Hardened optical window with Anti-reflective film with low visible reflectivity and

Abstract

A window (24) comprising a first layered film (36) and a second layered film (38) is described herein. The window (24) exhibits a maximum hardness at the first layered film (36) of at least 8 GPa as measured by the Brinell Indenter Hardness Test to promote durability and scratch resistance. The amount, thickness, number, and material of alternating layers of the first layered film (36) and the second layered film (38) are configured such that the window (24) has a relatively high light transmittance (e.g., greater than 90%) and a relatively low reflectance (e.g., less than 5%) within a wavelength range of 50 nm of interest centered on a wavelength between 850 nm and 950 nm, while when the window (24) is viewed from the first layering film (36), the window (24) still exhibits a dark opaque appearance.

Description

Technical Field

[0001] CROSS REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority under the Patent Law to U.S. Provisional Application Serial No. 63 / 414128 filed on October 7, 2022 and U.S. Provisional Application Serial No. 63 / 525029 filed on July 5, 2023, the contents of which are the basis of this article and are incorporated herein by reference in their entirety.

[0003] The present invention relates to a protective cover for a sensor system. In particular, the present invention relates to a protective cover comprising a layered film such that the protective cover exhibits anti-reflective properties within a 50 nm wavelength of interest from 850 nm to 850 nm while exhibiting a dark opaque appearance. Background Art

[0004] A light detection and ranging (LIDAR) system includes an electromagnetic radiation transmitter and a sensor. The electromagnetic radiation transmitter transmits an electromagnetic radiation transmitter beam that can be reflected from an object, and the sensor detects the reflected electromagnetic radiation transmitter beam. The electromagnetic radiation transmitter beam can be a continuous wave, pulsed, frequency modulated, or otherwise distributed in a radial range to detect objects in the field of view. Information about the object can be interpreted from the properties of the detected reflected electromagnetic radiation transmitter beam. The distance between the object and the electromagnetic radiation transmitter beam can be determined based on the flight time from the emission of the electromagnetic radiation transmitter beam to the detection of the reflected electromagnetic radiation transmitter beam. If the object is moving, the path and speed of the object can be determined based on the radial position shift of the reflected and detected emitted electromagnetic radiation transmitter beam over time and in some cases based on Doppler frequency measurements.

[0005] LIDAR systems in automobiles and other infrared sensing systems in exposed environments such as aviation or home security applications need to be protected from the environment and various sources of damage, such as with a cover lens or a cover glass window. Vehicles are another potential application for LIDAR systems, where LIDAR systems provide spatial imaging capabilities to achieve assisted driving, semi-automatic driving, or fully automatic driving. In such applications, electromagnetic radiation emitters and sensors are mounted on the roof of the vehicle or on the shorter front part of the vehicle. Electromagnetic radiation emitters that emit electromagnetic radiation with wavelengths outside the visible light range (such as at 905nm or 1550nm) are considered for vehicle LIDAR applications. In order to protect the electromagnetic radiation emitter and sensor from collisions from rocks and other objects, a window is placed between the electromagnetic radiation emitter and sensor and the external environment in the line of sight of the electromagnetic radiation emitter and sensor. For other applications of LIDAR systems, such as aviation and home security applications, a window is similarly placed between the electromagnetic radiation emitter / sensor and the external environment. However, there is the problem of rocks and other objects striking the window scratching the window and causing other types of damage to the window, causing the window to scatter the transmitted and reflected electromagnetic radiation transmitter beams, thereby reducing the effectiveness of the LIDAR system. Summary of the invention

[0006] The present invention solves this problem with a window comprising a first layered film and a second layered film. The first layered film may face away from the electromagnetic radiation emitter / sensor when installed in a LIDAR system and includes a scratch resistant layer embedded therein to provide damage resistance to the window. Therefore, rocks and other objects that collide with the window are less likely to cause defects in the window that scatter the emitted and reflected electromagnetic radiation from the LIDAR sensor, thereby resulting in improved performance. In addition, the first layered film and the second layered film further include alternating layers of materials with different refractive indices (including materials that provide hardness and scratch resistance) so that the number of alternating layers and their thicknesses can be configured so that the window has high transmission and low reflection in a desired wavelength range (e.g., within a 50nm wavelength range around a center wavelength between 850nm and 950nm). The alternating layers of material can further be selected so that the window transmits and reflects a relatively small amount of radiation in the visible spectrum, thereby providing the window with an aesthetically pleasing dark appearance while reducing signal noise caused by visible light that may otherwise impinge on the detector of the LIDAR system.

[0007] Aspect (1) of the present invention relates to a window for a sensing system, comprising: a substrate, comprising a first surface and a second surface, the first surface and the second surface being main surfaces of the substrate; a first layered film disposed on the first surface of the substrate, the first layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein the refractive index of the one or more higher refractive index materials of the first layered film is higher than the refractive index of the one or more lower refractive index materials of the first layered film; a second layered film disposed on the second surface of the substrate, the second layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein the refractive index of the one or more higher refractive index materials of the second layered film is higher than the refractive index of the one or more lower refractive index materials of the second layered film; and a maximum hardness at the first layered film by The window has an average percent transmittance of greater than 90% calculated over a 50 nm wavelength range of interest centered at a wavelength between 850 nm and 950 nm for light incident on the first and second surfaces at an angle of incidence less than or equal to 15°; an average reflectance of less than 4% calculated over a 50 nm wavelength range of interest between 850 nm and 950 nm for light incident on the first and second surfaces at an angle of incidence less than or equal to 15°; and an average percent transmittance of less than 5% calculated from 400 nm to 700 nm for light incident on the first and second surfaces at an angle of incidence less than or equal to 15°.

[0008] Aspect (2) of the present invention relates to a window according to aspect (1), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average P-polarization transmittance and an average S-polarization transmittance greater than 85% calculated within the 50nm wavelength range of interest for light incident on the first surface and the second surface at an incident angle less than or equal to 60°.

[0009] Aspect (3) of the present invention relates to a window according to aspect (2), wherein the average P-polarization transmittance and the average S-polarization transmittance calculated within the 50 nm wavelength range of interest are greater than 89% for light incident on the first surface and the second surface at an incident angle less than or equal to 60°.

[0010] Aspect (4) of the present invention relates to a window according to any one of aspects (1) to (3), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has a CIELAB L* reflectance value less than or equal to 37 for an incident angle less than or equal to 60° on the first layered film.

[0011] Aspect (5) of the present invention is directed to the window according to aspect (4), wherein the CIELAB L* reflectance value is less than or equal to 25 for an incident angle less than or equal to 50° on the first layered film.

[0012] Aspect (6) of the present invention relates to a window according to any one of aspects (1) to (5), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that when observed from one side of the first layered film, the window has CIELAB a* and b* reflectance values ​​greater than or equal to -6.0 and less than or equal to 6.0.

[0013] Aspect (7) of the present invention relates to a window according to any one of aspects (1) to (6), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent transmittance greater than 95% calculated within the 50nm wavelength range of interest for light incident on the first surface and the second surface in the normal direction.

[0014] Aspect (8) of the present invention relates to a window according to any one of aspects (1) to (7), wherein: the refractive index of the substrate for electromagnetic radiation having a wavelength of 905 nm is about 1.45 to about 1.55, the substrate is a glass substrate or a glass ceramic substrate, the refractive index of one or more higher refractive index materials is about 1.7 to about 4.0, and the refractive index of one or more lower refractive index materials is about 1.3 to about 1.6, and the difference in refractive index between any one of the one or more higher refractive index materials and any one of the one or more lower refractive index materials is about 0.5 or greater.

[0015] Aspect (9) of the present invention relates to a window according to any one of aspects (1) to (8), wherein: one of the alternating layers of the first layered film farthest from the substrate forms the end surface material of the window, the end surface material of the window includes a lower refractive index material, and the first layered film includes a scratch-resistant layer formed of one of one or more higher refractive index materials and having a thickness greater than or equal to 1500nm and less than or equal to 5000nm.

[0016] Aspect (10) of the present invention is directed to a window according to aspect (9), wherein the scratch resistant layer is separated from the end surface by a plurality of alternating layers of one or more lower refractive index materials and one or more higher refractive index materials of the first layered film.

[0017] Aspect (11) of the present invention is directed to the window according to aspect (10), wherein the scratch-resistant layer is separated from the end surface by at least 1000 nm.

[0018] Aspect (12) of the present invention relates to a window according to aspects (1) to (11), wherein the one or more higher refractive index materials of the second layered film include silicon having an extinction coefficient less than or equal to 0.01 in the 50 nm wavelength range of interest.

[0019] Aspect (13) of the present invention relates to the window according to aspect (12), wherein the extinction coefficient is less than or equal to 0.005 within the 50 nm wavelength range of interest.

[0020] Aspect (14) of the present invention is directed to the window according to aspect (13), wherein the second layered film includes two or more silicon layers.

[0021] Aspect (15) of the present invention is directed to the window according to aspect (14), wherein the silicon layer of the second layered film closest to the substrate includes a minimum thickness of the two or more silicon layers.

[0022] Aspect (16) of the present invention is directed to the window according to aspect (15), wherein a combined thickness of the silicon layers contained in the second layered film is greater than or equal to 500 nm.

[0023] Aspect (17) of the present invention is directed to the window according to any one of aspects (12) to (16), wherein the layer of one or more higher refractive index materials in the second layered film is not silicon.

[0024] Aspect (18) of the present invention relates to the window according to any one of aspects (1) to (17), wherein the maximum hardness measured by the Berkovich indenter hardness test at the first layered film is at least 15 GPa.

[0025] Aspect (19) of the present invention relates to the window according to any one of aspects (1) to (18), wherein the hardness measured by the Berkovich indenter hardness test at the first layered film is at least 14 GPa in a depth range of 400 nm to 1000 nm.

[0026] Aspect (20) of the present invention relates to a window for a sensing system, comprising: a substrate, comprising a first surface and a second surface, the first surface and the second surface being main surfaces of the substrate; a first layered film, disposed on the first surface of the substrate, the first layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein the refractive index of the one or more higher refractive index materials of the first layered film is higher than the refractive index of the one or more lower refractive index materials of the first layered film; a second layered film, disposed on the second surface of the substrate, the second layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein the one or more higher refractive index materials of the second layered film are The window has a refractive index of a higher refractive index material higher than the refractive index of one or more lower refractive index materials of the second layered film; and a maximum hardness, measured by a Berkovich indenter hardness test at the first layered film, the maximum hardness being at least 8 GPa, wherein the amount, thickness, number and materials of the alternating layers of the first layered film and the second layered film are configured so that the window: has an average reflectivity of less than 4% calculated over a 50 nm wavelength range of interest centered at a wavelength between 850 nm and 950 nm for light incident on the first surface and the second surface at an angle of less than or equal to 15°; has a CIELAB L* reflectance value of less than or equal to 37 for an incident angle of less than or equal to 60° on the first layered film; and has CIELAB a* and b* reflectance values ​​greater than or equal to -6.0 and less than or equal to 6.0 when viewed from one side of the first layered film.

[0027] Aspect (21) of the present invention relates to the window according to aspect (20), wherein the CIELAB L* reflectance value is less than or equal to 25 for an incident angle less than or equal to 50° on the first layered film.

[0028] Aspect (22) of the present invention relates to a window according to any one of aspects (20) to (21), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent transmittance greater than 95% calculated within the 50nm wavelength range of interest for light incident on the first surface and the second surface at an incident angle less than or equal to 15°.

[0029] Aspect (23) of the present invention relates to a window according to any one of aspects (20) to (22), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent transmittance of less than 5% calculated from 400nm to 700nm for light incident on the first surface and the second surface at an incident angle less than or equal to 15°.

[0030] Aspect (24) of the present invention relates to a window according to any one of aspects (20) to (23), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average P-polarization transmittance and an average S-polarization transmittance greater than 85% calculated within a wavelength range of 50 nm for light incident on the first surface and the second surface at an incident angle less than or equal to 60°.

[0031] Aspect (25) of the present invention relates to a window according to aspect (24), wherein the average P-polarization transmittance and the average S-polarization transmittance calculated within the 50 nm wavelength range of interest are greater than 89% for light incident on the first surface and the second surface at an incident angle less than or equal to 60°.

[0032] Aspect (26) of the present invention relates to the window according to any one of aspects (20) to (25), wherein the maximum hardness measured by the Berkovich indenter hardness test at the delaminated film is at least 15 GPa.

[0033] Aspect (27) of the present invention relates to a window according to any one of aspects (20) to (26), wherein: one of the alternating layers of the first layered film farthest from the substrate forms the end surface material of the window, the end surface material of the window includes a lower refractive index material, and the first layered film includes a scratch-resistant layer formed of one of one or more higher refractive index materials and having a thickness greater than or equal to 1500nm and less than or equal to 5000nm.

[0034] Aspect (28) of the present invention relates to a window according to aspect (27), wherein: the scratch-resistant layer is separated from the end surface by multiple alternating layers of one or more lower refractive index materials and one or more higher refractive index materials of the first layered film, and the scratch-resistant layer is separated from the end surface by at least 1000 nm.

[0035] Aspect (29) of the present invention relates to a window according to any one of aspects (20) to (28), wherein the one or more higher refractive index materials of the second layered film include silicon having an extinction coefficient less than or equal to 0.004 in the 50 nm wavelength range of interest.

[0036] Aspect (30) of the present invention is directed to the window according to aspect (29), wherein the second layered film comprises two or more silicon layers.

[0037] Aspect (31) of the present invention is directed to the window according to aspect (30), wherein the silicon layer of the second layered film closest to the substrate comprises a minimum thickness of the two or more silicon layers.

[0038] Aspect (32) of the present invention is directed to the window according to aspect (31), wherein a combined thickness of the silicon layers contained in the second layered film is greater than or equal to 500 nm.

[0039] Aspect (33) of the present invention relates to the window according to any one of aspects (29) to (32), wherein the layer of one or more higher refractive index materials in the second layered film is not silicon.

[0040] Aspect (34) of the present invention relates to a window for a sensing system, comprising: a substrate, comprising a first surface and a second surface, the first surface and the second surface being the main surfaces of the substrate; a first layered film, disposed on the first surface of the substrate, the first layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein the refractive index of the one or more higher refractive index materials of the first layered film is higher than the refractive index of the one or more lower refractive index materials of the first layered film; a second layered film, disposed on the second surface of the substrate, the second layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein the refractive index of the one or more higher refractive index materials of the second layered film is higher than the refractive index of the one or more lower refractive index materials of the second layered film a refractive index of a refractive index material, wherein one or more higher refractive index materials of the second layered film include silicon; and a maximum hardness, measured by a Berkovich indenter hardness test at the first layered film, the maximum hardness being at least 15 GPa, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window: has an average reflectivity of less than 4% calculated over a 50 nm wavelength range of interest centered at a wavelength between 850 nm and 950 nm for light incident on the first surface and the second surface at an angle of incidence of less than or equal to 15°; and has an average percent transmittance of greater than 95% calculated over a 50 nm wavelength range of interest for light incident on the first surface and the second surface at an angle of incidence of less than or equal to 15°.

[0041] Aspect (35) of the present invention relates to a window according to aspect (34), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent transmittance of less than 5% calculated from 400nm to 700nm for light incident on the first surface and the second surface at an incident angle less than or equal to 15°.

[0042] Aspect (36) of the present invention relates to a window according to any one of aspects (34) to (35), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average P-polarization transmittance and an average S-polarization transmittance greater than 85% calculated within a 50nm wavelength range of interest between 850nm and 950nm for light incident on the first surface and the second surface at an incident angle less than or equal to 60°.

[0043] Aspect (37) of the present invention relates to a window according to aspect (36), wherein the average P-polarization transmittance and the average S-polarization transmittance calculated within the 50 nm wavelength range of interest between 850 nm and 950 nm are greater than 89% for light incident on the first surface and the second surface at an incident angle less than or equal to 60°.

[0044] Aspect (38) of the present invention relates to a window according to any one of aspects (34) to (37), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has a CIELAB L* reflectance value less than or equal to 37 for an incident angle less than or equal to 60° on the first layered film.

[0045] Aspect (39) of the present invention relates to the window according to aspect (38), wherein the CIELAB L* reflectance value is less than or equal to 25 for an incident angle less than or equal to 50° on the first layered film.

[0046] Aspect (40) of the present invention relates to a window according to any one of aspects (34) to (39), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that when viewed from one side of the first layered film, the window has CIELAB a* and b* reflectance values ​​greater than or equal to -6 and less than or equal to 6.

[0047] Aspect (41) of the present invention relates to a window according to any one of aspects (34) to (40), wherein: one of the alternating layers of the first layered film farthest from the substrate forms the end surface material of the window, the end surface material of the window includes a lower refractive index material, and the first layered film includes a scratch-resistant layer formed of one of one or more higher refractive index materials and having a thickness greater than or equal to 1500nm and less than or equal to 5000nm.

[0048] Aspect (42) of the present invention relates to a window according to aspect (41), wherein: the scratch-resistant layer is separated from the end surface by multiple alternating layers of one or more lower refractive index materials and one or more higher refractive index materials of the first layered film, and the scratch-resistant layer is separated from the end surface by at least 1000 nm.

