Camera device and headlamp device for generating an environmental map

Abstract

The invention relates to a camera device (10) by means of which only such objects (O1, O2) in an environment (U) are to be filmed which lie in a predetermined object plane (E1, E2) at a distance from the camera device (10). To this end, the camera device (10) comprises an illumination device (30) in order to illuminate the desired object (O1, O2) with illumination light (31) and an image detection device (40) in order to detect the reflected illumination light (41) on the object (O1, O2). In order to carry out the filming depending on the object plane, the camera device also comprises a control device (50) in order to operate the illumination device (30) to provide the illumination light (31) in light pulses and to operate the image detection device (40) to detect the reflected illumination light (41) within a filming interval which is assigned to the light pulses. In order to avoid disturbing effects on the resulting image, a turning unit (20) is additionally provided for turning the respective illumination light (31, 41) between the environment and the illumination device (30) and the image detection device (40).

Description

Technical Field

[0001] This invention relates to a camera device for generating or detecting at least one image of at least one object in an environment. The invention also relates to a headlight device for a motor vehicle, comprising a headlight light source and a camera device. Background Technology

[0002] In particular, the present invention relates to the detection of an image of a identified or desired object in an environment. To this end, it is specified that the desired object is illuminated with predetermined illumination light by means of an illumination device, wherein the illumination light is detected by an image detection device, such as a photographic camera or video camera, by means of an image sensor upon reflection on the object. The image sensor can convert incident light into an image signal in a known manner. With appropriate processing, the image signal can then be combined or reconstructed by a display device (e.g., a display) into the desired image of the object in the environment.

[0003] The camera device is preferably constructed as a so-called "Holocam". This means that holographic optics (HOE) are used to transmit illumination light provided by the illumination device to the desired object, and to deflect the illumination light reflected from the object to the image detection device. Therefore, the image detection device and the illumination device do not need to be on the same optical axis as the object to be photographed in the environment.

[0004] To realize the aforementioned "holographic camera," the camera device includes a light guide medium comprising a first deflecting element and a second deflecting element. The light guide medium can be constructed, for example, as a plate or sheet made of glass or plastic. The first and second deflecting elements are preferably arranged spaced apart from each other along the longitudinal extension direction of the light guide medium. Here, the first and second deflecting elements provide the deflection function or light steering function of the camera device. This means that the first and second deflecting elements are preferably implemented as diffractive optical elements and / or the aforementioned holographic optical elements, such as volumetric holograms. The light guide medium is configured to transmit or transfer light coupled to the light guide medium at a corresponding angle by the first and / or second deflecting elements through internal reflection, particularly total internal reflection, between the first and second deflecting elements. The transmittable light is preferably the previously mentioned illumination light. To provide illumination light through the light guide medium to illuminate objects in the environment, the camera device therefore also includes an illumination device configured to provide illumination light to the second deflecting element. The second deflecting element is now configured to couple the illumination light input into the light guide medium for transmission to the first deflecting element. The first deflection element is configured such that illumination light transmitted via internal reflection in the light guide medium is output from the light guide medium and coupled again to illuminate an object. To generate an image of the corresponding object in the environment, the camera device also includes the aforementioned image detection device. To transmit the illumination light reflected from the corresponding object back to the image detection device, the first deflection element is configured to input and couple the reflected illumination light back into the light guide medium for transmission to the second deflection element. Correspondingly, the second deflection element is configured to output and couple the illumination light transmitted via internal reflection in the light guide medium back to the image detection device.

[0005] The aforementioned deflection elements are therefore constructed for bidirectional deflection or redirection of the illumination light. This means that each deflection element can both couple the (reflected) illumination light input into the light guide medium and couple the (reflected) illumination light output from the light guide medium.

[0006] An example of a design scheme for a "holographic camera" is known from DE 10 2017 217 193 A1. In this design, the "holographic camera" is used as a so-called head-up display in a vehicle. Here, a volumetric hologram is arranged in a transparent sub-region of the vehicle window glass, serving as a holographic film with at least two optical elements for light deflection. Light from the environment is input-coupled into the window glass and deflected to the camera through these optical elements. The camera can then generate an image signal from the incident light, which is provided to a projector. The projector generates projection light from the image signal. This projection light is then input-coupled into the window glass through the optical elements and output-coupled to be displayed to the driver of the vehicle, thus displaying an image of the environment on the window glass.

[0007] In this case, no targeted lighting is set for the objects expected in the environment.

[0008] Instead of holographic optical elements used for light deflection, lenses can also be used, for example, as disclosed in US 2009 / 0153712 A1. On the one hand, illumination light can be emitted from the illumination unit into the environment through the lens; on the other hand, illumination light reflected from the environment can be provided to the camera. However, a disadvantage of such lenses is that their manufacture, especially grinding, is largely costly.

[0009] Therefore, it is advantageous to use the aforementioned holographic optical element instead of a lens for light redirection. For example, a corresponding system is known from US2019 / 0086674 A1. A head-mounted display is described here that uses a "holographic camera" to display a desired image to the wearer based on their gaze direction. Here, a corresponding holographic optical element is used to couple infrared light into a light-conducting medium for gaze direction detection and then output coupling it to the user's eyes. The light reflected from the eyes can then be input-coupled into the light-conducting medium again through the holographic optical element and output-coupled to the camera to determine the gaze direction. A projector can then be manipulated according to the gaze direction to generate the desired display image in the form of projected light. Here, the projector uses a holographic optical element to redirect the projected light for display to the wearer.

