CN105645766B

CN105645766B - Optical glass and optical element

Info

Publication number: CN105645766B
Application number: CN201610127491.5A
Authority: CN
Inventors: 匡波
Original assignee: Chengdu Guangming Optoelectronics Co Ltd
Current assignee: Chengdu Guangming Optoelectronics Co Ltd
Priority date: 2016-03-07
Filing date: 2016-03-07
Publication date: 2019-02-26
Anticipated expiration: 2036-03-07
Also published as: CN105645766A

Abstract

The present invention provide a kind of refractive index be 1.76-1.80, the high-refraction low-dispersion optical glass for mold that Abbe number is 47-51, be free of Ta in the glass ingredient₂O₅, and the glass has excellent transmitance.Optical glass, weight percent composition includes: B₂O₃: 25-40%；La₂O₃: 20-40%；Gd₂O₃: 12-25%；ZrO₂: 6.5-15%；ZnO: greater than 10% but be less than or equal to 20%；SiO₂: 0-3%；Nb₂O₅: 0-5%；Y₂O₃: 0-10%；Without containing Ta₂O₅.The present invention passes through reasonable component proportion, make this glass while realizing desired optical constant, it is easily achieved conducive to accurate die pressing and with the Spectralite with high refractivity and low dispersion of excellent transmitance, and the gas preform and optical element that are formed by the optical glass.

Description

Optical glass and optical element

Technical field

The present invention relates to a kind of optical glass with high-refractivity and low-dispersion characteristic, and are formed by the optical glass Gas preform and optical element.

Background technique

For optical glass, refractive index, Abbe number, transmitance are its core photosensitiveness features.Refractive index and Abbe number Determine the basic function of glass, it is low that the optical glass that refractive index 1.76-1.80, Abbe number are 47-51 belongs to high refractive index Dispersion optical glass, application of this kind of high-performance glass in optical system can shorten the length of camera lens, improve image quality.

For the requirement for meeting optical glass precise compression molding, requirement is proposed to the transition temperature Tg of optical glass.? Under the premise of realizing identical optical property, how to realize the low Tg temperature of glass and guarantee that transmitance is excellent simultaneously, be current The target of research and development.CN102050571A disclose a kind of refractive index be 1.77-1.83, the high refractive index light that Abbe number is 44-51 Glass is learned, but its Tg temperature is higher, is not suitable for low cost accurate die pressing.In addition, containing a large amount of Ta in the glass ingredient₂O₅, and Ta₂O₅Belong to expensive metal oxide, it is a large amount of to use the cost of material for improving Spectralite with high refractivity and low dispersion, Reduce the economy of product.Further more, it also contains SnO₂, SnO₂It is not only difficult to melt, easily forms impurity in glass, influence Glass inherent quality and processing performance can also improve the degree of staining of glass, reduce transmitance.Camera shooting projects class optical system Optical element is more demanding to optical glass transmitance, if the transmission light transmitted by lens amount that high-refraction low-dispersion optical glass for mold is formed is not Foot, will lead to the transmitted light flux sharp fall of optical system or die-offs, influence image quality.

Summary of the invention

Technical problem to be solved by the invention is to provide the height that a kind of refractive index is 1.76-1.80, Abbe number is 47-51 Refraction and low dispersion optical glass is free of Ta in the glass ingredient₂O₅, and the glass has excellent transmitance.

The present invention also provides a kind of gas preform and optical element formed by above-mentioned optical glass.

The technical proposal for solving the technical problem of the invention is: optical glass, and weight percent composition includes: B₂O₃: 25-40%；La₂O₃: 20-40%；Gd₂O₃: 12-25%；ZrO₂: 6.5-15%；ZnO: greater than 10% but it is less than or equal to 20%；SiO₂: 0-3%；Nb₂O₅: 0-5%；Y₂O₃: 0-10%；Without containing Ta₂O₅。

Further, also contain: Al₂O₃: 0-10% and/or Li₂O:0-10% and/or Na₂O:0-10% and/or K₂O:0- 10% and/or GeO₂: 0-10% and/or Bi₂O₃: 0-10% and/or CeO₂: 0-1% and/or Sb₂O₃: 0-1% and/or RO:0- 10%, wherein one of RO MgO, CaO, SrO or BaO or a variety of.

Further, wherein Al₂O₃: 0-5% and/or Li₂O:0-5% and/or Na₂O:0-5% and/or K₂O:0-5% And/or GeO₂: 0-5% and/or Bi₂O₃: 0-5% and/or CeO₂: 0-0.5% and/or Sb₂O₃: 0-0.5% and/or RO:0- 5%.

