PATENT DOCUMENT

Publication Number: US-10466395-B1
Application Number: US-201715703749-A
Country: US
Kind Code: B1

Title: Systems with matte infrared-transparent layers

Abstract:
A system such as a vehicle system, building, or electrical equipment may be provided with one or more optical components. The optical components may include a near-infrared camera or other components that operate at near-infrared wavelengths. A visible-light-reflecting-and-infrared-light-transmitting layer may overlap the optical component. This overlapping layer may have first and second index-matched layers and an interposed textured layer. The textured layer may be a thin-film interference filter or other coating that is configured to reflect visible light while transmitting infrared light. The transmitted infrared light may pass to the optical component with minimal wavefront distortion due to the index matching of the first and second layers. The texture of the textured layer may cause visible light to reflect diffusely and thereby provide the visible-light-reflecting-and-infrared-light-transmitting layer with a matte appearance.

Claims:
What is claimed is: 
     
       1. A system, comprising:
 an infrared optical component; 
 a visible-light-reflecting-and-infrared-light-transmitting layer that overlaps the infrared optical component and that includes:
 a first infrared-light-transmitting layer with a textured surface, 
 a visible-light-reflecting-and-infrared-light-transmitting coating layer on the textured surface, and 
 a second infrared-light-transmitting layer on the visible-light-reflecting-and-infrared-light-transmitting coating layer; and 
 
 vehicle support structures laterally adjacent to the visible-light-reflecting-and-infrared-light-transmitting layer, wherein an entire lateral area of the visible-light-reflecting-and-infrared-light-transmitting layer is color matched to the vehicle support structures. 
 
     
     
       2. The system defined in  claim 1  wherein the first infrared-light-transmitting layer has a first refractive index, wherein the second infrared-light-transmitting layer has a second refractive index, and wherein the first and second refractive indexes differ by less than 0.2. 
     
     
       3. The system defined in  claim 1  wherein the infrared optical component comprises an infrared camera. 
     
     
       4. The system defined in  claim 1  wherein the visible-light-reflecting-and-infrared-light-transmitting coating layer comprises a stack of thin-film layers on the textured surface. 
     
     
       5. The system defined in  claim 4  wherein the stack of thin-film layers is a thin-film-interference filter formed from inorganic layers with different index of refraction values that is configured to reflect at least 50% of visible light from 400-700 nm and that is configured to transmit at least 80% of infrared light at 900-1000 nm. 
     
     
       6. The system defined in  claim 5  wherein the first infrared-light-transmitting layer comprises a polymer layer. 
     
     
       7. The system defined in  claim 6  wherein the polymer layer comprises a polycarbonate layer. 
     
     
       8. The system defined in  claim 3  wherein the visible-light-reflecting-and-infrared-light-transmitting coating layer comprises at least one layer that exhibits a bulk visible light transmission of less than 80% and an infrared light transmission of greater than 80%. 
     
     
       9. The system defined in  claim 3  wherein the visible-light-reflecting-and-infrared-light-transmitting coating layer comprises a layer of amorphous silicon. 
     
     
       10. The system defined in  claim 1  wherein a given one of the first infrared-light-transmitting layer and the second infrared-light transmitting layer comprises polymer that includes a dye that colors the polymer. 
     
     
       11. The system defined in  claim 1  wherein a given one of the first infrared-light-transmitting layer and the second infrared-light transmitting layer comprises polymer that includes a pigment that colors the polymer. 
     
     
       12. Apparatus, comprising:
 a textured polymer layer having a textured surface; 
 a thin-film interference filter formed from a stack of thin-film layers on the textured polymer layer, wherein the thin-film interference filter is configured to reflect visible light and transmit infrared light; 
 a polymer coating layer on the thin-film interference filter; 
 a first anti-reflective coating on the textured polymer layer; and 
 a second anti-reflective coating on the polymer coating layer. 
 
