Corrugated metal layers and optical structures including corrugated metal layers

Abstract

An optical construct includes a lens layer and optically opaque first and second mask layers. The lens layer has a first main surface including a plurality of microlenses arranged along orthogonal first and second directions. The first and second mask layers are spaced apart from the first main surface and define corresponding plurality of first and second through openings arranged along the first and second directions, respectively. The first mask layer is disposed between the structured first main surface and the second mask layer. Each microlens corresponds one-to-one with both the first and second openings. The optical construct includes an intermediate layer disposed between the structured first main surface and the first mask layer, and includes a corrugated second main surface facing and substantially registered with a corrugated third main surface of the first mask layer to define a substantially uniform spacing between the second and third main surfaces.

Description

Background Technology

[0001] Optical elements may include microlenses and pinhole masks having pinholes aligned with the microlenses. Summary of the Invention

[0002] This specification generally relates to corrugated metal layers and optical constructs. The optical construct may include a lens layer and a corrugated metal layer. The display system may include the optical construct near the sensor.

[0003] In some aspects of this specification, an optical construct is provided, comprising a lens layer and spaced-apart, optically opaque first and second mask layers. The lens layer includes a structured first main surface comprising a plurality of microlenses arranged along orthogonal first and second directions. The spaced-apart, optically opaque first and second mask layers are spaced from the first main surface and define corresponding plurality of first and second through-holes arranged along the first and second directions. The first mask layer is disposed between the structured first main surface and the second mask layer. Each microlens corresponds one-to-one with both the first and second through-holes. The optical construct includes an intermediate layer disposed between the structured first main surface and the first mask layer, and includes a corrugated second main surface facing and substantially registered with a corrugated third main surface of the first mask layer to define a substantially uniform spacing between the second and third main surfaces.

[0004] In some aspects of this specification, an optical construct is provided. The optical construct includes: a lens layer comprising a plurality of microlenses arranged along orthogonal first and second directions; an optically opaque first mask layer spaced apart from the plurality of microlenses and defining a plurality of first through-holes arranged along the first and second directions; and a corrugated metal layer having a substantially uniform thickness in the range of about 50 nm to about 500 nm and embedded in the optical construct between the plurality of microlenses and the first mask layer, such that for visible light propagating along thickness directions orthogonal to the first and second directions and incident on the optical construct from the lens layer side, the optical construct reflects less than about 25% of the incident light. There is a one-to-one correspondence between the microlenses and the first through-holes.

[0005] In some aspects of this specification, a metal layer is provided comprising a first main surface with regularly corrugated patterns and an opposite second main surface with regularly corrugated patterns. The regularly corrugated patterns of each of the first and second main surfaces are regularly arranged along at least a first direction at a spacing of less than about 500 nm. The metal layer has an average thickness in the range of about 50 nm to about 500 nm and defines a plurality of through openings arranged along the first direction and an orthogonal second direction.

[0006] In some aspects of this specification, a metal layer is provided comprising a first main surface with regularly corrugated patterns and a second main surface with regularly corrugated patterns of opposite shapes. The regularly corrugated patterns of the first and second main surfaces are substantially registered to each other such that the first and second main surfaces define a substantially uniform spacing therebetween. The regularly corrugated patterns of each of the first and second main surfaces are arranged along at least a first direction at a spacing of less than about 500 nm. The metal layer is optically opaque and defines a plurality of through openings arranged along the first direction and an orthogonal second direction.

[0007] These and other aspects will become apparent from the detailed description that follows. However, in no way should this brief overview be construed as limiting the subject matter for which protection can be claimed. Attached Figure Description

[0008] Figure 1 It is a schematic cross-sectional view of an optical structure according to some implementation schemes.

[0009] Figures 2 to 3 It is a schematic top plan view of the corrugations of each layer or surface of an optical structure or part thereof according to some implementation schemes.

[0010] Figures 4A to 4B It is a schematic top-view projection of multiple microlenses and through-holes according to some implementation schemes.

[0011] Figure 5 It is a schematic diagram of a curled optical structure or part of an optical structure according to some implementation schemes.

[0012] Figure 6 It is a schematic cross-sectional view of a display system based on some implementation schemes.

[0013] Figures 7 to 8 This is an image of an exemplary corrugated metal layer disposed on an intermediate layer. Detailed Implementation

[0014] Reference is made in the following description to the accompanying drawings, which form part of the invention and illustrate various embodiments by way of example. The drawings are not necessarily drawn to scale. It should be understood that other embodiments may be conceived and practiced without departing from the scope or spirit of this specification. Therefore, the following detailed description should not be considered limiting.

[0015] Optical constructs may include microlens arrays and metal masks having an array of through-holes (e.g., pinholes) corresponding to the microlenses. However, it has been found that using metal masks can cause unwanted specular reflections in the mask regions between the through-holes. According to some embodiments of this specification, it has been found that using corrugated metal layers (e.g., having corrugations with a spacing smaller than the wavelength of visible light) instead of flat or substantially planar metal layers can substantially reduce unwanted reflections. The corrugated metal layers can be formed by depositing (e.g., sputtering) metal onto a layer having a corrugated main surface, which is formed by replicating a pattern from a tool (e.g., during casting and curing). In some cases, forming a lens layer on one side of a substrate and a layer with a corrugated main surface on the opposite side of the substrate can lead to unwanted curling in the formed optical construct. However, it has been found that curling can be reduced or substantially eliminated by appropriately selecting the materials and thicknesses of the lens layer and the layer with the corrugated main surface.

