CN118284831A - Durable optical window for light detection and ranging (LIDAR) applications - Google Patents

Abstract

There is provided a window for a sensing system, the window comprising: a substrate comprising an outer major surface and an inner major surface; an outer layered film disposed on the outer major surface; and an inner layered film disposed on the inner major surface. Each of the outer and inner layered films includes alternating high and low refractive index layers. The outer layered film includes a scratch resistant layer having a thickness of about 0.5 μm to about 10 μm and exhibiting a hardness of at least 11GPa as measured with a Berkovich indenter hardness test. The window exhibits an average transmittance of more than 85% (within + -25 nm) of at least one wavelength in the infrared spectrum from 900nm to 1600nm and an average transmittance of less than 5% in the visible spectrum from 420nm to 650nm, respectively, at an angle of incidence <15 deg..

Description

Durable optical window for light detection and ranging (LIDAR) applications

RELATED APPLICATIONS

The present application claims the benefit of priority from U.S. patent application Ser. No. 63/284,161, filed on day 35U.S. C. ≡119, month 11, day 2021, and from U.S. provisional application Ser. No. 63/409,443, filed on day 9, month 23, 2022, each of which is incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates generally to durable windows and articles for LIDAR applications having high transmission in the infrared spectrum and low transmission in the visible spectrum, particularly windows having outer and inner layered films with alternating high and low refractive index layers, as well as other features that support LIDAR driven optical properties.

Background

Light detection and ranging ("LIDAR") systems include lasers and sensors. The laser emits a laser beam that is reflected from the object, and the sensor detects the reflected laser beam. The laser beam is pulsed or otherwise distributed over a radial range to detect objects in the field of view. Information about the object may be decrypted from the detected properties of the reflected laser beam. The distance of the object from the laser beam may be determined from the time of flight from the emission of the laser beam to the detection of the reflected laser beam. If the object is moving, the path and velocity of the object can be determined from the displacement of the reflected and detected radial position of the emitted laser beam as a function of time, as well as from Doppler frequency measurements.

LIDAR systems in automobiles and other infrared sensing systems exposed to the environment, such as aerospace or home security applications, require protection from the environment and various sources of damage, for example, with cover lenses or cover glass windows. Vehicles are another potential application of LIDAR systems, where the LIDAR systems provide spatial mapping capabilities to enable assisted, semi-automated, or fully automated driving. In such applications, the laser transmitter and sensor are mounted on the roof of the vehicle or on the underside of the front of the vehicle. Lasers emitting electromagnetic radiation having wavelengths outside the visible range (such as 905nm or 1550 nm) are contemplated for use in vehicular LIDAR applications. In order to protect the laser and sensor from the impact of rocks and other objects, a window is placed between the laser and sensor and the external environment within the line of sight of the laser and sensor. For other applications of the LIDAR system, such as aerospace and home security applications, a window is similarly placed between the laser/sensor and the external environment. However, there are problems with rocks and other objects striking the window and causing other types of damage to the window, which can cause the window to scatter the emitted and reflected laser beam, thereby compromising the effectiveness of the LIDAR system.

LIDAR sensor performance is also known to be negatively affected by the presence of microwave radiation in the environment proximate the sensor. For example, a mobile phone that is in close proximity to the sensor may generate microwave radiation, which may reduce the efficiency of the sensor and the LIDAR system in which it is employed.

In addition, vehicle owners and vehicle manufacturers with LIDAR systems desire some aesthetics associated with these systems, in addition to the functional benefits provided by these systems. For example, vehicle manufacturers may prefer to configure the aesthetics (e.g., color) of the windows employed in these systems to match the aesthetics of other vehicle features (e.g., tinting of the headlamp lens cover, accent features, geolamp colors, etc.). In other cases, the owner may wish the LIDAR system (including its window) to exhibit a particular desired color, possibly to supplement the color of the vehicle body or to otherwise match the glare characteristics.

Thus, there is a need for durable windows and articles for LIDAR applications that have high transmission in the infrared spectrum and low transmission in the visible spectrum, as well as other attributes, including microwave shielding and/or controllable color development.

Disclosure of Invention

According to an aspect of the present disclosure, there is provided a window for a sensing system, comprising: a substrate comprising an outer major surface and an inner major surface, wherein the outer major surface and the inner major surface are opposite to each other; an outer layered film disposed on an outer major surface of the substrate; and an inner layered film disposed on the inner major surface of the substrate. The outer layered film includes a plurality of alternating high refractive index layers and low refractive index layers. The inner layered film includes a plurality of alternating high refractive index layers and low refractive index layers. Each of the high refractive index layers has a refractive index greater than that of each of the low refractive index layers. The outer layered film includes a scratch resistant layer having a thickness of about 0.5 μm to about 10 μm. The outer layered film exhibits a hardness of at least 11GPa as measured with a Berkovich indenter hardness test from the outermost surface of the outer layered film to a depth of 1 μm. Furthermore, the number, thickness and materials of the plurality of alternating high and low refractive index layers of the outer and inner layered films are configured such that the window exhibits an average transmittance of greater than 85% (within ±25 nm) of at least one wavelength in the infrared spectrum from 900nm to 1600nm and an average transmittance of less than 5% in the visible spectrum from 420nm to 650nm at an angle of incidence <15 °.

According to another aspect of the present disclosure, there is provided a window for a sensing system, comprising: a substrate comprising an outer major surface and an inner major surface, wherein the outer major surface and the inner major surface are opposite to each other; an outer layered film disposed on an outer major surface of the substrate; and an inner layered film disposed on the inner major surface of the substrate. The outer layered film includes a plurality of alternating high refractive index layers and low refractive index layers. The inner layered film includes a plurality of alternating high refractive index layers and low refractive index layers. Each of the high refractive index layers has a refractive index greater than that of each of the low refractive index layers. The outer layered film includes a scratch resistant layer having a thickness of about 0.5 μm to about 10 μm. Further, the inner layered film includes one or more absorbing layers, wherein each absorbing layer includes a refractive index of 3.0 or more, an extinction coefficient of 0.1 or more at one or more wavelengths in the ultraviolet and visible spectrum from 100nm to 700 nm. The outer layered film exhibits a hardness of at least 11GPa as measured with a Berkovich indenter hardness test from the outermost surface of the outer layered film to a depth of 1 μm. Furthermore, the number, thickness and materials of the plurality of alternating high and low refractive index layers of the outer and inner layered films are configured such that the window exhibits an average transmittance of greater than 85% (within ±25 nm) of at least one wavelength in the infrared spectrum from 900nm to 1600nm and an average transmittance of less than 5% in the visible spectrum from 420nm to 650nm at an angle of incidence <15 °.

According to a further aspect of the present disclosure, there is provided a window for a sensing system, comprising: a substrate comprising an outer major surface and an inner major surface, wherein the outer major surface and the inner major surface are opposite to each other; an outer layered film disposed on an outer major surface of the substrate; and an inner layered film disposed on the inner major surface of the substrate. The outer layered film includes a plurality of alternating high refractive index layers and low refractive index layers. The inner layered film includes a plurality of alternating high refractive index layers and low refractive index layers. Each of the high refractive index layers has a refractive index greater than that of each of the low refractive index layers. The outer layered film includes a scratch resistant layer having a thickness of about 0.5 μm to about 10 μm. In addition, the inner layered film or the outer layered film includes a transparent conductive oxide layer. The outer layered film exhibits a hardness of at least 11GPa as measured with a Berkovich indenter hardness test from the outermost surface of the outer layered film to a depth of 1 μm. Furthermore, the number, thickness and materials of the plurality of alternating high and low refractive index layers of the outer and inner layered films are configured such that the window exhibits an average transmittance of greater than 85% (within ±25 nm) of at least one wavelength in the infrared spectrum from 900nm to 1600nm and an average transmittance of less than 5% in the visible spectrum from 420nm to 650nm at an angle of incidence <15 °.

Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide an overview or framework for understanding the nature and character of the claims.

The accompanying drawings are included to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments and, together with the description, serve to explain the principles and operations of the various embodiments.

Drawings

FIG. 1 is a side view of a vehicle in an external environment illustrating a LIDAR system on the roof of the vehicle and another LIDAR system on the front of the vehicle;

FIG. 2 is a schematic diagram of one of the LIDAR systems of FIG. 1, illustrating an electromagnetic radiation emitter and sensor in a housing, the electromagnetic radiation emitted by the electromagnetic radiation emitter and sensor exiting the housing through a window and returning through the window as reflected radiation;

FIG. 3 is a cross-sectional view of two embodiments of the window of FIG. 2 taken at region III of FIG. 2, each window illustrated as including a substrate having an outer layered film over an outer major surface of the substrate and an inner layered film over an inner major surface of the substrate;

FIG. 4A is Sup>A cross-sectional view of one of the windows of FIG. 3, taken at region IV-A of FIG. 3, illustrating an outer layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein one layer of the one or more lower refractive index materials provides Sup>A terminal surface closest to the external environment;

FIG. 4B is a cross-sectional view of one of the windows of FIG. 3, taken at region IV-B of FIG. 3, illustrating an inner layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein one layer of the one or more lower refractive index materials provides a terminal surface closest to the electromagnetic radiation emitter and sensor;

FIG. 5A is Sup>A cross-sectional view of one of the windows of FIG. 3, taken at region V-A of FIG. 3, illustrating an outer layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein one layer of the one or more lower refractive index materials provides Sup>A terminal surface closest to the external environment;

FIG. 5B is a cross-sectional view of one of the windows of FIG. 3, taken at region V-B of FIG. 3, illustrating an inner layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein one layer of the one or more lower refractive index materials provides a terminal surface closest to the electromagnetic radiation emitter and sensor;

FIG. 6A is a graph of modeled dual-surface transmittance versus wavelength from 1500nm to 1600nm for an exemplary window of the present disclosure at normal incidence from the exterior and interior surfaces of the window;

FIG. 6B is a graph of modeled dual-surface S & P polarized transmittance versus wavelength from 1500nm to 1600nm for an exemplary window of the present disclosure at 60 incident from the outer and inner surfaces of the window;

FIG. 6C is a graph of modeled dual-surface reflectivity versus wavelength from 1500nm to 1600nm for an exemplary window of the present disclosure at normal incidence from the outer and inner surfaces of the window;

FIG. 6D is a graph of modeled dual-surface transmittance versus wavelength from 400nm to 700nm for an exemplary window of the present disclosure at normal incidence from the outer and inner surfaces of the window;

FIG. 6E is a graph of modeled reflected color from 90 incident normal to the exterior and interior surfaces of an exemplary window of the present disclosure;

FIG. 6F is a graph of measured Berkovich nanoindentation hardness versus displacement into the outer surface of an exemplary window of the present disclosure;

FIG. 6G is a graph of measured attenuation of microwave radiation through exemplary windows of the present disclosure versus thickness of indium zinc oxide layers within those windows;

FIG. 7A is a graph of modeled dual-surface transmittance versus wavelength from 1500nm to 1600nm for an exemplary window of the present disclosure at normal incidence from the exterior and interior surfaces of the window;

FIG. 7B is a graph of modeled dual-surface S & P polarized transmittance versus wavelength from 1500nm to 1600nm for an exemplary window of the present disclosure at 60 incident from the outer and inner surfaces of the window;

FIG. 7C is a graph of modeled dual-surface reflectivity versus wavelength from 1500nm to 1600nm for an exemplary window of the present disclosure at normal incidence from the outer and inner surfaces of the window;

FIG. 7D is a graph of modeled dual-surface transmittance versus wavelength from 400nm to 700nm for an exemplary window of the present disclosure at normal incidence from the outer and inner surfaces of the window;

FIG. 8A is a graph of modeled dual-surface transmittance versus wavelength from 1500nm to 1600nm for an exemplary window of the present disclosure at 15 ° angles of incidence from the outer and inner surfaces of the window;

FIG. 8B is a graph of modeled dual-surface S & P polarized transmittance versus wavelength from 1500nm to 1600nm for an exemplary window of the present disclosure at 60 incident from the outer and inner surfaces of the window;

FIG. 8C is a graph of modeled dual-surface reflectivity versus wavelength from 1500nm to 1600nm for an exemplary window of the present disclosure at 15 incident angles from the outer and inner surfaces of the window;

FIG. 8D is a graph of modeled dual-surface transmittance versus wavelength from 400nm to 700nm for an exemplary window of the present disclosure at 15 ° angles of incidence from the outer and inner surfaces of the window; and

Fig. 8E is a graph of modeled reflected colors of an exemplary window of the present disclosure when incident from perpendicular to 90 ° from the outer and inner surfaces of the window.

