CN109987838B

CN109987838B - Optical glass, glass preform, optical element and optical instrument

Info

Publication number: CN109987838B
Application number: CN201910333444.XA
Authority: CN
Inventors: 匡波; 卢家金
Original assignee: CDGM Glass Co Ltd
Current assignee: CDGM Glass Co Ltd
Priority date: 2019-04-24
Filing date: 2019-04-24
Publication date: 2022-04-15
Anticipated expiration: 2039-04-24
Also published as: CN109987838A

Abstract

The invention provides optical glass with a refractive index of 1.58-1.64 and an Abbe number of 35-40, which comprises the following components in percentage by weight: SiO 2₂：52～62％、TiO₂：15～25％、Na₂O：2～12％、K₂O：2～12％、B₂O₃: 0 to 10% of TiO₂/SiO₂The range of (A) is 0.25 to 0.45. Through reasonable component design, the optical glass of the invention has lower density and excellent devitrification resistance while obtaining the expected refractive index and Abbe number, and is suitable for precision die pressing.

Description

Optical glass, glass preform, optical element and optical instrument

Technical Field

The invention relates to optical glass, in particular to optical glass with a refractive index of 1.58-1.64 and an Abbe number of 35-40, and a glass prefabricated member, an optical element and an optical instrument made of the optical glass.

Background

In recent years, with the rapid popularization and use of digital cameras, video cameras, and camera phones, optical materials have also been rapidly developed toward high precision and miniaturization. Among optical element molding methods, precision press molding has become the mainstream. Precision press-molding of glass is to mold a glass preform with a mold having a predetermined shape under pressure at high temperature to obtain a glass molded article having the shape of a final product or very close to the shape thereof. Molded articles having a desired shape can be mass-produced at high yield by precision press molding. Due to the high accuracy of the required geometry, this pressing method has to use sophisticated precision instruments and therefore requires expensive mould materials, the lifetime of such moulds greatly affects the yield of the produced product, an important factor for the long lifetime of the moulds is that the working temperature is as low as possible. To meet the above requirements, there is an increasing demand for optical glasses having high quality, low density and low transition temperature.

CN1141889A discloses an optical glass with a refractive index of 1.52-1.65 and an Abbe number of 35-50, which contains 6-35% of Nb₂O₅Which not only leads to an increase in the density and cost of the glass, but also increases the risk of devitrification of the glass.

Disclosure of Invention

The invention aims to provide optical glass which has low density and excellent devitrification resistance and is suitable for precision die pressing.

The technical scheme adopted by the invention for solving the technical problem is as follows: the optical glass comprises the following components in percentage by weight: SiO 2₂：52～62％、TiO₂：15～25％、Na₂O：2～12％、K₂O：2～12％、B₂O₃: 0 to 10% of TiO₂/SiO₂The range of (A) is 0.25 to 0.45.

Further, the optical glass comprises the following components in percentage by weight: and (3) RO: 0 to 5% of Li₂O：0～5％、ZnO：0～5％、ZrO₂：0～5％、Al₂O₃: 0-5% of a clarifying agent: 0-1%, wherein RO is one or more of MgO, CaO, SrO and BaO, and the clarifying agent is Sb₂O₃、SnO₂SnO and CeO₂One or more of (a).

Further, the optical glass comprises the following components in percentage by weight: SiO 2₂: 55-60%, and/or B₂O₃: greater than 0% but less than or equal to 8%, and/or TiO₂: 17 to 22% and/or Na₂O: 5 to 11%, and/or K₂O: 5-11%, and/or RO: 0 to 3%, and/or Li₂O: 0-3%, and/or ZnO: 0 to 2%, and/or ZrO₂: 0 to 2%, and/or Al₂O₃: 0-2%, and/or a clarifying agent: 0-0.5%, wherein RO is one or more of MgO, CaO, SrO and BaO, and the clarifying agent is Sb₂O₃、SnO₂SnO and CeO₂One or more of (a).

