Prism-enhanced lenses and methods of using prism-enhanced lenses

Abstract

This application relates to prism-enhanced lenses and methods for using prism-enhanced lenses. An electro-active lens utilizing a surface relief structure and electro-active materials is presented, wherein changes in refractive index promote changes in optical properties. Molded structures and liquid crystals are used to form a diffractive lens. In addition to the classic lens formation method using diffractive optics and multiple Fresnel zones, additional structures are placed between the Fresnel zones to improve diffraction efficiency across the visible spectrum and reduce chromatic aberration.

Description

[0001] This application is a divisional application based on the patent application with application number 201780009140.7, application date January 31, 2017, and invention name “Prism-enhanced lens and method using prism-enhanced lens”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of priority under 35 U.S.C. 119 to U.S. application No. 62 / 321,893, filed on April 13, 2016, entitled “Prism-Enhanced Lenses,” and U.S. application No. 62 / 289,512, filed on February 1, 2016, entitled “Enhanced Surface Relief Lenses,” each of which is incorporated herein by reference in its entirety. Background Art

[0004] A fundamental limitation of diffraction-based lenses is their inherent wavelength dependence, which results in reduced diffraction efficiency outside the lens's specified design wavelength. This arises from the requirement for constructive interference at the lens's focus, which can generally only be optimized for a single wavelength of light in the visible region.

[0005] As those skilled in the art will appreciate, conventional diffractive lenses include one or more phase wraps or resets. Phase wrapping (or phase reset) is a sawtooth-like modulation of the lens's phase retardation profile, where each tooth or "wrap" has an optical path length approximately equal to an integer number of wavelengths. This allows for thinner devices, where optical power is induced by constructive interference at the focal point through diffraction rather than refraction across the entire lens.

[0006] Phase resetting corresponding to an integer number of wavelengths produces perfect constructive interference and is considered to have 100% diffraction efficiency. However, when the phase resetting is not an integer number of wavelengths, the performance of the lens degrades due to the lack of perfect constructive interference at the focus, which results in a decrease in diffraction efficiency. Diffraction efficiency decreases as the optical path difference associated with the phase resetting deviates from an integer number of wavelengths. Minimum diffraction efficiency occurs when the phase resetting corresponds to half a wavelength (where the phase resetting corresponds to destructive interference).

[0007] Due to the variation in wavelength across the visible spectrum, for a single wavelength (defined as the design wavelength λ0), the phase reset in a conventional diffractive lens only corresponds to a phase delay of an integer number n wavelengths. For other wavelengths of light, the phase reset may correspond to a non-integer number of wavelengths; as the wavelength becomes larger or smaller than the design wavelength, the phase difference at the phase reset deviates from an integer number of wavelengths. This degrades the performance of the lens away from the design wavelength.

[0008] The diffraction efficiency (η) of a phase-based diffractive lens can be quantitatively described using the following equation:

[0009]

[0010] where λ is the wavelength of the light, λ0 is the design wavelength of the lens, and k is the diffraction order. (In the case of a diffractive lens, for proper operation, the diffraction order is first order, k = 1.) This function does not include the effects of optical dispersion associated with the material used to make the lens. Material dispersion can further reduce diffraction efficiency at wavelengths far from the design wavelength.

[0011] Some example calculations are shown below for a diffractive lens with a design wavelength (λ0) of 550 nm:

[0012] Table 1

[0013] Wavelength (λ) Diffraction efficiency (η) 450nm 0.848 500nm 0.968 550nm 1 600nm 0.978 650nm 0.925

[0014] For such lenses, the diffraction efficiency varies by more than 15% across the visible spectrum.This reduction in diffraction efficiency can be of greater importance when working with multi-order diffractive lenses (whereby phase resetting occurs at more than one integer number of wavelengths). Summary of the Invention

[0015] The inventors have recognized that the chromatic dependence of diffractive lenses is a major drawback when compared to refractive optics. The present technology addresses this drawback by providing the diffractive lens with an additional prismatic structure in the phase-wrapped region to mitigate unwanted destructive interference. The additional prismatic structure provides a trade-off between diffraction efficiency at the design wavelength and at other wavelengths. This is particularly beneficial for ophthalmic lenses, including spectacle lenses, contact lenses, and intraocular lenses.

[0016] The technology can be implemented as an electro-active lens, in which an electro-active material (such as a liquid crystal material) is in optical communication with a surface relief structure that includes additional prismatic structures. The surface relief structure can be molded and then bonded to another substrate to form a cavity that holds the liquid crystal material.

[0017] Embodiments of the present invention include an electro-active lens comprising a first substrate, a second substrate, a liquid crystal material disposed between the first and second substrates, and a surface relief structure formed in the first substrate opposite the second substrate. The surface relief structure defines a Fresnel lens having a plurality of concentric rings and at least one prismatic structure disposed between a pair of concentric rings in the plurality of concentric rings.

[0018] In some cases, the mth ring in the plurality of concentric rings has a value greater than Where m is an integer greater than 1, f is the focal length of the Fresnel lens, and λ0 is the design wavelength of the electro-active lens. If there are, for example, m-1 prismatic structures with an aggregate width w, then the inner radius of the mth ring in the plurality of concentric rings is equal to r m The sum of w.