Detailed Description

In the following detailed description, for purposes of explanation and not limitation, example embodiments disclosing specific details are set forth in order to provide a thorough understanding of the various principles of the present disclosure. However, it will be apparent to one having ordinary skill in the art having had the benefit of the present disclosure, that the present disclosure may be practiced in other embodiments that depart from the specific details disclosed herein. In addition, descriptions of well-known devices, methods and materials may be omitted so as not to obscure the description of the various principles of the present disclosure. Finally, where applicable, like reference numerals refer to like elements.

Ranges may be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are related to the other endpoint, and independently of the other endpoint.

Directional terms used herein, such as "upper", "lower", "right", "left", "front", "rear", "top" and "bottom", refer only to the drawn figures and are not intended to imply absolute orientation.

Unless explicitly stated otherwise, any method set forth herein is not to be construed as requiring that its steps be performed in a specific order. Accordingly, if a method claim does not actually recite an order to be followed by its steps or it is not specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that an order be inferred. This applies to any possible non-explicit interpretation basis, including: logic matters related to step configuration or operation flow; plain meaning derived from grammatical organization or punctuation; the number or type of embodiments described in the specification.

As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component" includes aspects having two or more such components unless the context clearly indicates otherwise.

The present disclosure addresses the above-described problems and concerns with respect to LIDAR systems. The durable window of the present disclosure generally includes an inner layered film and an outer layered film, at least one of which includes one or more layers of a material that provides rigidity and scratch resistance to the window. Thus, rocks and other objects impacting the window are less likely to cause defects to the window that would scatter electromagnetic radiation emitted and reflected from the LIDAR sensor, thereby improving its performance. In addition, the layered film further comprises alternating layers of materials having different refractive indices (including materials that provide hardness and scratch resistance), such that the number of alternating layers and their thickness can be configured such that the window has high transmittance and low reflectance at infrared wavelengths (e.g., 905nm, 1550nm, etc.), and if desired, low transmittance and high reflectance at visible wavelengths. Further, one or both of the inner and outer layered films may include one or more layers that absorb ultraviolet and visible light wavelengths and/or may include one or more transparent conductive oxide layers that may provide microwave shielding, if desired.

Reference will now be made in detail to the present preferred embodiments, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

Referring now to FIG. 1, a vehicle 10 includes one or more LIDAR systems 12. One or more LIDAR systems 12 may be disposed anywhere on the vehicle 10 or within the vehicle 10. For example, one or more LIDAR systems 12 may be disposed on a roof 14 of the vehicle 10 and/or a front 16 of the vehicle 10.

Referring now to fig. 2, each of the one or more LIDAR systems 12 includes an electromagnetic radiation emitter and sensor 18, which may be enclosed in a housing 20 as is known in the art. Electromagnetic radiation emitter and sensor 18 emits electromagnetic radiation 22 having a wavelength or range of wavelengths. The emitted radiation 22 exits the housing 20 through windows 100a, 200a in the path of the emitted electromagnetic radiation. If an object (not shown) in the external environment 26 is in the path of the emitted radiation 22, the emitted radiation 22 will reflect off the object and return as reflected radiation 28 to the electromagnetic radiation emitter and sensor 18. The reflected radiation 28 again passes through the windows 100a, 200a to the electromagnetic radiation emitter and sensor 18. In an embodiment, the emitted radiation 22 and the reflected radiation 28 have a wavelength of 905nm or 1550nm or a range including 905nm or 1550nm wavelengths. Electromagnetic radiation other than reflected radiation 28, such as electromagnetic radiation having wavelengths in the visible spectrum, portions of the ultraviolet range, portions of the infrared range shorter than the desired 905nm and/or 1550nm wavelengths, and/or microwave radiation, may or may not pass through windows 100a, 200a, depending on the optical properties of windows 100a, 200a as described herein.

As used herein, "visible spectrum" is the portion of the electromagnetic spectrum visible to the human eye, generally referring to electromagnetic radiation having wavelengths in the range of about 380nm or 400nm to about 700 nm. The "ultraviolet range" is the portion of the electromagnetic spectrum having wavelengths between about 10nm and about 400 nm. The "infrared range" of the electromagnetic spectrum starts at about 700nm and extends to longer wavelengths. Solar electromagnetic radiation produced by the sun, commonly referred to as "sunlight", has wavelengths falling within these three ranges. Further, as used herein, "microwave radiation" is defined as electromagnetic radiation emitted at a frequency of 0.3GHz or greater (e.g., 0.3GHz to 100 GHz), including mobile telephones operating in 5G mobile telephone networks.

Referring now to fig. 3, a window 100a, 200a for each of one or more LIDAR systems 12 includes a substrate 30. The substrate 30 includes an outer major surface 32 and an inner major surface 34. The outer major surface 32 and the inner major surface 34 are major surfaces of the substrate 30 that are opposite each other. The outer major surface 32 is closest to the external environment 26. The inner major surface 34 is closest to the electromagnetic radiation emitter and sensor 18. The emitted radiation 22 encounters the inner major surface 34 before the outer major surface 32. The reflected radiation 28 encounters the outer major surface 32 before the inner major surface 34. The substrate 30 further includes an outer laminate film 36 disposed on the outer major surface 32 of the substrate 30, and an inner laminate film 38 disposed on the inner major surface 34 of the substrate 30. It should be appreciated that the windows 100a, 200a as described herein are not limited to vehicle applications, as further described herein, may be used in any application where the windows 100b, 200a would help provide improved impact and optical performance.

As used herein, the term "disposing" includes coating, depositing, and/or forming a material on a surface using any method known in the art. The disposed material may constitute a layer as defined herein. The phrase "disposed on …" includes the case where a material is formed on a surface such that the material is in direct contact with the surface, and also includes the case where: a material is formed on a surface, wherein there are one or more intervening materials between the disposed material and the surface. The intervening material may constitute a layer as defined herein.

The substrate 30 may be a glass substrate. The glass substrate may have a composition of soda lime glass, alkali alumino-silicate glass, alkali-containing borosilicate glass, and alkali alumino-borosilicate glass, although other glass compositions are contemplated. Such glass compositions can be chemically strengthened by ion exchange processes. In some variations, the composition may be free of lithium ions.

An alkali aluminosilicate glass composition suitable for use in substrate 30 includes alumina, at least one alkali metal, in some embodiments greater than 50 mole% SiO ₂, in other embodiments at least 58 mole% SiO ₂, and in still other embodiments at least 60 mole% SiO ₂, wherein the ratio (of Al ₂O₃+B₂O₃)/∑ _{Modifying agent} (i.e., sum of modifiers) is greater than 1, wherein the ratio of these components is expressed in mole% and the modifier is an alkali metal oxide.

Another suitable alkali aluminosilicate glass composition for substrate 30 includes: 64 to 68 mole% SiO ₂; 12 to 16 mole% Na ₂ O;8 to 12 mole% of Al ₂O₃; 0 to 3 mole% of B ₂O₃; 2 to 5 mole% of K ₂ O;4 to 6 mole% MgO; and 0 to 5 mole% CaO, wherein: 66 mol% or more of SiO ₂+B₂O₃ +CaO or less than 69 mol%; na ₂O+K₂O+B₂O₃ + MgO + CaO + SrO >10 mole%; mgO+CaO+SrO is more than or equal to 5 mol% and less than or equal to 8 mol%; (Na ₂O+B₂O₃)—Al₂O₃.ltoreq.2 mol.; na ₂O—Al₂O₃.ltoreq.6 mol.; 4 mol.; na ₂O+K₂O)-Al₂O₃.ltoreq.10 mol.; another suitable alkaline aluminosilicate glass composition for substrate 30 includes 2 mol% or more Al ₂O₃ and/or ZrO ₂, or 4 mol% or more Al ₂O₃ or/or ZrO ₂).

An example glass composition includes SiO ₂、B₂O₃ and Na ₂ O, where (SiO ₂+B₂O₃) is greater than or equal to 66 mole percent and Na ₂ O is greater than or equal to 9 mole percent. In an embodiment, the composition includes at least 6% by weight alumina. In further embodiments, the composition of one or more alkaline earth oxides, such as alkaline earth oxide content, is at least 5% by weight. In some embodiments, a suitable composition further comprises at least one of K ₂ O, mgO and CaO. In a particular embodiment, the composition of the substrate 30 includes 61 to 75 mole% SiO ₂; 7 to 15 mole% of Al ₂O₃; 0 to 12 mole% of B ₂O₃; 9 to 21 mole% Na ₂ O;0 to 4 mole% of K ₂ O;0 to 7 mole% MgO; and 0 to 3 mole% CaO.

Further example compositions suitable for use in substrate 30 include: 60 to 70 mole% SiO ₂; 6 to 14 mole% Al ₂O₃; 0 to 15 mole% of B ₂O₃; 0 to 15 mole% Li ₂ O; 0 to 20 mole% Na ₂ O;0 to 10 mole% of K ₂ O;0 to 8 mole% MgO;0 to 10 mole% CaO;0 to 5 mole% ZrO ₂; 0 to 1 mole% SnO ₂; 0 to 1 mole% CeO ₂; less than 50ppm As ₂O₃; and less than 50ppm Sb ₂O₃; wherein 12 mol% or less (Li ₂O+Na₂O+K₂ O) or less than 20 mol% and 0 mol% or less (MgO+CaO) or less than 10 mol%. Still further example glass compositions suitable for use in substrate 30 include: 63.5 to 66.5 mole% SiO ₂; 8 to 12 mole% of Al ₂O₃; 0 to 3 mole% of B ₂O₃; 0 to 5 mole% Li ₂ O; 8 to 18 mole% Na ₂ O;0 to 5 mole% of K ₂ O;1 to 7 mole% MgO;0 to 2.5 mole% CaO;0 to 3 mole% ZrO ₂; 0.05 to 0.25 mole% SnO ₂; 0.05 to 0.5 mole% CeO ₂; less than 50ppm As ₂O₃; and less than 50ppm Sb ₂O₃; wherein, the mol percent of Li ₂O+Na₂O+K₂ O is more than or equal to 14 and less than or equal to 18 mol percent and the mol percent of MgO+CaO is more than or equal to 2 and less than or equal to 7 mol percent.

The substrate 30 may be substantially planar or sheet-like, but other embodiments may use curved or other shaped or engraved substrates. The length and width of the substrate 30 may vary depending on the desired size of the windows 100a, 200 a. The substrate 30 may be formed using various methods, such as a float glass process and a downdraw process, such as fusion downdraw and slot downdraw. The substrate 30 may be used in a non-reinforced state. Commercially available examples of suitable non-reinforced substrates 30 for windows 100a, 200a areGlass 3, which is a soda-alumina-silica glass substrate.

The glass forming the substrate 30 may be modified to have regions associated with the outer major surface 32 and/or regions associated with the inner major surface 34 to withstand compressive stresses ("compressive stress, CS"). In such cases, the region subjected to compressive stress extends from the outer major surface 32 and/or the inner major surface 34 to one or more compression depths. This compressive stress generation further creates a central region that is subject to tensile stress, which has a maximum at the center of the central region, referred to as central tension (central tension or center tension, CT). The central region extends between the compression depths and is subjected to tensile stress. The tensile stress in the central region balances or counteracts the compressive stress in the region subjected to the compressive stress. As used herein, the terms "compressive depth" and "DOC (depth of compression)" refer to the depth at which the stress within the substrate 30 changes from compressive to tensile. At the compression depth, the stress changes from positive (compressive) to negative (tensile) stress, so the stress has a zero value. The compression depth protects the substrate 30 from crack propagation caused by a sharp impact to the outer major surface 32 and/or the inner major surface 34 of the substrate 30, while the compression stress minimizes the likelihood of crack growth and penetration of the compression depth. In an embodiment, the compression depths are each at least 20 μm. In embodiments, the absolute value of the maximum compressive stress CS within the region is at least 200MPa, at least about 400MPa, at least 600MPa, or up to about 1000MPa.

