Multi-transmission optical filters

Abstract

An optical filter may include: an interference filter that allows at least two channels associated with at least two transmission peaks to pass through; and a plurality of blockers, wherein each of the plurality of blockers allows a corresponding channel associated with a corresponding transmission peak among the at least two transmission peaks to pass through, and blocks one or more channels other than the corresponding channel associated with the corresponding transmission peak.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 62 / 912,951, filed on October 9, 2019, entitled “MULTI-TRANSMISSION OPTICALFILTER,” and U.S. Non-Provisional Patent Application No. 16 / 948,960, filed on October 7, 2020, entitled “MULTI-TRANSMISSION OPTICAL FILTER,” which are expressly incorporated herein by reference. Background Art

[0003] An interference filter is an optical filter that reflects one or more spectral bands or lines and transmits other spectral bands or lines. An interference filter can be wavelength selective due to the interference effect that occurs between the incident wave and the reflected wave at the boundaries of the interference filter. Summary of the invention

[0004] According to some embodiments, an optical filter may include: an interference filter that allows at least two channels associated with at least two transmission peaks to pass through; and a plurality of blockers, wherein each of the plurality of blockers allows a corresponding channel associated with a corresponding transmission peak among the at least two transmission peaks to pass through, and blocks one or more channels other than the corresponding channel associated with the corresponding transmission peak.

[0005] According to some embodiments, a sensor device may include: an optical sensor that collects data using multiple channels; and an optical device that includes: a spacer; and a first reflector and a second reflector, wherein the optical device is associated with at least two transmission peaks; and a plurality of blockers attached to the optical device, wherein each of the plurality of blockers allows a corresponding channel of the plurality of channels associated with a corresponding transmission peak of the at least two transmission peaks to pass through.

[0006] According to some embodiments, a binary multi-spectral filter may include: a plurality of interference filters; and a plurality of blockers, wherein each interference filter in the plurality of interference filters is configured to allow a corresponding channel pair associated with a corresponding transmission peak pair to pass through, wherein an interference filter in the plurality of interference filters is associated with a first blocker in the plurality of blockers, the first blocker being configured to allow a channel associated with a first transmission peak of the corresponding transmission peak pair to pass through and to block a channel associated with a second transmission peak in the corresponding transmission peak pair, and wherein the interference filter is associated with a second blocker in the plurality of blockers, the second blocker being configured to allow a channel associated with the second transmission peak to pass through and to block a channel associated with the first transmission peak. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a diagram of an example interference filter.

[0008] Figure 2 is a diagram of an example device including an interference filter.

[0009] Figure 3 is a diagram illustrating an example transmission diagram for an interference filter.

[0010] Figure 4 is a diagram illustrating an example transmission diagram for an interference filter associated with spacers of various different thicknesses.

[0011] Figure 5 is a diagram illustrating an example transmission diagram for an interference filter. DETAILED DESCRIPTION

[0012] The following detailed description of example embodiments refers to the accompanying drawings.The same reference numbers in different drawings may identify the same or similar elements.

[0013] An optical sensor can use a filter to transmit light of a desired frequency for a sensing operation. For example, an optical sensor can perform sensing about one or more frequency ranges (referred to herein as channels). In some cases, an optical sensor can use an interference filter to transmit a channel and block unwanted light frequencies. An interference filter (e.g., an interferometer, a Fabry-Perot interferometer, an etalon, a Leo filter, etc.) can transmit light associated with a transmission peak based on the geometry and material composition of the interference filter. In some embodiments, the interference filter can be configurable to transmit a channel associated with a transmission peak within the free spectral range (FSR) of the interference filter, so that the optical sensor can perform sensing about the channel.

[0014] It may be beneficial to perform sensing of multiple channels using a single optical sensor. To facilitate sensing of multiple channels, the FSR of the interference filter can be manipulated by changing the geometry and / or material composition of the interference filter. However, a larger FSR may result in a larger resonator bandwidth, resulting in poorer spectral resolution, so extending the FSR to widen the range of addressable channels may not be a viable solution in all use cases. If the optical sensor is to perform sensing of multiple channels, the interference filter can be fabricated with two or more different spacer thicknesses, which may result in the interference filter transmitting two or more corresponding channels. However, the use of multiple spacer thicknesses may complicate the fabrication of the optical filter and may be difficult or impossible to implement using some deposition techniques.