     
     
       13. The apparatus defined in  claim 12  wherein the textured polymer layer has a first refractive index, wherein the polymer coating layer has a second refractive index, and wherein the first and second refractive indexes are within 0.2 at wavelengths of 900-1000 nm. 
     
     
       14. The apparatus defined in  claim 12  further comprising:
 an infrared optical component that is configured to receive infrared light at a wavelength of 900-1000 nm through the thin-film interference filter and the first anti-reflective coating. 
 
     
     
       15. The apparatus defined in  claim 14  further comprising colorant in a given one of the textured polymer layer and the polymer coating layer, wherein visible light is colored by the colorant and diffusely reflects from the thin-film interference filter. 
     
     
       16. A vehicle having an interior and an exterior, comprising:
 a vehicle body that separates the interior from the exterior; 
 a dashboard in the interior; 
 a near-infrared camera; and 
 a visible-light-reflecting-and-infrared-light-transmitting layer in the dashboard and overlapping the near-infrared camera, wherein the visible-light-reflecting-and-infrared-light-transmitting layer comprises:
 a first infrared-transparent layer having a textured surface, 
 a thin-film stack at the textured surface that is configured to transmit infrared light from the interior to the near-infrared camera and that is configured to reflect at least some visible light from the interior through the first infrared-transparent layer and back towards the interior, and 
 a second infrared-transparent layer, wherein the thin-film stack is interposed between the first infrared-transparent layer and the second infrared-transparent layer. 
 
 
     
     
       17. The vehicle defined in  claim 16  wherein the first infrared-transparent layer comprises a polymer containing a colorant. 
     
     
       18. The vehicle defined in  claim 17  wherein the first and second infrared-transparent layers comprise polymers with index of refraction values that match within 0.05 and wherein the colorant provides the first infrared-transparent layer with a non-black color. 
     
     
       19. The apparatus defined in  claim 12 , wherein the textured polymer layer is interposed between the first anti-reflective coating and the thin-film interference filter, wherein the thin-film interference filter is interposed between the textured polymer layer and the polymer coating layer, and wherein the polymer coating layer is interposed between the thin-film interference filter and the second anti-reflective coating. 
     
     
       20. The vehicle defined in  claim 16 , wherein the visible-light-reflecting-and-infrared-light-transmitting layer further comprises:
 a first infrared antireflection coating on the first infrared-transparent layer; and 
 a second infrared antireflection coating on the second infrared-transparent layer.