[0010] However, undesirable interference effects may occur during gaze direction recognition when redirecting the infrared light. These interference effects can be, for example, stray light, such as ambient light, or reflections of infrared light, such as reflections on the glasses of a wearer of a head-mounted display. This can result in the camera's image sensor being overexposed, making it impossible to reliably determine the gaze direction. Summary of the Invention

[0011] The object of the present invention is to further develop the above-described camera device in such a way that it can selectively detect only one or more predetermined objects in the environment and avoid interference effects on the obtained image.

[0012] This objective is achieved through the subject matter of the independent patent claims. Advantageous extensions of the invention are disclosed by the dependent patent claims, the following description, and the accompanying drawings.

[0013] This invention is based on the understanding that in a permanent or continuous lighting environment, illumination light is always reflected from multiple objects located in different object planes or cross-sectional planes of the environment. That is, illumination light is reflected back from different depth planes far from the camera device. Therefore, it is impossible to target the illumination and detection of individual objects within the environment. The object plane in this invention specifically refers to a plane in space, preferably parallel to the sensor plane orientation of the image sensor of the image detection device. Here, the environment to be detected by the camera device typically includes multiple such cross-sectional planes, arranged one after another at different distances from the camera device, as seen from the camera device. By now having the image detection device additionally and continuously detect the reflected illumination light from the environment, it typically results in an image of the environment being displayed on a large number of objects in different cross-sectional planes. The object of this invention is to provide illumination light in a targeted manner at one of these cross-sectional planes so as to illuminate and thus detect only objects located in the corresponding cross-sectional plane. Conversely, objects located in cross-sectional planes different from the desired cross-sectional plane should not be detected and should therefore be obscured or not displayed in the resulting image.

[0014] To achieve this, the aforementioned camera device further includes a control device configured to operate the lighting device and the image detection device in a predetermined switching operation manner. That is, the lighting device and the image detection device each have an on switching state and an off switching state. In the on or active state, the image detection device is configured to detect reflected illumination light. Conversely, in the off or deactivated state, it does not detect illumination light. Correspondingly, in the active or on state, the lighting device is configured to provide illumination light, while in the off or deactivated state, it does not provide illumination light. According to the switching operation, the control device is now configured to, for example, switch the image detection device and the lighting device from the on switching state to the off switching state according to a predetermined switching mode, and vice versa. The switching operation, i.e., the switching mode, can be set in particular by those skilled in the art. The switching operation can here be adjusted according to the distance between the cross-sectional plane and the camera device.

[0015] However, the switching operation described herein is selected such that the lighting device and the image detection device are sequentially switched to an on or active state, offset from each other in time, i.e., at time intervals, to provide illumination and to detect reflected illumination. In other words, the predetermined or fixed-defined lighting interval in which the lighting device provides illumination and the predetermined or fixed-defined shooting interval in which the image detection device detects reflected ambient light are offset from each other in time. The lighting interval and the shooting interval are preferably defined by a predetermined pause interval. The pause interval here represents the time period during which the lighting device and the image detection device simultaneously switch to a deactivated state. This means that either the object is illuminated or the reflected illumination is detected.

[0016] Thus, the lighting device can be said to provide illumination to the environment with defined illumination pulses, and the image detection device only detects the component of illumination light reflected back to the image detection device within the shooting interval. This process can also be called "gated imaging." The corresponding durations of the illumination interval and the shooting interval can be selected based on the distance from the object in the cross-sectional plane or the desired cross-sectional plane to the camera device.

[0017] This results in the advantage that only objects located in a predetermined cross-sectional plane are shown in the resulting image with predetermined brightness values ​​and / or in a highlighted manner. Conversely, the remaining environment, i.e., objects located in other cross-sectional planes, is obscured, i.e., not shown. This is particularly evident from time-constrained shooting windows or shooting intervals: obscuring or not showing objects located in cross-sectional planes different from the desired cross-sectional plane. In addition to time-coordinated shooting time, the inverse square law is also particularly useful for light attenuation. Thus, the aforementioned interference effects in the resulting image can also be avoided.

[0018] Preferably, the control device can also be configured to determine the distance to an illuminated object in the environment based on the duration or length of the pause interval. The control device can calculate the distance in a known manner based on a predetermined propagation speed of the illumination light in the light-conducting medium and the environment.

[0019] The invention also includes embodiments that provide additional advantages.

[0020] The aforementioned switching operation will now be described in more detail. In one embodiment of the invention, the control device in the gearbox is configured to extend or shorten the pause interval between the active state of the lighting device and the active state of the image detection device in each switching process, according to a predetermined switching criterion. Here, in particular, only the pause interval is extended or shortened, which is defined or set by the off time of the lighting device and the immediately following on time of the image detection device. Here, the switching process in the sense of the invention refers to a switching cycle, which includes: an lighting interval, followed by a pause interval and a final shooting interval.

