Camera device for generating an image of an environment and headlight arrangement

Abstract

Camera device (10) for producing at least one image of at least one object (O1, O2) in an environment (U), comprising: - a light-guiding medium (23) comprising a first deflection element (21) and a second deflection element (22) and configured to transmit light by means of internal reflection between the first and second deflection elements (21, 22), - a lighting device (30) configured to provide an illumination light (31) for illuminating the object (O1, O2) in the environment (U), an image acquisition device (40) configured to capture the reflected illumination light (41) upon reflection of the illumination light (31) at the respective object (O1, O2) and to generate at least one image, wherein, for the purpose of providing the reflected illumination light (41) to the image acquisition device (40), the first deflection element (21) is configured to couple the reflected illumination light (41) into the light-guiding medium (23) for transmission to the second deflection element (22), and the second deflection element (22) is configured to couple the transmitted illumination light (41) out of the light-guiding medium (23) for transmission to the image acquisition device (40),wherein the image acquisition device (40) is attached directly to a first side of the light guiding medium (23) within an area formed by a decoupling deflection structure (222) of the second deflection element (22), - a control device (50) configured to operate the lighting device (30) and the image acquisition device (40) in a predetermined switching operation, wherein the lighting device (30) and the image acquisition device (40) have an activated state for providing the illumination light (31) and for capturing the reflected illumination light (41) in the switching operation at different times from each other, characterized in that the lighting device (30) is configured to provide the illumination light (31) to the second deflection element (22), wherein the second deflection element (22) is configured to couple the illumination light (31) into the light-guiding medium (23) for transmission to the first deflection element (21), and the first deflection element (21) is configured to couple the transmitted illumination light (31) out of the light-guiding medium (23) for illumination of the object,wherein the illumination device (30) is attached directly to the first side of the light guiding medium (23) within an area formed by a coupling deflection structure (221) of the second deflection element (22), and that the first deflection element (21) and the second deflection element (22) are configured to compensate for a distance between the image acquisition device (40) and the illumination device (30).

Description

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

[0002] The invention relates in particular to capturing an image of a specific or desired object in its environment. For this purpose, the desired object is illuminated by a lighting device with a predetermined amount of light, which, upon reflection from the object, can be captured by an image capture device, such as a camera or video camera, using an image sensor. The image sensor can convert the incident light into an image signal in a known manner. The image signal can then be processed by a display device, such as a screen, to assemble or reconstruct the desired image of the object in its environment.

[0003] Preferably, the camera device is designed as a so-called "holocam". This means that holographic-optical elements (HOEs) are used to, on the one hand, transmit the illumination provided by the lighting device to the desired object and, on the other hand, to redirect the illumination reflected from the object to the image capture device. The image capture device and the lighting device therefore do not need to be located on the same optical axis as the object being recorded in the environment.

[0004] To realize the aforementioned "Holocam," the camera device comprises a light-guiding medium, which includes a first deflection element and a second deflection element. The light-guiding medium can, for example, be a plate or disc made of glass or plastic. The first and second deflection elements are preferably spaced apart from each other along a longitudinal axis of the light-guiding medium. The first and second deflection elements provide the deflection or light-guiding function of the camera device. That is, the first and second deflection elements are preferably implemented as diffractive optical elements and / or the aforementioned holographic-optical elements, for example, as volume holograms.The light-guiding medium is configured to transmit or forward light, coupled into it at a corresponding angle by means of the first and / or second deflection element, between the first and second deflection elements by means of internal reflection, in particular total internal reflection. The transmittable light is preferably the aforementioned illumination light. To provide the illumination light via the light-guiding medium for illuminating the object in its surroundings, the camera device thus also includes the illumination device, which is configured to provide the illumination light to the second deflection element. The second deflection element is then configured to couple the illumination light into the light-guiding medium for transmission to the first deflection element.The first deflection element is designed to extract the illumination light, transmitted via internal reflection within the light-guiding medium, from the light-guiding medium to illuminate the object. To generate the image of the respective object in its environment, the camera device also includes the aforementioned image acquisition device. To transmit the illumination light reflected from the object back to the image acquisition device, the first deflection element is designed, preferably to couple the reflected illumination light back into the light-guiding medium for transmission to the second deflection element.

[0005] Accordingly, the second deflection element is designed to decouple the illumination light, which is transmitted via internal reflection in the light-guiding medium, from the light-guiding medium for transmission to the image acquisition device.

[0006] The aforementioned deflection elements are thus designed for bidirectional deflection or redirection of the illumination light. This means that each deflection element can both couple the (reflected) illumination light into the light-guiding medium and couple the (reflected) illumination light out of the light-guiding medium.

[0007] An example of a "holocam" design is known from DE 10 2017 217 193 A1. In this design, the "holocam" is used as a so-called head-up display in a vehicle. A volume hologram, consisting of a holographic film with at least two optical elements for redirecting light, is arranged in a transparent section of a vehicle windshield. Light from the surroundings is coupled into the windshield via the optical elements and redirected towards a camera. The camera then generates an image signal from the incident light, which is sent to a projector. The projector uses the image signal to create a projection light. This projection light is then coupled into the windshield via the optical elements and subsequently projected onto the windshield for the driver to see an image of the surroundings.

[0008] Therefore, targeted illumination of the desired object in the surrounding area is not intended.

[0009] Instead of a holographic-optical element for redirecting light, a lens can also be used, as disclosed in US 2009 / 0153712 A1. The lens can, on the one hand, emit illumination from a lighting unit into the surroundings and, on the other hand, provide the reflected illumination from the surroundings to a camera. However, a disadvantage of such a lens is that its manufacture, especially the grinding of the lens, is usually complex.

