Far infrared transmitting member and method for manufacturing far infrared transmitting member

Abstract

The present application suitably suppresses reflection of far infrared rays and suitably forms an antireflection film. A far infrared ray transmitting member (20) has a substrate (30) that transmits far infrared rays and a functional film (32) formed on the substrate (30) and containing a low refractive index layer (34) that has an oxide as a main component and has a refractive index of 1.5 or less for light of a wavelength of 10 μm, the low refractive index layer (34) having MgO as a main component, and the content ratio of MgO being 50 mass% or more and 100 mass% or less with respect to the entirety of the low refractive index layer (34).

Description

TECHNICAL FIELD

[0001] The present application relates to a far infrared ray transmitting member and a method for manufacturing a far infrared ray transmitting member. BACKGROUND

[0002] When a far infrared ray sensor is mounted on a vehicle or the like, for example, a far infrared ray transmitting member that transmits far infrared rays is sometimes provided so that far infrared rays are properly incident on the far infrared ray sensor. Such a far infrared ray transmitting member is required to suppress reflection of far infrared rays and thereby improve the transmittance of far infrared rays. In order to suppress reflection, it is known to form an antireflection film (AR film) on a substrate. For example, in Patent Literature 1, an optical member capable of transmitting infrared rays obtained by laminating a first coating film and a second coating film as antireflection films on a substrate is described. In addition, it is also known to use a fluorine compound such as MgF2 as an antireflection film for far infrared rays. In addition, in Patent Literature 2, an infrared ray transmitting structure for far infrared rays using a fluorine compound such as MgF2 as a low refractive index layer is described.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 62-299901

[0006] Patent Literature 2: Japanese Patent No. 3704739 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] However, in the case of using the first coating film and the second coating film in Patent Literature 1, for example, according to the characteristics of the films described in Patent Literature 1, in order to impart appropriate antireflection properties, it is necessary to increase the film thickness or the like, and there is room for improvement in terms of appropriately suppressing reflection of far infrared rays. In addition, fluorine compounds such as MgF2 have poor adhesion to substrates and inorganic films. Furthermore, there are few options for the formation process on a substrate, and there is room for improvement in terms of making the formation process flexible. Therefore, there is a demand for a far infrared ray transmitting member that can appropriately suppress reflection of far infrared rays and can appropriately form an antireflection film.

[0009] An object of the present application is to provide a far infrared ray transmitting member and a method for manufacturing a far infrared ray transmitting member that can appropriately suppress reflection of far infrared rays and can appropriately form an antireflection film.

[0010] MEANS FOR SOLVING THE PROBLEM

[0011] To address the aforementioned problems and achieve the objective, the far-infrared transmission component disclosed herein comprises a substrate that transmits far-infrared rays and a functional film formed on the substrate. The functional film includes a low-refractive-index layer with oxide as the main component and a refractive index of 1.5 or less for light with a wavelength of 10 μm. The low-refractive-index layer has MgO as the main component, and the content of MgO relative to the total low-refractive-index layer is 50% by mass or more and 100% by mass or less.

[0012] To solve the above problems and achieve the objective, in the method for manufacturing a far-infrared transmission component disclosed herein, a far-infrared transmission component is manufactured by forming a functional film on a far-infrared transmission substrate. The functional film includes a low refractive index layer with oxide as the main component and a refractive index of 1.5 or less for light with a wavelength of 10 μm. The low refractive index layer has MgO as the main component, and the content of MgO relative to the total low refractive index layer is 50% by mass or more and 100% by mass or less.

[0013] Invention Effects

[0014] According to the present invention, the reflection of far-infrared rays can be appropriately suppressed, and an anti-reflection film can be appropriately formed. Attached Figure Description

[0015] Figure 1 This is a schematic diagram showing the state in which the vehicle glass of this embodiment is mounted on a vehicle.

[0016] Figure 2 This is a top view schematic diagram of the vehicle glass 1 according to the first embodiment.

[0017] Figure 3 For along Figure 2 A cross-sectional view along line AA.

[0018] Figure 4 For along Figure 2 A sectional view of section BB.

[0019] Figure 5 This is a cross-sectional schematic diagram of the far-infrared transmission component of this embodiment.

[0020] Figure 6 This is a cross-sectional schematic diagram of a far-infrared transmission component, which is another example of this embodiment.

[0021] Figure 7 This is a cross-sectional schematic diagram of a far-infrared transmission component, which is another example of this embodiment.

[0022] Figure 8 This is a cross-sectional schematic diagram of a far-infrared transmission component, which is another example of this embodiment.

[0023] Figure 9 This is a cross-sectional schematic diagram of a far-infrared transmission component, which is another example of this embodiment.

[0024] Figure 10 A graph showing the evaluation results for each example.

[0025] Figure 11 A graph showing the evaluation results for each example. Detailed Implementation

[0026] Hereinafter, suitable embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited to these embodiments; furthermore, in the case of multiple embodiments, it also includes configurations by combining various embodiments. Additionally, numerical values ​​include rounding ranges.

[0027] (vehicle)

[0028] Figure 1 This is a schematic diagram illustrating the state in which the vehicle glass of this embodiment is mounted on a vehicle. For example... Figure 1 As shown, the vehicle glass 1 of this embodiment is mounted on a vehicle V. The vehicle glass 1 is a window component applied to the front windshield of the vehicle V. That is, the vehicle glass 1 is used as the front window of the vehicle V, in other words, it is used as a windshield. An infrared camera CA1 and a visible light camera CA2 are mounted inside the vehicle V (inside the vehicle). It should be noted that the inside of the vehicle V (inside the vehicle) refers to, for example, the passenger compartment where the driver's seat is located.

[0029] The camera unit 100 of this embodiment comprises vehicle glass 1, a far-infrared camera CA1, and a visible light camera CA2. The far-infrared camera CA1 is a camera that detects far-infrared radiation, capturing a thermal image of the exterior of the vehicle V by detecting far-infrared radiation from the exterior of the vehicle V. The visible light camera CA2 is a camera that detects visible light, capturing an image of the exterior of the vehicle V by detecting visible light from the exterior of the vehicle V. It should be noted that, in addition to the far-infrared camera CA1 and the visible light camera CA2, the camera unit 100 may also include, for example, LiDAR or millimeter-wave radar. Here, far-infrared radiation refers to electromagnetic waves in the wavelength range of, for example, 8μm to 13μm, and visible light refers to electromagnetic waves in the wavelength range of, for example, 360nm to 830nm. Furthermore, 8μm to 13μm here refers to 8μm or more and 13μm or less, and 360nm to 830nm refers to 360nm or more and 830nm or less, and the same applies below. It should be noted that far-infrared radiation can be set to electromagnetic waves in the wavelength range of 8μm to 12μm.

[0030] (Vehicle glass)

[0031] Figure 2 This is a top view schematic diagram of the vehicle glass 1 according to the first embodiment. Figure 3 For along Figure 2 A cross-sectional view along line AA. Figure 4 For along Figure 2 A sectional view of section BB. (e.g.) Figure 2 As shown, the upper edge of the vehicle glass 1 is referred to as upper edge 1a, the lower edge of the vehicle glass 1 as lower edge 1b, one side edge of the vehicle glass 1 as side edge 1c, and the other side edge of the vehicle glass 1 as side edge 1d. Upper edge 1a is the edge portion located vertically upward when the vehicle glass 1 is mounted on the vehicle V. Lower edge 1b is the edge portion located vertically downward when the vehicle glass 1 is mounted on the vehicle V. Side edge 1c is the edge portion located on one side of the vehicle glass 1 when it is mounted on the vehicle V. Side edge 1d is the edge portion located on the other side of the vehicle glass 1 when it is mounted on the vehicle V.

[0032] Hereinafter, in the direction parallel to the surface of the vehicle glass 1, the direction from the upper edge 1a to the lower edge 1b is defined as the Y direction, and the direction from the side edge 1c to the side edge 1d is defined as the X direction. In this embodiment, the X direction is orthogonal to the Y direction. The direction orthogonal to the surface of the vehicle glass 1, i.e., the thickness direction of the vehicle glass 1, is defined as the Z direction. The Z direction is, for example, the direction from the outside of the vehicle V to the inside of the vehicle V when the vehicle glass 1 is mounted on the vehicle V. The X and Y directions are along the surface of the vehicle glass 1, but for example, if the surface of the vehicle glass 1 is curved, they can also be directions tangent to the surface of the vehicle glass 1 at the center point O of the vehicle glass 1. The center point O refers to the center position of the vehicle glass 1 when viewed from the Z direction.

[0033] A light-transmitting area A1 and a light-blocking area A2 are formed on the vehicle glass 1. The light-transmitting area A1 occupies the central portion of the vehicle glass 1 when viewed from the Z direction. The light-transmitting area A1 is used to ensure the driver's field of vision. The light-transmitting area A1 transmits visible light. The light-blocking area A2 is formed around the light-transmitting area A1 when viewed from the Z direction. The light-blocking area A2 blocks visible light. Within the light-blocking area A2a, which is part of the upper edge 1a, a far-infrared transmission area B and a visible light transmission area C are formed.

[0034] The far-infrared transmission region B is the area that transmits far-infrared light, and it is also the area where the far-infrared camera CA1 is installed. That is, the far-infrared camera CA1 is positioned where it overlaps with the far-infrared transmission region B when viewed from the optical axis of the far-infrared camera CA1. The visible light transmission region C is the area that transmits visible light, and it is also the area where the visible light camera CA2 is installed. That is, the visible light camera CA2 is positioned where it overlaps with the visible light transmission region C when viewed from the optical axis of the visible light camera CA2.

[0035] Because a far-infrared transmission area B and a visible light transmission area C are formed in the light-shielding area A2, the light-shielding area A2 blocks far-infrared rays in areas other than the area where the far-infrared transmission area B is formed, and blocks visible light in areas other than the area where the visible light transmission area C is formed. A light-shielding area A2a is formed around the far-infrared transmission area B and the visible light transmission area C. By setting the light-shielding area A2a around them in this way, various sensors can be protected from the influence of sunlight, which is therefore preferred. Since the wiring of various sensors is not visible from outside the vehicle, this is also preferred from an aesthetic design point of view.

