WO2016171651A1

WO2016171651A1 - Tunable filters

Info

Publication number: WO2016171651A1
Application number: PCT/US2015/026662
Authority: WO
Inventors: Michael Dongxue WANG
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2015-04-20
Filing date: 2015-04-20
Publication date: 2016-10-27
Also published as: TW201644260A; TWI584646B

Abstract

An example electronic device includes a first tunable filter, a second tunable filter, an image sensor to receive image components passed by the first tunable filter and the second tunable filter, and a controller. The controller is to, during a first time period, control the first tunable filter to pass an infrared (IR) component of an image input, control the second tunable filter to block a visible light (VL) component of the image input, and control the image sensor to capture an IR image using the IR component. The controller is further to, during a second time period, control the first tunable filter to block the IR component of the image input, control the second tunable filter to pass the VL component of the image input, and control the image sensor to capture a VL image using the VL component.

Description

TUNABLE FILTERS

Background

[0001] Many types of electronic devices can include components to capture visible light images for use in still or video photography. Further, electronic devices can include components to capture electromagnetic radiation in non-visible bands. For example, some components may capture non- visible information in the infrared band.

Brief Description Of The Drawings

[0002] Some examples are described with respect to the following figures.

[0003] Fig. 1 is a schematic diagram of an example device that includes tunable filters.

[0004] Fig. 2 is a flow diagram of an example process for an imaging operation using tunable filters.

[0005] Figs. 3A-3B are schematic diagrams of an example imaging operation using tunable filters.

[0006] Fig. 4 is a schematic diagram of an example device that includes an angled tunable filter.

[0007] Fig. 5 is a flow diagram of an example process for an imaging operation using an angled tunable filter.

[0008] Figs. 6A-6C are schematic diagrams of an example imaging operation using an angled tunable filter.

[0009] Fig. 7 is a schematic diagram of an example device that includes a tunable filter.

[0010] Fig. 8 is a flow diagram of an example process for an imaging operation using a tunable filter. Detailed Description

[0011] Some conventional electronic devices use separate components to capture visible light and infrared images. The visible light images may be used for photo and/or video applications. The infrared images may be used for various applications, including three- dimensional (3D) imaging, facial recognition, device input or control, motion capture, camera focusing, etc. The use of separate components to capture visible light images and infrared images may contribute to the complexity and cost of such conventional electronic devices.

[0012] In accordance with some examples, techniques and/or mechanisms are provided to capture visible light and infrared images from an input image. In some examples, an electronic device may include an aperture or lens to receive the input image. A liquid crystal (LC) tunable filter may be used to selectively filter specific bands of energy. After this filtering, one or more sensors may capture separate visible light and infrared images. Some examples may enable the capture of visible light and infrared images using simple and cost- effective components.

[0013] Fig. 1 is a schematic diagram of an example device 100 that includes tunable filters. The device 100 may be all or a portion of any electronic, such as a mobile telephone, a computer, a server, a media player, a personal digital assistant, a tablet, a network device, etc. As shown, the device 100 can include an optical aperture 130, an infrared emitter 135, a first tunable filter 140, a second tunable filter 150, an image sensor 160, processor(s) 180, memory 185, and machine-readable storage 195.

[0014] The processor(s) 180 can include a microprocessor, microcontroller, processor module or subsystem, programmable integrated circuit, programmable gate array, multiple processors, a microprocessor including multiple processing cores, or another control or computing device.

[0015] The memory 185 can be any type of computer memory (e.g., dynamic random access memory (DRAM), static random-access memory (SRAM), non-volatile memory (NVM), a combination of DRAM and NVM, etc.). The machine-readable storage 195 can include any type of non-transitory storage media such as hard drives, flash storage, optical disks, non-volatile memory, etc. [0016] As shown, the machine -readable storage 195 can include an imaging module 190. In some examples, the imaging module 190 can be code or program instructions executable by the processor(s) 180. However, any of the features described herein in relation to the imaging module 190 can be implemented in any suitable manner. For example, the features of the imaging module 190 can also be implemented in any combination of software, firmware, and/or hardware. In some examples, the imaging module 190 may control the optical aperture 130, the infrared emitter 135, the first tunable filter 140, the second tunable filter 150, and/or the image sensor 160.

