Contrast enhancing active polarization

Abstract

Scene light is received by a photosensor through a switchable waveplate and a spatial frequency optical element. An intensity signal is generated with the photosensor in response to receiving the scene light. The switchable waveplate is driven in response to the intensity signal.

Description

Attorney Docket No.: EIDOP102PCTCONTRAST ENHANCING ACTIVE POLARIZATION CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. non-provisional Application No.19 / 046,740 filed February 6, 2025, which is hereby incorporated by reference.TECHNICAL FIELD

[0002] This disclosure relates generally to optics, and in particular to contrast enhancing active polarization.BACKGROUND INFORMATION

[0003] In certain contexts, selectively imaging with respect to wavelength or polarization orientation is helpful. For example, some sunglasses block or attenuate blue light wavelengths (e.g. 400 nm - 450 nm) to reduce glare for the wearer since the shorter wavelengths of blue light may be scattered more easily than longer wavelengths of visible light. In another example, polarized sunglasses block or reflect one particular polarization orientation of light that is more likely to produce glare from sunlight reflecting off of water, for example.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Non-limiting and non-exhaustive embodiments of the invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

[0005] FIG. 1 illustrates an example scene including a skier skiing down a mountain slope, in accordance with aspects of the disclosure.

[0006] FIG. 2 illustrates an optical device having a frame securing an optical element, in accordance with aspects of the disclosure.

[0007] FIG. 3A illustrates an example optical system that may be implemented in optical devices, in accordance with aspects of the disclosure.

[0008] FIG. 3B illustrates an example optical system having more than one sensor module, in accordance with aspects of the disclosure.Attorney Docket No.: EIDOP102PCT

[0009] FIG. 4A illustrates an example timing diagram for measuring intensity signals, in accordance with aspects of the disclosure.

[0010] FIG. 4B illustrates an example timing diagram for measuring intensity signals and multiplexing optical values, in accordance with aspects of the disclosure.

[0011] FIG. 5 illustrates an example optical system including a sensor array that may be implemented in optical devices, in accordance with aspects of the disclosure.

[0012] FIG. 6 illustrates an example process of contrast enhancement based on spatial frequency, in accordance with aspects of the disclosure.DETAILED DESCRIPTION

[0013] Embodiments of contrast enhancing active polarization are described herein. In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.

[0014] Reference throughout this specification to "‘one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0015] In aspects of this disclosure, visible light may be defined as having a wavelength range of approximately 380 nm - 700 nm. Non-visible light may be defined as light having wavelengths that are outside the visible light range, such as ultraviolet light and infrared light. Infrared light having a wavelength range of approximately 700 nm - 1 mm includes near-infraredAttorney Docket No.: EIDOP102PCTlight. In aspects of this disclosure, near-infrared light may be defined as having a wavelength range of approximately 700 nm - 1.6 pm.

[0016] In aspects of this disclosure, the term “transparent"’ may be defined as having greater than 90% transmission of light. In some aspects, the term “transparent"’ may be defined as a material having greater than 90% transmission of visible light.

[0017] In certain contexts, increasing visibility and contrast for a particular spatial frequency is desirable. By way of example, a skier or snowboarder may be interested in recognizing terrain features such as moguls in order to navigate through or around the terrain features. These terrain features may have a different spatial frequency than other terrain features such as a large slope that is more easily recognized or smaller features that are inconsequential to recognize during w inter sports experiences. Of course, increasing visibility and contrast in other contexts may also be desirable.

[0018] In implementations of this disclosure, a photosensor is placed between a switchable waveplate and a spatial frequency optical element. The switchable w aveplate may include a liquid crystal layer configured to change an orientation of liquid crystals based on a received voltage, for example. Processing logic drives an optical retardation value onto the switchable waveplate in response to an intensity' signal generated by the photosensor receiving scene light through the switchable w-aveplate and the spatial frequency optical element. The processing logic may drive the switchable w aveplate to increase (or approach maximization) of the intensity signal generated by the photosensor. This system may be implemented in a w earable such as ski googles or sunglasses so that the scene light propagating to the eye of a user is selected (by the switchable waveplate) to provide enhanced contrast for particular spatial frequencies in the external environment. The spatial frequency optical element may be selected to match a particular spatial frequency of a feature (at a particular distance) that the user desires to see with enhanced contrast. For example, a mogul may be between 6 inches and 36 inches and the spatial frequency optical element may be configured to maximize transmission of the sceneAttorney Docket No.: EIDOP102PCTlight associated with that chosen spatial frequency at a certain distance. For example, a skier may want to enhance their view for terrain features (e g. moguls) at a distance of 20 feet, 40 feet, or 100 feet, for example. The switchable waveplate may select for polarization orientations of the scene light that increases (or approaches maximization) of the intensity of the scene light at the specified spatial frequency. In some implementations, a wearable device includes additional photosensors associated with different spatial frequency filters so that the enhancement of different spatial frequencies can be selected by the user. These and other embodiments are described in more detail in connection with FIGs. 1-6.

