Optical detector, spectral sensor, and method for manufacturing an optical detector

Abstract

An optical detector (1) is provided. It comprises a plurality of sensor segments (11) configured to detect electromagnetic radiation, an aperture sheet (20) arranged in a vertical direction (z) above the sensor segments (11), the aperture sheet (20) comprising a first layer (21) and a second layer (22), the first layer (21) being closer to the sensor segments (11) than the second layer (22). For each of the sensor segments (11), the first layer (21) defines a first aperture (31) and the second layer (22) defines a second aperture (32), the first aperture (31) and the second aperture (32) forming an aperture stack (30) that defines a direction of sensitivity (ds) of the respective one of the sensor segments (11). The optical detector (1) further comprises a color filter (50) arranged between the sensor segments (11) and the aperture sheet (20), and a diffuser film (60) arranged between the color filter (50) and the aperture sheet (20). At least one of the first aperture (31) and the second aperture (32) has, in a top view, a shape of regular tessellation.

Description

[0001] 2023PF01759 April 2, 2025P2024,0147 WO N- 1 -Description OPTICAL DETECTOR, SPECTRAL SENSOR, AND METHOD FORMANUFACTURING AN OPTICAL DETECTOR The present disclosure relates to an optical detector and to method for manufacturing such optical detector. Thedisclosure further relates to a spectral sensor and to anoptoelectronic device employing such optical detector.Optical detectors for sectored viewing may be based on micro-lens array, MLA, packages. Due to the tolerances in MLA andpackaging processes, a viewing angle of such sensors may betilted, therefore requiring huge compensation efforts.Further, a circular field of view, FOV, of individual sensorsegments integrated in the optical detector may be realizedby means of circular apertures. However, combining circularfields of view of several sensor segments may lead to an inhomogeneous sensitivity of the system. At least one object of particular embodiments is to provide an improved optical detector. In particular, the optical detector may have an optimized aperture configuration. This object is achieved with the subject-matter of the independent claims. Embodiments and developments derive from the dependent claims. An optical detector is provided. According to at least one embodiment, the optical detector comprises a plurality of sensor segments configured to detect electromagnetic radiation.2023PF01759 April 2, 2025P2024,0147 WO N- 2 -Here and in the following, electromagnetic radiation denotes light of any wavelength region, for example the visible wavelength range, the infrared wavelength range and / or the ultraviolet wavelength range. In particular, the sensor segments may be sensitive for the visible wavelength range. That the optical detector comprises a plurality of sensor segments can mean that it comprises at least two sensor segments. Preferably, the optical detector comprises at least two and at most 25 sensor segments. The plurality of sensor segments may be arranged in an array. This can mean that the sensor segments are arranged adjacent to each other in lateral directions. Lateral directions run parallel to a main plane of extension of the array. The sensor segments may be arranged in or on a common sensor substrate. For example, the sensor substrate is a semiconductor substrate, and the sensor segments are formed by photodiodes integrated in thesemiconductor substrate. Each photodiode is configured togenerate an electrical signal that is proportional to theintensity of electromagnetic radiation hitting the photodiode. In an implementation, each sensor segment is formed by a single photodiode. However, it is also possible that each sensor segment is formed by more than one photodiode. The sensor segment and / or the photodiode forming the sensor segment may be referred to as pixel. According to at least one embodiment, the optical detector comprises an aperture sheet arranged in a vertical direction above the sensor segments, the aperture sheet comprising a first layer and a second layer, the first layer being closer to the sensor segments than the second layer. The vertical direction runs perpendicular to the main plane of extension of the array or of the sensor substrate,2023PF01759 April 2, 2025P2024,0147 WO N- 3 -respectively. The aperture sheet may be arranged between the plurality of sensor segments and incoming electromagnetic radiation to be detected. The first layer may be arranged at a side of the aperture sheet that faces the plurality of sensor segments. The second layer may be arranged at a side of the aperture sheet that faces away from the sensor segments. The aperture sheet may comprise a material that is transparent for electromagnetic radiation to be detected.Here and in the following, the term “transparent” can mean atransparency of at least 80% or at least 90% for a specific wavelength range. However, the first layer and the second layer may be opaque for electromagnetic radiation to be detected. The first and the second layer may absorb or reflect electromagnetic radiation to be detected. In other words, electromagnetic radiation that hits the first or the second layer does not reach the sensor segments. For example, the aperture sheet comprises a transparent glass body, wherein opaque chromium layers are deposited on main sides of the glass body as first and second layers. According to at least one embodiment, for each of the sensorsegments, the first layer defines a first aperture, and thesecond layer defines a second aperture. The first and thesecond aperture form an aperture stack that defines a direction of sensitivity of the respective one of the sensor segments. At places of the apertures, the first layer and the secondlayer, respectively, are removed. Therefore, an optical pathis defined through the aperture sheet for each sensor segment. The first apertures defined by the first layer are spaced from each other in lateral directions. Similarly, the second apertures defined by the second layer are spaced from2023PF01759 April 2, 2025P2024,0147 WO N- 4 -each other in lateral directions. Electromagnetic radiation passing through the first and the second aperture reaches therespective sensor segment. Each aperture stack is assigned toa respective sensor segment, and vice versa. The first and second aperture may be different in size and shape. Further, the centers of the first and the second aperture may beshifted in lateral directions. Shape, size, offset anddistance between the apertures, as well as the refractive index of a material between the first layer and second layer, define the optical path through the aperture sheet, as thus the direction of sensitivity of the sensor segments. Thedirection of sensitivity relates to a field of view of