[0021] By changing the pause interval, the object can thus be photographed at different cross-sectional planes and therefore at different distances from the camera device. By increasing the pause interval, the object can be photographed at increasingly farther distances from the camera device. Conversely, by shortening the pause interval, the object can be photographed at increasingly closer distances to the camera device. Therefore, it is possible to use the camera device to detect a large number or multiple images of the environment, in which objects located in different cross-sectional planes of the environment are shown respectively. In other words, the environment can be photographed in layers. For example, the resulting images can then be combined to form a 3D image of the environment.

[0022] According to the switching criteria, for example, the pause interval can be specified to change, for example, until a predetermined maximum limit is reached, i.e., the maximum duration of the pause interval, or until a predetermined minimum limit is reached, i.e., the minimum duration of the pause interval. Alternatively, the switching criteria can also be limited by a predetermined number of detected images.

[0023] To enable the image detection device to operate during switching operations, various modifications are disclosed below. In a modification of this invention, the image detection device includes a mechanically movable locking element for switching between an active (or image-taking / recording) state and a deactivated (or image-taking / recording) state. The locking element can also be referred to as a "shutter." For example, a control device can manipulate an electrically operable locking mechanism of the locking element such that the locking element is closed to deactivate the image detection device, and opened to activate the image detection device.

[0024] In another variation of the embodiments of the invention, the image detection device includes an electrically switchable layer, specifically configured as a film layer. This film layer is mounted in front of the image sensor when viewed from the light incident direction of the image detection device. To switch the image detection device, a control device is now configured to provide, for example, a predetermined voltage to the film layer. Depending on whether a voltage is applied to the film layer, the film layer can be switched to a transparent (transparent) or opaque (opaque) state. This prevents reflected illumination light from reaching the image sensor. The film layer can be configured, for example, as an OLED (organic light-emitting diode) or LCD film or an electrochromic film layer.

[0025] In another embodiment of the invention, the lighting device and the image detection device are arranged at a predetermined distance relative to each other in the transmission area of ​​the light guide medium formed by the second deflection element. The lighting device and the image detection device can preferably be directly attached to the light guide medium. Here, the first and second deflection elements are configured to compensate for the distance between the image detection device and the lighting device. Therefore, shadowing or darkening can be avoided when illumination light is emitted onto the object and reflected in the resulting image of the object. How precisely the distance compensation works will be described later in the context of the design of the first and second deflection elements.

[0026] The illumination light is preferably monochromatic. Correspondingly, in another embodiment of the invention, the lighting device includes a laser source to provide illumination light. Thus, high-energy, particularly narrow-bandwidth, laser-like illumination light can be provided by the lighting device. The laser source can be implemented, for example, by at least one semiconductor laser diode and / or a laser constructed in a known manner. Additionally or alternatively, the illumination light can also be provided by an LED light source having one or more light-emitting diodes (LEDs), each with or without a corresponding filter.

[0027] In another embodiment of the invention, the lighting device is configured to generate illumination light in the infrared frequency range. This means that the lighting device can particularly provide illumination light with wavelengths between 780 nanometers and 1 millimeter. Thus, the illumination light is particularly outside the human visible spectrum.

[0028] The configuration possibilities of the deflection elements are now described in more detail below. The deflection elements are therefore preferably constructed as diffractive optical elements (DOEs). In one embodiment of the invention, it is specifically specified that the first and second deflection elements are constructed as gratings, particularly surface holographic gratings (surface holograms) or volume holographic gratings (volume holograms).

[0029] Gratings, also known as diffraction gratings, and their operation and manufacturing methods are well known. In principle, a grating can be realized in a substrate by fabricating one or more structures that are at least periodically segmented, so-called grating structures or deflection structures. With the aid of such a grating structure, the grating can cause light redirection through the physical effect of diffraction, as is known for example by mirrors, lenses, or prisms. If light, i.e., a beam of light, strikes the grating, wherein the incident beam specifically satisfies Bragg's equations, the beam is diffracted or deflected by the grating. Therefore, light redirection can be achieved, in particular, through the interference phenomenon of the beam of light diffracted by the grating. The diffraction angle that causes the light to deflect or redirect is specifically set by the construction of the grating structure (grating characteristics), such as the grating spacing.

[0030] Gratings can be fabricated, for example, by exposure of a substrate, such as by photolithography or holography. In this regard, gratings can also be called holographic gratings or holographic gratings. Therefore, the deflecting element is constructed as a holographic optical element. Two types of holographic gratings are generally known: surface holographic gratings (SHG) and volume holographic gratings (VHG). In the case of surface holographic gratings, the grating structure can be generated by optically deforming the surface structure of the substrate. Examples of surface holographic gratings are so-called sawtooth or blazed gratings. Conversely, in the case of volume holographic gratings, the grating structure can be fabricated into the entire volume or a sub-region of the substrate.