[0049] Aspect (43) of the present invention relates to a window according to any one of aspects (34) to (42), wherein the second layered film comprises two or more silicon layers having an extinction coefficient less than or equal to 0.01 in the 50 nm wavelength range of interest.

[0050] Aspect (44) of the present invention is directed to the window according to aspect (43), wherein the silicon layer of the second layered film closest to the substrate comprises a minimum thickness of the two or more silicon layers.

[0051] Aspect (45) of the present invention is directed to the window according to aspect (44), wherein the combined thickness of the silicon layers contained in the second layered film is greater than or equal to 500 nm.

[0052] Aspect (46) of the present invention relates to the window according to any one of aspects (43) to (45), wherein the layer of one or more higher refractive index materials in the second layered film is not silicon.

[0053] Aspect (47) of the present invention relates to a window according to aspect (46), wherein the layer of the one or more higher refractive index materials that is not silicon in the second layered film is the layer of the one or more higher refractive index materials closest to the substrate.

[0054] Aspect (48) of the present invention relates to the window according to any one of aspects (34) to (47), further comprising a perfluoropolyether layer disposed on the first layered film.

[0055] Aspect (49) of the present invention relates to the window according to any one of aspects (14) to (30), wherein the second layered film comprises a TCO material layer, wherein two or more silicon layers are disposed between the TCO material layer and the substrate.

[0056] Aspect (50) of the present invention relates to a window according to aspect (49), wherein the TCO material layer comprises a sheet resistance greater than or equal to 140Ω / □ and less than or equal to 210Ω / □, wherein the TCO material layer comprises a thickness greater than or equal to 20nm and less than or equal to 30mm.

[0057] Aspect (51) of the present invention is directed to the window according to aspect (50), wherein the TCO material layer is indium tin oxide and comprises an extinction coefficient less than or equal to .05 over the entire 50 nm wavelength range of interest.

[0058] Aspect (52) of the present invention relates to a window according to any of the preceding aspects, wherein an internal AR stack separates two or more silicon layers from the inner end surface of the second layered film, wherein the internal AR stack includes at least two layers of one or more higher refractive index materials that are not silicon.

[0059] Aspect (53) of the present invention relates to a window according to aspect (52), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent reflectivity of less than 0.5% calculated over a 50 nm wavelength range of interest for light incident on the interior end surface at an incident angle less than or equal to 15°.

[0060] Aspect (54) of the present invention relates to a window according to any one of aspects (51) to (53), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent transmittance of less than 1% calculated from 400nm to 700nm for light incident on the first surface and the second surface in the normal direction.

[0061] Aspect (55) of the present invention relates to a window according to any one of aspects (51) to (54), wherein: the second layered film comprises at least ten silicon layers and the inner AR stack comprises less than two layers of one or more higher refractive index materials that are not silicon.

[0062] Aspect (56) of the present invention relates to a window according to aspect (55), wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window exhibits a polarization average reflectivity range (maximum value-minimum value) of less than 0.5% calculated over a wavelength range of 850 nm to 950 nm for light incident on the first layered film at an incident angle of 15°.

[0063] Additional features and advantages will be set forth in the detailed description that follows, and in part will become apparent to those skilled in the art from that description, or may be learned by practicing the embodiments as described herein, including the following detailed description, claims, and accompanying drawings.

[0064] It should be understood that both the foregoing general description and the following detailed description are merely illustrative 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 into 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 operation of the various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 is a side view of a vehicle in an external environment illustrating a LIDAR system on a roof of the vehicle and another LIDAR system on a front portion of the vehicle in accordance with one or more embodiments of the present invention;

[0066] Figure 2 According to one or more embodiments of the present invention Figure 1 A schematic diagram of one of the LIDAR systems of FIG. 1, illustrating an electromagnetic radiation transmitter and a sensor in a housing, the radiation transmitter emitting electromagnetic radiation that exits the housing through a window and returns through the window as reflected radiation;

[0067] Figure 3 According to one or more embodiments of the present invention Figure 2The area III of Figure 2 a cross-sectional view of a window of , illustrating a window comprising a substrate having a layered film over a first surface of the substrate and a second layered film over a second surface of the substrate;

[0068] Figure 4 According to one or more embodiments of the present invention Figure 3 The interception is made at region IV of Figure 3 a cross-sectional view of a window of illustrating a layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein the layer of the one or more lower refractive index materials provides the end surface closest to the external environment;

[0069] Figure 5 According to one or more embodiments of the present invention Figure 3 The area V is intercepted Figure 3 a cross-sectional view of a window of illustrating a second layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein the layers of the one or more lower refractive index materials provide end surfaces proximate to the electromagnetic radiation emitter and sensor;

[0070] Fig. 6A is a graph of the refractive index and extinction coefficient of silicon materials that can be used in layered films in the wavelength range of 350 nm to 1000 nm according to one or more embodiments of the present invention;

[0071] Figure 6B is in the wavelength range of 800nm ​​to 1000nm according to one or more embodiments of the present invention Fig. 6A A graph of the extinction coefficient of silicon material represented in;

[0072] Figure 7 is a graph of modeled dual surface light transmittance for light in the infrared wavelength range of interest of 850 nm to 950 nm incident on a first layered film of a first example window at an incident angle of 15° in accordance with one or more embodiments of the present invention;

[0073] Figure 8 is a graph of modeled dual surface transmittance for s- and p-polarized light in the infrared wavelength range of interest of 850 nm to 950 nm incident on a first layered film of a first example window at an incident angle of 60° in accordance with one or more embodiments of the present invention;

[0074] Fig. 9 is a graph of modeled dual surface reflectance for light in the infrared wavelength range of interest of 850 nm to 950 nm incident on the first layered film and the second layered film of the first example window at an incident angle of 15° in accordance with one or more embodiments of the present invention;

[0075] Fig.10 is a graph of modeled dual surface light transmittance for light in the visible spectrum incident on a first layered film of a first example window at an incident angle of 15° in accordance with one or more embodiments of the present invention;

[0076] Fig.11A is a graph of modeled CIELAB color space values ​​a* and b* for reflectance of light incident on a first layered film of a first example window at multiple incident angles in accordance with one or more embodiments of the present invention;

[0077] Fig. 11B is a graph of modeled CIELAB lightness values, L*, of reflectance of light incident on a first layered film of a first example window at a plurality of incident angles according to one or more embodiments of the present invention;

[0078] Fig.12 is a graph of nanoindentation hardness as a function of depth into a first layered film for a sample constructed according to a first example window in accordance with one or more embodiments of the present invention;

[0079] Fig.13 is a graph of modeled dual surface light transmittance in the spectral range of 350 nm to 1500 nm for light incident on a first layered film of a second example window according to one or more embodiments of the present invention;

[0080] Fig.14 is a graph of modeled dual surface reflectance over a spectral range of 350 nm to 1500 nm for light incident on a first layered film and a second layered film of a second example window according to one or more embodiments of the present invention;

[0081] Fig.15 is a graph of modeled CIELAB color space values ​​a* and b* for reflectance of light incident on a first layered film of a second example window at multiple incident angles in accordance with one or more embodiments of the present invention;

[0082] Fig.16 is a graph of modeled dual surface light transmittance in the spectral range of 350 nm to 1500 nm for light incident on a first layered film of a third example window according to one or more embodiments of the present invention;

[0083] Fig.17A is a graph of modeled dual surface reflectance in the spectral range of 350 nm to 1500 nm for light incident on a first layered film and a second layered film of a third example window according to one or more embodiments of the present invention;

[0084] Fig. 17Bis a graph of modeled dual surface reflectance in the spectral range of 850 nm to 950 nm for light incident on a first layered film and a second layered film of a third example window according to one or more embodiments of the present invention;

[0085] Fig.18 is a graph of modeled CIELAB color space values ​​a* and b* for reflectance of light incident on a first layered film of a third example window at multiple incident angles in accordance with one or more embodiments of the present invention;

[0086] Fig.19 is a graph of modeled dual surface transmittance over a spectral range of 350 nm to 1600 nm for light incident on a first layered film of a fourth example window according to one or more embodiments of the present invention;

[0087] Fig. 20A is a graph of modeled reflectivity of light in the spectral range of 350 nm to 1700 nm incident on a first layered film of a fourth example window according to one or more embodiments of the present invention;

[0088] Fig. 20B is a graph of modeled reflectivity of light in the spectral range of 350 nm to 1700 nm incident on a second layered film of a fourth example window according to one or more embodiments of the present invention;

[0089] Fig. 20C is a graph of modeled reflectance of light in the spectral range of 800 nm to 1050 nm incident on the first layered film of the third example window and the fourth example window at an incident angle of 15° according to one or more embodiments of the present invention;

[0090] Fig.20D is a graph of modeled reflectivity of light in the spectral range of 800 nm to 1050 nm incident on the first layered film of the third example window and the fourth example window at an incident angle of 60° according to one or more embodiments of the present invention;

[0091] Fig.20E is a graph of modeled reflectivity of light in the spectral range of 800 nm to 1050 nm incident on the second layered film of the third example window and the fourth example window at an incident angle of 15° according to one or more embodiments of the present invention; and

[0092] Fig.21 is a graph of modeled CIELAB color space values ​​a* and b* for reflectance of light incident on a first layered film of a fourth example window at various incident angles in accordance with one or more embodiments of the present invention. DETAILED DESCRIPTION

[0093] Reference will now be made in detail to an embodiment of a window for a LIDAR sensor. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. The window described herein may include a first layered film and a second layered film, which are composed of alternating layers of a higher refractive index material and a lower refractive index material and are configured to provide a relatively high transmittance and a relatively low reflectivity in the desired infrared wavelength range of interest. When the window is installed in the LIDAR system, the first layered film may face away from the sensor / electromagnetic radiation emitter and be exposed to the external environment, while the second layered film may face the sensor / electromagnetic radiation emitter. That is, when the LIDAR system is observed from the outside, the observer can observe the first layered film. The light emitted by the electromagnetic radiation emitter may first be incident on the second layered film before propagating through the substrate. According to the present invention, the first layered film of the window described herein may include one or more relatively thick (e.g., greater than or equal to 500nm) scratch-resistant layers of a high refractive index material. The scratch resistant layer may be embedded within the first layered film such that the window comprises a maximum nanoindentation hardness of greater than or equal to 8 GPa (e.g., greater than or equal to 10 GPa, greater than or equal to 12 GPa, greater than or equal to 14 GPa) when measured by a Berkovich indenter hardness test at the first layered film. This nanoindentation hardness may be at a depth of 1 μm within the first layered film. This nanoindentation hardness beneficially provides scratch resistance and improves the performance of the LIDAR system.

[0094] In aspects, the alternating layers of the first and second layered films of the windows described herein are also constructed to provide the optical performance attributes required for operation of the LIDAR system in the infrared spectrum. In embodiments, the amount, thickness, number, and materials of the alternating layers of the first and second layered films are configured such that the window has an average percent transmittance greater than 90% (e.g., greater than or equal to 95%) calculated over a wavelength range of interest of at least 50 nm, 60 nm, 70 nm, 80 nm, or 90 nm centered at a wavelength in the range of 850 nm to 950 nm for light incident on the first and second surfaces at an angle of incidence of 15° or less. In embodiments, the amount, thickness, number, and materials of the alternating layers of the first and second layered films are configured such that the window has a transmittance greater than or equal to 92% over the entire spectral range of 950 nm to 950 nm for light incident in the normal direction, and preferably a transmittance greater than or equal to 94%, and even more preferably a transmittance greater than or equal to 96%. The amount, thickness, number and material of the alternating layers of the first layered film and the second layered film can be configured so that the window also includes an average percent P-polarization transmittance and S-polarization transmittance calculated within the 50nm (or 60nm, or 70nm, or 80nm, or 90nm) wavelength range of interest of greater than 85% (e.g., greater than or equal to 89%, greater than or equal to 90%, greater than or equal to 93%) for light incident on the first surface and the second surface at an incident angle of 60 degrees or less. In an embodiment, the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent reflectivity of less than or equal to 5.0% (e.g., less than or equal to 4.0%, less than or equal to 3.0%, less than or equal to 2.0%, less than or equal to 1.0%) calculated within the 50nm (or 60nm, or 70nm, or 80nm, or 90nm) wavelength range of interest for light incident on the first surface and the second surface at an incident angle of 15° or less. In aspects, the amount, thickness, number, and materials of the alternating layers of the first and second layered films are configured such that the window has an average percent reflectivity (for both S and P polarizations) of less than 4.0% (e.g., less than or equal to 3.0%, less than or equal to 2.0%, less than or equal to 1.0) away from the second layered film at an incident angle of less than 15°. In aspects, the amount, thickness, number, and materials of the alternating layers of the first and second layered films are configured such that the window has an average percent reflectivity (for both S and P polarizations) of less than 5.5% (e.g., less than or equal to 5.0%, less than or equal to 4.0%, less than or equal to 3.5%, less than or equal to 3.0%, less than or equal to 2.0%, less than or equal to 1.0) away from the second layered film at an incident angle of less than 45°.In aspects, the amount, thickness, number and materials of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent reflectivity (for both S and P polarizations) of less than 8.0% (e.g., less than or equal to 7.5%, less than or equal to 7.0%, less than or equal to 6.5%, less than or equal to 6.0%, less than or equal to 5.0%, less than or equal to 5.0%, less than or equal to 4.0%, less than or equal to 3.5%, less than or equal to 3.0%, less than or equal to 2.0%, less than or equal to 1.0) away from the second layered film at an incident angle less than 60°.

[0095] In other aspects, the first layered film and the second layered film of the window described herein can also be constructed to have relatively low reflectivity and transmittance for visible light, thereby providing the window with an aesthetically pleasing dark appearance and eliminating signal noise. In embodiments, for example, the amount, thickness, number, and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent transmittance of less than 5% (e.g., less than or equal to 4.5%, less than or equal to 4.0%, less than or equal to 3.5%, less than or equal to 3.0%, less than or equal to 2.5%, less than or equal to 2.0%) for light incident on the first layered film at an incident angle of 15° or less calculated from 400nm to 700nm. In embodiments, for example, the amount, thickness, number, and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent transmittance of less than 1% for light incident on the first layered film in the normal direction calculated from 450nm to 650nm. This low transmission of visible light can be achieved by incorporating an absorber layer into the second layered film in the amounts described herein.

[0096] The windows may also exhibit low reflection in the visible wavelength range. In embodiments, for example, the amount, thickness, number, and materials of the alternating layers of the first layered film and the second layered film are configured such that the window has an average percent reflectance of less than 10% (e.g., less than or equal to 9.0%, less than or equal to 8.0%, less than or equal to 7.0%, less than or equal to 6.0%, less than or equal to 5.0%, less than or equal to 4.5%, less than or equal to 4.0%, less than or equal to 3.5%, less than or equal to 3.0%, less than or equal to 2.5%, less than or equal to 2.0%) calculated from 450 nm to 650 nm for light incident on the first layered film at an incident angle of 15° or less. In an embodiment, the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent reflectivity of less than 12% (e.g., less than or equal to 11%, less than or equal to 10%, less than or equal to 9.0%, less than or equal to 8.0%, less than or equal to 7.0%, less than or equal to 6.0%, less than or equal to 5.0%, less than or equal to 4.5%, less than or equal to 4.0%, less than or equal to 3.5%, less than or equal to 3.0%, less than or equal to 2.5%, less than or equal to 2.0%) calculated from 450nm to 650nm for light incident on the first layered film at an incident angle of 45° or less. In an embodiment, the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent reflectivity of less than 16% (e.g., less than or equal to 15%, less than or equal to 14%, less than or equal to 13%, less than or equal to 12%, less than or equal to 11%, less than or equal to 10%, less than or equal to 9.0%, less than or equal to 8.0%, less than or equal to 7.0%, less than or equal to 6.0%, less than or equal to 5.0%, less than or equal to 4.5%, less than or equal to 4.0%, less than or equal to 3.5%, less than or equal to 3.0%, less than or equal to 2.5%, less than or equal to 2.0%) calculated from 450nm to 650nm for light incident on the first layered film at an incident angle of 60° or less.

[0097] When viewed from the first layered film (i.e., from outside the LIDAR sensor), the windows described herein can exhibit a reflection having a CIELAB lightness L* value of less than or equal to 40 (e.g., less than or equal to 37, less than or equal to 35, less than or equal to 30) when viewed from an angle of 60 degrees or less. When illuminated by a light source at a plurality of different incident angles ranging from 0° to 90°, the windows described herein can also exhibit a reflection having a CIELAB color space a* and b* values ​​greater than or equal to -6 and less than or equal to 6 (e.g., greater than or equal to -5 and less than or equal to 5, greater than or equal to -4 and less than or equal to 4, greater than or equal to -3 and less than or equal to 3, greater than or equal to -2.5 and less than or equal to 2.5) when viewed from the first layered film. When viewed from the side of the first layered film, the perceived color of the window can be black or relatively dark, making the window less noticeable to an external observer. In an embodiment, the window exhibits CIELAB color space a* and b* values ​​greater than or equal to 2.5 and less than or equal to 2.5 when illuminated by a light source at a plurality of different incident angles ranging from 0° to 60°.

