WO2021060362A1 - Optical glass and optical element - Google Patents

Optical glass and optical element Download PDF

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Publication number
WO2021060362A1
WO2021060362A1 PCT/JP2020/035992 JP2020035992W WO2021060362A1 WO 2021060362 A1 WO2021060362 A1 WO 2021060362A1 JP 2020035992 W JP2020035992 W JP 2020035992W WO 2021060362 A1 WO2021060362 A1 WO 2021060362A1
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WO
WIPO (PCT)
Prior art keywords
content
glass
tio
optical
mass
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PCT/JP2020/035992
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French (fr)
Japanese (ja)
Inventor
俊伍 桑谷
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Hoya株式会社
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Publication date
Priority claimed from JP2019175787A external-priority patent/JP2021050126A/en
Priority claimed from JP2020002064A external-priority patent/JP2021109799A/en
Priority claimed from JP2020125251A external-priority patent/JP2022021586A/en
Application filed by Hoya株式会社 filed Critical Hoya株式会社
Priority to CN202080002703.1A priority Critical patent/CN112867699A/en
Publication of WO2021060362A1 publication Critical patent/WO2021060362A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/12—Silica-free oxide glass compositions
    • C03C3/16—Silica-free oxide glass compositions containing phosphorus
    • C03C3/21—Silica-free oxide glass compositions containing phosphorus containing titanium, zirconium, vanadium, tungsten or molybdenum
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/062—Glass compositions containing silica with less than 40% silica by weight
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/062—Glass compositions containing silica with less than 40% silica by weight
    • C03C3/064—Glass compositions containing silica with less than 40% silica by weight containing boron
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/12—Silica-free oxide glass compositions
    • C03C3/16—Silica-free oxide glass compositions containing phosphorus
    • C03C3/19—Silica-free oxide glass compositions containing phosphorus containing boron
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C4/00—Compositions for glass with special properties
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements

Definitions

  • the present invention relates to optical glass and optical elements.
  • Optical elements incorporated in in-vehicle optical equipment and optical elements incorporated in heat-generating optical equipment are used in environments with large temperature changes. Fluctuations in optical characteristics such as the refractive index due to temperature changes affect the imaging characteristics of the optical system.
  • the temperature coefficient of the relative refractive index (dn / dT) represents the change in the refractive index with respect to the temperature change. In an optical element whose refractive index decreases as the temperature rises, the temperature coefficient of relative refractive index becomes negative. On the contrary, in an optical element in which the refractive index increases as the temperature rises, the temperature coefficient of the relative refractive index becomes positive.
  • the productivity is inferior, and the glass melting equipment (for example, a crucible, a stirring equipment for molten glass, etc.) in the melting process is eroded, and the economic efficiency is also inferior. Therefore, a glass having a low liquidus temperature LT, that is, a glass having a low melting temperature and molding temperature of the glass is required.
  • Patent Document 1 discloses an optical glass in which the temperature coefficient (dn / dT) of the relative refractive index is negative. However, it has been found that the glass of Patent Document 1 has a high liquidus temperature LT and is inferior in productivity and economy.
  • the average coefficient of linear thermal expansion of the optical element is important when performing optical design.
  • a low refractive index low dispersion glass material and a high refractive index high dispersion glass material are combined, the smaller the difference in the average linear thermal expansion coefficient of the glass material, the better the bonding.
  • a low refractive index low dispersion glass material containing fluorine usually has a large average linear thermal expansion coefficient. Therefore, the high refractive index and high dispersion glass material to be combined with it is also required to have a high average linear thermal expansion coefficient.
  • the optical glass disclosed in Patent Document 2 has a high refractive index but a low dispersion and a small average linear thermal expansion coefficient. Therefore, there is a demand for optical glass having a high refractive index and a high dispersion and a large average linear thermal expansion coefficient.
  • an object of the present invention is to provide an optical glass having a low temperature coefficient (dn / dT) of a relative refractive index due to a temperature change and a large average linear thermal expansion coefficient, and an optical element made of the optical glass.
  • the gist of the present invention is as follows. (1)
  • the refractive index nd is 1.63 to 1.80, and the refractive index nd is 1.63 to 1.80.
  • the Abbe number ⁇ d is 22 to 34
  • the content of Nb 2 O 5 is 25 to 55% by mass
  • the content of WO 3 is less than 30% by mass
  • the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 36 to 60% by mass.
  • Mass ratio of total contents of 2 O 3 and Ta 2 O 5 [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3) + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.10 or less,
  • the mass ratio of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 [TiO 2 / (P 2 O 5 + B 2 O 3 )] is 0.50 or less.
  • (A) The content of P 2 O 5 is 20 to 36% by mass, and the content is 20 to 36% by mass.
  • Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.50 or less.
  • P 2 O 5 mass ratio of the content of B 2 O 3 to the content of [B 2 O 3 / P 2 O 5] is 0.05 to 0.39
  • the total content [MgO + CaO + SrO + BaO] of MgO, CaO, SrO and BaO is 8.0% by mass or less.
  • the content of P 2 O 5 is 25 to 38% by mass, and the content is 25 to 38% by mass.
  • the content of Al 2 O 3 is less than 5% by mass
  • Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
  • the total content of MgO, CaO, SrO and BaO [MgO + CaO + SrO + BaO] is 7.0% by mass or less.
  • the mass ratio of the content of TiO 2 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 is 0.25 or more.
  • the content of P 2 O 5 is 25 to 50% by mass, and the content is 25 to 50% by mass.
  • the content of TiO 2 is 10 to 50% by mass,
  • the Nb 2 O 5 content is 5 to 30% by mass,
  • the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 35 to 60% by mass.
  • Mass ratio of TiO 2 content to total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more, Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
  • A) The content of WO 3 is 7% by mass or less.
  • the content of P 2 O 5 is 25 to 50% by mass, and the content is 25 to 50% by mass.
  • the Nb 2 O 5 content is 14-40% by mass.
  • the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 35 to 60% by mass.
  • Mass ratio of TiO 2 content to total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more, P 2 O 5 mass ratio of the content of B 2 O 3 to the content of [B 2 O 3 / P 2 O 5] is 0.05 to 0.39
  • the total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O [Li 2 O + Na 2 O + K 2 O + Cs 2 O] is 10% by mass or more.
  • K 2 O weight ratio of Na 2 O content to the content of [Na 2 O / K 2 O ] is 1.50 or more, an optical glass.
  • the temperature coefficient dn / dT of the relative refractive index at the wavelength of the He-Ne laser (633 nm) is ⁇ 0.1 ⁇ 10 -6 to -13.0 ⁇ 10 -6 ° C -1 in the range of 20 to 40 ° C.
  • the optical glass according to any one of (1), (2), (4) to (6).
  • an optical glass having a low temperature coefficient (dn / dT) of a relative refractive index due to a temperature change and a large average linear thermal expansion coefficient, and an optical element made of the optical glass.
  • the glass composition of optical glass in the present invention and the present specification is expressed on an oxide basis.
  • the "oxide-based glass composition” refers to a glass composition obtained by converting all glass raw materials into those that are decomposed at the time of melting and exist as oxides in optical glass, and the notation of each glass component is Following the convention, it is described as SiO 2 , TiO 2 , and so on.
  • the content and total content of the glass component are based on mass, and "%" means “mass%”.
  • the content of the glass component can be quantified by a known method, for example, an inductively coupled plasma emission spectroscopic analysis method (ICP-AES), an inductively coupled plasma mass analysis method (ICP-MS), or the like.
  • ICP-AES inductively coupled plasma emission spectroscopic analysis method
  • ICP-MS inductively coupled plasma mass analysis method
  • the content of the constituent component is 0%, which means that the constituent component is substantially not contained, and the component is allowed to be contained at an unavoidable impurity level.
  • thermal stability refers to the difficulty of crystal precipitation in glass.
  • thermal stability refers to the difficulty of crystal precipitation when the molten glass solidifies
  • devitrification resistance refers to the difficulty of crystal precipitation when the solidified glass is reheated, as in the case of reheat pressing. It shall refer to the difficulty.
  • the refractive index refers to the refractive index nd at the d-line (wavelength 587.56 nm) of helium unless otherwise specified.
  • ⁇ d is used as a value representing a property related to dispersion, and is expressed by the following equation.
  • nF is the refractive index of blue hydrogen at the F line (wavelength 486.13 nm)
  • nC is the refractive index of red hydrogen at the C line (656.27 nm).
  • ⁇ d (nd-1) / nF-nC ... (1)
  • optical glass of the present invention will be described separately for the first embodiment, the second embodiment, and the third embodiment.
  • the optical glass is The refractive index nd is 1.63 to 1.80, and the refractive index nd is 1.63 to 1.80.
  • the Abbe number ⁇ d is 22 to 34,
  • the content of Nb 2 O 5 is 25 to 55% by mass,
  • the content of WO 3 is less than 30% by mass,
  • the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 36 to 60% by mass.
  • Mass ratio of total contents of 2 O 3 and Ta 2 O 5 [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3) + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.10 or less,
  • the mass ratio of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 [TiO 2 / (P 2 O 5 + B 2 O 3 )] is 0.50 or less.
  • the following (A) or (B) is satisfied.
  • (A) The content of P 2 O 5 is 20 to 36% by mass, and the content is 20 to 36% by mass.
  • Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.50 or less.
  • P 2 O 5 mass ratio of the content of B 2 O 3 to the content of [B 2 O 3 / P 2 O 5] is 0.05 to 0.39
  • the total content [MgO + CaO + SrO + BaO] of MgO, CaO, SrO and BaO is 8.0% by mass or less.
  • the content of P 2 O 5 is 25 to 38% by mass, and the content is 25 to 38% by mass.
  • the content of Al 2 O 3 is less than 5% by mass
  • Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
  • the total content of MgO, CaO, SrO and BaO [MgO + CaO + SrO + BaO] is 7.0% by mass or less.
  • the mass ratio of the content of TiO 2 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 is 0.25 or more.
  • the optical glass according to the first embodiment means the optical glass according to the first embodiment satisfying the above (A) and the optical glass according to the first embodiment satisfying the above (B). And.
  • the refractive index nd is 1.63 to 1.80.
  • the lower limit of the refractive index nd may be 1.65, 1.67, or 1.69, and the upper limit of the refractive index nd may be 1.79, 1.78, or 1.77.
  • the refractive index nd can be set to a desired value by appropriately adjusting the content of each glass component.
  • the components having the function of relatively increasing the refractive index nd are Nb 2 O 5 , TiO 2 , WO 3 , Bi 2 O 3 , Ta 2 O 5 , ZrO 2 , La 2 O 3, etc. Is.
  • the components having a function of relatively lowering the refractive index nd are P 2 O 5 , SiO 2 , B 2 O 3 , Li 2 O, Na 2 O, K 2 O and the like. is there.
  • TIO 2 , Nb 2 O 5 with respect to the total content of P 2 O 5 , B 2 O 3 , SiO 2 , Al 2 O 3 , Li 2 O, Na 2 O, K 2 O and Cs 2 O, Mass ratio of total contents of WO 3 , Bi 2 O 3 and Ta 2 O 5 [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5 + B 2 O 3 + SiO 2) + Al 2 O 3 + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] can be increased to increase the refractive index nd, and decreasing the mass ratio can decrease the refractive index nd.
  • the Abbe number ⁇ d is 22 to 34.
  • the lower limit of the Abbe number ⁇ d may be 22.5, 23, or 23.5, and the upper limit of the Abbe number ⁇ d may be 32, 30, or 28.
  • the Abbe number ⁇ d can be set to a desired value by appropriately adjusting the content of each glass component.
  • the components that relatively lower the Abbe number ⁇ d, that is, the highly dispersed components, are Nb 2 O 5 , TiO 2 , WO 3 , Bi 2 O 3 , Ta 2 O 5 , ZrO 2, and the like.
  • the components that relatively increase the Abbe number ⁇ d, that is, the low dispersion components are P 2 O 5 , SiO 2 , B 2 O 3 , Li 2 O, Na 2 O, K 2 O, La 2 O 3 , BaO, CaO, SrO and the like.
  • the content of Nb 2 O 5 is 25 to 55%.
  • the lower limit of the content of Nb 2 O 5 is preferably 27%, more preferably 29%, 31%, and 33% in that order.
  • the upper limit of the content of Nb 2 O 5 is preferably 53%, more preferably 51%, 49%, and 47% in that order.
  • Nb 2 O 5 is a component that contributes to high refractive index and high dispersion. Therefore, by setting the content of Nb 2 O 5 in the above range, an optical glass having a desired optical constant can be obtained. On the other hand, if the content of Nb 2 O 5 is too large, the coloring of the glass may be strengthened.
  • the content of WO 3 is less than 30%.
  • the upper limit of the content of WO 3 is preferably 20%, more preferably 15%, 10%, and 5%.
  • the content of WO 3 is preferably low, and the lower limit thereof is preferably 0%.
  • the content of WO 3 may be 0%.
  • the transmittance can be increased and the increase in the specific gravity of the glass can be suppressed. Further, the temperature coefficient (dn / dT) of the relative refractive index can be lowered.
  • the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 is 36 to 60%.
  • the lower limit of the total content is preferably 38%, more preferably 40%, 41%, and 42%.
  • the upper limit of the total content is preferably 58%, more preferably 56%, 54%, and 52%.
  • TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 are components that contribute to high dispersion of glass. Therefore, by setting the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] in the above range, an optical glass having a desired optical constant can be obtained. In addition, the thermal stability of the glass can be improved. On the other hand, if the total content is too large, an optical glass having a desired optical constant may not be obtained, the thermal stability of the glass may be lowered, and the coloring of the glass may be strengthened.
  • the upper limit of the mass ratio is preferably 1.07, and more preferably 1.04, 1.02, and 1.00 in that order.
  • the lower limit of the mass ratio is more preferably 0.50, and more preferably 0.55, 0.60, and 0.65.
  • the mass ratio of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 [TiO 2 / (P 2 O 5 + B 2 O 3 )] is 0. It is 50 or less.
  • optical glass according to the first embodiment satisfies (A) or (B) as described above.
  • (A) will be described in detail.
  • the optical glass according to the first embodiment is (A)
  • the content of P 2 O 5 is 20 to 36% by mass, and the content is 20 to 36% by mass.
  • Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.50 or less.
  • P 2 O 5 mass ratio of the content of B 2 O 3 to the content of [B 2 O 3 / P 2 O 5] is 0.05 to 0.39
  • the total content of MgO, CaO, SrO and BaO [MgO + CaO + SrO + BaO] is 8.0% by mass or less. Can meet the requirements of.
  • the content of P 2 O 5 is 20 to 36 percent.
  • the lower limit of the content of P 2 O 5 is preferably 21%, more preferably 22%, 23%, and 24%.
  • the upper limit of the content of P 2 O 5 is preferably 35%, more preferably 34%, 33%, and 32% in that order.
  • P 2 O 5 is a network-forming component of glass, and is an essential component for containing a large amount of highly dispersed components in glass. By setting the content of P 2 O 5 in the above range, an optical glass having high thermal stability and a desired optical constant can be obtained.
  • the mass ratio of the content [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.50 or less.
  • the upper limit of the mass ratio is preferably 1.47, and more preferably 1.44, 1.42, and 1.40 in that order.
  • the lower limit of the mass ratio is preferably 1.00, more preferably 1.05, 1.08, and 1.10.
  • the thermal stability is high and the temperature coefficient of relative refractive index ( An optical glass having a low dn / dT) and a large average coefficient of linear thermal expansion can be obtained.
  • the mass ratio of the content of B 2 O 3 to the content of P 2 O 5 [B 2 O 3 / P 2 O 5] 0.05 ⁇ It is 0.39.
  • the lower limit of the mass ratio is preferably 0.06, more preferably 0.07, 0.08, 0.09.
  • the upper limit of the mass ratio is more preferably 0.36, and further preferably 0.33, 0.31 and 0.29.
  • the mass ratio [B 2 O 3 / P 2 O 5 ] in the above range the temperature coefficient of relative refractive index (dn / dT) is low, the average coefficient of linear thermal expansion is large, and the devitrification resistance is high. Further, an optical glass having a low liquidus temperature LT can be obtained.
  • the total content [MgO + CaO + SrO + BaO] of MgO, CaO, SrO and BaO is 8.0% or less.
  • the upper limit of the total content is preferably 6%, more preferably 5%, 4%, and 3%.
  • the lower limit of the total content is preferably 0%.
  • the mass ratio of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 [TiO 2 / (P 2 O 5 + B). 2 O 3 )] is 0.50 or less.
  • the upper limit of the mass ratio is preferably 0.47, more preferably 0.44, 0.42, 0.40 in that order.
  • the lower limit of the mass ratio is more preferably 0.00, and further preferably 0.03, 0.06, 0.08, 0.10.
  • Non-limiting examples of the content and ratio of the glass component in the optical glass according to the first embodiment satisfying the above (A) are shown below.
  • the upper limit of the content of B 2 O 3 is preferably 10%, more preferably 8%, 7%, and 6%.
  • the lower limit of the content of B 2 O 3 is preferably 1%, more preferably 1.5%, 1.8%, and 2.0% in that order.
  • B 2 O 3 is a network-forming component of glass and has a function of improving the thermal stability of glass.
  • the content of B 2 O 3 is preferably in the above range.
  • the content of Al 2 O 3 is preferably 3% or less, more preferably 2% or less and 1% or less.
  • the content of Al 2 O 3 may be 0%.
  • Al 2 O 3 is a glass component having a function of improving the chemical durability and weather resistance of glass, and can be considered as a network forming component.
  • the content of Al 2 O 3 increases, the devitrification resistance of the glass decreases.
  • problems such as an increase in the glass transition temperature Tg and a decrease in thermal stability are likely to occur.
  • the upper limit of the content of Al 2 O 3 is preferably in the above range.
  • the mass ratio of the content of TiO 2 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [
  • the lower limit of TiO 2 / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 )] is preferably 0, and more preferably 0.02, 0.04, and 0.06.
  • the upper limit of the mass ratio is preferably 0.50, and more preferably 0.45, 0.40, and 0.35.
  • TiO 2 is a component having a particularly large effect of increasing the refractive index among the components for increasing the refractive index. Therefore, from the viewpoint of obtaining a desired optical constant, the mass ratio [TiO 2 / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 )] is preferably in the above range.
  • the lower limit of the TiO 2 content is preferably 0%, more preferably 1%, 2%, 3%, and 4%.
  • the content of TiO 2 may be 0%.
  • the upper limit of the TiO 2 content is preferably 15%, more preferably 13%, 11%, and 10%.
  • TiO 2 greatly contributes to high dispersion. On the other hand, TiO 2 tends to increase the coloring of the glass relatively easily, and may deteriorate the meltability. Therefore, the content of TiO 2 is preferably in the above range.
  • the total content of TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 ]
  • the lower limit is preferably 36%, more preferably 38%, 40%, 41%, and 42% in that order.
  • the upper limit of the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 ] is preferably 58%, more preferably 56%, 54%, and 52%.
  • TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 contribute to high dispersion of glass, and also have a function of improving the thermal stability of glass by containing an appropriate amount. On the other hand, it is also a component that increases the coloring of glass. Therefore, the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 ] is preferably in the above range.
  • the lower limit of the Na 2 O content is preferably 6%, more preferably 8%, 9%, and 10% in that order.
  • the upper limit of the Na 2 O content is preferably 30%, more preferably 28%, 26%, and 25%.
  • Na 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion.
  • the Na 2 O content is preferably in the above range.
  • the upper limit of the total content [Li 2 O + Na 2 O + K 2 O] of Li 2 O, Na 2 O and K 2 O is preferably 35%. Further, it is more preferable in the order of 33%, 31%, and 30%.
  • the lower limit of the total content is preferably 10%, more preferably 14%, 17%, and 18%.
  • Li 2 O, Na 2 O and K 2 O all have a function of improving the thermal stability of glass. However, if these contents are high, the chemical durability and weather resistance may be lowered. Therefore, the total content of Li 2 O, Na 2 O and K 2 O [Li 2 O + Na 2 O + K 2 O] is preferably in the above range.
  • the optical glass according to the first embodiment is (B)
  • the content of P 2 O 5 is 25 to 38% by mass, and the content is 25 to 38% by mass.
  • the content of Al 2 O 3 is less than 5% by mass
  • Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
  • the total content of MgO, CaO, SrO and BaO [MgO + CaO + SrO + BaO] is 7.0% by mass or less.
  • the mass ratio of the content of TiO 2 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 is 0.25 or more, Can meet the requirements of.
  • the content of P 2 O 5 is 25 to 38 percent.
  • the lower limit of the content of P 2 O 5 is preferably 26%, more preferably 27%, 28%, 29% and 30%.
  • the upper limit of the content of P 2 O 5 is preferably 37%.
  • P 2 O 5 is a network-forming component of glass, and is an essential component for containing a large amount of highly dispersed components in glass. By setting the content of P 2 O 5 in the above range, an optical glass having high thermal stability and a desired optical constant can be obtained.
  • the content of Al 2 O 3 is less than 5%.
  • the content of Al 2 O 3 is preferably 3% or less, more preferably 2% or less and 1% or less.
  • the content of Al 2 O 3 may be 0%.
  • Al 2 O 3 is a glass component having a function of improving the chemical durability and weather resistance of glass, and can be considered as a network forming component.
  • the content of Al 2 O 3 increases, the devitrification resistance of the glass decreases.
  • problems such as an increase in the glass transition temperature Tg and a decrease in thermal stability are likely to occur.
  • the upper limit of the content of Al 2 O 3 is preferably in the above range.
  • the mass ratio of the content [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
  • the upper limit of the mass ratio is preferably 1.78, and more preferably 1.76 and 1.74.
  • the lower limit of the mass ratio is preferably 1.00, more preferably 1.05, 1.08, and 1.10.
  • the thermal stability is high and the temperature coefficient of relative refractive index ( An optical glass having a low dn / dT) and a large average coefficient of linear thermal expansion can be obtained.
  • the total content [MgO + CaO + SrO + BaO] of MgO, CaO, SrO and BaO is 7.0% or less.
  • the upper limit of the total content is preferably 6%, more preferably 5%, 4%, and 3%.
  • the lower limit of the total content is preferably 0%.
  • the mass ratio of the content of TiO 2 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 is 0.25 or more.
  • the lower limit of the mass ratio is preferably 0.26, more preferably 0.27, 0.28, 0.29 in that order.
  • the upper limit of the mass ratio is preferably 0.50, and more preferably 0.45, 0.40, and 0.35.
  • TiO 2 is a component having a particularly large effect of increasing the refractive index among the components for increasing the refractive index. Therefore, from the viewpoint of obtaining a desired optical constant, the mass ratio [TiO 2 / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 )] is preferably in the above range.
  • the mass ratio of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 [TiO 2 / (P 2 O 5 + B). 2 O 3 )] is 0.50 or less.
  • the upper limit of the mass ratio is preferably 0.47, and more preferably 0.46 and 0.45 in that order.
  • the lower limit of the mass ratio is preferably 0.00, and more preferably 0.20, 0.25, 0.30, and 0.35 in that order.
  • Non-limiting examples of the content and ratio of the glass component in the optical glass according to the first embodiment satisfying the above (B) are shown below.
  • the lower limit of the content of the mass ratio of B 2 O 3 to the content of P 2 O 5 [B 2 O 3 / P 2 O 5] are preferably Is 0.
  • the mass ratio may be 0.
  • the upper limit of the mass ratio is more preferably 0.36, and further preferably 0.33, 0.31 and 0.29.
  • the mass ratio [B 2 O 3 / P 2 O 5 ] in the above range the temperature coefficient of relative refractive index (dn / dT) is low, the average coefficient of linear thermal expansion is large, and the devitrification resistance is high. Further, an optical glass having a low liquidus temperature LT can be obtained.
  • the upper limit of the content of B 2 O 3 is preferably 10%, more preferably 8%, 7%, and 6%.
  • the lower limit of the content of B 2 O 3 is preferably 0%.
  • the content of B 2 O 3 may be 0%.
  • B 2 O 3 is a network-forming component of glass and has a function of improving the thermal stability of glass.
  • the content of B 2 O 3 is preferably in the above range.
  • the lower limit of the content of TiO 2 is preferably 0%, and further 1%, 2%, 3%, 4%, 6%, 8 %, 10%, and 12% are more preferable.
  • the content of TiO 2 may be 0%.
  • the upper limit of the TiO 2 content is preferably 15%.
  • TiO 2 greatly contributes to high dispersion. On the other hand, TiO 2 tends to increase the coloring of the glass relatively easily, and may deteriorate the meltability. Therefore, the content of TiO 2 is preferably in the above range.
  • the total content of TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 ]
  • the lower limit is preferably 36%, more preferably 38%, 40%, 41%, and 42% in that order.
  • the upper limit of the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 ] is preferably 58%, further 56%, 54%, 52%, 50%, 48%, 46%. More preferred in order.
  • TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 contribute to high dispersion of glass, and also have a function of improving the thermal stability of glass by containing an appropriate amount. On the other hand, it is also a component that increases the coloring of glass. Therefore, the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 ] is preferably in the above range.
  • the lower limit of the Na 2 O content is preferably 6%, more preferably 8%, 9%, and 10%.
  • the upper limit of the Na 2 O content is preferably 30%, and more preferably 28%, 26%, 25%, 22%, 20%, 18%, and 17% in that order.
  • Na 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion.
  • the Na 2 O content is preferably in the above range.
  • the upper limit of the total content [Li 2 O + Na 2 O + K 2 O] of Li 2 O, Na 2 O and K 2 O is preferably 35%. Further, 33%, 31%, 30%, 28%, 27%, 26%, and 25% are preferable in this order.
  • the lower limit of the total content is preferably 10%, more preferably 14%, 17%, 18%, and 20%.
  • Li 2 O, Na 2 O and K 2 O all have a function of improving the thermal stability of glass. However, if these contents are high, the chemical durability and weather resistance may be lowered. Therefore, the total content of Li 2 O, Na 2 O and K 2 O [Li 2 O + Na 2 O + K 2 O] is preferably in the above range.
  • the content of Nb 2 O 5 in the optical glass according to the first embodiment satisfying the above (B) is 25 to 55%.
  • the lower limit of the content of Nb 2 O 5 is preferably 27%, more preferably 29%.
  • the upper limit of the content of Nb 2 O 5 is preferably 53%, and more preferably 51%, 49%, 47%, 40%, 35%, and 33% in that order.
  • Nb 2 O 5 is a component that contributes to high refractive index and high dispersion. Therefore, by setting the content of Nb 2 O 5 in the above range, an optical glass having a desired optical constant can be obtained. On the other hand, if the content of Nb 2 O 5 is too large, the coloring of the glass may be strengthened.
  • the lower limit of the average coefficient of linear thermal expansion ⁇ of 100 to 300 ° C. is preferably 100 ⁇ 10 -7 ° C. -1 , and further 105 ⁇ 10 -7 ° C. -1 , 110. It is more preferable in the order of ⁇ 10 -7 ° C -1 , 115 ⁇ 10 -7 ° C -1 , and 120 ⁇ 10 -7 ° C -1.
  • the upper limit of the average coefficient of linear thermal expansion ⁇ is more preferably 200 ⁇ 10 -7 °C -1 , and further 190 ⁇ 10 -7 °C -1 , 180 ⁇ 10 -7 °C -1 , 170 ⁇ 10 ⁇ . It is more preferable in the order of 7 ° C -1 and 160 ⁇ 10 -7 ° C -1.
  • the average coefficient of linear expansion ⁇ is measured based on the provisions of JOBIS08-2003. However, the sample shall be a round bar with a length of 20 mm ⁇ 0.5 mm and a diameter of 5 mm ⁇ 0.5 mm, and with a load of 98 mN applied to the sample, it shall be heated so as to rise at a constant rate of 4 ° C. And measure the elongation of the sample.
  • the average coefficient of linear expansion ⁇ is expressed in the unit of [° C -1 ], but the numerical value of the average coefficient of linear expansion ⁇ is the same even when [K -1] is used as the unit.
  • the temperature coefficient dn / dT of the relative refractive index at the wavelength (633 nm) of the He—Ne laser is in the range of 20 to 40 ° C., preferably ⁇ 1.0 ⁇ 10-6 to. -10.0 x 10 -6 ° C -1 , and further -1.5 x 10 -6 to -9.0 x 10 -6 ° C -1 , -2.0 x 10 -6 to -8.0.
  • the temperature coefficient dn / dT of the relative refractive index is measured based on the interferometry of JOBIS18-2008.
  • the temperature coefficient dn / dT is expressed in the unit of [° C-1 ], but the numerical value of the temperature coefficient dn / dT is the same even when [K -1] is used as the unit. ..
  • Glass component Non-limiting examples of the content and ratio of glass components other than the above in the optical glass according to the first embodiment are shown below.
  • the upper limit of the content of SiO 2 is preferably 5%, more preferably 3%, 2%, and 1%.
  • the content of SiO 2 may be 0%.
  • a quartz glass melting device such as a quartz glass crucible may be used to melt the glass.
  • the glass frit is produced be free of SiO 2 contains a small amount of SiO 2.
  • the amount of SiO 2 mixed into the glass from the quartz glass melting device depends on the melting conditions, but is, for example, about 0.5 to 1% by mass with respect to the total content of all glass components.
  • the amount of SiO 2 increases by about 0.5 to 1% by mass while the content ratio of the glass component other than SiO 2 remains constant. The above amount may increase or decrease depending on the melting conditions. Since the optical characteristics such as the refractive index and the Abbe number change depending on the content of SiO 2, the content of the glass component other than SiO 2 is finely adjusted to obtain an optical glass having desired optical characteristics.
  • SiO 2 is a network-forming component of glass, and has a function of improving thermal stability, chemical durability, and weather resistance of glass, increasing the viscosity of molten glass, and facilitating molding of molten glass.
  • the upper limit of the content of SiO 2 is preferably in the above range.
  • the upper limit of the content of Bi 2 O 3 is preferably 15%, more preferably 10%, 7%, 5%, and 3% in that order.
  • the lower limit of the Bi 2 O 3 content is preferably 0%.
  • Bi 2 O 3 has a function of improving the thermal stability of glass by containing an appropriate amount.
  • the content of Bi 2 O 3 is increased, the coloring of the glass is increased. Therefore, the content of Bi 2 O 3 is preferably in the above range.
  • the upper limit of the content of Ta 2 O 5 is preferably 10%, more preferably 7%, 5%, and 3%.
  • the lower limit of the content of Ta 2 O 5 is preferably 0%.
  • the content of Ta 2 O 5 may be 0%.
  • Ta 2 O 5 is a glass component having a function of improving the thermal stability and devitrification resistance of glass.
  • Ta 2 O 5 increases the refractive index and makes the glass highly dispersed. Further, when the content of Ta 2 O 5 is increased, the thermal stability of the glass is lowered, and when the glass is melted, the unmelted residue of the glass raw material is likely to occur. Therefore, the content of Ta 2 O 5 is preferably in the above range.
  • Ta 2 O 5 is an extremely expensive component as compared with other glass components, and as the content of Ta 2 O 5 increases, the production cost of glass increases. Further, since Ta 2 O 5 has a larger molecular weight than other glass components, it increases the specific gravity of the glass, and as a result, increases the weight of the optical element.
  • the upper limit of the Li 2 O content is preferably 5%, more preferably 3%, 2%, and 1%.
  • the lower limit of the Li 2 O content is preferably 0%.
  • the content of Li 2 O may be 0%.
  • Li 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion.
  • the Li 2 O content is preferably in the above range.
  • the lower limit of K 2 O content is preferably 1%, even 2%, 3%, preferably by 4% order.
  • the upper limit of the content of K 2 O is preferably 13%, further 12%, 11%, preferably by 10% order.
  • K 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the thermal stability of glass. It also has the function of increasing the average coefficient of linear thermal expansion.
  • the content of K 2 O is within the above range.
  • the upper limit of the content of Cs 2 O is preferably 5%, more preferably 3%, 2%, and 1%.
  • the lower limit of the Cs 2 O content is preferably 0%.
  • the content of Cs 2 O may be 0%.
  • Cs 2 O has a function of improving the meltability of glass, but when the content is increased, the thermal stability and refractive index nd of the glass are lowered, and the volatilization of the glass component is increased during melting. The desired glass cannot be obtained. Therefore, the content of Cs 2 O is preferably in the above range.
  • the content of MgO is preferably 5% or less, more preferably 3% or less and 1% or less.
  • the lower limit of the MgO content is preferably 0%.
  • the content of MgO may be 0%.
  • the CaO content is preferably 5% or less, more preferably 3% or less and 1% or less.
  • the lower limit of the CaO content is preferably 0%.
  • the CaO content may be 0%.
  • the SrO content is preferably 6% or less, more preferably 5% or less, 3% or less, and 1% or less.
  • the lower limit of the SrO content is preferably 0%.
  • the BaO content is preferably 8% or less, more preferably 5% or less, 3% or less, and 1% or less.
  • the lower limit of the BaO content is preferably 0%.
  • MgO, CaO, SrO, and BaO are all glass components having a function of improving the thermal stability and devitrification resistance of glass.
  • the content of these glass components is increased, the high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass are lowered. Therefore, the content of each of these glass components is preferably in the above range.
  • the upper limit of the ZnO content is preferably 10%, more preferably 6%, 4%, and 3%.
  • the ZnO content is preferably low, and the lower limit thereof is preferably 0%.
  • the ZnO content may be 0%.
  • ZnO is a glass component having a function of improving the thermal stability of glass.
  • the ZnO content is too high, the specific gravity of the glass increases. Further, the temperature coefficient (dn / dT) of the relative refractive index becomes high. Therefore, the ZnO content is preferably in the above range.
  • the content of ZrO 2 is preferably 5% or less, more preferably 3% or less and 1% or less.
  • the lower limit of the ZrO 2 content is preferably 0%.
  • ZrO 2 is a glass component having a function of improving the thermal stability and devitrification resistance of glass. However, if the content of ZrO 2 is too high, the thermal stability tends to decrease. Therefore, the content of ZrO 2 is preferably in the above range.
  • the upper limit of the Sc 2 O 3 content is preferably 2%.
  • the lower limit of the Sc 2 O 3 content is preferably 0%.
  • the upper limit of the HfO 2 content is preferably 2%.
  • the lower limit of the HfO 2 content is preferably 0%.
  • Sc 2 O 3 and HfO 2 both have a function of increasing the refractive index nd and are expensive components. Therefore, the contents of Sc 2 O 3 and HfO 2 are preferably in the above range.
  • the upper limit of the content of Lu 2 O 3 is preferably 2%.
  • the lower limit of the content of Lu 2 O 3 is preferably 0%.
  • Lu 2 O 3 has a function of increasing the refractive index nd. In addition, since it has a large molecular weight, it is also a glass component that increases the specific gravity of glass. Therefore, the content of Lu 2 O 3 is preferably in the above range.
  • the upper limit of the content of GeO 2 is preferably 2%.
  • the lower limit of the content of GeO 2 is preferably 0%.
  • GeO 2 has a function of increasing the refractive index nd, and is a prominently expensive component among commonly used glass components. Therefore, from the viewpoint of reducing the manufacturing cost of glass, the content of GeO 2 is preferably in the above range.
  • the upper limit of the content of La 2 O 3 is preferably 2%.
  • the lower limit of the content of La 2 O 3 is preferably 0%.
  • the content of La 2 O 3 may be 0%.
  • the content of La 2 O 3 is preferably in the above range from the viewpoint of suppressing the decrease in thermal stability and devitrification resistance.
  • the upper limit of the content of Gd 2 O 3 is preferably 2%.
  • the lower limit of the content of Gd 2 O 3 is preferably 0%.
  • the content of Gd 2 O 3 is preferably in the above range from the viewpoint of suppressing an increase in specific gravity while maintaining good thermal stability and devitrification resistance of the glass.
  • the upper limit of the content of Y 2 O 3 is preferably 2%.
  • the lower limit of the content of Y 2 O 3 is preferably 0%.
  • the content of Y 2 O 3 may be 0%.
  • the content of Y 2 O 3 is preferably in the range.
  • the upper limit of the content of Yb 2 O 3 is preferably 2%.
  • the lower limit of the content of Yb 2 O 3 is preferably 0%.
  • Yb 2 O 3 Since Yb 2 O 3 has a larger molecular weight than La 2 O 3 , Gd 2 O 3 , and Y 2 O 3 , it increases the specific gravity of glass. As the specific gravity of glass increases, the mass of the optical element increases. For example, if a lens having a large mass is incorporated into an autofocus type imaging lens, the power required to drive the lens during autofocus increases, and the battery consumption increases. Therefore, it is desirable to reduce the content of Yb 2 O 3 to suppress the increase in the specific gravity of the glass.
  • the content of Yb 2 O 3 is preferably in the above range from the viewpoint of preventing a decrease in thermal stability of the glass and suppressing an increase in specific gravity.
  • the optical glass according to the first embodiment satisfying the above (A) is mainly composed of the above-mentioned glass components, that is, P 2 O 5 , Nb 2 O 5 , B 2 O 3 as essential components, and WO 3 , SiO 2 as optional components.
  • the optical glass according to the first embodiment satisfying the above (B) is mainly composed of the above-mentioned glass components, that is, P 2 O 5 and Nb 2 O 5 as essential components, and B 2 O 3 and WO 3 as optional components.
  • the total content is preferably 95% or more, more preferably 98% or more, further preferably 99% or more, still more preferably 99.5% or more.
  • the upper limit of the content of TeO 2 is preferably 2%.
  • the lower limit of the content of TeO 2 is preferably 0%.
  • TeO 2 Since TeO 2 is toxic, it is preferable to reduce the content of TeO 2. Therefore, the content of TeO 2 is preferably in the above range.
  • the optical glass according to the first embodiment is basically composed of the above glass components, but it is also possible to contain other components as long as the effects of the present invention are not impaired. Further, in the present invention, the inclusion of unavoidable impurities is not excluded.
  • the optical glass according to the first embodiment does not contain these elements as a glass component.
  • the optical glass according to the first embodiment does not contain these elements as a glass component.
  • the optical glass according to the first embodiment does not contain these elements as a glass component.
  • Sb (Sb 2 O 3 ) and Ce (CeO 2 ) are arbitrarily addable elements that function as fining agents.
  • Sb (Sb 2 O 3 ) is a fining agent having a large fining effect.
  • Sb (Sb 2 O 3 ) is highly oxidizing, and if the amount of Sb (Sb 2 O 3 ) added is increased, the coloration of the glass increases due to light absorption by Sb ions, which is not preferable. Further, when the glass is melted, if Sb is present in the melt, the elution of platinum constituting the glass melting crucible into the melt is promoted, and the platinum concentration in the glass becomes high.
  • the content of Sb 2 O 3 is indicated by external division. That is, when the total content of all glass components other than Sb 2 O 3 and CeO 2 is 100% by mass, the content of Sb 2 O 3 is preferably less than 1% by mass, more preferably 0.1% by mass. Is less than. Further, is preferable in the order of less than 0.05% by mass, less than 0.03% by mass, and less than 0.02% by mass.
  • the content of Sb 2 O 3 may be 0% by mass.
  • the content of CeO 2 is also indicated by external division. That is, when the total content of all glass components other than CeO 2 and Sb 2 O 3 is 100% by mass, the content of CeO 2 is preferably less than 2% by mass, more preferably less than 1% by mass, and even more preferably. Is in the range of less than 0.5% by mass, more preferably less than 0.1% by mass.
  • the content of CeO 2 may be 0% by mass.
  • the glass transition temperature Tg of the optical glass according to the first embodiment is preferably 570 ° C. or lower, more preferably 560 ° C. or lower, 550 ° C. or lower, 540 ° C. or lower, and 530 ° C. or lower.
  • the upper limit of the glass transition temperature Tg satisfies the above range, it is possible to suppress an increase in the glass molding temperature and the annealing temperature, and it is possible to reduce thermal damage to the press molding equipment and the annealing equipment. Further, when the lower limit of the glass transition temperature Tg satisfies the above range, it becomes easy to maintain good thermal stability of the glass while maintaining a desired Abbe number and refractive index.
  • the specific gravity is preferably 3.60 or less, and more preferably 3.50 or less and 3.40 or less. If the specific gravity of the glass can be reduced, the weight of the lens can be reduced. As a result, the power consumption of the autofocus drive of the camera lens on which the lens is mounted can be reduced.
  • the light transmittance of the optical glass according to the first embodiment can be evaluated by the degree of coloring ⁇ 5.
  • the spectral transmittance of a glass sample having a thickness of 10.0 mm ⁇ 0.1 mm is measured in the wavelength range of 200 to 700 nm, and the wavelength at which the external transmittance is 5% is defined as ⁇ 5.
  • the ⁇ 5 of the optical glass according to the first embodiment is preferably 400 nm or less, more preferably 380 nm or less, and further preferably 370 nm or less.
  • the optical glass according to the embodiment of the present invention may be produced by blending a glass raw material so as to have the above-mentioned predetermined composition and using the blended glass raw material according to a known glass manufacturing method. For example, a plurality of types of compounds are mixed and sufficiently mixed to obtain a batch raw material, and the batch raw material is placed in a quartz crucible or a platinum crucible for rough melting. The melt obtained by crude melting is rapidly cooled and crushed to prepare a cullet. Further, the cullet is placed in a platinum crucible, heated and remelted to obtain molten glass, and after further clarification and homogenization, the molten glass is formed and slowly cooled to obtain an optical glass. A known method may be applied to the molding and slow cooling of the molten glass.
  • the compound used when preparing the batch raw material is not particularly limited, and examples of such a compound include oxides and carbonates. Examples thereof include salts, nitrates, hydroxides and fluorides.
  • a known method may be applied. For example, a glass raw material is melted to obtain molten glass, and the molten glass is poured into a mold to form a plate shape to produce a glass material made of optical glass according to the present invention. The obtained glass material is appropriately cut, ground, and polished to produce a cut piece having a size and shape suitable for press molding. The cut piece is heated and softened, and press-molded (reheat-pressed) by a known method to produce an optical element blank that approximates the shape of the optical element. An optical element blank is annealed and ground and polished by a known method to produce an optical element.
  • the optical functional surface of the manufactured optical element may be coated with an antireflection film, a total reflection film, or the like, depending on the purpose of use.
  • optical elements include various lenses such as spherical lenses, prisms, and diffraction gratings.
  • the optical glass according to the second embodiment will be described in detail.
  • the optical glass according to the second embodiment is The content of P 2 O 5 is 25 to 50% by mass,
  • the content of TiO 2 is 10 to 50% by mass,
  • the Nb 2 O 5 content is 5 to 30% by mass,
  • the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 35 to 60% by mass.
  • Mass ratio of TiO 2 content to total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more, Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
  • the following (A) or (B) is satisfied.
  • (A) The content of WO 3 is 7% by mass or less.
  • the optical glass according to the second embodiment means the optical glass according to the second embodiment satisfying the above (A) and the optical glass according to the second embodiment satisfying the above (B). And.
  • the content of P 2 O 5 is 25-50%.
  • the lower limit of the content of P 2 O 5 is preferably 27%, more preferably 29%, 31%, and 32% in that order.
  • the upper limit of the content of P 2 O 5 is preferably 42%, more preferably 40%, 38%, 37%, and 36%.
  • P 2 O 5 is a network-forming component of glass, and is an essential component for containing a large amount of highly dispersed components in glass. By setting the content of P 2 O 5 in the above range, an optical glass having high thermal stability and a desired optical constant can be obtained.
  • the content of TiO 2 is 10 to 50%.
  • the lower limit of the TiO 2 content is preferably 12%, more preferably 14%, 15%, 16%, and 17% in that order.
  • the upper limit of the TiO 2 content is preferably 40%, more preferably 35%, 30%, 28%, 26%, 24%, and 23%.
  • TiO 2 greatly contributes to high dispersion. On the other hand, TiO 2 tends to increase the coloring of the glass relatively easily, and may deteriorate the meltability. Therefore, the content of TiO 2 is preferably in the above range.
  • the content of Nb 2 O 5 is 5 to 30%.
  • the lower limit of the content of Nb 2 O 5 is preferably 10%, more preferably 12%, 14%, 16%, 17%, and 18%.
  • the upper limit of the content of Nb 2 O 5 is preferably 28%, more preferably 27%, 26%, and 25%.
  • Nb 2 O 5 is a component that contributes to high refractive index and high dispersion. Therefore, by setting the content of Nb 2 O 5 in the above range, an optical glass having a desired optical constant can be obtained. On the other hand, if the content of Nb 2 O 5 is too large, the coloring of the glass may be strengthened.
  • the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 is 35 to 60%.
  • the lower limit of the total content is preferably 36%, more preferably 37%, 38%, and 39%.
  • the upper limit of the total content is preferably 55%, more preferably 50%, 47%, 45%, and 44%.
  • TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 are components that contribute to high dispersion of glass. Therefore, by setting the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] in the above range, an optical glass having a desired optical constant can be obtained. In addition, the thermal stability of the glass can be improved. On the other hand, if the total content is too large, an optical glass having a desired optical constant may not be obtained, the thermal stability of the glass may be lowered, and the coloring of the glass may be strengthened.
  • the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O
  • the mass ratio of the content of TiO 2 to 5 ] is 0.25 or more.
  • the lower limit of the mass ratio is preferably 0.30, and more preferably 0.32, 0.34, 0.36, 0.38, 0.40 in that order.
