Optical filter and method for manufacturing an optical filter

Abstract

The optical filter includes a matrix including an optically transparent matrix material and nanoparticles including carbon atoms arranged in a hexagonal structure embedded in the matrix material, wherein at least one of the nanoparticles is physically separated from the other nanoparticles, and / or at least one nanoparticle aggregate including a plurality of nanoparticles has a maximum diameter of less than 30 nm, and each nanoparticle of the at least one nanoparticle aggregate is in physical contact with at least another one of the nanoparticles of the at least one nanoparticle aggregate.

Description

Detailed Description of the Invention

[0001] [Technical field] Various embodiments relate generally to optical filters and methods of making optical filters.

[0002] [background]

[0002] Radiation from the sun reaches Earth in the wavelength range of 100 nm to 1 million nm, including ultraviolet, visible, and infrared radiation. These three closely spaced components of the electromagnetic spectrum are generally defined as wavelengths ranging from 150 nm to 3 μm. Artificial light from electronic sources such as light bulbs, LEDs, or computer and phone screens is particularly rich in light with wavelengths less than 500 nm.

[0003]

[0003] Portions of this spectrum, particularly those below 500 nm, are known to be harmful to the structure of the human eye and to trigger various neural pathways in the brain and nervous system through the optic nerve, leading to secondary health effects. It is desirable to eliminate or minimize this light, hereafter referred to as "high-energy blue light" or "undesirable wavelengths."

[0004]

[0004] A variety of filters already exist that provide protection from high-energy blue light, whether in the form of eyeglasses, screen protectors, light bulb covers, or other forms. These filters are transparent in the visible wavelength range of the electromagnetic spectrum and are placed between a high-energy blue light source and the human eye. The majority of these filters simply absorb the undesired wavelengths and also introduce changes to the visual image, whether as distortion, dimming, or color shifts.

[0005]

[0005] Furthermore, many optically transparent materials that provide shielding against harmful portions of the electromagnetic spectrum are primarily inorganic in nature and are formed from glasses or minerals that may be rich in various shielding elements. While these may have desirable optical properties, they have undesirable physical and mechanical properties and are typically heavy, fragile, and brittle. High refractive index polymeric and resinous materials have desirable optical and mechanical properties and are clear, strong, and lightweight, but lack protection against undesirable wavelengths.

[0006]

[0006] The interaction of electromagnetic radiation, particularly visible light, with carbon-based nanomaterials exhibiting complex structures and dielectric properties has been demonstrated to alter the composition of the incident light beam (see, for example, U.S. Patent Application Publication No. 2008 / 286453, WO 2017 / 211420, U.S. Patent No. 6,066,272, U.S. Patent Application Publication No. 2011 / 001252, WO 2020 / 249207).

[0007]

[0007] Carbon-based nanomaterials have been deposited in the form of thin coatings on filter substrates or incorporated into optically transparent matrices to avoid easy wear. However, due to the very limited solubility of carbon-based nanomaterials in polymer or resin matrices in general, it is very difficult to incorporate nanomaterials into transparent polymer or resin matrices, making it very difficult to mix and disperse carbon-based nanomaterials in any matrix material at a desired concentration. Achieving a homogeneous dispersion without visible clusters or anomalies in the optical material, which is desirable from an optical perspective, presents additional challenges.

[0008]

[0008] Therefore, there is a need for optical filters containing nanoparticles that have excellent optical properties, and methods for making such optical filters.

[0009] [overview] According to a first aspect of the present disclosure, there is provided an optical filter including a matrix including an optically transparent matrix material and nanoparticles embedded in the matrix material, the nanoparticles including carbon atoms arranged in a hexagonal structure or a mixed hexagonal and pentagonal structure.

[0010] At least one of the nanoparticles is physically separated from the other nanoparticles, i.e., at least one nanoparticle is in exclusive contact with the matrix material but not with another one of the nanoparticles. The presence of such nanoparticles is an indication of a homogeneous distribution of the nanoparticles within the matrix material and contributes to the reduction or even elimination of the aforementioned undesired distortion, dimming, or color shift compared to commercially available materials. That is, the optical filter according to the present disclosure is configured to reduce or eliminate the aforementioned undesired wavelengths with much less distortion, dimming, or color shift than commercially available materials.

[0011] In an exemplary embodiment, the nanoparticles or majority of the nanoparticles are each physically separated from other nanoparticles.

[0012] Alternatively or additionally, at least one nanoparticle aggregate comprising a plurality of nanoparticles has a maximum diameter of less than 30 nm, and each nanoparticle of the at least one nanoparticle aggregate is in physical contact with at least one other nanoparticle of the at least one nanoparticle aggregate. The presence of such aggregates is a further indication of a homogeneous distribution of nanoparticles within the matrix material and contributes to the reduction or even elimination of the aforementioned undesired distortion, dimming, or color shift compared to commercially available materials. That is, optical filters according to the present disclosure are configured to reduce or eliminate the aforementioned undesired wavelengths with significantly less distortion, dimming, or color shift than commercially available materials.

[0013] Optionally, the majority of the nanoparticle aggregates have a maximum diameter of less than 30 nm.

[0014]

[0014] Suitable criteria for characterizing the optical quality of optical filters according to the present disclosure are the maximum refractive index variation and / or the maximum density of striae that result in an optical path difference of 30 nm. These criteria are also used in ISO standard 10110.

[0015]

[0015] Optical filters according to exemplary embodiments of the present disclosure have a resolution of ±50×10 -6 and / or the maximum density of striae that results in an optical path difference of 30 nm can be 10%.

[0016] The maximum variation in refractive index as defined above defines the optical non-uniformity in accordance with ISO standard 10110-4. -6 The maximum refractive index variation of ±20×10 corresponds to a uniformity grade of 0 according to ISO standard 10110-4. -6 Maximum refractive index variation (according to ISO standard 10110-4, uniformity class 1), optionally ±5×10 -6 Maximum refractive index variation of ±2×10 (according to ISO standard 10110-4, uniformity class 2), optionally ±2×10 -6 Maximum refractive index variation of ±1×10 (uniformity class 3 according to ISO standard 10110-4), optionally ±1×10 -6 Maximum refractive index variation of ±0.5×10 (uniformity grade 4 according to ISO standard 10110-4), optionally ±0.5×10 -6 A maximum refractive index variation of 0.05 mm (uniformity grade 5 according to ISO standard 10110-4) can occur.

[0017] As defined above, a maximum density of 10% striae resulting in an optical path difference of 30 nm corresponds to a striae grade of 1 in accordance with ISO standard 10110-4. Optical filters according to exemplary embodiments may have a maximum density of 5% striae resulting in an optical path difference of 30 nm (striae grade of 2 in accordance with ISO standard 10110-4), optionally a maximum density of 2% striae resulting in an optical path difference of 30 nm (striae grade of 3 in accordance with ISO standard 10110-4), further optionally a maximum density of 1% striae resulting in an optical path difference of 30 nm (striae grade of 4 in accordance with ISO standard 10110-4), and further optionally no visible striae (striae grade of 5 in accordance with ISO standard 10110-4).

[0018] A commonly used technique for determining the uniformity and striae grades is the shadowgraphy technique, which allows for quantitative evaluation of the uniformity and striae grades by means of calipers and reference filters. Alternatively, the uniformity and striae grades can be determined by interferometry. These techniques are well known to those skilled in the art.

[0019] Alternatively or additionally, the optical filter may be characterized in accordance with one or more of the following standards: ANSI Z80.1, ANSI Z80.3, ISO 8980-1. Optical filters according to exemplary embodiments of the present disclosure may meet the lens quality and clarity requirements set forth in the aforementioned standards.

[0020] The nanoparticles may have a diameter of 1 nm to 1000 nm (e.g., a mean diameter corresponding to the arithmetic mean). The nanoparticles may have a uniform or disordered size distribution. The nanoparticles and / or their aggregates may be spherical or rod-shaped, with or without an ordered or crystalline structure. Depending on the composition of both the nanoparticles and the matrix material, the nanoparticles and matrix material may account for 0.0005 wt% to 15 wt%, optionally 0.01 wt% to 5 wt% of the total mass (weight) of the optical filter.

[0021] The light filtering or light altering effect of the optical filters according to the present disclosure increases with increasing nanoparticle concentration, especially in the wavelength range of 200-600 nm.

[0022]

[0022] The nanoparticles may comprise either or both graphene nanoparticles and carbon nanotubes. Graphene nanoparticles may comprise or be flakes of graphene layers. Graphene nanoparticles may exist as single, straight sheets, or in multi-layered or, if not multi-layered, entangled or wrinkled arrangements. Carbon nanotubes may exist as single-walled or multi-walled nanotubes. Carbon nanotubes may have dimensions (e.g., lengths) of 10 nm to 20 μm, optionally 20 nm to 5 μm.

[0023]

[0023] The nanoparticles may include nanoparticles containing carbon atoms arranged in a pentagonal structure. This type of nanoparticle can be said to have a mixed hexagonal and pentagonal structure. Such nanoparticles may include or be configured as fullerenes. Fullerenes may be individual molecules with diameters between 1 nm and 10 nm, optionally between 1 nm and 2 nm (e.g., an average diameter corresponding to the arithmetic mean). Fullerenes are C 60 Fullerene (Buckminsterfullerene), or C 70 , C 84 It may also comprise or consist of higher molecular weight fullerenes such as C 60 consists of 60 carbon atoms arranged in 12 pentagons and 20 hexagons, defining a carbon composite structure (carbon cage).

[0024]

[0024] The nanoparticles in any given optical filter may be of the same type or may be a mixture of different types. In the optical filters according to the present disclosure, C 60 and C 70 and / or derivatives thereof, may comprise 25 wt% to 100 wt%, optionally 50 wt% to 95 wt% of the total mass (weight) of the nanoparticles.

[0025]

[0025] Fullerenes may include or be configured as endohedral fullerenes. Endohedral fullerenes are fullerenes that have one or more additional particles (e.g., atoms, ions, molecules) enclosed within a carbon cage. The particles enclosed within the carbon cage are called dopants.

[0026]

[0026] Encapsulation of particles within fullerene carbon cages is an effective means of combining otherwise incompatible materials (i.e., materials that may react, hinder, or interfere with each other chemically, optically, or mechanically when in direct contact with or mixed with each other) into a single optical filter; encapsulation within fullerene carbon cages prevents the encapsulated particles from interacting with each other, thereby protecting the matrix material from interacting with encapsulated particles that have good optical properties but may have chemical or mechanical properties that are degradative to the matrix material. In contrast to "incompatible materials," "compatible materials" can coexist within the same matrix material and simultaneously exhibit their own optical or light-altering effects without adversely affecting each other.