therespective sensor segment. In particular, the direction ofsensitivity may be a main direction of the field of view. Thedirections of sensitivity of at least two of the sensor segments may be different. Preferable, each sensor segment has a different direction of sensitivity defined by the aperture stack that is associated with the respective one of the sensor segments. According to at least one embodiment, at least one of the first aperture and the second aperture has, in a top view, apolygonal shape of tessellation.The top view refers to a view on the optical detector from the side of aperture sheet facing away from the sensor segments. The shape extends in lateral directions. That theshape is a shape of tessellation can mean that several ofthese shapes can cover a surface or plane with no overlaps and no gaps. The polygonal shape may be a triangle, a rectangle, or a hexagon. In particular, the shape may be anequilateral triangle, a square or a regular hexagon. Theshape of the first aperture may be different from the shape2023PF01759 April 2, 2025P2024,0147 WO N- 5 -of the second aperture. For example, one of these apertures may have a circular or elliptical shape. However, it is also possible that both apertures have the same polygonal shape. The first aperture and / or the second aperture of eachaperture stack may have the same polygonal shape oftessellation. In particular, aperture stacks of adjacentsensor segments may have apertures, the shapes of which can be arranged in a plane without gaps and overlaps. By means of the polygonal shapes of the apertures, adjacent sensor segments may have fields of view that join together in thesense of tessellation. In other words, a scene is mappedhomogeneously and without gaps onto the array of sensor segments. According to at least one embodiment, an optical detector comprises a plurality of sensor segments configured to detect electromagnetic radiation; an aperture sheet arranged in a vertical direction above the sensor segments, the aperture sheet comprising a first layer and a second layer, the first layer being closer to the sensor segments than the second layer; wherein, for each of the sensor segments, the first layer defines a first aperture and the second layer defines a second aperture, the first and the second aperture forming an aperture stack that defines a direction of sensitivity of therespective one of the sensor segments; and wherein at leastone of the first aperture and the second aperture has, in a top view, a polygonal shape of tessellation. The proposed concept is based on the following technical considerations, among others.The optical detector may be employed as color or spectralsensor to assist a camera system by providing data relating2023PF01759 April 2, 2025P2024,0147 WO N- 6 -to the spectral composition of one or more ambient light sources illuminating a scene to be captured by the camera system. To this end, the optical detector comprises a plurality of sensor segments with different directions of sensitivity to evaluate the ambient light. The field of view of the optical detector at least partially overlaps with the field of view of the camera system, wherein each sensor segment may be assigned to one particular sector of the scene to be captured. Thus, the optical detector may be referred to as sectored view sensor. The optical detector may have a low resolution, in particular a lower resolution than the camerasystem. It might be sufficient to provide a single- or twodigit number of sensor segments / pixels corresponding to respective sectors of the scene to be captured.Conventional approaches may use a micro-lens array, MLA, todirect light towards the sensor segments. However, an MLAbased design concept for a sectored view sensor may sufferfrom tilted viewing angles due to tolerances in the MLAprocess as well as tolerances in the packaging process. Inturn, huge efforts for tilt compensation are required during final test. Further, due to the low pixel count of theoptical detector it is required for MLA concepts to blurand / or smooth the scenery image to compensate for small butdominant and / or moving light spots, which would be projected by the MLA to an area between the pixels. The present disclosure provides a sectored view sensor without MLA, but with an aperture optics, that may be referred to as facet eye optics. In particular, the presentdisclosure suggests replacing the MLA by an individualaperture stacks for each sensor segment to facilitate thesectored view goal. The apertures can be manufactured highly2023PF01759 April 2, 2025P2024,0147 WO N- 7 -accurately and alignment between the sensor segments and the apertures can be achieved with high precision. The viewingangle, the direction of sensitivity (field of view) and thesmoothing in this design can be defined by the aperturediagonals, the aperture distances, their size ratio, andtheir off-axis shift. Further, the present disclosure relates to an optimizedaperture configuration to generate a homogeneous sensitivityover the full object field. This is achieved by having atleast one of the apertures of each aperture stack with apolygonal shape suited for tessellation. This means that the shapes are such that a plane could be covered without gapsand overlaps. In particular, the apertures limiting the fieldof view have polygonal shapes instead of circular ones. Ifcircular shapes were used, an overlap of separate viewingfields would be necessary to prevent clipping effects whensmall but dominant light spots are present. Having an arrayarrangement of several circular viewing sectors, thegeometrical sensitivity of the system would not behomogeneous. In other words, the detected brightness of adominant small radiation spot would depend on its position inthe scene. On the one hand, if the position is in the fieldof view of several sensor segments, higher sensor signalswould be generated. On the other hand, there might bepositions in the scene, for which none of the sensor segmentsare sensitive or for which the sensor segments are lesssensitive, resulting in lower sensor signals. By havingpolygonal aperture shapes, the fields of view of the sensorsegments may join together in the sense of tessellation. Thismakes the sensitivity of the system more homogeneous. Further, since the individual fields of view of the sensor segments have polygonal shapes, a combined field of view of2023PF01759 April 2, 2025P2024,0147 WO N- 8 -the optical detector may also have a polygonal shape and maymatch the field of view of an associated camera system. According to at least one embodiment, the first aperture is smaller than the second aperture, and wherein the second aperture has a polygonal shape of tessellation. According to at least one embodiment, the second aperture is smaller than the first aperture, and wherein the first aperture has a polygonal shape of tessellation. That one aperture is