[0036] like Figure 3 As shown, the vehicle glass 1 has a glass substrate 12 (first glass substrate), a glass substrate 14 (second glass substrate), an intermediate layer 16, and a light-shielding layer 18. In the vehicle glass 1, the glass substrate 12, the intermediate layer 16, the glass substrate 14, and the light-shielding layer 18 are sequentially stacked in the Z direction. The glass substrate 12 and the glass substrate 14 are fixed to each other (adhesive-bonded) by the intermediate layer 16.

[0037] As the glass substrates 12 and 14, for example, soda-lime glass, borosilicate glass, aluminosilicate glass, etc., can be used. The interlayer 16 is an adhesive layer that bonds the glass substrates 12 and 14 together. As the interlayer 16, for example, polyvinyl butyral (hereinafter also referred to as PVB) modified materials, ethylene-vinyl acetate copolymer (EVA) materials, polyurethane resin materials, vinyl chloride resin materials, etc., can be used. More specifically, the glass substrate 12 includes one surface 12A and another surface 12B, the other surface 12B being in contact with and fixed (adheded) to one surface 16A of the interlayer 16. The glass substrate 14 includes one surface 14A and another surface 14B, one surface 14A being in contact with and fixed (adheded) to the other surface 16B of the interlayer 16. In this way, the vehicle glass 1 is a laminated glass obtained by laminating the glass substrates 12 and 14. However, the vehicle glass 1 is not limited to laminated glass; for example, it may be a structure containing only one of the glass substrate 12 and the glass substrate 14. In this case, the intermediate layer 16 may not be provided. Hereinafter, without distinguishing between the glass substrates 12 and 14, it will be referred to as the glass substrate 10.

[0038] The light-shielding layer 18 includes one surface 18A and another surface 18B, with one surface 18A in contact with and fixed to the other surface 14B of the glass substrate 14. The light-shielding layer 18 is a layer that blocks visible light. For example, a ceramic light-shielding layer or a light-shielding film can be used as the light-shielding layer 18. For example, a ceramic layer containing conventionally known materials, such as a black ceramic layer, can be used. For example, a light-shielding polyethylene terephthalate (PET) film, a light-shielding polyethylene naphthalate (PEN) film, or a light-shielding polymethyl methacrylate (PMMA) film can be used.

[0039] In this embodiment, the side of the vehicle glass 1 where the light-shielding layer 18 is provided is the inner side (interior side) of the vehicle V, and the side of the vehicle glass 1 where the glass substrate 12 is provided is the outer side (outer side) of the vehicle V. However, it is not limited to this, and the light-shielding layer 18 may also be the outer side of the vehicle V. When the glass is made of laminated glass composed of glass substrates 12 and 14, the light-shielding layer 18 may be formed between the glass substrate 12 and the glass substrate 14.

[0040] (Shaded area)

[0041] The light-shielding region A2 is formed by providing a light-shielding layer 18 on the glass substrate 10. That is, the light-shielding region A2 is the region of the glass substrate 10 where the light-shielding layer 18 is present. Specifically, the light-shielding region A2 is the region where the glass substrate 10 is stacked with the glass substrate 12, the intermediate layer 16, the glass substrate 14, and the light-shielding layer 18. On the other hand, the light-transmitting region A1 is the region of the glass substrate 10 where the light-shielding layer 18 is not present. Specifically, the light-transmitting region A1 is the region where the glass substrate 12, the intermediate layer 16, and the glass substrate 14 are stacked, but the light-shielding layer 18 is not stacked.

[0042] (Far-infrared transmission area)

[0043] like Figure 3 As shown, the vehicle glass 1 has an opening 19 extending from one surface (surface 12A) in the Z direction to another surface (surface 14B). A far-infrared transmitting member 20 is disposed within the opening 19. The area where the opening 19 is formed and the far-infrared transmitting member 20 is disposed is the far-infrared transmitting region B. That is, the far-infrared transmitting region B is the area where the opening 19 is provided and the far-infrared transmitting member 20 is disposed within the opening 19. No light-shielding layer 18 is provided in the far-infrared transmitting region B. That is, the glass substrate 12, intermediate layer 16, glass substrate 14, and light-shielding layer 18 are not provided in the far-infrared transmitting region B; instead, the far-infrared transmitting member 20 is provided within the formed opening 19. The far-infrared transmitting member 20 will be described later.

[0044] (Visible light transmission region)

[0045] like Figure 4 As shown, similar to the light-transmitting region A1, the visible light transmission region C is the region in the Z direction where the glass substrate 10 does not have a light-shielding layer 18. That is, the visible light transmission region C is the region where the glass substrate 12, the intermediate layer 16, and the glass substrate 14 are stacked, but the light-shielding layer 18 is not stacked.

[0046] like Figure 2As shown, the visible light transmission region C is preferably located near the far-infrared transmission region B. Specifically, the center of the far-infrared transmission region B, viewed from the Z direction, is designated as the center point OB, and the center of the visible light transmission region C, viewed from the Z direction, is designated as the center point OC. When the shortest distance between the far-infrared transmission region B (opening 19) and the visible light transmission region C, viewed from the Z direction, is defined as distance L, distance L is preferably greater than 0 mm and less than or equal to 100 mm, and more preferably 10 mm or more and 80 mm or less. By positioning the visible light transmission region C relative to the far-infrared transmission region B within this range, images of close proximity can be captured using the far-infrared camera CA1 and the visible light camera CA2, while perspective distortion in the visible light transmission region C can be suppressed, thereby enabling the visible light camera CA2 to capture images appropriately. By capturing images of close proximity using the far-infrared camera CA1 and the visible light camera CA2, the processing load on the data obtained from each camera can be reduced, and the wiring of power and signal cables becomes more appropriate.

[0047] like Figure 2 As shown, the visible light transmission region C and the far-infrared transmission region B are preferably arranged along the X direction. That is, the visible light transmission region C is preferably arranged along the X direction with the far-infrared transmission region B, and not located on the Y-direction side of the far-infrared transmission region B. By arranging the visible light transmission region C in a manner that aligns it with the far-infrared transmission region B along the X direction, the visible light transmission region C can be positioned near the upper edge 1a. Therefore, the driver's field of vision in the light-transmitting region A1 can be adequately ensured.

[0048] (Far-infrared transmission component)

[0049] The far-infrared transmission component 20, which is set in the far-infrared transmission area B, will be described in detail below. Figure 5 This is a cross-sectional schematic diagram of the far-infrared transmission component of this embodiment. Figure 5 As shown, the far-infrared transmission member 20 has a substrate 30 and a functional film (AR film) 32 formed on the substrate 30. In this embodiment, the far-infrared transmission member 20 has the functional film 32 formed on both one surface 30a and the other surface 30b of the substrate 30. However, the far-infrared transmission member 20 is not limited to having the functional film 32 formed on both surfaces 30a and 30b of the substrate 30; it may also have the functional film 32 formed on at least one of surfaces 30a and 30b. It should be noted that surface 30a is the surface that becomes the inner side of the vehicle when mounted on the vehicle glass 1, and surface 30b is the surface that becomes the outer side of the vehicle when mounted on the vehicle glass 1.

[0050] In this embodiment, the far-infrared transmission member 20 is provided in the light-shielding area A2 of the vehicle glass 1, which serves as the windshield of the vehicle V. However, it is not limited to this and can also be provided on any external component of the vehicle V, such as an external component for a pillar. Furthermore, the far-infrared transmission member 20 is not limited to being provided on the vehicle V and can be used for any purpose.

[0051] (Substrate)

[0052] The substrate 30 is a component capable of transmitting far-infrared rays. The internal transmittance of the substrate 30 for light (far-infrared rays) with a wavelength of 10 μm is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. Furthermore, the average internal transmittance of the substrate 30 for light (far-infrared rays) with wavelengths of 8 μm to 12 μm is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. With the internal transmittance of the substrate 30 for light with a wavelength of 10 μm and the average internal transmittance for light with wavelengths of 8 μm to 12 μm within this range, far-infrared rays can be appropriately transmitted, for example, the performance of the far-infrared camera CA1 can be fully utilized. It should be noted that the average internal transmittance here refers to the average of the internal transmittance of each wavelength in this band (here, 8 μm to 12 μm).

[0053] The internal transmittance of the substrate 30, after deducting the surface reflection losses on the incident and emanating sides, is well known in the art and can be measured using conventional methods. The measurement is performed, for example, as follows.

[0054] Prepare a pair of flat specimens (first specimen and second specimen) with the same substrate composition but different thicknesses. The two sides of the flat specimens are parallel planes that have been optically polished. Let the external transmittance of the first specimen including surface reflection loss be T1, the external transmittance of the second specimen including surface reflection loss be T2, the thickness of the first specimen be Td1 (mm), and the thickness of the second specimen be Td2 (mm), where Td1 < Td2. Then, the internal transmittance τ at a thickness Tdx (mm) can be calculated by the following formula (1).

[0055] τ=exp[-Tdx×(lnT1-lnT2) / ΔTd]……(1)

[0056] It should be noted that the external transmittance of infrared radiation can be measured, for example, using a Fourier transform infrared spectrometer (manufactured by ThermoScientific, trade name: Nicolet iS10).

[0057] The refractive index of the substrate 30 for light with a wavelength of 10 μm is preferably 1.5 or higher and 4.0 or lower, more preferably 2.0 or higher and 4.0 or lower, and even more preferably 2.2 or higher and 3.5 or lower. Furthermore, the average refractive index of the substrate 30 for light with wavelengths from 8 μm to 12 μm is preferably 1.5 or higher and 4.0 or lower, more preferably 2.0 or higher and 4.0 or lower, and even more preferably 2.2 or higher and 3.5 or lower. With the refractive index and average refractive index of the substrate 30 within this range, far-infrared light can be appropriately transmitted, thus maximizing the performance of the far-infrared camera CA1. It should be noted that the average refractive index here refers to the average value of the refractive index of light at various wavelengths in this band (here, 8 μm to 12 μm). The refractive index can be determined, for example, by fitting an optical model using polarization information obtained from an infrared ellipsometer (manufactured by JAWoollam, IR-VASE-UT) and a spectroscopic transmission spectrum obtained from a Fourier transform infrared spectroscopy device.

[0058] The thickness d0 of the substrate 30 is preferably 0.5 mm or more and 5 mm or less, more preferably 1.0 mm or more and 4 mm or less, and even more preferably 1.5 mm or more and 3 mm or less. Within this thickness range, strength can be ensured while allowing appropriate transmission of far-infrared rays. It should be noted that the thickness d0 can also be described as the length in the Z direction from surface 30a to surface 30b of the substrate 30.