[0027]

[0027] The endohedral fullerene may contain within its carbon composite structure, i.e., carbon cage, one or more of a metal dopant, a metalloid dopant, or their respective oxides, chlorides, fluorides, iodides, or nitrates. Exemplary dopants include aluminum, antimony, barium, cerium, copper, didymium, gold, iron, lead, magnesium, molybdenum, neodymium, nickel, niobium, palladium, platinum, potassium, praseodymium, silicon, silver, tin, titanium, tungsten, vanadium, zinc, and zirconium, as well as one or more of their respective oxides, chlorides, fluorides, iodides, and nitrates.

[0028]

[0028] An effective combination of incompatible particles can be ensured by having the mass fraction of the endohedral fullerene relative to the total mass of the nanoparticles be between 0 and 70%, optionally between 20 and 60%, and further optionally between 30 and 50%.

[0029]

[0029] One or more of the nanoparticles may include one or more functional groups. Nanoparticles that include one or more functional groups are called functionalized nanoparticles. The one or more functional groups may contain elements other than carbon. The functional groups may enhance or alter the interaction of the nanoparticles with light, or may facilitate better bonding, dissolution, or interaction of the nanoparticles with the matrix material in which they are incorporated.

[0030]

[0030] The one or more functional groups may be or may include one or more of amide, amine, carbonyl, carboxyl, epoxide, ester, halide, hydroxyl, isocyanate, isothiocyanate, thiol, and sulfur-containing groups such as sulfate, sulfone, sulfide groups, etc.

[0031]

[0031] Functionalized nanoparticles are functionalized derivatives of nanoparticles. The functionalized derivatives within any given optical filter may all contain one or more of the aforementioned functional groups, or a mixture of nanoparticles and their functionalized derivatives may be present, with or without the aforementioned functional groups, with the same or different numbers of functional groups. The aforementioned functional groups may be of the same type or of different types, e.g., a mixture of different compounds.

[0032] The matrix material may include one or more of an acrylate-based polymer, a polycarbonate-based polymer, a urethane-based polymer, a thiourethane-based polymer, an epoxy-based polymer, and an episulfide-based polymer. In an exemplary embodiment, the matrix material may include a polymer exhibiting an aromatic structure.

[0033] The matrix material may comprise a single material type, or may comprise two or more material types, either copolymerized together or simply mixed. When two or more materials are combined into a single optical filter, it is particularly preferred that they be thoroughly mixed to provide a homogeneous final structure and ensure optical and structural consistency throughout the optical filter.

[0034] The matrix material may comprise an inorganic material, optionally an inorganic glass or mineral material (e.g., a synthetic or natural crystalline inorganic material), whose mass fraction relative to the total mass of the matrix material may be at least 50 wt%, optionally at least 80 wt%, and further optionally at least 95 wt%.

[0035]

[0035] According to a second aspect of the present disclosure, a multilayer optical filter is provided which includes a plurality of filter layers stacked in the thickness direction, and one or more of the plurality of filter layers is configured as the above-mentioned optical filter.

[0036] The multilayer optical filters described above can be particularly interesting when using multiple incompatible materials. By separating the incompatible materials into separate filter layers, their advantages can be utilized without the consequences of their incompatibility.

[0037] The number of filter layers may range from 2 to 20, optionally from 2 to 10, and further optionally from 2 to 5.

[0038] The multilayer optical filter as a whole has a reflectivity of ±50×10 -6 , optionally ±20×10 -6 , and optionally ±5×10 -6 , and optionally ±2×10 -6 , and optionally ±1×10 -6 , and optionally 0.5×10 -6Additionally or alternatively, the multilayer optical filter as a whole may have a maximum density of 10% striae that results in an optical path difference of 30 nm, optionally a maximum density of 5% striae that results in an optical path difference of 30 nm, further optionally a maximum density of 2% striae that results in an optical path difference of 30 nm, further optionally a maximum density of 1% striae that results in an optical path difference of 30 nm, and further optionally no visible striae.

[0039] The multiple filter layers may include first and second filter layers configured as the above-described optical filters having different nanoparticle compositions, or different matrix materials, or different nanoparticle compositions and different matrix materials. This configuration provides an effective way to incorporate incompatible matrix materials and / or nanoparticles into a single filter.

[0040] The filter layers may be of the same thickness or of different thicknesses depending on the filtering characteristics of the filter, since the permeability of a given filter layer decreases as the thickness of the filter layer increases.

[0041]

[0041] The filter layers may have the same refractive power (diopter) or different refractive powers, depending on the desired mechanical and optical properties. By adjusting the refractive power of the individual filter layers, the overall thickness and diopter of the multilayer optical filter can be optimized, e.g., minimized or reduced. The thicknesses of the different filter layers, as well as the ratio of the thicknesses of the different filter layers, may be different in different regions of the filter.

[0042] In an exemplary multi-layer filter, at least one of the filter layers may be free of nanoparticles containing carbon atoms arranged in hexagonal structures (e.g., hexagonal and pentagonal structures), which can effectively separate two adjacent filter layers containing incompatible nanoparticles and / or matrix materials.

[0043]

[0043] At least one filter layer that does not contain nanoparticles containing carbon atoms arranged in a hexagonal structure may contain inorganic material, optionally inorganic glass or mineral material, in a mass fraction of at least 50 wt%, optionally at least 80 wt%, and further optionally at least 95 wt%, relative to the total mass of the at least one filter layer.

[0044]

[0044] The mineral or inorganic glass containing filter layer is preferably sandwiched through the thickness of the multi-layer filter between two polymer or resin layers which act as protective layers for the inorganic glass or mineral containing layer.

[0045]

[0045] In exemplary multi-layer filters comprising multiple mineral or inorganic glass-containing filter layers, at least two of the multiple layers are separated by at least one polymer or resin layer to prevent glass-to-glass contact and abrasion and / or spalling.

[0046]

[0046] Minerals or inorganic glasses may be enriched with metals or metalloids, or their respective oxides, to enhance their optical or mechanical properties. While not particularly limited, the most preferred metals and metalloids include aluminum, barium, boron, calcium, cerium, didymium, gold, lead, magnesium, neodymium, niobium, platinum, potassium, praseodymium, silver, sodium, strontium, tin, titanium, and zirconium, as well as one or more of their respective oxides. At least one filter layer that does not contain nanoparticles containing hexagonally arranged carbon atoms may contain a single enriching compound, or multiple enriching compounds to take advantage of the enriching properties of multiple compounds within a single layer. In the case of optical filters that include filter layers containing multiple inorganic glasses or minerals that do not contain nanoparticles containing hexagonally arranged carbon atoms, the layers may contain the same inorganic glass or mineral, or different inorganic glasses or minerals, or mixtures or combinations thereof, to take advantage of the optical qualities of multiple different materials within a single optical filter. These layers may contain the same reinforcing compound or combination of reinforcing compounds, or different reinforcing compounds or combinations thereof. A given glass or mineral filter layer may contain one or more enriching agents. The one or more enriching agents may comprise 0.5 wt% to 70 wt%, preferably 5 wt% to 40 wt%, of the total mass of the respective inorganic glass or mineral-containing filter layer.

[0047] In exemplary multilayer filters, at least two of the plurality of filter layers may have substantially the same dimensions and / or shapes in a direction perpendicular to the thickness direction. Optionally, most or even all of the plurality of filter layers may have substantially the same dimensions and / or shapes in a direction perpendicular to the thickness direction. In such multilayer filters, light rays pass through a substantially equal number of filter layers regardless of the angle of incidence and position on the filter, thus providing a consistent image across the entire multilayer filter. Such a configuration is particularly suitable for multilayer filters configured as plano lenses or single diopter lenses.

[0048] In exemplary multi-layer filters, at least two of the filter layers, and optionally most or even all of the filter layers, may have different dimensions or shapes, or different dimensions and shapes, perpendicular to the thickness direction. In such multi-layer filters, light rays pass through a variable number of filter layers depending on the angle of incidence and their position on the filter. Such configurations are particularly suitable for progressive multifocal eyeglass lenses or light filters for medical or technical use, since the diopter and / or intensity of transmitted light differs in different parts of the filter.

[0049] The optical filters or multilayer filters described above can be used as top protective screens or incorporated into the screens of electronic devices (televisions, mobile phones, etc.). Alternatively, these filters can be used in eyeglasses or sunglasses, or as lenses for technical applications (cameras, binoculars, telescopes, etc.). These filters may or may not have refractive power.

[0050]

[0050] The optical filters and / or filter layers described above may further include other particles that impart specific and unique optical properties, for example, modify the refractive index. These other particles may include metals or metalloids or their respective oxides, chlorides, fluorides, iodides, or nitrates. Without limitation, the most preferred metals and metalloids are aluminum, antimony, barium, cerium, copper, didymium (a mixture of praseodymium and neodymium), gold, iron, lead, magnesium, molybdenum, neodymium, nickel, niobium, palladium, platinum, potassium, praseodymium, silicon, silver, tin, titanium, tungsten, vanadium, zinc, and zirconium, as well as their oxides, chlorides, fluorides, iodides, and nitrates. These other particles may all be of the same type, i.e., the same material, or may be of different types, i.e., a mixture of different materials. These other particles may have an average diameter (e.g., corresponding to the arithmetic mean) between 2 nm and 5 μm, preferably between 5 nm and 3 μm. They may all have the same diameter or may have different diameters. In the present invention, these other particles containing one or more of the aforementioned compounds may account for 0 wt% to 80 wt%, preferably 5 wt% to 50 wt%, of the total mass of the nanoparticles.

[0051] The optical filters and / or filter layers described above may further comprise one or more additional components (e.g., additives), such as dyes (which may or may not have their own light filtering effect), UV inhibitors, release agents, etc. Such additional components may also be added to filter layers that do not contain nanoparticles containing carbon atoms arranged in a hexagonal structure. The additional components may be dissolved in the matrix material at the molecular level, partially dissolved, or completely dissolved. Alternatively, the nanoparticles and / or other particles may be present in the matrix as clusters or aggregates, depending on their composition, the method of introduction into the matrix material, and the desired optical qualities. Individual clusters or aggregates may be homogeneous or may be a mixture of different nanoparticles / particle species. These clusters or aggregates may exhibit a regular, ordered structure or an irregular, disordered structure, and may be spherical, rod-like, amorphous, or crystalline, depending on their composition, the method of preparation, and the desired optical qualities. Within a given optical filter or filter layer, some of the nanoparticles and / or other particles may exist as individual nanoparticles / particles, and some may simultaneously exist as clusters or agglomerates.