[0016] In some implementations, the optical construct can be used as an angle-selective optical filter, applicable to various applications such as fingerprint sensing. The optical construct can be positioned between the fingerprint sensing area of ​​a device (e.g., a mobile phone) and a sensor within the device, and can be adapted to transmit light reflected from a finger in the fingerprint sensing area to the sensor while rejecting light incident on the optical construct from different angles. In addition to a corrugated metal mask layer, a second mask layer can be used to reduce unwanted crosstalk (e.g., in cases where light incident on one microlens is transmitted through an opening corresponding to another microlens).

[0017] Figure 1This is a schematic cross-sectional view of an optical construct 100 according to some embodiments. The optical construct includes a lens layer 110 and layers 120 and 130, which may be mask layers, wherein one of layers 120 and 130 may be referred to as a first mask layer, and the other of layers 120 and 130 may be referred to as a second mask layer. Layers 120 and 130 include through openings 126 and 136, respectively. The through opening in the first mask layer may be referred to as a first opening, and the through opening in the second mask layer may be referred to as a second opening. In some embodiments, one or both of layers 120 and 130 may be metal layers. In one embodiment, layer 120 is a corrugated metal layer. In some embodiments, layer 130 is a substantially planar layer. Lens layer 110 may be disposed on a substrate layer 140. In some embodiments, the optical construct 100 further includes an intermediate layer 115 disposed between the substrate layer 140 and layer 120 and / or a spacer layer 145 disposed between layers 120 and layer 130. The optical construct 100 may include a first main surface 112, a second main surface 117, and a third main surface 122, wherein the first main surface 112 is the surface of the lens layer 110 that is away from the second main surface 117, the second main surface is the main surface of the intermediate layer 115 that faces the third main surface 122 and is away from the first main surface 112, and the third main surface 122 is the main surface of the layer 120 that is away from the intermediate layer 115. The third main surface 122 of the optical construct 100 may also be, or alternatively, described as the second main surface of the layer 120 opposite to the first main surface 121 of the layer 120.

[0018] In some embodiments, the optical construct 100 includes a lens layer 110 comprising a structured first main surface 112 including a plurality of microlenses 114 arranged along an orthogonal first and second direction (e.g., the x and y directions, referring to the illustrated xyz coordinate system). The optical construct 100 may further include a spaced-apart, optically opaque first mask layer 120 and second mask layer 130, spaced from the first main surface 112 and defining corresponding plurality of first through-holes 126 and second through-holes 136 arranged along the first and second directions, wherein the first mask layer 120 is disposed between the structured first main surface 112 and the second mask layer 130. In some embodiments, the microlenses 114 correspond one-to-one with the first through-holes 126 and with the second through-holes 136. The optical construct 100 may further include an intermediate layer 115 disposed between a structured first primary surface 112 and a first mask layer 120, and includes a corrugated second primary surface 117 facing and substantially registered with a corrugated third primary surface 122 of the first mask layer 120 to define a substantially uniform spacing S1 (e.g., in the range of about 50 nm to about 500 nm) between the second primary surface and the third primary surface.

[0019] In some embodiments, the optical construct 100 includes: a lens layer 110 comprising a plurality of microlenses 114 arranged along orthogonal first and second directions (e.g., x and y directions); an optically opaque first mask layer 130 spaced apart from the plurality of microlenses 114 and defining a plurality of first through-holes 136 arranged along the first and second directions; and a corrugated metal layer 120 having a substantially uniform thickness S1 (e.g., in the range of about 50 nm to about 500 nm) and embedded in the optical construct between the plurality of microlenses and the first mask layer 130. In some embodiments, there is a one-to-one correspondence between the microlenses 114 and the first through-holes 136. In some embodiments, the metal layer 120, which may be described as a second mask layer, defines a plurality of second through-holes 126 arranged along the first and second directions. In some embodiments, there is a one-to-one correspondence between the microlenses 114 and the second through-holes 126.

[0020] Microlenses are typically lenses having at least two orthogonal dimensions (e.g., height and diameter, or diameters along two axes) of less than about 1 mm and greater than about 100 nm. For example, a microlens may have an average diameter ranging from about 0.5 μm to about 500 μm or from about 5 μm to about 100 μm. For example, a microlens may have an average radius of curvature ranging from 5 μm to 50 μm. Microlenses can have any suitable shape. For example, a microlens can be a spherical microlens or an aspherical microlens. For example, in some embodiments, a microlens is a pincushion lens, which can allow the higher portion of the area covered by the lens to be optically active. A pincushion lens can be substantially symmetrical about two orthogonal planes (e.g., planes passing through the center of the lens and parallel to the xz and yz planes, respectively), or substantially symmetrical about three planes parallel to the lens film thickness direction (where each plane is at an angle of about 60 degrees to each other), rather than rotationally symmetrical about any axis.