[0059] There are no particular limitations on the material of the substrate 30; examples include Si, Ge, ZnS, and chalcogenide glasses. It can be said that the substrate 30 preferably contains at least one material selected from the group consisting of Si, Ge, ZnS, and chalcogenide glasses. By using such a material in the substrate 30, far-infrared rays can be appropriately transmitted.

[0060] Preferred compositions for chalcogenide glasses include the following:

[0061] Expressed in atomic percent, it contains:

[0062] Ge+Ga: 7%~25%,

[0063] Sb: 0%–35%

[0064] Bi: 0%–20%

[0065] Zn: 0%–20%

[0066] Sn: 0%–20%

[0067] Si: 0%–20%

[0068] La: 0%–20%

[0069] S+Se+Te: 55%~80%

[0070] Ti: 0.005%~0.3%

[0071] Li+Na+K+Cs: 0%~20%

[0072] F + Cl + Br + I: 0% to 20%. Furthermore, this glass preferably has a glass transition temperature (Tg) of 140°C to 550°C.

[0073] It should be noted that Si or ZnS is more preferably used as the material for the substrate 30.

[0074] (Functional membrane)

[0075] A functional film 32 is formed on a substrate 30 and is a layer for suppressing far-infrared reflection. In this embodiment, the functional film 32 has a low-refractive-index layer 34 and a high-refractive-index layer 36.

[0076] exist Figure 5 In the example, low-refractive-index layer 34 and high-refractive-index layer 36 are alternately stacked. Figure 5 In the example, the functional film 31 has a low refractive index layer 34 and a high refractive index layer 36 sequentially stacked on the substrate 30 in a direction away from the substrate 30. However, in the functional film 31, the layer formed on the side closest to the substrate 30 is not limited to the low refractive index layer 34, but can be, for example, the high refractive index layer 36. For example, the high refractive index layer 36 and the low refractive index layer 34 can be sequentially stacked in a direction away from the substrate 30.

[0077] In addition, Figure 5 In the example, the functional film 32 has a structure consisting of a single low-refractive-index layer 34 and a single high-refractive-index layer 36, but it is not limited to this; at least one of multiple low-refractive-index layers 34 and high-refractive-index layers 36 can also be stacked. For example, as described later. Figure 6 As shown, the far-infrared transmission component 20 can have multiple layers of low-refractive-index layers 34 and multiple layers of high-refractive-index layers 36 alternately stacked on the substrate 30 in a direction away from the substrate 30. That is, the substrate 30, low-refractive-index layer 34, high-refractive-index layer 36, low-refractive-index layer 34, ..., high-refractive-index layer 36 can be stacked sequentially. Alternatively, the far-infrared transmission component 20 can also have multiple layers of high-refractive-index layers 36 and multiple layers of low-refractive-index layers 34 alternately stacked on the substrate 30 in a direction away from the substrate 30. That is, the substrate 30, high-refractive-index layer 36, low-refractive-index layer 34, high-refractive-index layer 36, ..., low-refractive-index layer 34 can also be stacked sequentially.

[0078] In addition, the functional membrane 32 can be as described later. Figure 7The structure shown includes a low-refractive-index layer 34 but not a high-refractive-index layer 36. The functional film 32 can be characterized by having at least one low-refractive-index layer 34. That is, the functional film 32 can be a single-layer film composed of a single low-refractive-index layer 34, or it can be a multilayer film composed of low-refractive-index layers 34 and high-refractive-index layers 36. By using a multilayer structure as the antireflective film 32, low reflectivity can be easily achieved over a wide wavelength range by utilizing the interfacial reflections generated at each interface and the interference of light.

[0079] (Low-refractive-index layer)

[0080] A low-refractive-index layer 34 is formed on the substrate 30 and is a film for suppressing far-infrared light reflection. The low-refractive-index layer 34 is a film with a low refractive index for far-infrared light, and the refractive index of the low-refractive-index layer 34 for light with a wavelength of 10 μm is preferably less than or equal to the square root of the refractive index of the substrate 30, and preferably less than or equal to 1.5, more preferably less than or equal to 0.8 and less than 1.5, and even more preferably less than or equal to 0.8 and less than 1.4. Furthermore, the average refractive index of the low-refractive-index layer 34 for light with wavelengths of 8 μm to 12 μm is preferably less than or equal to the square root of the average refractive index of the substrate 30, and preferably less than or equal to 1.5, more preferably less than or equal to 0.8 and less than 1.5, and even more preferably less than or equal to 0.8 and less than 1.4. By utilizing the refractive index and average refractive index of the low-refractive-index layer 34 within this range, it can function appropriately as a low-refractive-index film, thereby appropriately suppressing the reflection of far-infrared rays, while also allowing the film thickness of the functional film 32 to be reduced.

[0081] Furthermore, the thickness d1 of the low refractive index layer 34 is preferably 0.1 μm or more and 2 μm or less, more preferably 0.2 μm or more and 1.7 μm or less, and even more preferably 0.3 μm or more and 1.5 μm or less. With a thickness d1 within this range, the reflection of far-infrared rays can be appropriately suppressed, while simultaneously reducing the thickness of the functional film 32. It should be noted that the thickness d1 can also be described as the length in the Z direction from the surface 34a of the low refractive index layer 34 to the opposite surface 34b.

[0082] Here, the refractive index of the low-refractive-index layer 34 for light with a wavelength of 10 μm is defined as refractive index n1, and the product of the refractive index n1 and the thickness d1 of the low-refractive-index layer 34 is defined as the optical film thickness n1d1. In this case, the optical film thickness n1d1 of the low-refractive-index layer 34 for light with a wavelength of 10 μm is preferably 0.1 μm or more and 2.5 μm or less, more preferably 0.2 μm or more and 2.2 μm or less, and even more preferably 0.4 μm or more and 2.0 μm or less. In addition, the average optical film thickness of the low-refractive-index layer 34 is preferably 0.1 μm or more and 2.5 μm or less, more preferably 0.2 μm or more and 2.2 μm or less, and even more preferably 0.3 μm or more and 2.0 μm or less, wherein the average optical film thickness is the product of the average refractive index of the low-refractive-index layer 34 for light with a wavelength of 8 μm to 12 μm and the thickness d1. By controlling the optical film thickness n1d1 and the average optical film thickness within this range, the reflection of far-infrared rays can be appropriately suppressed, while the film thickness of the functional film 32 can be reduced.

[0083] The low-refractive-index layer 34 is capable of transmitting far-infrared radiation. The extinction coefficient of the low-refractive-index layer 34 for light with a wavelength of 10 μm is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.02 or less. The average extinction coefficient of the low-refractive-index layer 34 for light with wavelengths from 8 μm to 12 μm is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.02 or less. Within this range of extinction coefficient and average extinction coefficient, far-infrared radiation can be appropriately transmitted. It should be noted that the average extinction coefficient refers to the average value of the extinction coefficients for each wavelength in this band (here, 8 μm to 12 μm). The extinction coefficient can be determined, for example, by fitting an optical model using polarization information obtained from an infrared ellipsometer (manufactured by JA Woollam, IR-VASE-UT) and a spectroscopic transmission spectrum obtained from a Fourier transform infrared spectrometer.

[0084] The low refractive index layer 34 is a film with oxide as its main component. Here, "main component" can refer to a content of 50% by mass or more relative to the total content of the low refractive index layer 34. More specifically, the low refractive index layer 34 preferably has MgO as its main component as an oxide. The content of MgO in the low refractive index layer 34 is preferably 50% by mass or more and 100% by mass or less relative to the total content of the low refractive index layer 34, more preferably 70% by mass or more and 100% by mass or less, and even more preferably 70% by mass or more and 100% by mass or less. Furthermore, the low refractive index layer 34 is preferably composed solely of MgO, that is, the content of MgO, excluding unavoidable impurities, is 100% by mass. With the MgO content within this range, the low refractive index layer 34 can appropriately transmit far-infrared rays, and its low refractive index for far-infrared rays can appropriately suppress far-infrared ray reflection.

[0085] The low-refractive-index layer 34 may contain minor components, which are components other than the oxide (in this case, MgO) that is the main component. Preferred minor components are oxides that transmit infrared radiation, such as NiO. x CuO x ZnO, ZrO2, Bi2O3, Y2O3. That is, the low refractive index layer 34 preferably contains substances selected from NiO. x CuO x At least one material selected from the group consisting of ZnO, ZrO2, Bi2O3, and Y2O3 is used as a secondary component. MgO is hygroscopic, and there is room for improvement in water resistance, but by including a secondary component, water resistance can be improved. Alternatively, for example, the water resistance of the functional film 32 can be improved by forming a water-resistant layer on the surface of the low-refractive-index layer 34 of MgO alone, thereby protecting the low-refractive-index layer 34. It should be noted that nickel oxide and copper oxide are known to have various compositions depending on the valence of nickel and copper, and x can take any value from 0.5 to 2. Furthermore, the valence may not be singular, and may be a mixture of two or more valences. In this embodiment, NiO is used as... x NiO is preferred as a substitute for CuO. x CuO is preferred.

[0086] (High refractive index layer)

[0087] A high refractive index layer 36 is formed on a low refractive index layer 34. That is, in this embodiment, a low refractive index layer 34 and a high refractive index layer 36 are sequentially stacked on the inner surface 30a of the substrate 30, starting from the substrate 30 side, and on the outer surface 30b of the substrate 30, also sequentially stacked from the substrate 30 side. Hereinafter, the surface of the low refractive index layer 34 opposite to the substrate 30 is designated as surface 34a, the substrate 30 side surface of the low refractive index layer 34 is designated as surface 34b, the surface of the high refractive index layer 36 opposite to the substrate 30 is designated as surface 36a, and the substrate 30 side surface of the high refractive index layer 36 is designated as surface 36b. In this embodiment, the surface 36b of the high refractive index layer 36 adheres to the surface 34a of the low refractive index layer 34, and the surface 36a opposite to the surface 36b of the high refractive index layer 36 is exposed to the outside.

