CN111116039A

CN111116039A - Dense crown optical glass

Info

Publication number: CN111116039A
Application number: CN202010005214.3A
Authority: CN
Inventors: 毛露路; 何波; 郝良振
Original assignee: CDGM Glass Co Ltd
Current assignee: CDGM Glass Co Ltd
Priority date: 2016-11-07
Filing date: 2016-11-07
Publication date: 2020-05-08
Anticipated expiration: 2036-11-07
Also published as: CN106495469B; CN106495469A; CN111116039B

Abstract

The invention provides dense crown optical glass with good weather resistance and low cost, wherein the refractive index of the dense crown optical glass is 1.56-1.62, and the Abbe is 57-64. Dense crown optical glass having a composition, expressed in mole percent, comprising: SiO 2₂45‑65％、B₂O₃10‑25％、Al₂O₃3-10% of BaO, 15-30% of BaO, and the viscosity is lower than 50dPaS at the temperature of 1400 ℃. Through reasonable component proportion design, the glass has lower cost of raw materials, better weather resistance and better process performance, and the viscosity is lower than 50dPaS at the temperature of 1400 ℃; the weatherability is 3 grade or above, which can fully meet the market demand of optical glass with lower price and better performance.

Description

Dense crown optical glass

The application is a divisional application of an invention patent application with application number 201610975562.7, application date 2016, 11, 7 and named "dense crown optical glass".

Technical Field

The invention relates to dense crown optical glass, in particular to dense crown optical glass with a refractive index of 1.56-1.62 and an Abbe of 57-64, which has low cost and good weather resistance and process performance.

Background

The optical glass with the refractive index of 1.56-1.62 and the Abbe number of 57-64 belongs to dense crown optical glass, is widely applied to imaging lenses, telescopes, gun sighting telescope and other optical systems, and is a great amount of basic material in the field of optical glass.

In recent years, as the market competition of terminals such as cameras and telescopes is becoming more and more intense, terminal manufacturers are demanding optical glasses with lower price and better performance to meet the market competition. The cost of optical glass is mainly composed of raw material cost, production cost and subsequent processing cost. Therefore, there are three main approaches to reducing the cost of such dense crown optical glasses:

1) in the aspect of raw materials: on the basis of ensuring that key indexes such as refractive index, Abbe number, transmittance and the like reach the standard, the raw materials with lower price are preferentially adopted, and the raw materials with higher price, such as rare earth raw materials, are reduced or even not used;

2) the process aspect is as follows: the components are reasonably proportioned, and the viscosity of the glass in key working procedures such as clarification, forming and the like is well adjusted, for example: if the viscosity at 1400 ℃ is less than 50dPaS, the maximum melting temperature may not exceed 1400 ℃. In the production process, common adverse factors such as bubbles, stripes and inclusions are easy to remove.

3) Since the dense crown glass having the refractive index and the abbe number within the above ranges is generally very poor in weather resistance, generally less than 3-grade in weather resistance, is liable to cause flaws during cleaning after polishing, requires an additional special protective process and requires a low-humidity storage environment, thus increasing the process, difficulty and cost. Even if a special protection process and a low-humidity production environment are adopted, in actual production, the yield of the glass is still low compared with that of optical glass with better weather resistance. Therefore, the improvement of the weather resistance of the glass is a key factor for improving the subsequent processing yield and reducing the subsequent processing cost.

US3510325A discloses a glazing of similar optical propertiesContains 42-46% of B₂O₃20-25% of CaO and 14-16% of La₂O₃But such a high content of B₂O₃Poor weather resistance and cost increase are caused, and 14-16% of La is used₂O₃The acid resistance of the glass is reduced, the cost of raw materials is increased, and the consumption of rare earth resources is increased.

US005744409A discloses glasses containing 7-12% Li₂O, excessive Li₂O causes rapid deterioration of the weatherability and devitrification resistance of the glass. When thick products are produced, particularly products with the thickness of more than 40mm, the speed of the inner part of the glass becoming solid is far slower than the speed of the surface of the glass becoming solid, so that the middle part of the glass is easy to generate stripes and is easy to scrap. In addition, it contains a large amount of Li₂The glass of O is liable to contaminate the mold when used for precision press molding.

