Optical construction comprising a lens film and a multilayer mask

Abstract

An optical construction includes a lens film having an outermost first major surface and a second major surface. The first major surface includes a plurality of microlenses. A multilayer mask having an average thickness less than about 0.5 times an average focal length of the microlenses and having an optical density greater than about 2 is disposed on the second major surface. The multilayer mask includes first and second mask layers of a polymer, where each of the first and second mask layers has an optical density greater than about 0.3. The multilayer mask defines a plurality of laser-ablated through openings therein in a one-to-one correspondence with the microlenses. An optical transmittance of the optical construction as a function of angle of incidence has a transmittance peak having a peak transmittance T1 and a corresponding 20% extreme full-width W1, where T1 / W1 ≥ 2.4% / degree.

Description

Background Technology

[0001] Optical devices may include microlens arrays and masks including pinhole arrays. Summary of the Invention

[0002] This specification relates in its entirety to an optical construct comprising a multilayer mask and a lens film, the lens film comprising multiple microlenses.

[0003] In some aspects of this specification, an optical construct is provided. The optical construct includes a lens film having an outermost structured first main surface and an opposite outermost substantially flat second main surface. The structured first main surface includes a plurality of microlenses arranged along orthogonal first and second directions. The optical construct includes a polymer multilayer mask disposed on the second main surface of the lens film. The multilayer mask has an average thickness less than about 0.5 times the average focal length of the microlenses and an optical density greater than about 2. The multilayer mask includes a first mask layer and a second mask layer of polymer, each of the first and second mask layers having an optical density greater than about 0.3. The multilayer mask defines a plurality of laser ablation through openings arranged along the first and second directions. These through-holes are aligned with these microlenses in a one-to-one correspondence, such that: for substantially collimated light incident on the structured first main surface side of the optical structure along an incident direction forming an incident angle with the second main surface, the optical transmittance of the optical structure as a function of the incident angle includes a first transmission peak having a first peak transmittance T1 and a corresponding 20% ​​maximum full width at 1 / 20° W1. T1 / W1 ≥ 2.4% / degree.

[0004] In some aspects of this specification, an optical construct is provided. The optical construct includes a lens film having an outermost structured first main surface and an opposite outermost substantially flat second main surface. The structured first main surface includes a plurality of microlenses arranged along orthogonal first and second directions. The optical construct includes a polymer multilayer mask disposed on the second main surface of the lens film. The multilayer mask has an average thickness less than about 0.5 times the average focal length of the microlenses and an optical density greater than about 2. The multilayer mask includes a first mask layer and a second mask layer of polymer, each of the first and second mask layers having an optical density greater than about 0.3. The multilayer mask defines a plurality of laser ablation through openings arranged along the first and second directions. These through-holes are aligned with these microlenses in a one-to-one correspondence, such that: for substantially collimated light incident on the structured first main surface side of the optical structure along an incident direction forming an incident angle with the second main surface, the optical transmittance of the optical structure as a function of the incident angle includes a first transmission peak having a first peak transmittance T1 and a second transmission peak having a second peak transmittance T2. The second transmission peak is the maximum transmission peak at an incident angle at least about 30 degrees larger and no more than about 60 degrees larger than the first transmission peak. T2 ≤ 3% and T1 / T2 ≥ 10.

[0005] In some aspects of this specification, an optical construct is provided. The optical construct includes a lens film having an outermost structured first main surface and an opposite outermost substantially flat second main surface. The structured first main surface includes a plurality of microlenses arranged along orthogonal first and second directions. The optical construct includes a multilayer mask disposed on the second main surface of the lens film. The multilayer mask has an average thickness less than about 0.5 times the average focal length of the microlenses and an optical density greater than about 2. The multilayer mask defines a plurality of laser ablation through openings arranged along the first and second directions. The through openings are aligned with the microlenses in a one-to-one correspondence. The multilayer mask includes a first mask layer of polymer and a second mask layer comprising a first material and a second material, the first material and the second material including corresponding first and second binding groups, wherein the first binding groups and the second binding groups have complementary interactions. Each of the first mask layer and the second mask layer has an optical density greater than about 0.3.

[0006] In some aspects of this specification, an optical construct is provided. The optical construct includes a lens film having an outermost structured first main surface and an opposite outermost substantially flat second main surface. The structured first main surface includes a plurality of microlenses arranged along orthogonal first and second directions. The optical construct includes a multilayer mask of polymer disposed on the second main surface of the lens film. The multilayer mask has an average thickness less than about 0.5 times the average focal length of the microlenses and an optical density greater than about 2. The multilayer mask defines a plurality of laser ablation through openings arranged along the first and second directions. The through openings are aligned with the microlenses in a one-to-one correspondence. The multilayer mask includes a first mask layer and a second mask layer of polymer, each of the first and second mask layers having an optical density greater than about 0.3. The first mask layer is thicker than the second mask layer, and the optical density of the second mask layer is greater than that of the first mask layer.

[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] Figure 2 It is a schematic graph of the optical transmittance as a function of the incident angle for an optical structure according to some implementation schemes.

[0010] Figures 3A to 3B It is a schematic top-view projection of an optical structure according to some implementation schemes.

[0011] Figures 4A to 4B It is a schematic cross-sectional view of a multilayer mask according to some implementation schemes.

[0012] Figures 5A to 5C The solvent deposition of a mask layer on a lens film is schematically shown according to some embodiments.

[0013] Figure 5D It is a schematic cross-sectional view of a mask layer deposited on a lens film through layer-by-layer self-assembly.

[0014] Figure 5E This is a schematic diagram of a double layer.

[0015] Figure 5F This is a schematic diagram of laser ablation of a multi-layer mask through a lens film.

[0016] Figure 6It is a schematic graph of optical absorption versus wavelength based on some implementation schemes.

[0017] Figure 7 It is a graph showing the absorption rate of various masks against wavelength.

[0018] Figure 8 It is a graph comparing the optical transmittance of optical structures with the angle of incidence.

[0019] Figure 9 This is a graph of the optical transmittance versus the angle of incidence for an exemplary optical structure. Detailed Implementation

[0020] 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.

[0021] Optical constructs may include microlens arrays and a metal mask having an array of through-holes (e.g., pinholes) corresponding to the microlenses. However, it has been found that using a metal mask can cause unwanted specular reflections in the mask region between the through-holes. A polymer layer comprising an optically absorbing material can be used instead of a metal mask. However, previous optical constructs using such polymer layers have through-holes with poor shape sharpness, which can lead to undesirable broad peaks in optical transmittance through the through-holes and / or undesirable crosstalk (e.g., light incident on a microlens can transmit through adjacent through-holes) and / or undesirable low peak transmittance (unless large-diameter through-holes that would cause undesirable crosstalk are used).

[0022] According to some embodiments of this specification, a multilayer mask is provided that provides a spike in optical transmittance through an optical structure. The multilayer mask may comprise a solvent-deposited mask layer and / or a coated and cured polymer mask layer. A solvent-deposited mask layer is formed by depositing (e.g., coating) a material (e.g., a polymer and an optically absorbing material) in a solvent and then evaporating the solvent. The multilayer mask may comprise a mask layer formed by layer-by-layer self-assembly of a first material and a second material, the first material and the second material having corresponding first and second binding groups, the first and second binding groups having complementary interactions (e.g., electrostatic interactions between positively charged functional groups and negatively charged functional groups). For example, the first material and the second material may be a polymer and nanoparticles, respectively, with opposite charges. After the multilayer mask has been formed, through-holes can be formed in the multilayer mask by laser ablation.