[0098] In other aspects, the windows described herein may be characterized in that they exhibit relatively high transmittance (e.g., greater than or equal to 90%) in a 50 nm (or 60 nm, or 70 nm, or 80 nm, or 90 nm) wavelength range of interest centered at a wavelength of 850 nm to 950 nm, while exhibiting relatively low average transmittance (e.g., less than or equal to 5%) in the visible spectrum (400 nm to 700 nm). This transmittance contrast in a relatively close spectral range is achieved by incorporating an absorber layer having a relatively low extinction coefficient in the 50 nm (or 60 nm, or 70 nm, or 80 nm, or 90 nm) wavelength range of interest. In embodiments, the absorber layer should have an extinction coefficient of less than or equal to 0.01 (e.g., less than or equal to 0.009, less than or equal to 0.008, less than or equal to 0.007, less than or equal to 0.005, less than or equal to 0.004, less than or equal to 0.0035, less than or equal to 0.0030, less than or equal to 0.0025, less than or equal to 0.0020, less than or equal to 0.0015, less than or equal to 0.0010) at wavelengths within the 50 nm (or 60 nm, or 70 nm, or 80 nm, or 90 nm) wavelength range of interest between 850 nm and 950 nm. In embodiments, the absorber layer may simultaneously exhibit an extinction coefficient that is relatively high (e.g., greater than or equal to .05, greater than or equal to .06, greater than or equal to .07, greater than or equal to .08) in the visible spectrum to absorb sufficient visible light to provide the dark opaque appearance described herein. An example material for the absorber layer described herein is a silicon material with a low extinction coefficient in the 50 nm (or 60 nm, or 70 nm, or 80 nm, or 90 nm) wavelength range of interest. When incorporated into the first and second layered films in the amounts described herein, such layers can absorb enough visible light to provide a suitable dark appearance while also achieving relatively high transmittance in the 50 nm (or 60 nm, or 70 nm, or 80 nm, or 90 nm) wavelength range of interest in the near infrared.

[0099] Thus, the windows described herein provide durable anti-reflective properties for the desired wavelength range of interest of 850 nm to 950 nm, while providing an aesthetically pleasing and performance-enhancing black or dark appearance. The windows described herein can improve LIDAR sensor performance over certain existing sensors by preventing visible light from being incident on the sensor and improving the signal-to-noise ratio. In addition, the windows described herein can reduce unwanted glare visible to external observers.

[0100] Unless otherwise noted, the total reflectivity values, specular reflectivity values, and average reflectivity values ​​provided herein are dual-surface reflectivity values ​​that represent the total reflectivity of the entire window, including the reflectivity associated with each material interface in the window (e.g., between air and the layered film, between the layered film and the substrate, etc.). Unless otherwise noted, the reflectivity values ​​provided in the infrared are measured from the side of the second layered film described herein (e.g., from the side positioned to face the sensor and emitter of the LIDAR system), and the reflectivity values ​​provided in the visible light are measured from the side of the first layered film described herein (e.g., from the side positioned to face the external environment of the LIDAR system).

[0101] Unless otherwise specified herein, average transmittance and reflectance values ​​are calculated using the percent reflectance and transmittance values ​​at various wavelengths within the specified wavelength range. The average reflectance transmittance value can be calculated by averaging the values ​​at each integer wavelength within the specified wavelength range.

[0102] Unless otherwise noted herein, CIELAB color space a* and b* and lightness L* values ​​are measured / simulated for a standard observer with a 10 degree field of view using D65 illumination.

[0103] As used herein, the term "dark appearance" or "black appearance" refers to the reflective appearance of a window when viewed from an exterior surface. A window having a dark appearance or black appearance according to the present invention comprises an average light transmittance of 5% or less within 400nm to 700nm when viewed from an angle of 60° or less and a reflectance having a CIELAB lightness L* value of less than 45 when viewed from an angle of 60° or less.

[0104] Unless otherwise expressly stated, it is not intended in any way that any method described herein should be construed as requiring that its steps be performed in a specific order. Therefore, in the event that a method claim does not actually state the order in which its steps are to be followed or in the event that such steps are not otherwise specifically stated in the claims or specification to be limited to a specific order, no order is intended to be inferred in any way. This applies to any possible non-express basis for interpretation, including: logical issues regarding step arrangement or operational flow; ordinary meaning derived from grammatical organization or punctuation; the number or type of embodiments described in the specification.

[0105] As used herein, the term "and / or" when used in a list of two or more items means that any one of the listed items may be used alone, or any combination of two or more of the listed items may be used. For example, if a composition is described as containing components A, B, and / or C, the composition may contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

[0106] Those skilled in the art and those who make or use the invention will envision modifications to the invention. It should therefore be understood that the embodiments shown in the drawings and described above are for illustrative purposes only and are not intended to limit the scope of the invention, which is defined by the appended claims, as interpreted according to the principles of patent law including the doctrine of equivalents.

[0107] In this document, relational terms such as first and second, top and bottom, and the like are used only to distinguish one entity or action from another entity or action, and do not necessarily require or imply any actual such relationship or order between such entities or actions. The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but may also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element beginning with "comprises..." does not, without more limitations, exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0108] As used herein, the term "about" means that the quantity, size, formulation, parameter and other quantities and characteristics are not and need not be exact, but may be approximate and / or may be larger or smaller as needed, reflecting tolerances, conversion factors, rounding, measurement errors and the like, as well as other factors known to those skilled in the art. When the term "about" is used to describe the endpoints of a value or range, the present invention should be understood to include the specific value or endpoint mentioned. Regardless of whether the endpoint of a numerical value or range in the specification is stated as "about", the endpoint of the numerical value or range is intended to include two embodiments: one embodiment is modified with "about" and one embodiment is not modified with "about". It should be further understood that the endpoints of each of the ranges are important relative to the other endpoint and independently of the other endpoint.

[0109] The term "formed from" can mean one or more of comprising, consisting essentially of, or consisting of. For example, a component formed from a particular material can include the particular material, consist essentially of the particular material, or consist of the particular material.

[0110] Also as used herein, the terms "article," "glass article," "ceramic article," "glass ceramic," "glass element," "glass ceramic article," and "glass ceramic articles" may be used interchangeably and in their broadest sense to include any article made in whole or in part of glass and / or glass ceramic materials.

[0111] The term "disposed" is used herein to refer to a layer or sublayer that is coated, deposited, formed, or otherwise disposed on a surface. The term disposed may include layers / sublayers disposed in direct contact with adjacent layers / sublayers or layers / sublayers separated by intermediate materials that may or may not form a layer.

[0112] Unless otherwise stated herein, the refractive indices of the materials described herein are measured at 905 nm.

[0113] As used herein, the term "extinction coefficient" or "k" is a dimensionless property of a material that depends on the absorption coefficient of the material multiplied by the wavelength of light divided by 4π.

[0114] Reference Figure 1 , the vehicle 10 includes one or more LIDAR systems 12. The one or more LIDAR systems 12 may be disposed anywhere on or within the vehicle 10. For example, the one or more LIDAR systems 12 may be disposed on a roof 14 of the vehicle 10 and / or a front portion 16 of the vehicle 10.

[0115] Reference Figure 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. The 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 a window 24, which is in the path of the emitted electromagnetic radiation. If an object (not illustrated) in the external environment 26 is in the path of the emitted radiation 22, the emitted radiation 22 will be reflected from the object and returned to the electromagnetic radiation emitter and sensor 18 as reflected radiation 28. The reflected radiation 28 again passes through the window 24 to the electromagnetic radiation emitter and sensor 18. In an embodiment, the emitted radiation 22 and the reflected radiation 28 may include light in a suitable wavelength range of interest. For example, in embodiments, emitted radiation 22 and reflected radiation 28 may be greater than or equal to 850 nm and less than or equal to 950 nm (e.g., greater than or equal to 875 nm and less than or equal to 925 nm, greater than or equal to 890 nm and less than or equal to 910 nm, approximately 905 nm, 905 nm). Electromagnetic radiation other than reflected radiation 28, such as electromagnetic radiation having wavelengths in portions of the visible spectrum, the ultraviolet range, may also interact with window 24. As described herein, window 24 may include layered films that include a layer structure designed to absorb light in the visible spectrum while also reflecting relatively small amounts of light in the visible spectrum, such that the window has a dark or black appearance when viewed from the exterior of housing 20.

[0116] The "visible spectrum" is the portion of the electromagnetic spectrum visible to the human eye and generally refers to electromagnetic radiation having wavelengths in the range of about 400 nm to about 700 nm. The "ultraviolet range" is the portion of the electromagnetic spectrum having wavelengths between about 10 nm to about 400 nm. The "infrared range" of the electromagnetic spectrum begins at about 700 nm and extends to longer wavelengths. The sun produces solar electromagnetic radiation having wavelengths falling within all three of those ranges, generally referred to as "sunlight."

[0117] Reference Figure 3, the window 24 of each of the one or more LIDAR systems 12 includes a substrate 30. The substrate 30 includes a first surface 32 and a second surface 34. The first surface 32 and the second surface 34 are major surfaces of the substrate 30. The first surface 32 is closest to the external environment 26. The second surface 34 is closest to the electromagnetic radiation emitter and sensor 18. The emitted radiation 22 encounters the second surface 34 before the first surface 32. The reflected radiation 28 encounters the first surface 32 before the second surface 34. The substrate 30 further includes a first layered film 36 disposed on the first surface 32 of the substrate 30 and a second layered film 38 disposed on the second surface 34 of the substrate 30. It should be understood that the window 24 as described herein is not limited to automotive applications, as further described herein, and can be used in any application where the window 24 will help provide improved collision and optical performance.

[0118] According to the present invention, the substrate 30 can be made of a variety of different materials. In an embodiment, the substrate 30 can be made of any type of glass, glass ceramic, ceramic or suitable polymer-based material. Various example structures and compositions of the substrate 30 are now described in more detail.

[0119] In an embodiment, the substrate 30 includes a glass composition or a glass article. For example, the substrate 30 may include borosilicate glass, aluminosilicate glass, soda-lime glass, chemically tempered borosilicate glass, chemically tempered aluminosilicate glass, or chemically tempered soda-lime glass. In an embodiment, the glass composition of the substrate 30 can be chemically tempered by an ion exchange process. In an embodiment, the composition may not contain lithium ions.

[0120] Suitable alkali aluminosilicate glass compositions for substrate 30 include aluminum oxide, at least one alkali metal, and in embodiments greater than 50 mol % SiO 2 , in other embodiments comprising at least 58 mol % SiO 2 , and in yet other embodiments comprises at least 60 mol % SiO 2 , where the ratio (Al 2 O 3 +B 2 O 3 ) / ∑ 改性剂 (i.e., the sum of the modifiers) is greater than 1, wherein the ratio of the components is expressed in mole %, and the modifier is an alkali metal oxide. In a specific embodiment, the composition includes: 58 mol % to 72 mol % SiO 2 ; 9 mol% to 17 mol% Al 2 O 3 ; 2 mol% to 12 mol% B 2 O 3 ; 8 mol% to 16 mol% Na 2O; and 0 mol% to 4 mol% K 2 O, where the ratio (Al 2 O 3 +B 2 O 3 ) / ∑ 改性剂 (that is, the sum of the modifiers) is greater than 1.

[0121] Another suitable alkali aluminosilicate glass composition for substrate 30 includes: 64 mol% to 68 mol% SiO 2 ; 12 mol% to 16 mol% Na 2 O; 8 mol% to 12 mol% Al 2 O 3 ; 0 mol% to 3 mol% B 2 O 3 ; 2 mol% to 5 mol% K 2 O; 4 mol% to 6 mol% MgO; and 0 mol% to 5 mol% CaO, of which: 66 mol% ≤ SiO 2 +B 2 O 3 +CaO≦69 mol%; Na 2 O+K 2 O+B 2 O 3 +MgO+CaO+SrO>10 mol%; 5 mol%≦MgO+CaO+SrO≦8 mol%; (Na 2 O+B 2 O 3 )—Al 2 O 3 ≦2 mol%; 2 mol%≦Na 2 O—Al 2 O 3 ≤6 mol%; and 4 mol% ≤ (Na 2 O+K 2 O)-Al 2 O 3 ≦10 mol%.

[0122] Another suitable alkali aluminosilicate glass composition for substrate 30 includes 2 mol% or more of Al 2 O 3 and / or ZrO 2 or 4 mol% or more Al 2 O 3 and / or ZrO 2 .

[0123] An example glass composition includes SiO 2 , B 2 O 3 And Na2 O, among which (SiO 2 +B 2 O 3 )≧66 mol%, and Na 2 O≧9 mol%. In an embodiment, the composition comprises at least 6 wt% aluminum oxide. In another embodiment, the composition of one or more alkaline earth metal oxides, such as an alkaline earth metal oxide content of at least 5 wt%. In an embodiment, a suitable composition further comprises K 2 In a specific embodiment, the composition of the substrate 30 includes 61 mol% to 75 mol% SiO 2 ; 7 mol% to 15 mol% Al 2 O 3 ; 0 mol% to 12 mol% B 2 O 3 ; 9 mol% to 21 mol% Na 2 O; 0 mol% to 4 mol% K 2 O; 0 mol % to 7 mol % MgO; and 0 mol % to 3 mol % CaO.

[0124] Another example composition suitable for substrate 30 includes: 60 mol% to 70 mol% SiO 2 ; 6 mol% to 14 mol% Al 2 O 3 ; 0 mol% to 15 mol% B 2 O 3 ; 0 mol% to 15 mol% Li 2 O; 0 mol% to 20 mol% Na 2 O; 0 mol% to 10 mol% K 2 O; 0 mol% to 8 mol% MgO; 0 mol% to 10 mol% CaO; 0 mol% to 5 mol% ZrO 2 ; 0 mol% to 1 mol% SnO 2 ; 0 mol% to 1 mol% CeO 2 ; Less than 50ppm As 2 O 3 ; and less than 50ppm Sb 2 O 3 ; 12 mol% ≤ (Li 2 O+Na 2 O+K 2 O)≦20 mol% and 0 mol%≦(MgO+CaO)≦10 mol%.

[0125] Another example glass composition suitable for substrate 30 includes: 63.5 mol% to 66.5 mol% SiO 2; 8 mol% to 12 mol% Al 2 O 3 ; 0 mol% to 3 mol% B 2 O 3 ; 0 mol% to 5 mol% Li 2 O; 8 mol% to 18 mol% Na 2 O; 0 mol% to 5 mol% K 2 O; 1 mol% to 7 mol% MgO; 0 mol% to 2.5 mol% CaO; 0 mol% to 3 mol% ZrO 2 ; 0.05 mol% to 0.25 mol% SnO 2 ; 0.05 mol% to 0.5 mol% CeO 2 ; Less than 50ppmAs 2 O 3 ; and less than 50ppm Sb 2 O 3 ; 14 mol% ≤ (Li 2 O+Na 2 O+K 2 O) ≤ 18 mol % and 2 mol % ≤ (MgO + CaO) ≤ 7 mol %.

[0126] The substrate 30 may be substantially planar or sheet-like, but other embodiments may utilize curved or otherwise shaped or sculpted substrates. The length and width of the substrate 30 may vary depending on the desired size of the window 24. The substrate 30 may be formed using various methods such as float glass processes and down-draw processes such as fusion drawing and slot drawing. The substrate 30 may be used in a non-tempered state. Commercially available examples of suitable non-tempered substrates 30 for the window 24 are Glass code 2320, which is a sodium aluminosilicate glass substrate.

[0127] The glass forming the substrate 30 may be modified so that the region adjacent to the first surface 32 and / or the region adjacent to the second surface 34 is under compressive stress ("compressive stress, CS"). In this case, the region under compressive stress extends from the first surface 32 and / or the second surface 34 to the compression depth. This generation of compressive stress further forms a central region under tensile stress, which has a maximum value at the center of the central region, referred to as central tension or center tension (CT). The central region extends between the compression depths and is under tensile stress. The tensile stress of the central region balances or offsets the compressive stress of the region under compressive stress. As used herein, the terms "compression depth" and "DOC" refer to the depth at which the stress within the substrate 30 changes from compressive stress to tensile stress. At the compression depth, the stress spans from positive (compressive) stress to negative (tensile) stress and therefore has a value of zero. The compression depth protects the substrate 30 from the propagation of cracks introduced by sharp impacts to the first surface 32 and / or the second surface 34 of the substrate 30, while the compressive stress minimizes the possibility of crack growth and penetration through the compression depth. In an embodiment, the compression depths are each at least 20 μm. In an embodiment, the absolute value of the maximum compressive stress CS within the region is at least 200 MPa, at least about 400 MPa, at least 600 MPa, or at most about 1000 MPa.