[0052] The other particles may be dispersed in the matrix to such an extent that each particle is exclusively surrounded by and in contact with the matrix material.

[0053] The filter as a whole may further comprise an outer coating. Without limitation, the most preferred coatings are hard protective coatings or other colored, anti-reflective, anti-UV, or anti-polarizing coatings known in the art. In the case of multi-layer filters, the filter layers may be separated by thin coatings, films, or adhesives, or may be layered directly on top of each other, depending on the desired mechanical and optical properties.

[0054] According to a third aspect of the present disclosure, there is provided a method for producing an optical filter. The method includes the steps of adding nanoparticles comprising carbon atoms arranged in a hexagonal or mixed hexagonal and pentagonal configuration to an optically transparent matrix material or a precursor of the optically transparent matrix material to obtain a mixture; homogenizing the mixture to obtain a homogenized mixture (e.g., a dispersion); and inserting the homogenized mixture into a mold to form the optical filter. The method may be performed in the order described above. Any of the nanoparticles and / or matrix materials described above may be used to produce an optical filter by this method.

[0055]

[0055] The problems associated with the extremely limited solubility of nanoparticles and excessive or uncontrolled clustering or agglomeration, which result in poor quality and unclear lenses, are overcome by homogenizing the mixture. Thus, the above-described method allows for the production of optical filters and multilayer filters having the above-described properties, i.e., optical filters according to the present disclosure can be produced by the above-described method.

[0056]

[0056] Nanoparticles with extremely limited solubility require dispersion in the matrix or precursor material as a colloidal suspension rather than as a solution, and then require dispersion and homogenization instead of dissolution. If dissolution of the nanoparticles is possible or necessary, their solubility in the optically transparent matrix material or precursor to the optically transparent matrix material must be determined. If only partial dissolution or no dissolution of the nanoparticles in the optically transparent matrix material or precursor to the optically transparent matrix material is desired or required, the important factor is the rate at which the nanoparticles settle or float, as determined by the following equation, assuming the nanoparticles are spherical:

number

[0057]

[0057] where Υs is the settling or flotation velocity of the nanoparticles, V is the nanoparticle volume, and ρ p is the nanoparticle density, and ρ m is the density of the optically transparent matrix material or the precursor of the optically transparent matrix material, g is the acceleration of gravity, η is the viscosity of the optically transparent matrix material or the precursor of the optically transparent matrix material, and r is the nanoparticle radius.

[0058] The size of the nanoparticles and the density difference between the nanoparticles and the optically transparent matrix material or precursor of the optically transparent matrix material determine the rate at which the nanoparticles rise or fall, with smaller particles generally falling or rising more slowly than larger particles. The settling or rising rate is inversely proportional to the viscosity of the optically transparent matrix material or precursor of the optically transparent matrix material. When balanced with the time the mixture must rest before hardening, as well as the hardening time, and the viscosity increase caused by the solidification or hardening of the optically transparent matrix material or precursor of the optically transparent matrix material, the most appropriate diameter of the nanoparticles or nanoparticle aggregates can be determined, and the most appropriate time for introducing the nanoparticles into the filter preparation process can be selected. When multiple matrix materials are used, the most appropriate individual or combination of these can be selected to disperse the nanoparticles.

[0059]

[0059] Without wishing to be bound by any particular theory, it is believed that the dispersibility of nanoparticles and the final diameter of the nanoparticles in a colloidal suspension depend on the shear force: τ=ηΥ m The effect is largely influenced by the ability of the fluid to mechanically break down and disperse the nanoparticle material using

[0060] where τ is the shear force on the nanomaterial during mixing, η is the viscosity of the optically transparent matrix material or precursor to the optically transparent matrix material, and Υ mis the velocity of the optically transparent matrix material or precursor to the optically transparent matrix material during mixing. The effectiveness of any such mixing and dispersing process depends on the liquid shear rate:

number

[0061] where R s is the shear rate and V u is the tip speed of the rotor (spinning unit for mixing the liquid, V u is determined by the rotor diameter and the rotor revolutions per minute), and D s is the distance between the rotor and the stator (the housing around the rotor). This allows for high shear rates to be achieved without being constrained by any single dimension of the equipment required to achieve high shear rates. High liquid shear forces, liquid velocities, and shear rates are necessary to obtain particularly fine nanoparticles, and therefore stable suspensions of nanoparticles within the optically transparent matrix material or precursor to the optically transparent matrix material. This process can be aided by selecting a high viscosity for the optically transparent matrix material or precursor to the optically transparent matrix material.

[0062] Homogenization of the mixture may involve high speed homogenization at mixing speeds above 5000 rpm (revolutions per minute), optionally above 10000 rpm, and further optionally from 10000 rpm to 80000 rpm, and / or ultrasonic treatment at frequencies above 5 kHz, optionally above 10 kHz, and further optionally from 10 kHz to 80 kHz. Such homogenization of the mixture results in a colloidal suspension that effectively overcomes the problem of the extremely limited solubility of nanoparticles in commonly used matrix materials or precursors of commonly used matrix materials.

[0063] The mixture was homogenized for 30,000 seconds. -1 Ultra, optional 50000 seconds-1 Ultra, and optionally 60,000 seconds -1 ~350000 seconds -1 Mixing at these shear rates contributes to a highly homogeneous distribution of the nanoparticles within the mixture.

[0064]

[0062] The homogenization can be carried out at a temperature higher than room temperature and lower than the melting point, boiling point, or decomposition temperature of the matrix material or the precursor of the matrix material. Alternatively, when nanoparticles are added to the precursor of the matrix material, the homogenization can be carried out at a temperature lower than room temperature to control the stability of the precursor and increase the viscosity, which improves the shear capacity of the precursor.

[0065] Because the presence of gases or bubbles in the materials can produce optically inferior filters, mixing can be performed under vacuum, for example, at pressures less than 0.1 bar, optionally less than 0.01 bar, and even optionally less than 0.001 bar, to prevent the mixing and dissolution of gases into the mixture. Mixing can be performed under an inert gas atmosphere to prevent reaction or oxidation of either the matrix or precursor materials or the nanoparticles or additives, which could impair the optical or mechanical properties of the filter. Nanoparticles can be mixed with or added to the filter together with other additives, such as antioxidants, UV stabilizers, dyes, and mold release agents. When multiple types of nanoparticles are added, they can be added simultaneously or at different stages during the mixing process, depending on the degree of homogenization desired for the different nanoparticle species.

[0066]

[0064] During the addition of the nanoparticles to the optically transparent matrix material or the precursor of the optically transparent matrix material, the optically transparent matrix material or the precursor of the optically transparent matrix material can be in a liquid state to obtain a liquid mixture, and / or the mixture can be in a liquid state during homogenization. By these measures, the degree of homogeneity can be further improved. Alternatively, when a thermoplastic resin is used for or as the matrix material, the nanoparticles can be added to the thermoplastic resin in granular or powder form before dissolving.

[0067] The degree of homogeneity can be further improved by adding a surfactant to the liquid mixture or homogenized mixture. The use of a surfactant can be particularly important when a uniform dispersion of nanoparticles is desired, or when a protective layer around the nanoparticles is desired to prevent direct interaction of the precursor material with the matrix material. The surfactant may be added before, simultaneously with, or after the nanoparticles, depending on the type of nanoparticles and their interaction with the surfactant and the matrix or precursor material, as well as the manufacturing process being used. When high-speed homogenization is used, the surfactant is most preferably added after homogenization to avoid excessive foaming. One or more surfactants may be used, and they may be added simultaneously or at different times (e.g., process or method steps) in the production procedure.

[0068] The mass ratio of surfactant to nanoparticles can be in the range of 1:1 to 50:1, optionally 10:1 to 35:1. Suitable surfactants are those selected from the group consisting of nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants, or mixtures thereof. Although not particularly limited, the most preferred surfactants include one or more of dodecyltrimethylammonium chloride, myristyltrimethylammonium bromide, sodium lauryl sulfate, Triton X-100, Tween (Polysorbate) 20, Tween (Polysorbate) 60, and Tween (Polysorbate) 80.

[0069]

[0067] In an exemplary method, a surfactant may be added to the homogenized mixture, and before inserting the homogenized mixture into a mold, the homogenized mixture may be subjected to low speed homogenization at a mixing speed of less than 10,000 rpm, optionally between 200 rpm and 10,000 rpm.

[0070] In an exemplary method, nanoparticles may be dispersed or dissolved in a matrix or precursor material in an amount less than that required to produce the optical filter (bulk material) to form a concentrate, which may then be added to the bulk material. In this way, homogenization may be facilitated.

[0071]

[0069] An exemplary method may further include dissolving nanoparticles in a solvent miscible with the liquid matrix material or liquid precursor of the optically transparent matrix material to obtain a first premixture; adding the first premixture to the liquid optically transparent matrix material or liquid precursor of the optically transparent matrix material to obtain a second premixture; and heating the second premixture to a temperature above the boiling point of the solvent and below the boiling point or decomposition temperature of the optically transparent matrix material or precursor of the optically transparent matrix material to obtain a liquid mixture, which can improve the homogeneity of the mixture and reduce or control nanoparticle aggregation.

[0072] The optically transparent matrix material or precursor to the optically transparent matrix material may comprise a thermoplastic polymer, a thermosetting polymer, a resin precursor, or a mixture thereof.

[0073]

[0071] The method may further include mechanically treating the filter after it has been removed from the mold and / or applying a coating, such as a protective coating and / or an anti-reflective coating, to one or more surfaces of the filter.

[0074] In the case of filters comprising a single layer, the filters may be cast as a final product. They may also be cast as thicker semi-finished filters or lenses that are then subsequently cast and annealed and formed into a final product through a combination of cutting, grinding, and polishing. Hard protective coatings or other coatings, such as tinted, anti-reflective, anti-UV, or anti-polarizing coatings, may be applied.

[0075] In the case of a multi-layer filter, the filter layers can be produced sequentially in a suitable mold, with a particular filter layer being produced on top of an already cured or semi-cured filter layer. Prior to production of the filter layer on the surface of the already cured or semi-cured filter layer in the mold, the surface of the cured or semi-cured filter layer can be mechanically and / or chemically treated, for example scraped, to increase the surface area in order to strengthen the adhesion between the filter layers. The appropriate surface treatment and degree of curing are selected depending on the materials that will be in contact with each other and the balance between obtaining an optimal degree of adhesion between successive filter layers and the risk of them reacting with each other when they are uncured or semi-cured.

[0076]

[0074] Alternatively or additionally, the surface of an already cured or semi-cured filter layer may be coated with a thin layer of adhesive or uncured resin, provided that this does not significantly interfere with the clarity of the filter or the quality of the image viewed through the filter.

