Window material for optical components, cover for optical component packaging, optical component packaging and optical device

Abstract

[Solution] A window material for optical elements has a rough surface on its main light-transmitting surface, with a total value of 1.7 × 10⁴ μm³ or more for the volume of the protruding valley space (Vvv) of the profile surface with a load area ratio of 10% and the volume of the protruding peak solidity (Vmp) of the profile surface with a load area ratio of 80% as specified in JIS B 0681-2:2018. [Effects] The window material for optical elements of the present invention is formed of a flat-shaped synthetic quartz glass that is easy to shape and can be manufactured at low cost. Even in a flat shape, for example, as a window material for UV-LEDs such as UVC-LEDs packaged in a surface mount device (SMD PKG), light emitted from the optical element, especially light with a beam distribution angle, can be efficiently concentrated when it passes through the window material. It can achieve the same light concentration as conventional convex-shaped lens-shaped windows, and can also provide light distribution without uneven illumination, such as with Lambertian reflection.

Description

[Technical Field]

[0001] This invention relates to an optical element package and an optical device suitable for controlling the light distribution properties of optical elements. Furthermore, this invention relates to an optical element package and an optical device for encapsulating optical elements such as ultraviolet light-emitting diodes. [Previous Technology]

[0002] In recent years, ultraviolet-emitting light elements, namely ultraviolet-light-emitting diodes (UV-LEDs), have been considered as alternatives to mercury lamps and other environmentally limited devices, such as those used for the inactivation of viruses like coronaviruses and for water sterilization. Among these, deep ultraviolet-light-emitting diodes (UVC-LEDs) that emit light in the deep ultraviolet (UV-C) region have attracted attention. For example, UV-LEDs are implemented using a flip-chip method because light cannot be extracted from the substrate such as a sapphire substrate used to form the layer of the device. Therefore, the device emits light with a beam angle and often cannot achieve the highly directional light like laser light. From the perspective of improving light extraction efficiency and eliminating uneven light intensity, methods that can control the beam distribution are needed.

[0003] Currently, UV-LEDs, which are made by molding and encapsulating the resin commonly used in white LEDs into a lens shape, often suffer from resin degradation due to the short wavelength light emitted by the element. Among these, surface-mount quartz (SMD PKG), which has excellent transmittance for short wavelength light, is most commonly chosen as the encapsulation material for UV-LEDs. Consideration is being given to using SMD PKG as a substrate to control light distribution.

[0004] For example, Japanese Patent Application Publication No. 2019-220507 (Patent Document 1) discloses a light-emitting device comprising a plurality of cylindrical lenses in order to obtain uniformity of the light intensity surface emitted from a light-emitting diode in the ultraviolet region. Also, Japanese Patent Application Publication No. 2020-025089 (Patent Document 2) discloses an LED device comprising a deep ultraviolet LED element, which uses a combination of crystalline fluororesin and silicone resin, wherein the crystalline fluororesin, which is resistant to short-wavelength light, is used to form an optical component (lens-shaped component) in the part mainly illuminated by light, thereby controlling light distribution and improving light extraction efficiency. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-220507 [Patent Document 2] Japanese Patent Application Publication No. 2020-025089 [Summary of the Invention]

[0006] [The problem the invention aims to solve]

[0007] However, using the cylindrical lens described in Japanese Patent Application Publication No. 2019-220507 (Patent Document 1) requires highly complex optical calculations. Furthermore, if a cylindrical lens is used, the SMD PKG will become larger in the Z direction (height direction). When considering using the optical element as an optical element package or using the optical element package as an optical device (optical element module), the optical element package and the optical device (optical element module) will become larger, which is disadvantageous in such designs. Moreover, although synthetic quartz glass is used as a window material for the long-term stable extraction of light in the ultraviolet region, processing synthetic quartz glass into a lens shape will increase the cost.

[0008] Furthermore, the method of using crystalline fluororesin in a lens-shaped component as described in Japanese Patent Application Publication No. 2020-025089 (Patent Document 2) is not considered to have high durability from the perspective of light transmittance in the ultraviolet region, resin degradation caused by ultraviolet light, and ensuring airtightness, for long-term use such as LEDs.