[0015] If the interference filter is configured to transmit a channel associated with a transmission peak in certain regions of the FSR, the interference filter may also pass a second channel associated with a second transmission peak at a frequency different from the desired transmission peak (e.g., due to harmonic effects). For example, if the interference filter is configured to transmit a transmission peak that occurs in a region of the FSR that is susceptible to harmonic effects, the interference filter may also transmit the second transmission peak that may overlap with the desired channel. In this case, if the interference filter (or another filter) is not configured to block the unwanted harmonic transmission peak, the optical sensor may detect noise in the desired channel.

[0016] Embodiments described herein provide an interference filter that transmits channels associated with two or more transmission peaks for measurement by an optical sensor: a first transmission peak (e.g., in a harmonic region of the FSR of the interference filter) and a second transmission peak harmonically related to the corresponding first transmission peak. The interference filter may include two or more blockers corresponding to the two or more transmission peaks. Each blocker may allow a corresponding channel associated with a corresponding one of the two or more transmission peaks to pass through, and may block one or more other transmission peaks of the two or more transmission peaks. The blocker may use a transmission peak in the region of the FSR that would otherwise cause harmonic interference. For example, this may enable an optical sensor to perform sensing in a near infrared (NIR) spectral range and a visible spectral range (e.g., a red light wavelength range, a biologically significant wavelength range, etc.) without increasing the design complexity or manufacturing difficulty compared to a variable spacer design.

[0017] Figure 1is a diagram of an example interference filter 100. In some embodiments, the interference filter 100 may include a spectral filter, a multi-spectral filter (e.g., a binary multi-spectral filter, etc.), etc. In some aspects, the interference filter 100 may include a biometric sensor device, a security sensor device, a health monitoring sensor device, an object identification sensor device, a spectral identification sensor device, a sensor of a wearable device, etc. As shown, the interference filter 100 includes one or more spacers 110, a reflector group 120, and a blocker group 130-1 and 130-2. The propagation of light through the spacer 110 and the reflection of the light by the reflector 120 may create interference, and may allow only light associated with a specific channel or frequency range (e.g., a transmission peak) to pass through. The channel can be configured by changing the thickness of the spacer 110 or the material properties of the spacer 110 and / or the reflector 120. For example, when the thickness of the spacer 110 is changed, the channel of the interference filter 100 can be shifted up or down. Similarly, if different regions of the spacer 110 have different thicknesses, or if different spacers 110 of the interference filter 100 have different thicknesses, different regions or different spacers 110 may allow passage through associated with different transmission peaks. Moreover, changing the material properties of the spacer 110 and / or the reflector 120 may shift the transmission peak upward or downward. The spacer 110 may include any material capable of allowing light to pass through, such as glass, polymers, substrates, and the like. For example, the spacer 110 may include silicon dioxide (SiO2), hydrogenated silicon (Si:H), niobium titanium oxide (NbTiOx), niobium tantalum oxide (NbTaOx), zinc oxide (ZnO), and the like. Si:H may provide material absorption in regions where harmonic transmission peaks may occur in a given design, meaning that the use of Si:H may provide functionality of the blocker 130 with respect to harmonic transmission peaks. In some aspects, the interference filter 100 may include a single blocker 130 that blocks a first transmission peak and a spacer 110 that is partially composed of Si:H that blocks a second transmission peak. For example, the area of ​​the interference filter 100 not covered by a single blocker 130 may include a spacer 110 composed of Si:H, thereby reducing the cost associated with implementing multiple blockers. Therefore, the blocker can be implemented in the hydrogenated silicon spacer 110 of the interference filter 100. The reflector 120 may include a reflective layer, such as a reflective glass layer, etc. The reflector 120 may be attached to the opposite side of the spacer 110. In some aspects, the reflector 120 may be composed of a reflective material, such as a silver layer, etc. In some aspects, the reflector 120 and the spacer 110 may have a thickness less than a threshold value. For example, the reflector 120 and the spacer 110 can form a Fabry-Perot interferometer having a thickness less than about 3 microns.

[0018] As shown, the interference filter 100 includes a plurality of blockers 130. The blockers 130 include devices capable of blocking (e.g., reflecting, absorbing, or a combination thereof) light associated with a first frequency and passing (e.g., transmitting) light associated with a second frequency. For example, the blockers 130 may include optical filters. In some embodiments, the blockers 130 may be attached to a surface of the interference filter 100. In some embodiments, the blockers 130 may not overlap each other on the surface of the interference filter 100.

[0019] exist Figure 1 In the example shown, blocker 130-1 is configured to pass a channel at approximately 1100 nm (indicated by the dashed ellipse around the right transmission peak of transmission graph 150), and blocker 130-2 is configured to pass a channel at approximately 775 nm (indicated by the dashed ellipse around the left transmission peak of transmission graph 150). Figure 3 Describe in more detail.