[0077] To ensure complete cure and strong adhesion between the filter layers, this thin layer of adhesive or uncured resin may contain one or more polymerization free radical initiators or catalysts that are the same as or different from those found within one or both of the bulk filter materials in contact with it.

[0078]

[0076] In the case of a multi-layer filter comprising at least two filter layers having different dimensions and / or shapes perpendicular to the thickness direction, the final product is obtained through a combination of cutting, grinding and polishing that removes the entire thickness of one or more layers at one or more locations on one or both of the major surfaces of the filter.

[0079] In the following description, various embodiments of the present invention will be described with reference to the accompanying figures. [Brief explanation of the drawings]

[0080] [Figure 1] 1 is a schematic diagram of an exemplary optical filter according to the present disclosure. [Figure 2] 1 is a graph showing the transmittance in the wavelength range of 350-800 nm of several exemplary optical filters according to the present disclosure containing nanoparticles at different concentrations. [Figure 3] 1 is a graph showing the transmittance in the wavelength range of 350-800 nm for three optical filters according to the present disclosure, all three of which contain the same matrix material and the same type and concentration of nanoparticles, but with different thicknesses. [Figure 4] FIG. 2 is a schematic diagram of another exemplary optical filter according to the present disclosure. [Figure 5] 1 is a schematic diagram of an exemplary multilayer optical filter according to the present disclosure. [Figure 6] FIG. 2 is a schematic diagram of another exemplary multilayer optical filter according to the present disclosure. [Figure 7] FIG. 1 is a schematic diagram of yet another exemplary multilayer optical filter according to the present disclosure. [Figure 8]1 is a flowchart of an exemplary method for manufacturing an optical filter according to the present disclosure. [Figure 9] 1 is a flow chart of an exemplary method of making a liquid mixture according to the present disclosure.

[0081] [Detailed explanation]

[0078] The following detailed description, with reference to the accompanying drawings, shows, by way of illustration, specific details and embodiments in which the invention may be practiced.

[0082] 1 is a schematic diagram of an exemplary optical filter 100 according to the present disclosure. Filter 100 includes a matrix 102 comprising an optically transparent matrix material and nanoparticles 104 embedded in matrix material 102. Nanoparticles 104 include carbon atoms arranged in a hexagonal structure.

[0083] 1, at least one of the nanoparticles 104A may be physically separated from the other nanoparticles 104, i.e., at least one nanoparticle 104A may be in exclusive contact with the matrix material but not with another one of the nanoparticles 104. The presence of such nanoparticles is indicative of a homogeneous distribution of the nanoparticles 104 within the matrix material and contributes to the reduction or even elimination of undesirable distortion, dimming, or color shift compared to commercially available materials.

[0084] As further shown in FIG. 1, each of the plurality of nanoparticles 104 or the majority of nanoparticles 104 may be physically separated from any of the other nanoparticles 104.

[0085]

[0082] Some of the nanoparticles 104 may form at least one nanoparticle aggregate 104B comprising multiple nanoparticles 104. The nanoparticles 104 forming the at least one nanoparticle aggregate 104B are in physical contact with at least one other nanoparticle 104 forming the at least one nanoparticle aggregate 104B.

[0086] At least one nanoparticle aggregate 104B may have a maximum diameter d of less than 30 nm. The presence of such aggregates is a further indication of a homogeneous distribution of nanoparticles 104 within the matrix material, and contributes to the reduction or even elimination of undesirable distortion, dimming, or color shift compared to commercially available materials.

[0087]

[0084] The optical filter 100 is ±50×10 -6 and / or may have a maximum density of striae of 10% that results in an optical path difference of 30 nm.

[0088]

[0085] The interaction of light with the nanoparticles 104 of the filter 100 reduces or eliminates undesirable wavelengths in the 200-600 nm wavelength range with little distortion, dimming, or color change.

[0089] The effect of exemplary filters according to the present disclosure on incident light in the wavelength range of 350 to 800 nm is shown in FIG. 2. The solid transmittance curve is for a first optical filter that includes a CR-39 matrix material but does not include nanoparticles embedded in the matrix material. The dotted transmittance curve is for a second optical filter that differs from the first optical filter only in that it includes a first concentration of nanoparticles embedded in the matrix material. The dashed transmittance curve is for a third optical filter that differs from the second optical filter only in that it includes a nanoparticle concentration that is three times the first concentration. The dashed-dotted transmittance curve is for a fourth optical filter that differs from the second optical filter only in that it includes a nanoparticle concentration that is five times the first concentration. The doubled transmittance curve is for a fifth optical filter that differs from the second optical filter only in that it includes a nanoparticle concentration that is ten times the first concentration.

[0090]

[0087] Figure 2 shows that the nanoparticles suppress the transmittance of each filter in the wavelength range of about 400-600 nm, i.e., undesirable wavelengths in the blue wavelength range can be suppressed by filters according to the present disclosure. Figure 2 further shows that this effect increases with nanoparticle concentration.

[0091]

[0088] Because the transmittance of an optical filter decreases with increasing thickness, the transmittance in the wavelength range of 350 to 800 nm can be further controlled by the thickness of the optical filter. This effect is illustrated in Figure 3, which shows the transmittance in the wavelength range of 350 to 800 nm for three optical filters according to the present disclosure. All three optical filters contain the same matrix material and the same type and concentration of nanoparticles, but have different thicknesses.

[0092]

[0089] The transmittance curve shown by a solid line in Figure 3 is the transmittance curve of one of these optical filters used as a reference filter. Its thickness is referred to as the "nanoparticle lens standard thickness" in Figure 3. The transmittance curve shown by a dotted line in Figure 3 is the transmittance curve of a first comparative optical filter whose thickness is reduced compared to the reference filter. The transmittance curve shown by a dashed line in Figure 3 is the transmittance curve of a second comparative optical filter whose thickness is increased compared to the reference filter.

[0093]

[0090] As can be clearly seen from Figure 3, the transmittance of the optical filter according to the present disclosure decreases as the filter thickness increases over the entire wavelength range of 350 to 800 nm.

[0094]

[0091] The maximum variation in refractive index as defined above defines the optical non-uniformity in accordance with ISO standard 10110-4. -6 The maximum refractive index variation of ±20×10 corresponds to a uniformity grade of 0 according to ISO standard 10110-4. -6Maximum refractive index variation (uniformity class 1 according to ISO standard 10110-4) of ±5×10 -6 maximum refractive index variation of ±2×10 (uniformity class 2 according to ISO standard 10110-4), optionally ±2×10 -6 maximum refractive index variation of ±1×10 (uniformity class 3 according to ISO standard 10110-4), optionally ±1×10 -6 maximum refractive index variation of ±0.5×10 (uniformity class 4 according to ISO standard 10110-4), optionally ±0.5×10 -6 The maximum refractive index variation (uniformity grade 5 according to ISO standard 10110-4) can be obtained.

[0095] As defined above, a maximum density of 10% striae resulting in an optical path difference of 30 nm corresponds to a striae grade of 1 in accordance with ISO standard 10110-4. Optical filter 100 may have a maximum density of 5% striae resulting in an optical path difference of 30 nm (striae grade of 2 in accordance with ISO standard 10110-4), optionally a maximum density of 2% striae resulting in an optical path difference of 30 nm (striae grade of 3 in accordance with ISO standard 10110-4), further optionally a maximum density of 1% striae resulting in an optical path difference of 30 nm (striae grade of 4 in accordance with ISO standard 10110-4), and further optionally no visible striae (striae grade of 5 in accordance with ISO standard 10110-4).

[0096] A commonly used technique for determining the uniformity and striae grades is the shadowgraphy technique, which allows for quantitative assessment of the uniformity and striae grades by means of calipers and reference filters. Alternatively, the uniformity and striae grades can be determined by interferometry. These techniques are well known to those skilled in the art.

[0097] Alternatively or additionally, optical filters according to the present disclosure may be characterized in accordance with one or more of the following standards: ANSI Z80.1, ANSI Z80.3, ISO 8980-1. Optical filters according to exemplary embodiments of the present disclosure may meet the lens quality and clarity requirements set forth in the aforementioned standards.

[0098]

[0095] The nanoparticles 104 may have a diameter between 1 nm and 1000 nm (e.g., an average diameter corresponding to the arithmetic mean). The nanoparticles 104 may have a uniform or disordered size distribution. The nanoparticles 104 may form aggregates larger than the individual nanoparticles. The nanoparticles 104 and / or their aggregates may be spherical or rod-shaped, with or without an ordered or crystalline structure. Depending on the composition of both the nanoparticles 104 and the matrix material, the nanoparticles 104 and the matrix material may account for 0.0005 wt% to 15 wt%, optionally 0.01 wt% to 5 wt%, of the total mass of the optical filter 100.

[0099]

[0096] The nanoparticles 100 may comprise one or both of graphene nanoparticles and carbon nanotubes. Graphene nanoparticles may comprise or be fragments of graphene sheets. Graphene nanoparticles may exist as single, straight sheets, or in multi-layered or, if not multi-layered, entangled or wrinkled arrangements. Carbon nanotubes may exist as single-walled or multi-walled nanotubes. Carbon nanotubes may have dimensions (e.g., lengths) of 10 nm to 20 μm, optionally 20 nm to 5 μm.

[0100]

[0097] The nanoparticles 104 may include nanoparticles containing carbon atoms arranged in a pentagonal structure. This type of nanoparticle may be said to have a mixed hexagonal and pentagonal structure. Such nanoparticles may include or be configured as fullerenes. Fullerenes may be individual molecules with diameters between 1 nm and 10 nm, optionally between 1 nm and 2 nm (e.g., an average diameter corresponding to the arithmetic mean). Fullerenes are C 60 Fullerene (Buckminsterfullerene), or C 70 , C 84 It may also comprise or consist of higher molecular weight fullerenes such as C 60 consists of 60 carbon atoms arranged in 12 pentagons and 20 hexagons, defining a carbon composite structure (carbon cage).

[0101]

[0098] The nanoparticles 104 may be of the same type or may be a mixture of different types. 60 and C 70 Smaller fullerenes, such as may comprise 25 wt% to 100 wt%, optionally or preferably 50 wt% to 95 wt% of the total mass (weight) of the nanoparticles.

[0102]

[0099] Fullerenes may include or be configured as endohedral fullerenes. Endohedral fullerenes are fullerenes that have one or more additional particles (e.g., atoms, ions, molecules) enclosed within a carbon cage. The particles enclosed within the carbon cage are called dopants.