Further, the optical glass comprises the following components in percentage by weight: b is₂O₃: 1-5%, and/or RO: 0 to 2%, and/or Li₂O: 0-1%, and/or ZnO: 0 to 1%, and/or ZrO₂: 0 to 1%, and/or Al₂O₃：0～1％。

Further, the optical glass comprises the following components in percentage by weight: (Na)₂O+K₂O)/TiO₂Is in the range of 0.4 to 1.3, preferably (Na)₂O+K₂O)/TiO₂Is in the range of 0.6 to 1.2, more preferably (Na)₂O+K₂O)/TiO₂The range of (A) is 0.8 to 1.1.

Further, the optical glass comprises the following components in percentage by weight: TiO 2₂/SiO₂In the range of 0.30 to 0.42, preferably TiO₂/SiO₂The range of (A) is 0.30 to 0.40.

Further, the optical glass comprises the following components in percentage by weight: na (Na)₂O/K₂O is in the range of 0.5 to 2, preferably Na₂O/K₂O is in the range of 0.6 to 1.5, and Na is more preferable₂O/K₂The range of O is 0.8 to 1.2.

Further, the optical glass comprises the following components in percentage by weight: b is₂O₃/TiO₂In the range of 0.02 to 0.5, preferably B₂O₃/TiO₂In the range of 0.05 to 0.4, more preferably B₂O₃/TiO₂The range of (A) is 0.1 to 0.3.

Further, the above optical glass does not contain Li₂O, and/or does not contain ZnO, and/or does not contain ZrO₂And/or does not contain Al₂O₃。

Further, the refractive index nd of the optical glass is 1.58 to 1.64, preferably 1.60 to 1.63; the Abbe number vd is 35 to 40, preferably 36 to 39.

Further, the moisture resistance stability RC of the above optical glass is 2 or more, preferably 1; and/or acid stability RA is 2 or more, preferably 1; and/or lambda₈₀Less than or equal to 400nm, preferably lambda₈₀In the range of less than or equal to 395 nm; and/or lambda₅Less than or equal to 370nm, preferably lambda₅In the range of less than or equal to 365 nm; and/or a density p of 2.80g/cm³Hereinafter, it is preferably 2.75g/cm³Hereinafter, more preferably 2.70g/cm³The following.

The glass preform is made of the optical glass.

And the optical element is made of the optical glass or the glass prefabricated member.

The optical instrument is made of the optical glass or the optical element.

The invention has the beneficial effects that: through reasonable component design, the optical glass of the invention has lower density and excellent devitrification resistance while obtaining the expected refractive index and Abbe number, and is suitable for precision die pressing.

Detailed Description

The optical glass of the present invention is obtained by the following steps, which are not limited to the above-described embodiments, and can be appropriately modified within the scope of the object of the present invention. Note that, although the description of the duplicate description may be appropriately omitted, the gist of the invention is not limited to this. The optical glass of the present invention may be simply referred to as glass in the following.

[ optical glass ]

The ranges of the respective components of the optical glass of the present invention are explained below. In the present specification, the contents of the respective components are all expressed in terms of weight percentage with respect to the total amount of glass substances of the components converted into oxides, if not specifically stated. Here, the "component converted to oxide" means that when oxides, complex salts, hydroxides, and the like used as raw materials of the optical glass component components of the present invention are decomposed in the melt and converted to oxides, the total amount of the oxides is 100%.

Unless otherwise indicated herein, the numerical ranges set forth herein include upper and lower values, and the terms "above" and "below" include the endpoints, and all integers and fractions within the range, and are not limited to the specific values listed in the defined range. As used herein, "and/or" is inclusive, e.g., "A and/or B," and means A alone, B alone, or both A and B.