[0010] Therefore, it is advantageous to use the aforementioned holographic-optical elements instead of a lens to redirect the illumination light. A corresponding system is known, for example, from US 2019 / 0086674 A1. This patent describes a head-mounted display that uses a "holocam" to display a desired image to the wearer of the head-mounted display, depending on the wearer's gaze direction. Appropriate holographic-optical elements are used to couple infrared light into and out of a light-guiding medium for gaze direction detection, thus delivering the light to the user's eye. The light reflected from the eye can then be coupled back into the light-guiding medium via the holographic-optical elements and out to a camera to determine the gaze direction.Depending on the viewing direction, a projector can be controlled, which generates a desired display image in the form of projected light. The projector uses holographic-optical elements to redirect this projected light onto the surface for display.

[0011] However, this process can lead to undesirable interference when redirecting the infrared light during gaze direction detection. This interference can be caused by sources such as ambient light or reflections of the infrared light, for example, from the glasses worn by the user of the head-mounted display. This can result in overexposure of the camera's image sensor, making reliable gaze direction determination impossible.

[0012] DE 603 ​​19 238 T2 relates to a night vision imaging system and method for installation in a vehicle. Fig. Figure 3A of this publication shows a system configuration in which the display device is located in a HUD configuration. In this specific configuration, the display is installed in the central part of the vehicle's front window. An image intensifier, which may be integrated into a camera, can be positioned near the display device and functionally connected to it, or it can be integrated into the display device. It is explained that, for example, a flat-optics technology based on holography can be used for this configuration. This enables the image to be transmitted from the image intensifier to the HUD without the need for a CCD / CMOS camera. In the configuration described in Fig. In the configuration shown in Figure 3A of this printed document, the image intensifier is directly connected to the flat optics and transmits an image to a selected location, for example, in front of the driver's field of vision, using holograms. The image intensifier can be installed anywhere in the front of the vehicle. The light source, on the other hand, is installed in the upper interior of the vehicle, near the rearview mirror. It is also possible to install the light source at any other suitable location in or on the vehicle, for example, in the headlights, grille, side mirrors, or elsewhere, and to guide the light to the front of the vehicle via an optical fiber, where the light beam can be emitted.

[0013] US Patent 2012 / 0249797 A1 relates to an interactive head-mounted eyepiece with an integrated processor for processing content for display and an integrated image source for introducing the content into an optical assembly through which the user views their surroundings and the displayed content. The optical assembly includes absorbing polarizers or anti-reflective coatings to reduce stray light. Fig. Figure 4 of this publication shows an arrangement in which image light is coupled into a waveguide.

[0014] US Patent 2017 / 0115395 A1 concerns an active or passive gated sensor imaging system with a minimized time interval between successive sensor exposures. In the active imaging system, a light source emits light pulses toward an area of ​​interest, and an image sensor receives reflections of these pulses from objects located at a depth of field (DOF) to be imaged and converts these reflections into an image. Each full frame of the image contains a multitude of gate cycles. Each gating cycle involves the emission of a particular light pulse and the reception of reflections of that pulse. A delay time is defined as the duration between the sensor exposure periods of successive gate cycles.A controller manages the operation of the light source and the image sensor to minimize the delay time for at least one gating cycle of an image, with the delay time being adaptively determined in accordance with at least one system parameter or environmental condition.

[0015] The object of the present invention is to further develop the camera device described above in such a way that only one or more predetermined objects in the environment are selectively detected and interference effects on the resulting image are avoided.

[0016] The problem is solved by the subject matter of the independent patent claims. Advantageous embodiments of the invention are disclosed by the dependent patent claims, the following description, and the figures.

[0017] The invention is based on the understanding that with continuous or permanent illumination of the environment, the light is always reflected by several objects located in different object planes or cross-sectional planes of the environment. This means that the light is reflected from depth planes at varying distances from the camera device. Targeted illumination and capture of a single object in the environment is therefore not possible. For the purposes of this invention, an object plane refers in particular to a plane in space, preferably aligned parallel to a sensor plane of an image sensor of the image capture device. The environment to be captured by the camera device typically comprises several such cross-sectional planes, arranged sequentially at different distances from the camera device.By also continuously capturing the reflected ambient light, the image capture device typically produces an image of the environment on which a multitude of objects are depicted in different sectional planes. The aim of the invention is to selectively direct the illumination light to each of these sectional planes in order to illuminate and thus capture only the object located within that plane. Objects located in planes other than the desired sectional plane should not be captured and are therefore either hidden or not displayed in the resulting image.

[0018] To achieve this, the camera device described above is additionally designed to include a control unit configured to operate the illumination device and the image acquisition device in a predetermined switching mode. This means that the illumination device and the image acquisition device each have an on / off switching state and an off switching state. In the on / off or activated state, the image acquisition device is configured to capture the reflected illumination light. In the off / deactivated state, however, no illumination light is captured. Similarly, the illumination device is configured to provide illumination light in the activated or on state, while in the off / deactivated state, the illumination device does not provide illumination light.According to the switching operation, the control device is now configured to switch the image acquisition device and the lighting device, for example according to a predetermined switching pattern, from the switched-on state to the switched-off state and vice versa. The switching operation, that is, the switching pattern, can be defined, in particular, by a person skilled in the art. The switching operation can be adjusted depending on the distance of the cutting plane to the camera device.