[0103] [000100] Encapsulation of particles within fullerene carbon cages is an effective means of combining otherwise incompatible materials (i.e., materials that may react, hinder, or interfere with each other chemically, optically, or mechanically when in direct contact with or mixed with each other) into a single optical filter, because encapsulation within fullerene carbon cages prevents the encapsulated particles from interacting with each other and protects the matrix material from interacting with encapsulated particles that have good optical properties but may have chemical or mechanical properties that are degradative to the matrix material. In contrast to "incompatible materials," "compatible materials" can coexist within the same matrix material and simultaneously exhibit their own optical or light-altering effects without adversely affecting each other.

[0104] [000101] The endohedral fullerene may contain, within its carbon composite structure, i.e., carbon cage, one or more of a metal dopant, a metalloid dopant, or their respective oxides, chlorides, fluorides, iodides, or nitrates. Exemplary dopants include aluminum, antimony, barium, cerium, copper, didymium, gold, iron, lead, magnesium, molybdenum, neodymium, nickel, niobium, palladium, platinum, potassium, praseodymium, silicon, silver, tin, titanium, tungsten, vanadium, zinc, and zirconium, as well as one or more of their respective oxides, chlorides, fluorides, iodides, and / or nitrates.

[0105] [000102] An effective combination of incompatible particles can be ensured by having the mass fraction of the endohedral fullerene be between 0% and 70 wt%, optionally between 20 and 60 wt%, and further optionally between 30 and 50 wt%, relative to the total mass (weight) of the nanoparticles.

[0106] [000103] One or more of the nanoparticles 104 may include one or more functional groups. Nanoparticles that include one or more functional groups are called functionalized nanoparticles. The one or more functional groups may contain elements other than carbon. The functional groups may enhance or alter the interaction of the nanoparticles 104 with light or may facilitate better bonding, dissolution, or interaction of the nanoparticles 100 with a matrix material.

[0107] [000104] The one or more functional groups may be or include one or more of amide, amine, carbonyl, carboxyl, epoxide, ester, halide, hydroxyl, isocyanate, isothiocyanate, thiol, and sulfur-containing groups such as sulfate, sulfone, sulfide groups, and the like.

[0108] [000105] Functionalized nanoparticles are functionalized derivatives of nanoparticles 104. All functionalized derivatives may contain one or more of the aforementioned functional groups, or mixtures of nanoparticles and their functionalized derivatives may be present, with or without the aforementioned functional groups, with the same or different numbers of functional groups. The aforementioned functional groups may be of the same type or of different types, e.g., a mixture of different compounds.

[0109] [000106] The matrix material may include one or more of an acrylate-based polymer, a polycarbonate-based polymer, a urethane-based polymer, a thiourethane-based polymer, an epoxy-based polymer, and an episulfide-based polymer. Exemplary matrix materials may include polymers exhibiting aromatic structures.

[0110] [000107] The matrix material may comprise a single material type, or two or more material types, which may be copolymerized together or simply mixed. When two or more materials are combined into a single optical filter, it is particularly preferred that they be thoroughly mixed to provide a homogeneous final structure and ensure optical and structural consistency throughout the optical filter 100.

[0111] [000108] The matrix material may comprise an inorganic material, optionally an inorganic glass or mineral material, whose mass fraction relative to the total mass of the matrix material may be at least 50 wt%, optionally at least 80 wt%, and further optionally at least 95 wt%.

[0112] [000109] The optical filter 100 shown in Figure 1 has two substantially planar major surfaces 106a and 106b facing each other. In operation, the filter 100 is positioned so that one major surface 106a acts as a light input surface and the other major surface 106b acts as a light output surface. The light propagation directions are indicated in Figure 1 by arrows labeled I and O. Arrow I indicates the direction of light incidence on the light input surface 106a, and arrow O indicates the direction of light output from the light output surface 106b.

[0113] [000110] Due to the substantially planar major surfaces 106a and 106b, filter 100 has no refractive power, which specifically means that either major surface 106a, 106b can act as a light input or output surface.

[0114] [000111] Figure 4 is a schematic diagram of an optical filter 200 according to another embodiment of the present disclosure. Optical filter 200 differs from optical filter 100 shown in Figure 1 only in terms of its shape. More specifically, unlike filter 100 shown in Figure 1, filter 200 has two curved major surfaces 206a and 206b. Due to the curved configuration of major surfaces 206a and 206b and their different degrees of curvature, with outer surface 206b exhibiting a higher degree of curvature than inner surface 206a, optical filter 200 has a positive refractive power (diopter). It should be noted that optical filters having negative refractive powers are also encompassed by the present disclosure.

[0115] 4, concave major surface 206a is illustrated as a light input surface for incident light propagating along direction I, and convex major surface 206b is illustrated as a light output surface. The propagation direction of light passing through optical filter 200 is indicated by arrow O.

[0116] 5 is a schematic diagram of an exemplary multilayer optical filter 300 including multiple filter layers 300-1, 300-2, 300-3 stacked in a thickness direction z of the multilayer optical filter 300. The exemplary multilayer filter 300 shown in FIG. 5 includes a first filter layer 300-1, a second filter layer 300-2, and a third filter layer 300-3 sandwiched between the first filter layer 300-1 and the second filter layer 300-2 in the thickness direction z.

[0117] [000114] The first filter layer 300-1 and the second filter layer 300-2 may each be configured as an optical filter as described above.

[0118] [000115] The first filter layer 300-1 may include a first matrix 302-1 including a first optically transparent matrix material and first nanoparticles 304-1 embedded in the matrix material, the first nanoparticles 304-1 including carbon atoms arranged in a hexagonal structure. In Figure 5, the first nanoparticles 304-1 are illustrated as being separated from one another. Additionally or alternatively, the first filter layer 300-1 may include at least one nanoparticle aggregate having a maximum diameter of less than 30 nm.

[0119] [000116] The first filter layer 300-1 may have a maximum refractive index variation of ±50×10 −6 and / or a maximum density of striae of 10% that results in an optical path difference of 30 nm.

[0120] Similarly, the second filter layer 300-2 may include a second matrix 302-2 including a second optically transparent matrix material and second nanoparticles 304-2 embedded in the second optically transparent matrix material, the second nanoparticles 304-2 including carbon atoms arranged in a hexagonal structure. In FIG. 5 , the second nanoparticles 304-2 are illustrated as being separated from one another. Additionally or alternatively, the second filter layer 300-2 may include at least one nanoparticle aggregate having a maximum diameter of less than 30 nm.

[0121] [000118] The second layer 300-2 may have a maximum refractive index variation of ±50×10 −6 and / or a maximum density of striae of 10% that results in an optical path difference of 30 nm.

[0122] [000119] The third filter layer 300-3 may include a third matrix 302-3 that includes an optically transparent matrix material. The third filter layer 300-3 may not include nanoparticles that include carbon atoms arranged in a hexagonal structure.

[0123] [000120] The multilayer optical filter 300 shown in Figure 5 may be particularly interesting when using multiple incompatible materials. By separating the incompatible materials into separate filter layers, their advantages can be utilized without the consequences of their incompatibility. For example, the first optically transparent matrix material included in the first matrix 302-1 may be different from the second optically transparent matrix material included in the second matrix 302-2. Alternatively or additionally, the first nanoparticles 304-1 may be different from the second nanoparticles 304-2. This configuration provides an effective way to incorporate incompatible matrix materials and / or nanoparticles into a single filter.

[0124] [000121] The number of filter layers may be different than 3 and may range from 2 to 20, optionally 2 to 10, and further optionally 2 to 5.

[0125] [000122] The multilayer optical filter 300 as a whole has a reflectivity of ±50×10 -6 , optionally ±20×10 -6 , and optionally ±5×10 -6 , and optionally ±2×10 -6 , and optionally ±1×10 -6 , and optionally 0.5×10 -6 Additionally or alternatively, the multilayer optical filter 300 may overall have a maximum 10% density of striae that results in an optical path difference of 30 nm, optionally have a maximum 5% density of striae that results in an optical path difference of 30 nm, further optionally have a maximum 2% density of striae that results in an optical path difference of 30 nm, further optionally have a maximum 1% density of striae that results in an optical path difference of 30 nm, and further optionally have no visible striae.

[0126] [000123] Filter layers 300-1, 300-2, 300-3 may be the same thickness or may be different thicknesses depending on the filtering characteristics of filter 300, as discussed above, since the transmittance of a filter is directly related to its thickness.

[0127] [000124] The filter layers 300-1, 300-2, and 300-3 of the exemplary filter 300 shown in Figure 5 may be configured to have planar major surfaces 306a-1, 306b-1, 306a-2, 306b-2, 306a-3, and 306b-3, respectively. Thus, the multi-layer filter 300 shown in Figure 5 has no optical power (diopters).

[0128] [000125] The filter layers may alternatively have refractive power, as illustrated in Figure 6. The filter 400 shown in Figure 6 includes a first filter layer 400-1, a second filter layer 400-2, and a third filter layer 400-3 sandwiched between the first filter layer 400-1 and the second filter layer 400-2 in the thickness direction z of the filter 400.

[0129] [000126] The first filter layer 400-1 and the second filter layer 400-2 may each be configured as an optical filter as described above. That is, the first filter layer 400-1 may include a first matrix 402-1 including a first optically transparent matrix material and first nanoparticles 404-1 embedded in the first matrix material, the first nanoparticles 404-1 including carbon atoms arranged in a hexagonal structure.

[0130] [000127] The first filter layer 400-1 may have a maximum refractive index variation of ±50×10 −6 and / or a maximum density of striae of 10% that results in an optical path difference of 30 nm.

[0131] Similarly, the second filter layer 400-2 may include a second matrix 402-2 including a second optically transparent matrix material and second nanoparticles 404-2 embedded in the second optically transparent matrix material, the second nanoparticles 404-2 including carbon atoms arranged in a hexagonal structure. The second filter layer 400-2 may have a maximum refractive index variation of ±50×10 and / or a maximum density of striae of 10% resulting in an optical path difference of 30 nm.

[0132] [000129] The third filter layer 400-3 may include a third matrix 402-3 that includes an optically transparent matrix material. The third filter layer 400-3 may not include nanoparticles that include carbon atoms arranged in a hexagonal structure.

[0133] 5, filter layers 400-1, 400-2, 400-3 have curved major surfaces 406a-1, 406b-1, 406a-2, 406b-2, 406a-3, 406b-3, and thus may have refractive power. Thus, filter 400 as a whole may have a refractive power (diopters). Because it is desirable to prepare the most photorefractive lens possible from layers with the highest refractive indices to reduce overall lens thickness and weight, filter layers 400-1, 400-2, 400-3 may have the same degree of curvature and refractive power (diopters), or may have different degrees of curvature and refractive power, depending on the desired mechanical and optical properties. The thicknesses of the different filter layers 400-1, 400-2, 400-3, as well as the ratio of the thicknesses of the different filter layers 400-1, 400-2, 400-3, may be different in different regions of the filter 400.

