Optical system, multispectral optical sensor and electric device

Abstract

The optical system (1) for a multispectral optical sensor (10) comprises a diffusive element (2), a detector (3) comprising a detection plane (30), an optical element (4) with an entrance side (41) and an exit side (42) between the diffusive element (2) and the detector (3), and an aperture (5) at the entrance side (41) of the optical element (4) between the diffusive element (2) and the optical element (41). The optical element (4) is configured to image at least one field of view (100) to the detection plane (30). The detection plane (30) is arranged in a focal plane of the optical element (4). The diffusive element (2) is configured to scatter light from the field of view (100) generating a blurred image (90) of the field of view (100) in the detection plane (30).

Description

[0001] Description

[0002] OPTICAL SYSTEM, MULTISPECTRAL OPTICAL SENSOR AND ELECTRIC DEVICE

[0003] An optical system is specified. Furthermore, a multispectral optical sensor comprising an optic system and an electric device comprising a multispectral optical sensor are specified.

[0004] One object to be achieved is, inter alia, to specify an improved optical system that is particularly suitable for a multispectral optical sensor. Further objects to be achieved are, inter alia, to specify a multispectral optical sensor and an electric device comprising such an optical system.

[0005] These objects are achieved by an optical system comprising the features of independent claim 1, by a multispectral optical sensor comprising the features of claim 13 and by an electric device comprising the features of claim 16, respectively .

[0006] According to at least one embodiment the optic system comprises a diffusive element, a detector comprising a detector plane and an optical element with an entrance side and an exit side arranged between the diffusive element and the detector. In particular, the diffusive element is configured to at least partially scatter light from an object in a field of view of the optical element before the light from the object is imaged by the optical element to the detection plane. In particular, light from the obj ect to be imaged to the detection plane by the optical element enters the optical element via the entrance side and leaves the optical element via the exit side . Preferably, the exit side of the optical element faces the detector .

[0007] The detector is , for example , a semiconductor detector . For example , the detector comprises a photodiode or a CCD ("charge coupled device" ) chip . Preferably, the detector comprises a plurality of detection regions such as pixels and / or subpixels arranged side by side in the detection plane . For example , the detection plane is parallel to the exit side of the optical element . In particular, the detector is a CMOS ("Complementary Metal-Oxide-Semiconductor" detector .

[0008] According to at least one embodiment of the optical system, the optical system comprises an aperture at the entrance side of the optical element arranged between the di f fusive element and the optical element . Preferably, the aperture is arranged directly at the optical element . That is , no further element , in particular no further optically active element , is preferably arranged between the aperture and the optical element . Alternatively, it is possible that at least one further element can be arranged between the aperture and the optical element . The further element may be , for example , a connection means such as an adhesive or the like . It is further possible that the aperture is part of the entrance side . For example , the entrance side may be processed to form the aperture . In particular, the aperture is opaque to radiation in the visible wavelength range . Preferably, the aperture is opaque to light that is to be detected by the detector . According to at least one embodiment of the optical system, the optic element is configured to image at least one fuse of you to the detection plane. That is, the optical element is an imaging optics.

[0009] It is in particular possible that the optical element is configured to image a plurality of field of views to the detection plane. In this case, different field of views are preferably imaged in different regions of the detection plane. In particular, these different regions are distinct. For example, each of the different regions forms a detection region. For example, the optical system comprises a total field of view that is in particular formed by a combination of all fields of views. That is, the individual field of views are segments of the total field of view in this case. Here and in the following it is understood that if it is referred to a plurality of field of views, these field of views are in particular segments of the total field of view. Preferably, the field of views, i.e. the segments of the total field of view are distinct. It is alternatively possible that at least some of the fields of view at least partially overlap.

[0010] According to at least one embodiment of the optical system, the detector claim is arranged in a focal plane of the optical element.

