of the coupling area can be a transmissive or reflective diffractive structure, a transmissive or reflective volume hologram, a mirror surface, a prism or, according to the invention, a transmissive or reflective relief grid.

[0035] This provides a transparent output region. The extent of the output region in a second direction perpendicular to the first direction can be larger than the extent of the input region in the second direction.

[0036] Furthermore, an illumination and / or projection system with a functionalized waveguide for such an illumination and / or projection system is provided, wherein a light and / or image source is additionally provided, the light of which strikes the coupling area. In the functionalized waveguide for a detector system, the coupling area can comprise at least two volume holograms, each of which deflects only a portion of the radiation emanating from an object to be detected and striking the front face, such that the deflected portion propagates as coupled radiation within the base body by reflection to the output coupling area and strikes the output coupling area. The embodiment described here, in which the coupling area and / or output coupling area comprises one or more volume holograms, is not part of the claimed invention.The volume holograms of the coupling region can differ in that their deflection function exhibits different spectral angular properties. This allows different wavelengths to be deflected at the same angle of incidence. The outcoupling region deflects at least a portion of the coupled radiation entering it, causing the deflected portion to exit the base body (preferably via the front or back) to reach the detector system.

[0037] With such a waveguide, more colors can be transmitted because the volume holograms of the coupling area have different spectral angular properties and thus, at the same angles of incidence, deflect different wavelengths so that they are part of the coupled radiation in the base body.

[0038] The volume holograms of the coupling area can be arranged adjacent to each other (with or without a gap between them), and in particular, they can be arranged adjacent to each other in the first direction. However, it is also possible for the volume holograms of the coupling area to be arranged one above the other (i.e., preferably in a stacking direction that is perpendicular to the first direction and perpendicular to the second direction), so that a layered stack of volume holograms is present. Alternatively or additionally, the functions of some or all of the volume holograms of the coupling area can be implemented in a single volume hologram. Such an implementation is also called multiplexing. These possible configurations of the coupling area can be provided in all described embodiments.

[0039] The outfeed section can have an associated volume hologram for each volume hologram of the input section, which provides the same spectral angular property during deflection as the corresponding volume hologram of the input section. This allows the dispersion of the volume holograms of the input section to be compensated.

[0040] The volume holograms of the output area can be arranged adjacent to each other (with or without a gap between them), in particular they can be arranged adjacent to each other in the first direction. However, it is also possible for the volume holograms of the output area to be arranged on top of each other (i.e., preferably in a stacking direction that is perpendicular to the first direction and perpendicular to the second direction), so that a layered stack of volume holograms is present. Alternatively or additionally, the functions of some or all of the volume holograms of the output area can be implemented in a single volume hologram. Such an implementation is also called multiplexing. These possible configurations of the output area can be provided in all described embodiments.

[0041] The volume holograms of the coupling area can be designed as reflective or transmissive volume holograms. The same applies to the volume holograms of the coupling area.

[0042] The coupling area can have at least or exactly 2, 3, 4, 5, 6, 7, 8, 9, 10, up to 40, up to 50 or up to 100 (or any value between 1 and 100) volume holograms.

[0043] In the functionalized waveguide for a detector system, the coupling area can have several diffractive coupling structures that are adjacent in the first direction and differ in that they have different horizontal fields of view in a plane spanned by a perpendicular to the front and a second direction perpendicular to the first direction, so that they deflect radiation from the different horizontal fields of view towards the outcoupling area.

[0044] This allows a larger horizontal field of view to be captured and directed to a detector.

[0045] The diffractive coupling structures can be designed to deflect the radiation from the different horizontal fields of view towards the output coupling area.

[0046] This allows a larger horizontal field of view to be captured and directed to a detector.

[0047] The diffractive coupling structures can be designed in such a way that they encode the radiation from the different horizontal fields of view by different deflected wavelengths during deflection, so that the outcoupling and / or detection is possible selectively for the different horizontal fields of view.

[0048] The output coupling area can have an associated diffractive output coupling structure for the diffractive input coupling structure, which selectively deflects radiation with wavelengths of the associated diffractive input coupling structure.

[0049] The diffractive outcoupling structures can deflect the radiation from the associated input coupling structures so that it hits spatially different areas of a detector system.

[0050] A color filter can be provided for at least one locally different area of ​​the detector, which directs only the corresponding wavelength range to the detector.

[0051] The diffractive coupling structures can be designed to encode the radiation from the different deflection angle ranges, so that the coupling out and / or detection is selectively possible for the different horizontal fields of view.

[0052] The coupling area can have a shading baffle with a lamellar structure in front of each diffractive coupling structure, which defines a different vertical field of view for each diffractive coupling structure in a plane spanned by a perpendicular to the front and the first direction.

[0053] The output coupling area can have an associated diffractive output coupling structure for each diffractive input coupling structure, selectively deflecting radiation from the different deflection angle ranges of the associated diffractive input coupling structures. The diffractive output coupling structures can be arranged adjacent to the first direction.

[0054] The diffractive output structures can each be designed as a reflective or transmissive volume hologram.

[0055] The functionalized waveguide for a detector system can be designed or further developed such that the coupling area along the second direction has at least two different diffractive coupling structures that differ in that they have a different deflection component in the second direction.

[0056] This results in higher efficiency with regard to the utilization of the coupled radiation. The deflection component in the second direction can be selected for each of the diffractive coupling structures that are offset along the second direction relative to the output coupling region such that the existing offset for the coupled radiation is compensated.

[0057] The output coupling area can be designed in such a way that it deflects the radiation coupled in by the different diffractive input coupling structures into the same angular range.

[0058] The functionalized waveguide for a detector system can be designed or further developed such that the coupling area includes a coupling relief grid and the coupling area includes a coupling relief grid.

[0059] According to the invention, the coupling relief grid and the coupling relief grid have the same grid period.

[0060] The functionalized waveguide can also be designed as a screen with a transparent base body. In this case, the transparent base body can be part of a screen.

[0061] The screen can be, for example, the screen of a portable device (such as a smartphone or a laptop), a stationary screen, or any other screen, such as one installed in a motor vehicle.

[0062] The outcoupling area can be located closer to the edge of the base body along the first direction than the incoupling area.

[0063] Furthermore, the coupling area can be located on the rear side.

[0064] Furthermore, the screen can have a light-emitting layer arranged on the back of the base body, and the coupling area can be located between the base body and the light-emitting layer.

[0065] The image sensor can be located on the back of the base body in an area that serves as the display area of ​​the screen and is switched off during recording using the image sensor.

[0066] The screen may have an additional camera that records the object, the camera's recording being used to colorize a recording of the object using the image sensor.

[0067] The screen can have a light-emitting layer located on the back of the base body, which generates a real image. This light-emitting layer can, for example, have light-emitting pixels. In this case, the real image is generated in the plane of the pixels. The pixels can each have a beam angle of at least 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170° down to less than 180°.

[0068] Since this pixelated light-emitting layer is located on the back of the base body, the light emitted by the pixels is transmitted through the base body and reaches a viewer.

[0069] To prevent light emitted by the light-emitting layer from being diffracted by the diffractive structure of the coupling area and thus not reaching the viewer, the diffractive structure of the coupling area can be designed so that only light with a specific polarization is diffracted and thus guided within the base body (or waveguide). The light emitted by the light-emitting layer can then have a polarization that is inefficient for the diffractive structure of the coupling area and transmit undisturbed through it. This eliminates the need for the light-emitting layer to be a source of stray light, and it is no longer necessary to darken or mask out the pixelated light-emitting layer in the coupling area to prevent stray light coupling during image capture by the image sensor.

[0070] Possibilities for a defined polarization would include LCD displays or the application of a polarizing film between the light-emitting layer and the base body.

[0071] The functionalized waveguide (or the described detector system) can be designed or further developed to be provided as a functionalized disk (or detector system) for a vehicle. The vehicle can be a motor vehicle, truck, aircraft, motorized or non-motorized vehicle, or any other type of vehicle. The disk can be any part of the vehicle, such as the windshield, a side window, or a rear window. In particular, multiple disks (or detector systems) can be provided for a vehicle. These can be used, for example, to detect the position of a person or object inside the vehicle. Furthermore, a vehicle is provided with one or more such functionalized disks (or with one or more detector systems).

[0072] The outcoupling area can be located closer to the edge of the base body along the first direction than the incoupling area.

[0073] The functionalized disk can be used in a detector system, which can be designed and further developed in the manner described. In particular, a detector can be provided onto which the portion of the radiation deflected by the output coupling area strikes. Between the output coupling area and the detector, the detection system can have at least one optical imaging element. This at least one optical imaging element can be, for example, a lens, a refractive lens, or a refractive camera lens.

[0074] The base body can have a further input coupling region and a further output coupling region spaced apart from it in the first direction. The further input coupling region deflects at least a portion of the radiation coming from a light or image source and striking the further input coupling region such that the deflected portion propagates as coupled-in radiation within the base body by reflections to the further output coupling region and strikes it. The further output coupling region can comprise a structure, e.g., a diffractive structure, that deflects the coupled-in radiation striking it such that the deflected portion exits the base body through the front or back to produce the desired illumination and / or projection. The diffractive structure can be adapted to the wavelengths of the radiation coming from the light or image source in such a way that as much radiation as possible is reflected.Nevertheless, the diffractive structure can still exhibit the desired transparency, for example, when looking through it. Furthermore, it is possible that the diffractive structure only deflects a portion of the radiation from the light or image source.

[0075] The structure of the further output coupling area can be a transmissive or reflective diffractive structure, a transmissive or reflective volume hologram, a mirror surface, a prism, or a transmissive or reflective relief grid.

[0076] This provides a disc that has two additional optical functionalities.

[0077] The coupled radiation and the coupled additional radiation can, for example, propagate in opposite directions, at least section by section, within the same region of the base body. Thus, the same transmission channel is used in different directions.

[0078] Of course, the coupled radiation and the coupled-in further radiation can also propagate completely in different areas within the base body.

[0079] The coupling area and the subsequent coupling area can be formed, at least partially, in the same area of ​​the base body. For example, they can be integrated together, stacked on top of each other, and / or partially overlap.

[0080] Furthermore, it is possible that the coupling area and the further coupling area are formed in different areas in the base body.

[0081] Furthermore, the functionalized waveguide can be designed or further developed as a functionalized disk for illumination and / or projection, wherein the base body has an input region and an output region spaced apart from it in a first direction. The input region deflects at least a portion of the radiation coming from a light or image source and striking the input region such that the deflected portion propagates as coupled radiation within the base body by reflection to the output region and strikes the output region. The output region can comprise a structure, e.g., a diffractive structure, that deflects the coupled radiation striking it such that the deflected portion exits the base body (preferably via the front or back) to effect the desired illumination and / or projection. The diffractive structure of the output region is preferably semi-transparent.The diffractive structure can be adapted to the wavelengths of the radiation coming from the light or image source in such a way that as much radiation as possible is reflected. Nevertheless, the diffractive structure can still exhibit the desired transparency, for example, when looking through it. Furthermore, it is possible for the diffractive structure to deflect only a portion of the radiation from the light or image source.

[0082] The structure of the output coupling area can be a transmissive or reflective diffractive structure, a transmissive or reflective volume hologram, a mirror surface, a prism, or a transmissive or reflective relief grid.

