High-Speed Electrically Active Lens Switching System and Method

Abstract

Conventional liquid crystal lenses switch on and off very slowly, allowing humans to perceive a gradual transition of the lens from high to low refractive power. This makes them unsuitable for quickly focusing virtual images in augmented reality, mixed reality, or virtual reality systems. Conversely, the inventive fast-switching electro-active lens system can switch so quickly (e.g., 35 milliseconds or less) that humans perceive its refractive power to change instantaneously. The system achieves this fast switching using electro-active waveplates in series with slower liquid crystal lenses. The wavelength position can be quickly switched between vertically or horizontally polarized radiation. Each lens focuses vertically or horizontally polarized light and transmits the orthogonal polarization. By switching the polarization state, the waveplate effectively turns one lens on and the other lens off much faster than either lens could switch by itself.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Patent Application No. 62 / 954,743, filed Dec. 30, 2019, under 35 U.S.C. § 119(e), and is hereby incorporated by reference in its entirety.

Background Art

[0002] An electro - active lens can be used to adjust the focus of a person's eye onto a digital image presented on an augmented reality or virtual reality display at a fixed virtual position from the eye, but at various simulated distances. A typical electro - active lens is small in mass and volume and consumes little energy, but its refractive power does not switch quickly. A typical electro - active lens with a width of 30 - 40 millimeters takes hundreds of milliseconds to switch from one refractive power to another. This delay is distinguishable by the user and degrades the quality of the visual experience.

Summary of the Invention

[0003] The inventive electro-active lens system can (apparently) switch from one refractive power to another in tens of milliseconds, or faster, rather than in hundreds of milliseconds. It does this using a pair of electro-active lens elements (also called electro-active lenses) configured to operate on light in orthogonal polarization states (e.g., horizontal and vertical polarization states), and a dynamic polarization switch that can switch the light between those orthogonal polarization states in tens of milliseconds. For example, the first electro-active lens element may be configured to focus horizontally polarized light but not vertically polarized light, and the second electro-active lens element may be configured to focus vertically polarized light but not horizontally polarized light. Even if the electro-active lens elements turn on / off slowly, e.g., in units of hundreds of milliseconds, the polarization adjuster can switch the light between the horizontal and vertical polarization states in tens of milliseconds. If the first and second electro-active lens elements have different refractive powers, the polarization adjuster can effectively change the refractive power of the lens within tens of milliseconds by quickly switching the light between the horizontal and vertical polarization states.

[0004] The refractive power should be switchable in less than tens of milliseconds, but the time between switching events is rarely that short. In practice, the time between switching events can be several seconds or more. By taking advantage of the difference between the time it takes to switch an electroactive lens and the time between switching events, the switching speed in an apparatus having a high-speed polarization adjuster (also called a polarization orientation changer or variable phase retarder) and one or more low-speed focus-changing devices (electroactive or liquid crystal lens elements) can be increased. By combining a high-speed polarization-changing component with one or more slower focus-changing components (e.g., first and second electroactive lens elements), the polarization-changing component enables only one of the refractive powers of the focus-changing components to be "optically present" in the optical system at a time. One focus-changing device is optically present while the other focus-changing components are not optically present, and vice versa. Since the polarization-changing component can quickly switch the incident light from one polarization orientation to the other, the system can quickly switch from one focus-changing component to the other without moving parts. In a high-speed variable electroactive lens system having only a single focus-changing element, the system can quickly switch from the "lens on" state to the "lens off" state. There is no limit to the number of focus-changing elements that can be used in a single electroactive lens system.

[0005] The inventive electro-active lens system may include a polarization changer, a first electro-active lens optically communicating with the polarization changer, and a polarization switcher and a second electro-active lens optically communicating with the first electro-active lens. The polarization changer is switchable between a first state in which the polarization changer switches the polarization of light between a first polarization state and a second polarization state (e.g., orthogonal linear polarization states) and a second state in which the polarization changer transmits light in the first polarization state. The first electro-active lens is switchable between a first focusing state in which the first electro-active lens focuses light in the first polarization state and transmits light in the second polarization state and a first transmission state in which the first electro-active lens transmits light in the first and second polarization states. Also, the second electro-active lens is switchable between a second focusing state in which the second electro-active lens focuses light in the first polarization state and transmits light in the second polarization state and a second transmission state in which the second electro-active lens transmits light in the first and second polarization states.

[0006] The polarization switcher may include a liquid crystal wave plate and may have a phase difference of π / 2 in the first state and a phase difference of 0 in the second state. The polarization switcher may be configured to switch between the first state and the second state faster than (i) the first electro-active lens is configured to switch between the first focusing state and the first non-focusing state and (ii) the second electro-active lens is configured to switch between the second focusing state and the second non-focusing state. For example, the polarization switcher may be configured to switch between the first state and the second state within 100 milliseconds, 50 milliseconds, 35 milliseconds, 30 milliseconds, 25 milliseconds, 20 milliseconds, 15 milliseconds, 10 milliseconds, 5 milliseconds, or faster. Similarly, the first and second electro-active lenses may each be configured to switch between their respective focusing and non-focusing states in more than 100 milliseconds.

[0007] The polarizer switch and the electroactive lens may be integrated together, for example, without an air gap between components. For example, the polarizer switch and the first electroactive lens can share a first common substrate. Similarly, the first and second electroactive lenses can share a second common substrate.