[0023] It has been found that mask layers formed by layer-by-layer self-assembly (e.g., polymers and nanoparticles with opposite charges) provide a desired increase in optical density with a lower increase in thickness compared to, for example, simply increasing the thickness of a mask layer formed by solvent deposition or coating and curing. However, it has been found that when using only mask layers formed by layer-by-layer self-assembly, it is difficult to achieve the desired low crosstalk due to the difficulty in achieving sufficient thickness of such mask layers. According to some embodiments of this specification, multilayer masks comprising a polymer mask layer (e.g., a solvent-deposited or coated and cured polymer layer) and a layer-by-layer self-assembled mask layer can, for example, achieve high optical density (e.g., greater than about 2) and a desired total thickness (e.g., from about 1 micrometer to about 7 micrometers), thereby resulting in low crosstalk. According to some embodiments, it has been further found that solvent-deposited mask layers provide improved via shape definition (and, for example, correspondingly lower crosstalk) compared to, for example, polymer mask layers formed by coating and curing. In some embodiments, the multilayer mask comprises a solvent-deposited mask layer and a mask layer formed via layer-by-layer self-assembly.

[0024] In some embodiments, the optical construct can be used as an angle-selective optical filter, which can be used in various applications, such as fingerprint sensing applications. In some embodiments, the optical construct can be disposed between the fingerprint sensing area and the sensor in a device (e.g., a mobile phone) 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.

[0025] Figure 1This is a schematic cross-sectional view of an optical construct 200 according to some embodiments. The optical construct 200 includes: a lens film 110 having an outermost structured first main surface 102 and an opposite outermost second main surface 104; and a multilayer mask 120 disposed on the second main surface 104 of the lens film 110. The structured first main surface 102 includes a plurality of microlenses 103 arranged along orthogonal first and second directions (e.g., x and y directions). The second main surface 104 may be substantially flat (e.g., flat or nominally flat or a plane with less variation or curvature compared to the structured first main surface 102). The multilayer mask 120 has an average thickness less than about 0.5 times the average focal length of the microlenses and may have an optical density greater than about 2. The multilayer mask 120 may include two or more mask layers. In some embodiments, the multilayer mask 120 includes polymer mask layers 120a and 120b, each of which may have an optical density greater than about 0.3. Either of mask layers 120a and 120b may be referred to as a first mask layer, and the other of mask layers 120a and 120b may be referred to as a second mask layer. In some embodiments, the first mask layer is a polymer mask layer (e.g., a solvent-deposited mask layer), and the second mask layer includes a first material and a second material having corresponding first and second binding groups, wherein the first and second binding groups have complementary interactions (e.g., via layer-by-layer self-assembly deposition). The multilayer mask 120 defines a plurality of laser-ablated through-openings 123 arranged along a first and a second direction, wherein the through-openings 123 are aligned with microlenses in a one-to-one correspondence.

[0026] 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. Microlenses may have an average diameter, for example, ranging from about 0.5 micrometers to about 500 micrometers, or from about 5 micrometers to about 100 micrometers. For example, a microlens may have an average radius of curvature ranging from 5 micrometers to 50 micrometers. Microlenses may have any suitable shape. For example, a microlens may be a spherical microlens or an aspherical microlens. For example, in some embodiments, a microlens is a pincushion lens, which may allow the higher portion of the area covered by the lens to be optically active. A pincushion lens may 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.

[0027] The multilayer mask 120 may be a polymer multilayer mask. A polymer multilayer mask is a multilayer mask in which each mask layer is a polymer. The polymer layer comprises an organic polymer that extends substantially continuously in the length and width of the layer, and may optionally include, for example, non-polymer particles distributed within the polymer. For example, a pigment and / or dye-filled polymer may be used to form the polymer layer.

[0028] The multilayer mask 120 has a third principal surface 143 and a fourth principal surface 144 facing away from each other, wherein the third principal surface 143 faces the lens film 110. The multilayer mask 120 has an average thickness t, which may alternatively be described as an average spacing between the third principal surface 143 and the fourth principal surface 144. Unless otherwise stated, the average value refers to an unweighted average value. In some embodiments, the average thickness t is, for example, less than about 0.5 times, or less than about 0.4 times, or less than about 0.3 times the average focal length f. In some such embodiments, or in other embodiments, the average thickness t is, for example, less than about 10 micrometers, or less than about 8 micrometers, or less than about 6 micrometers, or less than about 5 micrometers, or less than about 4 micrometers. The average thickness t may, for example, be greater than about 1 micrometer, or greater than about 2 micrometers, or greater than about 2.5 micrometers. The average thickness t may, for example, range from about 1 micrometer to about 7 micrometers, or from about 2 micrometers to about 6 micrometers. In some embodiments, the total thickness T of the lens film 110 and the multilayer mask 120 is no greater than about 100 micrometers (e.g., in the range of about 30 micrometers to about 100 micrometers). The lens film 110 may include, for example, a lens layer 194 cast and cured on a substrate layer 197, such that the thickness of the lens film 110 is the thickness of the lens layer 194 and the substrate layer 197. The substrate layer 197 may be, for example, a polymer film such as a polyethylene terephthalate (PET) film. In some embodiments, the average focal length f is, for example, in the range of T-3t to T+2t, or in the range of T-2t to T+t, or in the range of Tt to T. The casting and curing processes are generally described in, for example, U.S. Patent Nos. 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.). This type of casting and curing process can utilize acrylic resins to form microlenses.

[0029] In some embodiments, in at least a first cross-section along a direction substantially orthogonal to the first and second directions and substantially bisecting the first opening 123a of the plurality of through openings 123, the first opening 123a has a larger first width d1 on the side of the multilayer mask 120 facing the lens film 110 and a smaller second width d2 on the side of the multilayer mask 120 facing away from the lens film 110. In other embodiments, the first width d1 is smaller than the second width d2. In some embodiments, d1 and d2 are approximately equal. The relative widths of d1 and d2 may depend on the material selection of the multilayer mask and the laser ablation processing conditions. Adjusting the shape of the through-hole via laser processing conditions is generally described, for example, in U.S. Patent No. 7,864,450 (Segawa et al.). In some embodiments, the ratio of the first width d1 to the second width d2 (d1 / d2) is in the range of about 1.1 to about 2.

[0030] In some embodiments, the through opening 123 has an average diameter ranging from about 1 micrometer to about 10 micrometers, or from about 2 micrometers to about 8 micrometers. The diameter d0 of the through opening can be understood as the diameter of a cylinder having a length equal to its thickness t and a volume equal to the volume of the through opening (e.g., diameter d0 may be approximately equal to...). Figure 1 The average diameter is (d1+d2) / 2. The average diameter is the diameter d0 (unweighted average) obtained by averaging the diameters of the through-openings. The average value of d1 or d2 may also be specified or alternatively. In some embodiments, for at least one of the third main surface 143 and the fourth main surface 144, the opening end at the main surface has an average diameter in the range of about 1 micrometer to about 10 micrometers or about 2 micrometers to about 8 micrometers. The diameter of the opening end can be understood as the diameter of a circle having the same area as the opening end. The average diameter of the opening end is the diameter (unweighted average) obtained by averaging the diameters of the opening ends. In some embodiments, 0.5 ≤ d / t ≤ 2, where d is the average value of d0, d1, or d2, and t is the average thickness of the multilayer mask.