Further, wherein Al₂O₃: 0-1% and/or Li₂O:0-1% and/or Na₂O:0-1% and/or K₂O:0-1% And/or GeO₂: 0-1% and/or Bi₂O₃: 0-1%.

Further, wherein B₂O₃: 28.5-35% and/or La₂O₃: 25-35% and/or Gd₂O₃: 14-22% and/or ZrO₂: 6.5-10% and/or ZnO:11-16% and/or SiO₂: 0-2% and/or Nb₂O₅: 0-1% and/or Y₂O₃: 0-5%.

Further, wherein B₂O₃: 29-32% and/or La₂O₃: 27-32% and/or Gd₂O₃: 15-20% and/or ZrO₂: 6.5-8.5% and/or ZnO:11-14.5% and/or SiO₂: 0-0.5% and/or Nb₂O₅: 0-0.5% and/or Y₂O₃: 0- 1%.

Further, wherein ZnO/ (B₂O₃+SiO₂) it is 0.25-0.65；And/or (ZrO₂+Y₂O₃)/(Nb₂O₅+Gd₂O₃) For 0.30-1.50；And/or La₂O₃/(La₂O₃+Gd₂O₃+Y₂O₃) it is 0.38-0.75.

Further, wherein La₂O₃/(La₂O₃+Gd₂O₃+Y₂O₃) it is 0.45-0.70；And/or ZnO/ (B₂O₃+SiO₂) be 0.30-0.55；And/or (ZrO₂+Y₂O₃)/(Nb₂O₅+Gd₂O₃) it is 0.48-1.10.

Further, wherein La₂O₃/(La₂O₃+Gd₂O₃+Y₂O₃) it is 0.55-0.65；And/or ZnO/ (B₂O₃+SiO₂) be 0.30-0.50；And/or (ZrO₂+Y₂O₃)/(Nb₂O₅+Gd₂O₃) it is 0.50-1.0.

Further, the density of glass is in 5.00g/cm³Below；The transition temperature Tg of glass is at 625 DEG C or less.

Gas preform is made of above-mentioned optical glass.

Optical element is made of above-mentioned optical glass.

The beneficial effects of the present invention are: not introducing SnO₂Ingredient keeps glass transmitance excellent；Without Ta₂O₅, optimize life Produce cost；By reasonable component proportion, make this glass while realizing desired optical constant, it is easy to accomplish to be conducive to precision Molding and the Spectralite with high refractivity and low dispersion with excellent transmitance, and it is pre- by the glass that the optical glass is formed Product and optical element.

Specific embodiment

I, optical glass

The composition of optical glass of the invention is described in detail below, the content of each glass ingredient, total content do not have such as There is special instruction, be then all indicated using weight %, the ratio between the content of glass ingredient and total content are indicated with weight ratio.Separately It outside, in the following description, also include the specified value when mentioning specified value or less or specified value or more.

B₂O₃It is that glass network forms component, has the function of improving glass fusible and reduce glass transition temperature.For Reach said effect, present invention introduces 25% or more or more B₂O₃, but when its introduction volume is more than 40%, then glass is steady It is qualitative to decline, and refractive index declines, and is unable to get high refractive index of the invention.Therefore, B of the invention₂O₃Content be 25-40%, preferred scope 28.5-35%, preferred range are 29-32%.

SiO₂It is also glass former, with B₂O₃The loose chain multi-layered network constituted is different, SiO₂Shape in glass At be oxygen-octahedron three-dimensional network, it is very fine and close firm.Such network is added in glass, to loose boron oxygen triangle Body [BO₃] network reinforced, so that it is become fine and close, to promote the high temperature viscosity of glass.At the same time, oxygen-octahedron three The addition of network is tieed up, La is isolated in glass network₂O₃、Nb₂O₅The ability enhancing of equal crystallizations cation and anion, increases crystallization Threshold value enables the devitrification resistance of glass to be promoted.If but SiO₂The unconfined increasing of content, it is tired on the one hand to will cause dissolution Difficulty will definitely increase La on the other hand in order to maintain higher refractive index and low dispersion₂O₃、Gd₂O₃Equal rare earth oxides contain Amount, SiO₂To La₂O₃Solubility it is lower, will cause glass devitrification resistance can sharply decline.Therefore, in the present invention, content It is limited to 0-3%, preferably 0-2%, more preferably 0-0.5%.