[0020] Each blocker 130 can be configured to block one or more channels other than the channels through which the blocker 130 passes. For example, blocker 130-1 can be configured to block light of a wavelength associated with blocker 130-2 (e.g., approximately 775 nm), and blocker 130-2 can be configured to block light of a wavelength associated with blocker 130-1 (e.g., approximately 1100 nm). In this way, interference filter 100 can utilize transmission peaks associated with harmonic transmission peaks by using blockers 130 to block unwanted frequencies, thereby reducing interference and improving the accuracy of measurements performed by an optical sensor associated with interference filter 100.

[0021] The transmission peaks and the corresponding harmonic transmission peaks associated with the transmission peaks can be identified using a method for analyzing the propagation of electromagnetic waves through a layered medium. In one example, the transmission peaks and the corresponding harmonic transmission peaks can be determined using a transfer matrix method. For example, the transfer matrix method can identify the harmonic response associated with the reflector 120 and the spacer 110 based at least in part on the geometry and material composition of the reflector 120 and the spacer 110. The harmonic response can indicate a transmission peak and one or more corresponding harmonic transmission peaks.

[0022] The interference filter 100 may include a plurality of spacers 110 of different thicknesses. Each thickness of the spacer 110 may be associated with a corresponding transmission peak pair (or a corresponding plurality of transmission peaks) and a corresponding blocker group 130. An example of a transmission diagram associated with such an embodiment is shown in FIG. Figure 4 and 5In some aspects, the spacer 110 and the reflector 120 can be configured so that the spacer 110 and the reflector 120 create a transmission peak and a corresponding harmonic transmission peak. For example, the thickness of the spacer 110 and the reflector 120, the material properties of the spacer 110 and the reflector 120, etc. can be configured so that the spacer 110 and the reflector 120 transmit the transmission peak and one or more corresponding harmonic transmission peaks.

[0023] As indicated above, Figure 1 are provided only as examples. Other examples may differ from those regarding Figure 1 as described.

[0024] Figure 2 is a diagram of an example device 200 including an interference filter 100. Device 200 includes any device that includes the interference filter 100 and an optical sensor 210. In some aspects, device 200 is an optical device. Interference filter 100 is described in more detail elsewhere herein. In some embodiments, device 200 may be a sensor device, such as a spectrometer, a spectral sensor (e.g., a binary multi-spectral (BMS) sensor), etc. As shown, device 200 includes interference filter 100 and optical sensor 210. Optical sensor 210 includes a device capable of sensing light. For example, optical sensor 210 may include an image sensor, a multi-spectral sensor, a spectral sensor, etc. In some embodiments, optical sensor 210 may include a charge coupled device (CCD) sensor, a complementary metal oxide semiconductor (CMOS) sensor, etc. In some embodiments, optical sensor 210 may include a front side illumination (FSI) sensor, a back side illumination (BSI) sensor, etc. As shown by reference numeral 220, the first blocker 130 of interference filter 100 may pass through a channel associated with a first transmission peak. As indicated by reference numeral 230 , the second barrier 130 of the interference filter 100 may allow a channel associated with the second transmission peak to pass therethrough.

[0025] As indicated above, Figure 2 are provided only as examples. Other examples may differ from those regarding Figure 2 as described.

[0026] Figure 3 is a diagram illustrating an example transmission graph 300 (e.g., transmission graph 150) for interference filter 100. As shown, transmission graph 300 includes a first transmission peak 310 and a second transmission peak 320. For example, first transmission peak 310 may occur in a region of a free spectral range (FSR) 330 of interference filter 100 that is associated with a harmonic transmission peak of first transmission peak 310 (i.e., second transmission peak 320).

[0027] Harmonic peaks may interfere with the sensing operation of a sensor device (e.g., device 200). For example, consider an interference filter configured to pass a first channel at approximately 775 nm (e.g., as a primary channel, not as a harmonic of another channel) and a second channel at approximately 1100 nm. In this case, the interference filter may pass a harmonic transmission peak of the second channel at 775 nm in addition to the first channel at 775 nm. Therefore, the interference filter may cause interference to the first channel at 775 nm due to the overlap of the first channel with the harmonic transmission peak.