[0083] Furthermore, the first coupling area for detection can have a larger horizontal extent than the first coupling area for detection, and the second coupling area for projection and / or illumination can have a larger horizontal extent as well as a larger vertical extent than the second coupling area for projection and / or illumination.

[0084] Thus, in the upper, visible area of ​​the transparent base body, there can be a holographic strip for detection (no pupil replication required) as well as a holographic surface for projection and / or illumination, with the holographic surface typically having a larger extent in the horizontal and vertical directions for positioning the eyes than the second coupling area in the non-visible area of ​​the transparent base body.

[0085] The first coupling area and the second coupling area can be located in a visible area of ​​the transparent base body (especially if the functionalized waveguide is part of a detector system as well as an illumination and / or projection system).

[0086] Furthermore, a lighting and / or projection system with a functionalized lens for lighting and / or projection is provided. The lighting and / or projection system may also include a light or image source.

[0087] The functionalized waveguide can be designed or further developed so that it is suitable not only for a detector system but also for an illumination and / or projection system. For this purpose, the base body can have a second output coupling area that deflects at least a portion of the light from a light or image source, which strikes the second output coupling area as illumination radiation, in such a way that the deflected portion serves for illumination and / or projection.

[0088] The second coupling area can be developed and further formed in the same way as the coupling area or the first coupling area described so far.

[0089] The waveguide can be designed such that the base body has a second coupling area that deflects the light from the light or image source in such a way that reflected light in the base body is propagated by reflections to the second coupling area and hits it.

[0090] Alternatively or additionally, the light from the light or image source can hit the base body as a free jet and thus the second output coupling area, so that it is not guided by reflection in the base body.

[0091] Furthermore, a detection system and an illumination and / or projection system with a functionalized waveguide for a detector system and an illumination and / or projection system are provided. The system can include the light or image source.

[0092] The described different configurations of the functionalized waveguide, the functionalized screen, and the functionalized disk can be combined with one another where technically feasible. It is also possible to exchange individual feature groups among them.

[0093] The detection system according to the invention can be designed as a camera (e.g. digital camera or video camera).

[0094] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations given, but also in other combinations or on their own, without leaving the scope of the present invention.

[0095] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying drawings, which also disclose essential features of the invention. These exemplary embodiments serve only for illustration and are not to be interpreted as limiting. For example, a description of an exemplary embodiment with a plurality of elements or components is not to be interpreted as meaning that all of these elements or components are necessary for implementation. Rather, other exemplary embodiments may also contain alternative elements and components, fewer elements or components, or additional elements or components. Elements or components from different exemplary embodiments may be combined with one another unless otherwise specified. Modifications and variations described for one of the exemplary embodiments may also be applicable to other exemplary embodiments.To avoid repetition, identical or corresponding elements in different figures are designated with the same reference symbols and are not explained multiple times. The figures show: . Fig. 1 a side view of an embodiment of a detector system; Fig. 2 a top view of waveguide 1 of Fig. 1 Fig. 3 a top view of the waveguide 1; Fig. 4 a schematic representation of the spectrally resolved, angle-dependent deflection efficiency of the reflective volume hologram of the coupling area 4; Fig. 5 a schematic representation of the deflection efficiency for three different angles of incidence as a function of wavelength; Fig. 6 an enlarged section view of a side view to illustrate the averaging over a defined angular range caused by the detector pixels; Figs. 7A-7C top views of the waveguide to illustrate different width ratios between the coupling and coupling areas; Fig. 7 a top view to illustrate the possible restriction of the horizontal field of view in a detector system 2 with lens 1; Figs. 8A and 8B further embodiments of the waveguide 1.8C An enlarged side view of the coupling area of ​​waveguide 1 to illustrate a possible reduction of the vertical field of view; Figs. 9A and 9B Illustration to illustrate the production of a volume hologram for the coupling area; Fig. 10 A top view of the waveguide according to a further embodiment; Figs. 11A-F Side views of the coupling area of ​​the waveguide of . Fig. 10 ; Fig. 12 a schematic representation of the spectrally resolved, angle-dependent deflection efficiency of the coupling area according to Fig. 10 Figures 13A-13C schematically show the deflection efficiency of different angles of incidence as a function of wavelength; Figures 14A-F show schematic side views to illustrate the output coupling area of ​​the waveguide according to Fig. 10 Fig. 15: Schematic representation of the spectrally resolved, angle-dependent deflection efficiency for the coupling region of a waveguide with 40 different volume holograms; Fig. 16: Top view of a waveguide according to a further embodiment; Fig. 17: Top view of the waveguide of Fig. 16 ; Fig. 18A, 18B Side views of the coupling area to illustrate the operation of the waveguide according to Figuren 16 und 17 Figures 19A-19C schematically show the angle of incidence and spectral efficiency of the laterally offset coupling volume holograms of the waveguide according to Fig. 16 Fig. 20 schematically shows the spectral angle-dependent spectrum of the output coupling holograms of the embodiment according to Fig. 16 including spectral filtering; Figs. 21 and 22: Top views of two different waveguides 1 to illustrate a further embodiment; Fig. 23: Side view of a further embodiment of the waveguide according to the invention; Fig. 24: Schematic representation of the geometric transmission spectrum of the waveguide according to Fig. 23 ; Fig. 25 an enlarged side view of the coupling area of ​​the waveguide of Fig. 23 Fig. 26 shows a schematic representation of the geometric transmission spectrum when vignetting is caused by the entrance pupil of the detector system; Fig. 27 schematically shows a simulated cross-section through one grid period of the buried input grid of the waveguide according to Fig. 23 Fig. 28 schematically shows the diffraction efficiency of the relief grating as a function of wavelength; Fig. 29 shows a top view of another embodiment; Fig. 30 shows a side view of the embodiment of Fig. 29 Fig. 31 shows another embodiment; Fig. 32 shows the side view of Fig. 31 Fig. 33 shows a schematic representation of an optical system; Fig. 34 shows the optical system according to Fig. 33 Fig. 35 shows a further embodiment of the waveguide, which can be used in particular for projection and / or illumination; Fig. 36 shows the side view of the waveguide. Fig. 35 Fig. 37 shows the top view of the waveguide of Fig. 35 Figures 38-40 schematically show illumination or projection with a waveguide; Figures 41A-41C show illumination or projection with a free beam path from the light / illumination source to the coupling area, where the coupling area is used reflectively; Figures 42A-42C show the corresponding arrangement according to Fig.41A-41C , when the output coupling area is used transmissively; Figs. 43A-43C show one variant of combining detection with projection or illumination; Figs. 44A-44C show another variant of combining detection with projection or illumination; Figs. 44D-44F show another variant of combining detection with illumination or projection; Fig. 45 shows an embodiment in which the waveguide is used in a microscope; Figs. 46-46D show embodiments of integrating the waveguide or forming the waveguide in a windshield of a vehicle, and Figs. 47A-47C show variants of integrating the waveguide in a side window of a car.

[0096] The embodiments of Figuren 1-22 and 29-47C are based on volume holograms and are therefore not part of the claimed invention.

[0097] The views according to Fig. 1 bis 3 show an embodiment of the waveguide 1 together with a detector system 2 to realize a camera 3.

[0098] The waveguide 1 comprises an input coupling area 4 and a spaced-apart output coupling area 5 and can, as in Fig. 1 bis 3 The figure is shown to be formed on a plane-parallel plate 6 with a flat front surface 7 and a flat back surface 8. The plane-parallel plate 6, which can also be referred to as the base body 6, is made of a transparent material, such as glass or plastic.

[0099] The detector system 2 and the lower part of the plate 6 with the output coupling area 5 can only be in one in Fig. 1 The housing G shown schematically is arranged so that it is not immediately apparent to a user that it is a camera 3.

[0100] With the camera 3, an object 9 can be imaged in such a way that light beams L1, L2, L3 emanating from the object 9 enter the plate 6 via the front surface 7 and are deflected by the coupling area 4 so that they strike the front surface 7 at an angle that causes total internal reflection. Thus, the light beams L1, L2, and L3 are guided by total internal reflection at the front surface 7 and back surface 8 to the coupling area 5, which deflects them towards the front surface 7, causing the light beams L1-L3 to exit the plate via the front surface 7. The light beams L1-L3 then propagate in the waveguide 1 along a first direction R1 (here the y-direction) from the coupling area 4 to the coupling area 5.

[0101] By means of a lens 10 of the detector system 2, the light beams L1 - L3 are then focused onto a detector 11 of the detector system 2, so that the desired image of the object 9 can be taken by means of the detector 11.

[0102] The coupling area 4 is designed as a reflective volume hologram that exhibits an angle-of-incidence wavelength selectivity, so that it has high transparency for a large angular and wavelength range (as shown by the transmitted light beam L1' in Fig. 1 (This is indicated; other transmitted light beams are not shown for the sake of simplicity). This means that only a portion of the light beams L1–L3 emanating from object 9 and striking the coupling area 4 are deflected in the manner described. Other light beams from object 9 propagate through the coupling area 4 and exit the plate 6 via the rear surface 8. Thus, the coupling area 4 can be described as semi-transparent.

[0103] In Fig. 4 The spectrally resolved, angle-dependent deflection efficiency for the reflective volume hologram of the coupling area 4 is schematically represented as a function of the incidence angle of the corresponding light beam, where the wavelength in µm is plotted along the x-axis and the incidence angle in ° along the y-axis. Fig. 5 The deflection efficiency for the angles of incidence +20°, 0° and -20° is shown, with the wavelength in nm plotted along the x-axis and the efficiency along the y-axis.

[0104] Out of Fig. 4 und 5 It can be deduced that the reflective volume hologram of the coupling area 4 deflects radiation from the spectral range of 392 nm to 398 nm (λcentral = 395 nm ± 3 nm) with high efficiency for an incidence angle of -20° and thus couples it into the plane-parallel plate 6. For an incidence angle of 0°, the high efficiency is present for the spectral range of 528 nm to 536 nm (λcentral = 532 nm ± 4 nm), and for an incidence angle of +20°, a high coupling efficiency is present for the spectral range of 600 nm to 610 nm (λcentral = 605 nm ± 5 nm).

[0105] Since the waveguide 1 according to Fig. 1 bis 3 Since the waveguide 1 is configured such that neither the input coupling area 4 nor the output coupling area 5 has an imaging function, it exhibits an infinity-to-infinity configuration. One can also say that the waveguide 1 performs an infinity-to-infinity mapping. Thus, the spectral and angle-dependent deflection efficiency of the reflective volume hologram of the input coupling area 4 results in each field angle (and therefore each point of the imaged object 9) being represented after coupling via the input coupling area 4 only from a small spectral range, as described with reference to Fig. 4 und 5 As explained above, this results in a spectrally resolved angular distribution, which ultimately leads to an image with a spectral profile (or color gradient) on detector 11. The light beams L1–L3, coupled out via the output coupling area 5, are thus coupled out with an angular spectrum, which is converted into a spatial distribution on detector 11 by means of the lens 10. Detector 11 can be, for example, a CCD detector or a CMOS detector.