La₂O₃It is the necessary component of optical characteristics needed for obtaining the present invention.Work as La₂O₃Content less than 20% when, it is difficult to it is real Optical characteristics required for existing；But when its content is more than 40%, glass devitrification resistance deteriorates with melting behaviour.Therefore, originally The La of invention₂O₃Content be 20-40%, preferred scope 25-35%, preferred range be 27-32%.

Gd₂O₃It is the effective component for obtaining optical glass having high refractive index, passes through Gd in the present invention₂O₃With La₂O₃It coexists, it can be with The stability for forming glass is improved, but works as Gd₂O₃When content is lower than 12%, said effect is unobvious；If its content is more than 25% When, then glass devitrification resistance reduces, and forms the bad stability of glass.Therefore, Gd of the invention₂O₃Content be 12-25%, Preferred scope is 14-22%, and more preferable range is 15-20%.

The component of the high refractive low dispersive effect of the present invention preferably also introduces Y₂O₃, meltbility, the devitrification of glass can be improved Property, while devitrification of glass ceiling temperature can be also reduced, if but its content is more than 10%, stability, the devitrification resistance drop of glass It is low.Therefore, Y₂O₃Content range is 0-10%, preferred scope 0-5%, more preferably 0-1%.

La₂O₃、Gd₂O₃And Y₂O₃In, it is to improving glass refraction and stability, glass being maintained to act on maximum component La₂O₃.If but La is used only in optical glass of the invention₂O₃, then it is difficult to ensure sufficient stability, glass.Therefore, in this hair Bright middle La₂O₃The introduction volume of component is relatively more, and makes La₂O₃And Gd₂O₃It coexists；Or preferably make La₂O₃、Gd₂O₃And Y₂O₃ It coexists；More preferable La₂O₃/(La₂O₃+Gd₂O₃+Y₂O₃) range be 0.38-0.75, further preferred La₂O₃/(La₂O₃+Gd₂O₃+ Y₂O₃) range be 0.45-0.70, still more preferably La₂O₃/(La₂O₃+Gd₂O₃+Y₂O₃) range be 0.55-0.65, can obtain To the glass of the high-refractivity and low-dispersion with excellent stability, glass, while glass not easy coloring.

Nb₂O₅There is fabulous effect to glass refraction reduction liquidus temperature is improved, it may have improve the devitrification resistance of glass With the effect of chemical durability.If its content is more than 5%, glass dispersion is improved, and is unable to reach the optics of glass of the present invention Characteristic.Therefore, Nb₂O₅Content range be 0-5%, preferred scope 0-1%, more preferable range be 0-0.5%.

The chemical stability that glass can be improved is added in glass in ZnO in right amount, while the high temperature that can also reduce glass is viscous Degree and Tg temperature.But if ZnO additional amount is excessive, the devitrification resistance of glass can decline, while high temperature viscosity is smaller, to molding Bring difficulty.In glass system of the present invention, if design requirement is not achieved lower than 10%, Tg temperature in the content of ZnO；If it contains Amount is higher than 20%, and the devitrification resistance of glass can decline, and design requirement is not achieved in high temperature viscosity.Therefore, the content of ZnO is limited to Greater than 10% but it is less than or equal to 20%, preferably 11-16%, more preferably 11-14.5%.

For the present invention in order to obtain lower Tg temperature and stability is good, the glass that is easy to melt, inventor passes through a large number of experiments The study found that working as ZnO/ (B₂O₃+SiO₂) range be 0.25-0.65, preferably ZnO/ (B₂O₃+SiO₂) range be 0.30-0.55, into Preferred ZnO/ (the B of one step₂O₃+SiO₂) when being 0.30-0.50, the stability and Tg temperature of glass obtain range up to optimum balance The preferable product of quality.

ZrO₂Belong to high refraction oxide, the refractive index of glass can be significantly improved, while improving the chemical stability of glass； In the present invention, ZrO₂It is also improved the extremely dispersed effect of glass, the exception of glass is dispersed to be conducive to disappear in optical design Except second order spectrum, content is too low, then foregoing advantages are unobvious, but additional amount can excessively significantly improve the crystallization risk of glass. Therefore, content is limited to 6.5-15%, preferably 6.5-10%, more preferably 6.5-8.5%.

As optical glass, optical transmittance is considerable performance indicator, as (ZrO₂+Y₂O₃)/(Nb₂O₅+ Gd₂O₃) scope control in 0.30-1.50, be preferably controlled in 0.48-1.10, more preferably control in 0.50-1.00, further When being preferably controlled in 0.50-0.70, it can be achieved that while currently preferred refractive index and Abbe number range, also can effectively it inhibit Glass coloration, and improve the thermal stability and devitrification resistance property of glass.

