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WO2025224582A1 - Filtre d'interférence et son procédé de fabrication - Google Patents

Filtre d'interférence et son procédé de fabrication

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Publication number
WO2025224582A1
WO2025224582A1 PCT/IB2025/054082 IB2025054082W WO2025224582A1 WO 2025224582 A1 WO2025224582 A1 WO 2025224582A1 IB 2025054082 W IB2025054082 W IB 2025054082W WO 2025224582 A1 WO2025224582 A1 WO 2025224582A1
Authority
WO
WIPO (PCT)
Prior art keywords
layer
optical stack
layers
plane
interference filter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/IB2025/054082
Other languages
English (en)
Inventor
Kenneth Jarefors
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
3M Innovative Properties Co
Original Assignee
3M Innovative Properties Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 3M Innovative Properties Co filed Critical 3M Innovative Properties Co
Publication of WO2025224582A1 publication Critical patent/WO2025224582A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/28—Interference filters
    • G02B5/281—Interference filters designed for the infrared light
    • G02B5/282—Interference filters designed for the infrared light reflecting for infrared and transparent for visible light, e.g. heat reflectors, laser protection
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B27/0172—Head mounted characterised by optical features
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/281—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for attenuating light intensity, e.g. comprising rotatable polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/28—Interference filters
    • G02B5/285—Interference filters comprising deposited thin solid films

Definitions

  • the present disclosure relates generally to an interference filter for an automatic darkening filter and a method of manufacturing the interference filter.
  • Automatic darkening filters are often provided on a protective headgear, where protection from high intensity light is desired.
  • Automatic darkening filters generally include a switchable filter and an interference filter.
  • the interference filter may include a plurality of dielectric layers and a plurality of metallic layers alternating with the plurality of dielectric layers .
  • the interference filter may attenuate infrared radiation, blue light, and ultraviolet radiation.
  • each of the plurality of metallic layers may need to be uniform while being thin (e.g., less than 15 nanometers in thickness). However, it may be difficult to produce metallic layers that are uniform as well as thin.
  • the present disclosure provides an interference filter for an automatic darkening filter.
  • the interference filter includes a substrate that is optically transparent.
  • the interference filter further includes an optical stack disposed on the substrate.
  • the optical stack includes a plurality of first layers and a plurality of second layers alternating with the plurality of first layers.
  • the optical stack defines a plane and a total stack area in the plane of the optical stack.
  • Each first layer of the plurality of first layers is dielectric.
  • Each second layer of the plurality of second layers is metallic.
  • Each second layer defines athickness normal to the plane.
  • the thickness of each second layer is less than 40 nanometers (run).
  • Each second layer includes a plurality of discrete clusters extending along the plane of the optical stack and the thickness of the second layer.
  • each second layer further includes a plurality of voids extending through the thickness of the second layer and having a total void area in the plane of the optical stack.
  • An average largest cluster dimension of the plurality of discrete clusters of each second layer measured along the plane of the optical stack is less than 70 nm.
  • the total void area of each second layer is less than 1% of the total stack area of the optical stack.
  • the present disclosure provides an automatic darkening filter.
  • the automatic darkening filter includes a switchable filter that changes from a light transmission state to a dark transmission state in response to an activation signal.
  • the automatic darkening filter further includes the interference filter of the first aspect.
  • the interference filter is disposed on the switchable filter.
  • the present disclosure provides a protective headgear.
  • the protective headgear includes the automatic darkening filter of the second aspect.
  • the present disclosure provides a method of manufacturing an interference fdter for an automatic darkening fdter.
  • the method includes providing a substrate that is optically transparent.
  • the method further includes forming an optical stack on the substrate by depositing a plurality of second layers on a plurality of first layers, such that the plurality of second layers alternate with the plurality of first layers to form the optical stack on the substrate.
  • the optical stack defines a plane and a total stack area in the plane of the optical stack.
  • Each first layer of the plurality of first layers is dielectric.
  • Each second layer of the plurality of second layers is metallic.
  • Each second layer defines a thickness normal to the plane. The thickness of each second layer is less than 40 nanometers (nm).
  • Each second layer includes a plurality of discrete clusters extending along the plane of the optical stack and the thickness of the second layer.
  • the plurality of discrete clusters is spaced apart from each other, such that each second layer further includes a plurality of voids extending through the thickness of the second layer and having a total void area in the plane of the optical stack.