[0017] The optical aperture 130 may receive light input including a visible light (VL) portion 110 and an infrared (IR) portion 120. In some examples, the optical aperture 130 may include one or more optical components, such as lenses, a shutter, an image stabilizer, a focusing element, and so forth (not shown). In some examples, the image sensor 160 may be a sensor capable of capturing images using either the VL portion 110 and the IR portion 120. The image sensor 160 may be any of a semiconductor charge-coupled device (CCD), a complementary metal-oxide-semiconductor (CMOS), a N-type metal-oxide-semiconductor (NMOS), and so forth.

[0018] In some examples, the imaging module 190 may control the infrared emitter 135 to illuminate a target object with IR light. Further, the IR portion 120 may be IR light that is reflected off the target object when illuminated by the infrared emitter 135. In some examples, the emission pattern of the infrared emitter 135 may be encoded with a defined pattern for use in determining depth or distance information of an illuminated target. The IR portion 120 may be in the 800 to 850 nanometer wavelength range.

[0019] In some examples, the first tunable filter 140 and the second tunable filter 150 may be liquid crystal (LC) tunable filters. Each of the first tunable filter 140 and the second tunable filter 150 may include one or more electronically switchable LC wave plates to transmit a particular band of light, and to exclude others bands of light. Further, each LC tunable filter may include any number of polarizers and/or glass substrates. In some examples, each LC tunable filter may comprise holographically-formed, polymer dispersed liquid crystal material. In other examples, each of the first tunable filter 140 and the second tunable filter 150 may include multiple mirror layers and/or reflection gratings. A first mirror layer may be partially reflective, and a second mirror layer may have with variable effective reflectivity. In still other examples, each of the first tunable filter 140 and the second tunable filter 150 may be an acousto-optical tunable filter. As shown, in some examples, the first tunable filter 140 and the second tunable filter 150 may be positioned such that their light- receiving surfaces are aligned to receive the light entering the optical aperture 130.

[0020] In some examples, the imaging module 190 may control the first tunable filter 140 and the second tunable filter 150 to selectively provide either the VL portion 110 and the IR portion 120 to the image sensor 160. For instance, the first tunable filter 140 may always be substantially transparent to the IR portion 120, but may be tuned by a provided voltage to either block or pass the VL portion 110. Further, the second tunable filter 150 may always be substantially transparent to the VL portion 110, but may be tuned by a provided voltage to either block or pass the IR portion 120. An example imaging operation of the device 100 is described below with reference to Figs. 2 and 3A-3B. In some examples, the processor(s) 180 executing instructions included in the imaging module 190 can be a controller of device 100.

[0021] Referring now to Fig. 2, shown is a process 200 for an example process for an imaging operation using tunable filters. The process 200 may be performed by the processor(s) 180 and/or the imaging module 190 shown in Fig. 1. The process 200 may be implemented in hardware or machine-readable instructions (e.g., software and/or firmware). The machine-readable instructions are stored in a non-transitory computer readable medium, such as an optical, semiconductor, or magnetic storage device. For the sake of illustration, details of the process 200 may be described below with reference to Figs. 1 and 3A-3B.

[0022] At 210, an indication to capture image(s) may be received by an electronic device. For example, referring to Fig. 1, the imaging module 190 of the device 100 may receive a command or instruction to capture a visible light (VL) image, to capture an infrared (IR) image, or to capture both a VL image and an IR image. In some examples, the received command or instruction may trigger a shutter of the optical aperture 130, and thereby cause the optical aperture 130 to receive light input (e.g., both the VL portion 110 and the IR portion 120 shown in Fig. 1). [0023] In response to the indication to capture image(s), at 220, a determination is made about whether the image(s) to be captured is only a VL image. For example, referring to Fig. 1, the imaging module 190 may determine whether a received command or instruction is to only capture a VL image.