[0011] According to at least one embodiment, the diffusive element is configured to scatter light from the field of view such that a blurred image of the field of view is generated in the detector plane. In particular, an object in the field of view appears at the detection plane as an out-of-focus image, although the detection plane is arranged in a focal plane of the optical element. In particular due to scattering in the diffusive element an object in the field of view and / or the field of view may appear blurred in the detector plane. For example, the object and / or the field of view appear in the protection plan as if viewed through a frosted glass. In particular, contours, edges and small structures of the object and / or the field of view are blurred and not fully, i.e. sharply recognizable in the detector plane. That is, the field of view is optically averaged, for example such that small structures merge smoothly in one another.

[0012] Preferably, an intensity of the light of the field of view in the detection plane comprises a Gaussian distribution. In case that a plurality of field of views is imaged to the detection plane, in particular into a plurality of distinct detection regions, the blurred image associated with a certain field of view showing a Gaussian distribution covers a majority, in particular at least a third or at least half or at least two third of the detection region assigned to the respective field of view.

[0013] In at least one embodiment, the optical system for a multispectral optical sensor comprises a diffusive element, a detector comprising a detection plane, an optical element with an entrance side and an exit side arranged between the diffusive element in the detector, and an aperture at the entrance side of the optical element arranged between the diffusive element and the optical element. The optical element is configured to image at least one field of view to the detection plane. The detection plane is arranged in a focal plane of the optical element. The diffusive element is configured to scatter light from the field of view such that a blurred image of the field of view is generated in the detection plane .

[0014] The optical system described here is based, inter alia, on the following technical considerations . In order to improve colors of photographic images , it is advantageous to know an ambient light situation of a scene captured by the photographic camera . Thereby, the ambient light situation may be considered and the photographic image may be adapted accordingly in order to show the colors of the photographic images as true to reality as possible . For determining the ambient light situation, ambient light sensor such as multispectral sensors are usually used in combination with a photographic camera . By using multispectral sensors not only an intensity of the ambient light , by also the spectral distribution of the light can be analyzed . For example , capturing a photographic image in an ambience light situation of candle-light may show di f ferent colors than the same scene when the photographic image is captured in an ambience light situation i f a cold-white light-emitting diode is an ambient light source . By using a multispectral sensor, the ambient light situation can be analyzed and the photographic images may be adapted such that , for example in both said ambient light situation essentially the same colors are present in the photographic image .

[0015] I f more than one ambient light source is present in the scene captures by the photographic camera, it has been shown that a multispectral sensor is advantageous that comprises a plurality of fields of views at least partially overlapping with a field of view of the camera in the obj ect plane of the scene to be captured . In particular this allows for a detection of an ambient light gradient in the ambient light situation, which can be used to improve an image quality of the photographic image , for example , i f a plurality of ambient light sources are present or the ambient light situation changes dynamically .

[0016] In particular, a multispectral sensor comprising plurality of fields of views comprises a low resolution . Furthermore , structures of obj ects inside the field of view are typically of minor importance for the application of the multispectral sensor, since usually only the spectral distribution of ambient light inside the said field of view, for example on average , is of interest . It has been demonstrated that it is of particular advantage , especially in the case where the multispectral sensor comprises a plurality of fields of views , i f a blurred of out-of- focus images of the field of views are imaged to a detector of the multispectral sensor . By imaging a blurred image at the detector, the field of view can be optically averaged . Such a blurred image can be achieved i f , for example , the detector is arranged out of focus of an optics of the multispectral sensor . Further details on how to achieve a blurred image and the advantages thereof are disclosed, for example , in the document

[0017] WO 2022 / 074047 Al the disclosure contents of which are hereby incorporated by reference .

[0018] However, operating a multispectral sensor at low resolution, misalignment and chromatic aberration may lead to crosstalk between adj acent detector regions of the detector corresponding to the fields of views of the multispectral sensor . Furthermore , di f ferent distortion and centering of monochromatic images captured by the multispectral sensor may occur . Such negative ef fects may be compensated by an interpolation . The document WO 2023 / 117468 Al , the disclosure content of which is hereby incorporated by reference , describes a procedure for compensating of such distortion and geometrical misaligned .