[0088] The high refractive index layer 36 has a higher refractive index for light with a wavelength of 10 μm than the low refractive index layer 34. The refractive index of the high refractive index layer 36 for light with a wavelength of 10 μm is preferably 1.5 or higher and 4.3 or lower, more preferably 1.7 or higher and 4.3 or lower, more preferably 2 or higher, and even more preferably 2.0 or higher and 3.8 or lower. Furthermore, the average refractive index of the high refractive index layer 36 for light with a wavelength of 8 μm or higher and 12 μm or lower is higher than the average refractive index of the low refractive index layer 34 for light with a wavelength of 8 μm or higher and 12 μm or lower. The average refractive index of the high refractive index layer 36 for light with wavelengths from 8 μm to 12 μm is preferably 1.5 or higher and 4.3 or lower, more preferably 1.7 or higher and 4.3 or lower, more preferably 2 or higher, and even more preferably 2.0 or higher and 3.8 or lower. By keeping the refractive index and average refractive index within this range, the reflection of far-infrared rays can be appropriately suppressed, while simultaneously reducing the thickness of the functional film 32.

[0089] Furthermore, the thickness d2 of the high refractive index layer 36 is preferably 0.1 μm or more and 2 μm or less, more preferably 0.2 μm or more and 1.5 μm or less, and even more preferably 0.3 μm or more and 1.2 μm or less. With a thickness d2 within this range, the reflection of far-infrared rays can be appropriately suppressed, while simultaneously reducing the thickness of the functional film 32. It should be noted that the thickness d2 can also be described as the length in the Z direction from the surface 36a of the high refractive index layer 36 to the opposite surface 36b.

[0090] Here, the refractive index of the high refractive index layer 36 for light with a wavelength of 10 μm is defined as refractive index n2, and the product of the refractive index n2 and the thickness d2 of the high refractive index layer 36 is defined as the optical film thickness n2d2. In this case, the optical film thickness n2d2 of the high refractive index layer 36 for light with a wavelength of 10 μm is preferably 0.2 μm or more and 2.5 μm or less, more preferably 0.3 μm or more and 2.2 μm or less, and even more preferably 0.3 μm or more and 2.0 μm or less. In addition, the average optical film thickness of the high refractive index layer 36 is preferably 0.2 μm or more and 2.5 μm or less, more preferably 0.3 μm or more and 2.2 μm or less, and even more preferably 0.3 μm or more and 2.0 μm or less, wherein the average optical film thickness is the product of the average refractive index of the high refractive index layer 36 for light with a wavelength of 8 μm to 12 μm and the thickness d2. By controlling the optical film thickness n2d2 and the average optical film thickness within this range, the reflection of far-infrared rays can be appropriately suppressed, while the film thickness of the functional film 32 can be reduced.

[0091] The high refractive index layer 36 is capable of transmitting far-infrared radiation. The extinction coefficient of the high refractive index layer 36 for light with a wavelength of 10 μm is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.02 or less. The average extinction coefficient of the high refractive index layer 36 for light with wavelengths of 8 μm to 12 μm is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.02 or less. With the extinction coefficient and average extinction coefficient within this range, far-infrared radiation can be appropriately transmitted.

[0092] The material of the high refractive index layer 36 is arbitrary, but preferably contains materials selected from Ge, Si, and NiO. x CuO x At least one material from the group consisting of Y₂O₃, ZnS, Bi₂O₃, ZrO₂, ZnO, and diamond-like carbon. By using such a material, the high refractive index layer 36 appropriately transmits far-infrared rays, and having a high refractive index for far-infrared rays, it is able to appropriately suppress the reflection of far-infrared rays.

[0093] To protect the low-refractive-index layer 34 from water, the high-refractive-index layer 36 preferably has water-blocking properties. The water-blocking performance of the high-refractive-index layer 36 varies depending on the material, crystal structure, and film thickness. For example, from a water-blocking perspective, the high-refractive-index layer 36 preferably contains materials selected from NiO. x It is at least one material selected from the group consisting of ZnS, ZrO2, and diamond-like carbon. Furthermore, from the viewpoint of water resistance, the high refractive index layer 36 is preferably an amorphous structure.

[0094] (As a characteristic of functional membranes)

[0095] The functional film 32 is a laminate obtained by stacking the low-refractive-index layer 34 and the high-refractive-index layer 36 as described above. By alternately stacking the low-refractive-index layer 34 and the high-refractive-index layer 36, the functional film 32 can function appropriately as an AR film. Furthermore, by sequentially stacking the low-refractive-index layer 34 and the high-refractive-index layer 36 from the substrate 30 side, the functional film 32 can appropriately reduce reflectivity while reducing the film thickness.

[0096] Here, in the functional film 32, the total optical film thickness is defined as the sum of the optical film thickness of a low-refractive-index layer 34 and the optical film thickness of a high-refractive-index layer 36 that contacts the low-refractive-index layer 34 on the side opposite to the substrate 30. That is, when N is set to any positive integer, the total optical film thickness refers to the sum of the optical film thickness of the Nth low-refractive-index layer 34 and the optical film thickness of the (N+1)th high-refractive-index layer 36 from the substrate 30. In this case, the total optical film thickness is preferably less than 1 / 4 of the wavelength of the light being targeted. For example, for light with a wavelength of 10 μm, the total optical film thickness is preferably 0.3 μm or more and 2.5 μm or less, more preferably 0.5 μm or more and 2.3 μm or less, and even more preferably 1.0 μm or more and 2.2 μm or less. Within this range, the reflection of far-infrared rays can be appropriately suppressed. It should be noted that, in this embodiment, since the functional film 32 has a low-refractive-index layer 34 and a high-refractive-index layer 36 stacked on top of each other, the sum of the optical film thickness of the low-refractive-index layer 34 and the optical film thickness of the high-refractive-index layer 36 is the total optical film thickness of the functional film 32. Furthermore, in the case where multiple low-refractive-index layers 34 and multiple high-refractive-index layers 36 are stacked as in other examples described later, it is preferable that the total optical film thickness of each pair of low-refractive-index layers 34 and high-refractive-index layers 36 satisfies the above-mentioned range. Additionally, in the case where only a low-refractive-index layer 34 is stacked as in other examples described later, the optical film thickness of the low-refractive-index layer 34 is the total optical film thickness of the functional film 32.

[0097] Furthermore, in the functional film 32, the average total optical film thickness is defined as the sum of the average optical film thickness of a low-refractive-index layer 34 for light with wavelengths of 8 μm to 12 μm and the average optical film thickness of a high-refractive-index layer 36, which is in contact with the low-refractive-index layer 34 on the side opposite to the substrate 30. In this case, the average total optical film thickness is preferably 0.3 μm or more and 2.5 μm or less, more preferably 0.5 μm or more and 2.3 μm or less, and even more preferably 1.0 μm or more and 2.2 μm or less. With an average total optical film thickness within this range, the reflection of far-infrared rays can be appropriately suppressed. It should be noted that, in this embodiment, since the functional film 32 has a low-refractive-index layer 34 and a high-refractive-index layer 36 stacked together, the sum of the average optical film thickness of the low-refractive-index layer 34 and the average optical film thickness of the high-refractive-index layer 36 is the average total optical film thickness. Furthermore, in the case where multiple layers of low-refractive-index layers 34 and multiple layers of high-refractive-index layers 36 are stacked, as in other examples described later, it is preferable that the average total optical film thickness of each pair of low-refractive-index layers 34 and high-refractive-index layers 36 satisfies the above-mentioned range. Additionally, in the case where only low-refractive-index layers 34 are stacked, as in other examples described later, the average optical film thickness of the low-refractive-index layers 34 is equal to the average total optical film thickness of the functional films 32.

[0098] (Characteristics of far-infrared transmission components)

[0099] As described above, the far-infrared transmission member 20 has a functional film 32 formed on the surface of the substrate 30. By forming the functional film 32 on the surface of the substrate 30, the far-infrared transmission member 20 can suppress the reflection of far-infrared rays, thereby enabling appropriate transmission of far-infrared rays.

[0100] The far-infrared transmission member 20 preferably has a reflectance of 10 μm light of 10% or less, more preferably 5% or less, and even more preferably 3% or less. Furthermore, the average reflectance of the far-infrared transmission member 20 for light with wavelengths of 8 μm to 12 μm is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less. With reflectance and average reflectance within this range, it is possible to appropriately perform the function of a far-infrared transmission member. It should be noted that average reflectance refers to the average value of the reflectance of light at each wavelength in this band (here, 8 μm to 12 μm). Reflectance can be measured, for example, using a Fourier transform infrared spectrometer (manufactured by Thermo Scientific, Nicolet iS10).

[0101] Furthermore, the transmittance of the far-infrared transmission member 20 varies depending on the internal transmittance τ of the substrate 30 used. The transmittance of the far-infrared transmission member 20 for light with a wavelength of 10 μm is preferably (τ-20)% or more, more preferably (τ-10)% or more, and even more preferably (τ-5)% or more. Additionally, the average transmittance of the far-infrared transmission member 20 for light with a wavelength of 8 μm to 12 μm is preferably (τ-15)% or more, more preferably (τ-10)% or more, and even more preferably (τ-5)% or more. Within this range of transmittance and average transmittance, it is possible to appropriately perform the function of a far-infrared transmission member. It should be noted that the average transmittance refers to the average value of the transmittance of light at each wavelength in this band (here, 8 μm to 12 μm). The transmittance can be measured, for example, using a Fourier transform infrared spectrometer (manufactured by Thermo Scientific, Nicolet iS10).

[0102] In addition, preferred options include Figure 3The outer surface of the far-infrared transmission member 20 shown is formed flush (continuously) with the outer surface of the light-shielding area A2. In other words, it is installed so that the outer surface 20A of the far-infrared transmission member 20 is continuous with the surface 12A of the glass substrate 12. By making the surface 20A of the far-infrared transmission member 20 continuous with the surface 12A of the glass substrate 12 in this way, it is possible to suppress damage to the wiping effect of the wipers. In addition, it is possible to suppress the possibility of compromising the design of the vehicle V due to height differences, and the accumulation of sand and dust at height differences. Furthermore, the far-infrared transmission member 20 is preferably formed in accordance with the curved shape of the vehicle glass 1 to which it is applied. There are no particular limitations on the forming method of the far-infrared transmission member 20, and grinding or die forming can be selected depending on the curved shape and the component.

