Patent Description:
In another example, information regarding the near-infrared light may be used to recognize an identity of the user, a characteristic of the user (e.g., a height, a weight, a pulse, a blood oxygenation, etc.), a characteristic of another type of target (e.g., a distance to an object, a size of the object, a shape of the object, a spectroscopic signature of the object, etc.), and/or the like. However, during transmission of the near-infrared light toward the user or object and/or during reflection from the user or object toward the optical receiver, ambient light may interfere with the near-infrared light. Thus, the optical receiver may be optically coupled to an optical filter, such as a bandpass filter, to filter ambient light and to allow near-infrared light to pass through toward the optical receiver. Additionally, or alternatively, when performing sensing of multiple wavelengths of light, a filter may be provided to ensure that each wavelength of light, of the multiple wavelengths of light, is directed to a different sensor.

A multispectral sensor device, which may be an optical receiver, may be utilized to capture information about the multiple wavelengths of light. The multispectral sensor device may include a set of sensor elements (e.g., optical sensors, spectral sensors, and/or image sensors) that capture the information and are coupled to a multispectral filter. For example, an array of sensor elements may be utilized to capture information relating to multiple frequencies, and the multispectral filter may direct, to each sensor element, light associated with a different frequency. In some cases, a single filter may be disposed to cover each sensor element of the sensor element array, and may form a set of channels for the sensor element array. Multi spectral devices are disclosed in <CIT>, and <CIT>.

According to some possible implementations, an optical filter may include a substrate. The optical filter may include a first mirror. The optical filter may include a second mirror. The optical filter may include a spacer. The first mirror, the second mirror, and the spacer may form a plurality of component filters. A first component filter, of the plurality of component filters, may be associated with a first cross-sectional area and a second component filter, of the plurality of component filters, is associated with a second cross-sectional area. The first cross-sectional area and the second cross-sectional area may be configured to response balance the first component filter and the second component filter.

The plurality of component filters may be configured based at least in part on respective input fluxes, filter responsivities, and sensor responsivities.

The optical filter may form at least <NUM> channels.

At least one of the first mirror, the second mirror, or the spacer includes at least one of: a germanium layer, a silicon-germanium layer, a hydrogenated silicon layer, a hydrogenated germanium layer, or a hydrogenated silicon-germanium layer.

At least one of the first mirror, the second mirror, or the spacer may include at least one of: a silicon layer, a silicon dioxide (SiO<NUM>) layer, an aluminum oxide (Al<NUM>O<NUM>) layer, a titanium dioxide (TiO<NUM>) layer, a niobium pentoxide (Nb<NUM>O<NUM>) layer, a tantalum pentoxide (Ta<NUM>O<NUM>) layer, or a magnesium fluoride (MgF<NUM>) layer.

At least two component filters, of the plurality of component filters, are associated with a common wavelength, and wherein a net cross-sectional area of the at least two component filters may be configured to response balance the at least two component filters with another component filter of the plurality of component filters.

The first cross-sectional area may differ from the second cross-sectional area by greater than <NUM>%.

A spectral range of the optical filter may include a near-infrared spectral range or a mid-infrared spectral range.

The first component filter may be associated with a first wavelength of light and the second component filter may be associated with a second wavelength of light.

According the invention, binary multispectral filter includes a plurality of layers. The plurality of layers includes a set of high refractive index layers associated with a first refractive index and a set of low refractive index layers associated with a second refractive index that is less than the first refractive index. The plurality of layers forms a plurality of channels to direct a plurality of wavelengths of light. A plurality of cross-sectional areas of a plurality of component filters corresponds to the plurality of channels is varied to configure a response associated with the plurality of channels to a particular response.

The particular response may be balanced to within less than approximately <NUM>% differentiation between the plurality of channels.

The particular response may be a non-balanced response.

A first area of a first channel, of the plurality of channels, to a second area of a second channel, of the plurality of channels, may correspond to a ratio of a first input flux of the first channel, a first filter responsivity of the first channel, and a first sensor responsivity of the first channel to a second input flux of the second channel, a second filter responsivity of the second channel, and a second sensor responsivity of the second channel.