[0008] This electroactive lens system can be used or operated by setting the polarizer switch to a first or second state, setting the first electroactive lens to a first focused state or a first non-focused state, setting the second electroactive lens to a second focused state or a second non-focused state, and transmitting light through the polarizer switch, the first electroactive lens, and the second electroactive lens. When the polarizer switch is in the first state, the first electroactive lens is in the first focused state, and the second electroactive lens is in the second non-focused state, the second electroactive lens can be switched from the second non-focused state to the second focused state, during which the system transmits light in a first polarization state through the polarizer switch, focuses the light with the first electroactive lens, and transmits the light through the second electroactive lens without focusing the light with the second electroactive lens. After the second electroactive lens is switched from the second non-focused state to the second focused state, the polarizer switch can be switched from the first state to the second state, thereby focusing the light on the second electroactive lens and transmitting the light without focusing the light on the first electroactive lens. The switching of the second electroactive lens from the second non-focused state to the second focused state and the switching of the polarizer switch from the first state to the second state can occur in response to a desired change in the position of the virtual image. The switching of the second electroactive lens from the second non-focused state to the second focused state takes at least 100 milliseconds, and the switching of the polarizer switch from the first state to the second state can take less than 100 milliseconds.

[0009] Another electroactive lens system includes a liquid crystal wave plate in an optical system having first and second liquid crystal lenses. The liquid crystal wave plate is switchable between a retardation of 0 wavelength and a retardation of half wavelength within 35 milliseconds. The first liquid crystal lens is switchable between a first state that focuses light in a first linearly polarized state onto a first focal plane and a second state that focuses light in a first linearly polarized state onto a second focal plane. The second liquid crystal lens is switchable between a first state that focuses light in a second linearly polarized state orthogonal to the first linearly polarized state onto a third focal plane and a second state that focuses light in a second linearly polarized state onto a fourth focal plane.

[0010] The liquid crystal wave plate and the first liquid crystal lens can share a first common substrate, and the first liquid crystal lens and the second liquid crystal lens can share a second common substrate. The first and second liquid crystal lenses can each transmit light in the second and first linearly polarized states, respectively. The first liquid crystal lens can take longer than 35 milliseconds (e.g., 100 milliseconds or more) to switch between the first state and the second state. between to switch.

[0011] This electroactive lens system may also include a display optically in communication with the liquid crystal wave plate and configured to emit light in a first linearly polarized state. And a processor operatively coupled to the liquid crystal wave plate, the first liquid crystal lens, the second liquid crystal lens, and the display and configured to control the retardation of the liquid crystal wave plate, the first liquid crystal lens, the second liquid crystal lens, and the display may be included.

[0012] All combinations of the foregoing concepts, as well as additional concepts discussed in more detail below (assuming such concepts are not mutually inconsistent), are considered to be part of the subject matter of the invention disclosed herein. In particular, all combinations of the subject matter recited in the claims, which appear at the end of this disclosure, are considered to be part of the inventive subject matter disclosed herein. Terms used in any disclosure incorporated herein by reference and explicitly used herein should be given meanings that most closely match the specific concepts disclosed herein.

Brief Description of the Drawings

[0013] Those skilled in the art will understand that the drawings are presented primarily for illustrative purposes and are not intended to limit the scope of the subject matter of the invention described herein. The drawings are not necessarily to scale, and in some instances, various aspects of the subject matter of the invention disclosed herein may be shown exaggerated or enlarged in the drawings to facilitate understanding of different features. In the drawings, like reference characters generally mean like features (e.g., functionally similar and / or structurally similar elements).

[0014]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

[0015] The fast-switching electroactive lens system can change the focus of linearly polarized light from an object, e.g., a display in an augmented reality headset, in a period of less than 35 milliseconds (e.g., 30, 25, 20, 15, 10, 5, or fewer milliseconds). It does this with a combination of a fast-switching waveplate and slower-switching liquid crystal lenses. Each lens has two principal axes that are orthogonal to each other and orthogonal to the optical axis of the lens. Each lens focuses light polarized along one principal axis (the focusing principal axis) and transmits light polarized along the other principal axis (the transmission principal axis). The amount of focus, i.e., the refractive power, along the focusing principal axis of the lens depends, among other things, on the thickness of the liquid crystal and the applied voltage, and may be adjusted continuously (e.g., from -5 to +5 diopters), or switched between two or more discrete states (e.g., in increments of 0.5 or 1.0 diopter between 0 and 5 diopters). Each lens can provide no refractive power (zero) when off (when no voltage is applied), or can provide a non-zero refractive power when off. Other ranges and values of refractive power are possible.

[0016] The lenses are aligned such that their optical axes coincide, but their principal axes are rotated 90° with respect to each other. The focusing principal axis of the first lens is parallel to the transmission principal axis of the second lens, and the transmission principal axis of the first lens is parallel to the focusing principal axis of the second lens. The optical axes of the lenses coincide with the optical axis of the waveplate, and the principal axes of the waveplate are aligned with the principal axes of the lenses. In other words, when viewed along the surface normal (the optical axis of the fast-switching electroactive lens system), the waveplate and the lenses have coincident surface normals and aligned principal axes.

[0017] Since the lenses are aligned with the converging and transmission principal axes rotated 90°, when the system is illuminated by light linearly polarized along one of the system's principal axes, one lens focuses the light and the other lens transmits the light. When the polarization state of the incident light is converted to an orthogonal linearly polarized state (e.g., horizontal to vertical, or +45° to -45°), the operation of the lenses switches. The waveplate changes state much faster than the lenses, enabling a much faster, user-observable transition from one refractive power to the other than if a single lens provided all the optical adjustment. Also, if the transitions do not occur frequently (e.g., at intervals longer than the lens switching time), one lens can be switched between refractive power levels while the other lens focuses the light so that it is ready for the next transition.

[0018] Polarization state and liquid crystal alignment direction Figures 1A, 1B, and 1C show symbols used in the present disclosure to describe different linear polarization orientations or states. Symbol 5 in Figure 1A indicates that the direction of the linear polarization appears as if it is "entering and exiting the plane of the figure". Symbol 10 in Figure 1B indicates that the direction of the linear polarization is orthogonal to the direction indicated by symbol 5. In this case, the direction of the linear polarization is "left - right across the plane of the figure". Symbol 15 in Figure 1C indicates that the direction of the linear polarization is also orthogonal to the direction indicated by symbol 5. The direction of the linear polarization indicated by symbol 15 is "up - down across the plane of the figure".