[0103] There are no particular limitations on the shape of the far-infrared transmission member 20, but a plate-like shape consistent with the shape of the opening 19 is preferred. That is, for example, if the opening 19 is circular, the far-infrared transmission member 20 is preferably cylindrical. Furthermore, from an aesthetic design perspective, the surface shape of the far-infrared transmission member 20 on the outer side of the vehicle can be machined to match the curvature of the outer surface of the glass substrate 12. Moreover, for reasons such as balancing a wide-angle view of the far-infrared camera CA1 and improved mechanical properties, the far-infrared transmission member 20 can be made into a lens shape. When such a structure is made, far-infrared rays can be effectively focused even with a small area of ​​the far-infrared transmission member 20, which is therefore preferable. In this case, the number of lens-shaped far-infrared transmission members 20 is preferably 1 to 3, typically preferably 2. Furthermore, the lens-shaped far-infrared transmission member 20 is particularly preferably pre-aligned and modularized, and integrated with the housing or bracket that adhesively bonds the far-infrared camera CA1 to the vehicle glass 1.

[0104] In the vehicle glass 1 of this embodiment, it is preferable to have a structure in which the area of ​​the opening 19 on the inner side of the vehicle is smaller than the area of ​​the opening 19 on the outer side of the vehicle, and the shape of the far-infrared transmission member 20 is also such that the area of ​​the inner side of the vehicle is smaller than the area of ​​the outer side of the vehicle. By making such a structure, the strength against impacts from the outside of the vehicle is improved. Furthermore, in the case where the vehicle glass 1 of this embodiment is a laminated glass having a glass substrate 12 (outer side of the vehicle) and a glass substrate 14 (inner side of the vehicle), the opening 19 is formed by overlapping the opening 12a of the glass substrate 12 and the opening 14a of the glass substrate 14. In this case, the area of ​​the opening 12a of the glass substrate 12 can be larger than the area of ​​the opening 14a of the glass substrate 14, and the far-infrared transmission member 20, which has the same size as the opening 12a of the glass substrate 12, is disposed in the opening 12a of the glass substrate 12.

[0105] From a strength perspective, the thickness of the far-infrared transmission member 20 is preferably 1.5 mm or more, more preferably 2.0 mm or more, and even more preferably 3.0 mm or more. There is no particular upper limit to the thickness of the far-infrared transmission member 20, and it is typically 5.0 mm or less. Here, thickness refers to the length of the far-infrared transmission member 20 in the Z direction.

[0106] In addition, such as Figure 3 As shown, in the far-infrared transmission member 20, the length D1 of the longest straight line connecting any two points on the outer surface of the vehicle is preferably 80 mm or less. More preferably, the length D1 is 70 mm or less, and even more preferably 65 mm or less. Furthermore, the length D1 is preferably 60 mm or more. Additionally, as... Figure 3 As shown, in the opening 19 of the far-infrared transmission region B, the length D2 of the longest straight line connecting any two points on the outer surface of the vehicle is preferably 80 mm or less. More preferably, the length D2 is 70 mm or less, and even more preferably 65 mm or less. Furthermore, the length D2 is preferably 60 mm or more. The length D2 can also be described as the length of the longest straight line connecting any two points on the outer periphery of the opening 19 on the outer surface (surface 12A) of the vehicle glass 1. With the length D1 of the far-infrared transmission member 20 and the length D2 of the opening 19 within this range, the reduction in the strength of the vehicle glass 1 can be suppressed, and the perspective distortion around the opening 19 can also be suppressed. It should be noted that when the shape of the outer surface of the far-infrared transmission member 20 is circular, the lengths D1 and D2 are lengths equivalent to the diameter of the outer surface of the vehicle. Furthermore, the lengths D1 and D2 here refer to the lengths when the vehicle glass 1 is mounted on the vehicle V. For example, if the glass is bent to form a shape that is mounted on the vehicle V, then the lengths D1 and D2 are the lengths in the bent state. The same applies to the descriptions of dimensions and positions other than lengths D1 and D2 unless otherwise specified.

[0107] (Manufacturing method of infrared transmission component)

[0108] Next, the manufacturing method of the far-infrared transmission member 20 will be described. In manufacturing the far-infrared transmission member 20, a substrate 30 is prepared, and a low-refractive-index layer 34 is formed on the surface of the substrate 30. In this embodiment, the low-refractive-index layer 34 is formed on the surface of the substrate 30 by sputtering. Then, a high-refractive-index layer 36 is formed on the surface of the low-refractive-index layer 34 formed on the substrate 30 by sputtering. Thus, the far-infrared transmission member 20 is manufactured. By using sputtering to form the low-refractive-index layer 34 and the high-refractive-index layer 36, the adhesion of the film can be improved. However, the manufacturing method of the far-infrared transmission member 20 is not limited to this. For example, the low-refractive-index layer 34 and the high-refractive-index layer 36 are not limited to being formed by sputtering; they can also be formed by, for example, vapor deposition. Since the low-refractive-index layer 34 is mainly composed of oxides, its formation method is not limited to vapor deposition like that of fluorides, and it can be formed using various methods. In particular, forming it by sputtering can improve productivity and film adhesion.

[0109] (Another example of this implementation)

[0110] In this embodiment, the functional film 32 has a structure consisting of a low-refractive-index layer 34 and a high-refractive-index layer 36 stacked together, but it is not limited to this. Other stacking examples of the functional film 32 will be described below.

[0111] Figure 6 This is a cross-sectional schematic diagram of another example of a far-infrared transmission component in this embodiment. Figure 6 As shown, the functional film 32 can be stacked with multiple layers of low-refractive-index layers 34 and multiple layers of high-refractive-index layers 36. In this case, in the functional film 32, starting from the substrate 30 side, the low-refractive-index layers 34 and high-refractive-index layers 36 are stacked alternately in the order of low-refractive-index layer 34, high-refractive-index layer 36, low-refractive-index layer 34, ..., forming a high-refractive-index layer 36 on the surface of the functional film 32 opposite to the substrate 30. In other words, in the functional film 32, the low-refractive-index layers 34 and high-refractive-index layers 36 are stacked alternately with the side closest to the substrate 30 being the low-refractive-index layer 34 and the side furthest from the substrate 30 opposite to the substrate 30 being the high-refractive-index layer 36. By stacking multiple layers of low-refractive-index layers 34 and multiple layers of high-refractive-index layers 36 in this way, the reflectivity of light over a wider wavelength range can be suppressed.

[0112] It should be noted that, in cases such as Figure 6In the case of multiple layers of low-refractive-index layers 34 and multiple layers of high-refractive-index layers 36, it is preferable that each low-refractive-index layer 34 is made of the same material. On the other hand, each high-refractive-index layer 36 does not have to be made of the same material, and a film with excellent durability can be selected as the outermost layer. For example, a high-hardness film such as diamond-like carbon, which has durability for wiping wipers, can be disposed on the outermost layer, or a film of a material with excellent water-resistant properties can be disposed on the outermost layer as described above.

[0113] Figure 7 This is a cross-sectional schematic diagram of another example of a far-infrared transmission component in this embodiment. Figure 7 As shown, the functional film 32 can be formed only by the low refractive index layer 34, without forming the high refractive index layer 36.

[0114] It should be noted that, since MgO is hygroscopic, when only the low refractive index layer 34 is formed, the low refractive index layer 34 preferably contains a secondary component for improving water resistance. As mentioned above, this secondary component preferably includes components selected from NiO. x CuO x At least one material from the group consisting of ZnO, ZrO2, Bi2O3 and Y2O3.

[0115] Figure 8 This is a cross-sectional schematic diagram of another example of a far-infrared transmission component in this embodiment. Figure 8 As shown, the far-infrared transmission component 20 is formed between the substrate 30 and the functional film 32; in other words, an adhesion film 38 is formed between the substrate 30 and the low-refractive-index layer 34. That is, in the above embodiment, the low-refractive-index layer 34 and the substrate 30 are directly adhered, but they can also be bonded together through the adhesion film 38, as in this example. It should be noted that in Figure 8 In the example, for ease of explanation, the functional film 32 is shown as a stack of a low refractive index layer 34 and a high refractive index layer 36, but it is not limited to this and can be any of the stacked structures described above.

[0116] (Adhesive film)

[0117] The adhesive film 38 is a film that enables the substrate 30 and the low refractive index layer 34 to adhere together. In other words, the adhesive film 38 is a film that improves the adhesive strength between the substrate 30 and the low refractive index layer 34.

[0118] The refractive index of the adhesive film 38 for light with a wavelength of 10 μm is preferably 1.0 or higher and 4.3 or lower, more preferably 1.5 or higher and 4.3 or lower, and even more preferably 1.5 or higher and 3.8 or lower. Furthermore, the average refractive index of the adhesive film 38 for light with wavelengths of 8 μm to 12 μm is preferably 1.0 or higher and 4.3 or lower, more preferably 1.5 or higher and 4.3 or lower, and even more preferably 1.5 or higher and 3.8 or lower. By having the refractive index and average refractive index within this range, the reflection of far-infrared rays can be appropriately suppressed.

[0119] Furthermore, the thickness d3 of the adhesive film 38 is preferably 0.05 μm or more and 0.5 μm or less, more preferably 0.05 μm or more and 0.3 μm or less, and even more preferably 0.05 μm or more and 0.1 μm or less. With a thickness d3 within this range, far-infrared reflection can be appropriately suppressed, while ensuring proper adhesion between the substrate 30 and the low-refractive-index layer 34. It should be noted that the thickness d3 can also be described as the length in the Z direction from surface 38a of the adhesive film 38 to the opposite surface 38b. Additionally, the thickness d3 of the adhesive film 38 is preferably thinner than the thickness d1 of the low-refractive-index layer 34 and the thickness d2 of the high-refractive-index layer 36. By ensuring that the thickness d3 of the adhesive film 38 is thinner than the thicknesses of these layers, the impact on optical performance can be reduced.

[0120] The adhesive film 38 is capable of transmitting far-infrared rays. The extinction coefficient of the adhesive film 38 for light with a wavelength of 10 μm is preferably 0.4 or less, more preferably 0.2 or less, and even more preferably 0.1 or less. The average extinction coefficient of the adhesive film 38 for light with wavelengths of 8 μm to 12 μm is preferably 0.4 or less, more preferably 0.2 or less, and even more preferably 0.1 or less. With the extinction coefficient and average extinction coefficient within this range, far-infrared rays can be appropriately transmitted.

[0121] The material of the adhesion film 38 is arbitrary, but preferably contains materials selected from Si, Ge, MgO, and NiO. x CuO x At least one material selected from the group consisting of ZnS, Al2O3, ZrO2, SiO2, TiO2, ZnO, and Bi2O3. The adhesive film 38, by using such a material, enables the substrate 30 and the low-refractive-index layer 34 to be properly adhered.