  • An average largest cluster dimension of the plurality of discrete clusters of each second layer measured along the plane of the optical stack is less than 70 nm.
  • the total void area of each second layer is less than 1% of the total stack area of the optical stack.
  • FIG. 1 is a schematic cross-sectional view of an interference filter for an automatic darkening filter according to an embodiment of the present disclosure
  • FIG. 2A is a schematic top view of a second layer of the interference filter of FIG. 1 in isolation according to an embodiment of the present disclosure
  • FIG. 2B is a schematic partial cross-sectional view of the interference filter of FIG. 1 depicting a first layer and an adjacent second layer in isolation according to an embodiment of the present disclosure
  • FIG. 3 is a schematic exploded perspective view of an automatic darkening fdter according to an embodiment of the present disclosure
  • FIG. 4 is a schematic perspective view of a protective shield including the automatic darkening fdter of FIG. 3 according to an embodiment of the present disclosure
  • FIG. 5 is a flowchart depicting various steps of a method of manufacturing an interference fdter according to an embodiment of the present disclosure
  • FIG. 6A is a photograph of a first sample that was produced by depositing pure silver on a base layer
  • FIG. 6B is a photograph of a second sample that was produced by depositing copper doped silver on a base layer
  • FIG. 7A illustrates SEM images of the first sample of FIG. 6A obtained using a scanning electron microscope
  • FIG. 7B illustrates SEM images of the second sample of FIG. 6B obtained using a scanning electron microscope
  • FIG. 8 is a graph depicting transmittance versus wavelength for various first samples and second samples
  • FIG. 9 is a graph depicting photopic transmittance versus deposition rate
  • FIG. 10A is a graph depicting transmittance versus wavelength for various first samples after heat treatment.
  • FIG. 10B is a graph depicting transmittance versus wavelength for various second samples after heat treatment.
  • the term “generally,” unless otherwise specifically defined, means that the property or attribute would be readily recognizable by a person of ordinary skill but without requiring absolute precision or a perfect match (e.g., within +/- 20 % for quantifiable properties).
  • the term “substantially,” unless otherwise specifically defined, means to a high degree of approximation (e.g., within +/- 10% for quantifiable properties) but again without requiring absolute precision or a perfect match.
  • first and second are used as identifiers. Therefore, such terms should not be construed as limiting of this disclosure.
  • the terms “first” and “second” when used in conjunction with a feature or an element can be interchanged throughout the embodiments of this disclosure.
  • first material when termed as “similar” to a second material, at least 90 weight % of the first and second materials are identical and any variation between the first and second materials comprises less than about 10 weight % of each of the first and second materials.
  • “at least one of A and B” should be understood to mean “only A, only B, or both A and B.”
  • the term “transmittance” broadly refers to the percentage of energy in a given region of the electromagnetic spectrum (e.g., visible, infrared, or any other range) that is transmitted across a surface.
  • optically transparent refers to the ability of light to transmit through a material.
  • An element that is optically transparent has a high light transmittance (e.g., greater than 80%) over at least a portion of the visible light spectrum (from about 400 nm to about 700 nm).
  • luminous transmittance and “photopic transmittance” both refer to a weighted mean of the transmittance in the visible wavelength range, i.e., from about 380 nm to about 780 nm.
  • dielectric refers to non-metallic and non-electrically conducting materials.
  • a layer that is dielectric is made of one or more dielectric materials.
  • the term “refractive index” broadly refers to the absolute refractive index of a material which is understood to be the ratio of the speed of electromagnetic radiation in free space to the speed of electromagnetic radiation in that material.
  • the refractive index can be measured using known methods and is generally measured using an Abbe Refractometer in the visible light region.
  • the present disclosure relates to an interference filter for an automatic darkening filter.
  • the interference filter includes a substrate that is optically transparent.
  • the interference filter further includes an optical stack disposed on the substrate.
  • the optical stack includes a plurality of first layers and a plurality of second layers alternating with the plurality of first layers.
  • the optical stack defines a plane and a total stack area in the plane of the optical stack.
  • Each first layer of the plurality of first layers is dielectric.
  • Each second layer of the plurality of second layers is metallic.
  • Each second layer defines a thickness normal to the plane.
  • each second layer is less than 40 nanometers (nm).
  • Each second layer includes a plurality of discrete clusters extending along the plane of the optical stack and the thickness of the second layer. The plurality of discrete clusters is spaced apart from each other, such that each second layer further includes a plurality of voids extending through the thickness of the second layer and having a total void area in the plane of the optical stack.
