Note: Descriptions are shown in the official language in which they were submitted.
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EYE WEAR AND METHODS FOR MAKING EYEWEAR
FIELD OF THE DISCLOSURE
[0001] The present disclosure relates to eyewear including spectacles
and the like. More particularly, the present disclosure relates to eyewear
including one or more metalenses.
BACKGROUND
[0002] Conventional eyewear devices such as spectacles include one
or more refractive eyewear lenses made of plastic or glass. The term
"refractive lens" herein refers to lenses that focus or disperse light beams
by
means of refraction caused by the curvature and/or relative angles of
surfaces of the lens. For example, concave and/or convex surfaces may be
used for focusing or dispersing light
[0003] The shape, size and weight of refractive lenses in conventional
eyewear may be dictated or limited by the optical requirements of the lens.
For example, the thickness of lenses in eyewear is typically related to the
optical strength of the lenses. Such refractive lenses may pose a variety of
difficulties for conventional eyewear. For example, refractive lenses may be
bulky, heavy less visually appealing and/or less comfortable for a user.
SUMMARY
[0004] According to an aspect, there is provided an eyewear device
comprising: an eyewear frame; at least one eyewear lens held by the
eyewear frame, each at least one eyewear lens comprising: a respective
substantially transparent lens body; and a respective metalens integrated
with the lens body, wherein the metalens comprises a substantially
transparent substrate and a plurality of subwavelength structures arranged
on the substrate in a pattern to interact with visible light.
[0005] According to another aspect, there is provided an eyewear lens
comprising: a substantially transparent lens body; and a metalens integrated
with the lens body, wherein the metalens comprises a substantially
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transparent substrate and a plurality of subwavelength structures arranged
on the substrate in a pattern to interact with visible light.
[0006] According to another aspect, there is provided a method for
making an eyewear device comprising: providing at least one eyewear lens
comprising a substantially transparent lens body and a metalens integrated
with the lens body, the metalens comprising a substantially transparent
substrate and a plurality of subwavelength structures arranged on the
substrate in a pattern to interact with visible light; providing an eyewear
frame; and mounting the at least one eyewear lens in the eyewear frame.
[0007] In some embodiments, the eyewear device comprises
spectacles.
[0008] In some embodiments, the subwavelength structures comprise
one of a dielectric material and a metal.
[0009] In some embodiments, for each said eyewear lens, the
respective lens body comprises one of: plastic, polycarbonate, high-
refractive-index polymer, and glass.
[0010] In some embodiments, the subwavelength structures comprise
nanopillars.
[0011] In some embodiments, for each said eyewear lens, the
respective metalens is embedded within the lens body.
[0012] In some embodiments, for each said eyewear lens, the
respective lens body comprises a front and a rear surface, and the metalens
is arranged on one of: the front surface and the rear surface.
[0013] In some embodiments, for each said eyewear lens, the
respective substrate of the metalens is adhered to the lens body.
[0014] In some embodiments, the substrate comprises one of: a
polymer and glass.
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[0015] In some embodiments, the subwavelength structures of the
metalens are arranged directly on the lens body, the lens body forming the
substrate of the metalens.
[0016] In some embodiments, the metalens of each said at least one
eyewear lens is configured to correct an eyesight condition.
[0017] In some embodiments, the lens body is a planar body.
[0018] In some embodiments, for each said at least one eyewear lens,
the respective metalens comprises a plurality of metalens regions, each of
the plurality of metalens regions having a respective focusing strength.
[0019] Other aspects and features of the present disclosure will
become apparent to those ordinarily skilled in the art upon review of the
following description of the specific embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Aspects and embodiments of the disclosure will now be
described in greater detail with reference to the accompanying diagrams, in
which:
[0021] Figure 1 is a front view of an example metalens according to
some embodiments;
[0022] Figure 2 is a front view of the metalens of Figure 1;
[0023] Figure 3 is an enlarged perspective partial view of an example
array of nanofins of a metalens;
[0024] Figure 4 is a front perspective view of an example eyewear
device according to some embodiments;
[0025] Figure 5 is a side cross-sectional view of an eyewear lens
according to some embodiments;
[0026] Figure 6 is a side cross-sectional view of another eyewear lens
according to some embodiments;
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[0027] Figure 7 is a side cross-sectional view of yet another eyewear
lens according to some embodiments;
[0028] Figure 8 is a front view of an eyewear lens having multiple
metalens regions according to some embodiments; and
[0029] Figure 9 is a flowchart of a method for making a metalens for
an eyewear device using an electron beam lithography (EBL) process
according to some embodiments;
[0030] Figure 10 is a flowchart of a method for making eyewear
according to some embodiments; and
[0031] Figure 11 is a front view of an example eyewear device
according to another embodiment.