[0019] The switching operation is configured such that the lighting device and the image acquisition device are switched on or activated in a time-shifted manner, specifically sequentially and with a time interval between them, to provide the illumination light and to capture the reflected illumination light. In other words, a predetermined or fixed illumination interval, during which the lighting device provides the illumination light, and a predetermined or fixed-definition recording interval, during which the image acquisition device captures the reflected ambient light, are temporally offset from each other. The illumination and recording intervals are preferably separated by a predetermined pause interval.The pause interval represents a period during which both the lighting system and the image capture system are simultaneously switched to a deactivated state. This means that either the object is illuminated or the reflected light is captured.

[0020] In this way, the lighting device provides the ambient light in defined pulses, and the image capture device only records the portion of the light reflected back to it within the recording interval. This process can also be described as "gated imaging." The duration of both the lighting and recording intervals can be selected depending on the distance between the scanning plane, or the object in the desired scanning plane, and the camera.

[0021] This offers the advantage that only an object located in the predetermined section plane is displayed in the resulting image with a predetermined brightness value and / or highlighted. The rest of the surroundings, i.e., objects located in other section planes, are hidden, meaning they are not displayed. The fact that objects located in other sections are hidden or not displayed is primarily due to the time-limited recording window or interval. In addition to the precisely timed recording, the inverse square law regarding light decay is particularly helpful. This also prevents the aforementioned artifacts from appearing in the resulting image.

[0022] Preferably, the control device can also be configured to determine the distance of the imaged object in its surroundings based on the duration or length of the pause interval. The control device can calculate this distance in a known manner as a function of a predetermined propagation speed of the illumination light in the light-guiding medium and the surroundings.

[0023] The invention also includes embodiments that offer additional advantages.

[0024] The aforementioned switching operation will now be described in more detail. In one embodiment of the invention, the control device is configured in switching mode to lengthen or shorten the pause interval between the activated state of the lighting device and the activated state of the image acquisition device according to a predetermined switching criterion with each switching operation. Specifically, only those pause intervals are lengthened or shortened that are limited or defined by the switch-off time of the lighting device and the immediately subsequent switch-on time of the image acquisition device. For the purposes of this invention, a switching operation is defined as a switching cycle comprising a lighting interval followed by a pause interval and a final image acquisition interval.

[0025] By changing the pause interval, objects in different planes, and therefore at different distances from the camera, can be captured. Increasing the pause interval allows objects at increasingly greater distances from the camera to be captured, while decreasing it allows objects at increasingly closer distances. Thus, the camera can capture multiple images of the environment, each depicting an object located in a different plane. This creates a layered representation of the environment. The resulting images can then be combined, for example, to create a three-dimensional model of the environment.

[0026] The switching criterion can, for example, stipulate that the pause interval is changed until a predetermined maximum limit is reached (i.e., a maximum duration of the pause interval) or until a predetermined minimum limit is reached (i.e., a minimum duration of the pause interval). Alternatively, the switching criterion can also be limited by a predetermined number of captured images.

[0027] To enable the image acquisition device to operate in switching mode, various variants are disclosed below. In one variant of an embodiment of the invention, the image acquisition device comprises a mechanically movable shutter element for switching between the activated or recording state and the deactivated or non-recording state. The shutter element can also be referred to as a "shutter." The control device can, for example, actuate an electrically controlled shutter mechanism of the shutter element, such that the shutter element closes to deactivate the image acquisition device and opens to activate the image acquisition device.

[0028] In a further embodiment of the invention, the image acquisition device comprises an electrically switchable layer, which is preferably designed as a film layer. This layer is positioned in front of the image sensor, facing the direction of light incidence from the image acquisition device. To switch the image acquisition device, the control device is configured, for example, to supply a predetermined electrical voltage to the film layer. Depending on whether the electrical voltage is applied to the film layer or not, the film layer can be switched to either a transparent (transmitting light) or opaque (not transmissive light) state. This prevents the reflected illumination light from striking the image sensor. The film layer can, for example, be designed as an OLED (Organic Light Emitting Diode), an LCD film, or an electrochromic film layer.

[0029] In a further embodiment of the invention, the illumination device and the image acquisition device are arranged at a predetermined distance from each other within a transmission area of ​​the light-guiding medium formed by the second deflection element. Preferably, the illumination device and the image acquisition device can be in direct contact with the light-guiding medium. The first and second deflection elements are designed to compensate for the distance between the image acquisition device and the illumination device. This prevents shadowing or shading when the illumination light is emitted to the object and reflected from the object in the resulting image. The precise mechanism for compensating for this distance will be described in more detail later in connection with the design of the first and second deflection elements.

[0030] Preferably, the illumination light is monochromatic. In a further embodiment of the invention, the illumination device comprises a laser light source for providing the illumination light. This allows the illumination device to provide, in particular, high-energy and especially narrowband illumination light in the form of laser light. The laser light source can be implemented, for example, by at least one semiconductor laser diode and / or a laser of a known design. Additionally or alternatively, the illumination light can also be provided by an LED light source with one or more light-emitting diodes (LEDs), each with or without a corresponding light filter.

[0031] In a further embodiment of the invention, the lighting device is configured to generate illumination in the infrared frequency range. This means that the lighting device can, in particular, provide illumination with a wavelength between 780 nanometers and one millimeter. As a result, the illumination is located, in particular, outside the visible light spectrum.

[0032] The following section describes possible configurations of the deflection elements in more detail. Preferably, the deflection elements are configured as diffractive optical elements (DOEs). In one embodiment of the invention, it is particularly provided that the first and second deflection elements are configured as optical gratings, especially as holographic surface gratings (surface hologram) or holographic volume gratings (volume hologram).