[0019] The prismatic structure may include an annular prismatic structure concentric with a pair of concentric rings. In some examples, an annular prismatic structure may be present between each pair of concentric rings in the plurality of concentric rings and concentric with each pair of concentric rings. Furthermore, in some cases, one or more of the prismatic structures may overlap with adjacent concentric rings. One or more of the prismatic structures may define a plurality of peaks, a curved surface, or both. The prismatic structure may have a height of approximately 0.1 micrometers to approximately 50 micrometers and a width of approximately 5 micrometers to approximately 200 micrometers.

[0020] A multi-stage prism-enhanced lens (i.e., a lens having concentric rings with a height equal to mλ, where m is an integer greater than 1 and λ is the design wavelength) can have a Strehl ratio greater than about 0.85 at a wavelength of about 550 nm, a Strehl ratio greater than about 0.70 at a wavelength of about 450 nm, and a Strehl ratio greater than about 0.60 at a wavelength of about 450 nm. For example, the Strehl ratio of the electro-active lens can be greater than about 0.65 or even 0.80 over a wavelength range of about 450 nm to about 650 nm.

[0021] Another example electro-active lens includes a first substrate, a second substrate, a liquid crystal material disposed between the first and second substrates, and a surface relief structure formed in the first substrate opposite the second substrate. The surface relief structure defines a stack of concentric Fresnel lenses. The stack of concentric Fresnel lenses may include a first Fresnel lens having a first height and a second Fresnel lens having a second height less than the first height.

[0022] Other embodiments include a method of focusing light. The method includes focusing light using an electro-active lens comprising a first substrate, a second substrate, a liquid crystal material disposed between the first and second substrates, and a surface relief structure formed in the first substrate opposite the second substrate. The surface relief structure defines a Fresnel lens having a plurality of concentric rings and at least one prismatic structure disposed between a pair of the plurality of concentric rings. Applying a voltage to the liquid crystal material changes the focal length of the electro-active lens.

[0023] Another example electro-active lens includes a first substrate, a second substrate, a liquid crystal material disposed between the first and second substrates, and a surface relief structure formed in the first substrate opposite the second substrate. The surface relief structure defines a Fresnel lens having a plurality of concentric rings and at least one interstitial element disposed between a pair of concentric rings in the plurality of concentric rings. The interstitial element may have a width of approximately 25 microns.

[0024] It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of the claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. It should also be appreciated that terminology explicitly employed herein that may also appear in any disclosure incorporated by reference should be given a meaning most consistent with the specific concepts disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Those skilled in the art will understand that the drawings are primarily for illustrative purposes and are not intended to limit the scope of the inventive subject matter described herein. The drawings are not necessarily drawn to scale; in some cases, various aspects of the inventive subject matter disclosed herein may be shown exaggerated or enlarged in the drawings to facilitate understanding of the various features. In the drawings, like reference characters generally refer to like features (e.g., functionally similar and / or structurally similar elements).

[0026] Figure 1 A cross section of an electro-active lens is shown, comprising a liquid crystal layer arranged between a flat substrate and a substrate defining a Fresnel lens.

[0027] Figure 2A A cross section of an electro-active prism-enhanced ophthalmic lens is shown, comprising a liquid crystal layer disposed between a flat substrate and a substrate defining a Fresnel lens, and a prismatic structure disposed between two rings of the Fresnel lens.

[0028] Figure 2B Shown Figure 2A Close-up of the cross section shown in .

[0029] Figure 2C Shown Figure 2A and 2B Plan view of the surface relief structure of the prismatically enhanced lens shown in FIG.

[0030] Figure 2D Shown Figures 2A-2C A perspective view of the surface relief structure of a prismatically enhanced lens is shown in FIG.

[0031] Figure 3shows the on-axis optical cross Figures 2A-2D The optical path difference (OPD) of the device and its comparison with the OPD of a phase-based diffractive lens designed for blue, green or red light.

[0032] Figure 4 Shown is a cross section of an electro-active lens comprising a liquid crystal layer arranged between a flat substrate and a substrate defining a Fresnel lens, and a "bicuspid" prismatic structure arranged between two rings of the Fresnel lens.

[0033] Figure 5 shows the on-axis optical cross Figure 4 The OPD of the device and its comparison with the OPD of a phase-based diffractive lens designed for green light.

[0034] Figure 6 Shown is a cross section of a prismatically enhanced lens having a circular prismatic structure between a pair of concentric rings of a Fresnel lens.

[0035] Figure 7 A cross section of a prismatically enhanced lens is shown having a sawtooth prismatic structure between a pair of concentric rings of a Fresnel lens.

[0036] Figure 8 Shown is a cross section of a Fresnel lens having a gap between a pair of concentric rings of the Fresnel lens.

[0037] Figure 9 A profile diagram of an electro-active prism enhanced lens is shown.

[0038] Figure 10-12 The difference in Strehl ratio when comparing a standard diffractive kinoform lens and an example prism-enhanced lens for light wavelengths of 550 nm, 650 nm, and 450 nm is shown.

[0039] Figure 13 A graph showing the normalized irradiance of light at a wavelength of 450 nm focused by a prism-enhanced lens to a distance of 0.976 meters.