  • An average largest cluster dimension of the plurality of discrete clusters of each second layer measured along the plane of the optical stack is less than 70 nm.
  • the total void area of each second layer is less than 1% of the total stack area of the optical stack.
  • Each second layer having the average largest cluster dimension less than 70 nm and the total void area less than 1% of the total stack area may be highly uniform (i.e., have a substantially uniform thickness with reduced defects, such as discrete clusters and void areas).
  • the high uniformity of each second layer may improve an optical performance (i.e., improved luminous transmittance, reduced light scattering, and improved attenuation of near infrared radiation) of the interference filter.
  • each second layer may be made from doped silver, that is, silver and a dopant.
  • the dopant may include copper (Cu), aluminum (Al), zinc (Zn), silicon carbide (SiC), or combinations thereof.
  • Making each second layer from the doped silver may improve the uniformity of the second layer. Specifically, making each second layer from the doped silver may reduce both the average largest cluster dimension of the plurality of discrete clusters and the total void area of the plurality of voids of the second layer. As discussed above, the high uniformity of each second layer may improve the optical performance of the interference filter.
  • each second layer from the doped silver can allow reducing the thickness of the second layer while maintaining the high uniformity of the second layer.
  • the thickness of each second layer may be in a range of from 6 nm to 12 nm.
  • the doped silver may therefore allow forming ultrathin and uniform second layers.
  • a mixture of the silver and the dopant may be deposited at a higher deposition rate as compared to pure silver without compromising the uniformity of the resulting second layer.
  • the mixture of the silver and the dopant may provide a much greater flexibility in the deposition rate as compared to pure silver, and in some cases, may expedite manufacturing of the interference fdter.
  • FIG. 1 illustrates a schematic cross-sectional view of an interference filter 100 for an automatic darkening filter according to an embodiment of the present disclosure.
  • the interference filter 100 shown in FIG. 1 may be alternatively referred to as an “induced transmittance filter.”
  • the interference filter 100 includes a substrate 102 that is optically transparent.
  • the substrate 102 includes glass or aluminum oxide (A12O3).
  • the substrate 102 may include soda-lime glass, borosilicate glass, aluminosilicate glass, or any other suitable glass based on desired application attributes.
  • the substrate 102 may have any suitable thickness depending on desired application attributes.
  • the interference filter 100 further includes an optical stack 104 disposed on the substrate 102.
  • the optical stack 104 defines a plane 110 (schematically depicted by a line in FIG. 1) and a total stack area in the plane 110 of the optical stack 104.
  • the optical stack 104 includes a plurality of first layers 106 and a plurality of second layers 108 alternating with the plurality of first layers 106.
  • Each first layer 106 of the plurality of first layers 106 is dielectric.
  • each first layer 106 includes silicon dioxide (SiO2), titanium dioxide (TiO2), tantalum pentoxide (Ta2O5), aluminum oxide (A12O3), hafnium oxide (HfO2), zinc sulfide (ZnS), or combinations thereof.
  • Each first layer 106 may define a thickness 106T normal to the plane 110.
  • the thickness 106T of each first layer 106 may be selected based on desired application attributes.
  • the thicknesses 106T of the plurality of first layers 106 may be same or different. Further, the plurality of first layers 106 may have same or different refractive indices.
  • one or more first layers 106 of the plurality of first layers 106 may be multi-layered. In other words, in some embodiments, the one or more first layers 106 may be made up of a plurality of dielectric layers.
  • Each second layer 108 of the plurality of second layers 108 is metallic.
  • Each second layer 108 defines a thickness 108T normal to the plane 110.
  • the thickness 108T of each second layer 108 is less than 40 nanometers (nm).
  • FIG. 2A illustrates a schematic top view of one second layer 108 of the plurality of second layers 108 in isolation according to an embodiment of the present disclosure.
  • FIG. 2B illustrates a schematic partial cross-sectional view of the interference filter 100 of FIG. 1 depicting one second layer 108 and one first layer 106 adjacent to the one second layer 108 in isolation according to an embodiment of the present disclosure.
  • the plane 110 of the optical stack 104 (shown in FIG. 1) is also depicted in FIGS. 2A and 2B.
  • each second layer 108 includes a plurality of discrete clusters 112 (schematically depicted as circles in FIG. 2A) extending along the plane 110 of the optical stack 104 and the thickness 108T of the second layer 108.