[0021] In some embodiments, for visible light 150 propagating along a thickness direction orthogonal to the first and second directions (e.g., the negative z-direction) and incident on the optical structure 100 from the lens layer 110 side, the optical structure reflects (see, for example, reflected light 152, etc.) less than about 25%, or less than about 23%, or less than about 20%, or less than about 18%, or less than about 16%, or less than about 14%, or less than about 12%, or less than about 10% of the incident light 150. Visible light 150 can be understood as substantially filling at least one microlens in microlens 114. For example, visible light 150 may include one or more visible wavelengths (e.g., about 400 nm to about 700 nm) and / or may include wavelengths uniformly distributed in the range of about 400 nm to about 700 nm. For example, the reflectivity of the optical construct to visible light 150 (e.g., less than about 25%) may be the average reflectivity at wavelengths from about 400 nm to about 700 nm (e.g., corresponding to wavelengths uniformly distributed in the range of about 400 nm to about 700 nm), or for example, the reflectivity at a wavelength of about 550 nm (e.g., corresponding to visible light 150 with a wavelength of 550 nm).

[0022] The optical construct 100 has a thickness direction (e.g., the z-direction) orthogonal to the first and second directions. The thickness or spacing S1 is along the thickness direction of the optical construct 100. A first mask layer 120 (which is a metal layer in some embodiments) extends primarily along the first and second directions (e.g., the x and y directions) and has a thickness along a thickness direction orthogonal to the first and second directions (e.g., the z-direction). In the illustrated embodiment, the thickness of the first mask layer 120 is the spacing S1. A layer's thickness or spacing can be described as substantially uniform if the thickness of a layer, or the spacing between that layer and adjacent layers, or the spacing between opposite main surfaces of that layer, varies by less than 50% [(maximum minus minimum) / maximum multiplied by 100%) over at least 80% of the area of ​​the main surface of that layer. In some embodiments, this substantially uniform spacing or thickness varies by less than 40% or less than 30% over at least 80% of the area of ​​the main surface. In some such embodiments or in others, at least 80% of the area of ​​the main surface is at least 85%, at least 90%, or at least 95% of the area of ​​the main surface.

[0023] In some embodiments, the substantially uniform spacing or thickness S1 is in the range of about 50 nm to about 2500 nm, or about 2000 nm, or about 1500 nm, or about 1000 nm, or about 500 nm or about 400 nm. S1 can be selected such that layer 120 is optically opaque. In some embodiments, the metal substantially fills the substantially uniform spacing. In other words, in some embodiments, the metal substantially fills the entire distance S1 between the main surfaces 117 and 122. For example, the metal substantially filling the substantially uniform spacing may fill at least 60%, at least 80%, or at least 90% of the volume of the spacing. In some embodiments, the metal (e.g., the metal substantially filling the spacing S1 or the metal of layer 120) comprises at least one transition metal. In some embodiments, the metal comprises one or more transition metals from Groups 4 to 10 of the periodic table. In some embodiments, one or more transition metals from Groups 4 to 10 of the periodic table are derived from Group 4 or Group 5 of the periodic table. In some such embodiments or in others, the substantially uniform spacing or thickness S1 can range from about 50 nm to about 500 nm or from about 50 nm to about 400 nm (e.g., making layer 120 optically opaque). In some embodiments, the metal comprises one or more of zirconium, titanium, chromium, nickel, or iron. For example, the metal may consist of a single-element metal, or the metal may be or include an alloy (such as a chromium-nickel alloy) or stainless steel (such as stainless steel 304) that includes iron and includes chromium and nickel as the main non-ferrous components. In some embodiments, the metal layer includes other metals, such as aluminum or silver.

[0024] In some embodiments, mask layer 130 is formed of a metal such as aluminum or any of the metals described for layer 120. In some such embodiments or in others, mask layer 130 may have an average thickness tm in any range described for S1. In some embodiments, mask layer 130 is formed of a polymeric material comprising, for example, optically absorbing dyes or pigments dispersed in the polymeric material, such as carbon black particles. In some such embodiments or in others, for example, mask layer 130 has an average thickness tm in the range of about 1 micrometer to about 10 micrometers.

[0025] For a layer extending primarily along a first and a second direction (e.g., the x and y directions), the layer may be described as optically opaque when the transmittance (e.g., average transmittance at wavelengths from about 400 nm to about 700 nm) of unpolarized visible light incident on the layer in a third direction perpendicular to the first and second directions (parallel to the z direction) in the region between any through-holes in the layer is less than 10%, or less than 5%, or less than 1%, or less than 0.5%, or less than 0.1%. Alternatively or additionally, the layer may be characterized by its optical density (minus the base-10 logarithm of [transmittance / 100%], where the transmittance is for unpolarized visible light incident along the third direction, unless otherwise stated). In some embodiments, the mask layer has an optical density greater than about 1.5, or greater than about 2, or greater than about 2.5, or greater than about 3 between adjacent through-holes.

[0026] In some embodiments, for example, the average maximum lateral dimension (maximum dimension in the xy plane) of the through openings 126 and / or 136 is in the range of about 500 nanometers to about 50 micrometers, or about 1 micrometer to about 30 micrometers, or about 1 micrometer to about 15 micrometers, or about 1.5 micrometers to about 10 micrometers. The shape of the through openings 126 and / or 136 may be approximately circular.