[0019] Figures 2A, 2B, and 2C show symbols used in the present disclosure to describe the rubbing direction or alignment direction of the alignment layer used in a liquid crystal focus changer (electrically active lens). Symbol 20 in Figure 2A indicates the rubbing direction faces as if it is "entering and exiting within the plane of the figure". Symbol 25 in Figure 2B indicates that the rubbing direction faces is orthogonal to the direction indicated by symbol 20, and in this case, the rubbing direction facesis "left and right across the plane of the figure". The symbol 30 in FIG. 2C indicates that the rubbing direction is orthogonal to the direction indicated by the symbols 20 and 25, and the rubbing direction is "up and down across the plane of the figure". Each liquid crystal lens typically has two alignment layers, i.e., one on each side of the liquid crystal material, and their rubbing directions may be parallel, antiparallel, or orthogonal to each other. In some cases, only one alignment layer may be used for cost reduction. Using two alignment layers increases both the switching speed and the field of view width.

[0020] The symbols shown in FIGS. 1A - 1C and FIGS. 2A - 2C indicate relative directions. When different drawings are from different viewpoints, different symbols can be used to indicate the same polarization state in different drawings. Similarly, when different drawings are from different viewpoints, the same symbol can be used to indicate different polarization states in different drawings. For example, in a side view or a projection view of an optical component, the symbol 5 may indicate a horizontally polarized state, and the symbol 10 may indicate a vertically polarized state. In an end - on view (i.e., a view along the optical axis) of the same optical component, the symbol 10 may indicate a horizontally polarized state, and the symbol 15 may indicate a vertically polarized state.

[0021] High - speed electro - active lens switching system Figure 3A shows an exploded view of a high-speed switching lens system 300 that includes a polarization orientation changer (also called a polarization rotator, a polarization adjuster, or a variable phase element) 40 that optically communicates with a first electro-active lens 50 and a second electro-active lens 60. The polarization orientation changer 40, the first electro-active lens 50, and the second electro-active lens 60 are optically in series with each other or stacked on top of each other. The lens system 300 can utilize a planar liquid crystal, such as Merck MLC-2140, in all three components 40, 50, and 60. The first electro-active lens 50 has its alignment layer aligned orthogonally to the alignment layer of the second electro-active lens 60. In this case, the first electro-active lens 50 has a horizontally aligned liquid crystal rubbing direction 25, and the second electro-active lens 60 has a vertically aligned liquid crystal rubbing direction 30. Other rubbing directions (e.g., a rubbing direction of ±45°) are also possible and are typically used when less than 100% focusing is required (in other words, only a portion of the light is focused while the other portion passes unfocused).

[0022] The apparatus 300 shown in FIG. 3A is a preferred embodiment, but additional polarization switches may be added to add functional control options. For example, the apparatus 300 of FIG. 3A can quickly switch the refractive powers of the lenses 50 and 60. If an additional polarization switch is positioned between the lenses 50 and 60, activating both polarization switches can change the polarization state of the light propagating through the system such that both lenses 50, 60 focus the light. More specifically, the first polarization switch 40 can switch the light from a second polarization state 10 to a first polarization state 15, and a second polarization switch (not shown) can switch the light from the first polarization state 15 to the second polarization state 10. Alternatively, both polarization switches can be activated such that neither lens 50, 60 focuses the light, even though one or both lenses are operating to provide refractive power or are being switched between states. This can be useful for providing a greater refractive power than that provided by a single lens.

[0023] During operation, linearly polarized light 35 from an object (e.g., a display or a spatial light modulator in an augmented or virtual reality system) enters the polarization rotator 40 in a second polarization state (e.g., vertically polarized as indicated by symbol 10). When the polarization rotator 40 is in the first state (e.g., off), as shown in FIG. 3A, it emits light 45 in the first polarization state, which can be rotated 90° with respect to the second polarization state (e.g., horizontally polarized as indicated by symbol 15). When the polarization rotator 40 is in the second state (e.g., on), it emits light 45 in the same polarization state as the input light 35 (horizontally polarized in this embodiment).

[0024] The light 45 exiting the polarization adjuster 40 enters the first electro-active lens 50, which focuses the light 45 onto the first focal plane when the light 45 is in the first polarization state (e.g., vertically polarized) and the first electro-active lens 50 is in the first state (e.g., on). When the light 45 is in the first polarization state and the first electro-active lens 50 is in the second state (e.g., off), the first electro-active lens 50 focuses the light onto the second focal plane. Also, when the light 45 is in the second polarization state (e.g., horizontally polarized), it passes through the first electro-active lens 50 without being focused by the first electro-active lens 50.

[0025] The light 55 exiting the first electro-active lens 50 enters the second electro-active lens 60, which, like the first electro-active lens 50, is switchable between two states (e.g., on state and off state). However, unlike the first electro-active lens 50, the second electro-active lens 60 acts only on light in the second polarization state (e.g., horizontally polarized). When the second electro-active lens 60 is in the first state, it focuses the light in the second polarization state onto the third focal plane. Also, when the second electro-active lens 60 is in the second state, it focuses the light in the second polarization state onto the fourth focal plane. The light 55 in the first polarization state (e.g., vertically polarized) passes through the second electro-active lens 60 without being focused by the second electro-active lens 60. The light 65 exits the second electro-active lens 60 and the system 300.