[0033] An optical grating, also called a diffraction grating, as well as its operating principle and manufacturing process, are generally known. In principle, an optical grating can be realized by incorporating one or more at least partially periodic structures, so-called grating structures or deflection structures, into a substrate. Through the grating structure, the optical grating can achieve light deflection, similar to that achieved by mirrors, lenses, or prisms, via the physical effect of diffraction. When light, that is, light rays, fall upon the optical grating, and these incident light rays, in particular, satisfy the Bragg equation, the light rays are diffracted or deflected by the optical grating. Light deflection can thus occur, in particular, through interference phenomena of the light rays diffracted by the optical grating.The diffraction angle, in which the light is deflected or redirected, is determined in particular by the design of the grating structure (grating properties), such as grating spacing.

[0034] The optical grating can be fabricated, in particular, by exposing the substrate, for example, photolithography or holography. In this context, the optical grating can then also be referred to as a holographic or holographic-optical grating. Thus, the deflection elements are designed as holographic-optical elements. Two types of holographic-optical gratings are generally known: surface holographic gratings (SHGs) and volume holographic gratings (VHGs). In surface holographic gratings, the grating structure can be created by optically deforming a surface structure of the substrate. Examples of surface holographic gratings are so-called sawtooth or blaze gratings. In contrast, the grating structure of volume holographic gratings can be incorporated into the entire volume or a portion of the volume of the substrate.

[0035] Suitable materials for the substrate used to incorporate the optical grating include a polymer or plastic, especially a photopolymer, or a film, particularly a photosensitive film, for example, made of plastic or organic materials. Alternatively, glass can also be used as the substrate. Preferably, the optical medium itself can serve as the substrate for incorporating the respective optical grating. Thus, the deflection elements are integrally formed with the optical medium. The first and second deflection elements can, for example, be directly incorporated into a surface structure of the optical medium. That is, the deflection structure can, for example, be etched or laser-etched into the surface or a volume of the optical medium. Therefore, the optical medium itself can be designed as the aforementioned optical element.Alternatively, the optical fiber can also be designed as a separate element from the first and second deflection elements. For example, the first and second deflection elements can be formed in different sections of a holographic film or plate, which is attached to the optical fiber. The film or plate can be glued to the optical fiber, for instance. Alternatively, the holographic film can also be designed as an adhesive film and adhere directly to the surface of the optical fiber by molecular forces, without the need for adhesive.

[0036] Preferably, the deflection elements are also wavelength-selective or frequency-selective. Thus, only light, in particular a first component of the light, with a predetermined wavelength can be deflected or diffracted by the deflection element to a predetermined diffraction angle. Light, in particular a second component of the light, with a wavelength other than the predetermined one, is preferably not deflected, or the deflection decreases the greater the difference from the predetermined wavelength. The second component of light, which deviates from the predetermined wavelength or optimal wavelength, can therefore preferably propagate unhindered through the substrate containing the deflection element. Advantageously, this deflection effect is maximal for the optimal wavelength and decreases or weakens towards longer and shorter wavelengths, for example according to a Gaussian curve.In this case, the respective deflection element can therefore preferably be designed to be wavelength-selective or frequency-selective only with respect to the illumination light provided by the lighting device. This prevents, for example, ambient light, such as the aforementioned stray light, from being coupled into the light-guiding medium and supplied to the image acquisition device for generating the image.

[0037] Particularly preferably, the deflecting elements are designed to be direction-selective or angle-selective. Directional selectivity refers specifically to a predetermined diffraction angle at which the respective deflecting element deflects the incident light away from its direction of incidence. That is, the light striking the deflecting element is deflected from its direction of incidence into a predetermined direction. The angle that arises between the direction of incidence and the direction of deflection is called the diffraction angle. Advantageously, this deflection effect is maximal for the predetermined direction of deflection and decreases or weakens for other directions of deflection, for example, according to a Gaussian curve. This can also result in a slight dispersion of the illuminated light when deflected by the deflecting elements.

[0038] Additionally or alternatively, the directional selectivity can also refer to the direction of incidence of the light on the deflecting element. That is, only light, and in particular a portion of the light, that falls on the respective deflecting element from a predetermined direction of incidence or optimal direction (i.e., at a predetermined angle of incidence) can be deflected at a diffraction angle predetermined relative to that direction of incidence. Light, and in particular a portion of the light, that falls on the respective deflecting element from a direction other than the optimal direction is preferably not deflected, or the deflection decreases the greater the difference from the predetermined direction of incidence. Consequently, the portion of light that deviates from the optimal direction can preferably propagate unhindered through the light-guiding medium.Advantageously, this deflection effect is maximal for the optimal direction and decreases or weakens towards sharper or more obtuse angles of incidence, for example according to a Gaussian bell curve.

[0039] Advantageously, the deflection elements can each comprise more than one optical grating, for example, two optical gratings arranged side by side or stacked. Thus, each deflection element has more than one deflection structure. Each of the deflection structures can be angle-selective with respect to a different angle of incidence and / or wavelength-selective with respect to a different wavelength. This type of holographic grating is also known as a multiple volume holographic grating (MVHG).