  • Each discrete cluster 112 of the plurality of discrete clusters 112 may include a largest cluster dimension 112L in the plane 110 of the optical stack 104.
  • the plurality of discrete clusters 112 of each second layer 108 may define an average largest cluster dimension.
  • the average largest cluster dimension may be a mean or an average of the largest cluster dimensions 112L of the plurality of discrete clusters 112 of the respective second layer 108.
  • each second layer 108 further includes a plurality of voids 114 (schematically depicted as dashed ovals in FIG. 2A) extending through the thickness 108T of the second layer 108 and having a total void area in the plane 110 of the optical stack 104.
  • the total void area may be a sum of the areas of the plurality of voids 114 of the respective second layer 108 in the plane 110.
  • the total void area of each second layer 108 may be the total area of the plurality of voids 114 ofthe second layer 108.
  • the total void area may correspond to an area ofan adjacent first layer 106 that is not covered by the second layer 108.
  • the average largest cluster dimension and the total void area may be determined using a Scanning Electron Microscope (SEM).
  • the average largest cluster dimension of the plurality of discrete clusters 112 of each second layer 108 measured along the plane 110 of the optical stack 104 is less than 70 nm.
  • each second layer 108 is less than 1% of the total stack area of the optical stack 104.
  • Each second layer 108 having the average largest cluster dimension less than 70 nm and the total void area less than 1% of the total stack area may be highly uniform (i.e., have a substantially uniform thickness with reduced defects, such as discrete clusters and void areas).
  • the high uniformity of each second layer 108 may improve an optical performance (i.e., improved luminous transmittance, reduced light scattering, and improved attenuation of near infrared radiation) of the interference filter 100.
  • each second layer 108 includes silver in an amount of from 95% to 99.5%, by weight.
  • Each second layer 108 further includes a dopant in an amount of from 0.5% to 5%, by weight.
  • the dopant includes copper (Cu), aluminum (Al), zinc (Zn), silicon carbide (SiC), or combinations thereof.
  • Making each second layer 108 from the aforementioned composition of silver and the dopant may improve the uniformity of the second layer 108. Specifically, making each second layer 108 from the doped silver may reduce both the average largest cluster dimension of the plurality of discrete clusters 112 and the total void area of the plurality of voids 114 ofthe second layer 108. As discussed above, the high uniformity of each second layer 108 may improve the optical performance of the interference fdter 100.
  • each second layer 108 from the doped silver can allow reducing the thickness 108T of the second layer 108 while maintaining the high uniformity of the second layer 108.
  • the thickness 108T of each second layer 108 may be less than 12 nm.
  • the thickness 108T of each second layer 108 may be in a range of from 6 nm to 12 nm.
  • the doped silver may thus allow forming ultrathin and uniform second layers 108.
  • the average largest cluster dimension may be from 48 nm to 68 nm.
  • the total void area of each second layer 108 may be less than 0.1% of the total stack area of the optical stack 104, such that the second layer 108 substantially covers an adjacent first layer 106 of the plurality of first layers 106. This configuration of the plurality of second layers 108 may further improve the optical characteristics of the interference filter 100.
  • the interference filter 100 may further include a dielectric stack (not shown).
  • the dielectric stack may be disposed on the optical stack 104, such that the optical stack 104 is disposed between the dielectric stack and the substrate 102.
  • the dielectric stack may be disposed between the optical stack 104 and the substrate 102.
  • the dielectric stack may be disposed between two layers of the optical stack 104.
  • the dielectric stack may include a plurality of dielectric layers stacked on top of each other. The plurality of dielectric layers may have same or different refractive indices. In some cases, alternating dielectric layers from the plurality of dielectric layers may have alternating high and low refractive indices.
  • a first dielectric layer from the plurality of dielectric layers may have a high refractive index and a second dielectric layer adjacent to the first dielectric layer may have a low refractive index.
  • the interference filter 100 may therefore employ a combination of the dielectric stack and the optical stack 104, based on desired application attributes.
  • the interference filter 100 may be configured to attenuate the infrared (IR), blue light, and ultraviolet (UV) wavelength components from a high intensity light. In some embodiments, the interference filter 100 may eliminate hazardous IR, blue light, and UV wavelength components from the high intensity light.
  • IR infrared
  • UV ultraviolet
  • FIG. 3 illustrates a schematic exploded perspective view of an automatic darkening filter 10 according to an embodiment of the present disclosure.
  • the automatic darkening filter 10 includes a switchable filter 40 that changes from a light transmission state to a dark transmission state in response to an activation signal.
