WO2014161358A1

WO2014161358A1 - High-refraction optical glass and method of fabricating same

Info

Publication number: WO2014161358A1
Application number: PCT/CN2013/090302
Authority: WO
Inventors: 王自力; 黄�俊
Original assignee: 成都尤利特光电科技有限公司
Priority date: 2013-04-03
Filing date: 2013-12-24
Publication date: 2014-10-09
Also published as: CN103145331B; CN103145331A

Abstract

A high-refraction, high dispersion optical glass has high transmittance, low glass density, desirable anti-devitrification, and applicability to repeated pressing in a secondary hot pressing process. The optical glass contains SiO₂, B₂O₃, Gd₂O₃, Nb₂O₅, TiO₂, BaO, CaO, Ta₂O₅, ZnO, Li₂O, and ZrO₂ as essential components, but does not contain Bi₂O₃. The glass has an index of refraction (nd) of at least 1.88, an Abbe number (Vd) of 23 to 26, a glass density smaller than 4.2g/cm³, and a transition temperature (Tg) lower than 610°C.

Description

High refractive optical glass and method of manufacturing same

Technical field

The present invention relates to a high refractive, high dispersion optical glass, and a method of making the same. More specifically, the present invention particularly relates to an optical constant having a specific range of refractive index (nd) of 1.88 or more and an Abbe number (vd) of 23 to 26, and having high transmission and low density. , good stability of optical glass.

Background technique

In recent years, with the rapid spread of SLR cameras and their widespread use in people's lives, optical materials used as optical systems in SLR cameras have been widely used, especially as high refractive index, high dispersion glass, which not only satisfies The design requirements of the optical system of high-performance digital cameras need to meet the requirements and high definition requirements of large-size lenses for SLR optical systems.

The development of optical glass with a low Abbe number is very useful for the design of optical systems for SLR cameras. By combining two sets of optical lenses with different Abbe numbers or larger differences, the chromatic aberration of the two-color light can be reduced or eliminated, thereby improving the imaging quality of the lens.

As such optical glass in the field of high refraction and high dispersion, there are many types, such as phosphate series glass, or such series of Bi ₂ 0 ₃ components, regardless of the refractive index or Abbe number. Glass. However, such glass will bring the glass to a deep coloring and low transmittance, and the glass will be darkened after the ultraviolet light is irradiated, which not only increases the insurmountable defects of the lens manufacturing and subsequent processing, but also satisfies the camera. High transmission requirements for optical systems.

In the manufacturing process of optical glass, as the refractive index increases, the coloring tendency of the glass increases, especially for high refractive, high dispersion optical glass, the coloring will become more serious as the dispersion value increases. In particular, when the glass which is colored by the tendency is used, the blue light sensitivity of the short-wavelength side of the base color in the optical imaging system of the camera is lowered, which seriously affects the definition of the image quality.

Moreover, for such high-refraction, high-dispersion optical glass, the stability of the glass and the good resistance to devitrification during the secondary hot pressing process are repeated and repeated hot pressing in the pressed blank. There is no key to fog and devitrification on the surface.

As such high-refraction, high-dispersion optical glass having a refractive index (nd) of 1.88 or more and an Abbe number (vd) of 23 to 26, the optical characteristics currently known and belonging to the present range have not been seen. The refractive index of the glass described in the earlier patent document CN1204073C is within this range, but the glass Abbe number (vd) is greater than 27, and the glass density is large and the resistance to devitrification is poor; CN101012103A, the refractive index (nd) thereof belongs to the scope of the present invention. But the dispersion value is low, the Abbe number is greater than 26 or more, and then CN1835895A, CN101318769A, although the Abbe number (vd) is 26 or lower, the refractive index (nd) is less than 1.88, which is quite different from the optical constant of the present invention, and cannot meet the design requirements of the current novel SLR optical system; In the case of multiple hot pressing, there is no defect on the surface of the blank, and CN1204073C, CN101012103A, CN1835895A are difficult to overcome the fogging and opacity formed on the surface of the profile in the secondary hot pressing due to its high devitrification temperature. Furthermore, it is necessary to consider the improvement of glass transmission and manufacturing stability, as well as low-cost operation, so the above drawbacks are obvious.