< essential Components and optional Components >

SiO₂Present as a skeleton in the present invention, is an essential component of the present invention by introducingSiO of 52% or more₂Since the glass composition has an effect of improving the thermal stability of the glass, is effective in obtaining a viscosity suitable for forming when the glass solution is formed, and when the content exceeds 62%, the melting property of the glass deteriorates and the transition temperature increases, 52 to 62% of SiO is introduced in the present invention₂Preferably, 55-60% of SiO is introduced₂。

B₂O₃Also an oxide forming the glass, and when the content thereof exceeds 10%, the refractive index of the glass is lowered, volatility during melting is increased, fluctuation of optical constant of the glass is caused and chemical stability of the glass is deteriorated, and in order to obtain an optical glass having a desired optical constant range and excellent chemical stability, B₂O₃The content of (B) is limited to 0 to 10%, preferably more than 0% but 8% or less, more preferably 1 to 5%.

TiO₂Has the effect of increasing the refractive index of the glass, can participate in the formation of a glass network, and can also improve the mechanical properties and chemical stability of the glass, and when the content thereof is less than 15%, the above effects cannot be obtained, but when the content thereof exceeds 25%, the glass is easily devitrified, and the short-wavelength transmittance of the glass is deteriorated. Thus, TiO₂The content of (b) is limited to 15 to 25%, preferably 17 to 22%.

After a great deal of experimental research by the inventor, if TiO is used in the invention₂/SiO₂Below 0.25, the glass transition temperature rises and the chemical stability decreases; if TiO₂/SiO₂When the amount exceeds 0.45, the devitrification resistance of the glass tends to deteriorate and the density tends to increase, so that TiO in the present invention₂/SiO₂The range of (A) is 0.25 to 0.45, preferably 0.30 to 0.42, and more preferably 0.30 to 0.40.

In some embodiments of the invention, B is prepared by reacting₂O₃/TiO₂In the range of 0.02 to 0.5, volatilization of the glass can be suppressed and coloring of the glass can be reduced, and B is preferably used₂O₃/TiO₂0.05 to 0.4, and more preferably B₂O₃/TiO₂0.1 to 0.3.

Na₂O is an essential component of the present invention, notOnly has the function of reducing the glass transition temperature and has stronger fluxing function. Relative to K₂O，Na₂O can reduce the high-temperature viscosity of the glass, and is beneficial to eliminating bubbles and stripes. However, when the content is less than 2%, the effect of lowering the transition temperature and the effect of fluxing are not significant, and when the content is more than 12%, devitrification resistance and chemical stability of the glass are drastically lowered. Thus, Na₂The content of O is 2 to 12%, preferably 5 to 11%.

K₂O also has the effect of lowering the glass transition temperature and fluxing. Relative to Na₂O，K₂O can improve the transparency and the gloss of the glass and improve the devitrification resistance of the glass. In the invention K₂The content of O is 2 to 12%, preferably 5 to 11%.

Through a great deal of experimental research of the inventor, the (Na) is controlled₂O+K₂O)/TiO₂A value of (A) is 0.4 or more, an optical glass having a low transition temperature and a low density can be obtained relatively easily at the same time, but when (Na)₂O+K₂O)/TiO₂A value of more than 1.3 lowers the chemical stability of the glass. Thus, in the present invention (Na)₂O+K₂O)/TiO₂Is in the range of 0.4 to 1.3, preferably (Na)₂O+K₂O)/TiO₂Is in the range of 0.6 to 1.2, more preferably (Na)₂O+K₂O)/TiO₂The range of (A) is 0.8 to 1.1.

In some embodiments of the invention, the compound is prepared by reacting Na₂O/K₂O is in the range of 0.5-2, so that the glass has excellent bubble degree and striae degree and simultaneously the chemical stability of the glass is obviously improved, and Na is preferred₂O/K₂O is 0.6 to 1.5, more preferably Na₂O/K₂O is 0.8 to 1.2.

Li₂O also has the effect of lowering the glass transition temperature, but when the content thereof exceeds 5%, the devitrification resistance of the glass deteriorates, and Li₂O causes severe corrosion of platinum crucible, so Li in the present invention₂The content of O is 0 to 5%, preferably 0 to 3%, more preferably 0 to 1%, and further preferably no introduction.