DETAILED DESCRIPTION
[0032] As mentioned above, the shape and thickness of conventional
eyewear lenses may be limited or dictated by the optical requirements of the
lenses. Thick eyewear lenses may be bulky, heavy, and/or uncomfortable
for a wearer of the eyewear. Thus, it may be desirable to reduce the
required thickness and weight of eyewear lenses. Furthermore, frames for
conventional eyewear may need to be designed to accommodate refractive
lenses of a variety of different thicknesses and/or curvatures because such
features of the lens may vary depending on the strength and type of
correction provided by the lenses.
[0033] According to an aspect, there is provided an eyewear device
comprising at least one an eyewear lens held in an eyewear frame to be
worn by a user. The at least one eyewear lens comprises a respective lens
body and at least one respective metalens integrated with the lens body.
The metalens may also be referred to as a metasurface, metalens zone, etc.
According to another aspect, there is provided an eyewear lens having at
least one metalens. According to another aspect, there is provided a method
of making eyewear as described herein.
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[0034] The eyewear device may be a pair of spectacles, glasses, a
monocle, or any other similar eyewear in which an eyewear lens is held in a
position within a user's line of sight when worn. The eyewear device may be
for correcting an eye condition. Eyewear (e.g. spectacles) comprising at least
one metalens carried in or on a lens body may be planar, thin and much
lighter than conventional eyewear having refractive lenses. The lens body
may comprise CR39, polycarbonate or other higher index materials, for
example.
[0035] A "metalens" is a lens including an array of structures on a
substrate that interact with electromagnetic radiation. Specifically, the
structures have dimensions that are less than the wavelength(s) of the
radiation and are arranged in a pattern which alters an incoming wavefront in
a non-refractive, non-diffractive manner by virtue of the composition, shape,
orientation, height and diameter of the structures. Structures having such
dimensions are referred to herein as "subwavelength structures". To interact
with electromagnetic radiation in the visible spectrum (i.e. visible light),
the
subwavelength structures have dimensions such as height, width and/or
spacing in the nanometer range. Thus, such structures may be referred to
as nanostructures. Nanostructures may be in the form of nanopillars (e.g.
nanofins) which act as sub-wavelength light phase shifters to focus or
disperse light. The term "nanopillar" refers to any structure with one or more
subwavelength dimensions (height, width, thickness) that extends away from
the substrate. The term "nanofin" refers to a nanopillar with a generally fin-
like shape. For example, nanofins may have a generally rectangular prism-
like shape as shown in Figure 3. A metalens may also be referred to as a
"planar lens". A substrate with subwavelength structures thereon may be
referred to as a "metasurface". Metalenses have been proposed for use in
various electronic devices such as cameras, for example.
[0036] The metalens-based eyewear lenses described herein may be
thinner than conventional devices. Reducing the thickness of lenses in
eyewear may be advantageous. The use of metalenses in eyewear such as
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spectacles may allow for smaller, lighter lenses, which may improve the
comfort and customizability of eyewear.
[0037] Figure 1 is a front view of an example metalens 100. The
metalens 100 comprises a substrate 106 with an array of subwavelength
structures 108 distributed thereon. The subwavelength structures 108 are
arranged on the substrate in a pattern to interact with visible light. The
subwavelength structures 108 in this example are nanofins (e.g. thin
rectangular-prism-shaped extensions).
[0038] As will be apparent to a person skilled in the art, the size and
number of the subwavelength structures 108 are not shown to scale. The
subwavelength structures 108 as shown in Figure 1 are substantially
enlarged and reduced in number for illustrative purposes. For example, the
diameter of the metalens 100 shown in Figure 1 may be a few centimeters
(although metalenses used in eyewear according to the disclosure are not
limited to a particular size) and subwavelength structures 108 may have
dimensions in the range of 10's to 100's of nanometers. Furthermore, a
metalens will typically include orders of magnitude more subwavelength
structures than are shown in Figure 1 (possibly on the order of one million
nanostructures per square millimeter or more).
[0039] The arrangement of subwavelength structures 108 shown in
Figure 1 is also shown to illustrate that the subwavelength structures 108
may be arranged in a pattern with various tilt angles relative to one another.
Embodiments of this disclosure are not limited to any particular pattern or
arrangement of subwavelength structures of a metalens, including the
pattern shown in Figure 1.