Two methods for extracting detailed and accurate stress curves (stress as a function of depth) of a substrate 30 having areas subject to compressive stress are disclosed in U.S. patent No. 9140543, entitled "System and method for measuring stress curves of ion exchange glasses," filed 5/3 in 2012 by Douglas CLIPPINGER ALLAN et al, and claims priority to U.S. provisional patent application No. 61/489800 filed 5/25 in 2011, the entire contents of which are incorporated herein by reference.

In an embodiment, creating the region(s) of the substrate 30 that are subjected to compressive stress includes subjecting the substrate 30 to an ion exchange chemical tempering process (chemical tempering is commonly referred to as "chemical strengthening"). In an ion exchange chemical tempering process, ions at or near the outer and inner major surfaces 32, 34 of the substrate 30 are replaced by or exchanged with larger ions, typically having the same valence or oxidation state. In embodiments in which the substrate 30 comprises, consists essentially of, or consists of an alkali alumino-silicate glass, an alkali borosilicate glass, an alkali alumino-borosilicate glass, or an alkali silicate glass, the ions and larger ions in the surface layer of the glass are monovalent alkali cations such as Na ⁺ (when Li ⁺ is present in the glass), K ⁺、Rb⁺, and Cs ⁺. Alternatively, monovalent cations in the outer and inner major surfaces 32, 34, at the outer and inner major surfaces 32, 34, or near the outer and inner major surfaces 32, 34 may be replaced with monovalent cations other than alkali metal cations, such as Ag ⁺ or the like.

In an embodiment, the ion exchange process is performed by immersing the substrate 30 in a molten salt bath containing larger ions to be exchanged with smaller ions in the substrate 30. Those skilled in the art will appreciate that the parameters for the ion exchange process, including but not limited to bath composition and temperature, soak time, number of dips of the glass in the salt bath (or baths), use of multiple salt baths and additional steps such as annealing, washing and the like, are generally determined by the composition of the substrate 30 and the desired depth of compression and compressive stress of the substrate 30 resulting from the strengthening operation. For example, ion exchange of alkali metal-containing glass substrates may be accomplished by immersion in at least one molten bath containing salts including, but not limited to, nitrates, sulfates and chlorides of the larger alkali metal ions. In an embodiment, the molten salt bath comprises potassium nitrate (0 to 100 wt%), sodium nitrate (0 to 100 wt%) and lithium nitrate (0 to 12 wt%), the combined potassium nitrate and sodium nitrate having a weight percentage in the range of 88 wt% to 100 wt%. In embodiments, the temperature of the molten salt bath is typically in the range of about 350 ℃ up to about 500 ℃ and the soaking time ranges from about 15 minutes up to about 40 hours, including from about 20 minutes up to about 10 hours. However, different temperatures and soak times than those described above may also be used. The substrate 30 may be pickled or otherwise treated to remove or reduce the effects of surface cracking.

The substrate 30 has a thickness 35 defined as the shortest linear distance between the outer major surface 32 and the inner major surface 34. In an embodiment, the thickness 35 of the substrate 30 is between about 100 μm and about 5 mm. According to one or more embodiments, the substrate 30 may have a physical thickness 35 ranging from about 100 μm to about 500 μm (e.g., 100, 200, 300, 400, or 500 μm). In other embodiments, the thickness 35 ranges from about 500 μm to about 1000 μm (e.g., 500, 600, 700, 800, 900, or 1000 μm). The thickness 35 may be greater than about 1mm (e.g., about 2, 3, 4, or 5 mm). In one or more embodiments, the thickness 35 is 2mm or less than 1mm. Commercially available compositions suitable for use with the substrate 30 that has been subjected to ion exchange areA glass, wherein the glass has a CS of about 850MPa, a DOC of about 40 microns, and a thickness 35 of 1.0 millimeter (millimeter, mm). Another commercially available example of a suitable strengthening (via ion exchange) substrate 30 for the windows 100a, 200a isGlass 3, which is a soda-alumina-silica glass substrate.

Instead of or in addition to glass, the substrate 30 may include or may be a layer of visible light absorbing, IR transmissive material. Examples of such materials include infrared transmissive, visible light absorbing acrylic sheets such as those commercially available under the trade name EPLASTICSIR ACRYLIC 3143 and CYROIR acrylic 1146。IR ACRYLIC 3143 has a transmission of about 0% (at least less than 10%, or less than 1%) for electromagnetic radiation having a wavelength of about 700nm or less, but about 90% (above 85%) for electromagnetic radiation having a wavelength in the range of 800nm to about 1100nm, including 905 nm.

In an embodiment, the substrate 30 comprises an organic or suitable polymeric material. Examples of suitable polymers include, but are not limited to: thermoplastics including Polystyrene (PS) (including styrene copolymers and blends), polycarbonate (PC) (including copolymers and blends), polyesters (including copolymers and blends, including polyethylene terephthalate and polyethylene terephthalate copolymers), polyolefins (PO) and cyclic polyolefins (cyclic-PO), polyvinylchloride (PVC), acrylic polymers including polymethyl methacrylate (PMMA) (including copolymers and blends), thermoplastic Polyurethane (TPU), polyetherimide (PEI), and blends of these polymers with each other. Other exemplary polymers include epoxy resins, styrene resins, phenolic resins, melamine resins, and silicone resins.

In an embodiment, the substrate 30 includes a plurality of layers or sublayers. The layers or sublayers of the substrate 30 may be the same composition or different compositions from each other. In an embodiment, for example, the substrate 30 comprises a glass laminate structure. In an embodiment, a glass laminate structure includes a glass window including a first panel and a first panel attached to one another through a suitable interlayer (e.g., a polymeric interlayer) disposed between the first panel and the second panel. In embodiments, the glass laminate structure comprises a glass-on-glass laminate structure formed through, for example, a fusion downdraw process. Glass-polymer laminates are also contemplated and are within the scope of the present disclosure. Any material capable of satisfying the optical requirements described herein may be used as the substrate 30.

In embodiments, the substrate 30 exhibits an average transmittance of about 85% or greater, about 86% or greater, about 87% or greater, about 88% or greater, about 89% or greater, about 90% or greater, about 91% or greater, or about 92% or greater over the visible wavelength range. In an embodiment, the substrate 30 includes a coloring component (e.g., a coloring layer or additive), and may optionally exhibit a color such as white, black, red, blue, green, yellow, orange, or the like.

In one or more embodiments, the substrate 30 exhibits a refractive index in the range of about 1.45 to about 1.55. As used herein, unless otherwise indicated, "refractive index" refers to the refractive index of a material (here, substrate 30) to electromagnetic radiation having a wavelength of 1550 nm. Here, "refractive index (REFRACTIVE INDEX)" is synonymous with "refractive index (index of refraction)".

Referring now to fig. 4A, 4B, 5A and 5B, each of the outer and inner layered films 36, 38 of the windows 100a, 200a includes a number of alternating layers of one or more high refractive index layers 40 and one or more low refractive index layers 42. As used herein, the terms "high refractive index" and "low refractive index" refer to refractive index values relative to each other wherein one or more of the refractive indices of the one or more high refractive index layers 40 are greater than one or more of the refractive indices of the one or more low refractive index layers 42. In an embodiment, the one or more high refractive index layers 40 have a refractive index of about 1.7 to about 4.0. In an embodiment, the one or more low refractive index layers 42 have a refractive index of about 1.3 to about 1.6. In other embodiments, one or more low refractive index layers 42 have a refractive index of about 1.3 to about 1.7, while one or more high refractive index layers 40 have a refractive index of about 1.9 to about 3.8. The difference in refractive index between any of the one or more high refractive index layers 40 and any of the one or more low refractive index layers 42 may be about 0.1 or greater, 0.2 or greater, 0.3 or greater, 0.4 or greater, 0.5 or greater, 0.6 or greater, 0.7 or greater, 0.8 or greater, 0.9 or greater, 1.0 or greater, 1.5 or greater, 2.0 or greater, 2.1 or greater, 2.2 or greater, or even 2.3 or greater.

Manipulation of the number (number) and thickness of the alternating layers may result in selective transmission of electromagnetic radiation within a range of wavelengths through windows 100a, 200a and, separately, selective reflectivity of electromagnetic radiation within a range of wavelengths from outer and inner layered films 36, 38 or through outer and inner layered films 36, 38 due to the difference in refractive index of the one or more high refractive index layers 40 and one or more low refractive index layers 42. Thus, each of the outer and inner layered films 36, 38 is a thin film filter having predetermined optical properties configured as a function of number, thickness, and layers selected as the one or more high refractive index layers 40 and the one or more low refractive index layers 42.

According to some implementations of the windows 100a, 200a shown in fig. 4A-5B, each of the high refractive index layers 40 has a physical thickness ranging from 25nm to 750nm, 40nm to 600nm, 50nm to 500nm, and all ranges and thickness values between the above ranges. According to some implementations of the windows 100a, 200a shown in fig. 4A-5B, each of the low refractive index layers 42 has a physical thickness ranging from 5nm to 800nm, 10nm to 700nm, 15nm to 600nm, and all ranges and thickness values between the above ranges.

Some examples of suitable materials for use as the one or more low refractive index layers 42 include SiO₂、Al₂O₃、GeO₂、SiO、AlO_xN_y、SiO_xN_y、Si_uAl_vO_xN_y、MgO、MgAl₂O₄、MgF₂、BaF₂、CaF₂、DyF₃、YbF₃、YF₃ and CeF ₃. The nitrogen content of the material used as the one or more low refractive index layers 42 may be minimized (e.g., in materials such as AlO _xN_y、SiO_xN_y and Si _uAl_vO_xN_y).

Some examples of suitable materials for the one or more high refractive index layers 40 include amorphous silicon (a-Si)、SiN_x、SiN_x:H_y、AlN_x、Si_uAl_vO_xN_y、Ta₂O₅、Nb₂O₅、AlN、Si₃N₄、AlO_xN_y、SiO_xN_y、HfO₂、TiO₂、ZrO₂、Y₂O₃、Al₂O₃、MoO₃ and diamond-like carbon. The oxygen content of the material of the high refractive index layer 40 may be minimized, particularly in the SiN _x or AlN _x material. The AlO _xN_y material may be considered as oxygen doped AlN _x, i.e., it may have an AlN _x crystal structure (e.g., wurtzite), and need not have an AlON crystal structure. An exemplary preferred AlO _xN_y material for use as the one or more high-index layers 40 may include about 0 atomic% to about 20 atomic% oxygen, or about 5 atomic% to about 15 atomic% oxygen, while including 30 atomic% to about 50 atomic% nitrogen. Exemplary preferred Si _uAl_vO_xN_y for use as the one or more high-index layers 40 may include about 10 to about 30 or about 15 to about 25 atomic percent silicon, about 20 to about 40 or about 25 to about 35 atomic percent aluminum, about 0 to about 20 or about 1 to about 20 atomic percent oxygen, and about 30 to about 50 atomic percent nitrogen. The above materials may be hydrogenated to up to about 30% by weight. Because the refractive indices of the one or more high refractive index layers 40 and the one or more low refractive index layers 42 are relative to each other, the same material (such as Al ₂O₃) may be suitable for the one or more high refractive index materials 40, depending on the refractive index of the material(s) selected for the one or more low refractive index materials 42; alternatively, the same material (such as Al ₂O₃) may be suitable for the one or more low-index materials 42, depending on the refractive index of the material(s) selected for the one or more high-index materials 40.