[0040] In a further embodiment of the invention, the first and second deflection elements each comprise an inducing deflection structure for coupling the illumination light into the light-guiding medium and an outducing deflection structure for decoupling the illumination light from the light-guiding medium. The inducing deflection structure of the second deflection element and the outducing deflection structure of the first deflection element are configured to deflect the illumination light at a predetermined first diffraction angle. Conversely, the inducing deflection structure of the first deflection element and the outducing deflection structure of the second deflection element are configured to deflect the illumination light at a predetermined second diffraction angle that differs from the first diffraction angle. The illumination device is preferably arranged in the region of the inducing deflection structure of the second deflection element.The image acquisition device, on the other hand, is preferably arranged in the area of ​​the decoupling deflection structure of the second deflection element.

[0041] As previously explained, the deflection structures are thus designed to be directionally selective with respect to different diffraction angles. This offers the advantage that superposition or interference of the illumination light and the reflected illumination light during transmission in the light-guiding medium can be avoided. Furthermore, it also compensates for the aforementioned offset, i.e., the distance between the illumination device and the image acquisition device. Therefore, shadows cast by the illumination device onto the object can be avoided.

[0042] Advantageously, or alternatively, a segmented recording of the environment using the camera device is also possible. That is, different environmental areas, preferably non-overlapping environmental areas, can be captured using a single camera device. In a further embodiment of the invention, the image acquisition device comprises an image sensor with at least two detection areas, and the light guide medium has a separate deflection area for each of the detection areas. Each of the deflection areas comprises, as described above, the first and second deflection elements. Thus, each of the deflection areas is configured to capture an environmental area that is at least partially different. For this purpose, the respective deflection elements of a first deflection area preferably comprise different deflection structures than, for example, the deflection elements of a second deflection area.

[0043] If the camera device is used in a vehicle, such as a motor vehicle, the first deflection area can be used to record a roadway, while a second deflection area can simultaneously monitor an adjacent pedestrian walkway.

[0044] The invention also relates to a headlight assembly for a motor vehicle comprising a headlight light source and the camera device as previously described. The camera device can thus preferably be integrated into an existing headlight of the motor vehicle. The light-guiding medium is preferably transparent, i.e., made of a transparent material. For example, a glass plate or a plastic plate can serve as the light-guiding medium. The light-guiding medium is arranged in front of the headlight light source in the direction of radiation such that the headlight light source is configured to provide a headlight beam through the light through the light-guiding medium between the first and second object areas. This means that the headlight of the motor vehicle can be used both to illuminate the road and to record objects in the vicinity of the vehicle.

[0045] The motor vehicle is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus or motorcycle.

[0046] The invention also includes combinations of the features of the described embodiments.

[0047] The following are exemplary embodiments of the invention described. This is illustrated by: Fig. 1. A schematic representation of a cross-sectional image from a side perspective of a camera device, by means of which only one object in an environment, which is located in a predetermined object plane to the camera device, can be captured; and Fig. 2 A schematic representation of two different camera devices in comparison.

[0048] The exemplary embodiments described below are preferred embodiments of the invention. In these exemplary embodiments, the described components each represent individual features of the invention, which can be considered independently of one another and each further develops the invention independently. Therefore, the disclosure is intended to include combinations of features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0049] In the figures, identical reference symbols denote functionally equivalent elements.

[0050] Fig. Figure 1 shows a schematic representation of a camera device 10. The camera device 10 is shown in a sectional view from a side perspective. The camera device 10 is intended to capture only one or more objects in the environment U that are located in a predetermined object plane relative to the camera device 10. These objects can thus be represented in a resulting image. Objects located in a plane other than the predetermined object plane are not to be captured. These objects are not represented in the resulting image. The object plane refers to a plane in the environment that is parallel to the camera device in the camera's field of view.

[0051] In Fig. Figure 1 shows two different objects, O1 and O2, as examples. The first object, O1, is a person located in the first object plane, E1, in the environment. The second object, O2, is a tree located in the second object plane, E2, in the environment. The first object plane, E1, and therefore also the first object, O1, are closer to the camera device, E1, than the second object plane, E2, and the second object, O2.

[0052] In order to be able to record the objects O1, O2 depending on their distance from the camera device 10, which is determined by the respective object plane E1, E2, the camera device 10 comprises a deflection device 20, a lighting device 30, an image acquisition device 40 and a control device 50.

[0053] The lighting device 30 is, in this example, configured as a laser light source. The function of the lighting device 30 is to provide an illuminating light 31, in this case a laser light beam, for illuminating the desired object O1, O2. The image acquisition device 40 is, according to the exemplary embodiment, Fig. 1. The image acquisition device 40 is configured as a still camera or video camera. It is designed to capture reflected illumination 41, i.e., a portion of the supplied illumination 31 that is reflected back from the respective object O1, O2. For this purpose, the image acquisition device 40 can, for example, include an image sensor, such as a CMOS sensor or a CCD sensor. This sensor can convert the captured illumination 41 into a digital image signal in a known manner, by which the image of the environment U is encoded.

[0054] As in Fig. As shown in Figure 1, the camera device 10 is designed as a "holocam". This means that the object O1, O2 to be recorded no longer needs to be on the same optical axis as the illumination device 30 and / or the image acquisition device 40. The illumination device 30 and the image acquisition device 40 can therefore be arranged perpendicular to the recording direction of the camera device 10 and offset from the respective object O1, O2. This offers advantages, particularly when installing the camera device in a motor vehicle, which will be discussed in more detail later.