[0040] The metalens 100 in Figure 1 is planar disc-shaped (although
the shape may vary in other embodiments. The subwavelength structures
108 are arranged in a pattern that extends radially about a center axis 124
(shown in Figure 2) of the metalens 100 for an iris-like distribution. The
metalens in this example defines a circular center area 112 that does not
include the subwavelength structures. The subwavelength structures 108 are
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not included in the center area 112 in this example because axial and
paraxial rays passing therethrough may not require an alteration of the
wavefront to focus. The size of the center area may vary. In other
embodiments, the center area 112 may be larger or smaller or omitted. In
other words, the metalens 100 may alternatively include subwavelength
structures 108 in the region occupied by the center area 112 in Figure 1.
[0041] Each subwavelength structure 108 may have height, width
and/or thickness in the range of lOs to 100s of nanometers. A nanof in-type
subwavelength structure may be generally rectangular prism-shaped. For
example, a nanofin sized to have a peak response at the wavelength of
green light (532nm) may be 600nm high by 250nm wide by 95 nm thick
(although embodiments are not limited to these particular dimensions). The
nanof ins may, for example, be spaced approximately 600 nm apart. The
nanof ins (or other subwavelength structures) may be arranged radially about
the center axis 124 (Figure 2) at various tilt angles relative to the radial
direction. The separation between the structures 108 may similarly be in the
range of nanometers.
[0042] The thickness of the metalens 100 may be on the order of
microns, depending on the thickness of the substrate 106.
[0043] Figure 2 is a side view of the metalens 100 of Figure 1. Again,
for illustrative purposes, the subwavelength structures 108 of the metalens
100 are not shown to scale. The substrate 106 in this example is flat, but
may have posterior convexity or other curvature in other embodiments.
[0044] The center axis 124 is shown in Figure 2. The metalens 100
extends radially about the center axis.
[0045] Figure 3 is an enlarged perspective partial view of an example
array 300 of nanof ins 302 of a metalens. The array 300 is only partially
shown and extends beyond the stippled line border of Figure 3. Similar
nanofin arrays are shown by M. Khorasaninejad et al. "Super-Dispersive Off-
Axis Meta-Lenses for Compact High Resolution Spectroscopy" Nano Lett.
2016, 16, 3732-3737, the entire content of which is incorporated by
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reference. The nanof ins 302 are generally rectangular-prism-shaped
extensions from a substrate (not visible). The subwavelength structures 108
of the metalens 100 shown in Figure 1 may be in a form similar to the
nanof ins 302 shown in Figure 3. For example, the array 300 may be
representative of a small portion of the metalens 100 in Figures 1 and 2.
However, embodiments are not limited to the particular arrangement of
nanof ins shown in Figure 3. The specific arrangement/pattern of the
subwavelength structures may vary and is dependent upon the desired
output characteristic (e.g. focus strength) of the lens. Embodiments are not
limited to any particular configuration of the subwavelength structures.
[0046] The dimensions of the subwavelength structures may allow a
metalens to be much thinner than a refractive lens. A metalens may, thus,
be referred to as "nano-thin" or "ultrathin".
[0047] Some metalenses have been designed to function in the visible
spectrum only at a particular wavelength or in a very narrow wavelength
range. Some existing metalenses that interact with visible light include metal
or dielectric nanostructures. Example metalens structures including TiO2
nanostructures to interact with visible light over a range in the visible
spectrum are described by Mohammadreza Khorasaninejad, et al., in
"Visible Wavelength Planar Metalenses Based on Titanium Dioxide, IEEE
Journal of Selected Topics in Quantum Electronics, Vol. 23, No. 3, May/June
2017, which is incorporated by reference herein in its entirety. Example
TiO2-based metalenses are also described by Byrnes et al. in U.S. Patent
Application Publication No. 2017/082263, which is incorporated by reference
herein in its entirety.
[0048] The metalenses described herein may be configured to interact
with visible light having wavelength in the range of 380 to 660 nm.
Mohammadreza Khorasaninejad, et al. show results for TiO2 metalenses at
wavelengths of 660nm, 532nm and 405nm and state that the operating
bandwidth of such metalenses may be expanded by dispersion engineering
to a multi-wavelength regime and potentially for a continuous wavelength
range. See also F. Aieta, M.A. Kats, P. Genevet, and F. Capasso,
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"Multiwavelength Achromatic Metasurfaces by Dispersive Phase
Compensation", Science, vol. 347, pp 1342-1345, 2015, which is
incorporated herein by reference in its entirety.
[0049] TiO2 as the material for subwavelength structures may be
beneficial when used in eyewear. TiO2 has been shown to be suitable for
metalenses that function over a broad range of the visible light spectrum.