smaller than the other aperture can mean that a diagonal of the aperture is smaller than a diagonal of the other one. The smaller aperture may mainly define the blur or smoothing of the imaged scene. The smaller aperture may have a round / circular shape. It is however also possible that the smaller aperture also has a polygonal shape. The larger aperture may mainly define the field of view of the sensor segment. Since the larger aperture has a polygonal shape of tessellation, the fields of view of adjacent sensor segments join together in the sense of tessellation. In other words, the fields of view of the sensor segments cover the whole object plane imaged onto the array of sensor segments without gaps. If the first aperture is smaller than the second aperture, the sensor segments can be designed smaller, which in turn allows a smaller pixel pitch. If the second aperture is smaller than the first aperture, the entrance field for electromagnetic radiation is smaller. According to at least one embodiment, the sensor segments are arranged on a rectangular grid, and wherein at least one of the first aperture and the second aperture has a rectangular shape in top view.2023PF01759 April 2, 2025P2024,0147 WO N- 9 -In this case, the sensor segments are arranged in a rectangular array. For example, the sensor segments are arranged in a 2x2, 3x3, 4x4 or 5x5 array. The sensor segments may in particular have a rectangular shape, but other shapes are also possible. In this implementation, the first and / or the second aperture of each aperture stack has a rectangular shape corresponding to the rectangular grid. At least the larger one of the apertures may have a rectangular shape. In an implementation, the sensor segments are arranged on a square grid, and the respective aperture has a square shape. Having a rectangular, in particular square, aperture results in a field of view of the respective sensor segment covering a rectangular, in particular square, viewing sector of the object plane. Rectangular viewing sectors can adjoin or overlap each other without gaps in between. According to at least one embodiment, the sensor segments are arranged on a triangular grid, and wherein at least one of the first aperture and the second aperture has a triangular shape in top view. In this case, the sensor segments are arranged in a triangular array. The sensor segments may have a triangular shape, but other shapes are also possible. In this implementation, the first and / or the second aperture of each aperture stack has a triangular shape corresponding to the triangular grid. At least the larger one of the apertures may have a triangular shape. In an implementation, the sensorsegments are arranged on an equilateral triangular grid, andthe respective aperture has an equilateral triangular shape.Having a triangular, in particular equilateral triangular,aperture results in a field of view of the respective sensor2023PF01759 April 2, 2025P2024,0147 WO N- 10 -segment covering a triangular, in particular equilateral triangular, viewing sector of the object plane. Triangular viewing sectors can adjoin or overlap each other without gaps in between. According to at least one embodiment, wherein the sensor segments are arranged on a hexagonal grid, and wherein at least one of the first aperture and the second aperture has a hexagonal shape in top view. In this case, the sensor segments are arranged in a hexagonal array. The sensor segments may have a hexagonal shape, but other shapes are also possible. In this implementation, the first and / or the second aperture of each aperture stack has a hexagonal shape corresponding to the hexagonal grid. At least the larger one of the apertures may have a hexagonal shape. In an implementation, the sensor segments are arranged on a regular hexagonal grid, and the respective aperture has a regular hexagonal shape. Having a hexagonal, in particular regular hexagonal, aperture results in a field of view of the respective sensor segment covering a hexagonal, in particular regular hexagonal, viewing sector of the object plane. Hexagonal viewing sectors can adjoin or overlap each other without gaps in between.According to at least one embodiment, the directions ofsensitivity of at least two sensor segments are differentfrom each other. In other words, the fields of view of at least two sensor segments are different. Thus, the sensor segments cover different sectors of the object plane. However, the fields of view of the sensor segments may overlap. The fields of view2023PF01759 April 2, 2025P2024,0147 WO N- 11 -of the sensor segments may join together to form an overall field of view of the optical detector that covers the object plane homogenously. In particular, there are no blind spots in the power distribution of the combined sensor segments. According to at least one embodiment, the aperture sheet further comprises at least one intermediate layer between the first layer and the second layer, wherein, for each aperture stack, the at least one intermediate layer defines an intermediate aperture assigned to the respective one of the aperture stacks. The aperture sheet may comprise one or more intermediate layers between the first and the second layer. The intermediate layer may be arranged in the vertical direction above the first layer and below the second layer. The intermediate layer(s) is / are opaque for electromagnetic radiation to be detected. However, electromagnetic radiationcan pass the aperture sheet at places of the intermediateaperture. By means of the intermediate aperture the optical path through the aperture sheet can be further defined. Crosstalk between the sensor segments can be prevented. Thiscan mean that electromagnetic radiation passing the aperturesheet through one aperture stack may only reach the sensor segment associated with that aperture stack but cannot reach other sensor segments. This allows for smaller pixel pitches. According to at least one embodiment, the aperture sheet further comprises a substrate body that is transparent for electromagnetic radiation to be detected, wherein the firstlayer is arranged on a side of the substrate body facing thesensor segments, and the wherein the second layer is arranged2023PF01759 April 2, 2025P2024,0147 WO N- 12 -on a side of the substrate body facing away from the sensorsegments. As mentioned above, the substrate body may be or may comprise a glass body. The substrate body may have a refractive index of at least 1.4 or of at least 1.5 and / or of at most 1.8 or of at most 1.7. This applies, for example, for a wavelengthof 532 nm and a temperature of 300 K. An overall thickness ofthe substrate body is, for example, at least 0.2 mm and / or atmost 2 mm or at most 1 mm. The substrate body may comprise orconsist of a plurality of sub-sheets. A thickness of the sub-sheets is, for example, at least 50 µm or at least 150 µmand / or