Optical glass for near-infrared optical systems, method for producing the same, and use thereof

Abstract

The present application provides an optical glass for near-infrared optical system, a preparation method and application thereof. The optical glass comprises a glass matrix, which comprises the following elements in mass percentage: B: 5.0-10.0%; Si: 0-3.0%; La: 25.0-35.0%; Nb: 1.0-10.0%; Zn: 15.0-25.0%; Zr: 1.0-8.0%; Li: 0.01-1.0%; O: 25.0-38.0%; the near-infrared waveband refractive index n s of the optical glass is 1.75-1.82, and the relative partial dispersion PC,s is 0.45-0.55. The optical glass has low glass transition temperature and crystallization temperature, low density and relative grinding hardness, high Knoop hardness and excellent transmittance. Furthermore, the optical glass can be used as a precision molding aspherical optical component.

Description

Technical Field

[0001] This invention relates to an optical glass that can be used in near-infrared optical systems, its preparation method and application, and belongs to the field of optical glass. Background Technology

[0002] Systems such as day / night dual-use security lenses, drone payloads, laser focusing and collimation systems, and near-infrared lidar optical systems for autonomous driving require clear imaging of visible light and near-infrared (typically 850-950nm) on the same image plane. Astronomical star-guided telescopes and high-end machine vision lenses require correction of the secondary spectrum in wide-band systems. Coupling lenses and beam splitters in pulse oximeters and near-infrared brain imaging equipment (760nm, 850nm) need precise matching to the near-infrared refractive index to detect blood oxygen concentration in human tissues. Fundus imaging objectives in near-infrared fundus examination instruments require no strong light stimulation in the near-infrared band. Therefore, optical glass places requirements on the refractive index in the near-infrared band.

[0003] However, without an accurate near-infrared refractive index, any optical system involving the near-infrared band cannot be implemented. The near-infrared refractive index not only defines the system's focal length and image plane but also permeates every stage of chromatic aberration correction, material selection, anechoic treatment, and final performance evaluation. In particular, a suitable near-infrared refractive index n is needed. s Optical glass with a relative partial dispersion (PC,s) of 1.75 to 1.82 and a relative partial dispersion (PC,s) of 0.45 to 0.55.

[0004] Patent application CN111039563A discloses a refractive index n d Optical glass with a glass transition temperature (Tg) in the range of 1.8000 to 2.0000 and an Abbe number (υd) in the range of 25.0 to 45.0. The glass transition temperature (Tg) of this glass is preferably above 630°C, which is not conducive to the precision molding of aspherical optical components, and the refractive index in the near-infrared band is not mentioned.

[0005] Therefore, a near-infrared refractive index n is studied. s Optical glass with a chromaticity of 1.75~1.82 and a relative partial dispersion PC,s of 0.45~0.55 has become an urgent technical problem to be solved. Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In view of the technical problems existing in the prior art, the present invention first provides a near-infrared band refractive index n sThe optical glass of the present invention has a glass transition temperature of 1.75 to 1.82 and a relative partial dispersion (PC,s) of 0.45 to 0.55. The optical glass of the present invention has a low glass transition temperature and crystallization temperature, as well as low density and relative grinding hardness, but high Knoop hardness and excellent transmittance. Furthermore, the optical glass of the present invention can be used for precision molding of aspherical optical components.

[0008] The present invention also provides a method for preparing optical glass, which is simple and easy to implement, uses readily available raw materials, and is inexpensive, thereby further reducing the cost of optical systems.

[0009] Solution for solving the problem

[0010] This invention provides an optical glass, wherein the optical glass comprises a glass matrix, and the glass matrix contains the following elements by weight percentage:

[0011] B: 5.0~10.0%, preferably 6.0~9.0%;

[0012] Si: 0~3.0%, preferably 0.1~2.0%;

[0013] La: 25.0%~35.0%, preferably 27.0%~34.0%;

[0014] Nb: 1.0%~10.0%, preferably 3.0%~9.0%;

[0015] Zn: 15.0~25.0%, preferably 16.0~24.0%;

[0016] Zr: 1.0~8.0%, preferably 2.0~6.0%;

[0017] Li: 0.01~1.0%, preferably 0.1~0.9%;

[0018] O: 25.0~38.0%, preferably 27.0~37.0%;

[0019] The near-infrared refractive index n of the optical glass s The relative partial dispersion PC,s is 1.75~1.82, and the relative partial dispersion is 0.45~0.55.