  • the automatic darkening filter 10 further includes the interference filter 100.
  • the interference filter 100 is disposed on the switchable filter 40.
  • the interference filter 100 may be removably disposed on the switchable filter 40, such that the interference filter 100 is replaceable.
  • the switchable filter 40 includes a first polarization filter 14, a first optically rotating liquid crystal cell 16, a second polarization filter 18, a second optically rotating liquid crystal cell 20, a third polarization filter 22, and a fourth polarization filter 26.
  • the polarization filters 14, 18, 22 may have substantially orthogonal polarization directions.
  • the polarization direction of the second polarization filter 18 may be substantially orthogonal to the polarization direction of the first polarization filter 14, and the third polarization filter 22 may have substantially the same polarization direction as the first polarization filter 14. Further, the third polarization filter 22 and the fourth polarization filter 26 may have substantially parallel polarization directions.
  • the switchable filter 40 further includes a low twist color-tunable liquid crystal cell 24 disposed between the third polarization filter 22 and the fourth polarization filter 26.
  • the low twist color-tunable liquid crystal cell 24 may be similar in design as the liquid crystal cells 16, 20, but its operation is different because it is sandwiched between parallel polarizers 22, 26, as opposed to crossed polarizers.
  • the liquid crystal cells 16, 20, 24 may be provided with connectors 30, 32, 34, respectively, by which control voltages can be applied.
  • Each of the liquid crystal cells 16, 20 may include liquid crystal defining surfaces. Nematic crystal molecules may take specific angular positions so that the nematic crystal molecules are twisted through their respective twist angle between the defining surfaces.
  • the application of a voltage to connectors 30 and 32 may create an electric field between the defining surfaces.
  • the nematic liquid crystal molecules may align with the electric field perpendicular to the defining surfaces, rather than parallel to them, and the cell achieves a darkened state.
  • a control voltage is applied to the low twist cells 16, 20, a filter effect may be obtained.
  • the degree of rotation of the nematic crystal molecules may be controlled by varying the control voltage, and thus the corresponding filter effect may also be controlled.
  • the result is that liquid crystal cells 16, 20 may be in the light transmission state in the absence of an applied voltage, and in the dark transmission state in the presence of an applied voltage.
  • the voltage levels may be different for varying cell designs, depending on the liquid crystal materials used, different cell gap geometries, etc.
  • FIG. 4 illustrates a schematic perspective view of a protective headgear 50 according to an embodiment of the present disclosure.
  • the protective headgear 50 includes the automatic darkening filter 10.
  • the protective headgear 50 is a shield 60 (e.g., safety shield, also known as helmet).
  • the shield 60 includes a shield body 62.
  • the automatic darkening filter 10 may be positioned in the shield body 62 such that the automatic darkening filter 10 is directly in front of the eyes of a user when the shield 60 is worn by the user.
  • the automatic darkening filter 10 may intercept electromagnetic radiation (e.g., visible light, UV light, IR, etc.).
  • the automatic darkening filter 10 may be removably connected to the shield body 62.
  • the automatic darkening filter 10 may be provided in any other suitable equipment or articles and for other applications.
  • the automatic darkening filter 10 may be supplied as part of protective eyewear (e.g. goggles) rather than the fullcoverage shield 60.
  • the automatic darkening filter 10 may be provided in a handheld device, or in a window or aperture allowing inspection of a room, enclosure, machinery space etc., in which high intensity light may be present.
  • the automatic darkening filter 10 may be used in connection with industrial operations, for example welding (e.g. arc welding, torch welding, acetylene welding), cutting (e.g. laser cutting, acetylene cutting), brazing, soldering and the like.
  • the automatic darkening filter 10 may also be used in connection with medical procedures involving high intensity light, for example, laser surgery, hair removal, tattoo removal, light-curing of dental resins.
  • FIG. 5 illustrates a flowchart of a method 200 of manufacturing an interference filter (e.g., the interference filter 100 of FIG. 1) for an automatic darkening filter (e.g., the automatic darkening filter 10 of FIG. 3) according to an embodiment of the present disclosure.
  • the method 200 will be described with further reference to FIGS. 1 to 4.
  • the method 200 includes providing a substrate that is optically transparent.
  • the method 200 may include providing the substrate 102.
  • the method 200 further includes forming an optical stack on the substrate by depositing a plurality of second layers on a plurality of first layers, such that the plurality of second layers alternate with the plurality of first layers to form the optical stack on the substrate .