TiO2 is also biocompatible and bioinert and has been used in various types
of biomedical devices. TiO2 may have negligible optical absorption in the
visible spectrum. Other potential benefits of TiO2 include its high index of
refraction (close to diamond), high melting point, and antimicrobial
properties. See for example, Joseph A. Lemire et al. "Anti microbial Activity
of Metals: Mechanisms, Molecular Targets and Applications" Nature Reviews
Microbiology, Vol. II, No. 6, pages 371-384; June 13, 2013, the entirety of
which is incorporated by reference. TiO2, when deposited, may be strongly
adherent to the substrate and chemically impermeable. However,
embodiments are not limited to TiO2 subwavelength structures. Some
additional dielectric materials that may be used for subwavelength structures
include, but are not limited to, quartz, Gallium Nitride (GaN), and silicon
nitride. Other materials such as metal may be suitable for subwavelength
structures in the eyewear lenses.
[0050] TiO2 also has a high index of refraction (approximately 2.37 for
550 nm wavelength light), and metalenses using this dielectric may have
high conversion efficiency. The term "conversion efficiency" herein refers to
the amount of visible light entering the system when compared to the amount
in the final focal point. Losses may occur from reflection, scattering,
absorption, diffraction, etc. Mohammadreza Khorasaninejad, et al.
referenced above disclose up to 86% actualized and 95% simulated
conversion efficiency for TiO2 metalenses. Such metalenses may also have
a high numerical aperture (NA) (e.g. NA = 0.8) and may be capable of
focusing light into diffraction limited spots 1.5X smaller than commercial
100X objective lenses, such as the NikonTm CFI 60. Furthermore, TiO2 may
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be deposited on certain materials, atomic layer by layer by existing chip
manufacturing technology.
[0051] The substrate of the metalens in embodiments described
herein may be any suitable substantially light-transmissive or transparent
material. Some specific examples of substrate material include, but are not
limited to, substantially transparent polymer such as silicone, acrylic, High
Refractive Index Polymer (H RIP) nano-composite material, and glass. The
H RIP may be an organic matrix with high refractive inorganic nanoparticles
combined to create a substrate. In some embodiments, the substrate may
have a chromophore or coating to filter ultraviolet (UV) light to protect the
eye from UV exposure.
[0052] The substrate may be substantially rigid in some embodiments.
In other embodiments, the substrate may be a flexible, bendable material
(e.g. silicone, acrylic, or a hydrogel).
[0053] The term "substantially transparent" as used herein does not
require absolute transparency. Rather, for example, a tinted material may be
considered substantially transparent in that it is suitable for use in
eyewear,
spectacles, etc.
[0054] An example of an eyewear device according to an aspect of
the disclosure will now be described with reference to Figure 4. Figure 4 is a
front perspective view of a pair of spectacles 400 according to one
embodiment. However, eyewear embodiments are not limited to the
example spectacles in Figure 4.
[0055] The spectacles 400 include a first eyewear lens 401a, a
second eyewear lens 401b, and a frame 402. The eyewear lenses 401a and
401b are held in the frame 402 in a manner similar to conventional
spectacles.
[0056] The example frame 402 has a structure similar to conventional
frames and includes temple/earpiece portions 403a and 403b connected by
hinge means (not shown) to rims 404a and 404b. The rims 404a and 404b
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are connected by bridge 405 of the frame 402. The lenses 401a and 401b
are secured in the rims 404a and 404b. The frame 402 is configured such
that, when worn, the lenses 401a and 401b are positioned in front of the
user's eyes to be in their line of sight.
[0057] It is to be appreciated that eyewear in other embodiments will
have different frame and lens configurations, and the spectacles 400 in
Figure 4 are shown by way of non-limiting example. The shape, size and
configuration of eyewear frames and lenses may vary, while still positioning
the lenses in the line of sight.
[0058] The first eyewear lens 401a includes a lens body 406a and a
metalens 408a integrated with the lens body 406a. The second eyewear
lens 401b similarly includes a second lens body 406b and second metalens
408b integrated with the second lens body. In this example, the second
eyewear lens 401b has the same structure as the first eyewear lens 401a.
However, in other embodiments, each eyewear lens may have different
structures and/or configurations.
[0059] In Figure 4, stippled shading is used to illustrate the general
position and layout of the metalenses 408a and 408b and is not meant to
represent a reduction in light transmittivity. The metalenses 408a and 408b
may be highly light transmissive and may be substantially transparent. The
size of the metalenses 408a and 408b may vary. For example, the
metalenses 408a and 408b may cover a smaller or larger area than shown
or may occupy substantially the same area as the lens bodies 406a and
406b.
[0060] In this embodiment, the lens bodies 406a and 406b are flat
circular disc-shaped bodies. More particularly, the lens bodies 406a and
406b in this example are each a pane or plate of light transmissive material.