Therefore, the invention aims to develop a dense crown optical glass with excellent comprehensive performance aiming at the defects of the optical dense crown glass.

Disclosure of Invention

The invention aims to solve the technical problem of providing the dense crown optical glass with better weather resistance and lower cost, wherein the refractive index of the dense crown optical glass is 1.56-1.62, and the Abbe is 57-64.

The technical scheme adopted by the invention for solving the technical problem is as follows: dense crown optical glass having a composition, expressed in mole percent, comprising: SiO 2₂45-65％、B₂O₃10-25％、Al₂O₃3-10% of BaO, 15-30% of BaO, and the viscosity is lower than 50dPaS at the temperature of 1400 ℃.

Further, the composition comprises, in mole percent: 0-5% of MgO, 0-8% of CaO, 0-5% of SrO0, and La₂O₃0-4％、ZrO₂0-3％、TiO₂0-0.5％、Li₂O 0-4％、Sb₂O₃0-1％。

Dense crown optical glass having a composition, expressed in mole percent, of: SiO 2₂45-65％、B₂O₃10-25％、Al₂O₃3-10％、BaO 15-30％、MgO 0-5％、CaO 0-8％、SrO 0-5％、La₂O₃0-4％、ZrO₂0-3％、TiO₂0-0.5％、Li₂O 0-4％、Sb₂O₃0-1％。

Further, wherein SiO₂47-63%; and/or B₂O₃12 to 23 percent; and/or Al₂O₃4 to 8 percent; and/or BaO 16-28%.

Further, wherein, MgO is 0-3%; and/or 0-3% of CaO; and/or SrO 0-3%; and/or La₂O₃0 to 2 percent; and/or ZrO₂0 to 2 percent; and/or TiO₂0 to 0.2 percent; and/or Li₂0-2% of O; and/or Sb₂O₃0-0.5％。

Further, wherein SiO₂48-59%; and/or B₂O₃13 to 20 percent; and/or Al₂O₃4 to 7 percent; and/or BaO 17-26%.

Further, wherein SiO₂/B₂O₃Is 1.5-6.

Further, wherein B₂O₃/Al₂O₃Is 2-10.

Further, wherein SiO₂18-45% of- (BaO + SrO + CaO + MgO).

Further, the content of each component meets one or more than one of the following 3 conditions:

1)SiO₂/B₂O₃is 2 to 5;

2)B₂O₃/Al₂O₃is 3 to 8;

3)SiO₂the content of- (BaO + SrO + CaO + MgO) is 22-42%.

1)SiO₂/B₂O₃2.5 to 4;

2)B₂O₃/Al₂O₃is 3.5 to 7;

3)SiO₂25-38% of- (BaO + SrO + CaO + MgO).

Further, a viscosity of less than 50dPaS at a temperature of 1400 ℃; the weatherability is 3 grade or more; the refractive index is 1.56-1.62; abbe number is 57-64.

Further, a viscosity of less than 40dPaS at a temperature of 1400 ℃; a refractive index of 1.57 to 1.61; abbe number is 58-62.

The glass preform is made of the optical glass.

The optical element is made of the optical glass.

The invention has the beneficial effects that: through reasonable component proportion design, the glass has lower cost of raw materials, better weather resistance and better process performance, and the viscosity is lower than 50dPaS at the temperature of 1400 ℃; the weather resistance is 3 grade or above, the refractive index is 1.56-1.62, the Abbe number is 57-64, and the optical glass can fully meet the market demand of optical glass with lower price and better performance.

Detailed Description

I, optical glass

The optical glass of the invention has better weather resistance and process performance under the condition of having optical performance of refractive index (nd) of 1.56-1.62 and Abbe number (vd) of 57-64 based on the consideration of reducing the cost of raw materials and reducing or even not containing expensive raw materials such as rare earth and the like.