[0019] In particular, it has been shown that the performance of an interpolation for such a compensation can be particularly ef fectively carried out i f an intensity distribution of the blurred image at the detection unit is a Gaussian . This may also referred to as "Gaussian blur" . However, common approaches to achieve such a Gaussian blur result in an angular spread of the intensity at the detection unit so that light striking the detector with an angle of incidence distribution . The detector is usually operated together with color filters to separate the ambient light into its spectral contributions , the spectral sensitivity may vary with the angle of incidence . Since the color filters typically show a sensitivity in their transmissivity with respect to the angle of incident , the spectral distribution at the detector may show a variation .

[0020] The optical system described here makes use of the idea to use a di f fusive element in front of an aperture at an entrance side of an optical element which is configured to image a field of view to a detection plane of a detector . By using the di f fusive element a Gaussian blur, i . e . an intensity distribution of the imaged field of view is a Gaussian, at the detection plane can be achieved . At the same time , the aperture allows for a blocking of a wide angular spread, which may occur due to scattering in the di f fusive element . Hence , a Gaussian blur can be achieved, which is advantageous for compensation of distortions and geometrical misalignments as described above . At the same time , a comparably narrow distribution of angles of incidence at the detection plane can be achieved. Thereby, a spectral variation due to a variation of transmissivity of a color filter that may be used in the vicinity of the detection plane in order to achieve a spectral separation of the light of the field of view can be kept relatively low. Furthermore, interference ripples, that may occur at passivation layers of the detector and that are sensitive to the angle of incidence at the detector can be kept essentially the same for all field of views. This allows for a compensation of these interference ripples as a systematical error.

[0021] According to at least one embodiment of the optical system, the diffusive element is in direct contact with the aperture. For example, the diffusive element is at least partially formed with the aperture and / or the optical element. It is also possible that the aperture comprises an adhesive or the like and is directly arranged at the aperture and / or the entrance side of the optical element.

[0022] According to at least one embodiment the optical system, the diffusive element is arranged at the distance from the aperture. For example, the optical system is arranged in a housing. In this case, the housing may comprise an opening through which light from the at least one field of view enters the housing. In particular, in the opening of the diffusive element may be arranged. Advantageously, this can make the arrangement of the diffusive element particularly easy and therefore cost-effective. Moreover, by arranging to diffusive element is a distance from the aperture the diffusive element can be easily replaced by a different diffusive element with other scattering properties, for example, if an application of the optical sensor changes. According to at least one embodiment the optical system, the optical element comprises a telecentric optical lens , in particular a telecentric optical micro-lens . By using a micro-lens , the optical system can be formed particularly small . By using a telecentric lens the influence of the si ze of the field of view and / or the angle of incidence of light at the entrance side of the optical can be reduced .

[0023] According to at least one embodiment of the optical system, at least one interference filter is arranged between the optical element and to detection plane . For example , the interference filter acts as a color filter . That is , the interference filter may be an optical bandpass filter since which is transmissive for only a certain wavelength range or a certain wavelength . In particular, by using such interference filter, a monochromatic image of the field of view is imaged in the detection plane .

[0024] The interference filter comprises , for example , a plurality of dielectric layers with di f ferent refractive indices stacked on top of each other . Preferably, the interference filter comprises a plurality of layer pairs having a first dielectric layer and a second dielectric layer which are alternately stacked . Materials of the dielectric layers may dependent on the wavelength range that is transmitted through by the interference filter . Examples for materials for suitable dielectric layers include SiO2 , SiN, A12O3 , TiO2 or comparable dielectric materials .

[0025] According to at least one embodiment of the optical system, the detector comprises a plurality of detector regions . In particular, each detector region is associated to a distinct field of view . Preferably, the detector regions are formed in the detector plane. For example, the detector regions form pixels of the detector.