[0128] In U.S. Patent No. 9,140,543, entitled “Systems and Methods for Measuring the Stress Profile of Ion-Exchanged Glass,” filed by Douglas Clippinger Allan et al. on May 3, 2012, two methods for extracting detailed and accurate stress distribution (stress as a function of depth) of a substrate 30 having a zone under compressive stress are disclosed, and Douglas Clippinger Allan et al. requested priority to U.S. Provisional Patent Application No. 61 / 489,800, filed on May 25, 2011, of the same name, the contents of which are incorporated herein by reference in their entirety.

[0129] In an embodiment, creating a region of the substrate 30 under compressive stress includes subjecting the substrate 30 to an ion exchange chemical tempering process (chemical tempering is often referred to as "chemical toughening"). In the ion exchange chemical tempering process, ions at or near the first surface 32 and the second surface 34 of the substrate 30 are replaced or exchanged with larger ions, typically having the same valence or oxidation state. In those embodiments in which the substrate 30 comprises, consists essentially of, or consists of an alkali aluminosilicate glass, an alkali borosilicate glass, an alkali aluminoborosilicate glass, or an alkali silicate glass, the ions in the surface layer of the glass and the larger ions are monovalent alkali metal cations, such as Na + (When Li + ), K + , Rb + and Cs + Alternatively, the monovalent cations in, at, or near the first and second surfaces 32, 34 may be replaced with monovalent cations other than alkali metal cations, such as Ag. + or similar.

[0130] In an embodiment, the ion exchange process is performed by immersing the substrate 30 in a molten salt bath containing larger ions that will be exchanged with smaller ions in the substrate 30. It will be appreciated by those skilled in the art that the parameters of the ion exchange process, including but not limited to the bath composition and temperature, immersion time, number of immersions of the glass in the salt bath (or multiple salt 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 compression depth and compressive stress of the substrate 30 resulting from the tempering operation. As an example, ion exchange of an alkali-containing glass substrate can be achieved by immersing in at least one molten bath containing salts such as, but not limited to, nitrates, sulfates, and chlorides of larger alkali metal ions. In an embodiment, the molten salt bath includes potassium nitrate (0 wt % to 100 wt %), sodium nitrate (0 wt % to 100 wt %), and lithium nitrate (0 wt % 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° C. to about 500° C., and the immersion time ranges from about 15 minutes to about 40 hours, including about 20 minutes to about 10 hours. However, temperatures and immersion times different from those described above may also be used. The substrate 30 may be acid polished or otherwise treated to remove or reduce the effects of surface cracks.

[0131] In an embodiment, the substrate 30 includes a glass ceramic material having both a glass phase and a ceramic phase. Illustrative glass ceramics include materials in which the glass phase is formed by silicates, borosilicates, aluminosilicates or boroaluminosilicates, and the ceramic phase is formed by β-spodumene, β-quartz, nepheline, hexagonal potassium nepheline or triclinic nepheline. "Glass ceramics" include materials produced by controlled crystallization of glass. Examples of suitable glass ceramics may include Li2O-Al2O3-SiO2 system (i.e., LAS system) glass ceramics, MgO-Al2O3-SiO2 system (i.e., MAS system) glass ceramics, ZnO×A12O3×nSiO2 (i.e., ZAS system) and / or glass ceramics with a main crystalline phase, the main crystalline phase comprising β-quartz solid solution, β-spodumene, cordierite and lithium disilicate. A chemical toughening process may be used to toughen the glass ceramic substrate.

[0132] In an embodiment, substrate 30 comprises a ceramic material such as an inorganic crystalline oxide, nitride, carbide, oxynitride, carbonitride, and / or the like. Illustrative ceramics include those having alumina, aluminum titanate, mullite, cordierite, zircon, spinel, perovskite, zirconia, ceria, silicon carbide, silicon nitride, silicon aluminum oxynitride, or a zeolite phase.

[0133] 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); polyvinyl chloride (PVC); acrylic polymers, including polymethyl methacrylate (PMMA) (including copolymers and blends); thermoplastic urethane (TPU); polyetherimide (PEI); and blends of these polymers. Other exemplary polymers include epoxy resins, styrene resins, phenolic resins, melamine resins, and silicone resins.

[0134] In an embodiment, the substrate 30 includes a plurality of layers or sub-layers. The layers or sub-layers of the substrate 30 may be the same or different from each other. For example, in an embodiment, the substrate 30 includes a glass laminate structure. In an embodiment, the glass laminate structure includes a first glass pane and a second glass pane, which are attached to each other by a suitable interlayer (e.g., a polymer interlayer) disposed between the first glass pane and the second glass pane. In an embodiment, the glass laminate structure includes a glass-on-glass laminate structure formed by, for example, a melt-draw process. Glass-polymer laminates are also considered and within the scope of the present invention. Any material that can meet the optical requirements described herein can be used as the substrate 30.

[0135] In an embodiment, the substrate 30 exhibits an elastic modulus (or Young's modulus) in the range of about 30 GPa to about 120 GPa. In some cases, the elastic modulus of the substrate may be in the range of about 30 GPa to about 110 GPa, about 30 GPa to about 100 GPa, about 30 GPa to about 90 GPa, about 30 GPa to about 80 GPa, about 30 GPa to about 70 GPa, about 40 GPa to about 120 GPa, about 50 GPa to about 120 GPa, about 60 GPa to about 120 GPa, about 70 GPa to about 120 GPa, and all ranges and sub-ranges therebetween.

[0136] In an embodiment, the substrate 30 exhibits an average light transmittance of about 85% or more, about 86% or more, about 87% or more, about 88% or more, about 89% or more, about 90% or more, about 91% or more, or about 92% or more in the visible light 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, etc.

[0137] like Figure 3 , the substrate 30 has a thickness 35 defined as the shortest straight-line distance between the first surface 32 and the second surface 34. In an embodiment, the thickness 35 of the substrate 30 is between about 100 μm and about 5 mm. In an embodiment, the substrate 30 may have a physical thickness 35 ranging from about 100 μm to about 500 μm (e.g., 100 μm, 200 μm, 300 μm, 400 μm, or 500 μm). In other embodiments, the thickness 35 ranges from about 500 μm to about 1000 μm (e.g., 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, or 1000 μm). The thickness 35 may be greater than about 1 mm (e.g., about 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, or 7 mm). In one or more specific embodiments, the thickness 35 is 2 mm or less or less than or equal to 1 mm.

[0138] In embodiments, thickness 35 is uniform (e.g., varies less than 1% throughout the substrate) such that substrate 35 is in the form of a planar sheet. In embodiments, thickness 35 is a variable thickness and has a value that varies with location on substrate 30. Thickness 35 may vary along one or more of its dimensions for aesthetic and / or functional reasons. For example, the edges of substrate 30 may be thicker than more central areas of substrate 30. The length, width, and physical thickness dimensions of substrate 30 may also vary depending on the application or use of article 30.

[0139] In an embodiment, substrate 30 comprises a layer of visible light absorbing, IR transmissive material. Examples of such materials include infrared transmissive, visible light absorbing acrylic sheets, such as those available under the trade name IR acrylic 3143 and CYRO IR acrylic 1146 is commercially available from ePlastics. IRacrylic 3143 has about 0% (at least less than 10% or less than 1%) transmittance for electromagnetic radiation having a wavelength of about 700 nm or less, but has about 90% (greater than 85%) transmittance for wavelengths in the range of 800 nm to about 1100 nm (including 905 nm).

[0140] In an embodiment, the substrate 30 exhibits a refractive index in the range of about 1.45 to about 1.55. In an embodiment, the substrate exhibits an average transmittance greater than or equal to 95% (e.g., greater than or equal to 96%, greater than or equal to 97%, greater than or equal to 98%, greater than or equal to 99%, greater than or equal to 99.5%) over the entire spectral range of 1400 nm to 1600 nm.

[0141] Reference Figure 4 and Figure 5 , the first layered film 36 and the second layered film 38 each include a certain amount of alternating layers of one or more higher refractive index materials 40 and one or more lower refractive index materials 42. Although the same reference numerals are used to identify each of the one or more higher refractive index materials 40 and the one or more lower refractive index materials 42, it should be understood that the use of the same reference numerals does not indicate that each of the layers is composed of the same material or includes the same structure. In each of the first layered film 36 and the second layered film 38, different layers of the layers of the respective higher refractive index materials 40 and lower refractive index materials 42 may include different compositional or structural properties.

[0142] As used herein, the terms "higher refractive index" and "lower refractive index" refer to refractive index values ​​relative to each other, wherein one or more refractive indices of the one or more higher refractive index materials 40 are greater than one or more refractive indices of the one or more lower refractive index materials 42. In an embodiment, the one or more higher refractive index materials 40 have a refractive index of about 1.7 to about 4.5. In an embodiment, the one or more lower refractive index materials 42 have a refractive index of about 1.3 to about 1.6. In an embodiment, the one or more lower refractive index materials 42 have a refractive index of about 1.3 to about 1.7, and the one or more higher refractive index materials 40 have a refractive index of about 1.9 to about 3.8. The difference in refractive index of any of the one or more higher refractive index materials 40 and any of the one or more lower refractive index materials 42 may be about 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1.0 or more, 1.5 or more, 2.0 or more, 2.1 or more, 2.2 or more, or even 2.3 or more. Due to the difference in refractive index of the one or more higher refractive index materials 40 and the one or more lower refractive index materials 42, the manipulation of the amount (number) of alternating layers and their thicknesses may result in selective transmittance of electromagnetic radiation within a range of wavelengths through window 24 and selective reflectance of electromagnetic radiation within a range of wavelengths exiting from first layered film 36, respectively. Thus, the first layered film 36 (and the second layered film 38, if used) is a thin film filter having predetermined optical properties that are configured to vary as a function of the amount, thickness, number, and materials selected as one or more higher refractive index materials 40 and one or more lower refractive index materials 42.

[0143] Some examples of suitable materials for use as the one or more lower refractive index materials 42 include SiO 2 、Al 2 O 3 ,GeO 2 、SiO、AlO x N y 、SiO x N y 、Si u Al v O x N y 、MgO、MgAl 2 O 4 MgF 2 , BaF 2 , CaF 2 ,DyF 3 , YbF 3 , YF 3 and CeF 3The nitrogen content of the material used as the one or more lower refractive index materials 42 can be minimized (e.g., in materials such as AlO x N y 、SiO x N y and Si u Al v O x N y of the materials).

[0144] Some examples of suitable materials for use as the one or more higher refractive index materials 40 include Si, amorphous silicon (a-Si), SiN x 、SiN x :H y 、AlN x 、Si u Al v O x N y 、 2 O 5 , Nb 2 O 5 、AlN、Si 3 N 4 、AlO x N y 、SiO x N y , HfO 2 、TiO 2 、ZrO 2 , Y 2 O 3 、Al 2 O 3 、MoO 3 and diamond-like carbon. The oxygen content of the material used for the higher refractive index material 40 can be minimized, especially in SiN x or AlN x Materials. AlO x N y The material can be considered as oxygen-doped AlN x , that is, they may have AlN x The one or more higher refractive index materials 40 may have a crystalline structure such as wurtzite and need not have an AlON crystalline structure. x N y The material may include about 0 atomic % to about 20 atomic % oxygen or about 5 atomic % to about 15 atomic % oxygen, while containing 30 atomic % to about 50 atomic % nitrogen. Exemplary preferred Si materials for use as one or more higher refractive index materials 40 u Al v O x N yThe materials may include about 10 atomic % to about 30 atomic % or about 15 atomic % to about 25 atomic % silicon, about 20 atomic % to about 40 atomic % or about 25 atomic % to about 35 atomic % aluminum, about 0 atomic % to about 20 atomic % or about 1 atomic % to about 20 atomic % oxygen, and about 30 atomic % to about 50 atomic % nitrogen. The foregoing materials may be hydrogenated up to about 30 weight %. Because the refractive indices of the one or more higher refractive index materials 40 and the one or more lower refractive index materials 42 are relative to each other, the same material (such as Al) may be used. 2 O 3 ) may be applicable to one or more higher refractive index materials 40 depending on the refractive index of the material selected for one or more lower refractive index materials 42, and alternatively, may be applicable to one or more lower refractive index materials 42 depending on the refractive index of the material selected for one or more higher refractive index materials 40.

[0145] In an embodiment, the one or more lower refractive index materials 42 of the first layered film 36 are composed of SiO 2 The one or more higher refractive index materials 40 of the first layered film 36 are composed of SiO x N y or SiN x In one embodiment, the one or more lower refractive index materials 42 of the first layered film 36 are composed of SiO 2 The one or more higher refractive index materials 40 of the first layered film 36 are composed of SiN x or SiO x N y The one or more lower refractive index materials 42 of the second layered film 38 are composed of SiO 2 The one or more higher refractive index materials 40 of the second layered film 38 include a silicon (eg, a-Si) layer. In an embodiment, the one or more lower refractive index materials 42 of the first layered film 36 are composed of SiO 2 The one or more higher refractive index materials 40 of the first layered film 36 are composed of SiN x or SiO x N y The one or more lower refractive index materials 42 of the second layered film 38 are composed of SiO 2 The one or more higher refractive index materials 40 of the second layered film 38 include an amorphous silicon (a-Si) layer and a SiN x or SiO x N y layer.

[0146] There is no particular limitation on the amount of alternating layers of higher refractive index material 40 and lower refractive index material 42 in either the first layered film 36 or the second layered film 38. In embodiments, the number of alternating layers within the first layered film 36 is 7 or more, 9 or more, 11 or more, 13 or more, 15 or more, 17 or more, 19 or more, 21 or more, 23 or more, 25 or more, or 51 or more, or 81 or more. In embodiments, the amount of alternating layers within the second layered film 38 is 7 or more, 9 or more, 11 or more, 13 or more, 15 or more, 17 or more, 19 or more, 21 or more, 23 or more, or 25 or more, or 51 or more, or 81 or more. In embodiments, the amount of alternating layers in the first layered film 36 and the second layered film 38 that together form the window 24 (excluding the substrate 30) is 14 or more, 20 or more, 26 or more, 32 or more, 38 or more, 44 or more, 50 or more, 72 or more, or 100 or more. In general, the greater the amount of layers in the first layered film 36 and the second layered film 38, the more closely the transmittance and reflectance properties of the window 24 are tailored to one or more specific wavelengths or wavelength ranges.

[0147] Each of the alternating layers of first layered film 36 and second layered film 38 has a thickness. The thickness selected for each of the alternating layers determines the optical path length of light propagating through window 24, and determines the constructive and destructive interference between different light rays reflected at each material interface of window 24. Thus, the thickness of each of the alternating layers, in combination with the refractive indices of the one or more higher refractive index materials 40 and the one or more lower refractive index materials 42, determines the reflectivity and transmittance spectra of window 24.

[0148] refer to Figure 3 , Figure 4 and Figure 5 , reflected radiation 28 first encounters end surface 44 of first layered film 36 when interacting with window 24, and end surface 44 may be open to external environment 26. In embodiments, the layer of one or more lower refractive index materials 42 provides end surface 44 to more closely match the refractive index of air in external environment 26, thereby reducing reflection of incident electromagnetic radiation (whether reflected radiation 28 or other radiation) exiting from end surface 44. The layer of one or more lower refractive index materials 42 providing end surface 44 is the layer of first layered film 36 farthest from substrate 30. Similarly, in embodiments, when one or more lower refractive index materials 42 are SiO 2 When SiO is used as one or more lower refractive index materials 42 2 The layer is directly disposed on the first surface 32 of the substrate 30, SiO 2The layer will typically include a large molar percentage of SiO 2 Without being bound by theory, it is believed that SiO in both the substrate 30 and the adjacent layer of the one or more lower refractive index materials 42 2 The commonality allows for increased bonding strength.

[0149] Emitted radiation 22 first encounters end surface 48 of second layered film 38 when interacting with window 24. In embodiments, the layer of one or more lower refractive index materials 42 provides end surface 48 to more closely match the refractive index of air within enclosure 20, thereby reducing reflection of incident emitted radiation 22 away from end surface 48. The layer of one or more lower refractive index materials 42 providing end surface 48 is the layer of second layered film 38 farthest from substrate 30. Similarly, in embodiments, when one or more lower refractive index materials 42 are SiO 2 When SiO is used as one or more lower refractive index materials 42 2 The layer is disposed directly on the second surface 34 of the substrate 30 .

[0150] The material with a relatively high refractive index may also have a relatively high hardness that provides scratch resistance and impact resistance. An example material that has both high hardness and can be one of the one or more higher refractive index materials 40 is SiO x N y Other examples of materials that have both high hardness and a relatively high refractive index material 40 are SiN x 、SiN x :H y and Si 3 N 4 It has been found that relatively thick (e.g., greater than or equal to 500 nm) SiO x N y (or other suitable higher refractive index material) layer can increase the scratch resistance and / or damage resistance of the window 24. This increased scratch resistance and / or damage resistance can be particularly beneficial in the first layered film 36, which may be more likely to encounter impacts with debris from the external environment 26. Therefore, in an embodiment, the first layered film 36 includes a layer of one of the one or more higher refractive index materials 40 having a thickness greater than or equal to 500nm (e.g., greater than or equal to 1000nm, greater than or equal to 1500nm, greater than or equal to 2000nm). This higher refractive index layer having a thickness of 500nm or more is described herein as a "scratch resistant layer."

