DISTANCE MEASURING SYSTEM

Description

[0001] The invention relates to a distance measuring system.

[0002] A distance measurement system can, for example, include a LIDAR system. The LIDAR system ("Light Detection and Ranging") is an optical method that allows the distance to an object located in a spatial area or measurement volume to be determined by measuring the time of flight of light pulses. Various LIDAR systems are already known that can use optical elements to guide the light beam into the measurement volume and receive a reflected light beam from the measurement volume to direct it to a detector device. The distance measurement is based on measuring the time of flight of the light from the light source to the detector.

[0003] From US 2018 / 0106901 A1 a LIDAR sensor for detecting an object in the environment and a method for activating a LIDAR sensor are known.

[0004] From DE 10 2016 220 232 A1 an optical element for a LIDAR system is known which has an expansion optics and a projection lens, wherein the expansion optics and / or the projection lens are formed by a holographic element.

[0005] US 2018 / 0232048 A1 discloses an object tracker comprising a waveguide and at least one grating lamella formed in the waveguide. Illuminating light propagates along a first optical path from a source to an object, while light reflected by at least one surface of the object is deflected by the grating lamellas in a second optical path to a detector.

[0006] From DE 10 2016 118 471 A1 an optical detection device for arranging on an attachment part of a motor vehicle and for monitoring an area adjacent to the attachment part is known.

[0007] From DE 10 2017 208 896 A1 a LIDAR device for scanning a scanning area with at least one beam is known, comprising at least one beam source for generating the at least one beam and for coupling the at least one beam into at least one optical waveguide, a deflection device for deflecting the at least one beam into the scanning area, comprising a receiving unit for receiving at least one beam reflected from an object and for deflecting the at least one reflected beam onto a detector, wherein the deflection device comprises a holographic optical element and a spatial light modulator.

[0008] A disadvantage of the known distance measuring systems is that separate optical elements have to be aligned with each other and can slip, for example, due to mechanical stress.

[0009] The invention is based on the object of providing a distance measuring system that is robust against mechanical stress.

[0010] The problem is solved by the subject matter of the independent patent claims. Advantageous developments of the invention are disclosed by the dependent patent claims, the following description, and the figures.

[0011] The invention provides a distance measuring system. The distance measuring system comprises a carrier medium, which is made, for example, of glass or plastic and is designed to transmit light coupled into the carrier medium by means of internal reflection. In particular, a glass plate can be provided as the carrier medium. The carrier medium has a measuring region for emitting and receiving light, a coupling region, and a detector region, which are arranged in different sections of the carrier medium. The rigid coupling of said regions by means of the carrier medium can prevent the described slipping. The distance measuring function, which can be a LIDAR function, is achieved via the invention-specific light guide described below.

[0012] The distance measuring system comprises a light source configured and arranged to emit light with a predetermined wavelength onto the coupling region. The light source can, in particular, comprise an LED or a laser, preferably a laser diode, capable of emitting light with the predetermined wavelength. The predetermined wavelength refers to an emission wavelength of the light source, which is predetermined depending on the LED or laser used. The predetermined wavelength can preferably be in an infrared wavelength range of 800 nanometers to 1000 nanometers, in particular 850 nanometers, 905 nanometers, 1064 nanometers, or 1550 nanometers.

[0013] The coupling region is designed as a holographic element with a coupling diffraction structure and is configured to couple light with the predetermined wavelength, which falls from the light source onto the coupling diffraction structure, into the carrier medium in the direction of the measuring region, wherein the measuring region is designed as a combination of a holographic element with a radiation diffraction structure and a holographic element with a reception diffraction structure, wherein the radiation diffraction structure is configured to couple in-coupled light of the predetermined wavelength from the coupling region out of the carrier medium into a measurement volume to be monitored for reflection on an object outside the carrier medium, and wherein the reception diffraction structure is configured to couple the reflected light of the predetermined wavelength, which falls from outside the carrier medium onto the reception diffraction structure,to couple into the carrier medium in the direction of the detector area.