[0009] In view of the above, the present invention aims to provide a flat-shaped optical element window material and an optical element package cover having the optical element window material, which are easy to shape and can be manufactured at low cost by using a material with high light durability in the ultraviolet region, namely synthetic quartz glass. In particular, it provides a flat-shaped optical element window material and an optical element package cover having the optical element window material that can efficiently collect light emitted from a light source with a light distribution angle, even if it is not a convex lens shape. Furthermore, the present invention aims to provide an optical element package body that encapsulates an optical element using the optical element package cover, and an optical device having an optical element window material. [Means for Solving the Problem]

[0010] As a result of the inventors’ keen investigation in order to solve the above-mentioned problems, they discovered that in window materials made of synthetic quartz glass, the micro-shape of the main surface through which light passes is set as a rough surface with a predetermined surface property based on geometric property specifications (GPS). By using window materials made of synthetic quartz glass with a flat shape that is easy to shape and can be manufactured at low cost, light with a light distribution angle can be efficiently collected, thereby completing the present invention.

[0011] Therefore, the present invention provides the following: a window material for optical elements, a cover for an optical element package, an optical element package, and an optical device. 1. A window material for optical elements, which is a window material for an optical element package that houses an optical element that emits or receives light, or for an optical device having an optical element package that houses an optical element that emits or receives light, wherein it is formed of synthetic quartz glass; has a flat plate shape; one or both sides of the aforementioned light-transmitting main surface are rough; on the aforementioned rough surface, i.e., the main surface, the total value of the volume of the protruding valley space (Vvv) of the profile surface with a load area ratio of 10% as specified in JIS B 0681-2:2018, and the volume of the protruding peak solid part (Vmp) of the profile surface with a load area ratio of 80% is 1.7 × 10 4 μm 3 or more. 2. The window material for optical elements as described in 1, wherein the thickness is 0.1 to 3 mm. 3. The window material for an optical element as described in 1 or 2, wherein the surface roughness (Ra) of the aforementioned rough surface, i.e., the main surface, is 0.1 to 0.5 μm. 4. A cover for an optical element package, comprising: the window material for an optical element as described in any one of 1 to 3, and an adhesive layer laminated on a portion of one side of the aforementioned main surface of the optical element window material. 5. The cover for an optical element package as described in 4, wherein the adhesive constituting the aforementioned adhesive layer is at least one selected from resin-based adhesives and metal-based adhesives. 6. The cover for an optical element package as described in 4 or 5, wherein the aforementioned adhesive layer is in a semi-cured state (B-Stage). 7. An optical element package comprising: an optical element, a housing member in which the optical element is disposed, a window material for the optical element as described in any one of claims 1 to 3, and an adhesive layer; wherein the window material for the optical element is disposed at a position through which light passes, the optical element is housed in the housing member, and the housing member and the window material for the optical element are bonded and packaged via the adhesive layer. 8. The optical element package as described in 7, wherein the optical element is a light-emitting element emitting light with a wavelength of 220 to 600 nm or a light-receiving element receiving light. 9. The optical element package as described in 7 or 8, wherein the optical element is a light-emitting element emitting light with a beam angle of 150 degrees or less. 10. The optical element package as described in any one of claims 7 to 9, wherein the optical element is a light-emitting element, and the shortest distance between the light-emitting element and the window material for the optical element is 0.5 to 10 mm. 11. An optical device comprising: an optical element package housing in which a light-emitting element is disposed internally, and a window material for the optical element as described in any one of claims 1 to 3; the window material for the optical element is disposed at a position where the light passes. 12. The optical device as described in 11, wherein the optical element is an optical element emitting light with a wavelength of 220 to 600 nm or a light-receiving element receiving light. 13. The optical device as described in 11 or 12, wherein the optical element is a light-emitting element emitting light having a beam angle of 150 degrees or less.14. The optical device described in any one of 11 to 13, wherein the aforementioned optical element is a light-emitting element, and the shortest distance between the aforementioned optical element package and the aforementioned optical element window material is 0.5 to 10 mm. [Effects of the invention].

[0012] The optical element window material of the present invention is formed of a flat-shaped synthetic quartz glass that is easy to shape and can be manufactured at low cost. Even if it is a flat-shaped window material, for example, as a window material for UV-LEDs such as UVC-LEDs packaged in a surface mount type package (SMD PKG), light emitted from the optical element, especially light with a light distribution angle, can be efficiently concentrated when it passes through the window material. It can achieve the same light concentration as the lens-shaped window material of the past, such as the convex shape, and can also be used as a light distribution without uneven illumination, such as a Lambertian reflection.