[0031] Polymers or plastics, particularly photopolymers, or films, such as those made of plastic or organic materials, particularly photosensitive films, are particularly suitable as materials for the substrate used to fabricate gratings. Alternatively, glass can also be used as the substrate. Preferably, the photoconductive medium itself can be constructed as a substrate for fabricating the corresponding gratings. Thus, these deflection elements are integrally constructed with the photoconductive medium. Thus, the first and second deflection elements can be fabricated, for example, directly on the surface structure of the photoconductive medium. That is, the deflection structure can be etched or laser-cut into, for example, the surface or volume of the photoconductive medium. Thus, the photoconductive medium itself can be constructed as the aforementioned HOE. Alternatively, the photoconductive medium can also be constructed as elements separate from the first and second deflection elements. For example, the first and second deflection elements can be constructed in different sections of a holographic film or plate fixed to the photoconductive medium. For example, the film or plate can be bonded to the photoconductive medium for fixation. Alternatively, the holographic film can also be constructed as an adhesive film and can be directly, i.e., attached to the surface of the photoconductive medium by molecular forces without the use of adhesives.

[0032] Furthermore, the deflection element is preferably configured to be wavelength-selective or frequency-selective. Therefore, only light with a predetermined wavelength, particularly the first component of light, can be deflected or diffracted to a predetermined diffraction angle by the deflection element. Light with a length different from the predetermined length, particularly the second component of light, is preferably not deflected, or the greater the difference from the predetermined wavelength, the smaller the deflection. The second component of light deviating from the predetermined wavelength or optimal wavelength can therefore preferably propagate unimpeded through the substrate with the deflection element. Advantageously, the deflection effect is greatest with respect to the optimal wavelength and decreases, or becomes weaker, for example, depending on the Gaussian clock toward longer and shorter wavelengths. In the present case, the corresponding deflection element can therefore preferably be formed wavelength-selectively or frequency-selectively only with respect to the illumination light provided by the illumination device. Thus, for example, it can be prevented that light from the environment, such as the aforementioned interfering light, is completely input and coupled into the photoconductor medium and provided to the image detection device to generate an image.

[0033] Furthermore, the deflecting element is particularly preferably configured to be direction-selective or angle-selective. Direction selectivity here specifically relates to a predetermined diffraction angle, at which the corresponding deflecting element deflects the incident light from its incident direction. That is, the light incident on the deflecting element is deflected from its incident direction to a predetermined deflection direction. The angle formed between the incident direction and the deflection direction is called the diffraction angle. Advantageously, the deflection effect is greatest with respect to the predetermined deflection direction and decreases, or becomes weaker, for example, depending on the orientation of the Gaussian clock deviating from the deflection direction. Thus, it is also possible that the illuminating light slightly disperses when deflected by the deflecting element.

[0034] Additionally or alternatively, direction selectivity can also relate to the incident direction of light on the deflecting element. This means that only light, particularly light components, from a predetermined incident or optimal direction, such as at a predetermined incident angle on the corresponding deflecting element, can be deflected at a predetermined diffraction angle relative to the incident direction. Light, particularly light components, falling on the corresponding deflecting element from directions different from the optimal direction are preferably not deflected, or the greater the difference from the predetermined incident direction, the smaller the deflection. The light components deviating from the optimal direction can therefore preferably propagate unimpeded through the optical guide medium. Advantageously, this deflection effect is greatest with respect to the optimal direction and decreases, or becomes weaker, for example, depending on the angle of the Gaussian clock toward a sharper or blunter incident angle.

[0035] Advantageously, the deflecting elements may also each comprise more than one grating, such as two gratings, arranged adjacent to or stacked on top of each other. Thus, the corresponding deflecting elements have more than one deflection structure. Here, each deflection structure can be configured to be angle-selective with respect to different incident angles and / or wavelength-selective with respect to different wavelengths. This type of holographic grating is also called a multiplex volume holographic grating (MVHG).

[0036] In another embodiment of the present invention, the first and second deflection elements respectively include an input coupling deflection structure for coupling illumination light into the photoconductor medium and an output coupling deflection structure for coupling illumination light out of the photoconductor medium. Here, the input coupling deflection structure of the second deflection element and the output coupling deflection structure of the first deflection element are configured to deflect the illumination light at a predetermined first diffraction angle. The input coupling deflection structure of the first deflection element and the output coupling deflection structure of the second deflection element are configured to deflect the illumination light at a predetermined second diffraction angle different from the first diffraction angle. The illumination device is preferably arranged in the region of the input coupling deflection structure of the second deflection element. Conversely, the image detection device is preferably arranged in the region of the output coupling deflection structure of the second deflection element.

[0037] Therefore, as explained in more detail above, the deflection structure is constructed to be range-selective for different diffraction angles. The resulting advantage is that it avoids superposition or interference between the illumination light and the reflected illumination light as they propagate through the optical guide medium. Furthermore, it compensates for the aforementioned offset, i.e., the distance between the illumination device and the image detection device. This prevents the illumination device from casting shadows on the object.

[0038] Additionally or alternatively, advantageously, the environment can be segmented using a camera device. This means that different environmental areas, preferably non-overlapping environmental areas, can be detected by the camera device. For this purpose, in another embodiment of the invention, the image detection device includes an image sensor having at least two detection ranges, and the photoconductive medium has its own deflection range for each detection range. As described above, each deflection range here includes first and second deflection elements, respectively. Thus, each deflection range is configured to detect at least locally different environmental ranges. For this purpose, the corresponding deflection element of the first deflection range preferably includes, for example, a deflection structure different from that of the deflection element of the second deflection range.