The alkaline earth metal oxide RO is one or more of MgO, CaO, SrO and BaO, the devitrification resistance and the chemical stability of the glass can be improved by introducing a small amount, and when the content exceeds 5%, the devitrification tendency of the glass is increased, so that the amount of RO introduced in the present invention is 0 to 5%, preferably 0 to 3%, more preferably 0 to 2%.

ZnO has the effect of lowering the transition temperature of the glass and improving chemical stability, and when the content thereof exceeds 5%, the devitrification resistance of the glass deteriorates. Therefore, the content of ZnO is limited to 0 to 5%, preferably 0 to 2%, more preferably 0 to 1%, and further preferably not incorporated.

ZrO₂Can improve the refractive index and chemical stability of the glass, and has proper amount of ZrO₂The content of the glass is higher than 5%, the glass is difficult to melt, the melting temperature is increased, inclusions are easy to appear in the glass, the transmittance of the glass is reduced, the manufacturing cost of the glass is increased, and the product competitiveness is reduced. Thus, ZrO of the present invention₂The content of (b) is 0 to 5%, preferably 0 to 2%, more preferably 0 to 1%, and further preferably no incorporation.

Al₂O₃The chemical stability of the glass can be improved, but when the content exceeds 5%, the refractive index of the glass is lowered and the meltability is deteriorated. Thus, Al of the invention₂O₃The content of (b) is 0 to 5%, preferably 0 to 2%, more preferably 0 to 1%, and further preferably no incorporation.

Sb₂O₃、SnO₂SnO and CeO₂One or more of the components can be added as a fining agent by adding a small amount of Sb₂O₃、SnO₂、CeO₂The component can improve the fining effect of the glass, but when Sb is used₂O₃When the content exceeds 1%, the glass tends to have a reduced fining property and the deterioration of the forming mold is promoted by the strong oxidation thereof, so that Sb in the present invention₂O₃The amount of (B) is 1% or less, preferably 0.5% or less. SnO₂SnO may be added as a fining agent, but when the content exceeds 1%, the glass is colored, or when the glass is heated, softened and subjected to refiningSince Sn becomes a starting point of nucleation and tends to devitrify during re-molding such as press molding, the SnO of the present invention₂And SnO are contained in an amount of 1% or less, preferably 0.5% or less, and more preferably not incorporated. CeO (CeO)₂Action and addition amount ratio of (B) and SnO₂The content is 1% or less, preferably 0.5% or less, and more preferably no incorporation.

In order to easily obtain a desired refractive index and Abbe number while obtaining an optical glass having a low transition temperature and density and excellent chemical stability and coloring degree, SiO is preferable₂、B₂O₃、TiO₂、Na₂O and K₂The total content of O is 95% or more, more preferably 98% or more, and still more preferably 99% or more.

< component which should not be contained >

In the glass of the present invention, even when a small amount of oxides of transition metals such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo is contained singly or in combination, the glass is colored and absorbs at a specific wavelength in the visible light region, thereby impairing the property of the present invention to improve the effect of visible light transmittance.

In recent years, oxides of Th, Cd, Tl, Os, Be, and Se tend to Be used as harmful chemical substances in a controlled manner, and measures for protecting the environment are required not only in the glass production process but also in the processing process and disposal after commercialization. Therefore, when importance is attached to the influence on the environment, it is preferable that these components are not substantially contained except for inevitable mixing. Thereby, the optical glass becomes practically free from substances contaminating the environment. Therefore, the optical glass of the present invention can be manufactured, processed, and discarded without taking special measures for environmental countermeasures.