[0013] Furthermore, if the optical element package and optical device of the optical element window material of the present invention are used, compared with the optical element package and optical device of the conventional convex-shaped or lens-shaped window material, the volume can be reduced, and it is expected that the optical element package and optical device (optical element module) using UV-LED and the like will be more compact, the cost will be reduced, and the design freedom of the optical device (optical element module) will be higher.

Implementation Method

[0015] Hereinafter, the present invention will be described in detail. The optical element window material of the present invention is suitable for an optical element package housing a light-emitting or light-receiving optical element, and is provided in the portion where light enters and exits between the interior and exterior of the optical element package housing. In the optical element package housing, the optical element is housed in a housing member and encapsulated by the optical element window material. Furthermore, the optical element window material of the present invention is suitable for an optical device having an optical element package housing a light-emitting or light-receiving optical element, and is provided in the portion where light enters and exits between the interior and exterior of the optical device.

[0016] The optical element window material of the present invention is formed of synthetic quartz glass. Furthermore, the optical element window material of the present invention has a flat plate shape. In the present invention, the flat plate shape is not like the shape of a convex lens that collects light with a convex surface; rather, it is preferable that both sides of the main surface through which light passes through the optical element window material are slightly flat, and particularly preferably that both sides of the main surface through which light passes through the optical element window material are slightly parallel. If the optical element window material of the present invention is flat plate, its size and thickness can be appropriately selected considering the size of the housing member, the mechanical strength of the optical element window material, and the mechanical strength when used as an optical element package and optical device. Furthermore, the thickness of the optical element window material of the present invention can be appropriately selected considering the attenuation of the wavelength of light relative to the optical element, and the pressure difference between the inner and outer sides of the window material, i.e., the inside and outside of the optical element package (e.g., the air pressure difference between the inside and outside of the optical element package). Specifically, the thickness of the window material is preferably 0.1 mm or more, more preferably 0.2 mm or more, more preferably 3 mm or less, and more preferably 2 mm or less.

[0017] In this invention, the main surface through which light passes through the window material for optical elements is roughened on one or both sides in order to scatter light on the main surface. This roughened surface has a predetermined surface characteristic based on geometric property specifications (GPS). Furthermore, the predetermined surface characteristic of this invention is characterized by a total value of 1.7 × 10⁴ μm³ or more for the volume of the protruding valley space (Vvv) of a profile surface with a load area ratio of 10% as specified in JIS B 0681-2:2018 and the volume of the protruding peak solidity (Vmp) of a profile surface with a load area ratio of 80%. Because the window material for optical elements has this surface characteristic, even a flat surface can obtain light distribution characteristics with high light-gathering properties. The combined value of Vvv and Vmp is smaller than 1.7 × 10⁴ μm³ because the surface of the window material used for optical components has a large unevenness, resulting in less light being scattered on the surface. This leads to more light passing through the window material as straight rays, making it difficult to fully concentrate light with a beam distribution angle, thus hindering the production of a concentrated radial beam, similar to that obtained by Lambertian reflection. The surface properties of the window material used for optical components can be measured using a 3D surface shape measuring machine, etc.

[0018] In this invention, the surface roughness (Ra) of the main surface of the window material for optical elements is preferably 0.1 μm or more, preferably 0.5 μm or less, and even more preferably 0.4 μm or less. If the surface roughness (Ra) of the main surface is within this range, it can reduce the possibility that the light becomes diffused due to increased reflection loss of the main surface of the window material for optical elements, or that the proportion of parallel light transmitted through the window material remains unchanged is increased due to less light reflected from the main surface, thus failing to adequately collect light.