[0024] If it is determined at 220 that the image to be captured is only a VL image, then the process 200 continues at 270 (described below). However, if it is determined at 220 that the image(s) to be captured is not only a VL image, then at 230, a first tunable filter may be controlled to block a VL portion of an input image. For example, referring to Fig. 3A, the imaging module 190 (not shown) may cause a control voltage VI to be provided to the first tunable filter 140, thereby controlling the first tunable filter 140 to block the VL portion 110. Further, because the first tunable filter 140 is always transparent to IR light, the first tunable filter 140 may pass the IR portion 120.

[0025] At 240, a second tunable filter may be controlled to pass an IR portion of the input image. For example, referring to Fig. 3 A, the imaging module 190 may cause a control voltage V2 to be provided to the second tunable filter 150, thereby controlling the second tunable filter 150 to pass the IR portion 120.

[0026] At 250, an IR image may be captured using an image sensor. For example, referring to Fig. 3 A, the imaging module 190 may control the image sensor 160 to capture an IR image using the IR portion 120 passed by both the first tunable filter 140 and the second tunable filter 150.

[0027] At 260, a determination is made about whether the image(s) to be captured include both an IR image and a VL image. For example, referring to Fig. 1, the imaging module 190 may determine whether a received command or instruction is to capture an IR image only, or is to capture both an IR image and a VL image.

[0028] If it is determined at 260 that the image(s) to be captured do not include both an IR image and a VL image, then the process 200 is completed. However, if it is determined at 260 that the image(s) to be captured include both an IR image and a VL image, then the process 200 continues at 270. Note that, as discussed above, the process 200 can also continue at 270 when only a VL image is captured (i.e., upon a positive determination at 220).

[0029] At 270, the first tunable filter is controlled to pass the VL portion of the input image. For example, referring to Fig. 3B, the imaging module 190 may cause a control voltage V3 to be provided to the first tunable filter 140, thereby controlling the first tunable filter 140 to pass the VL portion 110. Further, because the first tunable filter 140 is always transparent to IR light, the first tunable filter 140 may also pass the IR portion 120.

[0030] At 280, a second tunable filter may be controlled to block the IR portion of the input image. For example, referring to Fig. 3B, the imaging module 190 may cause a control voltage V4 to be provided to the second tunable filter 150, thereby controlling the second tunable filter 150 to block the IR portion 120. However, because the second tunable filter 150 is always transparent to VL light, the second tunable filter 150 may pass the VL portion 110

[0031] At 290, a VL image may be captured using the image sensor. For example, referring to Fig. 3B, the imaging module 190 may control the image sensor 160 to capture a VL image using the VL portion 110 passed by both the first tunable filter 140 and the second tunable filter 150. After 290, the process 200 is completed.

[0032] Referring again to Fig. 1, in some examples, the first tunable filter 140 may be electronically tuned to pass only a specific color band of the VL portion 110. Further, the imaging module 190 may control the first tunable filter 140 to sequentially pass a set of color bands included in the VL portion 110. For example, the imaging module 190 may control the first tunable filter 140 to a red color band, a green color band, and a blue color band in sequence. In addition, the imaging module 190 may control the image sensor 160 to capture separate color images using the separate color bands passed by the first tunable filter 140. In some examples, by capturing these color images separately, the image sensor 160 may be used without including a color filter (e.g., a Bayer pattern filter). Further, in some examples, the imaging module 190 may combine the separate color images into a single combined VL image. [0033] Referring now to Fig. 4, shown is a schematic diagram of an example device 400 that includes an angled tunable filter. The device 400 may be all or a portion of any electronic, such as a mobile telephone, a computer, a server, a media player, a personal digital assistant, a tablet, a network device, etc.

[0034] As shown, the device 400 can include an optical aperture 130, an infrared emitter 135, processor(s) 180, memory 185, and machine -readable storage 195, which were described above with reference to Fig. 1. In addition, the device 400 can also include a tunable filter 240, a VL sensor 165, and an IR sensor 170. In some examples, the VL sensor 165 may be a sensor to capture VL images using the VL portion 110. Further, the IR sensor 170 may be a sensor to capture IR images using the IR portion 120.