[0039] If the camera device is used in a vehicle, such as a motor vehicle, then a first deflection range can be used to film the roadway, while a second deflection range can be used to monitor the adjacent sidewalk.

[0040] The present invention also relates to a headlight device for a motor vehicle, comprising a headlight light source and a camera device as described above. The camera device can therefore be preferably integrated into an existing headlight of a motor vehicle. Here, the light-guiding medium is preferably constructed to be transparent, that is, particularly constructed of a transparent material. Therefore, for example, a glass plate or a plastic plate can be used as the light-guiding medium. Here, the light-guiding medium is arranged in front of the headlight light source in the radiation direction of the headlight light source, such that the headlight light source is configured to provide headlight illumination by allowing light to pass between first and second object regions through the light-guiding medium. That is, the headlight of the motor vehicle can be used not only to illuminate the roadway but also to photograph objects in the vehicle's environment.

[0041] The motor vehicle is preferably constructed as a car, especially a passenger car or a truck, or as a passenger bus or a motorcycle.

[0042] The present invention also includes combinations of features of the embodiments described. Attached Figure Description

[0043] Embodiments of the present invention are described below. Therefore:

[0044] Figure 1 A schematic diagram of a cross-sectional image of a camera device from a side view is shown, which allows for the detection of only objects in the environment located in a predetermined object plane relative to the camera device;

[0045] Figure 2 A schematic diagram of two different camera devices is shown in the comparison. Detailed Implementation

[0046] The embodiments explained below are preferred embodiments of the present invention. In these embodiments, the components described represent individual features of the invention that should be considered independently of each other, and these features also independently extend the invention. Therefore, this disclosure is also intended to cover the features of these embodiments and the different combinations shown. Furthermore, the described embodiments may also be supplemented by further features of the invention already described.

[0047] In the figure, the same reference numerals represent elements with the same function.

[0048] Figure 1A schematic diagram of camera device 10 is shown. Here, camera device 10 is shown in cross-sectional view from a side perspective. Specifically, camera device 10 should only capture one or more objects in the environment U located in a predetermined object plane relative to camera device 10. Therefore, these objects can be shown in the resulting image. One or more objects located in an object plane different from the predetermined object plane should not be captured. Instead, these objects should not be shown in the resulting image. Here, the object plane refers to a corresponding plane in the environment that is arranged parallel to camera device 10 in the shooting direction.

[0049] Figure 1 illustrates two distinct objects, O1 and O2. The first object O1 is a person located on a first object plane E1 in the environment. The second object O2 is a tree located on a second object plane E2 in the environment. The first object plane E1, and therefore the first object O1, is closer to the camera device 10 than the second object plane E2 and the second object O2.

[0050] Now, in order to capture images of objects O1 and O2 based on their distance from the camera device 10, the camera device 10 includes a turning device 20, a lighting device 30, an image detection device 40, and a control device 50, wherein the distance is determined by the corresponding object planes E1 and E2.

[0051] The lighting device 30 is exemplarily constructed as a laser light source in this context. The function of the lighting device 30 is to provide illumination light 31, in this case, a laser beam, for illuminating desired objects O1 and O2. Figure 1 In the embodiments described, the image detection device 40 is configured as a camera or video camera. The image detection device 40 is configured to detect the reflected illumination light 41, i.e., a component of the provided illumination light 31, which is reflected back when the illumination light 31 is reflected from corresponding objects O1, O2. For this purpose, the image detection device 40 may, for example, have an image sensor, such as a CMOS sensor or a CCD sensor. It is capable of converting the detected illumination light 41 into a digital image signal in a known manner, wherein an image of the environment U is encoded by this digital image signal.

[0052] like Figure 1 As shown, the camera device 10 is configured as a "holographic camera". Therefore, the objects O1 and O2 to be photographed no longer need to be located on the same optical axis as the lighting device 30 and / or the image detection device 40. The lighting device 30 and the image detection device 40 can therefore be arranged perpendicular to the shooting direction of the camera device 10 and offset relative to the corresponding objects O1 and O2. This provides advantages, which will be discussed in more detail later, particularly when the camera device is mounted in a motor vehicle.

[0053] To achieve this deflection, the aforementioned deflection device 20 is provided. In the present case, the deflection device 20 includes a light-guiding medium 30 constructed as a glass plate or sheet for transmitting or transporting light via internal reflection. Two deflecting elements 21, 22 are spaced apart from each other in the longitudinal direction within the light-guiding medium 20. The function of the deflecting elements is to deflect the illumination light 31 provided by the illumination device 30 toward the environment and to deflect the illumination light 41 reflected from the environment toward the image detection device 40. Here, the deflection structure is preferably constructed to be frequency-selective with respect to the wavelength of the illumination light 31, 41. Therefore, only the illumination light 31, 41 is deflected by the deflecting elements. Conversely, ambient light falling on the deflection structures 21, 22 from the environment is not deflected, and in particular, can propagate through the light-guiding medium 20 without deflection.

[0054] Deflection elements 21 and 22 in Figure 1 The structure is configured as a holographic optical element, specifically as a multiplexed volume holographic grating (multi-volume hologram). That is, each of the deflection elements 21 and 22 includes two different deflection structures, namely input-coupled deflection structures 211 and 221 and output-coupled deflection structures 212 and 222, respectively.