[0027] In some aspects of this specification, a corrugated metal layer 120 is provided. In some embodiments, the metal layer 120 includes a regularly corrugated first main surface 121 and a regularly corrugated opposite second main surface 122, wherein the regular corrugations of each of the first and second main surfaces 121 are regularly arranged along at least a first direction (e.g., the x-direction) at a spacing P1 less than about 500 nm or any range described elsewhere herein. The metal layer 120 may have an average thickness S1 in the range of about 50 nm to about 500 nm or any other range of S1 described elsewhere herein. The metal layer 120 defines a plurality of through openings 126 arranged along the first direction and an orthogonal second direction (e.g., the y-direction). In some embodiments, the regular corrugations of the first and second main surfaces 121 and 122 are substantially registered to each other (e.g., registered and / or sufficiently registered within a range less than 50%, 30%, or 10% of the thickness of the metal layer 120, such that the first and second main surfaces define a substantially uniform spacing S1 therebetween).

[0028] In some embodiments, the metal layer 120 includes a regularly corrugated first main surface 121 and a regularly corrugated opposite second main surface 122, wherein the regularly corrugated surfaces of the first and second main surfaces 121 are substantially registered to each other such that the first and second main surfaces define a substantially uniform spacing S1 therebetween. The substantially uniform spacing S1 can be within any range described elsewhere. The regularly corrugated surfaces of each of the first and second main surfaces 121 are arranged along at least a first direction (e.g., the x-direction) at a spacing P1 less than about 500 nm or within any range described elsewhere herein. The metal layer 120 may be optically opaque and may define a plurality of through openings 126 arranged along the first direction and an orthogonal second direction (e.g., the y-direction).

[0029] In some embodiments, the optical construct 100 includes a lens layer 110 and a metal layer 120, wherein the lens layer 110 includes a plurality of microlenses 114 arranged along a first direction and a second direction, and the microlenses 114 correspond one-to-one with the through opening 126. In some embodiments, the optical construct 100 includes: a lens layer 110 including a structured first main surface 112 including a plurality of microlenses 114 arranged along the first direction and the second direction; and a metal layer 120, wherein the metal layer is substantially co-linear with the lens layer 110, and the microlenses 114 correspond one-to-one with the through opening 126. In some such embodiments or in other embodiments, for visible light 150 propagating in a direction orthogonal to the first and second directions (e.g., the x-direction and the y-direction) and incident on the optical construct from the lens layer side, the optical construct 100 reflects less than about 25% of the incident light 150, or reflects within any range described elsewhere herein. In some embodiments, the optical construct 100 further includes an intermediate layer 115 disposed between the lens layer 110 and the metal layer 120, wherein the metal layer 120 is disposed on and substantially registered with the corrugated main surface 117 of the intermediate layer 115. In some embodiments, the optical construct further includes a mask layer 130 defining a plurality of through openings 136 arranged along a first direction and a second direction, wherein the metal layer 120 is disposed between the lens layer 110 and the mask layer 130. The microlenses 114 may correspond one-to-one with the through openings 136 in the mask layer 130.

[0030] Layers can be described as substantially colinear with each other if at least about 60% of each layer is colinear with at least about 60% of each other layer in a top plan view (viewed along the thickness direction of the optical structure 100). Here, for example, 60% of a layer refers to 60% of the area in the top view (e.g., 60% of the area of ​​that layer projected onto a plane defined by the first and second directions). In some embodiments, for layers described as substantially colinear, at least about 70%, or at least about 80%, or at least about 90% of each layer is colinear with at least about 70%, or at least about 80%, or at least about 90% of each other layer in the top plan view.

[0031] In some embodiments, the lens layer and the intermediate layer have corresponding average thicknesses h1 and h2, wherein 0.5 ≤ h2 / h1 ≤ 10, or 0.7 ≤ h2 / h1 ≤ 5, or 0.9 ≤ h2 / h1 ≤ 3. In some embodiments, each of h1 and h2 is in the range of 3 micrometers to 50 micrometers, or in the range of 5 micrometers to 40 micrometers. As further described elsewhere herein, the ratio h2 / h1 may be selected to reduce or maximize the reduction of curling of the optical construct 100. In some embodiments, for example, the average thickness ts of the substrate layer 140 may be at least about 10 micrometers, or at least about 15 micrometers, or at least about 20 micrometers, and / or may not exceed about 150 micrometers or not exceed about 100 micrometers. In some embodiments, ts is greater than at least one of h1 or h2. In some embodiments, ts is greater than each of h1 and h2. In some embodiments, the spacer layer 145 has an average thickness h3, for example, which may be in the range of about 1 micrometer to about 50 micrometers or about 2 micrometers to about 40 micrometers. In some embodiments, the total thickness of the optical construct 100 is no greater than about 200 micrometers, or no greater than about 150 micrometers, or no greater than about 100 micrometers (e.g., about 30 micrometers to about 200 micrometers or about 40 micrometers to about 150 micrometers).

[0032] In some embodiments, the regular corrugations of the first primary surface 121 and the second primary surface 122 are substantially registered with each other. In some embodiments, the corrugations of the metal layer 120 or the corrugations of the first primary surface 121 and the second primary surface 122 are regularly arranged along at least one direction (e.g., the x-direction) at a spacing P1 of less than about 500 nm. In some embodiments, the spacing P1 is less than about 400 nm, or less than about 350 nm, or less than about 300 nm. In some such embodiments or in other embodiments, the spacing P1 is greater than about 50 nm or greater than about 100 nm. The first primary surface 121 and the second primary surface 122 of the layer 120 may correspond to the second primary surface 117 and the third primary surface 122 of the optical construct 100. In some embodiments, the substantially registered corrugations of the second primary surface 117 and the third primary surface 122 are regularly arranged along at least one direction (e.g., the x-direction) at a spacing P1, which may be less than about 500 nm or may be within any range described elsewhere herein. In some embodiments, S1 may be less than or about equal to P1. In some embodiments, the corrugations of the main surface 117 or the first main surface 121 and / or the second main surface 122 have an average peak-to-valley height h4, which can be within any range, for example, for S1 or for P1. In some embodiments, for example, the first main surface 121 has an average peak-to-valley height h4 in the range of about 50 nm to about 2500 nm or about 100 nm to about 1500 nm.