  • the upper limit of the mass ratio is preferably 0.65, more preferably 0.60, 0.58, 0.56 in that order.
  • TiO 2 is a component having a particularly large effect of high dispersion. Therefore, from the viewpoint of obtaining a desired optical constant, the mass ratio [TiO 2 / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 )] is preferably in the above range.
  • the mass ratio of the total contents of P 2 O 5 , B 2 O 3 and SiO 2 to the total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [ (P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
  • the upper limit of the mass ratio is preferably 1.75, and more preferably 1.73, 1.72, 1.71, and 1.70.
  • the lower limit of the mass ratio is preferably 1.20, and more preferably 1.30, 1.35, 1.38, and 1.40 in that order.
  • the thermal stability is high and the temperature coefficient of relative refractive index ( An optical glass having a low dn / dT) and a large average coefficient of linear thermal expansion can be obtained.
  • the content of WO 3 is 7% or less.
  • the upper limit of the content of WO 3 is preferably 5%, more preferably 3%, 2%, and 1%.
  • the content of WO 3 is preferably low, and the lower limit thereof is preferably 0%.
  • the content of WO 3 may be 0%.
  • the content of WO 3 is preferably 15% or less, and the upper limit thereof is more preferably 10%, 5%, and 3%.
  • the content of WO 3 is preferably low, and the lower limit thereof is preferably 0%.
  • the content of WO 3 may be 0%.
  • the transmittance can be increased and the increase in the specific gravity of the glass can be suppressed. Further, the temperature coefficient (dn / dT) of the relative refractive index can be lowered.
  • the content of fluorine F is preferably 3% or less, and the upper limit thereof is more preferably 1%, 0.5%, and 0.3%. ..
  • the content of F is preferably small, and the lower limit thereof is preferably 0%.
  • the content of F may be 0%.
  • optical glass according to the second embodiment satisfying the above (B) does not substantially contain fluorine F.
  • Non-limiting examples of the content and ratio of glass components other than the above in the optical glass according to the second embodiment are shown below.
  • the upper limit of the mass ratio is preferably 1.00, more preferably 0.95, 0.90, 0.85, 0.82, 0.80.
  • the lower limit of the mass ratio is more preferably 0.50, and further preferably 0.55, 0.60, 0.62, 0.64.
  • the mass ratio of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 [TiO 2 / (P 2 O 5 + B 2 O 3 )] is 0. It is preferably 70 or less.
  • the upper limit of the mass ratio is preferably 0.68, more preferably 0.67, 0.66, 0.65.
  • the lower limit of the mass ratio is preferably 0.25, more preferably 0.35, 0.40, 0.45 in that order.
  • the mass ratio of the content of B 2 O 3 to the content of P 2 O 5 [B 2 O 3 / P 2 O 5] is preferably at 0.39 or less.
  • the upper limit of the mass ratio is more preferably 0.20, and further preferably 0.15, 0.12, 0.10, 0.08, 0.07, 0.06 in that order.
  • the total content [MgO + CaO + SrO + BaO] of MgO, CaO, SrO and BaO is 8.0% or less.
  • the upper limit of the total content is preferably 6%, more preferably 5%, 4%, and 3%.
  • the lower limit of the total content is preferably 0%.
  • the upper limit of the mass ratio of the content of TiO 2 [TiO 2 / P 2 O 5] to the content of P 2 O 5 is preferably 0.70, more 0 It is more preferable in the order of .68, 0.66, 0.65.
  • the lower limit of the mass ratio is preferably 0.25, more preferably 0.35, 0.40, 0.45 in that order.
  • the upper limit of the content of B 2 O 3 is preferably 10%, more preferably 7%, 5%, 3%, and 2%.
  • the content of B 2 O 3 may be 0%.
  • B 2 O 3 is a network-forming component of glass and has a function of improving the thermal stability of glass.
  • the content of B 2 O 3 is preferably in the above range.
  • the content of Al 2 O 3 is preferably 3% or less, more preferably 2% or less and 1% or less.
  • the content of Al 2 O 3 may be 0%.
  • Al 2 O 3 is a glass component having a function of improving the chemical durability and weather resistance of glass, and can be considered as a network forming component.
  • the content of Al 2 O 3 increases, the devitrification resistance of the glass decreases.
  • problems such as an increase in the glass transition temperature Tg and a decrease in thermal stability are likely to occur.
  • the upper limit of the content of Al 2 O 3 is preferably in the above range.
  • the upper limit of the content of SiO 2 is preferably 5%, more preferably 3%, 2%, and 1%.
  • the content of SiO 2 may be 0%.
  • a quartz glass melting device such as a quartz glass crucible may be used to melt the glass.
  • the glass frit is produced be free of SiO 2 contains a small amount of SiO 2.
  • the amount of SiO 2 mixed into the glass from the quartz glass melting device depends on the melting conditions, but is, for example, about 0.5 to 1% by mass with respect to the total content of all glass components.
  • the amount of SiO 2 increases by about 0.5 to 1% by mass while the content ratio of the glass component other than SiO 2 remains constant. The above amount may increase or decrease depending on the melting conditions. Since the optical characteristics such as the refractive index and the Abbe number change depending on the content of SiO 2, the content of the glass component other than SiO 2 is finely adjusted to obtain an optical glass having desired optical characteristics.
  • SiO 2 is a network-forming component of glass, and has a function of improving thermal stability, chemical durability, and weather resistance of glass, increasing the viscosity of molten glass, and facilitating molding of molten glass.
  • the upper limit of the content of SiO 2 is preferably in the above range.
  • the upper limit of the total content [P 2 O 5 + B 2 O 3 + SiO 2 ] of P 2 O 5 , B 2 O 3 and SiO 2 is preferably 45%, and further. Is more preferable in the order of 42%, 40%, and 38%.
  • the lower limit of the total content is preferably 25%, more preferably 28%, 30%, and 32%.
  • the upper limit of the content of Bi 2 O 3 is preferably 15%, more preferably 10%, 7%, 5%, and 3%.
  • the lower limit of the Bi 2 O 3 content is preferably 0%.
  • Bi 2 O 3 has a function of improving the thermal stability of glass by containing an appropriate amount.
  • the content of Bi 2 O 3 is increased, the coloring of the glass is increased. Therefore, the content of Bi 2 O 3 is preferably in the above range.
  • the upper limit of the content of Ta 2 O 5 is preferably 10%, more preferably 7%, 5%, and 3%.
  • the lower limit of the content of Ta 2 O 5 is preferably 0%.
  • the content of Ta 2 O 5 may be 0%.
  • Ta 2 O 5 is a glass component having a function of improving the thermal stability and devitrification resistance of glass.
  • Ta 2 O 5 increases the refractive index and makes the glass highly dispersed. Further, when the content of Ta 2 O 5 is increased, the thermal stability of the glass is lowered, and when the glass is melted, the unmelted residue of the glass raw material is likely to occur. Therefore, the content of Ta 2 O 5 is preferably in the above range.
  • Ta 2 O 5 is an extremely expensive component as compared with other glass components, and as the content of Ta 2 O 5 increases, the production cost of glass increases. Further, since Ta 2 O 5 has a larger molecular weight than other glass components, it increases the specific gravity of the glass, and as a result, increases the weight of the optical element.
  • the upper limit of the Li 2 O content is preferably 5%, more preferably 3%, 2%, and 1%.
  • the lower limit of the Li 2 O content is preferably 0%.
  • the content of Li 2 O may be 0%.
  • Li 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion.
  • the Li 2 O content is preferably in the above range.
  • the lower limit of the Na 2 O content is preferably 6%, more preferably 10%, 12%, and 13% in that order.
  • the upper limit of the Na 2 O content is preferably 30%, more preferably 22%, 20%, 19%, and 18%.
  • Na 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion.
  • the Na 2 O content is preferably in the above range.
  • the lower limit of the K 2 O content is preferably 1%, more preferably 2%, 3%, and 4%.
  • the upper limit of the content of K 2 O is preferably 13%, further 12%, 11%, preferably by 10% order.
  • K 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the thermal stability of glass. It also has the function of increasing the average coefficient of linear thermal expansion.
  • the content of K 2 O is within the above range.
  • the upper limit of the total content [Li 2 O + Na 2 O + K 2 O] of Li 2 O, Na 2 O and K 2 O is preferably 35%, further 30%. 28%, 26%, and 25% are more preferable in this order.
  • the lower limit of the total content is preferably 10%, more preferably 14%, 18%, 19%, and 20%.
  • Li 2 O, Na 2 O and K 2 O all have a function of improving the thermal stability of glass. However, if these contents are high, the chemical durability and weather resistance may be lowered. Therefore, the total content of Li 2 O, Na 2 O and K 2 O [Li 2 O + Na 2 O + K 2 O] is preferably in the above range.
  • the upper limit of the content of Cs 2 O is preferably 5%, more preferably 3%, 2%, and 1%.
  • the lower limit of the Cs 2 O content is preferably 0%.
  • the content of Cs 2 O may be 0%.
  • Cs 2 O has a function of improving the meltability of glass, but when the content is increased, the thermal stability and refractive index nd of the glass are lowered, and the volatilization of the glass component is increased during melting. The desired glass cannot be obtained. Therefore, the content of Cs 2 O is preferably in the above range.
  • the upper limit of the total content [Li 2 O + Na 2 O + K 2 O + Cs 2 O] of Li 2 O, Na 2 O, K 2 O and Cs 2 O is preferably 35%. Further, 30%, 28%, 26%, and 25% are more preferable in this order.
  • the lower limit of the total content is preferably 10%, more preferably 14%, 18%, 19%, and 20%.
  • Li 2 O, Na 2 O, K 2 O and Cs 2 O all have a function of improving the thermal stability of glass. However, if these contents are high, the chemical durability and weather resistance may be lowered. Therefore, the total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O [Li 2 O + Na 2 O + K 2 O + Cs 2 O] is preferably in the above range.
  • the content of MgO is preferably 5% or less, more preferably 3% or less and 1% or less.
  • the lower limit of the MgO content is preferably 0%.
  • the content of MgO may be 0%.
  • the CaO content is preferably 5% or less, more preferably 3% or less and 1% or less.
  • the lower limit of the CaO content is preferably 0%.
  • the CaO content may be 0%.
  • the SrO content is preferably 6% or less, more preferably 5% or less, 3% or less, and 1% or less.
  • the lower limit of the SrO content is preferably 0%.
  • the BaO content is preferably 8% or less, more preferably 5% or less, 3% or less, and 1% or less.
  • the lower limit of the BaO content is preferably 0%.
  • MgO, CaO, SrO, and BaO are all glass components having a function of improving the thermal stability and devitrification resistance of glass.
  • the content of these glass components is increased, the high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass are lowered. Therefore, the content of each of these glass components is preferably in the above range.
  • the upper limit of the ZnO content is preferably 10%, more preferably 6%, 4%, and 3%.
  • the ZnO content is preferably low, and the lower limit thereof is preferably 0%.
  • the ZnO content may be 0%.
  • ZnO is a glass component having a function of improving the thermal stability of glass.
  • the ZnO content is too high, the specific gravity of the glass increases. Further, the temperature coefficient (dn / dT) of the relative refractive index becomes high. Therefore, the ZnO content is preferably in the above range.
  • the content of ZrO 2 is preferably 5% or less, more preferably 3% or less and 1% or less.
  • the lower limit of the ZrO 2 content is preferably 0%.
  • ZrO 2 is a glass component having a function of improving the thermal stability and devitrification resistance of glass. However, if the content of ZrO 2 is too high, the thermal stability tends to decrease. Therefore, the content of ZrO 2 is preferably in the above range.
  • the upper limit of the content of Sc 2 O 3 is preferably 2%.
  • the lower limit of the Sc 2 O 3 content is preferably 0%.
  • the upper limit of the HfO 2 content is preferably 2%.
  • the lower limit of the HfO 2 content is preferably 0%.
  • Sc 2 O 3 and HfO 2 both have a function of increasing the refractive index nd and are expensive components. Therefore, the contents of Sc 2 O 3 and HfO 2 are preferably in the above range.
  • the upper limit of the content of Lu 2 O 3 is preferably 2%.
  • the lower limit of the content of Lu 2 O 3 is preferably 0%.
  • Lu 2 O 3 has a function of increasing the refractive index nd. In addition, since it has a large molecular weight, it is also a glass component that increases the specific gravity of glass. Therefore, the content of Lu 2 O 3 is preferably in the above range.
  • the upper limit of the content of GeO 2 is preferably 2%.
  • the lower limit of the content of GeO 2 is preferably 0%.
  • GeO 2 has a function of increasing the refractive index nd, and is a prominently expensive component among commonly used glass components. Therefore, from the viewpoint of reducing the manufacturing cost of glass, the content of GeO 2 is preferably in the above range.
  • the upper limit of the content of La 2 O 3 is preferably 2%.
  • the lower limit of the content of La 2 O 3 is preferably 0%.
  • the content of La 2 O 3 may be 0%.
  • the content of La 2 O 3 is preferably in the above range from the viewpoint of suppressing the decrease in thermal stability and devitrification resistance.
  • the upper limit of the content of Gd 2 O 3 is preferably 2%.
  • the lower limit of the content of Gd 2 O 3 is preferably 0%.
  • the content of Gd 2 O 3 is preferably in the above range from the viewpoint of suppressing an increase in specific gravity while maintaining good thermal stability and devitrification resistance of the glass.
  • the upper limit of the content of Y 2 O 3 is preferably 2%.
  • the lower limit of the content of Y 2 O 3 is preferably 0%.
  • the content of Y 2 O 3 may be 0%.
  • the content of Y 2 O 3 is preferably in the range.
  • the upper limit of the content of Yb 2 O 3 is preferably 2%.
  • the lower limit of the content of Yb 2 O 3 is preferably 0%.
  • Yb 2 O 3 Since Yb 2 O 3 has a larger molecular weight than La 2 O 3 , Gd 2 O 3 , and Y 2 O 3 , it increases the specific gravity of glass. As the specific gravity of glass increases, the mass of the optical element increases. For example, if a lens having a large mass is incorporated into an autofocus type imaging lens, the power required to drive the lens during autofocus increases, and the battery consumption increases. Therefore, it is desirable to reduce the content of Yb 2 O 3 to suppress the increase in the specific gravity of the glass.
  • the content of Yb 2 O 3 is preferably in the above range from the viewpoint of preventing a decrease in thermal stability of the glass and suppressing an increase in specific gravity.
  • the optical glass according to the second embodiment mainly contains the above-mentioned glass components, that is, P 2 O 5 , TiO 2 , Nb 2 O 5 as essential components, and WO 3 , B 2 O 3 , Al 2 O 3 , as optional components.
  • SiO 2 , Bi 2 O 3 , Ta 2 O 5 Li 2 O, Na 2 O, K 2 O, Cs 2 O, MgO, CaO, SrO, BaO, ZnO, ZrO 2 , Sc 2 O 3 , HfO 2 , It is preferably composed of Lu 2 O 3 , GeO 2 , La 2 O 3 , Gd 2 O 3 , Y 2 O 3 , and Yb 2 O 3 , and the total content of the above-mentioned glass components is 95% or more. Is preferable, 98% or more is preferable, 99% or more is further preferable, and 99.5% or more is further preferable.
  • the upper limit of the content of TeO 2 is preferably 2%.
  • the lower limit of the content of TeO 2 is preferably 0%.
  • TeO 2 Since TeO 2 is toxic, it is preferable to reduce the content of TeO 2. Therefore, the content of TeO 2 is preferably in the above range.
  • the optical glass according to the second embodiment is basically composed of the above glass components, but it is also possible to contain other components as long as the effects of the present invention are not impaired. Further, in the present invention, the inclusion of unavoidable impurities is not excluded.
  • the optical glass according to the second embodiment does not contain these elements as a glass component.
  • the optical glass according to the second embodiment does not contain these elements as a glass component.
  • Sb (Sb 2 O 3 ) and Ce (CeO 2 ) are arbitrarily addable elements that function as fining agents.
  • Sb (Sb 2 O 3 ) is a fining agent having a large fining effect.
  • Sb (Sb 2 O 3 ) is highly oxidizing, and if the amount of Sb (Sb 2 O 3 ) added is increased, the coloration of the glass increases due to light absorption by Sb ions, which is not preferable. Further, when the glass is melted, if Sb is present in the melt, the elution of platinum constituting the glass melting crucible into the melt is promoted, and the platinum concentration in the glass becomes high.
  • the content of Sb 2 O 3 is indicated by external division. That is, when the total content of all glass components other than Sb 2 O 3 and CeO 2 is 100% by mass, the content of Sb 2 O 3 is preferably less than 1% by mass, more preferably 0.1% by mass. Is less than. Further, is preferably less than 0.05% by mass, less than 0.03% by mass, less than 0.02% by mass, and less than 0.01% in this order.
  • the content of Sb 2 O 3 may be 0% by mass.
  • the content of CeO 2 is also indicated by external division. That is, when the total content of all glass components other than CeO 2 and Sb 2 O 3 is 100% by mass, the content of CeO 2 is preferably less than 2% by mass, more preferably less than 1% by mass, and even more preferably. Is in the range of less than 0.5% by mass, more preferably less than 0.1% by mass.
  • the content of CeO 2 may be 0% by mass.
  • the refractive index nd is preferably 1.63 to 1.80.
  • the lower limit of the refractive index nd may be 1.65, 1.67, 1.69, 1.71 or 1.73, and the upper limit of the refractive index nd may be 1.79, 1.78, or 1.77.
  • the refractive index nd can be set to a desired value by appropriately adjusting the content of each glass component.
  • the components having the function of relatively increasing the refractive index nd are Nb 2 O 5 , TiO 2 , WO 3 , Bi 2 O 3 , Ta 2 O 5 , ZrO 2 , La 2 O 3, etc. Is.
  • the components having a function of relatively lowering the refractive index nd are P 2 O 5 , SiO 2 , B 2 O 3 , Li 2 O, Na 2 O, K 2 O and the like. is there.
  • the Abbe number ⁇ d is preferably 20 to 30.
  • the lower limit of the Abbe number ⁇ d may be 22, 22.5, 23, or 23.2, and the upper limit of the Abbe number ⁇ d may be 28, 26, or 25.
  • the Abbe number ⁇ d can be set to a desired value by appropriately adjusting the content of each glass component.
  • the components that relatively lower the Abbe number ⁇ d, that is, the highly dispersed components, are Nb 2 O 5 , TiO 2 , WO 3 , Bi 2 O 3 , Ta 2 O 5 , ZrO 2, and the like.
  • the components that relatively increase the Abbe number ⁇ d, that is, the low dispersion components are P 2 O 5 , SiO 2 , B 2 O 3 , Li 2 O, Na 2 O, K 2 O, La 2 O 3 , BaO, CaO, SrO and the like.
  • the lower limit of the average coefficient of linear thermal expansion ⁇ at 100 to 300 ° C. is preferably 100 ⁇ 10 -7 ° C -1 , and further 105 ⁇ 10 -7 ° C -1 , 110. ⁇ 10 -7 °C -1, 115 ⁇ 10 -7 °C -1, preferably in the order of 120 ⁇ 10 -7 °C -1.
  • the upper limit of the average coefficient of linear thermal expansion ⁇ is more preferably 200 ⁇ 10 -7 °C -1 , and further 190 ⁇ 10 -7 °C -1 , 180 ⁇ 10 -7 °C -1 , 170 ⁇ 10 ⁇ . 7 ° C -1 , 160 ⁇ 10 -7 ° C -1 , 150 ⁇ 10 -7 ° C -1 , 145 ⁇ 10 -7 ° C -1 are more preferable.
  • the average coefficient of linear expansion ⁇ is measured based on the provisions of JOBIS08-2003. However, the sample shall be a round bar with a length of 20 mm ⁇ 0.5 mm and a diameter of 5 mm ⁇ 0.5 mm, and with a load of 98 mN applied to the sample, it shall be heated so as to rise at a constant rate of 4 ° C. And measure the elongation of the sample.
  • the average coefficient of linear expansion ⁇ is expressed in the unit of [° C -1 ], but the numerical value of the average coefficient of linear expansion ⁇ is the same even when [K -1] is used as the unit.
  • the temperature coefficient dn / dT of the relative refractive index at the wavelength (633 nm) of the He—Ne laser is in the range of 20 to 40 ° C., preferably ⁇ 1.0 ⁇ 10-6 to.
  • the order is ⁇ 3.0 ⁇ 10 -6 to ⁇ 6.5 ⁇ 10 -6 ° C -1.
  • the temperature coefficient dn / dT of the relative refractive index is measured based on the interferometry of JOBIS18-2008.
  • the temperature coefficient dn / dT is expressed in the unit of [° C-1 ], but the numerical value of the temperature coefficient dn / dT is the same even when [K -1] is used as the unit.
  • the glass transition temperature Tg of the optical glass according to the second embodiment is preferably 600 ° C. or lower, more preferably 590 ° C. or lower, 580 ° C. or lower, 570 ° C. or lower, and 560 ° C. or lower.
  • the upper limit of the glass transition temperature Tg satisfies the above range, it is possible to suppress an increase in the glass molding temperature and the annealing temperature, and it is possible to reduce thermal damage to the press molding equipment and the annealing equipment. Further, when the lower limit of the glass transition temperature Tg satisfies the above range, it becomes easy to maintain good thermal stability of the glass while maintaining a desired Abbe number and refractive index.
  • the specific gravity is preferably 3.40 or less, more preferably 3.30 or less, and 3.20 or less. If the specific gravity of the glass can be reduced, the weight of the lens can be reduced. As a result, the power consumption of the autofocus drive of the camera lens on which the lens is mounted can be reduced.
  • the light transmittance of the optical glass according to the second embodiment can be evaluated by the degree of coloring ⁇ 5.
  • the spectral transmittance of a glass sample having a thickness of 10.0 mm ⁇ 0.1 mm is measured in the wavelength range of 200 to 700 nm, and the wavelength at which the external transmittance is 5% is defined as ⁇ 5.
  • the ⁇ 5 of the optical glass according to the second embodiment is preferably 400 nm or less, more preferably 390 nm or less, and further preferably 385 nm or less.
  • the production of the optical glass and the production of the optical element and the like according to the second embodiment can be the same as those of the first embodiment.
  • the optical glass according to the third embodiment will be described in detail.
  • the optical glass according to the third embodiment is The content of P 2 O 5 is 25 to 50%, The Nb 2 O 5 content is 14-40%, The total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 35 to 60%.
  • Mass ratio of TiO 2 content to total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more, P 2 O 5 mass ratio of the content of B 2 O 3 to the content of [B 2 O 3 / P 2 O 5] is 0.05 to 0.39
  • the total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O [Li 2 O + Na 2 O + K 2 O + Cs 2 O] is 10% or more.
  • K 2 O weight ratio of Na 2 O content to the content of [Na 2 O / K 2 O ] is 1.50 or more.
  • the content of P 2 O 5 is 25-50%.
  • the lower limit of the content of P 2 O 5 is preferably 26%, more preferably 26.5% and 26.7 in that order.
  • the upper limit of the content of P 2 O 5 is preferably 42%, more preferably 40%, 38%, 37%, and 36%.
  • P 2 O 5 is a network-forming component of glass, and is an essential component for containing a large amount of highly dispersed components in glass. By setting the content of P 2 O 5 in the above range, an optical glass having high thermal stability and a desired optical constant can be obtained.
  • the content of Nb 2 O 5 is 14 to 40%.
  • the lower limit of the content of Nb 2 O 5 is preferably 16%, more preferably 17%, 18%, 19%, and 20% in that order.
  • the upper limit of the content of Nb 2 O 5 is preferably 38%, more preferably 36%, 34%, and 32% in that order.
  • Nb 2 O 5 is a component that contributes to high refractive index and high dispersion. Therefore, by setting the content of Nb 2 O 5 in the above range, an optical glass having a desired optical constant can be obtained. On the other hand, if the content of Nb 2 O 5 is too large, the coloring of the glass may be strengthened.
  • the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 is 35 to 60%.
  • the lower limit of the total content is preferably 36%, more preferably 37%, 38%, and 39%.
  • the upper limit of the total content is preferably 55%, more preferably 50%, 48%, 47%, and 46%.
  • TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 are components that contribute to high dispersion of glass. Therefore, by setting the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] in the above range, an optical glass having a desired optical constant can be obtained. In addition, the thermal stability of the glass can be improved. On the other hand, if the total content is too large, an optical glass having a desired optical constant may not be obtained, the thermal stability of the glass may be lowered, and the coloring of the glass may be strengthened.
  • the mass ratio of the content of TiO 2 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 is 0.25 or more.
  • the lower limit of the mass ratio is preferably 0.26, more preferably 0.27, 0.28, 0.29, 0.30 in that order.
  • the upper limit of the mass ratio is preferably 0.65, and more preferably 0.60, 0.58, 0.56, 0.54, 0.52, 0.50, 0.48. ..
  • TiO 2 is a component having a particularly large effect of high dispersion. Therefore, from the viewpoint of obtaining a desired optical constant, the mass ratio [TiO 2 / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 )] is preferably in the above range.
  • the mass ratio of the content of B 2 O 3 to the content of P 2 O 5 [B 2 O 3 / P 2 O 5] is 0.05 to 0.39.
  • the upper limit of the mass ratio is preferably 0.30, and more preferably 0.25, 0.22, 0.20, 0.19, and 0.18.
  • the lower limit of the mass ratio is preferably 0.06, and more preferably 0.07, 0.08, and 0.09.
  • the total content [Li 2 O + Na 2 O + K 2 O + Cs 2 O] of Li 2 O, Na 2 O, K 2 O and Cs 2 O is 10% or more.
  • the lower limit of the total content is preferably 12%, more preferably 14%, 16%, and 17% in that order.
  • the upper limit of the total content is preferably 35%, more preferably 30%, 28%, 26%, and 25%.
  • Li 2 O, Na 2 O, K 2 O and Cs 2 O all have a function of improving the thermal stability of glass. However, if these contents are high, the chemical durability and weather resistance may be lowered. Therefore, the total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O [Li 2 O + Na 2 O + K 2 O + Cs 2 O] is preferably in the above range.
  • K 2 O weight ratio of Na 2 O content to the content of [Na 2 O / K 2 O ] is 1.50 or more.
  • the lower limit of the mass ratio is preferably 1.70, more preferably 1.90, 2.10 and 2.30 in that order.
  • the upper limit of the mass ratio is preferably 10.0, and more preferably 8.50, 7.50, 7.00, and 6.50.
  • Na 2 O and K 2 O are components that contribute to lowering the specific gravity of glass, and have a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion.
  • the mass ratio [Na 2 O / K 2 O] is preferably in the above range.
  • Non-limiting examples of the content and ratio of glass components other than the above in the optical glass according to the third embodiment are shown below.
  • the upper limit of the content of B 2 O 3 is preferably 10%, more preferably 9%, 8%, 7%, and 6%.
  • B 2 O 3 is a network-forming component of glass and has a function of improving the thermal stability of glass.
  • the content of B 2 O 3 is preferably in the above range.
  • P 2 O 5 and B 2 O total mass ratio of the content of B 2 O 3 to the content of 3 [B 2 O 3 / ( P 2 O 5 + B 2 O 3) ] Is preferably 0.18, more preferably 0.17, 0.16, 0.15 in that order.
  • the lower limit of the mass ratio is preferably 0, more preferably 0.01, 0.03, 0.05.
  • the mass ratio [B 2 O 3 / (P 2 O 5 + B 2 O 3 )] is preferably in the above range.
  • the content of Al 2 O 3 is preferably 3% or less, more preferably 2% or less and 1% or less.
  • the content of Al 2 O 3 may be 0%.
  • Al 2 O 3 is a glass component having a function of improving the chemical durability and weather resistance of glass, and can be considered as a network forming component.
  • the content of Al 2 O 3 increases, the devitrification resistance of the glass decreases.
  • problems such as an increase in the glass transition temperature Tg and a decrease in thermal stability are likely to occur.
  • the upper limit of the content of Al 2 O 3 is preferably in the above range.
  • the upper limit of the content of SiO 2 is preferably 5%, more preferably 3%, 2%, and 1%.
  • the content of SiO 2 may be 0%.
  • a quartz glass melting device such as a quartz glass crucible may be used to melt the glass.
  • the glass frit is produced be free of SiO 2 contains a small amount of SiO 2.
  • the amount of SiO 2 mixed into the glass from the quartz glass melting device depends on the melting conditions, but is, for example, about 0.5 to 1% by mass with respect to the total content of all glass components.
  • the amount of SiO 2 increases by about 0.5 to 1% by mass while the content ratio of the glass component other than SiO 2 remains constant. The above amount may increase or decrease depending on the melting conditions. Since the optical characteristics such as the refractive index and the Abbe number change depending on the content of SiO 2, the content of the glass component other than SiO 2 is finely adjusted to obtain an optical glass having desired optical characteristics.
  • SiO 2 is a network-forming component of glass, and has a function of improving thermal stability, chemical durability, and weather resistance of glass, increasing the viscosity of molten glass, and facilitating molding of molten glass.
  • the upper limit of the content of SiO 2 is preferably in the above range.
  • the upper limit of the total content [P 2 O 5 + B 2 O 3 + SiO 2 ] of P 2 O 5 , B 2 O 3 and SiO 2 is preferably 50%, and further. Is more preferred in the order of 45%, 43%, 42%, 41%.
  • the lower limit of the total content is preferably 25%, more preferably 27%, 28%, and 29%.
  • the mass ratio of the total content of P 2 O 5 and B 2 O 3 to the total content of P 2 O 5 , B 2 O 3 , SiO 2 , and Al 2 O 3 [
  • the lower limit of (P 2 O 5 + B 2 O 3 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3 )] is preferably 0.80, and further 0.90, 0.93, It is more preferable in the order of 0.96 and 0.98.
  • the upper limit of the mass ratio is preferably 1.00.
  • the mass ratio may be 1.00.
  • the mass ratio [(P 2 O 5 + B 2 O 3 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3 )) ] Is preferably in the above range.
  • the lower limit of the TiO 2 content is preferably 10%, more preferably 11%, 12%, and 13% in that order.
  • the upper limit of the TiO 2 content is preferably 50%, more preferably 40%, 35%, 30%, 28%, 26%, 23%, and 21%.
  • TiO 2 greatly contributes to high dispersion. On the other hand, TiO 2 tends to increase the coloring of the glass relatively easily, and may deteriorate the meltability. Therefore, the content of TiO 2 is preferably in the above range.
  • the upper limit of the content of WO 3 is preferably 15%, more preferably 10%, 5%, 3%, 2%, and 1%.
  • the content of WO 3 is preferably low, and the lower limit thereof is preferably 0%.
  • the content of WO 3 may be 0%.
  • the transmittance can be increased and the increase in the specific gravity of the glass can be suppressed. Further, the temperature coefficient (dn / dT) of the relative refractive index can be lowered.
  • the upper limit of the content of Bi 2 O 3 is preferably 15%, more preferably 10%, 7%, 5%, and 3%.
  • the lower limit of the Bi 2 O 3 content is preferably 0%.
  • Bi 2 O 3 has a function of improving the thermal stability of glass by containing an appropriate amount.
  • the content of Bi 2 O 3 is increased, the coloring of the glass is increased. Therefore, the content of Bi 2 O 3 is preferably in the above range.
  • the upper limit of the mass ratio [TiO 2 / (P 2 O 5 + B 2 O 3 )] of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 is , Preferably 0.70, and more preferably 0.66, 0.64, 0.62, 0.60.
  • the lower limit of the mass ratio is preferably 0.25, more preferably 0.27, 0.29, 0.31 in that order.
  • the upper limit of the mass ratio of the content of TiO 2 [TiO 2 / P 2 O 5] to the content of P 2 O 5 is preferably 0.70, more 0 It is more preferable in the order of .66, 0.64, 0.62.
  • the lower limit of the mass ratio is preferably 0.25, more preferably 0.28, 0.31 and 0.34.
  • the lower limit of the total content [TiO 2 + Nb 2 O 5 ] of TiO 2 and Nb 2 O 5 is preferably 35.0%, and further 37.0% and 39. It is more preferable in the order of 0.0% and 40.0%.
  • the upper limit of the total content is preferably 65.0%, more preferably 60.0%, 55.0%, 50.0%, 48.0%, and 46.0%.
  • the total content [TiO 2 + Nb 2 O 5 ] is preferably in the above range.
  • the lower limit of the mass ratio of the content of Nb 2 O 5 to the total content of Nb 2 O 5 and WO 3 is , It is preferably 0.70, and more preferably 0.80, 0.90, 0.95 in that order.
  • the upper limit of the mass ratio is preferably 1.00.
  • the mass ratio may be 1.00.
  • the mass ratio [Nb 2 O 5 / (Nb 2 O 5 + WO 3 )] is It is preferably in the above range.
  • the lower limit of the mass ratio of the content of TiO 2 to the total content of TiO 2 and WO 3 is preferably 0.70. Further, it is more preferable in the order of 0.80, 0.90, 0.95.
  • the upper limit of the mass ratio is preferably 1.00. The mass ratio may be 1.00.
  • the mass ratio [TiO 2 / (TiO 2 + WO 3 )] is preferably in the above range. ..
  • the mass ratio of the total content of TiO 2 and Nb 2 O 5 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , and Bi 2 O 3 [(TiO 2 + Nb).
  • the lower limit of 2 O 5 ) / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 )] is preferably 0.70, and more preferably 0.80, 0.90, and 0.95.
  • the upper limit of the mass ratio is preferably 1.00.
  • the mass ratio may be 1.00.
  • the mass ratio [(TiO 2 + Nb 2 O 5 ) / (TiO 2 + Nb 2 O) 5 + WO 3 + Bi 2 O 3 )] is preferably in the above range.
  • the upper limit of the content of Ta 2 O 5 is preferably 10%, more preferably 7%, 5%, and 3%.
  • the lower limit of the content of Ta 2 O 5 is preferably 0%.
  • the content of Ta 2 O 5 may be 0%.
  • Ta 2 O 5 is a glass component having a function of improving the thermal stability and devitrification resistance of glass.
  • Ta 2 O 5 increases the refractive index and makes the glass highly dispersed. Further, when the content of Ta 2 O 5 is increased, the thermal stability of the glass is lowered, and when the glass is melted, the unmelted residue of the glass raw material is likely to occur. Therefore, the content of Ta 2 O 5 is preferably in the above range.
  • Ta 2 O 5 is an extremely expensive component as compared with other glass components, and as the content of Ta 2 O 5 increases, the production cost of glass increases. Further, since Ta 2 O 5 has a larger molecular weight than other glass components, it increases the specific gravity of the glass, and as a result, increases the weight of the optical element.
  • the upper limit of the Li 2 O content is preferably 5%, more preferably 3%, 2%, and 1%.
  • the lower limit of the Li 2 O content is preferably 0%.
  • the content of Li 2 O may be 0%.
  • Li 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion.
  • the Li 2 O content is preferably in the above range.
  • the lower limit of the Na 2 O content is preferably 6%, more preferably 10%, 12%, and 13% in that order.
  • the upper limit of the Na 2 O content is preferably 30%, more preferably 22%, 20%, 19%, and 18%.
  • Na 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion.
  • the Na 2 O content is preferably in the above range.
  • the lower limit of K 2 O content is preferably 1%, even 2%, 3%, preferably by 4% order.
  • the upper limit of the content of K 2 O is preferably 13%, further 12%, 11%, preferably by 10% order.
  • K 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the thermal stability of glass. It also has the function of increasing the average coefficient of linear thermal expansion. On the other hand, when the K 2 O content increases, the thermal stability, devitrification resistance, chemical durability, weather resistance decreases. Therefore, it is preferable that the content of K 2 O is within the above range.
  • the upper limit of the total content [Li 2 O + Na 2 O + K 2 O] of Li 2 O, Na 2 O and K 2 O is preferably 35%, further 30%. 28%, 26%, and 25% are more preferable in this order.
  • the lower limit of the total content is preferably 10%, more preferably 14%, 15%, 16%, and 17%.
  • Li 2 O, Na 2 O and K 2 O all have a function of improving the thermal stability of glass. However, if these contents are high, the chemical durability and weather resistance may be lowered. Therefore, the total content of Li 2 O, Na 2 O and K 2 O [Li 2 O + Na 2 O + K 2 O] is preferably in the above range.
  • the upper limit of the content of Cs 2 O is preferably 5%, more preferably 3%, 2%, and 1%.
  • the lower limit of the Cs 2 O content is preferably 0%.
  • the content of Cs 2 O may be 0%.
  • Cs 2 O has a function of improving the meltability of glass, but when the content is increased, the thermal stability and refractive index nd of the glass are lowered, and the volatilization of the glass component is increased during melting. The desired glass cannot be obtained. Therefore, the content of Cs 2 O is preferably in the above range.
  • the mass ratio of the content of Na 2 O to the total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O [Na 2 O / (Li 2 O + Na 2 O + K).
  • the lower limit of 2 O + Cs 2 O)] is preferably 0.20, more preferably 0.50, 0.55, 0.60, 0.65.
  • the upper limit of the mass ratio is preferably 0.98, more preferably 0.95, 0.92, 0.90, 0.88.
  • the mass ratio [Na 2 O / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is preferably in the above range.
  • the mass ratio of the total contents of P 2 O 5 , B 2 O 3 and SiO 2 to the total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [
  • the upper limit of (P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is preferably 2.50, and further 2.40, 2.35, 2.30. It is more preferable in the order of 2.27 and 2.25.
  • the lower limit of the mass ratio is preferably 1.20, and more preferably 1.30, 1.35, 1.38, and 1.40 in that order.
  • the thermal stability is high and the temperature coefficient of relative refractive index ( An optical glass having a low dn / dT) and a large average coefficient of linear thermal expansion can be obtained.
  • the content of MgO is preferably 5% or less, more preferably 3% or less and 1% or less.
  • the lower limit of the MgO content is preferably 0%.
  • the content of MgO may be 0%.
  • the CaO content is preferably 5% or less, more preferably 3% or less and 1% or less.
  • the lower limit of the CaO content is preferably 0%.
  • the CaO content may be 0%.
  • the SrO content is preferably 6% or less, more preferably 5% or less, 3% or less, and 1% or less.
  • the lower limit of the SrO content is preferably 0%.
  • the BaO content is preferably 8% or less, more preferably 5% or less, 3% or less, and 1% or less.
  • the lower limit of the BaO content is preferably 0%.
  • the upper limit of the total content [MgO + CaO + SrO + BaO] of MgO, CaO, SrO, and BaO is preferably 8.0%, and further 5.0% and 4.0%. , 3.0%, 1.5%, 1.0%, 0.5% in that order.
  • the lower limit of the total content is preferably 0%.
  • the total content may be 0%.
  • MgO, CaO, SrO, and BaO are all glass components having a function of improving the thermal stability and devitrification resistance of glass.
  • the content of these glass components is increased, the high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass are lowered.
  • the BaO content is too large, the specific gravity of the glass increases. Therefore, each content and total content of these glass components are preferably in the above range.
  • the upper limit of the ZnO content is preferably 10%, more preferably 6%, 4%, and 3%.
  • the ZnO content is preferably low, and the lower limit thereof is preferably 0%.
  • the ZnO content may be 0%.
  • ZnO is a glass component having a function of improving the thermal stability of glass.
  • the ZnO content is too high, the specific gravity of the glass increases. Further, the temperature coefficient (dn / dT) of the relative refractive index becomes high. Therefore, the ZnO content is preferably in the above range.
  • the lower limit of the mass ratio [Na 2 O / (Na 2 O + Zn O)] of the content of Na 2 O to the total content of Na 2 O and Zn O is preferably 0.50. Yes, more preferably in the order of 0.60, 0.70, 0.90.
  • the upper limit of the mass ratio is preferably 1.00.
  • the mass ratio may be 1.00.
  • the mass ratio [Na 2 O / (Na 2 O + Zn O)] is in the above range from the viewpoint of suppressing an increase in the specific gravity of the glass and suppressing an increase in the temperature coefficient (dn / dT) of the relative refractive index. Is preferable.
  • the lower limit of the mass ratio [TiO 2 / (TiO 2 + ZnO)] of the content of TiO 2 to the total content of TiO 2 and ZnO is preferably 0.70, and further. Is more preferable in the order of 0.80, 0.90, 0.95.
  • the upper limit of the mass ratio is preferably 1.00.
  • the mass ratio may be 1.00.
  • the mass ratio [TiO 2 / (TiO 2 + ZnO)] is preferably in the above range.
  • the mass ratio of the total content of TiO 2 and Nb 2 O 5 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Zn O [(TIO 2).
  • the lower limit of [+ Nb 2 O 5 ) / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + ZnO)] is preferably 0.70, and further in the order of 0.80, 0.90, 0.95. preferable.
  • the upper limit of the mass ratio is preferably 1.00.
  • the mass ratio may be 1.00.
  • the mass ratio [(TiO 2 + Nb 2 O 5 ) / (TiO 2 + Nb 2 O) 5 + WO 3 + Bi 2 O 3 + ZnO)] is preferably in the above range.
  • the upper limit of the mass ratio is preferably 1.00, more preferably 0.95, 0.90, 0.85, 0.82, 0.80.
  • the lower limit of the mass ratio is more preferably 0.50, and further preferably 0.60, 0.65, 0.68, 0.70 in that order.
  • the content of ZrO 2 is preferably 5% or less, more preferably 3% or less and 1% or less.
  • the lower limit of the ZrO 2 content is preferably 0%.
  • ZrO 2 is a glass component having a function of improving the thermal stability and devitrification resistance of glass. However, if the content of ZrO 2 is too high, the thermal stability tends to decrease. Therefore, the content of ZrO 2 is preferably in the above range.
  • the upper limit of the Sc 2 O 3 content is preferably 2%.
  • the lower limit of the Sc 2 O 3 content is preferably 0%.
  • the upper limit of the HfO 2 content is preferably 2%.
  • the lower limit of the HfO 2 content is preferably 0%.
  • Sc 2 O 3 and HfO 2 both have a function of increasing the refractive index nd and are expensive components. Therefore, the contents of Sc 2 O 3 and HfO 2 are preferably in the above range.
  • the upper limit of the content of Lu 2 O 3 is preferably 2%.
  • the lower limit of the content of Lu 2 O 3 is preferably 0%.
  • Lu 2 O 3 has a function of increasing the refractive index nd. In addition, since it has a large molecular weight, it is also a glass component that increases the specific gravity of glass. Therefore, the content of Lu 2 O 3 is preferably in the above range.
  • the upper limit of the content of GeO 2 is preferably 2%.
  • the lower limit of the content of GeO 2 is preferably 0%.
  • GeO 2 has a function of increasing the refractive index nd, and is a prominently expensive component among commonly used glass components. Therefore, from the viewpoint of reducing the manufacturing cost of glass, the content of GeO 2 is preferably in the above range.
  • the upper limit of the content of La 2 O 3 is preferably 2%.
  • the lower limit of the content of La 2 O 3 is preferably 0%.
  • the content of La 2 O 3 may be 0%.
  • the content of La 2 O 3 is preferably in the above range from the viewpoint of suppressing the decrease in thermal stability and devitrification resistance.
  • the upper limit of the content of Gd 2 O 3 is preferably 2%.
  • the lower limit of the content of Gd 2 O 3 is preferably 0%.
  • the content of Gd 2 O 3 is preferably in the above range from the viewpoint of suppressing an increase in specific gravity while maintaining good thermal stability and devitrification resistance of the glass.
  • the upper limit of the content of Y 2 O 3 is preferably 2%.
  • the lower limit of the content of Y 2 O 3 is preferably 0%.
  • the content of Y 2 O 3 may be 0%.
  • the content of Y 2 O 3 is preferably in the range.
  • the upper limit of the content of Yb 2 O 3 is preferably 2%.
  • the lower limit of the content of Yb 2 O 3 is preferably 0%.
  • Yb 2 O 3 Since Yb 2 O 3 has a larger molecular weight than La 2 O 3 , Gd 2 O 3 , and Y 2 O 3 , it increases the specific gravity of glass. As the specific gravity of glass increases, the mass of the optical element increases. For example, if a lens having a large mass is incorporated into an autofocus type imaging lens, the power required to drive the lens during autofocus increases, and the battery consumption increases. Therefore, it is desirable to reduce the content of Yb 2 O 3 to suppress the increase in the specific gravity of the glass.
  • the content of Yb 2 O 3 is preferably in the above range from the viewpoint of preventing a decrease in thermal stability of the glass and suppressing an increase in specific gravity.
  • the optical glass according to the third embodiment mainly contains the above-mentioned glass components, that is, P 2 O 5 , Nb 2 O 5 , B 2 O 3 , TiO 2 , Na 2 O, K 2 O as essential components, and optional components.
  • the upper limit of the content of TeO 2 is preferably 2%.
  • the lower limit of the content of TeO 2 is preferably 0%.
  • TeO 2 Since TeO 2 is toxic, it is preferable to reduce the content of TeO 2. Therefore, the content of TeO 2 is preferably in the above range.
  • the content of fluorine F is preferably 3% or less, and the upper limit thereof is more preferably 1%, 0.5%, and 0.3%.
  • the content of F is preferably small, and the lower limit thereof is preferably 0%.
  • the content of F may be 0%. Also, preferably, it does not substantially contain fluorine F.