It is a small amount of to introduce Al₂O₃It can improve and form the stability and chemical stability of glass, but when its content is more than 10%, it is aobvious Show the tendency that glass melting is deteriorated, devitrification resistance reduces, therefore Al of the present invention₂O₃Content be 0-10%, preferably 0-5%, More preferably 0-1% is not introduced further preferably.

Li₂O is added in glass ingredient, and the Tg temperature of glass can be effectively reduced.But low softening point optical glass is logical It is often used platinum or platinum alloy vessel melting, Li during high melt, in glass ingredient⁺Easily corrode platinum or platinum alloy device Ware causes to generate more platiniferous foreign matter in finished glass, leads to the quality decline of glass.On the other hand, such glass is used for When during precise compression molding, it is easy to produce the risk of glass elements surface blur, reason is to be typically coated with carbon containing member in mold The release agent of element, the Li in glass ingredient be easy and release agent in carbon react, generated on glass original part surface thick Rough opaque film layer.Therefore, Li₂O content is limited to 0-10%, preferably 0-5%, more preferably 0-1%.

Na₂O and K₂O is to be easy to cause in devitrification temperature to the reduction effective any ingredient of Tg if its ingredient is excessive It rises and is difficult to vitrifying, therefore its content is limited to 0-10%, more preferably 0-5%, further preferably 0-1% respectively.

RO (one of RO MgO, CaO, SrO or BaO or a variety of) can improve the meltbility of glass, adjust glass light Property, but when its content is more than 10%, the devitrification resistance of glass reduces, therefore the preferred RO content of the present invention is 0-10%, more excellent Selecting range is 0-5%, is not introduced further preferably.

Bi₂O₃Glass refraction, but the excessive transmissivity containing the short wavelength side for then showing visible light region sometimes can be improved It reduces, glass has the tendency that colouring, therefore the preferred Bi of the present invention₂O₃Content is 0-10%, more preferably 0-5%, further Preferably 0-1% is not introduced still more preferably.

GeO₂It can also be effectively improved the stability and devitrification resistance to form glass, but due to GeO₂Component is very expensive, Therefore preferably GeO₂Content is respectively 0-10%, more preferably 0-5%, further preferably 0-1%, is not drawn still more preferably Enter.

By adding Sb on a small quantity₂O₃、CeO₂The clarifying effect of glass can be improved in component, but works as Sb₂O₃Content is more than 1% When, glass has the tendency that devitrification resistance property reduction, the risk that dispersion increases, simultaneously because its strong oxidation promotes shaping mould The deterioration of tool, therefore the preferred Sb of the present invention₂O₃Additive amount be 0-1%, more preferably 0-0.5% is further preferably added without. CeO₂Effect and additive amount ratio and Sb₂O₃Unanimously, content is preferably 0-1%, more preferably 0-0.5%, further preferably It does not add.

In the following, being illustrated to the characteristic of optical glass of the invention.

[optical constant of optical glass]

Optical glass of the invention is high-refractivity and low-dispersion glass, lens made of high-refractivity and low-dispersion glass mostly with Lens made of high refractive index high-dispersion glass are combined, and are used for chromatic aberration correction.Optical glass of the invention is suitable for it from imparting From the point of view of the optical characteristics of purposes, the range of glass refraction nd is 1.76-1.80, and preferred range is 1.76-1.79, Preferred range is 1.76-1.78, further preferred range 1.77-1.78；The Abbe number ν of glass of the present invention_dModel It encloses for 47-51, preferred scope 48-50, more preferable range is 49-50.

[coloring of optical glass]

The shortwave transmitted spectrum characteristic degree of staining (λ of glass of the present invention₈₀/λ₅) indicate.λ₈₀Refer to that glass transmittance reaches Corresponding wavelength, λ when 80%₅Refer to that glass transmittance reaches corresponding wavelength when 5%.Wherein, λ₈₀Measurement be using having The glass with a thickness of 10 ± 0.1mm of two parallel to each other and optical polish opposite planes, measures from 280nm to 700nm Spectral transmission in wavelength domain and the wavelength for showing transmissivity 80%.So-called spectral transmission or transmissivity are to glass Above-mentioned surface vertically incident intensity I_inLight, project intensity I through glass and from plane_outLight in the case where lead to Cross I_out/I_inThe amount of expression, and also contain the transmissivity of the surface reflection loss on the above-mentioned surface of glass.The folding of glass It is higher to penetrate rate, surface reflection loss is bigger.Therefore, in glass of high refractive index, λ₈₀The small coloring for meaning glass itself of value Seldom.