[0026] When the first electro-active lens 50 and the second electro-active lens 60 provide different refractive power levels, the lens system 300 can switch between a series of different refractive power level focal lengths by operating the polarization switch 40, the first electro-active lens 50, and the second electro-active lens 60. For example, if the first electro-active lens 50 can switch between refractive power levels of 0.0 diopters and 1.0 diopters (the first / on state and the second / off state respectively), and the second electro-active lens 50 can switch between refractive power levels of 0.5 diopters and 1.5 diopters (the first / on state and the second / off state respectively), the lens system 300 can switch between refractive power levels of 0.0, 0.5, 1.0, and 1.5 diopters by operating the polarization switch 40, the first electro-active lens 50, and the second electro-active lens 60. These refractive power levels are merely examples, and other optical power levels are possible, including refractive power levels that are not evenly spaced, such as refractive powers selected to focus an object in the planes of near, near-middle, middle, far-middle, and / or far distances.

[0027] The high switching speed of the polarization adjuster 40 enables the lens system 300 to quickly (e.g., within 30 milliseconds) switch between these refractive power levels even when the first and second electro-active lenses 50 and 60 can switch slowly (e.g., in 100 milliseconds or more). For example, while the first electro-active lens 50 is on and the polarization adjuster 40 is off, the second electro-active lens 60 can transition from one refractive power to the other without affecting the light propagating through the lens system 300. When the second lens 60 has completed its transition and is ready and at the desired refractive power, the polarization adjuster 40 switches states to focus light on the second electro-active lens 60, and even if the first electro-active lens 50 is still on, the first electro-active lens 50 no longer focuses the light.

[0028] FIG. 3A shows the components in an exploded perspective view having a gap between the components. The lens system functions even with a gap as shown in FIG. 3A, but the lens system can also be fabricated with the components adjacent to each other, joined or integrated, to eliminate reflections at the interfaces. For example, the first electroactive lens 50 can share the first substrate with the polarization orientation changer 40 and the second substrate with the second electroactive lens 60.

[0029] FIG. 3B shows an integrated high-speed switching electroactive lens system 350. In this system 350, substrates 41 and 43 form a polarization adjuster 40 together with a liquid crystal layer 42. Substrates 43 and 46 form a first lens 50 together with a liquid crystal layer 44. And substrates 46 and 48 form a second lens 60 together with a liquid crystal layer 47. Substrates 43 and 46 are shared by a plurality of components and are therefore coated on each side with separate alignment layers and independently actuated electrodes (not shown).

[0030] High-speed polarization adjuster (variable phase retarder) FIGS. 4A and 4B show side views of a cross-section of the polarization adjuster 40. FIG. 4A shows the adjuster 40 in the non-powered or off (first) state, while FIG. 4B shows the adjuster 40 in the powered or on (second) state.

[0031] The polarization adjuster 40 is composed of a first substrate 72 and a second substrate 80, and a planar liquid crystal (for example, Merck MLC-2140 nematic liquid crystal) is sandwiched and sealed between the two substrates 72 and 80. On the surface of the lower substrate 72, there is a transparent conductive coating 75, also called an electrode (for example, indium tin oxide (ITO)). On this electrode 75, there is a transparent alignment layer (for example, a polyimide made from Nissan Sunever 410 polyimide varnish). Typically, the alignment layer is applied, cured, and then rubbed with a felt cloth along the desired alignment direction. (Figs. 2A - 2C show possible rubbing directions for the alignment layer.) Adjacent to the electrode 75 is the liquid crystal. On the surface of the upper substrate 80, there is another conductive coating (electrode) 85, which can be made of the same material as the first electrode 75 is made of.

[0032] Figure 4A shows the difference between the electrodes 75 and 85. When the polarization adjuster 40 is off, the alignment layer on the first electrode 75 is configured to align the adjacent liquid crystal molecules in the direction indicated by symbol 25, while the alignment layer on the second electrode 85 is configured to align the adjacent liquid crystal molecules in the direction indicated by symbol 20. As a result of this configuration, the liquid crystal molecules are aligned in the alignment / direction 25 at the first electrode 75, in the alignment / direction 20 at the second electrode 85, and in an intermediate alignment / direction between the alignment 25 and the alignment 20 in the middle of the liquid crystal layer, and as the liquid crystal approaches the first electrode 75 and the second electrode 85 respectively, it gradually twists as it approaches the alignments 25 and 20. This twisted configuration is shown by the three symbols 100 in Fig. 4A. This twist of the liquid crystal molecules adjusts or changes the polarization direction of the light 105 from the polarization alignment 10 when entering the polarization adjuster 40 to the polarization alignment 5 when exiting the polarization adjuster 40.

[0033] FIG. 4B shows a polarization modulator 40 in which the voltage supply unit 110 applies an electric field potential to the first electrode 75 while an opposite electric field potential is applied to the second electrode 85. The applied voltage may be an alternating current (AC) signal such as a sine wave or a square wave. When power is applied, the liquid crystal molecules reorient from direction 100 to direction 115 as shown in FIG. 4B. In this state, the polarization orientation 10 of the light 105 entering the polarization modulator is the same as the polarization orientation 10 of the light 105 when it exits the polarization modulator. In other words, when a voltage is applied to the electrodes 75 and 85, the phase difference of the polarization modulator changes from π / 2 to 0. The polarization modulator 40 does not change the direction of light propagation.

[0034] Other configurations of the polarization modulator are also possible. For example, the rubbing direction of the alignment layer may have parallel or anti-parallel rubbing directions instead of the intersecting or orthogonal rubbing directions of FIGS. 4A and 4B. In parallel or anti-parallel rubbing directions, the polarization modulator does not change the polarization state of the incident light when the incident light is off (i.e., when no voltage is applied to the liquid crystal by the electrodes), and its nominal phase difference is 0. Instead, the polarization modulator changes the polarization state of the incident light when it is on (i.e., when a voltage is applied across the liquid crystal by the electrodes), for example, by changing horizontal or vertical polarization by a phase difference change of π / 2.