  • the optical glass according to the third embodiment is basically composed of the above glass components, but other components may be contained as long as the effects of the present invention are not impaired. Further, in the present invention, the inclusion of unavoidable impurities is not excluded.
  • the optical glass according to the third embodiment does not contain these elements as a glass component.
  • the optical glass according to the third embodiment does not contain these elements as a glass component.
  • the optical glass according to the third embodiment does not contain these elements as a glass component.
  • Sb (Sb 2 O 3 ) and Ce (CeO 2 ) are arbitrarily addable elements that function as fining agents.
  • Sb (Sb 2 O 3 ) is a fining agent having a large fining effect.
  • Sb (Sb 2 O 3 ) is highly oxidizing, and if the amount of Sb (Sb 2 O 3 ) added is increased, the coloration of the glass increases due to light absorption by Sb ions, which is not preferable. Further, when the glass is melted, if Sb is present in the melt, the elution of platinum constituting the glass melting crucible into the melt is promoted, and the platinum concentration in the glass becomes high.
  • the content of Sb 2 O 3 is indicated by external division. That is, when the total content of all glass components other than Sb 2 O 3 and CeO 2 is 100% by mass, the content of Sb 2 O 3 is preferably less than 1% by mass, more preferably 0.1% by mass. Is less than. Further, is preferably less than 0.05% by mass, less than 0.03% by mass, less than 0.02% by mass, and less than 0.01% in this order.
  • the content of Sb 2 O 3 may be 0% by mass.
  • the content of CeO 2 is also indicated by external division. That is, when the total content of all glass components other than CeO 2 and Sb 2 O 3 is 100% by mass, the content of CeO 2 is preferably less than 2% by mass, more preferably less than 1% by mass, and even more preferably. Is in the range of less than 0.5% by mass, more preferably less than 0.1% by mass.
  • the content of CeO 2 may be 0% by mass.
  • the refractive index nd is preferably 1.63 to 1.80.
  • the lower limit of the refractive index nd may be 1.65, 1.67, 1.69, 1.71 or 1.73, and the upper limit of the refractive index nd may be 1.79, 1.78, or 1.77.
  • the refractive index nd can be set to a desired value by appropriately adjusting the content of each glass component.
  • the components having the function of relatively increasing the refractive index nd are Nb 2 O 5 , TiO 2 , WO 3 , Bi 2 O 3 , Ta 2 O 5 , ZrO 2 , La 2 O 3, etc. Is.
  • the components having a function of relatively lowering the refractive index nd are P 2 O 5 , SiO 2 , B 2 O 3 , Li 2 O, Na 2 O, K 2 O and the like. is there.
  • the Abbe number ⁇ d is preferably 20 to 30.
  • the lower limit of the Abbe number ⁇ d may be 22, 22.5, 23, or 23.2, and the upper limit of the Abbe number ⁇ d may be 28, 26, or 25.
  • the Abbe number ⁇ d can be set to a desired value by appropriately adjusting the content of each glass component.
  • the components that relatively lower the Abbe number ⁇ d, that is, the highly dispersed components, are Nb 2 O 5 , TiO 2 , WO 3 , Bi 2 O 3 , Ta 2 O 5 , ZrO 2, and the like.
  • the components that relatively increase the Abbe number ⁇ d, that is, the low dispersion components are P 2 O 5 , SiO 2 , B 2 O 3 , Li 2 O, Na 2 O, K 2 O, La 2 O 3 , BaO, CaO, SrO and the like.
  • the lower limit of the average coefficient of linear thermal expansion ⁇ at 100 to 300 ° C. is preferably 100 ⁇ 10 -7 ° C -1 , and further 102 ⁇ 10 -7 ° C -1 , 104. It is more preferable in the order of ⁇ 10 -7 ° C -1 , 106 ⁇ 10 -7 ° C -1 , and 108 ⁇ 10 -7 ° C -1.
  • the upper limit of the average coefficient of linear thermal expansion ⁇ is more preferably 200 ⁇ 10 -7 °C -1 , and further 190 ⁇ 10 -7 °C -1 , 180 ⁇ 10 -7 °C -1 , 170 ⁇ 10 ⁇ . 7 ° C -1 , 160 ⁇ 10 -7 ° C -1 , 150 ⁇ 10 -7 ° C -1 , 145 ⁇ 10 -7 ° C -1 are more preferable.
  • the average coefficient of linear expansion ⁇ is measured based on the provisions of JOBIS08-2003. However, the sample shall be a round bar with a length of 20 mm ⁇ 0.5 mm and a diameter of 5 mm ⁇ 0.5 mm, and with a load of 98 mN applied to the sample, it shall be heated so as to rise at a constant rate of 4 ° C. And measure the elongation of the sample.
  • the average coefficient of linear expansion ⁇ is expressed in the unit of [° C -1 ], but the numerical value of the average coefficient of linear expansion ⁇ is the same even when [K -1] is used as the unit.
  • the temperature coefficient dn / dT of the relative refractive index at the wavelength (633 nm) of the He—Ne laser is in the range of 20 to 40 ° C., preferably ⁇ 1.0 ⁇ 10-6 to.
  • the temperature coefficient dn / dT of the relative refractive index is measured based on the interferometry of JOBIS18-2008.
  • the temperature coefficient dn / dT is expressed in the unit of [° C-1 ], but the numerical value of the temperature coefficient dn / dT is the same even when [K -1] is used as the unit.
  • the glass transition temperature Tg of the optical glass according to the third embodiment is preferably 600 ° C. or lower, more preferably 590 ° C. or lower, 580 ° C. or lower, 570 ° C. or lower, and 560 ° C. or lower.
  • the upper limit of the glass transition temperature Tg satisfies the above range, it is possible to suppress an increase in the glass molding temperature and the annealing temperature, and it is possible to reduce thermal damage to the press molding equipment and the annealing equipment. Further, when the lower limit of the glass transition temperature Tg satisfies the above range, it becomes easy to maintain good thermal stability of the glass while maintaining a desired Abbe number and refractive index.
  • the specific gravity is preferably 3.40 or less, and more preferably 3.30 or less and 3.20 or less. If the specific gravity of the glass can be reduced, the weight of the lens can be reduced. As a result, the power consumption of the autofocus drive of the camera lens on which the lens is mounted can be reduced.
  • the light transmittance of the optical glass according to the third embodiment can be evaluated by the degree of coloring ⁇ 5.
  • the spectral transmittance of a glass sample having a thickness of 10.0 mm ⁇ 0.1 mm is measured in the wavelength range of 200 to 700 nm, and the wavelength at which the external transmittance is 5% is defined as ⁇ 5.
  • the ⁇ 5 of the optical glass according to the third embodiment is preferably 400 nm or less, more preferably 390 nm or less, and further preferably 385 nm or less.
  • the production of the optical glass and the production of the optical element and the like according to the third embodiment can be the same as those of the first embodiment.
  • Examples 1-1 and 1-2 correspond to the first embodiment
  • Examples 2-1 and 2-2 correspond to the second embodiment
  • Examples 3-1 and 3-2 correspond to the third embodiment. Corresponds to the embodiment.
  • Example 1-1 [Preparation of glass sample] The sample numbers shown in Tables 1-1 to 1-6.
  • Compound raw materials corresponding to each component that is, raw materials such as phosphates, carbonates, and oxides, were weighed and sufficiently mixed to prepare a compounding raw material so as to form a glass having a composition of 1 to 52.
  • the compounding raw material was put into a platinum crucible, heated to 900 to 1350 ° C. in an atmospheric atmosphere to melt, homogenized and clarified by stirring to obtain molten glass.
  • the molten glass was cast into a molding die, molded, and slowly cooled to obtain a block-shaped glass sample.
  • the compounding raw material is put into a quartz glass crucible, melted, then transferred to a platinum crucible, further heated to melt, homogenized by stirring, and clarified, and the obtained molten glass is cast into a molding die and molded. , May be slowly cooled.
  • the glass sample was processed so as to have a plane having a thickness of 10 mm, parallel to each other and optically polished, and the spectral transmittance in the wavelength range from 280 nm to 700 nm was measured.
  • the spectral transmittance B / A was calculated with the intensity of the light beam perpendicularly incident on one plane optically polished as the intensity A and the intensity of the light beam emitted from the other plane as the intensity B.
  • the wavelength at which the spectral transmittance is 5% was defined as ⁇ 5.
  • the spectral transmittance also includes the reflection loss of light rays on the sample surface.
  • Glass transition temperature Tg The glass transition temperature Tg was measured at a heating rate of 10 ° C./min using a differential scanning calorimetry device (DSC3300SA) manufactured by NETZSCH JAPAN.
  • Example 1-2 The glass sample obtained in Example 1 was cut and ground to prepare a cut piece. The cut piece was press-molded by a reheat press to prepare an optical element blank. The optical element blank is precisely annealed, the refractive index is precisely adjusted to the required refractive index, and then ground and polished by a known method to obtain a biconvex lens, a biconcave lens, a plano-convex lens, a plano-concave lens, and a concave meniscus lens. , Various lenses such as convex meniscus lenses were obtained.
  • Example 2-1 [Preparation of glass sample] Sample No. shown in Table 2-1.
  • Compound raw materials corresponding to each component that is, raw materials such as phosphates, carbonates, and oxides, are weighed and sufficiently mixed with the compounding raw materials so as to form a glass having a composition of 2-1 to 2-8. did.
  • the compounding raw material was put into a platinum crucible, heated to 900 to 1350 ° C. in an atmospheric atmosphere to melt, homogenized and clarified by stirring to obtain molten glass.
  • the molten glass was cast into a molding die, molded, and slowly cooled to obtain a block-shaped glass sample.
  • the compounding raw material is put into a quartz glass crucible, melted, then transferred to a platinum crucible, further heated to melt, homogenized by stirring, and clarified, and the obtained molten glass is cast into a molding die and molded. , May be slowly cooled.
  • the glass sample was processed so as to have a plane having a thickness of 10 mm, parallel to each other and optically polished, and the spectral transmittance in the wavelength range from 280 nm to 700 nm was measured.
  • the spectral transmittance B / A was calculated with the intensity of the light beam perpendicularly incident on one plane optically polished as the intensity A and the intensity of the light beam emitted from the other plane as the intensity B.
  • the wavelength at which the spectral transmittance is 5% was defined as ⁇ 5.
  • the spectral transmittance also includes the reflection loss of light rays on the sample surface.
  • Glass transition temperature Tg The glass transition temperature Tg was measured at a heating rate of 10 ° C./min using a differential scanning calorimetry device (DSC3300SA) manufactured by NETZSCH JAPAN.
  • Example 2-2 The glass sample obtained in Example 2-1 was cut and ground to prepare a cut piece. The cut piece was press-molded by a reheat press to prepare an optical element blank. The optical element blank is precisely annealed, the refractive index is precisely adjusted to the required refractive index, and then ground and polished by a known method to obtain a biconvex lens, a biconcave lens, a plano-convex lens, a plano-concave lens, and a concave meniscus lens. , Various lenses such as convex meniscus lenses were obtained.
  • Example 3-1 [Preparation of glass sample] Sample No. shown in Table 3-1.
  • Compound raw materials corresponding to each component that is, raw materials such as phosphates, carbonates, and oxides, are weighed and sufficiently mixed to prepare a mixed raw material so as to form a glass having a composition of 3-1 to 3-8. did.
  • the compounding raw material was put into a platinum crucible, heated to 900 to 1350 ° C. in an atmospheric atmosphere to melt, homogenized and clarified by stirring to obtain molten glass.
  • the molten glass was cast into a molding die, molded, and slowly cooled to obtain a block-shaped glass sample.
  • the compounding raw material is put into a quartz glass crucible, melted, then transferred to a platinum crucible, further heated to melt, homogenized by stirring, and clarified, and the obtained molten glass is cast into a molding die and molded. , May be slowly cooled.
  • the glass sample was processed so as to have a plane having a thickness of 10 mm, parallel to each other and optically polished, and the spectral transmittance in the wavelength range from 280 nm to 700 nm was measured.
  • the spectral transmittance B / A was calculated with the intensity of the light beam perpendicularly incident on one plane optically polished as the intensity A and the intensity of the light beam emitted from the other plane as the intensity B.
  • the wavelength at which the spectral transmittance is 5% was defined as ⁇ 5.
  • the spectral transmittance also includes the reflection loss of light rays on the sample surface.
  • Example 3-2 The glass sample obtained in Example 3-1 was cut and ground to prepare a cut piece.
  • the cut piece was press-molded by a reheat press to prepare an optical element blank.
  • the optical element blank is precisely annealed, the refractive index is precisely adjusted to the required refractive index, and then ground and polished by a known method to obtain a biconvex lens, a biconcave lens, a plano-convex lens, a plano-concave lens, and a concave meniscus lens.
  • Various lenses such as convex meniscus lenses were obtained.
  • the optical glass according to one aspect of the present invention can be produced by adjusting the composition described in the specification with respect to the glass composition exemplified above.

Abstract

[Problem] To provide an optical glass having a low temperature coefficient of the relative refractive index (dn/dT) thereof due to temperature change and a large average linear thermal expansion coefficient, and an optical element that comprises the optical glass. [Solution] An optical glass having a refractive index nd of 1.63-1.80, an Abbe number νd of 22-34, a Nb2O5 content of 25-55 mass%, a WO3 content of less than 30 mass%, a total content [TiO2 + Nb2O5 + WO3 + Bi2O3 + Ta2O5] of TiO2, Nb2O5, WO3, Bi2O3, and Ta2O5 of 36-60 mass%, a mass ratio [(TiO2 + Nb2O5 + WO3 + Bi2O3 + Ta2O5)/(P2O5 + B2O3 + SiO2 + Al2O3 + Li2O + Na2P + K2O + Cs2O)] of the total content of TiO2, Nb2O5, WO3, Bi2O3, and Ta2O5 to the total content of P2O5, B2O3, SiO2, Al2O3, Li2O, Na2O, K2O, and Cs2O of 1.10 or less, and a mass ratio [TiO2/(P2O5 + B2O3)] of the content of TiO2 to the total content of P2O5 and B2O3 of 0.50 or less, and satisfying (A) or (B).

Description

光学ガラスおよび光学素子Optical glass and optical elements
　本発明は、光学ガラスおよび光学素子に関する。 The present invention relates to optical glass and optical elements.
　車載用光学機器に組み込まれる光学素子や、プロジェクタ、コピー機、レーザプリンタおよび放送用機材等のような熱を発生する光学機器に組み込まれる光学素子は、温度変化の大きい環境で使用される。温度変化により屈折率などの光学特性が変動すると、光学系の結像特性等に影響を及ぼす。 Optical elements incorporated in in-vehicle optical equipment and optical elements incorporated in heat-generating optical equipment such as projectors, copiers, laser printers, and broadcasting equipment are used in environments with large temperature changes. Fluctuations in optical characteristics such as the refractive index due to temperature changes affect the imaging characteristics of the optical system.
　ここで、相対屈折率の温度係数（ｄｎ／ｄＴ）がマイナスになる光学素子とプラスになる光学素子とを組み合わせることで、光学系の結像特性等への温度変化の影響を低減できることが知られている。 Here, it is known that the influence of temperature change on the imaging characteristics of the optical system can be reduced by combining an optical element in which the temperature coefficient (dn / dT) of the relative refractive index is negative and an optical element in which the temperature coefficient (dn / dT) is positive. Has been done.
　相対屈折率の温度係数（ｄｎ／ｄＴ）とは、温度変化に対する屈折率の変化を表すものである。温度が上昇するときに屈折率が低くなる光学素子では、相対屈折率の温度係数はマイナスとなる。逆に、温度が上昇するときに屈折率が高くなる光学素子では、相対屈折率の温度係数は、プラスとなる。 The temperature coefficient of the relative refractive index (dn / dT) represents the change in the refractive index with respect to the temperature change. In an optical element whose refractive index decreases as the temperature rises, the temperature coefficient of relative refractive index becomes negative. On the contrary, in an optical element in which the refractive index increases as the temperature rises, the temperature coefficient of the relative refractive index becomes positive.
　その他に、ガラスの熔融温度および成形温度が高い場合には、生産性に劣る他、熔融工程におけるガラス熔融器具（例えば、坩堝、熔融ガラスの攪拌器具など）が侵蝕され、経済性にも劣る。したがって、液相温度ＬＴが低く、すなわち、ガラスの熔融温度および成形温度が低いガラスが求められる。 In addition, when the melting temperature and molding temperature of glass are high, the productivity is inferior, and the glass melting equipment (for example, a crucible, a stirring equipment for molten glass, etc.) in the melting process is eroded, and the economic efficiency is also inferior. Therefore, a glass having a low liquidus temperature LT, that is, a glass having a low melting temperature and molding temperature of the glass is required.
　特許文献１には、相対屈折率の温度係数（ｄｎ／ｄＴ）がマイナスとなる光学ガラスが開示されている。しかしながら、特許文献１のガラスでは、液相温度ＬＴが高く、生産性および経済性に劣ることがわかった。 Patent Document 1 discloses an optical glass in which the temperature coefficient (dn / dT) of the relative refractive index is negative. However, it has been found that the glass of Patent Document 1 has a high liquidus temperature LT and is inferior in productivity and economy.
　加えて、光学素子の平均線熱膨張係数が、光学設計に行う際に重要となる。低屈折率低分散硝材と高屈折率高分散硝材とを組み合わせる場合に、硝材の平均線熱膨張係数の差が小さいほど接合が良好となる。例えば、フッ素を含有する低屈折率低分散硝材では、通常、平均線熱膨張係数が大きい。そのため、それと組み合わせる高屈折率高分散硝材も高い平均線熱膨張係数を有することが求められる。特許文献２に開示された光学ガラスは、高屈折率であるが低分散であり平均線熱膨張係数は小さい。したがって、高屈折率高分散であって、平均線熱膨張係数が大きい光学ガラスが求められている。 In addition, the average coefficient of linear thermal expansion of the optical element is important when performing optical design. When a low refractive index low dispersion glass material and a high refractive index high dispersion glass material are combined, the smaller the difference in the average linear thermal expansion coefficient of the glass material, the better the bonding. For example, a low refractive index low dispersion glass material containing fluorine usually has a large average linear thermal expansion coefficient. Therefore, the high refractive index and high dispersion glass material to be combined with it is also required to have a high average linear thermal expansion coefficient. The optical glass disclosed in Patent Document 2 has a high refractive index but a low dispersion and a small average linear thermal expansion coefficient. Therefore, there is a demand for optical glass having a high refractive index and a high dispersion and a large average linear thermal expansion coefficient.
特開２０１９－１６９７号公報JP-A-2019-1697 特開２００７－１０６６１１号公報JP-A-2007-106611
　そこで、本発明は、温度変化による相対屈折率の温度係数（ｄｎ／ｄＴ）が低く、平均線熱膨張係数の大きい光学ガラス、ならびに前記光学ガラスからなる光学素子を提供することを目的とする。 Therefore, an object of the present invention is to provide an optical glass having a low temperature coefficient (dn / dT) of a relative refractive index due to a temperature change and a large average linear thermal expansion coefficient, and an optical element made of the optical glass.
　本発明の要旨は以下のとおりである。
（１）　屈折率ｎｄが１．６３～１．８０であり、
　アッベ数νｄが２２～３４であり、
　Ｎｂ２Ｏ５の含有量が２５～５５質量％であり、
　ＷＯ３の含有量が３０質量％未満であり、
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］が３６～６０質量％であり、
　Ｐ２Ｏ５、Ｂ２Ｏ３、ＳｉＯ２、Ａｌ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量の質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３＋Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が１．１０以下であり、
　Ｐ２Ｏ５およびＢ２Ｏ３の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］が０．５０以下であり、
　下記（Ａ）または（Ｂ）を満たす光学ガラス。
（Ａ）　Ｐ２Ｏ５の含有量が２０～３６質量％であり、
　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が１．５０以下であり、
　Ｐ２Ｏ５の含有量に対するＢ２Ｏ３の含有量の質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］が０．０５～０．３９であり、
　ＭｇＯ、ＣａＯ、ＳｒＯおよびＢａＯの合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］が８．０質量％以下である。
（Ｂ）　Ｐ２Ｏ５の含有量が２５～３８質量％であり、
　Ａｌ２Ｏ３の含有量が５質量％未満であり、
　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が１．８０以下であり、
　ＭｇＯ、ＣａＯ、ＳｒＯおよびＢａＯの合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］が７．０質量％以下であり、
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）］が０．２５以上である。 The gist of the present invention is as follows.
(1) The refractive index nd is 1.63 to 1.80, and the refractive index nd is 1.63 to 1.80.
The Abbe number νd is 22 to 34,
The content of Nb 2 O 5 is 25 to 55% by mass,
The content of WO 3 is less than 30% by mass,
The total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 36 to 60% by mass. ,
TIO 2 , Nb 2 O 5 , WO 3 , Bi with respect to the total content of P 2 O 5 , B 2 O 3 , SiO 2 , Al 2 O 3 , Li 2 O, Na 2 O, K 2 O and Cs 2 O. Mass ratio of total contents of 2 O 3 and Ta 2 O 5 [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3) + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.10 or less,
The mass ratio of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 [TiO 2 / (P 2 O 5 + B 2 O 3 )] is 0.50 or less.
An optical glass that satisfies the following (A) or (B).
(A) The content of P 2 O 5 is 20 to 36% by mass, and the content is 20 to 36% by mass.
Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.50 or less.
P 2 O 5 mass ratio of the content of B 2 O 3 to the content of [B 2 O 3 / P 2 O 5] is 0.05 to 0.39
The total content [MgO + CaO + SrO + BaO] of MgO, CaO, SrO and BaO is 8.0% by mass or less.
(B) The content of P 2 O 5 is 25 to 38% by mass, and the content is 25 to 38% by mass.
The content of Al 2 O 3 is less than 5% by mass,
Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
The total content of MgO, CaO, SrO and BaO [MgO + CaO + SrO + BaO] is 7.0% by mass or less.
The mass ratio of the content of TiO 2 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more.
（２）Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が１．００以上である、（１）に記載の光学ガラス。 (2) Mass ratio of the total contents of P 2 O 5 , B 2 O 3 and SiO 2 to the total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2) The optical glass according to (1), wherein O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.00 or more.
（３）Ｐ２Ｏ５、Ｂ２Ｏ３、ＳｉＯ２、Ａｌ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量の質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３＋Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が０．５０以上である、（１）または（２）に記載の光学ガラス。 (3) TIO 2 , Nb 2 O 5 , WO with respect to the total content of P 2 O 5 , B 2 O 3 , SiO 2 , Al 2 O 3 , Li 2 O, Na 2 O, K 2 O and Cs 2 O. 3 , Mass ratio of total contents of Bi 2 O 3 and Ta 2 O 5 [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3 + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 0.50 or more, according to (1) or (2).
（４）Ｐ２Ｏ５の含有量が２５～５０質量％であり、
　ＴｉＯ２の含有量が１０～５０質量％であり、
　Ｎｂ２Ｏ５含有量が５～３０質量％であり、
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］が３５～６０質量％であり、
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量に対するＴｉＯ２の含有量の質量比[ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）]が０．２５以上であり、
　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比[（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）]が１．８０以下であり、
　下記（Ａ）または（Ｂ）を満たす光学ガラス。
（Ａ）ＷＯ３の含有量が７質量％以下である。
（Ｂ）実質的にＦを含まない。 (4) The content of P 2 O 5 is 25 to 50% by mass, and the content is 25 to 50% by mass.
The content of TiO 2 is 10 to 50% by mass,
The Nb 2 O 5 content is 5 to 30% by mass,
The total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 35 to 60% by mass. ,
Mass ratio of TiO 2 content to total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more,
Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
An optical glass that satisfies the following (A) or (B).
(A) The content of WO 3 is 7% by mass or less.
(B) Substantially contains no F.
（５）Ｐ２Ｏ５の含有量が２５～５０質量％であり、
　Ｎｂ２Ｏ５含有量が１４～４０質量％であり、
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］が３５～６０質量％であり、
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量に対するＴｉＯ２の含有量の質量比[ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）]が０．２５以上であり、
　Ｐ２Ｏ５の含有量に対するＢ２Ｏ３の含有量の質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］が０．０５～０．３９であり、
　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ］が１０質量％以上であり、
　Ｋ２Ｏの含有量に対するＮａ２Ｏの含有量の質量比［Ｎａ２Ｏ／Ｋ２Ｏ］が１．５０以上である、光学ガラス。 (5) The content of P 2 O 5 is 25 to 50% by mass, and the content is 25 to 50% by mass.
The Nb 2 O 5 content is 14-40% by mass.
The total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 35 to 60% by mass. ,
Mass ratio of TiO 2 content to total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more,
P 2 O 5 mass ratio of the content of B 2 O 3 to the content of [B 2 O 3 / P 2 O 5] is 0.05 to 0.39
The total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O [Li 2 O + Na 2 O + K 2 O + Cs 2 O] is 10% by mass or more.
K 2 O weight ratio of Na 2 O content to the content of [Na 2 O / K 2 O ] is 1.50 or more, an optical glass.
（６）実質的にＦを含まない、（５）に記載の光学ガラス。 (6) The optical glass according to (5), which is substantially free of F.
（７）１００～３００℃の平均線熱膨張係数αが１００×１０－７～２００×１０－７℃－１である、（１）、（２）、（４）～（６）のいずれかに記載の光学ガラス。 (7) Any of (1), (2), and (4) to (6), wherein the average coefficient of linear thermal expansion α at 100 to 300 ° C. is 100 × 10-7 to 200 × 10-7 ° C. -1. The optical glass described in.
（８）Ｈｅ－Ｎｅレーザの波長（６３３ｎｍ）における相対屈折率の温度係数ｄｎ／ｄＴが２０～４０℃の範囲で－０．１×１０－６～－１３．０×１０－６℃－１である、（１）、（２）、（４）～（６）のいずれかに記載の光学ガラス。 (8) The temperature coefficient dn / dT of the relative refractive index at the wavelength of the He-Ne laser (633 nm) is −0.1 × 10 -6 to -13.0 × 10 -6 ° C -1 in the range of 20 to 40 ° C. The optical glass according to any one of (1), (2), (4) to (6).
（９）上記（１）～（８）のいずれかに記載の光学ガラスからなる光学素子。 (9) An optical element made of the optical glass according to any one of (1) to (8) above.
　本発明によれば、温度変化による相対屈折率の温度係数（ｄｎ／ｄＴ）が低く、平均線熱膨張係数の大きい光学ガラス、ならびに前記光学ガラスからなる光学素子を提供できる。 According to the present invention, it is possible to provide an optical glass having a low temperature coefficient (dn / dT) of a relative refractive index due to a temperature change and a large average linear thermal expansion coefficient, and an optical element made of the optical glass.
　本発明および本明細書において、光学ガラスのガラス組成は、特記しない限り、酸化物基準で表示する。ここで「酸化物基準のガラス組成」とは、ガラス原料が熔融時にすべて分解されて光学ガラス中で酸化物として存在するものとして換算することにより得られるガラス組成をいい、各ガラス成分の表記は慣習にならい、ＳｉＯ２、ＴｉＯ２などと記載する。ガラス成分の含有量および合計含有量は、特記しない限り質量基準であり、「％」は「質量％」を意味する。 Unless otherwise specified, the glass composition of optical glass in the present invention and the present specification is expressed on an oxide basis. Here, the "oxide-based glass composition" refers to a glass composition obtained by converting all glass raw materials into those that are decomposed at the time of melting and exist as oxides in optical glass, and the notation of each glass component is Following the convention, it is described as SiO 2 , TiO 2 , and so on. Unless otherwise specified, the content and total content of the glass component are based on mass, and "%" means "mass%".
　ガラス成分の含有量は、公知の方法、例えば、誘導結合プラズマ発光分光分析法（ＩＣＰ－ＡＥＳ）、誘導結合プラズマ質量分析法（ＩＣＰ－ＭＳ）等の方法で定量することができる。また、本明細書および本発明において、構成成分の含有量が０％とは、この構成成分を実質的に含まないことを意味し、該成分が不可避的不純物レベルで含まれることを許容する。 The content of the glass component can be quantified by a known method, for example, an inductively coupled plasma emission spectroscopic analysis method (ICP-AES), an inductively coupled plasma mass analysis method (ICP-MS), or the like. Further, in the present specification and the present invention, the content of the constituent component is 0%, which means that the constituent component is substantially not contained, and the component is allowed to be contained at an unavoidable impurity level.
　本明細書において、ガラスの熱的安定性および耐失透性とは、ともにガラス中における結晶析出のしにくさを指す。特に、熱的安定性は熔融状態のガラスが固化する際の結晶析出のしにくさを指し、耐失透性はリヒートプレス時のように、固化したガラスを再加熱したときの結晶析出のしにくさを指すものとする。 In the present specification, both the thermal stability and the devitrification resistance of glass refer to the difficulty of crystal precipitation in glass. In particular, thermal stability refers to the difficulty of crystal precipitation when the molten glass solidifies, and devitrification resistance refers to the difficulty of crystal precipitation when the solidified glass is reheated, as in the case of reheat pressing. It shall refer to the difficulty.
　また、本明細書では、屈折率は、特記しない限り、ヘリウムのｄ線（波長５８７．５６ｎｍ）における屈折率ｎｄをいう。 Further, in the present specification, the refractive index refers to the refractive index nd at the d-line (wavelength 587.56 nm) of helium unless otherwise specified.
　また、アッベ数νｄは、分散に関する性質を表す値として用いられるものであり、以下の式で表される。ここで、ｎＦは青色水素のＦ線（波長４８６．１３ｎｍ）における屈折率、ｎＣは赤色水素のＣ線（６５６．２７ｎｍ）における屈折率である。
　　νｄ=（ｎｄ－１）／ｎＦ－ｎＣ　・・・（１） Further, the Abbe number νd is used as a value representing a property related to dispersion, and is expressed by the following equation. Here, nF is the refractive index of blue hydrogen at the F line (wavelength 486.13 nm), and nC is the refractive index of red hydrogen at the C line (656.27 nm).
νd = (nd-1) / nF-nC ... (1)
　以下に、本発明の光学ガラスを、第１実施形態、第２実施形態、第３実施形態に分けて説明する。 Hereinafter, the optical glass of the present invention will be described separately for the first embodiment, the second embodiment, and the third embodiment.
第１実施形態
　第１実施形態に係る光学ガラスについて詳細に説明する。
　第１実施形態に光学ガラスは、
　屈折率ｎｄが１．６３～１．８０であり、
　アッベ数νｄが２２～３４であり、
　Ｎｂ２Ｏ５の含有量が２５～５５質量％であり、
　ＷＯ３の含有量が３０質量％未満であり、
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］が３６～６０質量％であり、
　Ｐ２Ｏ５、Ｂ２Ｏ３、ＳｉＯ２、Ａｌ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量の質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３＋Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が１．１０以下であり、
　Ｐ２Ｏ５およびＢ２Ｏ３の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］が０．５０以下であり、
　下記（Ａ）または（Ｂ）を満たす。
（Ａ）　Ｐ２Ｏ５の含有量が２０～３６質量％であり、
　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が１．５０以下であり、
　Ｐ２Ｏ５の含有量に対するＢ２Ｏ３の含有量の質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］が０．０５～０．３９であり、
　ＭｇＯ、ＣａＯ、ＳｒＯおよびＢａＯの合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］が８．０質量％以下である。
（Ｂ）　Ｐ２Ｏ５の含有量が２５～３８質量％であり、
　Ａｌ２Ｏ３の含有量が５質量％未満であり、
　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が１．８０以下であり、
　ＭｇＯ、ＣａＯ、ＳｒＯおよびＢａＯの合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］が７．０質量％以下であり、
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）］が０．２５以上である。 First Embodiment The optical glass according to the first embodiment will be described in detail.
In the first embodiment, the optical glass is
The refractive index nd is 1.63 to 1.80, and the refractive index nd is 1.63 to 1.80.
The Abbe number νd is 22 to 34,
The content of Nb 2 O 5 is 25 to 55% by mass,
The content of WO 3 is less than 30% by mass,
The total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 36 to 60% by mass. ,
TIO 2 , Nb 2 O 5 , WO 3 , Bi with respect to the total content of P 2 O 5 , B 2 O 3 , SiO 2 , Al 2 O 3 , Li 2 O, Na 2 O, K 2 O and Cs 2 O. Mass ratio of total contents of 2 O 3 and Ta 2 O 5 [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3) + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.10 or less,
The mass ratio of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 [TiO 2 / (P 2 O 5 + B 2 O 3 )] is 0.50 or less.
The following (A) or (B) is satisfied.
(A) The content of P 2 O 5 is 20 to 36% by mass, and the content is 20 to 36% by mass.
Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.50 or less.
P 2 O 5 mass ratio of the content of B 2 O 3 to the content of [B 2 O 3 / P 2 O 5] is 0.05 to 0.39
The total content [MgO + CaO + SrO + BaO] of MgO, CaO, SrO and BaO is 8.0% by mass or less.
(B) The content of P 2 O 5 is 25 to 38% by mass, and the content is 25 to 38% by mass.
The content of Al 2 O 3 is less than 5% by mass,
Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
The total content of MgO, CaO, SrO and BaO [MgO + CaO + SrO + BaO] is 7.0% by mass or less.
The mass ratio of the content of TiO 2 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more.
　以下、特記しない限り、第１実施形態に係る光学ガラスとは、上記（Ａ）を満たす第１実施形態に係る光学ガラスおよび上記（Ｂ）を満たす第１実施形態に係る光学ガラスを意味するものとする。 Hereinafter, unless otherwise specified, the optical glass according to the first embodiment means the optical glass according to the first embodiment satisfying the above (A) and the optical glass according to the first embodiment satisfying the above (B). And.
　第１実施形態に係る光学ガラスにおいて、屈折率ｎｄは１．６３～１．８０である。屈折率ｎｄの下限は１．６５、１．６７、または１．６９でもよく、屈折率ｎｄの上限は１．７９、１．７８、または１．７７でもよい。 In the optical glass according to the first embodiment, the refractive index nd is 1.63 to 1.80. The lower limit of the refractive index nd may be 1.65, 1.67, or 1.69, and the upper limit of the refractive index nd may be 1.79, 1.78, or 1.77.
　屈折率ｎｄは各ガラス成分の含有量を適宜調整することにより所望の値にすることができる。相対的に屈折率ｎｄを高める働きを有する成分（高屈折率化成分）は、Ｎｂ２Ｏ５、ＴｉＯ２、ＷＯ３、Ｂｉ２Ｏ３、Ｔａ２Ｏ５、ＺｒＯ２、Ｌａ２Ｏ３等である。一方、相対的に屈折率ｎｄを低くする働きを有する成分（低屈折率化成分）は、Ｐ２Ｏ５、ＳｉＯ2、Ｂ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２Ｏ等である。したがって、例えば、Ｐ２Ｏ５、Ｂ２Ｏ３、ＳｉＯ２、Ａｌ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量の質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３＋Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］を増加させることにより屈折率ｎｄを高めることができ、該質量比を減少させることにより屈折率ｎｄを低下させることができる。 The refractive index nd can be set to a desired value by appropriately adjusting the content of each glass component. The components having the function of relatively increasing the refractive index nd (high refractive index component) are Nb 2 O 5 , TiO 2 , WO 3 , Bi 2 O 3 , Ta 2 O 5 , ZrO 2 , La 2 O 3, etc. Is. On the other hand, the components having a function of relatively lowering the refractive index nd (lowering the refractive index component) are P 2 O 5 , SiO 2 , B 2 O 3 , Li 2 O, Na 2 O, K 2 O and the like. is there. Thus, for example, TIO 2 , Nb 2 O 5 , with respect to the total content of P 2 O 5 , B 2 O 3 , SiO 2 , Al 2 O 3 , Li 2 O, Na 2 O, K 2 O and Cs 2 O, Mass ratio of total contents of WO 3 , Bi 2 O 3 and Ta 2 O 5 [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5 + B 2 O 3 + SiO 2) + Al 2 O 3 + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] can be increased to increase the refractive index nd, and decreasing the mass ratio can decrease the refractive index nd.
　第１実施形態に係る光学ガラスにおいて、アッベ数νｄは２２～３４である。アッベ数νｄの下限は２２．５、２３、または２３．５でもよく、アッベ数νｄの上限は３２、３０、または２８でもよい。 In the optical glass according to the first embodiment, the Abbe number νd is 22 to 34. The lower limit of the Abbe number νd may be 22.5, 23, or 23.5, and the upper limit of the Abbe number νd may be 32, 30, or 28.
　アッベ数νｄは、各ガラス成分の含有量を適宜調整することにより所望の値にすることができる。相対的にアッベ数νｄを低くする成分、すなわち高分散化成分は、Ｎｂ２Ｏ５、ＴｉＯ２、ＷＯ３、Ｂｉ２Ｏ３、Ｔａ２Ｏ５、ＺｒＯ２等である。一方、相対的にアッベ数νｄを高くする成分、すなわち低分散化成分は、Ｐ２Ｏ５、ＳｉＯ2、Ｂ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２Ｏ、Ｌａ２Ｏ３、ＢａＯ、ＣａＯ、ＳｒＯ等である。 The Abbe number νd can be set to a desired value by appropriately adjusting the content of each glass component. The components that relatively lower the Abbe number νd, that is, the highly dispersed components, are Nb 2 O 5 , TiO 2 , WO 3 , Bi 2 O 3 , Ta 2 O 5 , ZrO 2, and the like. On the other hand, the components that relatively increase the Abbe number νd, that is, the low dispersion components, are P 2 O 5 , SiO 2 , B 2 O 3 , Li 2 O, Na 2 O, K 2 O, La 2 O 3 , BaO, CaO, SrO and the like.
　第１実施形態に係る光学ガラスにおいて、Ｎｂ２Ｏ５の含有量は２５～５５％である。Ｎｂ２Ｏ５の含有量の下限は、好ましくは２７％であり、さらには２９％、３１％、３３％の順により好ましい。また、Ｎｂ２Ｏ５の含有量の上限は、好ましくは５３％であり、さらには５１％、４９％、４７％の順により好ましい。 In the optical glass according to the first embodiment, the content of Nb 2 O 5 is 25 to 55%. The lower limit of the content of Nb 2 O 5 is preferably 27%, more preferably 29%, 31%, and 33% in that order. The upper limit of the content of Nb 2 O 5 is preferably 53%, more preferably 51%, 49%, and 47% in that order.
　Ｎｂ２Ｏ５は、高屈折率化および高分散化に寄与する成分である。したがって、Ｎｂ２Ｏ５の含有量は上記範囲とすることで、所望の光学恒数を有する光学ガラスが得られる。一方、Ｎｂ２Ｏ５の含有量が多すぎると、ガラスの着色が強まるおそれがある。 Nb 2 O 5 is a component that contributes to high refractive index and high dispersion. Therefore, by setting the content of Nb 2 O 5 in the above range, an optical glass having a desired optical constant can be obtained. On the other hand, if the content of Nb 2 O 5 is too large, the coloring of the glass may be strengthened.
　第１実施形態に係る光学ガラスにおいて、ＷＯ３の含有量は３０％未満である。ＷＯ３の含有量の上限は、好ましくは２０％であり、さらには１５％、１０％、５％の順により好ましい。ＷＯ３の含有量は少ない方が好ましく、その下限は好ましくは０％である。ＷＯ３の含有量は０％でもよい。 In the optical glass according to the first embodiment, the content of WO 3 is less than 30%. The upper limit of the content of WO 3 is preferably 20%, more preferably 15%, 10%, and 5%. The content of WO 3 is preferably low, and the lower limit thereof is preferably 0%. The content of WO 3 may be 0%.
　ＷＯ３の含有量を上記範囲とすることで、透過率を高めることができ、また、ガラスの比重の増大を抑制できる。また、相対屈折率の温度係数（ｄｎ／ｄＴ）を低くすることができる。 By setting the content of WO 3 in the above range, the transmittance can be increased and the increase in the specific gravity of the glass can be suppressed. Further, the temperature coefficient (dn / dT) of the relative refractive index can be lowered.
　第１実施形態に係る光学ガラスにおいて、ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］は３６～６０％である。該合計含有量の下限は、好ましくは３８％であり、さらには４０％、４１％、４２％の順により好ましい。また、該合計含有量の上限は、好ましくは５８％であり、さらには５６％、５４％、５２％の順により好ましい。 In the optical glass according to the first embodiment, the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 36 to 60%. The lower limit of the total content is preferably 38%, more preferably 40%, 41%, and 42%. The upper limit of the total content is preferably 58%, more preferably 56%, 54%, and 52%.
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５は、ガラスの高分散化に寄与する成分である。したがって、合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］を上記範囲とすることで、所望の光学恒数を有する光学ガラスが得られる。また、ガラスの熱的安定性も改善できる。一方、該合計含有量が多すぎると、所望の光学恒数を有する光学ガラスが得られないおそれがあり、また、ガラスの熱的安定性が低下し、ガラスの着色が強まるおそれがある。 TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 are components that contribute to high dispersion of glass. Therefore, by setting the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] in the above range, an optical glass having a desired optical constant can be obtained. In addition, the thermal stability of the glass can be improved. On the other hand, if the total content is too large, an optical glass having a desired optical constant may not be obtained, the thermal stability of the glass may be lowered, and the coloring of the glass may be strengthened.
　第１実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５、Ｂ２Ｏ３、ＳｉＯ２、Ａｌ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量の質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３＋Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］は１．１０以下である。該質量比の上限は、好ましくは１．０７であり、さらには１．０４、１．０２、１．００の順により好ましい。また、該質量比の下限は、より好ましくは０．５０であり、さらには０．５５、０．６０、０．６５の順により好ましい。 In the optical glass according to the first embodiment, TiO 2 with respect to the total content of P 2 O 5 , B 2 O 3 , SiO 2 , Al 2 O 3 , Li 2 O, Na 2 O, K 2 O and Cs 2 O. , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 total content mass ratio [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5) / (P 2 O 5) + B 2 O 3 + SiO 2 + Al 2 O 3 + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.10 or less. The upper limit of the mass ratio is preferably 1.07, and more preferably 1.04, 1.02, and 1.00 in that order. The lower limit of the mass ratio is more preferably 0.50, and more preferably 0.55, 0.60, and 0.65.
　質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３＋Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］を上記範囲とすることで、所望の光学恒数を有する光学ガラスが得られる。 Mass ratio [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3 + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] By setting the range, an optical glass having a desired optical constant can be obtained.
　第１実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５およびＢ２Ｏ３の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］は０．５０以下である。 In the optical glass according to the first embodiment, the mass ratio of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 [TiO 2 / (P 2 O 5 + B 2 O 3 )] is 0. It is 50 or less.
　質量比［ＴｉＯ２／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］を上記範囲とすることで、所望の光学恒数を有し、熱的安定性が高い光学ガラスが得られる。 By setting the mass ratio [TiO 2 / (P 2 O 5 + B 2 O 3 )] in the above range, an optical glass having a desired optical constant and high thermal stability can be obtained.
　第１実施形態に係る光学ガラスは、上記のとおり（Ａ）または（Ｂ）を満たす。まず（Ａ）ついて詳述する。 The optical glass according to the first embodiment satisfies (A) or (B) as described above. First, (A) will be described in detail.
　第１実施形態に係る光学ガラスは、
（Ａ）　Ｐ２Ｏ５の含有量が２０～３６質量％であり、
　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が１．５０以下であり、
　Ｐ２Ｏ５の含有量に対するＢ２Ｏ３の含有量の質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］が０．０５～０．３９であり、
　ＭｇＯ、ＣａＯ、ＳｒＯおよびＢａＯの合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］が８．０質量％以下である、
　との要件を満たしうる。 The optical glass according to the first embodiment is
(A) The content of P 2 O 5 is 20 to 36% by mass, and the content is 20 to 36% by mass.
Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.50 or less.
P 2 O 5 mass ratio of the content of B 2 O 3 to the content of [B 2 O 3 / P 2 O 5] is 0.05 to 0.39
The total content of MgO, CaO, SrO and BaO [MgO + CaO + SrO + BaO] is 8.0% by mass or less.
Can meet the requirements of.
　上記（Ａ）を満たす第１実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５の含有量は２０～３６％である。Ｐ２Ｏ５の含有量の下限は、好ましくは２１％であり、さらには２２％、２３％、２４％の順により好ましい。また、Ｐ２Ｏ５の含有量の上限は、好ましくは３５％であり、さらには３４％、３３％、３２％の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (A), the content of P 2 O 5 is 20 to 36 percent. The lower limit of the content of P 2 O 5 is preferably 21%, more preferably 22%, 23%, and 24%. The upper limit of the content of P 2 O 5 is preferably 35%, more preferably 34%, 33%, and 32% in that order.
　Ｐ２Ｏ５は、ガラスのネットワーク形成成分であり、ガラス中に高分散成分を多く含有するために必須の成分である。Ｐ２Ｏ５の含有量を上記範囲とすることで、熱的安定性が高く、所望の光学恒数を有する光学ガラスが得られる。 P 2 O 5 is a network-forming component of glass, and is an essential component for containing a large amount of highly dispersed components in glass. By setting the content of P 2 O 5 in the above range, an optical glass having high thermal stability and a desired optical constant can be obtained.