  • the optical stack defines a plane and a total stack area in the plane of the optical stack.
  • Each first layer of the plurality of first layers is dielectric.
  • Each second layer of the plurality of second layers is metallic.
  • Each second layer defines athickness normal to the plane.
  • the thickness of each second layer is less than 40 nm.
  • Each second layer includes a plurality of discrete clusters extending along the plane of the optical stack and the thickness of the second layer.
  • each second layer further includes a plurality of voids extending through the thickness of the second layer and having a total void area in the plane of the optical stack.
  • An average largest cluster dimension of the plurality of discrete clusters of each second layers measured along the plane of the optical stack is less than 70 nm.
  • the total void area of each second layer is less than 1% of the total stack area of the optical stack.
  • the method 200 may include forming the optical stack 104 on the substrate 102 by depositing the plurality of second layers 108 on the plurality of first layers 106, such that the plurality of second layers 108 alternate with the plurality of first layers 106 to form the optical stack 104 on the substrate 102.
  • the average largest cluster dimension is from 48 nm to 68 nm. In some embodiments, the total void area of each second layer is less than 0.1% of the total stack area of the optical stack, such that the second layer substantially covers an adjacent first layer of the plurality of first layers.
  • each second layer includes silver in an amount of from 95% to 99.5%, by weight.
  • Each second layer further includes a dopant in an amount of from 0.5% to 5%, by weight.
  • the dopant includes copper (Cu), aluminum (Al), zinc (Zn), silicon carbide (SiC), or combinations thereof.
  • the thickness of each second layer is less than 12 nm.
  • each first layer includes silicon dioxide (SiO2), titanium dioxide (TiO2), tantalum pentoxide (Ta2O5), aluminum oxide (A12O3), hafnium oxide (HfO2), zinc sulfide (ZnS), or combinations thereof.
  • the substrate includes glass or aluminum oxide (A12O3).
  • each second layer is deposited on the adjacent first layer by physical vapor deposition (PVD) using athermal resistive source or electron gun evaporation.
  • PVD physical vapor deposition
  • each second layer 108 may be deposited on the adjacent first layer 106 by physical vapor deposition (PVD) using a thermal resistive source or electron gun evaporation. PVD may be suitable and preferable process for depositing each second layer 108.
  • each second layer is deposited by evaporating a mixture of the silver and the dopant.
  • each second layer 108 may be deposited by evaporating a mixture of silver and the dopant.
  • a deposition rate of each second layer on the adjacent first layer is greater than 8 angstroms per second.
  • a deposition rate of each second layer 108 on the adjacent first layer 106 may be greater than 8 angstroms per second.
  • the mixture of the silver and the dopant may be deposited at a higher deposition rate as compared to pure silver without compromising the uniformity of the resulting second layer 108.
  • the mixture of the silver and the dopant may provide a much greater flexibility in the deposition rate as compared to pure silver, and in some cases, may expedite manufacturing of the interference filter.
  • a plurality of first samples was prepared by coating pure silver on the base layer. Further, a plurality of second samples was prepared by coating a mixture of 98.5% silver and 1.5% Cu (also referred to as “copper doped silver” herein) on the base layer. Granulates of size ranging from 2 millimeter (mm) to 5 mm were used to deposit the mixture (copper doped silver) on the base layer.
  • FIG. 6A is a photograph of one first sample.
  • FIG. 6B is a photograph of one second sample. Referring to FIGS. 6A and 6B, it was observed that the second sample (shown in FIG. 6B) with the copper doped silver coating exhibited reduced light scattering as compared to the first sample (shown in FIG. 6A) with the pure silver coating. Specifically, the second sample exhibited reduced “wide angle forward scattering,” which was visually observable. The first sample and the second sample were then tested in accordance with ISO 18526-2:2020, 14.2 (Test methods for eye and face protection). About 2% to 4% improvement in the second sample with respect to the first sample was observed.
  • FIG. 7A illustrates SEM images of different sections of the first sample obtained using a scanning electron microscope.
  • FIG. 7B illustrates SEM images of different sections of the second sample obtained using the scanning electron microscope.
  • an average largest cluster dimension of discrete clusters formed in the pure silver layer from three sections was calculated to be from 84 nm to 99 nm.
  • a noncovered area (i.e., area of the base layer not covered by the pure silver layer) of the three sections was calculated to be from 1.7% to 4.5% of the total area of the base layer.
