Patent Publication Number: US-2021168269-A1

Title: Vehicle assistance systems

Description:
TECHNICAL FIELD 
     The disclosure describes vehicle assistance systems, in particular, optical vehicle assistance systems. 
     BACKGROUND 
     Automated driving technology makes use of optical sensor systems to detect roadway objects which can include infrastructure, other vehicles, or pedestrians. Increasing the range of detectability, improving signal to noise, and improving the recognition of objects continue to be fields of development. Systems that can provide at a distance, conspicuity, identification, and data via optical sensor systems, while being substantially visually imperceptible, may be advantageous. For example, signs may serve a dual purpose, where the sign may be visually read in the traditional way, and simultaneously the optical system can sense an invisible code that assists an onboard driving system with automated driving. 
     Other industry problems regarding optical sensors include the need to improve detection in adverse conditions that may affect light path and quality, which can cause signal to noise problems for the detection of infrastructure, vehicles, or pedestrians. 
     SUMMARY 
     The disclosure describes an example vehicle assistance system including a light sensor, a pixelated filter array adjacent the light sensor, and a full-field optically-selective element adjacent the pixelated filter array. The optically-selective element is configured to selectively direct an optical component of light incident on the optically-selective element across the pixelated filter array to the light sensor. In some examples, the vehicle includes a land, sea, or air vehicle. 
     The disclosure describes an example technique including receiving, by a full-field optically-selective element of a vehicle assistance system, a light signal from an object. The example technique includes selectively directing, by the full-field optically-selective element, an optical component of the light signal through a pixelated filter array to a light sensor. A computing device may receive an image data signal from the image sensor in response to the light signal, compare the image data signal with a plurality of reference images in a lookup table, and generate, in response to the comparison, an output signal. 
     The details of one or more aspects of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The foregoing and other aspects of this invention are made more evident in the following Detailed Description, when read in conjunction with the attached Figures. 
         FIG. 1  is a conceptual diagram of an example vehicle assistance system including a light sensor, a pixelated filter array, and a full-field optically-selective element. 
         FIG. 2  is a conceptual diagram of an example system including the vehicle assistance system of  FIG. 1  for detecting light deflected by an object. 
         FIG. 3  is a conceptual diagram of an example system including a vehicle assistance system including cascaded optically-selective elements for detecting light deflected by an object. 
         FIG. 4  is a conceptual diagram of an example optically-selective element including a cross-type dichroic splitter. 
         FIG. 5A  is a conceptual diagram of an example optically-selective element including a trichroic prism. 
         FIG. 5B  is a conceptual diagram of an example optically-selective element including a trichroic prism. 
         FIG. 6A  is a conceptual diagram of a Bayer color filter array. 
         FIG. 6B  is a conceptual diagram of a red/clear/clear/clear (RCCC) color filter array. 
         FIG. 6C  is a conceptual diagram of a monochrome filter array. 
         FIG. 6D  is a conceptual diagram of a red/clear/clear/blue (RCCB) color filter array. 
         FIG. 6E  is a conceptual diagram of a red/green/clear/blue (RGCB) color filter array. 
         FIG. 7A  is a conceptual diagram of a full-field optically-selective element configured to reflect an infrared wavelength band and transmit visible light. 
         FIG. 7B  is a conceptual diagram of a full-field optically-selective element configured to reflect a first infrared wavelength band and transmit a second infrared wavelength band and visible light. 
         FIG. 7C  is a conceptual diagram of a full-field optically-selective element configured to reflect a first and a second infrared wavelength band and transmit a third infrared wavelength band and visible light. 
         FIG. 7D  is a conceptual diagram of a full-field optically-selective element configured to reflect an infrared wavelength band and transmit visible light and an ultraviolet wavelength band. 
         FIG. 7E  is a conceptual diagram of a full-field optically-selective element configured to reflect an ultraviolet wavelength band and transmit visible light and an infrared wavelength band. 
         FIG. 7F  is a conceptual diagram of a full-field optically-selective element configured to reflect an infrared wavelength band and an ultraviolet wavelength band and transmit visible light. 
         FIG. 7G  is a conceptual diagram of a full-field optically-selective element configured to reflect first red and green wavelength bands and transmit second and green wavelength bands and a blue wavelength band. 
         FIG. 7H  is a conceptual diagram of a full-field optically-selective element configured to reflect an s-polarized red wavelength band, and transmit a p-polarized red wavelength bands, and transmit green and blue wavelength bands. 
         FIG. 8  is a conceptual diagram of an example optically-selective element including a lens. 
         FIG. 9  is a conceptual diagram of an example field optically-selective element including a curved reflective interface. 
         FIG. 10  is a conceptual diagram of an example optically-selective element including an inclined reflector. 
         FIG. 11A  is a conceptual diagram of a vehicle including an automated driver assistance system (ADAS). 
         FIG. 11B  is a conceptual partial front view of the vehicle of  FIG. 11A . 