[0106] Since the coupling area 4 has the reflective volume hologram, coupling via the reflective volume hologram leads to dispersion within the coupled spectral range for every angle. If the output coupling area 5 has a reflective volume hologram of the same design as the coupling area 4, the dispersion caused by the coupling area 4 is compensated, and all spectral components are deflected again to the corresponding angle.

[0107] As an alternative to the described infinity-to-infinity configuration of waveguide 1, the coupling area 4 and / or the coupling area 5 can, for example, have an imaging function in the form of a lens or concave mirror function. This allows finite-to-infinity, infinity-to-finite, or finite-to-finite imaging configurations to be realized using waveguide 1. In the coupling area 4, this can be used, for example, to capture an object 9 that is positioned so close to waveguide 1 that it can no longer be optically perceived as being at infinity. In the coupling area 5, implementing such a lens or concave mirror function allows the coupled-out angular spectrum to be directly converted into a spatial distribution in the focal plane of this implemented lens or mirror function. In this case, the lens 9 can, for example, be omitted.In this case, it can be said that the detector system 2 comprises the detector 11 as well as the lens and / or concave mirror function of the output coupling area 5. Since the lens 10 can be omitted, the detector 11 can, for example, be positioned and / or attached directly to the front face 7 of the waveguide 1, thereby achieving a very high degree of integration, minimal volume, and high robustness.

[0108] As already explained, the angular distribution, spectrally resolved after extraction via the extraction area 5, is converted into a spatial distribution on the detector 11 using the objective 10 or an imaging function integrated into the extraction area 5. Such a detector 11 has a discretization in the form of pixels. According to the representation in Fig. 6 , in which the unfolded waveguide system is shown on the detector side, each pixel PX averages over a defined angular range, which is given by the pixel size PG, its distance from the optical axis AP and the focal length F AK of the lens 10 or the imaging function of the output coupling area 5.

[0109] According to the representations in Fig. 4 und 5 The acquisition of an angular range is also linked to integration over a spectral range. The spectral bandwidth is defined by the maximum (α 2 , ) of a pixel. Fig. 4 ) and the minimum recorded angle (α 1 , Fig. 4 ) given, which can be calculated as follows: α 1 , n = atan PG ⋅ 0 , 5 + n − 1 ⋅ PG f α 2 , n = atan PG ⋅ 0 , 5 + n ⋅ PG f , where n is the number of the respective pixel (0 → on the optical axis, n < 0 → below the optical axis, n > 0 → above the optical axis), PG is the pixel size and f is the focal length of the optical system.

[0110] Using these limiting angles, the bandwidth over which each pixel is integrated can then be calculated, for example, based on Kogelnik's coupled-wave theory. Thus, the total spectrum detected by a pixel is composed of the spectra within the detected angular range, which is why it contributes to the spectrum described in the following diagrams: Fig. 5 The broadening shown in the depicted spectra occurs. In the limiting case where detector 11 consists of only one pixel onto which all angular ranges are transferred, image information with all spectral components would be recorded.

[0111] While the position of the pupil (ray beam limiting aperture or point where the principal rays of all field angles intersect) in the infinity-infinity configuration of the waveguide 1 depends on the ratio of the width B1 (extent perpendicular to the first direction R1 along a second direction R2, which here corresponds to the x-direction) of the coupling area 4 ( Fig. 2 ) the width B2 of the coupling area 5 is determined, the field of view of the waveguide 1 in the direction of R2 is additionally dependent on the distance D of the coupling area 4 from the coupling area 5 along the propagation direction R1 or the first direction R1 in the waveguide 1.

[0112] Naturally, the dimensions of the coupling area 4 and the coupling area 5 can be limited by apertures. Here, we always refer to the optically utilized dimension or width. These are subsequently also referred to as effective widths.

[0113] In the Fig. 7A, 7B und 7C Three fundamentally different width ratios of the coupling-in to coupling-out regions 4 and 5 are shown. Only non-vignetted field angles are considered in the pupil position analysis.

[0114] Out of Fig. 7A It follows that for the ratio B1 / B2 > 1, the output coupling area 5 of the waveguide 1 acts as the pupil. Thus, all angles are present at every point in the output coupling area 5.

[0115] In the special case B1 / B2 = 1 ( Fig. 7B ) only the central field angle propagates unvignetted through the waveguide 1. In this case, both the coupling area 4 and the coupling area 5 form the pupil.

[0116] When the ratio of B1 / B2 is < 1 ( Fig. 7C ) the coupling area 4 is the pupil of the waveguide 1, so that at each point of the coupling area 5 different angular ranges are present and coupled out.

[0117] Furthermore, a fundamental distinction can be made between the field of view (hereinafter also referred to as FoV) of waveguide 1 and the field of view (hereinafter also referred to as FoV) of detector system 2. The smaller of the two fields of view (or of the two FoV) determines the field of view of the entire system.

[0118] The horizontal field of view (in the x-direction) received and re-coupled by waveguide 1 in the infinity-to-infinity configuration of waveguide 1 is determined by the widths B1 and B2 of the input coupling area 4 and the output coupling area 5, as well as their distance D from each other (regardless of whether the pupil lies on the input coupling area 4 and / or the output coupling area 5). The field of view of the detector system 2 is, to a first approximation, given by the focal length of the objective lens 10 (or the lens function contained in the output coupling area 5) and by the size of the detector 11 in the direction of the horizontal field of view.

[0119] Ideally, the field of view (FoV) of waveguide 1 and detector system 2 is identical. This results in optimal resolution across the entire FoV of waveguide 1. As long as the FoV of detector system 2 is larger than the FoV of waveguide 1, the horizontal FoV of the overall system is determined by the width of the input coupling area 4, the width of the output coupling area 5, and the distance D between the input coupling area 4 and the output coupling area 5. Advantageously, the entire FoV is thus captured. However, this results in a reduced resolution. If the horizontal FoV of detector system 2 is smaller than the FoV of waveguide 1, the FoV of the overall system is limited by the FoV of the detector system. This offers the advantage of increased resolution, although only a portion of the FoV of waveguide 1 is captured.When using lens 10, the distance of the detector system 2 from the waveguide 1 may restrict the FoV, as outer angular areas can no longer be captured by lens 10, as shown in . Fig. 7D as indicated.

[0120] The desired field of view (FoV) of waveguide 1 can be matched to the FoV of detector system 2 by adjusting B1, B2, and D. Alternatively, the FoV of detector system 2 can be matched to the FoV of waveguide 1 by adjusting the objective focal length and / or the detector size.

[0121] As previously explained, the pupil position of the waveguide 1 is determined by the ratio of the width B1 of the coupling area 4 to the width B2 of the coupling area 5. Consequently, the shape of the angular distribution at the coupling area 5 changes. This results in advantageous properties for certain arrangements and applications.

[0122] If B1 / B2 > 1, the output coupling area 5 forms the pupil of the waveguide 1. Considering all non-vignetted beams, all field angles are present at every point in the output coupling area 5. Consequently, all field angles, i.e., the complete field of view (FoV) of the waveguide 1, can be acquired with only one detector system 2 with a sufficiently large FoV and a sufficiently large entrance pupil. To achieve a large FoV of the waveguide 1, it is therefore advantageous to make the input coupling area 4 wider than the output coupling area 5. A small distance between the input coupling area 4 and the output coupling area 5 is also advantageous.

[0123] In the representation according to Fig. 7A It was assumed that a horizontally symmetrical arrangement of the input coupling area 4 and the output coupling area 5 exists, resulting in a symmetrical field of view (FoV) of the waveguide 1. However, it is possible to offset the output coupling area 5 laterally (in the x-direction), as shown in Fig. 8A This is indicated. This also results in an offset of the horizontal FoV. Without a corresponding correction of the output coupling area 5, this angular distribution with the corresponding offset is also generated on detector 11 by the shifting. This could lead to the FoV of detector system 2 being exceeded and thus the overall FoV being restricted. This can be changed by implementing an additional deflection function (such as a prism, a tilted mirror, a linear grating, etc.) in the output coupling area 5. This allows the offset of the coupled angular spectrum to be compensated (or symmetrized) and the output FoV to be aligned again with the FoV of detector system 2. Alternatively, it is also possible to tilt detector system 2 according to the angular offset.If not only one shifted decoupling area 5 is provided, but several decoupling areas 5 1 , 5 2 next to each other, including a corresponding compensation and adapted detection system 2, an enlarged horizontal FoV composed of several individual FoV can be generated (. Fig. 8B ).

[0124] With this configuration, it is possible to reach the limiting case where the combined width of all output areas 5 equals the width of the input area 4. However, it is essential that each individual output area 5 be considered separately in relation to the input area 4. As long as the ratio of width B1 / B2 is > 1 for each individual output area 5, each output area 5 remains the pupil of the system, so the described relationships continue to hold true.

[0125] The relationships described using the example of horizontal pupil position and horizontal field of view (FoV) can also be applied to vertical pupil position and vertical FoV, taking into account the folding of the beam path in this direction. However, the following special considerations apply in the vertical direction, including vignetting of the beam.

[0126] The vertical field of view (FoV) received by a hypothetical infinitely extended waveguide system and forwarded to the output coupling area is, in the infinite-infinity configuration of waveguide 1, given by the critical angle of total internal reflection within waveguide 1 and the propagation angle of less than 90° relative to the normal of the waveguide interface, i.e., the front 7 and back 8. For finitely extended, realistic waveguides 1, however, a propagation angle of less than 80° relative to the normal of the front 7 or back 8 must be achieved to ensure that beams L1-L3 propagate from a large angular range to the output coupling area 5 and not past it. For a typical refractive index of 1.5, an angular range between 40° and 80° relative to the normal of the front 7 or back 8 thus propagates within waveguide 1 and is coupled out again by the output coupling area 5.

[0127] Just as the horizontal FoV can be limited, so too can the vertical FoV of the overall system (waveguide 1 together with detector system 2) be limited by the vertical FoV of detector system 2. Furthermore, due to the spectrally divided input and output angular range, the spectral sensitivity of detector 11 can also restrict the vertical FoV. For example, if detector 11 is not sensitive to particularly long-wavelength and / or short-wavelength radiation, the effective extent of detector 11 decreases, and thus the vertical FoV of detector system 2 is reduced. Fig. 8C ).

[0128] In the described embodiments, the image on the detector exhibits the described color gradient, so that a full-color image cannot be transmitted and recorded via the waveguide 1.

[0129] The described reflective volume holograms for the coupling area 4 and the coupling area 5 can, for example, be produced by exposing a photosensitive volume holographic material 12, which is integrated into the waveguide 1, with a reference wave 13 with a wavelength of 532 nm, which is incident on the front 7 at an angle of incidence of 0°, and a signal wave 14 with the same wavelength, which is incident on the back 8 at an angle of incidence of 60°, as shown in Fig. 9A As shown, the reference wave 13 and the signal wave 14 originate from the same laser, so that an interference field or interference volume is created over the photosensitive volume holographic material and corresponding refractive index modifications can form there.

[0130] Photosensitive materials such as glasses, dichromate gelatins, or photopolymers can be used as photosensitive volume holographic materials. These can, for example, be applied to a PC film (polycarbonate film) and exposed accordingly. The film can then be laminated onto a substrate for waveguide 1 to create the waveguide 1. The film can be laminated, for example, only in the area of ​​the input coupling region 4 and the output coupling region 5. Alternatively, full-surface lamination over the entire waveguide area is possible, whereby only the corresponding input and output coupling functions are exposed in the input and output coupling regions. To protect the volume holograms, it is advisable to apply another substrate to the laminated volume hologram. This results in a layer stack with the following basic structure: transparent substrate, cement or adhesive layer, volume hologram, cement or adhesive layer.Adhesive layer, transparent substrate.