[0014] The detector region is designed as a holographic element with a detector diffraction structure and is configured to couple in-coupled light of the predetermined wavelength from the measuring region, which light falls on the detector diffraction structure, from the carrier medium to a detector device, wherein the detector device is configured to detect the light of the predetermined wavelength coupled out to the detector device and to determine a distance to the object from a light travel time of the light from the light source to the detector device.

[0015] In other words, light with a given wavelength can be emitted from a light source into a coupling region, where it is coupled into a carrier medium by a coupling diffraction structure, which can be a holographic element. Within the carrier medium, the light can be transmitted to a measurement region by internal reflection, i.e., total internal reflection.

[0016] At least two holographic elements are provided in the measuring area, each of which can, for example, have its own diffraction structure, namely the emission diffraction structure and the reception diffraction structure, wherein the holographic elements can be connected to one another, for example in a layered construction using a transfer adhesive. The emission diffraction structure can couple the light out of the carrier medium and radiate it onto a measurement volume to be monitored, in which the light can be reflected off an object and fall back into the carrier medium, where the reception diffraction structure can couple the reflected light into the carrier medium in the direction of the detector area. In this case, in the direction of the detector area means a macroscopic direction from the measuring area to the detector area along the carrier medium, or a directional vector in the direction of propagation of the light by means of internal reflection.A light path can of course have a zigzag course due to internal reflection.

[0017] The detector region is also designed as a holographic element with a detector diffraction structure that can diffract the light reflected from the object in the measurement volume onto a detector device. The detector device can then detect the incoming signal of the reflected light and determine a distance to the object from the light's travel time from the light source to the detector device. For this purpose, the light source can preferably emit the light in a light pulse, wherein a time measurement can be started simultaneously with the emission of the light pulse and stopped when the light pulse arrives at the detector device. From this time, the distance to the object can then be determined using the speed of light and taking into account the light's travel time in the distance measuring system, i.e. only the light's travel time from leaving the measurement region to re-entering the measurement region is measured.

[0018] A holographic element, also known as a holographic optical element (HOE), is an optical element whose operating principle is based on holography and can be manufactured using holographic processes, i.e., holographic exposure. For this purpose, an interference pattern created by the superposition of two coherent waves of the same wavelength can be recorded on a light-sensitive layer of the holographic element. This method can be used to produce optical gratings, lenses, mirrors, and beam splitters that have the same properties as conventional optical elements, but are thinner.

[0019] The invention offers the advantage that the distance measuring system is more robust and resistant to external influences, such as mechanical stress, since a more compact design with fewer separate components can be achieved. Furthermore, the distance measuring system requires less installation space. Additionally, the distance measuring system could be applied to transparent and curved surfaces, such as a window or side pane or headlight of a motor vehicle, or to a display, particularly a cell phone display, thanks to the light transmission of the carrier medium.

[0020] Furthermore, it is provided that the coupling region and the detector region have a smaller dimension than the measuring region, wherein the coupling diffraction structure has a scattering grating structure which is designed to deflect light rays of the light incident on the coupling diffraction structure to different degrees depending on the point of incidence, so that the coupling diffraction structure spreads or scatters the light rays onto the emission diffraction structure, and wherein the receiving diffraction structure has a bundling grating structure which is designed to deflect the reflected light incident from outside the carrier medium onto the receiving diffraction structure to different degrees depending on the point of incidence, so that the receiving diffraction structure focuses the light rays onto the detector diffraction structure, and wherein the detector diffraction structure has a corresponding scattering diffraction structure which is designed toTo parallelize the light beams for coupling out of the carrier medium to the detector device. In other words, an image of the coupling area can be enlarged to a dimension of the measuring area, and an image of the measuring area can be reduced to a dimension of the detector area, so that an expansion optic or a collimation optic can be formed using the diffraction structures.