         FIG. 12  is a flowchart of an example technique for sensing, by a vehicle assistance system, an optical signal. 
         FIG. 13  is a conceptual diagram of coded pattern readable by a vehicle assistance system. 
         FIG. 14  is a chart showing a spectrum of an example narrow band blocking multilayer optical film (MOF). 
         FIG. 15A  is a chart showing a relationship between wavelength, polar angle, and reflectance of the MOF of  FIG. 14  in air. 
         FIG. 15B  is a chart showing a relationship between wavelength, polar angle, and transmittance of the MOF of  FIG. 14  in air. 
         FIG. 16A  is a chart showing a relationship between wavelength, polar angle, and reflectance of the MOF of  FIG. 14  in glass. 
         FIG. 16B  is a chart showing a relationship between wavelength, polar angle, and transmittance of the MOF of  FIG. 14  in glass. 
         FIG. 16C  is a chart showing a relationship between wavelength, polar angle, and p-polarized transmittance of the MOF of  FIG. 14  in glass. 
         FIG. 16D  is a chart showing a relationship between wavelength, polar angle, and s-polarized transmittance of the MOF of  FIG. 14  in glass. 
         FIG. 17  is a chart showing a spectrum of an example dual band blocking multilayer optical film (MOF). 
         FIG. 18A  is a chart showing a relationship between wavelength, polar angle, and reflectance of the MOF of  FIG. 17  in air. 
         FIG. 18B  is a chart showing a relationship between wavelength, polar angle, and transmittance of the MOF of  FIG. 17  in air. 
     
    
    
     It should be understood that features of certain Figures of this disclosure may not necessarily be drawn to scale, and that the Figures present non-exclusive examples of the techniques disclosed herein. 
     DETAILED DESCRIPTION 
     The disclosure describes vehicle navigation systems. In some examples, vehicle navigation systems according to the disclosure may be used to decode patterns or optical signatures of optically encoded articles, for example, navigation assistance or traffic sign pattern or objects. 
     Vehicle assistance systems may include automated driver assistance systems (ADAS). Object sensing and detection in ADAS systems, for example, by ADAS cameras or optical sensors may pose challenges in terms of spectral resolution and polarization. In some examples, systems and techniques according to the disclosure may provide a way to increase signal to noise in a compact and practical way that is compatible with current imager systems. Optical filters may be combined with imager pixel arrays. In some examples, beamsplitters may be used to enable high efficiency, compact designs. In some examples, an a beamsplitter may enable high spatial resolution for the wavelength being sensed or analyzed. For example, dedicating an entire imager to a particular wavelength or band (for example, centered at 840 nm), may provide a high resolution of variation for that wavelength or band (for example 840 nm) over the entire image, in contrast with an imager sensing different bands or wavelengths of which only a few pixels may be associate with the wavelength or band of interest. 
     In some examples, a system functions as a transceiver and includes an optical filter component that modifies the wavelength of light incident on an imaging system enabling it to decode patterns or optical signatures of optically encoded articles. The system may include an optically-selective filter (for example, wavelength-selective, polarization-selective, or both) that selectively blocks visible or non-visible light (UV and/or IR) wavelengths or linear or circular polarization states to enhance the detection of items such as IR coded signs or unique spectral features of objects, for example, objects encountered by or in the vicinity of a land, air, or sea vehicle. The filter can be used as a freestanding element or as a beamsplitter component. The filter may be used in combination with the one or more filter of an imager pixel array to analyze images having non-visible spectral features. Unique signatures can be compared to a look up table of known signatures and meanings. 
     In some examples, the angular wavelength shifting properties of a multilayer optical film (MOF) may be used to transform a beamsplitter imager into a hyperspectral camera in vehicle assistance systems. The MOF may include birefringement MOFs. Such MOFs which may exhibit good off-angle performance and relatively high angle shift. For example, an angle-shifting optically-selective filter may be immersed in a beamsplitter in optical communication with an imager. In some examples, a pixel array adjacent the imager includes at least one clear pixel. The pixel array may be in contact with the imager, or spaced from, but optically coupled with, the imager. The system further includes an angle-limiting element for introducing light having a range angles of incidence at the filter surface. The system may include two imagers, one primarily for spectroscopy and the other for imaging. This may enable a high efficiency imaging spectrometer or spectropolarimeter for ADAS or vehicle assistance systems. Thus, challenges in detection for ADAS cameras in terms of spectral resolution and polarization may be addressed. For example, both image information and spectral/polarization analysis of a scene may be performed. 
     In this disclosure, “visible” refers to wavelengths in a range between about 400 nm and about 700 nm, and “infrared” (IR) refers to wavelengths in a range between about 700 nm and about 2000 nm, for example, wavelengths in a range between about 800 nm and about 1200 nm, and includes infrared and near-infrared. Ultraviolet (UV) refers to wavelengths below about 400 nm. 