Description:
This application claims the benefit of provisional patent application No. 62/397,457, filed on Sep. 21, 2016, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to infrared-transparent structures, and, more particularly, to systems having infrared-transparent layers with a matte appearance. 
     BACKGROUND 
     In vehicles, building systems, portable electronic devices, and other systems, it is often desirable to provide structures that modify the propagation of light. For example, it may sometimes be desirable to provide these systems with layers that block visible light while transmitting infrared light. 
     It can be challenging to incorporate infrared-transparent structures such as these into systems. If care is not taken, structures that are infrared-transparent will have an undesirable appearance. 
     SUMMARY 
     A system such as a vehicle system, building, or electrical equipment may be provided with one or more optical components. The optical components may include a near-infrared camera or other components that operate at near-infrared wavelengths. 
     A visible-light-reflecting-and-infrared-light-transmitting layer may overlap the optical component. This overlapping layer may have first and second index-matched layers and an interposed textured layer. The textured layer may be a thin-film interference filter or other coating that is configured to reflect visible light while transmitting infrared light. 
     The infrared light that passes through the visible-light-reflecting-and-infrared-light-transmitting layer may reach the optical component with minimal wavefront distortion due to the matched refractive indexes of the first and second layers. 
     The texture of the textured layer may cause visible light to reflect diffusely and thereby provide the visible-light-reflecting-and-infrared-light-transmitting layer with a matte appearance. Colorant such as dye or pigment may be added to the visible-light-reflecting-and-infrared-light-transmitting layer to match the appearance of the visible-light-reflecting-and-infrared-light-transmitting layer to nearby structures in the system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an illustrative system in accordance with an embodiment. 
         FIG. 2  is a cross-sectional side view of an illustrative optical component such as an infrared camera in accordance with an embodiment. 
         FIG. 3  is a diagram showing how a textured visible-light-scattering layer may be formed in an infrared-transparent layer in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of an illustrative multilayer stack that may be used in forming an antireflection coating or a thin-film interference filter such as a visible-light-blocking-and-infrared-light-transmitting filter in accordance with an embodiment. 
         FIG. 5  is a cross-sectional side view of an illustrative layer of bulk material that may exhibit a desired light absorption spectrum such as a spectrum that absorbs visible light and transmits infrared light in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of an illustrative coating layer for an infrared-transparent layer that has a layer of bulk material and a stack of thin-film layers in accordance with an embodiment. 
         FIG. 7  is a diagram showing illustrative light transmission characteristics for infrared-transparent layers in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A system may have infrared optical components. Infrared-transparent layers may cover infrared optical components to protect the infrared optical components and to hide the infrared optical components from view. 
       FIG. 1  is a diagram of an illustrative system that may include an infrared-transparent layer. System  10  of  FIG. 1  may be a building, a vehicle, electronic equipment such as a cellular telephone, laptop computer, or other portable electronic device, or other suitable system that includes electrical components. Some of the electrical components may be light-based components (sometimes referred to as optical components) that operate using infrared light. As an example, system  10  may include one or more infrared optical components such as components  20 . 
     Components  20  may be mounted in alignment with structures that are transparent to infrared light such as infrared-light-transparent layers (structures)  24 . Layers  24  may be at least partly opaque at visible light wavelengths. For example, when viewed by a user of system  10 , layers  24  may be black or may be white or have other non-black colors (e.g., blue, green, red, silver, yellow, gold, or other non-black colors). 
     System  10  may have support structures such as support structures  12 . In a vehicle, support structures  12  may form portions of a vehicle body or portions of a vehicle window (as examples). In other systems, support structures  12  may form walls in a device or building. 