[0020] According to the optical glass of the present invention, the sum of the contents of Si and B elements, ∑(Si+B), is 5.0% to 11.0% by mass percentage; preferably 6.0% to 10.0%.

[0021] The ratio of the sum of La and Nb content to the sum of Si and B content, ∑(La+Nb) / ∑(Si+B), is 2.0~8.0, preferably 3.0~7.0.

[0022] According to the optical glass of the present invention, the content ratio of La to Zn, by mass percentage, is 1.0 to 2.0, preferably 1.4 to 1.8;

[0023] The ratio of Zn to Zr is 2.5 to 9.0, preferably 3.0 to 8.5.

[0024] According to the optical glass of the present invention, the ratio of O to Nb content, by mass percentage, is 2.5 to 7.5, preferably 3.0 to 7.0.

[0025] According to the optical glass of the present invention, the optical glass further comprises Sb element; preferably, the content of Sb element is not more than 500 ppm by mass percentage of the glass matrix, and more preferably not more than 300 ppm.

[0026] According to the optical glass of the present invention, the optical glass does not contain one or more of the elements Ti, Ta, Gd, W, Y, Yb, Ba, Bi, Ge and Te.

[0027] According to the optical glass of the present invention, the glass transition temperature of the optical glass is lower than 560°C; the crystallization temperature of the optical glass is lower than 1020°C.

[0028] The density of the optical glass is 4.50 g / cm³. 3 The optical glass has the following characteristics: a relative abrasive hardness (FA) of less than 150; and a Knoop hardness (HK) of greater than 600 GPa.

[0029] According to the optical glass of the present invention, the wavelength λ at which the external transmittance of the optical glass is 80% is... 80 The wavelength is below 330nm when the external transmittance is 5% and below 400nm.

[0030] The present invention also provides a method for preparing optical glass according to the present invention, which includes weighing and mixing the raw materials of each element of the optical glass in proportion, melting them, and then pouring or casting them into a molding die, or directly pressing them into shape.

[0031] The present invention also provides an aspherical optical component comprising the aforementioned optical glass.

[0032] The effects of the invention

[0033] The optical glass of this invention has a low glass transition temperature and crystallization temperature, as well as low density and relative grinding hardness, but high Knoop hardness and excellent transmittance. Furthermore, the optical glass of this invention can be used for precision molding of aspherical optical components.

[0034] The present invention also provides a simple and easy method for preparing optical glass, with readily available raw materials and low cost, which further helps to reduce the cost of optical systems. Detailed Implementation

[0035] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0036] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0037] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0038] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0039] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0040] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0041] In this invention, the optical glass comprises a glass matrix, which contains the following elements by weight percentage:

[0042] B: 5.0~10.0%, preferably 6.0~9.0%;

[0043] Si: 0~3.0%, preferably 0.1~2.0%;

[0044] La: 25.0%~35.0%, preferably 27.0%~34.0%;

[0045] Nb: 1.0%~10.0%, preferably 3.0%~9.0%;

[0046] Zn: 15.0~25.0%, preferably 16.0~24.0%;

[0047] Zr: 1.0~8.0%, preferably 2.0~6.0%;

[0048] Li: 0.01~1.0%, preferably 0.1~0.9%;

[0049] O: 25.0~38.0%, preferably 27.0~37.0%;

[0050] The near-infrared refractive index n of the optical glass s The relative partial dispersion PC,s is 1.75~1.82, and the relative partial dispersion is 0.45~0.55.

[0051] Elements are introduced in various forms using compounds that allow them to be introduced in appropriate amounts. As described below, the content of each element is expressed as a percentage of the glass matrix by mass.

[0052] Boron (B) is the main structural component in the glass network framework and also acts as a flux to lower the glass melting temperature. Boron is structurally composed of boron-oxygen trigonal [BO3] and boron-oxygen tetrahedron [BO4]. Under different conditions, boron can exist as trigonal [BO3] or boron-oxygen tetrahedron [BO4]. At high temperatures, it is generally difficult to form boron-oxygen tetrahedra, and it can only exist as trigonal structures. However, at low temperatures, under certain conditions, boron tends to capture free oxygen to form tetrahedra, resulting in a denser structure and increased low-temperature viscosity of the glass. The inventors of this invention have discovered that boron not only has the properties of lowering glass viscosity at high temperatures and increasing it at low temperatures, but it is also a major component in reducing the near-infrared refractive index of glass. When the content of boron is too low, it cannot act as a flux, reduces the amount of laium (La) melted into the glass, and decreases the chemical stability of the glass; while when the content of boron is too high, it reduces the near-infrared refractive index of the glass and increases the tendency for crystallization. Therefore, the content of element B, based on the mass percentage of the glass matrix, is 5.0~10.0%, preferably 6.0~9.0%, and more preferably 6.5~8.5%.