In order to achieve environmental friendliness, the optical glass of the present invention does not contain As₂O₃And PbO. Although As₂O₃With elimination of bubbles and better prevention of glass stainingEffect, but As₂O₃The addition of (b) increases the platinum attack of the glass on the furnace, particularly on the platinum furnace, resulting in more platinum ions entering the glass, which adversely affects the service life of the platinum furnace. PbO can significantly improve the high-refractivity and high-dispersion properties of the glass, but PbO and As₂O₃All cause environmental pollution.

The term "not introduced", "not containing" or "0%" as used herein means that the compound, molecule or element is not intentionally added as a raw material to the optical glass of the present invention; however, it is within the scope of the present invention that certain impurities or components which are not intentionally added may be present as raw materials and/or equipment for producing the optical glass and may be contained in the final optical glass in small or trace amounts.

The performance of the optical glass of the present invention will be described below.

< refractive index and Abbe number >

Refractive index (nd) and Abbe number (. nu.) of optical glass_d) The test was carried out according to the method specified in GB/T7962.1-2010.

The refractive index (nd) of the optical glass is 1.58-1.64, preferably 1.60-1.63; abbe number (v)_d) 35 to 40, preferably 36 to 39.

< moisture resistance stability >

The moisture resistance stability (RC) (surface method) of the optical glass was measured according to the method prescribed in GB/T7962.15-2010.

The moisture resistance stability (RC) (surface method) of the optical glass of the present invention is 2 or more, preferably 1.

< stability against acid >

The acid Resistance (RA) of the optical glass (surface method) was tested according to the method specified in GB/T7962.14-2010.

The acid resistance stability (RA) (surface method) of the optical glass of the present invention is 2 or more, preferably 1.

< degree of coloration >

Lambda for the degree of coloration of optical glass₈₀/λ₅And (4) showing. Lambda [ alpha ]₈₀Means the transmittance of the glassWavelength, λ, corresponding to 80%₅The wavelength corresponding to the glass transmittance of 5% is referred to. Wherein λ is₈₀Was measured using a glass having a thickness of 10. + -. 0.1mm with two opposing planes parallel to each other and optically polished, measuring the spectral transmittance in the wavelength region from 280nm to 700nm and showing a wavelength of transmittance of 80%. The spectral transmittance or transmittance is the intensity I of light incident perpendicularly to the surface of the glass_inLight transmitted through the glass and having an intensity I emitted from a plane_outIn the case of light of (1) through (I)_out/I_inThe quantity expressed and also the transmission of the surface reflection losses on the above-mentioned surface of the glass.

Optical glass lambda of the present invention₈₀Less than or equal to 400nm, preferably lambda₈₀In the range of less than or equal to 395 nm; lambda [ alpha ]₅Less than or equal to 370nm, preferably lambda₅Is less than or equal to 365 nm.

< Density >

The density (. rho.) of the optical glass was measured according to the method specified in GB/T7962.20-2010.

The optical glass of the present invention has a density (. rho.) of 2.80g/cm³Hereinafter, it is preferably 2.75g/cm³Hereinafter, more preferably 2.70g/cm³The following.

[ production method ]

The method for manufacturing the optical glass comprises the following steps: the glass is produced by adopting conventional raw materials and conventional processes, carbonate, nitrate, sulfate, oxide and the like are used as raw materials, the materials are mixed according to a conventional method, the mixed furnace burden is put into a smelting furnace at 1300-1400 ℃ for smelting, and the homogeneous molten glass without bubbles and undissolved substances is obtained after clarification, stirring and homogenization, and the homogeneous molten glass is cast in a mold and annealed. Those skilled in the art can appropriately select the raw materials, the process method and the process parameters according to the actual needs.

Glass preform and optical element

The glass preform can be produced from the optical glass produced by, for example, grinding or press molding such as reheat press molding or precision press molding. That is, the glass preform may be produced by machining the optical glass by grinding, polishing, or the like, or by producing a preform for press molding from the optical glass, subjecting the preform to reheat press molding, and then polishing, or by precision press molding the preform obtained by polishing.