[0131] Due to the spectral angular dependence already described, an incident plane wave W1 ( Fig. 9B The spectral range of 605 nm ± 5 nm, which strikes the reflective volume hologram in the material at an angle of +20°, is deflected towards the front face 7 such that the deflected wave W1 strikes the front face 7 at an angle β1 of approximately 40°. For the remaining wavelengths of the plane wave W1, the reflective volume hologram of the coupling area 4 is transparent.

[0132] For a plane wave W2 striking the reflective volume hologram at an angle of 0°, wavelengths in the range of 532 nm ± 4 nm are reflected such that they strike the front surface 7 at an angle β 2 of approximately 60°. The remaining wavelengths of the plane wave W2 pass through the reflective volume hologram, making the reflective volume hologram transparent to these wavelengths of the plane wave W2.

[0133] Of a plane wave W3, which strikes the reflective volume hologram in the material at an angle of -20°, the wavelengths of 395 nm ± 3 nm are reflected to the front face such that they strike the front face at an angle β3 of approximately 80°. The remaining wavelengths of the plane wave W3 pass through the reflective volume hologram, so that the reflective volume hologram is transparent for these wavelengths.

[0134] To achieve the transmission of angular information (image information from infinity) through waveguide 1 over the largest possible spectral range, this can be done in Fig. 4 The angle-dependent spectrum shown can be improved by the fact that the coupling region 4 not only has one reflective volume hologram, but several reflective volume holograms 41, 42, 43, 44 and 45 arranged one below the other, as shown in Fig. 10 and Fig. 11A-F The volume holograms 41–45 differ in that they exhibit different spectral angular selectivities, meaning that different wavelengths are reflected by the volume holograms 41–45 at the same angle of incidence. Due to this angular selectivity, radiation coupled into the waveguide 1, for example from volume hologram 41 by reflection towards the front face 7, is not (or only minimally) affected by the underlying holograms 42–45, so that the coupled radiation can propagate (largely) unaffected to the output coupling area 5.

[0135] The volume holograms 41–45 can also be arranged one above the other in the z-direction, creating a layer stack on the waveguide. Furthermore, it is possible to implement the functions of all five holograms into a single hologram (or volume hologram), also known as multiplexing.

[0136] The different spectral angular properties can be achieved, for example, by using the same angular setting as in Fig. 9A Different wavelengths can be used for the reference wave 12 and the signal wave 13. Alternatively, it is possible to use the same wavelengths for all volume holograms 4 1 - 4 5, with the angle of incidence of the reference wave 12 and the signal wave 13 being varied appropriately.

[0137] The reflective volume holograms 4 1 - 4 5 were produced with the exposure configuration according to Fig. 9A The images were taken at different wavelengths. The exposure wavelength for volume hologram 4 was 1900 nm (black), for volume hologram 4 2660 nm (red), for volume hologram 4 3532 nm (green), for volume hologram 4 4400 nm (blue), and for volume hologram 4 5370 nm (violet).

[0138] In Fig. 11B-11F The coupling of the angular range by the minimum angle of -20°, the maximum angle of +20°, and the central angle of incidence of 0° for each of the volume holograms 4 1 - 4 5 is schematically represented. At 0°, the spectral range around the central wavelength with which the exposure of the respective reflective volume hologram 4 1 - 4 5 was performed is deflected and coupled in by each reflective volume hologram 4 1 - 4 5.

[0139] In Fig. 12 is in the same way as in Fig. 4 The simulated overall spectrum is shown, which is coupled into waveguide 1 by the five reflective volume holograms 41–45. Accordingly, each reflective volume hologram 41–45 contributes a different spectral range at each angle of incidence. When considering the entirety of all reflective volume holograms 41–45, the spectral bandwidth is thereby increased at the individual angles, ultimately ensuring a broadband image formation across all angles of incidence.

[0140] Furthermore, Fig. 12 The shift of the coupled spectrum towards shorter wavelengths with increasing angle of incidence and the shift of the coupled spectrum towards longer wavelengths for decreasing angles of incidence can be determined.

[0141] Fig. 13A This shows, as an example, the spectrum coupled in with an incidence angle of 0°. Fig. 13B The corresponding spectrum for an incidence angle of +20° and the coupled spectrum for an incidence angle of -20° are shown in Fig. 13C shown. In all representations according to Fig. 13A - 13C The wavelength in µm is shown along the x-axis and the coupling efficiency along the y-axis, ranging from 0 (no coupling) to 1 (complete coupling). A comparison with the representation according to... Fig. 5 shows that, compared to a single reflective volume hologram, there is a significantly improved sampling of the coupled spectrum as a result of using a higher number (five reflective volume holograms compared to one reflective volume hologram) of specifically recorded volume holograms.

[0142] In Fig. 14 The corresponding reflective volume holograms 51-55 for output coupling are shown. The overall height of the reflective volume holograms 51-55 is preferably chosen to be similar to the entrance pupil 14 of the detector system 2 in order to detect as much light as possible.

[0143] Just as with the input holograms, the volume holograms 51–55 can also be arranged one above the other in the z-direction for output coupling, creating a layer stack on the waveguide. Furthermore, it is possible to implement the functions of all five holograms into a single hologram or volume hologram, also known as multiplexing.

[0144] To couple a nearly continuous spectrum into waveguide 1 at any angle, thus ensuring the transmission of full-color image information, for example, forty selectively exposed reflective volume holograms can be arranged one above the other. A corresponding simulation of the angle-dependent coupling spectrum is shown in Fig. 15 The exposure wavelengths for capturing the individual reflective volume holograms according to the exposure configuration are shown. Fig. 9A The following wavelengths can be selected, for example, where the wavelength is given in nm: 358, 368, 378, 389, 400, 411, 421, 432, 443, 454, 464, 474, 487, 498, 509, 519, 532, 544, 556, 568, 583, 598, 613, 629, 645, 662, 679, 696, 715, 735, 755, 775, 795, 815, 835, 855, 875, 896, 917, and 940. Alternatively, the reflective volume holograms can also be created with a single wavelength and adjusted exposure angles of the reference and signal waves. 12, 13 are recorded. After propagation of the radiation in the waveguide 1 to the output coupling region 5, all angles and the complete spectrum are generally present at every location in this extended output coupling region 5 over a relatively large area. The output coupling can then be carried out, as described previously, with corresponding reflective volume holograms. Preferably, the same forty volume holograms are generated as are present in the input coupling region 4.

[0145] Since the output coupling area 5 often does not need to be transparent, any other type of output coupling of the radiation propagated up to the output coupling area 5 is also possible. Thus, in embodiments not part of the claimed invention, a tilted mirror surface, a prism, mirrored gratings, transmission gratings, and / or multi-order Fresnel structures can be used in transmission or reflection. At this point on the waveguide 1, the use of non-transparent optical surfaces is possible, since a non-transparent detector 11 is required anyway.

[0146] This possibility of designing the coupling area 5 also applies, of course, to the embodiments already described and to the embodiments yet to be described.

[0147] Tilted mirror surfaces and multi-order Fresnel structures in reflection or transmission advantageously exhibit high efficiency and do not introduce additional dispersion during deflection. However, they also do not provide dispersion compensation. Mirrored gratings and transmission gratings for output coupling can perform the desired dispersion correction, but they exhibit lower efficiency. A prism exhibits high efficiency but can adversely increase dispersion. The desired dispersion correction is advantageously achieved with the formation of reflective volume holograms, since each wavelength channel is coupled out via a separate reflective volume hologram. However, the efficiency is relatively low because the area of ​​the output coupling region must be divided by the number of individual reflective volume holograms.

[0148] In Figuren 16 bis 18B An embodiment of the waveguide 1 is shown in which the horizontal field of view (i.e., the field of view in the xz plane) is increased. It is assumed that the field of view of the detector system 2 does not restrict the field of view of the waveguide 1.

[0149] The coupling area 4 comprises three equally wide reflective volume holograms 41, 42 and 43, which are arranged one above the other (in the y-direction) and which cover different angular ranges and thus different horizontal fields of view in the xz-plane, as can be seen in particular in the top view in Fig. 17 is represented in angular space.

[0150] As an alternative to arranging holograms 41, 42, and 43 one above the other in the y-direction, they can also be arranged one above the other in the z-direction, creating a stack of layers on the waveguide. Furthermore, it is possible to implement the individual hologram functions of all three holograms into a single hologram (or volume hologram), also known as multiplexing.

[0151] For example, the second reflective volume hologram 4 2 in the xz-plane can cover the angular range γ 0 ± γ 1 and thus a central field of view for γ 0 = 0. The central field of view is given, for example, by the width of the second volume hologram 4 2, the width of the correspondingly assigned second output hologram 5 2, and by the distance between the two volume holograms 4 2 , 5 2.

[0152] The first reflective volume hologram 4 1, compared to the second reflective volume hologram 4 2, has an additional one-dimensional deflection function in the horizontal direction (in the xz-plane). The horizontal field of view assigned to the first volume hologram 4 1 is thus shifted by the amount of the applied deflection function (angular offset) in the angular range and is γ 0 - 2 • γ 1 ± γ 1. A corresponding applied deflection function for the third reflective volume hologram 4 3 results in a horizontal field of view of γ 0 + 2 • γ 1 + γ 1. Therefore, a different horizontal field of view can be transmitted with each volume hologram 4 1 - 4 3 in combination with the corresponding volume hologram 5 1 - 5 3 for output. The magnitude and direction of the applied deflection function (angle offset) can be used to specifically influence the overall FoV.For example, symmetrical or asymmetrical overall FoV as well as FoV with overlapping partial FoV or gaps between the partial FoV can be created.

[0153] To achieve the largest possible, symmetrical and seamless horizontal FoV accordingly Fig. 17 To achieve this, the implemented deflection functions must be selected according to the rule in the previous section such that the angle ranges are adjacent to each other and overlap as little as possible.

[0154] In the embodiment described here, all horizontal angular ranges propagate after coupling in the same horizontal channel, as in Fig. 16 This is indicated. This is also necessary to ensure detection with only one detection system 2. If all coupling holograms 4 1 - 4 3 are recorded identically except for the deflection function, the following also occurs accordingly. Fig. 18A also for superposition in the vertical direction. After extraction, all horizontal fields of view (FoV) would thus be superimposed on detector 11. To differentiate the individual horizontal angular ranges, the embodiment described here provides for the encoding of the horizontal angular ranges into a corresponding number of vertical angular ranges. Fig. 18B It was ensured that the coupling area 4 remains transparent over a wide range of angles and wavelengths under normal viewing conditions. The encoding of the horizontal angle ranges into vertical angle ranges can be achieved by designing the reflective volume holograms 41 to 43 to deflect into different vertical propagation angle ranges within the waveguide 1. Reflective volume holograms with appropriate deflection properties can be used for this purpose. Alternatively, a lamellar structure (flanges, not shown) can be placed in front of each reflective volume hologram 41–43 to restrict the respective vertical field of view (FoV). However, this significantly reduces the transparency in the coupling area 4.