[0035] In some examples, the tunable filter 240 may be a liquid crystal (LC) tunable filter. Further, the tunable filter 240 may have a refractive index that is variable by applying different voltage levels. The tunable filter 240 may include liquid crystal material having constructive and/or deconstructive interference under certain wavelengths of light, thereby enabling the tunable filter 240 to pass and/or block specific wavelengths. Further, the tunable filter 240 may include any number of polarizers and/or glass substrates. In some examples, the tunable filter 240 may comprise holographically-formed, polymer dispersed liquid crystal material. In other examples, the tunable filter 240 may include multiple mirror layers and/or reflection gratings. A first mirror layer may be partially reflective, and a second mirror layer may have with variable effective reflectivity. In still other examples, the tunable filter 240 may be an acousto-optical tunable filter.

[0036] In some examples, the tunable filter 240 may include a multi-layer one-fourth wavelength stack with alternative high/low refractive index to pass optical wavelengths (e.g., a Distributed Bragg Reflector (DBR)). Further, the tunable filter 240 may have a peak wavelength that varies according to angle of incidence.

[0037] In some examples, the tunable filter 240 may be disposed at an angle of incidence 117 relative to a path of light entering the optical aperture 130. For example, the angle of incidence 117 between the optical surface of the tunable filter 240 and the light path may set to thirty degrees, to forty-five degrees, to sixty degrees, and so forth. [0038] In some examples, the tunable filter 240 may have a refractive index in the infrared band such that, at the angle of incidence 117, the IR portion 120 is reflected off the surface of the tunable filter 240. Further, the tunable filter 240 may be positioned such that the IR portion 120 that reflects off the tunable filter 240 is directed into the IR sensor 170. In this manner, the IR sensor 170 may capture an IR image using the reflected IR portion 120.

[0039] In some examples, the tunable filter 240 may have a refractive index in the visible light band such that, at the angle of incidence 117, the VL portion 110 is not reflected off the surface of the tunable filter 240. Further, in some examples, the tunable filter 240 may be electronically tuned to pass only a specific sub-portion 115 (e.g., a first color band) of the VL portion 110, and to block a remainder (e.g., other color bands) of the VL portion 110. For example, the imaging module 190 may control the tunable filter 240 to pass one of multiple color bands (e.g., a red color band), and to block a remainder of the multiple colors bands (e.g., a green color band and a blue color band). In some examples, the imaging module 190 may control the tunable filter 240 to pass multiple color bands. Further, the imaging module 190 may control the tunable filter 240 to block all of the VL portion 110.

[0040] As shown in Fig. 4, in some examples, each sub-portion 115 passing through the tunable filter 240 may be provided to the VL sensor 165. Further, the VL sensor 165 may capture a VL image for each sub-portion 115. For example, the imaging module 190 may control the tunable filter 240 such that the sub-portion 115 forms a sequence of a red color band, a green color band, and a blue color band. In this manner, the VL sensor 165 may sequentially capture a red image, a green image, and a blue image. In some examples, the sequential capture of different color images may enable the device 400 to not include an optical color filter.

[0041] In some examples, the imaging module 190 may process the multiple color images captured by the VL sensor 165 separately, or may combine them into a multiple-color image (e.g., a red-green-blue (RGB) image). The resulting VL image(s) may be used for photo and/or video applications. In some examples, the sequential capture of different color images may provide greater overall image brightness than is possible with a single captured image that includes multiple colors. An example imaging operation of the device 400 is described below with reference to Figs. 5 and 6A-6C. In some examples, the processor(s) 180 executing instructions included in the imaging module 190 can be a controller of device 400.

[0042] Referring now to Fig. 5, shown is an example process 500 for an imaging operation using an angled tunable filter. The process 500 may be performed by the processor(s) 180 and/or the imaging module 190 shown in Fig. 4. The process 500 may be implemented in hardware or machine-readable instructions (e.g., software and/or firmware). The machine-readable instructions are stored in a non-transitory computer readable medium, such as an optical, semiconductor, or magnetic storage device. For the sake of illustration, details of the process 500 may be described below with reference to Figs. 4 and 6A-6C.