[0028] By utilizing the blocker 130 and the harmonic transmission peak associated with the first transmission peak 310, the interference filter 100 can reduce interference, and the effective spectral range of the interference filter 100 can be increased. For example, the interference filter 100 can use a single spacer to pass the second channel (associated with the first transmission peak 310) and the harmonic transmission peak of the second channel (associated with the second transmission peak 320) through, rather than configuring two spacers of the interference filter to pass the first channel and the second channel (which may cause interference between the harmonic transmission peaks of the first channel and the second channel). The corresponding blocker of the interference filter 100 can block one of the first channel and the second channel. Therefore, the interference filter 100 can pass light associated with two transmission peaks at a single spacer thickness, thereby simplifying the manufacture of the interference filter 100 and increasing the number of channels that can be passed by the interference filter 100 for a given spacer thickness distribution.

[0029] Figure 4 4 is a diagram illustrating an example transmission chart 400 for an interference filter (e.g., interference filter 100) associated with a plurality of spacers 110 of different thicknesses. Here, five of the eight regions of the interference filter are shown by way of example only, and regions not shown are indicated by ellipses. As indicated by reference numeral 410, the interference filter can include a plurality of spacers 110 of different thicknesses. As shown, each spacer 110 is associated with a corresponding mirror set 120 and a corresponding plurality (e.g., a corresponding pair) of blockers 130.

[0030] Based on the corresponding thickness of the spacer 110 and / or the material properties of the spacer 110 and / or the reflector 120, each region of the interference filter can allow a corresponding channel to pass through. The corresponding channel is shown by reference numeral 420. In addition, if the corresponding channel is in the FSR region associated with the corresponding harmonic transmission peak, each region of the interference filter can allow the channel associated with the corresponding harmonic transmission peak to pass through. The corresponding channel associated with the harmonic transmission peak is shown by reference numeral 430. As shown, each region of the interference filter associated with a different spacer thickness can be associated with a corresponding spacer pair 110. One spacer 110 in each pair can block the channel shown by reference numeral 420, and the other spacer 110 in each pair can block the channel shown by reference numeral 430. In this way, the number of channels that the interference filter passes through is increased relative to the method in which the interference filter is configured to pass a single channel outside the FSR region associated with the harmonic effect.

[0031] Figure 5 is a diagram illustrating an example transmission graph 500 of an interference filter (e.g., interference filter 100). As shown by graph 500, in some embodiments, the interference filter can be a plurality of primary filter channels 510 and a plurality of secondary filter channels 520. Each secondary filter channel 520 can be associated with a harmonic transmission peak of a corresponding primary filter channel 510. As shown, the primary filter channels 510 and the secondary filter channels 520 can be at a spacing of approximately 5 nm relative to each other. This can be achieved by configuring the characteristics of the reflector 120 or the spacer 110. Therefore, the spacing and number of channels addressable by a sensor device (e.g., device 200) can be increased relative to an approach that does not use secondary filter channels 520.

[0032] As indicated above, Figure 5 are provided as examples. Other examples may differ from those regarding Figure 5 As described.

[0033] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the embodiments to the precise form disclosed.Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the embodiments.

[0034] As used herein, satisfying a threshold may refer to a value being greater than a threshold, more than a threshold, above a threshold, greater than or equal to a threshold, less than a threshold, less than a threshold, below a threshold, less than or equal to a threshold, equal to a threshold, etc., depending on the context.

[0035] Even though particular combinations of features are recited in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of the various embodiments. In fact, many of these features may be combined in ways not specifically recited in the claims and / or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of the various embodiments includes each dependent claim in combination with every other claim in the claim group.

[0036] Unless explicitly described in this way, the elements, actions or instructions used herein should not be interpreted as key or necessary. Moreover, as used herein, the articles "one" and "an" are intended to include one or more projects, and can be used interchangeably with "one or more". Further, as used herein, the article "the" is intended to include one or more projects quoted in conjunction with the article "the", and can be used interchangeably with "one or more". In addition, as used herein, the term "group" is intended to include one or more projects (such as related projects, unrelated projects, combinations of related projects and unrelated projects, etc.), and can be used interchangeably with "one or more". In the case of only one project, the phrase "only one" or similar language is used. Moreover, as used herein, the terms "have", "have", "have (having)" etc. are intended to be open terms. Further, unless otherwise expressly provided, the phrase "based on" is intended to mean "based at least in part on". Furthermore, as used herein, the term "or" when used in series is intended to be inclusive and may be used interchangeably with "and / or" unless expressly stated otherwise (eg, if used in combination with "either" or "only one of...").

Claims

1. An optical filter, comprising: an interference filter that passes at least two channels associated with at least two transmission peaks; as well as Multiple blockers, wherein each of the plurality of blockers is attached to the same surface of the interference filter, passes a corresponding channel associated with a corresponding transmission peak of the at least two transmission peaks, and blocks one or more channels other than the corresponding channel associated with the corresponding transmission peak; and The first transmission peak among the at least two transmission peaks is a harmonic transmission peak of the second transmission peak among the at least two transmission peaks.