Summary of the invention

It is an object of the present invention to provide not only an optical constant having the above-described range and meeting the requirements of the optical system design of a camera, but also achieving good stability against devitrification without introducing expensive components. Quantitative production of costs and achieving good secondary hot pressing. At the same time, the lens is lighter at a lower density, reducing the weight of the whole machine. With a low transition temperature (Tg), it is suitable for the drawing of precision moldings. And overcome the above shortcomings and defects.

Moreover, another object of the present invention is to achieve high transmission of the optical lens, maximally meeting the design requirements of the optical system of the SLR camera.

The optical glass of the present invention contains: Si0 ₂ , B ₂ 0 ₃ , Gd ₂ 0 ₃ , Nb ₂ 0 ₅ , Ti0 ₂ , BaO, CaO, Ta ₂ 0 ₅ , ZnO, Li ₂ 0, ZrO^ are essential components The optical glass has an optical constant of a refractive index nd greater than 1.88 and an Abbe number vd of 23-26.

Wherein, when expressed by 1%), the optical glass contains the following components:

10~25% of Si0 ₂

The condition of 1~11% B ₂ 0 ₃ is: (Si02/ B203 ) The weight ratio is greater than 2

5~15% of Gd ₂ 0 ₃

15~30% of Nb ₂ 0 ₅

The 5~22% Ti0 ₂ condition is: (Nb205/ Ti02) The weight ratio is greater than 1

10~30% BaO

3~15% CaO

Ta ₂ 0 ₅ greater than 0 but less than 5%

ZnO larger than 0~ but less than 5%

The condition of Li ₂ 0 greater than 0 but less than 6% is: (ZnO+Li20) Zr0 _{2 with a} weight ratio of less than 1 and less than 5%

0~5% of W0 ₃

0 to 5% of K ₂ 0

0~5% SrO

0~2% of Sn0 ₂

0 or more but less than 1% of Sb ₂ 0 ₃ .

Preferably, when expressed as 1%), the optical glass contains the following components: 12~22% of Si0 ₂

The condition of 2~8% B ₂ 0 ₃ is: (Si02/ B203 ) Gd ₂ 0 _{3 with} weight ratio greater than 2 6~12%

16~28% of Nb ₂ 0 ₅

The 7-20% Ti0 ₂ condition is: (Nb205/ Ti02) The weight ratio is greater than

12~28% BaO

4~11% CaO

Ta ₂ 0 ₅ greater than 0 but less than 4%

ZnO larger than 0~ but less than 4%

Li ₂ 0 conditions greater than 0 but less than 5% are: (ZnO/Li20) Zr0 _{2 with a} weight less than 4%

0~4% of W0 ₃

0 to 3% of K ₂ 0

0~3% of SrO

0~1% of Sn0 ₂

0 or more but less than 0.5% of Sb ₂ 0 _{3 o}

Preferably, the optical glass contains the following components:

Si0 ₂ 14.5-21.5%;

B ₂ 0 ₃ 2.7-6.9%;

Gd ₂ 0 ₃ 6.1-10.9%;

Nb ₂ 0 ₅ 19.2-26.7%;

Ti0 ₂ 11.3-18.3;

BaO 12.5-26.0%;

CaO 3.0-9.2%;

Ta ₂ 0 ₅ 0.6-3.8 %;

ZnO 0.6-2.8%;

Li ₂ 0 1.6-3.5%;

Zr0 ₂ 0.7-3.2%;

W03 0-3.1%;

K ₂ 0 0-1.0%;

SrO 0-1.0%;

Sn0 ₂ 0-0.4%;

Sb ₂ 0 ₃ 0.1%.

Wherein, the internal transparency of the glass is less than 412.

Wherein, the density of the glass is not higher than 4.2 g/cm ³ . Wherein, the glass transition temperature Tg is not higher than 610 ° C, and the liquidus temperature L _{T is} not higher than 1080

°C.