       FIG. 1  is a conceptual diagram of an example vehicle assistance system  10  including a light sensor  12   a , a pixelated filter array  14   a , and a full-field optically-selective element  16  (also referred to as a “wavelength selective element”). The term “full-field” indicates that optically-selective element  16  optically covers an entirety of light sensor  12   a  and pixelated filter array  14   a , such that all light incident on light sensor  12   a  or pixelated filter array  14   a  passes through optically-selective element  16 . For example, light from optically-selective element  16  may be output parallel, angled, convergent, or divergent, or otherwise directed to substantially optically cover light sensor  12   a  or pixelated filter array  14   a . In some examples, system  10  may include one or more optical elements to guide light from optically-selective element  16  to optically spread across or cover light sensor  12   a  or pixelated filter array  14   a . Pixelated filter array  14   a  is adjacent (for example, in contact with, or spaced from and optically coupled with) light sensor  12   a . Optically-selective element  16  is adjacent (for example, in contact with, or spaced from and optically coupled with) pixelated filter array  14   a.    
     Optically-selective element  16  may include an optical filter, a multilayer optical film, a microreplicated article, a dichroic filter, a retarder or waveplate, at least one beamsplitter, or combinations thereof. Optically-selective element  16  may include glass, one or more polymers, or any suitable optical material or combinations thereof. In the example shown in  FIG. 1 , full-field optically-selective element  16  includes a beamsplitter. In some examples, the beamsplitter includes a polarization beamsplitter, a wavelength beamsplitter, a dichroic prism, a trichroic prism, or combinations thereof. The beamsplitter includes two triangular prisms joined (for example, by an adhesive) at their bases forming interface  18 . A dichroic coating or layer may be provided at interface  18  to split an arriving light signal into two or more spectral components, for example, components having different wavelengths or polarization states. Optically-selective element  16  may be wavelength-selective, polarization-selective, or both. An optical coating or filter may be provided on or adjacent (for example, in contact with) one or more faces of optically-selective element  16  to filter, for example, selectively absorb, transmit, or change predetermined wavelengths or polarization states. In some examples, the optical coating may include a waveplate or retarder, for example, a half-wave retarder or quarter-wave retarder, to change the polarization direction, or to interchange linearly polarization to circular polarization. In some examples, the optical coating includes a spatially variant wavelength-selective filter. In this disclosure, the term “polarization states” includes linear and circular polarization states. In some examples, system  10  includes at least one polarizing filter across an optical path arriving at light sensor  12   a . In some examples, optically-selective element  16  includes at least one of an ultraviolet-(UV) transmitting, visible-reflecting multilayer film filter; an ultraviolet-(UV) reflecting, visible-transmitting multilayer film filter; an edge filter; a transmission notch filter; a reflective notch filter; or a multiband filter. 
     As shown in  FIG. 1 , optically-selective element  16  splits a light signal L incident on optically-selective element  16  into two optical components, C 1  and C 2 , and selectively directs optical component C 1  of light L through pixelated filter array  14   a  to light sensor  12   a . In some examples, the second optical component C 2  is discarded. In other examples, second optical component C 2  is sent to another light sensor. For example, light sensor  12   a  may include a first light sensor, and system  10  may include a second light sensor  12   b . Likewise, pixel filter array  14   a  may include a first pixel filter array, and system  10  may include a second pixel filter array  14   b . Thus, optically-selective element  16  may selectively direct second optical component C 2  through second pixelated filter array  14   b  to second light sensor  12   b . Pixelated filter arrays  14   a ,  14   b  may cause predetermined components of light to be incident on light sensors  12   a  and  12   b  in discrete regions, or pixels. Thus, each pixel may include sub-pixels for one or more predetermined channels or components of light. For example, each pixel of pixelated filter array  14   a ,  14   b  may include one or more of red, green, blue, or clear sub-pixels. Some examples of sub-pixel configurations of pixelated filter arrays are described with reference to  FIGS. 6A to 6E . 
     In some examples, pixelated filter arrays  14   a ,  14   b  may be respectively integrated with light sensors  12   a  and  12   b , for example, fabricated in the same integrated chip. Thus, pixelated filter arrays  14   a ,  14   b  may be grown on or otherwise in immediate contact with light sensors  12   a  and  12   b.    