[0026] In particular, the optical element is configured to image each field of view to its associated detector region in the detection plane. By forming a plurality of detector regions, a total field of view of the optical system may be segmented into a plurality of field of views. This allows, for example, for a more precise detection of an ambient light situation determined by a plurality of light sources or in case that the ambient light situation changes dynamically. In particular, an ambient light gradient can be obtained.

[0027] For example, all of detector regions comprises the same size. That is, in the detection plane all detector regions may have the same dimensions. Alternatively, the detector regions may differ in size. This can be advantageous, if, for example, the corresponding field of view also have different sizes.

[0028] The detector regions may have a rectangular, in particular a quadratic contour in view of the detection plane.

[0029] Alternatively or additionally, at least some of the detector regions may have a different contour, for example, a contour of a circuit, a ring, a circle segment or a ring segment.

[0030] According to at least one embodiment of the optical system, each detector region comprises a plurality of sub-regions. In particular, the blurred image of each field of view is generated such in the detection plane that at least some of the plurality of sub-regions are radiated by light of the associated field of view. For example, each detector region may comprise 4 or 9 or 12 sub-regions. Preferably, a widening or blurring of light of a certain field of view is performed such that in the corresponding detector region at least 3 of the sub-regions is radiated with light from the corresponding field of view. This is particularly advantageous if a Gaussian blur is carried out by the optical system. In this case a distortion or a geometrical misalignment may be compensated by interpellation since by using the information of the at least fees sub-regions the Gaussian blur can be exactly calculated by fitting. Further details with respect to such an interpellation are described in the document WO 2023 / 117468 Al.

[0031] According to at least one embodiment of the optical system, an angular scattering pattern of the diffusive element is more directed than a Lambertian scattering pattern, in particular as seen in an angular polar plot. Such a diffusive element is also known as a so-called slight diffuser. In particular, light leaving the diffusive element has a narrower angular distribution compact to a comparable Lambertian diffuser with, for example, the same geometrical dimension. In other words, light leaving the diffusive element is more directed than light leaving a comparable Lambertian diffuser. Such a narrow angular scattering pattern of the diffusive element allows for a Gaussian blur at the detection plane, wherein at the same time an angle spread can be comparably small. Hence, the aperture only blocks a relatively little amount of light leaving the diffusive element, resulting in a higher intensity of the image of the field of view at the detection plane.

[0032] According to at least one embodiment the optical system, the diffusive element comprises a grounded glass and / or a frosted glass . According to at least one embodiment of the optical system, the diffusive element comprises a matrix material filled with microstructures. For example, the matrix material is an epoxy. In particular, the matrix material is a so-called optic mold. For example, the matrix material is transparent for visible radiation and / or light to be detected by the detector. Preferably, light from the field of view entering the diffusive element only little interacts matrix material and is scattered at the microstructures. That is, by adjusting the size and / or the amount of microstructures in the matrix material, scattering properties of the diffusive element may be adjusted.

[0033] According to at least one embodiment of the optical system, the diffusive element comprises microstructures at the side facing the optical element. These microstructures may have different refractive indices, resulting in a scattering of light in the diffusive element.

[0034] According to at least one embodiment of the optical system, the diffusive element comprises a diffuser foil. The diffuser foil may further comprise an adhesive and may be glued directly at the aperture and / or the entrance side of the optical element.

[0035] According to at least one embodiment of the optical system, the diffusive element comprises a polymer dispersed liquid crystal. For example, the polymer dispersed liquid crystal comprises liquid crystal molecules dissolved in a polymer. A voltage may be applied to the polymer dispersed liquid crystal. In case that a voltage is applied to the polymer dispersed liquid crystal, the liquid crystal molecules may align, allowing incident light to pass through the polymer dispersed polymer. If the voltage is turned off, i.e. no voltage is applied to the polymer dispersed liquid crystal, the liquid crystal molecules may randomly orient and incident light is scattered. Hence, the usage of a polymer dispersed liquid crystal allows for a controlled switching of the diffusive element.

[0036] Furthermore, a multispectral optical sensor is described. In particular, the multispectral optical sensor comprises at least one optical system, preferably a plurality of optical systems described herein. That is, all features disclosed for the optical system are also disclosed for the multispectral optical sensor and vice versa.