[0055] To achieve this offset, the aforementioned deflection device 20 is provided. In this case, the deflection device 20 comprises a light-guiding medium 30, designed as a glass plate or glass disc, for guiding or transmitting light by means of internal reflection. Two deflection elements 21, 22 are incorporated into the light-guiding medium 20 at intervals along a longitudinal direction. The function of the deflection elements is to deflect the illumination 31 provided by the illumination device 30 to the surroundings and to deflect the reflected illumination 41 from the surroundings to the image acquisition device 40. Preferably, the deflection structures are designed to be frequency-selective for a specific wavelength of the illumination 31, 41. Thus, only the illumination 31, 41 is deflected by the deflection elements.Ambient light falling from the environment U onto the deflection structures 21, 22, however, is not deflected and can propagate through the light-guiding medium 20 without deflection.

[0056] The deflection elements 21, 22 are in Fig. 1 are designed as holographic-optical elements, in particular as holographic multi-volume gratings (multi-volume holograms). That is, each of the deflection elements 21, 22 comprises two different deflection structures, namely an input deflection structure 211, 221 and an output deflection structure 212, 222.

[0057] To provide the illumination light 31, the illumination device 30 is attached directly to a first side of the light-guiding medium 23 within a region formed by the coupling deflection structure 221 of the second deflection element 22. For example, the illumination device 30 can be glued to the light-guiding medium. When the illumination light 31 strikes the coupling deflection structure 221, it is deflected at a diffraction angle determined by a grating property of the deflection structure 221 in the direction of the first deflection element 21 and is thereby coupled into the light-guiding medium 23. The light-guiding medium 31 then transmits the coupled illumination light 31 to the coupling deflection structure 212 of the first deflection element 21 by means of total internal reflection.By means of the outgoing deflection structure 212, the illumination light 31 is deflected into the surroundings U to illuminate the respective object O1, O2 at a diffraction angle determined by a grating property of the deflection structure 212, and thus coupled out of the light-guiding medium 23. When the illumination light 31 then encounters an object O1, O2 in the surroundings U, the illumination light 31, or at least a portion of it, is reflected and returned to the first deflection element 21 in the form of reflected illumination light 41. If the reflected illumination light 41 then encounters the incoming deflection structure 211 of the first deflection element 21, the reflected illumination light 41 is deflected at a diffraction angle determined by a grating property of the deflection structure 211 towards the second deflection element 22 and thereby coupled into the light-guiding medium 23.The light-guiding medium 31 transmits the coupled reflected illumination light 41 to the decoupling deflection structure 222 of the second deflection element 22 by means of total internal reflection. By means of the decoupling deflection structure 222, the reflected illumination light 41 is finally deflected at a diffraction angle determined by a grating property of the deflection structure 222 towards the image acquisition device 40 and thus coupled out of the light-guiding medium 23. To capture the reflected illumination light 41, the image acquisition device 40 is attached directly to the first side of the light-guiding medium 23 within a region formed by the decoupling deflection structure 222 of the second deflection element 22. For example, the image acquisition device 40 can be glued to the light-guiding medium. As in . Fig. As shown in Figure 1, the lighting device 30 and the image capture device 40 are arranged one above the other at a distance a from each other in the longitudinal direction of the light guiding medium 23.

[0058] According to the in Fig. In the embodiment described in point 1, the aforementioned lattice property of the coupling deflection structure 221 corresponds to the lattice property of the coupling deflection structure 212. This is in Fig. 1 is symbolized in particular by the identical hatching. Thus, the respective diffraction angles at which the coupling deflection structure 221 and the coupling deflection structure 212 deflect the illumination light 31 also correspond. Analogously, the grating property of the coupling deflection structure 211 corresponds to the grating property of the coupling deflection structure 222. This is shown in Fig. 1 is symbolized in particular by the identical hatching. Thus, the respective diffraction angles at which the coupling deflection structure 211 and the coupling deflection structure 222 deflect the reflected illumination light 41 also coincide. Consequently, the coupling deflection structure 221 and the coupling deflection structure 212 are directionally selective with respect to different diffraction angles compared to the coupling deflection structure 211 and the coupling deflection structure 222. As in Fig. As shown in Figure 1, it can thus be achieved that the path of the illumination light 31 within the light-guiding medium 23 differs from the path of the reflected illumination light 41. The illumination light 31 is therefore totally reflected a different number of times and at different locations at each interface of the light-guiding medium 23 compared to the reflected illumination light 41. This prevents the illumination light 31 and the reflected illumination light 41 from overlapping.

[0059] Finally, the aforementioned control device 50 is provided for the object-plane-dependent detection of only one predetermined object O1, O2 in the environment U. In this example, the control device 50 is designed as a microcontroller. The control device 50 is configured to operate the lighting device 30 and the image acquisition device in a predetermined switching mode. That is, the control device 50 can control the lighting device 30 to emit the illumination light 31 in one or more light pulses, each with a predetermined illumination interval. Furthermore, the control device 50 can also control the image acquisition device 40 to detect the reflected illumination light 41 only within one or more predetermined recording intervals, each of which is assigned to a preceding illumination interval. As in Fig. As shown in Figure 1, the image acquisition device for switching comprises an electrically switchable film layer 42, which can be switched to a transparent or opaque state by means of the control device 50.

[0060] According to the switching operation, each illumination interval and its associated recording interval preferably occur sequentially. Thus, a pause interval is provided between each illumination interval and its associated recording interval. During this pause interval, neither the illumination device 30 (for providing the illumination light 31) nor the image acquisition device 40 (for capturing the reflected illumination light 41) is activated.