[0040] Figure 14 A graph showing the normalized irradiance of light at a wavelength of 550 nm focused by a prism-enhanced lens to a distance of 1.064 meters.

[0041] Figure 15 A graph showing the normalized irradiance of light at a wavelength of 650 nm focused by a prism-enhanced lens to a distance of 0.902 meters is shown. DETAILED DESCRIPTION

[0042] An electro-active prism-enhanced lens can be characterized by having a surface relief structure formed by combining or superimposing two or more Fresnel lenses. These Fresnel lenses can be spherical Fresnel lenses with different design wavelengths or focal lengths; cylindrical Fresnel lenses with different orientations, design wavelengths, or focal lengths; or a combination of spherical and cylindrical Fresnel lenses. They can be scaled and / or offset from each other along the optical axis of the prism-enhanced lens before being superimposed. The precise scale, shift, and shape can depend in part on the dispersion of the lens material, the dispersion of the liquid crystal in the lens-like operating state (e.g., extraordinary refractive index in a vertically aligned system, ordinary refractive index in a planar aligned system, or intermediate states), or both. The resulting superimposed structure can be circularly symmetric or asymmetric (e.g., to correct for astigmatism) and can be used to define a mold for forming a lens substrate.

[0043] Compared to a conventional Fresnel lens, a prismatically enhanced lens can have better (average) optical performance over a wider wavelength range, e.g., over the visible spectrum (approximately 450-650 nm). For example, a prismatically enhanced lens can have a higher average diffraction efficiency over the visible spectrum than a conventional Fresnel lens. Alternatively or additionally, the Strehl Ratio (explained below) of a prismatically enhanced lens can vary by about 0.25 or less (e.g., from 0.6 to 0.85, or by about 0.20, 0.15, 0.10, or 0.05) over the wavelength range of 450-650 nm, while the Strehl Ratio of a comparable conventional Fresnel lens can vary by more than 0.25 (e.g., by about 0.50) over the same wavelength range.

[0044] However, compared to some traditional Fresnel lenses, prism-enhanced lenses may suffer from disadvantages, including a larger minimum resolvable spot size at the central design wavelength. In other words, a prism-enhanced lens may have a smaller modulation transfer function (MTF) at the central design wavelength than a comparable traditional Fresnel lens. However, it should have a larger MTF at other wavelengths than such a comparable traditional Fresnel lens.

[0045] Prism-enhanced lenses can be used in many different types of applications. They are particularly well-suited for vision correction, which does not require the diffraction-limited optical performance typically required for camera lenses and other optical applications. For example, electro-active prism-enhanced lenses can be used to form all or part of eyeglass lenses, contact lenses, intraocular lenses, or any other lens used in the eye.

[0046] Electro-active Fresnel lens

[0047] Figure 1A cross-section of two Fresnel zones 106 and 107 in a surface-relief liquid crystal electro-active lens 100 is shown. Lens 100 comprises a vertically aligned liquid crystal layer 101 disposed between two substrates 103 and 104, with alignment layers and transparent conductive layers applied to the substrate surface 105 in contact with the liquid crystal layer, as is readily understood in the art. Substrate 104 defines a surface-relief structure 102—here, a Fresnel lens—with diffractive structures (concentric rings) 106 and 107. The height of diffractive structures 106 and 107 can range from 0.5 to 50 microns, depending on the number of wavelengths reset per phase, the birefringence of the liquid crystal, the focal power of the lens, and the design wavelength of the incident light. For a standard one-wavelength-per-phase lens, the diffractive structures are typically 2 to 5 microns high. For a +1.00D lens designed for 450nm light, when considering the first two Fresnel zones, the radii of diffractive structures 106 and 107 are 950 microns and 390 microns, respectively.

[0048] The refractive index of the substrate 104 can be matched to the refractive index of the liquid crystal 101 so that when the liquid crystal 101 is in an "off" or unmodulated state, the surface relief structure 102 is unnoticeable. Applying a voltage to the liquid crystal 101 causes the liquid crystal 101 to reorient, thereby changing the refractive index of the liquid crystal, as is understood in the art. This change in the refractive index of the liquid crystal makes the surface relief structure 102 apparent, thereby changing the optical power of the lens 100.

[0049] Prism-enhanced ophthalmic lenses

[0050] Figures 2A-2D Different views of an electro-active prism enhanced ophthalmic lens 200 are shown. Figure 1 Like lens 100 shown in FIG, prism-enhanced ophthalmic lens 200 includes liquid crystal material 101 disposed in a cavity formed between substrates 103 and 204, wherein surface relief structure 202 is formed in substrate 204. Substrates 103 and 204 together form a substantially or static meniscus lens that provides a fixed optical power, which depends on the curvature and refractive index of the substrates. (In other cases, the substrates can be flat, with a uniform refractive index, to provide little fixed optical power. Or they can be shaped to form biconvex, biconcave, plano-concave, or plano-convex lenses.) The size, shape, and material of the substrates can be selected so that lens 200 is a contact lens, an intraocular lens, or an eyeglass lens.