[0021] A focusing grating structure can have an inhomogeneous diffraction structure which, for example, can diffract light rays from an edge of the diffraction structure more strongly than light rays from a center of the diffraction structure, whereby the light rays can be focused. Accordingly, a diverging grating structure can have a grating structure in which light rays can be fanned out depending on their incident position. In this embodiment, the focusing grating structure and the diverging grating structure and the corresponding distances between the two structures are preferably selected such that the light rays converge from the focusing grating structure to the diverging grating structure and are parallelized again by the diverging grating structure, or alternatively diverge from the diverging grating structure to the focusing grating structure and are parallelized or focused again by the focusing grating structure.This arrangement is comparable to a Galilean telescope, in which a converging lens and a diverging lens are arranged one behind the other such that the focal lengths of the two lenses coincide at a single point behind the diverging lens. This offers the advantage that a detector that is smaller than the measuring range can be used for the detector device, eliminating the need for complex beam expansion in the coupling area, thus saving costs.

[0022] The invention also includes embodiments which provide additional advantages.

[0023] One embodiment provides that the coupling diffraction structure, the radiation diffraction structure, the reception diffraction structure and the detector diffraction structure are designed as an optical grating, in particular a holographic volume grating or a holographic surface grating.

[0024] Optical gratings, also called diffraction gratings, as well as their mode of operation and manufacturing processes are generally known. In principle, optical gratings can be formed as at least partially periodic structures, so-called grating structures, in a substrate which can bring about light guidance through the physical effect of diffraction, as is known, for example, from mirrors, lenses or prisms. When light, i.e. light rays, fall on the optical grating, whereby the incident light rays in particular satisfy the Bragg equation, the light rays are diffracted or deflected by the optical grating. The light guidance can thus occur in particular through interference phenomena of the light rays diffracted by the optical grating. The deflection structure can accordingly also be referred to as a diffraction structure.A holographic surface grating and a holographic volume grating are holographic optical elements that can be manufactured in particular by a holography process.

[0025] An optical grating can preferably be designed to be angle- or direction-selective and / or wavelength- or frequency-selective with respect to the incident light. Thus, only light incident on an optical grating from a predetermined direction of incidence, for example at a predetermined angle, can be deflected. Light incident on the optical grating from a different direction is preferably not deflected, or the greater the difference from the predetermined direction of incidence, the less deflected it is. Additionally or alternatively, only light of one wavelength, or light that deviates from the predetermined wavelength by at most a predetermined wavelength range, can be deflected by the optical grating at a specific diffraction angle.In other words, for example, an optimal wavelength can be specified at which only a portion of the light in a certain wavelength or frequency range around the optimal wavelength is deflected by the optical grating (e.g. a central optimal wavelength and a range with wavelength values ​​up to + / - 10 percent of the optimal wavelength), while the remaining portion of the light can propagate through the grating without being deflected. At least a monochromatic light portion can thus be split off from polychromatic light that hits the optical grating. The deflection effect is thus frequency-selective and / or angle-selective, with the deflection effect being maximum for an optimal wavelength and decreasing or becoming weaker towards longer and shorter wavelengths, for example according to a Gaussian bell.In particular, the deflection effect only affects a fraction of the visible light spectrum and / or in an angular range of less than 90 degrees.

[0026] Particularly preferably, optical gratings can be produced by exposing a substrate, for example photolithographically or holographically. In In this context, the optical gratings can also be referred to as holographic or holographic-optical gratings. Two types of holographic-optical gratings are known: holographic surface gratings (SHGs for short) and holographic volume gratings (VHGs for short). With holographic surface gratings, the grating structure can be created by optically deforming a surface structure of the substrate. The changed surface structure can deflect incident light, for example, by reflecting it. Examples of holographic surface gratings are so-called sawtooth or blaze gratings. In contrast, with holographic volume gratings, the grating structure can be incorporated into the entire volume or a partial area of ​​the volume of the substrate. Holographic surface gratings and holographic volume gratings are generally frequency-selective.