2. The optical filter according to claim 1, wherein the plurality of blockers include a first blocker and a second blocker, and the at least two transmission peaks include a first transmission peak and a second transmission peak, wherein the first blocker allows the channel associated with the first transmission peak among the at least two channels to pass through, and blocks the channel associated with the second transmission peak among the at least two channels, and The second blocker allows the channel associated with the second transmission peak to pass through, and blocks the channel associated with the first transmission peak. The optical filter according to claim 1 , wherein the plurality of blockers do not overlap with each other.

4. The optical filter of claim 1, wherein the at least two transmission peaks include a first group of transmission peaks and a second group of transmission peaks, wherein the second group of transmission peaks are harmonically related to corresponding transmission peaks in the first group of transmission peaks.

5. The optical filter according to claim 4, wherein the plurality of blockers include a first blocker and a second blocker, wherein the first blocker is configured to allow a channel group associated with the first group of transmission peaks in the at least two channels to pass through, and to block a channel group associated with the second group of transmission peaks in the at least two channels, and The second blocker is configured to block the channel group associated with the first group of transmission peaks and allow the channel group associated with the second group of transmission peaks to pass through. 6 . The optical filter according to claim 1 , wherein at least one transmission peak of the at least two transmission peaks is outside a free spectral range of the interference filter.

7. The optical filter of claim 1 , wherein the interference filter comprises: a first reflector, a second reflector, and a spacer between the first reflector and the second reflector.

8. The optical filter of claim 7, wherein the spacer comprises a hydrogenated silicon spacer.

9. The optical filter of claim 1, wherein the interference filter comprises a mirror, and wherein the same surface is on the mirror.

10. A sensor device comprising: Optical sensors to collect data using multiple channels; as well as Optical equipment, including: spacers; and a first reflector and a second reflector, wherein the optical device is associated with at least two transmission peaks; and a plurality of blockers attached to the optical device, wherein each of the plurality of blockers is attached to a surface of the first reflector and passes a corresponding one of the plurality of channels associated with a corresponding one of the at least two transmission peaks; The first transmission peak among the at least two transmission peaks is a harmonic transmission peak of the second transmission peak among the at least two transmission peaks.

11. The sensor device of claim 10, wherein the optical device further comprises a plurality of spacers, and wherein each spacer of the plurality of spacers is associated with a respective set of transmission peaks. 12 . The sensor device of claim 10 , wherein the first transmission peak of the at least two transmission peaks is associated with a near infrared spectral range, and wherein the second transmission peak of the at least two transmission peaks is associated with a visible spectral range.

13. A spectral filter comprising: Multiple interference filters; as well as Multiple blockers, wherein each interference filter of the plurality of interference filters is configured to pass a corresponding pair of channels associated with a corresponding pair of transmission peaks, wherein an interference filter of the plurality of interference filters is associated with a first blocker of the plurality of blockers, the first blocker being configured to pass a channel associated with a first transmission peak of the corresponding transmission peak pair and to block a channel associated with a second transmission peak of the corresponding transmission peak pair, wherein the interference filter is associated with a second blocker of the plurality of blockers, the second blocker being configured to pass the channel associated with the second transmission peak and block the channel associated with the first transmission peak, and wherein the first blocker and the second blocker are attached to the same surface of the interference filter; and The second transmission peak is a harmonic transmission peak of the first transmission peak.

14. The spectral filter of claim 13, wherein each interference filter of the plurality of interference filters is associated with a corresponding blocker pair.

15. The spectral filter according to claim 14, wherein each of the corresponding blocker pairs comprises a corresponding first blocker and a corresponding second blocker, wherein the corresponding first blocker is configured to block a channel associated with a corresponding first transmission peak in the corresponding transmission peak pair and to allow a channel associated with a corresponding second transmission peak in the corresponding transmission peak pair to pass through, and The corresponding second blocker is configured to allow the channel associated with the corresponding second transmission peak to pass through, and block the channel associated with the corresponding first transmission peak.

16. The spectral filter of claim 13, wherein the first transmission peak is associated with a near infrared spectral range and the second transmission peak is associated with a visible spectral range.

17. The spectral filter according to claim 13, wherein the interference filter comprises a first reflector and a second reflector, and Wherein said same surface is on said reflector.

18. The spectral filter of claim 13, wherein the first blocker is attached to a first portion of the same surface, and Wherein the second barrier is attached to a second portion of the same surface.

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