In the embodiment of the windows 100a, 200a shown in fig. 4A-5B, one or more low refractive index layers 42 of the outer and inner layered films 36, 38 are composed of SiO ₂ layers, while one or more high refractive index layers 40 of the outer and inner layered films 36 are composed of AlN _x、AlO_xN_y、SiO_xN_y、Si₃N₄ or SiN _x layers. In some of these implementations, some of the high refractive index layers 40 are composed of SiO _xN_y, while some of the high refractive index layers 40 are composed of Si ₃N₄. Thus, various combinations of high refractive index layers 40 may be present in the outer and inner layered films 36, 38 of the windows 100a, 200 a.

In the embodiment of the window 100a, 200a shown in fig. 4A-5B, one or more of the high refractive index layers 40 of the inner laminated film 38 is comprised of an absorbing layer 60. In some embodiments of windows 100a, 200a, inner layered film 38 includes one or more absorbent layers 60. As also shown in fig. 4B and 5B, some of the high refractive index layers 40 of the inner layered film 38 of the windows 100a, 200a may be composed of an absorber layer 60, none of which is in direct contact with the inner major surface 34 of the substrate 30. In an embodiment, one or more low refractive index layers 42 of the outer layered film 36 are composed of SiO ₂ layers and one or more high refractive index layers 40 of the outer layered film are composed of AlN _x、AlO_xN_y、SiO_xN_y、Si₃N₄ or SiN _x layers, while one or more low refractive index layers 42 of the inner layered film 38 are composed of SiO ₂ layers and one or more high refractive index layers 40 of the inner layered film 38 are composed of amorphous silicon (a-Si) absorber layer 60 and Si ₃N₄ layers. Furthermore, according to the windows 100a, 200a shown in fig. 4A to 5B, the absorbing layer has a physical thickness ranging from 10nm to 400nm, 20nm to 350nm, 25nm to 300nm and all ranges and thickness values between the above ranges.

In some embodiments of the window 200a shown in fig. 5A and 5B, the inner layered film 38 and/or the outer layered film 36 may include one or more absorbent layers 60. As shown in fig. 5B, for example, the outer layered film 36 may be configured with one or more absorber layers 60, the absorber layers 60 being adjacent to either the high index layer 40 or the low index layer 42, none of which is in direct contact with the outer major surface 32 of the substrate 30. In other embodiments of window 200a, outer layered film 36 may be provided with one or more absorber layers 60 in place of one or more of high refractive index layer 40 and low refractive index layer 42.

In those implementations of the windows 100a, 200a that include one or more absorber layers 60, each of the absorber layers may be amorphous silicon (a-Si), germanium (Ge), or gallium arsenide (GaAs). In some implementations of the window 100a, 200a including one or more absorber layers 60, each of the absorber layers may include a refractive index of 3.0 or greater. Further, in some implementations of the window 100a, 200a including one or more absorbing layers 60, each of the absorbing layers may include an extinction coefficient of 0.1 or greater at one or more wavelengths in the ultraviolet and visible spectrum from 100nm to 700 nm.

In the embodiment of window 200a shown in fig. 5A-5B, the outer layered film 36 or the inner layered film 38 may include one or more transparent conductive oxide (TRANSPARENT CONDUCTIVE OXIDE, TCO) layers 70. For example, the transparent conductive oxide layer 70 in the outer layered film 36 may be positioned between the substrate 30 and the scratch resistant layer 52 (as described in detail in the present disclosure below). As another example, the transparent conductive oxide layer 70 in the inner layered film 38 may be positioned between the substrate 30 and one of the high refractive index layer 40 or the low refractive index layer 42 (see fig. 5B). In one implementation, as shown in fig. 5B, the inner layered film 38 is positioned in contact with the inner major surface 34 of the substrate 30 and between the low refractive index layer 42 and the substrate 30.

In an embodiment, the transparent conductive oxide layer 70 employed in window 200a is combined with the number, thickness, and materials of the outer and inner layered films 36, 38 for protecting the components located behind window 200a from microwave radiation. In some embodiments of window 200a, as shown in the exemplary form in fig. 5A and 5B, the transparent conductive oxide layer 70 in combination with the number, thickness, and material of the outer and inner layered films 36, 38 is configured such that window 200a exhibits an energy attenuation of at least 15dB for microwave radiation greater than 1 GHz. As used herein, the "energy attenuation" of microwave radiation is measured using a network analyzer. The window according to the present disclosure is placed between two faraday cages, with the microwave transmitter in one cage and the microwave receiver in the other cage, unless otherwise indicated. Measurement and energy attenuation (in "dB") calculations may then be performed in accordance with techniques in the field of the present disclosure (e.g., maniyara, R et al, in communication herewith, vol.7, art No.13771 (2016), "an anti-reflective transparent conductor having ultra-low optical loss (< 2%) and electrical resistance (< Ω sq ^-1), the entire contents of which are incorporated herein by reference).

In some embodiments of window 200a, as shown in the exemplary form in fig. 5A and 5B, transparent conductive oxide layer 70 in combination with the number, thickness, and material of outer and inner layered films 36 and 38 is configured such that window 200a exhibits at least 2dB, 4dB, 6dB, 8dB, 10dB, 12dB, 13dB, 14dB, or 15dB energy attenuation for microwave radiation from 1GHz to 50GHz, 1GHz to 40GHz, or 1GHz to 30 GHz. For example, the transparent conductive oxide layer 70 in combination with the number, thickness, and materials of the outer and inner layered films 36, 38 is configured such that the window 200a exhibits an energy attenuation of at least 2dB, 4dB, 6dB, 8dB, 10dB, 12dB, 13dB, 14dB, or 15dB for microwave radiation at 1.5GHz and/or 25 GHz.

In those embodiments of window 200a that include one or more transparent conductive oxide layers 70, the TCO layer 70 may be any transparent conductive oxide material as understood by those of skill in the art of this disclosure. Suitable materials for transparent conductive oxide layer 70 include SnO₂、In₂O₃、ZnO、CdO、ZnO-SnO₂、ZnO-In₂O₃、In₂Or-SnO₂、CdO-In₂O₃、MgIn₂O₄、GaInO₃、CdSb₂O₆、ZnO-In₂O₃-SnO₂、CdO-In₂O₃-SnO₂ and ZnO-CdO-In ₂O₃-SnO₂. In some implementations, any of the foregoing TCO materials suitable for the transparent conductive oxide layer 70 of the window 200a may be doped with F, al ₂O₃, sb, as, nb, ta, ge and other dopants as understood by those of skill in the art of this disclosure. In a preferred implementation, the transparent conductive oxide layer 70 is F-doped SnO ₂ (FTO), sn-doped In ₂O₃(ITO)、ZnO₂、Al₂O₃ -doped ZnO ₂ (AZO), and In ₂O₃ -doped ZnO (IZO). Furthermore, according to the window 200a shown in fig. 5A-5B, each of the transparent conductive oxide layers 70 has a physical thickness ranging from 50nm to 400nm, 75nm to 300nm, 100nm to 250nm, and all ranges and thickness values between the above ranges.

The number of alternating high index layers 40 and low index layers 42 in the outer or inner layered film 36, 38 is not particularly limited. In an embodiment, the number of alternating layers within each of the outer and inner layered films 36, 38 is 7 or more or 9 or more. In embodiments, the number of alternating layers within the outer layered film 36 and/or the inner layered film 38 is 9 or more, 17 or more, 19 or more, or 81 or more. In an embodiment, the number of alternating layers in the outer and inner layered films 36, 38 that collectively form the windows 100a, 200a, excluding the substrate 30, is 9 or more, 16 or more, 24 or more, 26 or more, or even 88 or more. In embodiments of windows 100a, 200a, the plurality of alternating high index layers 40 and low index layers 42 in outer layered film 36 is 5 to 15 layers. In an embodiment of the window 100a, 200a, the plurality of alternating high index layers 40 and low index layers 42 in the inner laminated film 38 is 5 to 15 layers. According to an embodiment, the plurality of alternating high refractive index layers 40 and low refractive index layers 42 in the outer and inner layered films 36, 38 are 5 to 15 layers, for example, the outer layered film 38 is 9 to 13 layers and the inner layered film 38 is 9 to 13 layers.

In general, the greater the number of layers within the outer and inner layered films 36, 38, the narrower the transmittance and reflectance properties of the windows 100a, 200a are tuned for one or more particular wavelengths or wavelength ranges. Further, each of the alternating high and low refractive index layers 40, 42 of the outer and inner layered films 36, 38 has a thickness.

In some embodiments of the windows 100a, 200a, as shown in fig. 4A-5B, the low refractive index layer 42 of the outer layered film 36 may be disposed in contact with the outer major surface 32 of the substrate 30. As shown in fig. 4A, 4B, 5A, and 5B, the reflected radiation 28 first encounters the terminal surface 44 of the outer layered film 36 when interacting with the windows 100a, 200a, and the terminal surface 44 may be open to the external environment 26. In an embodiment, one or more low refractive index layers 42 provide a termination surface 44 to more closely match the refractive index of air in the external environment 26, thereby reducing reflection of incident electromagnetic radiation (whether reflected radiation 28 or otherwise) from the termination surface 44. The one or more low refractive index layers 42 that provide the termination surface 44 are the layers of the outer layered film 36 furthest from the substrate 30. Similarly, in embodiments, when the one or more low refractive index layers 42 are SiO ₂, the SiO ₂ layer as the one or more low refractive index layers 42 is disposed directly on and in contact with the outer major surface 32 of the substrate 30, the outer major surface 32 of the substrate 30 typically comprising a large mole percent of SiO ₂. Without being bound by theory, it is believed that SiO ₂ versatility in both the substrate 30 and adjacent layers of the one or more low refractive index layers 42 allows for increased bond strength.

In some embodiments of the windows 100a, 200a, as shown in fig. 4A-5B, the low refractive index layer 42 of the inner layered film 38 may be disposed in contact with the inner major surface 34 of the substrate 30. The emitted radiation 22 first encounters the terminal surface 48 of the inner layered film 38 upon interaction with the windows 100a, 200 a. In an embodiment, one or more low refractive index layers 42 provide a termination surface 48 to more closely match the refractive index of air within housing 20, thereby reducing reflection of incident emitted radiation 22 from termination surface 48. The one or more low refractive index layers 42 that provide the termination surface 48 are the layers of the inner layered film 38 furthest from the substrate 30. Similarly, in an embodiment, when the one or more low refractive index layers 42 are SiO ₂, the SiO ₂ layer as the one or more low refractive index layers 42 is disposed directly on and in contact with the inner major surface 34 of the substrate 30.

The implementation of the windows 100a, 200a shown in fig. 4A-5B includes a scratch resistant layer 52 (which may be one of the high refractive index layers 40) in the outer layered film 36. The scratch resistant layer 52 may have a thickness of about 0.1 μm to 10 μm, 0.25 μm to 10 μm, 0.5 μm to 10 μm, 0.1 μm to 5 μm, 0.25 μm to 5 μm, 0.5 μm to 5 μm,1 μm to 10 μm, or 1 μm to 5 μm. For example, the scratch resistant layer 52 may have a physical thickness of 100nm、200nm、300nm、400nm、500nm、600nm、700nm、800nm、900nm、1000nm、1250nm、1500nm、2000nm、2500nm、3000nm、4000nm、5000nm、6000nm、7000nm、8000nm、9000nm、10000nm and all physical thicknesses between the above thicknesses.

Referring again to scratch resistant layer 52, a material having a relatively high refractive index may have a relatively high hardness at the same time, thereby providing scratch resistance and impact resistance. An example material that may be both high hardness and scratch resistant layer 52 (and one of high refractive index layers 40) is Si ₃N₄. Other example materials that have both high hardness and can be scratch resistant layer 52 are SiN _x、SiN_x:H_y and SiO _xN_y. The thickness of the scratch resistant layer 52, whether at the second layer of the outer layered film 36 or elsewhere, may be maximized to increase the scratch and/or mar resistance of the windows 100a, 200 a. The thickness and location of the scratch resistant layer 52 within the outer layered film 36 may be optimized to provide a desired level of hardness and scratch resistance to the outer layered film 36 and thus to the overall window 100a, 200 a.