[0151] In embodiments, the thickness and location within the first layered film 36 of the scratch resistant layer may be optimized to provide a desired degree of hardness and scratch resistance to the first layered film 36 and, therefore, to the entire window 24. Different applications for the window 24 may result in different desired thicknesses of the scratch resistant layer of the higher refractive index material 40 that acts as a layer that provides hardness and scratch resistance to the window 24. For example, a window 24 that protects a LIDAR system 12 on a vehicle 10 may require a different thickness of the scratch resistant layer of the higher refractive index material 40 than a window 24 that protects a LIDAR system 12 at an office building. In embodiments, the scratch resistant layer of the higher refractive index material 40 that acts as a layer that provides hardness and scratch resistance to the window 24 has a thickness between 500 nm and 50,000 nm, such as a thickness between 500 nm and 10,000 nm, such as a thickness between 2,000 nm and 5,000 nm. In embodiments, the thickness of this scratch resistant layer of higher refractive index material 40 has a thickness of 30% or more, 40% or more, 50% or more, 65% or more, or 85% or more, or 86% or more of the thickness of first layered film 36. Generally speaking, the scratch resistant layer of higher refractive index material 40 that acts as a layer providing hardness and scratch resistance to window 24 will be the portion of first layered film 36 that faces external environment 26, rather than the portion of second layered film 38 that is protected by housing 20, but this may not always be the case.

[0152] As will be described in further detail below, the amount, thickness, number, and materials of the remaining layers of the first layered film 36 and the second layered film 38 can be configured to provide the desired optical properties (transmittance and reflectivity of the desired wavelength) to the window 24, almost independently of the thickness selected for the scratch-resistant layer of the higher refractive index material 40 that serves as the layer that provides hardness and scratch resistance to the window 24. This insensitivity of the optical properties of the overall window 24 to the thickness of the scratch-resistant layer of the higher refractive index material 40 that serves as the layer that provides hardness and scratch resistance to the window 24 occurs when the material has relatively low or negligible optical absorption of electromagnetic radiation at a target wavelength or wavelength range (e.g., 850nm to 950nm, 905nm). For example, Si 3 N 4 Electromagnetic radiation in the wavelength range of 700 nm to 2000 nm is absorbed only negligibly.

[0153] This substantial insensitivity allows the scratch-resistant layer of the higher refractive index material 40 in the first layered film 36 to have a predetermined thickness to meet a specified hardness or scratch resistance requirement. For example, the first layered film 36 for the window 24 at the roof 14 of the vehicle 10 may have different hardness and scratch resistance requirements than the first layered film 36 for the window 24 at the front portion 16 of the vehicle 10, and thus have a different thickness for the scratch-resistant layer of the higher refractive index material 40. This may be achieved without significantly changing the light transmittance and reflectivity properties of the first layered film 36 as a whole.

[0154] The hardness of the first layered film 36 having the scratch resistant layer of the higher refractive index material 40, and thus the hardness of the window 24, can be quantified. In embodiments, the maximum hardness of the window 24 measured at the first layered film 36 having the scratch resistant layer of the higher refractive index material 40 (as measured by a Berkovich Indenter Hardness Test) can be about 8 GPa or greater, about 10 GPa or greater, about 12 GPa or greater, about 14 GPa or greater, about 15 GPa or greater, about 16 GPa or greater, or about 18 GPa or greater at one or more indentation depths of 50 nm to 2000 nm (measured from the end surface 44), and even 2000 nm to 5000 nm. As used herein, the "Berkovich Indenter Hardness Test" includes measuring the hardness of a material on its surface by indenting the surface with a diamond Berkovich indenter. The Berkovich indenter hardness test includes indenting the end surface 44 of the first layered film 36 with a diamond Berkovich indenter to form an indentation depth in the range of about 50 nm to about 2000 nm (or the entire thickness of the first layered film 36); and measuring the maximum hardness from the indentation along the entire indentation depth range or a segment of the indentation depth range (e.g., in the range of about 100 nm to about 600 nm), as commonly used in Oliver, W.C.; Pharr, G.M. An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments, J. Mater. Res., Vol. 7, No. 6, 1992, pp. 1564-1583; and Oliver, W.C.; Pharr, G.M. Measurement of Hardness and Elastic Modulus by Instrument Indentation: Advances in Method Understanding and Improvement. Indentation: Advances in Understanding and Refinements to Methodology, J. Mater. Res., Vol. 19, No. 1, 2004, pp. 3 to 20. When the LIDAR system 12 is used, such as the vehicle 10 (see Figure 1) When used for its intended purpose, this degree of hardness increases the resistance of window 24 to impact damage from sand, pebbles, debris, and other objects encountered. Thus, this degree of hardness reduces or prevents optical scattering of LIDAR system 12 and degradation of performance that would otherwise result from impact damage.

[0155] In an embodiment, at least a portion of the first layered film 36 is disposed between the scratch-resistant layer of the higher refractive index material 40 and the end surface 44. In an embodiment, the first layered film 36 includes a plurality of alternating layers of one or more lower refractive index materials 42 and one or more higher refractive index materials 40 located between the end surface 44 and the scratch-resistant layer. This stack of alternating layers disposed between the scratch-resistant layer and the end surface 44 is described herein as an "optical control layer". In an embodiment, the optical control layer disposed between the scratch-resistant layer and the end surface 44 has a combined thickness greater than or equal to 500 nm (e.g., greater than or equal to 600 nm, greater than or equal to 700 nm, greater than or equal to 800 nm, greater than or equal to 900 nm, greater than or equal to 1000 nm, greater than or equal to 1100 nm, greater than or equal to 1200 nm, greater than or equal to 1300 nm). The amount, composition, and thickness of the optical control layer may be selected to provide the desired anti-reflection performance attributes described herein at an operating wavelength of the LIDAR sensor 12 between 850 nm and 950 nm. In this manner, the second layered film 36 may be designed to provide desirable optical performance characteristics in the visible and / or UV spectrum, as described herein.

[0156] In an embodiment, at least 25% (e.g., at least 26%, at least 27%, at least 28%, at least 29%, at least 30%) of the thickness 46 of the first layered film 36 is disposed between the scratch resistant layer and the end surface 44. It is believed that this depth of the scratch resistant layer within the first layered film 36 contributes to the first layered film 36 having a relatively high nanoindentation hardness (as measured by the Berkovich Indenter Hardness Test) over a relatively large depth range within the first layered film 36. In an embodiment, the first layered film 36 has a nanoindentation hardness greater than or equal to 8 GPa from a depth of 50 nm to a depth of 2000 nm within the first layered film 36. In an embodiment, the first layered film 36 has a nanoindentation hardness greater than or equal to 10 GPa from a depth of 100 nm to a depth of 1000 nm within the first layered film 36. In an embodiment, the first layered film 36 has a nanoindentation hardness greater than or equal to 14 GPa from a depth of 400 nm to a depth of 1000 nm within the first layered film 36. Such hardness values ​​help provide scratch resistance and / or damage resistance against cracks having a relatively wide range of depths.

[0157] Reference Figure 4 and Figure 5, the first layered film 36 has a thickness 46, and the second layered film 38 has a thickness 50. Assuming that the first layered film 36 including a scratch-resistant layer of one or more higher refractive index materials 40 can have a thickness 46 of about 1 μm or more while still providing the transmittance and reflectance properties described herein. In an embodiment, 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 2800 nm to about 5900 nm. The lower limit of about 1 μm is about the minimum thickness 46 that still provides hardness and scratch resistance to the window 24. The upper limit of the thickness 46 is limited by the cost and time required to place the layer of the first layered film 36 on the substrate 30. In addition, the upper limit of the thickness 46 is limited to prevent the first layered film 36 from warping the substrate 30, which depends on the thickness of the substrate 30. The thickness 50 of the second layered film 38 can be any thickness that is considered necessary to impart the desired transmittance and reflectance properties to the window 24. In an embodiment, the thickness 50 of the second layered film 38 is in a range from about 800 nm to about 7000 nm.

[0158] While addressing the issues discussed above in the background by imparting hardness, impact resistance, and scratch resistance to window 24 through a maximized thickness of higher refractive index material 40, the amount, thickness, number, and materials of the layers of first and second layered films 36 and 38 are configured to also provide a relatively high transmittance of infrared radiation between 850 nm and 950 nm through window 24. In an embodiment, the thickness, number, and materials of the alternating layers of first and second layered films 36 and 38 are configured so that window 24 has an average percent transmittance of greater than or equal to 90% (e.g., greater than or equal to 91%, greater than or equal to 92%, greater than or equal to 93%, greater than or equal to 94%, greater than or equal to 95%) calculated over a 50 nm wavelength range of interest centered around a wavelength of 850 nm to 950 nm (e.g., a 20 nm wavelength range of interest centered around 905 nm) for light incident on first and second surfaces 32 and 34 at angles within 15° of a normal to the first and second surfaces 32 and 34.

[0159] In an embodiment, the thickness, number and material of the alternating layers of the first layered film 36 and the second layered film 38 are configured so that the window 24 has an average reflectivity of less than or equal to 4.0% (e.g., less than or equal to 3.5%, less than or equal to 3.0%, less than or equal to 2.5%, less than or equal to 2.0%, less than or equal to 1.5%, less than or equal to 1.0%) calculated within a 50nm wavelength range of interest centered around a wavelength of 850nm to 950nm (e.g., a 20nm wavelength range of interest centered around 905nm) for light incident on the first surface 32 and the second surface 34 at an angle within 15° from the normal to the first surface 32 and the second surface 34. In an embodiment, the number, thickness, number and material of the alternating layers of the first layered film 36 and the second layered film 38 are configured so that the window has an average P-polarization transmittance and an average S-polarization transmittance calculated within a 50nm wavelength range of interest centered on a wavelength of 850nm to 950nm (for example, a 20nm wavelength range of interest centered on 905nm) greater than 85% (greater than or equal to 86%, greater than or equal to 87%, greater than or equal to 88%, greater than or equal to 89%, greater than or equal to 90%, greater than or equal to 91%, greater than or equal to 92%) for light incident on the first surface 32 and the second surface 34 at an angle within 60° to the normal of the first surface 32 and the second surface 34 (for example, at an incident angle of 0° to 60°, 0° to 50°, 0° to 40°, 0° to 30°). As used herein, the term "reflectivity" is defined as the percentage of incident optical power within a given wavelength range that is reflected from a material (eg, window 24, substrate 30, first layered film 36, second layered film 38, or portions thereof).

[0160] In an embodiment, the thickness, number, and material of the alternating layers of the first layered film 36 and the second layered film 38 are configured so that the window 24 has an average percent transmittance of greater than or equal to 95% (e.g., greater than or equal to 95.5%, greater than or equal to 96%, greater than or equal to 96.5%, greater than or equal to 97.5%, greater than or equal to 98%) calculated within a 50 nm wavelength range of interest centered at a wavelength of 850 nm to 950 nm (e.g., a 20 nm wavelength range of interest centered at 905 nm) for light incident normally on the first surface 32 and the second surface 34. As used herein, the terms "transmittance" and "percent transmittance" are used interchangeably and refer to the percentage of incident optical power transmitted through a material (e.g., window 24, substrate 30, first layered film 36, second layered film 38, or portions thereof) within a given wavelength range.

[0161] In an embodiment, the thickness, number and materials of the alternating layers of the first layered film 36 and the second layered film 38 are configured so that the window 24 also (in addition to meeting the optical performance requirements in the infrared described herein) has a desired dark appearance. Figure 1 ), the window 24 may exhibit a CIELAB color space a* value greater than or equal to -6.0 and less than or equal to 6.0 (e.g., greater than or equal to -5.0 and less than or equal to 5.0, greater than or equal to -4.0 and less than or equal to 4.0, greater than or equal to -3.0 and less than or equal to 3.0, greater than or equal to -2.5 and less than or equal to 2.5, greater than or equal to -2.5 and less than or equal to 0) for light having an angle incident on the first surface 32 in the range of 0° to 90°. Window 24 can also exhibit a CIELAB color space b* value of greater than or equal to -6.0 and less than or equal to 6.0 (e.g., greater than or equal to -5.0 and less than or equal to 5.0, greater than or equal to -4.0 and less than or equal to 4.0, greater than or equal to -3.0 and less than or equal to 3.0, greater than or equal to -2.5 and less than or equal to 2.5, greater than or equal to -2.5 and less than or equal to 0) for light having an angle of incidence on first surface 32 in the range of 0° to 90°. Such color space values ​​can be obtained even in embodiments where substrate 30 has a relatively high transmittance (e.g., greater than 90%) and a relatively low reflectance (e.g., less than or equal to 22%) across the visible spectrum.

[0162] In an embodiment, the thickness, number, and materials of the alternating layers of the first layered film 36 and the second layered film 38 are configured such that when viewed from an angle of incidence of less than or equal to 60°, the window 24 has a CIELAB lightness L* value of less than 45 (e.g., less than or equal to 40, less than or equal to 35, less than or equal to 30). In an embodiment, the thickness, number, and materials of the alternating layers of the first layered film 36 and the second layered film 38 are configured such that the window 24 has a CIELAB lightness L* value of less than 20 for light that is normally incident on the first layered film 36 and is reflected. The foregoing combination of CIELAB color space and lightness values ​​indicates that the window 24 has a relatively dark appearance from a variety of angles of incidence.

[0163] The dark appearance of the window 24 can be achieved by incorporating silicon (e.g., in the form of a-Si) or other suitable materials that absorb in the visible spectrum (referred to herein as "absorber layers") in the second layered film 38 as one of the one or more higher refractive index materials 40. Silicon is suitable for the absorber layer because, in addition to having a relatively high refractive index (approximately 4.0 at 905), it has relatively high optical absorption in the ultraviolet range and visible range. The thickness and amount of the silicon layer and other layers of the first layered film 36 and the second layered film 38 can thus provide a window 24 with a low percentage transmittance of electromagnetic radiation in the ultraviolet range and visible range (partly due to the optical absorption rate of amorphous in those wavelength ranges), but a high percentage transmittance in the desired portion of the infrared range. In an embodiment, the second layered film 38 includes one or more silicon (e.g., in the form of a-Si) layers as one of the one or more higher refractive index materials 40, while the first layered film 36 does not include the one or more silicon layers. This structure may be beneficial in that the silicon is located only behind the substrate 30 and is therefore protected from the external environment 26. Thus, the nanoindentation hardness values ​​described herein may be obtained by incorporating the scratch resistant layer into the first layered film 36, while the dark appearance may be obtained by incorporating the silicon into the second layered film 38.

[0164] In an embodiment, the silicon material used to form at least one of the one or more higher refractive index materials 40 layers is modified to facilitate relatively high optical transmittance within a 50 nm wavelength of interest centered around wavelengths of 850 nm to 950 nm. In particular, it has been found that the silicon material (or other suitable material that absorbs more radiation in the visible spectrum in a higher amount than other higher refractive index materials 40 described herein) should be modified to facilitate relatively high optical transmittance within a 50 nm wavelength of interest centered around wavelengths of 850 nm to 950 nm. In particular, it has been found that the silicon material (or other suitable material that absorbs more radiation in the visible spectrum in a higher amount than other higher refractive index materials 40 described herein) should be modified to facilitate relatively high optical transmittance within a 50 nm wavelength of interest centered around wavelengths of 850 nm to 950 nm. In some embodiments, the range of wavelengths may be between 890 nm to 910 nm, and in various embodiments may be approximately 890 nm, 891 nm, 892 nm, 893 nm, 894 nm, 895 nm, 896 nm, 897 nm, 898 nm, 899 nm, 900 nm, 901 nm, 902 nm, 903 nm, 904 nm, 905 nm, 906 nm, 907 nm, 008 nm, 909 nm, and 910 nm, and any and all ranges including any of these values ​​as endpoints, wherein the wavelength up to the peak operating wavelength is associated with at least one of the emitter and the sensor 18) has an extinction coefficient of less than or equal to 0.01 (e.g., less than or equal to 0.009, less than or equal to 0.008, less than or equal to 0.007, less than or equal to 0.005, less than or equal to 0.004, less than or equal to 0.0035, less than or equal to 0.0030, less than or equal to 0.0025, less than or equal to 0.0020, less than or equal to 0.0015, less than or equal to 0.0010). In an embodiment, it is preferred that the silicon material has an extinction coefficient of less than .005 at this wavelength, while exhibiting a relatively high extinction coefficient (e.g., greater than or equal to .06, greater than or equal to 0.07, greater than or equal to 0.08, greater than or equal to 0.09, greater than or equal to 0.1) throughout the visible spectrum. This low extinction coefficient in the 50 nm wavelength range of interest and relatively high extinction coefficient throughout the visible spectrum facilitates the addition of silicon in sufficient amounts to reduce visible light transmission to the ranges described herein without significantly affecting transmittance in the wavelength range of interest.