     Infrared-transparent layers  24  may be mounted in openings in structures  12 . Infrared components such as components  20  may be mounted behind infrared transparent layers  24  so that components  20  are overlapped by layers  24  and therefore are protected by layers  24 . 
     Structures  12  may be configured to completely or partly surround an interior region such as interior region  14  and may separate interior region  14  from exterior region  16 . Viewers  26  of layers  24  may include viewers  26  that are located in interior region  14  (e.g., viewers  26  may include vehicle occupants when system  10  is a vehicle) and may include viewers that are located in exterior region  16  (e.g., viewers  26  may include external observers). 
     Layer  24  and surrounding portions of system  10  may be illuminated by interior and exterior light sources  18 . Light sources  18  may include light-emitting diodes, lamps, the sun, and other sources of light. Light  30  that is emitted by one or more of light sources  18  may include visible and infrared light. 
     Infrared-transparent layer  24  may be mounted in structures  12  so that portions of structures  12  are adjacent to layer  24 . For example, portions  121  of structures  12  in interior  14  may be adjacent to layer  24  in interior  14  and portions  12 E on the exterior of structures  12  may lie adjacent to layer  24  on the exterior surface of structures  12 . To enhance visual aesthetics, it may be desirable for the appearance of layers  24  to match the appearance of adjacent portions of system  10  such as portions  22  (e.g. it may be desirable for layers  24  and portions  22  to be color matched). 
     Portions (structures)  22  (e.g., external body portions and/or internal body portions in a vehicle) may sometimes be referred to as fascias, fascia structures, or fascia portions of system  10 . Interior body portions in a vehicle (e.g., structures  121 ) may form portions of a vehicle dashboard or other mounting structure for layer  24 . Exterior body portions in a vehicle (e.g., structures  12 E) may form portions of a vehicle bumper, front, side, rear, or roof body panel or may form a window portion (e.g., a window portion that is covered with a colored ink or other opaque layer). As an example, in interior  14 , structures  22  may form a vehicle dashboard and in exterior  16  structures  22  may form a portion of a bumper or other body part in a vehicle body. Structures  22  may also form part of a display in an electronic device such as a cellular telephone or computer (e.g., a glass display cover layer that is coated with opaque ink or other opaque masking material), may form part of a window, or may form other structures for mounting layers  24 . 
     Structures  22  may be formed from plastic, glass, metal, wood, fabric, other materials, or combinations of these materials. Structures  22  may be visually opaque and may have a variety of different colors. As an example, structures  22  may be black, silver, gray, white, blue, green, red, yellow, or may have other colors. To visually coordinate the appearance of structures  22  and layers  24 , it may be desirable for layers  24  to be at least partially opaque at visible wavelengths (e.g., it may be desirable for layers  24  to reflect and block at least 50% or at least 70% or other suitable amount of visible light from 400-700 nm). 
     As an example, structures  22  may have a blue appearance and layers  24  may have a blue color or other appearance that is color coordinated with the appearance of structures  22 . To adjust the color of layers  24  to have a desired visual appearance when viewed by interior and exterior viewers  26 , layers  24  may include one or more materials with bulk properties that allow the materials to absorb and reflect visible light (e.g., polymers that contain visible-light-absorbing substances such as dyes or pigments) and/or may include thin-film stacks or other structures that are configured to at least partially block visible light. 
     Dyes, pigments, thin-film stacks, and other materials and structures in layers  24  may be configured to exhibit desired colors for viewers  26  when illuminated by light  30 . If, for example, it is desired for layers  24  to exhibit a blue color, a blue dye or blue pigment may be incorporate into layers  24  or a thin-film stack may be incorporated into layers  24  to produce a desired blue appearance. Particularly when layers  24  have lighter colors (white, silver, gold, red, green, blue, or other non-black colors), it may be desirable for at least a portion of layers  24  to reflect at least 20%, at least 50%, at least 70%, or other suitable amount of visible light at wavelengths of 400-700 nm, while blocking at least 20%, 50%, 70%, 80%, etc. of visible light at 400-700 nm. This may allow light to reflect from layer  24  through an overlapping colored polymer layer or other layer in layers  24  so that the color of the color polymer layer is visible to a viewer. 