[0043] At 510, an indication to capture image(s) may be received by an electronic device. For example, referring to Fig. 4, the imaging module 190 of the device 400 may receive a command or instruction to capture a visible light (VL) image, to capture an infrared (IR) image, or to capture both a VL image and an IR image. In some examples, the received command or instruction may trigger a shutter of the optical aperture 130, and thereby cause the optical aperture 130 to receive a light input (e.g., both the VL portion 110 and the IR portion 120 shown in Fig. 4).

[0044] In response to the indication to capture image(s), at 520, a determination is made about whether the image(s) to be captured is only a VL image. For example, referring to Fig. 4, the imaging module 190 may determine whether a received command or instruction is to only capture a VL image.

[0045] If it is determined at 520 that the image to be captured is only a VL image, then the process 500 continues at 560 (described below). However, if it is determined at 520 that the image(s) to be captured is not only a VL image, then at 530, an IR portion of a light input may be reflected using the tunable filter. For example, referring to Fig. 4, the tunable filter 240 may be disposed at a forty- five degree angle relative to the light input, and may reflect the IR portion 120 at a ninety degree angle into the IR sensor 170. [0046] At 540, an IR image may be captured using the reflected IR image. For example, referring to Fig. 4, the imaging module 190 may control the IR sensor 170 to capture an IR image using the IR portion 120 reflected off the tunable filter 240.

[0047] At 550, a determination is made about whether the image(s) to be captured include both an IR image and a VL image. For example, referring to Fig. 4, the imaging module 190 may determine whether a received command or instruction is to capture both an IR image and a VL image, or is to capture only an IR image.

[0048] If it is determined at 550 that the image(s) to be captured do not include both an IR image and a VL image, then the process 500 is completed. However, if it is determined at 550 that the image(s) to be captured include both an IR image and a VL image, then the process 500 continues at 560. Note that, as discussed above, the process 500 can also continue at 560 when only a VL image is to be captured (i.e., upon a positive determination at 520).

[0049] At 560, the tunable filter may be controlled to pass a single VL color band. For example, referring to Figs. 4 and 6A, the imaging module 190 may cause a control voltage V5 to be provided to the tunable filter 240, thereby controlling the tunable filter 240 to pass the red color band 110R, and to block the green color band HOG and the blue color band HOB.

[0050] At 570, a single color image may be captured using a VL image sensor. For example, referring to Figs. 4 and 6A, the imaging module 190 may control the VL sensor 165 to capture a red color image using the red color band 110R passed by the tunable filter 240.

[0051] At 580, a determination is made about whether there are additional colors to be captured. If so, the process 500 returns to 560 to perform a loop. Specifically, for each color, the tunable filter passes another color band at 560, and the VL image sensor captures another color image at 570. For example, referring to Figs. 4 and 6B, the imaging module 190 may cause a control voltage V6 to be provided to the tunable filter 240, thereby controlling the tunable filter 240 to pass the green color band HOG, and to block the red color band 110R and the blue color band HOB. The imaging module 190 may then control the VL sensor 165 to capture a green color image using the green color band HOG. In addition, referring to Figs. 4 and 6C, the imaging module 190 may cause a control voltage V7 to be provided to the tunable filter 240, thereby controlling the tunable filter 240 to pass the blue color band HOB, and to block the red color band 110R and the green color band HOG. The imaging module 190 may then control the VL sensor 165 to capture a blue color image using the blue color band HOB. After all color images are captured, the process 500 is completed.

[0052] Referring now to Fig. 7, shown is a schematic diagram of an example device 700 that includes a tunable filter. The device 700 may be all or a portion of any electronic, such as a mobile telephone, a computer, a server, a media player, a personal digital assistant, a tablet, a network device, etc.

[0053] As shown, the device 700 can include an optical aperture 130, an infrared emitter 135, image sensor 160, processor(s) 180, memory 185, machine-readable storage 195, which were described above with reference to Fig. 1. In addition, the device 700 can also include an IR/VL tunable filter 740. In some examples, the IR/VL tunable filter 740 may be a liquid crystal (LC) tunable filter. Further, in some examples, the IR/VL tunable filter 740 may be a combination of the first tunable filter 140 and the second tunable filter 150 described above with reference to Fig. 1. The IR/VL tunable filter 740 may also include any number of polarizers and/or glass substrates. In some examples, the IR/VL tunable filter 740 may comprise holographically-formed, polymer dispersed liquid crystal material. In other examples, the IR VL tunable filter 740 may include multiple mirror layers and/or reflection gratings. A first mirror layer may be partially reflective, and a second mirror layer may have with variable effective reflectivity. In still other examples, the IR/VL tunable filter 740 may be an acousto-optical tunable filter.