[0051] exist Figures 2B-2DSurface relief structure 202, shown in more detail in FIG, defines a Fresnel lens comprising concentric Fresnel rings 206a-206f (collectively, concentric rings 206). However, unlike conventional Fresnel lenses, surface relief structure 202 includes additional prismatic structures 201a-201e (collectively, prismatic structures 201), each of which is disposed between a pair of concentric rings 206. In operation, prismatic structures 201 redirect light into the focal point of diffractive lens 200. Other example lenses may have fewer prismatic structures, e.g., prismatic structures only between the inner or outer few concentric rings, one prismatic structure between every second or third pair of concentric rings, and so on. There may also be a blending region near the outer periphery of the Fresnel lens, e.g., to provide a gradual change in optical power.

[0052] In this example, each prismatic structure 201 is annular and concentric with the concentric rings 206 of the Fresnel lens. For example, prismatic structure 201a is disposed between and concentric with concentric rings 206a and 206b. Other example lenses may have prismatic structures of other shapes when viewed along the optical axis of the lens, including C-shaped prismatic structures, periodically segmented annular prismatic structures, and non-periodically segmented annular prismatic structures. For example, additional prismatic structures may be shaped to provide cylindrical power along one or more axes orthogonal to the optical axis of the lens.

[0053] Depending on their size and shape, the additional prismatic structures 201 can be considered to form a second Fresnel lens concentric with the concentric rings 206 of the first Fresnel lens. The first and second Fresnel lenses can be optimized to operate at different wavelengths. They can have different focal lengths at a given wavelength and can be offset relative to each other along the optical axis of the ophthalmic lens 200. In other words, there can be a difference in the number of Fresnel lenses that are superimposed to form a second Fresnel lens. Figure 2C and 2D The composite relief structure shown in FIG is a bias or offset previously applied to one of the Fresnel lenses (e.g., the first Fresnel lens). The difference between the first and second Fresnel lenses can also be expressed or represented as a different number of rings, where the rings have different sizes, shapes, and positions.

[0054] The ophthalmic lens 200 also includes various electronic components 290, including but not limited to a processor / driver circuit, a power supply, an antenna, or a photodetector, for actuating the liquid crystal material 101. In this case, the electronic components 290 are sandwiched between the substrates 103 and 204; in other cases, they can be disposed externally to the lens 200. These electronic components 290 modulate the focal length of the ophthalmic lens by varying the voltage applied to the liquid crystal material 101 via transparent or nearly transparent conductive traces 292 connected to electrodes 294 (only one shown) on either side of the liquid crystal material 101. The electrodes can be formed from a transparent conductive material, such as indium tin oxide (ITO), deposited on the substrate 103 and the surface relief structure 202. These electrodes do not necessarily need to be patterned, but rather another conductive material (e.g., ITO) can be deposited and patterned to form the conductive traces 292 connecting the electrodes to the drive electronics.

[0055] At or near a bias voltage of 0 volts, the refractive index of the liquid crystal material can substantially match the refractive index of the surrounding substrate 204, thereby making the surface relief pattern 202 appear transparent or nearly transparent to the wearer. Applying a voltage to the liquid crystal material 101 changes the refractive index of the liquid crystal material, thereby changing the optical power provided by the portion of the lens 200 containing the surface relief structure 202. This change in optical power can be positive or negative, depending on the liquid crystal material, the applied voltage, the surface relief structure, or the lens shape.

[0056] Typically, each prismatic structure 201 is shorter and narrower than the adjacent concentric rings 206. In this example, the maximum height of the prismatic structure 201a is from 0.1 to 50 microns (e.g., 0.25 microns, 0.50 microns, 0.75 microns, 1 micron, 2 microns, 5 microns, 7.5 microns, 10 microns, 15 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, or any sub-range or value within this range). The width of the prismatic structure 201a is typically from 5 microns to 200 microns (e.g., 7.5 microns, 10 microns, 15 microns, 25 microns, 50 microns, 75 microns, 100 microns, 125 microns, 150 microns, 175 microns, or any sub-range or value within this range). For example, each prismatic structure 201 can be 25 microns wide and can have a height ranging from 0.25 microns to 0.75 microns.

[0057] The prismatic structures 201 may have different heights, different widths, or a combination of both. For example, the inner prismatic structures 201 may be taller, wider, or both taller and wider than the outer prismatic structures 201 .

[0058] The second Fresnel zone 206b is shifted outward from the center of the lens 200 to make room for the prismatic structure 201a, which modifies the spacing of the Fresnel zones. In a conventional Fresnel lens, the equation Calculate the radius of the Fresnel zone spacing, where m is the Fresnel zone number, f is the focal length of the lens (e.g., 25 mm to infinity), and λ0 is the design wavelength of light. In this prism-enhanced diffractive lens 200, the Fresnel zones are shifted outward, which increases the Fresnel zone spacing for Fresnel zones farther from the center of the lens.

[0059] The size of the prism affects the zone spacing as follows: the inner radius of a given Fresnel zone is increased by an amount equal to the sum of the widths of the prismatic structure between that given Fresnel zone and the center of the lens. To see how, consider Figure 2A The lens 200 shown in FIG. has five prismatic structures 201 and six concentric rings 206. The inner radius of the outermost ring 206f is equal to the sum of the widths of the five prismatic structures 201 and √12fλ0 (m=6). In this case, if the width of the prismatic structures 201 is 0.25 to 0.75 microns, the inner radius of the outermost ring 206f is 1.25 to 3.75 microns larger than the inner radius in the absence of the prismatic structures. Therefore, the inner radius of the outermost ring 206f is larger than the inner radius of the sixth Fresnel zone in a conventional lens having the same focal length and design wavelength.