According to some possible implementations, a system may include a set of optical sensors disposed in a substrate. The system may include a multispectral filter deposited on the substrate. The multispectral filter may include at least one layer configured to form a plurality of channels corresponding to the set of optical sensors. A plurality of cross-sectional areas of the plurality of channels may be configured to response balance the set of optical sensors.

A first input flux at a first wavelength for a first channel of the plurality of channels may be different from a second input flux at a second wavelength for a second channel of the plurality of channels.

The system may at least one of: a biometric system, a security system, a health monitoring system, an object identification system, or a spectroscopic identification system.

A sensor element (e.g., an optical sensor) may be incorporated into an optical sensor device to obtain information (e.g., spectral data) regarding a set of electromagnetic frequencies. For example, the optical sensor device may include an image sensor, a multispectral sensor, and/or the like that may perform a sensor measurement of light. The optical sensor device may utilize one or more sensor technologies, such as a complementary metal-oxide-semiconductor (CMOS) technology, a charge-coupled device (CCD) technology, and/or the like. The optical sensor device may include multiple sensor elements (e.g., an array of sensor elements) each configured to obtain information about a different frequency of light.

A sensor element may be associated with a filter that filters light to the sensor element. For example, the sensor element may be aligned with a linear variable filter (LVF), a circular variable filter (CVF), a Fabry-Perot filter, and/or the like to cause a portion of light directed toward the sensor element to be filtered. For a binary filter structure, such as a Fabry-Perot filter, a spacer may be positioned between reflectors (e.g., mirrors) of the binary filter structure. Configuration of refractive indices, thicknesses, and/or the like of layers of the reflectors, layers of the spacer, and/or the like may enable configuration of the binary filter structure to form a set of channels. A channel may include a portion of the filter that directs light to a sensor element of a sensor element array. In this way, the sensor element array may obtain information regarding multiple different wavelengths of light.

However, a sensor element may be associated with a first sensor responsivity to a first wavelength of light and a second sensor responsivity to a second wavelength of light. Similarly, the filter may be associated with a first filter responsivity for passing through the first wavelength of light and a second filter responsivity for passing through a second wavelength of light. Further, in some cases, a light source may provide different levels of flux at different wavelengths of light. As a result, an optical power of the first wavelength of light may exceed a maximum optical power threshold associated with a first sensor element, which may result in insufficient signal to noise ratio for the first sensor element to perform an accurate measurement of the first wavelength of light. In contrast, an optical power of the second wavelength of light may be less than a minimum optical power threshold associated with a second sensor element, which may result in insufficient signal to noise ratio for the second sensor element to perform an accurate measurement of the second wavelength of light. Moreover, a saturated sensor element (e.g., a sensor element receiving radiant energy greater than a threshold) may distribute charge to adjacent sensor elements, which may reduce an accuracy of measurements as a result of false signal effects, crosstalk effects, and blooming effects.

In some cases, a gain flattening filter may be disposed into an optical path to avoid a mismatch between optical powers of the first wavelength of light and the second wavelength of light by attenuating light passing through the gain flattening filter. In this way, the gain flattening filter may prevent the first wavelength of light from exceeding the maximum optical power threshold, but may further reduce an optical power of the second wavelength of light. To compensate for the reduced optical power of the second wavelength of light, an exposure time of the sensor element array may be increased to increase an amount of light of the second wavelength that is measured by the second sensor element. However, increasing an exposure time may result in excessive time to perform a measurement, inaccuracy relating to capture of stray light, and/or the like.

The invention provides a multispectral filter array with integrated response balancing. In this case, the multispectral filter array is configured with different sized channels (e.g., a first channel for the first wavelength of light with a first cross-sectional area and a second channel for the second wavelength of light with a second cross-sectional area) to balance an optical power of wavelengths of light directed to sensor elements of a sensor element array. In this way, a multispectral filter array may be provided for a sensor element array that improves signal to noise ratio of measurements of the sensor element array, improves accuracy of the sensor element array, reduces exposure time of the sensor element array, and/or the like. Moreover, the multispectral filter may reduce a likelihood of false signal effects, crosstalk effects, and blooming effects by reducing a likelihood of sensor element saturation, sensor element distribution of charge to adjacent sensor elements, and/or the like.