     At the same time, satisfactory performance of infrared-light components  20  can be ensured by configuring infrared-transparent layers  24  to exhibit substantial transparency at infrared light wavelengths. Layers  24  may, for example, exhibit transparency values of greater than 50%, greater than 70%, greater than 80%, greater than 90%, less than 99.99%, or other suitable values at near infrared wavelengths (e.g., wavelengths above 800 nm, from 800-2500 nm, less than 3000 nm, 900-1000 nm, etc.). 
     If desired, more than one electrical component may be mounted under (behind) each infrared-transparent layer  24 . As shown in  FIG. 1 , for example, one or more components  32  may be mounted behind layers  24  in addition to infrared components  20 . Components  32  may include capacitive touch sensors, force sensors, temperature sensors, antennas or other wireless circuits, and/or other electrical components. 
     Infrared components  20  may be any suitable components that operate at infrared wavelengths. As an example, components  20  may include infrared proximity sensors. Infrared proximity sensors may include a light source such as an infrared light-emitting diode or infrared laser that emits infrared light and a corresponding infrared-light detector (e.g., a silicon photodetector) that measures reflections of the emitted infrared light from nearby objects such as objects  28 . Components  20  may also include lidar sensors. Lidar sensors, which may sometimes be referred to as light detection and ranging sensors or laser radar sensors, may have lasers that emit beams of infrared light, scanning systems that scan the emitted beams, and infrared light detectors that detect reflections of the emitted infrared light from objects  28 . If desired, components  20  may include infrared cameras, light sources that emit infrared light (e.g., arrays of infrared light-emitting diodes and/or infrared lasers that emit light for an infrared cameras), and/or other infrared components. 
       FIG. 2  is a cross-sectional side view of infrared component  20  in an illustrative configuration in which component  20  is an infrared camera. As shown in  FIG. 2 , camera (component)  20  may include a housing such as housing  60 . Infrared image sensor  62  may be formed from a silicon die having an array of image sensor pixels  64  (e.g., pixels with silicon photodetectors or other infrared-sensitive light detectors) or other digital infrared image sensor. A lens such as lens  66  may include one or more infrared-transparent lens elements and may be used to focus incoming infrared light  46  so that sensor  62  may capture images of objects  28 . Infrared components  20  may operate at near infrared wavelengths (e.g., wavelengths of 800-2500 nm, 800 nm or more, 940 nm, 900-1000 nm, 800-1000 nm, below 1000 nm, below 2000 nm, below 3000 nm, or other suitable near infrared wavelengths). 
     A cross-sectional side view an illustrative infrared-transparent structure and an associated infrared component  20  (e.g., an infrared camera or other infrared-light component  20 ) is shown in  FIG. 3 . As shown in  FIG. 3 , infrared-transparent layer  24  may have infrared-transparent layers such as layer  38  and  42 . Optional coatings  36  and  44  (e.g., antireflection coatings, etc.) may be formed on the inner and outer surfaces of layer  24 , respectively. Layers  38  and  42  may be formed from polymers (e.g., polycarbonate, acrylic, etc.), glass, or other materials that are transparent to infrared light. With one illustrative configuration, layer  42  is a substrate layer (e.g., a layer of polycarbonate, etc.) with a textured surface (textured surface  42 ′) on which coating layer  40  is formed to reflect and block visible light while passing infrared light. In this configuration, layer  38  may be an infrared-transparent polymer coating that is formed on coating layer  40 . Other types of arrangements may be used, if desired. For example, layer  38  may be a substrate layer with a textured surface (e.g., layer  38  may be a layer of polycarbonate with a textured surface, etc.), layer  40  may be formed from a coating on the textured surface (e.g., a coating that blocks and reflects visible light while passing infrared light), and layer  42  may be an infrared-transparent polymer coating that is formed on coating layer  40 . Arrangements for layer  24  in which layer  42  is a substrate layer with a textured surface (surface  42 ′) and layer  38  is a coating that is formed on layer  40  on textured surface  42 ′ may sometimes be described herein as an example. This is, however, merely illustrative. Any suitable configuration for forming a textured visible light reflecting layer such as layer  40  that passes infrared light may be used, if desired. 
     Layer  24  may be formed in a vehicle body, in a dashboard, or in other portions of a vehicle (e.g., layer  24  may form part of a front, rear, side, or roof window in a vehicle, may form part of a display layer in a portable electronic device such as a cellular telephone or a computer, etc., or may be formed in any other portion of system  10  (e.g., in a position that overlaps optical component  20 ). 