[0134] [000131] As noted above, each of the filters 300, 400 may have a filter layer that does not include nanoparticles containing hexagonally arranged carbon atoms. In filter 300, the third filter layer 300-3 is shown without nanoparticles containing hexagonally arranged carbon atoms. In filter 400, the third filter layer 400-3 is shown without nanoparticles containing hexagonally arranged carbon atoms. These filter layers 300-3, 400-3 can effectively separate adjacent filter layers 300-1, 300-2 and 400-1, 400-2, respectively. Therefore, these adjacent filter layers may include incompatible nanoparticles and / or incompatible matrix materials.

[0135] [000132] Filter layers 300-3, 400-3 that do not contain nanoparticles containing carbon atoms arranged in a hexagonal structure may contain inorganic material, optionally inorganic glass or mineral material, in a mass fraction of at least 50 wt%, optionally at least 80 wt%, and further optionally at least 95 wt%, based on the total mass (weight) of the respective filter layer 300-2, 400-3.

[0136] [000133] As indicated above, the mineral or inorganic glass containing filter layer 300-3, 400-3 is sandwiched in the thickness direction z between other filter layers 300-1 and 300-2 or 400-1 and 400-2, which may act as protective layers for the inorganic glass or mineral containing layer 300-3, 400-3.

[0137] [000134] In exemplary multi-layer filters that include multiple mineral or inorganic glass-containing filter layers, at least two of the multiple layers can be separated by at least one polymer or resin layer to prevent glass-to-glass contact and abrasion and / or spalling.

[0138] [000135] Mineral or inorganic glasses may be enriched with metals or metalloids, or their respective oxides, to enhance their optical or mechanical properties. Without limitation, the most preferred metals and metalloids include one or more of aluminum, barium, boron, calcium, cerium, didymium, gold, lead, magnesium, neodymium, niobium, platinum, potassium, praseodymium, silver, sodium, strontium, tin, titanium, and zirconium, as well as their respective oxides.

[0139] [000136] Filter layers 300-3, 400-3 that do not contain nanoparticles containing hexagonally arranged carbon atoms may contain a single reinforcing compound, or multiple reinforcing compounds to take advantage of the reinforcing properties of multiple compounds within a single layer. In the case of optical filters that contain multiple inorganic glass or mineral filter layers without nanoparticles containing hexagonally arranged carbon atoms, the layers may contain the same inorganic glass or mineral, or different inorganic glass or mineral materials, or mixtures or combinations thereof, to take advantage of the optical qualities of multiple different materials within a single optical filter. These layers may contain the same reinforcing compound or combinations of reinforcing compounds, or different reinforcing compounds or combinations thereof. A given glass or mineral filter layer may contain one or more reinforcing agents. The one or more reinforcing agents may account for 0.5 wt% to 70 wt%, preferably 5 wt% to 40 wt%, of the total weight of the respective inorganic glass or mineral filter layer.

[0140] 5, the filter layers 300-1, 300-2, and 300-3 may have substantially the same dimensions and / or shapes in a direction perpendicular to the thickness direction z. This also applies essentially to the filter 400 shown in FIG. 6. In these multilayer filters 300, 400, light rays pass through a substantially equal number of filter layers regardless of the angle of incidence and position on the filter 300, 400, thus resulting in a consistent image throughout the multilayer filter 300, 400. This configuration is particularly suitable for multilayer filters configured as plano or single diopter lenses.

[0141] [000138] Figure 7 illustrates an exemplary multi-layer filter 500 including multiple filter layers 500-1, 500-2, 500-3, 500-4, 500-5, 500-6, 500-7, and 500-8 stacked in the thickness direction z of the filter 500. The filter layers 500-2, 500-4, 500-6, and 500-8, indicated by the shaded areas in Figure 7, may include nanoparticles containing carbon atoms arranged in a hexagonal structure. As shown in Figure 7, the filter layers 500-1, 500-2, 500-3, 500-4, 500-5, 500-6, 500-7, and 500-8 have different dimensions, shapes, or dimensions and shapes perpendicular to the thickness direction z. In such a multi-layer filter, light rays pass through a variable number of filter layers depending on the angle of incidence and their position on the filter. Such a configuration is particularly suitable for progressive multifocal spectacle lenses or light filters for medical or technical use, since the refractive power and / or intensity of transmitted light can be different in different parts of the filter.

[0142] [000139] The optical filters 100, 200 or multi-layer filters 300, 400, 500 described above can be used as a protective top screen or incorporated into the screens of electronic devices (televisions, mobile phones, etc.). Alternatively, these filters can be used in eyeglasses or sunglasses, or as lenses in technical applications (cameras, binoculars, telescopes, lamps, etc.).

[0143] [000140] The optical filters 100, 200 and / or filter layers 300, 400, 500 described above may further include other particles that impart specific and unique optical properties, e.g., modify the refractive index. These other particles may include metals or metalloids or their respective oxides, chlorides, fluorides, iodides, or nitrates. Without limitation, the most preferred metals and metalloids are aluminum, antimony, barium, cerium, copper, didymium, gold, iron, lead, magnesium, molybdenum, neodymium, nickel, niobium, palladium, platinum, potassium, praseodymium, silicon, silver, tin, titanium, tungsten, vanadium, zinc, and zirconium, as well as their oxides, chlorides, fluorides, iodides, and nitrates. These other particles may all be of the same type, i.e., the same material, or may be a mixture of different materials. These other particles may have a diameter of 2 nm to 5 μm (e.g., an average diameter corresponding to the arithmetic mean), but most preferably 5 nm to 3 μm. They may all be the same diameter or may have different diameters. These other particles, comprising one or more of the aforementioned compounds, may account for 0 wt% to 80 wt%, preferably 5 wt% to 50 wt%, of the total mass of the nanoparticles.

[0144] [000141] The optical filters 100, 200, 300, 400, and 500 described above may further include one or more of the following: dyes (which may or may not have their own light filtering effect), ultraviolet light inhibitors, mold release agents, etc. Such additional components may also be added to filter layers that do not contain nanoparticles containing carbon atoms arranged in a hexagonal structure. The additional components may be dissolved, partially dissolved, or completely dissolved in the matrix material at the molecular level. Alternatively, the nanoparticles and / or other particles may exist as clusters or aggregates in the matrix depending on their composition, the method of introduction into the matrix material, and the desired optical quality. Individual clusters or aggregates may be homogeneous or may be a mixture of different nanoparticles / particle species. These clusters or aggregates may exhibit a regular, ordered structure or an irregular, disordered structure, and may be spherical, rod-like, amorphous, or crystalline, depending on their composition, preparation method, and desired optical quality. Within a given optical filter or optical filter layer, some of the other particles may exist as individual particles and some may simultaneously exist as clusters or aggregates.

[0145] [000142] Additionally, the nanoparticles may form their own visually distinct layer through controlled lowering or rising, but are most preferably homogeneously distributed throughout the matrix material.

[0146] [000143] Other particles may be dispersed in the matrix to such an extent that each particle is exclusively surrounded by and in contact with the matrix material.

[0147] [000144] Each of the above-described filters 100, 200, 300, 400, 500, as a whole, may further include an exterior coating. Without limitation, the most preferred coatings are hard protective coatings or other tinted, anti-reflective, anti-UV, or anti-polarizing coatings known in the art.

[0148] [000145] Additionally, the above-mentioned filter layers 300-1, 300-2, 300-3, 400-1, 400-2, 400-3, 500-1, ..., 500-8 may be separated by a thin coating or adhesive, or may be layered directly on top of each other, depending on the desired mechanical and optical properties.

[0149] [000146] Figure 8 is a flowchart of an exemplary method 600 for fabricating an optical filter according to the present disclosure. Method 600 may include step 602 of adding nanoparticles comprising carbon atoms arranged in a hexagonal structure to an optically transparent matrix material or a precursor of the optically transparent matrix material to obtain a mixture; step 604 of homogenizing the mixture to obtain a homogenized mixture; and step 606 of inserting the homogenized mixture into a mold to form the optical filter. This method 600 may be performed in the order described above. Any of the above-described nanoparticles and / or matrix materials described in the context of filters 100-500 above may be used to fabricate an optical filter according to this method 600.

[0150] [000147] Problems related to the extremely limited solubility of nanoparticles and excessive or uncontrolled clustering or agglomeration, which result in poor quality and unclear lenses, are overcome by homogenizing the mixture. The above-described method 600 thus enables the production of optical filters and multilayer filters with the above-described properties.

[0151] [000148] Nanoparticles with extremely limited solubility require dispersion in the matrix or precursor material as a colloidal suspension rather than as a solution, and then require dispersion and homogenization instead of dissolution. If dissolution of the nanoparticles is possible or necessary, their solubility in the optically clear matrix material or precursor to the optically clear matrix material must be determined. If only partial dissolution or no dissolution of the nanoparticles in the optically clear matrix material or precursor to the optically clear matrix material is desired or required, the important factor is the rate at which the nanoparticles settle or float, as calculated by the following equation, assuming the nanoparticles are spherical:

number

[0152] [000149] Where, Υ s is the settling or flotation velocity of the nanoparticles, V is the nanoparticle volume, and ρ p is the nanoparticle density, and ρ m is the density of the optically transparent matrix material or the precursor of the optically transparent matrix material, g is the acceleration of gravity, η is the viscosity of the optically transparent matrix material or the precursor of the optically transparent matrix material, and r is the nanoparticle radius.

[0153] [000150] The size of the nanoparticles and the density difference between the nanoparticles and the optically transparent matrix material or precursor of the optically transparent matrix material determine the rate at which the nanoparticles rise or fall, with smaller particles generally falling or rising more slowly than larger particles. The settling or rising rate is inversely proportional to the viscosity of the optically transparent matrix material or precursor of the optically transparent matrix material. When balanced with the time the mixture must rest before hardening, as well as the hardening time and the viscosity increase caused by the solidification or hardening of the optically transparent matrix material or precursor of the optically transparent matrix material, the most appropriate diameter of the nanoparticles or nanoparticle aggregates can be determined, and the most appropriate time for introducing the nanoparticles into the filter preparation process can be selected. When multiple matrix materials are used, the most appropriate individual or combination of these can be selected to disperse the nanoparticles.