[0155] With this differentiation of the various vertical propagation angle ranges, the radiation from each coupling volume hologram 4 1 - 4 3, and thus also each horizontal FoV, propagates into a different vertical FoV. After output coupling, the different vertical FoVs are then converted into laterally superimposed, adjacent spatial distributions onto the detector 11. This allows an enlarged horizontal FoV to be recorded, whereby the vertical FoV is reduced by the magnification factor of the horizontal FoV.

[0156] In an alternative variant, the detector-side spectral and angle-dependent separation of the horizontal FoV encoded in the vertical FoV, which is explained in more detail below, can be used.

[0157] If each horizontal FoV is coupled with an identically configured volume hologram, except for the deflection function (angular offset), each horizontal FoV propagates through waveguide 1 in the same vertical angular and spectral range. For each horizontal FoV, this results approximately, for example, in Fig. 4 The spectrum shown is dependent on the angle of incidence. Detector-side separation is then no longer possible.

[0158] Alternatively, each horizontal FoV can be coupled in different directions in the waveguide 1 with a special volume hologram, with each volume hologram 4 1 - 4 3 being recorded in a different configuration (exposure angle and / or wavelength).

[0159] In Fig. 19A, 19B und 19C are the angle-of-incidence and spectral-dependent efficiencies of the laterally offset coupling volume holograms 4 1 , 4 2 and 4 3 ( Fig. 18B ) shown. In the following analysis, it is assumed that the vertically coupled angular range is limited to ± 20° by total internal reflection in the waveguide. Furthermore, detector 11 only has a spectral sensitivity of 400 nm to 700 nm. This procedure can, of course, also be applied to other vertical angular ranges and detector sensitivities.

[0160] According to the representation in Fig. 19B The first volume hologram 41 couples an incidence angle range between 6.67° and 20° in a spectral range between 400 nm and 440 nm into the waveguide 1. In contrast to the first volume hologram 41, the second volume hologram 42 couples radiation from the entire incidence angle range over a spectrum from 400 nm to 650 nm into the waveguide 1. The third volume hologram 43 will couple the incidence angle range between -6.67° and -20° in a spectral range from 565 nm to 700 nm into the waveguide 1. Thus, each horizontal field of view is coupled into the waveguide 1 by a specific volume hologram 41-43 with different properties. These properties are used after extraction to separate the horizontal fields of view.

[0161] The holograms 41, 42, and 43 can also be arranged one above the other in the z-direction, creating a layer stack on the waveguide. Furthermore, it is possible to implement the individual hologram functions of all three holograms into a single hologram (or volume hologram), also known as multiplexing.

[0162] In the output coupling area 5, it can be expected that the spectral angular spectrum coupled in by all input volume holograms 41–43 is present at every location. In output coupling area 5, volume holograms 51, 52, 53 are arranged laterally offset above one another, exhibiting behavior identical to that of the vertical input. Each of these holograms 51–53 then ensures the output of the radiation coupled in by the corresponding input volume hologram 41–43 with the corresponding Fig. 19A - 19C The spectral angle distribution shown.

[0163] As in the coupling region, the holograms 51, 52, 53 can alternatively be arranged one above the other in the z-direction, creating a layer stack on the waveguide. Furthermore, it is possible to implement the individual hologram functions of all three holograms into a single hologram (or volume hologram), also known as multiplexing.

[0164] After the signal is extracted, the total field is separated so that the different horizontal fields of view (FoV) can be detected individually. For this purpose, the detector area of ​​detector 11 is first divided vertically. Each area corresponds to a vertical angular range. The number of area segments (vertical angular ranges) is identical to the number of different horizontal FoV. Normally, the detector area (total vertical angular range) is divided into equal areas (a division into areas of different sizes is also possible). Fig. 19C However, due to the typical behavior in reflection volume holograms within the individual angular ranges, spectral superposition occurs, so that ultimately different horizontal FoVs would be superimposed with the same vertical FoV. To avoid this, spectral filters can be provided for each sub-region of the detector 11, i.e., for each vertical partial angular range, which suppress unintended spectral components for a corresponding angular range. As a result, the different horizontal FoVs can be uniquely assigned to different regions on the detector (i.e., vertical angular ranges / FoV). Consequently, a unique assignment of the different horizontal FoVs to different vertical FoVs is achieved accordingly. Fig. 18b realized.

[0165] As an alternative to using spectral filters, it is also possible to use special output volume holograms, which only allow output in the required spectral range.

[0166] After applying the spectral filters or using the spectrally adapted output volume holograms, the following results are obtained: Fig. 20 The angle-dependent spectrum is shown. This eliminates the overlap of different horizontal FoV and thus allows for a clear assignment of the horizontal FoV to the corresponding vertical FoV.

[0167] This increases the detectable horizontal field of view (FoV). However, this simultaneously leads to a reduction in the vertical FoV.

[0168] The advantage of the described spectral coding of the horizontal FoV in the vertical FoV compared to the angular coding of the horizontal FoV in the vertical FoV lies primarily in the higher transparency over a large angular and spectral range with normal transmission through the coupling area 4.

[0169] One disadvantage of spectral coding is that each horizontal field of view (FoV) captures a different spectral band, and information can be lost if, for example, little or no radiation occurs in a particular horizontal FoV within the corresponding spectral range. This deficit can be compensated for by using multiple output coupling sections with correspondingly spectrally shifted input spectra for the different horizontal FoVs. However, this also requires a corresponding number of detector systems.

[0170] The following aspects must be considered in the general design of the overall waveguide system 1 and, in particular, in the design of the input and output coupling volume holograms: To realize n different horizontal fields of view (FoV), n different input and output coupling volume holograms as well as n angular ranges (detector ranges) including corresponding band or edge filter functions are required. The n horizontal angular ranges are converted into n vertical angular ranges.

[0171] The individual efficiency profiles of the volume holograms must not exhibit any spectral overlaps within the same angular range, as otherwise spectral separation of the vertical FoV and thus also the horizontal FoV would no longer be possible. Despite spectral filtering, a superposition of radiation components from different horizontal FoVs would occur.

[0172] To capture as much radiation power as possible, each volume hologram must be designed to cover the largest possible spectral range within its respective angular range. However, the spectral sensitivity of the detector must also be taken into account. When comparing the angle- and wavelength-dependent efficiency curves in Fig. 19B und 19C It becomes clear that in the angular range between +6.67° and +20°, only a 40 nm bandwidth of radiation is used. With a correspondingly optimized design of the volume hologram, an increase in this bandwidth and thus the coupling of a potentially higher radiation power would be possible. In contrast to the angular range between +6.67° and +20°, a spectral range of 135 nm is coupled in the angular range between -6.67° and -20°.

[0173] The subdivision of the horizontal field of view (FoV) is linked to the spectral properties of the volume hologram. Normally, all vertical sub-FoVs are the same size. However, depending on the application, different sizes of the vertical FoV can be implemented for the different horizontal FoVs. This requires a corresponding design of the volume holograms in combination with filtering before the individual detector areas.

[0174] In Fig. 21 Figure 1 shows an embodiment of the waveguide 1 in which the coupling area 4 is wider than the coupling area 5 and the coupling area 4 is realized by a reflective volume hologram. The coupling area 5 can also have a reflective volume hologram. The field of view (FoV) is determined by the size of these areas and their distance from each other. In conjunction with Fig. 22 In the described embodiment, it is assumed that the FoV of the detector system 2 does not restrict the FoV of the waveguide 11.

[0175] The approach according to Fig. 22 To increase detection efficiency, the coupling area 4 is vertically subdivided (along the second direction) into three sub-coupling surfaces 41, 42, and 43. While the central coupling surface (or the central reflective volume hologram 41) only includes a function for deflecting the radiation in the first direction (only in the y-direction without an x-component) towards the output coupling area 5, the right sub-coupling surface 42 additionally integrates a horizontal deflection function (or an x-component of the deflection) along the second direction (towards the central volume hologram 41), as shown in Fig. 22 This is indicated schematically. A corresponding horizontal deflection function along the second direction (towards the central volume hologram 4 1) is also integrated into the left sub-coupling surface 4 3.

[0176] Without this deflection function, the field of view (FoV) for the coupling surface 4 2 and the coupling area 5 would be determined by the sizes of the surfaces, their distance, and the decentering (along the second direction) of the coupling surface 4 2 relative to the coupling area 5 (the same would apply to the combination of the left coupling surface 4 3 and the coupling area). This FoV has an angular offset relative to the central FoV (given by the central coupling surface 4 1 and the coupling surface 5). The overall result is an increased FoV, which is determined by the total width of the two coupling surfaces.

[0177] By integrating the described deflection function into the two lateral coupling surfaces 42 and 43, the described angular offset can be compensated. The decentered coupling volume hologram 42, 43 then covers the same field of view (FoV) as the central coupling volume hologram 41 in combination with the output coupling volume hologram 5. However, the radiation emanating from the decentered coupling volume hologram 42, 43 propagates horizontally in the waveguide with a horizontal angular offset and is coupled out of the waveguide 1 with this offset. Thus, the same FoV is present side by side after output coupling. Using a detector system 2 with a sufficiently large FoV, these adjacent identical FoVs can be detected. This increases the detected radiation power for the horizontal FoV, but not the power density relevant for the signal-to-noise ratio.

[0178] To achieve this, the output coupling surface 5 is designed with the help of volume holograms in such a way that it couples out the radiation coupled in by the central input volume hologram 4 1 as well as the radiation coupled in by the decentered input volume holograms 4 2 , 4 3 into the same angular range.

[0179] This is achieved by having the output coupling area 5 have 5 different pre-exposed output coupling functions. Each output coupling function is efficient only for the radiation of the corresponding input volume hologram 4 1 - 4 3 (angle selectivity of volume hologram), so that ultimately the radiation propagating from different directions onto the output coupling area 5 is coupled out into the same angular range by the corresponding output coupling function. The strength of the angular selectivity can be adjusted via the thickness and refractive index modulation of the volume holographic material and the exposure configuration.

[0180] One of these functions corresponds to the original output coupling function and ensures only the vertical output of the radiation. All other implemented functions exhibit a special, adapted angular selectivity, so that they are only efficient for a horizontal angular range around the respective horizontal angular offset propagating from the corresponding decentered input surface 42, 43 towards the output coupling surface 5. In addition to the vertical output coupling function, this output coupling function includes compensation for the horizontal angular offset, so that the field of view (FoV) generated by the decentered input surfaces 42, 43 is superimposed on the FoV generated by the centered input surface 41. As a result, the power density within the FoV is increased, thus improving the signal-to-noise ratio.

[0181] The method described here can also be referred to as pupil reduction in optical terms (cf. pupil replication or pupil expansion in imaging = reversed light path). In this way, power can be collected over a large area in the input coupling area 4 and coupled out over a small area in the output coupling area 5.

[0182] This makes it possible to realize a coupling area 4 with very low efficiency and therefore high transmission. This enables high-intensity image information acquisition via a coupling surface 4 with the highest possible transmission.