at most 450 µm or at most 320 µm. Intermediate layersdefining intermediate apertures, as described above, may be arranged between the sub-sheets, such that they are embedded in the substrate body. The thickness and the refractive index of the substrate body may affect the range of angles under which electromagnetic radiation reaches the first apertureand / or the sensor segments. For example, a refractive indexof glass or another material for the aperture sheet may limita maximum possible angle of detection to be about 40°. Thus,transmission and / or crosstalk characteristics can be adjusted by appropriate selection of the substrate body. According to at least one embodiment, the optical detectorfurther comprises a color filter arranged between the sensorsegments and the aperture sheet. The color filter is configured to transmit electromagnetic radiation of a specific wavelength range and / or the block electromagnetic radiation of other wavelength ranges. For example, the color filter is configured to transmit light in the blue, red or green wavelength range. For example, the2023PF01759 April 2, 2025P2024,0147 WO N- 13 -color filter is arranged on a surface of the sensor segments. The sensor segments may share a common color filter. In thiscase, all sensor segments are sensitive to the same spectralrange which is, for example, a sub-range of the visible spectral range. Thus, the sensor segments detect a monochromatic image of the scene. The color filter may be implemented as interference filter, Bragg filter or tinted filter. According to at least one embodiment, the optical detectorfurther comprises a diffuser film arranged between the colorfilter and the aperture sheet. For example, the diffuser film is arranged on the color filter. It is also possible that the diffuser film is arranged on a side of the aperture sheet facing the color filter. For example, the diffuser film is a matrix material with embedded light-scattering particles and / or a light- transmissive layer having one or two roughened main sides.The sensor segments may share a common diffuser film. Thecolor filter may exhibit transmission characteristics that are dependent on the angular spread of light rays hitting the color filter. By means of the diffuser film the angular spread can be adjusted, such that the transmission of the color filter is more independent from the angle of incidence. Further, a spectral sensor is provided. The spectral sensor comprises a plurality of optical detectors according to one of the embodiments described above. This means that features of the optical detector are also disclosed for the spectral sensor, and vice versa.2023PF01759 April 2, 2025P2024,0147 WO N- 14 -According to at least one embodiment, the spectral sensor comprises a plurality of optical detectors as described above, wherein the color filters of the optical detectors differ from each other to form distinct color channels of the spectral sensor. By means of the different color filters each of the optical detectors is sensitive to a different wavelength range. Thus, a monochromatic image is generated by a respective one of the optical detectors. By combining several optical detectors a spectral composition of the ambient light can thus be evaluated. The spectral sensor may comprise at least twooptical detectors forming distinct color channels. Forexample, the spectral sensor comprises at least three spectral channels, at least nine color channels, or at least twelve color channels.According to at least one embodiment of the spectral sensor,the plurality of optical detectors forms an array of color channels. For example, the optical detectors are arranged in a 2x2, 3x3, or 3x4 array. It is likewise possible that the optical detectors are arranged in a line to form a linear array. As mentioned above, the sensor segments are also arranged in an array. Thus, the sensor segments of each optical detector may form sub-arrays of the spectral sensor. Further, an optoelectronic device is provided. The optoelectronic device comprises the optical detector according to one of the embodiments described above. This means that features of the optical detector are also disclosed for the optoelectronic device, and vice versa.2023PF01759 April 2, 2025P2024,0147 WO N- 15 -According to at least one embodiment, the optoelectronicdevice comprises the spectral sensor according to one of theabove-described embodiment. Further, the optoelectronic device comprises a camera system configured to take pictures in the visible spectral range. Further, the optoelectronic device comprises a processing unit, wherein the processing unit is configured to calculate a white balancing for the pictures taken by the camera system using data from the spectral sensor. In a possible implementation, the optoelectronic device may comprise or may be a smart device, such as a smartphone. The camera system and the spectral sensor may be arranged side by side in the optoelectronic device. In particular, a field of view of the camera system may at least partially overlap a field of detection of the spectral sensor. The processing unit may be integrated in the optoelectronic device and may be electrically connected to the camera system and the spectral sensor. The processing unit may be configured to combine image data from the camera system and data from the spectral sensor. The spectral sensor can be implemented as anambient light sensor, ALS, used for white balancing thecamera system. Because the field of detection may be larger than the field of view of the camera system, an efficient white balancing across the overall field of view is enabled. In particular, the spectral sensor may detect and analyze oneor more than one ambient light sources illuminating the sceneto be captured by the camera system. Thus, complex lighting conditions of the scene can be evaluated. Further, a method for manufacturing an optical detector is provided. Preferably, the optical detector according to one2023PF01759 April 2, 2025P2024,0147 WO N- 16 -of the above-described embodiments is manufactured by the method. Thus, features of the optical detector are also disclosed for the method for manufacturing the optical detector, and vice versa. According to at least one embodiment of the method, the method comprises providing a semiconductor substrate carrying the plurality of sensor segments. Providing the semiconductor substrate may comprise forming the plurality of sensor segments in the substrate. A semiconductor process, for example CMOS process may be used to form the sensor segments. Further, readout circuitry for reading out and processing the sensor signals may be integrated in the semiconductor substrate. The sensor segments may be embedded in the substrate or may be arranged at a main surface of the substrate. After forming the sensor segments, the color filter as described above may be arranged on the