[0154] [000151] Without wishing to be bound by any particular theory, the dispersibility of nanoparticles and the final diameter of the nanoparticles in a colloidal suspension is influenced by the shear force: τ=ηΥ m The effect is largely influenced by the ability of the fluid to mechanically break down and disperse the nanoparticle material using

[0155] where τ is the shear force on the nanomaterial during mixing, η is the viscosity of the optically transparent matrix material or precursor to the optically transparent matrix material, and Υ m is the velocity of the optically transparent matrix material or precursor to the optically transparent matrix material during mixing. The effectiveness of any such mixing and dispersing process depends on the liquid shear rate:

number

[0156] where R s is the shear rate and V uis the tip speed of the rotor (spinning unit for mixing the liquid, V u is determined by the rotor diameter and the rotor revolutions per minute), and D s is the distance between the rotor and the stator (the housing around the rotor). This allows for high shear rates to be achieved without being constrained by any single dimension of the equipment required to achieve high shear rates. High liquid shear forces, liquid velocities, and shear rates are necessary to obtain particularly fine nanoparticles, and therefore stable suspensions of nanoparticles within the optically transparent matrix material or precursor to the optically transparent matrix material. This process can be aided by selecting a high viscosity for the optically transparent matrix material or precursor to the optically transparent matrix material.

[0157] [000152] Homogenization of the mixture may include high speed homogenization at mixing speeds above 5000 rpm (revolutions per minute), optionally above 10000 rpm, and further optionally from 10000 rpm to 80000 rpm, and / or ultrasonic treatment at frequencies above 5 kHz, optionally above 10 kHz, and further optionally from 10 kHz to 80 kHz. Such homogenization of the mixture results in a colloidal suspension that effectively overcomes the problems resulting from the extremely limited solubility of nanoparticles in commonly used matrix materials or precursors of commonly used matrix materials.

[0158] [000153] The mixture was homogenized for 30,000 seconds. -1 Ultra, optional 50000 seconds -1 Ultra, and optionally 60,000 seconds -1 ~350000 seconds -1 Mixing at these shear rates contributes to a highly homogeneous distribution of the nanoparticles within the mixture.

[0159] [000154] Homogenization can be performed at a temperature above room temperature and below the melting point, boiling point, or decomposition temperature of the matrix material or precursor of the matrix material. Alternatively, when nanoparticles are added to the precursor of the matrix material, homogenization can be performed below room temperature to control the stability of the precursor and increase the viscosity, which improves the shear capacity of the precursor.

[0160] [000155] Because the presence of gases or bubbles in the material can produce optically inferior filters, mixing can be performed under vacuum, for example, at pressures less than 0.1 bar, optionally less than 0.01 bar, and even optionally less than 0.001 bar, to prevent mixing and dissolution of gases into the mixture. Mixing can be performed under an inert gas atmosphere to prevent reaction or oxidation of either the matrix or precursor materials or the nanoparticles or additives, which could impair the optical or mechanical properties of the filter. Nanoparticles can be mixed with or added to the filter together with other additives, such as antioxidants, UV stabilizers, dyes, and mold release agents. When multiple types of nanoparticles are added, they can be added simultaneously or at different stages during the mixing process, depending on the degree of homogenization desired for the different nanoparticle species.

[0161] [000156] During the addition of the nanoparticles to the optically transparent matrix material or the precursor of the optically transparent matrix material, the optically transparent matrix material or the precursor of the optically transparent matrix material can be in a liquid state to obtain a liquid mixture, and / or the mixture can be in a liquid state during homogenization. By these means, the degree of homogeneity can be further improved. Alternatively, when a thermoplastic resin is used for or as the matrix material, the nanoparticles can be added to the thermoplastic resin in granular or powder form before dissolving.

[0162] [000157] The degree of uniformity can be further improved by adding a surfactant to the liquid mixture or homogenized mixture. The use of a surfactant can be particularly important when a uniform dispersion of nanoparticles without dissolution is desired, or when a protective layer around the nanoparticles is desired to prevent direct interaction of the precursor material with the matrix material. The surfactant may be added before, simultaneously with, or after the nanoparticles, depending on the type of nanoparticles and their interaction with the surfactant and the matrix or precursor material. When high-speed homogenization is used, the surfactant is most preferably added after homogenization to avoid excessive foaming. One or more surfactants may be used, and they may be added simultaneously or at different times during the process.

[0163] [000158] The weight ratio of surfactant to nanoparticles can range from 1:1 to 50:1, optionally from 10:1 to 35:1. Suitable surfactants are those selected from the group consisting of nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants, or mixtures thereof. Although not particularly limited, the most preferred surfactants include one or more of dodecyltrimethylammonium chloride, myristyltrimethylammonium bromide, sodium lauryl sulfate, Triton X-100, Tween (Polysorbate) 20, Tween (Polysorbate) 60, and Tween (Polysorbate) 80.

[0164] [000159] In an exemplary method, a surfactant may be added to the homogenized mixture, and the homogenized mixture may be subjected to low speed homogenization at a mixing speed of less than 10,000 rpm, optionally between 200 rpm and 10,000 rpm, before inserting the homogenized mixture into a mold.

[0165] [000160] In an exemplary method, nanoparticles may be dispersed or dissolved in a matrix or precursor material in an amount less than that required to produce the optical filter (bulk material) to produce a concentrate, which may then be added to the bulk material. In this manner, homogenization may be facilitated.

[0166] 9 is a flowchart of an exemplary method 700 for making a liquid mixture, according to an exemplary embodiment. Method 700 may further include step 702: dissolving nanoparticles in a solvent miscible with the liquid matrix material or a liquid precursor of the optically transparent matrix material to obtain a first premixture; step 704: adding the first premixture to the liquid optically transparent matrix material or a liquid precursor of the optically transparent matrix material to obtain a second premixture; and step 706: heating the second premixture to a temperature above the boiling point of the solvent and below the boiling point or decomposition temperature of the optically transparent matrix material or a precursor of the optically transparent matrix material to obtain a liquid mixture. Method 700 may improve mixture uniformity and reduce or control nanoparticle aggregation.

[0167] [000162] The optically transparent matrix material or precursor to the optically transparent matrix material can include a thermoplastic polymer, a thermosetting polymer, a resin precursor, or a mixture thereof.

[0168] [000163] The method may further include mechanically treating the filter after it is removed from the mold and / or applying a coating, such as a protective coating and / or an anti-reflective coating, to one or more surfaces of the filter.

[0169] [000164] In the case of filters containing a single layer, the filters, whether in plano form or with diopter, can be cast as a final product. They may also be cast as thicker blank filters or lenses that are then subsequently cast and annealed and formed into the final product through a combination of cutting, grinding, and polishing. Hard protective coatings or other coatings, such as tinted, anti-reflective, anti-UV, or anti-polarizing coatings, may be applied.

[0170] [000165] In the case of a multi-layer filter, the filter layers may be fabricated sequentially in a suitable mold, with a particular filter layer fabricated on top of, i.e., the surface of, an already cured or semi-cured filter layer. Prior to fabrication of a filter layer on top of an already cured or semi-cured filter layer in the mold, the surface of the cured or semi-cured filter layer may be mechanically and / or chemically treated, e.g., scraped, to increase the surface area to enhance adhesion between the filter layers. The appropriate surface treatment and degree of curing are selected depending on the materials that will be in contact with each other and the balance between obtaining an optimal degree of adhesion between successive filter layers and the risk of them reacting with each other when uncured or semi-cured.

[0171] [000166] Alternatively or additionally, the surface of an already cured or semi-cured filter layer may be coated with a thin layer of adhesive or uncured resin, provided that this does not significantly interfere with the clarity of the filter or the quality of the image viewed through the filter.

[0172] [000167] To ensure complete cure and strong adhesion between the filter layers, this thin layer of adhesive or uncured resin may contain one or more polymerization free radical initiators or catalysts that are the same or different from those found within one or both of the bulk filter materials in contact with it.

[0173] [000168] In the case of a multi-layer filter comprising at least two filter layers having different dimensions and / or shapes perpendicular to the thickness direction, such as the filter shown in Figure 7, in addition to casting, the final product can be obtained through a combination of cutting, grinding and polishing to remove the full thickness of one or more layers at one or more locations on one or both of the major surfaces of the filter.

[0174] [000169] Below are described several examples according to the present disclosure.

[0175] [000170] Example 1 is an optical filter including a matrix including an optically transparent matrix material and nanoparticles including carbon atoms arranged in a hexagonal structure embedded in the matrix material, wherein at least one of the nanoparticles may be physically separated from the other nanoparticles, and / or at least one nanoparticle aggregate including the plurality of nanoparticles may have a maximum diameter of less than 30 nm, and each nanoparticle of the at least one nanoparticle aggregate is in physical contact with at least another one of the nanoparticles of the at least one nanoparticle aggregate.

[0176] [000171] In Example 2, the optical filter of Example 1 is ±50×10 -6 and / or having a maximum density of striae of 10% that results in a maximum refractive index variation of 30 nm.

[0177] [000172] In Example 3, the optical filter according to Example 1 or 2 can optionally further include: the nanoparticles include one or both of graphene nanoparticles and carbon nanotubes.

[0178] [000173] In Example 4, the optical filter according to any one of Examples 1-3 can optionally further include: the nanoparticles comprise nanoparticles comprising carbon atoms arranged in a pentagonal structure, optionally fullerenes, further optionally endohedral fullerenes.

[0179] [000174] In Example 5, the optical filter according to Example 4 may optionally further include that the nanoparticles comprise, within their carbon composite structure, endohedral fullerenes containing one or more of a metal dopant, a metalloid dopant, or their respective oxides, chlorides, fluorides, iodides, or nitrates.

[0180] [000175] In Example 6, the optical filter according to any one of Examples 1-5 can optionally further include one or more of the nanoparticles comprising one or more functional groups.

[0181] [000176] In Example 7, the optical filter according to Example 6 can optionally further include the one or more functional groups being or including one or more of an amide, an amine, a carbonyl, a carboxyl, an epoxide, an ester, a halide, a hydroxyl, an isocyanate, an isothiocyanate, a thiol, and a sulfur-containing group.

[0182] [000177] In Example 8, the optical filter according to any one of Examples 1-7 may optionally further include that the matrix material comprises one or more of an acrylate-based polymer, a polycarbonate-based polymer, a urethane-based polymer, a thiourethane-based polymer, an epoxy-based polymer, and an episulfide-based polymer, or other polymers or resins exhibiting an aromatic structure.

[0183] [000178] In Example 9, the optical filter according to any one of Examples 1-8 can optionally further include: the matrix material comprising an inorganic material, optionally an inorganic glass material, in an amount of at least 50 wt%, optionally at least 80 wt%, and further optionally at least 95 wt%, based on the total weight of the matrix material.