[0061] By operating the lighting device 30 and the image acquisition device 40 in switching mode, only the desired object plane E1, E2 in the surrounding area can be illuminated during a switching operation, so that only the illumination light 41 reflected from the respective object O1, O2 located in the desired object plane E1, E2 is recorded. A switching operation is defined as a sequence of exactly one illumination interval, followed by a pause interval and a final recording interval. Preferably, the switching operation can comprise one or more such switching operations.

[0062] Which object plane E1, E2 in the environment U is illuminated and captured by the camera device 10 depends in particular on the characteristics of the switching operation. These characteristics include, among others, 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 recording interval, and the duration of the associated pause interval. The lower the light intensity, the longer, for example, the duration of the illumination interval and the recording interval must be to provide reflected illumination light 41 with sufficient intensity to the image capture device 40. The longer the duration of the pause interval, the further away an object O1, O2 can be from the camera device 10.Conversely, the shorter the duration of the pause interval, the closer the object O1, O2 must be to the camera device 10.

[0063] Thus, according to the exemplary embodiment in Fig. 1. Using the camera device 10, either the first object O1 or the second object O2 can be recorded (in a respective image) during a switching operation. Which of the objects O1 or O2 is recorded depends on the selected properties of the switching operation.

[0064] If, however, several switching operations are planned according to the switching operation, a three-dimensional image of the environment U can also be generated. For this purpose, the control device 50 is designed to lengthen or shorten the respective pause interval duration in a switching operation relative to the pause interval duration of a preceding switching operation. This allows the reflected illumination light 41 from different object planes E1, E2 to be detected, as described above. The resulting images can then be combined, for example, by means of the control device 50 to form the three-dimensional image. Alternatively, it would of course also be possible to capture a two-dimensional image on which several objects O1, O2 from different object planes E1, E2 are depicted.

[0065] The camera device 10 described above can, for example, be installed in a motor vehicle. The camera device 10 can be used, for instance, for object detection to identify objects on the road, enabling the vehicle to perform protective functions such as emergency braking. To save installation space when arranging the camera device 10 in the motor vehicle, it can, for example, be integrated into a headlight. The camera device 10 can be connected to a headlight light source 61, as shown in Fig. Figure 1 shows a headlight arrangement 60. The light-guiding medium 23 is preferably transparent, for example, as a transparent glass plate or polymer plate. The camera device 10 is arranged with the light-guiding medium 23 in the direction of emission from the headlight light source 61 and in front of the headlight light source 61. The headlight light source is located preferably between the first deflection element 21 and the second deflection element 22. Thus, the headlight light source 61 can provide the headlight light unhindered through the light-guiding medium 23 to the surroundings U, for example, to illuminate the roadway for a driver. Preferably, the roadway can be simultaneously recorded by means of the camera device 10 to detect unwanted objects. Preferably, the illumination light 31 with a wavelength in the infrared range is provided by means of the lighting device 30.Thus, the recording of the surroundings U by means of the camera device 10 can be carried out invisibly to the driver. The driver's view is therefore not obstructed.

[0066] Based on Fig. 2 Finally, one advantage of the aforementioned deflection unit 20 of the camera device 10 can be described in more detail. Fig. Figure 2 schematically shows an effect on the recording properties of a camera device for object plane-dependent recording of objects in an environment, with and without the deflection unit 20.

[0067] Without the deflection unit 20, as shown in the upper illustration in Fig. As shown in Figure 2, the aforementioned distance a, which the lighting device 30 and the image acquisition device 40 have from each other (due to space constraints alone), is not compensated for. As a result, a first component 311 of the illumination light 31 would be reflected by an object in the first object plane E1 and reflected back to the image acquisition device 40 as the first component 411 of the reflected illumination light 41. Conversely, a second component 312 of the illumination light 31 would be reflected by an object in the second object plane E2 and reflected back to the image acquisition device 40 as the second component 412 of the reflected illumination light 41. Thus, from a single emitted light beam of the illumination light 31, two or more light beams of reflected illumination light 41 would arrive at the image acquisition device 40. This can lead to undesirable interference effects on the resulting image.Examples of disruptive effects include overexposure and / or unwanted shadows.

[0068] Such interference effects can be avoided by using the deflection unit 20. Another function of the deflection unit is therefore to compensate for the offset caused by the distance a between the lighting device 30 and the image acquisition device 40. This function is particularly evident in the lower figure in Fig. Figure 2 is shown schematically. The aforementioned directional selectivity of the deflection structures 211, 212, 221, 222 is utilized. As previously described, with directional selectivity, the incident light is deflected at a predetermined diffraction angle determined by the respective grating property. The diffraction angle is the angle between an incident light ray and the corresponding deflected light ray. However, the deflection structures 211, 212, 221, 222 are generally non-ideal systems, so that instead of a deflected light ray, a fan or cone-shaped beam of light is produced. The illuminating light 31 and the reflected illuminating light 41 are thus fanned out within a predetermined cone angle or angle of inclination during each coupling in and / or out. Preferably, the angle of inclination is less than 5°, and particularly less than 1°.This spreading of the light thus compensates for the offset between lighting device 30 and image capture device 40. Fig. Figure 1 thus shows rather an idealized representation of the illuminating light 31 and the reflected illuminating light 41 as individual light rays.