[0027] Glass, preferably quartz glass, is particularly suitable as a substrate material for incorporating an optical grating. Alternatively or additionally, a polymer, in particular a photopolymer, or a film, in particular a photosensitive film, for example made of plastic or an organic material, can also be used. When using such substrates, it should also be noted that the material, especially in substrate form, has flexible and optical waveguide properties. Substrates that have a deflection structure for diffracting light, for example in the form of an optical grating, can also be referred to as holographic optical elements (HOEs).

[0028] A further embodiment provides that the coupling region, the measuring region and the detector region are formed integrally with the carrier medium or that the carrier medium is formed as a separate element from the coupling region, the measuring region and the detector region.

[0029] In the first case, the coupling region, the measuring region, and the detector region can thus, for example, be incorporated directly into a surface structure of the carrier medium. The carrier medium itself can thus be designed as an HOE, for example, etched or lasered. In the second case, the coupling region, the measuring region, the detector region, and the carrier medium can be designed separately. The coupling region, the measuring region, and the detector region can, for example, each form a separate element, and the carrier medium can form a further element that rests against the other elements. The respective regions can thus be designed as at least one respective HOE. This allows for a greater choice when using a carrier medium. For example, the coupling region, the measuring region, and the detector region can be formed in different sections of a holographic foil or plate.To attach the film or plate to the carrier medium, the film or plate can be glued to the carrier medium. Alternatively, the holographic film can also be designed as an adhesive film and adhere directly to the surface of the carrier medium through molecular forces, i.e., without adhesive.

[0030] A further embodiment provides that the holographic element of the emission diffraction structure and the holographic element of the reception diffraction structure are connected to one another, wherein the reception diffraction structure is arranged between the measurement volume and the emission diffraction structure from the perspective of the measurement volume, and the reception diffraction structure at least partially overlays the emission diffraction structure. In other words, the emission diffraction structure and the reception diffraction structure can be designed as two holographic elements that are connected to one another in a planar manner, in particular bonded by a transfer adhesive, wherein the emission diffraction structure can transmit the light from the light source through the reception diffraction structure, since the latter is transparent to the angle of incidence of the light from the emission diffraction structure.The reflected light, in turn, can be deflected by the receiving diffraction structure arranged in front of the emission diffraction structure, since the angle of incidence here is sensitive according to the grating structure of the receiving diffraction structure. The holographic elements can also be arranged offset from one another so that they only overlap in a partial area. Furthermore, more than two holographic elements, for example, a layer structure of three or more, can be used. This embodiment offers the advantage that an emission and reception area in the measurement area can be designed identically, whereby a light path outside the carrier medium to the object can be designed identically in both the forward and return directions.In addition, a more stable design of the distance measuring system can be achieved because the holographic elements are not formed separately but are connected to each other, which makes it more difficult for the radiation diffraction structure and the reception diffraction structure to shift.

[0031] A further embodiment provides that the radiation diffraction structure has a focusing grating structure and / or a scattering grating structure, each of which is designed to deflect different light beams of the light incident on the radiation diffraction structure to different degrees depending on the point of incidence. This means that a different angular change of the respective light beams of the light can be achieved depending on the point of incidence; for example, outer light beams can be deflected at a larger angle with respect to an optical axis than inner light beams. In particular, it can be provided that an interaction of the input diffraction structure with the radiation diffraction structure parallelizes, fans out, or focuses the light beams to a focal point for coupling them out of the carrier medium.The radiation diffraction structure can also have multiple regions, each of which has one of the grating structures, whereby the radiation diffraction structure can also have a converging grating structure and a scattering grating structure. This embodiment offers the advantage that different radiation characteristics can be generated and, for example, a large measurement volume can be scanned by a fanned-out beam, or an object in the measurement volume can be scanned more precisely by a focused light beam.