[0054] In some examples, the IR/VL tunable filter 740 may be electronically tuned to pass only a specific color band of the VL portion 110, or to pass only the IR portion 120. For example, the imaging module 190 may control the IR/VL tunable filter 740 to pass a red color band, a green color band, a blue color band, and the IR portion 120 in a sequence to the image sensor 160. Further, the image sensor 160 may capture IR and color images using the color bands and the IR portion 120 passed by the IR/VL tunable filter 740. In some examples, the imaging module 190 may combine the separate color images to obtain a single combined VL image. The imaging module 190 may use the IR image to determine depth and/or biometric information associated with the VL image. In addition, the imaging module 190 may control the IR/VL tunable filter 740 to block both the VL portion 110 and the IR portion 120. An example imaging operation of the device 700 is described below with reference to Fig. 8. In some examples, the processor(s) 180 executing instructions included in the imaging module 190 can be a controller of device 700.

[0055] Referring now to Fig. 8, shown is an example process 800 for an imaging operation using a tunable filter. The process 800 may be performed by the processor(s) 180 and/or the imaging module 190 shown in Fig. 7. The process 800 may be implemented in hardware or machine -readable instructions (e.g., software and/or firmware). The machine- readable instructions are stored in a non-transitory computer readable medium, such as an optical, semiconductor, or magnetic storage device. For the sake of illustration, details of the process 800 may be described below with reference to Fig. 7.

[0056] At 810, an indication to capture image(s) may be received by an electronic device. For example, referring to Fig. 7, the imaging module 190 of the device 700 may receive a command or instruction to capture visible light (VL) and infrared (IR) images. In some examples, the received command or instruction may trigger a shutter of the optical aperture 130, and thereby cause the optical aperture 130 to receive a light input (e.g., both the VL portion 110 and the IR portion 120 shown in Fig. 7).

[0057] In response to the indication to capture image(s), at 820, an tunable filter may be controlled to pass each of a plurality of color bands and an IR portion in a sequence. For example, referring to Fig. 7, the imaging module 190 may control the IR/VL tunable filter 740 to pass the IR portion 120 and each of multiple color bands (e.g., red, green, and blue color bands) of the VL portion 110.

[0058] At 830, a plurality of color images and an IR image may be captured using an image sensor. For example, referring to Fig. 7, the imaging module 190 may control the image sensor 160 to capture an IR image using the IR portion 120 passed by the IR/VL tunable filter 740. In another example, the imaging module 190 may control the image sensor 160 to capture a red VL image using a red color band passed by the IR/VL tunable filter 740. In some examples, the image sensor 160 may capture the color images and the IR image in a sequence. After all images are captured at 830, the process 800 is completed.

[0059] In some examples, the VL and IR images captured by device 100, device 400, and/or device 700 may be used for various applications. For example, the VL images may be used for photo and/or video applications. Further, the IR images may be used to determine depth information associated with VL images for use in three-dimensional (3D) applications. In addition, the IR images may be used for biometric applications (e.g., facial recognition), for receiving user inputs or gestures, for motion capture, for camera focusing, and so forth.

[0060] In accordance with some examples, techniques and/or mechanisms are provided to capture visible light and infrared images from an input image. In some examples, a liquid crystal (LC) tunable filter may be used to selectively filter specific bands of energy, and one or more sensors may capture separate visible light and infrared images. Some examples may enable the capture of visible light and infrared images using simple and cost-effective components. Note that, while Figs. 1-8 show some examples, it is contemplated that each of the features described above with reference to Figs. 1-8 may combined and/or used with any other features described herein.