[0019] FIG. 1 illustrates an example scene 101 having a skier 180 skiing down a mountain slope, in accordance with aspects of the disclosure. In example environments such as winter sports, a user may be particularly interested in features with a certain spatial frequency. In snowy conditions, changing weather conditions and varying terrain may contribute to fastchanging lighting conditions. The changing lighting conditions may include very bright conditions wdth the sun 185 reflecting off of the snow; for example. The user may be able to ascertain features of the terrain with very large spatial frequencies (e.g. large trees, hills, valleys), but struggle to view smaller features because of a lack of contrast from sunlight reflecting off the snow; Additionally, some snow feature may be too small for skier 180 to care about such as approximately 1 ” patterns in the snow that the skis of skier 180 will easily absorb. Depending on the angle of the sun, features with a particular spatial frequency (e g. moguls 190) may reflect a specific polarization orientation of sunlight. However, as skier 180 moves through the terrain, the specific polarization orientation and intensity of the sunlight may change.

[0020] In FIG. 1, skier 180 is wearing optical device 100 on their head. Optical device 100 enhances the contrast of selected spatial frequencies by modulating scene light from the external environment. In FIG. 1, optical device 100 takes the form of goggles although optical device 100 may take a variety of forms (e.g. glasses or visor) to be worn on the head of the user. The aspects of the disclosure may also be implemented in a visor of a helmet. The aspects of theAttorney Docket No.: EIDOP102PCTdisclosure may also be implemented in other contexts to enhance contrast for certain spatial frequencies. Other example contexts may include aerospace, police, and / or military engagements.

[0021] FIG. 2 illustrates optical device 200 having a frame 210 securing an optical element 215, in accordance with aspects of the disclosure. Optical element 215 may be considered a lens, in some contexts. Optical device 200 may be worn on ahead of user. FIG. 2 shows optical device in a google form-factor. Optical device 200 includes sensor modules 230A, 230B, 230C, 230D, 230E, and 230F (collectively referred to sensor modules 230). Optical device 200 may include only one sensor module 230 or a pl urality of sensor modules 230. The sensor modules 230 may be spread around in different locations or be disposed adjacent to each other. Sensor modules 230 are configured to receive scene light from the external environment.

[0022] FIG. 3A illustrates an example optical system 300 that may be implemented in optical devices 100 or 200, in accordance with aspects of the disclosure. System 300 includes a switchable waveplate 360 and a polarizer layer 350. System 300 also includes sensor module 330. Sensor module 330 may be one example of sensor modules 230, in FIG. 2. Sensor module 330 includes spatial frequency optical element 341 and photosensor 331. Notably, photosensor 331 receives scene light 391 through switchable waveplate 360, polarizer layer 350, and spatial frequency optical element 341, in the specific implementation of FIG. 3A. Photosensor 331 may be implemented as a single photodiode. Photosensor 331 may be implemented as an array of photodiodes. Photosensor 331 may be implemented as an array of photodiodes arranged in rows and columns. Photosensor 331 may be implemented as a complementary metal-oxide semiconductor (CMOS) image sensor.

[0023] Polarizer layer 350 is disposed between spatial frequency optical element 341 and switchable waveplate 360, in FIG. 3A. Polarizer layer 350 may include a polanzer that reflects or absorbs a particular polarization orientation of scene light. For example, the polarizerAttorney Docket No.: EIDOP102PCTmay absorb or reflect a vertical polarization orientation or a horizontal polarization orientation. Polarizer layer 350 may be a wire-grid polarizer, in some implementations.

[0024] Polarizer layer 350 and switchable waveplate 360 may be included in a lens of an optical element (e.g. optical element 215). While not particularly illustrated, a fixed dimming layer and / or wavelength filter may also be included in the optical element. Polarizer layer 350 and switchable waveplate 360 may extend to within a frame (e.g. frame 210) so that switchable waveplate 360 and polarizer layer 350 modulates scene light 391 propagating to eye 303 of a user in addition to modulating scene light 391 that eventually propagates to spatial frequency optical element 341 as light 395. The percentage of light 393 that polarizer layer 350 reflects or absorbs will depend on the optical retardation value driven onto switchable waveplate 360 to change the polarization orientation of scene light 391.

[0025] Spatial frequency optical element 341 selectively transmits light 395 based on spatial frequencies. Spatial frequency optical element 341 may be configured to selectively transmit light 395 based on spatial frequencies at a specific distance (e.g. 20 feet, 40 feet, 100 feet, or otherwise) from the sensor module 330. Spatial frequency optical element 341 may be implemented as a spatial frequency grating. Spatial frequency optical element 341 may be configured to maximize transmission of light from features in a scene with a spatial frequency of between 6 inches and 36 inches while blocking or reducing transmission of light from features in the scene with a spatial frequency of less than 6 inches or greater than 36 inches. In an implementation, spatial frequency optical element 341 is configured to maximize transmission of light from features in a scene with a spatial frequency of betw een 6 inches and 24 inches while blocking or reducing transmission of light from features in the scene with a spatial frequency of less than 6 inches or greater than 24 inches. In an implementation, spatial frequency optical element 341 is configured to maximize transmission of light from features in a scene with a spatial frequency of between 6 inches and 12 inches while blocking or reducing transmission of light from features in the scene with a spatial frequency of less than 6 inches or greater than 12Attorney Docket No.: EIDOP102PCTinches. In an implementation, spatial frequency optical element 341 is configured to maximize transmission of light from features in a scene with a spatial frequency of between 3 inches and 12 inches while blocking or reducing transmission of light from features in the scene with a spatial frequency of less than 3 inches or greater than 12 inches. Of course, other spatial frequency ranges may also be written into spatial frequency optical element 341.