[0033] Figures 2 to 3 This is a schematic top plan view of the corrugations on the layers or surfaces of an optical structure or a part thereof, according to some embodiments. Figure 2 In some implementation schemes, the corrugations extend along the y-direction and are regularly arranged along the x-direction at a spacing P1. Figure 2 The ripples can be a regular array of linear prisms. Figure 2 The optical structure shown, or a portion thereof, has a width W along the x-direction and a length L along the y-direction. Figure 3 In the diagram, the ripples are regularly arranged at a spacing P1 in the x-direction and at a spacing P2 in the y-direction. P1 and P2 can be located independently within any range described elsewhere in this document with respect to P1 (e.g., less than about 500 nm). Figure 3 The ripples can be a regular two-dimensional pyramid array.

[0034] In some embodiments, the substantially registered corrugations of the second primary surface 117 and the third primary surface 122 and / or the corrugations of layer 120 extend along a third third direction (e.g., the y-direction) and are regularly arranged along an orthogonal fourth direction (e.g., the x-direction). The corrugations may be regularly arranged along the fourth direction at a spacing P1 of less than about 500 nm. The spacing P1 may be within any range described elsewhere herein. For example, the third and fourth directions may be the same as the second and first directions, respectively, or may be rotated relative to the second and first directions (e.g., about the z-axis). In some embodiments, the substantially registered corrugations of the second primary surface 117 and the third primary surface 122 and / or the corrugations of layer 120 are regularly arranged along each of the third third direction (e.g., the y-direction) and different (e.g., orthogonal) fourth directions (e.g., the x-direction) at respective spacings P2 and P1 of less than about 500 nm. Each of P1 and P2 may be within any range described elsewhere herein with respect to P1. For example, the corrugations may be regularly arranged on a hexagonal lattice. In some implementations, the substantially registered corrugations of the second primary surface 117 and the third primary surface 122 and / or the corrugations of layer 120 are arranged aperiodically or irregularly. For example, the corrugations may be a quasi-crystalline pattern, or they may be arranged randomly or pseudo-randomly (appearing random but originating from a deterministic process).

[0035] Figures 4A to 4BThis is a schematic top-view projection of multiple microlenses 114 and through-holes 231 (e.g., corresponding to through-holes 126 and / or through-holes 136) according to some embodiments. The microlenses 114 are arranged along orthogonal first and second directions (e.g., the x and y directions), and the through-holes 231 are arranged along the first and second directions. In the illustrated embodiment, the microlenses 114 and through-holes 231 are located on a regular triangular array. Other patterns are also possible (e.g., square or rectangular arrays, other two-dimensional periodic arrays, or irregular patterns). The optical construct 100 can be adapted to primarily transmit light incident along a predetermined direction (e.g., along the thickness direction of the optical construct) rather than along other directions. Figure 4A In the illustrated embodiment, the microlens 114 and the through-hole 231 are centered on a straight line parallel to the z-direction. This allows light incident on the optical structure along the z-axis to pass through the optical lens and the through-hole, while blocking obliquely incident light. Figure 4B In the illustrated embodiment, the microlens 114 and the through-hole 231 are centered on a straight line at an angle to the z-direction. For example, this allows light incident on the optical structure at an angle to the z-direction to pass through the optical lens and the through-hole, while blocking perpendicularly incident light, etc.

[0036] In some embodiments, the lens layer 110 is formed by casting resin onto the substrate 140 using a tool that defines the microlens 114, followed by resin curing. Similarly, in some embodiments, the intermediate layer 115 is formed by casting resin onto the substrate 140 using a tool that defines the corrugated surface 117, followed by resin curing. Suitable resins (e.g., acrylates) and suitable casting and curing methods are known in the art and can be generally described in, such as, U.S. Patents 5,175,030 (Lu et al.), 5,183,597 (Lu), and 9,919,339 (Johnson et al.), and U.S. Patent Application Publication No. 2012 / 0064296 (Walker, JR. et al.). Suitable substrates include polyethylene terephthalate (PET) substrates. The layer 120 can then be coated or otherwise deposited (e.g., by vapor deposition or sputtering) onto the corrugated surface 117. Then, for example, spacer layer 145 can be formed by coating a resin (e.g., acrylate) onto the main surface 122 of layer 120 and then curing the resin. Layer 130 can then be coated or otherwise deposited (e.g., vapor deposition or sputtering) onto spacer layer 145. Through openings 126 and 136 can then be formed by ablating through microlens 114 using a coherent pulsed light source (e.g., a laser), for example, having a wavelength of 400 nm to 1200 nm, or 500 nm to 1100 nm, or 1000 nm to 1100 nm, or 1020 nm to 1100 nm. Various lasers can be used as the light source. Suitable lasers include, for example, Nd:YAG lasers, fiber lasers, and diode lasers. For example, the light source could be a doped fiber laser that produces a near-infrared (NIR) band with wavelengths of about 1020 nm to about 1100 nm. Typically, layers 120 and 130 are ablated, while layers 115 and 145 are essentially not ablated. For example, the formation of holes in layers using a laser through a microlens array is broadly described in U.S. Patent Application Publication No. 2007 / 0258149 (Gardner et al.). In some examples, through-holes are formed by laser ablation at 50% power using a 40W fiber laser with a 7x expander (available from SPI Lasers, Southampton, UK), where the fiber laser operates at 20 kHz and the pulse duration is set to 30 ns, and a 167 mm F-Theta lens is used with a galvanometer scanner that moves the laser beam at 2 m / s (the spacing between lines is 100 micrometers). Other suitable methods for forming through-holes include microprinting and photolithography techniques (e.g., including the use of microlens layers to expose a photomask).