[0165] In an embodiment, the alternating layers of the second layered film 38 formed of silicon have a combined thickness greater than or equal to 250 nm (e.g., greater than or equal to 300 nm, greater than or equal to 325 nm, greater than or equal to 350 nm, greater than or equal to 375 nm, greater than or equal to 400 nm, greater than or equal to 450 nm, greater than or equal to 500 nm, greater than or equal to 550 nm, greater than or equal to 600 nm, greater than or equal to 650 nm, greater than or equal to 700 nm). In an embodiment, the combined thickness of the silicon layers in the second layered film constitutes at least 20% (e.g., at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%) of the thickness 50 of the second layered film 50. Applicants have discovered that this thickness of silicon sufficiently absorbs visible light such that window 24 has an average percent transmittance of less than 5% (e.g., less than or equal to 4.5%, less than or equal to 4.0%, less than or equal to 3.5%, less than or equal to 3.0%, less than or equal to 2.5%, less than or equal to 2.0%, less than or equal to 1.5%, less than or equal to 1.0%, less than or equal to 0.9%, less than or equal to 0.8%, less than or equal to 0.7%, less than or equal to 0.6%, less than or equal to 0.5%, less than or equal to 0.4%, less than or equal to 0.3%, less than or equal to 0.2%, less than or equal to 0.1%) calculated from 400 nm to 700 nm for light incident on first surface 32 and second surface 34 at angles within 15° of the normal to first surface 32 and second surface 34. Thus, reflected radiation 28 (see Figure 2 ) will not reach the transmitter and sensor 18, thereby improving the signal-to-noise ratio of the LIDAR system 12.

[0166] In an embodiment, the second layered film 36 includes two or more layers formed of silicon. In an embodiment, at least one of the two or more layers formed of silicon includes a thickness greater than or equal to 150 nm (e.g., greater than or equal to 160 nm, greater than or equal to 170 nm, greater than or equal to 180 nm, greater than or equal to 190 nm, greater than or equal to 200 nm). In an embodiment, at least two but less than all of the two or more layers formed of silicon in the second layered film 36 include a thickness greater than or equal to 150 nm. In an embodiment, at least seven (7) alternating layers of the second layered film 38 are disposed between one of the silicon layers having a thickness of 150 nm or greater and the second surface 34. In an embodiment, the silicon layer included in the second layered film 38 includes a thickness of less than or equal to 70 nm (e.g., less than or equal to 65 nm, less than or equal to 60 nm, less than or equal to 55 nm, less than or equal to 50 nm, less than or equal to 30 nm, less than or equal to 25 nm, less than or equal to 20 nm) including a thickness less than 150 nm from the second surface 34. It is believed that this separation between the substrate 30 and the relatively thick silicon layer helps reduce reflectivity in the visible spectrum.

[0167] In an embodiment, the alternating layers of the first layered film 36 and the second layered film 38 are constructed to achieve a relatively low average reflectivity in the visible spectrum. For example, in an embodiment, the window includes an average reflectivity of less than or equal to 10% (e.g., less than or equal to 9%, less than or equal to 8%, less than or equal to 7%) calculated over a wavelength range of 400 nm to 700 nm. This low reflectivity beneficially prevents the window 24 from being damaged by the external environment 26 (see Figure 1 ) has a colored appearance when observed and contributes to the CIE color space a* and b* and lightness L* values ​​described in this article.

[0168] In an embodiment, to limit the reflectivity in the visible spectrum of the window, the silicon layer of the second layered film 38 closest to the substrate 30 is the narrowest silicon layer in the second layered film 38. That is, among the layers of the second layered film 38 in which the one or more higher refractive index materials 40 are silicon, the layer closest to the substrate 30 comprises the smallest thickness. In an embodiment, the nearest silicon layer in the second layered film 38 comprises a thickness of less than or equal to 15 nm (e.g., less than or equal to 10 nm, less than or equal to 8 nm, less than or equal to 7 nm, less than or equal to 6 nm, less than or equal to 5 nm, less than or equal to 4 nm, less than or equal to 3 nm, less than or equal to 2 nm). Applicants have found that this structure beneficially prevents the silicon-containing layer in the second layered film 38 from causing tinted reflectivity while still contributing to the relatively low visible light transmittance values ​​described herein.

[0169] In an embodiment, the layer of the one or more higher refractive index materials 40 closest to the substrate 30 in the second layered film 38 is not silicon. In an embodiment, for example, the layer of the one or more higher refractive index materials 40 closest to the substrate 30 may be made of the same higher refractive index material (e.g., SiN) used in the first layered film. x 、SiO x N Y 、Si 3 N 4 ). In an embodiment, the layer of the one or more higher refractive index materials 40 in the second layered film 38 closest to the substrate 30 is the only higher refractive index layer that is not composed of silicon. Without wishing to be bound by theory, applicants believe that when silicon is incorporated into the second layered film 38, especially when the silicon layer contained in the second layered film 38 includes a thickness greater than or equal to 8 nm, this structure can help reduce reflectivity in the visible spectrum.

[0170] The layers of first and second layered films 36, 38 (i.e., layers of higher refractive index material 40 and lower refractive index material 42) may be formed by any known method in the art, including discrete deposition or continuous deposition processes. In one or more embodiments, only continuous deposition processes may be used, or alternatively, only discrete deposition processes may be used to form the layers.

[0171] Examples

[0172] The following example is a modeled example using computer-assisted modeling to show how the amount, thickness, number and materials of the layers of the first layered film 36 and the second layered film 38 can be configured so that the window 24 has a desired average percent transmittance and average percent reflectivity that varies with the wavelength and incident angle of the incident electromagnetic radiation.

[0173] Example 1 - The window 24 of Example 1 includes a first layered film 36 and a second layered film 38. The second layered film 38 includes FIG. 6A to FIG. 6BA layer of silicon material is represented as "low-k" material in FIG. The low-k material is supported amorphous silicon and is formed by a method similar to existing materials, but the process conditions are changed during the deposition process. As shown, over the entire wavelength range of 350nm to 1000nm, the low-k material exhibits an extinction coefficient that is shifted downward from the extinction coefficient of certain existing silicon materials. Thus, the low-k material exhibits an extinction coefficient less than or equal to 0.01 (e.g., less than or equal to 0.004 in this specific example) over the entire wavelength range of 850nm to 950nm. Over the entire wavelength range of 890nm to 910nm, the low-k silicon exhibits an extinction coefficient less than 0.002 (approximately .0016 at 905nm). This is a reduction of more than an order of magnitude compared to existing silicon materials, which have an extinction coefficient greater than or equal to .044 over the entire wavelength range of 850nm to 950nm. In addition, as Fig. 6A As shown in , the extinction coefficient of the low-k material is comparable to that of existing silicon materials (less than an order of magnitude) in the wavelength range of 400 nm to 700 nm. From 400 nm to 700 nm, the low-k material exhibits an extinction coefficient ranging from 0.078 to 1.92. Such relatively high extinction coefficients within the visible spectrum enable the incorporation of low-k silicon materials in sufficient amounts to absorb visible light and provide the dark opaque appearance described herein, while the relatively low extinction coefficient allows such amounts to be introduced without adversely affecting the transmittance in the 50 nm wavelength range of interest to a significant degree.

[0174] The window 24 of Example 1 includes a first layered film 36 disposed on a first surface 32 of a substrate 30 of aluminosilicate glass (Corning code 2320). The window 24 also includes a second layered film 38 disposed on a second surface 34 of the substrate 30. The first layered film 36 includes SiO as the lower refractive index material 42. 2 and thirty-three (33) alternating layers of SiN as the higher refractive index material 40. Layer 24 is a scratch resistant layer of the higher refractive index material 40 having a thickness of 2000 nm. Layers 1 to 23 are optical control layers separating the scratch resistant layer from the end surface 44 having a combined thickness of 1307.01 nm. Layers 25 to 33 are refractive index matching layers separating the scratch resistant layer from the first surface 32 and having a combined thickness of 338.45 nm. In this example, the scratch resistant layer constitutes 54.86% of the thickness of the first layered film 36.

[0175] The second layered film 38 includes twenty-three (23) alternating layers of lower refractive index material 42 and higher refractive index material 40. In this example, the lower refractive index material 42 is SiO 2, while the higher refractive index material 40 is a combination of SiN and Si. As shown, layers 35, 37, 39 and 41 (the four layers of higher refractive index material 40 closest to substrate 30) are SiN, while the remaining layers of higher refractive index material 40 are low-k Si. Layer 43 (the Si layer closest to substrate 30) is the narrowest Si layer with a thickness of 12.04 nm. The combined thickness of the silicon layers is 708.4 nm, which constitutes 46.6% of the total thickness of the second layered film 38.

[0176] The thickness of the layers of the first layered film 36 and the second layered film 38 are generally configured as described in Table 1 below and are used to calculate Figures 7 to 12 The transmittance, reflectance, CIELAB color space and reflected lightness value and nanoindentation hardness value described in it.

[0177]

[0178]

[0179]

[0180] Figure 7 is a graph of the modeled light transmittance of the window 24 according to Example 1 for light incident on the window 24 at an incident angle of 15° over the entire spectral range of 850 nm to 950 nm. Figure 7 As shown in , the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 1 has a percent transmittance greater than 93% for light incident on the first surface 32 or the second surface 34 at an incident angle of less than 15° over the entire wavelength range extending from 850nm to 950nm. In fact, over the entire wavelength range of 850nm to 950nm, the window exhibits a transmittance greater than 93% for light at an incident angle of 15°. Over the entire wavelength range of 860nm to 950nm, the transmittance is greater than 95%. At 905nm, the transmittance is about 97%. As shown in FIG. Figure 8 As shown in FIG. 1 , the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 1 has an average P-polarized light transmittance and an average S-polarized light transmittance calculated within the wavelength range of interest of 850nm to 950nm for light incident on the first surface and the second surface at an angle within 60° to the normal of the first surface and the second surface, which is greater than 89%. In the entire wavelength range of 890nm to 910nm, the S and P polarized light transmittances are greater than 91%.

[0181] like Fig. 9As shown in FIG. 1 , the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 1 has a percent reflectivity of less than 4% from the end surface 44 of the first layered film 36 and the end surface 48 of the second layered film 38 for light incident on the substrate 300 at an incident angle of 15° in the approximate wavelength range of 850nm to 950nm. The reflectivity from the end surface 44 is comparable to the reflectivity from the end surface 48, which is due to the first layered film 36 and the second layered film 38 being composed of materials with relatively low absorptivity in the reference wavelength range. As shown, the reflectivity is less than 1.6% over the entire wavelength range of 860nm to 950nm. In the wavelength range of 850nm to 950nm, the reflectivity has a minimum value of approximately less than 1.0% (approximately 0.8%) at a wavelength of 925nm.

[0182] like Fig.10 As shown in , the amount, thickness, number and materials of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 1 has a transmittance of less than 12% in the entire visible spectrum for light incident on the window 24 at an angle of incidence of less than or equal to 15°. From 400nm to 650nm, the transmittance in the visible spectrum is less than 3%. For wavelengths less than 600nm, the transmittance in the visible spectrum is less than 0.2%. It is believed that these low transmittance values ​​are due in part to the absorptivity of the silicon layer in the second layered film 38 to visible light. The window 24 exhibits an average transmittance of less than or equal to 5.0% in the wavelength range of 400nm to 700nm.

[0183] like Fig.11A and Fig. 11B As shown in , the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that when viewed from the end surface 44 of the first layered film, the window 24 of Example 1 has a dark appearance. FIG. 11 provides simulated CIELAB reflection color data of Example 1 for light reflected from the end surface 44. The color of the reflected light can be characterized using CIELAB color coordinates. The a* axis in the color space represents the green-red color component, where negative a* values ​​correspond to green and positive a* values ​​correspond to red. The b* axis in the color space represents the blue-yellow component, where negative b* values ​​correspond to blue and positive b* values ​​correspond to yellow. The closer the a* and b* values ​​are to the origin, the more neutral the reflected light will appear to the observer. The CIELAB a* and b* values ​​are generated by simulating light sources at multiple different incident angles ranging from 0° to 90°. As shown, the a* value ranges from about 0 to about 4.5, while the b* value ranges from about -0.8 to about 0.8. This indicates that when the incident light from the external environment 26 (see Figure 1 ) when observed, the window 24 according to Example 1 has a neutral appearance.

[0184] Fig. 11B The modeled CIELAB lightness L* values ​​of the reflection are plotted as a function of the incident angle on the end surface 44. As shown, for an incident angle of less than or equal to 60°, the lightness L* value is less than or equal to 35. For an incident angle of less than or equal to 50°, the lightness L* value is less than or equal to 25. For an incident angle of less than or equal to 35°, the lightness L* value is less than or equal to 20. This indicates that when the incident angle from the external environment 26 (see Figure 1 ) when observed, the window 24 according to Example 1 has a dark appearance.

[0185] Fig.12 Nanoindentation hardness as a function of depth for samples constructed according to Example 1 herein is shown. The hardness values ​​are simulated as if the side of the first layered film 36 were subjected to the Berkovich indenter hardness test described herein. The samples were measured over a depth range of 50 nm to 1000 nm. Fig.12 As depicted in FIG. 1 , the sample exhibits a maximum hardness greater than 15.5 GPa at a depth of approximately 750 nm. Without wishing to be bound by theory, it is believed that the maximum hardness is located above the scratch resistant layer due to the stress field generated by the indenter propagating beneath the scratch resistant layer once a depth of 1050 nm is reached. Fig.12 As shown in , the window 24 according to Example 1 exhibits a nanoindentation hardness of greater than 8 GPa in a depth range of 50 nm to 1000 nm. The window 24 according to Example 1 also exhibits a nanoindentation hardness of greater than 10 GPa in a depth range of 100 nm to 1000 nm. The window 24 according to Example 1 also exhibits a nanoindentation hardness of greater than 12 GPa in a depth range of 200 nm to 1000 nm. The window 24 according to Example 1 also exhibits a nanoindentation hardness of greater than 14 GPa in a depth range of 400 nm to 1000 nm. The window 24 according to Example 1 also exhibits a nanoindentation hardness of greater than 15 GPa in a depth range of 600 nm to 1000 nm. This shows that the example provides advantageous scratch resistance / damage resistance for various applications.

[0186] ***

[0187] Embodiments of the present invention may be further understood in view of the following information.

[0188] In an embodiment, one of the first layered film 36 and the second layered film 38 includes one or more layers formed of a transparent conductive oxide ("transparent conductive oxide, TCO") material. The TCO material may replace one of the layers of the higher refractive index material 40. The TCO material layer may be communicatively (e.g., conductively) coupled to a power source (not depicted) for heating the window 24. This heating is beneficial for one or more LiDAR systems 12 to operate in a low temperature environment. The TCO material may be selected from suitable optically transparent and conductive materials, such as indium tin oxide ("indium tin oxide, ITO"), aluminum-doped zinc oxide ("aluminum-doped zinc oxide, AZO"), and indium-doped cadmium oxide. In an embodiment, ITO is preferred due to its excellent heat resistance over certain other existing TCO materials.

[0189] In an embodiment, the TCO material layer is disposed in the second layered film 38. In some embodiments, the TCO material layer is disposed closer to the end surface 48 than the absorber layer (e.g., Si layer) located in the second layered film 38, such that the absorber layer is disposed between the TCO material layer and the substrate 30. This configuration beneficially facilitates the addition of TCO material without affecting the dark opaque appearance of the window 24 described herein. In an aspect, the TCO material layer is disposed between the lower refractive index material layers 42 due to its intermediate refractive index. However, embodiments are contemplated in which the TCO material layer is disposed adjacent to the substrate 30 (e.g., disposed between the substrate 30 and one of the first layered film 36 and the second layered film 38). In an aspect, the second layered film 38 includes a single TCO material (e.g., ITO) layer, wherein the single TCO material layer is the higher refractive index material 40 layer farthest from the substrate 30, wherein multiple absorber (e.g., Si) layers (and / or other higher refractive index material 40 layers) are disposed between the TCO material layer and the substrate 30.

[0190] The thickness of the TCO material layers may be selected based on a variety of factors, including the desired sheet resistance necessary to achieve heating of the window 24 and the desired optical properties of the window 24. In an embodiment, each of the TCO material layers has a thickness less than or equal to 50 nm (e.g., less than or equal to 45 nm, less than or equal to 40 nm, less than or equal to 35 nm, less than or equal to 30 nm, less than or equal to 25 nm, less than or equal to 20 nm, and less than or equal to 30 nm) and an optical extinction coefficient less than or equal to .05 (e.g., less than or equal to .04) at 905 nm. Embodiments in which the TCO material layers have a thickness greater than 50 nm are also contemplated. When the extinction coefficient is less than .05 over the entire spectral range of 840 nm to 1020 nm, absorption in the wavelength range of interest is beneficially minimized to maintain the excellent transmission properties of the layered films described herein. That is, the TCO material layers do not significantly affect the transmission properties of the window 24 in the wavelength range of interest while providing sufficient sheet resistance to facilitate heating. ITO has been found to be a suitable TCO material, providing a suitable sheet resistance for heating when deposited at a thickness of 20-30 nm, while having an extinction coefficient of less than .05 in the wavelength range of interest.