[0183] On the other hand, the coupling area can also be implemented with a just-acceptable transmission, i.e., with a high coupling efficiency, in order to concentrate as much radiant power as possible onto a very small output coupling area. A very small solar cell could then be attached to the output coupling area to convert the radiant energy into electrical energy. It is also possible for the output to be coupled to a detector array.

[0184] Implementing different decoupling functions is possible with sufficiently thick volume holographic material with a sufficiently high refractive index modification. This implementation of different functions in a single holographic surface is also known as functional multiplexing. Alternatively, the individual decoupling functions can also be exposed into several stacked volume holographic sheets.

[0185] It should be noted that, just as in the vertical direction, this also results in angle-dependent spectral coupling in the horizontal direction, leading to an angle-dependent spectral profile in the horizontal direction as well. However, since spectral information is lost anyway due to the spectral distribution in the vertical direction, this color gradient does not represent a significant disadvantage of the method.

[0186] As from Fig. 22 As can be seen, the efficiency increase with vertical subdivision of the coupling area 4, while maintaining the same width of the coupling area, is associated with a reduction in the horizontal FoV. This disadvantage can be mitigated by combining it with the variant according to Fig. 16 bis 18 This can be compensated for, but this results in a reduction of the vertical FoV.

[0187] However, if a horizontal subdivision of the coupling surface is used... Fig. 21 according to Fig. 16 performed, the original FoV can be determined from only one coupling volume hologram ( Fig. 21 The coupling volume hologram area can be increased. However, with a constant coupling volume hologram area, this does not result in an overall increase in the coupled radiation power. However, if the area of ​​each coupling volume hologram is increased, the efficiency of the system can be improved using the procedure described above.

[0188] In principle, the coupling volume holograms can be freely distributed along waveguide 1. The effect on the respective field of view (FoV) with respect to the coupling volume hologram, as well as a correspondingly adjusted correction of coupled-out angular ranges, must then be taken into account.

[0189] In Fig. 23 Figure 1 shows an embodiment in which a relief grating is formed in both the input coupling area 4 and the output coupling area 5. The rules for determining the grating period are essentially the same as for a volume hologram. A diffraction angle is required for which total internal reflection in the waveguide 1 is ensured. Furthermore, symmetrical gratings are advantageously used for input and output coupling. Optionally, if desired, an imaging function can be applied to the input coupling grating and / or the output coupling grating. This allows objects located, for example, only 50 cm from the waveguide 1 to be sharply imaged.

[0190] The advantage of designing the input and output coupling gratings as relief structures compared to volume holograms lies in the lower angular and wavelength selectivity. As already described, when using volume holograms, a limited viewing angle is associated with a restricted wavelength range. Without a corresponding implementation Fig. 11 Gaps in the illuminating spectrum lead to dead vertical viewing angles. These defects can be prevented by the higher wavelength and angle acceptance of relief structures.

[0191] The coupling grid 20 can be applied, for example, by means of an epoxy resin or a UV-curing polymer to the right surface 21 of the left plate 22 with thickness d 1 in Fig. 23 They can be molded. Typical polymers have refractive indices n of approximately 1.5.

[0192] The coupling grid 20 is then coated with a thin, high-refractive-index dielectric layer 23. Typical refractive indices for this are n > 2.0. For example, values ​​between 10 and 100 nm can be used for the thickness of the layer 23. It is particularly advantageous to coat not only the coupling grid 20, but the entire left plate 22 with the thin, high-refractive-index layer 23 in order to achieve a uniform transmission across the entire surface.

[0193] The second plate 24 (with a thickness d 2 ) is then bonded to the coupling grating 20 and the associated plate 22 (with a thickness d 1) using an epoxy resin or a UV-curing polymer. The coupling relief grating 20 is thus embedded in the substrate formed by the two plates 22 and 24, and, due to its thin, high-refractive-index layer, acts as a reflection grating 20 with diffraction efficiencies between 5% and 20%.

[0194] For the output coupling grid 25, a grid with the same number of lines (grid period) is used, which, however, is molded onto the outer surface 7 of the left plate 22 or onto the outer surface 8 of the second plate 24. In the case of the Fig. 23 In the illustrated embodiment, the output coupling grid 25 is molded onto the front surface 7. After molding, this grid 25 is coated with aluminum vapor deposition to achieve high output coupling efficiency. Efficiency values ​​of around 50% are achievable over a broad wavelength and angular spectrum.

[0195] The waveguide 1 with the input coupling grid 20 and the output coupling grid 25 has two apertures, since the edges of the input coupling grid 20 and the edges of the output coupling grid 25 each act as apertures that clip the beam path. In the illustration according to Fig. 23 Only one beam of light for exactly one wavelength is shown. Other wavelengths emanating from the same object point are deflected by the coupling grating 20 to different angles in the waveguide 1. This relationship between wavelength and propagation angle in the waveguide 1 is continuous, although not linear.

[0196] Thus, with long waveguides 1 containing many reflections (e.g., 10, 20, etc.), it is possible that the area of ​​the input grating 20 (viewed in a vertical section) falls precisely on the output grating 25. In this case, a large amount of light is transmitted. However, it is also possible that the aperture of the input grating 20 is imaged only once below and once above the output grating 25, so that no light is coupled out at the output grating 25.

[0197] The transmitted spectrum is thereby divided into efficient and inefficient regions that alternate almost periodically. Such a purely geometrically determined transmission spectrum is found in Fig. 24 The graph shows the wavelength in nm along the x-axis and the transmission efficiency along the y-axis, ranging from 0 (no transmission of the light incident on the input grating 20) to 1 (all the light incident on the input grating 20 is coupled out via the output grating 25, neglecting the grating diffraction efficiency). This transmission efficiency is shown for an angle of incidence of -15°, covering the wavelength range from 400 to 530 nm (dashed line), for an angle of incidence of 0°, covering a wavelength range from 440 to 645 nm (solid line), and for an angle of incidence of +15°, covering a wavelength range from 555 nm to 690 nm (dotted line).The spectral limitations arise firstly from the condition for total internal reflection and secondly from the deflection angle after coupling, at which the output coupling grating is just struck (without internal total internal reflection at the output surfaces). It is evident from this that the transmitted spectral interval shifts with the angle of incidence. The transmitted spectral interval increases with increasing refractive index of waveguide 1.

[0198] In Fig. 25 The vignetting caused by the entrance pupil (EP) of detector system 2 is shown schematically. Thus, a portion of the coupled beams cannot reach detector 11, resulting in a geometrically determined transmission spectrum, as shown in Fig. 26 is shown schematically. The representation in Fig. 26 corresponds to the representation in Fig. 24 As expected, this vignetting leads to worse transmission spectra for the angles of incidence -15° and +15°.

[0199] The coupling grid 20 is designed as a sawtooth grid, i.e. the profile shape of each grid period follows at least approximately a sawtooth shape. Fig. 27 Figure 1 shows a simulated cross-section through one grating period of the buried coupling grating, assuming a slight profile rounding. The lateral extent from 0 to 430 nm is plotted along the x-axis, and the profile section from 0 to 300 nm is plotted along the y-axis, resulting in a layer thickness of 60 nm and a blaze depth of 120 nm. Using such a structure, it is possible to couple a wide wavelength range into waveguide 1 with approximately 10 to 15% efficiency. The resulting diffraction efficiency (reflectivity) is shown in Figure 1. Fig. 28 The curves RE0 and RM0 show the reflectance for zeroth-order reflection for s-polarized fields (RE) and p-polarized fields (RM). RM1 and RE1 show the reflectance for the negative first diffraction order for s-polarized fields (RE) and p-polarized fields (RM).

[0200] For the coupling grid 25, a similar profile shape can be used as in Fig. 27 can be used. However, a metal coating is used there instead of the high-refractive-index dielectric.

[0201] In Fig. 29 und 30 Figure 1 shows an embodiment in which the waveguide 1 is integrated into a display 30. The display 30 can be a display of a mobile consumer device (such as a mobile phone or a laptop). It can also be a display of a desktop computer.

[0202] As in the depictions of Fig. 29 und 30 As can be seen, the coupling area 4 with the reflective volume hologram is formed on the back side 8. This hologram causes a beam deflection such that the deflected beams are guided within the display, for example by total internal reflection, until they reach the coupling area 5 with the coupling volume hologram, which causes a deflection towards the camera sensor 11. The image thus captured is essentially a frontal view of the user B, who is looking directly at the coupling area 4. The image therefore corresponds to a recording made with a camera sensor positioned in the area of ​​the coupling area 4. The solution can therefore be described as follows: Fig. 29 und 30 This can be described as a transparent image sensor integrated into the display without affecting its display function. It allows for the recording of images or image sequences directly at the display 30, thus enabling a frontal view of the scene to be displayed.

[0203] This feature can be advantageously used for applications such as video telephony or taking self-portraits (so-called selfies), as the user's gaze towards the display coincides with the center of the image captured by the camera. This allows both participants in a video call to maintain eye contact, which was previously impossible because the corresponding cameras were always positioned at the edge of the display. This eye contact leads to a more natural and immersive conversation experience. When taking a self-portrait, the user can, for example, follow the live preview of the image being captured without having to look away from the camera and towards the display.

[0204] In addition to its deflecting function, the coupling grid 5 can, for example, have an imaging function, so that no additional optics are needed in front of the camera sensor 11. This maximizes the integration of the camera into the display 30.

[0205] Due to the pronounced wavelength and angle selectivity of the diffraction efficiency typical of volume holograms, and the possibility of tailoring the diffraction efficiency, the portion of the display 30 covered by the coupling grating appears largely transparent, and the content displayed on the screen remains visible to the viewer. For this to occur, the efficiency of the coupling grating 4 must be high enough to allow the camera sensor 11 to capture the image. At the same time, the efficiency of the coupling grating must be low enough to maintain transparency and prevent any effects that would be disturbing to the viewer. The resulting transparency of the applied volume hologram in the coupling area therefore also depends on the light sensitivity of the camera sensor 11 used.

[0206] In the simplest configuration of the coupling area 4 and the coupling area 5 according to the embodiment of Fig. 1 bis 3 A different wavelength range is transmitted to detector 11 or camera sensor 11 for each angle, resulting in an image with a vertical color gradient. This image can then be converted into a monochrome image. To obtain, for example, a natural multicolored image, the monochrome image can be colorized in real time using image information captured by another front camera. In this way, a natural image can be provided via the volume-holographically implemented camera function, offering the aforementioned advantage of a frontal view.

[0207] Alternatively, the color functionality of the volume holographically implemented camera function can be implemented according to the exemplary embodiment of Fig. 10 bis 15 This would eliminate the need for an additional front camera and post-coloring.

[0208] At the in Fig. 29 und 30 In the illustrated embodiment, it was assumed that the output area 5 and the camera sensor 11 are located below a non-display area 31 of the display 30, since otherwise the light emitted by the display would also fall on the camera sensor 11. This would interfere with the image capture.

[0209] However, if a display 30 is used that is transparent when inactive, the camera sensor can also be arranged below the area actually used by the display, as in the embodiment shown in Fig. 31 und 32 is shown.

[0210] When a picture is taken, the relevant area of ​​the display 30 is dimmed so that only the light coming from the coupling area 5 falls on the camera sensor 11. In this way, the display 30 can be used completely for display purposes when the camera function is not activated. If the camera function is activated, only a portion of the display 30 is dimmed. The display area is therefore only restricted when necessary, and only near the edge.