　上記（Ａ）を満たす第１実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］は１．５０以下である。該質量比の上限は、好ましくは１．４７であり、さらには１．４４、１．４２、１．４０の順により好ましい。また、該質量比の下限は、好ましくは１．００であり、さらには１．０５、１．０８、１．１０の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (A), the total of P 2 O 5 , B 2 O 3 and SiO 2 with respect to the total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O. The mass ratio of the content [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.50 or less. The upper limit of the mass ratio is preferably 1.47, and more preferably 1.44, 1.42, and 1.40 in that order. The lower limit of the mass ratio is preferably 1.00, more preferably 1.05, 1.08, and 1.10.
　質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］を上記範囲とすることで、熱的安定性が高く、相対屈折率の温度係数（ｄｎ／ｄＴ）が低く、平均線熱膨張係数の大きい光学ガラスが得られる。 By setting the mass ratio [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] in the above range, the thermal stability is high and the temperature coefficient of relative refractive index ( An optical glass having a low dn / dT) and a large average coefficient of linear thermal expansion can be obtained.
　上記（Ａ）を満たす第１実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５の含有量に対するＢ２Ｏ３の含有量の質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］は０．０５～０．３９である。該質量比の下限は、好ましくは０．０６であり、さらには０．０７、０．０８、０．０９の順により好ましい。また、該質量比の上限は、より好ましくは０．３６であり、さらには０．３３、０．３１、０．２９の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (A), the mass ratio of the content of B 2 O 3 to the content of P 2 O 5 [B 2 O 3 / P 2 O 5] 0.05 ~ It is 0.39. The lower limit of the mass ratio is preferably 0.06, more preferably 0.07, 0.08, 0.09. The upper limit of the mass ratio is more preferably 0.36, and further preferably 0.33, 0.31 and 0.29.
　質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］を上記範囲とすることで、相対屈折率の温度係数（ｄｎ／ｄＴ）が低く、平均線熱膨張係数が大きく、耐失透性が高く、さらに液相温度ＬＴの低い光学ガラスが得られる。 By setting the mass ratio [B 2 O 3 / P 2 O 5 ] in the above range, the temperature coefficient of relative refractive index (dn / dT) is low, the average coefficient of linear thermal expansion is large, and the devitrification resistance is high. Further, an optical glass having a low liquidus temperature LT can be obtained.
　上記（Ａ）を満たす第１実施形態に係る光学ガラスにおいて、ＭｇＯ、ＣａＯ、ＳｒＯおよびＢａＯの合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］は８．０％以下である。該合計含有量の上限は、好ましくは６％であり、さらには５％、４％、３％の順により好ましい。また、該合計含有量の下限は、好ましくは０％である。 In the optical glass according to the first embodiment satisfying the above (A), the total content [MgO + CaO + SrO + BaO] of MgO, CaO, SrO and BaO is 8.0% or less. The upper limit of the total content is preferably 6%, more preferably 5%, 4%, and 3%. The lower limit of the total content is preferably 0%.
　合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］を上記範囲とすることで、高分散化を促進できる。 By setting the total content [MgO + CaO + SrO + BaO] in the above range, high dispersion can be promoted.
　また、上記（Ａ）を満たす第１実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５およびＢ２Ｏ３の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］は０．５０以下である。該質量比の上限は、好ましくは０．４７であり、さらには０．４４、０．４２、０．４０の順により好ましい。また、該質量比の下限は、より好ましくは０．００であり、さらには０．０３、０．０６、０．０８、０．１０の順により好ましい。 Further, in the optical glass according to the first embodiment satisfying the above (A), the mass ratio of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 [TiO 2 / (P 2 O 5 + B). 2 O 3 )] is 0.50 or less. The upper limit of the mass ratio is preferably 0.47, more preferably 0.44, 0.42, 0.40 in that order. The lower limit of the mass ratio is more preferably 0.00, and further preferably 0.03, 0.06, 0.08, 0.10.
　質量比［ＴｉＯ２／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］を上記範囲とすることで、所望の光学恒数を有し、熱的安定性が高い光学ガラスが得られる。 By setting the mass ratio [TiO 2 / (P 2 O 5 + B 2 O 3 )] in the above range, an optical glass having a desired optical constant and high thermal stability can be obtained.
　上記（Ａ）を満たす第１実施形態に係る光学ガラスにおけるガラス成分の含有量および比率について、以下に非制限的な例を示す。 Non-limiting examples of the content and ratio of the glass component in the optical glass according to the first embodiment satisfying the above (A) are shown below.
　上記（Ａ）を満たす第１実施形態に係る光学ガラスにおいて、Ｂ２Ｏ３の含有量の上限は、好ましくは１０％であり、さらには８％、７％、６％の順により好ましい。また、Ｂ２Ｏ３の含有量の下限は、好ましくは１％であり、さらには１．５％、１．８％、２．０％の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (A), the upper limit of the content of B 2 O 3 is preferably 10%, more preferably 8%, 7%, and 6%. The lower limit of the content of B 2 O 3 is preferably 1%, more preferably 1.5%, 1.8%, and 2.0% in that order.
　Ｂ２Ｏ３は、ガラスのネットワーク形成成分であり、ガラスの熱的安定性を改善する働きを有する。一方、Ｂ２Ｏ３の含有量が多いと、耐失透性が低下する傾向がある。そのためＢ２Ｏ３の含有量は上記範囲であることが好ましい。 B 2 O 3 is a network-forming component of glass and has a function of improving the thermal stability of glass. On the other hand, when the content of B 2 O 3 is large, the devitrification resistance tends to decrease. Therefore, the content of B 2 O 3 is preferably in the above range.
　上記（Ａ）を満たす第１実施形態に係る光学ガラスにおいて、Ａｌ２Ｏ３の含有量は、好ましくは３％以下であり、さらには２％以下、１％以下の順により好ましい。Ａｌ２Ｏ３の含有量は０％でもよい。 In the optical glass according to the first embodiment satisfying the above (A), the content of Al 2 O 3 is preferably 3% or less, more preferably 2% or less and 1% or less. The content of Al 2 O 3 may be 0%.
　Ａｌ２Ｏ３は、ガラスの化学的耐久性、耐候性を改善する働きを有するガラス成分であり、ネットワーク形成成分として考えることができる。一方、Ａｌ２Ｏ３の含有量が多くなると、ガラスの耐失透性が低下する。また、ガラス転移温度Ｔｇが上昇し、熱的安定性が低下する等の問題が生じやすい。このような問題を回避する観点から、Ａｌ２Ｏ３の含有量の上限は上記範囲であることが好ましい。 Al 2 O 3 is a glass component having a function of improving the chemical durability and weather resistance of glass, and can be considered as a network forming component. On the other hand, when the content of Al 2 O 3 increases, the devitrification resistance of the glass decreases. In addition, problems such as an increase in the glass transition temperature Tg and a decrease in thermal stability are likely to occur. From the viewpoint of avoiding such a problem, the upper limit of the content of Al 2 O 3 is preferably in the above range.
　上記（Ａ）を満たす第１実施形態に係る光学ガラスにおいて、ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）］の下限は、好ましくは０であり、さらには０．０２、０．０４、０．０６の順により好ましい。また、該質量比の上限は、好ましくは０．５０であり、さらには０．４５、０．４０、０．３５の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (A), the mass ratio of the content of TiO 2 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [ The lower limit of TiO 2 / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 )] is preferably 0, and more preferably 0.02, 0.04, and 0.06. The upper limit of the mass ratio is preferably 0.50, and more preferably 0.45, 0.40, and 0.35.
　ＴｉＯ２は、高屈折率化成分の中でも、特に高屈折率化の作用が大きい成分である。したがって、所望の光学恒数を得る観点から、質量比［ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）］は上記範囲であることが好ましい。 TiO 2 is a component having a particularly large effect of increasing the refractive index among the components for increasing the refractive index. Therefore, from the viewpoint of obtaining a desired optical constant, the mass ratio [TiO 2 / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 )] is preferably in the above range.
　上記（Ａ）を満たす第１実施形態に係る光学ガラスにおいて、ＴｉＯ２の含有量の下限は、好ましくは０％であり、さらには１％、２％、３％、４％の順により好ましい。ＴｉＯ２の含有量は０％でもよい。また、ＴｉＯ２の含有量の上限は、好ましくは１５％であり、さらには１３％、１１％、１０％の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (A), the lower limit of the TiO 2 content is preferably 0%, more preferably 1%, 2%, 3%, and 4%. The content of TiO 2 may be 0%. The upper limit of the TiO 2 content is preferably 15%, more preferably 13%, 11%, and 10%.
　ＴｉＯ２は、高分散化に大きく寄与する。一方、ＴｉＯ２は、比較的ガラスの着色を増大させやすく、また、熔融性を悪化させるおそれがある。そのためＴｉＯ２の含有量は上記範囲であることが好ましい。 TiO 2 greatly contributes to high dispersion. On the other hand, TiO 2 tends to increase the coloring of the glass relatively easily, and may deteriorate the meltability. Therefore, the content of TiO 2 is preferably in the above range.
　上記（Ａ）を満たす第１実施形態に係る光学ガラスにおいて、ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３およびＢｉ２Ｏ３の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３］の下限は、好ましくは３６％であり、さらには３８％、４０％、４１％、４２％の順により好ましい。また、合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３］の上限は、好ましくは５８％であり、さらには５６％、５４％、５２％の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (A), the total content of TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 ] The lower limit is preferably 36%, more preferably 38%, 40%, 41%, and 42% in that order. The upper limit of the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 ] is preferably 58%, more preferably 56%, 54%, and 52%.
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３およびＢｉ２Ｏ３は、ガラスの高分散化に寄与し、また、適量を含有させることにより、ガラスの熱的安定性を改善する働きも有する。一方、ガラスの着色を増大させる成分でもある。したがって、合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３］は上記範囲であることが好ましい。 TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 contribute to high dispersion of glass, and also have a function of improving the thermal stability of glass by containing an appropriate amount. On the other hand, it is also a component that increases the coloring of glass. Therefore, the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 ] is preferably in the above range.
　上記（Ａ）を満たす第１実施形態に係る光学ガラスにおいて、Ｎａ２Ｏの含有量の下限は、好ましくは６％であり、さらには８％、９％、１０％の順により好ましい。また、Ｎａ２Ｏの含有量の上限は、好ましくは３０％であり、さらには２８％、２６％、２５％の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (A), the lower limit of the Na 2 O content is preferably 6%, more preferably 8%, 9%, and 10% in that order. The upper limit of the Na 2 O content is preferably 30%, more preferably 28%, 26%, and 25%.
　Ｎａ２Ｏは、ガラスの低比重化に寄与する成分であり、ガラスの熔融性を改善し、また平均線熱膨張係数を大きくする働きを有する。一方、Ｎａ２Ｏの含有量が多くなると、耐失透性が低下する。したがって、Ｎａ２Ｏの含有量は上記範囲であることが好ましい。 Na 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion. On the other hand, as the Na 2 O content increases, the devitrification resistance decreases. Therefore, the Na 2 O content is preferably in the above range.
　上記（Ａ）を満たす第１実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏ、Ｎａ２ＯおよびＫ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ］の上限は、好ましくは３５％であり、さらには３３％、３１％、３０％の順により好ましい。また、該合計含有量の下限は、好ましくは１０％であり、さらには１４％、１７％、１８％の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (A), the upper limit of the total content [Li 2 O + Na 2 O + K 2 O] of Li 2 O, Na 2 O and K 2 O is preferably 35%. Further, it is more preferable in the order of 33%, 31%, and 30%. The lower limit of the total content is preferably 10%, more preferably 14%, 17%, and 18%.
　Ｌｉ２Ｏ、Ｎａ２ＯおよびＫ２Ｏは、いずれもガラスの熱的安定性を改善する働きを有する。しかし、これらの含有量が多くなると、化学的耐久性、耐候性が低下するおそれがある。そのため、Ｌｉ２Ｏ、Ｎａ２ＯおよびＫ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ］は上記範囲であることが好ましい。 Li 2 O, Na 2 O and K 2 O all have a function of improving the thermal stability of glass. However, if these contents are high, the chemical durability and weather resistance may be lowered. Therefore, the total content of Li 2 O, Na 2 O and K 2 O [Li 2 O + Na 2 O + K 2 O] is preferably in the above range.
　次に（Ｂ）について詳述する。 Next, (B) will be described in detail.
　第１実施形態に係る光学ガラスは、
（Ｂ）　Ｐ２Ｏ５の含有量が２５～３８質量％であり、
　Ａｌ２Ｏ３の含有量が５質量％未満であり、
　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が１．８０以下であり、
　ＭｇＯ、ＣａＯ、ＳｒＯおよびＢａＯの合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］が７．０質量％以下であり、
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）］が０．２５以上である、
との要件を満たしうる。 The optical glass according to the first embodiment is
(B) The content of P 2 O 5 is 25 to 38% by mass, and the content is 25 to 38% by mass.
The content of Al 2 O 3 is less than 5% by mass,
Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
The total content of MgO, CaO, SrO and BaO [MgO + CaO + SrO + BaO] is 7.0% by mass or less.
The mass ratio of the content of TiO 2 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more,
Can meet the requirements of.
　上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５の含有量は２５～３８％である。Ｐ２Ｏ５の含有量の下限は、好ましくは２６％であり、さらには２７％、２８％、２９％、３０％の順により好ましい。また、Ｐ２Ｏ５の含有量の上限は、好ましくは３７％である。 In the optical glass according to the first embodiment satisfying the above (B), the content of P 2 O 5 is 25 to 38 percent. The lower limit of the content of P 2 O 5 is preferably 26%, more preferably 27%, 28%, 29% and 30%. The upper limit of the content of P 2 O 5 is preferably 37%.
　Ｐ２Ｏ５は、ガラスのネットワーク形成成分であり、ガラス中に高分散成分を多く含有するために必須の成分である。Ｐ２Ｏ５の含有量を上記範囲とすることで、熱的安定性が高く、所望の光学恒数を有する光学ガラスが得られる。 P 2 O 5 is a network-forming component of glass, and is an essential component for containing a large amount of highly dispersed components in glass. By setting the content of P 2 O 5 in the above range, an optical glass having high thermal stability and a desired optical constant can be obtained.
　上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおいて、Ａｌ２Ｏ３の含有量は、５％未満である。Ａｌ２Ｏ３の含有量は、好ましくは３％以下であり、さらには２％以下、１％以下の順により好ましい。Ａｌ２Ｏ３の含有量は０％でもよい。 In the optical glass according to the first embodiment satisfying the above (B), the content of Al 2 O 3 is less than 5%. The content of Al 2 O 3 is preferably 3% or less, more preferably 2% or less and 1% or less. The content of Al 2 O 3 may be 0%.
　Ａｌ２Ｏ３は、ガラスの化学的耐久性、耐候性を改善する働きを有するガラス成分であり、ネットワーク形成成分として考えることができる。一方、Ａｌ２Ｏ３の含有量が多くなると、ガラスの耐失透性が低下する。また、ガラス転移温度Ｔｇが上昇し、熱的安定性が低下する等の問題が生じやすい。このような問題を回避する観点から、Ａｌ２Ｏ３の含有量の上限は上記範囲であることが好ましい。 Al 2 O 3 is a glass component having a function of improving the chemical durability and weather resistance of glass, and can be considered as a network forming component. On the other hand, when the content of Al 2 O 3 increases, the devitrification resistance of the glass decreases. In addition, problems such as an increase in the glass transition temperature Tg and a decrease in thermal stability are likely to occur. From the viewpoint of avoiding such a problem, the upper limit of the content of Al 2 O 3 is preferably in the above range.
　上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］は１．８０以下である。該質量比の上限は、好ましくは１．７８であり、さらには１．７６、１．７４の順により好ましい。また、該質量比の下限は、好ましくは１．００であり、さらには１．０５、１．０８、１．１０の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (B), the total of P 2 O 5 , B 2 O 3 and SiO 2 with respect to the total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O. The mass ratio of the content [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less. The upper limit of the mass ratio is preferably 1.78, and more preferably 1.76 and 1.74. The lower limit of the mass ratio is preferably 1.00, more preferably 1.05, 1.08, and 1.10.
　質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］を上記範囲とすることで、熱的安定性が高く、相対屈折率の温度係数（ｄｎ／ｄＴ）が低く、平均線熱膨張係数の大きい光学ガラスが得られる。 By setting the mass ratio [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] in the above range, the thermal stability is high and the temperature coefficient of relative refractive index ( An optical glass having a low dn / dT) and a large average coefficient of linear thermal expansion can be obtained.
　上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおいて、ＭｇＯ、ＣａＯ、ＳｒＯおよびＢａＯの合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］は７．０％以下である。該合計含有量の上限は、好ましくは６％であり、さらには５％、４％、３％の順により好ましい。また、該合計含有量の下限は、好ましくは０％である。 In the optical glass according to the first embodiment satisfying the above (B), the total content [MgO + CaO + SrO + BaO] of MgO, CaO, SrO and BaO is 7.0% or less. The upper limit of the total content is preferably 6%, more preferably 5%, 4%, and 3%. The lower limit of the total content is preferably 0%.
　合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］を上記範囲とすることで、高分散化を促進できる。 By setting the total content [MgO + CaO + SrO + BaO] in the above range, high dispersion can be promoted.
　上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおいて、ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）］は０．２５以上である。該質量比の下限は、好ましくは０．２６であり、さらには０．２７、０．２８、０．２９の順により好ましい。また、該質量比の上限は、好ましくは０．５０であり、さらには０．４５、０．４０、０．３５の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (B), the mass ratio of the content of TiO 2 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [ TiO 2 / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 )] is 0.25 or more. The lower limit of the mass ratio is preferably 0.26, more preferably 0.27, 0.28, 0.29 in that order. The upper limit of the mass ratio is preferably 0.50, and more preferably 0.45, 0.40, and 0.35.
　ＴｉＯ２は、高屈折率化成分の中でも、特に高屈折率化の作用が大きい成分である。したがって、所望の光学恒数を得る観点から、質量比［ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）］は上記範囲であることが好ましい。 TiO 2 is a component having a particularly large effect of increasing the refractive index among the components for increasing the refractive index. Therefore, from the viewpoint of obtaining a desired optical constant, the mass ratio [TiO 2 / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 )] is preferably in the above range.
　また、上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５およびＢ２Ｏ３の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］は０．５０以下である。該質量比の上限は、好ましくは０．４７であり、さらには、０．４６、０．４５の順に好ましい。また、該質量比の下限は、好ましくは０．００であり、さらには０．２０、０．２５、０．３０、０．３５の順に好ましい。 Further, in the optical glass according to the first embodiment satisfying the above (B), the mass ratio of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 [TiO 2 / (P 2 O 5 + B). 2 O 3 )] is 0.50 or less. The upper limit of the mass ratio is preferably 0.47, and more preferably 0.46 and 0.45 in that order. The lower limit of the mass ratio is preferably 0.00, and more preferably 0.20, 0.25, 0.30, and 0.35 in that order.
　質量比［ＴｉＯ２／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］を上記範囲とすることで、所望の光学恒数を有し、熱的安定性が高い光学ガラスが得られる。 By setting the mass ratio [TiO 2 / (P 2 O 5 + B 2 O 3 )] in the above range, an optical glass having a desired optical constant and high thermal stability can be obtained.
　上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおけるガラス成分の含有量および比率について、以下に非制限的な例を示す。 Non-limiting examples of the content and ratio of the glass component in the optical glass according to the first embodiment satisfying the above (B) are shown below.
　上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５の含有量に対するＢ２Ｏ３の含有量の質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］の下限は、好ましくは０である。該質量比は０でもよい。また、該質量比の上限は、より好ましくは０．３６であり、さらには０．３３、０．３１、０．２９の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (B), the lower limit of the content of the mass ratio of B 2 O 3 to the content of P 2 O 5 [B 2 O 3 / P 2 O 5] are preferably Is 0. The mass ratio may be 0. The upper limit of the mass ratio is more preferably 0.36, and further preferably 0.33, 0.31 and 0.29.
　質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］を上記範囲とすることで、相対屈折率の温度係数（ｄｎ／ｄＴ）が低く、平均線熱膨張係数が大きく、耐失透性が高く、さらに液相温度ＬＴの低い光学ガラスが得られる。 By setting the mass ratio [B 2 O 3 / P 2 O 5 ] in the above range, the temperature coefficient of relative refractive index (dn / dT) is low, the average coefficient of linear thermal expansion is large, and the devitrification resistance is high. Further, an optical glass having a low liquidus temperature LT can be obtained.
　上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおいて、Ｂ２Ｏ３の含有量の上限は、好ましくは１０％であり、さらには８％、７％、６％の順により好ましい。また、Ｂ２Ｏ３の含有量の下限は、好ましくは０％である。Ｂ２Ｏ３の含有量は０％でもよい。 In the optical glass according to the first embodiment satisfying the above (B), the upper limit of the content of B 2 O 3 is preferably 10%, more preferably 8%, 7%, and 6%. The lower limit of the content of B 2 O 3 is preferably 0%. The content of B 2 O 3 may be 0%.
　Ｂ２Ｏ３は、ガラスのネットワーク形成成分であり、ガラスの熱的安定性を改善する働きを有する。一方、Ｂ２Ｏ３の含有量が多いと、耐失透性が低下する傾向がある。そのためＢ２Ｏ３の含有量は上記範囲であることが好ましい。 B 2 O 3 is a network-forming component of glass and has a function of improving the thermal stability of glass. On the other hand, when the content of B 2 O 3 is large, the devitrification resistance tends to decrease. Therefore, the content of B 2 O 3 is preferably in the above range.
　上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおいて、ＴｉＯ２の含有量の下限は、好ましくは０％であり、さらには１％、２％、３％、４％、６％、８％、１０％、１２％の順により好ましい。ＴｉＯ２の含有量は０％でもよい。また、ＴｉＯ２の含有量の上限は、好ましくは１５％である。 In the optical glass according to the first embodiment satisfying the above (B), the lower limit of the content of TiO 2 is preferably 0%, and further 1%, 2%, 3%, 4%, 6%, 8 %, 10%, and 12% are more preferable. The content of TiO 2 may be 0%. The upper limit of the TiO 2 content is preferably 15%.
　ＴｉＯ２は、高分散化に大きく寄与する。一方、ＴｉＯ２は、比較的ガラスの着色を増大させやすく、また、熔融性を悪化させるおそれがある。そのためＴｉＯ２の含有量は上記範囲であることが好ましい。 TiO 2 greatly contributes to high dispersion. On the other hand, TiO 2 tends to increase the coloring of the glass relatively easily, and may deteriorate the meltability. Therefore, the content of TiO 2 is preferably in the above range.
　上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおいて、ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３およびＢｉ２Ｏ３の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３］の下限は、好ましくは３６％であり、さらには３８％、４０％、４１％、４２％の順により好ましい。また、合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３］の上限は、好ましくは５８％であり、さらには５６％、５４％、５２％、５０％、４８％、４６％の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (B), the total content of TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 ] The lower limit is preferably 36%, more preferably 38%, 40%, 41%, and 42% in that order. The upper limit of the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 ] is preferably 58%, further 56%, 54%, 52%, 50%, 48%, 46%. More preferred in order.
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３およびＢｉ２Ｏ３は、ガラスの高分散化に寄与し、また、適量を含有させることにより、ガラスの熱的安定性を改善する働きも有する。一方、ガラスの着色を増大させる成分でもある。したがって、合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３］は上記範囲であることが好ましい。 TiO 2 , Nb 2 O 5 , WO 3 and Bi 2 O 3 contribute to high dispersion of glass, and also have a function of improving the thermal stability of glass by containing an appropriate amount. On the other hand, it is also a component that increases the coloring of glass. Therefore, the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 ] is preferably in the above range.
　上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおいて、Ｎａ２Ｏの含有量の下限は、好ましくは６％であり、さらには８％、９％、１０％の順により好ましい。また、Ｎａ２Ｏの含有量の上限は、好ましくは３０％であり、さらには２８％、２６％、２５％、２２％、２０％、１８％、１７％の順にさらに好ましい。 In the optical glass according to the first embodiment satisfying the above (B), the lower limit of the Na 2 O content is preferably 6%, more preferably 8%, 9%, and 10%. The upper limit of the Na 2 O content is preferably 30%, and more preferably 28%, 26%, 25%, 22%, 20%, 18%, and 17% in that order.
　Ｎａ２Ｏは、ガラスの低比重化に寄与する成分であり、ガラスの熔融性を改善し、また平均線熱膨張係数を大きくする働きを有する。一方、Ｎａ２Ｏの含有量が多くなると、耐失透性が低下する。したがって、Ｎａ２Ｏの含有量は上記範囲であることが好ましい。 Na 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion. On the other hand, as the Na 2 O content increases, the devitrification resistance decreases. Therefore, the Na 2 O content is preferably in the above range.
　上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏ、Ｎａ２ＯおよびＫ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ］の上限は、好ましくは３５％であり、さらには３３％、３１％、３０％、２８％、２７％、２６％、２５％の順に好ましい。また、該合計含有量の下限は、好ましくは１０％であり、さらには１４％、１７％、１８％、２０％の順により好ましい。 In the optical glass according to the first embodiment satisfying the above (B), the upper limit of the total content [Li 2 O + Na 2 O + K 2 O] of Li 2 O, Na 2 O and K 2 O is preferably 35%. Further, 33%, 31%, 30%, 28%, 27%, 26%, and 25% are preferable in this order. The lower limit of the total content is preferably 10%, more preferably 14%, 17%, 18%, and 20%.
　Ｌｉ２Ｏ、Ｎａ２ＯおよびＫ２Ｏは、いずれもガラスの熱的安定性を改善する働きを有する。しかし、これらの含有量が多くなると、化学的耐久性、耐候性が低下するおそれがある。そのため、Ｌｉ２Ｏ、Ｎａ２ＯおよびＫ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ］は上記範囲であることが好ましい。 Li 2 O, Na 2 O and K 2 O all have a function of improving the thermal stability of glass. However, if these contents are high, the chemical durability and weather resistance may be lowered. Therefore, the total content of Li 2 O, Na 2 O and K 2 O [Li 2 O + Na 2 O + K 2 O] is preferably in the above range.
　上記（Ｂ）を満たす第１実施形態に係る光学ガラスにおいて、Ｎｂ２Ｏ５の含有量は２５～５５％である。Ｎｂ２Ｏ５の含有量の下限は、好ましくは２７％であり、より好ましくは２９％である。また、Ｎｂ２Ｏ５の含有量の上限は、好ましくは５３％であり、さらには５１％、４９％、４７％、４０％、３５％、３３％の順に好ましい。 The content of Nb 2 O 5 in the optical glass according to the first embodiment satisfying the above (B) is 25 to 55%. The lower limit of the content of Nb 2 O 5 is preferably 27%, more preferably 29%. The upper limit of the content of Nb 2 O 5 is preferably 53%, and more preferably 51%, 49%, 47%, 40%, 35%, and 33% in that order.
　Ｎｂ２Ｏ５は、高屈折率化および高分散化に寄与する成分である。したがって、Ｎｂ２Ｏ５の含有量は上記範囲とすることで、所望の光学恒数を有する光学ガラスが得られる。一方、Ｎｂ２Ｏ５の含有量が多すぎると、ガラスの着色が強まるおそれがある。 Nb 2 O 5 is a component that contributes to high refractive index and high dispersion. Therefore, by setting the content of Nb 2 O 5 in the above range, an optical glass having a desired optical constant can be obtained. On the other hand, if the content of Nb 2 O 5 is too large, the coloring of the glass may be strengthened.
　次に、第１実施形態に係る光学ガラスの特性について説明する。 Next, the characteristics of the optical glass according to the first embodiment will be described.
　第１実施形態に係る光学ガラスにおいて、１００～３００℃の平均線熱膨張係数αの下限は、好ましくは１００×１０－７℃－１であり、さらには１０５×１０－７℃－１、１１０×１０－７℃－１、１１５×１０－７℃－１、１２０×１０－７℃－１の順により好ましい。また、平均線熱膨張係数αの上限は、より好ましくは２００×１０－７℃－１であり、さらには１９０×１０－７℃－１、１８０×１０－７℃－１、１７０×１０－７℃－１、１６０×１０－７℃－１の順により好ましい。 In the optical glass according to the first embodiment, the lower limit of the average coefficient of linear thermal expansion α of 100 to 300 ° C. is preferably 100 × 10 -7 ° C. -1 , and further 105 × 10 -7 ° C. -1 , 110. It is more preferable in the order of × 10 -7 ° C -1 , 115 × 10 -7 ° C -1 , and 120 × 10 -7 ° C -1. The upper limit of the average coefficient of linear thermal expansion α is more preferably 200 × 10 -7 ℃ -1 , and further 190 × 10 -7 ℃ -1 , 180 × 10 -7 ℃ -1 , 170 × 10 −. It is more preferable in the order of 7 ° C -1 and 160 × 10 -7 ° C -1.
　１００～３００℃の平均線膨張係数αを上記範囲とすることで、ガラスの熱膨張に伴う屈折率の変化、すなわち、相対屈折率の温度係数ｄｎ／ｄＴの増大を抑制することができる。 By setting the average linear expansion coefficient α of 100 to 300 ° C. in the above range, it is possible to suppress a change in the refractive index due to thermal expansion of the glass, that is, an increase in the temperature coefficient dn / dT of the relative refractive index.
　平均線膨張係数αは、ＪＯＧＩＳ０８－２００３の規定に基づいて測定される。但し、試料は長さ２０ｍｍ±０．５ｍｍ、直径５ｍｍ±０．５ｍｍの丸棒とし、試料に９８ｍＮの荷重を印加した状態で、４℃毎分の一定速度で上昇するように加熱し、温度と試料の伸びを測定する。
　なお、本明細書では、平均線膨張係数αを［℃－１］の単位で表しているが、単位として［Ｋ－１］を用いた場合でも平均線膨張係数αの数値は同じである。 The average coefficient of linear expansion α is measured based on the provisions of JOBIS08-2003. However, the sample shall be a round bar with a length of 20 mm ± 0.5 mm and a diameter of 5 mm ± 0.5 mm, and with a load of 98 mN applied to the sample, it shall be heated so as to rise at a constant rate of 4 ° C. And measure the elongation of the sample.
In this specification, the average coefficient of linear expansion α is expressed in the unit of [° C -1 ], but the numerical value of the average coefficient of linear expansion α is the same even when [K -1] is used as the unit.
　第１実施形態に係る光学ガラスにおいて、Ｈｅ－Ｎｅレーザの波長（６３３ｎｍ）における相対屈折率の温度係数ｄｎ／ｄＴは、２０～４０℃の範囲で、好ましくは－１．０×１０－６～－１０．０×１０－６℃－１であり、さらには－１．５×１０－６～－９．０×１０－６℃－１、－２．０×１０－６～－８．０×１０－６℃－１、－２．５×１０－６～－７．０×１０－６℃－１、－３．０×１０－６～－６．５×１０－６℃－１の順により好ましい。 In the optical glass according to the first embodiment, the temperature coefficient dn / dT of the relative refractive index at the wavelength (633 nm) of the He—Ne laser is in the range of 20 to 40 ° C., preferably −1.0 × 10-6 to. -10.0 x 10 -6 ° C -1 , and further -1.5 x 10 -6 to -9.0 x 10 -6 ° C -1 , -2.0 x 10 -6 to -8.0. × 10 -6 ℃ -1 , -2.5 × 10 -6 ~ -7.0 × 10 -6 ℃ -1 , -3.0 × 10 -6 ~ -6. × 10 -6 ℃ -1 More preferred in order.
　ｄｎ／ｄＴを上記範囲とし、ｄｎ／ｄＴがプラスの光学素子と組み合わせることで、光学素子の温度が大きく変動するような環境下でも屈折率の変動が小さくなるため、より幅広い温度範囲において、所望の光学特性を高精度に発揮できる。 By setting dn / dT in the above range and combining it with an optical element having a positive dn / dT, the fluctuation of the refractive index becomes small even in an environment where the temperature of the optical element fluctuates greatly. The optical characteristics of the above can be exhibited with high accuracy.
　相対屈折率の温度係数ｄｎ／ｄＴは、ＪＯＧＩＳ１８－２００８の干渉法に基づいて測定される。
　なお、第１明細書では、温度係数ｄｎ／ｄＴを［℃－１］の単位で表しているが、単位として［Ｋ－１］を用いた場合でも温度係数ｄｎ／ｄＴの数値は同じである。 The temperature coefficient dn / dT of the relative refractive index is measured based on the interferometry of JOBIS18-2008.
In the first specification, the temperature coefficient dn / dT is expressed in the unit of [° C-1 ], but the numerical value of the temperature coefficient dn / dT is the same even when [K -1] is used as the unit. ..
　（ガラス成分）
　第１実施形態に係る光学ガラスにおける上記以外のガラス成分の含有量および比率について、以下に非制限的な例を示す。 (Glass component)
Non-limiting examples of the content and ratio of glass components other than the above in the optical glass according to the first embodiment are shown below.
　第１実施形態に係る光学ガラスにおいて、ＳｉＯ２の含有量の上限は、好ましくは５％であり、さらには３％、２％、１％の順により好ましい。ＳｉＯ２の含有量は０％でもよい。 In the optical glass according to the first embodiment, the upper limit of the content of SiO 2 is preferably 5%, more preferably 3%, 2%, and 1%. The content of SiO 2 may be 0%.
　なお、ガラスの熔融に石英ガラス製坩堝などの石英ガラス製の熔融器具を使用することがある。この場合、熔融器具からガラス熔融物に少量のＳｉＯ２が溶け込むため、ガラス原料がＳｉＯ２を含んでいなくても作製したガラスは少量のＳｉＯ２を含有する。石英ガラス製の熔融器具からガラスに混入するＳｉＯ２の量は熔融条件にもよるが、例えば、全ガラス成分の含有量の合計に対し、０．５～１質量％程度である。ＳｉＯ２以外のガラス成分の含有比は一定のまま、ＳｉＯ２の量が０．５～１質量％程度増加する。なお、熔解条件によって上記量は増減する。ＳｉＯ２の含有量によって、屈折率、アッベ数などの光学特性が変化するので、ＳｉＯ２以外のガラス成分の含有量を微調整して所望の光学特性を有する光学ガラスを得る。 A quartz glass melting device such as a quartz glass crucible may be used to melt the glass. In this case, since a small amount of SiO 2 melts into the glass melt from the melting device, the glass frit is produced be free of SiO 2 contains a small amount of SiO 2. The amount of SiO 2 mixed into the glass from the quartz glass melting device depends on the melting conditions, but is, for example, about 0.5 to 1% by mass with respect to the total content of all glass components. The amount of SiO 2 increases by about 0.5 to 1% by mass while the content ratio of the glass component other than SiO 2 remains constant. The above amount may increase or decrease depending on the melting conditions. Since the optical characteristics such as the refractive index and the Abbe number change depending on the content of SiO 2, the content of the glass component other than SiO 2 is finely adjusted to obtain an optical glass having desired optical characteristics.
　ＳｉＯ２は、ガラスのネットワーク形成成分であり、ガラスの熱的安定性、化学的耐久性、耐候性を改善し、熔融ガラスの粘度を高め、熔融ガラスを成形しやすくする働きを有する。一方、ＳｉＯ２の含有量が多いと、ガラスの耐失透性が低下する傾向がある。そのため、ＳｉＯ２の含有量の上限は上記範囲であることが好ましい。 SiO 2 is a network-forming component of glass, and has a function of improving thermal stability, chemical durability, and weather resistance of glass, increasing the viscosity of molten glass, and facilitating molding of molten glass. On the other hand, when the content of SiO 2 is large, the devitrification resistance of the glass tends to decrease. Therefore, the upper limit of the content of SiO 2 is preferably in the above range.
　第１実施形態において、Ｂｉ２Ｏ３の含有量の上限は、好ましくは１５％であり、さらには１０％、７％、５％、３％の順により好ましい。また、Ｂｉ２Ｏ３の含有量の下限は、好ましくは０％である。 In the first embodiment, the upper limit of the content of Bi 2 O 3 is preferably 15%, more preferably 10%, 7%, 5%, and 3% in that order. The lower limit of the Bi 2 O 3 content is preferably 0%.
　Ｂｉ２Ｏ３は、適量を含有させることによりガラスの熱的安定性を改善する働きを有する。一方、Ｂｉ２Ｏ３の含有量を高めると、ガラスの着色が増大する。したがって、Ｂｉ２Ｏ３の含有量は上記範囲であることが好ましい。 Bi 2 O 3 has a function of improving the thermal stability of glass by containing an appropriate amount. On the other hand, when the content of Bi 2 O 3 is increased, the coloring of the glass is increased. Therefore, the content of Bi 2 O 3 is preferably in the above range.
　第１実施形態に係る光学ガラスにおいて、Ｔａ２Ｏ５の含有量の上限は、好ましくは１０％であり、さらには７％、５％、３％の順により好ましい。また、Ｔａ２Ｏ５の含有量の下限は、好ましくは０％である。Ｔａ２Ｏ５の含有量は０％でもよい。 In the optical glass according to the first embodiment, the upper limit of the content of Ta 2 O 5 is preferably 10%, more preferably 7%, 5%, and 3%. The lower limit of the content of Ta 2 O 5 is preferably 0%. The content of Ta 2 O 5 may be 0%.
　Ｔａ２Ｏ５は、ガラスの熱的安定性および耐失透性を改善する働きを有するガラス成分である。一方、Ｔａ２Ｏ５は、屈折率を上昇させ、ガラスを高分散化させる。また、Ｔａ２Ｏ５の含有量が多くなると、ガラスの熱的安定性が低下し、ガラスを熔融するときに、ガラス原料の熔け残りが生じやすくなる。そのため、Ｔａ２Ｏ５の含有量は上記範囲であることが好ましい。さらに、Ｔａ２Ｏ５は、他のガラス成分と比較し、極めて高価な成分であり、Ｔａ２Ｏ５の含有量が多くなるとガラスの生産コストが増大する。さらに、Ｔａ２Ｏ５は他のガラス成分と比べて分子量が大きいため、ガラスの比重を増大させ、結果的に光学素子の重量を増大させる。 Ta 2 O 5 is a glass component having a function of improving the thermal stability and devitrification resistance of glass. On the other hand, Ta 2 O 5 increases the refractive index and makes the glass highly dispersed. Further, when the content of Ta 2 O 5 is increased, the thermal stability of the glass is lowered, and when the glass is melted, the unmelted residue of the glass raw material is likely to occur. Therefore, the content of Ta 2 O 5 is preferably in the above range. Further, Ta 2 O 5 is an extremely expensive component as compared with other glass components, and as the content of Ta 2 O 5 increases, the production cost of glass increases. Further, since Ta 2 O 5 has a larger molecular weight than other glass components, it increases the specific gravity of the glass, and as a result, increases the weight of the optical element.
　第１実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏの含有量の上限は、好ましくは５％であり、さらには３％、２％、１％の順により好ましい。Ｌｉ２Ｏの含有量の下限は、好ましくは０％である。Ｌｉ２Ｏの含有量は０％でもよい。 In the optical glass according to the first embodiment, the upper limit of the Li 2 O content is preferably 5%, more preferably 3%, 2%, and 1%. The lower limit of the Li 2 O content is preferably 0%. The content of Li 2 O may be 0%.
　Ｌｉ２Ｏは、ガラスの低比重化に寄与する成分であり、ガラスの熔融性を改善し、また平均線熱膨張係数を大きくする働きを有する。一方、Ｌｉ２Ｏの含有量が多くなると、耐失透性が低下する。したがって、Ｌｉ２Ｏの含有量は上記範囲であることが好ましい。 Li 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion. On the other hand, as the content of Li 2 O increases, the devitrification resistance decreases. Therefore, the Li 2 O content is preferably in the above range.
　第１実施形態に係る光学ガラスにおいて、Ｋ２Ｏの含有量の下限は、好ましくは１％であり、さらには２％、３％、４％の順により好ましい。また、Ｋ２Ｏの含有量の上限は、好ましくは１３％であり、さらには１２％、１１％、１０％の順により好ましい。 In the optical glass according to the first embodiment, the lower limit of K 2 O content is preferably 1%, even 2%, 3%, preferably by 4% order. The upper limit of the content of K 2 O is preferably 13%, further 12%, 11%, preferably by 10% order.
　Ｋ２Ｏは、ガラスの低比重化に寄与する成分であり、ガラスの熱的安定性を改善する働きを有する。また平均線熱膨張係数を大きくする働きを有する。一方、Ｋ２Ｏの含有量が多くなると、熱的安定性が低下し、ガラス化時に脈理が発生しやすくなる。したがって、Ｋ２Ｏの含有量は上記範囲であることが好ましい。 K 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the thermal stability of glass. It also has the function of increasing the average coefficient of linear thermal expansion. On the other hand, when the content of K 2 O is large, the thermal stability is lowered and the veins are likely to occur at the time of vitrification. Therefore, it is preferable that the content of K 2 O is within the above range.
　第１実施形態に係る光学ガラスにおいて、Ｃｓ２Ｏの含有量の上限は、好ましくは５％であり、さらには３％、２％、１％の順により好ましい。また、Ｃｓ２Ｏの含有量の下限は、好ましくは０％である。Ｃｓ２Ｏの含有量は０％でもよい。 In the optical glass according to the first embodiment, the upper limit of the content of Cs 2 O is preferably 5%, more preferably 3%, 2%, and 1%. The lower limit of the Cs 2 O content is preferably 0%. The content of Cs 2 O may be 0%.
　Ｃｓ２Ｏは、ガラスの熔融性を改善する働きを有するが、含有量が多くなると、ガラスの熱的安定性、屈折率ｎｄが低下し、また熔解中にガラス成分の揮発が増加して、所望のガラスが得られなくなる。そのため、Ｃｓ２Ｏの含有量は上記範囲であることが好ましい。 Cs 2 O has a function of improving the meltability of glass, but when the content is increased, the thermal stability and refractive index nd of the glass are lowered, and the volatilization of the glass component is increased during melting. The desired glass cannot be obtained. Therefore, the content of Cs 2 O is preferably in the above range.
　第１実施形態に係る光学ガラスにおいて、ＭｇＯの含有量は、好ましくは５％以下であり、さらには３％以下、１％以下の順により好ましい。また、ＭｇＯの含有量の下限は、好ましくは０％である。ＭｇＯの含有量は０％であってもよい。 In the optical glass according to the first embodiment, the content of MgO is preferably 5% or less, more preferably 3% or less and 1% or less. The lower limit of the MgO content is preferably 0%. The content of MgO may be 0%.
　第１実施形態に係る光学ガラスにおいて、ＣａＯの含有量は、好ましくは５％以下であり、さらには３％以下、１％以下の順により好ましい。また、ＣａＯの含有量の下限は、好ましくは０％である。ＣａＯの含有量は０％であってもよい。 In the optical glass according to the first embodiment, the CaO content is preferably 5% or less, more preferably 3% or less and 1% or less. The lower limit of the CaO content is preferably 0%. The CaO content may be 0%.
　第１実施形態に係る光学ガラスにおいて、ＳｒＯの含有量は、好ましくは６％以下であり、さらには５％以下、３％以下、１％以下の順により好ましい。また、ＳｒＯの含有量の下限は、好ましくは０％である。 In the optical glass according to the first embodiment, the SrO content is preferably 6% or less, more preferably 5% or less, 3% or less, and 1% or less. The lower limit of the SrO content is preferably 0%.
　第１実施形態に係る光学ガラスにおいて、ＢａＯの含有量は、好ましくは８％以下であり、さらには５％以下、３％以下、１％以下の順により好ましい。また、ＢａＯの含有量の下限は、好ましくは０％である。 In the optical glass according to the first embodiment, the BaO content is preferably 8% or less, more preferably 5% or less, 3% or less, and 1% or less. The lower limit of the BaO content is preferably 0%.
　ＭｇＯ、ＣａＯ、ＳｒＯ、ＢａＯは、いずれもガラスの熱的安定性および耐失透性を改善する働きを有するガラス成分である。しかし、これらガラス成分の含有量が多くなると、高分散性が損なわれ、また、ガラスの熱的安定性および耐失透性が低下する。そのため、これらガラス成分の各含有量は、それぞれ上記範囲であることが好ましい。 MgO, CaO, SrO, and BaO are all glass components having a function of improving the thermal stability and devitrification resistance of glass. However, when the content of these glass components is increased, the high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass are lowered. Therefore, the content of each of these glass components is preferably in the above range.
　第１実施形態に係る光学ガラスにおいて、ＺｎＯの含有量の上限は、好ましくは１０％であり、さらには６％、４％、３％の順により好ましい。ＺｎＯ含有量は少ない方が好ましく、その下限は好ましくは０％である。ＺｎＯの含有量は０％でもよい。 In the optical glass according to the first embodiment, the upper limit of the ZnO content is preferably 10%, more preferably 6%, 4%, and 3%. The ZnO content is preferably low, and the lower limit thereof is preferably 0%. The ZnO content may be 0%.
　ＺｎＯは、ガラスの熱的安定性を改善する働きを有するガラス成分である。しかし、ＺｎＯの含有量が多すぎるとガラスの比重が増大する。また、相対屈折率の温度係数（ｄｎ／ｄＴ）が高くなる。そのため、ＺｎＯの含有量は上記範囲であることが好ましい。 ZnO is a glass component having a function of improving the thermal stability of glass. However, if the ZnO content is too high, the specific gravity of the glass increases. Further, the temperature coefficient (dn / dT) of the relative refractive index becomes high. Therefore, the ZnO content is preferably in the above range.