[0035] The design parameters of the polarization modulator, including the liquid crystal material and the liquid crystal thickness, can be selected to increase the switching speed. The following equation shows an example of a design set for achieving high switching speed and high optical efficiency. Some exemplary turn-off times (indicating preferred liquid crystal thicknesses of either 2.4 micrometers or 5.3 micrometers) are shown, but the turn-on time can be reduced by using a switching voltage that is higher than necessary. The liquid crystal used in the preferred embodiment is HAE614752 manufactured by Jiangsu Hecheng Display Technology Co. of China. Other liquid crystals, such as MLC2136 manufactured by Merck Chemicals of Germany, can also be used.

[0036] For a twisted nematic liquid crystal cell placed between two polarizers aligned parallel and perpendicular to each surface director, the transmission is as follows:

Number

Number

Table 1

[0037] The phase difference of half wavelength (i.e., The polarizer that provides JPEG0007699835000017.jpg927) should have a liquid crystal layer whose thickness meets the criteria of the minimum transmission using the above equation. For a liquid crystal layer having a viscosity of 100 mPa and K = 10 pN, the thickness of the liquid crystal layer should be 2.4 μm or 5.3 μm for switching times of 6 milliseconds or 29 milliseconds, respectively. These switching times are short enough for the polarizer to change states (e.g., turn on or off) without perceptible delay by humans.

[0038] Operation of a high - speed switching electro - active lens system Figures 5 - 7 show the operation of a high - speed switching electro - active lens system 500 having a polarization adjuster 120, a first electro - active (liquid crystal) lens 125, and a second electro - active (liquid crystal) lens 130 that are optically in series with each other. The first electro - active lens 125 has an alignment layer rubbed in alignment 30, and the second electro - active lens 130 has an alignment layer rubbed in orthogonal alignment 20. Figures 5 - 7 show the gaps between components, but the components are in contact with each other, bonded together, or otherwise integrated to form a single unit like the system 350 of Figure 3B. The high - speed switching electro - active lens system 500 focuses and / or transmits the polarization of light emitted by a display 520 such as a transparent organic light - emitting diode (OLED) display in an augmented reality system. The high - speed switching electro - active lens system 500 and the display 520 are operably coupled to a processor 510, and the processor 510 can control the polarization adjuster 120, the first electro - active lens 125, and the second electro - active lens 130 in response to the content (video image) displayed on the display 520.

[0039] In FIG. 5, the polarization adjuster 120 is in the off state, as are the electro-active lenses 125 and 130. Light enters the polarization adjuster 120 at polarization orientation 5 and exits at orientation 15 (i.e., changes from one linearly polarized state to an orthogonal linearly polarized state). In this example, when the polarization adjuster 120 and lens 125 are in the electrically off state and the lens 130 is switched to the electrically on state, no optical focusing occurs because the rubbing direction orientation of lens 130 is orthogonal to the polarization state of the light entering lens 130. In other words, if the first electro-active lens 125 has no refractive power in the off state and the second electro-active lens 130 does not act on the light at polarization orientation 15, the system 500 does not focus the incident light.

[0040] FIG. 6 shows the polarization adjuster 120 still in the electrically off state and the first and second electro-active lenses 125 and 130 in the electrically on state. In this configuration, the first electro-active lens 125 has refractive power due to the voltage that actuates its liquid crystal material and changes its refractive index distribution. The polarization of the light entering the first electro-active lens 125 matches the orientation of the rubbing direction 30 of the first electro-active lens, so the first electro-active lens 125 focuses the incident light. However, the second electro-active lens 130 does not focus the light regardless of its setting because its rubbing direction 20 is orthogonal to the polarization orientation 15 of the light.

[0041] FIG. 7 shows a polarization modulator 120 in an electrically-on state (i.e., a voltage is applied to its liquid crystal layer), a first electroactive lens 125, and a second electroactive lens 130. In this state, the polarization modulator 120 does not convert the polarization state of the incident light. Instead, the polarization modulator 120 transmits the incident light with a polarization orientation 5. This means that the light emerging from the polarization modulator 120 is no longer polarized in the same orientation as the rubbing direction 30 of the first electroactive lens 125, but is now polarized in the same orientation as the rubbing direction 20 of the second electroactive lens 130. As a result, the second electroactive lens 130 focuses the incident light, while the first electroactive lens 125 does not. If the second electroactive lens 130 has a higher refractive power (shorter focal length) than the first electroactive lens 125, as shown in FIG. 7, this change in the polarization state changes the refractive power (focal length) of the lens system 500, even though the states of the first and second electroactive lenses 125 and 130 have not changed.

[0042] Display of Video in a High-Speed Switching Electroactive Lens System FIG. 8 shows a process for adjusting the focus of virtual images appearing in a video or other dynamic environment presented via an augmented reality, mixed reality, or virtual reality system using a high-speed switching electroactive lens system such as the systems of FIGS. 3 and 5-7. In the following example, the electroactive lens system includes a polarization-changing component (or polarization-changer) that can switch between state A (e.g., π / 2 phase difference) and state B (e.g., 0 phase difference) in 35 milliseconds, and two focus-changing components (electroactive lenses or focus-changers, lenses A and B) that can each switch states in approximately 350 milliseconds. The electroactive lens system is used in an augmented / virtual reality system that displays a video clip with a duration of 8 seconds. The display of the video clip includes changing the focus every 2 seconds, and the change in focus occurs in 35 milliseconds so as to be apparent to the observer.

[0043] This example of the video clip begins with a digital image at a long distance. At the 2 - second mark, as shown by the lower line in FIG. 8, the simulation distance of the digital image changes from long distance to medium - long distance. At the 4 - second mark, the simulation distance changes from medium - long distance to short distance. At the 6 - second mark, the simulation distance changes from short distance to medium distance. And at the 8 - second mark, the simulation distance changes from medium distance back to long distance.