The lens bodies 406a are planar in this embodiment, with generally parallel
front and rear surfaces separated by relatively small thickness. However,
embodiments are not limited to planar configurations. For example, the lens
body in other embodiments may have a somewhat curved front and rear
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surfaces (e.g. convex or concave) in other embodiments. Eyewear lenses
described herein are also not limited to circular, disc-like shapes. Other
shapes, (e.g. rectangular, oblong, etc.) are also possible.
[0061] The term "lens body" herein does not mean that the body itself
focuses or otherwise performs traditional corrective lens functions. Rather,
these lensing functions are performed by the metalenses 408a and 408b,
while the lens bodies 406a and 406b serve to secure the metalenses 408a
and 408b and may improve handling of the eyewear lenses 401a and 401b.
For example, the lens body 406a may also provide protection for the
metalens 408a and/or allow for easier mounting of the eyewear lenses 401a
and 401b in the frame 402.
[0062] The lens bodies 406a and 406b may be any substantially
transparent material suitable for carrying the metalenses 408a and 408b.
Example materials for the lens bodies 406a and 406b include, but are not
limited to, plastic (e.g. CR39 plastic), polycarbonate, glass and high-
refractive-index polymer (H RIP). Traditional spectacles are made of CR39
plastic, polycarbonate or other high index materials. While CR39 plastic is
commonly used in conventional eyewear, polycarbonate may be more
impact resistant and is commonly used for safety applications. High index
lenses may typically be relatively thin, light and have a good appearance
compared to lower index materials. Embodiments are not limited to a
particular material composition or index value of the lens bodies described
herein.
[0063] The metalenses 408a and 408b each comprise a distribution of
subwavelength structures on a substrate, with the subwavelength structures
arranged to interact with visible light. The metalenses 408a and 408b may,
for example, have structure and function similar to the subwavelength
structures of the metalens 100 in Figures 1 and 2. The subwavelength
structures of the metalenses 408a and 408b may, for example, be shaped
and/or arranged similar to the nanof ins 302 shown in Figure 3, although
embodiments are not limited to any particular shape, size or arrangement of
the subwavelength structures.
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[0064] The method by which the metalenses 408a and 408b are
integrated with the respective lens bodies 406a and 406b may vary. The
metalenses 408a and 408b may be attached (e.g. adhered or bonded) to the
front or rear surface of the corresponding lens bodies 406a and 406b.
Alternatively, the metalenses 408a and 408b may be embedded within the
corresponding lens bodies 406a and 406b (e.g. between and substantially
parallel to the front and rear surfaces of the lens bodies 406a and 406b). As
yet another option, the subwavelength structures of the metalenses 408a
and 408b may be deposited directly on the corresponding lens bodies 406a
and 406b (with the lens bodies 406a and 406b thereby forming the substrate
for the subwavelength structures). Any suitable method for the lens bodies
406a and 406b to hold the metalenses 408a and 408b may be used. Other
arrangements are also possible. Some example structures of eyewear
lenses showing details of how the metalenses 408a and 408b are integrated
with the lens bodies 406a and 406b are shown in Figures 5 to 7 and
described below.
[0065] The metalenses 408a and 408b may be configured to correct
an eye condition including, but not limited to, near or far-sightedness and/or
vertical or horizontal dysphoria (via prismatic correction). The shape,
dimensions, and/or arrangement of the subwavelength structures may be
designed based on eyesight tests and computer software (e.g. Lumericalim
simulation software).
[0066] The subwavelength structures of the metalenses 408a and
408b may comprise any material suitable for fabricating subwavelength
structures to interact with visible light. For example, the subwavelength
structures may be a dielectric such as TiO2. However, the subwavelength
structures may also be a non-dielectric material such as metal. The
subwavelength dielectric structures may be nanopillars arranged to function
over a range of wavelengths.
[0067] The substrate for the metalens of an eyewear lens may be any
substantially light transmissive material capable of having subwavelength
structures formed thereon. The substrate may be substantially rigid or
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flexible. The selection of the particular materials for the eyewear device may
be based on optical performance and manufacturing considerations.
[0068] Optionally, each lens 401a and 401b includes a center area
410a and 410b that does not include subwavelength structures, similar to the
metalens 100 of Figures 1 and 2. Central axial and par-axial rays passing
through the center areas 410a and 410b may not require interaction by the
lenses 401a and 401b.
[0069] The eyewear lenses 401a and 401b may have a reduced
weight, thickness and/or curvature compared to conventional refractive
lenses for spectacles.
[0070] The metalenses 408a and 408b may include multiple regions
or zones, with each region having a respective distribution of subwavelength
structures. The subwavelength structures in one region may have one or
more dimensions and/or distribution patterns that differ from one or more
other regions. Embodiments are not limited to a particular pattern,
dimension, or distribution of the subwavelength structures.