　第１実施形態に係る光学ガラスにおいて、ＺｒＯ２の含有量は、好ましくは５％以下であり、さらには３％以下、１％以下の順により好ましい。また、ＺｒＯ２の含有量の下限は、好ましくは０％である。 In the optical glass according to the first embodiment, the content of ZrO 2 is preferably 5% or less, more preferably 3% or less and 1% or less. The lower limit of the ZrO 2 content is preferably 0%.
　ＺｒＯ２は、ガラスの熱的安定性および耐失透性を改善する働きを有するガラス成分である。しかし、ＺｒＯ２の含有量が多すぎると、熱的安定性が低下する傾向を示す。そのため、ＺｒＯ２の含有量は上記範囲であることが好ましい。 ZrO 2 is a glass component having a function of improving the thermal stability and devitrification resistance of glass. However, if the content of ZrO 2 is too high, the thermal stability tends to decrease. Therefore, the content of ZrO 2 is preferably in the above range.
　第１実施形態に係る光学ガラスにおいて、Ｓｃ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｓｃ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the first embodiment, the upper limit of the Sc 2 O 3 content is preferably 2%. The lower limit of the Sc 2 O 3 content is preferably 0%.
　第１実施形態に係る光学ガラスにおいて、ＨｆＯ２の含有量の上限は、好ましくは２％である。また、ＨｆＯ２の含有量の下限は、好ましくは０％である。 In the optical glass according to the first embodiment, the upper limit of the HfO 2 content is preferably 2%. The lower limit of the HfO 2 content is preferably 0%.
　Ｓｃ２Ｏ３、ＨｆＯ２は、いずれも屈折率ｎｄを高める働きを有し、また高価な成分である。そのため、Ｓｃ２Ｏ３、ＨｆＯ２の各含有量は上記範囲であることが好ましい。 Sc 2 O 3 and HfO 2 both have a function of increasing the refractive index nd and are expensive components. Therefore, the contents of Sc 2 O 3 and HfO 2 are preferably in the above range.
　第１実施形態に係る光学ガラスにおいて、Ｌｕ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｌｕ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the first embodiment, the upper limit of the content of Lu 2 O 3 is preferably 2%. The lower limit of the content of Lu 2 O 3 is preferably 0%.
　Ｌｕ２Ｏ３は、屈折率ｎｄを高める働きを有する。また、分子量が大きいことから、ガラスの比重を増加させるガラス成分でもある。そのため、Ｌｕ２Ｏ３の含有量は上記範囲であることが好ましい。 Lu 2 O 3 has a function of increasing the refractive index nd. In addition, since it has a large molecular weight, it is also a glass component that increases the specific gravity of glass. Therefore, the content of Lu 2 O 3 is preferably in the above range.
　第１実施形態に係る光学ガラスにおいて、ＧｅＯ２の含有量の上限は、好ましくは２％である。また、ＧｅＯ２の含有量の下限は、好ましくは０％である。 In the optical glass according to the first embodiment, the upper limit of the content of GeO 2 is preferably 2%. The lower limit of the content of GeO 2 is preferably 0%.
　ＧｅＯ２は、屈折率ｎｄを高める働きを有し、また、一般的に使用されるガラス成分の中で、突出して高価な成分である。したがって、ガラスの製造コストを低減する観点から、ＧｅＯ２の含有量は上記範囲であることが好ましい。 GeO 2 has a function of increasing the refractive index nd, and is a prominently expensive component among commonly used glass components. Therefore, from the viewpoint of reducing the manufacturing cost of glass, the content of GeO 2 is preferably in the above range.
　第１実施形態に係る光学ガラスにおいて、Ｌａ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｌａ２Ｏ３の含有量の下限は、好ましくは０％である。Ｌａ２Ｏ３の含有量は０％であってもよい。 In the optical glass according to the first embodiment, the upper limit of the content of La 2 O 3 is preferably 2%. The lower limit of the content of La 2 O 3 is preferably 0%. The content of La 2 O 3 may be 0%.
　Ｌａ２Ｏ３の含有量が多くなるとガラスの熱的安定性および耐失透性が低下し、製造中にガラスが失透しやすくなる。したがって、熱的安定性および耐失透性の低下を抑制する観点から、Ｌａ２Ｏ３の含有量は上記範囲であることが好ましい。 When the content of La 2 O 3 is increased, the thermal stability and devitrification resistance of the glass are lowered, and the glass is easily devitrified during production. Therefore, the content of La 2 O 3 is preferably in the above range from the viewpoint of suppressing the decrease in thermal stability and devitrification resistance.
　第１実施形態に係る光学ガラスにおいて、Ｇｄ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｇｄ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the first embodiment, the upper limit of the content of Gd 2 O 3 is preferably 2%. The lower limit of the content of Gd 2 O 3 is preferably 0%.
　Ｇｄ２Ｏ３の含有量が多くなり過ぎるとガラスの熱的安定性および耐失透性が低下し、製造中にガラスが失透しやすくなる。また、Ｇｄ２Ｏ３の含有量が多くなり過ぎるとガラスの比重が増大し、好ましくない。したがって、ガラスの熱的安定性および耐失透性を良好に維持しつつ、比重の増大を抑制する観点から、Ｇｄ２Ｏ３の含有量は上記範囲であることが好ましい。 If the content of Gd 2 O 3 is too high, the thermal stability and devitrification resistance of the glass will decrease, and the glass will easily devitrify during production. Further, if the content of Gd 2 O 3 becomes too large, the specific gravity of the glass increases, which is not preferable. Therefore, the content of Gd 2 O 3 is preferably in the above range from the viewpoint of suppressing an increase in specific gravity while maintaining good thermal stability and devitrification resistance of the glass.
　第１実施形態に係る光学ガラスにおいて、Ｙ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｙ２Ｏ３の含有量の下限は、好ましくは０％である。Ｙ２Ｏ３の含有量は０％であってもよい。 In the optical glass according to the first embodiment, the upper limit of the content of Y 2 O 3 is preferably 2%. The lower limit of the content of Y 2 O 3 is preferably 0%. The content of Y 2 O 3 may be 0%.
　Ｙ２Ｏ３の含有量が多くなり過ぎるとガラスの熱的安定性および耐失透性が低下する。したがって、熱的安定性および耐失透性の低下を抑制する観点から、Ｙ２Ｏ３の含有量は上記範囲であることが好ましい。 If the content of Y 2 O 3 is too high, the thermal stability and devitrification resistance of the glass will decrease. Therefore, from the viewpoint of suppressing a decrease in the thermal stability and devitrification resistance, the content of Y 2 O 3 is preferably in the range.
　第１実施形態に係る光学ガラスにおいて、Ｙｂ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｙｂ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the first embodiment, the upper limit of the content of Yb 2 O 3 is preferably 2%. The lower limit of the content of Yb 2 O 3 is preferably 0%.
　Ｙｂ２Ｏ３は、Ｌａ２Ｏ３、Ｇｄ２Ｏ３、Ｙ２Ｏ３と比べて分子量が大きいため、ガラスの比重を増大させる。ガラスの比重が増大すると、光学素子の質量が増大する。例えば、質量の大きいレンズをオートフォーカス式の撮像レンズに組み込むと、オートフォーカス時にレンズの駆動に要する電力が増大し、電池の消耗が激しくなる。したがって、Ｙｂ２Ｏ３の含有量を低減させて、ガラスの比重の増大を抑えることが望ましい。 Since Yb 2 O 3 has a larger molecular weight than La 2 O 3 , Gd 2 O 3 , and Y 2 O 3 , it increases the specific gravity of glass. As the specific gravity of glass increases, the mass of the optical element increases. For example, if a lens having a large mass is incorporated into an autofocus type imaging lens, the power required to drive the lens during autofocus increases, and the battery consumption increases. Therefore, it is desirable to reduce the content of Yb 2 O 3 to suppress the increase in the specific gravity of the glass.
　また、Ｙｂ２Ｏ３の含有量が多すぎるとガラスの熱的安定性および耐失透性が低下する。ガラスの熱的安定性の低下を防ぎ、比重の増大を抑制する観点から、Ｙｂ２Ｏ３の含有量は上記範囲であることが好ましい。 Further, if the content of Yb 2 O 3 is too large, the thermal stability and devitrification resistance of the glass are lowered. The content of Yb 2 O 3 is preferably in the above range from the viewpoint of preventing a decrease in thermal stability of the glass and suppressing an increase in specific gravity.
　上記（Ａ）を満たす第１実施形態に係る光学ガラスは、主として上述のガラス成分、すなわち、必須成分としてＰ２Ｏ５、Ｎｂ２Ｏ５、Ｂ２Ｏ３、任意成分としてＷＯ３、ＳｉＯ２、Ａｌ２Ｏ３、ＴｉＯ２、Ｂｉ２Ｏ３、Ｔａ２Ｏ５、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２Ｏ、Ｃｓ２Ｏ、ＭｇＯ、ＣａＯ、ＳｒＯ、ＢａＯ、ＺｎＯ、ＺｒＯ２、Ｓｃ２Ｏ３、ＨｆＯ２、Ｌｕ２Ｏ３、ＧｅＯ２、Ｌａ２Ｏ３、Ｇｄ２Ｏ３、Ｙ２Ｏ３、およびＹｂ２Ｏ３で構成されていることが好ましく、上述のガラス成分の合計含有量は、９５％以上が好ましく、９８％以上より好ましく、９９％以上がさらに好ましく、９９．５％以上が一層好ましい。 The optical glass according to the first embodiment satisfying the above (A) is mainly composed of the above-mentioned glass components, that is, P 2 O 5 , Nb 2 O 5 , B 2 O 3 as essential components, and WO 3 , SiO 2 as optional components. , Al 2 O 3 , TiO 2 , Bi 2 O 3 , Ta 2 O 5 , Li 2 O, Na 2 O, K 2 O, Cs 2 O, MgO, CaO, SrO, BaO, ZnO, ZrO 2 , Sc 2 It is preferably composed of O 3 , HfO 2 , Lu 2 O 3 , GeO 2 , La 2 O 3 , Gd 2 O 3 , Y 2 O 3 , and Yb 2 O 3 , and contains the total amount of the above-mentioned glass components. The amount is preferably 95% or more, more preferably 98% or more, further preferably 99% or more, still more preferably 99.5% or more.
　また、上記（Ｂ）を満たす第１実施形態に係る光学ガラスは、主として上述のガラス成分、すなわち、必須成分としてＰ２Ｏ５、Ｎｂ２Ｏ５、任意成分としてＢ２Ｏ３、ＷＯ３、ＳｉＯ２、Ａｌ２Ｏ３、ＴｉＯ２、Ｂｉ２Ｏ３、Ｔａ２Ｏ５、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２Ｏ、Ｃｓ２Ｏ、ＭｇＯ、ＣａＯ、ＳｒＯ、ＢａＯ、ＺｎＯ、ＺｒＯ２、Ｓｃ２Ｏ３、ＨｆＯ２、Ｌｕ２Ｏ３、ＧｅＯ２、Ｌａ２Ｏ３、Ｇｄ２Ｏ３、Ｙ２Ｏ３、およびＹｂ２Ｏ３で構成されていることが好ましく、上述のガラス成分の合計含有量は、９５％以上が好ましく、９８％以上より好ましく、９９％以上がさらに好ましく、９９．５％以上が一層好ましい。 Further, the optical glass according to the first embodiment satisfying the above (B) is mainly composed of the above-mentioned glass components, that is, P 2 O 5 and Nb 2 O 5 as essential components, and B 2 O 3 and WO 3 as optional components. SiO 2 , Al 2 O 3 , TiO 2 , Bi 2 O 3 , Ta 2 O 5 , Li 2 O, Na 2 O, K 2 O, Cs 2 O, MgO, CaO, SrO, BaO, ZnO, ZrO 2 , It is preferably composed of Sc 2 O 3 , HfO 2 , Lu 2 O 3 , GeO 2 , La 2 O 3 , Gd 2 O 3 , Y 2 O 3 , and Yb 2 O 3 , which are the above-mentioned glass components. The total content is preferably 95% or more, more preferably 98% or more, further preferably 99% or more, still more preferably 99.5% or more.
　第１実施形態に係る光学ガラスにおいて、ＴｅＯ２の含有量の上限は、好ましくは２％である。また、ＴｅＯ２の含有量の下限は、好ましくは０％である。 In the optical glass according to the first embodiment, the upper limit of the content of TeO 2 is preferably 2%. The lower limit of the content of TeO 2 is preferably 0%.
　ＴｅＯ２は毒性を有することから、ＴｅＯ２の含有量を低減させることが好ましい。そのため、ＴｅＯ２の含有量は上記範囲であることが好ましい。 Since TeO 2 is toxic, it is preferable to reduce the content of TeO 2. Therefore, the content of TeO 2 is preferably in the above range.
　なお、第１実施形態に係る光学ガラスは、基本的に上記ガラス成分により構成されることが好ましいが、本発明の作用効果を妨げない範囲において、その他の成分を含有することも可能である。また、本発明において、不可避的不純物の含有を排除するものではない。 The optical glass according to the first embodiment is basically composed of the above glass components, but it is also possible to contain other components as long as the effects of the present invention are not impaired. Further, in the present invention, the inclusion of unavoidable impurities is not excluded.
＜その他の成分組成＞
　Ｐｂ、Ａｓ、Ｃｄ、Ｔｌ、Ｂｅ、Ｓｅは、いずれも毒性を有する。そのため、第１実施形態に係る光学ガラスがこれら元素をガラス成分として含有しないことが好ましい。 <Other component composition>
Pb, As, Cd, Tl, Be and Se are all toxic. Therefore, it is preferable that the optical glass according to the first embodiment does not contain these elements as a glass component.
　Ｕ、Ｔｈ、Ｒａはいずれも放射性元素である。そのため、第１実施形態に係る光学ガラスがこれら元素をガラス成分として含有しないことが好ましい。 U, Th, and Ra are all radioactive elements. Therefore, it is preferable that the optical glass according to the first embodiment does not contain these elements as a glass component.
　Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍは、ガラスの着色を増大させ、蛍光の発生源となり得る。そのため、第１実施形態に係る光学ガラスがこれら元素をガラス成分として含有しないことが好ましい。 V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm increase the coloring of glass and can be a source of fluorescence. Therefore, it is preferable that the optical glass according to the first embodiment does not contain these elements as a glass component.
　Ｓｂ（Ｓｂ２Ｏ３）、Ｃｅ（ＣｅＯ２）は清澄剤として機能する任意に添加可能な元素である。このうち、Ｓｂ（Ｓｂ２Ｏ３）は、清澄効果の大きな清澄剤である。しかし、Ｓｂ（Ｓｂ２Ｏ３）は酸化性が強く、Ｓｂ（Ｓｂ２Ｏ３）の添加量を多くしていくと、Ｓｂイオンによる光吸収により、ガラスの着色が増大し、好ましくない。また、ガラスを熔融するときに、熔融物中にＳｂがあると、ガラス熔融坩堝を構成する白金の熔融物への溶出が促進され、ガラス中の白金濃度が高くなる。ガラス中において、白金がイオンとして存在すると、光の吸収によりガラスの着色が増大する。また、ガラス中に白金が固形物として存在すると光の散乱源となり、ガラスの品質を低下させる。Ｃｅ（ＣｅＯ２）は、Ｓｂ（Ｓｂ２Ｏ３）と比較し、清澄効果が小さい。Ｃｅ（ＣｅＯ２）は、多量に添加するとガラスの着色が強まる。したがって、清澄剤を添加する場合は、添加量に注意しつつ、Ｓｂ（Ｓｂ２Ｏ３）を添加することが好ましい。 Sb (Sb 2 O 3 ) and Ce (CeO 2 ) are arbitrarily addable elements that function as fining agents. Of these, Sb (Sb 2 O 3 ) is a fining agent having a large fining effect. However, Sb (Sb 2 O 3 ) is highly oxidizing, and if the amount of Sb (Sb 2 O 3 ) added is increased, the coloration of the glass increases due to light absorption by Sb ions, which is not preferable. Further, when the glass is melted, if Sb is present in the melt, the elution of platinum constituting the glass melting crucible into the melt is promoted, and the platinum concentration in the glass becomes high. When platinum is present as ions in the glass, the coloration of the glass increases due to the absorption of light. Further, when platinum exists as a solid substance in the glass, it becomes a light scattering source and deteriorates the quality of the glass. Ce (CeO 2 ) has a smaller clarification effect than Sb (Sb 2 O 3). When Ce (CeO 2 ) is added in a large amount, the coloring of the glass is strengthened. Therefore, when adding a fining agent, it is preferable to add Sb (Sb 2 O 3) while paying attention to the amount of addition.
　Ｓｂ２Ｏ３の含有量は、外割り表示とする。すなわち、Ｓｂ２Ｏ３およびＣｅＯ２以外の全ガラス成分の合計含有量を１００質量％としたときのＳｂ２Ｏ３の含有量は、好ましくは１質量％未満、より好ましくは０．１質量％未満である。さらに、は０．０５質量％未満、０．０３質量％未満、０．０２質量％未満の順に好ましい。Ｓｂ２Ｏ３の含有量は０質量％であってもよい。 The content of Sb 2 O 3 is indicated by external division. That is, when the total content of all glass components other than Sb 2 O 3 and CeO 2 is 100% by mass, the content of Sb 2 O 3 is preferably less than 1% by mass, more preferably 0.1% by mass. Is less than. Further, is preferable in the order of less than 0.05% by mass, less than 0.03% by mass, and less than 0.02% by mass. The content of Sb 2 O 3 may be 0% by mass.
　ＣｅＯ２の含有量も、外割り表示とする。すなわち、ＣｅＯ２、Ｓｂ２Ｏ３以外の全ガラス成分の合計含有量を１００質量％としたときのＣｅＯ２の含有量は、好ましくは２質量％未満、より好ましくは１質量％未満、さらに好ましくは０．５質量％未満、一層好ましくは０．１質量％未満の範囲である。ＣｅＯ２の含有量は０質量％であってもよい。ＣｅＯ２の含有量を上記範囲とすることによりガラスの清澄性を改善できる。 The content of CeO 2 is also indicated by external division. That is, when the total content of all glass components other than CeO 2 and Sb 2 O 3 is 100% by mass, the content of CeO 2 is preferably less than 2% by mass, more preferably less than 1% by mass, and even more preferably. Is in the range of less than 0.5% by mass, more preferably less than 0.1% by mass. The content of CeO 2 may be 0% by mass. By setting the content of CeO 2 in the above range, the clarity of the glass can be improved.
（ガラス特性）
＜ガラス転移温度Ｔｇ＞
　第１実施形態に係る光学ガラスのガラス転移温度Ｔｇは、好ましくは５７０℃以下であり、さらには５６０℃以下、５５０℃以下、５４０℃以下、５３０℃以下の順により好ましい。 (Glass characteristics)
<Glass transition temperature Tg>
The glass transition temperature Tg of the optical glass according to the first embodiment is preferably 570 ° C. or lower, more preferably 560 ° C. or lower, 550 ° C. or lower, 540 ° C. or lower, and 530 ° C. or lower.
　ガラス転移温度Ｔｇの上限が上記範囲を満たすことにより、ガラスの成型温度およびアニール温度の上昇を抑制することができ、プレス成形用設備およびアニール設備への熱的ダメージを軽減できる。また、ガラス転移温度Ｔｇの下限が上記範囲を満たすことにより、所望のアッベ数、屈折率を維持しつつ、ガラスの熱的安定性を良好に維持しやすくなる。 When the upper limit of the glass transition temperature Tg satisfies the above range, it is possible to suppress an increase in the glass molding temperature and the annealing temperature, and it is possible to reduce thermal damage to the press molding equipment and the annealing equipment. Further, when the lower limit of the glass transition temperature Tg satisfies the above range, it becomes easy to maintain good thermal stability of the glass while maintaining a desired Abbe number and refractive index.
＜ガラスの比重＞
　第１実施形態に係る光学ガラスにおいて、比重は、好ましくは３．６０以下であり、さらには、３．５０以下、３．４０以下の順により好ましい。ガラスの比重を低減することができれば、レンズの重量を減少できる。その結果、レンズを搭載するカメラレンズのオートフォーカス駆動の消費電力を低減できる。 <Specific gravity of glass>
In the optical glass according to the first embodiment, the specific gravity is preferably 3.60 or less, and more preferably 3.50 or less and 3.40 or less. If the specific gravity of the glass can be reduced, the weight of the lens can be reduced. As a result, the power consumption of the autofocus drive of the camera lens on which the lens is mounted can be reduced.
＜ガラスの光線透過性＞
　第１実施形態に係る光学ガラスの光線透過性は、着色度λ５により評価できる。
　厚さ１０．０ｍｍ±０．１ｍｍのガラス試料について波長２００～７００ｎｍの範囲で分光透過率を測定し、外部透過率が５％となる波長をλ５とする。 <Light transmission of glass>
The light transmittance of the optical glass according to the first embodiment can be evaluated by the degree of coloring λ5.
The spectral transmittance of a glass sample having a thickness of 10.0 mm ± 0.1 mm is measured in the wavelength range of 200 to 700 nm, and the wavelength at which the external transmittance is 5% is defined as λ5.
　第１実施形態に係る光学ガラスのλ５は、好ましくは４００ｎｍ以下であり、より好ましくは３８０ｎｍ以下であり、さらに好ましくは３７０ｎｍ以下である。 The λ5 of the optical glass according to the first embodiment is preferably 400 nm or less, more preferably 380 nm or less, and further preferably 370 nm or less.
　λ５が短波長化された光学ガラスを用いることで、好適な色再現を可能とする光学素子を提供できる。 By using an optical glass in which λ5 has a shorter wavelength, it is possible to provide an optical element that enables suitable color reproduction.
（光学ガラスの製造）
　本発明の実施形態に係る光学ガラスは、上記所定の組成となるようにガラス原料を調合し、調合したガラス原料により公知のガラス製造方法に従って作製すればよい。例えば、複数種の化合物を調合し、十分混合してバッチ原料とし、バッチ原料を石英坩堝や白金坩堝中に入れて粗熔解（ラフメルト）する。粗熔解によって得られた熔融物を急冷、粉砕してカレットを作製する。さらにカレットを白金坩堝中に入れて加熱、再熔融（リメルト）して熔融ガラスとし、さらに清澄、均質化した後に熔融ガラスを成形し、徐冷して光学ガラスを得る。熔融ガラスの成形、徐冷には、公知の方法を適用すればよい。 (Manufacturing of optical glass)
The optical glass according to the embodiment of the present invention may be produced by blending a glass raw material so as to have the above-mentioned predetermined composition and using the blended glass raw material according to a known glass manufacturing method. For example, a plurality of types of compounds are mixed and sufficiently mixed to obtain a batch raw material, and the batch raw material is placed in a quartz crucible or a platinum crucible for rough melting. The melt obtained by crude melting is rapidly cooled and crushed to prepare a cullet. Further, the cullet is placed in a platinum crucible, heated and remelted to obtain molten glass, and after further clarification and homogenization, the molten glass is formed and slowly cooled to obtain an optical glass. A known method may be applied to the molding and slow cooling of the molten glass.
　なお、ガラス中に所望のガラス成分を所望の含有量となるように導入することができれば、バッチ原料を調合するときに使用する化合物は特に限定されないが、このような化合物として、酸化物、炭酸塩、硝酸塩、水酸化物、フッ化物等が挙げられる。 As long as a desired glass component can be introduced into the glass so as to have a desired content, the compound used when preparing the batch raw material is not particularly limited, and examples of such a compound include oxides and carbonates. Examples thereof include salts, nitrates, hydroxides and fluorides.
（光学素子等の製造）
　本発明の実施形態に係る光学ガラスを使用して光学素子を作製するには、公知の方法を適用すればよい。例えば、ガラス原料を熔融して熔融ガラスとし、この熔融ガラスを鋳型に流し込んで板状に成形し、本発明に係る光学ガラスからなるガラス素材を作製する。得られたガラス素材を適宜、切断、研削、研磨し、プレス成形に適した大きさ、形状のカットピースを作製する。カットピースを加熱、軟化して、公知の方法でプレス成形（リヒートプレス）し、光学素子の形状に近似する光学素子ブランクを作製する。光学素子ブランクをアニールし、公知の方法で研削、研磨して光学素子を作製する。 (Manufacturing of optical elements, etc.)
In order to produce an optical element using the optical glass according to the embodiment of the present invention, a known method may be applied. For example, a glass raw material is melted to obtain molten glass, and the molten glass is poured into a mold to form a plate shape to produce a glass material made of optical glass according to the present invention. The obtained glass material is appropriately cut, ground, and polished to produce a cut piece having a size and shape suitable for press molding. The cut piece is heated and softened, and press-molded (reheat-pressed) by a known method to produce an optical element blank that approximates the shape of the optical element. An optical element blank is annealed and ground and polished by a known method to produce an optical element.
　作製した光学素子の光学機能面には使用目的に応じて、反射防止膜、全反射膜などをコーティングしてもよい。 The optical functional surface of the manufactured optical element may be coated with an antireflection film, a total reflection film, or the like, depending on the purpose of use.
　光学素子としては、球面レンズなどの各種レンズ、プリズム、回折格子などが例示できる。 Examples of optical elements include various lenses such as spherical lenses, prisms, and diffraction gratings.
第２実施形態
　第２実施形態に係る光学ガラスについて詳細に説明する。
　第２実施形態に係る光学ガラスは、
　Ｐ２Ｏ５の含有量が２５～５０質量％であり、
　ＴｉＯ２の含有量が１０～５０質量％であり、
　Ｎｂ２Ｏ５含有量が５～３０質量％であり、
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］が３５～６０質量％であり、
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量に対するＴｉＯ２の含有量の質量比[ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）]が０．２５以上であり、
　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比[（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）]が１．８０以下であり、
　下記（Ａ）または（Ｂ）を満たす。
（Ａ）　ＷＯ３の含有量が７質量％以下である。
（Ｂ）　実質的にＦを含まない。 Second Embodiment The optical glass according to the second embodiment will be described in detail.
The optical glass according to the second embodiment is
The content of P 2 O 5 is 25 to 50% by mass,
The content of TiO 2 is 10 to 50% by mass,
The Nb 2 O 5 content is 5 to 30% by mass,
The total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 35 to 60% by mass. ,
Mass ratio of TiO 2 content to total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more,
Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
The following (A) or (B) is satisfied.
(A) The content of WO 3 is 7% by mass or less.
(B) Substantially contains no F.
　以下、特記しない限り、第２実施形態に係る光学ガラスとは、上記（Ａ）を満たす第２実施形態に係る光学ガラスおよび上記（Ｂ）を満たす第２実施形態に係る光学ガラスを意味するものとする。 Hereinafter, unless otherwise specified, the optical glass according to the second embodiment means the optical glass according to the second embodiment satisfying the above (A) and the optical glass according to the second embodiment satisfying the above (B). And.
　第２実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５の含有量は２５～５０％である。Ｐ２Ｏ５の含有量の下限は、好ましくは２７％であり、さらには２９％、３１％、３２％の順により好ましい。また、Ｐ２Ｏ５の含有量の上限は、好ましくは４２％であり、さらには４０％、３８％、３７％、３６％の順により好ましい。 In the optical glass according to the second embodiment, the content of P 2 O 5 is 25-50%. The lower limit of the content of P 2 O 5 is preferably 27%, more preferably 29%, 31%, and 32% in that order. The upper limit of the content of P 2 O 5 is preferably 42%, more preferably 40%, 38%, 37%, and 36%.
　Ｐ２Ｏ５は、ガラスのネットワーク形成成分であり、ガラス中に高分散成分を多く含有するために必須の成分である。Ｐ２Ｏ５の含有量を上記範囲とすることで、熱的安定性が高く、所望の光学恒数を有する光学ガラスが得られる。 P 2 O 5 is a network-forming component of glass, and is an essential component for containing a large amount of highly dispersed components in glass. By setting the content of P 2 O 5 in the above range, an optical glass having high thermal stability and a desired optical constant can be obtained.
　第２実施形態に係る光学ガラスにおいて、ＴｉＯ２の含有量の１０～５０％である。ＴｉＯ２の含有量の下限は、好ましくは１２％であり、さらには１４％、１５％、１６％、１７％の順により好ましい。また、ＴｉＯ２の含有量の上限は、好ましくは４０％であり、さらには３５％、３０％、２８％、２６％、２４％、２３％の順により好ましい。 In the optical glass according to the second embodiment, the content of TiO 2 is 10 to 50%. The lower limit of the TiO 2 content is preferably 12%, more preferably 14%, 15%, 16%, and 17% in that order. The upper limit of the TiO 2 content is preferably 40%, more preferably 35%, 30%, 28%, 26%, 24%, and 23%.
　ＴｉＯ２は、高分散化に大きく寄与する。一方、ＴｉＯ２は、比較的ガラスの着色を増大させやすく、また、熔融性を悪化させるおそれがある。そのためＴｉＯ２の含有量は上記範囲であることが好ましい。 TiO 2 greatly contributes to high dispersion. On the other hand, TiO 2 tends to increase the coloring of the glass relatively easily, and may deteriorate the meltability. Therefore, the content of TiO 2 is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、Ｎｂ２Ｏ５の含有量は５～３０％である。Ｎｂ２Ｏ５の含有量の下限は、好ましく１０は％であり、さらには１２％、１４％、１６％、１７％、１８％の順により好ましい。また、Ｎｂ２Ｏ５の含有量の上限は、好ましくは２８％であり、さらには２７％、２６％、２５％の順により好ましい。 In the optical glass according to the second embodiment, the content of Nb 2 O 5 is 5 to 30%. The lower limit of the content of Nb 2 O 5 is preferably 10%, more preferably 12%, 14%, 16%, 17%, and 18%. The upper limit of the content of Nb 2 O 5 is preferably 28%, more preferably 27%, 26%, and 25%.
　Ｎｂ２Ｏ５は、高屈折率化および高分散化に寄与する成分である。したがって、Ｎｂ２Ｏ５の含有量は上記範囲とすることで、所望の光学恒数を有する光学ガラスが得られる。一方、Ｎｂ２Ｏ５の含有量が多すぎると、ガラスの着色が強まるおそれがある。 Nb 2 O 5 is a component that contributes to high refractive index and high dispersion. Therefore, by setting the content of Nb 2 O 5 in the above range, an optical glass having a desired optical constant can be obtained. On the other hand, if the content of Nb 2 O 5 is too large, the coloring of the glass may be strengthened.
　第２実施形態に係る光学ガラスにおいて、ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］は３５～６０％である。該合計含有量の下限は、好ましくは３６％であり、さらには３７％、３８％、３９％の順により好ましい。また、該合計含有量の上限は、好ましくは５５％であり、さらには５０％、４７％、４５％、４４％の順により好ましい。 In the optical glass according to the second embodiment, the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 35 to 60%. The lower limit of the total content is preferably 36%, more preferably 37%, 38%, and 39%. The upper limit of the total content is preferably 55%, more preferably 50%, 47%, 45%, and 44%.
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５は、ガラスの高分散化に寄与する成分である。したがって、合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］を上記範囲とすることで、所望の光学恒数を有する光学ガラスが得られる。また、ガラスの熱的安定性も改善できる。一方、該合計含有量が多すぎると、所望の光学恒数を有する光学ガラスが得られないおそれがあり、また、ガラスの熱的安定性が低下し、ガラスの着色が強まるおそれがある。 TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 are components that contribute to high dispersion of glass. Therefore, by setting the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] in the above range, an optical glass having a desired optical constant can be obtained. In addition, the thermal stability of the glass can be improved. On the other hand, if the total content is too large, an optical glass having a desired optical constant may not be obtained, the thermal stability of the glass may be lowered, and the coloring of the glass may be strengthened.
　第２実施形態に係る光学ガラスにおいて、ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］に対するＴｉＯ２の含有量の質量比[ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）]は０．２５以上である。該質量比の下限は、好ましくは０．３０であり、さらには０．３２、０．３４、０．３６、０．３８、０．４０の順により好ましい。また、該質量比の上限は、好ましくは０．６５であり、さらには０．６０、０．５８、０．５６の順により好ましい。 In the optical glass according to the second embodiment, the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O The mass ratio of the content of TiO 2 to 5 ] [TIO 2 / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 )] is 0.25 or more. The lower limit of the mass ratio is preferably 0.30, and more preferably 0.32, 0.34, 0.36, 0.38, 0.40 in that order. The upper limit of the mass ratio is preferably 0.65, more preferably 0.60, 0.58, 0.56 in that order.
　ＴｉＯ２は、高屈折率化成分の中でも、特に高分散化の作用が大きい成分である。したがって、所望の光学恒数を得る観点から、質量比［ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）］は上記範囲であることが好ましい。 Among the high refractive index components, TiO 2 is a component having a particularly large effect of high dispersion. Therefore, from the viewpoint of obtaining a desired optical constant, the mass ratio [TiO 2 / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 )] is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］は１．８０以下である。該質量比の上限は、好ましくは１．７５であり、さらには１．７３、１．７２、１．７１、１．７０の順により好ましい。また、該質量比の下限は、好ましくは１．２０であり、さらには１．３０、１．３５、１．３８、１．４０の順により好ましい。 In the optical glass according to the second embodiment, the mass ratio of the total contents of P 2 O 5 , B 2 O 3 and SiO 2 to the total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [ (P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less. The upper limit of the mass ratio is preferably 1.75, and more preferably 1.73, 1.72, 1.71, and 1.70. The lower limit of the mass ratio is preferably 1.20, and more preferably 1.30, 1.35, 1.38, and 1.40 in that order.
　質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］を上記範囲とすることで、熱的安定性が高く、相対屈折率の温度係数（ｄｎ／ｄＴ）が低く、平均線熱膨張係数の大きい光学ガラスが得られる。 By setting the mass ratio [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] in the above range, the thermal stability is high and the temperature coefficient of relative refractive index ( An optical glass having a low dn / dT) and a large average coefficient of linear thermal expansion can be obtained.
　上記（Ａ）を満たす第２実施形態に係る光学ガラスにおいて、ＷＯ３の含有量は７％以下である。ＷＯ３の含有量の上限は、好ましくは５％であり、さらには３％、２％、１％の順により好ましい。ＷＯ３の含有量は少ない方が好ましく、その下限は好ましくは０％である。ＷＯ３の含有量は０％でもよい。 In the optical glass according to the second embodiment satisfying the above (A), the content of WO 3 is 7% or less. The upper limit of the content of WO 3 is preferably 5%, more preferably 3%, 2%, and 1%. The content of WO 3 is preferably low, and the lower limit thereof is preferably 0%. The content of WO 3 may be 0%.
　上記（Ｂ）を満たす第２実施形態に係る光学ガラスにおいて、ＷＯ３の含有量は１５％以下であることが好ましく、その上限は１０％、５％、３％の順により好ましい。ＷＯ３の含有量は少ない方が好ましく、その下限は好ましくは０％である。ＷＯ３の含有量は０％でもよい。 In the optical glass according to the second embodiment satisfying the above (B), the content of WO 3 is preferably 15% or less, and the upper limit thereof is more preferably 10%, 5%, and 3%. The content of WO 3 is preferably low, and the lower limit thereof is preferably 0%. The content of WO 3 may be 0%.
　ＷＯ３の含有量を上記範囲とすることで、透過率を高めることができ、また、ガラスの比重の増大を抑制できる。また、相対屈折率の温度係数（ｄｎ／ｄＴ）を低くすることができる。 By setting the content of WO 3 in the above range, the transmittance can be increased and the increase in the specific gravity of the glass can be suppressed. Further, the temperature coefficient (dn / dT) of the relative refractive index can be lowered.
　上記（Ａ）を満たす第２実施形態に係る光学ガラスにおいて、フッ素Ｆの含有量は３％以下であることが好ましく、その上限は１％、０．５％、０．３％の順により好ましい。Ｆの含有量は少ない方が好ましく、その下限は好ましくは０％である。Ｆの含有量は０％でもよい。 In the optical glass according to the second embodiment satisfying the above (A), the content of fluorine F is preferably 3% or less, and the upper limit thereof is more preferably 1%, 0.5%, and 0.3%. .. The content of F is preferably small, and the lower limit thereof is preferably 0%. The content of F may be 0%.
　上記（Ｂ）を満たす第２実施形態に係る光学ガラスは実質的にフッ素Ｆを含まない。 The optical glass according to the second embodiment satisfying the above (B) does not substantially contain fluorine F.
　Ｆの含有量を上記範囲とすることで、ガラスを熔解中の揮発を抑えることができ、屈折率の変動、脈理を抑えることができる。 By setting the F content within the above range, volatilization during melting of the glass can be suppressed, and fluctuations in the refractive index and pulse can be suppressed.
　第２実施形態に係る光学ガラスにおける上記以外のガラス成分の含有量および比率について、以下に非制限的な例を示す。 Non-limiting examples of the content and ratio of glass components other than the above in the optical glass according to the second embodiment are shown below.
　第２実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５、Ｂ２Ｏ３、ＳｉＯ２、Ａｌ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量の質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３＋Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］は１．１０以下であることが好ましい。該質量比の上限は、好ましくは１．００であり、さらには０．９５、０．９０、０．８５、０．８２、０．８０の順により好ましい。また、該質量比の下限は、より好ましくは０．５０であり、さらには０．５５、０．６０、０．６２、０．６４の順により好ましい。 In the optical glass according to the second embodiment, TiO 2 with respect to the total content of P 2 O 5 , B 2 O 3 , SiO 2 , Al 2 O 3 , Li 2 O, Na 2 O, K 2 O and Cs 2 O. , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 total content mass ratio [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5) / (P 2 O 5) + B 2 O 3 + SiO 2 + Al 2 O 3 + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is preferably 1.10 or less. The upper limit of the mass ratio is preferably 1.00, more preferably 0.95, 0.90, 0.85, 0.82, 0.80. The lower limit of the mass ratio is more preferably 0.50, and further preferably 0.55, 0.60, 0.62, 0.64.
　質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３＋Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］を上記範囲とすることで、所望の光学恒数を有する光学ガラスが得られやすくなる。 Mass ratio [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3 + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] By setting the range, it becomes easy to obtain an optical glass having a desired optical constant.
　第２実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５およびＢ２Ｏ３の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］は０．７０以下であることが好ましい。該質量比の上限は、好ましくは０．６８であり、さらには０．６７、０．６６、０．６５の順により好ましい。該質量比の下限は、好ましくは０．２５であり、さらには０．３５、０．４０、０．４５の順により好ましい。 In the optical glass according to the second embodiment, the mass ratio of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 [TiO 2 / (P 2 O 5 + B 2 O 3 )] is 0. It is preferably 70 or less. The upper limit of the mass ratio is preferably 0.68, more preferably 0.67, 0.66, 0.65. The lower limit of the mass ratio is preferably 0.25, more preferably 0.35, 0.40, 0.45 in that order.
　質量比［ＴｉＯ２／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］を上記範囲とすることで、所望の光学恒数を有し、熱的安定性が高い光学ガラスが得られやすくなる。 By setting the mass ratio [TiO 2 / (P 2 O 5 + B 2 O 3 )] to the above range, it becomes easy to obtain an optical glass having a desired optical constant and high thermal stability.
　第２実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５の含有量に対するＢ２Ｏ３の含有量の質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］は０．３９以下であることが好ましい。該質量比の上限は、より好ましくは０．２０であり、さらには０．１５、０．１２、０．１０、０．０８、０．０７、０．０６の順により好ましい。 In the optical glass according to the second embodiment, the mass ratio of the content of B 2 O 3 to the content of P 2 O 5 [B 2 O 3 / P 2 O 5] is preferably at 0.39 or less. The upper limit of the mass ratio is more preferably 0.20, and further preferably 0.15, 0.12, 0.10, 0.08, 0.07, 0.06 in that order.
　質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］を上記範囲とすることで、所望の光学恒数を有し、熱的安定性が高く、耐失透性が高い光学ガラスが得られやすくなる。 By setting the mass ratio [B 2 O 3 / P 2 O 5 ] in the above range, it becomes easy to obtain an optical glass having a desired optical constant, high thermal stability, and high devitrification resistance. ..
　第２実施形態に係る光学ガラスにおいて、ＭｇＯ、ＣａＯ、ＳｒＯおよびＢａＯの合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］は８．０％以下である。該合計含有量の上限は、好ましくは６％であり、さらには５％、４％、３％の順により好ましい。また、該合計含有量の下限は、好ましくは０％である。 In the optical glass according to the second embodiment, the total content [MgO + CaO + SrO + BaO] of MgO, CaO, SrO and BaO is 8.0% or less. The upper limit of the total content is preferably 6%, more preferably 5%, 4%, and 3%. The lower limit of the total content is preferably 0%.
　合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］を上記範囲とすることで、高分散化を促進できる。 By setting the total content [MgO + CaO + SrO + BaO] in the above range, high dispersion can be promoted.
　第２実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５の含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／Ｐ２Ｏ５］の上限は、好ましくは０．７０であり、さらには０．６８、０．６６、０．６５の順により好ましい。該質量比の下限は、好ましくは０．２５であり、さらには０．３５、０．４０、０．４５の順により好ましい。 In the optical glass according to the second embodiment, the upper limit of the mass ratio of the content of TiO 2 [TiO 2 / P 2 O 5] to the content of P 2 O 5 is preferably 0.70, more 0 It is more preferable in the order of .68, 0.66, 0.65. The lower limit of the mass ratio is preferably 0.25, more preferably 0.35, 0.40, 0.45 in that order.
　質量比［ＴｉＯ２／Ｐ２Ｏ５］を上記範囲とすることで、所望の光学恒数を有し、熱的安定性が高い光学ガラスが得られやすくなる。 By setting the mass ratio [TiO 2 / P 2 O 5 ] to the above range, it becomes easy to obtain an optical glass having a desired optical constant and high thermal stability.
　第２実施形態に係る光学ガラスにおいて、Ｂ２Ｏ３の含有量の上限は、好ましくは１０％であり、さらには７％、５％、３％、２％の順により好ましい。Ｂ２Ｏ３の含有量は０％でもよい。 In the optical glass according to the second embodiment, the upper limit of the content of B 2 O 3 is preferably 10%, more preferably 7%, 5%, 3%, and 2%. The content of B 2 O 3 may be 0%.
　Ｂ２Ｏ３は、ガラスのネットワーク形成成分であり、ガラスの熱的安定性を改善する働きを有する。一方、Ｂ２Ｏ３の含有量が多いと、耐失透性が低下する傾向がある。そのためＢ２Ｏ３の含有量は上記範囲であることが好ましい。 B 2 O 3 is a network-forming component of glass and has a function of improving the thermal stability of glass. On the other hand, when the content of B 2 O 3 is large, the devitrification resistance tends to decrease. Therefore, the content of B 2 O 3 is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、Ａｌ２Ｏ３の含有量は、好ましくは３％以下であり、さらには２％以下、１％以下の順により好ましい。Ａｌ２Ｏ３の含有量は０％でもよい。 In the optical glass according to the second embodiment, the content of Al 2 O 3 is preferably 3% or less, more preferably 2% or less and 1% or less. The content of Al 2 O 3 may be 0%.
　Ａｌ２Ｏ３は、ガラスの化学的耐久性、耐候性を改善する働きを有するガラス成分であり、ネットワーク形成成分として考えることができる。一方、Ａｌ２Ｏ３の含有量が多くなると、ガラスの耐失透性が低下する。また、ガラス転移温度Ｔｇが上昇し、熱的安定性が低下する等の問題が生じやすい。このような問題を回避する観点から、Ａｌ２Ｏ３の含有量の上限は上記範囲であることが好ましい。 Al 2 O 3 is a glass component having a function of improving the chemical durability and weather resistance of glass, and can be considered as a network forming component. On the other hand, when the content of Al 2 O 3 increases, the devitrification resistance of the glass decreases. In addition, problems such as an increase in the glass transition temperature Tg and a decrease in thermal stability are likely to occur. From the viewpoint of avoiding such a problem, the upper limit of the content of Al 2 O 3 is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、ＳｉＯ２の含有量の上限は、好ましくは５％であり、さらには３％、２％、１％の順により好ましい。ＳｉＯ２の含有量は０％でもよい。 In the optical glass according to the second embodiment, the upper limit of the content of SiO 2 is preferably 5%, more preferably 3%, 2%, and 1%. The content of SiO 2 may be 0%.
　なお、ガラスの熔融に石英ガラス製坩堝などの石英ガラス製の熔融器具を使用することがある。この場合、熔融器具からガラス熔融物に少量のＳｉＯ２が溶け込むため、ガラス原料がＳｉＯ２を含んでいなくても作製したガラスは少量のＳｉＯ２を含有する。石英ガラス製の熔融器具からガラスに混入するＳｉＯ２の量は熔融条件にもよるが、例えば、全ガラス成分の含有量の合計に対し、０．５～１質量％程度である。ＳｉＯ２以外のガラス成分の含有比は一定のまま、ＳｉＯ２の量が０．５～１質量％程度増加する。なお、熔解条件によって上記量は増減する。ＳｉＯ２の含有量によって、屈折率、アッベ数などの光学特性が変化するので、ＳｉＯ２以外のガラス成分の含有量を微調整して所望の光学特性を有する光学ガラスを得る。 A quartz glass melting device such as a quartz glass crucible may be used to melt the glass. In this case, since a small amount of SiO 2 melts into the glass melt from the melting device, the glass frit is produced be free of SiO 2 contains a small amount of SiO 2. The amount of SiO 2 mixed into the glass from the quartz glass melting device depends on the melting conditions, but is, for example, about 0.5 to 1% by mass with respect to the total content of all glass components. The amount of SiO 2 increases by about 0.5 to 1% by mass while the content ratio of the glass component other than SiO 2 remains constant. The above amount may increase or decrease depending on the melting conditions. Since the optical characteristics such as the refractive index and the Abbe number change depending on the content of SiO 2, the content of the glass component other than SiO 2 is finely adjusted to obtain an optical glass having desired optical characteristics.