[0053] Si (silicon) forms the main structural component of the glass network framework, promoting stable glass formation and effectively improving its viscosity, anti-crystallization properties, and chemical stability. Unlike the loose, chain-like layered network formed by boron (b), Si forms a dense and robust three-dimensional silicon-oxygen tetrahedral (SiO4) network in glass. This network strengthens the loose boron-oxygen triangular (BO3) and boron-oxygen tetrahedral (BO4) networks, making them denser and thus increasing the high-temperature viscosity of the glass. Simultaneously, the addition of the SiO4 three-dimensional network reduces the migration ability of elements such as la (La) and nb (Nb) outside the glass network, raising the crystallization threshold and improving the glass's anti-crystallization properties. However, excessive Si content leads to poorer meltability, an increased upper limit of crystallization temperature, and a higher glass transition temperature. Therefore, the Si content, by mass percentage of the glass matrix, is 0-3%, preferably 0.1-2%, and more preferably 0.2-1.5%.

[0054] In some specific embodiments, the inventors discovered through extensive experiments that the sum of the contents of Si and B elements, ∑(Si+B), has a decisive influence on the glass formation characteristics. If the sum of the contents of Si and B elements, ∑(Si+B), is too low, a stable glass cannot be formed; if the sum of the contents of Si and B elements, ∑(Si+B), is too high, the near-infrared refractive index and relative partial dispersion of the obtained glass are difficult to achieve the specific range of this invention. Therefore, in this invention, the sum of the contents of Si and B elements, ∑(Si+B), is 5.0% to 11.0% by mass percentage of the glass matrix; preferably 6.0% to 10.0%, more preferably 7.0% to 9.5%.

[0055] La (La) is an effective component for improving the refractive index and reducing relative partial dispersion in the near-infrared band of glass, and is a major component of this type of high-refractive-index optical glass. When the La content is too low, the near-infrared refractive index and relative partial dispersion of the glass will be difficult to reach the aforementioned specific ranges; when the La content is too high, the glass's devitrification tendency increases, the liquidus temperature rises, and the glass's specific gravity becomes excessive. In this invention, the La percentage, based on the mass percentage of the glass matrix, is 25.0% to 35.0%, preferably 27.0% to 34.0%, and more preferably 28.0% to 32.0%.

[0056] Nitrogen (Nb) element enhances the near-infrared refractive index, improves chemical stability, and improves crystallization properties of optical glass. In this invention, this effect is not significant when the Nb content is too low; however, when the Nb content is too high, the crystallization properties of the glass gradually deteriorate, making it difficult to achieve the desired optical performance, and the glass transition temperature increases. Therefore, in this invention, the Nb content, based on the mass percentage of the glass matrix, is 1.0% to 10.0%, preferably 3.0% to 9.0%, and more preferably 5.0% to 8.0%.

[0057] Zinc (Zn) is an effective component for improving the chemical and thermal stability of glass, as well as its refractive index in the near-infrared band. It can also reduce the high-temperature viscosity and Tg temperature of glass. Zn enters the glass's structural network as a zinc-oxygen octahedron [ZnO6] or a zinc-oxygen tetrahedron [ZnO4], making the glass structure more stable. If the Zn content is too high, the glass's resistance to crystallization decreases, and its high-temperature viscosity is low, making molding difficult. If the Zn content is too low, the desired effect cannot be achieved. Therefore, in this invention, the Zn content, based on the mass percentage of the glass matrix, is 15.0~25.0%, preferably 16.0~24.0%, and more preferably 17.0~23.0%.

[0058] In some specific implementations, in order to obtain glass with a low glass transition temperature, good stability, and easy melting, the inventors discovered through extensive experimental research that when the ratio of La to Zn content (La / Zn) is 1.0~2.0, preferably 1.4~1.8, the stability and Tg temperature of the glass can reach the optimal balance, resulting in a product of better quality.

[0059] Furthermore, in order to make the glass have excellent anti-crystallization properties, the ratio of the sum of La and Nb elements to the sum of Si and B elements, ∑(La+Nb) / ∑(Si+B), can be controlled to be 2.0~8.0, preferably 3.0~7.0, and more preferably 4.0~6.0.