sensor segments. Further, the diffuser film may be arranged on the color filter. According to at least one embodiment of the method, the method comprises providing the aperture sheet having the first layer and the second layer. For example, the aperture sheet is provided by starting with a substrate body, for example a glass wafer. The first layer may be a chromium layer that is deposited on a first surface of the substrate body. The second layer, for example also chromium, may be deposited on a second side of the substratebody. The first and the second layer can be structured by aphotolithographic and etching processes to form the first and the second apertures. The substrate body may have a2023PF01759 April 2, 2025P2024,0147 WO N- 17 -sufficient thickness that allows front and backside treatment. Alternatively, one of the first and the second layer is deposited and structured on a thinner substrate body. Then, one or more than one sub-sheets are deposited on said structured layer. Then, the other one of the first and the second layer is deposited on the sub-sheet and subsequently structured. Intermediate layers may be deposited between such sub-sheets. It is possible that portions of the substrate body and / or the sub-sheets are removed by grinding or etching processes the reduce the overall thickness after the apertures are formed. Further, the diffuser film may be deposited on the aperture sheet. According to at least one embodiment of the method, themethod comprises attaching the aperture sheet to thesemiconductor substrate. The aperture sheet may be attached to the semiconductor substrate by an adhesive layer or bonding layer. For example, the color filter and / or the diffuser film may be embedded in such adhesive layer or bonding layer. Attaching the aperturesheet to the semiconductor substrate may comprise a wafer-to-wafer, chip-to-wafer, or chip-to-chip bonding technique. Attaching the aperture sheet to the sensor wafer comprises an alignment procedure. Aperture stacks are aligned to respective sensor segments. According to at least one embodiment of the method, the method comprises providing a semiconductor substrate carrying the plurality of sensor segments; providing the aperturesheet having the first layer and the second layer; andattaching the aperture sheet at the semiconductor substrate.2023PF01759 April 2, 2025P2024,0147 WO N- 18 -The method for manufacturing an optical detector is based on the same technical considerations and has the same advantages as the optical detector described above. The following description of figures may further illustrate and explain aspects of the optical detector, the spectral sensor, the optoelectronic device, and the method formanufacturing the optical detector. Components, parts andsteps of the optical detector, the spectral sensor, theoptoelectronic device, and the method for manufacturing theoptical detector, respectively, that are functionallyidentical or have an identical effect are denoted by identical reference symbols. Identical or effectively identical components and parts might be described only with respect to the figures where they occur first. Their description is not necessarily repeated in successive figures. Figure 1 shows an optical detector according to an embodiment. Figures 2a and 2b shows an exemplary aperture sheet with a corresponding optical power distribution across a combined field of view. Figures 3a to 3c shows an aperture sheet according to an embodiment with a corresponding optical power distribution across a combined field of view. Figures 4 to 6 show optical detectors according to embodiments in a top view.Figures 7 to 9 show optical detectors according to further2023PF01759 April 2, 2025P2024,0147 WO N- 19 -embodiments in a cross-section. Figures 10 to 11 show spectral sensors according to embodiments. Figures 12 to 13 show an optoelectronic device according to an embodiment. Figure 14 schematically shows a method of manufacturing an optical detector. With figure 1 an optical detector 1 is shown in a cross-section. The optical detector 1 comprises a plurality ofsensor segments 11 configured to detect electromagnetic radiation. Possible beam paths of the electromagneticradiation are illustrated by solid and dashed lines. In theshown example, the sensor segments 11 are arranged at a main surface of a sensor substrate 10. The substrate 10 has a main plane of extension, which extends along lateral directions x, y. Although only two sensor segments 11 are shown, the optical detector 1 may comprise more than two sensor segments 11. In particular, the plurality of sensor segments 11 may be arranged laterally adjacent to each other and may form an array. The optical detector 1 further comprises an aperture sheet 20 arranged in a vertical direction z above the sensor segments 11. The vertical direction z runs perpendicular to thelateral directions x, y. An adhesive layer 40 may be arrangedbetween the sensor substrate 10 and the aperture sheet 20, asindicated in figure 1.2023PF01759 April 2, 2025P2024,0147 WO N- 20 -The aperture sheet 20 comprises a first layer 21 and a secondlayer 22, the first layer 21 being closer to the sensor segments 11 than the second layer 22. The first layer 21 is arranged on a side of the aperture sheet 20 that faces the sensor segments 11. The second layer 22 is arranged on a side of the aperture sheet 20 that faces away from the sensor segments 11. The aperture sheet 20 further comprises a substrate body 25 defining the sides on which the first and the second layer 21, 22 are arranged. For each of the sensor segments 11, the first layer 21 defines a first aperture 31 and the second layer 22 defines a second aperture 32. The first aperture 31 and the second aperture 32 form an aperture stack 30. In other words, each aperture stack 30 comprising the first aperture 31 and the second aperture 32 is assigned to a respective one of the sensor segments 11, and vice vera. The apertures 31, 32 are formed by holes / recesses in the first layer 21 and the second layer 22. Each aperture stack 30 defines a direction of sensitivity ds of the respective one of the sensor segments 11. The direction of sensitivity ds is a main direction of a field of view of the respective sensor segment 11. The field of view is defined by the size, the shape the distance and thelateral offset of the apertures 31, 32. As shown in figure 1,one of the sensor segments 11 has a direction of sensitivityds that is different from a direction of sensitivity ds’ ofthe other sensor segment 11. Further, although not shown in the cross-section of figure 1, at least one of the first aperture 31 and the second aperture 32 has, in a top view, a polygonal shape of tessellation.2023PF01759 April 2, 2025P2024,0147 WO N- 21 -This is further illustrated in the following figures, in particular figures 4 to 6. In figure 2a, an exemplary aperture sheet 20 