　ＳｉＯ２は、ガラスのネットワーク形成成分であり、ガラスの熱的安定性、化学的耐久性、耐候性を改善し、熔融ガラスの粘度を高め、熔融ガラスを成形しやすくする働きを有する。一方、ＳｉＯ２の含有量が多いと、ガラスの耐失透性が低下する傾向がある。そのため、ＳｉＯ２の含有量の上限は上記範囲であることが好ましい。 SiO 2 is a network-forming component of glass, and has a function of improving thermal stability, chemical durability, and weather resistance of glass, increasing the viscosity of molten glass, and facilitating molding of molten glass. On the other hand, when the content of SiO 2 is large, the devitrification resistance of the glass tends to decrease. Therefore, the upper limit of the content of SiO 2 is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量[Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２]の上限は、好ましくは４５％であり、さらには４２％、４０％、３８％の順により好ましい。該合計含有量の下限は、好ましくは２５％であり、さらには２８％、３０％、３２％の順により好ましい。 In the optical glass according to the second embodiment, the upper limit of the total content [P 2 O 5 + B 2 O 3 + SiO 2 ] of P 2 O 5 , B 2 O 3 and SiO 2 is preferably 45%, and further. Is more preferable in the order of 42%, 40%, and 38%. The lower limit of the total content is preferably 25%, more preferably 28%, 30%, and 32%.
　合計含有量[Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２]を上記範囲とすることで、熱的安定性が高く、所望の光学恒数を有する光学ガラスが得られる。 By setting the total content [P 2 O 5 + B 2 O 3 + SiO 2 ] in the above range, an optical glass having high thermal stability and a desired optical constant can be obtained.
　第２実施形態に係る光学ガラスにおいて、Ｂｉ２Ｏ３の含有量の上限は、好ましくは１５％であり、さらには１０％、７％、５％、３％の順により好ましい。また、Ｂｉ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the second embodiment, the upper limit of the content of Bi 2 O 3 is preferably 15%, more preferably 10%, 7%, 5%, and 3%. The lower limit of the Bi 2 O 3 content is preferably 0%.
　Ｂｉ２Ｏ３は、適量を含有させることによりガラスの熱的安定性を改善する働きを有する。一方、Ｂｉ２Ｏ３の含有量を高めると、ガラスの着色が増大する。したがって、Ｂｉ２Ｏ３の含有量は上記範囲であることが好ましい。 Bi 2 O 3 has a function of improving the thermal stability of glass by containing an appropriate amount. On the other hand, when the content of Bi 2 O 3 is increased, the coloring of the glass is increased. Therefore, the content of Bi 2 O 3 is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、Ｔａ２Ｏ５の含有量の上限は、好ましくは１０％であり、さらには７％、５％、３％の順により好ましい。また、Ｔａ２Ｏ５の含有量の下限は、好ましくは０％である。Ｔａ２Ｏ５の含有量は０％でもよい。 In the optical glass according to the second embodiment, the upper limit of the content of Ta 2 O 5 is preferably 10%, more preferably 7%, 5%, and 3%. The lower limit of the content of Ta 2 O 5 is preferably 0%. The content of Ta 2 O 5 may be 0%.
　Ｔａ２Ｏ５は、ガラスの熱的安定性および耐失透性を改善する働きを有するガラス成分である。一方、Ｔａ２Ｏ５は、屈折率を上昇させ、ガラスを高分散化させる。また、Ｔａ２Ｏ５の含有量が多くなると、ガラスの熱的安定性が低下し、ガラスを熔融するときに、ガラス原料の熔け残りが生じやすくなる。そのため、Ｔａ２Ｏ５の含有量は上記範囲であることが好ましい。さらに、Ｔａ２Ｏ５は、他のガラス成分と比較し、極めて高価な成分であり、Ｔａ２Ｏ５の含有量が多くなるとガラスの生産コストが増大する。さらに、Ｔａ２Ｏ５は他のガラス成分と比べて分子量が大きいため、ガラスの比重を増大させ、結果的に光学素子の重量を増大させる。 Ta 2 O 5 is a glass component having a function of improving the thermal stability and devitrification resistance of glass. On the other hand, Ta 2 O 5 increases the refractive index and makes the glass highly dispersed. Further, when the content of Ta 2 O 5 is increased, the thermal stability of the glass is lowered, and when the glass is melted, the unmelted residue of the glass raw material is likely to occur. Therefore, the content of Ta 2 O 5 is preferably in the above range. Further, Ta 2 O 5 is an extremely expensive component as compared with other glass components, and as the content of Ta 2 O 5 increases, the production cost of glass increases. Further, since Ta 2 O 5 has a larger molecular weight than other glass components, it increases the specific gravity of the glass, and as a result, increases the weight of the optical element.
　第２実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏの含有量の上限は、好ましくは５％であり、さらには３％、２％、１％の順により好ましい。Ｌｉ２Ｏの含有量の下限は、好ましくは０％である。Ｌｉ２Ｏの含有量は０％でもよい。 In the optical glass according to the second embodiment, the upper limit of the Li 2 O content is preferably 5%, more preferably 3%, 2%, and 1%. The lower limit of the Li 2 O content is preferably 0%. The content of Li 2 O may be 0%.
　Ｌｉ２Ｏは、ガラスの低比重化に寄与する成分であり、ガラスの熔融性を改善し、また平均線熱膨張係数を大きくする働きを有する。一方、Ｌｉ２Ｏの含有量が多くなると、耐失透性が低下する。したがって、Ｌｉ２Ｏの含有量は上記範囲であることが好ましい。 Li 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion. On the other hand, as the content of Li 2 O increases, the devitrification resistance decreases. Therefore, the Li 2 O content is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、Ｎａ２Ｏの含有量の下限は、好ましくは６％であり、さらには１０％、１２％、１３％の順により好ましい。また、Ｎａ２Ｏの含有量の上限は、好ましくは３０％であり、さらには２２％、２０％、１９％、１８％の順により好ましい。 In the optical glass according to the second embodiment, the lower limit of the Na 2 O content is preferably 6%, more preferably 10%, 12%, and 13% in that order. The upper limit of the Na 2 O content is preferably 30%, more preferably 22%, 20%, 19%, and 18%.
　Ｎａ２Ｏは、ガラスの低比重化に寄与する成分であり、ガラスの熔融性を改善し、また平均線熱膨張係数を大きくする働きを有する。一方、Ｎａ２Ｏの含有量が多くなると、耐失透性が低下する。したがって、Ｎａ２Ｏの含有量は上記範囲であることが好ましい。 Na 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion. On the other hand, as the Na 2 O content increases, the devitrification resistance decreases. Therefore, the Na 2 O content is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、Ｋ２Ｏの含有量の下限は、好ましくは１％であり、さらには２％、３％、４％の順により好ましい。また、Ｋ２Ｏの含有量の上限は、好ましくは１３％であり、さらには１２％、１１％、１０％の順により好ましい。 In the optical glass according to the second embodiment, the lower limit of the K 2 O content is preferably 1%, more preferably 2%, 3%, and 4%. The upper limit of the content of K 2 O is preferably 13%, further 12%, 11%, preferably by 10% order.
　Ｋ２Ｏは、ガラスの低比重化に寄与する成分であり、ガラスの熱的安定性を改善する働きを有する。また平均線熱膨張係数を大きくする働きを有する。一方、Ｋ２Ｏの含有量が多くなると、熱的安定性が低下し、ガラス化時に脈理が発生しやすくなる。したがって、Ｋ２Ｏの含有量は上記範囲であることが好ましい。 K 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the thermal stability of glass. It also has the function of increasing the average coefficient of linear thermal expansion. On the other hand, when the content of K 2 O is large, the thermal stability is lowered and the veins are likely to occur at the time of vitrification. Therefore, it is preferable that the content of K 2 O is within the above range.
　第２実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏ、Ｎａ２ＯおよびＫ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ］の上限は、好ましくは３５％であり、さらには３０％、２８％、２６％、２５％の順により好ましい。また、該合計含有量の下限は、好ましくは１０％であり、さらには１４％、１８％、１９％、２０％の順により好ましい。 In the optical glass according to the second embodiment, the upper limit of the total content [Li 2 O + Na 2 O + K 2 O] of Li 2 O, Na 2 O and K 2 O is preferably 35%, further 30%. 28%, 26%, and 25% are more preferable in this order. The lower limit of the total content is preferably 10%, more preferably 14%, 18%, 19%, and 20%.
　Ｌｉ２Ｏ、Ｎａ２ＯおよびＫ２Ｏは、いずれもガラスの熱的安定性を改善する働きを有する。しかし、これらの含有量が多くなると、化学的耐久性、耐候性が低下するおそれがある。そのため、Ｌｉ２Ｏ、Ｎａ２ＯおよびＫ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ］は上記範囲であることが好ましい。 Li 2 O, Na 2 O and K 2 O all have a function of improving the thermal stability of glass. However, if these contents are high, the chemical durability and weather resistance may be lowered. Therefore, the total content of Li 2 O, Na 2 O and K 2 O [Li 2 O + Na 2 O + K 2 O] is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、Ｃｓ２Ｏの含有量の上限は、好ましくは５％であり、さらには３％、２％、１％の順により好ましい。また、Ｃｓ２Ｏの含有量の下限は、好ましくは０％である。Ｃｓ２Ｏの含有量は０％でもよい。 In the optical glass according to the second embodiment, the upper limit of the content of Cs 2 O is preferably 5%, more preferably 3%, 2%, and 1%. The lower limit of the Cs 2 O content is preferably 0%. The content of Cs 2 O may be 0%.
　Ｃｓ２Ｏは、ガラスの熔融性を改善する働きを有するが、含有量が多くなると、ガラスの熱的安定性、屈折率ｎｄが低下し、また熔解中にガラス成分の揮発が増加して、所望のガラスが得られなくなる。そのため、Ｃｓ２Ｏの含有量は上記範囲であることが好ましい。 Cs 2 O has a function of improving the meltability of glass, but when the content is increased, the thermal stability and refractive index nd of the glass are lowered, and the volatilization of the glass component is increased during melting. The desired glass cannot be obtained. Therefore, the content of Cs 2 O is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ］の上限は、好ましくは３５％であり、さらには３０％、２８％、２６％、２５％の順により好ましい。また、該合計含有量の下限は、好ましくは１０％であり、さらには１４％、１８％、１９％、２０％の順により好ましい。 In the optical glass according to the second embodiment, the upper limit of the total content [Li 2 O + Na 2 O + K 2 O + Cs 2 O] of Li 2 O, Na 2 O, K 2 O and Cs 2 O is preferably 35%. Further, 30%, 28%, 26%, and 25% are more preferable in this order. The lower limit of the total content is preferably 10%, more preferably 14%, 18%, 19%, and 20%.
　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏは、いずれもガラスの熱的安定性を改善する働きを有する。しかし、これらの含有量が多くなると、化学的耐久性、耐候性が低下するおそれがある。そのため、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ］は上記範囲であることが好ましい。 Li 2 O, Na 2 O, K 2 O and Cs 2 O all have a function of improving the thermal stability of glass. However, if these contents are high, the chemical durability and weather resistance may be lowered. Therefore, the total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O [Li 2 O + Na 2 O + K 2 O + Cs 2 O] is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、ＭｇＯの含有量は、好ましくは５％以下であり、さらには３％以下、１％以下の順により好ましい。また、ＭｇＯの含有量の下限は、好ましくは０％である。ＭｇＯの含有量は０％であってもよい。 In the optical glass according to the second embodiment, the content of MgO is preferably 5% or less, more preferably 3% or less and 1% or less. The lower limit of the MgO content is preferably 0%. The content of MgO may be 0%.
　第２実施形態に係る光学ガラスにおいて、ＣａＯの含有量は、好ましくは５％以下であり、さらには３％以下、１％以下の順により好ましい。また、ＣａＯの含有量の下限は、好ましくは０％である。ＣａＯの含有量は０％であってもよい。 In the optical glass according to the second embodiment, the CaO content is preferably 5% or less, more preferably 3% or less and 1% or less. The lower limit of the CaO content is preferably 0%. The CaO content may be 0%.
　第２実施形態に係る光学ガラスにおいて、ＳｒＯの含有量は、好ましくは６％以下であり、さらには５％以下、３％以下、１％以下の順により好ましい。また、ＳｒＯの含有量の下限は、好ましくは０％である。 In the optical glass according to the second embodiment, the SrO content is preferably 6% or less, more preferably 5% or less, 3% or less, and 1% or less. The lower limit of the SrO content is preferably 0%.
　第２実施形態に係る光学ガラスにおいて、ＢａＯの含有量は、好ましくは８％以下であり、さらには５％以下、３％以下、１％以下の順により好ましい。また、ＢａＯの含有量の下限は、好ましくは０％である。 In the optical glass according to the second embodiment, the BaO content is preferably 8% or less, more preferably 5% or less, 3% or less, and 1% or less. The lower limit of the BaO content is preferably 0%.
　ＭｇＯ、ＣａＯ、ＳｒＯ、ＢａＯは、いずれもガラスの熱的安定性および耐失透性を改善する働きを有するガラス成分である。しかし、これらガラス成分の含有量が多くなると、高分散性が損なわれ、また、ガラスの熱的安定性および耐失透性が低下する。そのため、これらガラス成分の各含有量は、それぞれ上記範囲であることが好ましい。 MgO, CaO, SrO, and BaO are all glass components having a function of improving the thermal stability and devitrification resistance of glass. However, when the content of these glass components is increased, the high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass are lowered. Therefore, the content of each of these glass components is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、ＺｎＯの含有量の上限は、好ましくは１０％であり、さらには６％、４％、３％の順により好ましい。ＺｎＯ含有量は少ない方が好ましく、その下限は好ましくは０％である。ＺｎＯの含有量は０％でもよい。 In the optical glass according to the second embodiment, the upper limit of the ZnO content is preferably 10%, more preferably 6%, 4%, and 3%. The ZnO content is preferably low, and the lower limit thereof is preferably 0%. The ZnO content may be 0%.
　ＺｎＯは、ガラスの熱的安定性を改善する働きを有するガラス成分である。しかし、ＺｎＯの含有量が多すぎるとガラスの比重が増大する。また、相対屈折率の温度係数（ｄｎ／ｄＴ）が高くなる。そのため、ＺｎＯの含有量は上記範囲であることが好ましい。 ZnO is a glass component having a function of improving the thermal stability of glass. However, if the ZnO content is too high, the specific gravity of the glass increases. Further, the temperature coefficient (dn / dT) of the relative refractive index becomes high. Therefore, the ZnO content is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、ＺｒＯ２の含有量は、好ましくは５％以下であり、さらには３％以下、１％以下の順により好ましい。また、ＺｒＯ２の含有量の下限は、好ましくは０％である。 In the optical glass according to the second embodiment, the content of ZrO 2 is preferably 5% or less, more preferably 3% or less and 1% or less. The lower limit of the ZrO 2 content is preferably 0%.
　ＺｒＯ２は、ガラスの熱的安定性および耐失透性を改善する働きを有するガラス成分である。しかし、ＺｒＯ２の含有量が多すぎると、熱的安定性が低下する傾向を示す。そのため、ＺｒＯ２の含有量は上記範囲であることが好ましい。 ZrO 2 is a glass component having a function of improving the thermal stability and devitrification resistance of glass. However, if the content of ZrO 2 is too high, the thermal stability tends to decrease. Therefore, the content of ZrO 2 is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、Ｓｃ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｓｃ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the second embodiment, the upper limit of the content of Sc 2 O 3 is preferably 2%. The lower limit of the Sc 2 O 3 content is preferably 0%.
　第２実施形態に係る光学ガラスにおいて、ＨｆＯ２の含有量の上限は、好ましくは２％である。また、ＨｆＯ２の含有量の下限は、好ましくは０％である。 In the optical glass according to the second embodiment, the upper limit of the HfO 2 content is preferably 2%. The lower limit of the HfO 2 content is preferably 0%.
　Ｓｃ２Ｏ３、ＨｆＯ２は、いずれも屈折率ｎｄを高める働きを有し、また高価な成分である。そのため、Ｓｃ２Ｏ３、ＨｆＯ２の各含有量は上記範囲であることが好ましい。 Sc 2 O 3 and HfO 2 both have a function of increasing the refractive index nd and are expensive components. Therefore, the contents of Sc 2 O 3 and HfO 2 are preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、Ｌｕ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｌｕ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the second embodiment, the upper limit of the content of Lu 2 O 3 is preferably 2%. The lower limit of the content of Lu 2 O 3 is preferably 0%.
　Ｌｕ２Ｏ３は、屈折率ｎｄを高める働きを有する。また、分子量が大きいことから、ガラスの比重を増加させるガラス成分でもある。そのため、Ｌｕ２Ｏ３の含有量は上記範囲であることが好ましい。 Lu 2 O 3 has a function of increasing the refractive index nd. In addition, since it has a large molecular weight, it is also a glass component that increases the specific gravity of glass. Therefore, the content of Lu 2 O 3 is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、ＧｅＯ２の含有量の上限は、好ましくは２％である。また、ＧｅＯ２の含有量の下限は、好ましくは０％である。 In the optical glass according to the second embodiment, the upper limit of the content of GeO 2 is preferably 2%. The lower limit of the content of GeO 2 is preferably 0%.
　ＧｅＯ２は、屈折率ｎｄを高める働きを有し、また、一般的に使用されるガラス成分の中で、突出して高価な成分である。したがって、ガラスの製造コストを低減する観点から、ＧｅＯ２の含有量は上記範囲であることが好ましい。 GeO 2 has a function of increasing the refractive index nd, and is a prominently expensive component among commonly used glass components. Therefore, from the viewpoint of reducing the manufacturing cost of glass, the content of GeO 2 is preferably in the above range.
　第２実施形態に係る光学ガラスにおいて、Ｌａ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｌａ２Ｏ３の含有量の下限は、好ましくは０％である。Ｌａ２Ｏ３の含有量は０％であってもよい。 In the optical glass according to the second embodiment, the upper limit of the content of La 2 O 3 is preferably 2%. The lower limit of the content of La 2 O 3 is preferably 0%. The content of La 2 O 3 may be 0%.
　Ｌａ２Ｏ３の含有量が多くなるとガラスの熱的安定性および耐失透性が低下し、製造中にガラスが失透しやすくなる。したがって、熱的安定性および耐失透性の低下を抑制する観点から、Ｌａ２Ｏ３の含有量は上記範囲であることが好ましい。 When the content of La 2 O 3 is increased, the thermal stability and devitrification resistance of the glass are lowered, and the glass is easily devitrified during production. Therefore, the content of La 2 O 3 is preferably in the above range from the viewpoint of suppressing the decrease in thermal stability and devitrification resistance.
　第２実施形態に係る光学ガラスにおいて、Ｇｄ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｇｄ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the second embodiment, the upper limit of the content of Gd 2 O 3 is preferably 2%. The lower limit of the content of Gd 2 O 3 is preferably 0%.
　Ｇｄ２Ｏ３の含有量が多くなり過ぎるとガラスの熱的安定性および耐失透性が低下し、製造中にガラスが失透しやすくなる。また、Ｇｄ２Ｏ３の含有量が多くなり過ぎるとガラスの比重が増大し、好ましくない。したがって、ガラスの熱的安定性および耐失透性を良好に維持しつつ、比重の増大を抑制する観点から、Ｇｄ２Ｏ３の含有量は上記範囲であることが好ましい。 If the content of Gd 2 O 3 is too high, the thermal stability and devitrification resistance of the glass will decrease, and the glass will easily devitrify during production. Further, if the content of Gd 2 O 3 becomes too large, the specific gravity of the glass increases, which is not preferable. Therefore, the content of Gd 2 O 3 is preferably in the above range from the viewpoint of suppressing an increase in specific gravity while maintaining good thermal stability and devitrification resistance of the glass.
　第２実施形態に係る光学ガラスにおいて、Ｙ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｙ２Ｏ３の含有量の下限は、好ましくは０％である。Ｙ２Ｏ３の含有量は０％であってもよい。 In the optical glass according to the second embodiment, the upper limit of the content of Y 2 O 3 is preferably 2%. The lower limit of the content of Y 2 O 3 is preferably 0%. The content of Y 2 O 3 may be 0%.
　Ｙ２Ｏ３の含有量が多くなり過ぎるとガラスの熱的安定性および耐失透性が低下する。したがって、熱的安定性および耐失透性の低下を抑制する観点から、Ｙ２Ｏ３の含有量は上記範囲であることが好ましい。 If the content of Y 2 O 3 is too high, the thermal stability and devitrification resistance of the glass will decrease. Therefore, from the viewpoint of suppressing a decrease in the thermal stability and devitrification resistance, the content of Y 2 O 3 is preferably in the range.
　第２実施形態に係る光学ガラスにおいて、Ｙｂ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｙｂ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the second embodiment, the upper limit of the content of Yb 2 O 3 is preferably 2%. The lower limit of the content of Yb 2 O 3 is preferably 0%.
　Ｙｂ２Ｏ３は、Ｌａ２Ｏ３、Ｇｄ２Ｏ３、Ｙ２Ｏ３と比べて分子量が大きいため、ガラスの比重を増大させる。ガラスの比重が増大すると、光学素子の質量が増大する。例えば、質量の大きいレンズをオートフォーカス式の撮像レンズに組み込むと、オートフォーカス時にレンズの駆動に要する電力が増大し、電池の消耗が激しくなる。したがって、Ｙｂ２Ｏ３の含有量を低減させて、ガラスの比重の増大を抑えることが望ましい。 Since Yb 2 O 3 has a larger molecular weight than La 2 O 3 , Gd 2 O 3 , and Y 2 O 3 , it increases the specific gravity of glass. As the specific gravity of glass increases, the mass of the optical element increases. For example, if a lens having a large mass is incorporated into an autofocus type imaging lens, the power required to drive the lens during autofocus increases, and the battery consumption increases. Therefore, it is desirable to reduce the content of Yb 2 O 3 to suppress the increase in the specific gravity of the glass.
　また、Ｙｂ２Ｏ３の含有量が多すぎるとガラスの熱的安定性および耐失透性が低下する。ガラスの熱的安定性の低下を防ぎ、比重の増大を抑制する観点から、Ｙｂ２Ｏ３の含有量は上記範囲であることが好ましい。 Further, if the content of Yb 2 O 3 is too large, the thermal stability and devitrification resistance of the glass are lowered. The content of Yb 2 O 3 is preferably in the above range from the viewpoint of preventing a decrease in thermal stability of the glass and suppressing an increase in specific gravity.
　第２実施形態に係る光学ガラスは、主として上述のガラス成分、すなわち、必須成分としてＰ２Ｏ５、ＴｉＯ２、Ｎｂ２Ｏ５、任意成分としてＷＯ３、Ｂ２Ｏ３、Ａｌ２Ｏ３、ＳｉＯ２、Ｂｉ２Ｏ３、Ｔａ２Ｏ５、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２Ｏ、Ｃｓ２Ｏ、ＭｇＯ、ＣａＯ、ＳｒＯ、ＢａＯ、ＺｎＯ、ＺｒＯ２、Ｓｃ２Ｏ３、ＨｆＯ２、Ｌｕ２Ｏ３、ＧｅＯ２、Ｌａ２Ｏ３、Ｇｄ２Ｏ３、Ｙ２Ｏ３、およびＹｂ２Ｏ３で構成されていることが好ましく、上述のガラス成分の合計含有量は、９５％以上が好ましく、９８％以上より好ましく、９９％以上がさらに好ましく、９９．５％以上が一層好ましい。 The optical glass according to the second embodiment mainly contains the above-mentioned glass components, that is, P 2 O 5 , TiO 2 , Nb 2 O 5 as essential components, and WO 3 , B 2 O 3 , Al 2 O 3 , as optional components. SiO 2 , Bi 2 O 3 , Ta 2 O 5 , Li 2 O, Na 2 O, K 2 O, Cs 2 O, MgO, CaO, SrO, BaO, ZnO, ZrO 2 , Sc 2 O 3 , HfO 2 , It is preferably composed of Lu 2 O 3 , GeO 2 , La 2 O 3 , Gd 2 O 3 , Y 2 O 3 , and Yb 2 O 3 , and the total content of the above-mentioned glass components is 95% or more. Is preferable, 98% or more is preferable, 99% or more is further preferable, and 99.5% or more is further preferable.
　第２実施形態に係る光学ガラスにおいて、ＴｅＯ２の含有量の上限は、好ましくは２％である。また、ＴｅＯ２の含有量の下限は、好ましくは０％である。 In the optical glass according to the second embodiment, the upper limit of the content of TeO 2 is preferably 2%. The lower limit of the content of TeO 2 is preferably 0%.
　ＴｅＯ２は毒性を有することから、ＴｅＯ２の含有量を低減させることが好ましい。そのため、ＴｅＯ２の含有量は上記範囲であることが好ましい。 Since TeO 2 is toxic, it is preferable to reduce the content of TeO 2. Therefore, the content of TeO 2 is preferably in the above range.
　なお、第２実施形態に係る光学ガラスは、基本的に上記ガラス成分により構成されることが好ましいが、本発明の作用効果を妨げない範囲において、その他の成分を含有することも可能である。また、本発明において、不可避的不純物の含有を排除するものではない。 The optical glass according to the second embodiment is basically composed of the above glass components, but it is also possible to contain other components as long as the effects of the present invention are not impaired. Further, in the present invention, the inclusion of unavoidable impurities is not excluded.
＜その他の成分組成＞
　Ｐｂ、Ａｓ、Ｃｄ、Ｔｌ、Ｂｅ、Ｓｅは、いずれも毒性を有する。そのため、第２実施形態に係る光学ガラスがこれら元素をガラス成分として含有しないことが好ましい。 <Other component composition>
Pb, As, Cd, Tl, Be and Se are all toxic. Therefore, it is preferable that the optical glass according to the second embodiment does not contain these elements as a glass component.
　Ｕ、Ｔｈ、Ｒａはいずれも放射性元素である。そのため、第２実施形態に係る光学ガラスがこれら元素をガラス成分として含有しないことが好ましい。 U, Th, and Ra are all radioactive elements. Therefore, it is preferable that the optical glass according to the second embodiment does not contain these elements as a glass component.
　Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍは、ガラスの着色を増大させ、蛍光の発生源となり得る。そのため、第２実施形態に係る光学ガラスがこれら元素をガラス成分として含有しないことが好ましい。 V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm increase the coloring of glass and can be a source of fluorescence. Therefore, it is preferable that the optical glass according to the second embodiment does not contain these elements as a glass component.
　Ｓｂ（Ｓｂ２Ｏ３）、Ｃｅ（ＣｅＯ２）は清澄剤として機能する任意に添加可能な元素である。このうち、Ｓｂ（Ｓｂ２Ｏ３）は、清澄効果の大きな清澄剤である。しかし、Ｓｂ（Ｓｂ２Ｏ３）は酸化性が強く、Ｓｂ（Ｓｂ２Ｏ３）の添加量を多くしていくと、Ｓｂイオンによる光吸収により、ガラスの着色が増大し、好ましくない。また、ガラスを熔融するときに、熔融物中にＳｂがあると、ガラス熔融坩堝を構成する白金の熔融物への溶出が促進され、ガラス中の白金濃度が高くなる。ガラス中において、白金がイオンとして存在すると、光の吸収によりガラスの着色が増大する。また、ガラス中に白金が固形物として存在すると光の散乱源となり、ガラスの品質を低下させる。Ｃｅ（ＣｅＯ２）は、Ｓｂ（Ｓｂ２Ｏ３）と比較し、清澄効果が小さい。Ｃｅ（ＣｅＯ２）は、多量に添加するとガラスの着色が強まる。したがって、清澄剤を添加する場合は、添加量に注意しつつ、Ｓｂ（Ｓｂ２Ｏ３）を添加することが好ましい。 Sb (Sb 2 O 3 ) and Ce (CeO 2 ) are arbitrarily addable elements that function as fining agents. Of these, Sb (Sb 2 O 3 ) is a fining agent having a large fining effect. However, Sb (Sb 2 O 3 ) is highly oxidizing, and if the amount of Sb (Sb 2 O 3 ) added is increased, the coloration of the glass increases due to light absorption by Sb ions, which is not preferable. Further, when the glass is melted, if Sb is present in the melt, the elution of platinum constituting the glass melting crucible into the melt is promoted, and the platinum concentration in the glass becomes high. When platinum is present as ions in the glass, the coloration of the glass increases due to the absorption of light. Further, when platinum exists as a solid substance in the glass, it becomes a light scattering source and deteriorates the quality of the glass. Ce (CeO 2 ) has a smaller clarification effect than Sb (Sb 2 O 3). When Ce (CeO 2 ) is added in a large amount, the coloring of the glass is strengthened. Therefore, when adding a fining agent, it is preferable to add Sb (Sb 2 O 3) while paying attention to the amount of addition.
　Ｓｂ２Ｏ３の含有量は、外割り表示とする。すなわち、Ｓｂ２Ｏ３およびＣｅＯ２以外の全ガラス成分の合計含有量を１００質量％としたときのＳｂ２Ｏ３の含有量は、好ましくは１質量％未満、より好ましくは０．１質量％未満である。さらに、は０．０５質量％未満、０．０３質量％未満、０．０２質量％未満、０．０１％未満の順に好ましい。Ｓｂ２Ｏ３の含有量は０質量％であってもよい。 The content of Sb 2 O 3 is indicated by external division. That is, when the total content of all glass components other than Sb 2 O 3 and CeO 2 is 100% by mass, the content of Sb 2 O 3 is preferably less than 1% by mass, more preferably 0.1% by mass. Is less than. Further, is preferably less than 0.05% by mass, less than 0.03% by mass, less than 0.02% by mass, and less than 0.01% in this order. The content of Sb 2 O 3 may be 0% by mass.
　ＣｅＯ２の含有量も、外割り表示とする。すなわち、ＣｅＯ２、Ｓｂ２Ｏ３以外の全ガラス成分の合計含有量を１００質量％としたときのＣｅＯ２の含有量は、好ましくは２質量％未満、より好ましくは１質量％未満、さらに好ましくは０．５質量％未満、一層好ましくは０．１質量％未満の範囲である。ＣｅＯ２の含有量は０質量％であってもよい。ＣｅＯ２の含有量を上記範囲とすることによりガラスの清澄性を改善できる。 The content of CeO 2 is also indicated by external division. That is, when the total content of all glass components other than CeO 2 and Sb 2 O 3 is 100% by mass, the content of CeO 2 is preferably less than 2% by mass, more preferably less than 1% by mass, and even more preferably. Is in the range of less than 0.5% by mass, more preferably less than 0.1% by mass. The content of CeO 2 may be 0% by mass. By setting the content of CeO 2 in the above range, the clarity of the glass can be improved.
（ガラス特性）
　次に、第２実施形態に係る光学ガラスの特性について説明する。 (Glass characteristics)
Next, the characteristics of the optical glass according to the second embodiment will be described.
＜屈折率ｎｄ＞
　第２実施形態に係る光学ガラスにおいて、屈折率ｎｄは、好ましくは１．６３～１．８０である。屈折率ｎｄの下限は１．６５、１．６７、１．６９、１．７１または１．７３でもよく、屈折率ｎｄの上限は１．７９、１．７８、または１．７７でもよい。 <Refractive index nd>
In the optical glass according to the second embodiment, the refractive index nd is preferably 1.63 to 1.80. The lower limit of the refractive index nd may be 1.65, 1.67, 1.69, 1.71 or 1.73, and the upper limit of the refractive index nd may be 1.79, 1.78, or 1.77.
　屈折率ｎｄは各ガラス成分の含有量を適宜調整することにより所望の値にすることができる。相対的に屈折率ｎｄを高める働きを有する成分（高屈折率化成分）は、Ｎｂ２Ｏ５、ＴｉＯ２、ＷＯ３、Ｂｉ２Ｏ３、Ｔａ２Ｏ５、ＺｒＯ２、Ｌａ２Ｏ３等である。一方、相対的に屈折率ｎｄを低くする働きを有する成分（低屈折率化成分）は、Ｐ２Ｏ５、ＳｉＯ2、Ｂ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２Ｏ等である。 The refractive index nd can be set to a desired value by appropriately adjusting the content of each glass component. The components having the function of relatively increasing the refractive index nd (high refractive index component) are Nb 2 O 5 , TiO 2 , WO 3 , Bi 2 O 3 , Ta 2 O 5 , ZrO 2 , La 2 O 3, etc. Is. On the other hand, the components having a function of relatively lowering the refractive index nd (lowering the refractive index component) are P 2 O 5 , SiO 2 , B 2 O 3 , Li 2 O, Na 2 O, K 2 O and the like. is there.
＜アッベ数νｄ＞
　第２実施形態に係る光学ガラスにおいて、アッベ数νｄは、好ましくは２０～３０である。アッベ数νｄの下限は２２、２２．５、２３、または２３．２でもよく、アッベ数νｄの上限は２８、２６、または２５でもよい。 <Abbe number νd>
In the optical glass according to the second embodiment, the Abbe number νd is preferably 20 to 30. The lower limit of the Abbe number νd may be 22, 22.5, 23, or 23.2, and the upper limit of the Abbe number νd may be 28, 26, or 25.
　アッベ数νｄは、各ガラス成分の含有量を適宜調整することにより所望の値にすることができる。相対的にアッベ数νｄを低くする成分、すなわち高分散化成分は、Ｎｂ２Ｏ５、ＴｉＯ２、ＷＯ３、Ｂｉ２Ｏ３、Ｔａ２Ｏ５、ＺｒＯ２等である。一方、相対的にアッベ数νｄを高くする成分、すなわち低分散化成分は、Ｐ２Ｏ５、ＳｉＯ2、Ｂ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２Ｏ、Ｌａ２Ｏ３、ＢａＯ、ＣａＯ、ＳｒＯ等である。 The Abbe number νd can be set to a desired value by appropriately adjusting the content of each glass component. The components that relatively lower the Abbe number νd, that is, the highly dispersed components, are Nb 2 O 5 , TiO 2 , WO 3 , Bi 2 O 3 , Ta 2 O 5 , ZrO 2, and the like. On the other hand, the components that relatively increase the Abbe number νd, that is, the low dispersion components, are P 2 O 5 , SiO 2 , B 2 O 3 , Li 2 O, Na 2 O, K 2 O, La 2 O 3 , BaO, CaO, SrO and the like.
＜平均線熱膨張係数α＞
　第２実施形態に係る光学ガラスにおいて、１００～３００℃における平均線熱膨張係数αの下限は、好ましくは１００×１０－７℃－１であり、さらには１０５×１０－７℃－１、１１０×１０－７℃－１、１１５×１０－７℃－１、１２０×１０－７℃－１の順により好ましい。また、平均線熱膨張係数αの上限は、より好ましくは２００×１０－７℃－１であり、さらには１９０×１０－７℃－１、１８０×１０－７℃－１、１７０×１０－７℃－１、１６０×１０－７℃－１、１５０×１０－７℃－１、１４５×１０－７℃－１の順により好ましい。 <Average coefficient of linear thermal expansion α>
In the optical glass according to the second embodiment, the lower limit of the average coefficient of linear thermal expansion α at 100 to 300 ° C. is preferably 100 × 10 -7 ° C -1 , and further 105 × 10 -7 ° C -1 , 110. × 10 -7 ℃ -1, 115 × 10 -7 ℃ -1, preferably in the order of 120 × 10 -7 ℃ -1. The upper limit of the average coefficient of linear thermal expansion α is more preferably 200 × 10 -7 ℃ -1 , and further 190 × 10 -7 ℃ -1 , 180 × 10 -7 ℃ -1 , 170 × 10 −. 7 ° C -1 , 160 × 10 -7 ° C -1 , 150 × 10 -7 ° C -1 , 145 × 10 -7 ° C -1 are more preferable.
　１００～３００℃の平均線膨張係数αを上記範囲とすることで、ガラスの熱膨張に伴う屈折率の変化、すなわち、相対屈折率の温度係数ｄｎ／ｄＴの増大を抑制することができる。 By setting the average linear expansion coefficient α of 100 to 300 ° C. in the above range, it is possible to suppress a change in the refractive index due to thermal expansion of the glass, that is, an increase in the temperature coefficient dn / dT of the relative refractive index.
　平均線膨張係数αは、ＪＯＧＩＳ０８－２００３の規定に基づいて測定される。但し、試料は長さ２０ｍｍ±０．５ｍｍ、直径５ｍｍ±０．５ｍｍの丸棒とし、試料に９８ｍＮの荷重を印加した状態で、４℃毎分の一定速度で上昇するように加熱し、温度と試料の伸びを測定する。
　なお、本明細書では、平均線膨張係数αを［℃－１］の単位で表しているが、単位として［Ｋ－１］を用いた場合でも平均線膨張係数αの数値は同じである。 The average coefficient of linear expansion α is measured based on the provisions of JOBIS08-2003. However, the sample shall be a round bar with a length of 20 mm ± 0.5 mm and a diameter of 5 mm ± 0.5 mm, and with a load of 98 mN applied to the sample, it shall be heated so as to rise at a constant rate of 4 ° C. And measure the elongation of the sample.
In this specification, the average coefficient of linear expansion α is expressed in the unit of [° C -1 ], but the numerical value of the average coefficient of linear expansion α is the same even when [K -1] is used as the unit.
＜相対屈折率の温度係数ｄｎ／ｄＴ＞
　第２実施形態に係る光学ガラスにおいて、Ｈｅ－Ｎｅレーザの波長（６３３ｎｍ）における相対屈折率の温度係数ｄｎ／ｄＴは、２０～４０℃の範囲で、好ましくは－１．０×１０－６～－１３．０×１０－６℃－１であり、さらには－１．０×１０－６～－１０．０×１０－６℃－１、－１．５×１０－６～－９．０×１０－６℃－１、－２．０×１０－６～－８．０×１０－６℃－１、－２．５×１０－６～－７．０×１０－６℃－１、－３．０×１０－６～－６．５×１０－６℃－１の順により好ましい。 <Temperature coefficient of relative refractive index dn / dT>
In the optical glass according to the second embodiment, the temperature coefficient dn / dT of the relative refractive index at the wavelength (633 nm) of the He—Ne laser is in the range of 20 to 40 ° C., preferably −1.0 × 10-6 to. -13.0 × 10 -6 ℃ -1 , and further -1.0 × 10 -6 to -10.0 × 10 -6 ℃ -1 , -1.5 × 10 -6 to -9.0 × 10 -6 ℃ -1 , -2.0 × 10 -6 ~ -8.0 × 10 -6 ℃ -1 , -2.5 × 10 -6 ~ -7.0 × 10 -6 ℃ -1 , More preferably, the order is −3.0 × 10 -6 to −6.5 × 10 -6 ° C -1.
　ｄｎ／ｄＴを上記範囲とし、ｄｎ／ｄＴがプラスの光学素子と組み合わせることで、光学素子の温度が大きく変動するような環境下でも屈折率の変動が小さくなるため、より幅広い温度範囲において、所望の光学特性を高精度に発揮できる。 By setting dn / dT in the above range and combining it with an optical element having a positive dn / dT, the fluctuation of the refractive index becomes small even in an environment where the temperature of the optical element fluctuates greatly. The optical characteristics of the above can be exhibited with high accuracy.
　相対屈折率の温度係数ｄｎ／ｄＴは、ＪＯＧＩＳ１８－２００８の干渉法に基づいて測定される。
　なお、本明細書では、温度係数ｄｎ／ｄＴを［℃－１］の単位で表しているが、単位として［Ｋ－１］を用いた場合でも温度係数ｄｎ／ｄＴの数値は同じである。 The temperature coefficient dn / dT of the relative refractive index is measured based on the interferometry of JOBIS18-2008.
In this specification, the temperature coefficient dn / dT is expressed in the unit of [° C-1 ], but the numerical value of the temperature coefficient dn / dT is the same even when [K -1] is used as the unit.
＜ガラス転移温度Ｔｇ＞
　第２実施形態に係る光学ガラスのガラス転移温度Ｔｇは、好ましくは６００℃以下であり、さらには５９０℃以下、５８０℃以下、５７０℃以下、５６０℃以下の順により好ましい。 <Glass transition temperature Tg>
The glass transition temperature Tg of the optical glass according to the second embodiment is preferably 600 ° C. or lower, more preferably 590 ° C. or lower, 580 ° C. or lower, 570 ° C. or lower, and 560 ° C. or lower.
　ガラス転移温度Ｔｇの上限が上記範囲を満たすことにより、ガラスの成型温度およびアニール温度の上昇を抑制することができ、プレス成形用設備およびアニール設備への熱的ダメージを軽減できる。また、ガラス転移温度Ｔｇの下限が上記範囲を満たすことにより、所望のアッベ数、屈折率を維持しつつ、ガラスの熱的安定性を良好に維持しやすくなる。 When the upper limit of the glass transition temperature Tg satisfies the above range, it is possible to suppress an increase in the glass molding temperature and the annealing temperature, and it is possible to reduce thermal damage to the press molding equipment and the annealing equipment. Further, when the lower limit of the glass transition temperature Tg satisfies the above range, it becomes easy to maintain good thermal stability of the glass while maintaining a desired Abbe number and refractive index.
＜ガラスの比重＞
　第２実施形態に係る光学ガラスにおいて、比重は、好ましくは３．４０以下であり、さらには、３．３０以下、３．２０以下の順により好ましい。ガラスの比重を低減することができれば、レンズの重量を減少できる。その結果、レンズを搭載するカメラレンズのオートフォーカス駆動の消費電力を低減できる。 <Specific gravity of glass>
In the optical glass according to the second embodiment, the specific gravity is preferably 3.40 or less, more preferably 3.30 or less, and 3.20 or less. If the specific gravity of the glass can be reduced, the weight of the lens can be reduced. As a result, the power consumption of the autofocus drive of the camera lens on which the lens is mounted can be reduced.
＜ガラスの光線透過性＞
　第２実施形態に係る光学ガラスの光線透過性は、着色度λ５により評価できる。
　厚さ１０．０ｍｍ±０．１ｍｍのガラス試料について波長２００～７００ｎｍの範囲で分光透過率を測定し、外部透過率が５％となる波長をλ５とする。 <Light transmission of glass>
The light transmittance of the optical glass according to the second embodiment can be evaluated by the degree of coloring λ5.
The spectral transmittance of a glass sample having a thickness of 10.0 mm ± 0.1 mm is measured in the wavelength range of 200 to 700 nm, and the wavelength at which the external transmittance is 5% is defined as λ5.
　第２実施形態に係る光学ガラスのλ５は、好ましくは４００ｎｍ以下であり、より好ましくは３９０ｎｍ以下であり、さらに好ましくは３８５ｎｍ以下である。 The λ5 of the optical glass according to the second embodiment is preferably 400 nm or less, more preferably 390 nm or less, and further preferably 385 nm or less.
　λ５が短波長化された光学ガラスを用いることで、好適な色再現を可能とする光学素子を提供できる。 By using an optical glass in which λ5 has a shorter wavelength, it is possible to provide an optical element that enables suitable color reproduction.
　第２実施形態に係る光学ガラスの製造および光学素子等の製造については、第１実施形態と同様とすることができる。 The production of the optical glass and the production of the optical element and the like according to the second embodiment can be the same as those of the first embodiment.
第３実施形態
　第３実施形態に係る光学ガラスについて詳細に説明する。
　第３実施形態に係る光学ガラスは、
　Ｐ２Ｏ５の含有量が２５～５０％であり、
　Ｎｂ２Ｏ５含有量が１４～４０％であり、
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］が３５～６０％であり、
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量に対するＴｉＯ２の含有量の質量比[ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）]が０．２５以上であり、
　Ｐ２Ｏ５の含有量に対するＢ２Ｏ３の含有量の質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］が０．０５～０．３９であり、
　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ］が１０％以上であり、
　Ｋ２Ｏの含有量に対するＮａ２Ｏの含有量の質量比［Ｎａ２Ｏ／Ｋ２Ｏ］が１．５０以上である。 Third Embodiment The optical glass according to the third embodiment will be described in detail.
The optical glass according to the third embodiment is
The content of P 2 O 5 is 25 to 50%,
The Nb 2 O 5 content is 14-40%,
The total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 35 to 60%.
Mass ratio of TiO 2 content to total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more,
P 2 O 5 mass ratio of the content of B 2 O 3 to the content of [B 2 O 3 / P 2 O 5] is 0.05 to 0.39
The total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O [Li 2 O + Na 2 O + K 2 O + Cs 2 O] is 10% or more.
K 2 O weight ratio of Na 2 O content to the content of [Na 2 O / K 2 O ] is 1.50 or more.