[0032] Preferably, the radiation diffraction structure is divided into predefined sub-regions, which may, for example, have different sizes. The predefined sub-regions differ in the provided bundling grating structure or scattering grating structure in order to deflect the light rays of the light for coupling out of the carrier medium to different degrees in certain regions depending on the point of incidence in order to define a radiation characteristic. For example, predefined sub-regions of the radiation diffraction structure can focus the light rays to generate a finer scan of the measurement volume, and predefined sub-regions can fan out the light rays in a radiation region to generate a large-area scan.This embodiment offers the advantage that different radiation characteristics can be defined to scan regions of a measurement volume with varying degrees of accuracy. For example, a central sub-region can be configured to perform a finer scan, while outer sub-regions can be configured to perform a coarser scan.

[0033] One embodiment provides that the detector device has a photodiode matrix, wherein the photodiode matrix is ​​designed to assign the light coupled out to the detector device according to an entry position in the measuring range and / or an angle of incidence in the measuring range. In other words, a photodiode matrix, which can in particular be a photoelectric mixer detector (PMD sensor), can be provided, which, similar to a photocamera, can assign the light according to the entry position in the measuring range, i.e., the photodiode matrix can simultaneously determine a distance for each photodiode in the photodiode matrix. Alternatively or additionally, it can also be provided that the entry angle can be assigned to the measuring range in the photodiode matrix.The angle selectivity of the receiving diffraction structure can, for example, ensure that only light entering the measuring area at a specific angle is coupled into the carrier medium and thus to the detector device. This means that the receiving diffraction structure acts as a collimator that only transmits predetermined entrance angles. For example, the photodiode matrix can be designed as a matrix of CCD or CMOS sensors. This embodiment offers the advantage that location and distance information can be determined across an entire measuring volume using a light pulse. This makes it possible to implement a TOF camera (time of flight camera) that can record an entire distance scenario at once. The TOF camera thus provided can preferably be used to implement gesture recognition in front of a display or a screen into which the distance measuring system can be installed.

[0034] The invention also includes combinations of the features of the described embodiments.

[0035] Exemplary embodiments of the invention are described below. Shown are: Fig. 1 shows a schematic overview of an exemplary embodiment; Fig. 2 shows a schematic representation of the functionality of an exemplary embodiment; Fig. 3 shows a schematic side view according to an exemplary embodiment; Fig. 4 shows a schematic side view according to another exemplary embodiment.

[0036] The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention that can be considered independently of one another, each of which also develops the invention independently of one another. Therefore, the disclosure is intended to encompass combinations of the features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0037] In the figures, the same reference symbols designate elements with the same function.

[0038] In Fig. 1 1 shows an overview of a distance measuring system 10 according to an exemplary embodiment. The distance measuring system 10 can be designed, for example, as a LIDAR system or as a TOF camera. The distance measuring system 10 can have a carrier medium 12, which is manufactured, for example, using a layered construction, wherein a first layer can comprise a glass plate 14 and a second layer one or more holographic elements 16, which can be, for example, a photopolymer film. The at least one holographic element 16 can be glued onto the glass plate 14 or incorporated therein. In addition, a second glass plate 15 can enclose the at least one holographic element 16 as a further cover layer.

[0039] The distance measuring system 10 can have a light source 18, which can be designed, for example, as a laser diode and which can emit light into the carrier medium 12. In the carrier medium 12, the light emitted by the light source 18 can be deflected by diffraction and thus distributed over the entire surface of the carrier medium 12 and coupled out of the carrier medium 12 by a further diffraction structure, which is represented by the coupled-out light beams 20. These coupled-out light beams 20 can preferably be emitted over a surface into a measurement volume to be monitored for reflection by an object (not shown) outside the carrier medium. After reflection by the object, the light beams can re-enter the carrier medium 12 as reflected light 21.