[0026] Spatial frequency optical element 341 may be implemented as an annular aperture or mask that passes the desired spatial frequency range while blocking spatial frequencies outside the range. The selectivity' of the spatial frequency filter may depend on the size of the central obstruction (that blocks the light) and the width of the annular ring (that transmits light). The size of the central obstruction may set the cutoff frequency of spatial frequencies that will be blocked while the width of the annular region may determine the range of spatial frequencies that are passed. Low spatial frequencies are located near the center of the annular aperture (and are thus blocked), w hereas higher spatial frequences pass through the annular region located farther from the center of the annular aperture.

[0027] Spatial frequency optical element 341 may function to emphasize features at specific spatial scales and viewing angles by use of diffraction and interference of the scene light. Spatial frequency optical element 341 may be implemented with repeating structures (e g. lines, dots, or patterns) with a specific periodicity that interacts with incoming scene light. These structures may function as a Fourier filter that allow- or block certain spatial frequencies corresponding to feature sized in the image.

[0028] In implementations of the disclosure, spatial frequency optical element are implemented w ith a liquid crystal display where the size of the central obstruction and the width of the annular ring can be changed dynamically by driving different black and white images onto the liquid crystal display. Pixels in the liquid crystal display can be driven to black (blocking light) or white (passing light). In this implementation, processing logic 310 may be configured to drive an image onto the liquid crystal display used as spatial frequency optical element 341.Attorney Docket No.: EIDOP102PCTNotably, the desired spatial frequency range of the spatial frequency optical element may be changed simply by changing the image driven onto the liquid crystal display.

[0029] Spatial frequency optical element 341 may be disposed in the Fourier plane of the imaging system of sensor module 330, in some implementations. Additional refractive or diffractive lenses may be added to the imaging system of sensor module 330 to facilitate the spatial frequency fdtering functionality' of spatial frequency optical element 341.

[0030] Switchable waveplate 360 may be configured to change the polarization orientation of incoming scene light 391 in response to an optical retardation value 361 driven onto switchable waveplate 360. Switchable waveplate 360 may be a switchable half-waveplate configured to rotate the polarization of light between 0 degrees and 90 degrees, in some implementations. In some implementations, switchable waveplate 360 is implemented as a liquid crystal layer including liquid cry stals and a voltage driven across two transparent panels of the liquid cry stal layer changes the orientation of the liquid crystals in order to change the polarization orientation of scene light 391. Switchable waveplate 360 may' be driven in granular increments to rotate scene light 391. For example, optical retardation value 361 may drive switchable wav eplate 360 to rotate scene light 391 by 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees, 85 degrees, and / or 90 degrees. More granular optical retardation values are also possible to be driven onto switchable waveplate 360.

[0031] Processing logic 310 is configured to drive an optical retardation value 361 onto switchable waveplate 360 in response to receiving an intensity signal 336 generated by photosensor 331 in response to light 397 that is the scene light 391 received through switchable waveplate 360, polarizer layer 350, and the spatial frequency optical element 341. Processing logic 310 may be implemented as a microprocessor and / or a combination of analog and digital circuits.Attorney Docket No.: EIDOP102PCT

[0032] Processing logic 310 may be configured to drive switchable waveplate 360 to maximize or approach maximization of the intensity signal 336 generated by photosensor 331. In this disclosure, the term “maximize” may mean to be within 10% of maximizing the intensity of light. To maximize (or approach maximization of intensity signal 336), processing logic 310 may drive switchable waveplate 360 through incremental optical retardation values 361 during a “searching period”. By way of example, processing logic 310 may drive switchable waveplate 360 to rotate scene light 391 by 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees, 85 degrees, and 90 degrees and sample / measure intensity signal 336 for each optical retardation values 361. Whichever intensity value is highest, processing logic 310 will drive switchable waveplate 360 to the optical retardation value that corresponds to the highest intensity value 336 during a “viewing period.” The “viewing period” may be much longer than the “searching period.” The searching period may be 10 ms or less while the viewing period may be 50 ms, for example. Because of the persistence characteristics of eye 303, the searching period will be over a time period that is unnoticed by the user while the user will enjoy contrast enhancement of the spatial frequency of selected features during the “viewing period.” After the “viewing period” is finished, processing logic 310 may execute the “searching period” to adjust driving switchable waveplate 360 to update to changing scene light 391.

[0033] Because photosensor 331 receives light 395 through switchable waveplate 360, polarizer layer 350, and spatial frequency optical element 341, the maximized intensity' signal 336 corresponds with an optical retardation value driven onto switchable waveplate 360 that maximizes the light from spatial frequencies passed by spatial frequency optical element 341 (and potentially suppressing light intensity from features outside the selected spatial frequencies). Hence, if moguls 190 have a spatial frequency between 6 inches and 36 inches and spatial frequency optical element 341 is configured to maximize transmission of light from features in a scene with a spatial frequency of between 6 inches and 36 inches, the optical retardation valueAttorney Docket No.: EIDOP102PCT361 driven onto switchable waveplate 360 maximizes the intensity of light 395 (and consequently intensity signal 336) that passes through polarizer layer 350. Consequently, modulating switchable waveplate 360 can maximize the transmission of spatial frequency selected light 397 to photosensor 331 while light corresponding to other spatial frequencies (e.g.0-6 inches and 36 inches and larger) is more likely to be absorbed or reflected by polarizer layer 350. Thus, light 399 propagating to eye 303 is selected to maximize / highlight features in an external environment having the spatial frequency corresponding to the configuration of spatial frequency optical element 341.