<FIG> is a diagram of an example implementation <NUM> described herein. As shown in <FIG>, a multispectral filter <NUM> (e.g., a binary structure optical filter array) may include a first mirror <NUM>-<NUM>, a second mirror <NUM>-<NUM>, and a spacer <NUM>.

As further shown in <FIG>, first mirror <NUM>-<NUM> and second mirror <NUM>-<NUM> may sandwich spacer <NUM>. In other words, spacer <NUM> may separate first mirror <NUM>-<NUM> and second mirror <NUM>-<NUM> by a threshold distance, and/or faces of spacer <NUM> may be enclosed by first mirror <NUM>-<NUM> and second mirror <NUM>-<NUM>. In some implementations, mirrors <NUM> may be associated with a particular material. For example, mirrors <NUM> may include a set of metal mirror layers (e.g., silver), a set of dielectric mirror layers (e.g., alternating hydrogenated silicon layers and silicon dioxide layers), and/or the like to direct a portion of light directed from a light source toward sensor elements associated with multispectral filter <NUM>. Mirrors <NUM> may align with each sensor element of a sensor element array associated with each channel of multispectral filter <NUM>.

In some implementations, spacer <NUM> may include one or more spacer layers <NUM>. For example, spacer <NUM> may include a set of spacer layers <NUM>-<NUM> through <NUM>-<NUM> (e.g., dielectric layers). In some implementations, a thickness of one or more spacer layers <NUM> may be associated with ensuring a minimum spacer thickness for a particular wavelength. In some implementations, spacer <NUM> may be associated with a single cavity configuration. In some implementations, spacer <NUM> may be associated with a multi-cavity configuration.

In some implementations, multispectral filter <NUM> may be deposited onto a substrate associated with an optical sensor device. For example, mirror <NUM>-<NUM> may be deposited (e.g., via a deposition process and/or a photolithographic lift-off process) onto a substrate that includes an array of sensor elements to capture information (e.g., spectral data). In some implementations, spacer <NUM> may permit capture of information relating to multiple wavelengths. For example, a first portion of spacer <NUM> aligned with a first sensor element may be associated with a first thickness and a second portion of spacer <NUM> aligned with a second sensor element may be associated with a second thickness. In this case, light, which is directed toward the first sensor element and the second sensor element, may correspond to a first wavelength at the first sensor element based on the first thickness and a second wavelength at the second sensor element based on the second thickness. In this way, multispectral filter <NUM> permits multispectral sensing by an optical sensor device using a spacer (e.g., spacer <NUM>) associated with multiple portions, which are associated with multiple thicknesses, aligned to multiple sensor elements of the optical sensor device.

In the invention, multispectral filter <NUM> is associated with a set of channels corresponding to a set of component filters. For example, multispectral filter <NUM> may be associated with a first channel aligned to a first sensor element to direct a first wavelength of light to the first sensor element, and the first channel may be formed by a first component filter. In this case, the first component filter may be a portion of multispectral filter <NUM>. Similarly, multispectral filter <NUM> may include a second channel aligned to a second sensor element to direct a second wavelength of light to the second sensor element, and the second channel may be formed by a second component filter.

In some implementations, a first channel of multispectral filter <NUM> may be associated with a different cross-sectional area than a second component filter of multispectral filter <NUM>. For example, based on a responsivity of the sensor element array to the first wavelength and the second wavelength, a responsivity of multispectral filter <NUM> to the first wavelength and the second wavelength, a flux of the first layer and the second layer, and/or the like, respective cross-sectional areas of the first component filter and the second component filter are configured to response balance the first sensor element to within a threshold amount of an output of the second sensor element. In some implementations, the first sensor element may be response balanced to within approximately <NUM>% differentiation between channels, within approximately <NUM>% differentiation between channels, within approximately <NUM>% differentiation between channels, within approximately <NUM>% differentiation between channels, within approximately <NUM>% differentiation between channels, within approximately <NUM>% differentiation between channels, and/or the like.

In this way, multispectral filter <NUM> is response balanced to improve a signal to noise ratio for measurements performed using each sensor element associated with multispectral filter <NUM> relative to another multispectral filter with equal cross-sectional areas for each channel. Moreover, based on using differing cross-sectional areas to perform response balancing, multispectral filter <NUM> may be associated with reduced cost, reduced complexity, reduced exposure time, and/or the like relative to other techniques for response balancing.