[0019] The optical element window material of the present invention is made of synthetic quartz glass, but the optical element window material made of synthetic quartz glass can be manufactured, for example, by the following method. First, a synthetic quartz glass ingot is subjected to machining processes such as molding, annealing, slicing, cornering, and encapsulation to obtain a substrate with a rough surface on the machined surface. In the case of manufacturing an optical element window material with rough surfaces on both sides, a cleaning process can be performed before proceeding to the chemical etching (surface treatment) process described later. On the other hand, in the case of manufacturing a window material with a rough surface on only one side, the single side is ground and mirror-finished, and then a cleaning process is performed before proceeding to the chemical etching (surface treatment) process described later. Furthermore, the rough surface can also be achieved by re-roughening the single or two sides after mirror polishing, such as by sandblasting.

[0020] Next, chemical etching (surface treatment) is applied to the substrate obtained by machining. Specifically, the rough surface texture of the main surface of the roughened substrate obtained by machining is adjusted by chemical etching. The surface texture can be adjusted by appropriately selecting the type of etching solution and the immersion time in the etching solution. Hydrofluoric acid or buffered hydrofluoric acid is suitable as the etching solution. The concentration of the etching solution is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, preferably 20% by mass or less, and more preferably 15% by mass or less. If the concentration is lower than the above range, the etching speed is slow, and it takes a long time to obtain the desired surface texture, which may reduce productivity. On the other hand, if the concentration is higher than the above range, the etching speed is fast, and it may be impossible to perform precise control to obtain the desired surface texture.

[0021] Chemical etching can be a method of immersing the substrate to be processed in an etching solution or a method of pouring an etching solution onto the substrate to be processed. The processing can be batch processing of multiple sheets at once or leaf processing of individual sheets. The processing time due to the etching solution is preferably set to a range of 15 minutes or more, preferably 100 minutes or less, and more preferably 80 minutes or less. If the processing time is shorter than the above range, a high concentration of etching solution may be used to obtain the desired surface properties, making it difficult to achieve precise control over obtaining the desired surface properties. On the other hand, if the processing time is longer than the above range, there is a possibility that dissolved glass components may re-adhere, causing defects. These defects are particularly likely to become significant in methods where the substrate to be processed is immersed in the etching solution. Furthermore, productivity may also decrease. After chemical etching, rinsing (water washing) and drying the substrate yields a window material for optical components. The light distribution characteristics of the obtained optical element window material can be evaluated, for example, using an LED module spectral meter (LEDGON manufactured by Instrument Systems).

[0022] The optical element package cover of the present invention includes an optical element window material and an adhesive layer deposited on a portion of one side of the main surface of the optical element window material (e.g., the outer periphery of the main surface of the window material where the window material contacts the housing member). The optical element package cover is suitable for packaging optical element packages that house optical elements requiring hermeticity, such as UV-LEDs. By using the optical element package cover, which includes an optical element and a housing member that houses the optical element, the window material and the housing member are bonded together by the adhesive of the optical element package cover, an optical element package in which the optical element is hermetically packaged inside the housing member can be formed.

[0023] While there are no particular limitations on the adhesive layer, it is preferable to form it from at least one adhesive selected from resin-based adhesives and metal-based adhesives. Resin-based adhesives consist of a paste containing resin, particularly adhesives containing epoxy resin, silicone resin, etc., because the adhesive layer formed after bonding (after curing) creates a three-dimensional network structure, enabling bonding of synthetic quartz glass, as well as many materials such as ceramics and metal plates. Examples of resin-based adhesives include UV-curable and silicone-based adhesives, such as TB3114 (manufactured by ThreeBond) and KER-3000-M2 (manufactured by Shin-Etsu Chemical Co., Ltd.). The resin-based adhesive is applied to the window material for optical components using a known method to form an adhesive layer.

[0024] On the other hand, examples of metal-based adhesives include low-temperature soldering materials using Au-Sn, Zn-Sn, etc., sintered materials of metal nanoparticles such as nano silver particles, and fusions thereof. Adhesives using low-temperature soldering materials and sintered materials of metal nanoparticles can be commercially available. In the case of fusions of low-temperature soldering materials and metal nanoparticles, for example, an adhesive is prepared by mixing at least one known low-temperature solder (selected from the group consisting of Sn-Bi solder, Sn-Zn-Bi solder, and Sn-Zn solder) with nano silver particles (with an average primary particle size of 100 nm or less) as the main component, and then adding at least one metal element selected from the group consisting of zinc, zirconium, tellurium, antimony, and indium. The metal-based adhesive, before bonding (before hardening), can be in a paste state and applied to the window material of optical components using known coating methods such as dispensing machines, screen printing, and inkjet printing to form an adhesive layer. The adhesive layer can be preheated as needed to achieve a semi-cured state (B-Stage).