[0037] According to at least one embodiment the multispectral optical sensor comprises a plurality of optic systems described herein, wherein each optical system comprises a color filter transmissive for light of a certain color. For example, each of the color filters is formed by an interference filter. In particular, different color filters are transmissive for different wavelength ranges. For example, the wavelength ranges are distinct. Alternatively, at least some of the wavelength ranges may overlap with each other .

[0038] In particular, each optical system forms a color channel of the multispectral optical sensor. In other words, by the color filters light from the at least one field of view is separated in different colors, i.e. in spectral components. Preferably, each detector of each optical system detects a monochromatic image of the field of view or field of views imaged to the corresponding detection plane by the optical element . This allows a spectral analysis of ambient light in each of the field of views .

[0039] According to at least one embodiment of the multispectral optical sensor, the plurality of optical elements forms a microlens array . For example , the plurality of optical elements of the plurality of optical systems are provided in an optical compound . Preferably, the optical compound is a microlens array .

[0040] According to at least one embodiment of the multispectral optic sensor, the detectors of the plurality of elements are formed as one piece . For example , the detectors , optionally each comprising a plurality of detector regions and / or subregions , are formed by a semiconductor chip . Preferably, the semiconductor chip is arranged on a carrier for electrically contacting the detectors such as a printed circuit board . On or inside the carrier a control unit may be further arranged, by which the detectors are supplied with power and operated . The control unit may be a microcontroller or an application speci fic integrated circuit (AS IC ) .

[0041] Furthermore , an electric device is speci fied . The electric device in particular comprises a multispectral optical sensor described herein . That is , all features disclosed for the multispectral optical sensor also disclosed for the electric device and vice versa .

[0042] According to at least one embodiment , the electric device comprises a photographic camera and a multispectral optic sensor . The photographic camera is configured to capture a scene . The multispectral optical sensor is configured to capture an ambient light situation in the scene . In particular, a dimension of the scene is smaller than a dimension of all fields of view of the multispectral optical sensor combined . The dimension of the scene and of the fields of view of the multispectral optical sensor is , for example , obtained in an obj ect space , which comprises the scene that is to be captured by the camera . By adj usting the fields of views of the multispectral optical sensor to be greater than the scene captured by the camera, and an ambient light situation in the scene can be precisely obtained .

[0043] The electric device may be a mobile phone , a digital camera, a notebook, a tablet computer or the like .

[0044] According to at least one embodiment of the electric device , the electric device further comprises a calculation unit that is configured to adapt a color of the captured photographic image of the scene in accordance with the ambient light situation captured by the multispectral optical sensor . That is , colors of the photographic image of the scene captured by the photographic camera may be improved by the information of the ambient light situation obtained by means of the multispectral optical sensor . For example , influences of the spectrum of the ambient light on the colors of the captured photographic image may be compensated by the calculation unit . This may result in a more truthful of color representation in the captured scene .

[0045] Further advantages and advantageous embodiments and further developments of the optical system, the multispectral optical sensor and the electric will become apparent from the following exemplary embodiments shown in connection with schematic drawings . Identical elements , elements of the same kind or elements having the same ef fect , are provided with the same reference signs in the figures . The figures and the proportions of the elements shown in the figures are not to be regarded as true to scale . Rather, individual elements may be shown exaggeratedly large for better representability and / or for better comprehensibility .

[0046] In the figures :

[0047] Figures 1 to 3 show an optical system described herein according to exemplary embodiments in schematic sectional views .

[0048] Figure 4 shows a polar plot illustrating an angular scattering pattern of a di f fusive element used for an optical system described here .

[0049] Figure 5 shows a multispectral optical sensor described herein according to an exemplary embodiment in a schematic sectional view .

[0050] Figure 6 shows an electric device described herein according to an exemplary embodiment .