Different applications of the window 100a, 200a may result in different desired thicknesses of the scratch resistant layer 52 that serve as a layer providing hardness and scratch resistance to the window. For example, protecting the windows 100a, 200a of the LIDAR system 12 on the vehicle 10 may require a different thickness of the scratch-resistant layer 52 than protecting the windows 100a, 100a of the LIDAR system 12 of the office building. In embodiments, the physical thickness of the scratch resistant layer 52 is 40% or greater, 45% or greater, 50% or greater, 55% or greater, 60% or greater, 65% or greater, or 70% or greater of the total thickness of the outer layered film 36. In general, the scratch resistant layer 52, which serves as a layer providing hardness and scratch resistance to the windows 100a, 200a, will be part of the outer layered film 36 facing the external environment 26, rather than the inner layered film 38 protected by the housing 20, but this is not always the case.

As will be described in further detail below, the number, thickness, and materials of the remaining layers of the outer and inner layered films 36, 38 may be configured to provide the desired optical properties (transmittance and reflectance at the desired wavelengths) to the windows 100a, 200a, almost independent of the thickness of the scratch resistant layer 52 selected for use as a layer providing hardness and scratch resistance to the windows. This insensitivity of the optical properties of the windows 100a, 200a as a whole to the thickness of the scratch-resistant layer 52 may be affected by using a material in the scratch-resistant layer that has a relatively low or negligible optical absorption of electromagnetic radiation of the target wavelength or wavelength range (i.e., 905nm and/or 1550 nm). For example, the scratch resistant layer 52 of Si ₃N₄ only absorbs a small amount of electromagnetic radiation in the wavelength range 700nm to 2000 nm. This general insensitivity of the thickness of the scratch resistant layer 52 in the outer layered film 36 to the optical properties of the windows 100a, 200a allows the physical thickness of the scratch resistant layer to be selected to provide specific hardness or scratch resistance requirements for the window. For example, the outer laminate film 36 of the windows 100a, 200a utilized at the roof 14 of the vehicle 10 may have different hardness and scratch resistance requirements than the inner laminate film 36 of the windows 100a and 200a utilized at the front 16 of the vehicle 10, thus requiring a different thickness of the scratch resistant layer 52. This can be accomplished without significantly changing the transmittance and reflectance properties of the outer layered film 36 and the windows 100a, 200a as a whole.

The hardness of the outer layered film 36, and thus the windows 100a, 200a having the scratch resistant layer 52, can be quantified. In some embodiments, the maximum hardness of the windows 100a, 200a measured at the outer layered film 36 with the scratch resistant layer 52, as measured by the Berkovich indenter hardness test, may be about 8GPa or greater, about 9GPa or greater, about 10GPa or greater, about 11GPa or greater, about 12GPa or greater, about 13GPa or greater, about 14GPa or greater, about 15GPa or greater, about 16GPa or greater, about 17GPa or greater, or about 18GPa or greater at one or more indentation depths of even 2000nm to 5000nm, as measured by the Berkovich indenter hardness test. As used herein, the "Berkovich indenter hardness test" includes measuring the hardness of a material on its surface by pressing it into the surface with a diamond Berkovich indenter. Berkovich indenter hardness testing involves pressing a diamond Berkovich indenter into the terminal surface 44 of the outer layered film 36 to form an indentation having a depth in the range of about 50nm to about 1000nm (or the entire thickness of the outer layered film 36, whichever is smaller), and measuring the maximum hardness from this indentation along the entire indentation depth range or a segment of this indentation depth range (e.g., in the range of about 100nm to about 600 nm), typically using an improved technique of Oliver, W.C.& Phar, G.M. using load and displacement sensing indentation experiments to determine hardness and modulus of elasticity (J. Mater. Res., vol.7, no.6,1992,1564 ～ 1583) and Oliver, W.C.Pharr, G.M. hardness and modulus of elasticity are measured by instrumental indentation). Advanced understanding and modification of the process described in methods (J. Mater. Res., vol.19, no.1,2004, 3-20). As used herein, hardness refers to the maximum hardness, not the average hardness. These hardness levels may improve the resistance of the window 100a, 200a to impact damage from sand, small stones, debris, and other objects encountered when the LIDAR system 12 is used for its intended purpose, such as with the vehicle 10. Thus, these hardness levels may reduce or prevent degradation of the optical scattering and performance of the LIDAR system 12 that may result from impact damage.

In an embodiment, one or more low refractive index layers 42 providing the termination surface 44 have a thickness of less than 20%, or even less than 10%, of the wavelength of electromagnetic radiation at 1550 nm. In an embodiment, the thickness of the layer providing the termination surface 44 is between 150nm and 310 nm. Minimizing the thickness of the layer providing the termination surface 44 enhances the scratch and/or mar resistance provided by the scratch resistant layer 52 provided directly beneath the layer providing the one or more low refractive index layers 42 of the termination surface 44. As previously described, in embodiments, the scratch resistant layer 52 that imparts rigidity to the windows 100a, 200a is a second layer of the outer layered film 36 from the external environment 26 adjacent to the one or more low refractive index layers 42 that provide the terminal surfaces 44 of the windows 100a and 200 a.

The outer laminate film 36 has a thickness 46 and the inner laminate film 38 has a thickness 50. Assuming the thickness 46 of the outer layered film 36 includes the scratch resistant layer 52, its thickness may be about 1 μm or greater while still providing the transmittance and reflectance properties described herein. In embodiments, the thickness 46 is in the range of 1 μm to just over 50 μm, including about 1 μm to about 10 μm and about 2500nm to about 6000nm. The lower limit of about 1 μm is about the minimum thickness 46 that still provides the window 100a, 200a with hardness and scratch resistance. The upper limit of thickness 46 is limited by the cost and time required to place the layers of outer laminate film 36 on substrate 30. Further, the upper limit of the thickness 46 is limited to prevent the outer laminate film 36 from warping the substrate 30, depending on the thickness of the substrate 30. The thickness 50 of the inner layered film 38 may be any thickness required to impart the desired transmittance and reflectance properties to the windows 100a, 200 a. In embodiments, the thickness 50 of the inner layered film 38 is in the range of about 800nm to about 7000nm, about 800nm to about 5000nm, or about 800nm to about 3500 nm. If the inner layered film 38 also includes a scratch resistant layer 52 to impart stiffness and impact resistance, the thickness 50 of the inner layered film 38 may be thicker, as described in connection with the layered film 36 above.

While addressing the problems discussed in the prior art by imparting hardness, impact resistance, and scratch resistance to the windows 100a, 200a through the scratch resistant layer 52, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured to also maximize the transmission of reflected radiation 28 through the windows 100a, 200a having wavelengths of 905nm and/or 1550nm through the windows 100a, 200 a. In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured to also maximize the transmission of electromagnetic radiation through the windows 100a, 200a having wavelengths in the range of 900nm to 1600 nm. In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured such that the windows 100a, 200a have an average transmittance of greater than 75%, greater than 80%, greater than 85%, greater than 90%, greater than 92%, greater than 94%, greater than 95%, greater than 98%, greater than 98.5%, greater than 99%, or even greater than 99.5% (within ±25 nm) for electromagnetic radiation of at least one wavelength from 900nm to 1600nm within the infrared spectrum at normal or near normal incidence (i.e., <15 °). In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured such that the windows 100a, 200a have an average transmittance of greater than 75%, greater than 80%, greater than 85%, greater than 90%, greater than 92%, greater than 94%, greater than 95%, greater than 98%, greater than 98.5%, greater than 99%, or even greater than 99.5% at normal or near normal incidence (i.e., <15 ° incidence) for electromagnetic radiation having any wavelength in the range of 1500nm to 1600 nm. In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured such that the windows 100a, 200a have an average transmittance of greater than 75%, greater than 80%, greater than 85%, greater than 90%, greater than 92%, greater than 94%, greater than 95%, greater than 98%, greater than 98.5%, greater than 99%, or even greater than 99.5% (within ±25 nm) for electromagnetic radiation having a wavelength of 905nm and/or 1550nm at normal or near normal incidence (i.e., <15 ° incidence). In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured such that the windows 100a, 200a have an average transmittance of greater than 75%, greater than 80%, or greater than 85% at normal or near normal incidence (i.e., <15 ° angle of incidence) for electromagnetic radiation having any wavelength in the range of 880nm to 1580nm or 850nm to 1800 nm. The term "transmittance" refers to the percentage of incident optical power transmitted through a material (e.g., window 100a, 200a, substrate 30, outer layered film 36, inner layered film 38, or portions thereof) in a given wavelength range.

According to some embodiments of the windows 100a, 200a, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured to also maximize S & P polarized transmission through the windows 100a and 200a of reflected radiation 28 having wavelengths of 905nm and/or 1550nm through the windows 100a and 200 a. In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured to also maximize S & P polarized transmission of electromagnetic radiation having wavelengths in the range of 900nm to 1600nm through the windows 100a, 200 a. In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured such that the windows 100a, 200a have an S & P polarized transmittance of greater than 65%, greater than 70%, greater than 75%, greater than 80%, greater than 85%, or greater than 90% (within ±25 nm) for electromagnetic radiation of at least one wavelength from 900nm to 1600nm in the infrared spectrum at an angle of incidence from perpendicular to less than 60 °. In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured such that the windows 100a, 200a have an S & P polarized transmittance of greater than 65%, greater than 70%, greater than 75%, greater than 80%, greater than 85%, or greater than 90% for electromagnetic radiation having any wavelength in the range of 1500nm to 1600nm at an angle of incidence from perpendicular less than 60 °. In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured such that the windows 100a, 200a have an S & P polarized transmission of greater than 65%, greater than 70%, greater than 75%, greater than 80%, greater than 85%, or greater than 90% (within ±25 nm) for electromagnetic radiation having wavelengths of 905nm and/or 1550nm at an angle of incidence from perpendicular less than 60 °.

In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured to also minimize the reflectivity of reflected radiation 28 having wavelengths of 905nm and/or 1550nm from the windows 100a, 200a through the windows 100a, 200 a. In an embodiment, the number, thickness, and material configuration of the layers of the outer and inner layered films 36, 38 are also configured to minimize the reflectivity of electromagnetic radiation from the windows 100a, 200a having wavelengths in the range of 1500nm to 1600 nm. In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured such that the windows 100a, 200a have an average reflectivity of less than 10%, less than 5%, less than 3%, less than 2%, less than 1%, less than 0.8%, less than 0.5%, or even less than 0.3% for electromagnetic radiation having 905nm and/or 1550nm at any angle of incidence in the range of 0 ° to 8 °,0 to 15 °,0 to 25 °, or even 0 ° to 50 °. In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured such that the windows 100a, 200a have an average reflectivity of less than 10%, less than 5%, less than 3%, less than 2%, less than 1%, less than 0.8%, less than 0.5%, or even less than 0.3% (within ±25 nm) for electromagnetic radiation of at least one wavelength in the range of 900nm to 1600nm at any incident angle in the range of 0 ° to 8 °,0 ° to 15 °,0 to 25 °, or even 0 ° to 50 °. In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured such that the windows 100a, 200a have an average reflectivity of less than 10%, or less than 5%, for electromagnetic radiation having a wavelength of 905nm and/or 1550nm at any angle of incidence in the range of 0 ° to 8 °,0 to 15 °, or even 0 to 25 °. The term "reflectivity" is similarly defined as the percentage of incident optical power within a given wavelength range that is reflected from a material (e.g., window 100a, 200a, substrate 30, outer layered film 36, or portions thereof).