[0211] In a wide range of applications, significant added value can be generated by introducing and / or detecting additional radiation within the beam paths of an optical system without substantially affecting its core functionality. Radiation detection involves reflecting radiation from the beam path at a suitable point and directing it onto a sensor. Introducing radiation into the system utilizes the opposite light path to introduce additional radiation components. This can be used, for example, to illuminate the object's environment or to convey additional information.

[0212] Partially mirrored substrates 40 are used for this purpose in a known manner, as in Fig. 33 The diagram is schematically represented, with two lenses 41 and 42 schematically depicted for the optical system. This is the so-called combiner principle. However, this requires sufficient installation space within the optical system, which is determined by the size of the tilted substrate 40 or the projected beam diameter at the point of incidence and reflection. Furthermore, introducing and detecting radiation at the same point in the beam path is only possible with considerable effort (special coatings, complex optics for radiation superposition).

[0213] In this case, too, the waveguide 1 according to the invention, already described, can be used, which enables the introduction and / or detection of radiation with small installation space requirements, as schematically shown in Fig. 34 is shown.

[0214] In addition to radiation injection and detection, this approach also offers the possibility of selectively influencing the spectral properties of the injected or emitted radiation through filtering. Due to the high transparency of waveguide 1, these multifunctional components can be used at virtually any location within an optical system (including, if necessary, on the optical axis). Furthermore, the special physical properties of volume holograms allow these functions to be implemented at almost the same position.

[0215] The optical systems mentioned include not only technical optical systems but also transparent surfaces such as windows, car windshields, etc. In most cases, reflecting information in or out via a tilted, partially mirrored substrate is not an acceptable solution. However, the principle of the described waveguide 1 makes it possible to implement these functionalities directly within the transparent substrate (windows, car windshields, etc.) itself, without significantly affecting the transparency, i.e., the original beam path. As a result, entirely new applications arise for surfaces that normally serve, for example, only to protect people or objects from environmental influences such as wind, temperature, particles, or radiation.

[0216] The described principle of waveguide 1 can also be used for illumination and / or projection. For this purpose, the light path in waveguide 1 is used in the opposite direction, and a static or dynamic light source (or a correspondingly luminous image source) is used instead of the detector. Thus, the previous output coupling area becomes the input coupling area 4, and the previous input coupling area becomes the output coupling area 5, as shown in Fig. 35, 36 und 37 The radiation from the light source 32 is coupled into the waveguide 1 via the coupling area 4 and guided in this waveguide to the coupling area 5, via which the coupling out into space or a correspondingly downstream optical system then takes place.

[0217] From a physical perspective, there are no fundamental differences between projection and illumination, since in both cases radiation is generally provided in a predetermined form (angle and / or spatial distribution) in space or along a beam path. The illumination of an object can be schematically described as follows: Fig. 38 depicted. Fig. 39 schematically shows the projection of a virtual image for a viewer B. In Fig. 40 The projection of a real image (here the letter F) is shown schematically. The projection of a real image is identical to illumination.

[0218] Since the coupling area 4 and the output coupling area 5 can be implemented with volume holograms (preferably reflective volume holograms), nearly transparent light sources or projection devices can be realized due to the high angular and wavelength selectivity of the volume holograms. This allows for high transfer efficiency from coupling to output, the generation of a defined radiation pattern (i.e., angular or spatial distribution), and desired spectral compositions.

[0219] For the detection system, the horizontal extent of the input and output coupling areas 4,5 can be adapted to the required field of view (FoV). In the vertical direction (or first direction), the size of the areas is determined by the aperture size of the detection system. To achieve an extended FoV, it is preferable to select a larger horizontal (or second direction) extent for the input coupling area 4 than for the output coupling area 5. This results in an input coupling strip.

[0220] For a projection system, 2D pupil replication is preferred to provide image information or illumination over an extended area (eyebox). The pupil, coupled into the substrate, is replicated in both horizontal and vertical directions. The output area is therefore an area whose dimensions differ from those of the input area in both horizontal and vertical directions (which differs from the detection system described above).

[0221] When the detection and projection systems are connected, the visible area of ​​the waveguide contains the coupling area of ​​the detection with the dimensions described above and the coupling area of ​​the projection with the dimensions described above.

[0222] Of course, optical imaging functions can also be assigned to the coupling and / or output coupling areas 4, 5 of waveguide 1 for projection and / or illumination. This allows for the realization of finite-infinite, infinite-finite, finite-finite, or infinite-infinite configurations of waveguide 1. This enables targeted control of the radiation propagation, angular distribution, and / or distribution at a defined location during coupling and / or output. In addition to or instead of optical imaging functions such as lens and / or concave mirror functions, diffuser or beam transformation functions can also be incorporated into the coupling and / or output coupling surfaces, thereby also allowing targeted control of the radiation propagation.

[0223] As with the detection configuration, the effective size in the input and output coupling areas 4, 5 also has a significant influence on the angular range transported, accepted or emitted by the functionalized waveguide 1 in the illumination / projection configuration.

[0224] LEDs, lasers, etc., can be used as light sources, and displays (e.g., DMD displays, LCD displays, etc.) can be used as image sources. By using dynamic light sources or dynamic image sources, temporally variable angular or spatial distributions can be generated. This allows for adaptable illumination solutions, for example, in microscopes, or for introducing variable information (virtual or real image content) into beam paths.

[0225] As an alternative to the waveguide-based solution, illumination and / or projection functions with high transparency over a large angular and length range with normal transparency can also be implemented in a free-jet setup based on reflection volume holograms according to Fig. 41A, 41B und 41C or based on transmission volume holograms according to Fig. 42A, 42B und 42C to be realized.

[0226] As has been explained several times, volume holograms exhibit an angle-dependent spectral sensitivity. Due to this property, radiation within a defined wavelength range is efficiently deflected at a certain angle and, for example, coupled into waveguide 1. While this effect is rather disadvantageous for general detection and illumination applications, it can also be advantageously used, for example, in spectral detection or illumination applications.

[0227] In the field of illumination, this behavior of the volume hologram can be used to filter out a defined spectral range from directional incident radiation. For example, narrowband light sources with partial coherence, which, unlike lasers, are particularly suitable for the holographic projection of virtual or real image content, can be realized. With convergent or divergent radiation, it is possible to influence the wavelength spectrum deflected by the volume hologram by means of appropriately recorded volume holograms and the angular distribution of the volume hologram.

[0228] The angle-dependent spectral sensitivity of the volume hologram can also be used for detection applications. This is based on the simulated, angle-of-incidence and spectral-dependent efficiency according to... Fig. 4For each angle of incidence, a different spectral range is efficiently deflected and, for example, coupled vertically into a waveguide 1. In the simplest camera setup, as in Figs. 1 to 3 As shown, an output coupling volume hologram 5 corresponding to the input coupling volume hologram 4 is used, which provides for the output of the angles propagating in the waveguide 1, where each angle consists of a defined spectral range due to filtering or coupling. The angular distribution is then transformed into a spatial distribution on the detector 11 by an imaging function in the output coupling volume hologram 5 or by a lens, where each location in the vertical direction then corresponds to a defined spectral range. By means of an angle scan in the vertical direction and a synchronous detection of the intensity on the detector 11, angle-dependent spectral information can be determined in parallel in the horizontal direction.

[0229] Such a system can, for example, be mounted on the underside of an aircraft. By knowing the detection system 2, the aircraft's speed, and its position, spectral information about the area overflown can be determined, with the data being recorded in a horizontally parallelized manner.

[0230] In the previously described embodiments, possibilities for functionalizing transparent surfaces were presented, whereby high transparency of these surfaces can be maintained over a large angular and wavelength range with normal transparency. In this process, the radiation in the transparent area is coupled into the waveguide 1 in the case of detection and out of the waveguide 1 in the case of illumination / projection using special volume holograms 4. Propagation between this transparent detection and emission surface occurs based on total internal reflection within the substrate or the waveguide. However, reflection due to a suitable reflective coating is also possible. The optical electronics (detectors and control sources) can then be integrated at a position advantageous from a design or functional perspective. Thus, the position of the radiation detection or emission is flexible.Radiation emission is no longer tied to the position of the optoelectronics.

[0231] The high transparency of the described, volume holographically implemented functions allows them to be realized in almost the same location, since the functions do not influence each other or only do so to a minor extent if the volume holograms are designed appropriately.

[0232] In practice, this can be achieved, for example, by stacking the volume holograms, in which the individual functions are implemented, on top of each other. Alternatively, several optical functions can be imprinted into a single volume hologram (provided the volume holographic material has a sufficiently large maximum refractive index modification). The transparency of the functionalized waveguide 1 is maintained with a suitable design of the volume holograms 4 and 5. In combination with waveguide-based beam transport and the resulting small form factor, highly functionalized, transparent surfaces such as windows can be realized. Furthermore, this approach allows for a significant expansion of the functionality of optical systems through a relatively minor modification of the beam path.

[0233] Fig. 43D shows an example of the functionalization of a window 40, in which the lighting function ( Fig. 43A ), the detection function ( Fig. 43B ) and the projection function ( Fig. 43C The volume holograms are introduced using volume holography, and the radiation transport is realized via waveguides. The different volume holograms for the input and output regions are distinguished by the index: 41, 42, etc., 51, 52, etc.

[0234] Alternatively, individual functions can also be implemented in a non-waveguide-based manner (i.e., using free-jet propagation approaches).

[0235] In Fig. 44A Is this for lighting, in Fig. 44B Is this for detection and in Fig. 44C This is shown schematically for the projection. However, in these exemplary embodiments, the space advantage generated by the waveguide is (at least partially) lost again. Fig. 44A - 44C The described implementations with the respective free-ray configurations show reflection volume holograms. In Figs. 44D, 44E and 44FThis is shown together with transmission volume holograms. All functions not realized by free-jet propagation are shown in the Fig. 44A - 44F Implemented using waveguide technology.

[0236] The expansion of the functionality of an optical system is in Fig. 45 This is illustrated using the example of illumination and detection in a microscope 45 for the purpose of recording an overview of a sample. In this case, radiation is coupled into a waveguide 1 and directed to the volume holographic output coupling surface 5, which then couples the radiation into the projection space (sample carrier 46). The radiation backscattered from the sample 47 is subsequently coupled back into the waveguide 1 by another volume hologram 4', which then transports the radiation to the detector 11.

[0237] With appropriate design of the illumination system of microscope 45, the waveguide-based system 1 can, for example, remain in the beam path as a sample finder without disturbing the transmitted light illumination beam path. Alternatively to the in Fig. 45 In the arrangement shown, the waveguide-based illumination and imaging system (waveguide 1) can also be mounted above the sample 47. However, the installation space between the objective 48 of the microscope 45 and the sample 47 is usually very limited in microscopes.

[0238] In both variants, the fact that illumination and detection are located at the same point and on the optical axis of the microscope 45 has a positive effect on the overall functionality of the system. The perpendicular illumination of the sample 47 and the perpendicular detection of the radiation allow for a relatively high efficiency (detection power / illumination power). At the same time, a projection function is provided. In conventional optical systems, this can only be achieved with considerable effort and / or a large amount of installation space. In the case of the functionalized window 40 or the functionalized waveguide 1, a comparable property would only be possible with transparent radiation sources and detectors.