It should be noted that the means for producing the glass preform is not limited to the above means. As described above, the optical glass of the present invention is useful for various optical elements and optical designs, and among them, it is particularly preferable to form a preform from the optical glass of the present invention, and use the preform for reheat press forming, precision press forming, or the like to produce optical elements such as lenses, prisms, or the like.

The glass preform of the present invention and the optical element are each formed of the above-described optical glass of the present invention. The glass preform of the present invention has excellent characteristics possessed by optical glass; the optical element of the present invention has excellent characteristics of optical glass, and can provide optical elements such as various lenses and prisms having high optical values.

Examples of the lens include various lenses such as a concave meniscus lens, a convex meniscus lens, a double convex lens, a double concave lens, a plano-convex lens, and a plano-concave lens, each of which has a spherical or aspherical lens surface.

[ optical instruments ]

The optical element formed by the optical glass can be used for manufacturing optical instruments such as photographic equipment, camera equipment, display equipment, monitoring equipment and the like.

Examples

< example of optical glass >

In order to further clarify the explanation and explanation of the technical solution of the present invention, the following non-limiting examples are provided.

In this example, optical glasses having the compositions shown in tables 1 to 2 were obtained by the above-mentioned method for producing optical glasses. The characteristics of each glass were measured by the test method described in the present invention, and the measurement results are shown in tables 1 to 2.

TABLE 1

TABLE 2

< glass preform example >

Various lenses such as a concave meniscus lens, a convex meniscus lens, a biconvex lens, a biconcave lens, a plano-convex lens and a plano-concave lens, and preforms such as prisms were produced from the glasses obtained in examples 1 to 20 of optical glass by means of polishing or press molding such as reheat press molding and precision press molding.

< optical element example >

The preforms obtained in the above examples of glass preforms were annealed to reduce the deformation in the glass and to fine-tune the optical properties such as refractive index to desired values.

Next, each preform is ground and polished to produce various lenses such as a concave meniscus lens, a convex meniscus lens, a biconvex lens, a biconcave lens, a plano-convex lens, and a plano-concave lens, and prisms. The surface of the resulting optical element may be coated with an antireflection film.

< optical Instrument example >

The optical element obtained by the above-described optical element embodiment is used for, for example, imaging devices, sensors, microscopes, medical technologies, digital projection, communications, optical communication technologies/information transmission, optics/lighting in the automobile field, photolithography, excimer lasers, wafers, computer chips, and integrated circuits and electronic devices including such circuits and chips, or for image pickup devices and apparatuses in the vehicle-mounted field, by forming an optical component or an optical assembly by using one or more optical elements through optical design.

Claims

1. Optical glass, characterized in that its components, expressed in weight percent, contain: SiO 2₂：52～62％、TiO₂：15～25％、Na₂O：2～12％、K₂O：2～12％、B₂O₃: 0 to 10% of TiO₂/SiO₂In the range of 0.25 to 0.42, B₂O₃/TiO₂The range of (A) is 0.02 to 0.255.

2. The optical glass according to claim 1, wherein the composition, expressed in weight percent, further comprises: and (3) RO: 0 to 5% of Li₂O：0～5％、ZnO：0～5％、ZrO₂：0～5％、Al₂O₃: 0-5% of a clarifying agent: 0-1%, wherein RO is one or more of MgO, CaO, SrO and BaO, and the clarifying agent is Sb₂O₃、SnO₂SnO and CeO₂One or more of (a).

3. An optical glass according to claim 1 or 2, characterised in that its composition, expressed in weight percent, comprises: SiO 2₂: 55-60%, and/or B₂O₃: greater than 0% but less than or equal to 8%, and/or TiO₂: 17 to 22% and/or Na₂O: 5 to 11%, and/or K₂O: 5-11%, and/or RO: 0 to 3%, and/or Li₂O: 0-3%, and/or ZnO: 0 to 2%, and/or ZrO₂: 0 to 2%, and/or Al₂O₃: 0-2%, and/or a clarifying agent: 0-0.5%, wherein RO is one or more of MgO, CaO, SrO and BaO, and the clarifying agent is Sb₂O₃、SnO₂SnO and CeO₂One or more of (a).