[0037] The optical construct 100 may include optional additional elements or layers disposed on a lens layer 110 opposite to the substrate layer 140 and / or on a layer 140 opposite to layer 145. For example, a low refractive index layer may be disposed on the lens layer 110, or the lens layer 110 may include an optical decoupling structure, and / or a wavelength-selective optical filter may be disposed on layer 130. Examples of such layers or structures can be described, for example, in International Application Publication No. WO 2020 / 035768 (Yang et al.).

[0038] In some embodiments, the microlens layer is bonded to a display panel or other component via a low-refractive-index layer. In some embodiments, the low-refractive-index layer has a refractive index of no more than 1.3 (e.g., in the range of 1.1 to 1.3) and is disposed on a first main surface 103 of the lens layer 110 and has a main surface substantially conformal to the first main surface. Unless otherwise specified, the refractive index refers to the refractive index at 633 nm. The layer with a refractive index of no more than 1.3 can be, for example, a nanoporous layer as described in U.S. Patent Application Publication Nos. 2013 / 0011608 (Wolk et al.) and 2013 / 0235614 (Wolk et al.).

[0039] In some embodiments, lens layer 110 further includes optical decoupling structures that can be disposed between adjacent microlenses. The optical decoupling structure can be any object protruding beyond the microlenses to attach to the adjacent layer such that the adjacent layer does not contact the microlenses. The optical decoupling structure can be a cylindrical pillar, or a pillar having a non-circular cross-section (e.g., rectangular, square, elliptical, or triangular cross-section). The optical decoupling structure can have a constant cross-section, or the cross-section can vary along the thickness direction (e.g., the optical decoupling structure can be a tapered pillar that tapers near the top). In some embodiments, the optical decoupling structure has a tapered elliptical cross-section. For example, the optical decoupling structure can have any of the geometries of the optical decoupling structures described in International Application Publication No. WO2019 / 135190 (Pham et al.). In some embodiments, the optical decoupling structure extends from the base of the microlens array. In some embodiments, at least some of the optical decoupling structures are disposed on top of at least some of the microlenses. Related optical constructs, including optical decoupling structures, are described in International Application Publication No. WO 2020 / 035768 (Yang et al.) and U.S. Patent No. 62 / 944676, entitled “Optical Layers and Optical Systems”, filed on December 6, 2019.

[0040] In some embodiments, the optical construct includes two or more microlenses. For example, the optical construct may have opposing first and second main surfaces, each including multiple microlenses. The optical construct or layer may also include an embedded optically opaque mask layer disposed between and spaced apart from the first and second main surfaces. The mask layer may be or include a corrugated metal layer as further described elsewhere herein. Related optical constructs including opposing microlens layers are described in International Application Publication No. WO 2020 / 035768 (Yang et al.) and U.S. Patent No. 62 / 944676, filed December 6, 2019, entitled "Optical Layers and Optical Systems".

[0041] In some embodiments, it is desirable that the substrate 140 remains substantially flat (e.g., with little or no curling) after the formation of lens layer 110 and intermediate layer 115. The resin used to form the layers may shrink upon curing, therefore it may be necessary to use similar resin chemicals with similar shrinkage properties for the lens and intermediate layers 110 and 115. In some embodiments, each layer of the lens and intermediate layers 110 and 115 comprises a radiation (e.g., ultraviolet) curable polymer. In some such embodiments or in others, each layer of the lens and intermediate layers 110 and 115 comprises a crosslinked polymer. In some such embodiments or in others, each layer of the lens and intermediate layers 110 and 115 comprises an acrylate. In some embodiments, different resins (e.g., different acrylates or resins from different chemical classes) are used for the lens and intermediate layers 110 and 115, and the relative thicknesses of these layers (e.g., 0.7 ≤ h2 / h1 ≤ 5) are selected to reduce or eliminate the resulting curling. For example, a thicker layer formed from a resin with a lower tendency to shrink upon curing can be used to offset the effect of curling on a thinner layer formed from a resin with a higher tendency to shrink upon curing.

[0042] Figure 5 This is a schematic diagram of the curling of a portion 200 of an optical construct, such as according to some embodiments, which may correspond to an optical construct 100. The portion 200 is oriented such that it bends away from the flat surface 170. In some embodiments, the portion 200 of the optical construct 100 is removed from the optical construct 100 and placed on the flat surface 170 such that when at least the central portion 165 of the portion 200 contacts the flat surface 170, the average displacement d of the corner of the portion 200 from the flat surface 170 is less than about 5 mm, or less than about 4 mm, or less than about 3 mm, or less than about 2 mm, wherein the shape of the portion 200 is generally a rectangular plate, the length and width (e.g., corresponding to...) Figure 2The length (L) and width (W) are each in the range of approximately 8.5 inches to approximately 9 inches. Note that a square can be considered a special case of a rectangle. Alternatively, a curl as determined by the ASTM F415-87 (2005) test standard can be anywhere within these ranges.