[0040] In the carrier medium 12, a further diffraction structure can then direct the reflected light onto a detector device 22, which can preferably comprise a photodiode and which can detect the arrival of the light as an electronic signal. In particular, the light's travel time from emission by the light source 18 to detection by the detector device 22 can be measured in order to determine a distance to the object. In particular, a time offset that can arise from a light path within the carrier medium 12 can be subtracted.

[0041] With the Fig. 2 The schematic representation of the distance measuring system 10 shown in FIG. 1 is intended to explain the functionality of the distance measuring system 10 in more detail using the exemplary embodiment shown here. In Fig. 2 The distance measuring system 10 is designed with a carrier medium 12, a light source 18 and a detector device 22. The carrier medium 12, which can be designed as a light guide and can transmit coupled light by means of internal reflection, can be comparable to the embodiment of Fig. 1 two glass plates 14, 15 as flat cover layers for a holographic element 16 and another holographic element 17. Alternatively, however, it can also be provided that a light-conducting plastic is used instead of the glass plates.

[0042] The holographic element 16 can, for example, comprise a photopolymer film and be bonded to the glass plate 14 via an adhesive bond. Furthermore, the holographic element 17 can be bonded to the glass plate 15 via an adhesive bond, and the two holographic elements 14 and 15 can be bonded to each other via a transfer adhesive. The thickness of the holographic elements 16, 17 can be less than one millimeter, and the dimensions shown here are chosen only to illustrate the example.

[0043] The holographic element 17 can be configured in a coupling region 24 such that a coupling diffraction structure 26 is created, which can be, for example, a holographic surface grating and can couple light from the light source 18 into the carrier medium 12 in the direction of a measuring region 28, as indicated by the arrow pointing from bottom to top with the tip to the left in the coupling diffraction structure 26. Likewise, the holographic element 17 can be configured in the measuring region 28 with a radiation diffraction structure 30, which can be configured, for example, as a holographic volume grating, and which can couple the light from the coupling region 24 out of the carrier medium 12, wherein the coupled-out light can radiate through the holographic element 16 arranged above it, in particular in a direction toward an object to be measured, as indicated by the arrows pointing from right to left with the tip pointing upwards.The holographic element 16 arranged above, which has a receiving diffraction structure 32, which is designed, for example, as a holographic volume grating, can be transparent to the light coming from the direction of the radiation diffraction structure, since an angle of entry into the holographic element 16 does not fulfill an angle condition for deflection by the holographic element 16.

[0044] In particular, the receiving diffraction structure 32 in the measuring area 28 can be configured such that only light having a specific angle of incidence, in particular from a region outside the carrier medium 12 onto the measuring area 28, is deflected. This means that the receiving diffraction structure 32 can preferably be angle-selective and only couples incident angles of, for example, plus or minus one degree from a predefined entrance direction into the carrier medium 12. This makes it possible to create an optical collimator that, for example, only allows light rays into the carrier medium 12 that impinge perpendicularly on the measuring area 28.

[0045] Consequently, the coupled-out light can be reflected, for example, by an object outside the carrier medium 12 and fall back onto the measuring area 28, where it can then be coupled back into the carrier medium 12 by the receiving diffraction structure 32 in the direction of a detector area 34, which is indicated by the arrows from top to bottom with the tip on the left in the receiving diffraction structure 32.

[0046] In The holographic element 16 can be configured in the detector region 34 such that a detector diffraction structure 36, which is configured, for example, as a holographic surface grating, can couple the reflected light out of the carrier medium 12 in the direction of the detector device 22, where a light propagation time of the light from the light source 18 to the detector device 22 can then be determined. In this case, the detector device 22 can preferably have a photodiode matrix 38, which can assign the light coupled out to the detector device 22 according to an entry position of the reflected light on the measuring region, similar to a photo camera.For example, a light beam incident on a corner of the measuring area and thus on a corner of the receiving diffraction structure 32 can be directed to a corresponding corner of the photodiode matrix 38, whereby a light travel time can be determined for each reflected light beam reflected back to the receiving diffraction structure 32, from which a three-dimensional distance image can be determined.