[0034] In some implementations, during the “searching period,” processing logic 310 executes a searching function similar to a "binary search” in order to reduce the time of the searching period. By way of example, processing logic 310 may drive values of 0 degrees, 90 degrees and 45 degrees as the optical retardation value 361 during the searching period. If 45 degrees and 90 degrees optical retardation values yield the highest magnitude of intensity signal 336, processing logic 310 may then drive a 67.5 degree optical retardation value onto switchable waveplate 360 to search for the optical retardation value that maximizes intensity signal 336. If 0 degrees and 45 degrees optical retardation values yield the highest magnitude of intensity signal 336, processing logic 310 may then drive a 22.5 degree optical retardation value onto switchable waveplate 360 to search for the optical retardation value that maximizes intensity signal 336. This midpoint calculation process continues (within 2.5 degree or 5 degree increments) until the optical retardation value 361 is found to maximize intensity signal 336.

[0035] FIG. 3B illustrates an example optical system 301 having more than one sensor modules 330A and 330B (collectively referred to as sensor modules 330), in accordance with aspects of the disclosure. Optical system 301 may be implemented in optical devices 100 or 200. System 301 includes switchable waveplate 360 and polarizer layer 350. Sensor module 330A includes spatial frequency optical element 341 and photosensor 331. Sensor module 330B includes spatial frequency optical element 342 and photosensor 332.Attorney Docket No.: EIDOP102PCT

[0036] Photosensor 332 receives scene light 391 through switchable waveplate 360, polarizer layer 350, and spatial frequency optical element 342, in the specific implementation of FIG. 3B. Photosensor 332 may be implemented as a single photodiode. Photosensor 332 may be implemented as an array of photodiodes. Photosensor 332 may be implemented as an array of photodiodes arranged in rows and columns. Photosensor 332 may be implemented as a complementary metal-oxide semiconductor (CMOS) image sensor.

[0037] In an implementation, spatial frequency optical element 342 is configured to pass the same spatial frequency range as spatial frequency optical element 341. In this configuration, sensing modules 330A and 330B may be disposed on different locations on the optical device (e.g. optical device 200) so that scene light from different angles can be received by sensor modules 330. Processing logic 311 is configured to receive intensity signals 336 and 337. Processing logic 311 may be configured to drive switchable waveplate 360 to maximize (or approach maximizing) the intensity level of intensity signal 336 or intensity signal 337, whichever is greater.

[0038] Polarizer layer 350 and switchable waveplate 360 may extend to within a frame (e g. frame 210) so that switchable waveplate 360 and polarizer layer 350 modulates scene light 391 propagating to eye 303 of a user in addition to modulating scene light 391 that eventually propagates to spatial frequency optical element 342 as light 396. The percentage of light 393 that polarizer layer 350 reflects or absorbs will depend on the optical retardation value 362 driven onto switchable waveplate 360 to change the polarization orientation of scene light 391. Hence, the optical retardation value 362 driven onto switchable waveplate 360 determines the polarization orientation of light 393 and light 395 that eventually propagates to spatial frequency optical elements 341 and 342, in some implementations.

[0039] In some implementations, spatial frequency optical element 342 is configured to pass a different spatial frequency range as spatial frequency optical element 341. For example, spatial frequency optical element 341 may be configured to maximize transmission of light fromAttorney Docket No.: EIDOP102PCTfeatures in a scene with a spatial frequency of between 3 inches and 12 inches and spatial frequency optical element 342 may be configured to maximize transmission of light from features in a scene with a spatial frequency of between 24 inches and 48 inches. In some implementations (not illustrated), optical system 301 may include even more sensing modules 330 having different spatial frequency ranges than spatial frequency optical element 341 and spatial frequency optical element 342. For example, a third sensing module may have a spatial frequency optical element configured to maximize transmission of light from features in a scene with a spatial frequency of between 12 inches and 24 inches.

[0040] Optical system 301 includes a user input interface 317 configured to deliver an input signal 319 to processing logic 311. User input interface 317 may be an electrical switch, capacitive touchpad, or otherwise. User input interface 317 may be disposed on the optical device. User input interface 317 may be disposed off the optical device. User input interface 317 may be an application presented on a touchscreen of a mobile device and input signal 319 may be wirelessly delivered to processing logic 311. Input signal 319 may select for the spatial frequency range that the user desires to enhance the contrast for. For example, if the user selects a spatial frequency range of 24-48 inches and spatial frequency optical element 342 is configured to transmit light having the spatial frequency range of 24-48 inches, processing logic 311 may ignore intensity signal 336 and instead drive optical retardation value 362 in response to intensity signal 337.