The method for producing an optical glass according to the present invention comprises the steps of: producing a blank formed of the optical glass described above by cooling from a uniform glass liquid into a specific molding die through a leak device and solidifying to a constant thickness and width.

The method for manufacturing a secondary hot pressing member according to the present invention is to cut and process the rough material into a required size and weight, and then soften it by heating, and press-form it in a softened state to obtain a pressed blank of different shapes. .

The method for producing a precision molded preform according to the present invention comprises the steps of: softening the optical glass by the foregoing, and drawing the preform into a preform in a softened state.

In order to achieve the above requirements, the present invention has been found through repeated investigations to pass SiO ₂ , B ₂ 0 ₃ , Gd ₂ 0 ₃ , Nb ₂ 0 ₅ , Ti0 ₂ , BaO, CaO, Ta ₂ _{5 5} , ZnO, Li. ₂₀ , the optimized ratio of the necessary components and the introduction adjustment of optional components such as W0 ₃ , SrO, K ₂ 0, and not only when the Bi ₂ 0 ₃ component and the expensive rare earth component are introduced, The optical constant having the above specific range, and also having high transmission, low glass density, and low transition temperature are satisfied not only for the secondary hot pressing but also for the drawing of the precision press preform.

The results of the present invention also found that the ratio of SiO 2 /B 203 content is adjusted to be greater than 2 or greater, and the weight ratio of ZnO/Li 20 is less than 1, and the adjustment and ratio are optimized to have a specific optical constant, a low glass density, and In addition to the low transition temperature, the optical glass which is further improved in transmission, further optimized in devitrification resistance, and has good stability is also obtained, thereby completing the present invention.

Hereinafter, the glass components constituting the glass 1 to 10 included in the optical glass of the present invention and the percentage (%) of the content of each component and the total content of each group will be respectively expressed by Wt%:

In order to achieve the above various properties, the optical glass of the present invention contains SiO 2 and B 203 as essential components for forming a glass network, and contains Gd 203, Nb 205, Ti 2 as a necessary component for increasing the refractive index and includes as a lowering transition temperature. The indispensable components of ZnO and Li20, wherein the alkaline earth metal oxide BaO, CaO, SrO are introduced in at least two or more kinds, and the introduction amount of Sn02 and K20 is limited.

In the high-refraction, high-dispersion glass of the present invention, SiO 2 is a necessary component as a component for forming a glass network, and is a component which is most effective for increasing the viscosity of the glass liquid and enhancing the resistance to devitrification. When the amount of introduction of SiO 2 is too low, the viscosity of the glass is reduced, the devitrification is deteriorated, and the glass is colored and the glass is hardly formed, and it is difficult to form a stable, high-quality glass. If the amount of introduction is too large, the solubility of the melt deteriorates and the optical constant decreases, and it is difficult to obtain an ideal refractive index and dispersion value. Therefore, it is preferably 10 to 25%, more preferably 11 to 24%, still more preferably 12 to 22%.

B203 is the most effective component for forming glass network components and is effective for reducing solubility and lowering the melting temperature. However, in the glass of the present invention, if the amount introduced is too large, the glass coloring will It will be emphasized, and therefore, the amount of the bow I is controlled to be 11% or less, preferably 10 or less, further preferably 8% or less.

One object of the present invention is to achieve high transmittance, and when the ratio of the content of SiO 2 /B 203, that is, the content of SiO 2 / B 203 is less than 2.0, the tendency of coloring of the glass is increased, and the resistance to devitrification is lowered and the stability is changed. difference. When the weight ratio of SiO 2 / B 203 is more than 2.0 or more, the coloring of the glass is gradually weakened, the transmittance is improved, and the glass stability is also improved. Therefore, it is necessary to increase the specific gravity of the SiO 2 by an appropriate amount, and it is preferable to make the SiO 2 /B 203 / weight ratio more than 2.0 to reduce the coloration of the glass and increase the transmittance. The above ratio of SiO 2 /B 203 / is preferably at least 2.0, more preferably at least 2.5 or more.