[0025] The optical element package of the present invention includes a light-emitting element or a light-receiving element, i.e., an optical element, a housing member in which the optical element is disposed, a window material for the optical element, and an adhesive layer. In the optical element package of the present invention, the window material for the optical element is provided at a position through which light passes. Furthermore, in the optical element package, the optical element is housed in the housing member, and the housing member and the window material for the optical element are bonded and packaged via the adhesive layer. In the optical element package, the window material for the optical element and the adhesive layer can be formed by hardening the window material for the optical element as a cover for the optical element package and the adhesive layer of the cover for the optical element package.

[0026] In the optical element package of the present invention, a housing member has a partial opening. After housing the optical element, the housing member is joined to the optical element window material. The opening of the housing member is sealed with the optical element window material via an adhesive layer. Specifically, an example of the optical element package of the present invention is the optical element package 10 shown in FIG. 1, which is hermetically sealed between the optical element window material 1 and the housing member 3 housing the optical element 4 via an adhesive layer 2. Furthermore, in FIG. 1, 5 is a reflector.

[0027] The optical element disposed inside the housing member can be a light-emitting element or a light-receiving element. Preferably, the wavelength of the light emitted by the light-emitting element and the wavelength of the light received by the light-receiving element are both above 220 nm and below 600 nm. Examples of light-emitting elements include UV-LEDs (center wavelength 260–300 nm), blue light-emitting elements (wavelength 440–490 nm), green light-emitting elements (wavelength 490–580 nm), and yellow light-emitting elements (wavelength 550–600 nm) using aluminum gallium nitride (AlGaN), and elements particularly suitable for surface-emitting light.

[0028] The housing member, in the package for optical elements, can be a known type of member for housing optical elements. It is suitable to use a recessed portion formed of inorganic materials such as metals and ceramics, or organic materials such as rubber, elastomers, and resins, which has a housing portion for the optical element. The size of the housing member is appropriately set according to the application of the optical element, the size of the optical element being housed, and the size of the window material. Furthermore, particularly in LEDs, when the optical element reaches a high temperature due to heat generation, the luminous efficiency of the optical element decreases. Therefore, the housing member is suitable to be formed of materials with good heat dissipation properties, such as alumina-based ceramics or aluminum nitride-based ceramics, or to incorporate metals such as gold and copper as heat dissipation components.

[0029] The farther the light emitted from the light-emitting element is, the lower the illuminance. Furthermore, due to the requirement for compactness in the design of optical devices (optical element modules), the shortest distance between the optical element, especially the light-emitting element, and the window material used for the optical element is preferably 0.5 mm or more, more preferably 1 mm or more, more preferably 10 mm or less, and more preferably 8 mm or less.

[0030] Inside the optical element package (the part surrounded by the housing member and the window material), in addition to the optical element, other components such as pins for external electrical conduction between the optical element and the optical element package and reflectors (reflector plates) for improving light extraction efficiency can be provided. Inside the optical element package, the part other than the optical element and other components can be in a vacuum state, air, or a state filled with an inert gas (such as nitrogen), or a state filled with a solid such as transparent rubber, elastomer, or resin. However, from the viewpoint of the exothermic nature of the heat emitted by the optical element, a vacuum state or a state filled with a gas is preferred.

[0031] The optical device of the present invention includes an optical element package in which an optical element, i.e., an optical element, is disposed internally, and an optical element window. In the optical device of the present invention, the optical element window is disposed at a position through which light passes. This allows control over the light distribution properties of the optical device. As an optical device, there are optical element packages having one or more surface mount packages, and those having two or more optical element packages arranged in an array (generally referred to as an optical element module). As an optical device, it can be either a light-emitting device or a light-receiving device, but it is particularly suitable for light-emitting devices such as light irradiation devices. As a light-emitting device, a surface mount package (SMD PKG) for ultraviolet LEDs (UV-LEDs) such as deep ultraviolet LEDs is suitable.