[0041] FIG. 4A illustrates an example timing diagram 400 for measuring intensity signals, in accordance with aspects of the disclosure. Timing diagram 400 includes different time period to, ti, t2...tn. Time period to 401 through tn 409 may total to time segment 410.

[0042] In time period to 401, optical value 461 is driven onto switchable waveplate 360. While optical value 461 is driven onto switchable waveplate 360, the intensity signals 471 and 481 are measured by processing logic 311. Optical value 461 may be an optical retardation value (e.g. value 362) driven onto switchable waveplate 360 and intensity signals 471 and 481 mayAttorney Docket No.: EIDOP102PCTcorrespond to intensity signals 336 and 337 in FIG. 3B. Thus, intensity signal471 may represent the light intensity of light 397 propagating through spatial frequency optical element 341 and intensity signal 481 may represent the light intensity of light 396 propagating through spatial frequency optical element 342.

[0043] In time period ti 402, optical value 462 is driven onto switchable waveplate 360. While optical value 462 is driven onto switchable waveplate 360, the intensity7signals 472 and 482 are measured by processing logic 311. Optical value 462 may be an optical retardation value (e.g. value 362) ) driven onto switchable waveplate 360 and intensity signals 472 and 482 may correspond to intensity7signals 336 and 337 in FIG. 3B. Thus, intensity signal 472 may represent the light intensity7of light 397 propagating through spatial frequency optical element 341 and intensity signal 482 may represent the light intensity of light 396 propagating through spatial frequency optical element 342.

[0044] Similarly to time period to 401 and time period ti 402, time period t2403 includes processing logic 311 measuring intensity7signals 473 and 483 from photosensors 331 and 332 while optical value 463 is driven onto switchable waveplate 360. And, time period t3 404 includes processing logic 311 measuring intensity signals 474 and 484 from photosensors 331 and 332 while optical value 464 is driven onto switchable waveplate 360. These measurements continue until, in time period tn 409, processing logic 311 measures intensity signals 479 and 489 from photosensors 331 and 332 while optical value 469 is driven onto switchable waveplate 360.

[0045] In some implementations, time segment 410 is part of '‘searching period” to find the optical value that maximizes intensity signals 336 and 337. In these implementations, time periods to 401 through tn 409 may be short enough to be unnoticeable to a user. For example, each time period to 401 through tn 409 may be 5 ms or less. In some implementations, each time period to 401 through tn 409 is 2 ms or less. In some implementations, each time period to 401 through tn 409 is 1 ms or less. As described above, n may equal 19 where the optical retardationAttorney Docket No.: EIDOP102PCTvalue is driven onto switchable waveplate 360 in 5 degree increments (0 degrees, 5 degrees, 10 degrees... to 90 degrees). Integer n may equal nine if the optical retardation value is driven in 10 degree increments. Integer n may equal 91 if the optical retardation value is driven in 1 degree increments. If a binary search method is utilized, integer n may vary depending on how fast the searching function “finds” the optimal optical retardation value to maximize the intensity signals 336 and 337. Once the optimized intensity value is determined by processing logic 311, processing logic may drive the optical retardation value onto switchable waveplate 360 that optimized / maximized the intensity of light 397 and / or 396 for a “viewing period” so that a user can enjoy the enhanced contrast viewing of features having a spatial frequency that the user desires. After a time limit of the “viewing period,” processing logic 311 may restart the “searching period” function to ensure that the optical retardation value 362 is still the optimal retardation value due to changing light conditions. After this “searching period,” optical retardation value 362 may be adjusted or maintained for the subsequent “viewing period.”

[0046] In implementations where spatial frequency optical elements 341 and 342 are configured at different spatial frequencies, the intensity signals measured during each of the time periods 401, 402, 403, 404, or 409 are measured while the switchable waveplate 360 is driven to the same optical retardation value, in FIG. 4A.

[0047] FIG. 4B illustrates an example timing diagram 450 for measuring intensity signals and multiplexing optical values, in accordance with aspects of the disclosure. Time period tn 411 may be a searching period where processing logic 311 drives different optical retardation values 362 onto switchable waveplate 360 to determine the maximizing of intensity signals 336 and 337 for spatial frequency optical elements 341 and 342 configured for different spatial frequencies. The optical retardation value 491 that maximizes intensity signal 336 may then be driven onto switchable waveplate 360 for time period ti2412 and the optical retardation value 492 that maximizes intensity’ signal 337 may then be driven onto switchable waveplate 360 for time period ti3413 subsequent to time period ti2412. Time period tn 411 may be for 5 ms orAttorney Docket No.: EIDOP102PCTless while time period ti2412 may be for 20 ms or less and time period tis 413 may be for 20 ms or less. In this way, the optical retardation values 362 that maximize different spatial frequencies (written into spatial frequency optical elements 341 and 342) can be interlaced (time-multiplexed) to enhance the contrast of different spatial frequencies. Due to the persistence of the human eye, this time-multiplexing technique will go unnoticed by the user when the timemultiplexing is implemented at a time frequency that is sufficiently high.

[0048] Timing diagram 450 shows that time period ti4414 may be another “searching period” to remeasure the optical retardation value to maximize intensity signals 336 and 337. Time period ti4414 may be followed by time periods tis 415 and tie 416. The optical retardation value 494 that maximized intensity signal 336 during searching period ti4414 may then be driven onto switchable waveplate 360 for time period tis 415 and the optical retardation value 495 that maximized intensity signal 337 during searching period ti4414 may then be driven onto switchable waveplate 360 for time period tis 415 subsequent to time period ti4414.