The individual components of the glass according to the invention will be described below, the contents of the individual components being expressed in mol% unless otherwise stated.

[ essential Components and optional Components ]

In the glass of the present invention, SiO₂Is a main glass forming body and is a main component constituting a glass skeleton. If the content is more than 65%, the refractive index of the glass is lower than the design expectation, and the melting of the glass raw material becomes difficult and the high-temperature viscosity increases; if the content is less than 45%, the glass tends to rapidly deteriorate in weather resistance and devitrification resistance. Therefore, in the present invention, SiO₂The content of (B) is 45 to 65%, preferably 47 to 63%, and more preferably 48 to 59%.

B₂O₃Also one of the glass formers, to which glass B is added in a suitable amount₂O₃The skeleton structure of the glass can be more compact, the refractive index and the weather resistance of the glass are improved, and the high-temperature viscosity of the glass is reduced. At the same time B₂O₃Also a flux, which makes it easier to melt the raw materials. In the glasses of the present invention, if B₂O₃Content higher than 25%, B₂O₃The coordination structure in the glass is transformed to a loose structure, thereby reducing the weather resistance of the glass; if the content is less than 10%, the fluxing effect is not obvious, the high-temperature viscosity of the glass is increased, and the weather resistance is reduced. Thus, B₂O₃The content of (B) is 10 to 25%, preferably 12 to 23%, and more preferably 13 to 20%.

SiO₂And B₂O₃All are network formers of glass, but their structure and function formed in glass are different. The material structure determines the material performance, and the proportional relation of the two network formers is closely related to the internal structure of the glass. That is, in the glass of the present system, SiO₂And B₂O₃The ratio of (A) to (B) is closely related to the melting property, weather resistance and high-temperature viscosity of the glass. If SiO₂/B₂O₃If the ratio is too high, the melting property of the glass is poor, the high-temperature viscosity is increased, and the stability of the glass is reduced; if SiO₂/B₂O₃Too low, the weatherability of the glass is drastically reduced. The inventor researches and discovers that when SiO is used₂/B₂O₃When the ratio of (A) to (B) is in the range of 1.5 to 6, preferably 2 to 5, and more preferably 2.5 to 4, the glass has the most balanced melting property, weather resistance and high-temperature viscosity.

Li₂O belongs to alkali metal oxide, and is added into silicate system glass to break the main network of the glass, reduce the high temperature viscosity of the glass and make the production of the glass easier. More importantly, Li₂The amount of O in the glass of the present invention is in greater relation to the weathering resistance of the glass of the present invention which is most concerned. Small amount of Li₂O improves the weather resistance of the glass, but when the content of O exceeds 4 percent, the weather resistance and the devitrification resistance of the glass are reduced, and products with the thickness of more than 40mm are not easy to produce. At the same time due toLi₂O is very expensive, and if it is added in an amount exceeding 4%, the raw material cost is 2 to 3 times more expensive relative to glass to which this component is not added. Thus, in the glass component of the present invention, Li₂The content of O is 0 to 4%, preferably 0 to 2%, and more preferably not added. Na of the same family₂O and K₂O small amount of substituted Li₂O, which can lower the high-temperature viscosity of the glass but causes a sharp decrease in weather resistance, is not contained in the glass of the present invention₂O and K₂O。

Adding an appropriate amount of Al₂O₃The density of the glass network can be improved, the weather resistance and the glass forming stability of the glass are improved, and the refractive index and the dispersion of the glass can be adjusted. But excessive Al₂O₃The addition of (2) can cause the problems that the glass is difficult to melt, the dispersion cannot reach the design expectation, the high-temperature viscosity is increased, the abrasion degree of the glass is increased, the processing efficiency is reduced and the like; and Al₂O₃Too little results in instability of the glass, a decrease in devitrification resistance, and a decrease in weather resistance. In addition, to lower the melting temperature of the raw materials, the Al of such glasses₂O₃By using Al (OH)₃Is introduced in the form of (1). Due to the current Al (OH)₃Limitation of production Process, Al (OH)₃The iron impurities in the glass are not easy to remove completely, and the transmittance is rapidly deteriorated due to excessive addition of the iron impurities. Therefore, Al in the present invention₂O₃The content of (B) is 3 to 10%, preferably 4 to 8%, and more preferably 4 to 7%.