     The thickness of layer  38 , layer  42 , and/or all of the layers of layer  24  may be 1-5 mm, 3-7 mm, 0.5-4 mm, more than 0.05 mm, more than 0.1 mm, more than 0.5 mm, more than 1 mm, more than 2 mm, more than 3 mm, less than 3 mm, less than 4 mm, less than 5 mm, or other suitable thickness. As an example, a substrate layer in layer  24  (e.g., layer  38  or layer  42 ) may have a thickness of 1-5 mm or other suitable thickness. Coating layers  36 ,  40 , and  44  may have respective thicknesses T 3 , T 2 , and T 1  of 0.1 to 1 microns, more than 0.2 microns, more than 0.3 microns, 0.2 to 0.8 microns, less than 2 microns, less than 5 microns, or other suitable coating thickness values. 
     Layer  38  may have refractive index n 1  at near-infrared wavelengths and layer  42  may have index of refraction n 2  at near-infrared wavelengths. The values of n 1  and n 2  may be matched at infrared wavelengths (e.g., at 940 nm, at 900-1000 nm, or at other near infrared wavelengths). For example, n 1  and n 2  may differ by less than 0.3, less than 0.2, less than 0.1, less than 0.05, more than 0.01, or other suitable refractive index difference at these near infrared wavelengths. 
     Due to the index matching of layers  42  and  38  and the relatively small thickness of layer  40 , incoming infrared light  46  may pass through layer  24  without being reflected significantly and without acquiring excessive transmitted wavefront errors. The reflection of infrared light  46  at the interface between layer  42  and  38  may be, for example, less than 2%, less than 1%, less than 0.5%, less than 0.1%, more than 0.01%, or other suitable value. The low reflectivity and low transmitted wavefront error of light  46  that is passing through layer  24  allows this light to be accurately imaged by an infrared camera or accurately processed by other infrared components  20 . 
     As shown in  FIG. 3 , textured surface  42 ′ of layer  42  creates a light-scattering textured surface on the outer surface of layer  40 . This causes layer  40  to scatter incoming visible light  48  in a diffuse pattern (see, e.g., diffuse scattered light  50 ). In particular, visible light  48  (e.g., light at wavelengths of 400-700 nm) that is incident on layer  24  may be scattered by the visible-light-reflecting and visible-light-blocking properties of layer  40  to produce diffuse scattered visible light  50 . The diffuse nature of scattered light  50  may provide layer  24  with a matte appearance to viewer  26 . 
     To provide scattered light  50  with a desired color (e.g., to ensure that the outward appearance of layer  24  is color matched to adjacent structures  22  or is otherwise colored as desired), dyes, pigments, or other colorants may be added to layer  42  and/or the light reflection spectrum of coating  40 , layer  42 , and/or layer  44  can be adjusted. For example, if it is desired for layer  24  to have a light blue appearance, blue dye or blue pigment that is transparent at near-infrared wavelengths may be incorporated into layer  42 . Using this technique, layer  42  and therefore layer  24  may be provided with a desired appearance to match adjacent portions of body  14  such as portions  22  or other structures in system  10 . For example, layer  24  may be provided with a white appearance, a silver appearance, a red appearance, a blue appearance, a light blue or light red appearance, a dark or light yellow appearance, a light, dark, or medium gray appearance, a gold appearance, or other appearance. 
     In some configurations, a portion of visible light  48  may penetrate to layer  38 , so dyes, pigments, or other colorants may, if desired, be added to layer  38  to help provide layer  24  with a desired color. Coatings such as coatings  44  and  36  and layer  40  may have light reflection and light transmission spectra that can also be configured to provide layer  24  with a desired appearance (a desired color, gloss, etc.). 
     Textured surface  42 ′ may be formed by embossing layer  42  with a textured roller, by pressing against surface  42 ′ with a textured plate in a press, or by otherwise applying pressure with a textured tool. Laser processing techniques, chemical processing techniques, and/or other processing techniques may also be used in forming textured surface  42 ′. Textured surface  42 ′ preferably has a pseudorandom distribution of protrusions (peaks) and recesses (valleys) to provide layer  40  with a diffuse visible light reflectivity. Surface  42 ′ of layer  42  (and therefore the outer surface of layer  40  and the mating surface of layer  38 ) may be characterized by a root-mean-square (RMS) surface roughness R that is sufficiently small to ensure that infrared light  46  that passes to component  20  through any 5 mm diameter area or any 1 cm diameter area of layer  24  will experience a transmitted wavefront error (at 940 nm, 900-1000 nm, or other suitable near-infrared wavelength) of less than 1 radian RMS. 