[0071] To determine a desired layout of the subwavelength structures
of the metalenses described herein, in order to treat an eye condition,
eyesight testing or other measurements may be performed. A dioptric
strength of the metalens(s) may be calculated based on the testing.
.Computer software may then be used to determine the dimensions and
arrangement of the subwavelength structures based on the requirements
obtained as a function of the eye measurement process. One example of
suitable software is LumericalTm simulation software. The software may, for
example, define the subwavelength pattern/arrangement to achieve the focal
point to the refractive equivalent dioptric strength. This may be equivalent
to
traditional convex, concave, astigmatic (toric) or multifocal configurations.
However, the variable in lens configuration is not curvature (as for
refractive
lenses) but rather the height, width, tilt and separation of the subwavelength
structures to achieve the same focus. A metalens with the particular
configuration determined by the LumericalTm computer simulation software
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may then be fabricated. Again, it is to be understood that embodiments are
not limited to any particular arrangement or pattern of subwavelength
structures, or to any method of determining the particular arrangement or
pattern.
[0072] The lenses 401a and 401b of the spectacles 400 may also
include various other features not shown including, but not limited to,
ultraviolet (UV) protection, blue filters, antireflection coatings, etc. In
some
embodiments, the metalens-based eyewear lenses described herein may not
have designated front and back surfaces and may be reversible.
[0073] Metalenses may be more efficient and have a higher numerical
aperture than flat lenses made with diffractive optics because the wavelength
scale ring structure of diffractive optics may degrade the phase profile of
incident light. The sub-wavelength scale of nanofin phase disrupters of some
metalenses have been shown to achieve excellent diffraction limited focus.
[0074] Embodiments are not limited to the size, shape, or
arrangement of the metalenses 408a and 408b shown in Figure 4. In some
embodiments, one or more eyewear lenses may each comprise a plurality of
metalenses regions or zones, with each region or zone having a different
light focusing characteristic, similar to bifocal or trifocal refractive
lenses.
[0075] Example eyewear lenses will now be described with respect to
Figures 5 to 8. Such eyewear lenses may, for example, be used to correct a
variety of eyesight conditions including, but not limited to near-sightedness,
far-sightedness, and vertical or horizontal dysphoria (via prismatic
correction).
[0076] Figure 5 is a side cross-sectional view of an example eyewear
lens 500 according to some embodiments. The eyewear lens 500 may be
used in eyewear such as the spectacles 400 shown in Figure 4. The
eyewear lens 500 comprises a planar lens body 502 and a metalens 504.
The metalens 504 comprises a substrate 506 and a plurality of
subwavelength structures 508 distributed on the substrate 506 in an
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arrangement to interact with visible light. The lens body 502 may stabilize
the subwavelength structures 508 suspended therein.
[0077] The thickness of the substrate 506 and the size of the
individual subwavelength structures 508 are shown enlarged for illustrative
purposes and are not shown to scale. As described above, subwavelength
structures in metalenses typically have dimensions on the order of
nanometers, and a metalens may have millions of subwavelength structures
per square millimeter. Similar structural details in the embodiments of
Figures 6 and 7 are also shown enlarged and not to scale.
[0078] In Figure 5, the metalens 504 is embedded within the planar
lens body 502. The metalens 504 may be fabricated using a process similar
to the method of Figure 9, for example. The metalens 504 may be embedded
by a molding process or any other suitable means. The metalens 504 may
be embedded to be substantially parallel with the front and/or back surfaces
of the planar lens body 502.
[0079] Figure 6 is a side cross-sectional view of another example
eyewear lens 600 according to some embodiments. The eyewear lens 600
may be used in eyewear such as the spectacles 400 shown in Figure 4. The
eyewear lens 600 comprises a planar lens body 602 and a metalens 604.
The metalens 604 comprises a substrate 606 and a plurality of
subwavelength structures 608 distributed on the substrate 606 in an
arrangement to interact with visible light. The metalens 604 may be
fabricated using a process similar to the method of Figure 9, for example.
[0080] In Figure 6, the metalens 604 is adhered or otherwise attached
to the front surface 610 of the planar lens body 602. By way of example, an
adhesive may be applied to either the substrate 606 or the front surface 610
in order to attach the metalens 604 to the planar lens body 602. In other
embodiments, the metalens may be attached to the rear surface 612 of the
planar lens body 602.
[0081] In some embodiments, the metalens 604 may be
removable/replaceable. Thus, the same lens body 602 may be customized
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for various eye conditions by the desired type of metalens 604 attached
thereto.