[0051] The optical system 1 according to Figure 1 comprises an optical element 4 having a field of view 100 between a di f fusive element 2 and a detector 3 . For example , the detector 3 is a CMOS detector or a CCD detector . The optical element 4 is configured to image the field of view on a detection plane 30 of the detector 3 . The detection plane 30 is arranged in a focal plane of the optical element 4 . The optical element 4 is a telecentric lens and accordingly comprises two optical members 43 , 44 . An exit side 42 of the optical element 4 faces the detection plane . At an entrance side 41 of the optical element 4 opposing the exit side 42, an aperture 5 is arranged. The aperture 5 is preferably directly arranged at the entrance side 41.

[0052] At the aperture 5 the diffusive element 2 is arranged. For example, the diffusive element 2 is in direct contact with the aperture 5. The diffusive element 2 comprises, for example, a frosted glass or a grounded glass. The diffusive element 2 is configured to scatter light from the field of view 100 such that the blurred image 91 of the field of view is generated in the detector plane 30. In particular, an object in the field of view 100 appears at the detection plane as an out-of-focus image, although the detection plane 30 is arranged at a focal plane of the optical element 4. Due to the scattering in the diffusive element 2 the object and in particular the whole field of view 100 may appear blurred in the detector plane 30. The blurred image 91 comprises a Gaussian intensity distribution as illustrated in Figure 1. In other words, the blur applied by the diffusive element 2 is a Gaussian blur. If the optical system 1 is used in a multispectral optical sensor it is advantageous that the diffusive element 2 applies a Gaussian blur.

[0053] The aperture 5 is configured to block a wide angular spread, which may occur due to scattering in the diffusive element 2. Means in particular that the ratio of blurring is confined to a certain region of the detection plane 30.

[0054] Figure 2 illustrates that the optical system 1 may have a plurality of field of views 101 to 105. For example, the optical system 1 comprises a total field of view and the individual field of views 101 to 105 form segments of this total field of view. In contrast to Figure 1, in the optical system 1 according to Figure 2 , the detector 3 comprises a plurality of detector regions 31 to 35 . The detector regions 31 to 35 are arranged next to one another in the detection plane 30 . The optical element 4 is configured to image each field of view 101 to 105 to a corresponding detector region 31 to 35 . As illustrated in Figure 2 , in each detector region 31 to 35 a blurred image 91 to 91 of each corresponding field of view 101 to 105 is imaged .

[0055] Between the optical element 4 and to detection plane 30 an interference filter 6 is arranged . The interference filter 6 is formed as an optic bandpass filter which is transparent to a certain wavelength range . For example , the interference filter 6 is a color filter, such that the detector 3 detects a monochromatic image .

[0056] The aperture 5 blocks wide angles from the scattering pattern of the di f fusive element 2 such that no crosstalk between the detector regions 31 to 35 occurs . Furthermore , since widening from the scattering pattern of the di f fusive element to a block by the aperture 5 , light from all fields of view 101 to 105 essentially impinges the interference filter 6 with a similar or same angular distribution . That is , spectral variation due to di f ferent angles of incidents at the interference filter 6 can be reduced or eliminated .

[0057] In other aspects , the exemplary embodiment of Figure 2 comprises the same features , functionality and ef fects as the exemplary embodiment according to Figure 1 .

[0058] In contrast to the exemplary embodiment of Figure 2 , in the exemplary embodiment according to Figure 3 , the di f fusive element 2 is arranged at a distance from the aperture 5 . For example, the diffusive element 2 is arranged at a housing, i.e. an opening of a housing, in which the optical system 1 is arranged.

[0059] Figure 4 illustrates that an angular scattering pattern 71 of the diffusive element 2 is more directed than a Lambertian scattering pattern 71 in particular in an angular polar plot. The diffusive element 2 is in particular a diffusive element 2 as illustrated in connection with one of Figures 1 to 3.