[0060] Zr (zirconium) possesses properties that increase the refractive index in the near-infrared band and reduce relative partial dispersion. Introducing Zr into glass can improve its chemical stability and increase its near-infrared refractive index. When glass contains a large amount of rare earth elements, introducing a certain amount of Zr can reduce the glass's tendency to crystallize. However, when the Zr content is too high, it will increase the upper limit of the glass's crystallization temperature, increase the crystallization rate, worsen the glass's resistance to crystallization, and increase the glass transition temperature. Furthermore, Zr has a small ionic radius, high charge, and strong ionic field; when the Zr content is too high, it can cause anion accumulation, potentially leading to phase separation in the glass. Conversely, when the Zr content is too low, it does not have the desired effect. Therefore, in this invention, the Zr content, based on the mass percentage of the glass matrix, is 1.0~8.0%, preferably 2.0~6.0%, and more preferably 2.5~5.5%.

[0061] The Zn / Zr ratio directly affects the hardness and glass transition temperature of glass. A high Zn / Zr ratio significantly reduces the melting temperature and melt viscosity, thus lowering the glass transition temperature, but accelerates the depolymerization of the glass network, reducing its hardness. Conversely, a low Zn / Zr ratio significantly increases the melting temperature and refining temperature, while also increasing the degree of polymerization of the glass network, thus improving hardness, but negatively impacting the glass transition temperature. Therefore, in this invention, the Zn / Zr ratio can be 2.5–9.0, preferably 3.0–8.5, and more preferably 3.5–8.0.

[0062] O (oxygen) is the main structural element in the glass network framework. The atoms of Si and B, the main structural elements in the glass network framework, are located at the center of the glass network structure, surrounded by four or three O atoms, forming [SiO4] tetrahedra, [BO3] trigonometric prisms, or [BO4] tetrahedra. The oxygen atoms connecting two network forgings (such as Si-O-Si) are called bridging oxygen atoms. Bridging oxygen atoms form the "skeleton" of a robust, continuous three-dimensional random network, determining the optical properties, mechanical strength, chemical stability, and high / low temperature viscosity of the glass. Simultaneously, O also creates an environment for trace transition metal elements (such as Fe, Cr, Cu, Mn, etc.) in the glass to produce color, leading to glass coloration and reducing the glass's transmittance. Therefore, in this invention, the O content, based on the mass percentage of the glass matrix, is 25.0~38.0%, preferably 27.0~37.0%, and more preferably 29.0~36.0%.

[0063] In this invention, the content of O element directly determines the valence state of Nb element in the glass. The valence electron configuration of Nb element is 4d. 4 5s 1Common oxidation states of Nb include +2, +3, +4, and +5, each exhibiting a different color. Nb in the +5 oxidation state loses all its 4d electrons, resulting in no dd electron transitions and typically appearing white or colorless. Nb in the +3 and +4 oxidation states has unfilled d orbitals, and its dd electron transitions absorb visible light, resulting in dark colors such as black, blue, and red. In other words, the higher the oxidation state, the lighter the color. All Nb elements exhibit dd electron transitions, absorbing visible light and reducing the transmittance of the glass. The inventors of this invention discovered that the O / Nb ratio directly determines the amount of Nb in the glass. 5+ The O / Nb content is important. If the O / Nb ratio is too high, there are too few dd transitions in the glass, resulting in a lighter color, but this also leads to a decrease in the near-infrared refractive index. If the O / Nb ratio is too low, there are too many dd transitions in the glass, resulting in a darker color, which is detrimental to improving the glass's transmittance. Therefore, in this invention, the O / Nb ratio is 2.5~7.5, preferably 3.0~7.0, and more preferably 3.5~6.5.

[0064] Lithium (Li) acts as a glass network modifier, disrupting the silicon-oxygen (Si-O-Si) network and significantly reducing the melting temperature and viscosity of the glass, thus lowering the glass transition temperature. However, Li also reduces the near-infrared refractive index of the glass, which is detrimental to the control of optical properties. If the Li content is too high, the glass's resistance to crystallization decreases, making it prone to surface haze in precision-molded optical components, resulting in poor appearance. If the Li content is too low, it hinders the reduction of the glass transition temperature. In this invention, the Li content, based on the mass percentage of the glass matrix, is 0.01~1.0%, preferably 0.1~0.9%, and more preferably 0.2~0.7%.