  • an average largest cluster dimension of discrete clusters formed in the copper doped silver layer from three sections was calculated to be from 48 nm to 68 nm. Further, the copper doped silver layer substantially covered the base layer. That is, a non-covered area of the base layer was zero.
  • the copper doped silver layer was smoother, more uniform, and had much smaller discrete clusters as compared to the first sample (shown in FIG. 7A).
  • FIG. 8 illustrates a graph 300 depicting transmittance (y-axis, in %) versus wavelength (x- axis, in nm) for some first samples and some second samples.
  • the graph 300 includes a calculated curve 301 (dashed) depicting an ideal or desirable relation between transmittance and wavelength for the samples produced for experimental purposes and having the structure: ⁇ metallic layer/base layer/glass substrate ⁇ .
  • the graph 300 further includes a first curve 302 (long-dash short-dashed) depicting a variation of transmittance with respect to wavelength for one first sample (having pure silver layer) and a second curve 304 (long -dash double short-dashed) depicting a variation of transmittance with respect to wavelength for one second sample (having copper doped silver layer).
  • the graph 300 also includes other curves depicting variations of transmittance with respect to wavelength for other samples, but they are not designated by reference characters for clarity purposes.
  • the best performing first and second samples correspond to first and second curves 302, 304, respectively. It was noted that the second curve 304 was closer to the calculated curve 301 than the first curve 304.
  • the second sample corresponding to the second curve 304 transmitted greater than 60% of a substantially normally incident light for each wavelength in a visible wavelength range extending from about 400 nm to about 520 nm.
  • the second sample exhibited higher transmittance in the visible wavelength range extending from about 400 nm to about 520 nm.
  • the second sample exhibited better luminous transmittance than the first sample.
  • the second sample corresponding to the second curve 304 transmitted less than 30% of the substantially normally incident light for each wavelength in an infrared wavelength range extending from about 960 nm to about 1000 nm.
  • the second sample exhibited lower transmittance (or higher reflectance) in the infrared wavelength range extending from about 960 nm to about 1000 nm.
  • the second sample exhibited better infrared reflectance (or infrared attenuation) than the first sample.
  • FIG. 9 illustrates a graph 350 depicting photopic transmittance (y-axis, in %) versus deposition rate (x-axis, in angstroms/second) for the samples prepared by the pure silver and the copper doped silver.
  • the graph 350 includes a first curve 352 depicting a variation of photopic transmittance with respect to deposition rate of the pure silver on the base layer for the first samples.
  • the graph 350 further includes a second curve 354 depicting a variation of photopic transmittance with respect to deposition rate of copper doped silver layer on the base layer for the second samples.
  • the photopic transmittance of the first samples was very sensitive to the deposition rate of the pure silver.
  • the photopic transmittance of the second samples was less sensitive to the deposition rate of the copper doped silver. It was concluded that the copper doped silver allowed a much greater flexibility in the deposition rate as compared to pure silver. Also, the copper doped silver could be deposited at a higher deposition rate (e.g., greater than 8 angstroms/seconds) without negatively affecting the photopic transmittance of the produced second sample.
  • the first samples and the second samples were also tested for robustness to heat. Some first samples and some second samples were heat treated at 100 degrees Celsius for 10 minutes. Further, some first samples and some second samples were heat treated at 290 degrees Celsius for 10 seconds.
  • the first samples that were heat treated at 100 degrees Celsius for 10 minutes exhibited minor visual degradation.
  • the second samples that were heat treated at 100 degrees Celsius for 10 minutes exhibited no visual change.
  • the first samples that were heat treated at 290 degrees Celsius for 10 seconds also exhibited minor visual degradation.
  • the second samples that were heat treated at 290 degrees Celsius for 10 seconds exhibited no visual change.
  • FIG. 10A illustrates a graph depicting transmittance (y-axis, in %) versus wavelength (x- axis, in nm) for the first samples that were heat treated as well as the first samples that were not heat treated.
  • the graph 400 includes reference curves 401A, 401B, 401C, 401D (solid) depicting variation of transmittance versus wavelength for four first samples that were not heat treated.
  • the graph 400 further includes first curves 402A, 402B (long-dash double short-dashed) depicting variation of transmittance with respect to wavelength for two first samples that were heat treated at 100 degrees Celsius for 10 minutes.
  • the graph 400 further includes second curves 404A, 404B (dashed) depicting variation of transmittance with respect to wavelength for two first samples that were heat treated at 290 degrees Celsius for 10 seconds.