     First and second optical components C 1  and C 2  may differ in at least one wavelength band or polarization state, or combinations thereof, with C 2  typically being an optical complement to C 1 . In some examples, first optical component C 1  includes at least a first ultraviolet, visible, or infrared wavelength band (centered at λ 1 ), and second optical component C 2  includes at least a second ultraviolet, visible, or infrared band (centered at λ 2 ) different from the first band. In some examples, the first wavelength band has a bandwidth less than 200 nm, and wherein the second wavelength band comprises the spectral complement of the first wavelength band. In some examples, the first wavelength band has a bandwidth less than 100 nm, or less than 50 nm. In some examples, the first wavelength band includes at least one visible wavelength band, and wherein the second wavelength band includes at least one near-infrared band. In some examples, the first wavelength band includes at least one visible wavelength band and at least a first near-infrared band, and the second wavelength band includes at least a second near-infrared band. In some examples, the first wavelength band includes at least one visible wavelength band, and the second wavelength band includes at least one UV band. In some examples, the first wavelength band includes at least a first one visible wavelength band, and the second wavelength band includes at least a second visible wavelength band. In some examples, first optical component C 1  includes a first polarization state, and second optical component C 2  includes at least a second polarization state different from the first polarization states. In some examples, first light sensor  12   a  functions as an imaging sensor, and second light sensor  12   b  functions as a hyperspectral sensor. 
     In some examples, optically-selective element  16  includes an angle-limiting optical element. In some examples, in addition to, or instead of, the angle-limiting optical element, optically-selective element  16  includes an angle-spreading optical element. The angle-limiting or angle-spreading element may include a refractive element, a diffractive element, a lens, a prism, a microreplicated surface or article, or combinations thereof. In some examples, optically-selective element  16  including an angle-spreading optical element may function as a spectrometer, and emit different wavelengths at different angles. 
     System  10  may include a computing device  20 . Light sensors  12   a ,  12   b  may be in electronic communication with computing device  20 . Computing device  20  may include a processor  22  and a memory  24 . Processor  22  may be configured to implement functionality and/or process instructions for execution within computing device  20 . For example, processor  22  may be capable of processing instructions stored by a storage device, for example, memory  24 , in computing device  20 . Examples of processor  22  may include, any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or equivalent discrete or integrated logic circuitry. Memory  24  may include a lookup table that includes a plurality of reference images. 
     Computing device  20  may receive at least one image data signal from light sensors  12   a ,  12   b , and processor  22  may be configured to compare the image data signal with the plurality of reference images. Processor  22  may be configured to, based on the comparison, generate an output signal. Computing device  20  may send the output signal to a controller of the vehicle to cause the controller to take an action based on the output signal. The action may include a physical action, a communications action, an optical transmission, or controlling or activating a sensor. In some examples, computing device  20  may itself be a controller for the vehicle. For example, computing device  20  may direct navigation, and control movement of the vehicle. The output signal may be configured to one or more of adjust a navigation action, cause retrieval over a communications network of a response signal, cause retrieval over the communications network of vehicle environment information, or cause sending of a communication signal over the communications network to a target vehicle. The sensing and or communication may take place with another vehicle, but can also take place with part of the infrastructure (such as a sign), or with a person. In some examples, computing device  20  may communicate with a transceiver that can be on a different vehicle, an infrastructure component, or on a person. 
       FIG. 2  is a conceptual diagram of an example system  30  including vehicle assistance system  10  of  FIG. 1  for detecting light deflected by an object  31 . Object  31  may include any object encountered by or in the vicinity of a land, air, or sea vehicle. For example, object  31  may include traffic signs, construction equipment or signs, pedestrian jackets or clothing, retroreflective signs, billboards, advertisements, navigation markers, milestones, bridges, pavement, road markings, or the like. In some examples, system  30  includes a light transmitter  32  configured to transmit light towards object  31 . Thus, light sensor  12   a ,  12   b  may be configured to sense light reflected or retroreflected by object  31  from light transmitter  32 . In some examples, system  10  may include a particular light transmitter, and object  31  may reflect ambient light, for example, sunlight, or light from multiple sources, towards object  31 . In some examples, system  30  includes optically-selective element  16  including an optical filter, instead of a beamsplitter, as shown in  FIG. 2 . 
     As shown in  FIG. 2 , in some examples, system  30  includes an enclosure  34 . Enclosure  34  may include a rigid housing, or a semi-rigid or soft enclosure enclosing light sensors  12   a ,  12   b , pixelated filter array  14   a ,  14   b , and optically-selective element  16 . Enclosure  34  may protect the optical components from stray light, and may be substantially opaque, so that light sensors  12   a ,  12   b  are protective from inadvertent exposure to light. In some examples, enclosure  34  defines an optical window  36  to selectively admit light to optically-selective element  16  and ultimately to light sensors  12   a ,  12   b . Optical window  36  may include a lens (for example, a fish-eye lens), a refractive element, an optical filter, or be substantially optically clear. Enclosure  34  may be secured or mounted at a suitable location, region, or component of a vehicle, for example, an air, sea, or land vehicle. In some examples, enclosure  34  may be secured such that optical window  36  faces a predetermined orientation, for example, in a forward direction, a backward direction, or sideways, relative to a direction of travel of the vehicle. In some examples, multiple enclosures  34  may enclose multiple systems  10  or  30  at different locations or oriented in different directions about or on the vehicle. While systems  10  or  30  may include single optically-selective element  16 , in other examples, example systems may include two or more optically-selective elements, for example, as described with reference to  FIG. 3 . 