[0065] In some specific embodiments, the optical glass further comprises Sb. Sb is an effective component for degassing molten glass and is an optional component in the optical glass of the present invention. Excessive Sb can easily alloy with melting equipment (especially precious metals such as Pt), causing glass discoloration. Therefore, the Sb content, based on the mass percentage of the glass matrix, does not exceed 500 ppm, preferably not more than 300 ppm, and more preferably not more than 200 ppm.

[0066] Furthermore, in this invention, the optical glass does not contain one or more of the elements Ti, Ta, Gd, W, Y, Yb, Ba, Bi, Ge, and Te. The optical glass of this invention does not contain Te, which easily causes volatile streaks, thus avoiding their formation; it does not introduce Ba, reducing corrosion of the melting equipment during glass production and lowering production costs; it does not introduce expensive elements such as Ge, Ta, Gd, W, and Y, reducing raw material costs; and it does not introduce Ti, which has a variable valence. Additionally, to better achieve the objectives of this invention, it emphasizes the absence of Yb, which has an absorption peak at 850 nm. Since Bi reacts with Pt at 1200-1250℃, increasing the difficulty of melting the glass and hindering the production of glass with excellent internal quality, the optical glass of this invention does not introduce Bi.

[0067] Furthermore, to ensure the spectral transmittance of the optical glass described in this invention, the optical glass provided by this invention does not artificially introduce other coloring elements besides the components mentioned above, such as V, Mo, Cr, Mn, Fe, Co, Ni, Cu, and Ag. Simultaneously, it does not artificially introduce compounds containing the following harmful elements, such as Th, Cd, Tl, Os, Be, Se, Pb, As, and Hg. Furthermore, this invention strictly controls the coloring impurities V, Mo, Cr, Mn, Fe, Co, Ni, and Cu in the raw materials, ensuring that the content of these coloring impurities in the raw materials is below 5 ppm.

[0068] Furthermore, in this invention, the glass transition temperature of the optical glass is below 560°C; the crystallization temperature of the optical glass is below 1020°C; and the density of the optical glass is 4.50 g / cm³. 3 The optical glass has the following characteristics: a relative abrasive hardness (FA) of less than 150; and a Knoop hardness (HK) of greater than 600 GPa. The wavelength λ of the optical glass at 80% external transmittance is also specified. 80 The wavelength is below 330 nm when the external transmittance is 5% and below 400 nm. In addition, the optical glass of the present invention has excellent chemical stability.

[0069] The present invention also provides a method for preparing optical glass according to the present invention, comprising: weighing and mixing the raw materials of each element of the glass in proportion, melting them, and then pouring or casting them into a molding mold, or directly pressing them into shape.

[0070] Specifically, the preparation method includes the following steps: weighing and mixing the raw materials containing the elements required for the optical glass of the present invention according to a certain proportion to prepare a batch; putting the prepared batch into a melting device (such as a platinum crucible); melting it into a glass melt at a temperature of 1250-1300℃; raising the temperature to 1300-1350℃ to homogenize and remove bubbles; and lowering the temperature to 1150-1200℃ to adjust the viscosity of the glass melt. The entire process takes about 4-6 hours. Finally, the glass is poured or poured into a molding mold, or directly pressed into shape, and then slowly cooled to obtain the optical glass.

[0071] Furthermore, the present invention also provides an aspherical optical component, which includes the optical glass described in the present invention; preferably, the optical glass is processed into a sphere or similar body, placed in an aspherical mold, heated to a temperature not higher than the molding temperature, and molded for 50 to 200 seconds under conditions not exceeding 500 kgf to obtain the optical glass aspherical lens.

[0072] The molding temperature of aspherical lenses can be determined based on the glass transition temperature (Tg). Generally, the molding temperature of aspherical lenses is a temperature 40°C to 90°C above the glass transition temperature of optical glass. That is, this application defines the temperature 40°C to 90°C above the glass transition temperature as the molding temperature of aspherical lenses.

[0073] Example

[0074] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0075] Examples 1-24 and Comparative Examples 1-5 used SiO2, H3BO3, La2O3, Nb2O5, ZnO or ZnO2, ZrO2, Li2CO3 or LiSO4·H2O as raw materials to introduce elements. These were weighed and mixed uniformly according to the proportions in Tables 1-6 to prepare a batch. The batch was then placed in a platinum crucible and melted into glass at 1275±25℃. The temperature was then raised to 1325±25℃ for homogenization and bubble removal, and lowered to 1175±25℃ to adjust the viscosity of the glass melt. After approximately 5 hours of this process, the glass was poured into a mold and slowly cooled to obtain optical glass.