[0060] That is, light leaving the diffusive element 2 has a narrower angular distribution as a comparable Lambertian diffuser In other words, light leaving to diffusive element 2 is more directed than light leaving a comparable Lambertian diffuser. Such a narrow angular scattering pattern of the diffusive element 2 allows for a Gaussian blur at the detection plane 30, wherein at the same time an angle spread can be comparably small.

[0061] Figure 5 illustrates a multispectral optical sensor 10 comprising a plurality of color channels 81 to 84. Each of the color channels 81 to 84 comprises a plurality of detector regions 31 to 35 and a corresponding color filter 61 to 64. The color filters 61 to 64 are each formed as an interference bandpass filter, transmissive for different wavelength ranges. The wavelength ranges can be distinct or partially overlap .

[0062] The optical sensor 10 further comprises a plurality of optical systems 1 as described, for example, in connection with Figure 2. That is, each of the optic systems 1 comprises an optical element 4 that is configured to image a plurality of field of views 101 to 105 to the corresponding detection regions 31 to 35. Each of the optical systems 1 furthermore comprises an aperture 5 and a di f fusive element 2 arranged directly at the aperture 5 .

[0063] The plurality of optical elements 4 is formed as a micro-lens array . That is , the plurality of optical elements 4 are provided in a compound .

[0064] The plurality of di f fusive elements 2 is formed in one piece . For example , a compound of the di f fusive elements 2 is a frosted glass or a grounded glass .

[0065] During operation, light from a plurality of field of views 101 to 105 is captured by the multispectral optical sensor 10 . By each optical element 4 each field of view 101 to 105 is imaged in the detection plane 30 . Before the light of the fields of views 101 to 105 strikes the detector regions 31 to 35 of each color channel 81 to 82 , the light is filtered by the color filters 61 to 64 such that in each color channel 81 to 84 monochromatic images of each field of view 101 to 105 is detected by the corresponding detector regions 31 to 35 . That is , light from the fields of view 101 to 105 , which may be segments of a total field of view of the multispectral optical sensor 10 , is separated in their spectral components by the color filters 61 to 64 and is space resolved captured by the detection regions 31 to 35 of each color channel 81 to 84 . Hence , by the multispectral optical sensor 10 the spectral information of an ambient light situation can be captured in each field of view 101 to 105 .

[0066] The detector regions 31 to 35 of each color channel 81 to 84 may be formed as part of a common semiconductor chip forming the detectors 3 . The detectors 3 is arranged on a carrier 7 , which may be a printed circuit board or the like via which the detector 3 can be contacted, operated and read out .

[0067] Figure 6 shows an electric device 11 and an arrangement of field of views 101 to 109 and a scene 13 . The electronic device 11 comprises a photographic camera 12 and a multispectral optical sensor 10 , for example as described in connection with Figure 5 . The scene 13 is captured by the photographic camera 12 as a photographic image . The field of views 101 to 105 cover a larger space in an obj ect plane of the scene 13 as the scene 13 . The multispectral optical sensor 10 is configured to measure an ambient light situation of the scene 13 . It is therefore advantageous that the field of views 101 to 105 cover a larger space than the scene 13 so that the ambient light situation can be precisely measured .

[0068] The electronic device 11 further comprises a calculation unit that is configured to adapt colors of the photographic image on the basis of the ambient light situation captured by the multispectral optical sensor 10 . In particular, influences of the spectrum of the ambient light on the colors of the photographic image may be compensated by the calculation unit . This may result in a more truthful of color representation in the photographic image .

[0069] The invention is not restricted to the exemplary embodiments of the description on the basis of said exemplary embodiments . Rather, the invention encompasses any new feature and also any combination of features which in particular comprises any combination of features in the patent claims and any combination of features in the exemplary embodiments , even i f this feature or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.

[0070] This patent application claims the priority of German patent application 102023123848.5, the disclosure content of which is hereby incorporated by reference.