<FIG> and <FIG> are diagrams of example implementations <NUM>/<NUM>' described herein. As shown in <FIG>, a multispectral filter may include a first channel for a first wavelength formed by first component filter <NUM> and a second channel for a second wavelength formed by a second component filter <NUM>.

As further shown in <FIG>, each component filter may be aligned to a sensor element of a sensor element array. For example, component filter <NUM> may be aligned to sensor element <NUM>-<NUM> and component filter <NUM> may be aligned to sensor element <NUM>-<NUM>. In some implementations, a size of the component filters may differ to balance a response associated with sensor elements <NUM>. For example, a size of each component filter may be determined based on a function: <MAT> where F represents an input flux (from light <NUM>-<NUM> and light <NUM>-<NUM>) directed toward a component filter, A represents a cross-sectional area of the component filter, T represents a filter responsivity of the component filter (e.g., a transmissivity) to directing a wavelength toward a sensor element, and R represents a sensor responsivity of the sensor element at the wavelength that is directed by the component filter to the sensor element. In this case, for an input flux of equal power at a first wavelength directed to component filter <NUM> and at a second wavelength directed to component filter <NUM> (F<NUM> = F<NUM>), a ratio of areas of component filter <NUM> to component filter <NUM> may be determined: <MAT> In this case, each area may be selected to satisfy (<NUM>) and such that an amount of optical power directed to each sensor element does not exceed a maximum power threshold and is not less than a minimum power threshold (e.g., the sensor element is not saturated and is less likely to cause, for example, crosstalk relative to a non-response balanced sensor element). In this way, respective areas of component filter <NUM> and component filter <NUM> may be selected to achieve an equal energy balance across respective channels (E<NUM> = E<NUM>, where E is energy of a channel).

Although some implementations, described herein, are described in terms of an input flux of equal power, input fluxes of differing powers at differing wavelengths may be possible, and different channels may be associated with different cross-sectional areas to response balance the input fluxes of differing powers. Moreover, some implementations, described herein are described in terms of response balancing a set of two channels, however additional quantities of channels may be response balanced, such as <NUM> channels, <NUM> channels, <NUM> channels, and/or the like for a multispectral filter.

In some implementations, cross-sectional areas of, for example, component filter <NUM> and component filter <NUM> may be configured to achieve a non-equal response. For example, for a desired energy response for sensor elements that is not equal (e.g., to cause a first sensor element to have a greater energy response than a second sensor element), cross-sectional areas may be configured to create the desired energy response. In this way, another type of configurable energy response is possible (e.g., a non-response-balanced energy response) to achieve a particular optical functionality.

As shown in <FIG>, rather than a single aperture forming component filter <NUM>, multiple apertures may, collectively, form component filter <NUM>' with an area A<NUM>'. In this case, the total area A<NUM>' may be the same as area A<NUM>, which may result in example component filter <NUM>' being able to response balance component filter <NUM> (similar to component filter <NUM> response balancing component filter <NUM>). In some implementations, each of the apertures forming component filter <NUM>' may be a same area. In some implementations, a first aperture forming component filter <NUM>' may be a first area and a second aperture forming component filter <NUM>' may be a second area.

As indicated above, <FIG> and <FIG> are provided merely as examples. Other examples are possible and may differ from what was described with regard to <FIG> and <FIG>.

<FIG> is a diagram of an example optical filter <NUM>. <FIG> shows an example stackup of an optical filter with multiple channels to direct light described herein. As further shown in <FIG>, optical filter <NUM> includes an optical filter coating portion <NUM> and a substrate <NUM>.