[0076] Fabrication of aspherical optical components: After the optical glass of Examples 1-16 is polished into a sphere or similar shape required for molding, it is placed in a WC aspherical mold, heated to a temperature not exceeding the molding temperature, and molded for 150 s at 420 kgf to obtain the optical glass aspherical lens. In the examples, the molding temperature is the transition temperature (Tg) of the optical glass in each example plus 50°C.

[0077] Performance testing

[0078] 1. Glass transition temperature (Tg)

[0079] The glass transition temperature (Tg) of the optical glass was tested using a TMA tester from PE Corporation, USA.

[0080] 2. Near-infrared refractive index n s and relative partial dispersion PC,s

[0081] The refractive index (n) of the obtained optical glass was measured using a laser light source at 852.11 nm in the near-infrared band according to the test method in GB / T7962.11 "Test Methods for Colorless Optical Glass—Part 11: Precision Test of Visible Refractive Index". s The refractive indices nC and nF were measured using a hydrogen light source at wavelengths of 656.27 nm and 486.13 nm. The formula used was: Calculate the relative partial dispersion PC,s.

[0082] The near-infrared refractive index ns and relative partial dispersion PC,s obtained after processing and testing were recorded in the table after the sample was kept at (Tg-30)℃ for 10h, cooled to (Tg-200)℃ at a rate of -4℃ / h and then powered off to room temperature.

[0083] 3. Crystallization temperature L T

[0084] The crystallization temperature L was determined using a GM-N16P gradient furnace from Motoyama Corporation of Japan. T The determination.

[0085] 4. λ 80 With λ5

[0086] A glass specimen with a thickness of 10±0.1 mm and optically polished parallel planes is prepared. An incident light of intensity I is then injected into the glass specimen from a direction perpendicular to the planes. in The intensity I of the transmitted light is measured. out The strength is greater than I out / I in This is called the external transmittance of the glass.

[0087] In the wavelength range of 200~700nm, the wavelength corresponding to an external transmittance of 80% is denoted as λ. 80 The wavelength corresponding to an external transmittance of 5% is denoted as λ5.

[0088] 5. Density (ρ)

[0089] The measurement shall be performed in accordance with the method specified in GB / T7962.20 "Test methods for colorless optical glass—Part 20: density".

[0090] 6. Relative abrasive hardness (FA)

[0091] Relative abrasive hardness refers to the abrasive hardness of the tested glass relative to standard glass H-K9 under the same abrasive conditions. The relative abrasive hardness FA of the tested glass is calculated by multiplying the volumetric abrasive amount of the glass sample by the volumetric abrasive amount of the tested standard glass H-K9 sample by 100.

[0092] The specific test method for the volumetric grinding amount of the glass sample and the standard glass H-K9 sample is as follows: The glass sample and the standard glass H-K9 sample of the same size are fixed on a specific type of cast iron grinding disc using a clamp. A pressure of 1 kg is applied to both the sample and the standard sample. Then, a suspension of No. 40 corundum and water in a fixed ratio is added. The grinding disc is rotated at a speed of 60-65 rpm to grind the sample for 3 minutes. After grinding, the weight loss of the standard sample and the sample is measured and then converted into volumetric grinding amount.

[0093] 7. Knuth Hardness HK

[0094] The measurement shall be performed in accordance with the method specified in GB / T7962.18 "Test methods for colorless optical glass—Part 18: Kelvin hardness".

[0095] 8. Water resistance stability of powder coating (D) W

[0096] 10 g ± 0.0001 g of powdered glass (passed through a 40-32 mesh sieve) with a particle size of 425–560 μm was placed in a filter. The glass was then immersed in a quartz glass flask containing 80 mL of distilled water (pH = 6.5–7.5) and kept at a constant temperature of 98–100 °C for 60 minutes. All glass particles were then transferred to a pre-weighed filter, washed with 80 mL of anhydrous ethanol, and dried at 120 ± 5 °C to a constant weight. According to the formula: Calculate the glass leaching percentage. Where: D W —Percentage of glass leaching (%); B—Mass of filter and sample (in g); C—Mass of filter and etched sample (in g); A—Mass of filter (in g).

[0097] Based on the percentage of water leaching by mass, the water resistance stability D of optical glass is determined. W Classify according to Table a below.