4. An optical glass according to claim 1 or 2, characterised in thatThe components of the composition are expressed by weight percentage and comprise: b is₂O₃: 1-5%, and/or RO: 0 to 2%, and/or Li₂O: 0-1%, and/or ZnO: 0 to 1%, and/or ZrO₂: 0 to 1%, and/or Al₂O₃：0～1％。

5. An optical glass according to claim 1 or 2, characterised in that its composition, expressed in weight percentages, is such that: (Na)₂O+K₂O)/TiO₂The range of (A) is 0.4 to 1.3.

6. An optical glass according to claim 1 or 2, characterised in that its composition, expressed in weight percentages, is such that: (Na)₂O+K₂O)/TiO₂The range of (A) is 0.6 to 1.2.

7. An optical glass according to claim 1 or 2, characterised in that its composition, expressed in weight percentages, is such that: (Na)₂O+K₂O)/TiO₂The range of (A) is 0.8 to 1.1.

8. An optical glass according to claim 1 or 2, characterised in that its composition, expressed in weight percentages, is such that: TiO 2₂/SiO₂The range of (A) is 0.30 to 0.42.

9. An optical glass according to claim 1 or 2, characterised in that its composition, expressed in weight percentages, is such that: TiO 2₂/SiO₂The range of (A) is 0.30 to 0.40.

10. An optical glass according to claim 1 or 2, characterised in that its composition, expressed in weight percentages, is such that: na (Na)₂O/K₂The range of O is 0.5 to 2.

11. An optical glass according to claim 1 or 2, characterised in that its composition, expressed in weight percentages, is such that: na (Na)₂O/K₂The range of O is 0.6 to 1.5.

12. An optical glass according to claim 1 or 2, characterised in that its composition, expressed in weight percentages, is such that: na (Na)₂O/K₂The range of O is 0.8 to 1.2.

13. An optical glass according to claim 1 or 2, characterised in that its composition, expressed in weight percentages, is such that: b is₂O₃/TiO₂The range of (A) is 0.05 to 0.255.

14. An optical glass according to claim 1 or 2, characterised in that its composition, expressed in weight percentages, is such that: b is₂O₃/TiO₂The range of (A) is 0.1 to 0.255.

15. An optical glass according to claim 1 or 2, characterised in that it does not contain Li₂O, and/or does not contain ZnO, and/or does not contain ZrO₂And/or does not contain Al₂O₃。

16. The optical glass according to claim 1 or 2, wherein the refractive index nd of the optical glass is 1.58 to 1.64; the Abbe number vd is 35-40.

17. The optical glass according to claim 1 or 2, wherein the refractive index nd of the optical glass is 1.60 to 1.63; the Abbe number vd is 36-39.

18. The optical glass according to claim 1 or 2, wherein the optical glass has a moisture resistance stability RC of 2 or more types; and/or the acid stability RA is of more than 2 types; and/or lambda₈₀Less than or equal to 400 nm; and/or lambda₅Less than or equal to 370 nm; and/or a density p of 2.80g/cm³The following.

19. An optical glass according to claim 1 or 2, wherein the optical glass has a moisture resistance stability RC of class 1(ii) a And/or acid stability RA is of class 1; and/or lambda₈₀In the range of less than or equal to 395 nm; and/or lambda₅In the range of less than or equal to 365 nm; and/or a density p of 2.75g/cm³The following.

20. The optical glass according to claim 1 or 2, wherein the optical glass has a density p of 2.70g/cm³The following.

21. A glass preform made of the optical glass according to any one of claims 1 to 20.

22. An optical element produced from the optical glass according to any one of claims 1 to 20 or the glass preform according to claim 21.

23. An optical device comprising the optical glass according to any one of claims 1 to 20 or the optical element according to claim 22.