is shown that does not form part of the present invention but it useful for understanding the invention. The aperture sheet 20 is shown in a top view. The aperture sheet 20 comprises four aperture stacks 30 arranged in a 2x2 array, wherein each stack 30 comprises a first aperture 31 and a second aperture 32. Both apertures 31, 32 of the aperture stacks 30 have circular shapes in top view. The center of the smaller first aperture 31 is laterally shifted with respect to the center of the larger second aperture 32. Thus, the aperture stacks 30 define different directions of sensitivity ds, ds’ for thesensor segments 11 assigned to them. In other words, thesensor segments 11 cover different sectors of a scene to be captured. Figure 2b shows a corresponding simulated optical power distribution of light that passes through the aperture sheet 20. The simulation of the power distribution illustrates the geometrical sensitivity of the device. It may be learned from figure 2b, that an intensity of passing light is high at locations which are covered by either separate oroverlapping fields of view / sectors. However, in the centerof the 2x2 sectors a huge attenuation can be possible. In theshown example, there is a blind spot BS in the center of the power distribution. This means that, if a small light source is located outside the covered sectors, light coming fromthat light source cannot pass the aperture sheet. The blindspot is mainly caused by the use of circular apertures 31,32, since such apertures define circular field of view solidangles. However, these fields of view / sectors cannot beadjoined in such a way that the entire object plane ishomogenously covered by the sectored view sensor.2023PF01759 April 2, 2025P2024,0147 WO N- 22 -Figure 3a shows an aperture sheet 20 according to an embodiment. The aperture sheet 20 is different from the aperture sheet of figure 2a in that the first aperture 31 and the second aperture 32 are not circular but have a rectangular shape in top view. Figure 3b shows the corresponding power distribution of light that passes through the aperture sheet 20 of figure 3a. It can be seen that the respective sectors are matched to each other to form a homogenous power distribution across the combined field of view. This is possible due to the rectangular apertures defining respective fields of view / sectors that join together without gaps in between. In other words, the sectors are defined in such a way that their respective shapes cover the entire object plane in a sense of tessellation. Figure 3c shows various cross sections of the power distribution along dedicated lines Y0-Y0, Y1-Y1 and Y2-Y2 indicated in figure3b. Each cross section shows a smooth cosine attenuation fromthe center to the corners of the distribution (solid lines). The dashed lines illustrate the power distributions of individual sectors defined by the respective aperture stacks 30. Figure 4 shows an optical detector 1 according to an embodiment in top view. It shows a 3x3 array of rectangular sensor segments 11. However, the array size is arbitrary. The aperture sheet 20 comprises a plurality of first apertures31, each of which being aligned with a respective one of thesensor segments 11. A diagonal of the first apertures 31 issmaller than a diagonal of the sensor segments 11. Theaperture sheet 20 further comprises a plurality of second apertures 32. A diagonal of the second apertures 32 is larger than a diagonal of the first apertures 31. A lateral shift2023PF01759 April 2, 2025P2024,0147 WO N- 23 -between the first apertures 31 and the second apertures 32 varies for each aperture stack 30, thereby defining different directions of sensitivity for each sensor segment 11. Each aperture stack 30 further comprises an optional intermediate aperture 33 between the first aperture 31 and the second aperture 32. The intermediate apertures 33 may be laterally shifted with respect to the first and the second apertures 31, 32. The intermediate apertures 33 may have the same size and shape as one of the first and the second apertures 31, 32. Alternatively, the size and / or the shape of the intermediate apertures 33 may be different. With figure 5 an alternative embodiment of the optical detector 1 is shown. The embodiment according to figure 5 is different from the embodiment according to figure 4 in that the first and the second apertures 31, 32 do not have a rectangular shape but a hexagonal shape. Further, the sensor segments 11 are arranged on a hexagonal grid. With figure 6 a further alternative embodiment of the optical detector 1 is shown. In the embodiment according to figure 6 the first and the second apertures 31, 32 have a triangular shape. Further, the sensor segments 11 are arranged on a triangular grid. In figures 5 and 6 the sensor segment 11 still have a rectangular shape in top view, which may be easier to fabricate. However, the shape of the sensor segments 11 may differ from a rectangular shape. With figure 7 a further exemplary embodiment of the optical detector 1 is shown is a cross-section. The optical detector 1 further comprises a color filter 50 that is deposited directly on the sensor segments 11. The color filter may be configured to adjust a sensitivity of the optical detector 12023PF01759 April 2, 2025P2024,0147 WO N- 24 -to a spectral sub-range of the visible spectral range. A diffuser film 60 is deposited on the color filter 50. The diffuser film 60 is configured to compensate for a possible dependency of a transmission through the color filter 50 on an angle of incidence. Besides, the aperture sheet 20 comprises a thick substrate body 25, wherein the first layer 21 is arranged on the side of the substrate body 25 that faces the sensor substrate 10. The second layer 22 as well as an intermediate layer 23 are embedded in the substrate body 25. Each set of first, intermediate and second aperture 31, 32, 33 forms an aperture stack 30 assigned to a respective one of the sensor segments 11. The intermediate apertures 33 may be provided to prevent crosstalk between individual sensor segments 11. With figures 8 and 9 two further embodiments of the optical detector 1 are shown. In figure 8, the first aperture 31 defined by the first layer 21 has a diagonal d1, and the second aperture 32 defined by the second layer 22 has a diagonal d2, wherein d2 is larger than d1. In this case, preferably, the second aperture 32 has a polygonal shape, while the shape of the first aperture 31 is arbitrary. In the embodiment of figure 9, die diagonal d2 of the second aperture is smaller than the diagonal d1 of the first aperture 31. Here, preferably, the first aperture 31 has a polygonal shape, while the shape of the second aperture 32 is arbitrary. In addition, there is a distance h1 between a main surface of the sensor substrate 10 and the aperture sheet 20. In a preferred embodiment, the distance h1 is defined by