[0031] Figure 2 This is a schematic graph of the optical transmittance 267 as a function of the angle of incidence of an optical construct according to some embodiments. In some embodiments, the optical construct 200 is configured such that for substantially collimated light 133 incident on the structured first main surface side of the optical construct along an incident direction 134 forming an angle of incidence θ with the second main surface 104, the optical transmittance 267 of the optical construct 200 as a function of the angle of incidence θ includes a first transmission peak 268 having a first peak transmittance T1 and may include a corresponding 20% ​​maximum full width W1. The optical transmittance may alternatively be expressed as the transmission angle. The optical transmittance 133 is a function of the light source. For example, the substantially collimated light 133 may be collimated or nominally collimated, or may have a divergence or convergence angle of less than about 20 degrees, or less than about 10 degrees, or less than about 5 degrees. The substantially collimated light 133 may be filled or substantially filled with at least one microlens or may be filled or substantially filled with multiple microlenses. In some embodiments, T1 / W1 ≥ 2.4% / degree, or T1 / W1 ≥ 2.5% / degree, or T1 / W1 ≥ 2.6% / degree, or T1 / W1 ≥ 2.8% / degree, or T1 / W1 ≥ 3% / degree, or T1 / W1 ≥ 3.2% / degree, or T1 / W1 ≥ 3.4% / degree. In some embodiments, the optical transmittance 267 has a 20% maximum full width W1 corresponding to the first transmission peak 268, which is less than about 20 degrees, or less than about 15 degrees, or less than about 12 degrees, or less than about 10 degrees.

[0032] It has been found, for example, that characterizing optical transmittance based on the 20% maximum full width (FWHM) rather than the half-maximum full width (WHM) is useful, because the 20% maximum low full width (WHM) corresponds to improved optical properties (e.g., low crosstalk). According to some embodiments, it has been found that coated and cured monolayer masks, for example, capable of achieving substantially the same optical density as the multilayer masks described herein, typically have peaks with corresponding half-maximum full width (FWHM) and corresponding 20% ​​maximum full width (20%), wherein the 20% maximum full width (20%) is substantially larger than the FWHM and substantially larger than the 20% maximum full width (20%) of the multilayer masks described herein.

[0033] In some embodiments, the optical transmittance 267 of the optical construct 200 as a function of the angle of incidence θ includes a first transmission peak 268 having a first peak transmittance T1 and a second transmission peak 269 having a second peak transmittance T2. In some embodiments, the angle of incidence θ2 of the second transmission peak 269 is at least about 30 degrees larger than the angle of incidence θ1 of the first transmission peak 268. The second transmission peak may be the maximum transmission peak (i.e., the peak with the maximum transmittance) at an angle of incidence θ1 that is, for example, at least about 30 degrees larger and no more than about 60 degrees larger than the angle of incidence θ1 of the first transmission peak 268. The transmission angle θ2 will be understood as being at least about 30 degrees larger and no more than about 60 degrees larger than the angle of incidence θ1 of the first transmission peak 268, regardless of the sign of θ2-θ1, since a coordinate system may be chosen to reverse the signs of θ2 and θ1. The second peak may be generated at least in part, for example, by changes in the shape of the microlens caused by the process used to form the lens film (e.g., casting and curing processes).

[0034] In some embodiments, for example, T2 ≤ 3% or T2 ≤ 2.5%, or T2 ≤ 2.3%, or T2 ≤ 2%, or T2 ≤ 1.5%, or T2 ≤ 1%. In some such embodiments, or in other embodiments, for example, T1 / T2 ≥ 10, or T1 / T2 ≥ 12, or T1 / T2 ≥ 15, or T1 / T2 ≥ 18, or T1 / T2 ≥ 20. In some embodiments, T2 is at least about 0.1%, or at least about 0.25%, or at least about 0.5%. In some embodiments, T1 ≥ 15% or T1 ≥ 20%, or T1 ≥ 25%, or T1 ≥ 30%, or T1 ≥ 35%, or T1 ≥ 40%. Higher T1 (e.g., T1 ≥ 35%, or T1 ≥ 40%) may be desirable in some embodiments, while higher optical density (e.g., greater than about 2.5) may be desirable in some embodiments (e.g., to reduce crosstalk) and this may result in a lower (e.g., about 20% or about 25%) but still useful T1.

[0035] For any angle of incidence along an in-plane direction (orthogonal to the thickness direction (z-direction) of the optical structure), the optical transmittance as a function of that angle of incidence can be determined. The angle of incidence along an in-plane direction can also be alternatively described as the angle of incidence defined in a plane encompassing both the in-plane and thickness directions. Figure 1 In this context, the incident angle θ is along the x-direction (or defined in the xz plane). The optical transmittance as a function of the incident angle can depend on the chosen in-plane direction. For example, a graph of optical transmittance as a function of the incident angle along a first in-plane direction (e.g., the x-direction) can differ from a graph of optical transmittance as a function of the incident angle in a second in-plane direction (e.g., the y-direction) at different (e.g., differing by 30 degrees or 90 degrees). For example, for a hexagonal array of microlenses, the graph can be substantially the same along the directions between the nearest adjacent microlenses at 60 degrees to each other, but different along other directions in between. In embodiments where the lens film is manufactured using a roll-to-roll process, for example, the first direction can be the web transverse direction and the second direction can be the web longitudinal direction. For example, for the incident angle along the web longitudinal direction, a second transmission peak 269 of optical transmittance may exist, but for the incident angle along the web transverse direction, it does not exist (see example...). Figure 9 If the condition for optical transmittance as a function of the angle of incidence along at least one in-plane direction is satisfied, then quantities such as T1, T2, W1, or T1 / W1 can be described as satisfying that condition. Any condition described herein for T1, T2, W1, or T1 / W1 may apply to one in-plane direction, or to each of at least two non-collinear in-plane directions (e.g., defining an angle of about 30 degrees or about 90 degrees between them), or to each of two orthogonal in-plane directions, or to all in-plane directions.

[0036] Figures 3A to 3B This is a schematic top-view projection of an optical structure including a plurality of microlenses 103 and a through opening 123 according to some embodiments. The microlenses 103 are arranged along orthogonal first and second directions (e.g., the x and y directions), and the opening 123 is arranged along the first and second directions. Figure 3A In the illustrated embodiment, the microlens 103 and the opening 123 are centered along a straight line substantially perpendicular to the lens layer (i.e., substantially along the z-direction). Figure 3B In the embodiment shown, the microlens 103 and the opening 123 are centered along a straight line, so that they are at substantially the same angle as the lens layer. Figure 3A The optical structure is suitable for transmitting light incident on the optical structure primarily along its thickness direction (z-direction), while Figure 3B The optical construct is adapted to transmit light incident on it primarily along a direction at an angle to the thickness direction. In the illustrated embodiment, the microlens 103 and the opening 123 are located on a regular triangular array. Other patterns are also possible (e.g., square or rectangular arrays, other periodic arrays, or irregular patterns).