[0043] In some implementations, the first mask layer and the base layer or intermediate layer need to have a high (e.g., at least about 20 g / in) minimum average peel force F. It has been found that including the intermediate layer 115 can improve the bonding between the mask layer 120 and the base layer 140. For example, it has been found that metal layers (e.g., transition metal or transition metal alloy layers) formed (e.g., sputtered) on acrylate layers can provide a suitable minimum average peel force F, while metal layers formed directly on typical base layers (e.g., polyethylene terephthalate (PET) layers) may have undesirable low peel forces. The minimum average peel force F is determined using a 180-degree peel test at a peel rate of 12 in / min (see, e.g., Figure 1 The peel force (F) is determined using the method illustrated in the diagram, unless otherwise stated. An average peel force is measured for each of a plurality of samples (5 samples, unless otherwise stated), as the average of the force applied per unit width of the sample during the peeling process as a function of time (5 seconds, unless otherwise stated). The minimum of these average peel forces across the plurality of samples is the minimum average peel force F. In some embodiments, the minimum average peel force F between the intermediate layer 115 and the first mask layer 120 is at least about 20 g / in, or at least about 30 g / in, or at least about 40 g / in, or at least about 50 g / in. In some such embodiments or in others, the minimum average peel force F may be as high as about 200 g / in or as high as about 100 g / in. For example, the minimum average peel force F may be in the range of about 20 g / in to about 200 g / in.

[0044] Figure 6This is a schematic cross-sectional view of an illustrative display system 1000 for sensing a finger 180 of a user 190 applied to a display system 1000, according to some embodiments. The display system 1000 includes: a display panel 133; a sensor 147 disposed near the display panel 133 for sensing the finger 180 of the user 190; and an optical structure 100 disposed between the display panel 133 and the sensor 147, wherein a lens layer 110 is disposed away from the sensor 147. The display system 1000 may include infrared light sources 125 and / or 125', configured to emit infrared light 266 and / or 266' towards the finger 180 of the user 190, respectively, such that at least a portion 267 of the infrared light can be reflected from the finger 180. The optical structure 100 is configured to receive at least a portion 268 of the reflected infrared light 267 and transmit at least a portion 269 of it to the sensor 147. The display panel 133 may be configured to generate an image 134 for the user 190 to view. The display panel can be any suitable display panel, such as an organic light-emitting diode (OLED) display panel or a liquid crystal display (LCD) panel. Various other thin films or elements may be included in the display system 1000. For example, in the case of an LCD display panel, a backlight may be disposed between the display panel 133 and the optical structure 100, and a prism film may be disposed between the backlight and the display panel. Related optical structures and their applications in display systems are described in International Application Publication No. WO 2020 / 035768 (Yang et al.), U.S. Patent No. 63 / 080105, filed September 18, 2020, entitled "Optical Structure and Optical System Including Light-Absorbing Optical Cavity," and U.S. Patent No. 62 / 944676, filed December 6, 2019, entitled "Optical Layer and Optical System."

[0045] Example

[0046] One-dimensional (linear) nanostructured films were designed and fabricated by casting acrylate resin close to a tool and curing it onto a PET substrate. The nanostructures have a spacing and height of approximately 225 nm. Polymer (acrylate-based) microlenses were cast onto the substrate side opposite the nanostructures, and a metal layer was deposited on the nanostructures. Four pure metals were selected for comparison: titanium, zirconium, nickel, and silver, as well as stainless steel (SS) 304 and chromium. 80 -nickel 20Alloy. The table below summarizes the materials used in the coating process, the type of sputtering source (planar or circular magnetron tool), and the associated substrate motion (roll-to-roll (R2R) or rotation). Zirconium was coated with two different arrangements. Each combination of material, tool, and substrate motion was studied in advance to determine the sputtering power and coating time to provide an optical density of 3.3 (transmittance of 0.05%) when coating on a flat (unstructured) film. Through-holes were formed in the resulting corrugated metal layer by laser ablation through the microlens layer.

[0047] Reflectance was measured using a diode array spectrophotometer (tec5, Nynomic AG, Germany). The sample was placed individually on a sample stage below a bifurcated optical cable. In this setup, one bifurcation end was connected to a halogen tungsten lamp, and the other end to the tec5 spectrometer. Light from the lamp traveled through the first bifurcation end to the distal end of the probe and was reflected from the sample. The reflected light traveled from the distal end to the second bifurcation end, where it was coupled back into the spectrometer for analysis. The reflectance intensity was measured relative to an uncoated substrate (a PET film), and the reflectance at 550 nm wavelength was estimated (in percentage) based on the reflectance intensity measurements. The intrinsic reflectance of the flat metal at 550 nm wavelength was calculated from the real and imaginary parts of the metal's refractive index. The results are provided in the table below.