[0060] exist Figures 2A-2D In the example shown in FIG, the addition of a prism structure can be used to improve the diffraction efficiency of the multi-order diffraction structure, so that the phase reset position appears at integer wavelengths, not just as Figure 3 and 4 In this case, the diffraction efficiency drops off dramatically with deviation from the design wavelength, and greater emphasis is placed on removing this limitation.

[0061] Optical path difference in prism-enhanced lenses

[0062] By controlling the height of the surface relief profile, the optical path difference (OPD) of a prismatically enhanced ophthalmic lens can be modified to correspond to different wavelengths of light in different regions of the lens. The OPD can be expressed as:

[0063]

[0064] Where r is the distance from the center of the lens (radius), f is the focal length, and λ is the wavelength. The OPD resets at an integer number of wavelengths (e.g., 1, 2, 3, or 4 wavelengths) to produce a sawtooth profile.

[0065] Light is also guided to a focal point via a prismatic structure between the Fresnel zones, which improves optical performance. The combination of the addition of prismatic structures and the shifting of the Fresnel zones, if optimized, results in superior optical performance and increased diffraction efficiency.

[0066] Figure 3 The on-axis OPD of the prismatically enhanced ophthalmic lens 200 shown in FIG2 is shown (dashed line) and the OPD of light of a phase-based diffractive lens designed for blue light (dotted line), green light (dashed-dotted line), or red light (solid line). Figure 3 On the left side of the prism-enhanced ophthalmic lens 200, the OPD corresponds very similarly to the OPD of a diffractive lens designed to work with blue light, indicating good optical performance for blue light in that area of ​​the prism-enhanced ophthalmic lens. In the center, due to the shift in the position of phase wrapping in the prism-enhanced ophthalmic lens, the OPD of the prism-enhanced ophthalmic lens 200 corresponds very similarly to the OPD of a diffractive lens used for green light, indicating good optical performance for green light in that area of ​​the prism-enhanced ophthalmic lens 200. A similar situation occurs at the edges of the lens, where the OPD of the prism-enhanced ophthalmic lens 200 is similar to the OPD of a diffractive lens used for red light.

[0067] The correspondence of the OPDs of different regions of the prismatically enhanced ophthalmic lens 200 with the OPDs of diffractive lenses designed for different wavelengths indicates that the lens 200 is not as wavelength sensitive as existing diffractive optics. Light from the prismatic region also enters the focus via refraction to avoid losses at regions where phase wrapping moves outward.

[0068] "Double-pointed" prism-enhanced lenses

[0069] Figure 4 Another electro-active prism-enhanced lens 400 is shown. Again, prism-enhanced lens 400 includes a surface relief structure 402 formed on one surface of substrate 404 and defining a Fresnel lens comprising concentric rings 406 and 407. Surface relief structure 402 also includes a prismatic term 401 that cuts into the interface between concentric rings 406 and 407. In other words, the base of prismatic term 401 overlaps the base of concentric rings 407, thereby forming a bicuspid prism structure (i.e., a prismatic structure with two peaks). In operation, prismatic term 401 directs light into the focal point of lens 400. It also mitigates the reduction in diffraction efficiency at wavelengths above and below the design wavelength of the Fresnel lens.

[0070] Figure 5 Is for Figure 4FIG1 is a plot of the OPD of a prism-enhanced lens 400 (dashed line) and a conventional Fresnel lens designed for optimal performance at a wavelength of 550 nm (solid line). In this case, the prism structure in the prism-enhanced lens 400 does not shift the Fresnel zone position, but instead occupies zones before and after each phase reset. Figure 5 The OPD of the prism-enhanced lens 400 is shown to be largely identical to the OPD of a conventional Fresnel lens designed for green light (the Fresnel zones do not shift position compared to a diffractive lens for the same wavelength). The prism-enhanced lens 400 has a prismatic structure in regions before and after each phase wrap position in a standard diffractive lens. This demonstrates that selecting the prism angle to correspond to the focal point of light of different wavelengths can result in superior optical performance for other wavelengths.

[0071] Alternative prism-enhanced lenses

[0072] Figure 6-8 More alternative electro-active prism-enhanced lenses are shown.

[0073] exist Figure 6 In the lens 600, the surface relief structure 602 defines a circular optical device 601 disposed between Fresnel zones 606 and 607. Figure 7 In the lens 700, the surface relief structure 702 defines a prismatic structure 701 having a plurality of peaks 703 disposed adjacent to a Fresnel zone 706 and overlapping a Fresnel zone 707. Figure 8 In lens 800, surface relief structure 802 defines a gap element or optical clear area 801 between Fresnel zones 806 and 807. This gap element 801 can have a width of approximately 5 microns to 200 microns (e.g., 7.5 microns, 10 microns, 15 microns, 25 microns, 50 microns, 75 microns, 100 microns, 125 microns, 150 microns, 175 microns, or any sub-range or value within this range). For example, gap element 801 is approximately 25 microns wide.