[0082] Figure 7 is a side cross-sectional view of yet another example
eyewear lens 700 according to some embodiments. The eyewear lens 700
may be used in eyewear such as the spectacles 400 shown in Figure 4. The
eyewear lens 700 comprises a planar lens body 702 and a metalens 704. In
this example, the planar lens body 702 is the substrate for the metalens 704.
A plurality of subwavelength structures 708 are distributed directly on the
front surface 710 (or alternately the rear surface 712) of the planar lens
body
702 in an arrangement to interact with visible light. The metalens 704 may
be fabricated on the planar lens body 702 using a process similar to the
method of Figure 9, for example.
[0083] In Figure 7, the eyewear lens 700 also includes an optional
substantially transparent protective layer or coating 714 over the
subwavelength structures. The particular type of protective layer or coating
714 may be chosen to minimally interfere with the focusing of the metalens
704. The metalens 704 may be designed to account for the protective layer
or coating 714. A similar coating may be included on other lenses described
herein, including the lenses 500 and 600 of Figures 5 and 6. The eyewear
lenses described herein may also comprise other types of coatings including,
but not limited to, anti-reflective, polarizing, impact resistance, tint, UV
protection, etc.
[0084] Figure 8 is a front view of a multi-focal eyewear lens 800
according to another embodiment. The eyewear lens 800 comprises a lens
body 802 and a metalens 804 integrated therewith. The metalens 804 may,
for example, be integrated with the body in a manner similar to any of the
lenses 500, 600 and 700 shown in Figures 5 to 7. The metalens 804
comprises a plurality of regions, namely a first region 806a, a second region
806b and a third region 806c. The first region 806a has a first focal
strength.
The second region 806b has a second focal strength. The third region 806c
has a third focal strength. The subwavelength structures in each region have
a configuration for the corresponding focal strength. Similar to a traditional
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tri-focal lens, the first region 806a may be a "distance" region, the second
region 806b may be an "intermediate" region, and the third region 806c may
be a "near" region, although embodiments are not limited to this arrangement
[0085] The first, second and third metalens regions 806a, 806b and
806c may have discrete boundaries or lines of demarcation therebetween.
Alternatively, the focal strength of the metalens 804 may have a
"progressive" configuration where the focal strength changes over a gradient
between the regions.
[0086] The first, second and third metalens regions 806a, 806b and
806c are shown having different sizes, although they may have the same
size in other embodiments. The number of metalens regions or zones per
eyewear lens may also vary. In some embodiments, an eyewear lens may
include two or more than three different metalens regions, each having
different optical characteristics. The size, position and optical
characteristics
of each metalens region in a multi-region eyewear lens may vary.
[0087] In the example of Figure 8, the three regions 806a, 806b and
806c are formed as a single metalens sharing a single substrate. In other
embodiments, each different focal region of an eyewear lens may be formed
as a separate metalens on a separate substrate.
[0088] In still other embodiments, an eyewear lens may comprise a
metalens that has a variable optical characteristic. For example, rather than
multiple portions with discrete focusing strengths, a single metalens may
have a gradient from one focusing strength to another over its surface area.
For example, the lens may have a first area with a lower focusing power and
then increase focusing power over a gradient into a "reading zone" area of
the lens. In such cases, there may be no discrete lines of demarcation
between the reading zone and the remainder of the metalens. The term
"reading zone" herein refers to an area of the lens through which a user is
expected to look when reading or performing other activities involving looking
at objects relatively near to the eyes.
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[0089] The eyewear lenses described herein, such as lenses 500,
600, 700 and 800 of Figures 5 to 8, are not limited to use in spectacles.
Other forms of eyewear devices that may include similar metalens-based
lenses include, but are not limited to, swimming goggles, scuba masks, etc.
In addition to the typical function of such eyewear (goggles, masks etc.), the
metalenses of the eyewear lenses may be configured to correct one or more
eye conditions without requiring separate spectacles or contact lenses during
use.
[0090] In some embodiments, technology similar to existing silicon
chip manufacturing processes may be used or adapted for creating a
metalens for an eyewear lens. An example electron beam lithography (EBL)
process for fabricating a metalens is described by Mohammadreza
Khorasaninejad, et al. (2017), which is incorporated herein by reference.
[0091] Figure 9 is a flowchart of a method for making a metalens for
eyewear using an EBL process according to some embodiments.
Embodiments are not limited to the particular EBL process described below.
The metalens may also be fabricated using a non-EBL process (e.g. UV
lithography) in other embodiments.
[0092] At block 902, a polymer substrate is coated with a layer of
resist. The resist may, for example, be spin-coated on the substrate. The
resist in this example is an EBL resist such as ZEP 520A resist. The
thickness of the resist layer may determine the height of the nanostructures
to be formed.