[0032] When using an SMD PKG with reflectors, etc., even if there is only one light source within the SMD PKG, the emitted light is not point-emitting but rather becomes quasi-surface-emitting light with a beam distribution angle. Furthermore, for example, when the light-emitting elements commonly used in UV-LEDs are bonded using a reverse-chip method, in addition to becoming a point of light with a beam distribution angle, uneven illuminance often occurs. In cases requiring uniform illumination, such as photoresist curing, it is difficult to design an optical device that arranges optical element packages with such light distribution characteristics to uniformly illuminate a large area. Furthermore, in cases where the output of the optical element package is weak, the distance to the irradiated object must be shortened.

[0033] As with the optical device of the present invention, the optical element window material of the present invention, with its main surface having a rough surface having a predetermined surface texture, is provided at the position where light passes, relative to the optical element package. This allows for efficient illumination by eliminating illuminance unevenness, even with small output. In the optical device of the present invention, the optical element window material can be bonded, but it can also be unbonded. When fixing the optical element window material, it can be fixed in a detachable manner using flanges or the like. Furthermore, the optical element window material used in the optical element package of the optical device of the present invention can be the optical element window material of the present invention with a main surface having a rough surface texture, or other window materials.

[0034] Because of the requirement for compactness in the design of optical devices (optical element modules), the shortest distance between the optical element package, especially the optical element package in which the optical element is a light-emitting element, and the window material for the optical element is preferably 0.5 mm or more, more preferably 1 mm or more, more preferably 10 mm or less, and more preferably 8 mm or less.

[0035] The optical element window material, optical element package cover, optical element package, and optical device of the present invention are particularly effective for optical elements such as light-emitting elements that emit ultraviolet light (especially deep ultraviolet light below 280 nm) with wavelengths below 400 nm or light-receiving elements. Furthermore, the optical element window material, optical element package cover, optical element package, and optical device of the present invention are particularly effective for light-emitting elements that emit light with a beam distribution angle of 150 degrees or less. [Example]

[0036] Hereinafter, although embodiments and comparative examples are presented to specifically describe the present invention, the present invention is not limited to the embodiments described below.

[0037] [Example 1] The sliced ​​synthetic quartz glass substrate was polished using a planetary double-sided polishing machine to obtain a synthetic quartz glass wafer substrate with a thickness of 0.5 mm and rough surfaces on both sides of the main surface. Next, the obtained synthetic quartz glass substrate was immersed in 8% by mass buffered hydrofluoric acid for 60 minutes, washed with water, and dried to obtain a window material for optical components in the shape of a flat plate.

[0038] The surface properties of the rough surface, i.e., the main surface, of the obtained optical element window material were evaluated. The volume of the protruding valley (Vvv) of the profile surface with a load area ratio of 10% as specified in JIS B 0681-2:2018, and the volume of the protruding peak (Vmp) of the profile surface with a load area ratio of 80% were measured using a white interferometer (Nexview manufactured by Zygo Corporation). The combined value (Vvv+Vmp) of these values ​​was 1.91 × 10⁴ μm³ on both main surfaces. Furthermore, the surface roughness (Ra) of the obtained optical element window material, i.e., the main surface, was measured to be 0.41 μm on both main surfaces.

[0039] Next, at the outer periphery of the main surface where it joins with the receiving member of the obtained optical element window material, a metal-based adhesive is applied by screen printing to form an adhesive layer with a line width of 0.25 mm, thus obtaining a cover for the optical element package. In the metal-based adhesive, nano-silver particles with an average primary particle size of 50 nm are used as the main component, and a metal-based adhesive containing bismuth, tin, and indium is used.

[0040] Next, a surface mount type package (SMD PKG) carrier (receiving member) with an aluminum nitride substrate and a 3.5mm angle is used to encapsulate the top of a 50mW UVC-LED element (optical element) with an initial light distribution angle of 120 degrees and a wavelength of 265nm, obtained above, to obtain a surface mount type package (SMD PKG). The SMD PKG carrier has gold plating applied to the portion that joins with the synthetic quartz glass cover (the surface in contact with the adhesive layer). The LED inside the obtained SMD PKG (optical element package) is lit, and the light distribution angle is measured using an LED module spectral meter (LEDGON manufactured by Instrument Systems), finding it to be 70 degrees. The light distribution characteristics (3D diagram of the light distribution) are shown in Figure 1. At this time, the light distribution changes from the original batwing-like light distribution of the LED to near-uniform Lambertian reflection, and the light distribution characteristics change.