[0069] The following summarizes the advantages of using the camera device as described previously. Firstly, shadows on the resulting image can be avoided because the object is illuminated virtually on the same optical axis as the camera (hereinafter referred to as on-axis illumination). Secondly, the illumination and / or recording time window or interval is more accurate because, due to on-axis illumination, there is no unknown change in the geometric path length of the (reflected) illumination light. Otherwise, the influence of any offset between the illumination device and the image acquisition device would have an increasingly significant impact on the resulting image as the distance between the camera device and the object being recorded increases.Furthermore, the use of HOEs offers the advantage that the desired wavelength of the illumination light can be narrower (smaller) and thus more precisely defined (wavelength selectivity). This eliminates the need for additional optical filters in the camera device, saving costs and components, and consequently reducing unwanted effects (refractions and / or reflections). Similarly, the angular selectivity of HOEs allows for narrower angular ranges, enabling more precise angular design. This functionality is generally not achievable with conventional optical components. Additionally, the minimal or negligible size of the HOE allows for a particularly flat camera design, enabling the creation of a smaller and / or lighter package or housing for the camera device.This is particularly relevant in the automotive sector. Because HOEs can be integrated into a transparent light guide, which therefore only reacts to the wavelength and / or angle defined by the HOE, the advantage arises that the corresponding camera device can be used in locations that would otherwise be impossible, such as in the headlight area, for example in the automotive sector.

[0070] Overall, the examples show how a holocam can be made available to record objects that are located in defined object planes relative to the holocam.

Claims

[1] Camera device (10) for producing at least one image of at least one object (O1, O2) in a environment (U), comprising: - a light-guiding medium (23) comprising a first deflection element (21) and a second deflection element (22) and configured to transmit light by means of internal reflection between the first and second deflection elements (21, 22), - a lighting device (30) configured to provide an illumination light (31) for illuminating the object (O1, O2) in the environment (U), an image acquisition device (40) configured to capture the reflected illumination light (41) upon reflection of the illumination light (31) at the respective object (O1, O2) and to generate at least one image, wherein, for the purpose of providing the reflected illumination light (41) to the image acquisition device (40), the first deflection element (21) is configured to couple the reflected illumination light (41) into the light-guiding medium (23) for transmission to the second deflection element (22), and the second deflection element (22) is configured to couple the transmitted illumination light (41) out of the light-guiding medium (23) for transmission to the image acquisition device (40),wherein the image acquisition device (40) is attached directly to a first side of the light guiding medium (23) within an area formed by a decoupling deflection structure (222) of the second deflection element (22), - a control device (50) configured to operate the lighting device (30) and the image acquisition device (40) in a predetermined switching operation, wherein the lighting device (30) and the image acquisition device (40) have an activated state for providing the illumination light (31) and for capturing the reflected illumination light (41) at different times during the switching operation, characterized by, that the lighting device (30) is configured to provide the illumination light (31) to the second deflection element (22), wherein the second deflection element (22) is configured to couple the illumination light (31) into the light-guiding medium (23) for transmission to the first deflection element (21), and the first deflection element (21) is configured to couple the transmitted illumination light (31) out of the light-guiding medium (23) for illumination of the object, wherein the lighting device (30) is attached directly to the first side of the light-guiding medium (23) within an area formed by a coupling deflection structure (221) of the second deflection element (22), and that the first deflection element (21) and the second deflection element (22) are configured to compensate for a distance between the image acquisition device (40) and the lighting device (30). [2] Camera device (10) according to claim 1, wherein the control device (50) is configured in switching mode to lengthen or shorten a pause interval between the activated state of the lighting device (30) and the activated state of the image capture device (40) according to a predetermined switching criterion with each switching operation. [3] Camera device (10) according to one of the preceding claims, wherein the image acquisition device (40) for switching between the activated state and a deactivated state comprises a mechanically movable shutter element and / or an electrically switchable film layer (42). [4] Camera device (10) according to one of the preceding claims, wherein the illumination device (30) and the image capture device (40) are arranged at a predetermined distance (a) from each other in a transmission area of ​​the light guide medium (23) formed by the second deflection element (22). [5] Camera device (10) according to one of the preceding claims, wherein the illumination device (30) comprises a laser light source for providing the illumination light (31). [6] Camera device (10) according to one of the preceding claims, wherein the lighting device (30) is configured to generate the illumination light (31) in the infrared frequency range. [7] Camera device (10) according to one of the preceding claims, wherein the first and second deflection element (21, 22) are designed as optical gratings, in particular as holographic surface gratings or holographic volume gratings. [8] Camera device (10) according to one of the preceding claims, wherein the first and the second deflection element (21, 22) each comprise an in-coupling deflection structure (211, 221) for coupling the illumination light (31, 41) into the light-guiding medium (23) and an out-coupling deflection structure (212, 222) for coupling the illumination light (31, 41) out of the light-guiding medium (23), and and the coupling deflection structure (221) of the second deflection element (22) and the coupling deflection structure (212) of the first deflection element (21) are configured to deflect the illumination light (31) at a predetermined first diffraction angle, and the coupling deflection structure (211) of the first deflection element (21) and the coupling deflection structure (222) of the second deflection element (22) are designed to deflect the reflected illumination light (41) in a predetermined second diffraction angle different from the first diffraction angle. [9] Camera device (10) according to one of the preceding claims, wherein the image acquisition device (40) has an image sensor with at least two detection areas and the light guide medium (23) has a separate deflection area with the first and second deflection element (21, 22) for each of the detection areas, wherein each of the deflection areas is configured to detect an at least partially different area of ​​the environment (U). [10] Headlight arrangement (60) for a motor vehicle comprising a headlight light source (61) and a camera device (10) according to one of the preceding claims, wherein a light guiding medium (23) is designed to be transparent and is arranged in a direction of emission of the headlight light source (61) in such a way that the headlight light source (61) is designed to provide a headlight light through the light guiding medium (23) between a first and a second deflecting element (21, 22).

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