       FIG. 3  is a conceptual diagram of an example system  40  including a vehicle assistance system including cascaded optically-selective elements  16   a ,  16   b  for detecting light deflected by object  31 . System  40  is substantially similar to example system  30 , but includes two optically-selective elements  16   a  and  16   b  substantially similar to single optically-selective element  16  described with reference to  FIGS. 1 and 2 . System  40  includes three light sensors  12   a ,  12   b ,  12   c , and three pixelated filter arrays  14   a ,  14   b ,  14   c . First optically-selective element  16   a  splits incident light into two components, the first component being directed through first pixelated filter array  14   a  to first light sensor  12   a . The second component is directed to second optically-selective element  16   b , which splits the second component into two further components (third and fourth components), the third component being selectively directed through second pixelated filter array  14   b  to second light sensor  12   b , and the fourth component being selectively directed through third pixelated filter array  14   c  to third light sensor  12   c . System  40  may include three or more optically-selective elements and four or more light sensors and pixelated filter arrays, likewise splitting and selectively directing a series of light components to respective sensors. The different components may differ in at least one wavelength band or polarization state. 
     Instead of, or in addition to, a beamsplitter, systems  10 ,  30 , or  40  may include other optically-selective elements, for example, those described with reference to  FIGS. 4 and 5 . 
       FIG. 4  is a conceptual diagram of an example optically-selective element  16   c  including a cross-type dichroic splitter. The cross-type dichroic splitter (also known as an “X-cube” or “RGB prism”, for example, available from WTS Photonics Technology Co., Ltd, Fuzhou, China) may be defined by two dichroic interfaces  18   b  and  18   c  embedded in glass or another suitable optical medium. In some examples, interface  18   b  may define a red and green filter, while interface  18   c  may define a cyan filter transverse to interface  18   b . As seen in  FIG. 4 , optically-selective element  16   c  may substantially direct three components C 1 , C 2 , and C 3  of incident light L along three distinct directions. In some examples, three respective light sensors may separately detect the three components. C 1 , C 2 , and C 3  may correspond to any suitable predetermined combination of UV, visible, or IR wavelengths, and polarization states. In some examples, C 1 , C 2 , and C 3  may correspond to red, green, and blue channels. 
       FIG. 5A  is a conceptual diagram of an example optically-selective element  16   d  including a trichroic prism. The trichroic prism may be defined by glass or any suitable optical medium, and include two dichroic interfaces  18   d  and  18   e  at a predetermined angle. Dichroic interfaces  18   d  and  18   e  may act as dichroic filters and direct different components, for example, C 1 , C 2 , and C 3  of incident light L, along three distinct directions. In some examples, three respective light sensors may separately detect the three components. C 1 , C 2 , and C 3  may correspond to any suitable predetermined combination of UV, visible, or IR wavelengths (for example, bands centered at predetermined wavelengths λ 1 , λ 2 , and λ 3 ) and polarization states. In some examples, C 1 , C 2 , and C 3  may correspond to red, green, and blue channels. 
       FIG. 5B  is a conceptual diagram of an example optically-selective element  16   e  including a trichroic prism. The trichroic prism may be defined by glass or any suitable optical medium, and include dichroic interfaces between prismatic or refractive elements. The dichroic interfaces may act as dichroic filters and direct different components, for example, C 1 , C 2 , and C 3  of incident light L, along three distinct directions. In some examples, three respective light sensors may separately detect the three components. C 1 , C 2 , and C 3  may correspond to any suitable predetermined combination of UV, visible, or IR wavelengths (for example, bands centered at predetermined wavelengths λ 1 , λ 2 , and λ 3 ) and polarization states. In some examples, C 1 , C 2 , and C 3  may correspond to red, green, and blue channels. 
     Instead of, or in addition to, pixelated filter arrays  14   a ,  14   b , systems  10 ,  30 , or  40  may include other pixelated filter arrays, for example, those described with reference to  FIGS. 6A to 6E . 
       FIG. 6A  is a conceptual diagram of a Bayer color filter array. A Bayer color filter array includes a red, a blue, and two green pixels in each block (RGGB). While a particular relative arrangement of the red, green, and blue pixels is shown in  FIG. 6A , other geometric arrangements may also be used. A Bayer color filter array yields information about the intensity of light in red, green and blue wavelength regions by passing these wavelengths to discrete regions of an adjacent image sensor. The raw image data captured by the image sensor is then converted to full-color image by a demosaicing algorithm with intensities of all three primary colors (red, green, blue) represented at each pixel or block. A Bayer color filter array has 25% R, 25% B, and 50% G pixels. 