Gd203 is the same as La203 and has a component that achieves a high refractive index. However, when the amount of introduction is too large, it is difficult to achieve the required optical constant, and the glass stability is also lowered, but when the amount of introduction is too low, the devitrification resistance of the glass is also deteriorated. Therefore, in the present invention, the amount of introduction of Gd203 is controlled to be 5-15%, preferably 5 to 13%, more preferably 6 to 12%.

In the present invention, Nb205 is an essential component for achieving high refractive index and high dispersion, and can significantly improve the devitrification resistance of the glass and improve the stability of the glass, but when the amount thereof is less than 15%, It is difficult to obtain the above effects. If it is greater than 30%, the opposite is true, the anti-devitrification and stability of the glass will decrease, and the Abbe number will also exceed the set range. Therefore, the preferred range is from 15 to 30%, and more preferably from 19 to 32%. Change here to 17~28%

In the present invention, Ti02 is a necessary component for increasing the refractive index and the dispersion value. However, if the amount of introduction is less than 5%, it is difficult to achieve the set optical constant of high refraction and high dispersion, and the glass density will also increase. However, if the amount of introduction exceeds 22%, the absorption of the short-wavelength side and long-wavelength bands will be intensified, and the glass will be colored and the glass resistance to devitrification and solubility will be deteriorated. Therefore, the amount of introduction is controlled to 5 to 22%, preferably 6 to 21%, more preferably 8 to 19%, and most preferably 10 to 19%.

In order to satisfy the above-mentioned optical characteristics and achieve high permeation, it is preferable that the amount of introduction of Nb205 is larger than the amount of Ή02, more preferably the weight ratio of Nb205/Ti02 is more than 1.0, and still more preferably, the weight ratio of Nb205/Ti02 is more than 1.2.

In the present invention, BaO not only has the effect of improving the short-wavelength transmission of the short-wavelength of the visible light region, but also has the effects of improving the stability of the glass and devitrification, especially when the amount of introduction of TiO 2 is too large, the effect of BaO will be more obvious. However, when the amount of introduction of BaO exceeds 30%, not only the refractive index of the glass is lowered, but also the stability of the glass is also lowered. Therefore, the amount of BaO introduced is controlled to be 10-30%, preferably 12-28%, and further preferably 14-26%.

When the introduction amount of CaO is 3% or more, the transmittance of the short-wavelength side section can be remarkably improved and the glass density can be alleviated, and a good anti-devitrification state can be maintained and the glass liquid can be accelerated. However, when the amount of introduction exceeds 15%, the excessive introduction thereof lowers the refractive index of the glass, particularly the significant decrease in the dispersion value, and makes the glass viscosity smaller, devitrification resistance, and stability lower. Therefore, the amount thereof to be introduced is 3 to 15%, preferably 4 to 13%, more preferably 4 to 11%, still more preferably 5 to 9%. Ta205 is an important component for increasing the refractive index, increasing the dispersion value and bringing the optical constant to a set range, and significantly improving the stability of the glass. When Ta205 is less than 0.5%, the effect is not obvious, when it exceeds 5%, it is not only Less than the set dispersion value will increase the glass density, and the glass cost will also be greatly increased, which is not conducive to low-cost operation. Therefore, the amount of introduction is controlled to be 1 to 5%, preferably 1 to 4%, more preferably 1 to 3%.

In the present invention, ZnO is a component which has a remarkable effect of lowering the transformation temperature and improving the stability of the glass, and particularly has a function of stability when the amount of introduction of Nb205 is excessive. However, if the content is too large, it is difficult to achieve the desired refractive index and dispersion value, and the coloration of the glass will also be aggravated. Therefore, in order to achieve the set optical constant and to reduce the coloration of the glass, the amount of introduction is controlled by 1 to 5%, preferably 1 to 4%, more preferably 1 to 3%.