Further, B is present in the glass₂O₃In the case of (3), Al₂O₃And B₂O₃The relative content of (A) will affect Al₂O₃And B₂O₃The network in the glass forms a structure, which in turn affects the stability, weatherability, high temperature viscosity, and devitrification resistance of the glass. The inventor researches and discovers that when B is₂O₃/Al₂O₃When the ratio of (A) to (B) is more than 10, the glass is extremely unstable, devitrification is serious, and devitrification resistance is reduced; if B is₂O₃/Al₂O₃When the ratio is less than 2, the glass is deteriorated in weather resistance and increased in high-temperature viscosity. Therefore, the temperature of the molten metal is controlled,when B is present₂O₃/Al₂O₃When the ratio of (A) to (B) is in the range of 2 to 10, preferably 3 to 8, and more preferably 3.5 to 7, the glass is optimum in stability, weather resistance, high temperature viscosity and devitrification resistance.

Small amount of TiO₂The refractive index and dispersion of the glass can be improved, and the sunlight resistance and weather resistance of the glass are improved. However, the addition of too much of the glass can cause the transmittance of the glass in the ultraviolet band to be reduced sharply, so that a high-transmittance product is not easy to obtain. Thus, TiO₂The content of (B) is 0 to 0.5%, preferably 0 to 0.2%, and more preferably no addition.

BaO, SrO, CaO and MgO belong to alkaline earth metal oxides, and when the BaO, the SrO, the CaO and the MgO are added into glass, the refractive index and the dispersion of the glass can be adjusted, the high-temperature viscosity of the glass is reduced, and the stability of the glass is enhanced. Too much alkaline earth metal oxide may cause the glass to have undesirable refractive index, dispersion and weather resistance, while the glass has reduced short-wave transmittance and weather resistance; if the amount of the alkaline earth metal oxide added is too small, the glass will have an unexpected refractive index and dispersion, and the glass will have a reduced stability and an increased high-temperature viscosity. In addition, the effects of the above four alkaline earth metal oxides in the glass are still greatly different in the glasses according to the invention.

If the amount of CaO added is too large, although it contributes to improvement of the weatherability of the glass, the Abbe number of the glass is lower than the design target, and the devitrification resistance and stability of the glass are deteriorated. In addition, CaCO is generally used as CaO₃Introduction of, ordinary grade of, CaCO₃The coloring impurities such as medium iron, manganese and the like are more in content, and the glass is easily colored and scrapped; if high-purity CaCO is used₃The glass cost will rise rapidly.

If the amount of MgO added is too large, although it contributes to improvement of the weatherability of the glass, the refractive index of the glass does not meet the design requirements, the devitrification resistance of the glass and the stability of the glass are deteriorated, and the cost of the glass is rapidly increased.

The addition of SrO to glass can adjust the refractive index and abbe number of glass, but if the addition amount is too large, the weatherability and devitrification resistance of glass decrease, the refractive index and abbe number of glass do not meet the design expectations, and the cost of glass rapidly increases.

In the case of such high-refractive low-dispersion dense crown optical glasses, it is most appropriate to add BaO for adjustment, which raises the refractive index of the glass and at the same time achieves a smaller dispersion than other alkaline earth oxides. If the addition amount of BaO is too much, however, the anti-crystallization performance and the weather resistance of the glass can be rapidly reduced, and the glass is easy to overflow out of the pot in the melting process; if the amount of addition is too small, the stability of the glass is lowered, the high-temperature viscosity is increased, and the cost is rapidly increased.