[0049] FIG. 5 illustrates an example optical system 500 that may be implemented in optical devices 100 or 200, in accordance with aspects of the disclosure. System 500 includes a switchable waveplate 360 and a polarizer layer 350. System 300 also includes sensor module 530. Sensor module 530 may be one example of sensor modules 530, in FIG. 2. Sensor module 530 includes a sensor array 540. Sensor module 530 may optionally include a proximity sensor 580. Sensor array 540 may be implemented as a complementary metal-oxide semiconductor (CMOS) image sensor. Notably, sensor array 540 receives scene light 595 through switchable waveplate 360 and polarizer layer 350, in the specific implementation of FIG. 5.

[0050] Polarizer layer 350 is disposed between sensor array 540 and polarizer layer 350, in FIG. 5. Polarizer layer 350 may include a polarizer that reflects or absorbs a particular polarization orientation of scene light. For example, the polarizer may absorb or reflect a vertically polarization orientation or a horizontally polarization orientation.Attorney Docket No.: EIDOP102PCT

[0051] Polarizer layer 350 and switchable waveplate 360 in FIG. 5 may be included in a lens of an optical element (e.g. optical element 215). Polarizer layer 350 and switchable waveplate 360 may extend to within a frame (e.g. frame 210) so that switchable waveplate 360 and polarizer layer 350 modulates scene light 591 propagating to eye 503 of a user in addition to modulating scene light 591 that eventually propagates to sensor array 540 as light 595. The percentage of light 593 that polarizer layer 350 reflects or absorbs will depend on the optical retardation value 561 driven onto switchable waveplate 360 to change the polarization orientation of scene light 591.

[0052] Processing logic 510 is configured to drive an optical retardation value 561 onto switchable waveplate 360 in response to receiving an image 545 generated by sensor array 540 in response to light 595 that is the scene light 591 received through switchable waveplate 360 and polarizer layer 350.

[0053] Processing logic 510 is configured to receive image 545 from sensor array 540. Processing logic 510 is configured to perform image-processing techniques on image 545 to determine the spatial frequencies found in image 545. Determining the spatial frequencies found in image 545 may include decomposing an image into its constituent spatial frequencies.Decomposing the image into the included spatial frequencies may include performing a Fourier transform or a Fast Fourier Transform (FFT) on the image.

[0054] Processing logic 510 may be configured to filter for certain spatial frequencies in the image that correspond with a size of a feature in the scene. Returning to the example of moguls 190, the size of the moguls may be between 6 inches and 36 inches. In this context, processing logic 510 would filter image 545 for spatial frequencies corresponding to between 6 inches and 36 inches. Optical system 500 may need to determine the depth of the features in image 545 to make a more accurate measurement of the size of the features in image 545 and thus select the suitable spatial frequency filter.Attorney Docket No.: EIDOP102PCT

[0055] FIG. 5 shows an optional proximity sensor 580 in sensor module 530.Proximity sensor 580 may be communicatively coupled to processing logic 510. Processing logic 510 may drive proximity sensor 580 to capture proximity data at the same (or similar) time as image 545 is captured by sensor array 540. Proximity7sensor 580 may transmit one or more transmit signal(s) 581 into the external environment (e.g. scene 101) and receive a return signal 582 that is a portion of the transmit signal 581 being reflected or scattered by the features in the external environment. Proximity7sensor 580 may utilize infrared, near-infrared, or radiofrequency (RF) signals as transmit signal 581. Based on return signal 582, proximity sensor 580 generates mapping data 585 and provides the mapping data 585 to processing logic 510.Processing logic 510 can then use mapping data 585 to determine the distance of features in image 545 so that processing logic 510 can correspond spatial frequencies of features in image 545 with that actual size of those features.

[0056] Once one or more of those selected spatial frequencies are determined, processing logic 510 may iterate through driving a plurality7of optical retardation values 561 onto switchable waveplate 360 while capturing images 545 for each of the different optical retardation values 561 in a “searching period.” Whichever of the images 545 that provides the best contrast of the size of the desired features in the scene indicates which is the optimized optical retardation value 561 to enhance the contrast of those features for the eye 503 of the user to view light 599. Hence, for a “viewing period,” processing logic 510 may drive switchable waveplate 360 to the optical retardation value 561 that generated the image 545 with the best contrast of the features in the scene that have a size (e.g. the size of moguls 190) that the user is most interested in.

[0057] The “searching period” may be 5 ms or less while the “viewing period” may be for 20 ms or more, in some implementations. The viewing period may be greater than four times the searching period, in some implementations.

[0058] Optical system 500 may optionally include a user input interface 317 configured to deliver an input signal 519 to processing logic 510. User input interface 317 may be anAttorney Docket No.: EIDOP102PCTelectrical switch, capacitive touchpad, or otherwise. User input interface 317 may be disposed on the optical device (e.g. optical device 200). User input interface 317 may be disposed off the optical device. User input interface 317 may be an application presented on a touchscreen of a mobile device and input signal 519 may be wirelessly delivered to processing logic 510. Input signal 519 may select for the spatial frequency range that the user desires to enhance the contrast for. For example, if the user selects a spatial frequency range of 24-48 inches, processing logic 510 may set its spatial frequency fdters utilized during image processing of image 545 to analyze 24-48 inches.