Compared with other alkali metal oxides, Li20 has the effect of increasing the refractive index and maximally decreasing the glass transition temperature, and also has the effects of improving glass solubility, increasing glass forming viscosity, and reducing glass coloration, and is a necessity of the present invention. Component. However, when an excessive amount is introduced, the glass resistance to devitrification is lowered, and the optical constant is also greatly lowered. When it is preferable to improve the glass solubility and the transition temperature, the amount of introduction is controlled to be 1 to 6%, preferably 1 to 5%, further preferably 1 to 4%.

A low transition temperature is obtained by adjusting the ratio of the ZnO/Li20 content so as to achieve a desired specific optical constant while at the same time achieving a significant balance between the transition temperature (Tg) and the stability of the glass. (Tg) and achieve good solubility of the glass. Preferably, the amount of ZnO introduced is less than the amount of introduction of Li20, more preferably the weight ratio of ZnO/Li20 is less than 1, and further preferably the weight ratio of ZnO/Li20 is less than 0.5.

ZrO 2 has an effect of increasing the refractive index and the glass resistance to devitrification without coloring the glass. However, when the amount of introduction is more than 5%, not only the solubility will be deteriorated, but also the refractive index and the dispersion value will be lowered. Therefore, the amount thereof to be introduced is preferably 0.5 to 5%, more preferably 1 to 4%, still more preferably 1 to 3%.

W03 has a remarkable effect on increasing the refractive index and dispersion value and improving the devitrification. However, when the amount of introduction exceeds 5%, light absorption on the short-wavelength side of the visible light region is increased, and the tendency of glass coloring is intensified. Thus, as an optional component, the amount thereof is from 0 to 5%, preferably from 0 to 4%, more preferably from 0 to 3% or less.

Like Li20, K20, which is a homologous group, helps to improve the melting performance, lower the melting temperature, and reduce the coloration of the glass which is aggravated by the introduction of excessive Ti02. However, if the amount of introduction exceeds 5%, the glass resistance to devitrification will be drastically deteriorated, and the refractive index and dispersion value will also be significantly lowered. Therefore, the amount thereof is 0 to 5%, preferably 0 to 4%, more preferably 0 to 3% or less.

As an optional component thereof, SrO has an effect of improving glass fusibility and an increase in short-wavelength side passage permeability. However, when the amount of introduction is too high, the refractive index and stability of the glass are lowered, so that the amount of introduction is adjusted to 0 to 5%, preferably 0 to 4%, more preferably 0 to 3%.

Sn02 has the same effect as Zr02, but when the amount of introduction is too large, the glass fusibility will be deteriorated, the refractive index and dispersion value will also decrease, and the glass transition temperature (Tg) will rise rapidly. Cause However, the amount of introduction is preferably 0 to 2%, more preferably 0 to 1.5% or less.

Sb203 is any additive used as a fining agent, such as excessive addition and introduction, which will darken the glass, reduce the transmittance, and also deteriorate the stability of the melt and the intrinsic quality of the glass. Therefore, the amount thereof is 0 to 1%, preferably 0 to 0.6%, more preferably 0 to 0.5% or less.

As described above, in order to improve not only the stability of production, but also the transmittance of the visible light region and the reduction of the glass density while realizing the specific optical constant and low transition temperature of the present invention, SiO 2 , B 203 , G 203 , and Nb 205 are preferable. , Ti02, Ta205, BaO, CaO, ZnO, Li20, Zr02, the component introduction amount is 95% or more, and the introduction amount of components such as W03, K20, SrO, Sn02 is 5% or less, and the total amount thereof The amount introduced is 100%.

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

The optical glass of the present invention has a refractive index (nd) of more than 1.88 and an Abbe number (vd) of less than 26. When the refractive index is gradually increased, the glass resistance to devitrification is lowered. However, the optical glass of the present invention can achieve excellent devitrification resistance and high transmittance, so that the refractive index (nd) can be further improved. Accordingly, the refractive index (nd) of the present invention is preferably at least 1.88, more preferably 1.90 or 1.91. In order to achieve manufacturing stability, it is desirable to limit the refractive index (nd) to 1.92 or less, and more desirably to 1.91 or less.