In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are additionally configured to be specific to electromagnetic radiation having wavelengths in the ultraviolet range and the visible spectrum (such as wavelengths in or throughout the ranges of 100nm to 700nm, 300nm to 600nm, 420nm to 650nm, 300nm to 650nm, and 300nm to 700 mm): (a) minimizing the transmittance through the windows 100a, 200 a; (b) maximizing the reflectivity of the slave windows 100a, 200 a; and/or (c) absorbing electromagnetic radiation. In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are additionally configured to provide for electromagnetic radiation having a wavelength within a portion of the ultraviolet range, the visible spectrum, and the infrared range (such as a wavelength in the range of 300nm to 850nm, 300nm to 900nm, or 300nm to 1500 nm) that is shorter than 1500nm or shorter than 850 nm: (a) minimizing the transmittance through the windows 100a, 200 a; (b) Maximizing the reflectivity of the slave windows 100a, 200 a; and/or (c) absorbing electromagnetic radiation. in embodiments, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are additionally configured such that the windows 100a, 200a have less than 10%, less than 5%, less than 3%, less than 2%, less than 1%, less than 0.8% of the electromagnetic radiation having wavelengths in the ultraviolet and/or visible spectrum in the range of 100nm to 700nm, 300nm to 600nm, 300nm to 650nm, 420nm to 650nm, 300nm to 700nm, or 300nm to 950nm at normal or near normal incidence (i.e., <15 °) an average transmission of less than 0.5%, less than 0.2%, or even less than 0.15%. In an embodiment, the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are additionally configured such that the windows 100a, 200a have a wavelength of greater than 80% >, a wavelength of electromagnetic radiation having any wavelength in the ultraviolet range and visible spectrum (such as in the 300nm to 600nm, 300nm to 650nm, 420nm to 650nm, 300nm to 700nm, 300nm to 950nm, 400 nm to 700nm, 500nm to 700nm, or 550nm to 700 nm) at any incident angle in the range of 0 ° to 8 °,0 ° to 15 °, or 0 ° to 25 ° or greater than 90%, greater than 95%, or even greater than 97%. These embodiments prevent or reduce the transmittance of elevated temperature sunlight through the windows 100a, 200a to the housing 20 of the LIDAR system 12, which may improve the performance of the LIDAR 12. In addition, these embodiments prevent or reduce the transmissivity of electromagnetic radiation at wavelengths not necessary to operate the LIDAR system 12, such as wavelengths outside the 1450nm to 1550nm range (or 850nm to 950nm, and 1450nm and 1550 nm), which reduces noise that interferes with the electromagnetic radiation emitters and sensors 18, thereby improving the performance of the LIDAR system 12.

As described above, amorphous silicon (a-Si) is a material that is particularly suitable for use as one or more of the absorber layers 60, in some implementations, in place of the one or more high refractive index layers 40. In addition to having a relatively high refractive index (about 3.77 at 1550 nm), amorphous silicon (a-Si) has a relatively high optical absorption in the ultraviolet and visible range, but a tolerable optical absorption in the 900 to 1800nm range. The thickness and number of amorphous silicon (a-Si) absorber layer 60, as well as other layers of outer and inner layered films 36, 38, may thus provide a window 100a, 200a with a low percentage transmission for electromagnetic radiation in the ultraviolet and visible ranges (due in part to optical absorption of amorphous silicon in these wavelength ranges), but a high percentage transmission in the desired portion of the infrared range. Embodiments that do not utilize amorphous silicon (a-Si), or some other material having similar optical absorption properties, may primarily utilize optical interference to provide windows 100a, 200a with desired optical properties (e.g., low transmittance and/or high reflectance in the range of 300nm to 700nm, but high transmittance and low reflectance in the range of 1550nm or some range including 1550 nm). The following examples and other embodiments do utilize amorphous silicon (a-Si) or some other material having similar optical absorption properties of the absorption layer 60, utilize optical absorption and optical interference to provide the desired optical properties for the windows 100a, 200a. Thus, embodiments of the absorber layer 60 that utilize amorphous silicon (a-Si) or some other material having similar optical absorption properties may provide the windows 100a, 200a with desired optical properties with fewer layers in the outer and inner layered films 36, 38 than embodiments that do not utilize amorphous silicon (a-Si) or some other material having similar optical absorption properties. In an embodiment, the inner layered film 38 includes one or more amorphous silicon (a-Si) absorber layers 60 as one of the one or more high refractive index layers 40, while the outer layered film 36 does not include an absorber layer 60.

More generally, the number, thickness, and materials of the outer and inner layered films 36, 38 may be configured to tune the reflected color of the windows 100a, 200a at an incident angle of less than 90 °, as shown in the exemplary forms in fig. 4A-5B. In some embodiments of the windows 100a, 200a, the number, thickness, and materials of the outer and inner layered films 36, 38 are configured such that the windows exhibit tunable reflective colors at angles of incidence less than 90 °, or less than 15 °, as given by CIE color coordinates, a is from +50 to 0, b is from +40 to 0, when viewed from the outer layered film 36. In some embodiments of the windows 100a, 200a, the number, thickness, and materials of the outer and inner layered films 36, 38 are configured such that the windows exhibit tunable reflective colors at angles of incidence less than 90 °, or less than 15 °, as given by CIE color coordinates, a from +10 to-10, b from +30 to-10, when viewed from the inner layered film 38.

Further, the layers of the outer and inner layered films 36, 38 (e.g., the layers of the high and low refractive index layers 40, 42) may be formed by any known method in the art, including discrete sputter deposition or a continuous deposition process. In one or more embodiments, the layers of layered films 36, 38 may be formed using only a continuous deposition process, or alternatively, using only a discrete deposition process.

Examples

The following embodiments are all modeled embodiments using computer-aided modeling to demonstrate how the number, thickness, and materials of the layers of the outer and inner layered films 36, 38 are configured such that the windows 100a, 200a have a desired average transmittance and average reflectance as a function of the wavelength and angle of incidence of the incident electromagnetic radiation, as well as other properties and attributes outlined in the present disclosure.

Refractive index (n) and optical absorption (k) of each of alternating high and low refractive index layers 40, 42 of outer and inner layered films 36, 38 and substrate 30 as a function of wavelength were measured using ellipsometry. SiN _x、SiO₂, amorphous silicon (a-Si), in ₂O₃ doped ZnO ₂ (IZO) and aluminosilicate glass substrates for example 1 and example 2 [ (]The refractive indices of glass 3) are provided in tables 1 and 2, respectively, below. These materials are used as the high refractive index layer 40, the low refractive index layer 42, the absorption layer 60, the transparent conductive oxide layer 70, and the substrate 30 in the following embodiments.

Example 1

In this embodiment, a double-sided overlay window configuration exemplary window 200a (see fig. 5A and 5B, and corresponding description above) is modeled and detailed in table 1 below. This embodiment window design achieves > 80% transmission in the 1550nm + -25 nm infrared wavelength range for normal and up to 60 deg. incidence angles, < 0.5% reflection in the 1550nm + -25 nm infrared wavelength range for normal incidence angles, < <10% transmission in the visible wavelength range for normal incidence angles, a Berkovich nanoindentation hardness of >11GPa at an indentation depth in the range of about 50nm to about 1000nm in an outer layered film (e.g., outer layered film 36), and an attenuation of >15dB for microwave radiation.

Table 1 example 1

Referring to fig. 6A, a graph of modeled dual-surface transmittance versus wavelength for the exemplary window of example 1 is provided, as measured from 1500nm to 1600nm at normal incidence from the exterior and interior surfaces of the window. As shown in fig. 6A, the window of example 1 exhibited a transmittance of >90% over a wavelength range of 1550nm±25 nm.

Referring to fig. 6B, a plot of modeled dual-surface S & P polarized transmittance versus wavelength for the exemplary window of example 1 is provided, as measured from 1500nm to 1600nm at 60 ° incidence from the exterior and interior surfaces of the window. As shown in fig. 6B, the window of example 1 exhibited S & P polarized transmittance > 85% over a wavelength range of 1550nm±25 nm.

Referring now to fig. 6C, a plot of modeled dual-surface reflectivity versus wavelength for the exemplary window of example 1 is provided, as measured at normal incidence from 1500nm to 1600nm from the exterior and interior surfaces of the window. As shown in fig. 6C, the window of example 1 exhibited a reflectivity of <0.3% over a wavelength range of 1550nm±25 nm.

Referring now to fig. 6D, a graph of modeled dual-surface transmittance versus wavelength for the exemplary window of example 1 is provided, as measured from 400nm to 700nm at normal incidence from the exterior and interior surfaces of the window. As shown in fig. 6D, the window of example 1 exhibited a transmission of < <10% in the visible wavelength range.

Referring now to fig. 6E, a graph of modeled reflected colors for the exemplary window of example 1 is provided, as measured from the outer and inner surfaces of the window from perpendicular to 90 ° incidence. As shown, the window according to example 1 exhibits an a-value ranging from 0 to about 46 and a b-value ranging from about 1 to about 36 when viewed from the outer layered film 36. The window according to example 1 exhibits an a-value ranging from about-7 to about 7 and a b-value ranging from about-4 to about 21 when viewed from the inner layered film 38. As shown in fig. 6E, the configuration of the layers of the window may be adjusted to tune the reflected color exhibited by the window.

Referring now to fig. 6F, a graph of measured Berkovich nanoindentation hardness versus displacement into the outer surface of an exemplary window made according to example 1 is provided. As can be seen from fig. 6F, the window exhibits a nanoindentation hardness of >11GPa beyond a displacement depth of 500 nm. Furthermore, the window exhibits a maximum nanoindentation hardness of greater than 12 GPa. The nanoindentation hardness is greater than 10GPa over a depth ranging from 200nm to 2100 nm.

Referring now to fig. 6G, a graph of microwave radiation attenuation measured via exemplary windows of the present disclosure consistent with example 1 versus the thickness of the indium zinc oxide layer (i.e., the transparent conductive oxide layer 70 thereof) within those windows is provided. As can be seen from fig. 6G, the window of this embodiment exhibits >15dB of attenuation at 25GHz when a TCO layer of 145nm thick IZO material is used. In addition, the window of this embodiment exhibits >4dB attenuation at 1.5GHz when a TCO layer of 145nm thick IZO material is employed. It can also be seen from fig. 6G that a lower but perceptible level of attenuation was observed for the window employing a 75nm thick TCO layer of IZO material.

Referring again to fig. 6A-6G, a window with a thicker TCO layer (e.g., made of IZO material) will have higher attenuation at all wavelengths (i.e., over all visible, infrared, and microwave wavelength bands), while a window with a thinner TCO layer will have a relatively lower attenuation level. However, the transmittance ratio in each of the visible, infrared and microwave wavelength bands is primarily affected by the material properties of the TCO layer, resulting in a relatively higher transmittance in the visible and infrared wavelength bands compared to the microwave wavelength band. In other words, the spectral attenuation associated with the TCO layer increases with increasing wavelength. Thus, the window of the present disclosure has less absorption in the visible light segment than in the infrared segment (i.e., 1550 nm). At wavelengths longer than 1550nm, the attenuation associated with the TCO layer increases, which is one of the main driving forces of the microwave shielding borne by the window of the present disclosure.

Example 2

In this embodiment, an exemplary window 100a (see fig. 4A and 4B, and corresponding description above) of a two-sided window configuration is modeled and detailed in table 2 below. This embodiment window design achieves a Berkovich nanoindentation hardness of >99% transmission and <0.1% reflection in the infrared wavelength range of 1550nm + -25 nm for normal incidence, a transmission of < <10% in the visible wavelength range for normal incidence, and >14GPa at the outer surface.

Table 2 example 2

Referring now to fig. 7A, a graph of modeled dual-surface transmittance versus wavelength for an exemplary window of example 2 is provided, as measured at normal incidence from 1500nm to 1600nm from the exterior and interior surfaces of the window. As shown in fig. 7A, the window of example 2 exhibited a transmittance of >99.8% over a wavelength range of 1550nm±25 nm.

Referring now to fig. 7B, a plot of modeled dual-surface S & P polarized transmittance versus wavelength for the exemplary window of example 2 is provided, as measured from 1500nm to 1600nm at 60 ° incidence from the exterior and interior surfaces of the window. As shown in fig. 7B, the window of example 2 exhibited S & P polarized transmittance of >91% over a wavelength range of 1550nm±25 nm.

Referring now to fig. 7C, a plot of modeled dual-surface reflectivity versus wavelength for the exemplary window of example 2 is provided, as measured at normal incidence from 1500nm to 1600nm from the exterior and interior surfaces of the window. As shown in fig. 7C, the window of example 2 exhibited a reflectivity of <0.15% over a wavelength range of 1550nm±25 nm.