       FIG. 6B  is a conceptual diagram of a red/clear/clear/clear (RCCC) color filter array. For vehicle assistance systems or advanced driver assistance systems (ADAS), multiple cameras may capture the scene around a vehicle to assist during transport. Typical machine vision algorithms may use or analyze only the intensity of the light. But for ADAS, special color filter arrays may be produced to provide color information. One useful color information channel is in the red channel, which helps localize the region of interest of the image, such as traffic light, car rear-light, etc. Red/clear (RCCC) color filter arrays may be used for vehicle assistance use. Unlike Bayer sensors, RCCC sensors use clear filters instead of the blue and the two green filters in the 2×2 pixel pattern, and have 75% clear pixels which give the light intensity information and no color information. 25% of the pixels have RED color information. The red filter remains the same. A “clear filter” is the same concept as monochrome sensors. The advantage of this format is that it may provide more sensitivity to light and therefore may work better in dark conditions. Thus, in some examples, pixelated filter arrays according to the disclosure may include at least one clear pixel, for example, a plurality of clear pixels. 
       FIG. 6C  is a conceptual diagram of a monochrome filter array. A monochrome array has 100% “clear” pixels which give light intensity information and no color information. This is acceptable for either monochrome viewing or for analytics applications where no color information is required (for example, driver monitoring). The advantage of this format is that it provides more sensitivity to light and therefore may work better in dark conditions. 
       FIG. 6D  is a conceptual diagram of a red/clear/clear/blue (RCCB) color filter array. RCCB is similar to Bayer (RGGB) with the exception that half of the pixels are clear instead of green. The advantage of this format is that clear pixels provide more low-light sensitivity, thus leading to lower noise. This format has potential to allow the same camera for visual as well as analytic application. 
       FIG. 6E  is a conceptual diagram of a red/clear/clear/blue (RCCB) color filter array. RGCB is similar to Bayer (RGGB) with the exception that half of the green pixels are clear instead of green. The advantage of this format is that clear pixels provide more low-light sensitivity, thus leading to lower noise. This format has potential to allow the same camera for visual as well as analytic application. 
     The clear pixels may be transmissive in one or more of visible, infrared, or ultraviolet wavelengths, or combinations thereof. In some example, the clear pixels are transmissive to substantially only visible wavelengths. In some examples, the clear pixels are transmissive to substantially only infrared wavelengths. In some examples, the clear pixels are transmissive to substantially only ultraviolet wavelengths. In some examples, the clear pixels are transmissive to substantially only visible and infrared wavelengths. 
     While different color filter arrays are available, systems that do not include an optically-selective element may present problems. For example, in the absence of an optically-selective element, a vehicle assistance system or ADAS may exhibit limited spectral resolution in IR and UV, a lack of polarization information, signal loss if a polarizer is used, loss of signal due to filtering, and poor contrast between channels. 
     In example systems according to the disclosure, one or more optically-selective elements may address one or more of these problems, for example, by separating channels to provide better contrast, eliminating or attenuating interfering wavelengths, allowing improved spectral resolution in IR and UV, and yielding polarization information. Some examples, of splitting of light into different components by example wavelength selective elements is described with reference to  FIGS. 7A through 7H . 
       FIG. 7A  is a conceptual diagram of a full-field optically-selective element  16   f  configured to reflect an infrared wavelength band and transmit visible light.  FIG. 7B  is a conceptual diagram of a full-field optically-selective element  16   f  configured to reflect a first infrared wavelength band and transmit a second infrared wavelength band and visible light.  FIG. 7C  is a conceptual diagram of a full-field optically-selective element  16   h  configured to reflect a first and a second infrared wavelength band and transmit a third infrared wavelength band and visible light.  FIG. 7D  is a conceptual diagram of a full-field optically-selective element  16   i  configured to reflect an infrared wavelength band and transmit visible light and an ultraviolet wavelength band.  FIG. 7E  is a conceptual diagram of a full-field optically-selective element  16   j  configured to reflect an ultraviolet wavelength band and transmit visible light and an infrared wavelength band.  FIG. 7F  is a conceptual diagram of a full-field optically-selective element  16   k  configured to reflect an infrared wavelength band and an ultraviolet wavelength band and transmit visible light.  FIG. 7G  is a conceptual diagram of a full-field optically-selective element  16   l  configured to reflect first red and green wavelength bands and transmit second and green wavelength bands and a blue wavelength band.  FIG. 7H  is a conceptual diagram of a full-field optically-selective element  16   m  configured to reflect an s-polarized red wavelength band, and transmit a p-polarized red wavelength bands, and transmit green and blue wavelength bands. Detecting polarization with reduced or minimal signal loss is enabled by using a narrow band s-pol reflector. Image analysis between the two s- and p-polarized images can be used for polarization analysis of a scene. Detection of pavement conditions is one example such as determining if pavement is wet. Another example is eliminating surface glare so that the spectrum of a pavement marking can be analyzed. 
     While in the examples of  FIGS. 7A to 7H , a filter is in the cube (diagonal interface), in other examples, a filter may be disposed on a surface of the cube, in addition, or instead of, to a filter on the cube diagonal. In some examples, the diagonal film may include be a half mirror, used in combination with a cube surface filter that that is wavelength selective. The filters may include narrow band reflective as well as narrow band transmission filters. 