Further, in order to achieve the stability of production and to reduce the coloration of the glass, the Abbe number (vd) of the optical glass of the present invention is preferably 24 to 26.

The optical glass of the present invention is mainly used for secondary molding by softening pressing or repeated pressing by secondary heating, and is processed into an optical lens. Or it can be softened by secondary heating and drawn into a preformed bar material suitable for precision molding. Therefore, its low transition temperature and good resistance to devitrification are the key to manufacturing both.

According to the optical glass of the present invention, the internal permeation (wavelength into 70) is controlled to below 412 nm, preferably 410 nm or less, by composition optimization and process modification. The internal transmission (wavelength λ 5 ) is controlled to be 371 nm or less, preferably 370 nm or less. Since the optical glass of the present invention has a transmission of 70% or more in the wavelength range of λ 70 and a shorter wavelength direction of λ 5 , it is suitable as various high-pixel, high-resolution optical lenses.

When the glass density is excessively lowered, the stability of the production thereof is lowered, and the coloring tendency of the glass is also increased. Therefore, the glass density of the optical glass of the present invention is controlled to be in the range of more than 4.0 but less than 4.2.

The stability of the manufacturing is premised on having a low liquidus temperature, and when the devitrification resistance of the glass is lowered, the liquidus temperature thereof is sharply increased, and the glass stability is deteriorated. Thus, the liquidus temperature of the optical glass of the present invention is controlled to be lower than 1080 ° C, more preferably 1070 ° C or lower.

The optical glass of the present invention has a high refractive index (nd) of 1.88 or more and an Abbe number (vd) of 26 or less, and is a high refractive index optical glass having a low transition temperature suitable for precision molding, and It has good stability when directly forming a blank from a glass liquid, during the secondary hot pressing process, Repeated secondary hot pressing does not appear devitrification, and can be used to make prefabricated bars for precision molding.

The optical glass of the present invention has a glass transmittance of not higher than 412, a density of 4.17 or less, and a transition temperature (Tg) of 610 ° C or lower, in addition to the existing high refractive index and high dispersion optical glass. It also has good resistance to devitrification and low cost, enabling low-cost operation and mass production in a stable state.

It is apparent that various other modifications, substitutions and changes can be made in the form of the above-described embodiments of the present invention without departing from the spirit and scope of the invention.

The above content of the present invention will be further described in detail below by way of specific embodiments in the form of embodiments. However, the scope of the above-mentioned subject matter of the present invention should not be construed as being limited to the following examples. Any technique implemented based on the above description of the present invention is within the scope of the present invention.

detailed description

Example 1 Properties of the optical glass of the present invention

Tables 1 and 2 show the compositions of the optical glass of the present invention, the composition of N2l to N2OO, and the composition of Comparative Examples N2a to N2d of the same type of glass as the glass of the present invention. The optical glass obtained by annealing at -4.0/h annealing rate and cooling was measured in the following examples, and the refractive index (nd), Abbe number (vd), internal transmission (human 70), and (human 5) were measured in each of the examples and the comparative examples. The results of measurement of density (Ρ), transition temperature (Tg), and liquidus temperature (LT) are shown in Tables 1 and 2.

The raw materials of each component are weighed and mixed according to the composition ratio of each of the examples and the comparative examples to prepare a batch material, which is added to a specific platinum container, and melted, stirred, and clarified at a temperature of 1150 ° C to 1300 ° C. After stirring again, it is poured or leaked into the mold to form, and it can be annealed.

The properties of the above glass were measured as follows:

(1) Refractive index (nd) and Abbe's number (vd) Measurements Glass samples were obtained at an annealing rate of -4.0/h.

(2) The internal transmission of a 5 mm, 10 mm sample having two parallel polished faces was measured, that is, the wavelength (nm) at 70% was determined to be λ 70, and the wavelength (nm) at 5% was λ 5 . (The internal transmission does not include the transmittance when the surface of the sample is reflected.)

(3) Determine the density (Ρ) Measurements are made using the Archimedes method.