the combined thickness of the color filter 50 and the diffuser2023PF01759 April 2, 2025P2024,0147 WO N- 25 -film 60. Thus, as shown in figures 8 and 9, the aperture sheet 20 may be positioned directly on top of the diffuser film 60 to from a compact and stable device. The aperture sheet has a thickness h2. For example, the thickness h2 (together with a refractive index of the substrate body 25) is selected so that a maximum possible angle of detection is limited. With figure 10 a spectral sensor 100 is illustrated. The spectral sensor 100 comprises a plurality of optical detectors 1, 1’, 1’’. The sensor segments 11 of the respective optical detectors 1 are integrated in a common sensor substrate 10. Also, the optical detectors 1, 1’, 1’’ share a common aperture sheet 20 that is attached to the sensor substrate 10 by means of an adhesive or bonding layer 40. The aperture sheet 20 with the first and the second layer 21, 22 defines respective aperture stacks 30 for each of the optical detectors 1, 1’, 1’’. Each of the optical detectors 1, 1’, 1’’ may have a different color filter 50, 50’, 50’’. For example, the color filter 50 is transmissive for a first wavelength range, the color filter 50’ is transmissive for a second wavelength range, and the color filter 50’’ is transmissive for a third wavelength range, wherein the first, the second and the third wavelength range may be different sub-ranges of the visible wavelength domain. Thus, the plurality of optical detectors 1, 1’, 1’’ forms distinct color channels of the spectral sensor 100. Each color channelmay generate a monochromatic version of the same image.Sectors of a color channel may correspond to sectors of another color channel. In other words, each optical detector / color channel may have the same amount of sensor segments with corresponding fields of view.2023PF01759 April 2, 2025P2024,0147 WO N- 26 -Figure 11 shows the spectral sensor 100 in a top view. It illustrates that the color channels formed by respective optical detectors 1, 1’ with different color filters 50, 50’ can be arranged in an array. In the shown example, the spectral sensor 100 comprises twelve color channels arranged in a 3x4 array. However, the number of color channels and their arrangement is arbitrary. Figures 12 and 3 illustrate an embodiment of an optoelectronic device 200. For example, the optoelectronic device 200 is a smartphone. The optoelectronic device 200 comprises a camera system 150 and a spectral sensor 100. Thecamera system 150 and the spectral sensor 100 may be locatedunder a cover glass 151, for example. Moreover, theoptoelectronic device 200 includes a processing unit 160.The camera system 150 has a field of view FOV around aviewing direction of the camera system 150, the viewing direction can be an optical axis. It is noted that the camerasystem 150 is illustrated only very schematically so thatcomponents of the camera system 150, like lenes, optical filters, a CCD chip, or electronics are not shown. Forexample, the camera system 150 is configured for takingpictures and for recording videos.The spectral sensor 100 may be sensitive to a couple of sub-ranges of the visible spectral range. Thus, the spectralsensor 100 can be an ambient light sensor, ALS, used forwhite balancing the camera system 150.Moreover, the spectral sensor has a field of detection FODaround a viewing direction of the spectral sensor. Again, theviewing direction can be an optical axis. The field of2023PF01759 April 2, 2025P2024,0147 WO N- 27 -detection is composed of the plurality of directions of sensitivity ds, ds’, ds’’ of the individual sensor segments 11 comprised in the spectral sensor 100. For example, the field of detection FOD is larger than the field of view FOV. Hence, the field of detection FOD can have an opening angle larger than an opening angle of the field of view FOV. According to Figure 13, the viewing direction of the camerasystem 150 and the viewing direction of the spectral sensor100 are colinear, however, in principle there can also be anangle between the viewing directions. With figure 14 a method of manufacturing an optical detector 1according to the above-described embodiments is shown schematically. The method comprises the following steps that are not necessarily carried out in this order but can be carried out in this order.In a first step S1, a sensor substrate 10 carrying theplurality of sensor segments 11 is provided. In a second stepS2, the aperture sheet 20 having the first layer 21 and thesecond layer 22 is provided. In a third step S3, the aperturesheet 20 is attached to the sensor substrate 10, for example,by gluing. The aperture sheet 20 may be produced using lithographic techniques, for example. Thus, a positioning tolerance of the apertures 31, 32, 33 relative to one another may berelatively small, like at most 5 µm or at most 1 µm. On theother hand, positioning tolerances of the sensor segments 11 relative to one another and of the aperture sheet 20 relative to the sensor substrate 10 may be relatively large, forexample, at least 10 µm or at least 20 µm or at least 30 µm.For this reason, edge lengths of the sensor segments 11 are,2023PF01759 April 2, 2025P2024,0147 WO N- 28 -for example, at least twice the latter positioning tolerance larger than the first aperture 31. Hence, it can be assured that the first aperture 31 is always located on the assigned sensor segment 11. For example, each sensor segment 11 has an edge length of at least 100 µm and of at most 200 µm. The embodiments disclosed herein have been discussed for the purpose of familiarizing the reader with novel aspects of theidea. Although preferred embodiments have been shown anddescribed, many changes, modifications, equivalents, and substitutions of the disclosed concepts may be made by one having skill in the art without unnecessarily departing from the scope of the claims. It will be appreciated that the disclosure is not limited to the disclosed embodiments and to what has been particularly shown and described hereinabove. Rather, features recited in separate dependent claims or in the description may advantageously be combined. Furthermore, the scope of thedisclosure includes those variations and modifications, whichwill be apparent to those skilled in the art and fall within the scope of the appended claims. The term "comprising", insofar it was used in the claims or in the description, does not exclude other elements or steps of a corresponding feature or procedure. In case that the terms "a" or "an" were used in conjunction with features, they do not exclude a plurality of such features. Moreover, any reference signs in the claims should not be construed as limiting the scope.2023PF01759 April 2, 2025P2024,0147 WO N- 29 -This patent application claims priority from German patentapplication 10 2024 111 783.4, the disclosure content ofwhich is hereby included by reference.