[0037] Figures 4A to 4BThis is a schematic diagram of multilayer masks 222 and 223 according to some embodiments. Either multilayer mask 222 or 223 may correspond to multilayer mask 120. Each of multilayer masks 222 and 223 includes a first mask layer and second mask layers 222a and 222b having average thicknesses ta and tb. In some embodiments, the first mask layer 222a is disposed between the lens film 110 and the second mask layer 222b. In some embodiments, the second mask layer 222b is disposed between the lens film 110 and the first mask layer 222a. In some embodiments, the second mask layer 222b is thicker than the first mask layer 222a. In some embodiments, the first mask layer 222a is thicker than the second mask layer 222b, and the optical density of the second mask layer 222b is greater than the optical density of the first mask layer 222a. For example, the second mask layer 222b may be a relatively thin layer with a relatively high optical density, formed, for example, by layer-by-layer deposition, and the first mask layer 222a may be a relatively thick layer with a relatively low optical density (e.g., due to the relatively low concentration of optical absorbing material), formed by solvent deposition. In some embodiments, tb is less than about 0.5ta, or less than about 0.25ta, or less than about 0.2ta, or less than about 0.15ta, or less than 0.1ta. In some such embodiments or in other embodiments, tb is greater than about 50 nm and tb is less than about 10 micrometers. In some embodiments, the first mask layer 222a is a solvent-deposited mask layer or includes a solvent-deposited mask layer. In some such embodiments or in other embodiments, the second mask layer 222b comprises a first material and a second material (e.g., polymers and nanoparticles), the first material and the second material comprising corresponding first binding groups and second binding groups, wherein the first binding groups and the second binding groups have complementary interactions (e.g., functional groups with opposite charges). Such a layer may be deposited via layer-by-layer self-assembly as further described elsewhere herein.

[0038] Multilayer masks or mask layers can be characterized by their optical density, which can be expressed as a negative logarithm to base 10 of [transmittance / 100%], where the transmittance is the average transmittance for unpolarized, vertically incident light (incident between the through-holes) in a wavelength range of at least 400 nm to 600 nm, unless otherwise indicated. The wavelength range can be, for example, from 400 nm to 700 nm, or 400 to 800, or 400 to 900, or 400 nm to 1100 nm. (The transmittance of light incident from any direction can be measured). Multilayer masks 120, 222, or 224 can have an optical density, for example, greater than about 2, or greater than about 2.5, or greater than about 2.8, or greater than about 3. Each of the first and second mask layers can have an optical density, for example, greater than about 0.3, or greater than about 0.4, or greater than about 0.5.

[0039] In some embodiments, at least one of the first mask layer 222a and the second mask layer 222b absorbs at least 30%, or at least about 50%, or at least about 70%, or at least about 80% of substantially perpendicularly incident light with a wavelength λ in the range of λ1 to λ2. In some embodiments, λ1 is about 400 nm or about 450 nm, and λ2 is about 3000 nm, or about 2500 nm, or about 2000 nm, or about 1600 nm, or about 1500 nm, or about 1100 nm, or about 800 nm, or about 700 nm, or about 650 nm, or about 600 nm. In some embodiments, λ1 is about 700 nm, or about 750 nm, or about 780 nm, or about 800 nm, and λ2 is about 3000 nm, or about 2500 nm, or about 2000 nm, or about 1600 nm, or about 1500 nm, or about 1100 nm. In some embodiments, the at least one wavelength includes at least one visible wavelength (e.g., in the range of about 400 nm to about 700 nm) and / or at least one near-infrared wavelength (e.g., in the range of about 750 nm to about 3000 nm, or about 800 nm to about 1600 nm, or about 800 nm to about 1100 nm). For typical applications, it is generally desirable for the mask to absorb at least in the visible light range. For example, it may also be desirable for multilayer masks to absorb infrared light to facilitate laser ablation. The first mask layer 222a and the second mask layer 222b may have substantially the same absorption spectrum or may have different absorption spectra, as further described elsewhere herein.

[0040] Any of the multilayer masks or mask layers described herein may have a substantially uniform optical density. A substantially uniform optical density means an optical density that is uniform to a good approximation over a length scale of about 1 micrometer. For example, each cylindrical region of a mask layer or multilayer mask passing through a through-hole with a diameter of about 1 micrometer may have an optical density within about 15%, about 10%, or about 5% of the average optical density of such regions. In some embodiments, the mask layer has a substantially uniform optical density obtained by using optically absorbing particles (e.g., carbon black particles) with an average diameter substantially less than 1 micrometer (e.g., less than about 300 nm or less than about 250 nm) and substantially uniformly dispersed in the layer with a sufficiently high fill weight such that the average center-to-center spacing between the particles is less than about 1 micrometer.

[0041] Figures 5A to 5F A method for manufacturing an optical construct according to some embodiments is schematically illustrated. The method includes: providing a lens film 110 (see, for example...) Figure 5AThe lens film includes an outermost structured first main surface 102 and an outermost, substantially flat second main surface 104 opposite to it, wherein the structured first main surface 102 includes a plurality of microlenses 103 arranged along orthogonal first and second directions; coated with a mixture 150 of solvent 151, polymer 152 and optical absorption material 153 (see, for example...). Figure 5B The second primary surface of the lens film; drying the coated mixture (see, for example) Figures 5B to 5C The method involves forming a first mask layer 120a having an average thickness ta (e.g., less than about 10 micrometers) and an optical density greater than about 0.3 or within any range described elsewhere herein (e.g., substantially uniform). Alternatively, the first mask layer can be formed by coating a resin filled with an optically absorbing material and curing the resin. The method may also include depositing a second mask layer 120b having an average thickness ta (e.g., less than about 10 micrometers) and an optical density greater than about 0.3 or within any range described elsewhere (e.g., substantially uniform). The second mask layer 120b can be deposited directly on the second main surface 104, such as... Figure 5D The diagram schematically illustrates that the first mask layer 120a is subsequently deposited on the second mask layer 120b, or the second mask layer 120b can be deposited on the first mask layer 120a, as shown below. Figure 5F The diagram is schematically shown. A first mask layer 120a and a second mask layer 120b define a multilayer mask 120 having a combined average thickness t, which may be less than about 10 micrometers or less than about 0.5 times the average focal length f of the microlens 103, or may be within any range described elsewhere herein.

[0042] The first mask layer 120a may be a solvent-deposited mask layer. In some such embodiments, the first mask layer 120a may include an optically absorbing material such as carbon black particles dispersed in a thermoplastic polymer. A related solvent-deposited mask layer is described in U.S. Patent Application No. 63 / 040056, entitled "Optical Construction Including Lens Film and Mask Layer," filed June 17, 2020.

[0043] Various polymer systems can serve as carrier resins (resins to be deposited in solvent systems). For example, nitrocellulose and cellulose esters are useful polymers. Medium to high molecular weight hydroxyl-functionalized, partially hydrolyzed vinyl chloride-vinyl acetate copolymers can also be used as carrier resins. For alcohol-rich solvent systems, polyvinyl butyral may be useful or preferred. Depending on the solvent mixture, substrate selection, desired adhesion, etc., polyamides, ethyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, polyurethanes, maleic acid resins, epoxy resins, acrylics, and vinyl acrylates may also be useful or preferred. Suitable cellulose esters are available, for example, from Eastman Chemical Company. Suitable polyurethanes are available, for example, under the trade name VERSAMID PUR. Suitable polyvinyl butyral polymers are available, for example, under the trade name MOWITAL from Kuraray America. Suitable acrylate copolymers are available, for example, under the trade name PARALOID from Dow Chemical Company. Other polymers that may be useful in some cases include polyurethanes and silanes or silsesquioxanes. Other polymers that are soluble or dispersible in solvent systems and can form a film after drying can also be used.