[0044] For the purposes of this example, the simulation distances of long distance, medium - long distance, medium distance, and short distance are 6 meters, 2 meters, 1 meter, and 0.5 meters respectively. To view the image at these distances, the electro - active lens system provides net perceptible refractive powers of 0 diopters, 1 / 2 diopter, 1 diopter, and 2 diopters respectively, in the same order. In this example, lens A and lens B are each switchable between at least a subset of these refractive powers. Lens A is switchable between the 0 - diopter state and the 2 - diopter state, and lens B is switchable between the 0 - diopter state, the 1 / 2 - diopter state, and the 1 - diopter state.

[0045] In this example, when the polarization changer is in state A, lens A is optically present and lens B is not present. When the polarization changer is in state B, lens A is not optically present and lens B is present. That is, lens A focuses the light transmitted by the polarization changer in state A but does not focus when the polarization changer is in state B, and lens B focuses the light transmitted by the polarization changer in state B but does not focus when the polarization changer is in state A. A lens that is not focusing light, either because the lens is not operating or because the incident light is not polarized in a state that can be focused by the lens, provides a refractive power of 0 diopters.

[0046] At the start of the video, the polarization changer is in state A, the lens A is off and thus has 0 diopters, the lens B is also off, and due to the polarization changer being in state A, it has 0 diopters. The net perceivable refractive power of the electroactive lens system is 0 diopters.

[0047] Shortly after the video clip starts, for example, at the 1 - second mark, a processor coupled to or integrated with the electroactive lens instructs the lens B to switch its refractive power from 0 diopters to 1 / 2 diopter. While the lens B is changing focus, the polarization changer renders the lens B optically non - existent (the polarization changer is still in state A), so the observer cannot see the optical effect occurring in the lens B. The lens B takes a full 1 second to complete the change to the new refractive power, which is much longer than required. At the 2 - second mark of the video clip, the polarization changer switches from state A to state B, making the lens B optically present and changing the net perceivable refractive power of the system from 0 diopters to 1 / 2 diopter in 35 milliseconds.

[0048] Shortly after the 2 - second mark, for example, at the 3 - second mark, the processor instructs the lens A to switch its refractive power from 0 to 2 diopters. While the lens A is changing focus, the polarization changer renders the lens A optically non - existent (since the polarization changer is still in state B, the net perceivable refractive power of the electroactive lens system remains at 1 / 2 diopter), so the observer cannot see the optical effect occurring in the lens A. The lens A takes a full 1 second to complete the change to the new refractive power, which is much longer than required. At the 4 - second mark of the video clip, the polarization changer switches states again, making the lens A optically present and the lens B optically non - existent, and as a result, the net perceivable refractive power of the system changes from 1 / 2 diopter to 2 diopters in 35 milliseconds.

[0049] Immediately after the 4 - second mark, for example, at the 5 - second mark, the processor instructs lens B to switch its refractive power from 1 / 2 diopter to 1 diopter. During the transition state of the change, since the polarization changer makes lens B optically non - existent, the user cannot see any optical effect. It takes lens B a full second to complete the change to the new refractive power, which is much longer than required. At the 6 - second mark of the video clip, the polarization changer switches states, and as a result, the net perceivable refractive power of the system changes from 2 diopters to 1 diopter in 35 milliseconds.

[0050] Immediately after the 6 - second mark, for example, at the 7 - second mark, lens A is instructed to switch its refractive power from 1 diopter to 0 diopters. While lens A refocuses, the polarization changer makes lens A optically non - existent (the polarization changer is still in state B), so the observer cannot see the optical effect occurring with lens A. It takes lens A a full second to complete the change to the new refractive power, which is much longer than required. At the 8 - second mark of the video clip, the polarization changer switches states again, making lens A optically present and lens B optically absent, and as a result, the net perceivable refractive power of the system changes from 2 diopters to 0 diopters in 35 milliseconds.

[0051] This sequence may be changed and repeated as desired, and may be associated with and adjusted by a signal from a controller or processor presenting a digital image.

[0052] Although the lens may take hundreds of milliseconds to change focus, the observer observes that each change of focus occurs within 35 milliseconds.

[0053] Video output can be pre - prepared and programmed / controlled to be adjusted with the electro - active lens component to reduce the observer's perception of focus - switching time. However, in some cases, the video image may not be pre - prepared and cannot be used to control the switching in this pre - programmed manner. Instead, the electro - active lens operates in an on - demand switching mode controlled by the observer using a switch or other command device. In these cases, the polarization changer can be delayed from changing its state from one state to another until the focus - changing period is complete. As a result, a similar strategy may be adopted where the user will see a 35 - millisecond optical switching period and a 350 - millisecond delay between the switching command and execution, which may be more desirable than giving the user a 350 - millisecond focus - changing duration experience.

[0054] In another embodiment, a single electro - active lens can be used with a polarization rotator. By using two adjustable lenses, an almost infinite combination of high - speed switching configurations is possible from one refractive power to another, for example, from 1 diopter to 2 diopters, to 1 / 2 diopter, to 1 diopter, and then to 1 / 2 diopter, etc. While using a single lens enables high - speed switching between zero and another refractive power, such as next 0 diopter, then another refractive power, then 0 diopter, etc.

[0055] The system functions when random polarization enters the system (e.g., non - polarized emission from a non - polarized OLED display), but functions best with polarization. Non - polarized or random polarization can be polarized by a polarization filter located at the light - entry point of the system or by using a display technology that emits polarization, such as an LED display or a polarized OLED display.