[0041] [Example 2] A synthetic quartz glass wafer substrate was obtained using the same method as in Example 1. The obtained synthetic quartz glass substrate was then immersed in 10% by mass buffered hydrofluoric acid for 15 minutes, washed with water, and dried to obtain a flat-shaped window material for optical components.

[0042] The surface properties of the rough surface, i.e., the main surface, of the obtained optical element window material were evaluated in the same manner as in Example 1. As a result, the total value (Vvv+Vmp) was 7.02 × 10⁴ μm³ on both main surfaces. Furthermore, the surface roughness (Ra) of the rough surface, i.e., the main surface, of the obtained optical element window material was measured to be 1.02 μm on both main surfaces.

[0043] Next, a surface-mount package (SMD PKG) carrier (receiving member) containing a 50mW UVC-LED element (optical element) with an initial light distribution angle of 130 degrees and a wavelength of 280nm, identical to that in Example 1, was encapsulated with a cover using the same method as in Example 1, thus obtaining a surface-mount package (SMD PKG). The LED inside the obtained SMD PKG (optical element package) was lit, and the light distribution angle was measured using the same method as in Example 1; the light distribution angle was 48 degrees. The light distribution characteristics (3D diagram of the light distribution) are shown in Figure 2. At this time, the light distribution changes from the original batwing light distribution of the LED to a Lambertian reflection without uneven illumination, which is closer to the case in Example 1.

[0044] [Example 3] The sliced ​​synthetic quartz glass substrate was polished using a planetary double-sided polishing machine, and then mirror-finished using a planetary single-sided polishing machine to obtain a synthetic quartz glass wafer substrate with one rough surface and the other mirror surface, with a thickness of 0.8 mm. Next, the obtained synthetic quartz glass substrate was immersed in 5% by mass buffered hydrofluoric acid for 30 minutes, washed with water, and dried to obtain a flat-shaped window material for optical components.

[0045] The surface properties of the rough surface, i.e., the main surface, of the obtained optical element window material were evaluated in the same manner as in Example 1. As a result, the total value (Vvv + Vmp) of these components on the main surface (rough surface) was 2.05 × 10⁴ μm³. Furthermore, the surface roughness (Ra) of the obtained optical element window material, i.e., the main surface, was measured to be 0.39 μm on the main surface (rough surface).

[0046] Next, the same surface-mount package (SMD PKG) carrier (receiving member) as in Example 1, containing a UVC-LED element (optical element) inside, is encapsulated with a cover using the same method as in Example 1 to obtain a surface-mount package (SMD PKG). The LED inside the obtained SMD PKG (optical element package) is lit, and the light distribution angle is measured using the same method as in Example 1; the light distribution angle is 60 degrees. The light distribution characteristics (3D diagram of light distribution) are shown in Figure 3. At this time, the light distribution changes from the original batwing light distribution of the LED to near-uniform Lambertian reflection, and the light distribution characteristics change.

[0047] [Comparative Example 1] A synthetic quartz glass wafer substrate was obtained using the same method as in Example 1. The obtained synthetic quartz glass substrate was then immersed in 10% by mass buffered hydrofluoric acid for 180 minutes, washed with water, and dried to obtain a flat-shaped window material for optical components.

[0048] The surface properties of the rough surface, i.e., the main surface, of the obtained optical element window material were evaluated in the same manner as in Example 1. As a result, the total value (Vvv+Vmp) was 1.38 × 10⁴ μm³ on both main surfaces. Furthermore, the surface roughness (Ra) of the rough surface, i.e., the main surface, of the obtained optical element window material was measured to be 0.36 μm on both main surfaces.

[0049] Next, the same surface-mount package (SMD PKG) carrier (receiving member) as in Example 1, containing a UVC-LED element (optical element) internally identical to that in Example 1, is encapsulated with a cover using the same method as in Example 1 to obtain a surface-mount package (SMD PKG). The LED inside the obtained SMD PKG (optical element package) is lit, and the light distribution angle is measured using the same method as in Example 1, maintaining a light distribution angle of 120 degrees. The light distribution characteristics (3D diagram of light distribution) are shown in Figure 4. At this time, the light distribution maintains the batwing-wing light distribution characteristic of UVC-LED SMD PKGs with a near-inverted wafer configuration, and no change in light distribution characteristics is observed.