[0098] Table a

[0099]

[0100] 9. Powder method acid resistance stability D A

[0101] With D W The determination method is similar; a 0.01 mol / L nitric acid aqueous solution is added to the flask for treatment, according to the formula: Calculate the glass leaching percentage. Where: D A —Percentage of glass leaching (%); B—Mass of filter and sample (in g); C—Mass of filter and etched sample (in g); A—Mass of filter (in g).

[0102] Based on the percentage of leaching by mass, the acid resistance stability D of optical glass is determined. A Classify according to Table b below.

[0103] Table b

[0104]

[0105] 10. Surface method resistance to humid atmosphere stability R C (S)

[0106] Under conditions of 50℃ and 85% relative humidity, the stability of optical glass against humid atmospheres is divided into three levels based on the time required for hydrolysis spots to form on the polished glass surface, as shown in Table c.

[0107] Table c

[0108]

[0109] 11. Surface method acid resistance stability R A (S)

[0110] Under the action of acetic acid solution at 0.1N (pH=2.9) and 50℃, the acid resistance stability of optical glass is divided into three levels according to the time required for interference colors to appear on the polished glass surface, or for the surface to show discoloration or peeling, as shown in Table d.

[0111] Table d

[0112]

[0113] 12. Surface method alkali resistance stability R OH (S)

[0114] A 40mm × 40mm × 5mm sample, polished on all six sides, was immersed in a 0.01mol / L sodium hydroxide aqueous solution at a constant temperature of 50℃ ± 3℃ for 15 hours with thorough stirring. The leaching mass per unit area was calculated as mg / (cm²). 2 •15h), to improve the alkali resistance stability R of optical glass OH (S) is divided into five levels, as shown in Table e.

[0115] Table e

[0116]

[0117] 13. Surface method wash resistance stability RP(S)

[0118] A 35mm × 35mm × 8mm sample, polished on all six sides, was immersed in Na₅P₃O₂ at a constant temperature of 50℃ ± 3℃ and a concentration of 0.01mol / L with thorough stirring. 10 In aqueous solution for 1 hour. Based on the average leaching mass per unit area, the unit is mg / (cm²). 2 The washability stability RP(S) of optical glass is divided into five levels, as shown in Table f.

[0119] Table f

[0120]

[0121] 14. Appearance of aspherical optical components

[0122] The main appearance defects of aspherical optical components are haze and surface imperfections, as detailed below:

[0123] Fog condition: Against a black background, using a 27W fluorescent lamp, rotate the lens under transmitted light. The dense white (blue) dots seen in the center of the lens are recorded as white fog dots (blue fog dots). When the white (blue) fog dots merge into a patch, it is called a white (blue) fog spot. If they do not merge into a patch, there is no fog.

[0124] Surface defects: Under a black background, using a 27W fluorescent lamp, observe the inspected lens under reflected light, and compare the inspected lens with the limit sample to determine its appearance. Surface defects are assessed using common surface defects (i.e., pitting) and long scratches.

[0125] Surface defects are generally represented by 5 / N×A. Where 5 is the code for the surface defect, N×A is the permissible defect level, N is the maximum permissible number of defects, and A is the square root of the maximum permissible defect area.

[0126] Long scratches are represented by 5 / LN×A. Where 5 is the code for surface defects, L is the code for long scratches, N is the number of long scratches allowed, and A is the maximum allowable width of the scratch.

[0127] The near-infrared refractive index n of the optical glasses prepared in Examples 1-24 and Comparative Examples 1-4 s Relative partial dispersion PC,s, transition temperature Tg, liquidus temperature L T When the external transmittance reaches 80%, the corresponding wavelength λ 80 When the external transmittance reaches 5%, the corresponding wavelength λ5, density ρ, relative abrasive hardness (FA), Knoop strength HK, and water resistance stability D are also considered. W (Powder method), acid resistance stability D A (Powder method), stability against humid atmosphere R C (S) (Surface method), acid resistance stability R A (S)(Surface method), Alkali resistance stability R OH (S) (surface method), washability stability RP(S) (surface method), appearance of precision molded optical parts, etc., are listed in Table 1-5.