[0047] The coupling region 24, the measuring region 28, and the detector region 34 can be formed integrally with the carrier medium 12. Alternatively, however, the carrier medium 12 can also be formed as a separate element from the coupling region 24, the measuring region 28, and the detector region 34.

[0048] The coupling region 24 and the detector region 34 can, in particular, have smaller dimensions than the measuring region 28. For this purpose, the coupling diffraction structure 26 can have a diffraction grating structure that can deflect light rays from the light source 18 to varying degrees depending on the point of incidence on the coupling diffraction structure 26, so that the coupling diffraction structure 26 couples the light rays into the carrier medium 12 in such a way that they are fanned out onto the emission diffraction structure 30. Likewise, the reception diffraction structure can have a bundling grating structure that can deflect light rays of the reflected light from outside the carrier medium 12 to varying degrees depending on the point of incidence on the reception diffraction structure 32, so that the light rays are focused onto the detector diffraction structure 36.The detector diffraction structure 36 may have a scattering diffraction structure matching the condensing grating structure of the receiving diffraction structure 32, which can parallelize the light rays of the reflected light for coupling out of the carrier medium 12 onto the detector device 22.

[0049] Depending on the design of the distance measuring system 10, the radiation diffraction structure 30 can have a bundling grating structure and / or a scattering grating structure which, depending on the design of a radiation characteristic and an interaction with the coupling diffraction structure 26, can parallelize, fan out or focus the light beams to a focal point for coupling out of the carrier medium 12.

[0050] In Fig. 3 1 shows such an exemplary fanning out of light beams. Here, light beams from the light source 18 can be fanned out via the coupling diffraction structure 26 onto the emission diffraction structure 30. The emission diffraction structure 30 can, for example, have a further dispersion diffraction structure that fans out the light beams for coupling out of the carrier medium 12 onto a measurement volume to be monitored and can thus cover a wide monitoring area. The reception diffraction structure 32 can be designed accordingly so that it only allows an angle of incidence of the light beams for coupling into the carrier medium 12 in the direction of the detector device 22 that has the same angle of incidence as the emission direction, which is indicated by the double arrows 40.

[0051] In Fig. 4 A distance measuring system 10 according to a further exemplary embodiment is shown. Here, the carrier medium 12 can be designed similarly to the carrier medium 12 in Fig. 2However, the radiation diffraction structure 30 can be divided into predetermined sub-regions 42, which can, in particular, have different sizes, and the predetermined sub-regions 42 can differ in the grating structure provided for each sub-region. For example, certain regions can have a scattering grating structure, and other sub-regions can have a focusing grating structure, whereby the light rays are deflected to different degrees in certain regions for coupling out of the carrier medium 12. This allows a predetermined radiation characteristic to be generated.For example, sub-regions may fan out the light beams, thereby scanning a wide area having a low resolution, for example regions 43 and 44, but regions may also be provided which have a focusing grid structure and can scan a narrow area at a high scanning rate, such as regions 45 and 46.

[0052] Overall, the examples show how the invention can provide a distance measuring system, in particular in LIDAR or a TOF camera, via a holographic optical element.