[0044] Suitable solvents include alcohols, ketones, esters, hydrocarbons, glycols, glycol ethers, and glycol esters. Some of these solvents may be high-boiling and may be present in small amounts in the coating solution. High-boiling hydrocarbons, naphtha, and aromatics may also optionally be present in small amounts. Although not usually intentionally added, small amounts of water or moisture may be present in some polar solvents. Nitriles, aminoethanols, and amines may also be used as co-solvents. Preferred solvents can be determined by resin selection as well as process type and conditions (e.g., temperature). Typical preferred solvents include ketones and low-boiling alcohols.

[0045] The second mask layer 120b may include a first material and a second material (e.g., nanoparticles and polymers with opposite charges), the first material and the second material including corresponding first binding groups and second binding groups, wherein the first binding groups and the second binding groups have complementary interactions. The second mask layer 120b may be deposited by layer-by-layer (LbL) self-assembly. Layer-by-layer self-assembly is known in the art and may include, for example, layer-by-layer spray deposition as described in U.S. Patent No. 8,234,998 (Krogman et al.); or layer-by-layer deposition techniques as described in International Application Publication No. WO 2019 / 0186397 (Schmidt et al.). LbL processes are commonly used for the electrostatic assembly of films or coatings of polyelectrolytes with opposite charges, but other functionalities such as hydrogen-bonded donor / acceptor, metal ion / ligand, and covalently bonded moieties can also be driving forces for film assembly. Typically, this deposition process involves exposing a substrate with a surface charge to a series of liquid solutions. This can be achieved, for example, by immersing the substrate in a liquid bath (also known as dip coating), spraying, spin coating, roll coating, or inkjet printing. Exposure to a first polyionic liquid solution (where the polyions have an opposite charge to the substrate) causes rapid adsorption of charged substances near the substrate surface, forming a concentration gradient and drawing more polyelectrolytes from the bulk solution to the surface. Further adsorption occurs until a sufficient layer has developed to mask the underlying charge and reverse the net charge on the substrate surface. The substrate is then exposed to one or more water rinsing steps to remove any physically entangled or loosely bound polyelectrolytes. After rinsing, the substrate is then exposed to a second polyionic liquid solution where the polyions have an opposite charge to the first polyions. Again, adsorption occurs because the surface charge of the substrate is opposite to the charge of the polyions in the second liquid solution. Continued exposure to the second polyionic liquid solution leads to a reversal of the surface charge on the substrate. Subsequent rinsing can be performed to complete the cycle. This series of steps is called building a layer pair, also known as a deposited “bilayer,” and can be repeated as needed to add additional layer pairs to the substrate. Multicationic layers may comprise multicationic polymers or nanoparticles. Similarly, the multi-anion layer may include multi-anion polymers or nanoparticles.

[0046] In some embodiments, the first binding group and the second binding group have complementary interactions. These complementary interactions can be complementary electrostatic interactions or complementary hydrogen bonding interactions between hydrogen bond donors and acceptors. If the polymer, nanoparticles, and small molecules contain multiple negatively or positively charged sites, they may be referred to as “multiionic” or “multi-ionic,” or specifically, “multi-anionic,” “multi-anionic,” “multi-cationic,” or “multi-cationic.”

[0047] In some embodiments, at least one of the first material or the second material comprises a polyelectrolyte. For example, in some embodiments, the first material comprises a polyelectrolyte and the second material comprises nanoparticles. In some embodiments, the first material comprises a polyanion and the second material comprises a polycation, although in other embodiments, the first material comprises a polycation and the second material comprises a polyanion. In some embodiments, the polyelectrolyte is a polycation.

[0048] In some embodiments, the polycation is a polycationic polymer. Suitable polycationic polymers may include, but are not limited to, members of poly(diallyldimethylammonium chloride) (PDAC), linear and branched poly(ethyleneimine) (PEI), poly(allylamine hydrochloride) (PAH), polyethyleneamine, deacetylated chitosan, polyaniline, polyamide amine, poly(vinylbenzyltrimethylamine), and polyquaternary ammonium salt groups. In some embodiments, the polyelectrolyte is a polyanionic polymer. Suitable polyanionic polymers include, but are not limited to, sulfonated polystyrene (PSS), poly(vinyl sulfate), poly(vinyl sulfonate), poly(acrylic acid), poly(methacrylic acid), dextran sulfate, heparin, hyaluronic acid, carrageenan, carboxymethyl cellulose (CMC), alginate, sulfonated tetrafluoroethylene-type fluoropolymers such as perfluorosulfonic acid (NAFION), poly(vinyl phosphate), poly(vinyl phosphonic acid), and sodium hexametaphosphate. In some embodiments, the polycation is selected from the group consisting of: polydiallyldimethylammonium chloride, polyethyleneimine, polyallylamine, poly(2-(trimethylamino)ethyl methacrylate) and copolymers thereof.

[0049] The polyelectrolyte organic polymers just described can be characterized as polymers having (e.g., repeating) polymeric units carrying ionic or ionizable groups. These groups dissociate in aqueous solution (water), causing the polymer to become charged. Other types of polymers having multiple ionic groups capable of electrostatic interaction are aqueous dispersions of organic polymers. In some embodiments, these polymers also contain polymeric units containing ionic or ionizable groups. However, the concentration of such groups is significantly low, allowing the organic polymer to be dispersed in aqueous solution but not to dissolve to form a solution. Therefore, such organic polymers can be characterized as insoluble in water. In other embodiments, the organic polymer can be given water dispersibility by using ionic surfactants. Examples of commercially available aliphatic acrylic dispersions include cationic acrylic latexes available under the trade names RAYCAT 65124 and PICASSIAN AC-181. Examples of commercially available aqueous polyurethane dispersions include aliphatic polyether cationic polyurethane polymer dispersions available under the following trade names: SANCURE 20051 (also known as PRANTRITE DP675); SANCURE 20072 (also known as PRANTRITE DP676); and WITCOBOND UCX-214.

[0050] In some embodiments, the aqueous solution or dispersion further includes a "masking agent," which is an additive that promotes uniform and reproducible deposition by increasing ionic strength and reducing electrostatic repulsion between particles. Suitable masking agents include any low molecular weight salt, such as halide salts, sulfates, nitrates, phosphates, fluorophosphates, etc. Examples of halide salts include: chloride salts such as LiCl, NaCl, KCl, CaCl2, MgCl2, NH4Cl, etc.; bromide salts such as LiBr, NaBr, KBr, CaBr2, MgBr2, etc.; iodide salts such as LiI, NaI, KI, CaI2, MgI2, etc.; and fluoride salts such as NaF, KF, etc. Examples of sulfates include Li2SO4, Na2SO4, K2SO4, (NH4)2SO4, MgSO4, CoSO4, CuSO4, ZnSO4, SrSO4, Al2(SO4)3, and Fe2(SO4)3. Organic salts such as (CH3)3CCl and (C2H5)3CCl are also suitable masking agents. The appropriate masking agent concentration can vary with the ionic strength of the salt. In some embodiments, the aqueous solution or dispersion includes a masking agent (e.g., NaCl) at a concentration in the range of 0.01 M to 0.2 M. A second masking layer may contain trace amounts of the masking agent.