[0071] References

[0072] 1 optical system

[0073] 2 di f fusive element detector

[0074] 4 optical element

[0075] 5 aperture

[0076] 6 interference filter

[0077] 7 carrier

[0078] 10 multispectral sensor

[0079] 11 electric device

[0080] 12 photographic camera

[0081] 13 calculation unit

[0082] 30 detection plane

[0083] 31...35 detector region

[0084] 41 entrance side exit side

[0085] 43 first optical member

[0086] 44 second optical member

[0087] 61...64 color filter

[0088] 70 scattering distribution

[0089] 71 scattering distribution of Lambert di f fusor

[0090] 81...84 color channel

[0091] 90 , 91...95 blurred image

[0092] 100 , 101...109 field of view

Claims

Claims1. An optical system (1) for a multi-spectral optical sensor (10) comprising- a diffusive element (2) ,- a detector (3) comprising a detection plane (30) ,- an optical element (4) with an entrance side (41) and an exit side (42) arranged between the diffusive element (2) and the detector (3) , and- an aperture (5) at the entrance side (41) of the optical element (4) arranged between the diffusive element (2) and the optical element (4) , wherein- the optical element (4) is configured to image at least one field of view (100, 101...109) to the detection plane ( 30 ) ,- the detection plane (30) is arranged in a focal plane of the optical element (4) ,- the diffusive element (2) is configured to scatter light from the field of view (100, 101...109) such that a blurred image (90, 91...95) of the field of view (100, 101...109) is generated in the detection plane (30) , and- the diffusive element (2) is in direct contact with the aperture (5) .

2. The optical system (1) according to claim 1, wherein the diffusive element (2) is arranged at a distance from the aperture (5) .

3. The optical system (1) according to one of the preceding claims, wherein the optical element (4) comprises a telecentric optical micro-lens.

4. The optical system (1) according to one of the preceding claims, wherein at least one interference filter (6) is arranged between the optical element (4) and the detection plane (30) .

5. The optical system (1) according to one of the preceding claims, wherein- the detector (3) comprises plurality of detector regions (31...35) and- each detector region (31...35) is associated to a distinct field of view (100, 101...109) .

6. The optical system (1) according to claim 5, wherein- each detector region (31...35) comprises a plurality of sub-regions ,- the blurred image of each field of view (100, 101...109) is generated such in the detection plane (30) that at least some of the plurality of sub-regions are radiated by light of the associated field of view (100, 101...108) .

7. The optical system (1) according to one of the preceding claims, wherein angular scattering pattern of the diffusive element (2) is more directed than a Lambertian scattering pattern.

8. The optical system (1) according to one of the preceding claims, wherein the diffusive element (2) comprises at least one of the following glasses: a grounded glass, a frosted glass.

9. The optical system (1) according to one of the preceding claims, wherein- the diffusive element (2) comprises a matrix material (20) filled with microstructures and- the matrix material is an epoxy.

10. The optical system (1) according to one of the preceding claims, wherein the diffusive element (2) comprises microstructures at a side facing the optical element(4) .

11. The optical system (1) according to one of the preceding claims, wherein the diffusive element (2) comprises a polymer dispersed liquid crystal.

12. A multispectral optical sensor (10) comprising a plurality of optical system (1) according to one of the preceding claims, wherein each optical system (1) comprises a color filter (61...64) transmissive for a light of a certain color.

13. The multispectral optical sensor (10) according to claim 12, wherein the plurality of optical elements (4) forms a micro-lens array.

14. The multispectral optical sensor (10) according to claim 12 or 13, wherein the detectors (3) of the plurality of optical elements (1) are formed as one piece.

15. An electric device (11) comprising a photographic camera(12) and multispectral optical sensor (10) according to one of claims 12 to 14, wherein- the photographic camera (12) is configured to capture a photographic image of a scene (13) ,- the multispectral optical sensor (10) is configured to capture an ambient light situation in the scene (13) , and- a dimension of the scene is smaller than all fields of view (100, 101...109) of the multispectral optical sensor(10) .

16. The electric device (11) according to claim 15 further comprising a calculation unit configured to adapt a color of the captured photographic image of the scene(13) in accordance with the ambient light situation captured by the multispectral optical sensor (10) .

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