       FIG. 8  is a conceptual diagram of an example optically-selective element  16   m  including a lens  42 . Lens  42  creates a range of incidence angles on a filter in optically-selective element  16   n  (for example, a multilayer optical film), which results in wavelength shift directed upwards. The wavelength shift can be detected by an image sensor adjacent the upper face. A second lens  44  may converge light onto a second image sensor adjacent the right face of optically-selective element  16   m.    
       FIG. 9  is a conceptual diagram of an example field optically-selective element  16   o  including a curved reflective interface  46 . In some examples, curved reflective interface  46  may include a curved multilayer optical film (MOF). The curvature creates a range of angles of incidence that are then mapped to pixel locations. Each pixel location senses the effect of different reflection spectrum. While one specific curve is illustrated in  FIG. 9 , interface  46  may be disposed along any suitable geometric curve, compound curve, surface, or compound surface, including linear segments, circular arcs, ellipsoidal arcs, parabolic or hyperbolic arcs, plane segments, spherical surfaces, ellipsoid surfaces, paraboloid surfaces, hyperboloid surfaces, freeform surfaces or arcs, or combinations thereof. In some examples, as shown in  FIG. 9 , interface  46  includes an IR-reflecting visible-transmitting film. The angular wavelength shift occurs in the IR and provides a ray spread to the top face, while visible light passes through the right face. Imagers can be disposed adjacent the respective faces to capture the separated components. 
       FIG. 10  is a conceptual diagram of an example optically-selective element  16   p  including an inclined reflector  48 . Inclined reflector  48  may be used to create two incidence angles. In some examples, inclined reflector  48  may be curved, similar to curved interface  46 . The inclined or curved reflector  48  may separate light into two components, as shown in  FIG. 10 . Optically-selective element  16   o  may include filter  18   f  at the diagonal interface. 
       FIG. 11A  is a conceptual diagram of a vehicle  50  including an automated driver assistance system (ADAS).  FIG. 11B  is a conceptual partial front view of vehicle  50  of  FIG. 11A . The ADAS may include system  10  described with reference to  FIG. 1 , or systems  30  or  40 . For example, systems  10 ,  30 , or  40  may be mounted or enclosed in an enclosure (for example, enclosure  34  or similar enclosures) secured to a body or frame  52  of vehicle  50 . System  10  may detect light  54  deflected by an object  56 . In some examples, vehicle  50  may include a light source  58  sending light  60  towards object  56  that is deflected by object  56  (for example, reflected or retroreflected) to system  10 . Light source  58  may include headlights or vehicle lights  62 , or a dedicated light source  64  distinct from headlights or vehicle lights  62  (or combinations thereof). While a car is shown in  FIG. 11A , vehicle  50  may include any land, sea, or air vehicle. 
       FIG. 12  is a flowchart of an example technique for sensing, by a vehicle assistance system, an optical signal. The example technique of  FIG. 12  is described with reference to system  10  of  FIG. 1  and system  30  of  FIG. 2 . However, the example technique may be implement using any suitable system according to the disclosure. In some examples, the example technique includes receiving, by full-field optically-selective element  16  of vehicle assistance system  10 , light signal L from object  31  ( 70 ). The example technique includes selectively directing, by optically-selective element  16 , an optical component C 1  of light signal L through pixelated filter array  14   a  to light sensor  12   a  ( 72 ). 
     The example technique includes receiving, by computing device  20 , an image data signal from image sensor  12   a  in response to light signal L ( 74 ). In some examples, the image data signal may correspond to a single image captured at one instant of time. In other examples, the image data signal may include a series of images captured in real-time, near-real time, or at intermittent times. In some examples, light source  32  may illuminate object  31  with a light signal having a predetermined frequency or a predetermined temporal pattern, and object  31  may deflect a response signal having a response frequency or response temporal pattern. In some such examples, the receiving the light signal L ( 74 ) may be synchronized with, or asynchronous to, the light signal transmitted to object  31 . 
     The example technique includes comparing, by computing device  20 , the image data signal with a plurality of reference images in a lookup table ( 76 ). The comparing may be for a single image captured at a single instance of time, or may include a series of comparisons for a series of images captured in real-time, near-real time, or at intermittent times. In some examples, the lookup table may be implemented by or replaced with a machine learning module, for example, a deep-learning model, or a convolutional neural network, or a pattern recognition module. Thus, in some examples, entries of the lookup table may correspond to outputs of the machine learning module or pattern recognition module associated with images. In some examples, the light signal L may be generated by object  31  in response to a light signal having a spectrum S(λ) generated by light source  32 . Image sensor  12   a  and pixelated filter array  14   a  may have a first wavelength transmission function T 1 (λ) Optically-selective element  16  may have a second transmission function T 2 (λ) Object  31  may have a reflection spectrum R(λ). In such examples, a component of signal L received by image sensor  12   a  may correspond to S(λ)*T 1 (λ)*T 2 (λ)*R(λ), and computing device  20  may compare S(λ)*T 1 (λ)*T 2 (λ)*R(λ) with elements of a lookup table. 