[0061] Data and instructions are stored in respective storage devices, which are implemented as one or multiple computer-readable or machine-readable storage media. The storage media include different forms of non-transitory memory including semiconductor memory devices such as dynamic or static random access memories (DRAMs or SRAMs), erasable and programmable read-only memories (EPROMs), electrically erasable and programmable read-only memories (EEPROMs) and flash memories; non-volatile memory (NVM), magnetic disks such as fixed, floppy and removable disks; other magnetic media including tape; optical media such as compact disks (CDs) or digital video disks (DVDs); or other types of storage devices.

[0062] Note that the instructions discussed above can be provided on one computer- readable or machine-readable storage medium, or alternatively, can be provided on multiple computer-readable or machine-readable storage media distributed in a large system having possibly plural nodes. Such computer-readable or machine -readable storage medium or media is (are) considered to be part of an article (or article of manufacture). An article or article of manufacture can refer to any manufactured single component or multiple components. The storage medium or media can be located either in the machine running the machine-readable instructions, or located at a remote site from which machine -readable instructions can be downloaded over a network for execution.

[0063] In the foregoing description, numerous details are set forth to provide an understanding of the subject disclosed herein. However, some examples may be practiced without some of these details. Other examples may include modifications and variations from the details discussed above. It is intended that the appended claims cover such modifications and variations.

Claims

What is claimed

1. An electronic device comprising:

a first tunable filter;

a second tunable filter;

an image sensor to receive image components passed by the first tunable filter and the second tunable filter; and

a controller to:

during a first time period, control the first tunable filter to block an visible light (VL) portion of an image input, control the second tunable filter to pass a infrared (IR) portion of the image input, and control the image sensor to capture an IR image using the IR portion of the image input; and

during a second time period, control the first tunable filter to pass the VL portion of the image input, control the second tunable filter to block the IR portion of the image input, and control the image sensor to capture a VL image using the VL portion of the image input.

2. The electronic device of claim 1, wherein the first tunable filter and the second tunable filter are liquid crystal (LC) tunable filters.

3. The electronic device of claim 1, wherein the first tunable filter is substantially transparent to IR light.

4. The electronic device of claim 1, wherein the second tunable filter is substantially transparent to visible light.

5. The electronic device of claim 1, wherein the IR image comprises depth information associated with the VL image.

6. The electronic device of claim 1, further comprising an optical aperture to receive the image input.

7. The electronic device of claim 1, further comprising an IR emitter to illuminate a target.

8. An article comprising a non-transitory machine-readable storage medium storing instructions that upon execution cause at least one hardware processor to:

receive an indication to capture an infrared (IR) portion and a visible light (VL) portion of an input image; and

in response to a receipt of the indication:

control an IR/VL tunable filter to pass each of a plurality of color bands and the IR portion in a sequence, wherein the VL portion comprises the plurality of color bands, and

control the image sensor to capture a plurality of color images and an IR image using the plurality of color bands and the IR portion passed by the IR/VL tunable filter.

9. The article of claim 8, wherein the instructions further cause the processor to: combine the plurality of color images to obtain a combined VL image.

10. The article of claim 9, wherein the instructions further cause the processor to: use the IR image to determine biometric information associated with the combined VL image ..

11. The article of claim 8, wherein the IR/VL tunable filter is a liquid crystal (LC) tunable filter.

12. An apparatus comprising:

a liquid crystal (LC) tunable filter to reflect an infrared (IR) portion of an image input, and to pass a plurality of color bands included in a visible light (VL) portion of the image input;

an infrared (IR) image sensor to receive the IR portion reflected by the LC tunable filter;

a VL image sensor to receive the plurality of color bands passed by the LC tunable filter; and

a controller to, for each color band of the plurality of color bands in turn:

control the LC tunable filter to pass the color band and block a remainder of the plurality of color bands, and

control the VL image sensor to capture a color image using the color band passed by the LC tunable filter.

13. The apparatus of claim 12, wherein the LC tunable filter is positioned at a forty- five degree angle relative to an input light path.

14. The apparatus of claim 12, wherein the controller is to provide different voltages to the LC tunable filter to control which color band is passed by the LC tunable filter.

15. The apparatus of claim 12, wherein:

the plurality of color bands comprise red, blue, and green color bands; and

the controller is to combine the captured color images into a single red-green-blue (RGB) image.