Optical glass λ of the invention₈₀Less than or equal to 400nm, preferably λ₈₀Range be less than or equal to 395nm, it is more excellent Select λ₈₀Range be less than or equal to 390nm, further preferred λ₈₀Range be less than or equal to 385nm, it is further excellent The λ of choosing₈₀Range be less than or equal to 380nm.λ₅Less than or equal to 300nm, preferably λ₅Range be less than or equal to 290nm, more preferable λ₅Range be less than or equal to 285nm, further preferred λ₅Range be less than or equal to 280nm.

[density of optical glass]

The density of optical glass be temperature be 20 DEG C when unit volume quality, unit is with g/cm³It indicates.

The density of glass of the present invention is in 5.00g/cm³Hereinafter, preferably 4.80g/cm³Hereinafter, more preferably 4.70g/cm³ Hereinafter, further preferably 4.60g/cm³Below.

[transition temperature of optical glass]

Optical glass gradually can become mouldable state by solid-state in a certain temperature range.Transition temperature refers to glass specimen from room Temperature is warming up to temperature of hanging down of speeding, temperature corresponding to the intersection point that low-temperature region and high-temperature area straight line portion extended line intersect.

The transition temperature Tg of glass of the present invention at 625 DEG C hereinafter, it is preferred that 620 DEG C hereinafter, more preferable 615 DEG C hereinafter, into one Preferably 610 DEG C or less of step.

II, optical precast product and optical element

In the following, optical precast product and optical element that description is of the invention.

Optical precast product and optical element of the invention is formed by the optical glass of aforementioned present invention.Optics of the invention Prefabricated component has high-refractivity and low-dispersion characteristic；Optical element of the invention has high-refractivity and low-dispersion characteristic, can be with low Cost provides the optical elements such as the costly various lens of optics, prism.

As the example of lens, can enumerate lens face be spherical surface or aspherical recessed meniscus shaped lens, male bend moon-shaped lens, The various lens such as biconvex lens, biconcave lens, plano-convex lens, plano-concave lens.

This lens with lens combination made of high refractive index high-dispersion glass, recoverable color difference is suitable as color The lens of poor correction.In addition, being also effective lens for the densification of optics system.

In addition, for prism, since refractive index height passes through bending through combination in camera optical system Compact, wide-angle optics system can be realized towards required direction in optical path.

[optical glass embodiment]

The present invention is explained using following examples, but the present invention should not be limited to these embodiments.

The melting and forming method for producing optical glass can be using well known to a person skilled in the art technologies.By glass original Expect the proportion weighing of (carbonate, nitrate, sulfate, hydroxide, oxide, boric acid etc.) according to glass oxide with merging After mixing, put into smelting apparatus in (such as platinum crucible), then taken at 1150~1400 DEG C it is appropriate stirring, clarification, After homogenizing, be cooled to 1300 DEG C hereinafter, casting or leakage note in molding die, the post-processings such as last annealed, processing, or It is formed by precise compression molding technology direct pressing.

The characteristic of each glass of the invention is measured by method as shown below, and measurement result is indicated in 1~table of table 9 In.

(1) refractive index nd and Abbe number ν d

Refractive index and abbe number are tested according to method as defined in GB/T7962.1-2010.

(2) glass coloration degree (λ₈₀、λ₅)

Use the glass sample with a thickness of 10 ± 0.1mm with two optical polish planes relative to each other, measurement point Light transmission is calculated according to its result.

(3) glass transformation temperature (Tg)

It is measured by method as defined in GB/T7962.16-2010.

(4) specific gravity (ρ)

It is measured by method as defined in GB/T7962.20-2010.

Table 1

Table 2

Table 3

Table 4

Table 5

Table 6

Table 7

Table 8

Table 9

[optical precast product embodiment]

The obtained optical glass of embodiment 1 in table 1 is cut into predefined size, then equably coated release on the surface Then agent is heated, softens, is press-formed, make recessed meniscus shaped lens, male bend moon-shaped lens, biconvex lens, concave-concave The prefabricated component of the various lens such as lens, plano-convex lens, plano-concave lens, prism.

[optical element embodiment]

By obtained these prefabricated components annealing of above-mentioned optical precast product embodiment, the same of the deformation of inside glass is being reduced When be finely adjusted so that the optical characteristics such as refractive index reach desirable value.