[0122] It should be noted that, like the low refractive index layer 34, the adhesion film 38 can also be formed by sputtering, but is not limited to this; for example, it can also be formed by vapor deposition.

[0123] Figure 9 This is a cross-sectional schematic diagram of another example of a far-infrared transmission component in this embodiment. Figure 9As shown, the far-infrared transmission component 20 has a bandpass forming film 42 formed between the substrate 30 and the functional film 32; in other words, it has a bandpass forming film 42 formed between the substrate 30 and the low refractive index layer 34. That is, in the above embodiment, only the functional film 32 is formed on the substrate 30, but a bandpass forming film 42 can also be formed between the low refractive index layer 34 and the substrate 30, as in this example. It should be noted that... Figure 9 In the example, for ease of explanation, the functional film 32 is shown as a stack of a low refractive index layer 34 and a high refractive index layer 36, but it is not limited to this and can be any of the stacked structures described above.

[0124] The bandpass forming film 42 serves to expand the transmission wavelength range and form a bandpass. For example... Figure 9 As shown, the bandpass forming film 42 has an intermediate refractive index layer 44 and a high refractive index layer 46.

[0125] exist Figure 9 In this example, intermediate refractive index layer 44 and high refractive index layer 46 are alternately stacked. Figure 9 In the example, the bandpass forming film 42 has an intermediate refractive index layer 44 and a high refractive index layer 46 sequentially stacked on the substrate 30 in a direction away from the substrate 30. However, in the bandpass forming film 42, the layer formed on the side closest to the substrate 30 is not limited to the intermediate refractive index layer 44, but can be, for example, the high refractive index layer 46. For example, the high refractive index layer 46 and the intermediate refractive index layer 44 can be sequentially stacked in a direction away from the substrate 30.

[0126] In addition, Figure 9 In the example, the bandpass forming film 42 has a structure consisting of a single intermediate refractive index layer 44 and a single high refractive index layer 46, but it is not limited to this; at least one of multiple intermediate refractive index layers 44 and high refractive index layers 46 may also be stacked. For example, the bandpass forming film 42 may have multiple intermediate refractive index layers 44 and multiple high refractive index layers 46 alternately stacked on the substrate 30 in a direction away from the substrate 30. That is, the substrate 30, intermediate refractive index layer 44, high refractive index layer 46, intermediate refractive index layer 44, ..., high refractive index layer 46 may be stacked sequentially. Alternatively, the bandpass forming film 42 may also have multiple high refractive index layers 46 and multiple intermediate refractive index layers 44 alternately stacked on the substrate 30 in a direction away from the substrate 30. That is, the substrate 30, high refractive index layer 46, intermediate refractive index layer 44, high refractive index layer 46, ..., intermediate refractive index layer 44 may be stacked sequentially.

[0127] Furthermore, the bandpass forming film 42 can be a structure containing a high refractive index layer 46 but not an intermediate refractive index layer 44. It can be said that the bandpass forming film 42 is characterized by having at least one or more high refractive index layers 46. That is, the bandpass forming film 42 can be a single-layer film composed of a single high refractive index layer 46, or it can be a multilayer film obtained by stacking a high refractive index layer 46 and an intermediate refractive index layer 44.

[0128] The high refractive index layer 46 is a layer whose refractive index for far-infrared light is higher than that for the low refractive index layer 34 of the functional film 32. The properties and materials of the high refractive index layer 46 can be the same as those of the high refractive index layer 36 of the functional film 32, so detailed descriptions are omitted.

[0129] (Intermediate refractive index layer)

[0130] The intermediate refractive index layer 44 has a higher refractive index for light with a wavelength of 10 μm than the low refractive index layer 34, but lower than the high refractive index layers 36 and 46. The refractive index of the intermediate refractive index layer 44 for light with a wavelength of 10 μm is preferably 1.5 or higher and 3.5 or lower, more preferably 1.7 or higher and 3.0 or lower, and even more preferably 2.0 or higher and 2.5 or lower. Furthermore, the average refractive index of the intermediate refractive index layer 44 for light with a wavelength of 8 μm or higher and 12 μm or lower is higher than the average refractive index of the low refractive index layer 34 for light with a wavelength of 8 μm or higher and 12 μm or lower, but lower than the average refractive index of the high refractive index layers 36 and 46 for light with a wavelength of 8 μm or higher and 12 μm or lower. The average refractive index of the intermediate refractive index layer 44 for light with wavelengths of 8 μm to 12 μm is preferably 1.5 or higher and 3.5 or lower, more preferably 1.7 or higher and 3.0 or lower, and even more preferably 2.0 or higher and 2.5 or lower. By having the refractive index and average refractive index within this range, the intermediate refractive index layer 44 and the high refractive index layer 46 can be stacked together to function appropriately as an optical bandpass filter.

[0131] Furthermore, the thickness of the intermediate refractive index layer 44 is preferably 0.1 μm or more and 2.5 μm or less, more preferably 0.2 μm or more and 2.2 μm or less, and even more preferably 0.3 μm or more and 2.0 μm or less. With the thickness of the intermediate refractive index layer 44 within this range, the stacking of the intermediate refractive index layer 44 and the high refractive index layer 46 allows it to function appropriately as an optical bandpass filter.

[0132] The intermediate refractive index layer 44 is capable of transmitting far-infrared radiation. The extinction coefficient of the intermediate refractive index layer 44 for light with a wavelength of 10 μm is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.02 or less. The average extinction coefficient of the intermediate refractive index layer 44 for light with wavelengths of 8 μm to 12 μm is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.02 or less. With the extinction coefficient and average extinction coefficient within this range, the layering of the intermediate refractive index layer 44 and the high refractive index layer 46 allows it to function appropriately as an optical bandpass filter.

[0133] The material of the intermediate refractive index layer 44 is arbitrary, but preferably contains materials selected from ZnS and NiO. x CuO x At least one material from the group consisting of Y₂O₃, Bi₂O₃, ZrO₂, ZnO, and diamond-like carbon. The intermediate refractive index layer 44, by using such a material and through the stacking of the intermediate refractive index layer 44 with the high refractive index layer 46, can function appropriately as an optical bandpass filter.

[0134] (Effect)

[0135] As explained above, the far-infrared transmission member 20 of this embodiment includes a far-infrared transmission substrate 30 and a functional film 32. The functional film 32 is formed on the substrate 30 and includes a low-refractive-index layer 34, which is mainly composed of oxides and has a refractive index of 1.5 or less for light with a wavelength of 10 μm. The low-refractive-index layer 34 is mainly composed of MgO, and the content of MgO relative to the entire low-refractive-index layer 34 is 50% by mass or more and 100% by mass or less. By including a low-refractive-index layer 34 with a low refractive index for light with a wavelength of 10 μm and MgO as the main component, the far-infrared transmission member 20 can reduce the film thickness of the low-refractive-index layer 34 and impart appropriate anti-reflection properties. In addition, since the low-refractive-index layer 34 is mainly composed of MgO, the adhesion can be improved or the options for the formation process can be expanded. Therefore, according to this far-infrared transmission member 20, the reflection of far-infrared rays can be appropriately suppressed, and an anti-reflection film can be appropriately formed. In addition, by setting the main component of the low refractive index layer 34 to MgO, it is possible to provide a film that is transparent to far-infrared light and has a low refractive index.

[0136] Furthermore, the average refractive index of the low-refractive-index layer 34 for light with wavelengths of 8 μm or more and 12 μm or less is preferably 0.8 or more and 1.5 or less. Therefore, this far-infrared transmission member 20 can reduce the film thickness of the low-refractive-index layer 34 while imparting appropriate anti-reflection properties.

[0137] Furthermore, the optical film thickness n1d1 of the low refractive index layer 34 is preferably 0.1 μm or more and 2.5 μm or less, where the optical film thickness n1d1 is the product of the refractive index n1 of the low refractive index layer 34 for light with a wavelength of 10 μm and its thickness d1. Therefore, this far-infrared transmission member 20 can reduce the film thickness of the low refractive index layer 34 while imparting appropriate anti-reflection properties.

[0138] Furthermore, the extinction coefficient of the low refractive index layer 34 for light with a wavelength of 10 μm is preferably 0.1 or less. With the extinction coefficient of the low refractive index layer 34 within this range, the far-infrared transmission member 20 can appropriately transmit far-infrared rays.

[0139] Furthermore, the reflectivity of the far-infrared transmission member 20 to light with a wavelength of 10 μm is preferably 10% or less. With this far-infrared transmission member 20, far-infrared rays can be appropriately transmitted.

[0140] Furthermore, the average reflectance of the far-infrared transmission member 20 to light with wavelengths of 8 μm or more and 12 μm or less is preferably 10% or less. With this far-infrared transmission member 20, far-infrared rays can be appropriately transmitted.

[0141] Furthermore, the far-infrared transmission component 20 preferably also includes a high refractive index layer 36, which is formed on the side of the low refractive index layer 34 opposite to the substrate 30 side, and the high refractive index layer 36 has a higher refractive index for light with a wavelength of 10 μm than the low refractive index layer 34 for light with a wavelength of 10 μm. According to this far-infrared transmission component 20, by stacking the high refractive index layer 36 on the low refractive index layer 34, the reflectivity can be appropriately reduced while decreasing the film thickness.

[0142] Furthermore, the refractive index of the high-refractive-index layer 36 for light with a wavelength of 10 μm is preferably 2 or higher. According to this far-infrared transmission member 20, by stacking the high-refractive-index layer 36 on the low-refractive-index layer 34, the reflectivity can be appropriately reduced while decreasing the film thickness.

[0143] Furthermore, the total optical film thickness (n1d1) of the low-refractive-index layer 34 and the optical film thickness n2d2 of the high-refractive-index layer 36, which is in contact with the low-refractive-index layer 34 and located on the side opposite to the substrate 30, is preferably 0.1 μm or more and 2.5 μm or less. The optical film thickness n1d1 is the product of the refractive index n1 of the low-refractive-index layer 34 for light with a wavelength of 10 μm and its thickness d1, and the optical film thickness n2d2 is the product of the refractive index n2 of the high-refractive-index layer 36 for light with a wavelength of 10 μm and its thickness d2. By setting the total optical film thickness within this range, the reflectivity can be appropriately reduced while decreasing the film thickness.