Claims

1. A distance measuring system (10) comprising - a carrier medium (12), which is formed to transfer coupled-in light by means of internal reflection as a light guide, and comprising a measuring area (28) for emitting and receiving light, a coupling-in area (24) and a detector area (34), which are arranged in different sections of the carrier medium; - a light source (18), which is formed and arranged to emit light with a preset wavelength to the coupling-in area (24); wherein - the coupling-in area (24) is formed as a holographic element with a coupling-in diffraction structure (26) and configured to couple light with the preset wavelength, which is incident on the coupling-in diffraction structure (26) from the light source (18), into the carrier medium (12) towards the measuring area (28); wherein - the measuring area (28) is formed as a combination of a holographic element (17) with an emission diffraction structure (30) and a holographic element (16) with a reception diffraction structure (32), wherein the emission diffraction structure (30) is configured to couple coupled-in light of the preset wavelength from the coupling-in area (24) out of the carrier medium into a measurement volume to be monitored for reflection on an object outside of the carrier medium, and wherein the reception diffraction structure (32) is configured to couple the reflected light of the preset wavelength, which is incident on the reception diffraction structure (32) from outside of the carrier medium, into the carrier medium (12) towards the detector area (34); wherein - the detector area (34) is formed as a holographic element with a detector diffraction structure (36) and configured to couple coupled-in light of the preset wavelength from the measuring area (28), which is incident on the detector diffraction structure (36), out of the carrier medium (12) onto a detector device (22); wherein - the detector device (22) is formed to detect the light of the preset wavelength coupled out onto the detector device and to determine a distance to the object from a light propagation time of the light from the light source (18) to the detector device (22); - wherein the coupling-in area (24) and the detector area (34) have a smaller dimension than the measuring area (28), characterized in that the coupling-in diffraction structure (26) comprises a dispersing grating structure, which is formed to deflect light beams of the light, which is incident on the coupling-in diffraction structure (26), to different extent depending on a location of incidence, such that the coupling-in diffraction structure (26) expands the light beams onto the emission diffraction structure (30), and - wherein the reception diffraction structure (32) comprises a concentrating grating structure, which is formed to deflect the reflected light, which is incident on the reception diffraction structure (32) from outside of the carrier medium, to different extent depending on the location of incidence, such that the reception diffraction structure (32) focuses the light beams towards the detector diffraction structure (36), and wherein the detector diffraction structure (36) comprises a corresponding dispersing diffraction structure, which is formed to parallelize light beams of the light for coupling out of the carrier medium (12) onto the detector device (22).

2. The distance measuring system (10) according to claim 1, wherein the coupling-in diffraction structure (26), the emission diffraction structure (32), the reception diffraction structure (32) and the detector diffraction structure (36) are formed as an optical grating, in particular a holographic volume grating or a holographic surface grating.

3. The distance measuring system (10) according to any one of the preceding claims, wherein the coupling-in area (24), the measuring area (28) and the detector area (34) are formed integrally with the carrier medium (12) or wherein the carrier medium (12) is formed as a separate element to the coupling-in area (24), the measuring area (28) and the detector area (34).

4. The distance measuring system (10) according to any one of the preceding claims, wherein the holographic element (17) of the emission diffraction structure and the holographic element (16) of the reception diffraction structure are connected to each other, wherein, from the view of the measurement volume, the reception diffraction structure (32) is arranged between it and the emission diffraction structure (30) and the reception diffraction structure (32) at least partially overlaps the emission diffraction structure (30).

5. The distance measuring system (10) according to any one of the preceding claims, wherein the emission diffraction structure (30) comprises a concentrating grating structure and / or a dispersing grating structure, which are each formed to deflect different light beams of the light, which is incident on the emission diffraction structure (30), to different extent depending on the location of incidence.

6. The distance measuring system (10) according to claim 5, wherein the emission diffraction structure (30) is divided into preset sub-areas, wherein the preset sub-areas differ in the provided concentrating grating structure or dispersing grating structure, to deflect the light beams of the light for coupling out of the carrier medium (12) to different extent in certain areas depending on the location of incidence, to determine an emission characteristic.

7. The distance measuring system (10) according to any one of the preceding claims, wherein the detector device (22) comprises a photodiode array (38), wherein the photodiode array (28) is configured to associate the light coupled out onto the detector device (22) corresponding to an entry position on the measuring area (28) and / or an angle of entry on the measuring area.