[0128] Table 1: Examples 1 to 6

[0129]

[0130] Table 2: Examples 7 to 12

[0131]

[0132] Table 3: Examples 13-18

[0133]

[0134] Table 4: Examples 19-24

[0135]

[0136] Table 5: Comparative Examples 1 to 4

[0137]

[0138] As can be seen from Tables 1-4, the glass of embodiments (1-24) of the present invention has the required near-infrared refractive index n. s And relatively partially dispersed PC,s; glass transition temperature below 560℃; crystallization temperature below 1020℃; density of 4.50 g / cm³ 3The following parameters are required: relative abrasive hardness (FA) below 150; Knoop hardness (HK) above 600 GPa; wavelength λ at 80% external transmittance. 80 It has wavelengths below 330 nm when the external transmittance is 5% and below 400 nm, and also has excellent chemical stability.

[0139] In addition, the aspherical optical components manufactured by precision molding using the optical glass of the present invention do not exhibit fogging on the surface, thus economically meeting the needs of optical components.

[0140] The glasses in Comparative Examples 1-3 contain expensive W and / or Ta, resulting in high raw material costs and hindering cost reduction for optical components. Comparative Example 3, due to its excessively high W content, has a wavelength λ at an external transmittance of 80%. 80 The wavelength at which the external transmittance is 5% is higher than 330nm, exceeding 400nm. The glass transition temperatures of Comparative Examples 2 and 4 are too high, increasing the molding cost of the optical components. Comparative Examples 2 and 4, due to the presence of Ti, have a wavelength λ at which the external transmittance is 80%. 80 The wavelength is above 400nm, and the wavelength with an external transmittance of 5% is above 330nm. When molding aspherical optical components using the optical glass of Comparative Examples 2-4, there are still appearance problems.

[0141] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0142] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. An optical glass, characterized in that, The optical glass comprises a glass matrix, which contains the following elements by mass percentage: B: 5.0~10.0%, preferably 6.0~9.0%; Si: 0~3.0%, preferably 0.1~2.0%; La: 25.0%~35.0%, preferably 27.0%~34.0%; Nb: 1.0%~10.0%, preferably 3.0%~9.0%; Zn: 15.0~25.0%, preferably 16.0~24.0%; Zr: 1.0~8.0%, preferably 2.0~6.0%; Li: 0.01~1.0%, preferably 0.1~0.9%; O: 25.0~38.0%, preferably 27.0~37.0%; The near-infrared refractive index n of the optical glass s The relative partial dispersion PC,s is 1.75~1.82, and the relative partial dispersion is 0.45~0.

55.

2. The optical glass according to claim 1, characterized in that, The total content of Si and B elements, ∑(Si+B), is 5.0%~11.0% by mass; preferably 6.0%~10.0%. The ratio of the sum of La and Nb content to the sum of Si and B content, ∑(La+Nb) / ∑(Si+B), is 2.0~8.0, preferably 3.0~7.

0.

3. The optical glass according to claim 1 or 2, characterized in that, The content ratio of La to Zn, by mass percentage, is 1.0 to 2.0, preferably 1.4 to 1.8; The ratio of Zn to Zr is 2.5 to 9.0, preferably 3.0 to 8.

5.

4. The optical glass according to any one of claims 1-3, characterized in that, The O / Nb ratio, by mass percentage, is 2.5 to 7.5, preferably 3.0 to 7.

0.

5. The optical glass according to any one of claims 1-4, characterized in that, The optical glass also contains Sb; preferably, the content of Sb is no more than 500 ppm by mass percentage of the glass matrix, and more preferably no more than 300 ppm.

6. The optical glass according to any one of claims 1-5, characterized in that, The optical glass does not contain one or more of the elements Ti, Ta, Gd, W, Y, Yb, Ba, Bi, Ge, and Te.

7. The optical glass according to any one of claims 1-6, characterized in that, The glass transition temperature of the optical glass is below 560°C; the crystallization temperature of the optical glass is below 1020°C. The density of the optical glass is 4.50 g / cm³. 3 The optical glass has the following characteristics: a relative abrasive hardness (FA) of less than 150; and a Knoop hardness (HK) of greater than 600 GPa.

8. The optical glass according to any one of claims 1-7, characterized in that, The wavelength λ of the optical glass when its external transmittance is 80% 80 The wavelength is below 330nm when the external transmittance is 5% and below 400nm.

9. A method for preparing optical glass according to any one of claims 1-8, characterized in that, This includes weighing and mixing the raw materials of each element of the optical glass described in any one of claims 1-8 in proportion, melting them, and then pouring or casting them into a molding die, or directly pressing them into shape.

10. An aspherical optical component, characterized in that, Includes the optical glass according to any one of claims 1-8.

Images