[0191] Example 2 - The window 24 of Example 2 includes a first layered film 36 and a second layered film 38. The second layered film 38 includes FIG. 6A to FIG. 6B A layer of silicon material described as a "low-k" material. The window 24 of Example 2 includes a first layered film 36 located above the first surface 32 of the substrate 30. The window 24 also includes a second layered film 38 located above the second surface 34 of the substrate 30. In Example 2, the substrate 30 is a laminated material described in U.S. Provisional Patent Application No. 63 / 349,764, entitled "Laminate Windows for Infrared Sensing Systems," filed on June 7, 2022, which is incorporated herein by reference in its entirety. Specifically, the substrate 30 includes a first glass ply (as an outer ply away from the radiation emitter and sensor 18), an interlayer of an optically clear adhesive, and a second (inner) glass ply 320, the first glass ply being a 2.85 mm thick untempered aluminosilicate glass ply, the second (inner) glass ply 320 being a 1 mm thick chemically tempered aluminosilicate glass ply.

[0192] The first layered film 36 includes SiO as the lower refractive index material 42. 2and thirty-one (31) alternating layers of SiN as the higher refractive index material 40. Layer 22 is a scratch resistant layer of the higher refractive index material 40 having a thickness of 2038.98 nm. Layers 1 to 21 are optical control layers separating the scratch resistant layer from the end surface 44 having a combined thickness of 1352 nm. Layers 23 to 31 are index matching layers separating the scratch resistant layer from the first surface 32 and having a combined thickness of 380.87 nm. In this example, the scratch resistant layer constitutes 54.06% of the thickness of the first layered film 36.

[0193] The second layered film 38 includes twenty-three (23) alternating layers of lower refractive index material 42 and higher refractive index material 40. In this example, the lower refractive index material 42 is SiO 2 , while the higher refractive index material 40 is a combination of SiN, Si and ITO. As shown, layers 35, 37, 39 and 41 (the four layers of the higher refractive index material 40 closest to the substrate 30) are SiN, while the remaining layers of the higher refractive index material 40 are low-k Si and ITO. Layer 43 (the Si layer closest to the substrate 30) is the narrowest Si layer with a thickness of 12.22nm. The combined thickness of the silicon layers is 485.01nm, which constitutes 35.9% of the total thickness of the second layered film 38. Layer 55 is a layer of TCO material. As shown, the TCO layer has a refractive index of 1.72 at 905nm, which is less than half of the refractive index of the closest layer of the higher refractive index material 40. The thickness of the TCO layer is 22nm to provide the required sheet resistance for heating purposes. The TCO is beneficially located behind the silicon layer (closer to the end surface 48). As described herein, this layout of the TCO layer is beneficial because visible light is absorbed by the silicon layer and therefore does not reach the TCO layer. Adding a TCO layer in this manner beneficially prevents the TCO layer from altering the appearance of the window 24 described herein while also increasing functionality.

[0194] The thickness of the layers of the first layered film 36 and the second layered film 38 are generally configured as described in Table 2 below and are used to calculate Figures 13 to 15 The transmittance, reflectance, CIELAB color space and lightness value of the reflectance value described in.

[0195]

[0196]

[0197]

[0198] Fig.13 is a graph of the modeled light transmittance of the window 24 according to Example 2 for light incident on the window 24 at an incident angle of 15° and an incident angle of 60° over the entire spectral range of 350 nm to 1500 nm. Fig.13As shown in , the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 2 has a percent transmittance greater than 95% for light incident on the first surface 32 or the second surface 34 at an incident angle of less than 15° over the entire wavelength range extending from 850nm to 950nm. In fact, over the entire wavelength range of 850nm to 950nm, the window exhibits a transmittance greater than 96% for light at an incident angle of 15°. In addition, as Fig.13 As shown in the figure, the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 2 has a polarization average transmittance greater than 89% calculated within the wavelength range of interest of 850nm to 950nm for light incident on the first surface and the second surface at an angle within 60° to the normal of the first surface and the second surface.

[0199] like Fig.13 As further shown in , the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 2 has a transmittance of less than 10% in the entire visible spectrum for light incident on the window 24 (end surface 44) at an incident angle of less than or equal to 15°. The window 24 according to Example 2 exhibits an average transmittance of less than 2% from 400nm to 700nm at normal incidence. These low transmittance values ​​are due in part to the absorptivity of the silicon layer in the second layered film 38 to visible light. As shown in FIG. Fig.13 As further shown in FIG. 1 , the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 2 has a transmittance of less than 13% in the entire visible spectrum for light incident on the window 24 (end surface 44) at an incident angle less than or equal to 60°.

[0200] like Fig.14 As shown in FIG. 1 , the amount, thickness, number, and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 2 has a polarization average percent reflectivity of less than 1% from the end surface 44 of the first layered film 36 for light incident on the substrate 30 at an incident angle of 15° in the approximate wavelength range of 850 nm to 950 nm. The reflectivity from the end surface 44 is comparable to the reflectivity from the end surface 48 because the first layered film 36 and the second layered film 38 are composed of materials with relatively low absorptivity in the reference wavelength range.

[0201] like Fig.15 As shown in , the amount, thickness, number, and materials of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 2 has a dark appearance when viewed from the end surface 44 of the first layered film. Fig.15The simulated CIELAB reflectance color data of Example 2 is provided for light reflected from the end surface 44. The CIELAB a* and b* values ​​are generated by simulating a light source at a plurality of different incident angles ranging from 0° to 90°. As shown, the a* values ​​range from about -1.2 to about 0.8, and the b* values ​​range from about -0.3 to about 6. This indicates that when the light from the external environment 26 (see Figure 1 ) when observed, the window 24 according to Example 2 has a neutral appearance.

[0202] It has been found that in the second layered film 38, separating the silicon layer from the end surface 48 with one or more layers of another higher refractive index material 40 layer can provide improved anti-reflection performance in the 50 nm wavelength range of interest, especially from the end surface 48. Therefore, in an embodiment, the innermost silicon layer of the second layered film 38 farthest from the substrate 30 (closest to the end surface 48) can be separated from the end surface 48 by an "inner AR stack" that includes at least one layer of a lower refractive index material 42 and at least one layer of a higher refractive index material 40 that is not silicon (e.g., SiN or other suitable higher refractive index material). When an inner AR stack is included, the inner AR stack can also be disposed between the innermost silicon layer and the end surface 48. Although the design according to Example 2 herein exhibits advantageous performance, it has been found that the addition of the inner AR stack reduces the reflectivity of the window 24 in the 50 nm wavelength range of interest, especially at lower incident angles of less than or equal to 15° on the end surface 48. For light incident on the second layered film 38 at an angle of incidence of less than or equal to 15°, the inner AR stack can achieve a maximum reflectivity of less than or equal to 0.5% over the entire wavelength range of 890 nm to 950 nm.

[0203] In an embodiment, the inner AR stack of the second layered film 38 includes at least 2 layers (e.g., at least 3 layers, at least 4 layers) of a higher refractive index material 40 other than silicon or a TCO layer, such that the inner AR stack includes at least 4 (e.g., at least 6, at least 8) alternating layers of a lower refractive index material 42 and a higher refractive index material 40. In addition, a TCO layer (such as the TCO layer described herein with respect to Example 2) may be incorporated between the inner AR stack and the end surface 48 to facilitate heating without destroying the appearance of the window 24, as described herein with respect to Example 2.

[0204] Example 3 - The window 24 of Example 3 includes a first layered film 36 and a second layered film 38. The second layered film 38 includes FIG. 6A to FIG. 6BA layer of silicon material described as a "low-k" material. The window 24 of Example 3 includes a first layered film 36 located above the first surface 32 of the substrate 30. The window 24 also includes a second layered film 38 located above the second surface 34 of the substrate 30. In Example 3, the substrate 30 is a laminated material described in U.S. Provisional Patent Application No. 63 / 349,764, entitled "Laminate Windows for Infrared Sensing Systems," filed on June 7, 2022, which is incorporated herein by reference in its entirety. Specifically, the substrate 30 includes a first glass ply (as an outer ply away from the radiation emitter and sensor 18), an interlayer of an optically clear adhesive, and a second (inner) glass ply 320, the first glass ply being a 2.85 mm thick untempered aluminosilicate glass ply, the second (inner) glass ply 320 being a 1 mm thick chemically tempered aluminosilicate glass ply.

[0205] The first layered film 36 includes SiO as the lower refractive index material 42. 2 and thirty-one (31) alternating layers of SiN as the higher refractive index material 40. Layer 22 is a scratch resistant layer of the higher refractive index material 40 having a thickness of 2038.98 nm. Layers 1-21 are optical control layers separating the scratch resistant layer from the end surface 44 having a combined thickness of 1226.23 nm. Layers 23-31 are refractive index matching layers separating the scratch resistant layer from the first surface 32 and having a combined thickness of 355.85 nm. In this example, the scratch resistant layer constitutes 55.83% of the thickness of the first layered film 36.

[0206] The second layered film 38 includes thirty-three (33) alternating layers of lower refractive index material 42 and higher refractive index material 40. In this example, the lower refractive index material 42 is SiO 2 , and the higher refractive index material 40 is a combination of SiN, Si and ITO. As shown, layers 35, 37 and 39 (the three layers of higher refractive index material 40 closest to substrate 30) are SiN. Layers 41, 43, 45, 47, 49, 51, 53, 55 and 57 are silicon layers. Layer 41 (the Si layer closest to substrate 30) is the narrowest Si layer with a thickness of 9.55nm. The combined thickness of the silicon layers is 742.34nm, which constitutes 21.8% of the total thickness of the second layered film 38. Layer 65 is a TCO material layer. As shown, the TCO layer has a refractive index of 1.54. The TCO is beneficially located behind the silicon layer (closer to the end surface 48). As described herein, this layout of the TCO layer is beneficial because visible light is absorbed by the silicon layer and therefore does not reach the TCO layer. Adding the TCO layer in this manner beneficially prevents the TCO layer from changing the appearance of the window 24 described herein, while also increasing functionality.

[0207] In Example 3, layers 58 to 64 separate the silicon layer from the TCO layer and represent an inner AR stack, wherein the inner AR stack includes SiN as the higher refractive index material. As shown, three SiN layers separate the innermost silicon layer from the end surface 48. The inner AR stack includes seven layers having a combined thickness of 1251.11 nm, which accounts for 36.82% of the total thickness of the second layered film 38. As shown, the inner AR stack includes two opposing SiO layers having a thickness greater than 350 nm. 2 Layers (layers 58 and 62). Such thick layers help provide particularly low reflectivity on the inside of window 24, thereby preventing back reflections of emitted radiation from causing signal noise.

[0208] The thickness of the layers of the first layered film 36 and the second layered film 38 in Example 3 are generally configured as described in Table 3 below and are used to calculate Figures 16 to 18 The transmittance, reflectance, CIELAB color space and lightness value described in.

[0209]

[0210]

[0211]

[0212] Fig.16 is a graph of the modeled transmittance (polarization average) of the window 24 according to Example 3 for light incident on the window 24 at an angle of incidence of 15° and an angle of incidence of 60° over the entire spectral range of 350 nm to 1500 nm. Fig.16 As shown in FIG. 3 , the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 3 has a percent transmittance greater than 95% for light incident on the first surface 32 or the second surface 34 at an incident angle of less than 15° over the entire wavelength range extending from 850 nm to 950 nm. In fact, over the entire wavelength range from 850 nm to 950 nm, the window exhibits a transmittance greater than 96% for light at an incident angle of 15°.

[0213] In addition, if Fig.16 As shown in , the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 3 has a polarization average transmittance greater than 85% calculated in the wavelength range of interest of 850nm to 950nm for light incident on the first surface and the second surface at an angle within 60° from the normal of the first surface and the second surface. In addition, as Fig.16As shown in , the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 3 has a transmittance of less than 5% in the entire visible spectrum for light incident on the window 24 (end surface 44) at an incident angle of less than or equal to 60°. The window 24 according to Example 3 exhibits an average transmittance of less than 0.1% from 400nm to 700nm at normal incidence. The reduction in visible light transmittance compared to Example 3 is due to the greater number of silicon layers and the combined thickness of the silicon layers.

[0214] like Fig.17A As shown in FIG. 3 , the amount, thickness, number, and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 3 has a polarization average percent reflectivity of less than 1% from the end surface 44 of the first layered film 36 for light incident on the substrate 30 at an incident angle of 15° within the approximate wavelength range of 850 nm to 950 nm on either of the end surfaces 44 and 48. Fig. 17B As shown in FIG. 1 , the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 3 has an average percent reflectivity (polarization average) of less than 0.5% leaving both the end surface 44 of the first layered film 36 and the end surface 48 of the second layered film 38 for light incident at an incident angle of 15° within the approximate wavelength range of 890 nm to 950 nm, which is also lower than the average percent reflectivity of Example 2 due to the addition of the internal AR stack.

[0215] like Fig.18 As shown in , the amount, thickness, number, and materials of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 3 has a dark appearance when viewed from the end surface 44 of the first layered film. Fig.18 The simulated CIELAB reflectance color data of Example 3 is provided for light reflected from the end surface 44. The CIELAB a* and b* values ​​are generated by simulating a light source at a plurality of different incident angles ranging from 0° to 90°. As shown, the a* values ​​range from about -2.3 to about 4.5, while the b* values ​​range from about -1.65 to about 0. This indicates that when the light from the external environment 26 (see Figure 1 ), the window 24 according to Example 3 has a neutral appearance when viewed at 40°. The windows according to Examples 2 and 3 also exhibit L* values ​​less than 26 for light incident on the end surface 44 at incident angles ranging from 0° to 45°, thereby promoting the perceived dark color of the window 24 at those viewing angles.

[0216] ***

[0217] An alternative embodiment may be formed by modifying Example 3 by increasing the number of Si layers in the second layered film 38 and reducing the relative number of layers in the inner AR stack. Such changes may advantageously flatten the reflection spectrum from the sides of the end surface 44 while still exhibiting low reflectivity from light incident on the end surface 48 as compared to Example 3. In particular, it has been found that providing at least 10 (e.g., 10, 11, 12, 13, 14, or even 15) Si layers in the second layered film while reducing the size of the inner AR stack to include less than 3 (i.e., 1 or 2) of the higher refractive index material 40 layers between the Si layer and the TCO layer beneficially produces a flatter reflection spectrum around the 50 nm wavelength range of interest. This flatter reflection spectrum advantageously increases manufacturing tolerances and provides greater production throughput when achieving high transmittance and low reflectivity performance in the 50 nm wavelength range of interest described herein. Windows including this greater number of silicon layers and a reduced internal AR stack can achieve a reflectance range (max-min) of less than .05% for light in the wavelength range of 850nm to 970nm incident on the end surface 44 at an incident angle of 15°. Such embodiments can also achieve a reflectance range (max-min) of less than 3% for light in the wavelength range of 850nm to 950nm incident on the end surface 44 at an incident angle of 60°.

[0218] Example 4 - The window 24 of Example 4 includes a first layered film 36 and a second layered film 38. The second layered film 38 includes a silicon material layer described herein as a "low-k" material. The window 24 of Example 4 includes a first layered film 36 located above a first surface 32 of a substrate 30. The window 24 also includes a second layered film 38 located above a second surface 34 of the substrate 30. In Example 4, the substrate 30 is of the same construction as in Example 3.

[0219] The first layered film 36 includes SiO as the lower refractive index material 42. 2 and twenty-seven (27) alternating layers of SiN as the higher refractive index material 40. Layer 20 is a scratch resistant layer of the higher refractive index material 40 having a thickness of 2055.93 nm. Layers 1 to 19 are optical control layers separating the scratch resistant layer from the end surface 44 having a combined thickness of 1108.71 nm. Layers 21 to 27 are refractive index matching layers separating the scratch resistant layer from the first surface 32 and having a combined thickness of 222.41 nm. In this example, the scratch resistant layer constitutes 60.7% of the thickness of the first layered film 36.

[0220] The second layered film 38 includes thirty-three (33) alternating layers of lower refractive index material 42 and higher refractive index material 40. In this example, the lower refractive index material 42 is SiO 2, while the higher refractive index material 40 is a combination of SiN, Si and ITO. As shown, layers 29 and 31 (the two layers of the higher refractive index material 40 closest to the substrate 30) are SiN. Layers 33, 35, 37, 39, 41, 43, 45, 47, 49, 41, 43 and 55 are silicon layers. Therefore, Example 4 contains a greater number of silicon layers than Example 3. Layer 33 (the Si layer closest to the substrate 30) is the narrowest Si layer with a thickness of 8.05nm. The combined thickness of the silicon layers is 522.03nm, which constitutes 31.7% of the total thickness of the second layered film 38. Thus, Example 4 contains a greater number of silicon layers than Example 3. Although the combined thickness of the silicon layers is smaller in Example 4 than in Example 3, the combined thickness constitutes a greater percentage (greater than 30%) of the total thickness of the second layered film. Layer 59 is a TCO material layer. As shown, the TCO layer has a refractive index of 1.54. The TCO is advantageously located behind the silicon layer (closer to the end surface 48).