[0055] To provide illumination light 31, the illumination device 30 is directly mounted on the first side of the light guide medium 23 within the area formed by the input coupling deflection structure 221 of the second deflection element 22. For example, the illumination device 30 can be bonded to the light guide medium. If the illumination light 31 now strikes the input coupling deflection structure 221, the illumination light 31 is deflected toward the first deflection element 21 at a diffraction angle determined by the grating characteristics of the deflection structure 221, and thus input coupled into the light guide medium 23. The light guide medium 31 then transmits the input coupled illumination light 31 to the output coupling deflection structure 212 of the first deflection element 21 by internal total internal reflection. Through the output coupling deflection structure 212, the illumination light 31 is now deflected into the environment U at a diffraction angle determined by the grating characteristics of the deflection structure 212 to illuminate the corresponding objects O1, O2 and thus output coupled from the light guide medium 23. If illumination light 31 subsequently strikes objects O1 and O2 in the environment U, then illumination light 31 or at least one component of illumination light is reflected and returned to the first deflecting element 21 in the form of reflected illumination light 41. If the reflected illumination light 41 then strikes the input coupling deflection structure 211 of the first deflecting element 21, the reflected illumination light 41 is deflected toward the second deflecting element 22 at a diffraction angle determined by the grating characteristics of the deflection structure 211, and thus input coupled into the photoconductor medium 23. The photoconductor medium 31 then transmits the input coupled reflected illumination light 41 to the output coupling deflection structure 222 of the second deflecting element 22 via internal total internal reflection. Through the output coupling deflection structure 222, the reflected illumination light 41 is finally deflected toward the image detection device 40 at a diffraction angle determined by the grating characteristics of the deflection structure 222, and thus output coupled from the photoconductor medium 23. To detect the reflected illumination light 41, the image detection device 40 is directly mounted on the first side of the photoconductor medium 23 within the area formed by the output coupling deflection structure 222 of the second deflection element 22. For example, the image detection device 40 can be bonded to the photoconductor medium. Figure 1 As shown, the lighting device 30 and the image detection device 40 are therefore arranged vertically on the longitudinal extension direction of the light guide medium 23 at a distance a from each other.

[0056] according to Figure 1 In the exemplary embodiment described herein, the aforementioned grating characteristics of the input coupling deflection structure 221 correspond here to the grating characteristics of the output coupling deflection structure 212. This is in Figure 1 In particular, they are represented by the same shading. Therefore, the corresponding diffraction angles of the illumination light 31 deflected by the input coupling deflection structure 221 and the output coupling deflection structure 212 are also consistent with each other. Similarly, the grating characteristics of the input coupling deflection structure 211 correspond to the grating characteristics of the output coupling deflection structure 222. This is in Figure 1In particular, the same shading is used to represent this. Therefore, the input coupling deflection structure 221 and the output coupling deflection structure 222 cause the corresponding diffraction angles of the reflected illumination light 41 to be consistent with each other. Therefore, compared to the input coupling deflection structure 211 and the output coupling deflection structure 222, the input coupling deflection structure 221 and the output coupling deflection structure 212 are direction-selective with respect to different diffraction angles. Figure 1 As shown, this allows the beam direction of the illumination light 31 within the light guide medium 23 to deviate from the beam direction of the reflected illumination light 41. Therefore, compared to the reflected illumination light 41, the illumination light 31 is totally reflected at different frequencies and at different positions on the corresponding interfaces of the light guide medium 23. This prevents overlap between the illumination light 31 and the reflected illumination light 41.

[0057] Finally, the aforementioned control device 50 is configured to detect only one predetermined object O1, O2 in the environment U, depending on the object plane. In the present case, the control device 50 is configured, for example, as a microcontroller. The control device 50 is now configured to operate the lighting device 30 and the image detection device at predetermined switching intervals. This means that the control device 50 can manipulate the lighting device 30 to emit illumination light 31 in one or more light pulses at predetermined illumination intervals. Furthermore, the control device 50 can also manipulate the image detection device 40 to detect the reflected illumination light 41 only within one or more predetermined shooting intervals, wherein these predetermined shooting intervals are respectively assigned to the previous illumination intervals. Figure 1 As shown, the image detection device includes an electrically switchable film layer 42 for switching purposes, which can be switched to a transparent or opaque state by the control device 50.

[0058] According to the switching operation, the corresponding lighting interval and the respectively assigned shooting interval are preferably performed sequentially in time. Therefore, a corresponding pause interval is set between the corresponding lighting interval and the assigned shooting interval. During the pause interval, neither the lighting device 30 for providing illumination light 31 nor the image detection device 40 for detecting the reflected illumination light 41 is activated.

[0059] By operating the lighting device 30 and the image detection device 40 during the switching operation, only the desired object planes E1 and E2 in the environment can be illuminated during the switching process, so that only the illumination light 41 reflected from the corresponding objects O1 and O2 located in the desired object planes E1 and E2 is captured. The switching process refers to a sequence consisting of exactly one illumination interval, followed by a pause interval and a final shooting interval. The switching operation may preferably include, in particular, one or more such switching processes.