Optical filter coating portion <NUM> includes a set of optical filter layers. For example, optical filter coating portion <NUM> includes a first set of layers <NUM>-<NUM> through <NUM>-N+<NUM> (N≥ <NUM>) and a second set of layers <NUM>-<NUM> through <NUM>-N. In another example, optical filter coating portion <NUM> may be a single type of layer (e.g., one or more layers <NUM>), three or more types of layers (e.g., one or more layers <NUM>, one or more layers <NUM>, and one or more of one or more other types of layers), and/or the like. In some implementations, layers <NUM> may include a set of layers of a high refractive index material (H layers), such as silicon layers, hydrogenated silicon layers, silicon-germanium (SiGe) layers, hydrogenated germanium layers, hydrogenated silicon-germanium layers, and/or the like. Although some layers may be described as a particular material, such as SiGe, some layers may include (small quantities of) phosphor, boron, nitride, and/or the like. In some implementations, layers <NUM> may include a set of layers of a low refractive index material (L layers), such as silicon dioxide layers and/or the like. Additionally, or alternatively, the L layers may include silicon nitride layers, tantalum pentoxide (Ta<NUM>O<NUM>) layers, niobium pentoxide (Nb<NUM>O<NUM>) layers, titanium dioxide (TiO<NUM>) layers, aluminum oxide (Al<NUM>O<NUM>) layers, zirconium oxide (ZrO<NUM>) layers, yttrium oxide (Y<NUM>O<NUM>) layers, silicon nitride (Si<NUM>N<NUM>) layers, a combination thereof, and/or the like.

In some implementations, optical filter coating portion <NUM> may be associated with a particular quantity of layers, m. For example, a hydrogenated silicon-germanium based optical filter may include a quantity of alternating high refractive index layers and low refractive index layers, such as a range of <NUM> layers to <NUM> layers. In some implementations, optical filter coating portion <NUM> may be fabricated using a sputtering procedure. For example, optical filter coating portion <NUM> may be fabricated using a pulsed-magnetron based sputtering procedure to sputter alternating layers <NUM> and <NUM> on a glass substrate or another type of substrate, as described herein. In some implementations, multiple cathodes may be used for the sputtering procedure, such as a first cathode to sputter silicon and a second cathode to sputter germanium, thereby forming a silicon-germanium layer.

In some implementations, optical filter coating portion <NUM> may be annealed using one or more annealing procedures, such as a first annealing procedure at a temperature of approximately <NUM> degrees Celsius or between approximately <NUM> degrees Celsius and approximately <NUM> degrees Celsius, a second annealing procedure at a temperature of approximately <NUM> degrees Celsius or between approximately <NUM> degrees Celsius and approximately <NUM> degrees Celsius, and/or the like.

In some implementations, each layer of optical filter coating portion <NUM> may be associated with a particular thickness. For example, layers <NUM> and <NUM> may each be associated with a thickness of between <NUM> and <NUM>, between <NUM> and <NUM>, and/or the like. Additionally, or alternatively, optical filter coating portion <NUM> may be associated with a thickness of between <NUM> and <NUM>, <NUM> and <NUM>, and/or the like. In some implementations, at least one of layers <NUM> and <NUM> may each be associated with a thickness of less than <NUM>, less than <NUM>, or less than <NUM>, and/or the like. Additionally, or alternatively, optical filter coating portion <NUM> may be associated with a thickness of less than <NUM>, less than <NUM>, less than <NUM>, and/or the like. In some implementations, a layer may be associated with multiple different thicknesses. For example, to form a set of channels, a thickness of a particular layer (e.g., a spacer layer disposed between a set of reflectors) may be varied to cause different wavelengths of light to be directed to different sensor elements via different channels.

In some implementations, optical filter <NUM> may be associated with a particular spectral range, such as a near-infrared spectral range, a mid-infrared spectral range, and/or the like. For example, optical filter <NUM> may be associated with a spectral range from approximately <NUM> to approximately <NUM>, from approximately <NUM> to approximately <NUM>, from approximately <NUM> to approximately <NUM>, and/or the like.

In some implementations, a cross-sectional area of each channel may vary. For example, a first channel formed by a first component filter (e.g., a first area of optical filter <NUM> with a first thickness) may be associated with a first cross-sectional area and a second channel formed by a second component filter (e.g., a second area of optical filter <NUM> with a second thickness) may be associated with a second cross-sectional area. In this way, differing cross-sectional areas of different channels may be used to balance responses of sensor elements for the different channels. In some implementations, cross-sectional areas of component filters of optical filter <NUM> may vary by a threshold amount. For example, a first component filter may be associated with a cross-sectional area that is greater than a cross-sectional area of a second component filter by approximately <NUM>%, approximately <NUM>%, approximately <NUM>%, approximately <NUM>%, approximately <NUM>%, approximately <NUM>%, approximately <NUM>%, and/or the like.