(4) The glass transition temperature (Tg) is measured by a thermal analyzer at a heating rate of 4.0 ° C / min.

(5) Liquidus temperature (L _T ): 500 g of glass sample was placed in a small platinum container, set in a furnace at 10 ° C intervals, kept at different temperatures for 2 h, and the sample was cooled and observed by a microscope. The inside of the lump glass sample was crystallized to determine the liquidus temperature.

Table 1 Melting Example (% by weight)

Table 2 Melting Example (% by weight)

Component Example Comparative Example

8 9 10 a b c d

Si02 17.3 21.5 17.9 22.0 27.14 6.3 6.6

B203 2.8 3.4 3.3 18.5 13.2

Nb205 22.2 20.7 23.0 48.0 46.63 20.5 5.4

Gd203 9.6 9.9 6.1 0.2

La203 14.1 33.2

Ti02 15.5 11.3 10.5 5.0 11.56 11.2 13.4

BaO 17.8 13.9 26.0 1.0 17.8 16.8

CaO 6.3 8.9 4.0 6.0 2.2

As shown in Tables 1 and 2, the optical glass N2 l~N ₂ 10 of the embodiment of the present invention has a specific range of optical constants, that is, the refractive index (nd) is 1.8812-1.9261, and the Abbe number (vd) 24.13-25.92, glass. The inner permeation upper limit is less than 412, the lower limit is less than 371, the specific gravity is lower than 4.2, and the transition temperature (Tg) is lower than 610 °C. Due to the low liquidus temperature, not only the good reproducibility of the secondary hot pressing can be achieved, but also the appropriate Preform for precision molding. And can achieve stable mass production.

On the contrary, as shown in the comparative example in Table 2, although the refractive index (nd) reached 1.90 in a case, the Abbe number (vd) exceeded 26, which was not an optical constant of the present invention. At the same time, the glass density is also greater than the density of the range, the liquidus temperature is high, and the expensive Ge0 ₂ component is also contained, which is not suitable for stable, low-cost mass production.

In the case of b, the Abbe number (vd) is less than 26, but the refractive index (nd) is less than 1.88, which is not an optical constant of the present invention. Therefore, the design requirements of the optical system of the SLR camera cannot be satisfied. Not only that, the liquidus temperature of the glass is high, and it is difficult to achieve stable mass production.

The optical constants of the c example are lower than the specific optical constants of the present invention regardless of the refractive index (nd) or the Abbe number (vd), and the glass transition temperature is high and the devitrification resistance is poor, which is not suitable for the precision molding preform. The production of materials and the realization of secondary hot pressing.

In the case of d, the refractive index (nd) also reached 1.90, but the Abbe number (vd) was greater than 30, and the specific optical constant of the present invention was not obtained. At the same time, due to the inclusion of the Bi ₂ 0 ₃ component, the glass has poor transmission and the glass density is large. In summary, the optical glass of the present invention has a high refractive index (nd) of 1.88 or more, an Abbe number (vd) of 26 or less, and a high refractive index optical glass having a low transition temperature suitable for precision molding. Moreover, when it is directly formed into a raw material from a glass liquid, it has good stability, and in the secondary hot pressing process, the repeated secondary hot pressing does not appear to be devitrified, and can be made into a pre-formed bar for precision pressing. Industrial applicability

The invention provides a high refractive, high dispersion optical glass with high transmission and low glass density, and also has good anti-devitrification characteristics and can be suitable for repeated pressing in the secondary hot pressing process. On the basis of not introducing expensive components, it achieves good resistance to devitrification, achieves stable, low-cost quantitative production and achieves good secondary hot pressing. At the same time, the lens is lighter at a lower density, reducing the weight of the whole machine. With a low transition temperature (Tg), it is suitable for the drawing of precision molded preforms. Suitable for a wide range of applications in industry.

Claims

claims

1. An optical glass containing: Si0 ₂ , B ₂ 0 ₃ , Gd ₂ 0 ₃ , Nb ₂ 0 ₅ , Ti0 ₂ , BaO, CaO, Ta ₂ 0 ₅ , ZnO, Li ₂ 0, 21"0 ₂ as A required component, this optical glass has an optical constant with a refractive index nd greater than 1.88 and an Abbe number vd of 23 to 26.