[0060] Which object planes E1 and E2 in the environment U are illuminated and detected by the camera device 10 depends particularly on the characteristics of the switching operation. These characteristics include, in particular, the light intensity of the illumination light 31, the light guiding properties of the light guiding medium 23 and the environment U, the duration of the illumination interval and the shooting interval, and the duration of the allocated pause interval. For example, the lower the light intensity, the longer the duration of the illumination interval and the shooting interval must be selected in order to provide the image detection device 40 with a sufficiently strong reflected illumination light 41. The longer the duration of the pause interval, the farther away the objects O1 and O2 can be from the camera device 10. Conversely, the shorter the duration of the pause interval, the closer the objects O1 and O2 must be to the camera device 10.

[0061] Therefore, according to Figure 1 In the embodiments described, during the switching process, the camera device 10 can capture either a first object O1 or a second object O2 (in the corresponding image). Here, which object, O1 or O2, is captured depends on the selection of characteristics for the switching operation.

[0062] Conversely, if multiple switching processes are set according to the switching operation, a three-dimensional image of the environment U can also be generated, for example. For this purpose, the control device 50 is configured to extend or shorten the corresponding pause interval duration during the switching process relative to the pause interval duration of the previous switching process. Thus, as described above, the illumination light 41 reflected from different object planes E1, E2 can be detected. The corresponding images can then be combined into a three-dimensional image, for example, using the control device 50. Alternatively, a two-dimensional image can also be captured, on which multiple objects O1, O2 from different object planes E1, E2 are depicted.

[0063] The aforementioned camera device 10 can, for example, be installed in a motor vehicle. Here, the camera device 10 can be used for object recognition, such as to identify objects on the roadway, thereby enabling, for example, the execution of protective functions for the vehicle, such as emergency braking. To save installation space when arranging the camera device 10 in a motor vehicle, the camera device 10 can, for example, be integrated into the vehicle's headlights. Figure 1As shown, the camera device 10 can form a headlight device 60 with the headlight source 61. The light guiding medium 23 is particularly transparent, for example, constructed as a transparent glass plate or polymer plate. Here, the camera device 10 and the light guiding medium 23 are arranged in front of the headlight source 61 in the radiation direction of the headlight source 61. The headlight source is located between the first deflecting element 21 and the second deflecting element 22. Therefore, the headlight source 61 can provide headlight to the environment U without obstruction through the light guiding medium 23, for example, to illuminate the roadway for the driver. With the help of the camera device 10, it is preferable to be able to detect the roadway simultaneously in order to identify unwanted objects. Preferably, illumination light 31 with a wavelength in the infrared range is provided by the illumination device 30. Therefore, the environment U can be detected by the camera device 10 in a way that is invisible to the driver. Therefore, the driver's line of sight is not interfered with.

[0064] Finally, you can refer to it again. Figure 2 The advantages of the aforementioned steering unit 20 of the camera device 10 will be described in more detail. Figure 2 The illustration schematically shows the effect on the shooting characteristics of the camera device with and without the steering unit 20, depending on the object plane in the shooting environment.

[0065] Without the steering unit 20, that is, Figure 2 As shown in the upper figure, the aforementioned distance 'a' between the illumination device 30 and the image detection device 40 (due solely to structural space) cannot be compensated. As a result, the first beam component 311 of the illumination light 31 is reflected onto the object within the first object plane E1 and returns to the image detection device 40 as the reflected first beam component 411 of the illumination light 41. Conversely, the second beam portion 312 of the illumination light 31 is reflected onto the object within the second object plane E2 and returns to the image detection device 40 as the reflected second beam component 412 of the illumination light 41. Therefore, two or more beams of the reflected illumination light 41 reach the image detection device 40 from the emitted beam of the illumination light 31. Consequently, undesirable interference effects may occur on the resulting image. Interference effects may include, for example, overexposure and / or undesirable shadow projection.

[0066] This interference effect can be avoided by using the steering unit 20. Therefore, another function of the steering unit is to compensate for the offset between the lighting device 30 and the image detection device 40 caused by distance a. This function is particularly important in… Figure 2The following figure illustrates this schematically. In this case, the aforementioned directional selectivity of deflection structures 211, 212, 221, and 222 is utilized. As described above, in the case of directional selectivity, the incident light is deflected at a predetermined diffraction angle determined by the characteristics of the respective gratings. The diffraction angle is the angle between the incident beam and the associated deflected beam. However, deflection structures 211, 212, 221, and 222 are generally not ideal systems, thus producing a fan-shaped or conical beam instead of a deflected beam. The illumination light 31 and the reflected illumination light 41 therefore fan out within a predetermined cone angle or tilt angle during each input coupling and / or output coupling. The tilt angle is preferably less than 5°, particularly less than 1°. The offset between the illumination device 30 and the image detection device 40 can therefore be compensated for by this fan-shaped scattering of the light. Therefore, Figure 1 An idealized representation of illumination light 31 and reflected illumination light 41 as separate beams is shown.