[0184] [000179] Example 10 is a multilayer optical filter including a plurality of filter layers stacked in the thickness direction, wherein one or more of the plurality of filter layers is configured as an optical filter according to any one of Examples 1 to 9.

[0185] [000180] In Example 11, the multilayer optical filter according to Example 10 may optionally further include the plurality of filter layers including first and second filter layers configured as an optical filter according to any one of Examples 1 to 9 having different nanoparticle compositions, or different matrix materials, or different nanoparticle compositions and different matrix materials.

[0186] [000181] In Example 12, the multilayer optical filter according to Examples 10 or 11 can optionally further include at least one filter layer of the plurality of filter layers not including nanoparticles comprising carbon atoms arranged in a hexagonal structure.

[0187] [000182] In Example 13, the multilayer optical filter according to Example 12 can optionally further include at least one filter layer that does not include nanoparticles comprising carbon atoms arranged in a hexagonal structure comprises an inorganic material, optionally an inorganic glass material, in an amount of at least 50 wt%, optionally at least 80 wt%, and further optionally at least 95 wt%, based on the total weight of the at least one filter layer.

[0188] [000183] In Example 14, the multilayer optical filter according to any one of Examples 10 to 13 may optionally further include that at least two of the plurality of filter layers have different dimensions, or different shapes, or different dimensions and shapes in a direction perpendicular to the thickness direction.

[0189] [000184] Example 15 is a method for producing an optical filter, the method including the steps of adding nanoparticles including carbon atoms arranged in a hexagonal structure to an optically transparent matrix material or a precursor of the optically transparent matrix material to obtain a mixture; homogenizing the mixture to obtain a homogenized mixture; and inserting the homogenized mixture into a mold to form the optical filter.

[0190] [000185] In Example 16, the method according to Example 15 can optionally further include, wherein homogenizing the mixture includes one or both of high speed homogenization at a mixing speed of greater than 5000 rpm, optionally greater than 10000 rpm, and further optionally between 10000 rpm and 80000 rpm, and ultrasonic treatment at a frequency of greater than 5 kHz, optionally greater than 10 kHz, and further optionally between 10 kHz and 80 kHz.

[0191] [000186] In Example 17, the method according to Examples 15 or 16 is carried out by homogenizing the mixture for 30,000 seconds. -1 Ultra, optional 50000 seconds -1 Ultra, and optionally 60,000 seconds -1 ~350000 seconds -1 The method may optionally further comprise mixing at a shear rate of

[0192] [000187] In Example 18, the method according to any one of Examples 15-17 can optionally further include, during adding the nanoparticles to the optically transparent matrix material or precursor of the optically transparent matrix material, the optically transparent matrix material or precursor of the optically transparent matrix material being in a liquid state to obtain a liquid mixture, and / or during homogenizing the mixture, the mixture being in a liquid state.

[0193] [000188] In Example 19, the method according to Example 18 can optionally further include a surfactant being added to the liquid mixture or the homogenized mixture.

[0194] [000189] In Example 20, the method according to Example 19 can optionally further include a weight ratio of surfactant to nanoparticles ranging from 1:1 to 50:1, optionally from 10:1 to 35:1.

[0195] [000190] In Example 21, the method according to Example 19 or 20 can optionally further include the surfactant being selected from the group consisting of a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant, or a mixture thereof.

[0196] [000191] In Example 22, the method according to any one of Examples 19-21 can optionally further include adding a surfactant to the homogenized mixture, and subjecting the homogenized mixture to low speed homogenization at a mixing speed of less than 10,000 rpm, optionally between 200 rpm and 10,000 rpm, prior to inserting the homogenized mixture into a mold.

[0197] [000192] In Example 23, the method according to any one of Examples 18-22 may optionally further include the steps of dissolving nanoparticles in a solvent miscible with the liquid matrix material or the liquid precursor of the optically transparent matrix material to obtain a first premixture; adding the first premixture to the liquid optically transparent matrix material or the liquid precursor of the optically transparent matrix material to obtain a second premixture; and heating the second premixture to a temperature higher than the boiling point of the solvent and lower than the boiling point or decomposition temperature of the optically transparent matrix material or the precursor of the optically transparent matrix material to obtain a liquid mixture.

[0198] [000193] In Example 24, the method according to any one of Examples 15-23 can optionally further include the optically transparent matrix material or a precursor to the optically transparent matrix material comprising a thermoplastic polymer, a thermosetting polymer, a resin precursor, or a mixture thereof.

Claims

1. a matrix comprising an optically transparent matrix material; nanoparticles comprising carbon atoms arranged in a hexagonal structure embedded in a matrix material, at least one of the nanoparticles is physically separated from the other nanoparticles; and / or an optical filter, wherein at least one nanoparticle aggregate comprising a plurality of said nanoparticles has a maximum diameter of less than 30 nm, and each nanoparticle of said at least one nanoparticle aggregate is in physical contact with at least another one of the nanoparticles of said at least one nanoparticle aggregate.

2. ±50×10 －６ 2. The optical filter according to claim 1, wherein the maximum density of striae that cause a maximum refractive index variation of 100 nm and / or an optical path difference of 30 nm is 10%.

3. 3. The optical filter of claim 1, wherein the nanoparticles comprise one or both of graphene nanoparticles and carbon nanotubes.

4. 4. The optical filter of claim 1, wherein the nanoparticles comprise nanoparticles comprising carbon atoms arranged in a pentagonal structure, optionally fullerenes, further optionally endohedral fullerenes.

5. 5. The optical filter of claim 4, wherein the nanoparticles comprise endohedral fullerenes containing within their carbon composite structure one or more of a metal dopant, a metalloid dopant, or their respective oxides, chlorides, fluorides, iodides, or nitrates.

6. The optical filter of any one of claims 1 to 5, wherein one or more of the nanoparticles comprises one or more functional groups.

7. 7. The optical filter of claim 6, wherein the one or more functional groups are or include one or more of an amide, an amine, a carbonyl, a carboxyl, an epoxide, an ester, a halide, a hydroxyl, an isocyanate, an isothiocyanate, a thiol, and a sulfur-containing group.

8. 8. The optical filter according to claim 1, wherein the matrix material comprises one or more of an acrylate-based polymer, a polycarbonate-based polymer, a urethane-based polymer, a thiourethane-based polymer, an epoxy-based polymer, and an episulfide-based polymer, or other polymer or resin exhibiting an aromatic structure.

9. 9. The optical filter of claim 1, wherein the matrix material comprises an inorganic material, optionally an inorganic glass material, in an amount of at least 50 wt %, optionally at least 80 wt %, further optionally at least 95 wt %, based on the total weight of the matrix material.

10. A multilayer optical filter including a plurality of filter layers stacked in a thickness direction, A multilayer optical filter, wherein one or more filter layers of a plurality of filter layers are configured as the optical filter according to any one of claims 1 to 9.

11. 11. The multilayer optical filter of claim 10, wherein the plurality of filter layers comprises first and second filter layers configured as an optical filter according to any one of claims 1 to 9, each having a different nanoparticle composition, or a different matrix material, or a different nanoparticle composition and a different matrix material.

12. 12. The multilayer optical filter of claim 10 or 11, wherein at least one filter layer of the plurality of filter layers does not contain nanoparticles comprising carbon atoms arranged in a hexagonal structure.

13. 13. The multilayer optical filter of claim 12, wherein at least one filter layer that does not contain nanoparticles comprising carbon atoms arranged in a hexagonal structure comprises an inorganic material, optionally an inorganic glass material, in an amount of at least 50 wt %, optionally at least 80 wt %, and further optionally at least 95 wt %, based on the total weight of the at least one filter layer.

14. 14. The multilayer optical filter according to claim 10, wherein at least two of the plurality of filter layers have different dimensions, different shapes, or different dimensions and shapes in a direction perpendicular to the thickness direction.

15. 1. A method for manufacturing an optical filter, comprising: adding nanoparticles comprising carbon atoms arranged in a hexagonal structure to an optically transparent matrix material or a precursor of an optically transparent matrix material to obtain a mixture; homogenizing the mixture to obtain a homogenized mixture; inserting the homogenized mixture into a mold to form an optical filter; A method comprising:

16. said step of homogenizing the mixture further comprising: high speed homogenization at mixing speeds above 5000 rpm, optionally above 10000 rpm, and further optionally between 10000 rpm and 80000 rpm; and Sonication at frequencies above 5 kHz, optionally above 10 kHz, and further optionally between 10 kHz and 80 kHz 16. The method of claim 15, comprising one or both of:

17. The mixture is homogenized for 30,000 seconds. －１ Ultra, optional 50,000 seconds －１ Ultra, and optionally 60,000 seconds －１ ~350000 seconds －１ 17. The method of claim 15 or 16, comprising mixing at a shear rate of

18. during the addition of the nanoparticles to the optically transparent matrix material or the precursor of the optically transparent matrix material, the optically transparent matrix material or the precursor of the optically transparent matrix material is in a liquid state, and a liquid mixture is obtained; and / or While homogenizing the mixture, the mixture is in a liquid state. The method according to any one of claims 15 to 17.

19. 20. The method of claim 18, wherein a surfactant is added to the liquid mixture or the homogenized mixture.

20. 20. The method of claim 19, wherein the weight ratio of surfactant to nanoparticles ranges from 1:1 to 50:1, optionally from 10:1 to 35:

1.

21. 21. The method of claim 19 or 20, wherein the surfactant is selected from the group consisting of a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant, or a mixture thereof.

22. 22. The method according to any one of claims 19 to 21, wherein the surfactant is added to the homogenized mixture, and before inserting the homogenized mixture into a mould, the homogenized mixture is subjected to low speed homogenization at a mixing speed of less than 10,000 rpm, optionally between 200 rpm and 10,000 rpm.

23. the nanoparticles are dissolved in a solvent miscible with a liquid matrix material or a liquid precursor of an optically transparent matrix material to obtain a first premixture; adding the first premix to a liquid optically transparent matrix material or a liquid precursor of the optically transparent matrix material to obtain a second premix; the second premixture is heated to a temperature above the boiling point of the solvent and below the boiling point or decomposition temperature of the optically transparent matrix material or a precursor of the optically transparent matrix material to obtain a liquid mixture; The method according to any one of claims 18 to 22.

24. 24. The method of any one of claims 15 to 23, wherein the optically transparent matrix material or precursor to the optically transparent matrix material comprises a thermoplastic polymer, a thermosetting polymer, a resin precursor, or a mixture thereof.

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