[0051] Figure 5EThis is a schematic diagram of a double layer comprising a first material 333 and a second material 334. The first material 333 and the second material 334 have corresponding first binding groups 433 and second binding groups 434, wherein the first binding groups 433 and the second binding groups 434 have complementary interactions (opposite charges in the illustrated embodiment). Figure 5E In the schematically illustrated embodiment, the first material 333 is a cationic polymer, and the second material 334 is a plurality of ionic nanoparticles. In other embodiments, the polymer may be ionic, and the nanoparticles may be cationic. Charged nanoparticles may have a charge in the nanoparticle bulk or on surface groups or dispersants on the nanoparticle surface. Multiple bilayers (e.g., 2 to 20, or 3 to 10) may be deposited to provide the desired optical density. In embodiments where the first material 333 is a polymer, the resulting mask layer can be considered as a polymer mask layer, since the polymer bilayer typically extends at least across the length and width of the mask layer. Layer-by-layer deposition can produce a mask layer with a high density of nanoparticles. In some embodiments, the second mask layer contains at least about 50, or at least about 60, or at least about 70, or at least about 75, or at least about 80% by weight of nanoparticles. Useful nanoparticles include, for example, those described in International Application Publication No. WO 2019 / 0186397 (Schmidt et al.). In some embodiments, the nanoparticles include carbon black nanoparticles, metal oxide nanoparticles, or combinations thereof. The nanoparticles may have an average particle size (e.g., Dv50) in the range of about 5 nm to about 300 nm.

[0052] The method also includes using a laser 177 that emits infrared light 178 incident on the structured first primary surface 102 of the lens film 110 to ablate the multilayer mask 120. Figure 5F The diagram schematically illustrates multiple through openings 123 in a multilayer mask 120 prior to ablation (see example...). Figure 5F and Figure 1The through opening 123 is arranged along a first direction and a second direction and aligned with the microlens 103 in a one-to-one correspondence. The infrared light 178 may have a wavelength in, for example, the range of about 1020 nm to about 1100 nm, or any range described elsewhere herein. For example, the infrared light 178 may have a wavelength at a peak intensity of about 1064 nm. The infrared light 178 may have a beam diameter that fills or substantially fills at least one microlens. For example, the microlens may have an average diameter in the range of 5 to 50 micrometers, and the beam diameter may be in the range of 100 to 500 micrometers. The optical absorbing material 153 is preferably optically absorbing for the wavelength range of the infrared light 178 and for the visible light wavelength range (e.g., at least from about 450 nm to about 650 nm). The optical absorbing material 153 includes optical absorbing materials 153a and 153b, which may have the same or different compositions. For example, the optical absorbing material 153 may include one, two, or more optically absorbing pigments and / or dyes that can absorb in different wavelength ranges. For example, the first mask layer 120a (see example) Figure 5C The optically absorbing material 153 may include at least one optically absorbing dye and at least one optically absorbing pigment. The optically absorbing material 153 may be optically absorbing for visible wavelengths and for infrared light 178, such that the optically absorbing material 153 absorbs infrared light 178 to perform ablation and provide the desired optical density to the resulting mask layer. Suitable optically absorbing materials 153 include carbon black. In some embodiments, the optically absorbing material 153 includes nanoparticles, such as carbon black or metal oxide nanoparticles.

[0053] A coherent pulsed light source (e.g., a laser) with a wavelength ranging from 350 nm to 1600 nm, or from 400 nm to 1200 nm, or from 500 nm to 1100 nm, or from 1000 nm to 1100 nm, or from 1020 nm to 1100 nm can be used to form the through-aperture. For example, the light source could be a doped fiber laser that produces a near-infrared (NIR) band wavelength of about 1020 nm to about 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, a 1 st 2 nd Or 3 rd Harmonics. The desired wavelength range of the laser can depend on the polymer and optically absorbing materials used in the mask layer. For example, the use of a laser to form holes in a layer through a microlens array is broadly described in U.S. Patent Application Publication No. 2007 / 0258149 (Gardner et al.).

[0054] Figure 6This is a schematic graph of optical absorption versus wavelength according to some embodiments. Optical absorption spectra 391 and 392 are shown. Absorption-to-wavelength curves that differ only on a general scale will be considered the same absorption spectrum, while absorption-to-wavelength curves with different wavelength dependencies will be considered different absorption spectra. In some embodiments, the first mask layer and / or the second mask layer includes at least a first optical absorbing material and a second optical absorbing material (e.g., 153a and 153b), wherein the first optical absorbing material and the second optical absorbing material have different optical absorption spectra (e.g., spectra 391 and 392). For example, one of the optical absorbing materials may absorb more strongly in the visible wavelength range, while the other may absorb more strongly in the near-infrared wavelength range. In some embodiments, the first mask layer and the second mask layer have different optical absorption spectra (e.g., spectra 391 and 392). In some embodiments, the different spectra result in high absorption, for example, in the wavelength range of at least 400 nm to 1100 nm (e.g., at least about 75% for substantially perpendicular incident light).

[0055] The optical construct 200 may include optional additional elements or layers disposed on the lens film 110 opposite to the multilayer mask 120 and / or disposed on the multilayer mask 120 opposite to the lens film 110. For example, a low refractive index layer may be disposed on the lens film 110, or the lens film 110 may include an optical decoupling structure, and / or a wavelength-selective optical filter may be disposed on the multilayer mask 120 opposite to the lens film 110. Examples of such layers or structures can be described, for example, in International Application Publication No. WO2020 / 035768 (Yang et al.).

[0056] 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 102 of the lens film 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.).

[0057] In some embodiments, the lens film 110 further includes an optical decoupling structure that can be disposed between adjacent microlenses. The optical decoupling structure can be any object protruding beyond the microlenses to attach to adjacent layers such that the adjacent layers do not contact the microlenses. The optical decoupling structure can be a cylindrical pillar, or it can be a pillar with 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.

[0058] Example

[0059] Unless otherwise stated, all portions, percentages, and ratios reported in the following examples are based on weight.

[0060] Material

[0061]

[0062] Solvents and reagents not listed in the table above are available from Sigma-Aldrich Co. (St. Louis, Missouri).

[0063] IR dispersion 1

[0064] IR dispersion 1 is a dispersion of potassium tungsten oxide nanoparticles prepared by the process described in Comparative Example B (CE-B) of International Application Publication No. WO 2020 / 016755 (Sharma et al.).

[0065] Coating solution 1

[0066] A 16 wt% solution of CAP-504-0.2 in a DOWANOL PM:MEK blend (40:60 wt) was mixed with 2.8 g of IR dispersion 1 (40 wt% solution in DOWANOL PM) and 0.44 g of ORASOL Black X55. Then, 1 g of methyl ethyl ketone (MEK) and 1 g of DOWANOL PM were added, and the resulting mixture was homogenized using a vortex mixer.

[0067] Coating solution 2

[0068] A 17.3 wt% solution of CAP-504-0.2 in a DOWANOL PM:MEK blend (60:40 wt) was mixed with 28 g of IR dispersion 1 (40 wt% solution in DOWANOL PM) and 4.8 g of ORASOL Black X55 dissolved in 10.8 g of MEK. 27.4 g of methyl ethyl ketone (MEK) and 2.2 g of DOWANOL PM were then added, and the resulting mixture was homogenized using a vortex mixer.

[0069] Paint solution 3 (LbL paint solution)

[0070] Paint solution 3 was prepared by diluting SC20072 from 27 wt% solids to 1 wt% solids with deionized (DI) water after adding NaCl to a concentration of 200 mM. EXPCB paint solution was prepared by diluting EXPCB from 30 wt% solids to 1.0 wt% solids with DI water after adding NaCl to a concentration of 50 mM. PL92 was added to each paint solution to a concentration of 0.1 wt%. Paint solutions were prepared in batches of 1 kg each.