[0093] At block 904, the resist is exposed by EBL, defining the pattern
of the nanostructures in the resist. Alternatively, deep ultraviolet (UV)
lithography may be used to pattern the resist. The pattern for the lithography
step may generated using commercially available software (e.g. from
Lumerical Inc.Tm).
[0094] At block 906, the resist is developed in o-xylene (e.g. 99% o-
xylene). This step removes resist according to the lithographed pattern and
leave holes or gaps that correspond to the geometry of the intended
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nanostructures. The remaining resist on the substrate at this stage may be
referred to as "patterned" resist.
[0095] At block 908, TiO2 is deposited onto the patterned resist. The
deposition may be performed by atomic layer deposition (ALD). The TiO2
atomic layer deposition fills the gaps within the patterned resist to form
subwavelength structures of the desired shape, diameter, height, tilt and
spacing. These subwavelength structures or short wavelength structures
(SWS) may be customized to correct eye conditions, such as spherical and
chromatic aberration. By way of example, simulations with Lumerical lnc.'sTM
FDTD (finite difference time domain) solver programs may be used to create
phase profiles for spherical, cylindrical or multifocal platforms, which may
reduce or avoid the need to produce costly prototypes before manufacture.
[0096] The deposition of TiO2 may result in an excess TiO2 layer on
top of the resist. Thus, optionally, at block 610, the excess layer of TiO2
over the resist is etched away.
[0097] At block 912, the remaining resist is stripped. For example, the
stripping may be performed using an overnight Remover-PG bath. The
remaining TiO2 structures on the substrate form the metalens, which may
achieve a refractive outcome that is equivalent or better than a conventional
lens.
[0098] It is to be understood that the method of Figure 9 is provided by
way of example, and embodiments are not limited to this particular method of
making a metalens.
[0099] Figure 10 is a flowchart of an example method for making
eyewear according to another aspect.
[00100] At block 1002, at least one eyewear lens is provided. The at
least one eye wear lens may be similar to any of the eyewear lenses 401a,
401b, 500, 600, 700 and 800 described above and shown in Figures 4 to 8.
More particularly, the eye wear lens includes a substantially transparent and
generally planar lens body and a metalens integrated with the body. The
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metalens comprises a substantially transparent substrate and a plurality of
subwavelength structures arranged on the substrate in a pattern to interact
with visible light. Providing the eyewear lens may comprise making,
purchasing or otherwise obtaining the eyewear lens.
[00101] In some embodiments, making the lens comprises integrating a
metalens with a lens body. Integrating the metalens and the lens body may
comprise attaching the metalens to a front or rear surface of the lens body.
In other embodiments, making the lens comprises embedding the at least
one metalens within the lens body (e.g. by a molding process). In still other
embodiments, making the lens comprises depositing the subwavelength
structures of at least one metalens directly on the lens body.
[00102] At block 1004, an eyewear frame is provided. The frame may
be similar to the eyewear frame 402 shown in Figure 4, for example,
although embodiments are not limited to any particular eyewear frame. Any
eyewear frame suitable for mounting one or more eyewear lenses and being
worn by a user may be used. Providing the eyewear frame may comprise
making, purchasing or otherwise obtaining the eyewear frame.
[00103] At block 1006, the at least one eyewear lens is mounted in the
eyewear frame. The at least one eyewear lens may be mounted using any
suitable method (adhesive, gripping means, friction mounting, etc.). What
has been described is merely illustrative of the application of the principles
of
the disclosure. Other arrangements and methods can be implemented by
those skilled in the art without departing from the scope of the present
disclosure.
[00104] Figure 11 is a front view of an example eyewear device 1100
(spectacles in this case) according to another embodiment. The eyewear
device 1100 includes a frame 1102 and first and second eyewear lenses
1101a and 1101b held by the frame 1105. Temple and ear pieces of the
frame 1102 are not shown. Each of the eyewear lenses 1101a and 1101b
comprises a respective lens body 1104a or 1104b, and a respective
metalens 1106a or 1106b integrated with the corresponding lens body 1104a
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or 1104b. Again, stippled shading is used only to illustrate the general
position and layout of the metalenses 1106a and 1106b. The eyewear
lenses 1101a and 1101b and rims of the frame 1102 are not circular in this
embodiment, but have a non-circular shape similar to some typical
conventional spectacles. The eyewear lenses 1101a and 1101b may be
planar.
[00105] What has been described is merely illustrative of the
application of the principles of the disclosure. Other arrangements and
methods can be implemented by those skilled in the art without departing
from the scope of the present disclosure.