[0221] In Example 4, layers 56-58 separate the silicon layer from the TCO layer and represent an inner AR stack, wherein the inner AR stack includes SiN as the higher refractive index material. As shown, one SiN layer separates the innermost silicon layer from the end surface 48. The inner AR stack includes three layers having a combined thickness of 109.28 nm, which accounts for 6.62% of the total thickness of the second layered film 38. Therefore, the inner AR stack in Example 4 is much smaller than in Example 3 and constitutes a smaller portion (less than 10%) of the entire thickness of the second layered film 38. In addition, the inner AR stack in Example 4 includes two relatively thin SiO layers having thicknesses of 10 nm and 20 nm, respectively. 2 Without wishing to be bound by theory, the thinner inner AR stack in Example 4 is compensated by the additional Si layer, which helps to achieve the favorable reflectivity performance of light exiting from the end surface 48.

[0222] The thickness of the layers of the first layered film 36 and the second layered film 38 in Example 4 are generally configured as described in Table 4 below and are used to calculate Figures 19 to 21 The transmittance, reflectance, CIELAB color space and lightness value described in.

[0223]

[0224]

[0225]

[0226] Fig.19is a graph of the modeled transmittance (polarization average) of the window 24 according to Example 4 for light incident on the window 24 at an angle of incidence of 15° and an angle of incidence of 60° over the entire spectral range of 350 nm to 1600 nm. Fig.19 As shown in FIG. 4 , the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 4 has a percent transmittance greater than 95% for light incident on the first surface 32 or the second surface 34 at an incident angle of less than 15° over the entire wavelength range extending from 850 nm to 950 nm. In fact, over the entire wavelength range from 850 nm to 950 nm, the window exhibits a transmittance greater than 95% for light at an incident angle of 15°.

[0227] In addition, if Fig.19 As shown in , the amount, thickness, number and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 4 has a polarization average transmittance of greater than 90% calculated in the wavelength range of interest of 850nm to 950nm for light incident on the first surface and the second surface at an angle within 60° from the normal of the first surface and the second surface. In addition, as Fig.19 As shown in FIG. 4 , the amount, thickness, number, and material of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 4 has a transmittance of less than 20% in the entire visible spectrum for light incident on the window 24 (end surface 44) at an incident angle of less than or equal to 60°. At an incident angle of 60° on the end surface 44, the window 24 according to Example 4 exhibits a transmittance of less than 0.1% in the entire wavelength range of 400nm to 600nm. The window 24 according to Example 4 exhibits an average transmittance of less than 1% from 400nm to 700nm at both normal incidence and an incident angle of 15°.

[0228] like Fig. 20A As shown in FIG. 4 , the amount, thickness, number and material of the first layer film 36 and the second layer film 38 have been configured so that the window 24 of Example 4 has a polarization average percent reflectivity of less than 1% from the end surface 44 of the first layer film 36 for light incident on the substrate 30 at an incident angle of 15° within the approximate wavelength range of 850nm to 950nm. Fig. 20BAs shown in FIG. 4 , the amount, thickness, number, and materials of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 4 has an average percent reflectivity (polarization average) of less than 0.5% off the end surface 48 of the second layered film 38 for light incident at an incident angle of 15° within the approximate wavelength range of 850nm to 950nm. The window 24 of Example 4 exhibits a polarization average reflectivity of less than 10% for light incident on either of the end surfaces 44 and 48 within the approximate wavelength range of 850nm to 950nm and at an incident angle of 60°.

[0229] Fig. 20C , Fig.20D and Fig.20E The reflectivity performance of the windows according to Example 3 and Example 4 in the wavelength range of 850 nm to 950 nm was compared. Fig. 20C and Fig.20D Graphs of polarization average reflectivity for light incident on the end surface 44 of Examples 3 and 4 at incident angles of 15° and 60°, respectively. Fig. 20C As shown in , the reconfiguration of the second layered film 38 in Example 4 provides lower reflectivity (less than 0.1%) at 15° incident angle over the entire wavelength range of 860nm to 950nm. The reflectivity range (maximum-minimum) is also less than 0.05% for Example 4 over the wavelength range of 850nm to 950nm, while Example 3 exhibits a range of almost 0.2%. Fig.20D As shown in FIG. 1 , the reconfiguration of the second layered film 38 in Example 4 provides a lower reflectivity (less than 7%) at an incident angle of 60° over the entire wavelength range of 850nm to 950nm. The reflectivity range (maximum-minimum) is also less than 3% for Example 4 over the wavelength range of 850nm to 950nm, while Example 3 exhibits a range of greater than 5%. Fig.20E As shown in the Figures, the reconfiguration of the second layered film 38 in Example 4 provides a lower reflectivity (less than 0.2%) over the entire wavelength range of 850nm to 950nm for light incident on the end surface 48 at an incident angle of 15°. These results show that Example 4 has a reduced reflectivity and a flatter reflectance spectrum over the entire wavelength range of 850nm to 950nm compared to Example 3. As described herein, the layered film is made easier to manufacture.

[0230] like Fig.21 As shown in , the amount, thickness, number, and materials of the first layered film 36 and the second layered film 38 have been configured so that the window 24 of Example 4 has a dark appearance when viewed from the end surface 44 of the first layered film. Fig.21Simulated CIELAB reflectance color data for Example E is provided for light reflected from the end surface 44. The CIELAB a* and b* values ​​are generated by simulating a light source at a plurality of different incident angles ranging from 0° to 90°. As shown, the a* values ​​range from about -0.58 to about 0.9, while the b* values ​​range from about -0.2 to about 1.4. This indicates that when the light from the external environment 26 (see Figure 1 ), the window 24 according to Example 4 has a neutral appearance when viewed at 100°. The windows according to Examples 2 and 3 also exhibit L* values ​​less than 37 for light incident on the end surface 44 at incident angles ranging from 0° to 60°, thereby promoting the perceived dark color of the window 24 at those viewing angles.

[0231] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the claims.

Claims

1. A window for a sensing system, the window comprising: A substrate, comprising a first surface and a second surface, wherein the first surface and the second surface are main surfaces of the substrate; a first layered film disposed on the first surface of the substrate, the first layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein the one or more higher refractive index materials of the first layered film have a higher refractive index than the one or more lower refractive index materials of the first layered film; a second layered film disposed on the second surface of the substrate, the second layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein the one or more higher refractive index materials of the second layered film have a higher refractive index than the one or more lower refractive index materials of the second layered film; and a maximum hardness, measured by a Berkovich indenter hardness test at the first layered film, of at least 8 GPa, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured such that the window: having an average percent transmittance greater than 90% calculated over a 50 nm wavelength range of interest centered at a wavelength between 850 nm and 950 nm for light incident on the first surface and the second surface at an angle of incidence of less than or equal to 15°; having an average reflectivity of less than 4% calculated over the 50 nm wavelength range of interest between 850 nm and 950 nm for light incident on the first and second surfaces at an angle of less than or equal to 15°; and The invention has an average percent transmittance of less than 5% calculated from 400 nm to 700 nm for light incident on the first surface and the second surface at an incident angle less than or equal to 15°.

2. A window as described in claim 1, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average P-polarization transmittance and an average S-polarization transmittance greater than 85% calculated within the 50nm wavelength range of interest for light incident on the first surface and the second surface at an incident angle less than or equal to 60°.

3. The window of claim 2, wherein the average P-polarization transmittance and the average S-polarization transmittance calculated within the 50 nm wavelength range of interest are greater than 89% for light incident on the first surface and the second surface at an incident angle less than or equal to 60°.

4. A window as described in any of claims 1 to 3, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has a CIELAB L* reflectance value less than or equal to 37 for an incident angle less than or equal to 60° on the first layered film.

5. The window of claim 4, wherein the CIELAB L* reflectance value is less than or equal to 25 for angles of incidence on the first layered film that are less than or equal to 50°.

6. A window as described in any of claims 1 to 5, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that when viewed from one side of the first layered film, the window has CIELAB a* and b* reflectance values ​​greater than or equal to -6.0 and less than or equal to 6.

0.

7. A window as described in any one of claims 1 to 6, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent transmittance greater than 95% calculated within the 50nm wavelength range of interest for light incident normally on the first surface and the second surface.

8. The window according to any one of claims 1 to 7, wherein: The substrate has a refractive index of about 1.45 to about 1.55 for electromagnetic radiation having a wavelength of 905 nm, and the substrate is a glass substrate or a glass ceramic substrate, The refractive index of the one or more higher refractive index materials is about 1.7 to about 4.0, and wherein the refractive index of the one or more lower refractive index materials is about 1.3 to about 1.6, and The difference in the refractive index of any of the one or more higher refractive index materials and any of the one or more lower refractive index materials is about 0.5 or greater.

9. The window according to any one of claims 1 to 8, wherein: one of the alternating layers of the first layered film farthest from the substrate forms an end surface material of the window, the end surface material of the window comprising the lower refractive index material, and The first layered film includes a scratch resistant layer formed of one of the one or more higher refractive index materials and having a thickness greater than or equal to 1500 nm and less than or equal to 5000 nm.

10. The window of claim 9, wherein the scratch resistant layer is separated from the end surface by a plurality of alternating layers of the one or more lower refractive index materials and the one or more higher refractive index materials of the first layered film.

11. The window of claim 10, wherein the scratch resistant layer is separated from the end surface by at least 1000 nm.

12. The window of any one of claims 1 to 11, wherein the one or more higher refractive index materials of the second layered film include silicon having an extinction coefficient less than or equal to 0.01 in the 50 nm wavelength range of interest.

13. The window of claim 12, wherein the extinction coefficient is less than or equal to 0.005 over the 50 nm wavelength range of interest.

14. The window of claim 13, wherein the second layered film comprises two or more silicon layers.

15. The window of claim 14, wherein the second layered film comprises a layer of TCO material, wherein the two or more silicon layers are disposed between the layer of TCO material and the substrate.

16. The window of claim 15, wherein the TCO material layer comprises a thickness greater than or equal to 20 nm and less than or equal to 30 mm.

17. The window of claim 16, wherein the TCO material layer is indium tin oxide and comprises an extinction coefficient less than or equal to .05 throughout the 50 nm wavelength range of interest.

18. The window of any one of claims 14 to 17, wherein the silicon layer of the second layered film closest to the substrate comprises the smallest thickness of the two or more silicon layers.

19. The window of claim 18, wherein the combined thickness of the silicon layers contained in the second layered film is greater than or equal to 450 nm.

20. The window of any one of claims 12 to 19, wherein a layer of the one or more higher refractive index materials in the second layered film is not silicon.

21. The window of claim 20, wherein an inner AR stack separates the two or more silicon layers of the second layered film from an inner end surface of the second layered film, wherein the inner AR stack includes at least one layer of the one or more higher refractive index materials that is not silicon.

22. A window as described in claim 21, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent reflectivity of less than 0.5% calculated within the 50nm wavelength range of interest for light incident on both the first end surface of the first layered film and the second end surface of the second layered film at an incident angle less than or equal to 15°.

23. A window as described in any of claims 21 to 22, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent transmittance of less than 1% calculated from 400nm to 700nm for light incident on the first surface and the second surface in the normal direction.

24. A window as claimed in any one of claims 21 to 23, wherein: The second layered film includes at least ten silicon layers, and The inner AR stack includes less than two layers of the one or more higher refractive index materials that are not silicon.

25. A window as described in claim 24, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window exhibits a polarization average reflectivity range (maximum value-minimum value) of less than 0.5% calculated within the wavelength range of 850nm to 950nm for light incident on the first layered film at an incident angle of 15°.

26. The window of any of the preceding claims, wherein the maximum hardness at the first layered film as measured by the Berkovich Indenter Hardness Test is at least 15 GPa.

27. The window of any of the preceding claims, wherein the hardness at the first layered film as measured by the Berkovich Indenter Hardness Test is at least 14 GPa in the depth range of 400 nm to 1000 nm.

28. A window for a sensing system, comprising: A substrate, comprising a first surface and a second surface, wherein the first surface and the second surface are main surfaces of the substrate; a first layered film disposed on the first surface of the substrate, the first layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein the refractive index of the one or more higher refractive index materials of the first layered film is higher than the refractive index of the one or more lower refractive index materials of the first layered film; a second layered film disposed on the second surface of the substrate, the second layered film comprising alternating layers of one or more higher refractive index materials and one or more lower refractive index materials, wherein the refractive index of the one or more higher refractive index materials of the second layered film is higher than the refractive index of the one or more lower refractive index materials of the second layered film; and a maximum hardness, measured by a Berkovich indenter hardness test at the first layered film, of at least 8 GPa, wherein the amounts, thicknesses, numbers, and materials of alternating layers of the first layered film and the second layered film are configured such that the window: having an average reflectivity of less than 4% calculated over a 50 nm wavelength range of interest centered at a wavelength between 850 nm and 950 nm for light incident on the first surface and the second surface at an angle of less than or equal to 15°; has a CIELAB L* reflectance value of less than or equal to 37 for an incident angle of less than or equal to 60° on the first layered film; and The first layered film has CIELA b* and b* reflectance values ​​greater than or equal to -6.0 and less than or equal to 6.0 when viewed from one side of the first layered film.

29. The window of claim 28, wherein the CIELAB L* reflectance value is less than or equal to 25 for angles of incidence on the first layered film that are less than or equal to 50°.

30. A window as described in any of claims 28 to 29, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent transmittance greater than 95% calculated within the 50nm wavelength range of interest for light incident on the first surface and the second surface at an incident angle less than or equal to 15°.

31. A window as described in any of claims 28 to 30, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent transmittance of less than 5% calculated from 400nm to 700nm for light incident on the first surface and the second surface at an incident angle less than or equal to 15°.

32. A window as described in any one of claims 28 to 31, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average P-polarization transmittance and an average S-polarization transmittance greater than 85% calculated within a wavelength range of 50nm for light incident on the first surface and the second surface at an incident angle less than or equal to 60°.

33. A window as described in claim 32, wherein the average P-polarization transmittance and the average S-polarization transmittance calculated within the 50 nm wavelength range of interest are greater than 89% for light incident on the first surface and the second surface at an incident angle less than or equal to 60°.

34. The window of any one of claims 28 to 33, wherein the maximum hardness at the delaminated film as measured by the Berkovich Indenter Hardness Test is at least 15 GPa.

35. A window as claimed in any one of claims 28 to 34, wherein: one of the alternating layers of the first layered film farthest from the substrate forms an end surface material of the window, the end surface material of the window comprising the lower refractive index material, The first layered film includes a scratch resistant layer formed of one of the one or more higher refractive index materials and having a thickness greater than or equal to 1500 nm and less than or equal to 5000 nm.

36. The window of claim 35, wherein: The scratch resistant layer is separated from the end surface by the plurality of alternating layers of the one or more lower refractive index materials and the one or more higher refractive index materials of the first layered film, and The scratch resistant layer is separated from the end surface by at least 1000 nm.

37. The window of any one of claims 28 to 36, wherein the one or more higher refractive index materials of the second layered film include silicon having an extinction coefficient less than or equal to 0.004 in the 50 nm wavelength range of interest.

38. The window of claim 37, wherein the second layered film comprises two or more silicon layers.

39. The window of claim 38, wherein the second layered film comprises a layer of TCO material, wherein the two or more silicon layers are disposed between the layer of TCO material and the substrate.

40. The window of claim 39, wherein the layer of TCO material comprises a thickness greater than or equal to 20 nm and less than or equal to 30 mm.

41. The window of claim 40, wherein the TCO material layer is indium tin oxide and comprises an extinction coefficient less than or equal to .05 throughout the 50 nm wavelength range of interest.

42. The window of any one of claims 38 to 41, wherein the silicon layer of the second layered film closest to the substrate comprises the smallest thickness of the two or more silicon layers.

43. The window of any one of claims 38 to 42, wherein the combined thickness of the silicon layers contained in the second layered film is greater than or equal to 450 nm.

44. The window of any one of claims 38 to 43, wherein one layer of the one or more higher refractive index materials in the second layered film is not silicon.

45. The window of claim 44, wherein an inner AR stack separates the two or more silicon layers from the inner end surface of the second layered film, wherein the inner AR stack comprises at least two layers of the one or more higher refractive index materials that are not silicon.

46. ​​A window as described in claim 45, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent reflectivity of less than 0.5% calculated within the 50nm wavelength range of interest for light incident on both the first end surface of the first layered film and the second end surface of the second layered film at an incident angle less than or equal to 15°.

47. A window as claimed in any one of claims 45 to 46, wherein: The second layered film includes at least ten silicon layers, and The inner AR stack includes less than two layers of the one or more higher refractive index materials that are not silicon.

48. A window as described in claim 47, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window exhibits a polarization average reflectivity range (maximum value - minimum value) of less than 0.5% calculated within the wavelength range of 850nm to 950nm for light incident on the first layered film at an incident angle of 15°.

49. A window as described in any of claims 45 to 48, wherein the amount, thickness, number and material of the alternating layers of the first layered film and the second layered film are configured so that the window has an average percent transmittance of less than 1% calculated from 400nm to 700nm for light incident on the first surface and the second surface in the normal direction.

Images