Therefore, from the viewpoint of the combination of performance and cost, the glass of the present invention is mainly added with BaO, and the respective contents thereof are defined as follows:

the BaO content is limited to 15 to 30%, preferably 16 to 28%, and more preferably 17 to 26%.

The CaO content is limited to 0 to 8%, preferably 0 to 3%, and more preferably not added.

The SrO content is limited to 0 to 5%, preferably 0 to 3%, and more preferably not added.

The MgO content is limited to 0 to 5%, preferably 0 to 3%, and more preferably not added.

Further, the alkaline earth metal oxide breaks down SiO₂The glass network, the alkaline earth metal oxide and SiO₂The relative content of (A) is closely related to the stability, high temperature viscosity, weather resistance and stability of the glass. The inventor researches and discovers that when SiO is used₂When the value of- (BaO + SrO + CaO + MgO) is more than 45%, the glass has improved weather resistance, but the glass has increased high-temperature viscosity, reduced devitrification resistance and reduced glass stability. If SiO₂If the value of- (BaO + SrO + CaO + MgO) is less than 18%, the glass will have a sharp drop in weather resistance and glass forming stability, and SiO₂The value of- (BaO + SrO + CaO + MgO) is preferably 18 to 45%, more preferably 22 to 42%, and still more preferably 25 to 38%.

Small amount of La₂O₃When added to glass, the glass composition can increase the refractive index and dispersion of the glass and improve the weather resistance of the glass, but when the amount of the additive exceeds 4%, the glass composition is resistant to abrasionThe crystallization performance is lowered and particularly the cost is sharply increased. Therefore, La in the present invention₂O₃The content is limited to 0 to 4%, preferably 0 to 2%, and more preferably not added.

Small amount of ZrO₂The glass is added to improve the refractive index and dispersion of the glass, improve the weather resistance and devitrification resistance of the glass, reduce the erosion of glass liquid to refractory materials and prolong the service life of the refractory materials. However, if the content exceeds 3%, the glass is not easily dissolved, and there is a risk of generation of stones in the glass product. Thus, ZrO in the invention₂The content is limited to 0 to 3%, preferably 0 to 2%, and more preferably not added.

Sb₂O₃Is a fining agent, and is added into the glass to facilitate bubble elimination. In the present invention, the content is limited to 0 to 1%, preferably 0 to 0.5%, and more preferably not added.

[ Components which should not be contained ]

If necessary, other components not mentioned above can be added within a range not impairing the characteristics of the glass of the present invention. However, since the glass is colored and absorbs at a specific wavelength in the visible light region even when a small amount of a transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo is contained alone or in combination, thereby reducing the property of the present invention to improve the effect of the visible light transmittance, it is preferable that the optical glass, which requires transmittance at a wavelength in the visible light region, is not substantially contained.

In recent years, components such as Pb, 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. Thus, the optical glass contains virtually no 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.

The properties of the optical glass of the present invention will be described below:

[ optical constants of optical glass ]

The refractive index and Abbe number of the optical glass of the invention are tested according to the method specified in GB/T7962.1-2010. Through tests, the refractive index (nd) of the optical glass is more than 1.56, preferably more than 1.57, and more preferably more than 1.575; the upper limit is 1.62 or less, preferably 1.61 or less. An abbe number (vd) of 57 or more, preferably 58 or more, more preferably 59 or more; the upper limit is 64 or less, preferably 63 or less, and more preferably 62 or less.

[ high temperature viscosity ]

High temperature viscosity is measured using a high temperature viscometer with the numerical unit dPaS, the smaller the value, the smaller the viscosity. The optical glass of the present invention has a viscosity of not higher than 50dPaS, preferably not higher than 40dPaS, more preferably not higher than 30dPaS at a temperature of 1400 ℃.

[ weather resistance ]

The weather resistance test is carried out by placing the polished sample into a weather resistant box, testing the polished sample for 30 hours at 90% humidity and 40-50 ℃ in an environment circulating once per hour, and then testing the turbidity of the sample by using a spherical turbidimeter, wherein the larger the turbidity difference △ H, the worse the weather resistance, and Table 1 is a weather resistance rating table.