  • the first samples that were heat treated at 100 degrees Celsius for 10 minutes exhibited significantly degraded photopic transmittance as compared to those first samples (corresponding to the reference curves 401A, 401B, 401C, 40 ID) that were not heat treated.
  • the first samples that were heat treated at 290 degrees Celsius for 10 seconds also exhibited substantially degraded photopic transmittance as compared to those first samples (corresponding to the reference curves 401A, 401B, 401C, 401D) that were not heat treated. It was noted that the pure silver layers degraded significantly when exposed to high temperatures, which detrimentally affected the photopic transmittance of the first samples.
  • FIG. 10B illustrates a graph 450 depicting transmittance (y-axis, in %) versus wavelength (x-axis, in nm) for the second samples that were heat treated as well as the second samples that were not heat treated.
  • the graph 450 includes reference curves 451A, 45 IB (solid) depicting variation of transmittance with respect to wavelength for two second samples that were not heat treated.
  • the graph 400 further includes a first curve 452 (long-dash double short-dashed) depicting a variation of transmittance with respect to wavelength for a second sample that was heat treated at 100 degrees Celsius for 10 minutes.
  • the graph 400 further includes second curves 454A, 454B (dashed) depicting variation of transmittance with respect to wavelength for two second samples that were heat treated at 290 degrees Celsius for 10 seconds.
  • the second sample that was heat treated at 100 degrees Celsius for 10 minutes exhibited similar photopic transmittance as compared to those second samples (corresponding to the reference curves 451 A, 45 IB) that were not heat treated.
  • the second samples that were heat treated at 290 degrees Celsius for 10 seconds also exhibited similar photopic transmittance as compared to those second samples (corresponding to the reference curves 451 A, 45 IB) that were not heat treated. It was noted that the copper doped silver layers were robust to high temperatures, and as a result, the photopic transmittance of the second samples exposed to high temperatures was not negatively affected.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Filters (AREA)

Abstract

L'invention concerne un filtre d'interférence comprenant un empilement optique disposé sur un substrat optiquement transparent. L'empilement optique comprend une pluralité de premières couches alternant avec une pluralité de secondes couches. Chaque seconde couche comprend une pluralité de groupes discrets s'étendant le long d'un plan de l'empilement optique et une épaisseur de la seconde couche. La pluralité de groupes discrets est espacée les uns des autres, de telle sorte que chaque seconde couche comprend en outre une pluralité de vides s'étendant à travers l'épaisseur de la seconde couche et ayant une zone de vide totale dans le plan de l'empilement optique. Une dimension de groupe la plus grande moyenne de la pluralité de groupes discrets de chaque seconde couche mesurée le long du plan de l'empilement optique est inférieure à 70 nanomètres et la zone de vide totale chaque seconde couche est inférieure à 1% d'une zone d'empilement totale de l'empilement optique.
PCT/IB2025/054082 2024-04-22 2025-04-17 Filtre d'interférence et son procédé de fabrication Pending WO2025224582A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4799745A (en) * 1986-06-30 1989-01-24 Southwall Technologies, Inc. Heat reflecting composite films and glazing products containing the same
US20170200526A1 (en) * 2014-05-23 2017-07-13 The Regents Of The University Of Michigan Ultra-thin doped noble metal films for optoelectronics and photonics applications
US20200139935A1 (en) * 2017-04-17 2020-05-07 3E Nano Inc. Energy control coatings, structures, devices, and methods of fabrication thereof
US20200390606A1 (en) * 2016-05-12 2020-12-17 3M Innovative Properties Company Protective headgear comprising a curved switchable shutter and comprising multiple antireflective layers

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4799745A (en) * 1986-06-30 1989-01-24 Southwall Technologies, Inc. Heat reflecting composite films and glazing products containing the same
US4799745B1 (fr) * 1986-06-30 1992-02-25 Southwall Technologies Inc
US20170200526A1 (en) * 2014-05-23 2017-07-13 The Regents Of The University Of Michigan Ultra-thin doped noble metal films for optoelectronics and photonics applications
US20200390606A1 (en) * 2016-05-12 2020-12-17 3M Innovative Properties Company Protective headgear comprising a curved switchable shutter and comprising multiple antireflective layers
US20200139935A1 (en) * 2017-04-17 2020-05-07 3E Nano Inc. Energy control coatings, structures, devices, and methods of fabrication thereof

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