　第３実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５の含有量は２５～５０％である。Ｐ２Ｏ５の含有量の下限は、好ましくは２６％であり、さらには２６．５％、２６．７の順により好ましい。また、Ｐ２Ｏ５の含有量の上限は、好ましくは４２％であり、さらには４０％、３８％、３７％、３６％の順により好ましい。 In the optical glass according to the third embodiment, the content of P 2 O 5 is 25-50%. The lower limit of the content of P 2 O 5 is preferably 26%, more preferably 26.5% and 26.7 in that order. The upper limit of the content of P 2 O 5 is preferably 42%, more preferably 40%, 38%, 37%, and 36%.
　Ｐ２Ｏ５は、ガラスのネットワーク形成成分であり、ガラス中に高分散成分を多く含有するために必須の成分である。Ｐ２Ｏ５の含有量を上記範囲とすることで、熱的安定性が高く、所望の光学恒数を有する光学ガラスが得られる。 P 2 O 5 is a network-forming component of glass, and is an essential component for containing a large amount of highly dispersed components in glass. By setting the content of P 2 O 5 in the above range, an optical glass having high thermal stability and a desired optical constant can be obtained.
　第３実施形態に係る光学ガラスにおいて、Ｎｂ２Ｏ５の含有量は１４～４０％である。Ｎｂ２Ｏ５の含有量の下限は、好ましくは１６％であり、さらには１７％、１８％、１９％、２０％の順により好ましい。また、Ｎｂ２Ｏ５の含有量の上限は、好ましくは３８％であり、さらには３６％、３４％、３２％の順により好ましい。 In the optical glass according to the third embodiment, the content of Nb 2 O 5 is 14 to 40%. The lower limit of the content of Nb 2 O 5 is preferably 16%, more preferably 17%, 18%, 19%, and 20% in that order. The upper limit of the content of Nb 2 O 5 is preferably 38%, more preferably 36%, 34%, and 32% in that order.
　Ｎｂ２Ｏ５は、高屈折率化および高分散化に寄与する成分である。したがって、Ｎｂ２Ｏ５の含有量は上記範囲とすることで、所望の光学恒数を有する光学ガラスが得られる。一方、Ｎｂ２Ｏ５の含有量が多すぎると、ガラスの着色が強まるおそれがある。 Nb 2 O 5 is a component that contributes to high refractive index and high dispersion. Therefore, by setting the content of Nb 2 O 5 in the above range, an optical glass having a desired optical constant can be obtained. On the other hand, if the content of Nb 2 O 5 is too large, the coloring of the glass may be strengthened.
　第３実施形態に係る光学ガラスにおいて、ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］は３５～６０％である。該合計含有量の下限は、好ましくは３６％であり、さらには３７％、３８％、３９％の順により好ましい。また、該合計含有量の上限は、好ましくは５５％であり、さらには５０％、４８％、４７％、４６％の順により好ましい。 In the optical glass according to the third embodiment, the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 35 to 60%. The lower limit of the total content is preferably 36%, more preferably 37%, 38%, and 39%. The upper limit of the total content is preferably 55%, more preferably 50%, 48%, 47%, and 46%.
　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５は、ガラスの高分散化に寄与する成分である。したがって、合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］を上記範囲とすることで、所望の光学恒数を有する光学ガラスが得られる。また、ガラスの熱的安定性も改善できる。一方、該合計含有量が多すぎると、所望の光学恒数を有する光学ガラスが得られないおそれがあり、また、ガラスの熱的安定性が低下し、ガラスの着色が強まるおそれがある。 TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 are components that contribute to high dispersion of glass. Therefore, by setting the total content [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] in the above range, an optical glass having a desired optical constant can be obtained. In addition, the thermal stability of the glass can be improved. On the other hand, if the total content is too large, an optical glass having a desired optical constant may not be obtained, the thermal stability of the glass may be lowered, and the coloring of the glass may be strengthened.
　第３実施形態に係る光学ガラスにおいて、ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量に対するＴｉＯ２の含有量の質量比[ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）]は０．２５以上である。該質量比の下限は、好ましくは０．２６であり、さらには０．２７、０．２８、０．２９、０．３０の順により好ましい。また、該質量比の上限は、好ましくは０．６５であり、さらには０．６０、０．５８、０．５６、０．５４、０．５２、０．５０、０．４８の順により好ましい。 In the optical glass according to the third embodiment, the mass ratio of the content of TiO 2 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TiO 2). + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 )] is 0.25 or more. The lower limit of the mass ratio is preferably 0.26, more preferably 0.27, 0.28, 0.29, 0.30 in that order. The upper limit of the mass ratio is preferably 0.65, and more preferably 0.60, 0.58, 0.56, 0.54, 0.52, 0.50, 0.48. ..
　ＴｉＯ２は、高屈折率化成分の中でも、特に高分散化の作用が大きい成分である。したがって、所望の光学恒数を得る観点から、質量比［ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）］は上記範囲であることが好ましい。 Among the high refractive index components, TiO 2 is a component having a particularly large effect of high dispersion. Therefore, from the viewpoint of obtaining a desired optical constant, the mass ratio [TiO 2 / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 )] is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５の含有量に対するＢ２Ｏ３の含有量の質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］は０．０５～０．３９である。該質量比の上限は、好ましくは０．３０であり、さらには０．２５、０．２２、０．２０、０．１９、０．１８の順により好ましい。また、該質量比の下限は、好ましくは０．０６であり、さらには０．０７、０．０８、０．０９の順により好ましい。 In the optical glass according to the third embodiment, the mass ratio of the content of B 2 O 3 to the content of P 2 O 5 [B 2 O 3 / P 2 O 5] is 0.05 to 0.39. The upper limit of the mass ratio is preferably 0.30, and more preferably 0.25, 0.22, 0.20, 0.19, and 0.18. The lower limit of the mass ratio is preferably 0.06, and more preferably 0.07, 0.08, and 0.09.
　質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］を上記範囲とすることで、所望の光学恒数を有し、熱的安定性が高く、耐失透性が高い光学ガラスが得られやすくなる。 By setting the mass ratio [B 2 O 3 / P 2 O 5 ] in the above range, it becomes easy to obtain an optical glass having a desired optical constant, high thermal stability, and high devitrification resistance. ..
　第３実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ］は１０％以上である。該合計含有量の下限は、好ましくは１２％であり、さらには１４％、１６％、１７％の順により好ましい。また、該合計含有量の上限は、好ましくは３５％であり、さらには３０％、２８％、２６％、２５％の順により好ましい。 In the optical glass according to the third embodiment, the total content [Li 2 O + Na 2 O + K 2 O + Cs 2 O] of Li 2 O, Na 2 O, K 2 O and Cs 2 O is 10% or more. The lower limit of the total content is preferably 12%, more preferably 14%, 16%, and 17% in that order. The upper limit of the total content is preferably 35%, more preferably 30%, 28%, 26%, and 25%.
　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏは、いずれもガラスの熱的安定性を改善する働きを有する。しかし、これらの含有量が多くなると、化学的耐久性、耐候性が低下するおそれがある。そのため、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ］は上記範囲であることが好ましい。 Li 2 O, Na 2 O, K 2 O and Cs 2 O all have a function of improving the thermal stability of glass. However, if these contents are high, the chemical durability and weather resistance may be lowered. Therefore, the total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O [Li 2 O + Na 2 O + K 2 O + Cs 2 O] is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｋ２Ｏの含有量に対するＮａ２Ｏの含有量の質量比［Ｎａ２Ｏ／Ｋ２Ｏ］は１．５０以上である。該質量比の下限は、好ましくは１．７０であり、さらには１．９０、２．１０、２．３０の順により好ましい。また、該質量比の上限は、好ましくは１０．０であり、さらには８．５０、７．５０、７．００、６．５０の順により好ましい。 In the optical glass according to the third embodiment, K 2 O weight ratio of Na 2 O content to the content of [Na 2 O / K 2 O ] is 1.50 or more. The lower limit of the mass ratio is preferably 1.70, more preferably 1.90, 2.10 and 2.30 in that order. The upper limit of the mass ratio is preferably 10.0, and more preferably 8.50, 7.50, 7.00, and 6.50.
　Ｎａ２ＯおよびＫ２Ｏは、ガラスの低比重化に寄与する成分であり、ガラスの熔融性を改善し、また平均線熱膨張係数を大きくする働きを有する。しかし、Ｋ２Ｏの含有量が多くなると、熱的安定性、耐失透性、化学的耐久性、耐候性が低下する。したがって、質量比［Ｎａ２Ｏ／Ｋ２Ｏ］は上記範囲であることが好ましい。 Na 2 O and K 2 O are components that contribute to lowering the specific gravity of glass, and have a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion. However, when the K 2 O content increases, the thermal stability, devitrification resistance, chemical durability, weather resistance decreases. Therefore, the mass ratio [Na 2 O / K 2 O] is preferably in the above range.
　第３実施形態に係る光学ガラスにおける上記以外のガラス成分の含有量および比率について、以下に非制限的な例を示す。 Non-limiting examples of the content and ratio of glass components other than the above in the optical glass according to the third embodiment are shown below.
　第３実施形態に係る光学ガラスにおいて、Ｂ２Ｏ３の含有量の上限は、好ましくは１０％であり、さらには９％、８％、７％、６％の順により好ましい。 In the optical glass according to the third embodiment, the upper limit of the content of B 2 O 3 is preferably 10%, more preferably 9%, 8%, 7%, and 6%.
　Ｂ２Ｏ３は、ガラスのネットワーク形成成分であり、ガラスの熱的安定性を改善する働きを有する。一方、Ｂ２Ｏ３の含有量が多いと、耐失透性が低下する傾向がある。そのためＢ２Ｏ３の含有量は上記範囲であることが好ましい。 B 2 O 3 is a network-forming component of glass and has a function of improving the thermal stability of glass. On the other hand, when the content of B 2 O 3 is large, the devitrification resistance tends to decrease. Therefore, the content of B 2 O 3 is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５およびＢ２Ｏ３の合計含有量に対するＢ２Ｏ３の含有量の質量比［Ｂ２Ｏ３／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］の上限は、好ましくは０．１８であり、さらには０．１７、０．１６、０．１５の順により好ましい。該質量比の下限は、好ましくは０であり、さらには０．０１、０．０３、０．０５の順により好ましい。 Third the optical glass according to the embodiment, P 2 O 5 and B 2 O total mass ratio of the content of B 2 O 3 to the content of 3 [B 2 O 3 / ( P 2 O 5 + B 2 O 3) ] Is preferably 0.18, more preferably 0.17, 0.16, 0.15 in that order. The lower limit of the mass ratio is preferably 0, more preferably 0.01, 0.03, 0.05.
　ガラスの熱的安定性および耐失透性を改善する観点から、質量比［Ｂ２Ｏ３／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］は上記範囲であることが好ましい。 From the viewpoint of improving the thermal stability and devitrification resistance of the glass, the mass ratio [B 2 O 3 / (P 2 O 5 + B 2 O 3 )] is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ａｌ２Ｏ３の含有量は、好ましくは３％以下であり、さらには２％以下、１％以下の順により好ましい。Ａｌ２Ｏ３の含有量は０％でもよい。 In the optical glass according to the third embodiment, the content of Al 2 O 3 is preferably 3% or less, more preferably 2% or less and 1% or less. The content of Al 2 O 3 may be 0%.
　Ａｌ２Ｏ３は、ガラスの化学的耐久性、耐候性を改善する働きを有するガラス成分であり、ネットワーク形成成分として考えることができる。一方、Ａｌ２Ｏ３の含有量が多くなると、ガラスの耐失透性が低下する。また、ガラス転移温度Ｔｇが上昇し、熱的安定性が低下する等の問題が生じやすい。このような問題を回避する観点から、Ａｌ２Ｏ３の含有量の上限は上記範囲であることが好ましい。 Al 2 O 3 is a glass component having a function of improving the chemical durability and weather resistance of glass, and can be considered as a network forming component. On the other hand, when the content of Al 2 O 3 increases, the devitrification resistance of the glass decreases. In addition, problems such as an increase in the glass transition temperature Tg and a decrease in thermal stability are likely to occur. From the viewpoint of avoiding such a problem, the upper limit of the content of Al 2 O 3 is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、ＳｉＯ２の含有量の上限は、好ましくは５％であり、さらには３％、２％、１％の順により好ましい。ＳｉＯ２の含有量は０％でもよい。 In the optical glass according to the third embodiment, the upper limit of the content of SiO 2 is preferably 5%, more preferably 3%, 2%, and 1%. The content of SiO 2 may be 0%.
　なお、ガラスの熔融に石英ガラス製坩堝などの石英ガラス製の熔融器具を使用することがある。この場合、熔融器具からガラス熔融物に少量のＳｉＯ２が溶け込むため、ガラス原料がＳｉＯ２を含んでいなくても作製したガラスは少量のＳｉＯ２を含有する。石英ガラス製の熔融器具からガラスに混入するＳｉＯ２の量は熔融条件にもよるが、例えば、全ガラス成分の含有量の合計に対し、０．５～１質量％程度である。ＳｉＯ２以外のガラス成分の含有比は一定のまま、ＳｉＯ２の量が０．５～１質量％程度増加する。なお、熔解条件によって上記量は増減する。ＳｉＯ２の含有量によって、屈折率、アッベ数などの光学特性が変化するので、ＳｉＯ２以外のガラス成分の含有量を微調整して所望の光学特性を有する光学ガラスを得る。 A quartz glass melting device such as a quartz glass crucible may be used to melt the glass. In this case, since a small amount of SiO 2 melts into the glass melt from the melting device, the glass frit is produced be free of SiO 2 contains a small amount of SiO 2. The amount of SiO 2 mixed into the glass from the quartz glass melting device depends on the melting conditions, but is, for example, about 0.5 to 1% by mass with respect to the total content of all glass components. The amount of SiO 2 increases by about 0.5 to 1% by mass while the content ratio of the glass component other than SiO 2 remains constant. The above amount may increase or decrease depending on the melting conditions. Since the optical characteristics such as the refractive index and the Abbe number change depending on the content of SiO 2, the content of the glass component other than SiO 2 is finely adjusted to obtain an optical glass having desired optical characteristics.
　ＳｉＯ２は、ガラスのネットワーク形成成分であり、ガラスの熱的安定性、化学的耐久性、耐候性を改善し、熔融ガラスの粘度を高め、熔融ガラスを成形しやすくする働きを有する。一方、ＳｉＯ２の含有量が多いと、ガラスの耐失透性が低下する傾向がある。そのため、ＳｉＯ２の含有量の上限は上記範囲であることが好ましい。 SiO 2 is a network-forming component of glass, and has a function of improving thermal stability, chemical durability, and weather resistance of glass, increasing the viscosity of molten glass, and facilitating molding of molten glass. On the other hand, when the content of SiO 2 is large, the devitrification resistance of the glass tends to decrease. Therefore, the upper limit of the content of SiO 2 is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量[Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２]の上限は、好ましくは５０％であり、さらには４５％、４３％、４２％、４１％の順により好ましい。該合計含有量の下限は、好ましくは２５％であり、さらには２７％、２８％、２９％の順により好ましい。 In the optical glass according to the third embodiment, the upper limit of the total content [P 2 O 5 + B 2 O 3 + SiO 2 ] of P 2 O 5 , B 2 O 3 and SiO 2 is preferably 50%, and further. Is more preferred in the order of 45%, 43%, 42%, 41%. The lower limit of the total content is preferably 25%, more preferably 27%, 28%, and 29%.
　合計含有量[Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２]を上記範囲とすることで、熱的安定性が高く、所望の光学恒数を有する光学ガラスが得られる。 By setting the total content [P 2 O 5 + B 2 O 3 + SiO 2 ] in the above range, an optical glass having high thermal stability and a desired optical constant can be obtained.
　第３実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５、Ｂ２Ｏ３、ＳｉＯ２、およびＡｌ２Ｏ３の合計含有量に対するＰ２Ｏ５およびＢ２Ｏ３の合計含有量の質量比[（Ｐ２Ｏ５＋Ｂ２Ｏ３）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３）]の下限は、好ましくは０．８０であり、さらには０．９０、０．９３、０．９６、０．９８の順により好ましい。該質量比の上限は、好ましくは１．００である。該質量比は１．００でもよい。 In the optical glass according to the third embodiment, the mass ratio of the total content of P 2 O 5 and B 2 O 3 to the total content of P 2 O 5 , B 2 O 3 , SiO 2 , and Al 2 O 3 [ The lower limit of (P 2 O 5 + B 2 O 3 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3 )] is preferably 0.80, and further 0.90, 0.93, It is more preferable in the order of 0.96 and 0.98. The upper limit of the mass ratio is preferably 1.00. The mass ratio may be 1.00.
　熱的安定性が高く、所望の光学恒数を有するガラスを得る観点から、質量比[（Ｐ２Ｏ５＋Ｂ２Ｏ３）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３）]は上記範囲であることが好ましい。 From the viewpoint of obtaining a glass having high thermal stability and a desired optical constant, the mass ratio [(P 2 O 5 + B 2 O 3 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3 )) ] Is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、ＴｉＯ２の含有量の下限は、好ましくは１０％であり、さらには１１％、１２％、１３％の順により好ましい。また、ＴｉＯ２の含有量の上限は、好ましくは５０％であり、さらには４０％、３５％、３０％、２８％、２６％、２３％、２１％の順により好ましい。 In the optical glass according to the third embodiment, the lower limit of the TiO 2 content is preferably 10%, more preferably 11%, 12%, and 13% in that order. The upper limit of the TiO 2 content is preferably 50%, more preferably 40%, 35%, 30%, 28%, 26%, 23%, and 21%.
　ＴｉＯ２は、高分散化に大きく寄与する。一方、ＴｉＯ２は、比較的ガラスの着色を増大させやすく、また、熔融性を悪化させるおそれがある。そのためＴｉＯ２の含有量は上記範囲であることが好ましい。 TiO 2 greatly contributes to high dispersion. On the other hand, TiO 2 tends to increase the coloring of the glass relatively easily, and may deteriorate the meltability. Therefore, the content of TiO 2 is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、ＷＯ３の含有量の上限は、好ましくは１５％であり、さらには１０％、５％、３％、２％、１％の順により好ましい。ＷＯ３の含有量は少ない方が好ましく、その下限は好ましくは０％である。ＷＯ３の含有量は０％でもよい。 In the optical glass according to the third embodiment, the upper limit of the content of WO 3 is preferably 15%, more preferably 10%, 5%, 3%, 2%, and 1%. The content of WO 3 is preferably low, and the lower limit thereof is preferably 0%. The content of WO 3 may be 0%.
　ＷＯ３の含有量を上記範囲とすることで、透過率を高めることができ、また、ガラスの比重の増大を抑制できる。また、相対屈折率の温度係数（ｄｎ／ｄＴ）を低くすることができる。 By setting the content of WO 3 in the above range, the transmittance can be increased and the increase in the specific gravity of the glass can be suppressed. Further, the temperature coefficient (dn / dT) of the relative refractive index can be lowered.
　第３実施形態に係る光学ガラスにおいて、Ｂｉ２Ｏ３の含有量の上限は、好ましくは１５％であり、さらには１０％、７％、５％、３％の順により好ましい。また、Ｂｉ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the third embodiment, the upper limit of the content of Bi 2 O 3 is preferably 15%, more preferably 10%, 7%, 5%, and 3%. The lower limit of the Bi 2 O 3 content is preferably 0%.
　Ｂｉ２Ｏ３は、適量を含有させることによりガラスの熱的安定性を改善する働きを有する。一方、Ｂｉ２Ｏ３の含有量を高めると、ガラスの着色が増大する。したがって、Ｂｉ２Ｏ３の含有量は上記範囲であることが好ましい。 Bi 2 O 3 has a function of improving the thermal stability of glass by containing an appropriate amount. On the other hand, when the content of Bi 2 O 3 is increased, the coloring of the glass is increased. Therefore, the content of Bi 2 O 3 is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５およびＢ２Ｏ３の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］の上限は、好ましくは０．７０であり、さらには０．６６、０．６４、０．６２、０．６０の順により好ましい。該質量比の下限は、好ましくは０．２５であり、さらには０．２７、０．２９、０．３１の順により好ましい。 In the optical glass according to the third embodiment, the upper limit of the mass ratio [TiO 2 / (P 2 O 5 + B 2 O 3 )] of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 is , Preferably 0.70, and more preferably 0.66, 0.64, 0.62, 0.60. The lower limit of the mass ratio is preferably 0.25, more preferably 0.27, 0.29, 0.31 in that order.
　質量比［ＴｉＯ２／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］を上記範囲とすることで、所望の光学恒数を有し、熱的安定性が高い光学ガラスが得られやすくなる。 By setting the mass ratio [TiO 2 / (P 2 O 5 + B 2 O 3 )] to the above range, it becomes easy to obtain an optical glass having a desired optical constant and high thermal stability.
　第３実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５の含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／Ｐ２Ｏ５］の上限は、好ましくは０．７０であり、さらには０．６６、０．６４、０．６２の順により好ましい。該質量比の下限は、好ましくは０．２５であり、さらには０．２８、０．３１、０．３４の順により好ましい。 In the optical glass according to the third embodiment, the upper limit of the mass ratio of the content of TiO 2 [TiO 2 / P 2 O 5] to the content of P 2 O 5 is preferably 0.70, more 0 It is more preferable in the order of .66, 0.64, 0.62. The lower limit of the mass ratio is preferably 0.25, more preferably 0.28, 0.31 and 0.34.
　質量比［ＴｉＯ２／Ｐ２Ｏ５］を上記範囲とすることで、所望の光学恒数を有し、熱的安定性が高い光学ガラスが得られやすくなる。 By setting the mass ratio [TiO 2 / P 2 O 5 ] to the above range, it becomes easy to obtain an optical glass having a desired optical constant and high thermal stability.
　第３実施形態に係る光学ガラスにおいて、ＴｉＯ２およびＮｂ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５］の下限は、好ましくは３５．０％であり、さらには３７．０％、３９．０％、４０．０％の順により好ましい。また、該合計含有量の上限は、好ましくは６５．０％であり、さらには６０．０％、５５．０％、５０．０％、４８．０％、４６．０％の順により好ましい。 In the optical glass according to the third embodiment, the lower limit of the total content [TiO 2 + Nb 2 O 5 ] of TiO 2 and Nb 2 O 5 is preferably 35.0%, and further 37.0% and 39. It is more preferable in the order of 0.0% and 40.0%. The upper limit of the total content is preferably 65.0%, more preferably 60.0%, 55.0%, 50.0%, 48.0%, and 46.0%.
　高屈折率高分散であって、ガラスの熱的安定性の優れるガラスを得る観点から、該合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５］は上記範囲であることが好ましい。 From the viewpoint of obtaining a glass having a high refractive index and a high dispersion and excellent thermal stability of the glass, the total content [TiO 2 + Nb 2 O 5 ] is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｎｂ２Ｏ５およびＷＯ３の合計含有量に対するＮｂ２Ｏ５の含有量の質量比［Ｎｂ２Ｏ５／（Ｎｂ２Ｏ５＋ＷＯ３）］の下限は、好ましくは０．７０であり、さらには０．８０、０．９０、０．９５の順により好ましい。また、該質量比の上限は、好ましくは１．００である。該質量比は１．００でもよい。 In the optical glass according to the third embodiment, the lower limit of the mass ratio of the content of Nb 2 O 5 to the total content of Nb 2 O 5 and WO 3 [Nb 2 O 5 / (Nb 2 O 5 + WO 3)] is , It is preferably 0.70, and more preferably 0.80, 0.90, 0.95 in that order. The upper limit of the mass ratio is preferably 1.00. The mass ratio may be 1.00.
　高屈折率高分散であって、相対屈折率の温度係数（ｄｎ／ｄＴ）の上昇が抑制されたガラスを得る観点から、質量比［Ｎｂ２Ｏ５／（Ｎｂ２Ｏ５＋ＷＯ３）］は上記範囲であることが好ましい。 From the viewpoint of obtaining a glass having a high refractive index and a high dispersion and suppressed increase in the temperature coefficient (dn / dT) of the relative refractive index, the mass ratio [Nb 2 O 5 / (Nb 2 O 5 + WO 3 )] is It is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、ＴｉＯ２およびＷＯ３の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（ＴｉＯ２＋ＷＯ３）］の下限は、好ましくは０．７０であり、さらには０．８０、０．９０、０．９５の順により好ましい。また、該質量比の上限は、好ましくは１．００である。該質量比は１．００でもよい。 In the optical glass according to the third embodiment, the lower limit of the mass ratio of the content of TiO 2 to the total content of TiO 2 and WO 3 [TiO 2 / (TiO 2 + WO 3 )] is preferably 0.70. Further, it is more preferable in the order of 0.80, 0.90, 0.95. The upper limit of the mass ratio is preferably 1.00. The mass ratio may be 1.00.
　高分散であって、相対屈折率の温度係数（ｄｎ／ｄＴ）の上昇が抑制されたガラスを得る観点から、質量比［ＴｉＯ２／（ＴｉＯ２＋ＷＯ３）］は上記範囲であることが好ましい。 From the viewpoint of obtaining a glass having a high dispersion and suppressed increase in the temperature coefficient (dn / dT) of the relative refractive index, the mass ratio [TiO 2 / (TiO 2 + WO 3 )] is preferably in the above range. ..
　第３実施形態に係る光学ガラスにおいて、ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、およびＢｉ２Ｏ３の合計含有量に対するＴｉＯ２およびＮｂ２Ｏ５の合計含有量の質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５）／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３）］の下限は、好ましくは０．７０であり、さらには０．８０、０．９０、０．９５の順により好ましい。また、該質量比の上限は、好ましくは１．００である。該質量比は１．００でもよい。 In the optical glass according to the third embodiment, the mass ratio of the total content of TiO 2 and Nb 2 O 5 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , and Bi 2 O 3 [(TiO 2 + Nb). The lower limit of 2 O 5 ) / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 )] is preferably 0.70, and more preferably 0.80, 0.90, and 0.95. The upper limit of the mass ratio is preferably 1.00. The mass ratio may be 1.00.
　高屈折率高分散であって、相対屈折率の温度係数（ｄｎ／ｄＴ）の上昇が抑制されたガラスを得る観点から、質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５）／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３）］は上記範囲であることが好ましい。 From the viewpoint of obtaining a glass having a high refractive index and a high dispersion and suppressed increase in the temperature coefficient (dn / dT) of the relative refractive index, the mass ratio [(TiO 2 + Nb 2 O 5 ) / (TiO 2 + Nb 2 O) 5 + WO 3 + Bi 2 O 3 )] is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｔａ２Ｏ５の含有量の上限は、好ましくは１０％であり、さらには７％、５％、３％の順により好ましい。また、Ｔａ２Ｏ５の含有量の下限は、好ましくは０％である。Ｔａ２Ｏ５の含有量は０％でもよい。 In the optical glass according to the third embodiment, the upper limit of the content of Ta 2 O 5 is preferably 10%, more preferably 7%, 5%, and 3%. The lower limit of the content of Ta 2 O 5 is preferably 0%. The content of Ta 2 O 5 may be 0%.
　Ｔａ２Ｏ５は、ガラスの熱的安定性および耐失透性を改善する働きを有するガラス成分である。一方、Ｔａ２Ｏ５は、屈折率を上昇させ、ガラスを高分散化させる。また、Ｔａ２Ｏ５の含有量が多くなると、ガラスの熱的安定性が低下し、ガラスを熔融するときに、ガラス原料の熔け残りが生じやすくなる。そのため、Ｔａ２Ｏ５の含有量は上記範囲であることが好ましい。さらに、Ｔａ２Ｏ５は、他のガラス成分と比較し、極めて高価な成分であり、Ｔａ２Ｏ５の含有量が多くなるとガラスの生産コストが増大する。さらに、Ｔａ２Ｏ５は他のガラス成分と比べて分子量が大きいため、ガラスの比重を増大させ、結果的に光学素子の重量を増大させる。 Ta 2 O 5 is a glass component having a function of improving the thermal stability and devitrification resistance of glass. On the other hand, Ta 2 O 5 increases the refractive index and makes the glass highly dispersed. Further, when the content of Ta 2 O 5 is increased, the thermal stability of the glass is lowered, and when the glass is melted, the unmelted residue of the glass raw material is likely to occur. Therefore, the content of Ta 2 O 5 is preferably in the above range. Further, Ta 2 O 5 is an extremely expensive component as compared with other glass components, and as the content of Ta 2 O 5 increases, the production cost of glass increases. Further, since Ta 2 O 5 has a larger molecular weight than other glass components, it increases the specific gravity of the glass, and as a result, increases the weight of the optical element.
　第３実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏの含有量の上限は、好ましくは５％であり、さらには３％、２％、１％の順により好ましい。Ｌｉ２Ｏの含有量の下限は、好ましくは０％である。Ｌｉ２Ｏの含有量は０％でもよい。 In the optical glass according to the third embodiment, the upper limit of the Li 2 O content is preferably 5%, more preferably 3%, 2%, and 1%. The lower limit of the Li 2 O content is preferably 0%. The content of Li 2 O may be 0%.
　Ｌｉ２Ｏは、ガラスの低比重化に寄与する成分であり、ガラスの熔融性を改善し、また平均線熱膨張係数を大きくする働きを有する。一方、Ｌｉ２Ｏの含有量が多くなると、耐失透性が低下する。したがって、Ｌｉ２Ｏの含有量は上記範囲であることが好ましい。 Li 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion. On the other hand, as the content of Li 2 O increases, the devitrification resistance decreases. Therefore, the Li 2 O content is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｎａ２Ｏの含有量の下限は、好ましくは６％であり、さらには１０％、１２％、１３％の順により好ましい。また、Ｎａ２Ｏの含有量の上限は、好ましくは３０％であり、さらには２２％、２０％、１９％、１８％の順により好ましい。 In the optical glass according to the third embodiment, the lower limit of the Na 2 O content is preferably 6%, more preferably 10%, 12%, and 13% in that order. The upper limit of the Na 2 O content is preferably 30%, more preferably 22%, 20%, 19%, and 18%.
　Ｎａ２Ｏは、ガラスの低比重化に寄与する成分であり、ガラスの熔融性を改善し、また平均線熱膨張係数を大きくする働きを有する。一方、Ｎａ２Ｏの含有量が多くなると、耐失透性が低下する。したがって、Ｎａ２Ｏの含有量は上記範囲であることが好ましい。 Na 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the meltability of glass and increasing the average coefficient of linear thermal expansion. On the other hand, as the Na 2 O content increases, the devitrification resistance decreases. Therefore, the Na 2 O content is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｋ２Ｏの含有量の下限は、好ましくは１％であり、さらには２％、３％、４％の順により好ましい。また、Ｋ２Ｏの含有量の上限は、好ましくは１３％であり、さらには１２％、１１％、１０％の順により好ましい。 In the optical glass according to the third embodiment, the lower limit of K 2 O content is preferably 1%, even 2%, 3%, preferably by 4% order. The upper limit of the content of K 2 O is preferably 13%, further 12%, 11%, preferably by 10% order.
　Ｋ２Ｏは、ガラスの低比重化に寄与する成分であり、ガラスの熱的安定性を改善する働きを有する。また平均線熱膨張係数を大きくする働きを有する。一方、Ｋ２Ｏの含有量が多くなると、熱的安定性、耐失透性、化学的耐久性、耐候性が低下する。したがって、Ｋ２Ｏの含有量は上記範囲であることが好ましい。 K 2 O is a component that contributes to lowering the specific gravity of glass, and has a function of improving the thermal stability of glass. It also has the function of increasing the average coefficient of linear thermal expansion. On the other hand, when the K 2 O content increases, the thermal stability, devitrification resistance, chemical durability, weather resistance decreases. Therefore, it is preferable that the content of K 2 O is within the above range.
　第３実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏ、Ｎａ２ＯおよびＫ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ］の上限は、好ましくは３５％であり、さらには３０％、２８％、２６％、２５％の順により好ましい。また、該合計含有量の下限は、好ましくは１０％であり、さらには１４％、１５％、１６％、１７％の順により好ましい。 In the optical glass according to the third embodiment, the upper limit of the total content [Li 2 O + Na 2 O + K 2 O] of Li 2 O, Na 2 O and K 2 O is preferably 35%, further 30%. 28%, 26%, and 25% are more preferable in this order. The lower limit of the total content is preferably 10%, more preferably 14%, 15%, 16%, and 17%.
　Ｌｉ２Ｏ、Ｎａ２ＯおよびＫ２Ｏは、いずれもガラスの熱的安定性を改善する働きを有する。しかし、これらの含有量が多くなると、化学的耐久性、耐候性が低下するおそれがある。そのため、Ｌｉ２Ｏ、Ｎａ２ＯおよびＫ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ］は上記範囲であることが好ましい。 Li 2 O, Na 2 O and K 2 O all have a function of improving the thermal stability of glass. However, if these contents are high, the chemical durability and weather resistance may be lowered. Therefore, the total content of Li 2 O, Na 2 O and K 2 O [Li 2 O + Na 2 O + K 2 O] is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｃｓ２Ｏの含有量の上限は、好ましくは５％であり、さらには３％、２％、１％の順により好ましい。また、Ｃｓ２Ｏの含有量の下限は、好ましくは０％である。Ｃｓ２Ｏの含有量は０％でもよい。 In the optical glass according to the third embodiment, the upper limit of the content of Cs 2 O is preferably 5%, more preferably 3%, 2%, and 1%. The lower limit of the Cs 2 O content is preferably 0%. The content of Cs 2 O may be 0%.
　Ｃｓ２Ｏは、ガラスの熔融性を改善する働きを有するが、含有量が多くなると、ガラスの熱的安定性、屈折率ｎｄが低下し、また熔解中にガラス成分の揮発が増加して、所望のガラスが得られなくなる。そのため、Ｃｓ２Ｏの含有量は上記範囲であることが好ましい。 Cs 2 O has a function of improving the meltability of glass, but when the content is increased, the thermal stability and refractive index nd of the glass are lowered, and the volatilization of the glass component is increased during melting. The desired glass cannot be obtained. Therefore, the content of Cs 2 O is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＮａ２Ｏの含有量の質量比［Ｎａ２Ｏ／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］の下限は、好ましくは０．２０であり、０．５０、０．５５、０．６０、０．６５の順により好ましい。該質量比の上限は、好ましくは０．９８であり、さらには０．９５、０．９２、０．９０、０．８８の順により好ましい。 In the optical glass according to the third embodiment, the mass ratio of the content of Na 2 O to the total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O [Na 2 O / (Li 2 O + Na 2 O + K). The lower limit of 2 O + Cs 2 O)] is preferably 0.20, more preferably 0.50, 0.55, 0.60, 0.65. The upper limit of the mass ratio is preferably 0.98, more preferably 0.95, 0.92, 0.90, 0.88.
　耐失透性および熱安定性に優れるガラスを得る観点から、質量比［Ｎａ２Ｏ／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］は上記範囲であることが好ましい。 From the viewpoint of obtaining a glass having excellent devitrification resistance and thermal stability, the mass ratio [Na 2 O / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］の上限は、好ましくは２．５０であり、さらには２．４０、２．３５、２．３０、２．２７、２．２５の順により好ましい。また、該質量比の下限は、好ましくは１．２０であり、さらには１．３０、１．３５、１．３８、１．４０の順により好ましい。 In the optical glass according to the third embodiment, the mass ratio of the total contents of P 2 O 5 , B 2 O 3 and SiO 2 to the total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [ The upper limit of (P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is preferably 2.50, and further 2.40, 2.35, 2.30. It is more preferable in the order of 2.27 and 2.25. The lower limit of the mass ratio is preferably 1.20, and more preferably 1.30, 1.35, 1.38, and 1.40 in that order.
　質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］を上記範囲とすることで、熱的安定性が高く、相対屈折率の温度係数（ｄｎ／ｄＴ）が低く、平均線熱膨張係数の大きい光学ガラスが得られる。 By setting the mass ratio [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] in the above range, the thermal stability is high and the temperature coefficient of relative refractive index ( An optical glass having a low dn / dT) and a large average coefficient of linear thermal expansion can be obtained.
　第３実施形態に係る光学ガラスにおいて、ＭｇＯの含有量は、好ましくは５％以下であり、さらには３％以下、１％以下の順により好ましい。また、ＭｇＯの含有量の下限は、好ましくは０％である。ＭｇＯの含有量は０％であってもよい。 In the optical glass according to the third embodiment, the content of MgO is preferably 5% or less, more preferably 3% or less and 1% or less. The lower limit of the MgO content is preferably 0%. The content of MgO may be 0%.
　第３実施形態に係る光学ガラスにおいて、ＣａＯの含有量は、好ましくは５％以下であり、さらには３％以下、１％以下の順により好ましい。また、ＣａＯの含有量の下限は、好ましくは０％である。ＣａＯの含有量は０％であってもよい。 In the optical glass according to the third embodiment, the CaO content is preferably 5% or less, more preferably 3% or less and 1% or less. The lower limit of the CaO content is preferably 0%. The CaO content may be 0%.
　第３実施形態に係る光学ガラスにおいて、ＳｒＯの含有量は、好ましくは６％以下であり、さらには５％以下、３％以下、１％以下の順により好ましい。また、ＳｒＯの含有量の下限は、好ましくは０％である。 In the optical glass according to the third embodiment, the SrO content is preferably 6% or less, more preferably 5% or less, 3% or less, and 1% or less. The lower limit of the SrO content is preferably 0%.
　第３実施形態に係る光学ガラスにおいて、ＢａＯの含有量は、好ましくは８％以下であり、さらには５％以下、３％以下、１％以下の順により好ましい。また、ＢａＯの含有量の下限は、好ましくは０％である。 In the optical glass according to the third embodiment, the BaO content is preferably 8% or less, more preferably 5% or less, 3% or less, and 1% or less. The lower limit of the BaO content is preferably 0%.
　第３実施形態に係る光学ガラスにおいて、ＭｇＯ、ＣａＯ、ＳｒＯ、およびＢａＯの合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］の上限は、好ましくは８．０％であり、さらには、５．０％、４．０％、３．０％、１．５％、１．０％、０．５％の順により好ましい。また、該合計含有量の下限は、好ましくは０％である。該合計含有量は０％でもよい。 In the optical glass according to the third embodiment, the upper limit of the total content [MgO + CaO + SrO + BaO] of MgO, CaO, SrO, and BaO is preferably 8.0%, and further 5.0% and 4.0%. , 3.0%, 1.5%, 1.0%, 0.5% in that order. The lower limit of the total content is preferably 0%. The total content may be 0%.
　ＭｇＯ、ＣａＯ、ＳｒＯ、ＢａＯは、いずれもガラスの熱的安定性および耐失透性を改善する働きを有するガラス成分である。しかし、これらガラス成分の含有量が多くなると、高分散性が損なわれ、また、ガラスの熱的安定性および耐失透性が低下する。また、ＢａＯの含有量が多すぎるとガラスの比重が増大する。そのため、これらガラス成分の各含有量および合計含有量は、上記範囲であることが好ましい。 MgO, CaO, SrO, and BaO are all glass components having a function of improving the thermal stability and devitrification resistance of glass. However, when the content of these glass components is increased, the high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass are lowered. Further, if the BaO content is too large, the specific gravity of the glass increases. Therefore, each content and total content of these glass components are preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、ＺｎＯの含有量の上限は、好ましくは１０％であり、さらには６％、４％、３％の順により好ましい。ＺｎＯ含有量は少ない方が好ましく、その下限は好ましくは０％である。ＺｎＯの含有量は０％でもよい。 In the optical glass according to the third embodiment, the upper limit of the ZnO content is preferably 10%, more preferably 6%, 4%, and 3%. The ZnO content is preferably low, and the lower limit thereof is preferably 0%. The ZnO content may be 0%.
　ＺｎＯは、ガラスの熱的安定性を改善する働きを有するガラス成分である。しかし、ＺｎＯの含有量が多すぎるとガラスの比重が増大する。また、相対屈折率の温度係数（ｄｎ／ｄＴ）が高くなる。そのため、ＺｎＯの含有量は上記範囲であることが好ましい。 ZnO is a glass component having a function of improving the thermal stability of glass. However, if the ZnO content is too high, the specific gravity of the glass increases. Further, the temperature coefficient (dn / dT) of the relative refractive index becomes high. Therefore, the ZnO content is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｎａ２ＯおよびＺｎＯの合計含有量に対するＮａ２Ｏの含有量の質量比［Ｎａ２Ｏ／（Ｎａ２Ｏ＋ＺｎＯ）］の下限は、好ましくは０．５０であり、さらには０．６０、０．７０、０．９０の順により好ましい。また、該質量比の上限は、好ましくは１．００である。該質量比は１．００でもよい。 In the optical glass according to the third embodiment, the lower limit of the mass ratio [Na 2 O / (Na 2 O + Zn O)] of the content of Na 2 O to the total content of Na 2 O and Zn O is preferably 0.50. Yes, more preferably in the order of 0.60, 0.70, 0.90. The upper limit of the mass ratio is preferably 1.00. The mass ratio may be 1.00.
　ガラスの比重が増大するのを抑制し、また、相対屈折率の温度係数（ｄｎ／ｄＴ）が上昇するのを抑制する観点から、質量比［Ｎａ２Ｏ／（Ｎａ２Ｏ＋ＺｎＯ）］は上記範囲であることが好ましい。 The mass ratio [Na 2 O / (Na 2 O + Zn O)] is in the above range from the viewpoint of suppressing an increase in the specific gravity of the glass and suppressing an increase in the temperature coefficient (dn / dT) of the relative refractive index. Is preferable.
　第３実施形態に係る光学ガラスにおいて、ＴｉＯ２およびＺｎＯの合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（ＴｉＯ２＋ＺｎＯ）］の下限は、好ましくは０．７０であり、さらには０．８０、０．９０、０．９５の順により好ましい。また、該質量比の上限は、好ましくは１．００である。該質量比は１．００でもよい。 In the optical glass according to the third embodiment, the lower limit of the mass ratio [TiO 2 / (TiO 2 + ZnO)] of the content of TiO 2 to the total content of TiO 2 and ZnO is preferably 0.70, and further. Is more preferable in the order of 0.80, 0.90, 0.95. The upper limit of the mass ratio is preferably 1.00. The mass ratio may be 1.00.
　高分散であって、相対屈折率の温度係数（ｄｎ／ｄＴ）の上昇を抑制されたガラスを得る観点から、質量比［ＴｉＯ２／（ＴｉＯ２＋ＺｎＯ）］は上記範囲であることが好ましい。 From the viewpoint of obtaining a glass having a high dispersion and suppressing an increase in the temperature coefficient (dn / dT) of the relative refractive index, the mass ratio [TiO 2 / (TiO 2 + ZnO)] is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＺｎＯの合計含有量に対するＴｉＯ２およびＮｂ２Ｏ５の合計含有量の質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５）／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋ＺｎＯ）］の下限は、好ましくは０．７０であり、さらには０．８０、０．９０、０．９５の順により好ましい。また、該質量比の上限は、好ましくは１．００である。該質量比は１．００でもよい。 In the optical glass according to the third embodiment, the mass ratio of the total content of TiO 2 and Nb 2 O 5 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Zn O [(TIO 2). The lower limit of [+ Nb 2 O 5 ) / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + ZnO)] is preferably 0.70, and further in the order of 0.80, 0.90, 0.95. preferable. The upper limit of the mass ratio is preferably 1.00. The mass ratio may be 1.00.
　高屈折率高分散であって、相対屈折率の温度係数（ｄｎ／ｄＴ）の上昇が抑制されたガラスを得る観点から、質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５）／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋ＺｎＯ）］は上記範囲であることが好ましい。 From the viewpoint of obtaining a glass having a high refractive index and a high dispersion and suppressed increase in the temperature coefficient (dn / dT) of the relative refractive index, the mass ratio [(TiO 2 + Nb 2 O 5 ) / (TiO 2 + Nb 2 O) 5 + WO 3 + Bi 2 O 3 + ZnO)] is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｐ２Ｏ５、Ｂ２Ｏ３、ＳｉＯ２、Ａｌ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量の質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３＋Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］は１．１０以下であることが好ましい。該質量比の上限は、好ましくは１．００であり、さらには０．９５、０．９０、０．８５、０．８２、０．８０の順により好ましい。また、該質量比の下限は、より好ましくは０．５０であり、さらには０．６０、０．６５、０．６８、０．７０の順により好ましい。 In the optical glass according to the third embodiment, TiO 2 with respect to the total content of P 2 O 5 , B 2 O 3 , SiO 2 , Al 2 O 3 , Li 2 O, Na 2 O, K 2 O and Cs 2 O. , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 total content mass ratio [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5) / (P 2 O 5) + B 2 O 3 + SiO 2 + Al 2 O 3 + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is preferably 1.10 or less. The upper limit of the mass ratio is preferably 1.00, more preferably 0.95, 0.90, 0.85, 0.82, 0.80. The lower limit of the mass ratio is more preferably 0.50, and further preferably 0.60, 0.65, 0.68, 0.70 in that order.
　質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３＋Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］を上記範囲とすることで、所望の光学恒数を有する光学ガラスが得られやすくなる。 Mass ratio [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3 + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] By setting the range, it becomes easy to obtain an optical glass having a desired optical constant.
　第３実施形態に係る光学ガラスにおいて、ＺｒＯ２の含有量は、好ましくは５％以下であり、さらには３％以下、１％以下の順により好ましい。また、ＺｒＯ２の含有量の下限は、好ましくは０％である。 In the optical glass according to the third embodiment, the content of ZrO 2 is preferably 5% or less, more preferably 3% or less and 1% or less. The lower limit of the ZrO 2 content is preferably 0%.