In the invention, multiple channels are associated with a common wavelength. For example, a first channel may be associated with a same thickness as a second channel and a different thickness than a third channel. In this case, the first channel and the second channel may be associated with a first wavelength and the third channel may be associated with a third wavelength. Collectively, a net area of the first channel and the second channel are configured based on an area of the third channel to balance a response between sensor elements associated with the first channel, second channel, and third channel. In this way, multiple component filters forming multiple channels may be associated with a net cross-sectional area that is balanced with another channel to balance responses of sensor elements for the different channels.

Although some implementations, described herein, are described in terms of a binary multispectral filter, another type of multispectral filter with differing cross-sectional areas for component filters may be used, such as a single-layer polymer multispectral filter, a multi-layer polymer multispectral filter, an organic dye multispectral filter, and/or the like.

<FIG> is a diagram of an example implementation <NUM> described herein. As shown in <FIG>, example implementation <NUM> includes a sensor system <NUM>. Sensor system <NUM> may be a portion of an optical system, and may provide an electrical output corresponding to a sensor determination. For example, sensor system <NUM> may be a portion of a biometric system, a security system, a health monitoring system, an object identification system, a spectroscopic identification system, and/or the like. Sensor system <NUM> includes an optical filter structure <NUM>, which includes an optical filter <NUM>, and a set of optical sensors <NUM> (e.g., a sensor element array). For example, optical filter structure <NUM> may include an optical filter <NUM> that performs a blocking functionality and/or the like. Sensor system <NUM> includes an optical transmitter <NUM> that transmits an optical signal toward a target <NUM> (e.g., a person, an object, etc.).

Although implementations, described herein, may be described in terms of an optical filter in a sensor system, implementations described herein may be used in another type of system, may be used external to the sensor system, and/or the like.

In some implementations, another arrangement of optical filter <NUM> and optical sensor <NUM> may be utilized. For example, rather than passing the second portion of the optical signal collinearly with the input optical signal, optical filter <NUM> may direct the second portion of the optical signal in another direction toward a differently located optical sensor <NUM>. In some implementations, optical sensor <NUM> may be an avalanche photodiode, an Indium-Gallium-Arsenide (InGaAs) detector, an infrared detector, and/or the like.

As further shown in <FIG>, and by reference number <NUM>, an input optical signal is directed toward optical filter structure <NUM>. The input optical signal may include near-infrared light, mid-infrared light, and/or the like emitted by optical transmitter <NUM> and ambient light from the environment in which sensor system <NUM> is being utilized. For example, when optical filter <NUM> is a bandpass filter, optical transmitter <NUM> may direct near-infrared light toward an object for a spectroscopic measurement, and the near-infrared light may be reflected off target <NUM> (e.g., the object) toward optical sensors <NUM> to permit optical sensors <NUM> to perform a measurement of the near-infrared light. In this case, ambient light may be directed toward optical sensor <NUM> from one or more ambient light sources (e.g., a light bulb or the sun).

In another example, multiple light beams may be directed toward target <NUM> and a subset of the multiple light beams may be reflected toward optical filter structure <NUM>, which may be disposed at a tilt angle relative to optical sensor <NUM>, as shown. In some implementations, another tilt angle may be used. In some implementations, optical filter structure <NUM> may be disposed and/or formed directly onto optical sensors <NUM>, disposed a distance from optical sensors <NUM> (e.g., via free-space optics), and/or the like. For example, optical filter structure <NUM> may be coated and patterned onto optical sensors <NUM> using, for example, photolithography, a sputter deposition technique (e.g., using argon gas and helium gas as an inert gas mixture for sputter deposition), and/or the like.

In another example, optical transmitter <NUM> may direct near-infrared light toward another type of target <NUM>, such as for detecting a gesture in a gesture recognition system, detecting objects in proximity to a vehicle, detecting objects in proximity to a blind person, detecting a proximity to an object (e.g., using a LIDAR technique), and/or the like, and the near-infrared light and ambient light may be directed toward optical sensor <NUM> as a result.