[0056] Conclusion Although various embodiments of the invention have been described and illustrated herein, those skilled in the art will readily envision various other means and / or structures for performing the functions described herein and / or for obtaining the results and / or one or more of the advantages thereof, and each such variation and / or modification is to be regarded as within the scope of the embodiments of the invention described herein. More generally, those skilled in the art will readily understand that all parameters, dimensions, materials, and configurations described herein are meant to be illustrative and that the actual parameters, dimensions, materials, and / or configurations will depend on the particular application(s) for which the teachings of the invention are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Accordingly, the foregoing embodiments are presented by way of example only and it is understood that embodiments of the invention may be practiced otherwise than as specifically described and claimed within the scope of the appended claims and their equivalents. Embodiments of the invention disclosed herein are directed to each individual feature, system, article, material, kit, and / or method described herein. Additionally, any combination of two or more such features, systems, articles, materials, kits, and / or methods is included within the scope of the invention disclosed herein if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent.

[0057] The above embodiments can be implemented by any of a number of means. For example, embodiments of the design and fabrication of the technology disclosed herein may be implemented using hardware, software, or a combination thereof. When implemented in software, the software code may be executed by any suitable processor or collection of processors, whether provided on a single computer or distributed among multiple computers.

[0058] Also, concepts related to various inventions may be embodied in one or more ways, and examples have been provided. The acts performed as part of a method may be ordered in any suitable manner. As a result, embodiments may be constructed in which the acts are performed in an order different from that illustrated, which may include performing some acts simultaneously, even if they are shown as consecutive acts in an exemplary embodiment.

[0059] All definitions defined and used in this specification should be understood to control dictionary definitions, definitions in incorporated documents by reference, and / or the ordinary meaning of defined terms.

[0060] The indefinite articles "a" and "an" used in this specification and the claims should be understood to mean "at least one" unless explicitly indicated otherwise.

[0061] The phrase "and / or" used in this specification and the claims means "either or both" of the combined elements, i.e., elements that exist conjunctively in some cases and disjunctively in other cases. The multiple elements listed with "and / or" should be interpreted in the same manner, i.e., as "one or more" of the elements connected in parallel. Other elements may optionally exist in addition to the elements specifically identified by the "and / or" clause, whether or not they are related to the specifically identified elements. Therefore, by way of non-limiting example, a reference to "A and / or B", when used in conjunction with a syntax without limitations such as "comprising", can refer to only A in one embodiment (optionally including elements other than B), only B in another embodiment (optionally including elements other than A), both A and B in yet another embodiment (optionally including other elements), and so on.

[0062] As used in this specification and the claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" is inclusive, i.e., it includes at least one of a number of elements or a list of elements, and optionally additional items not in the list, but may also include more than two. Terms that clearly indicate the contrary, such as "only one of" or "exactly one of", or terms such as "consisting of" when used in the claims, refer to including exactly one element out of a number of or enumerated elements. Generally, the term "or" as used in this specification should be interpreted to indicate an exclusive alternative (i.e., "one or the other but not both") only when preceded by exclusive terms such as "either", "only one of", "only one and no more of", or "exactly one of". "Consisting essentially of" shall have the ordinary meaning as used in the field of patent law when used in the claims.

[0063] As used in this specification and the claims, the phrase "at least one" in relation to a list of one or more elements means at least one element selected from any one or more of the elements in the list of elements, but does not necessarily include at least one of every element specifically recited in the list of elements, and is not to be construed as excluding any combinations of elements in the list of elements. Also, by this definition, elements other than those specifically identified in the list of elements referred to by the phrase "at least one" are permitted to optionally exist, whether or not they are related to the specifically identified elements. Therefore, by way of non-limiting example, "at least one of A and B" (or equivalently "at least one of A or B", or equivalently "at least one of A and / or B") can refer to, in one embodiment, at least one A (optionally including elements other than B) where B does not exist and optionally including two or more A's, in another embodiment, at least one B (optionally including elements other than A) where A does not exist and optionally including two or more B's, and in yet another embodiment, at least one A optionally including two or more A's, and at least one B optionally including two or more B's (optionally including other elements).

[0064] In the claims, as well as in the above specification, all transitional phrases, such as "comprising", "including", "carrying", "having", "containing", "involving", "holding", "composed of", and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases "consisting of" and "consisting essentially of" are to be considered closed or semi-closed transitional phrases, respectively, as defined in the United States Patent and Trademark Office's Manual of Patent Examining Procedure, Section 2111.03.

Claims

Claim 1 An electroactive lens system comprising: A polarization switch that is switchable between a first state in which the polarization switch switches the polarization of light from a first polarization state to a second polarization state and a second state in which the polarization switch transmits light in the first polarization state; said polarization switch; A first electroactive lens arranged to receive the light from the polarization switch, the first electroactive lens being switchable between a first focusing state in which the first electroactive lens focuses light in the first polarization state and transmits the light in the second polarization state without focusing the light in the second polarization state, and a first non-focusing state in which the first electroactive lens transmits the light in the first polarization state and the second polarization state without focusing the light in the first polarization state or the second polarization state; said first electroactive lens; A second electroactive lens arranged to receive the light from the polarization switch and the first electroactive lens, the second electroactive lens being switchable between a second focusing state in which the second electroactive lens transmits the light in the first polarization state without focusing the light in the first polarization state and focuses the light in the second polarization state, and a second non-focusing state in which the second electroactive lens transmits the light in the first polarization state and the second polarization state without focusing the light in the first polarization state or the second polarization state; said second electroactive lens; and said electroactive lens system. Claim 2 The electroactive lens system according to claim 1, wherein the polarization switch comprises a liquid crystal wave plate having a switchable phase difference. Claim 3 The electroactive lens system according to claim 1, wherein the polarization switch has a phase difference of π / 2 in the first state and a phase difference of 0 in the second state. Claim 4 The electroactive lens system according to claim 1, wherein (i) the polarization switch is configured to switch between the first state and the second state faster than the first electroactive lens is configured to switch between the first focusing state and the first non-focusing state, and (ii) the polarization switch is configured to switch between the first state and the second state faster than the second electroactive lens is configured to switch between the second focusing state and the second non-focusing state. Claim 5 The electro-active lens system according to claim 4, wherein the polarization switch is configured to switch between the first state and the second state within 100 milliseconds.