[0002] 2023PF01759 April 2, 2025P2024,0147 WO N- 30 -References1 optical detector10 sensor substrate11 sensor segment20 aperture sheet21 first layer22 second layer23 intermediate layer25 substrate body30 aperture stack31 first aperture32 second aperture33 intermediate aperture40 adhesive layer50 color filter60 diffuser film100 spectral sensor150 camera system151 cover glass160 processing unit200 optoelectronic deviceFOV field of viewFOD field of detectionS1-S3 stepd1 diagonal of first apertured2 diagonal of second apertureh1 distanceh2 thicknessds direction of sensitivityx,y lateral directionsz vertical direction

Claims

2023PF01759 April 2, 2025P2024,0147 WO N- 31 -Claims1. An optical detector (1) comprising:^ a plurality of sensor segments (11) configured to detectelectromagnetic radiation,^ an aperture sheet (20) arranged in a vertical direction(z) above the sensor segments (11), the aperture sheet(20) comprising a first layer (21) and a second layer(22), the first layer (21) being closer to the sensorsegments (11) than the second layer (22),^ for each of the sensor segments (11), the first layer (21)defines a first aperture (31) and the second layer (22)defines a second aperture (32), the first aperture (31)and the second aperture (32) forming an aperture stack (30) that defines a direction of sensitivity (ds) of therespective one of the sensor segments (11),^ a color filter (50) arranged between the sensor segments(11) and the aperture sheet (20),^ a diffuser film (60) arranged between the color filter(50) and the aperture sheet (20),^ wherein at least one of the first aperture (31) and thesecond aperture (32) has, in a top view, a polygonal shapeof tessellation.

2. The optical detector (1) according to claim 1, wherein thefirst aperture (31) is smaller than the second aperture (32),and wherein the second aperture (32) has a polygonal shape of tessellation.

3. The optical detector (1) according to claim 1, wherein thesecond aperture (32) is smaller than the first aperture (31),and wherein the first aperture (31) has a polygonal shape of tessellation.2023PF01759 April 2, 2025P2024,0147 WO N- 32 -4. The optical detector (1) according to one of claims 1 to3, wherein the sensor segments (11) are arranged on arectangular grid, and wherein at least one of the first aperture (31) and the second aperture (32) has a rectangular shape in a top view.

5. The optical detector (1) according to one of claims 1 to3, wherein the sensor segments (11) are arranged on a triangular grid, and wherein at least one of the firstaperture (31) and the second aperture (32) has a triangularshape in a top view.

6. The optical detector (1) according to one of claims 1 to3, wherein the sensor segments (11) are arranged on ahexagonal grid, and wherein at least one of the first aperture (31) and the second aperture (32) has a hexagonal shape in a top view.

7. The optical detector (1) according to one of claims 1 to 6, wherein the directions of sensitivity (ds) of at least twosensor segments (11) are different from each other.

8. The optical detector (1) according to one of claims 1 to 7, wherein the aperture sheet (20) further comprises at leastone intermediate layer (23) between the first layer (31) andthe second layer (32), wherein, for each aperture stack (30),the at least one intermediate layer (23) defines an intermediate aperture (33) assigned to the respective one ofthe aperture stacks (30).

9. The optical detector (1) according to one of claims 1 to 8, wherein the aperture sheet (20) further comprises a substrate body (25) that is transparent for electromagnetic2023PF01759 April 2, 2025P2024,0147 WO N- 33 -radiation to be detected, wherein the first layer (21) is arranged on a side of the substrate body (25) facing thesensor segments (11), and the wherein the second layer (22)is arranged on a side of the substrate body (25) facing awayfrom the sensor segments (11).

10. A spectral sensor (100), comprising a plurality ofoptical detectors (1) according to one of claims 1 to 9,wherein the color filters (50) of the optical detectors (11) differ from each other, such that the optical detectors (1)form distinct color channels of the spectral sensor (100).

11. The spectral sensor (100) according to claim 10, whereinthe plurality of optical detectors (1) forms an array ofcolor channels.

12. An optoelectronic device (200), comprising^ a spectral sensor (100) according to claim 10 or 11,^ a camera system (150) configured to take pictures in thevisible spectral range, and^ a processing unit (160), wherein the processing unit (160)is configured to calculate a white balancing for the pictures taken by the camera system (150) using data from the spectral sensor (100).

13. A method for manufacturing an optical detector (1) of oneof claims 1 to 9, comprising:^ providing (S1) a sensor substrate (10) carrying theplurality of sensor segments (11),^ providing (S2) the aperture sheet (20) having the firstlayer (21) and the second layer (22), and^ attaching (S3) the aperture sheet (20) to the sensorsubstrate (10).

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