[0071] Method for preparing sprayed layer-by-layer (LbL) self-assembled coatings

[0072] The equipment used was purchased from Svaya Nanotechnologies, Inc. (Sunnyvale, CA), and was modeled after the system described in U.S. Patent No. 8,234,998 (Krogman et al.) and Krogman et al., “Automated Process for Improved Uniformity and Versatility of Layer-by-Layer Deposition,” Langmuir 2007, 23, 3137-3141. The equipment included a pressure vessel containing a coating solution. A spray nozzle with a flat spray pattern (purchased from Spraying Systems, Inc., Wheaton, Illinois) was installed to spray the coating solution and rinsing water at specified times controlled by a solenoid valve. The pressure vessel containing the coating solution (Alloy Products Corp., Waukesha, WI) was pressurized to 30 psi with nitrogen, while the pressure vessel containing deionized (DI) water was pressurized to 30 psi with air. The flow rate of the coating solution nozzles was 10 gallons / hour, while the flow rate of the DI water rinsing nozzles was 40 gallons / hour. The substrate to be coated (9" × 10") was adhered at the edges to a glass plate (12" × 12" × 1 / 8" thick) (Brin Northwestern Glass, Minneapolis, Minnesota) using epoxy resin (Scotch-Weld epoxy adhesive, DP100 Clear, 3M Company, St. Paul, MN). (Co., Minneapolis, MN) The glass plate is mounted on a vertically translating stage and held in place by a vacuum chuck. In a typical coating sequence, a polycationic solution (coating solution 3) is sprayed onto the substrate while the stage moves vertically downward at 76 mm / s. Then, after a 12-second holding time, DI water is sprayed onto the substrate while the stage moves vertically upward at 102 mm / s. The substrate is then dried with an air knife at 3 mm / s. Next, a polyanionic solution (e.g., EXPCB carbon black nanoparticles) is sprayed onto the substrate while the stage moves vertically downward at 76 mm / s. Another 12-second holding time is allowed. DI water is sprayed onto the substrate while the stage moves vertically upward at 102 mm / s. Finally, the substrate is dried with an air knife at 3 mm / s. The above sequence is repeated to represent deposition as (polycationic / polyanionic). nMultiple "double layers" are used, where n is the number of double layers. A coated substrate (e.g., a polymer film) is peeled off from the glass, followed by subsequent processing. The coating on the glass is retained for thickness, optical transmittance, and surface resistivity measurements.

[0073] Examples 1-2

[0074] A lens film was prepared by casting acrylate resin onto a polyethylene terephthalate (PET) substrate and curing the resin in contact with a replication tool to form a hexagonal array of microlenses with a diameter of 20 micrometers. A first mask layer was formed as follows: paint solution 1 was applied to the side of the PET substrate opposite the microlenses using a Meyer rod #10. The coating was dried in a hot air oven at 70°C for 5 minutes. A second mask layer was deposited as described in "Method for Making Spray layer-by-Layer (LbL) Self-Assembled Coatings". Three (Example 1) or six (Example 2) bilayers were deposited, each bilayer consisting of an anionic carbon black layer and a cationic polymer layer.

[0075] A through-hole was formed in the resulting multilayer mask via laser ablation through a microlens. A 40W pulsed fiber laser (SPI Lasers, UK) operating at 1070nm wavelength was used with the following parameters: scan speed: 2 m / s; line spacing: 100 μm; pulse length: 250 ns; repetition rate: 20 kHz; and laser power: 15%–25%. A strong and high-quality beam was generated by the laser. The fiber laser was protected from back reflection using a Faraday optical isolator mounted at the end of the beam delivery fiber. The laser beam diameter after passing through the beam expander was approximately 10 mm. The beam was guided to a commercially available laser scanning head (hurrySCAN III 14) with dielectric mirrors, obtained from SCANLAB AG (Germany). After being reflected downwards by a pair of galvanometer mirrors, the beam was finally focused by an F-Theta telecentric focusing lens. A 167 mm focal length focusing lens was used in the ablation experiment. Mount the scanner onto the manual Z-stage to control its position in the Z direction.

[0076] Examples 3-4

[0077] Examples 3 and 4 are prepared according to Examples 1-2, respectively, except that the second mask layer (LbL deposited mask layer) is deposited on the side of the PET substrate opposite to the microlens, and then the first mask layer (solvent deposited mask layer) is deposited on the second mask layer.

[0078] Examples 5-6

[0079] Coating solution 2 was delivered to a tank coating mold at a flow rate of 43.3 cc / min using a Zenith BPB pump with a pump rate of 1.168 cc / rev for a 6" wide coating on the back side of a 9" wide, 0.92 mil thick transparent PET film with 20-micron microlens features. Based on the above flow rate, the dry coating thickness at a linear velocity of 30 ft / min was estimated to be approximately 3 microns. After the coating solution, the coated web was first passed through a 10-ft long, two-zone gap dryer to minimize airflow-induced spot defects. Both gap drying zones were maintained at ambient temperature. Immediately following the gap dryer was a three-zone air flotation oven equipped with top and bottom air bars to dry all volatile solvents and cool the coating temperature in the final zone. Each drying zone was approximately 2 meters long. The temperatures of zones 1, 2, and 3 were set to 150, 175, and 200°F, respectively. The optical density of the coating was measured to be 2.2 using an X-Rite Gretag Macbeth D200-II 36.51.03 transmission densitometer.

[0080] The second mask layer was deposited as described in "Method for Making Spray layer-by-Layer (LbL) Self-Assembled Coatings". Three (Example 5) or six (Example 6) bilayers were deposited, each consisting of an anionic carbon black layer and a cationic polymer layer. For Examples 5 and 6, the optical densities of the final coatings after LBL deposition, measured using an X-Rite Gretag Macbeth D200-II 36.51.03 transmission densitometer, were 3.0 and 3.9, respectively.

[0081] The through-holes in the resulting multilayer mask were formed via laser ablation through a microlens as generally described in Examples 1-2, except that a 40W pulsed fiber laser (SPI Lasers, UK) operating at a wavelength of 1070 nm was used with the following parameters: scan rate: 2 m / s; line spacing: 70 μm; pulse length: 30 ns; repetition rate: 30 kHz; and laser power: 15%-25%. The focus was adjusted to a few millimeters above the sample to optimize laser ablation.

[0082] Comparative Example C1

[0083] Comparative Example C1 was prepared as described in Examples 1-2, except that the second mask layer (the mask layer for LbL deposition) was omitted.

[0084] Comparative Example C2

[0085] Comparative Example C2 was prepared as described in Examples 5-6, except that the second mask layer (the mask layer for LbL deposition) was omitted. The optical density of the coating was measured to be 2.2 using an X-Rite Gretag Macbeth D200-II 36.51.03 transmission densitometer.

[0086] Comparative examples C3-C4

[0087] Comparative Examples C3-C4 were prepared by coating three bilayers (C3) and six bilayers (C4) with only LBL. No other mask layers were deposited. For Comparative Examples C3 and C4, the optical densities of the LBL-only coatings were measured to be 0.74 and 1.64, respectively, using an X-Rite Gretag Macbeth D200-II 36.51.03 transmission densitometer.