Referring now to fig. 7D, a graph of modeled dual-surface transmittance versus wavelength for the exemplary window of example 2 is provided, as measured from 400nm to 700nm at normal incidence from the exterior and interior surfaces of the window. As shown in fig. 7D, the window of example 2 exhibited a transmission of < <10% (more specifically, less than 3.5%) in the visible wavelength range.

Example 3

In this embodiment, an exemplary window 200a (see fig. 5A and 5B, and corresponding description above) of a double-sided overlay window configuration is modeled and detailed in table 3. This embodiment window design achieves >90% transmission in the infrared wavelength range of 1550nm + -25 nm for normal and up to 60 deg. incidence angles, <0.5% reflection in the infrared wavelength range of 1550nm + -25 nm for 15 deg. incidence angles, <12% transmission in the visible wavelength range for 15 deg. incidence angles, berkovich nm indentation hardness of >11GPa at an indentation depth in the range of about 50nm to about 1000nm in an outer layered film (e.g., outer layered film 36), and attenuation of >15dB for microwave radiation.

Example 3 included a transparent conductive oxide layer 70 in the inner layered film 38. As shown in table 3, unlike embodiment 1, the transparent conductive oxide layer 70 does not directly contact the substrate 30. Instead, one of the one or more low refractive index layers 42 is positioned between the substrate 30 and the transparent conductive oxide layer 70. It is believed that the incorporation of such a low refractive index layer near the substrate 30 can improve the adhesion of the transparent conductive oxide layer 70 and help to improve durability. Another difference from embodiment 1 is that the outer layered film 36 does not include any absorbent layer 60. The outer layered film 36 comprises alternating layers of SiO ₂ and SiN, with the SiO ₂ layers forming the outermost and innermost layers, respectively, of the outer layered film 36. It is believed that the absence of any absorbent layer in the outer layered film 36 increases the stiffness (and thus scratch resistance and durability) and reduces the risk of delamination compared to the structure in example 1. The last 9 layers of the inner layered film 38 in example 3 are alternating low refractive index layers 42 and absorber layers 60. As a result, the only high refractive index layer 40 in the inner layered film 38 is between the transparent conductive oxide layer 70 and one of the absorber layers 60 that is closest to the substrate 30. Such multiple absorbing layers contribute to absorptivity in the visible spectrum and desired appearance.

The transparent conductive oxide layer 70 included in the inner layered film 38 in example 3 was 95nm based on a target sheet resistance of 70 ohm/sq. This is less than 140nm thick, which is the target for the same sheet resistance used in example 1. In an embodiment, the transparent conductive oxide layer 70 incorporated into one of the inner and outer layered films 38, 36 includes a sheet resistance greater than or equal to 50 ohms/sq and less than or equal to 100 ohms/sq (e.g., greater than or equal to 60 ohms/sq and less than or equal to 90 ohms/sq) to provide a suitable amount of energy attenuation.

Example 3 is further different from example 1 in that example 3 contains silicon having an extinction coefficient smaller than that used in example 1. Example 1 utilized more conventional silicon having an extinction coefficient greater than 0.05 at 1550 nm. In contrast, example 3 utilizes silicon having an extinction coefficient of less than 0.01 (e.g., less than or equal to 0.003) in the inner layered film 38. Example 3 also included a scratch resistant layer 52 in the outer layered film 36 that was 2000nm thick, having a higher refractive index (greater than 2.0 at 1550 nm) than that used in example 1. This high refractive index SiN layer is expected to have a higher hardness. As a result of incorporating low extinction coefficient Si and thinner transparent conductive oxide layer 70, example 3 was found to exhibit improved transmission performance compared to example 1 (example 3 exhibited about 96.3% transmission for light at 15 ° incidence).

TABLE 3 example 3

Referring to fig. 8A, a graph of modeled dual-surface transmittance versus wavelength for the exemplary window of example 3 is provided, as measured from 1500nm to 1600nm at 15 ° angles of incidence from the outer and inner surfaces (average polarization) of the window. As shown in fig. 8A, the window of example 3 exhibited a transmittance of >95% (even > 96%) over a wavelength range of 1550nm±25nm, which was improved as compared with example 1.

Referring to fig. 8B, a plot of modeled dual-surface S & P polarized transmittance versus wavelength for the exemplary window of example 3 is provided, as measured from 1500nm to 1600nm at 60 ° angles of incidence from the outer and inner surfaces of the window. As shown in fig. 8B, the window of example 3 exhibited >91% S & P polarized transmittance over the wavelength range of 1550nm±25nm, which was improved as compared to example 1.

Referring now to fig. 8C, a plot of modeled dual-surface reflectivity versus wavelength for the exemplary window of example 3 is provided, as measured from 1500nm to 1600nm at 15 ° angles of incidence from the outer and inner surfaces of the window. As shown in fig. 8C, the window of example 3 exhibited a reflectivity of <0.3% over a wavelength range of 1550nm±25nm, regardless of polarization.

Referring now to fig. 8D, a graph of modeled dual-surface transmittance versus wavelength for the exemplary window of example 3 is provided, as measured from 400nm to 700nm at 15 ° angles of incidence from the outer and inner surfaces of the window. As shown in fig. 8D, the window of example 1 exhibited a transmission of <12% over the visible wavelength range. In particular, at wavelengths less than 625nm, the window exhibits a transmittance of less than 1%. The average transmittance is less than 10% over a wavelength range from 400nm to 700nm at an angle of incidence of 15 °.

Referring now to fig. 8E, a graph of modeled reflected colors for the exemplary window of example 3 is provided, as measured from the exterior and interior surfaces of the window perpendicular to 90 ° incidence. As shown, the window according to example 3 exhibits an a-value ranging from about-9 to about 2 and a b-value ranging from about-8 to about 12 when viewed from the outer layered film 36. The window according to example 3 exhibits an a-value ranging from about-3.8 to about 6.8 and a b-value ranging from about-5 to about 23 when viewed from the inner layered film 38. As can be seen from fig. 8E, the configuration of the layers of the window can be adjusted to tune the reflected color exhibited by the window.

According to aspect 1 of the present disclosure, there is provided a window for a sensing system, the window comprising: a substrate comprising an outer major surface and an inner major surface, wherein the outer major surface and the inner major surface are opposite to each other; an outer layered film disposed on an outer major surface of the substrate; and an inner layered film disposed on the inner major surface of the substrate. The outer layered film includes a plurality of alternating high refractive index layers and low refractive index layers. The inner layered film includes a plurality of alternating high refractive index layers and low refractive index layers. Each of the high refractive index layers has a refractive index greater than that of each of the low refractive index layers. The outer layered film includes a scratch resistant layer having a thickness of about 0.5 μm to about 10 μm. The outer layered film exhibits a hardness of at least 11GPa as measured with a Berkovich indenter hardness test from the outermost surface of the outer layered film to a depth of 1 μm. Furthermore, the number, thickness and materials of the plurality of alternating high refractive index and low refractive index layers of the outer and inner layered films are configured such that the window exhibits an average transmittance of greater than 85% (within ±25 nm) of at least one wavelength in the infrared spectrum from 900nm to 1600nm at an angle of incidence <15 ° and an average transmittance of less than 5% in the visible spectrum from 420nm to 650nm at an angle of incidence <15 °.

In the case where aspect 1 is provided, according to aspect 2 of the present disclosure, the low refractive index layers in the outer and inner layered films are in contact with the outer and inner main surfaces of the substrate, respectively.

Where aspect 1 or aspect 2 is provided, according to aspect 3 of the present disclosure, wherein each of the high refractive index layers includes silicon-containing nitride, aluminum-containing nitride, or aluminum-containing oxynitride.

In the case where any one of aspects 1 to 3 is provided, according to aspect 4 of the present disclosure, each of the low refractive index layers includes a silicon-containing oxide.

In the case where any one of aspects 1 to 4 is provided, according to aspect 5 of the present disclosure, wherein the plurality of alternating high refractive index layers and low refractive index layers in the outer layered film is five (5) to fifteen (15) layers.

In the case where any one of aspects 1 to 5 is provided, according to aspect 6 of the present disclosure, the plurality of alternating high refractive index layers and low refractive index layers in the inner layered film is five (5) to fifteen (15) layers.

Providing any of aspects 1 to 6, according to aspect 7 of the present disclosure, the number, thickness, and materials of the plurality of alternating high and low refractive index layers of the outer and inner layered films are configured such that the window exhibits a transmittance of greater than 99% for infrared wavelengths of 1550nm±25nm at normal incidence.

Providing any one of aspects 1 to 7, according to aspect 8 of the present disclosure, wherein the scratch resistant layer has a thickness of 1 μm to 10 μm, and the outer layered film exhibits a hardness of at least 14GPa as measured from the outermost surface of the outer layered film to a depth of 1 μm with a Berkovich indenter hardness test.

According to aspect 9 of the present disclosure, there is provided a window for a sensing system, the window comprising: a substrate comprising an outer major surface and an inner major surface, wherein the outer major surface and the inner major surface are opposite to each other; an outer layered film disposed on an outer major surface of the substrate; and an inner layered film disposed on the inner major surface of the substrate. The outer layered film includes a plurality of alternating high refractive index layers and low refractive index layers. The inner layered film includes a plurality of alternating high refractive index layers and low refractive index layers. Each of the high refractive index layers has a refractive index greater than that of each of the low refractive index layers. The outer layered film includes a scratch resistant layer having a thickness of about 0.5 μm to about 10 μm. Further, the inner layered film includes one or more absorbing layers, wherein each of the absorbing layers includes a refractive index of 3.0 or more and an extinction coefficient of 0.1 or more at one or more wavelengths in the ultraviolet and visible spectrum from 100nm to 700 nm. The outer layered film exhibits a hardness of at least 11GPa as measured with a Berkovich indenter hardness test from the outermost surface of the outer layered film to a depth of 1 μm. Furthermore, the number, thickness and materials of the plurality of alternating high refractive index and low refractive index layers of the outer and inner layered films are configured such that the window exhibits an average transmittance of greater than 85% (within ±25 nm) of at least one wavelength in the infrared spectrum from 900nm to 1600nm at an angle of incidence <15 ° and an average transmittance of less than 5% in the visible spectrum from 420nm to 650nm at an angle of incidence <15 °.

Where aspect 9 is provided, in accordance with aspect 10 of the present disclosure, wherein the one or more absorber layers are selected from the group consisting of amorphous silicon (a-Si), germanium (Ge), and gallium arsenide (GaAs), and further wherein none of the one or more absorber layers is in direct contact with the inner major surface of the substrate.

Where aspects 9 or 10 are provided, according to aspect 11 of the present disclosure, one or more of the high refractive index layers of the inner layered film are one or more absorption layers.

In the case where any one of aspects 9 to 11 is provided, according to aspect 12 of the present disclosure, wherein the one or more absorption layers are amorphous silicon (a-Si).

Providing any of aspects 9 to 12, according to aspect 13 of the present disclosure, wherein the number, thickness, and materials of the plurality of alternating high refractive index layers and low refractive index layers of the outer and inner layered films are configured such that the window exhibits a transmittance of less than 10% in the visible spectrum from 420nm to 700nm at normal incidence.

In the case where any one of aspects 9 to 13 is provided, according to aspect 14 of the present disclosure, wherein the plurality of alternating high refractive index layers and low refractive index layers in the outer layered film is five (5) to fifteen (15) layers.

In the case where any one of aspects 9 to 14 is provided, according to aspect 15 of the present disclosure, wherein the plurality of alternating high refractive index layers and low refractive index layers in the inner layered film is five (5) to fifteen (15) layers.

Providing any of aspects 9 to 15, according to aspect 16 of the present disclosure, wherein the scratch resistant layer has a thickness of 1 μιη to 10 μιη and the outer layered film exhibits a hardness of at least 14GPa as measured with a Berkovich indenter hardness test from the outermost surface of the outer layered film to a depth of 1 μιη.