2. The optical glass according to claim 1, characterized in that: when expressed as 1%), the optical glass contains the following components:

10~25% Si0 ₂

The condition for 1~11% B ₂ 0 ₃ is: (Si02/B203) weight ratio is greater than 2

5~15% Gd ₂ 0 ₃

15~30% Nb ₂ 0 ₅

The conditions for 5~22% Ti0 ₂ are: (Nb205/Ti02) weight ratio is greater than 1

10~30% BaO

3~15% CaO

Greater than 0 but less than 5% of Ta ₂ 0 ₅

Greater than 0 but less than 5% ZnO

Greater than 0 but less than 6% Li ₂ 0 The conditions are: (ZnO+Li20) The weight ratio is less than 1 Less than 5% Zr0 ₂

0~5% of W0 ₃

0~5% K ₂ 0

0~5% SrO

0~2% Sn0 ₂

0 or more but less than 1% of Sb ₂ 0 ₃ .

3. The optical glass according to claims 1 and 2, characterized in that: when expressed as 1%), the optical glass contains the following components:

12~22% Si0 ₂

The condition for 2~8% B ₂ 0 ₃ is: (Si02/B203) weight ratio is greater than 2

6~12% Gd ₂ 0 ₃

16~28% Nb ₂ 0 ₅

The conditions for 7~20% Ti0 ₂ are: (Nb205/Ti02) weight ratio is greater than 1

12~28% BaO

4~11% CaO

Greater than 0 but less than 4% of Ta ₂ 0 ₅

Greater than 0 but less than 4% ZnO

Greater than 0 but less than 5% Li ₂ 0 The condition is: (ZnO/Li20) weight ratio is less than 1 Less than 4% Zr0 ₂

0~4% of W0 ₃

0~3% K ₂ 0

0~3% SrO

0~1% Sn0 ₂

0 or more but less than 0.5% Sb ₂ 0 _{3 o}

4. The optical glass according to claim 2, characterized in that: the optical glass contains the following components:

Si0 ₂ 14.5-21.5%;

B ₂ 0 ₃ 2.7-6.9%;

Gd ₂ 0 ₃ 6.1-10.9%;

Nb ₂ 0 ₅ 19.2-26.7%;

Ti0 ₂ 11.3-18.3;

BaO 12.5-26.0%;

CaO 3.0-9.2%;

Ta ₂ 0 ₅ 0.6-3.8%;

ZnO 0.6-2.8%;

Li ₂ 0 1.6-3.5%;

Zr0 ₂ 0.7-3.2%;

W03 0-3.1%;

K ₂ 0 0-1.0%;

SrO 0-1.0%;

Sn0 ₂ 0-0.4%;

Sb ₂ 0 ₃ 0.1%.

5. The optical glass according to any one of claims 1 to 4, characterized in that: the internal transmission of the glass is less than 412.

6. The optical glass according to any one of claims 1 to 5, characterized in that: the density of the glass is not higher than 4.2g/cm ³ .

7. The optical glass according to any one of claims 1 to 6, characterized in that: the glass transition temperature Tg is not higher than 610°C, and the liquidus temperature _LT is not higher than 1080°C.

8. The manufacturing method of optical glass according to any one of claims 1 to 7, characterized in that it includes the following steps: including flowing the uniform glass liquid into a specific mold through a leakage device, cooling and solidifying to a constant thickness and width, to produce a blank formed of the optical glass according to any one of claims 1 or 3.

9. A method for manufacturing secondary hot-pressed parts, which is to cut and process the blank material of claim 8 into The required specifications and weight are then heated and softened, and then pressed and formed in the softened state to obtain pressed blanks of different shapes.

10. A method for manufacturing precision pressed preforms, characterized by: including the following steps: heating and softening the optical glass according to any one of claims 1 or 8, and drawing it into a preform in a softened state. material.