[0059] FIG. 6 illustrates a process 600 of contrast enhancement based on spatial frequency, in accordance with aspects of the disclosure. The order in which some or all of the process blocks appear in process 600 should not be deemed limiting. Rather, one of ordinary skill in the art having the benefit of the present disclosure will understand that some of the process blocks may be executed in a variety of orders not illustrated, or even in parallel. All or a portion of the process blocks in process 600 may be performed by processing logic 310 or 311, for example.

[0060] In process block 605, scene light is received with a photosensor. The scene light propagates through a switchable waveplate and a spatial frequency optical element.

[0061] In process block 610, an intensity signal is generated with the photosensor in response to receiving the scene light.

[0062] In process block 615, the switchable waveplate is driven in response to the intensity signal. In some implementations, the switchable waveplate is driven to increase the intensity signal.

[0063] Process 600 may further include receiving the scene light with a second photosensor where the scene light propagates through the switchable waveplate and a second spatial frequency grating. Process 600 may further include generating a second intensity signalAttorney Docket No.: EIDOP102PCTwith the second photosensor in response to receiving the scene light. The switchable waveplate may be driven in response to the intensity signal and the second intensity signal.

[0064] In an implementation of process 600, the spatial frequency optical element is configured to boost transmission of the scene light from features in a scene within a first spatial frequency range and the second spatial frequency optical filter is configured to boost transmission of the scene light from features in a scene within a second spatial frequency range separated from the first spatial frequency by a buffer spatial frequency. By way of example, the first spatial frequency may be 12 inches to 24 inches and the second spatial frequency may be three inches to six inches and the buffer spatial frequency would be six inches to 12 inches.

[0065] In an implementation of process 600, the switchable waveplate is driven to increase the intensity signal during a first time period and driven to increase the second intensity signal during a second time period interlaced with the first time period at a frequency above 30 Hz. The first intensity signal is measured during the first time period and the second intensity signal is measured during the second time period.

[0066] In an implementation of process 600, the second spatial frequency optical filter is configured to transmit the scene light at the same spatial frequency as the spatial frequency optical filter and the switchable waveplate is driven in response to the higher of the first intensity signal and the second intensity signal.

[0067] In an implementation of process 600, the spatial frequency optical filter is configured to boost transmission of light from features in a scene with a spatial frequency of between 6 inches and 36 inches.

[0068] The term "processing logic’’ (e.g. processing logic 310, 311, and 510) in this disclosure may include one or more processors, microprocessors, multi-core processors.Application-specific integrated circuits (ASIC), and / or Field Programmable Gate Arrays (FPGAs) to execute operations disclosed herein. In some embodiments, memories (not illustrated) are integrated into the processing logic to store instructions to execute operationsAttorney Docket No.: EIDOP102PCTand / or store data. Processing logic may also include analog or digital circuitry to perform the operations in accordance with embodiments of the disclosure.

[0069] A “memory” or “memories” described in this disclosure may include one or more volatile or non-volatile memory architectures. The “memory” or “memories” may be removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules, or other data. Example memory7technologies may include RAM, ROM, EEPROM, flash memory7, CD-ROM, digital versatile disks (DVD), high-definition multimedia / data storage disks, or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information for access by a computing device.

[0070] Networks may include any network or network system such as, but not limited to, the following: a peer-to-peer network; a Local Area Network (LAN); a Wide Area Network (WAN); a public network, such as the Internet; a private network; a cellular network; a wireless network; a wired network; a wireless and wired combination network; and a satellite network.

[0071] Communication channels may include or be routed through one or more wired or wireless communication utilizing IEEE 802.11 protocols, short-range wireless protocols, SPI (Serial Peripheral Interface), I2C (Inter-Integrated Circuit), USB (Universal Serial Port), CAN (Controller Area Network), cellular data protocols (e g. 3G, 4G, LTE, 5G), optical communication networks, Internet Service Providers (ISPs), a peer-to-peer network, a Local Area Network (LAN), a Wide Area Network (WAN), a public network (e.g. “the Internet”), a private network, a satellite network, or otherwise.

[0072] A computing device may include a desktop computer, a laptop computer, a tablet, a phablet, a smartphone, a feature phone, a server computer, or otherwise. A server computer may be located remotely in a data center or be stored locally.Attorney Docket No.: EIDOP102PCT

[0073] The processes explained above are described in terms of computer software and hardware. The techniques described may constitute machine-executable instructions embodied within a tangible or non-transitory machine (e.g., computer) readable storage medium, that when executed by a machine will cause the machine to perform the operations described. Additionally, the processes may be embodied within hardware, such as an application specific integrated circuit (“ASIC’) or otherwise.

[0074] A tangible non-transitory machine-readable storage medium includes any mechanism that provides (i.e., stores) information in a form accessible by a machine (e.g., a computer, network device, personal digital assistant, manufacturing tool, any device with a set of one or more processors, etc.). For example, a machine-readable storage medium includes recordable / non-recordable media (e.g., read only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, etc.).