[0088] Comparative Example C5

[0089] The mask layer was formed from a UV-curable formulation comprising 15 parts carbon black, 60 parts isobornyl acrylate, 25 parts EBECRYL 4396, and 3 parts IRGACURE 819, as follows. As described in Examples 1-2, this UV-curable 100% solid formulation was coated onto the flat side of the lens film. The design conditions resulted in a coating thickness of approximately 5 micrometers. The coating was cured using a medium-pressure mercury UV "D-type" light source. Through-holes were laser-ablated through the resulting mask layer, roughly as described in Examples 1-2.

[0090] The absorptivity of the mask layer for various samples was determined as follows: First, transmittance and reflectance curves were measured using a HunterLab spectrometer (Hunter Associates Laboratory, Reston, VA), and the absorptivity was calculated as 100% - transmittance - reflectance using the results. Figure 7 This is a graph of the obtained absorbance against wavelength. Negative values ​​of absorbance are a result of measurement error in samples with absorbance close to zero. The absorbance was measured before laser ablation.

[0091] Following laser ablation, the angular transmittance of various samples was measured using a custom goniometer system comprising a collimated light source and a silicon detector. The light source consisted of a green LED with an emission wavelength of 530 nm attached to the collimating lens; both were from Thorlabs. The light source was stationary and had a fixed illumination angle. The silicon detector, with a photosensitive area of ​​20 mm × 20 mm, was also purchased from Thorlabs. After the microlens sample was clamped to the silicon detector, it was rotated together with the detector along two orthogonal axes, and the optical transmittance of the sample was calculated based on the measured power transfer. The results for Comparative Example C5 are shown in... Figure 8In Example 5, the results are shown in Figure 9 In Comparative Example C5, the peak transmittance T1 divided by 20% of the maximum full width W1 is 2.27% / degree in the transverse (CW) direction and 2.09% / degree in the longitudinal (DW) direction. In Example 5, the peak transmittance T1 divided by 20% of the maximum full width W1 is 3.57% / degree in the transverse (CW) direction and 2.50% / degree in the longitudinal (DW) direction.

[0092] 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.

[0093] 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.

[0094] 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 structure comprising: The lens film includes an outermost structured first main surface and an opposite outermost substantially flat second main surface, the structured first main surface including a plurality of microlenses arranged along an orthogonal first and second direction; as well as A polymer multilayer mask is disposed on the second main surface of the lens film. The multilayer mask has an average thickness less than 0.5 times the average focal length of the microlens and an optical density greater than 2. The multilayer mask includes a first mask layer and a second mask layer of polymer, each of which has an optical density greater than 0.

3. The multilayer mask defines a plurality of laser ablation through openings arranged along a first direction and a second direction. The through openings are aligned with the microlens in a one-to-one correspondence such that: for substantially collimated light incident on the structured first main surface side of the optical construct along an incident direction forming an incident angle with the second main surface, the optical transmittance of the optical construct as a function of the incident angle includes a first transmission peak having a first peak transmittance T1 and a corresponding 20% ​​maximum full width W1, T1 / W1 ≥ 2.4% / degree.

2. The optical construct according to claim 1, wherein the second mask layer comprises a first material and a second material, the first material and the second material comprising corresponding first binding groups and second binding groups, the first binding groups and the second binding groups having complementary interactions.

3. The optical construct according to claim 1 or 2, wherein the first mask layer comprises a solvent-deposited mask layer.

4. The optical structure according to any one of claims 1 to 3, wherein the first mask layer is disposed between the lens film and the second mask layer.

5. The optical structure according to any one of claims 1 to 3, wherein the second mask layer is disposed between the lens film and the first mask layer.

6. The optical structure according to any one of claims 1 to 5, wherein the first mask layer and the second mask layer have corresponding first average thickness ta and second average thickness tb, tb being less than 0.5ta.

7. The optical structure according to any one of claims 1 to 6, wherein the optical transmittance of the optical structure further includes a second transmission peak having a second peak transmittance T2, wherein the second transmission peak is the maximum transmission peak for an incident angle at least 30 degrees greater and not more than 60 degrees greater than the first transmission peak, and T2 ≤ 3%.

8. An optical construct, the optical construct comprising: The lens film includes an outermost structured first main surface and an opposite outermost substantially flat second main surface, the structured first main surface including a plurality of microlenses arranged along an orthogonal first and second direction; as well as A polymer multilayer mask is disposed on the second main surface of the lens film. The multilayer mask has an average thickness less than 0.5 times the average focal length of the microlens and an optical density greater than 2. The multilayer mask includes a first mask layer and a second mask layer of polymer, each of which has an optical density greater than 0.

3. The multilayer mask defines a plurality of laser ablation through openings arranged along the first and second directions. The through openings are aligned with the microlens in a one-to-one correspondence such that: for substantially collimated light incident on the structured first main surface side of the optical construct along an incident direction forming an incident angle with the second main surface, the optical transmittance of the optical construct as a function of the incident angle includes a first transmission peak having a first peak transmittance T1 and a second transmission peak having a second peak transmittance T2, the second transmission peak being the maximum transmission peak at an incident angle at least 30 degrees and no more than 60 degrees greater than the first transmission peak, T2 ≤ 3%, T1 / T2 ≥ 10.

9. The optical construct according to claim 8, wherein the optical transmittance has a maximum full width W1 of less than 20 degrees corresponding to the first transmission peak.

10. The optical construct according to any one of claims 8 to 9, wherein the second mask layer comprises a first material and a second material, the first material and the second material comprising corresponding first binding groups and second binding groups, the first binding groups and the second binding groups having complementary interactions.

11. An optical construct comprising: The lens film includes an outermost structured first main surface and an opposite outermost substantially flat second main surface, the structured first main surface including a plurality of microlenses arranged along an orthogonal first and second direction; as well as A multilayer mask is disposed on the second main surface of the lens film. The multilayer mask has an average thickness less than 0.5 times the average focal length of the microlens and an optical density greater than 2. The multilayer mask defines a plurality of laser ablation through-holes arranged along a first direction and a second direction, the through-holes being aligned with the microlens in a one-to-one correspondence. The multilayer mask includes a first mask layer and a second mask layer of polymer. The first mask layer and the second mask layer include a first material and a second material, the first material and the second material including corresponding first binding groups and second binding groups, the first binding groups and the second binding groups having complementary interactions, and each of the first mask layer and the second mask layer having an optical density greater than 0.

3.

12. The optical construct of claim 11, wherein the first material comprises a charged polymer and the second material comprises nanoparticles with opposite charges, and the second mask layer comprises at least 50% by weight nanoparticles.

13. The optical structure according to claim 11 or 12, wherein the first mask layer comprises at least a first optical absorbing material and a second optical absorbing material, the first optical absorbing material and the second optical absorbing material having different optical absorption spectra.

14. The optical structure according to any one of claims 11 to 13, wherein the first mask layer and the second mask layer have different optical absorption spectra.

15. An optical construct comprising: The lens film includes an outermost structured first main surface and an opposite outermost substantially flat second main surface, the structured first main surface including a plurality of microlenses arranged along an orthogonal first and second direction; as well as A polymer multilayer mask is disposed on the second main surface of the lens film. The multilayer mask has an average thickness less than 0.5 times the average focal length of the microlens and an optical density greater than 2. The multilayer mask defines a plurality of laser ablation through-holes arranged along a first direction and a second direction, the through-holes being aligned with the microlens in a one-to-one correspondence. The multilayer mask includes a first mask layer and a second mask layer of polymer, each of the first mask layer and the second mask layer having an optical density greater than 0.3, wherein the first mask layer is thicker than the second mask layer, and the optical density of the second mask layer is greater than the optical density of the first mask layer.

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