[0050] [Example 4] A surface mount device (SMD PKG) (Nikkiso VPS-171) with a 3.5mm angle housing a 30mW UVC-LED element with an initial light distribution angle of 130 degrees and a wavelength of 285nm is arranged in a 3×3 column relative to a deep ultraviolet LED module. At a distance of 4mm from the window of the SMD PKG, an optical element window is set in the same manner as in Example 2 to form an optical device (light-emitting device).

[0051] The LED in the obtained optical device is lit up, and the light distribution angle is measured in the same way as in Example 1. The light distribution angle is 48 degrees. [Simplified Explanation of the Diagram]

[0014] [Fig. 1] A cross-sectional view showing an example of the optical element package of the present invention. [Fig. 2] A 3D diagram of the light distribution of the optical element package of Embodiment 1. [Fig. 3] A 3D diagram of the light distribution of the optical element package of Embodiment 2. [Fig. 4] A 3D diagram of the light distribution of the optical element package of Embodiment 3. [Fig. 5] A 3D diagram of the light distribution of the optical element package of Comparative Example 1.

Claims

1. A window material for optical elements, which is a window material for an optical element package housing an optical element that emits light or receives light, or for an optical device having an optical element package housing an optical element that emits light or receives light, wherein, It is formed of synthetic quartz glass; it has a flat plate shape; one or both sides of the aforementioned light-transmitting main surface are rough; on the aforementioned rough surface, i.e. the main surface, the total value of the volume of the protruding valley space (Vvv) of the profile surface with a load area ratio of 10% as specified in JIS B 0681-2:2018 and the volume of the protruding peak solid (Vmp) of the profile surface with a load area ratio of 80% is 1.7×104μm3 or more.

2. The window material for optical elements as described in claim 1, wherein, The thickness is 0.1 to 3 mm.

3. Window material for optical elements as described in claim 1 or 2, wherein, The surface roughness (Ra) of the aforementioned rough surface, i.e. the main surface, is 0.1 to 0.5 μm.

4. A cover for an optical element package, comprising: an optical element window material as described in any one of claims 1 to 3, and an adhesive layer laminated on a portion of one side of the aforementioned main surface of the optical element window material.

5. A cover for an optical element package as described in claim 4, wherein, The adhesive constituting the aforementioned adhesive layer is at least one selected from resin-based adhesives and metal-based adhesives.

6. A cover for an optical element package as described in claim 4 or 5, wherein, The aforementioned adhesive layer is in a semi-cured state (B-Stage).

7. An optical element package comprising: an optical element, a housing member in which the optical element is disposed, a window material for the optical element as described in any one of claims 1 to 3, and an adhesive layer; wherein the window material for the optical element is disposed at a position through which light passes, the optical element is housed in the housing member, and the housing member and the window material for the optical element are joined and packaged via the adhesive layer.

8. The optical element package as described in claim 7, wherein, The aforementioned optical element is a light-emitting element that emits light with a wavelength of 220–600 nm or a light-receiving element that receives light.

9. The optical element package as described in claim 7 or 8, wherein, The aforementioned optical element is a light-emitting element that emits light with a light distribution angle of less than 150 degrees.

10. The optical element package as described in claim 7 or 8, wherein, The aforementioned optical element is a light-emitting element, and the shortest distance between the light-emitting element and the window material used for the aforementioned optical element is 0.5 to 10 mm.

11. An optical device comprising: an optical element package having a light-emitting element disposed therein, and an optical element window as described in any one of claims 1 to 3; wherein the optical element window is disposed at a position through which the light passes.

12. The optical apparatus as described in claim 11, wherein, The aforementioned optical element is a light-emitting element that emits light with a light distribution angle of less than 150 degrees.

13. The optical apparatus as described in claim 11 or 12, wherein, The aforementioned optical element is a light-emitting element that emits light with a wavelength of 220–600 nm or a light-receiving element that receives light.

14. The optical apparatus as described in claim 11 or 12, wherein, The aforementioned optical element is a light-emitting element, and the shortest distance between the aforementioned optical element package and the aforementioned optical element window material is 0.5 to 10 mm.

Images