[0144] In addition, the high refractive index layer 36 preferably contains materials selected from Ge, Si, and NiO.x CuO x At least one material from the group consisting of Y₂O₃, ZnS, Bi₂O₃, ZrO₂, ZnO, and diamond-like carbon. By using such a material as the high refractive index layer 36, the reflectivity can be appropriately reduced.

[0145] Furthermore, the far-infrared transmission member 20 may have an adhesion film 38 formed between the substrate 30 and the low-refractive-index layer 34 to allow the substrate 30 and the low-refractive-index layer 34 to adhere. By providing the adhesion film 38, the low-refractive-index layer 34 and the substrate 30 can be properly bonded.

[0146] In addition, the adhesion film 38 preferably contains materials selected from Si, Ge, MgO, and NiO. x CuO x At least one material selected from the group consisting of ZnS, Al2O3, ZrO2, SiO2, TiO2, ZnO, and Bi2O3. By setting the adhesion film 38 to such a material, the low refractive index layer 34 can be properly bonded to the substrate 30.

[0147] Furthermore, the substrate 30 preferably comprises at least one material selected from the group consisting of Si, Ge, ZnS, and chalcogenide glasses. By setting the substrate 30 to such a material, far-infrared rays can be appropriately transmitted.

[0148] Furthermore, the far-infrared transmission component 20 is preferably mounted on a vehicle. By mounting the far-infrared transmission component 20 on a vehicle, the performance of the vehicle-mounted far-infrared camera CA1 can be fully utilized.

[0149] Furthermore, the method for manufacturing the far-infrared transmission member 20 in this embodiment manufactures the far-infrared transmission member 20 by forming a functional film 32 on a far-infrared transmission substrate 30. The functional film 32 comprises a low-refractive-index layer 34 with oxide as its main component and a refractive index of 1.5 or less for light with a wavelength of 10 μm. According to this manufacturing method, a far-infrared transmission member 20 capable of appropriately suppressing the reflection of far-infrared rays can be manufactured, and an anti-reflection film can be appropriately formed.

[0150] Furthermore, the low refractive index layer 34 is preferably formed by sputtering in this manufacturing method. By using sputtering, the productivity of the low refractive index layer 34 and the adhesion of the film can be improved.

[0151] (Example)

[0152] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Tables 1 to 3 show the examples. In Tables 1 to 3, the units for thickness and total optical film thickness are nm.

[0153] [Table 1]

[0154]

[0155]

[0156]

[0157] (Example 1)

[0158] In Example 1, a far-infrared transmission component was fabricated by forming functional films on both sides of a substrate using magnetron sputtering. In Example 1, ZnS (multi-grade) was used as the substrate. The substrate thickness was set to 2 mm ± 0.1 mm. It should be noted that the thickness was measured using a digital vernier caliper (manufactured by Mitutoyo Corporation, CD-15CX). As the functional film, MgO was used as the low-refractive-index layer, and NiO was used... x As a high refractive index layer, the thickness d1 and refractive index n1 of the low refractive index layer, and the thickness d2 and refractive index n2 of the high refractive index layer are shown in Table 1. It should be noted that the refractive index here refers to the refractive index of light at 10 μm. Furthermore, the total optical film thickness, calculated as the sum of the optical film thickness n1d1 of the low refractive index layer and the optical film thickness n2d2 of the high refractive index layer, is shown in Table 1. The optical film thickness n1d1 is the product of the thickness d1 and refractive index n1 of the low refractive index layer, and the optical film thickness n2d2 is the product of the thickness d2 and refractive index n2 of the high refractive index layer. The thickness and refractive index were determined by fitting an optical model using polarized light information obtained from an infrared ellipsometer and a spectrophotometer obtained from a Fourier transform infrared spectrometer.

[0159] In Example 1, firstly, a Mg target and a substrate, serving as film-forming materials, are positioned opposite each other in a magnetron sputtering apparatus. Next, the entire apparatus is evacuated to a vacuum. Then, when the pressure inside the apparatus reaches 5 × 10⁻⁴ Pa, argon and oxygen are flowed through at a combined rate of 300 SCCM (standard cc / min, 1 atmosphere (25°C)). The evacuation rate is adjusted to maintain a pressure of 0.5 Pa within the apparatus at this point. Then, a 2000 W DC pulsed current (20 kHz) is applied to the target surface, thereby forming an MgO film on the surface of the substrate.

[0160] Next, NiO is prepared as a film-forming material. x Target and substrate. Argon and oxygen are flowed through the device at a combined rate of 300 SCCM. The exhaust rate is adjusted to maintain a pressure of 0.5 Pa within the apparatus. Then, a 3000 W DC pulsed current (20 kHz) is applied to the target surface, thereby forming NiO on the substrate surface. x membrane.

[0161] (Example 2)

[0162] In Example 2, a far-infrared transmission component was fabricated by forming functional films on both sides of a substrate using magnetron sputtering. The high-refractive-index layer was made of Si, and a Si target was used as the film-forming material. Argon was used as the gas for film formation, and the thicknesses of the low-refractive-index layer and the high-refractive-index layer were set as shown in Table 1. Otherwise, the far-infrared transmission component was prepared using the same method as in Example 1.

[0163] (Example 3)

[0164] In Example 3, functional films were formed on both sides of a substrate using vapor deposition and plasma CVD, respectively, to fabricate a far-infrared transmission component. The material of the high-refractive-index layer was set to diamond-like carbon (DLC), and the thicknesses of the low-refractive-index layer and the high-refractive-index layer were set as shown in Table 1. MgO was formed by vapor deposition, and the DLC film was formed by plasma CVD. Otherwise, the far-infrared transmission component was prepared using the same method as in Example 1.

[0165] (Example 4)

[0166] In Example 4, a far-infrared transmission component was fabricated by forming functional films on both sides of a substrate using a vapor deposition method. The structure of the functional films was set to consist of Ge and ZnS as high-refractive-index layers, and no low-refractive-index layer was used. Furthermore, the thickness of the functional films was set as shown in Table 1, and the far-infrared transmission component was prepared using the same method as in Example 1.

[0167] (Example 5)

[0168] In Example 5, a far-infrared transmission component was fabricated by forming functional films on both sides of a substrate using a vapor deposition method. The material of the first layer was set to MgF2, the material of the high-refractive-index layer as the second layer was set to ZnS, the thickness of the functional film was set to the thickness shown in Table 1, and the first layer was formed by vapor deposition. Otherwise, the far-infrared transmission component was prepared using the same method as in Example 4.

[0169] (Example 6)

[0170] In Example 6, functional films were formed on both sides of a substrate using vapor deposition and plasma CVD, respectively, to fabricate a far-infrared transmission component. The material of the low-refractive-index layer was set to MgO, and the material of the high-refractive-index layer was set to ZnS and diamond-like carbon (DLC). The thicknesses of the low-refractive-index layer and the high-refractive-index layer were set as shown in Table 1. Otherwise, the far-infrared transmission component was prepared using the same method as in Examples 3 and 4.

[0171] (Example 7)

[0172] In Example 7, a far-infrared transmission component was fabricated by forming functional films on both sides of a substrate using magnetron sputtering. A Si (FZ grade) substrate with a thickness of 2 mm ± 0.1 mm was used as the substrate. The low-refractive-index layer was made of MgO, and the high-refractive-index layer was made of NiO. x Furthermore, the thicknesses of the low-refractive-index layer and the high-refractive-index layer were set to the thicknesses shown in Table 1. Otherwise, a far-infrared transmission component was prepared using the same method as in Example 1.

[0173] (Example 8)

[0174] In Example 8, no functional film was formed, and a substrate made of ZnS was prepared.

[0175] (Example 9)

[0176] In Example 9, no functional film was formed, and a substrate made of Si was prepared.

[0177] (Example 10)

[0178] In Example 10, a far-infrared transmission component was fabricated by forming MgO as a low-refractive-index layer on both sides of a substrate using magnetron sputtering. For the MgO, a different sputtering apparatus than in Example 1 was used, with argon and oxygen gas set to a total of 15 SCCM, a DC pulse current of 400 W (20 kHz) applied to the target surface, and the low-refractive-index layer set as shown in Table 1. Otherwise, the far-infrared transmission component was prepared using the same method as in Example 1.

[0179] (Example 11)

[0180] In Example 11, a far-infrared transmission component was fabricated by forming functional films on both sides of a substrate using magnetron sputtering. The functional films consist only of MgO and NiO, which are low-refractive-index layers. x A mixed film of MgO and NiO. x The hybrid film was formed by depositing a pure Ni sheet on a Mg target. The low refractive index layer was set as shown in Table 1. Otherwise, a far-infrared transmission component was prepared using the same method as in Example 10. In Example 11, the atomic percentage of Ni in the low refractive index layer relative to the total atomic percentage of Ni and Mg was 11.7 atoms.

[0181] (Example 12)

[0182] The difference between Example 12 and Example 1 is that Si is formed as an adhesion film between the functional film and the substrate. In Example 12, the adhesion film is formed on the substrate using magnetron sputtering, and an anti-reflection film is formed on the adhesion film using magnetron sputtering. Furthermore, in Example 12, the thicknesses of the functional film and the adhesion film are set as shown in Table 2. In addition, a far-infrared transmission component is prepared using the same method as in Example 1.

[0183] (Example 13)

[0184] In Example 13, the infrared transmission performance when a bandpass forming film is formed between the functional film and the substrate was calculated using optical simulation. The high refractive index layer of the bandpass forming film was set to Ge, and the intermediate refractive index layer was set to ZnS. Six layers of Ge and ZnS films were alternately arranged from the substrate. The low refractive index layer of the functional film was set to MgO, and the high refractive index layer was set to ZnS. The functional film was then placed on top of the bandpass forming film. The optical constants of the bandpass forming film and the functional film were obtained using vapor deposition, and the thicknesses of the functional film and the bandpass forming film are shown in Table 3. The optical simulation was performed using simulation software (TFCalc, manufactured by Hulinks Co., Ltd.).

[0185] (Total optical film thickness)

[0186] As shown in Tables 1 to 3, the total optical film thickness of Example 4 is greater than 2.5 μm. It should be noted that the thickness and refractive index were determined by fitting an optical model using polarized light information obtained from an infrared ellipsometer and a spectrophotometer obtained from a Fourier transform infrared spectroscopy device.