TABLE 1 weather resistance rating table

The test shows that the weather resistance of the optical glass is 3 grades and above.

II, glass preform and optical element

Next, the optical preform and the optical element of the present invention are described.

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 the same optical and chemical characteristics as those of the above-mentioned optical glass; the optical element of the present invention has the same optical characteristics and chemical characteristics as those of the above optical glass, and can provide various optical elements such as lenses and prisms having high optical values at low cost.

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.

In addition, the prism can be incorporated into an imaging optical system, and the optical path can be bent to a desired direction, whereby a compact and wide-angle optical system can be realized.

Meanwhile, the glass can be used for drawing materials such as optical fibers and the like.

Examples

[ optical glass examples ]

In order to further understand the technical solution of the present invention, examples of the optical glass of the present invention will now be described. It should be noted that these examples do not limit the scope of the present invention.

The optical glasses (examples 1 to 20) shown in tables 1 and 2 were obtained by weighing and mixing general raw materials (such as oxides, hydroxides, carbonates, nitrates, etc.) for optical glasses in the ratios of the respective examples shown in the tables, placing the mixed raw materials in a platinum crucible, melting at 1300-.

Compositions, refractive indices (nd), Abbe numbers (vd), and weather resistances (C) of examples 1 to 20 of the present invention are shown in tables 1 and 2_R) The viscosity at 1400 ℃ is expressed by F, SiO₂/B₂O₃The value is denoted by K1; b is₂O₃/Al₂O₃Is denoted by K2; SiO 2₂The value of- (BaO + SrO + CaO + MgO) is represented by K3.

TABLE 1

TABLE 2

mol％	11	12	13	14	15	16	17	18	19	20
											SiO₂	52.00	52.00	60.00	46.00	55.70	62.00	49.00	58.00	50.00	54.70
B₂O₃	18.60	18.60	15.00	22.00	16.00	15.00	18.00	18.00	16.00	17.90
											Al₂O₃	4.80	4.80	3.00	4.00	3.90	3.50	3.20	4.00	4.00	4.40
La₂O₃	0.40	0.40	0.20	3.00	0.00	0.00	0.00	0.00	0.00	0.00
											ZrO₂	0.60	0.60	0.20	1.00	0.00	0.00	0.00	0.00	0.00	0.00
TiO₂	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
											BaO	23.50	17.50	21.30	22.00	21.60	19.00	28.80	20.00	30.00	22.90
SrO	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
											CaO	0.00	6.00	0.00	2.00	0.00	0.00	0.00	0.00	0.00	0.00
MgO	0.00	0.00	0.30	0.00	0.00	0.00	0.00	0.00	0.00	0.00
											Li₂O	0.00	0.00	0.00	0.00	2.70	0.50	1.00	0.00	0.00	0.00
Sb₂O₃	0.10	0.10	0.00	0.00	0.10	0.00	0.00	0.00	0.00	0.10
											Total up to	100.00	100.00	100.00	100.00	100.00	100.00	100.00	100.00	100.00	100.00
K1	2.80	2.80	4.00	2.09	3.48	4.13	2.72	3.22	3.13	3.06
											K2	3.88	3.88	5.00	5.50	4.10	4.29	5.63	4.50	4.00	4.07
K3	28.50	28.50	38.40	22.00	34.10	43.00	20.20	38.00	20.00	31.80
											Nd	1.58912	1.58723	1.57977	1.61743	1.59112	1.57118	1.61115	1.57470	1.61457	1.58993
Vd	61.60	61.04	60.36	57.14	61.10	62.34	58.36	62.25	57.40	61.25
											C_R	2	2	2	2	2	1	3	2	3	3
F(dPaS)	17	16	39	14	6	27	8	41	16	21

[ glass preform examples ]

The optical glasses obtained in examples 1 to 20 in table 1 were cut into a predetermined size, and then a release agent was uniformly applied to the surface of the optical glass, followed by heating, softening, and press-molding to prepare preforms of various lenses and prisms 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.