[0074] In each of these lenses, the precise shape of the surface relief structure can be selected to reduce the wavelength dependence of the optic, focus light at a focal point over a wide range of wavelengths, and / or mitigate the reduction in diffraction efficiency when operating outside the design wavelength. Those skilled in the art will readily appreciate that the prismatic structure can take additional forms, including forms with different scales, additional peaks, different shapes, etc., with the scope of the invention extending to any number of intermediate structures between the Fresnel zones.

[0075] Figure 9An example design of a prismatically enhanced lens having the parameters listed in Table 2 (below) is shown. The prismatically enhanced lens has a design optical power of +1.00D at a wavelength of 550nm. It includes a surface relief structure in which concentric rings and prismatic structures are formed in a PMMA substrate. The concentric rings are each approximately 9 microns high, with the width varying from almost 2 mm to approximately 0.5 mm. There is an annular prismatic structure between each pair of concentric rings. Each annular prismatic structure is approximately 25 microns wide and approximately 250 nm to 750 nm high. The void or cavity defined by the surface relief structure (having the concentric rings and prismatic structures) and another substrate (not shown) is filled with a liquid crystal material having a refractive index of approximately 1.7.

[0076] Table 2

[0077] Design wavelength 550nm Design optical power +1.00D Number of wavelengths per phase reset 3 (at 550nm) Prism width 25 microns Prism height 250nm to 750nm Number of prisms 5 Substrate material PMMA (refractive index = 1.5) liquid crystal material Refractive index = 1.7

[0078] This is just one example configuration to illustrate the concept of prism-enhanced design. Other parameters and prisms can be used to further modify the optical properties of the lens to further improve its diffraction efficiency and reduce chromatic aberration. In this example, the lens has phase reset at three wavelengths of optical path difference, rather than a single wavelength, to simplify lens manufacturing.

[0079] Prism-enhanced lens optical performance

[0080] Generally, the optical performance of a prismatically enhanced lens can be better, on average, over a wider range of wavelengths than the optical performance of a conventional Fresnel lens, where a conventional Fresnel lens has better performance at a particular wavelength or narrow range of wavelengths. For example, a prismatically enhanced lens can have a focal length that varies less with wavelength than a conventional Fresnel lens.

[0081] Similarly, a prism-enhanced lens can have a Strehl ratio that deviates less with wavelength over a given wavelength band than a conventional Fresnel lens. As understood by those skilled in the art of optics, the Strehl ratio is often defined as the ratio of the peak aberrated image intensity from a point source compared to the maximum achievable intensity using an ideal optical system limited only by diffraction at the aperture of the system. It is also often expressed in terms of the intensity at the center of the image (the intersection of the optical axis and the focal plane) resulting from an on-axis source. In most cases, these definitions result in very similar graphs (or identical graphs when the point of peak intensity is at the center due to symmetry).

[0082] A prism-enhanced lens can have a higher Strehl Ratio range over a given wavelength region (either across the wavelength region or on average) than a standard diffractive kinoform lens over the same wavelength region. In other cases, the minimum Strehl Ratio of a prism-enhanced lens can be greater than the minimum Strehl Ratio of a standard diffractive kinoform lens over the visible portion of the electromagnetic spectrum. For example, a prism-enhanced lens can have a minimum Strehl Ratio of 0.65, 0.70, 0.75, 0.80, 0.85, or higher over a range of about 450 nm to about 650 nm. For ophthalmic applications using low-cost optics, a Strehl Ratio of 0.65 may be acceptable.

[0083] Figure 10 、 11 1 and 12 show the difference in Strehl ratio when comparing a standard diffractive kinoform lens and an example prism-enhanced lens for light wavelengths of 450 nm, 550 nm, and 650 nm, respectively. Figure 11 In the case of 550nm, the standard diffraction lens performs better, as expected, since the design wavelength corresponds to 100% diffraction efficiency. The Strehl ratio of the prism-enhanced lens is above 0.8, so it can be considered a nearly diffraction-limited system.

[0084] exist Figure 11 and 12 Some of the advantages associated with this particular example of a prism-enhanced lens are demonstrated in . Figure 12 In the example, considering 650nm light, the Strehl ratio is about 0.1 higher in the prism-enhanced lens than in the standard diffraction lens. The prism-enhanced lens also has lower chromatic aberration compared to the standard diffraction lens, where the focal length is moved from 0.85m to 0.90m, thus being closer to the design focal length of 1m. When considering 650nm light, Figure 12 Chromatic aberration is also lower for the prism-enhanced lenses, with similar Strehl ratios observed between the prism-enhanced lenses and standard diffractive lenses.

[0085] Figure 13-15 Shown at different wavelengths Figure 10-12 Irradiance plots in the focal plane of a prism-enhanced lens. That is, they show the lateral irradiance distribution at the focal plane for each wavelength. Each irradiance plot shows a sharp focus, indicating that the lens exhibits good optical performance across the visible spectrum. Figure 13 Shown is an irradiance graph for 450 nm light at a distance of 0.976 meters from the prismatically enhanced lens. Figure 14 shows the irradiance graph for 550nm light at a distance of 1.064 meters from the prism-enhanced lens. And, Figure 15 Shown is an irradiance graph for 650 nm light at a distance of 0.902 meters from the prismatically enhanced lens.