     The example technique includes generating, by computing device  20 , in response to the comparison, an output signal ( 78 ). In some examples, the output signal is configured to one or more of adjust a navigation action, cause retrieval over a communications network of a response signal, cause retrieval over the communications network of vehicle environment information, or cause sending of a communication signal over the communications network to a target vehicle. 
     Instead of in vehicles, example systems or techniques according to the disclosure may be implemented in non-vehicular systems, for example, hand-held devices, wearable devices, computing devices, or the like. 
     The techniques described in this disclosure may be implemented, at least in part, in hardware, software, firmware, or any combination thereof. For example, various aspects of the described techniques may be implemented within one or more processors, including one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. The term “processor” or “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry. A control unit including hardware may also perform one or more of the techniques of this disclosure. 
     Such hardware, software, and firmware may be implemented within the same device or within separate devices to support the various techniques described in this disclosure. In addition, any of the described units, modules or components may be implemented together or separately as discrete but interoperable logic devices. Depiction of different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be realized by separate hardware, firmware, or software components. Rather, functionality associated with one or more modules or units may be performed by separate hardware, firmware, or software components, or integrated within common or separate hardware, firmware, or software components. 
     The techniques described in this disclosure may also be embodied or encoded in a computer system-readable medium, such as a computer system-readable storage medium, containing instructions. Instructions embedded or encoded in a computer system-readable medium, including a computer system-readable storage medium, may cause one or more programmable processors, or other processors, to implement one or more of the techniques described herein, such as when instructions included or encoded in the computer system-readable medium are executed by the one or more processors. Computer system readable storage media may include random access memory (RAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), flash memory, a hard disk, a compact disc ROM (CD-ROM), a floppy disk, a cassette, magnetic media, optical media, or other computer system readable media. In some examples, an article of manufacture may comprise one or more computer system-readable storage media. 
     EXAMPLES 
     Example 1 
     A prophetic example of a coded pattern is described.  FIG. 13  is a conceptual diagram of a coded pattern readable by a vehicle assistance system. The pattern includes two compositions together defining a two-dimensional (2D) QR barcode. The first composition includes a first dye having a transition edge at a first wavelength λ 1 . The second composition includes a second dye having a transition edge at a second wavelength λ 2 , higher than λ 1 . When the pattern is illuminated or viewed under small wavelength ranges, a computing device receiving image data from an image sensor imaging the pattern under λ 1  and λ 2  can detect that the composite code is actually made of two separate codes as shown in  FIG. 13 . The computing device can combine the two separate codes to generate the combined pattern, and detect information from the combined pattern. 
     Example 2 
     A prophetic example of an optically-selective element is described. A narrow band blocking multilayer optical film (MOF) having 1st order reflection centered at 1000 nm, with the 2nd order reflection tuned out is used. The bandwidth is tuned between 50 nm and 200 nm.  FIG. 14  is a chart showing a spectrum of an example narrow band blocking multilayer optical film (MOF).  FIG. 15A  is a chart showing a relationship between wavelength, polar angle, and reflectance of the MOF of  FIG. 14  in air.  FIG. 15B  is a chart showing a relationship between wavelength, polar angle, and transmittance of the MOF of  FIG. 14  in air. The acceptance angle is ±40°. 
       FIG. 16A  is a chart showing a relationship between wavelength, polar angle, and reflectance of the MOF of  FIG. 14  in glass (a glass beamsplitter cube).  FIG. 16B  is a chart showing a relationship between wavelength, polar angle, and transmittance of the MOF of  FIG. 14  in glass.  FIG. 16C  is a chart showing a relationship between wavelength, polar angle, and p-polarized transmittance of the MOF of  FIG. 14  in glass.  FIG. 16D  is a chart showing a relationship between wavelength, polar angle, and s-polarized transmittance of the MOF of  FIG. 14  in glass. Light is incident at 45°±15° cone in the cube. This shows a high angle shift and therefore a need for a collimation optic to limit the angle of incidence of the light on the film. 
     Example 3 
     A prophetic example of a dual-band optically-selective element is described. The element includes a filter made by laminating two multilayer optical films (MOFs) having respective single bands, at 800 nm and 1000 nm. Multibands between 350 nm and 1000 nm or more can be used.  FIG. 17  is a chart showing a spectrum of an example dual band blocking multilayer optical film (MOF).  FIG. 18A  is a chart showing a relationship between wavelength, polar angle, and reflectance of the MOF of  FIG. 17  in air.  FIG. 18B  is a chart showing a relationship between wavelength, polar angle, and transmittance of the MOF of  FIG. 17  in air. The two bands are independently tunable. 
     Various examples of the invention have been described. These and other examples are within the scope of the following claims.