[ optical element examples ]

The preforms obtained from the above glass preform examples were annealed to reduce the internal deformation of the glass and to perform fine adjustment so that the optical properties such as refractive index and the like could be brought 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.

The invention is dense crown optical glass with low cost and excellent weather resistance, the refractive index is 1.56-1.62, the Abbe is 57-64, and an optical element formed by the glass can meet the requirements of modern novel photoelectric products.

Claims

1. Dense crown optical glass, characterized in that its composition, expressed in mole percentages, contains: SiO 2₂45-65％、B₂O₃10-25％、Al₂O₃3-10% of BaO, 15-30% of BaO, and the viscosity is lower than 50dPaS at the temperature of 1400 ℃.

2. The dense crown optical glass according to claim 1, wherein the composition, expressed in terms of mole percent, further comprises: MgO 0-5%, CaO 0-8%, SrO 0-5%, La₂O₃0-4％、ZrO₂0-3％、TiO₂0-0.5％、Li₂O 0-4％、Sb₂O₃0-1％。

3. The dense crown optical glass is characterized by comprising the following components in percentage by mole: SiO 2₂45-65％、B₂O₃10-25％、Al₂O₃3-10％、BaO 15-30％、MgO 0-5％、CaO 0-8％、SrO 0-5％、La₂O₃0-4％、ZrO₂0-3％、TiO₂0-0.5％、Li₂O 0-4％、Sb₂O₃0-1％。

4. The dense crown optical glass according to any one of claims 1-3, wherein the SiO is₂47-63%; and/or B₂O₃12 to 23 percent; and/or Al₂O₃4 to 8 percent; and/or BaO 16-28%.

5. The dense crown optical glass according to any one of claims 1-3, wherein MgO is 0-3%; and/or 0-3% of CaO; and/or SrO 0-3%; and/or La₂O₃0 to 2 percent; and/or ZrO₂0 to 2 percent; and/or TiO₂0 to 0.2 percent; and/or Li₂0-2% of O; and/or Sb₂O₃0-0.5％。

6. The dense crown optical glass according to any one of claims 1-3, wherein the SiO is₂48-59%; and/or B₂O₃13 to 20 percent; and/or Al₂O₃4 to 7 percent; and/or BaO 17-26%.

7. The dense crown optical glass according to any one of claims 1-3, wherein the SiO is₂/B₂O₃Is 1.5-6.

8. The dense crown optical glass according to any one of claims 1-3, wherein B is₂O₃/Al₂O₃Is 2-10.

9. The dense crown optical glass according to any one of claims 1-3, wherein the SiO is₂18-45% of- (BaO + SrO + CaO + MgO).

10. An optical glass according to any one of claims 1 to 3, wherein the content of each component satisfies one or more of the following 3 conditions:

1)SiO₂/B₂O₃is 2 to 5;

2)B₂O₃/Al₂O₃is 3 to 8;

3)SiO₂the content of- (BaO + SrO + CaO + MgO) is 22-42%.

11. An optical glass according to any one of claims 1 to 3, wherein the content of each component satisfies one or more of the following 3 conditions:

1)SiO₂/B₂O₃2.5 to 4;

2)B₂O₃/Al₂O₃is 3.5 to 7;

3)SiO₂25-38% of- (BaO + SrO + CaO + MgO).

12. An optical glass according to any one of claims 1 to 3, wherein the viscosity is less than 50dPaS at a temperature of 1400 ℃; the weatherability is 3 grade or more; the refractive index is 1.56-1.62; abbe number is 57-64.

13. An optical glass according to any one of claims 1 to 3, wherein the viscosity is less than 40dPaS at a temperature of 1400 ℃; a refractive index of 1.57 to 1.61; abbe number is 58-62.

14. A glass preform made of the optical glass according to any one of claims 1 to 13.

15. An optical element made of the optical glass according to any one of claims 1 to 13.