In some implementations, a portion of the optical signal is passed by optical filter <NUM> and optical filter structure <NUM>. For example, alternating high index material layers and low index material layers of optical filter <NUM> may cause a first portion of light to be reflected and a second portion of light to be passed. In this case, optical filter <NUM> may include multiple channels formed using multiple component filters, and each channel may pass a different wavelength of light. Additionally, or alternatively, two or more channels may pass a common wavelength of light.

As further shown in <FIG>, and by reference number <NUM>, based on the portion of the optical signal being passed to optical sensor <NUM>, optical sensor <NUM> may provide an output electrical signal for sensor system <NUM>, such as for use in performing a spectroscopic measurement, recognizing a gesture of the user, detecting the presence of an object, and/or the like. Based on configuring a cross-sectional area of component filters corresponding to each channel, a response of optical sensors <NUM> is balanced, thereby improving measurement accuracy relative to an overexposed or underexposed sensor element in a sensor element array.

<FIG> and <FIG> are diagrams of example implementations <NUM>/<NUM>' described herein. As shown in <FIG>, example implementation <NUM> may include an optical filter <NUM> with multiple component filters <NUM> forming multiple channels.

As further shown in <FIG>, each component filter <NUM> may be associated with a particular wavelength of light that is directed to a respective sensor element aligned to each component filter <NUM>. For example, a first component filter <NUM> may be associated with passing light with a wavelength of <NUM> nanometers (nm), a second component filter <NUM> may be associated with passing light with a wavelength of <NUM>, and/or the like. As shown, component filters <NUM> may be associated with different sizes corresponding to different filter responsivities, different sensor element responsivities, and/or the like for different wavelengths to response balance the different sensor elements. As shown, some wavelengths may be directed to one or more sensor elements by multiple component filters <NUM>. For example, a set of two component filters <NUM> may be associated with passing light associated with a wavelength of <NUM> to response balance the difference sensor elements.

As shown in <FIG>, multiple component filters <NUM> are associated with a common wavelength, λ1 (e.g., <NUM>). In this case, each of the component filters <NUM> associated with the common wavelength are associated with different areas (e.g., A1, A2, A3, and A4, respectively). Based on including multiple component filters <NUM> with different areas to receive light associated with a common wavelength, example implementation <NUM>' enables multiple samplings of a signal level of the light associated with the common wavelength, thereby enabling high-dynamic range (HDR) imaging.

In this way, a multispectral filter includes varying cross-sectional areas for component filters and corresponding channels to response balance sensor elements associated with the component filters and corresponding channels. In this way, multispectral filter may improve an accuracy of sensing by the sensor elements, reduce an exposure time to perform a measurement, reduce cost, reduce size, and/or the like relative to other sensing techniques and/or response balancing techniques described above.

Some implementations are described herein in connection with thresholds. As used herein, satisfying a threshold may refer to a value being greater than the threshold, more than the threshold, higher than the threshold, greater than or equal to the threshold, less than the threshold, fewer than the threshold, lower than the threshold, less than or equal to the threshold, equal to the threshold, and/or the like.

Claim 1:
A binary multispectral filter (<NUM>), comprising:
a plurality of layers (<NUM>, <NUM>),
wherein the plurality of layers (<NUM>, <NUM>) includes a set of high refractive index layers (<NUM>) associated with a first refractive index and a set of low refractive index layers (<NUM>) associated with a second refractive index that is less than the first refractive index,
wherein the plurality of layers (<NUM>, <NUM>) form a plurality of channels to direct a plurality of wavelengths of light,
wherein a plurality of cross-sectional areas of a plurality of component filters (<NUM>) corresponding to the plurality of channels is varied to configure a response associated with the plurality of channels to a particular response;
wherein a first component filter (<NUM>) is associated with a first wavelength of light and a second component filter (<NUM>) is associated with a second wavelength of light; and
wherein at least two component filters, of the plurality of component filters (<NUM>), are associated with a common wavelength, and have different cross-sectional areas wherein a net cross-sectional area of the at least two component filters (<NUM>) is configured to response balance the at least two component filters (<NUM>) with another component filter of the plurality of component filters (<NUM>)