     The maximum slope of the protrusions and valleys on surface  42 ′ may be, as an example, 20-40°, 30°, or other suitable angle. The spatial scale of the surface roughness of layer  42  (e.g., the average size of the peaks and valleys in surface  42 ′) may be 10 microns, 5-15 microns, more than 3 microns, more than 7 microns, less than 15 microns, less than 25 microns, or other suitable size. The RMS surface roughness R of surface  38 ′ may be less than 1 micron, less than 0.5 microns, 50-200 nm, more than 1 nm, more than 10 nm, less than 300 nm, less than 2 microns, or other suitable surface roughness. 
       FIGS. 4, 5, and 6  are cross-sectional side views of illustrative structures that may be used in forming layers such as layers  36 ,  40 , and  44 . 
     In the configuration of  FIG. 4 , layer  70  includes a stack of thin-film layers  72 . Layer  70  may be used in forming layer  36 , layer  40 , and/or layer  44  or may be used in forming part of layer  36 , layer  40 , and/or layer  44 . Thin-film layers  72  may include silicon oxide, titanium oxide, aluminum oxide, or other metal oxides, silicon nitride or other nitrides, silicon oxynitride, or other inorganic dielectric layers. Thin-film layers  72  may also include semiconductor layers (e.g., indium tin oxide layers, hydrogenated amorphous silicon layers, etc.), and/or metal thin-film layers. The refractive index of layers  72  may vary between layers. For example, layers  72  may include higher refractive index layers (e.g., silicon nitride or titanium oxide) alternated with lower index of refraction layers (e.g., silicon oxide). If desired, thin-film layers  72  may include organic layers (e.g., one or more polymer layers). There may be any suitable number of thin-film layers  72  in layer  70  (e.g. layer  36 ,  40 , and/or  44 ). For example, there may be 2-20 layers  72  in layer  70 , 3-8 layers  72  in layer  70 , more than 3 layers  72  in layer  70 , more than 8 layers  72  in layer  70 , fewer than 30 layers  72 , or other suitable number of thin-film layers  72  in layer  70 . The thicknesses of layers  72  may be less than 1 micron, less than 0.5 microns, less than 0.25 microns, more than 0.05 microns, or other suitable thickness. 
     The number of layers  72  in layer  70  and the thickness and refractive index values of layers  72  may be selected so that layer  70  serves as an infrared antireflection coating (e.g., at 900-1000 nm or other suitable near infrared wavelengths associated with light  46 ) or may be selected so that layer  70  forms a filter that blocks and reflects visible light and transmits infrared light (e.g., a thin-film interference filter with a cut-off wavelength of 750 nm or other suitable wavelength). Layer  70  may also be configured to form an antireflection coating at both visible and infrared wavelengths. If desired, layers  72  may be configured so that the reflectivity spectrum and/or transmission spectrum of layer  70  has a desired shape that imparts a desired color to layer  24 . For example, layer  70  may be configured to reflect red light in an arrangement in which it is desired to provide layer  24  with a reddish appearance. 
     In the illustrative configuration of  FIG. 5 , layer  70  has been formed from a layer of material (layer  74 ) with desired bulk light absorption properties. Layer  74  may be, for example, a layer of semiconductor material such as a hydrogenated amorphous silicon layer that blocks visible light and that transmits infrared light. If desired, bulk light-absorption layers such as layer  74  of  FIG. 5  may include two or more layers  74  (e.g., two or more layers that individually absorb and therefor block visible light while transmitting near infrared light due to their bulk optical properties). 
     If desired, layer  70  (e.g., layer  36 , layer  40 , and/or layer  44 ) may be formed from one or more thin-film stacks of layers  72  (e.g., visible-light-blocking-and-infrared-light-transmitting filters or other thin-film filters and/or antireflection coatings of the types described in connection with  FIG. 4 ) and one or more layers  74  with desired bulk optical properties (e.g., desired visible light absorption and infrared light transmission properties, etc.). This type of arrangement is shown in  FIG. 6 . In the illustrative configuration of  FIG. 6 , one stack of thin-film layers  72  has been formed on one layer  74 , but one or more additional stacks of layers  72  and/or one or more additional layers  74  may be incorporated into layer  70  if desired. 