According to aspect 17 of the present disclosure, there is provided a window for a sensing system, the window comprising: a substrate comprising an outer major surface and an inner major surface, wherein the outer major surface and the inner major surface are opposite to each other; an outer layered film disposed on an outer major surface of the substrate; and an inner layered film disposed on the inner major surface of the substrate. The outer layered film includes a plurality of alternating high refractive index layers and low refractive index layers. The inner layered film includes a plurality of alternating high refractive index layers and low refractive index layers. Each of the high refractive index layers has a refractive index greater than that of each of the low refractive index layers. The outer layered film includes a scratch resistant layer having a thickness of about 0.5 μm to about 10 μm. In addition, the inner layered film or the outer layered film includes a transparent conductive oxide layer. The outer layered film exhibits a hardness of at least 11GPa as measured with a Berkovich indenter hardness test from the outermost surface of the outer layered film to a depth of 1 μm. Furthermore, the number, thickness and materials of the plurality of alternating high refractive index and low refractive index layers of the outer and inner layered films are configured such that the window exhibits an average transmittance of greater than 85% (within ±25 nm) of at least one wavelength in the infrared spectrum from 900nm to 1600nm at an angle of incidence <15 ° and an average transmittance of less than 5% in the visible spectrum from 420nm to 650nm at an angle of incidence <15 °.

Where aspect 17 is provided, in accordance with aspect 18 of the present disclosure, wherein the transparent conductive oxide layer is positioned between the substrate and the scratch resistant layer in the outer layered film.

Where aspect 17 is provided, in accordance with aspect 19 of the present disclosure, wherein the transparent conductive oxide layer is positioned in the inner layered film between the substrate and one of the high refractive index layer or the low refractive index layer.

Providing any of aspects 17 to 19, according to aspect 20 of the present disclosure, wherein the number, thickness, and materials of the plurality of alternating high refractive index and low refractive index layers of the outer and inner layered films are further configured such that the window exhibits an energy attenuation of at least 15dB for microwave radiation greater than 1 GHz.

In the case where any one of aspects 17 to 20 is provided, according to aspect 21 of the present disclosure, wherein the low refractive index layer in the outer layered film is in contact with the outer main surface of the substrate.

Any one of aspects 17 to 21 is provided in accordance with aspect 22 of the present disclosure, wherein each of the high refractive index layers comprises a silicon-containing nitride, an aluminum-containing nitride, or an aluminum-containing oxynitride.

Where any one of aspects 17 to 22 is provided, in accordance with aspect 23 of the present disclosure, each of the low refractive index layers comprises a silicon-containing oxide.

Where any one of aspects 17 to 23 is provided, according to aspect 24 of the present disclosure, wherein the plurality of alternating high refractive index layers and low refractive index layers of the outer and inner layered films are five (5) to fifteen (15) layers.

Providing any of aspects 17 to 24, according to aspect 25 of the present disclosure, wherein the scratch resistant layer has a thickness of 1 μιη to 10 μιη and the outer layered film exhibits a hardness of at least 14GPa as measured with a Berkovich indenter hardness test from the outermost surface of the outer layered film to a depth of 1 μιη.

Providing any of aspects 17 to 25, according to aspect 26 of the present disclosure, wherein at least one of the inner and outer layered films comprises one or more absorbing layers, wherein each absorbing layer has a refractive index of 3.0 or greater and an extinction coefficient of 0.1 or greater at one or more wavelengths in the ultraviolet and visible spectrum from 100nm to 700 nm.

Where aspect 26 is provided, in accordance with aspect 27 of the present disclosure, the one or more absorber layers are selected from the group consisting of amorphous silicon (a-Si), germanium (Ge), and gallium arsenide (GaAs).

Where aspects 26 or 27 are provided, according to aspect 28, wherein one or more of the high refractive index layers of the inner layered film are one or more absorbing layers.

It will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the spirit or scope of the claims.

Claims (28)

1. A window for a sensing system, the window comprising:

A substrate comprising an outer major surface and an inner major surface, wherein the outer major surface and the inner major surface are opposite to each other;

An outer layered film disposed on the outer major surface of the substrate; and

An inner layered film disposed on the inner major surface of the substrate,

Wherein the outer layered film comprises a plurality of alternating high refractive index layers and low refractive index layers,

Wherein the inner layered film comprises a plurality of alternating high refractive index layers and low refractive index layers,

Wherein each of the high refractive index layers has a refractive index greater than that of each of the low refractive index layers,

Wherein the outer layered film comprises a scratch resistant layer having a thickness of about 0.5 μm to about 10 μm,

Wherein the outer layered film exhibits a hardness of at least 11GPa as measured with a Berkovich indenter hardness test from the outermost surface of the outer layered film to a depth of 1 μm, and

Further wherein the number, thickness, and materials of the plurality of alternating high and low refractive index layers of the outer and inner layered films are configured such that the window exhibits an average transmittance of greater than 85% (within ±25 nm) of at least one wavelength in the infrared spectrum from 900nm to 1600nm at an incident angle <15 ° and an average transmittance of less than 5% in the visible spectrum from 420nm to 650nm at an incident angle <15 °.

2. The window of claim 1, wherein the low refractive index layers in the outer and inner layered films are in contact with the outer and inner major surfaces of the substrate, respectively.

3. The window of claim 1 or 2, wherein each of the high refractive index layers comprises a silicon-containing nitride, an aluminum-containing nitride, or an aluminum-containing oxynitride.

4. The window of any of claims 1-3, wherein each of the low refractive index layers comprises a silicon-containing oxide.

5. The window of any of claims 1-4, wherein the plurality of alternating high refractive index and low refractive index layers in the outer layered film is five (5) to fifteen (15) layers.

6. The window of any of claims 1-5, wherein the plurality of alternating high refractive index and low refractive index layers in the inner layered film is five (5) to fifteen (15) layers.

7. The window of any of claims 1-6, wherein the number, thickness, and material of the alternating high and low refractive index layers of the outer and inner layered films are configured such that the window exhibits a transmittance of greater than 99% at normal incidence for infrared wavelengths of 1550nm ± 25 nm.

8. The window of any of claims 1-7, wherein the scratch resistant layer has a thickness of 1 μιη to 10 μιη and the outer layered film exhibits a hardness of at least 14GPa as measured from an outermost surface of the outer film to a depth of 1 μιη with a Berkovich indenter hardness test.

9. A window for a sensing system, the window comprising:

A substrate comprising an outer major surface and an inner major surface, wherein the outer major surface and the inner major surface are opposite to each other;

An outer layered film disposed on the outer major surface of the substrate; and

An inner layered film disposed on the inner major surface of the substrate,

Wherein the outer layered film comprises a plurality of alternating high refractive index layers and low refractive index layers,

Wherein the inner layered film comprises a plurality of alternating high refractive index layers and low refractive index layers,

Wherein each of the high refractive index layers has a refractive index greater than that of each of the low refractive index layers,

Wherein the outer layered film comprises a scratch resistant layer having a thickness of about 0.5 μm to about 10 μm,

Wherein the inner layered film comprises one or more absorbing layers, wherein each absorbing layer comprises a refractive index of 3.0 or greater and an extinction coefficient of 0.1 or greater at one or more wavelengths in the ultraviolet and visible spectrum from 100nm to 700nm,

Wherein the outer layered film exhibits a hardness of at least 11GPa as measured with a Berkovich indenter hardness test from the outermost surface of the outer film to a depth of 1 μm, and

Further wherein the number, thickness, and materials of the plurality of alternating high and low refractive index layers of the outer and inner layered films are configured such that the window exhibits an average transmittance of greater than 85% (within ±25 nm) of at least one wavelength in the infrared spectrum from 900nm to 1600nm at an incident angle <15 ° and an average transmittance of less than 5% in the visible spectrum from 420nm to 650nm at an incident angle <15 °.

10. The window of claim 9, wherein the one or more absorber layers are selected from the group consisting of amorphous silicon (a-Si), germanium (Ge), and gallium arsenide (GaAs), and further wherein none of the one or more absorber layers is in direct contact with the inner major surface of the substrate.

11. The window of claim 9 or 10, wherein the one or more high refractive index layers of the inner layered film are the one or more absorbing layers.

12. The window of any of claims 9-11, wherein the one or more absorber layers are amorphous silicon (a-Si).

13. The window of any of claims 9-12, wherein the number, thickness, and material of the plurality of alternating high and low refractive index layers of the outer and inner layered films are configured such that the window exhibits a transmittance of less than 10% in the visible spectrum from 420nm to 700nm at normal incidence.

14. The window of any of claims 9-13, wherein the plurality of alternating high refractive index and low refractive index layers in the outer layered film is five (5) to fifteen (15) layers.

15. The window of any of claims 9-14, wherein the plurality of alternating high refractive index and low refractive index layers in the inner layered film is five (5) to fifteen (15) layers.

16. The window of any of claims 9-15, wherein the scratch resistant layer has a thickness of 1 μιη to 10 μιη and the outer layered film exhibits a hardness of at least 14GPa as measured from the outermost surface of the outer film to a depth of 1 μιη with a Berkovich indenter hardness test.

17. A window for a sensing system, the window comprising:

A substrate comprising an outer major surface and an inner major surface, wherein the outer major surface and the inner major surface are opposite to each other;

An outer layered film disposed on the outer major surface of the substrate; and

An inner layered film disposed on the inner major surface of the substrate,

Wherein the outer layered film comprises a plurality of alternating high refractive index layers and low refractive index layers,

Wherein the inner layered film comprises a plurality of alternating high refractive index layers and low refractive index layers,

Wherein each of the high refractive index layers has a refractive index greater than that of each of the low refractive index layers,

Wherein the outer layered film comprises a scratch resistant layer having a thickness of about 0.5 μm to about 10 μm, wherein the inner layered film or the outer layered film comprises a transparent conductive oxide layer,

Wherein the outer layered film exhibits a hardness of at least 11GPa as measured with a Berkovich indenter hardness test from the outermost surface of the outer film to a depth of 1 μm, and

Further wherein the number, thickness, and materials of the plurality of alternating high and low refractive index layers of the outer and inner layered films are configured such that the window exhibits an average transmittance of greater than 85% (within ±25 nm) of at least one wavelength in the infrared spectrum from 900nm to 1600nm at an incident angle <15 ° and an average transmittance of less than 5% in the visible spectrum from 420nm to 650nm at an incident angle <15 °.

18. The window of claim 17, wherein the transparent conductive oxide layer is positioned between the substrate and the scratch resistant layer in the outer layered film.

19. The window of claim 17, wherein the transparent conductive oxide layer is positioned in the inner layered film between the substrate and one of the high refractive index layer or low refractive index layer.

20. The window of any of claims 17-19, wherein the number, thickness, and material of the plurality of alternating high and low refractive index layers of the outer and inner layered films are further configured such that the window exhibits an energy attenuation of at least 15dB for microwave radiation greater than 1 GHz.

21. The window of any of claims 17-20, wherein a low refractive index layer in the outer layered film is in contact with the outer major surface of the substrate.

22. The window of any of claims 17-21, wherein each of the high refractive index layers comprises a silicon-containing nitride, an aluminum-containing nitride, or an aluminum-containing oxynitride.

23. The window of any of claims 17-22, wherein each of the low refractive index layers comprises a silicon-containing oxide.

24. The window of any of claims 17-23, wherein the plurality of alternating high and low refractive index layers in the outer and inner layered films is five (5) to fifteen (15) layers.

25. The window of any of claims 17-24, wherein the scratch resistant layer has a thickness of 1 μιη to 10 μιη and the outer layered film exhibits a hardness of at least 14GPa as measured from the outermost surface of the outer film to a depth of 1 μιη with a Berkovich indenter hardness test.

26. The window of any of claims 17-25, wherein at least one of the inner and outer layered films comprises one or more absorbing layers, wherein each absorbing layer comprises a refractive index of 3.0 or greater and an extinction coefficient of 0.1 or greater at one or more wavelengths in the ultraviolet and visible spectrum from 100nm to 700 nm.

27. The window of claim 26, wherein the one or more absorber layers are selected from the group consisting of amorphous silicon (a-Si), germanium (Ge), and gallium arsenide (GaAs).

28. The window of claim 26 or claim 27, wherein the one or more high refractive index layers of the inner layered film are the one or more absorbing layers.