[0187] (Evaluation of optical performance)

[0188] The optical properties of the samples from Examples 1 to 12 were evaluated. As optical properties, the average transmittance and average reflectance of the samples were measured using a Fourier transform infrared spectrometer (manufactured by Thermo Scientific, trade name: Nicolet iS10). Average transmittance was the average transmittance for light of various wavelengths from 8 μm to 12 μm, and average reflectance was the average reflectance for light of various wavelengths from 8 μm to 12 μm. If both average transmittance and average reflectance were acceptable, the evaluation result was indicated as "0"; if at least one of average transmittance and average reflectance was unacceptable, the evaluation result was indicated as "×". Regarding average reflectance, values ​​below 10% were considered acceptable, and values ​​above 10% were considered unacceptable. Furthermore, since average transmittance varies depending on the internal transmittance τ of the substrate, values ​​above (τ-10)% were considered acceptable, and values ​​below (τ-10)% were considered unacceptable. Specifically, when the substrate is ZnS, a transmittance of 87% or higher is considered acceptable, while a transmittance of less than 87% is considered unacceptable. Furthermore, regarding the average transmittance when the substrate is Si, a transmittance of 70% or higher is considered acceptable, while a transmittance of less than 70% is considered unacceptable.

[0189] For the sample in Example 13, the average transmittance and average reflectance were estimated based on the results of optical simulation.

[0190] The evaluation results of optical performance are shown in Tables 1 to 3. Examples 1 to 3, 6, 7, and 10 to 13 are examples, demonstrating that by using an oxide with MgO as the main component as the functional film, reflectivity can be suppressed, thereby increasing transmittance. Example 4 is a comparative example, showing that when a high refractive index film is used as the functional film, the average reflectivity cannot be sufficiently reduced, and the overall film thickness increases. Example 6 is a reference example, demonstrating that by using MgF2 as the functional film, reflectivity can be suppressed, thereby increasing transmittance. However, there are fewer options for the MgF2 formation process. In other words, by using an oxide as the functional film as in the examples, optical properties can be improved in the same way as with MgF2, while increasing the options for the formation process.

[0191] Figure 10 and Figure 11 A graph showing the evaluation results for each example. Figure 10 The graph shows the transmittance of light for each wavelength in Examples 1 to 6, i.e., when the substrate is ZnS. Figure 10 For example, the result for line segment La1 is 1; the result for line segment La2 is 2; the result for line segment La3 is 3; the result for line segment La4 is 4; the result for line segment La5 is 5; and the result for line segment La6 is 6. Figure 10As shown, it can be seen that Examples 1, 2, 3, and 6, which are examples of embodiments, can improve the overall transmittance in the 8μm to 12μm range of the far-infrared band compared with Example 4, which is a comparative example.

[0192] Figure 11 The graph shows the reflectance of light for each wavelength in Examples 1 to 6, i.e., when the substrate is ZnS. Figure 11 For example, the result for line segment Lb1 is 1; the result for line segment Lb2 is 2; the result for line segment Lb3 is 3; the result for line segment Lb4 is 4; the result for line segment Lb5 is 5; and the result for line segment Lb6 is 6. Figure 11 As shown, in Examples 1 to 5, the reflectivity was designed to be lowest at 10 μm, which is the target wavelength. However, it is evident that Examples 1, 2, 3, and 6, as embodiments, can reduce the overall reflectivity in the 8 μm to 12 μm range, which is the far-infrared band, compared to Example 4, which is a comparative example. In other words, the structure in which a low-refractive-index layer and a high-refractive-index layer are formed sequentially from the substrate can be considered an effective structure that can further reduce the average reflectivity near the target wavelength. In Example 6, the low-reflection band is broadened, which means that the anti-reflection band can be expanded by forming alternating layers of multilayer films.

[0193] (Evaluation of adhesion performance)

[0194] In addition, adhesion performance was evaluated. The adhesion performance evaluation involved a tape test, with a value of 0 for passing the test and 0 for failing. The tape test was performed as follows: using 18mm wide cellophane tape as shown in JIS Z1522, the tape was firmly adhered to the film-forming surface, and then peeled off while being pulled in a 90° direction.

[0195] The evaluation results of adhesion performance are shown in Tables 1 to 3. As shown in Tables 1 to 3, it can be seen that the adhesion is increased in Examples 1 to 3, 6, 7, and 10 to 12, which are examples. In addition, it can be seen that in Examples 4 and 5, the adhesion is decreased when Ge and MgF2 are formed by vapor deposition. That is, it can be seen that the adhesion can be improved by using an oxide as a low refractive index layer, and therefore it is more preferable.

[0196] (Evaluation of water resistance)

[0197] In addition, water resistance was evaluated as an optional assessment. In the evaluation of water resistance, a boiling test was performed; a passing result in the boiling test was indicated as 0, and a failing result was indicated as ×. The boiling test was performed by immersing the film-forming substrate in pure water at 100°C ± 3°C for 10 minutes. After the boiling test, any occurrence of film peeling or a change of more than 5% in the average transmittance of 8μm to 12μm was considered unacceptable. As shown in Examples 1, 3, 6, 7, and 12, forming a high-refractive-index film on the MgO film improved water resistance, which is arguably more preferable. Furthermore, as shown in Example 11, adding a minor component to the MgO film improved water resistance, which is arguably more preferable.

[0198] The embodiments of the present invention have been described above, but the embodiments are not limited to the content of these embodiments. Furthermore, the above-described constituent elements include elements readily conceived by those skilled in the art, substantially the same elements, and elements of so-called equivalent scope. Moreover, the above-described constituent elements can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the constituent elements can be made without departing from the spirit of the above-described embodiments.

[0199] Label Explanation

[0200] 1. Vehicle glass

[0201] 10, 12, 14 Glass substrate

[0202] 16 Intermediate Layers

[0203] 18. Light-shielding layer

[0204] 20 Far-infrared transmission components

[0205] 30 Substrate

[0206] 32 Functional Membranes

[0207] 34 Low Refractive Index Layer

[0208] 36 High Refractive Index Layer

Claims

1. A far-infrared transmission component, wherein, The far-infrared transmission component includes: Substrate that transmits far-infrared rays; and A functional film is formed on the substrate and includes a low refractive index layer consisting primarily of oxides and having a refractive index of 1.5 or less for light with a wavelength of 10 μm. The low-refractive-index layer has MgO as its main component, and the content of MgO relative to the entire low-refractive-index layer is more than 50% by mass and less than 100% by mass. The optical film thickness n1d1 of the low refractive index layer is greater than 0.1 μm and less than 2.5 μm. The optical film thickness n1d1 is the product of the refractive index n1 of the low refractive index layer for light with a wavelength of 10 μm and the thickness d1 of the low refractive index layer.

2. The far-infrared transmission component as described in claim 1, wherein, The low-refractive-index layer has an average refractive index of 0.8 or higher and 1.5 or lower for light with wavelengths above 8 μm and below 12 μm.

3. The far-infrared transmission component as described in claim 1 or claim 2, wherein, The extinction coefficient of the low refractive index layer for light with a wavelength of 10 μm is less than 0.

1.

4. The far-infrared transmission component as described in claim 1 or claim 2, wherein, The far-infrared transmission component has a reflectivity of less than 10% for light with a wavelength of 10 μm.

5. The far-infrared transmission component as described in claim 4, wherein, The far-infrared transmission component has an average reflectivity of less than 10% for light with wavelengths above 8μm and below 12μm.

6. The far-infrared transmission component as described in claim 1 or claim 2, wherein, The functional film further includes a high refractive index layer formed on the side of the low refractive index layer opposite to the substrate side, and the high refractive index layer has a higher refractive index for light with a wavelength of 10 μm than the low refractive index layer for light with a wavelength of 10 μm.

7. The far-infrared transmission component as described in claim 6, wherein, The high refractive index layer has a refractive index of 2 or higher for light with a wavelength of 10 μm.

8. The far-infrared transmission component as described in claim 6, wherein, The combined value of the optical film thickness n1d1 of the low refractive index layer and the optical film thickness n2d2 of the high refractive index layer, which is in contact with the low refractive index layer and located on the opposite side to the substrate, is 0.1 μm or more and 2.5 μm or less. The optical film thickness n1d1 is the product of the refractive index n1 of the low refractive index layer for light with a wavelength of 10 μm and the thickness d1 of the low refractive index layer. The optical film thickness n2d2 is the product of the refractive index n2 of the high refractive index layer for light with a wavelength of 10 μm and the thickness d2 of the high refractive index layer.

9. The far-infrared transmission component as described in claim 6, wherein, The high refractive index layer contains materials selected from Ge, Si, and NiO. x CuO x At least one material from the group consisting of Y2O3, ZnS, Bi2O3, ZrO2, ZnO and diamond-like carbon.

10. The far-infrared transmission component as described in claim 1 or claim 2, wherein, An adhesive film is formed between the substrate and the functional film, which causes the substrate and the functional film to adhere.

11. The far-infrared transmission component as claimed in claim 10, wherein, The adhesive film contains materials selected from Si, Ge, MgO, and NiO. x CuO x At least one material from the group consisting of ZnS, Al2O3, ZrO2, SiO2, TiO2, ZnO and Bi2O3.

12. The far-infrared transmission component as described in claim 1 or claim 2, wherein, The substrate comprises at least one material selected from the group consisting of Si, Ge, ZnS and chalcogenide glasses.

13. The far-infrared transmission component as described in claim 1 or claim 2, wherein, The far-infrared transmission component will be mounted on the vehicle.

14. A method for manufacturing a far-infrared transmission component, wherein, A far-infrared transmitting component is manufactured by forming a functional film on a far-infrared transmitting substrate. The functional film comprises a low-refractive-index layer with oxide as the main component and a refractive index of 1.5 or less for light with a wavelength of 10 μm. The low-refractive-index layer has MgO as the main component, and the content of MgO relative to the total low-refractive-index layer is 50% by mass or more and 100% by mass or less. The optical film thickness n1d1 of the low refractive index layer is greater than 0.1 μm and less than 2.5 μm. The optical film thickness n1d1 is the product of the refractive index n1 of the low refractive index layer for light with a wavelength of 10 μm and the thickness d1 of the low refractive index layer.

15. The method for manufacturing the far-infrared transmission component as described in claim 14, wherein, The low-refractive-index layer is formed by sputtering.

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