[0075] The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.

[0076] These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.

Claims

Attorney Docket No.: EIDOP102PCTCLAIMSWhat is claimed is:

1. Goggles comprising:a switchable liquid crystal layer including liquid crystals;a polarizer layer;a spatial frequency optical element, wherein the polarizer layer is disposed between the spatial frequency optical element and the switchable liquid crystal layer;a photodiode configured to receive scene light through the switchable liquid cry stal layer, the polarizer layer, and the spatial frequency optical element; andprocessing logic configured to drive an orientation of the liquid cry stals in response to receiving an intensity signal generated by the photodiode in response to the scene light received through the switchable liquid crystal layer, through the polarizer layer, and through the spatial frequency optical element.

2. The Goggles of claim 1, wherein the spatial frequency optical element is configured to maximize transmission of light from features in a scene with a spatial frequency of between 6 inches and 36 inches.

3. An optical device for wearing on a head of a user, the optical device comprising:a switchable waveplate;a spatial frequency optical element;a photosensor configured to receive scene light through the switchable waveplate and the spatial frequency optical element, wherein the spatial frequency optical element is disposed between the photosensor and the switchable waveplate; andprocessing logic configured to drive an optical retardation value of the switchable waveplate in response to receiving an intensity signal generated by the photosensor in response to the scene light.Attorney Docket No.: EIDOP102PCT4. The optical device of claim 3, wherein the spatial frequency optical element selectively passes the scene light based on spatial frequencies.

5. The optical device of claim 3, wherein the processing logic is configured to drive the switchable waveplate to maximize or approach maximization of the intensity signal generated by the photosensor.

6. The optical device of claim 3 further comprising:a second spatial frequency optical element; anda second photosensor configured to receive the scene light through switchable waveplate and the second spatial frequency optical element, wherein the second spatial frequency optical element is disposed between the second photosensor and the switchable waveplate, wherein the processing logic is also configured to drive the switchable waveplate in response to receiving a second intensity signal generated by the second photosensor in response to the scene light.

7. The optical device of claim 6, wherein the second spatial frequency optical filter is configured to pass a second spatial frequency range that is different than a first spatial frequency range passed by the spatial frequency optical element.

8. The optical device of claim 7, wherein the processing logic is further configured to:drive the switchable waveplate to a first optical retardation value during first time periods, wherein the first optical retardation value is in response to the intensity signal generated by the photosensor; anddrive the switchable waveplate to a second optical retardation value during second time periods, wherein the second optical retardation value is in response to the second intensity signal generated by the second photosensor,Attorney Docket No.: EIDOP102PCTand wherein the first time periods are interlaced with the second time periods at a frame rate above 30 Hz,and further wherein the processing logic is configured to measure the intensity signal during the first time periods and measure the second intensity signal during the second time periods.

9. The optical device of claim 3, wherein the processing logic is further configured to drive multiple optical retardation value onto the switchable waveplate to search for a maximizing optical retardation value that maximizes or approaches maximizing the intensity signal generated by the photosensor.

10. The optical device of claim 3. wherein the switchable waveplate includes a liquid crystal layer.

11. The optical device of claim 3, wherein the photosensor includes a photodiode.

12. The optical device of claim 3, wherein the spatial frequency optical element is configured to maximize transmission of light from features in a scene with a spatial frequency of between 6 inches and 36 inches.

13. The optical device of claim 3 further comprising:a polarizer layer disposed between the switchable waveplate and the spatial frequency optical element.

14. A method comprising:receiving scene light with a photosensor, wherein the scene light propagates through a switchable waveplate and a spatial frequency optical element;Attorney Docket No.: EIDOP102PCTgenerating an intensity signal with the photosensor in response to receiving the scene light; anddriving the switchable waveplate in response to the intensity signal.

15. The method of claim 14, wherein the switchable waveplate is driven to increase the intensity’ signal.

16. The method of claim 14 further comprising:receiving the scene light with a second photosensor, wherein the scene light propagates through the switchable waveplate and a second spatial frequency optical element; and generating a second intensity signal with the second photosensor in response to receiving the scene light, wherein the switchable waveplate is driven in response to the intensity signal and the second intensity signal.

17. The method of claim 16, wherein the spatial frequency optical element is configured to boost transmission of the scene light from features in a scene within a first spatial frequency range, and wherein the second spatial frequency optical filter is configured to boost transmission of the scene light from features in a scene within a second spatial frequency range separated from the first spatial frequency by a buffer spatial frequency.

18. The method of claim 17, wherein the switchable waveplate is driven to increase the intensity signal during a first time period and driven to increase the second intensity signal during a second time period interlaced with the first time period at a frequency above 30 Hz,wherein the intensity signal is measured during the first time period and the second intensity signal is measured during the second time period.Attorney Docket No.: EIDOP102PCT19. The method of claim 16, wherein the second spatial frequency optical fdter is configured to transmit the scene light at the same spatial frequency as the spatial frequency optical filter, and wherein the switchable waveplate is driven in response to the higher of the intensity signal and the second intensity signal.

20. The method of claim 14, wherein the spatial frequency optical filter is configured to boost transmission of light from features in a scene with a spatial frequency of between 6 inches and 36 inches.

Images