[0048] Material Sputtering magnetron tools Basement movement Intrinsic reflectance (%) Estimated TEC5 reflectance (%) Ti flat R2R 50.2 Approximately 10 Zr flat R2R 52.2 Approximately 8 <![CDATA[Cr 80 In 20 ]]> flat R2R 57.8 Approximately 20 SS flat R2R 62.2 Approximately 12 Ni flat R2R 61.2 Approximately 30 Ag round Rotation 98.2 Approximately >70 Zr round Rotation 52.2 Approximately 8

[0049] Figure 7 This is an image of a typical sputtered metal layer that penetrates near the opening in the metal layer. Figure 8 This is an image of a representative sample extending through the edge of the opening in metal layer 120. Figures 7 to 8 In the middle, the intermediate layer 115 is located below the metal layer 120.

[0050] Terms such as “about” will be understood in the context in which they are used and described by those skilled in the art. If it is unclear to those skilled in the art in the context of their use and description of “about” to express quantities of characteristic size, quantity, and physical properties, then “about” will be understood to mean within 10% of a specified value. A quantity given a specified value as “about” can be precisely the specified value. For example, if it is unclear to those skilled in the art in the context of their use and description of this specification, a quantity having a value of about 1 means that the quantity has a value between 0.9 and 1.1, and that the value can be 1.

[0051] All cited references, patents, and patent applications are incorporated herein by reference in their entirety in a consistent manner. In the event of any inconsistency or contradiction between the incorporated references and this application, the information in the foregoing description shall prevail.

[0052] Unless otherwise stated, the description of elements in the accompanying drawings should be understood to apply equally to corresponding elements in the other drawings. While specific embodiments have been illustrated and described herein, those skilled in the art will recognize that various alternative and / or equivalent embodiments may be used instead of the illustrated and described embodiments without departing from the scope of this disclosure. This application is intended to cover any modifications, variations, or combinations of the specific embodiments discussed herein. Therefore, this disclosure is intended to be limited only by the claims and their equivalents.

Claims

1. An optical construct, the optical construct comprising: A lens layer, the lens layer including a structured first main surface, the first main surface including a plurality of microlenses arranged along an orthogonal first direction and a second direction; A spaced-apart, optically opaque first mask layer and second mask layer, the first mask layer and the second mask layer being spaced apart from the first main surface and defining a plurality of corresponding first through openings and second through openings arranged along the first direction and the second direction, the first mask layer being disposed between the structured first main surface and the second mask layer, and the microlens corresponding one-to-one with the first through opening and with the second through opening; and An intermediate layer is disposed between the structured first primary surface and the first mask layer, and includes a corrugated second primary surface facing and registered with a corrugated third primary surface of the first mask layer to define a uniform spacing between the second primary surface and the third primary surface, wherein the lens and the intermediate layer have corresponding average thicknesses h1 and h2, 0.7 ≤ h2 / h1 ≤ 5. The lens and the intermediate layer each contain acrylate. The uniform intervals are filled with metal.

2. The optical construct according to claim 1, wherein the metal comprises one or more of zirconium, titanium, chromium, nickel or iron.

3. The optical construct according to claim 1, wherein the uniform spacing is in the range of 50 nm to 500 nm.

4. The optical construct according to claim 1, wherein the registration corrugations of the second primary surface and the third primary surface are regularly arranged along at least one direction with a spacing of less than 500 nm.

5. The optical structure according to any one of claims 1 to 4, wherein for visible light propagating in a direction orthogonal to the first direction and the second direction and incident on the optical structure from the lens layer side of the optical structure, the optical structure reflects less than 25% of the incident light.

6. The optical structure according to claim 1, wherein, The first mask layer is a corrugated metal layer having a uniform thickness in the range of 50 nm to 500 nm, and is embedded in the optical structure between the plurality of microlenses and the second mask layer, such that for visible light propagating along a thickness direction orthogonal to the first and second directions and incident on the optical structure from the lens layer side of the optical structure, the optical structure reflects less than 25% of the incident light.

7. The optical construct of claim 6, wherein the corrugations of the metal layer extend along a third direction and are regularly arranged along an orthogonal fourth direction.

8. The optical construct according to claim 6 or 7, wherein the corrugations of the metal layer are regularly arranged along at least one direction at a spacing of less than 500 nm.

9. The optical construct of claim 1, wherein the first mask layer is a metal layer, the metal layer comprising a first main surface with regular corrugations and a second main surface with regular corrugations, the regular corrugations of each of the first and second main surfaces of the metal layer being regularly arranged along at least a first direction at a spacing of less than 500 nm, the metal layer having an average thickness in the range of 50 nm to 500 nm and defining a plurality of through openings arranged along the first direction and an orthogonal second direction.

10. The optical construct of claim 9, wherein the regular corrugations of the first primary surface and the second primary surface of the metal layer are registered with each other.

11. The optical construct of claim 1, wherein the first mask layer is a metal layer, the metal layer comprising a first main surface with regular corrugations and a second main surface with regular corrugations of opposite shapes, the regular corrugations of the first main surface and the second main surface of the metal layer being registered to each other such that the first main surface and the second main surface of the metal layer define a uniform spacing therebetween; the regular corrugations of each of the first main surface and the second main surface of the metal layer are arranged along at least a first direction at a spacing of less than 500 nm, the metal layer being optically opaque and defining a plurality of through openings arranged along the first direction and an orthogonal second direction.

12. The optical construct of claim 11, wherein the regular ripples of the first main surface of the metal layer have an average peak-valley height in the range of 50 nm to 2500 nm.

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