     Layers  70  (e.g., layers  36 ,  40 , and/or  44 ), layer  38 , and/or layer  42  may have optical properties (light reflection spectrums and light transmission spectrums) that allow layer  24  to have a desired outward appearance for viewers  18  while allowing infrared light  46  to pass to optical component  20 . Illustrative transmission spectrums for layers  36 ,  40 ,  44 ,  38 , and/or  42 , and therefore for some or all of layer  24  are shown in  FIG. 7 . As shown in  FIG. 7 , when a given one of these layers has transmission spectrum  80 , both visible light and infrared light may be transmitted through the layer. A transmission spectrum such as transmission spectrum  80  may be used, for example, for an antireflection coating layer (e.g., layer  44  and/or  36 ). The presence of antireflection layers on layer  24  may enhance light transmission by more than 1%, by more than 2%, by more than 4%, or by other amounts. Infrared light transmission enhancements from layers  44  and  36  may reduce reflections that might otherwise reduce the intensity of incoming light  46  before this light is received by component  20 . Visible light transmission enhancements (e.g., in layer  44 ) may help enhance the appearance of layer  42  (e.g., by decreasing specular reflections from the outermost surface of layer  42 ). 
     When a given layer of layer  24  has transmission spectrum  82  (e.g., when layer  40  is provided with transmission spectrum T and a reflectivity spectrum R that is equal to 1-T or other suitable amount), layer  24  will be provided with good visible light reflecting and blocking capabilities and satisfactory infrared transparency. As illustrated by curve  82 , layer  40  and layer  24  may exhibit a visible light transmission at 400-700 nm that is less than 20%, less than 10%, less than 5%, less than 2%, less than 1%, more than 0.1%, or other suitable amount. The reflectivity of layer  40  may be more than 80%, more than 90%, more than 95%, more than 98%, more than 99%, less than 99.9%, or other suitable amount (e.g. at visible light wavelengths of 400-700 nm). 
     If desired, layer  40  may be provided with an intermediate amount of visible light transmission (see, e.g., curve  84 , which shows how layer  40  and, if desired, layer  24  may have a visible light transmission of 40-60% or other suitable intermediate value and may therefore have a visible light reflection of 60-40% or other suitable amount). This amount of light reflection may be desirable for layer  40  when the target appearance for layer  24  is medium gray. 
     Other layers in layer  24  (e.g., layers  42 ,  38 ,  44 , and  36 ) may also have transmission spectrums such as spectrums  80 ,  84 , and/or  82 , if desired. For example, dye or pigment in layer  42  may have spectrums such as spectrums  82  and  84  and may absorb visible light and pass infrared light. 
     The transmission spectrums of  FIG. 7  (and associated reflectivity spectrums) such as spectrums  82  and  84  have a cut-off wavelength of about 750 nm. For example, transmission T may exhibit a long-wavelength pass band starting above 800 nm. If desired, the transmission and reflection spectrums for one or more of the layers of layer  24  may have more complex shapes (e.g., to create a desired color for layer  24  or to modify the color of layer  24 ). 
     In configurations in which layer  24  forms a window for a vehicle or other system, the window may be formed from layers such as layers  42  and/or  38  and the other layers of  FIG. 3  and may, if desired, include one or more additional layers of transparent glass, clear polymer (e.g., polycarbonate), polymer adhesive layers, and/or other layers. In some arrangements, window(s) for system  10  may include laminated window structures such as one or more layers of glass with interposed polymer layer(s). The polymer in a laminated window may be, for example, a polymer such as polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA). Layer  24  may form one of the layers in a two-layer laminated vehicle window or may be embedded in the PVB or EVA layer between two window layers (as examples). Configurations may also be used for system  10  in which layer  24  forms a visible-light-reflecting-and-infrared-light-transmitting structure for other portions of a vehicle (or other system) such as a vehicle body, a portion of a dashboard, other interior and/or exterior structural portions of a vehicle or other system, portions of a display in an electronic device such as a portable electronic device, portions of a housing or other structure in electronic equipment, etc. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20170913
Publication Date: 20191105
Grant Date: 20191105
Priority Date: 20160921
Inventors: NORTHCOTT, MALCOLM J.
LAST, MATTHEW E.
PERALI, IRENE
ZERCOE, BRADFORD J.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04N23/11", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B1/04", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B5/208", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B5/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/208", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B1/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/208", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B1/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N5/332", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 68391732