[0086] Thus, the above prism-enhanced example improves the optical quality of the lens in the blue wavelength region while maintaining a Strehl ratio close to the diffraction limit at the design wavelength, with little degradation in optical quality at 650 nm. Furthermore, as shown in Table 3, which gives the parameters of a multi-stage (m=3) prism-enhanced and standard diffractive lens, chromatic aberration is minimal at wavelengths outside the design wavelength.

[0087] Table 3

[0088]

[0089] Further modifications to the prism portions (such as shape, width, height, and material) can provide further improvements to the optical properties with respect to wavelength and chromatic aberration.

[0090] Making Prism-Enhanced Lenses

[0091] The surface relief structures disclosed herein can be formed from any suitable material using any suitable technique. Suitable materials include, but are not limited to, high index adhesives, MR-10 polymers, polycarbonate, polypropylene, poly(methyl methacrylate) (PMMA), acrylonitrile butadiene styrene (ABS) plastics, and amorphous polyethylene terephthalate (A-PET). These materials can be molded, etched, embossed, or otherwise processed to form components for prismatically enhanced diffractive lenses. For example, they can be molded according to the techniques disclosed in International Application No. PCT / US2016 / 012121, entitled “Methods and Systems for Mold Releases,” which is incorporated herein by reference.

[0092] Furthermore, the present invention is not limited in scope to homeotropically aligned nematic liquid crystals, and other alignment methods of liquid crystals or other liquid crystal phases or other alignment methods of liquid crystals may be used, such as planar alignment, twisted nematic (TN), hybrid aligned nematic (HN), chiral nematic, blue phase, dark conglomerate phase, polymer dispersion, and smectic C* phase liquid crystals, as examples. Similar optical properties may be achieved by matching or mismatching the surface relief structure with the liquid crystal material.

[0093] in conclusion

[0094] Although various inventive embodiments have been described and illustrated herein, a person of ordinary skill in the art will readily recognize a variety of other means and / or structures for performing the functions described herein and / or obtaining the results and / or one or more advantages, and each of such variations and / or modifications is considered to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are intended to be exemplary, and that actual parameters, dimensions, materials, and / or configurations will depend on the specific application or applications for which the inventive teachings are used. Those skilled in the art will recognize or be able to determine, using only routine experimentation, many equivalents to the specific inventive embodiments described herein. Therefore, it should be understood that the foregoing embodiments are given by way of example only, and that within the scope of the appended claims and their equivalents, inventive embodiments may be implemented in a manner other than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and / or methods is included within the inventive scope of the present disclosure, provided such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent.

[0095] The above-described embodiments may be implemented in any of a variety of ways. For example, the design and implementation of the embodiments 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 on any suitable processor or set of processors, whether the processor is provided in a single computer or distributed among multiple computers.

[0096] Furthermore, various inventive concepts can be embodied as one or more methods, examples of which have been provided. The actions performed as part of a method can be ordered in any suitable manner. Thus, embodiments can be constructed in which actions are performed in an order different from that shown, which can include performing some actions simultaneously, even though shown as sequential actions in an illustrative embodiment.

[0097] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0098] Unless explicitly indicated to the contrary, the indefinite articles "a" and "an" as used in the specification and claims herein should be understood to mean "at least one."

[0099] The phrase "and / or" as used in the specification and claims herein should be understood to mean "either or both" of the elements so connected (i.e., elements that exist jointly in some cases and separately in other cases). Multiple elements listed using "and / or" should be interpreted in the same manner, i.e., "one or more" of the elements so connected. Other elements other than the elements specifically identified by the "and / or" clause may optionally be present, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, when "A and / or B" is used in conjunction with open language such as "comprising", reference to "A and / or B" may refer to only A (optionally including elements other than B) in one embodiment; to only B (optionally including elements other than A) in another embodiment; to both A and B (optionally including other elements) in yet another embodiment; and so on.

[0100] As used in this specification and in the claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating the items in a list, "or" or "and / or" should be interpreted as inclusive, that is, including at least one of a plurality of elements or a list of elements, but also including more than one, and optionally including other unlisted items. Only the terms clearly indicate the opposite, such as "only one of them" or "just one of them", otherwise "consisting of..." will refer to including just one element in a plurality of elements or a list of elements when used in the claims. Generally, the term "or" as used herein should be interpreted as indicating exclusive substitution (that is, "one or the other but not both") only when there is an exclusive term (such as "any one", "one of them", "only one of them" or "just one of them") in front. "Substantially consisting of..." should have the ordinary meaning as used in the field of patent law when used in the claims.

[0101] As used herein in the specification and claims, the phrase "at least one" when referring to a list of one or more elements should be understood to mean 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 each element specifically listed in the list of elements, and does not exclude any combination of elements in the list of elements. This definition also allows for the optional presence of elements other than the specifically identified elements to which the phrase "at least one" refers within the list of elements, whether related or unrelated to those specifically identified elements. Thus, as a 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, in one embodiment, mean at least one A, optionally including more than one A, but no B present (and optionally including elements other than B); in another embodiment, mean at least one B present, optionally including more than one B, but no A present (and optionally including elements other than A); in yet another embodiment, mean at least one A, optionally including more than one A, and at least one B, optionally including more than one B (and optionally including other elements); and so on.