6. The electro-active lens system according to claim 5, wherein the first electro-active lens is configured to switch between the first focusing state and the first non-focusing state in more than 100 milliseconds, and the second electro-active lens is configured to switch between the second focusing state and the second non-focusing state in more than 100 milliseconds.

7. The electro-active lens system according to claim 5, wherein the polarization switch is configured to switch between the first state and the second state within 30 milliseconds.

8. The electro-active lens system according to claim 1, wherein the polarization switch and the first electro-active lens share a first common substrate, and the first electro-active lens and the second electro-active lens share a second common substrate.

9. The electro-active lens system according to claim 1, wherein the first polarization state is a first linearly polarized state, and the second polarization state is a second linearly polarized state orthogonal to the first linearly polarized state.

10. A method of focusing light in an electro-active lens system, the electro-active lens system comprising a polarization switch that is switchable between a first state in which the polarization switch switches the polarization of light from a first polarization state to a second polarization state and a second state in which the polarization switch transmits light in the first polarization state; a first electro-active lens arranged to receive the light from the polarization switch, the first electro-active lens being switchable between a first focusing state in which the first electro-active lens focuses light in the first polarization state and transmits the light in the second polarization state without focusing the light in the second polarization state, and a first non-focusing state in which the first electro-active lens transmits the light in the first polarization state and the second polarization state without focusing the light in the first polarization state or the second polarization state; A second electro-active lens arranged to receive the light from the polarization switch and the first electro-active lens, wherein the second electro-active lens transmits the light in the first polarization state without focusing the light in the first polarization state, and a second focusing state in which the light is focused in the second polarization state; and a second non-focusing state in which the second electro-active lens transmits the light in the first polarization state and the second polarization state without focusing the light in the first polarization state or the second polarization state. The second electro-active lens is switchable between the two states, and the method includes: Setting the polarization switch to one of the first state or the second state; Setting the first electro-active lens to one of the first focusing state or the first non-focusing state; Setting the second electro-active lens to one of the second focusing state or the second non-focusing state; Sending the light through the polarization switch, the first electro-active lens, and the second electro-active lens. A method of focusing light in the electro-active lens system.

11. The method according to claim 10, wherein the polarization switch is in the second state, the first electro-active lens is in the first focusing state, and the second electro-active lens is in the second non-focusing state. Further, While switching the second electro-active lens from the second non-focusing state to the second focusing state, transmitting the light in the first polarization state through the polarization switch, focusing the light with the first electro-active lens, and transmitting the light through the second electro-active lens without focusing the light with the second electro-active lens; After the second electro-active lens has switched from the second non-focusing state to the second focusing state, switching the polarization switch from the second state to the first state, thereby focusing the light on the second electro-active lens and transmitting the light through the first electro-active lens without focusing the light on the first electro-active lens. The method includes:

12. The method according to claim 11, wherein switching the polarization switch from the second state to the first state after the second electro-active lens has switched from the second non-focusing state to the second focusing state is performed in response to a desired change in the position of the virtual image.

13. The method according to claim 11, wherein switching the second electro-active lens from the second non-converging state to the second converging state takes at least 100 milliseconds, and switching the polarization switch from the second state to the first state takes less than 100 milliseconds.

14. The method according to claim 10, wherein the first polarization state is a first linearly polarized state, and the second polarization state is a second linearly polarized state orthogonal to the first linearly polarized state.

15. An electro-active lens system comprising: a liquid crystal wave plate capable of switching between a zero wavelength retardation and a half-wave retardation within 35 milliseconds; a first liquid crystal lens arranged to receive light from the liquid crystal wave plate, the first liquid crystal lens being switchable between a first state in which the first liquid crystal lens focuses light in a first linearly polarized state on a first focal plane and a second state in which the first liquid crystal lens focuses light in the first linearly polarized state on a second focal plane; a second liquid crystal lens arranged to receive light from the liquid crystal wave plate and the first liquid crystal lens, the second liquid crystal lens being switchable between a first state in which the second liquid crystal lens focuses light in a second linearly polarized state orthogonal to the first linearly polarized state on a third focal plane and a second state in which the second liquid crystal lens focuses light in the second linearly polarized state on a fourth focal plane.

16. The electro-active lens system according to claim 15, wherein the liquid crystal wave plate and the first liquid crystal lens share a first common substrate, and the first liquid crystal lens and the second liquid crystal lens share a second common substrate.

17. The electro-active lens system according to claim 15, wherein the first liquid crystal lens is configured to transmit the light in the second linearly polarized state without focusing the light in the second linearly polarized state, and the second liquid crystal lens is configured to transmit the light in the first linearly polarized state without focusing the light in the first linearly polarized state.

18. The electro-active lens system according to claim 15, wherein the first liquid crystal lens is configured to switch between the first state and the second state in more than 35 milliseconds.

19. The electro-active lens system according to claim 15, comprising: The electroactive lens system further comprising a display configured to emit light to the liquid crystal waveplate in the first linearly polarized state. **Claim 20** The electroactive lens system according to claim 19, The electroactive lens system further comprising a processor operably coupled to the liquid crystal waveplate, the first liquid crystal lens, the second liquid crystal lens, and the display, and configured to control the phase difference of the liquid crystal waveplate, the first liquid crystal lens, the second liquid crystal lens, and the display.

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