[0067] The advantages of using the camera setup described above are summarized below. Firstly, shadows can be avoided in the resulting image because the illumination and shooting of the object are, to a certain extent, on the same optical axis (hereinafter also referred to as on-axis illumination). Furthermore, the precision of the illumination and / or shooting time windows or intervals is higher, as there are no unknown geometric path length variations in the (reflected) illumination light due to on-axis illumination. Otherwise, the offset between the illumination device and the image detection device would have an increasingly greater impact on the resulting image as the distance between the camera setup and the subject increases. Additionally, the use of HOE (Homo Equivalent of Angular Optical Spectroscopy) yields the following advantages: the desired wavelength of the illumination light can be narrower (smaller), thus allowing for better configuration (wavelength selectivity). Therefore, no additional filters are needed in the camera setup to filter wavelengths, saving cost and components, and thus eliminating additional interference effects (refraction and / or reflection). Similarly, due to the angular selectivity of HOE, a narrower angular range is also possible, allowing for better configuration of the angular range. This functionality is typically not emulated with classic optical components. Furthermore, the absence or negligible extension of the HOE allows for an exceptionally flat construction of the camera device, enabling smaller and / or lighter packages or housings. This is particularly important in the automotive manufacturing or automotive industry. By integrating the HOE into a transparent light guide that thus responds only to the wavelengths and / or angles specified by the HOE, the ultimate advantage is that the corresponding camera device can be installed in locations that would otherwise be impossible in automotive manufacturing, such as the headlight area.

[0068] Overall, these examples demonstrate how to provide a holographic camera for capturing images of objects located in an object plane defined relative to the holographic camera.

Claims

1. Camera device (10) for generating at least one image of at least one object in an environment, the camera device comprising: - a light guide medium (23) comprising a first deflection element (21) and a second deflection element (22) and being configured to transport light by internal reflection between the first and second deflection elements (21, 22); - an illumination device (30) configured to provide an illumination light (31) to the second deflection element (22) for illuminating an object in the environment, wherein the second deflection element (22) is configured to input couple the illumination light (31) into the light guide medium (23) for transport to the first deflection element (21) and the first deflection element (21) is configured such that the transported illumination light (31) is output coupled from the light guide medium (23) for illuminating the object; and - an image detection device (40) configured to detect a reflected illumination light (41) when the illumination light (31) is reflected on a respective object and to generate the at least one image, wherein for providing the reflected illumination light (41) to the image detection device (40) the first deflection element (21) is configured to input couple the reflected illumination light (41) into the light guide medium (23) for transport to the second deflection element (22) and the second deflection element (22) is configured such that the transported illumination light (41) is output coupled from the light guide medium (23) for transport to the image detection device (40), characterized by - a control device (50) configured to operate the illumination device (30) and the image detection device (40) in a predetermined switching operation, wherein the illumination device (30) and the image detection device (40) are in an activated state time-shifted to each other in the switching operation for providing the illumination light (31) and for detecting the reflected illumination light (41). The control device (50) is configured to prolong or shorten a pause interval between the activated state of the illumination device (30) and the activated state of the image detection device (40) in each switching process according to predetermined switching criteria in the switching operation.

2. The camera device (10) according to claim 1, wherein 3. Camera device (10) according to any one of the preceding claims, wherein the image detection device (40) comprises a mechanically movable shutter element and / or an electrically switchable film layer (42) for switching between an activated and a deactivated state. The illumination device (30) and the image detection device (40) are arranged in a predetermined distance to each other in a transport region of the light guide medium (23) formed by the second deflection element (22).

4. The camera device (10) according to claim 1 or 2, wherein The illumination device (30) comprises a laser source for providing the illumination light (31).

5. The camera device (10) according to claim 1 or 2, wherein The illumination device (30) is configured to generate the illumination light (31) in an infrared frequency range.

6. The camera device (10) according to claim 1 or 2, wherein ​ 7. The camera device (10) according to claim 1 or 2, wherein The first and second deflection elements (21, 22) are configured as gratings.

8. The camera device (10) according to claim 1 or 2, wherein The first and second deflection elements (21, 22) comprise an in-coupling deflection structure (211, 221) for in-coupling the illumination light (31, 41) into the light guide medium (23) and an out-coupling deflection structure (212, 222) for out-coupling the illumination light (31, 41) from the light guide medium (23), respectively, and The in-coupling deflection structure (221) of the second deflection element (22) and the out-coupling deflection structure (212) of the first deflection element (21) are configured to deflect the illumination light (31) with a predetermined first diffraction angle, and The in-coupling deflection structure (211) of the first deflection element (21) and the out-coupling deflection structure (222) of the second deflection element (22) are configured to deflect the reflected illumination light (41) with a predetermined second diffraction angle different from the first diffraction angle.

9. The camera device (10) according to claim 1 or 2, wherein The image detection device (40) comprises an image sensor having at least two detection ranges, and the light guide medium (23) has for each detection range its own deflection range comprising the first and second deflection elements (21, 22), wherein each deflection range is configured to detect at least a locally different environmental range of the environment.

10. The camera device (10) according to claim 7, wherein The first and second deflection elements (21, 22) are configured as surface holographic gratings or volume holographic gratings.

11. Headlamp arrangement (60) for a motor vehicle, comprising a headlamp light source (61) and a camera arrangement (10) according to any one of the preceding claims, wherein The light guide medium (23) is configured to be transparent and arranged in front of the headlamp light source (61) in the radiation direction of the headlamp light source, such that the headlamp light source (61) is configured to provide headlamp light through the light guide medium (23) between the first and second deflection elements (21, 22).

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