[0102] In the claims and foregoing description, all transitional phrases such as "comprising," "carrying," "having," "including," "involving," "maintaining," "consisting of," and the like are to be construed as open-ended, i.e., meaning including, but not limited to, "consisting of." Only the transitional phrases "consisting of" and "consisting essentially of" shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures Section 2111.03.

Claims

1. An electro-active lens comprising: a first substrate; a second substrate; a liquid crystal material disposed between the first substrate and the second substrate; as well as A surface relief structure is formed in the first substrate opposite to the second substrate, wherein the surface relief structure defines a diffraction lens having a plurality of phase-wrap regions and at least one prism structure arranged between a pair of phase-wrap regions among the plurality of phase-wrap regions to mitigate the reduction in diffraction efficiency at wavelengths above and below the design wavelength of the diffraction lens.

2. The electro-active lens of claim 1, wherein: The distance between the mth phase wrapping region in the plurality of phase wrapping regions and the center of the diffractive lens is at least r m =√2mfλ0, Wherein, m is an integer greater than 1, f is the focal length of the diffractive lens, and λ0 is the design wavelength of the electro-active lens.

3. The electro-active lens of claim 2, wherein: The at least one prism structure includes m-1 prism structures, the m-1 prism structures have a total width w, and an inner radius of the mth phase-warping region among the plurality of phase-warping regions is equal to r m and w.

4. The electro-active lens of claim 1 , wherein: The at least one prismatic structure includes a ring-shaped prismatic structure concentric with the pair of phase-wrap regions.

5. The electro-active lens of claim 1 , wherein: The at least one prismatic structure includes a ring-shaped prismatic structure between each pair of phase-wrap regions in the plurality of phase-wrap regions.

6. The electro-active lens of claim 1 , wherein: The at least one prismatic structure partially overlaps one of the pair of phase-wrap regions.

7. The electro-active lens of claim 1 , wherein: The at least one prismatic structure defines a plurality of peaks.

8. The electro-active lens of claim 1 , wherein: The at least one prismatic structure has a curved surface.

9. The electro-active lens of claim 1 , wherein: The at least one prismatic structure has a height of 0.1 micrometers to 50 micrometers and a width of 5 micrometers to 200 micrometers.

10. The electro-active lens of claim 1, wherein: The electro-active lens has a Strehl ratio greater than 0.85 at a wavelength of 550 nm.

11. The electro-active lens of claim 10, wherein: The electro-active lens has a Strehl ratio greater than 0.60 at a wavelength of 450 nm.

12. The electro-active lens of claim 11, wherein: The electro-active lens has a Strehl ratio greater than 0.70 at a wavelength of 450 nm.

13. The electro-active lens of claim 1 , wherein: The electro-active lens has a Strehl ratio greater than 0.65 over a wavelength range of 450 nm to 650 nm.

14. The electro-active lens of claim 1 , wherein: The electro-active lens has a Strehl ratio greater than 0.80 over a wavelength range of 450 nm to 650 nm.

15. The electro-active lens of claim 1 , wherein: The liquid crystal material is capable of changing the focal length of the electro-active lens in response to an applied voltage.

16. The electro-active lens of claim 1, wherein: The electro-active lens forms at least a portion of a lens system of at least one of spectacles, contact lenses, intraocular lenses, or another ophthalmic lens.

17. An electro-active lens comprising: a first substrate; a second substrate; a liquid crystal material disposed between the first substrate and the second substrate; as well as A surface undulation structure is formed in the first substrate opposite to the second substrate, wherein the surface undulation structure defines a diffraction lens having a plurality of phase-wrap regions and at least one prism structure arranged between a pair of phase-wrap regions among the plurality of phase-wrap regions to reduce a change in the Strehl ratio of the diffraction lens over a wavelength range of 450 nm to 650 nm.

18. The electro-active lens of claim 17, wherein: The electro-active lens has a Strehl ratio greater than 0.85 at a wavelength of 550 nm.

19. The electro-active lens of claim 18, wherein: The electro-active lens has a Strehl ratio greater than 0.60 at a wavelength of 450 nm.

20. The electro-active lens of claim 19, wherein: The electro-active lens has a Strehl ratio greater than 0.70 at a wavelength of 450 nm.

21. The electro-active lens of claim 17, wherein: The electro-active lens has a Strehl ratio greater than 0.65 over a wavelength range of 450 nm to 650 nm.

22. The electro-active lens of claim 17, wherein: The electro-active lens has a Strehl ratio greater than 0.80 over a wavelength range of 450 nm to 650 nm.

23. An electro-active lens comprising: a first substrate; a second substrate; a liquid crystal material disposed between the first substrate and the second substrate; as well as A single surface relief structure is formed on the first surface of the first substrate, the first surface of the first substrate facing the second substrate, and the single surface relief structure defines a diffraction lens having multiple phase-wrap regions and at least one prism structure arranged between a pair of phase-wrap regions among the multiple phase-wrap regions to reduce the chromatic aberration of the diffraction lens at wavelengths above and below the design wavelength of the diffraction lens.

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