[0239] The described waveguide 1 configurations can be used in the field of vehicles (e.g. cars, trucks, motorcycles, etc.).

[0240] To monitor and observe the external environment and the interior of vehicles, an increasing number of optical projection systems, such as cameras, are being installed both inside and outside the vehicle. As vehicles transition from purely manual human control to assisted and ultimately autonomous driving, it can be assumed that more and more powerful detectors will be used in cars in the future to ensure comprehensive and reliable sensor technology. However, these sensors must not compromise aesthetics, especially in the automotive sector. Ideally, the sensors should be invisible to the customer or anyone observing the vehicle.

[0241] Currently, optical detection systems are integrated into non-transparent areas such as the B-pillar. This leaves only a small opening for the lens. To increase design freedom and improve occupant visibility, the non-transparent areas of the vehicle body will be reduced in the future. Sensors based on conventional methods, which are mandatory in certain areas, will then no longer be able to be integrated almost invisibly. This phenomenon is already evident in optical systems for road sign and lane recognition, which must be mounted in the upper center of the windshield to obtain accurate measurements.Using conventional optical systems creates a non-transparent area in the windshield, which can restrict the driver's view and negatively impact the car's appearance. With the described waveguide, all car windows can be equipped with detector surfaces in the future without significantly affecting transparency. The radiation can be coupled into the glass from the designated coupling area and transported via waveguide to the detector, which can then be located in a non-transparent area of ​​the car.

[0242] In Figs. 46A, 46B, 46C and 46DVarious configurations of the waveguide 1 in the windshield 50 of a motor vehicle 51 are shown schematically. The coupling area 4 can be positioned at the desired location in the windshield 50, as it does not significantly affect the transparency of the windshield at that point. The radiation coupled in via the coupling area 4 is then guided by reflections in the windshield 50 to the output coupling area 5, which can be positioned in an area that is no longer visible. The detector system 2 (not shown) can also be positioned in this area.

[0243] In the variant according to Fig. 46A The disconnection area 5 is located in the area of ​​the car roof. In the variant according to... Fig. 46B The disconnection area is located in the area of ​​the hood or dashboard. Of course, lateral coupling is also possible, as shown in... Figs. 46C and 46Dshown, so that the coupling area 5 is then e.g. in the area of ​​the right ( Fig. 46C ) or left ( Fig. 46D) is positioned on the A-pillar. The windshield 50 (or any other transparent surface) can thus be functionalized using (volume) holographic structures and / or micro-optical relief structures to avoid significantly affecting its transparency under normal viewing conditions across a wide range of wavelengths and angles. Through the described functional implementation, radiation from the environment or the vehicle interior is coupled into the windshield 50. This then acts as a waveguide and, for example, propagates the radiation to the output coupling area via total internal reflection, which then couples the radiation to the detector system 2. Thus, the essentially transparent surface of the windshield can be used as the detection area, while the detector 11 can be mounted in a design- and / or functionally advantageous position.Consequently, the position of radiation detection or radiation absorption is no longer tied to the position of detector 11. This is particularly advantageous when radiation detection must take place at a specific location that also requires high transparency.

[0244] This in connection with Fig. 46A - 46D The described waveguide system can also be used in reverse for illuminating an object space or for projection purposes. In this configuration, the radiation emanating from a static or dynamic source (e.g., light source and / or image source) is coupled into the waveguide, i.e., disk 50, via the output coupling area, which now serves as the input coupling area and is located in the non-transparent region of the vehicle, and then coupled out again using the input coupling area 4, which now serves as the output coupling area and is located in the transparent region.

[0245] Of course, it is also possible to combine the described detection and projection / illumination, and then to position the coupling and decoupling areas located in the transparent part of the windshield close to each other or one above the other, as already described. Optimized detection can be achieved by specifically adapting the illumination to the detection, particularly in terms of spectral and angle dependency.

[0246] In the simplest waveguide configuration 1 (infinity-infinity configuration, recorded at one wavelength), it must be considered that, in the convolution / waveguide direction, only a specific spectral band is coupled into and ultimately coupled out of the waveguide at each angle. If the coupling and coupling regions 4, 5 are arranged one above the other, as in Figs. 46A and 46BAs shown, a color gradient dependent on angle or location results relative to the road in the vertical direction. When the arrangement is rotated by ± 90° (as in Figs. 46C and 46D As shown in the diagram, the color gradient is oriented horizontally (i.e., parallel to the road). Therefore, the orientation of the input and output coupling areas 4 and 5 must be carefully selected according to the specific task. The different field of view (FoV) of the two perpendicular directions (determined by the size ratio and distance between the input and output coupling areas 4 and 5, and the spectral sensitivity of the detector) must also be taken into account.

[0247] Furthermore, when designing the coupling area, the inclination of the respective disc 50 and the expected position of the object to be detected should be considered. For example, when observing the driver using the coupling area 4 integrated into the windshield, an angular shift of the vertical field of view (FoV) must be introduced in the form of a corresponding deflection function so that the optical axis in the vertical direction roughly coincides with the area of ​​the driver's face and, for example, the driver's torso is not detected. Thus, a specific design of the coupling area 4 allows for adaptation to the expected object and its projection. The same relationship applies to the use of the waveguide system as illumination. In this case, the coupling area 5 must be adapted to the desired illumination of the object space.

[0248] The in connection with Figs. 10 to 15The described design for providing RGB functionality is advantageous in automotive sensor applications to prevent detection failures in specific angular ranges due to the absence of spectral components. This ensures that a signal can be detected at any angle within a defined spectral range (ideally the spectral sensitivity of the detector). Furthermore, the reliability against detection failures resulting from spectral insensitivity of the input region 4 can also be increased by implementing the input and output regions 4 and 5 using the described surface relief structures.

[0249] The in connection with Figs. 16 to 20The described variant of the waveguide for increasing the horizontal FoV, in which the horizontal FoV is increased by encoding in the vertical FoV, can be advantageously used in the automotive sector, since a significantly larger horizontal FoV than vertical FoV is often required here.

[0250] The in connection with Figs. 21 and 22 The described variant for increasing detection efficiency can be advantageously used in the automotive sector, since four large surfaces in the form of discs are available for the coupling area. This allows as much beam power as possible to be directed to the detector system 2, and also enables the acquisition of image information under poor lighting conditions.

[0251] Furthermore, it is also possible to couple in radiation outside the visible spectral range, for example, radiation from the near-infrared. With the use of a suitably appropriate detector system, it is therefore possible to acquire image information under lighting conditions that are poor for humans.

[0252] As in connection with Figs. 33 to 45As described, the functionalized waveguides 1 can be used not only for receiving radiation but also for illuminating the object space or for projection. For this purpose, the opposite light path is used compared to the described detection arrangements using waveguide 1. In this way, the exterior and / or interior of the vehicle can be selectively illuminated to ensure reliable detection even under poor lighting conditions. This avoids, for example, detection failures in specific angular ranges, which can occur with the simplest version of waveguide 1 when certain spectral ranges are missing. The artificial illumination and the angle-dependent spectral sensitivity of the coupling surface must be coordinated.

[0253] For windshields and rear windows of motor vehicles, there is already a particularly high demand to make detection areas located at defined points as transparent as possible and to relocate the corresponding detectors or detection systems to opaque areas within the vehicle body. This allows the driver an unobstructed view while simultaneously integrating optical sensors for driver assistance systems, thereby increasing road safety. In addition to detection on the exterior, the functionalization described above also enables the acquisition of image information inside the vehicle. The resulting image sequences, combined with appropriate data processing, can be used to implement further safety systems such as driver fatigue detection or gesture control.This method also allows for the identification of the driver and / or passengers without a visible opening for a camera.

[0254] Just as in the windshield and rear window, coupling surfaces and detectors can also be integrated into the framing body areas of fixed side windows. Here too, the additional functionality can serve to capture image information both inside and outside the vehicle without significantly affecting the surface's transparency.

[0255] It is also possible to integrate multiple detection systems into different windows of a vehicle. In this way, the position of people and objects in space can be determined as with a 3-dimensional coordinate system (keyword: tomography and thus measurement from multiple perspectives).

[0256] The arrangement of the functionalized surfaces and the detector can also be applied to the illumination design. However, in this case, the output coupling surface, i.e., the emitting surface, is located in the transparent area, and the input coupling surface, including the radiation source, is located in the opaque area.

[0257] With a suitable design of the detection and / or lighting system, the output area of ​​the lighting system can coincide with the input area of ​​the detection system.

[0258] In contrast to fixed discs, the arrangement of the detection surface in movable discs is preferably chosen such that it lies in areas that are not within the vehicle body or within a non-transparent area, either during or after the process. Furthermore, the detection system must be rigidly connected to the movable disc to ensure the detection function remains functional during and after the process. Fig. 47A - 47C Various arrangements of the coupling and discoupling areas are shown using the example of a movable side window.

Claims

1. Functionalized waveguide for a detector system, wherein the waveguide (1) comprises a transparent base body (6) having a front side (7) and a rear side (8), wherein the base body (6) comprises a partly transparent input coupling region (4) and an output coupling region (5) spaced apart therefrom in a first direction (R1), wherein the input coupling region (4) comprises an input coupling relief grating which deflects only a portion of radiation coming from an object to be detected and impinging on the front side (7), such that the deflected portion propagates as coupled-in radiation in the base body (6) as far as the output coupling region (5) by means of reflections and impinges on the output coupling region (5), wherein the output coupling region (5) comprises an output coupling relief grating which deflects at least one portion of the coupled-in radiation impinging on it, such that the deflected portion emerges from the base body (6) via the front side (7) or rear side (8) in order to impinge on the detector system (2), wherein the input coupling relief grating and the output coupling relief grating comprise the same grating period, characterized in that the input coupling relief grating is embodied as a buried sawtooth grating having a grating period of 430 nm, a blaze depth of 120 nm and a layer thickness of 60 nm, wherein the material of the sawtooth grating has a refractive index of 2.4, and the material in which the sawtooth grating is buried has a refractive index of 1.5.

2. Waveguide according to any of the preceding claims, wherein the extent of the input coupling region (4) in a second direction (R2) transversely to the first direction (R1) is greater than the extent of the output coupling region (5) in the second direction (R2).

3. Waveguide according to any of the preceding claims, wherein the output coupling relief grating is embodied as a reflective output coupling relief grating.

4. Waveguide according to any of the preceding claims, wherein the input coupling region (4) and / or the output coupling region (5) also comprise(s) an imaging optical function in addition to the beam deflection.

5. Waveguide according to any of the preceding claims, wherein the input coupling relief grating transmits a portion of the radiation coming from the object to be detected and impinging on the front side (7), such that said portion emerges from the base body via the rear side (8).

6. Detector system comprising a functionalized waveguide according to any of the preceding claims.

7. Detector system according to Claim 6, wherein the detector system has a detector, on which the portion of the radiation which is deflected by the output coupling region impinges.

8. Detector system according to Claim 7, wherein the detector (11) is connected to the front or rear side (7, 8) of the base body (6).

9. Detector system according to Claim 7 or 8, wherein no separate imaging optical element is arranged between the detector (11) and the front and / or rear side (7, 8).