Then, each prefabricated component is ground, ground, make recessed meniscus shaped lens, male bend moon-shaped lens, biconvex lens, The various lens such as biconcave lens, plano-convex lens, plano-concave lens, prism.Antireflection can be also coated on the surface of gained optical element Film.

The present invention is the optical glass of inexpensive and excellent transmitance high refractive low dispersive, refractive index 1.76- The optical element that 1.80, Abbe number 47-51 and the glass are formed, can satisfy the needs of Modern New photovoltaic.

Claims

1. optical glass, which is characterized in that its weight percent composition includes: B₂O₃: 25-40%；La₂O₃: 20-40%； Gd₂O₃: 12-25%；ZrO₂: 6.5-15%；ZnO: greater than 10% but be less than or equal to 20%；SiO₂: 0-3%；Nb₂O₅: 0- 5%；Y₂O₃: 0-10%；(ZrO₂+Y₂O₃)/(Nb₂O₅+Gd₂O₃) it is 0.30-1.50；Without containing Ta₂O₅And SnO₂, refractive index is 1.76-1.80, Abbe number 47-51.

2. optical glass as described in claim 1, which is characterized in that also contain: Al₂O₃: 0-10% and/or Li₂O:0-10% And/or Na₂O:0-10% and/or K₂O:0-10% and/or GeO₂: 0-10% and/or Bi₂O₃: 0-10% and/or CeO₂: 0-1% And/or Sb₂O₃: 0-1% and/or RO:0-10%, wherein one of RO MgO, CaO, SrO or BaO or a variety of.

3. optical glass as claimed in claim 2, which is characterized in that wherein, Al₂O₃: 0-5% and/or Li₂O:0-5% and/ Or Na₂O:0-5% and/or K₂O:0-5% and/or GeO₂: 0-5% and/or Bi₂O₃: 0-5% and/or CeO₂: 0-0.5% and/or Sb₂O₃: 0-0.5% and/or RO:0-5%.

4. optical glass as claimed in claim 2, which is characterized in that wherein, Al₂O₃: 0-1% and/or Li₂O:0-1% and/ Or Na₂O:0-1% and/or K₂O:0-1% and/or GeO₂: 0-1% and/or Bi₂O₃: 0-1%.

5. optical glass as claimed in claim 1 or 2, which is characterized in that wherein, B₂O₃: 28.5-35% and/or La₂O₃: 25- 35% and/or Gd₂O₃: 14-22% and/or ZrO₂: 6.5-10% and/or ZnO:11-16% and/or SiO₂: 0-2% and/or Nb₂O₅: 0-1% and/or Y₂O₃: 0-5%.

6. optical glass as claimed in claim 1 or 2, which is characterized in that wherein, B₂O₃: 29-32% and/or La₂O₃: 27- 32% and/or Gd₂O₃: 15-20% and/or ZrO₂: 6.5-8.5% and/or ZnO:11-14.5% and/or SiO₂: 0-0.5% And/or Nb₂O₅: 0-0.5% and/or Y₂O₃: 0-1%.

7. optical glass as claimed in claim 1 or 2, which is characterized in that wherein, ZnO/ (B₂O₃+SiO₂) it is 0.25-0.65； And/or La₂O₃/(La₂O₃+Gd₂O₃+Y₂O₃) it is 0.38-0.75.

8. optical glass as claimed in claim 1 or 2, which is characterized in that wherein, La₂O₃/(La₂O₃+Gd₂O₃+Y₂O₃) be 0.45-0.70；And/or ZnO/ (B₂O₃+SiO₂) it is 0.30-0.55；And/or (ZrO₂+Y₂O₃)/(Nb₂O₅+Gd₂O₃) it is 0.48- 1.10。

9. optical glass as claimed in claim 1 or 2, which is characterized in that wherein, La₂O₃/(La₂O₃+Gd₂O₃+Y₂O₃) be 0.55-0.65；And/or ZnO/ (B₂O₃+SiO₂) it is 0.30-0.50；And/or (ZrO₂+Y₂O₃)/(Nb₂O₅+Gd₂O₃) it is 0.50- 1.0。

10. optical glass as claimed in claim 1 or 2, which is characterized in that the density of glass is in 5.00g/cm³Below；Glass Transition temperature Tg at 625 DEG C or less.

11. gas preform is made of optical glass described in claim 1-10 any claim.

12. optical element is made of optical glass described in claim 1-10 any claim.