　ＺｒＯ２は、ガラスの熱的安定性および耐失透性を改善する働きを有するガラス成分である。しかし、ＺｒＯ２の含有量が多すぎると、熱的安定性が低下する傾向を示す。そのため、ＺｒＯ２の含有量は上記範囲であることが好ましい。 ZrO 2 is a glass component having a function of improving the thermal stability and devitrification resistance of glass. However, if the content of ZrO 2 is too high, the thermal stability tends to decrease. Therefore, the content of ZrO 2 is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｓｃ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｓｃ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the third embodiment, the upper limit of the Sc 2 O 3 content is preferably 2%. The lower limit of the Sc 2 O 3 content is preferably 0%.
　第３実施形態に係る光学ガラスにおいて、ＨｆＯ２の含有量の上限は、好ましくは２％である。また、ＨｆＯ２の含有量の下限は、好ましくは０％である。 In the optical glass according to the third embodiment, the upper limit of the HfO 2 content is preferably 2%. The lower limit of the HfO 2 content is preferably 0%.
　Ｓｃ２Ｏ３、ＨｆＯ２は、いずれも屈折率ｎｄを高める働きを有し、また高価な成分である。そのため、Ｓｃ２Ｏ３、ＨｆＯ２の各含有量は上記範囲であることが好ましい。 Sc 2 O 3 and HfO 2 both have a function of increasing the refractive index nd and are expensive components. Therefore, the contents of Sc 2 O 3 and HfO 2 are preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｌｕ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｌｕ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the third embodiment, the upper limit of the content of Lu 2 O 3 is preferably 2%. The lower limit of the content of Lu 2 O 3 is preferably 0%.
　Ｌｕ２Ｏ３は、屈折率ｎｄを高める働きを有する。また、分子量が大きいことから、ガラスの比重を増加させるガラス成分でもある。そのため、Ｌｕ２Ｏ３の含有量は上記範囲であることが好ましい。 Lu 2 O 3 has a function of increasing the refractive index nd. In addition, since it has a large molecular weight, it is also a glass component that increases the specific gravity of glass. Therefore, the content of Lu 2 O 3 is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、ＧｅＯ２の含有量の上限は、好ましくは２％である。また、ＧｅＯ２の含有量の下限は、好ましくは０％である。 In the optical glass according to the third embodiment, the upper limit of the content of GeO 2 is preferably 2%. The lower limit of the content of GeO 2 is preferably 0%.
　ＧｅＯ２は、屈折率ｎｄを高める働きを有し、また、一般的に使用されるガラス成分の中で、突出して高価な成分である。したがって、ガラスの製造コストを低減する観点から、ＧｅＯ２の含有量は上記範囲であることが好ましい。 GeO 2 has a function of increasing the refractive index nd, and is a prominently expensive component among commonly used glass components. Therefore, from the viewpoint of reducing the manufacturing cost of glass, the content of GeO 2 is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、Ｌａ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｌａ２Ｏ３の含有量の下限は、好ましくは０％である。Ｌａ２Ｏ３の含有量は０％であってもよい。 In the optical glass according to the third embodiment, the upper limit of the content of La 2 O 3 is preferably 2%. The lower limit of the content of La 2 O 3 is preferably 0%. The content of La 2 O 3 may be 0%.
　Ｌａ２Ｏ３の含有量が多くなるとガラスの熱的安定性および耐失透性が低下し、製造中にガラスが失透しやすくなる。したがって、熱的安定性および耐失透性の低下を抑制する観点から、Ｌａ２Ｏ３の含有量は上記範囲であることが好ましい。 When the content of La 2 O 3 is increased, the thermal stability and devitrification resistance of the glass are lowered, and the glass is easily devitrified during production. Therefore, the content of La 2 O 3 is preferably in the above range from the viewpoint of suppressing the decrease in thermal stability and devitrification resistance.
　第３実施形態に係る光学ガラスにおいて、Ｇｄ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｇｄ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the third embodiment, the upper limit of the content of Gd 2 O 3 is preferably 2%. The lower limit of the content of Gd 2 O 3 is preferably 0%.
　Ｇｄ２Ｏ３の含有量が多くなり過ぎるとガラスの熱的安定性および耐失透性が低下し、製造中にガラスが失透しやすくなる。また、Ｇｄ２Ｏ３の含有量が多くなり過ぎるとガラスの比重が増大し、好ましくない。したがって、ガラスの熱的安定性および耐失透性を良好に維持しつつ、比重の増大を抑制する観点から、Ｇｄ２Ｏ３の含有量は上記範囲であることが好ましい。 If the content of Gd 2 O 3 is too high, the thermal stability and devitrification resistance of the glass will decrease, and the glass will easily devitrify during production. Further, if the content of Gd 2 O 3 becomes too large, the specific gravity of the glass increases, which is not preferable. Therefore, the content of Gd 2 O 3 is preferably in the above range from the viewpoint of suppressing an increase in specific gravity while maintaining good thermal stability and devitrification resistance of the glass.
　第３実施形態に係る光学ガラスにおいて、Ｙ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｙ２Ｏ３の含有量の下限は、好ましくは０％である。Ｙ２Ｏ３の含有量は０％であってもよい。 In the optical glass according to the third embodiment, the upper limit of the content of Y 2 O 3 is preferably 2%. The lower limit of the content of Y 2 O 3 is preferably 0%. The content of Y 2 O 3 may be 0%.
　Ｙ２Ｏ３の含有量が多くなり過ぎるとガラスの熱的安定性および耐失透性が低下する。したがって、熱的安定性および耐失透性の低下を抑制する観点から、Ｙ２Ｏ３の含有量は上記範囲であることが好ましい。 If the content of Y 2 O 3 is too high, the thermal stability and devitrification resistance of the glass will decrease. Therefore, from the viewpoint of suppressing a decrease in the thermal stability and devitrification resistance, the content of Y 2 O 3 is preferably in the range.
　第３実施形態に係る光学ガラスにおいて、Ｙｂ２Ｏ３の含有量の上限は、好ましくは２％である。また、Ｙｂ２Ｏ３の含有量の下限は、好ましくは０％である。 In the optical glass according to the third embodiment, the upper limit of the content of Yb 2 O 3 is preferably 2%. The lower limit of the content of Yb 2 O 3 is preferably 0%.
　Ｙｂ２Ｏ３は、Ｌａ２Ｏ３、Ｇｄ２Ｏ３、Ｙ２Ｏ３と比べて分子量が大きいため、ガラスの比重を増大させる。ガラスの比重が増大すると、光学素子の質量が増大する。例えば、質量の大きいレンズをオートフォーカス式の撮像レンズに組み込むと、オートフォーカス時にレンズの駆動に要する電力が増大し、電池の消耗が激しくなる。したがって、Ｙｂ２Ｏ３の含有量を低減させて、ガラスの比重の増大を抑えることが望ましい。 Since Yb 2 O 3 has a larger molecular weight than La 2 O 3 , Gd 2 O 3 , and Y 2 O 3 , it increases the specific gravity of glass. As the specific gravity of glass increases, the mass of the optical element increases. For example, if a lens having a large mass is incorporated into an autofocus type imaging lens, the power required to drive the lens during autofocus increases, and the battery consumption increases. Therefore, it is desirable to reduce the content of Yb 2 O 3 to suppress the increase in the specific gravity of the glass.
　また、Ｙｂ２Ｏ３の含有量が多すぎるとガラスの熱的安定性および耐失透性が低下する。ガラスの熱的安定性の低下を防ぎ、比重の増大を抑制する観点から、Ｙｂ２Ｏ３の含有量は上記範囲であることが好ましい。 Further, if the content of Yb 2 O 3 is too large, the thermal stability and devitrification resistance of the glass are lowered. The content of Yb 2 O 3 is preferably in the above range from the viewpoint of preventing a decrease in thermal stability of the glass and suppressing an increase in specific gravity.
　第３実施形態に係る光学ガラスは、主として上述のガラス成分、すなわち、必須成分としてＰ２Ｏ５、Ｎｂ２Ｏ５、Ｂ２Ｏ３、ＴｉＯ２、Ｎａ２Ｏ、Ｋ２Ｏ、任意成分としてＡｌ２Ｏ３、ＳｉＯ２、ＷＯ３、Ｂｉ２Ｏ３、Ｔａ２Ｏ５、Ｌｉ２Ｏ、Ｃｓ２Ｏ、ＭｇＯ、ＣａＯ、ＳｒＯ、ＢａＯ、ＺｎＯ、ＺｒＯ２、Ｓｃ２Ｏ３、ＨｆＯ２、Ｌｕ２Ｏ３、ＧｅＯ２、Ｌａ２Ｏ３、Ｇｄ２Ｏ３、Ｙ２Ｏ３、およびＹｂ２Ｏ３で構成されていることが好ましく、上述のガラス成分の合計含有量は、９５％以上が好ましく、９８％以上より好ましく、９９％以上がさらに好ましく、９９．５％以上が一層好ましい。 The optical glass according to the third embodiment mainly contains the above-mentioned glass components, that is, P 2 O 5 , Nb 2 O 5 , B 2 O 3 , TiO 2 , Na 2 O, K 2 O as essential components, and optional components. Al 2 O 3 , SiO 2 , WO 3 , Bi 2 O 3 , Ta 2 O 5 , Li 2 O, Cs 2 O, MgO, CaO, SrO, BaO, ZnO, ZrO 2 , Sc 2 O 3 , HfO 2 , It is preferably composed of Lu 2 O 3 , GeO 2 , La 2 O 3 , Gd 2 O 3 , Y 2 O 3 , and Yb 2 O 3 , and the total content of the above-mentioned glass components is 95% or more. Is preferable, 98% or more is preferable, 99% or more is further preferable, and 99.5% or more is further preferable.
　第３実施形態に係る光学ガラスにおいて、ＴｅＯ２の含有量の上限は、好ましくは２％である。また、ＴｅＯ２の含有量の下限は、好ましくは０％である。 In the optical glass according to the third embodiment, the upper limit of the content of TeO 2 is preferably 2%. The lower limit of the content of TeO 2 is preferably 0%.
　ＴｅＯ２は毒性を有することから、ＴｅＯ２の含有量を低減させることが好ましい。そのため、ＴｅＯ２の含有量は上記範囲であることが好ましい。 Since TeO 2 is toxic, it is preferable to reduce the content of TeO 2. Therefore, the content of TeO 2 is preferably in the above range.
　第３実施形態に係る光学ガラスにおいて、フッ素Ｆの含有量は３％以下であることが好ましく、その上限は１％、０．５％、０．３％の順により好ましい。Ｆの含有量は少ない方が好ましく、その下限は好ましくは０％である。Ｆの含有量は０％でもよい。また、好ましくは、フッ素Ｆを実質的に含まない。 In the optical glass according to the third embodiment, the content of fluorine F is preferably 3% or less, and the upper limit thereof is more preferably 1%, 0.5%, and 0.3%. The content of F is preferably small, and the lower limit thereof is preferably 0%. The content of F may be 0%. Also, preferably, it does not substantially contain fluorine F.
　Ｆの含有量を上記範囲とすることで、ガラスを熔解中の揮発を抑えることができ、屈折率の変動、脈理を抑えることができる。 By setting the F content within the above range, volatilization during melting of the glass can be suppressed, and fluctuations in the refractive index and pulse can be suppressed.
　なお、第３実施形態に係る光学ガラスは、基本的に上記ガラス成分により構成されることが好ましいが、本発明の作用効果を妨げない範囲において、その他の成分を含有することも可能である。また、本発明において、不可避的不純物の含有を排除するものではない。 It is preferable that the optical glass according to the third embodiment is basically composed of the above glass components, but other components may be contained as long as the effects of the present invention are not impaired. Further, in the present invention, the inclusion of unavoidable impurities is not excluded.
＜その他の成分組成＞
　Ｐｂ、Ａｓ、Ｃｄ、Ｔｌ、Ｂｅ、Ｓｅは、いずれも毒性を有する。そのため、第３実施形態に係る光学ガラスがこれら元素をガラス成分として含有しないことが好ましい。 <Other component composition>
Pb, As, Cd, Tl, Be and Se are all toxic. Therefore, it is preferable that the optical glass according to the third embodiment does not contain these elements as a glass component.
　Ｕ、Ｔｈ、Ｒａはいずれも放射性元素である。そのため、第３実施形態に係る光学ガラスがこれら元素をガラス成分として含有しないことが好ましい。 U, Th, and Ra are all radioactive elements. Therefore, it is preferable that the optical glass according to the third embodiment does not contain these elements as a glass component.
　Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍは、ガラスの着色を増大させ、蛍光の発生源となり得る。そのため、第３実施形態に係る光学ガラスがこれら元素をガラス成分として含有しないことが好ましい。 V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm increase the coloring of glass and can be a source of fluorescence. Therefore, it is preferable that the optical glass according to the third embodiment does not contain these elements as a glass component.
　Ｓｂ（Ｓｂ２Ｏ３）、Ｃｅ（ＣｅＯ２）は清澄剤として機能する任意に添加可能な元素である。このうち、Ｓｂ（Ｓｂ２Ｏ３）は、清澄効果の大きな清澄剤である。しかし、Ｓｂ（Ｓｂ２Ｏ３）は酸化性が強く、Ｓｂ（Ｓｂ２Ｏ３）の添加量を多くしていくと、Ｓｂイオンによる光吸収により、ガラスの着色が増大し、好ましくない。また、ガラスを熔融するときに、熔融物中にＳｂがあると、ガラス熔融坩堝を構成する白金の熔融物への溶出が促進され、ガラス中の白金濃度が高くなる。ガラス中において、白金がイオンとして存在すると、光の吸収によりガラスの着色が増大する。また、ガラス中に白金が固形物として存在すると光の散乱源となり、ガラスの品質を低下させる。Ｃｅ（ＣｅＯ２）は、Ｓｂ（Ｓｂ２Ｏ３）と比較し、清澄効果が小さい。Ｃｅ（ＣｅＯ２）は、多量に添加するとガラスの着色が強まる。したがって、清澄剤を添加する場合は、添加量に注意しつつ、Ｓｂ（Ｓｂ２Ｏ３）を添加することが好ましい。 Sb (Sb 2 O 3 ) and Ce (CeO 2 ) are arbitrarily addable elements that function as fining agents. Of these, Sb (Sb 2 O 3 ) is a fining agent having a large fining effect. However, Sb (Sb 2 O 3 ) is highly oxidizing, and if the amount of Sb (Sb 2 O 3 ) added is increased, the coloration of the glass increases due to light absorption by Sb ions, which is not preferable. Further, when the glass is melted, if Sb is present in the melt, the elution of platinum constituting the glass melting crucible into the melt is promoted, and the platinum concentration in the glass becomes high. When platinum is present as ions in the glass, the coloration of the glass increases due to the absorption of light. Further, when platinum exists as a solid substance in the glass, it becomes a light scattering source and deteriorates the quality of the glass. Ce (CeO 2 ) has a smaller clarification effect than Sb (Sb 2 O 3). When Ce (CeO 2 ) is added in a large amount, the coloring of the glass is strengthened. Therefore, when adding a fining agent, it is preferable to add Sb (Sb 2 O 3) while paying attention to the amount of addition.
　Ｓｂ２Ｏ３の含有量は、外割り表示とする。すなわち、Ｓｂ２Ｏ３およびＣｅＯ２以外の全ガラス成分の合計含有量を１００質量％としたときのＳｂ２Ｏ３の含有量は、好ましくは１質量％未満、より好ましくは０．１質量％未満である。さらに、は０．０５質量％未満、０．０３質量％未満、０．０２質量％未満、０．０１％未満の順に好ましい。Ｓｂ２Ｏ３の含有量は０質量％であってもよい。 The content of Sb 2 O 3 is indicated by external division. That is, when the total content of all glass components other than Sb 2 O 3 and CeO 2 is 100% by mass, the content of Sb 2 O 3 is preferably less than 1% by mass, more preferably 0.1% by mass. Is less than. Further, is preferably less than 0.05% by mass, less than 0.03% by mass, less than 0.02% by mass, and less than 0.01% in this order. The content of Sb 2 O 3 may be 0% by mass.
　ＣｅＯ２の含有量も、外割り表示とする。すなわち、ＣｅＯ２、Ｓｂ２Ｏ３以外の全ガラス成分の合計含有量を１００質量％としたときのＣｅＯ２の含有量は、好ましくは２質量％未満、より好ましくは１質量％未満、さらに好ましくは０．５質量％未満、一層好ましくは０．１質量％未満の範囲である。ＣｅＯ２の含有量は０質量％であってもよい。ＣｅＯ２の含有量を上記範囲とすることによりガラスの清澄性を改善できる。 The content of CeO 2 is also indicated by external division. That is, when the total content of all glass components other than CeO 2 and Sb 2 O 3 is 100% by mass, the content of CeO 2 is preferably less than 2% by mass, more preferably less than 1% by mass, and even more preferably. Is in the range of less than 0.5% by mass, more preferably less than 0.1% by mass. The content of CeO 2 may be 0% by mass. By setting the content of CeO 2 in the above range, the clarity of the glass can be improved.
（ガラス特性）
　次に、第３実施形態に係る光学ガラスの特性について説明する。 (Glass characteristics)
Next, the characteristics of the optical glass according to the third embodiment will be described.
＜屈折率ｎｄ＞
　第３実施形態に係る光学ガラスにおいて、屈折率ｎｄは、好ましくは１．６３～１．８０である。屈折率ｎｄの下限は１．６５、１．６７、１．６９、１．７１または１．７３でもよく、屈折率ｎｄの上限は１．７９、１．７８、または１．７７でもよい。 <Refractive index nd>
In the optical glass according to the third embodiment, the refractive index nd is preferably 1.63 to 1.80. The lower limit of the refractive index nd may be 1.65, 1.67, 1.69, 1.71 or 1.73, and the upper limit of the refractive index nd may be 1.79, 1.78, or 1.77.
　屈折率ｎｄは各ガラス成分の含有量を適宜調整することにより所望の値にすることができる。相対的に屈折率ｎｄを高める働きを有する成分（高屈折率化成分）は、Ｎｂ２Ｏ５、ＴｉＯ２、ＷＯ３、Ｂｉ２Ｏ３、Ｔａ２Ｏ５、ＺｒＯ２、Ｌａ２Ｏ３等である。一方、相対的に屈折率ｎｄを低くする働きを有する成分（低屈折率化成分）は、Ｐ２Ｏ５、ＳｉＯ2、Ｂ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２Ｏ等である。 The refractive index nd can be set to a desired value by appropriately adjusting the content of each glass component. The components having the function of relatively increasing the refractive index nd (high refractive index component) are Nb 2 O 5 , TiO 2 , WO 3 , Bi 2 O 3 , Ta 2 O 5 , ZrO 2 , La 2 O 3, etc. Is. On the other hand, the components having a function of relatively lowering the refractive index nd (lowering the refractive index component) are P 2 O 5 , SiO 2 , B 2 O 3 , Li 2 O, Na 2 O, K 2 O and the like. is there.
＜アッベ数νｄ＞
　第３実施形態に係る光学ガラスにおいて、アッベ数νｄは、好ましくは２０～３０である。アッベ数νｄの下限は２２、２２．５、２３、または２３．２でもよく、アッベ数νｄの上限は２８、２６、または２５でもよい。 <Abbe number νd>
In the optical glass according to the third embodiment, the Abbe number νd is preferably 20 to 30. The lower limit of the Abbe number νd may be 22, 22.5, 23, or 23.2, and the upper limit of the Abbe number νd may be 28, 26, or 25.
　アッベ数νｄは、各ガラス成分の含有量を適宜調整することにより所望の値にすることができる。相対的にアッベ数νｄを低くする成分、すなわち高分散化成分は、Ｎｂ２Ｏ５、ＴｉＯ２、ＷＯ３、Ｂｉ２Ｏ３、Ｔａ２Ｏ５、ＺｒＯ２等である。一方、相対的にアッベ数νｄを高くする成分、すなわち低分散化成分は、Ｐ２Ｏ５、ＳｉＯ2、Ｂ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２Ｏ、Ｌａ２Ｏ３、ＢａＯ、ＣａＯ、ＳｒＯ等である。 The Abbe number νd can be set to a desired value by appropriately adjusting the content of each glass component. The components that relatively lower the Abbe number νd, that is, the highly dispersed components, are Nb 2 O 5 , TiO 2 , WO 3 , Bi 2 O 3 , Ta 2 O 5 , ZrO 2, and the like. On the other hand, the components that relatively increase the Abbe number νd, that is, the low dispersion components, are P 2 O 5 , SiO 2 , B 2 O 3 , Li 2 O, Na 2 O, K 2 O, La 2 O 3 , BaO, CaO, SrO and the like.
＜平均線熱膨張係数α＞
　第３実施形態に係る光学ガラスにおいて、１００～３００℃における平均線熱膨張係数αの下限は、好ましくは１００×１０－７℃－１であり、さらには１０２×１０－７℃－１、１０４×１０－７℃－１、１０６×１０－７℃－１、１０８×１０－７℃－１の順により好ましい。また、平均線熱膨張係数αの上限は、より好ましくは２００×１０－７℃－１であり、さらには１９０×１０－７℃－１、１８０×１０－７℃－１、１７０×１０－７℃－１、１６０×１０－７℃－１、１５０×１０－７℃－１、１４５×１０－７℃－１の順により好ましい。 <Average coefficient of linear thermal expansion α>
In the optical glass according to the third embodiment, the lower limit of the average coefficient of linear thermal expansion α at 100 to 300 ° C. is preferably 100 × 10 -7 ° C -1 , and further 102 × 10 -7 ° C -1 , 104. It is more preferable in the order of × 10 -7 ° C -1 , 106 × 10 -7 ° C -1 , and 108 × 10 -7 ° C -1. The upper limit of the average coefficient of linear thermal expansion α is more preferably 200 × 10 -7 ℃ -1 , and further 190 × 10 -7 ℃ -1 , 180 × 10 -7 ℃ -1 , 170 × 10 −. 7 ° C -1 , 160 × 10 -7 ° C -1 , 150 × 10 -7 ° C -1 , 145 × 10 -7 ° C -1 are more preferable.
　１００～３００℃の平均線膨張係数αを上記範囲とすることで、ガラスの熱膨張に伴う屈折率の変化、すなわち、相対屈折率の温度係数ｄｎ／ｄＴの増大を抑制することができる。 By setting the average linear expansion coefficient α of 100 to 300 ° C. in the above range, it is possible to suppress a change in the refractive index due to thermal expansion of the glass, that is, an increase in the temperature coefficient dn / dT of the relative refractive index.
　平均線膨張係数αは、ＪＯＧＩＳ０８－２００３の規定に基づいて測定される。但し、試料は長さ２０ｍｍ±０．５ｍｍ、直径５ｍｍ±０．５ｍｍの丸棒とし、試料に９８ｍＮの荷重を印加した状態で、４℃毎分の一定速度で上昇するように加熱し、温度と試料の伸びを測定する。
　なお、本明細書では、平均線膨張係数αを［℃－１］の単位で表しているが、単位として［Ｋ－１］を用いた場合でも平均線膨張係数αの数値は同じである。 The average coefficient of linear expansion α is measured based on the provisions of JOBIS08-2003. However, the sample shall be a round bar with a length of 20 mm ± 0.5 mm and a diameter of 5 mm ± 0.5 mm, and with a load of 98 mN applied to the sample, it shall be heated so as to rise at a constant rate of 4 ° C. And measure the elongation of the sample.
In this specification, the average coefficient of linear expansion α is expressed in the unit of [° C -1 ], but the numerical value of the average coefficient of linear expansion α is the same even when [K -1] is used as the unit.
＜相対屈折率の温度係数ｄｎ／ｄＴ＞
　第３実施形態に係る光学ガラスにおいて、Ｈｅ－Ｎｅレーザの波長（６３３ｎｍ）における相対屈折率の温度係数ｄｎ／ｄＴは、２０～４０℃の範囲で、好ましくは－１．０×１０－６～－１３．０×１０－６℃－１であり、さらには－１．０×１０－６～－１０．０×１０－６℃－１、－１．３×１０－６～－９．０×１０－６℃－１、－１．３×１０－６～－８．０×１０－６℃－１、－１．５×１０－６～－７．０×１０－６℃－１、－１．６×１０－６～－６．５×１０－６℃－１の順により好ましい。 <Temperature coefficient of relative refractive index dn / dT>
In the optical glass according to the third embodiment, the temperature coefficient dn / dT of the relative refractive index at the wavelength (633 nm) of the He—Ne laser is in the range of 20 to 40 ° C., preferably −1.0 × 10-6 to. -13.0 a × 10 -6 ℃ -1, more -1.0 × 10 -6 ~ -10.0 × 10 -6 ℃ -1, -1.3 × 10 -6 ~ -9.0 × 10 -6 ℃ -1 , -1.3 × 10 -6 ~ -8.0 × 10 -6 ℃ -1 , -1.5 × 10 -6 ~ -7.0 × 10 -6 ℃ -1 , It is more preferable in the order of −1.6 × 10 -6 to −6.5 × 10 -6 ° C -1.
　ｄｎ／ｄＴを上記範囲とし、ｄｎ／ｄＴがプラスの光学素子と組み合わせることで、光学素子の温度が大きく変動するような環境下でも屈折率の変動が小さくなるため、より幅広い温度範囲において、所望の光学特性を高精度に発揮できる。 By setting dn / dT in the above range and combining it with an optical element having a positive dn / dT, the fluctuation of the refractive index becomes small even in an environment where the temperature of the optical element fluctuates greatly. The optical characteristics of the above can be exhibited with high accuracy.
　相対屈折率の温度係数ｄｎ／ｄＴは、ＪＯＧＩＳ１８－２００８の干渉法に基づいて測定される。
　なお、本明細書では、温度係数ｄｎ／ｄＴを［℃－１］の単位で表しているが、単位として［Ｋ－１］を用いた場合でも温度係数ｄｎ／ｄＴの数値は同じである。 The temperature coefficient dn / dT of the relative refractive index is measured based on the interferometry of JOBIS18-2008.
In this specification, the temperature coefficient dn / dT is expressed in the unit of [° C-1 ], but the numerical value of the temperature coefficient dn / dT is the same even when [K -1] is used as the unit.
＜ガラス転移温度Ｔｇ＞
　第３実施形態に係る光学ガラスのガラス転移温度Ｔｇは、好ましくは６００℃以下であり、さらには５９０℃以下、５８０℃以下、５７０℃以下、５６０℃以下の順により好ましい。 <Glass transition temperature Tg>
The glass transition temperature Tg of the optical glass according to the third embodiment is preferably 600 ° C. or lower, more preferably 590 ° C. or lower, 580 ° C. or lower, 570 ° C. or lower, and 560 ° C. or lower.
　ガラス転移温度Ｔｇの上限が上記範囲を満たすことにより、ガラスの成型温度およびアニール温度の上昇を抑制することができ、プレス成形用設備およびアニール設備への熱的ダメージを軽減できる。また、ガラス転移温度Ｔｇの下限が上記範囲を満たすことにより、所望のアッベ数、屈折率を維持しつつ、ガラスの熱的安定性を良好に維持しやすくなる。 When the upper limit of the glass transition temperature Tg satisfies the above range, it is possible to suppress an increase in the glass molding temperature and the annealing temperature, and it is possible to reduce thermal damage to the press molding equipment and the annealing equipment. Further, when the lower limit of the glass transition temperature Tg satisfies the above range, it becomes easy to maintain good thermal stability of the glass while maintaining a desired Abbe number and refractive index.
＜ガラスの比重＞
　第３実施形態に係る光学ガラスにおいて、比重は、好ましくは３．４０以下であり、さらには、３．３０以下、３．２０以下の順により好ましい。ガラスの比重を低減することができれば、レンズの重量を減少できる。その結果、レンズを搭載するカメラレンズのオートフォーカス駆動の消費電力を低減できる。 <Specific gravity of glass>
In the optical glass according to the third embodiment, the specific gravity is preferably 3.40 or less, and more preferably 3.30 or less and 3.20 or less. If the specific gravity of the glass can be reduced, the weight of the lens can be reduced. As a result, the power consumption of the autofocus drive of the camera lens on which the lens is mounted can be reduced.
＜ガラスの光線透過性＞
　第３実施形態に係る光学ガラスの光線透過性は、着色度λ５により評価できる。
　厚さ１０．０ｍｍ±０．１ｍｍのガラス試料について波長２００～７００ｎｍの範囲で分光透過率を測定し、外部透過率が５％となる波長をλ５とする。 <Light transmission of glass>
The light transmittance of the optical glass according to the third embodiment can be evaluated by the degree of coloring λ5.
The spectral transmittance of a glass sample having a thickness of 10.0 mm ± 0.1 mm is measured in the wavelength range of 200 to 700 nm, and the wavelength at which the external transmittance is 5% is defined as λ5.
　第３実施形態に係る光学ガラスのλ５は、好ましくは４００ｎｍ以下であり、より好ましくは３９０ｎｍ以下であり、さらに好ましくは３８５ｎｍ以下である。 The λ5 of the optical glass according to the third embodiment is preferably 400 nm or less, more preferably 390 nm or less, and further preferably 385 nm or less.
　λ５が短波長化された光学ガラスを用いることで、好適な色再現を可能とする光学素子を提供できる。 By using an optical glass in which λ5 has a shorter wavelength, it is possible to provide an optical element that enables suitable color reproduction.
　第３実施形態に係る光学ガラスの製造および光学素子等の製造については、第１実施形態と同様とすることができる。 The production of the optical glass and the production of the optical element and the like according to the third embodiment can be the same as those of the first embodiment.
　以下に本発明を実施例により説明するが、本発明は以下の実施例のみに限定されるものでは無い。なお、実施例１－１、１－２は第１実施形態に対応し、実施例２－１、２－２は第２実施形態に対応し、実施例３－１、３－２は第３実施形態に対応する。 The present invention will be described below by way of examples, but the present invention is not limited to the following examples. In addition, Examples 1-1 and 1-2 correspond to the first embodiment, Examples 2-1 and 2-2 correspond to the second embodiment, and Examples 3-1 and 3-2 correspond to the third embodiment. Corresponds to the embodiment.
（実施例１－１）
［ガラスサンプルの作製］
　表１－１～１－６に示す試料Ｎｏ．１～５２の組成を有するガラスとなるように、各成分に対応する化合物原料、すなわち、リン酸塩、炭酸塩、酸化物等の原料を秤量し、十分混合して調合原料とした。該調合原料を白金製坩堝に投入し、大気雰囲気下で９００～１３５０℃に加熱して熔融し、攪拌により均質化、清澄して熔融ガラスを得た。該熔融ガラスを成形型に鋳込んで成形し、徐冷して、ブロック形状のガラスサンプルを得た。
　なお、調合原料を石英ガラス製坩堝に投入し、熔融した後、白金製坩堝へ移してさらに加熱して熔融し、攪拌により均質化、清澄して得た熔融ガラスを成形型に鋳込んで成形、徐冷してもよい。 (Example 1-1)
[Preparation of glass sample]
The sample numbers shown in Tables 1-1 to 1-6. Compound raw materials corresponding to each component, that is, raw materials such as phosphates, carbonates, and oxides, were weighed and sufficiently mixed to prepare a compounding raw material so as to form a glass having a composition of 1 to 52. The compounding raw material was put into a platinum crucible, heated to 900 to 1350 ° C. in an atmospheric atmosphere to melt, homogenized and clarified by stirring to obtain molten glass. The molten glass was cast into a molding die, molded, and slowly cooled to obtain a block-shaped glass sample.
The compounding raw material is put into a quartz glass crucible, melted, then transferred to a platinum crucible, further heated to melt, homogenized by stirring, and clarified, and the obtained molten glass is cast into a molding die and molded. , May be slowly cooled.
［ガラスサンプルの評価］
　得られたガラスサンプルについて、以下に示す方法にて、ガラス組成、比重、屈折率ｎｄ、アッベ数νｄ、λ５、ガラス転移温度Ｔｇ、相対屈折率の温度係数ｄｎ／ｄＴ、平均線膨張係数αを測定した。結果を、表１－１、１－２、１－４に示す。 [Evaluation of glass sample]
For the obtained glass sample, the glass composition, specific gravity, refractive index nd, Abbe number νd, λ5, glass transition temperature Tg, temperature coefficient of relative refractive index dn / dT, and average linear expansion coefficient α are determined by the methods shown below. It was measured. The results are shown in Tables 1-1, 1-2, and 1-4.
〔１〕ガラス組成
　得られたガラスサンプルについて、誘導結合プラズマ発光分光分析法（ＩＣＰ－ＡＥＳ）で各ガラス成分の含有量を測定した。 [1] Glass Composition The content of each glass component of the obtained glass sample was measured by inductively coupled plasma emission spectroscopy (ICP-AES).
〔２〕比重
　日本光学硝子工業会規格ＪＯＧＩＳ－０５に基づいて測定した。 [2] Specific gravity The measurement was performed based on the Japan Optical Glass Industry Association standard JOBIS-05.
〔３〕屈折率ｎｄおよびアッベ数νｄ
　日本光学硝子工業会規格ＪＯＧＩＳ－０１に基づいて測定した。 [3] Refractive index nd and Abbe number νd
The measurement was performed based on the Japan Optical Glass Industry Association standard JOGIS-01.
〔４〕λ５
　ガラスサンプルを、厚さ１０ｍｍで、互いに平行かつ光学研磨された平面を有するように加工し、波長２８０ｎｍから７００ｎｍまでの波長域における分光透過率を測定した。光学研磨された一方の平面に垂直に入射する光線の強度を強度Ａとし、他方の平面から出射する光線の強度を強度Ｂとして、分光透過率Ｂ／Ａを算出した。分光透過率が５％になる波長をλ５とした。なお、分光透過率には試料表面における光線の反射損失も含まれる。 [4] λ5
The glass sample was processed so as to have a plane having a thickness of 10 mm, parallel to each other and optically polished, and the spectral transmittance in the wavelength range from 280 nm to 700 nm was measured. The spectral transmittance B / A was calculated with the intensity of the light beam perpendicularly incident on one plane optically polished as the intensity A and the intensity of the light beam emitted from the other plane as the intensity B. The wavelength at which the spectral transmittance is 5% was defined as λ5. The spectral transmittance also includes the reflection loss of light rays on the sample surface.
〔５〕ガラス転移温度Ｔｇ
　ガラス転移温度Ｔｇは、ＮＥＴＺＳＣＨ　ＪＡＰＡＮ社製の示差走査熱量分析装置（ＤＳＣ３３００ＳＡ）を使用し、昇温速度１０℃／分にて測定した。 [5] Glass transition temperature Tg
The glass transition temperature Tg was measured at a heating rate of 10 ° C./min using a differential scanning calorimetry device (DSC3300SA) manufactured by NETZSCH JAPAN.
〔６〕相対屈折率の温度係数ｄｎ／ｄＴの測定
　得られたガラスサンプルについて、ＪＯＧＩＳ１８―２００８の干渉法に基づき測定した。光源は波長６３３ｎｍのＨｅ－Ｎｅレーザを用い、温度－７０～１５０℃の範囲で連続測定した。測定結果のうち、２０℃～４０℃の範囲のｄｎ／ｄＴ値を表１－１、１－２、１－４に示す。 [6] Measurement of Temperature Coefficient of Relative Refractive Index dn / dT The obtained glass sample was measured based on the interferometry of JOBIS18-2008. A He-Ne laser having a wavelength of 633 nm was used as a light source, and continuous measurement was performed in a temperature range of −70 to 150 ° C. Among the measurement results, the dn / dT values in the range of 20 ° C. to 40 ° C. are shown in Tables 1-1, 1-2, and 1-4.
〔７〕平均線膨張係数αの測定
　１００～３００℃の平均線膨張係数αは、ＪＯＧＩＳ０８－２００３の規定に基づいて測定した。但し、試料は長さ２０ｍｍ±０．５ｍｍ、直径５ｍｍ±０．５ｍｍの丸棒とし、試料に９８ｍＮの荷重を印加した状態で、４℃毎分の一定速度で上昇するように加熱し、温度と試料の伸びを測定した。 [7] Measurement of average linear expansion coefficient α The average linear expansion coefficient α at 100 to 300 ° C. was measured based on the provisions of JOBIS08-2003. However, the sample is a round bar with a length of 20 mm ± 0.5 mm and a diameter of 5 mm ± 0.5 mm, and with a load of 98 mN applied to the sample, it is heated so as to rise at a constant rate of 4 ° C. every minute, and the temperature is increased. And the elongation of the sample was measured.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
（実施例１－２）
　実施例１で得られたガラスサンプルを、切断、研削してカットピースを作製した。カットピースをリヒートプレスによりプレス成形して、光学素子ブランクを作製した。光学素子ブランクを精密アニールし、所要の屈折率になるよう屈折率を精密に調整した後、公知の方法で研削、研磨することで、両凸レンズ、両凹レンズ、平凸レンズ、平凹レンズ、凹メニスカスレンズ、凸メニスカスレンズ等の各種レンズが得られた。 (Example 1-2)
The glass sample obtained in Example 1 was cut and ground to prepare a cut piece. The cut piece was press-molded by a reheat press to prepare an optical element blank. The optical element blank is precisely annealed, the refractive index is precisely adjusted to the required refractive index, and then ground and polished by a known method to obtain a biconvex lens, a biconcave lens, a plano-convex lens, a plano-concave lens, and a concave meniscus lens. , Various lenses such as convex meniscus lenses were obtained.
（実施例２－１）
［ガラスサンプルの作製］
　表２－１に示す試料Ｎｏ．２－１～２－８の組成を有するガラスとなるように、各成分に対応する化合物原料、すなわち、リン酸塩、炭酸塩、酸化物等の原料を秤量し、十分混合して調合原料とした。該調合原料を白金製坩堝に投入し、大気雰囲気下で９００～１３５０℃に加熱して熔融し、攪拌により均質化、清澄して熔融ガラスを得た。該熔融ガラスを成形型に鋳込んで成形し、徐冷して、ブロック形状のガラスサンプルを得た。
　なお、調合原料を石英ガラス製坩堝に投入し、熔融した後、白金製坩堝へ移してさらに加熱して熔融し、攪拌により均質化、清澄して得た熔融ガラスを成形型に鋳込んで成形、徐冷してもよい。 (Example 2-1)
[Preparation of glass sample]
Sample No. shown in Table 2-1. Compound raw materials corresponding to each component, that is, raw materials such as phosphates, carbonates, and oxides, are weighed and sufficiently mixed with the compounding raw materials so as to form a glass having a composition of 2-1 to 2-8. did. The compounding raw material was put into a platinum crucible, heated to 900 to 1350 ° C. in an atmospheric atmosphere to melt, homogenized and clarified by stirring to obtain molten glass. The molten glass was cast into a molding die, molded, and slowly cooled to obtain a block-shaped glass sample.
The compounding raw material is put into a quartz glass crucible, melted, then transferred to a platinum crucible, further heated to melt, homogenized by stirring, and clarified, and the obtained molten glass is cast into a molding die and molded. , May be slowly cooled.
［ガラスサンプルの評価］
　得られたガラスサンプルについて、以下に示す方法にて、ガラス組成、屈折率ｎｄ、アッベ数νｄ、λ５、ガラス転移温度Ｔｇ、平均線膨張係数α、相対屈折率の温度係数ｄｎ／ｄＴ、比重を測定した。結果を、表２－３に示す。 [Evaluation of glass sample]
For the obtained glass sample, the glass composition, refractive index nd, Abbe number νd, λ5, glass transition temperature Tg, average linear expansion coefficient α, relative refractive index temperature coefficient dn / dT, and specific gravity are determined by the methods shown below. It was measured. The results are shown in Table 2-3.
〔１〕ガラス組成
　得られたガラスサンプルについて、誘導結合プラズマ発光分光分析法（ＩＣＰ－ＡＥＳ）で各ガラス成分の含有量を測定した。なお、表２－３に示すＮｏ．２－１～２－８の全てのガラスサンプルにおいて、Ｆの含有量は０％であった。 [1] Glass Composition The content of each glass component of the obtained glass sample was measured by inductively coupled plasma emission spectroscopy (ICP-AES). No. shown in Table 2-3. The F content was 0% in all the glass samples 2-1 to 2-8.
〔２〕比重
　日本光学硝子工業会規格ＪＯＧＩＳ－０５に基づいて測定した。 [2] Specific gravity The measurement was performed based on the Japan Optical Glass Industry Association standard JOBIS-05.
〔３〕屈折率ｎｄおよびアッベ数νｄ
　日本光学硝子工業会規格ＪＯＧＩＳ－０１に基づいて測定した。 [3] Refractive index nd and Abbe number νd
The measurement was performed based on the Japan Optical Glass Industry Association standard JOGIS-01.
〔４〕λ５
　ガラスサンプルを、厚さ１０ｍｍで、互いに平行かつ光学研磨された平面を有するように加工し、波長２８０ｎｍから７００ｎｍまでの波長域における分光透過率を測定した。光学研磨された一方の平面に垂直に入射する光線の強度を強度Ａとし、他方の平面から出射する光線の強度を強度Ｂとして、分光透過率Ｂ／Ａを算出した。分光透過率が５％になる波長をλ５とした。なお、分光透過率には試料表面における光線の反射損失も含まれる。 [4] λ5
The glass sample was processed so as to have a plane having a thickness of 10 mm, parallel to each other and optically polished, and the spectral transmittance in the wavelength range from 280 nm to 700 nm was measured. The spectral transmittance B / A was calculated with the intensity of the light beam perpendicularly incident on one plane optically polished as the intensity A and the intensity of the light beam emitted from the other plane as the intensity B. The wavelength at which the spectral transmittance is 5% was defined as λ5. The spectral transmittance also includes the reflection loss of light rays on the sample surface.
〔５〕ガラス転移温度Ｔｇ
　ガラス転移温度Ｔｇは、ＮＥＴＺＳＣＨ　ＪＡＰＡＮ社製の示差走査熱量分析装置（ＤＳＣ３３００ＳＡ）を使用し、昇温速度１０℃／分にて測定した。 [5] Glass transition temperature Tg
The glass transition temperature Tg was measured at a heating rate of 10 ° C./min using a differential scanning calorimetry device (DSC3300SA) manufactured by NETZSCH JAPAN.
〔６〕相対屈折率の温度係数ｄｎ／ｄＴの測定
　得られたガラスサンプルについて、ＪＯＧＩＳ１８―２００８の干渉法に基づき測定した。光源は波長６３３ｎｍのＨｅ－Ｎｅレーザを用い、温度－７０～１５０℃の範囲で連続測定した。測定結果のうち、２０℃～４０℃の範囲のｄｎ／ｄＴ値を表２－３に示す。 [6] Measurement of Temperature Coefficient of Relative Refractive Index dn / dT The obtained glass sample was measured based on the interferometry of JOBIS18-2008. A He-Ne laser having a wavelength of 633 nm was used as a light source, and continuous measurement was performed in a temperature range of −70 to 150 ° C. Of the measurement results, the dn / dT values in the range of 20 ° C to 40 ° C are shown in Table 2-3.
〔７〕平均線膨張係数αの測定
　１００～３００℃の平均線膨張係数αは、ＪＯＧＩＳ０８－２００３の規定に基づいて測定した。但し、試料は長さ２０ｍｍ±０．５ｍｍ、直径５ｍｍ±０．５ｍｍの丸棒とし、試料に９８ｍＮの荷重を印加した状態で、４℃毎分の一定速度で上昇するように加熱し、温度と試料の伸びを測定した。 [7] Measurement of average linear expansion coefficient α The average linear expansion coefficient α at 100 to 300 ° C. was measured based on the provisions of JOBIS08-2003. However, the sample is a round bar with a length of 20 mm ± 0.5 mm and a diameter of 5 mm ± 0.5 mm, and with a load of 98 mN applied to the sample, it is heated so as to rise at a constant rate of 4 ° C. every minute, and the temperature is increased. And the elongation of the sample was measured.
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
（実施例２－２）
　実施例２－１で得られたガラスサンプルを、切断、研削してカットピースを作製した。カットピースをリヒートプレスによりプレス成形して、光学素子ブランクを作製した。光学素子ブランクを精密アニールし、所要の屈折率になるよう屈折率を精密に調整した後、公知の方法で研削、研磨することで、両凸レンズ、両凹レンズ、平凸レンズ、平凹レンズ、凹メニスカスレンズ、凸メニスカスレンズ等の各種レンズが得られた。 (Example 2-2)
The glass sample obtained in Example 2-1 was cut and ground to prepare a cut piece. The cut piece was press-molded by a reheat press to prepare an optical element blank. The optical element blank is precisely annealed, the refractive index is precisely adjusted to the required refractive index, and then ground and polished by a known method to obtain a biconvex lens, a biconcave lens, a plano-convex lens, a plano-concave lens, and a concave meniscus lens. , Various lenses such as convex meniscus lenses were obtained.
（実施例３－１）
［ガラスサンプルの作製］
　表３－１に示す試料Ｎｏ．３－１～３－８の組成を有するガラスとなるように、各成分に対応する化合物原料、すなわち、リン酸塩、炭酸塩、酸化物等の原料を秤量し、十分混合して調合原料とした。該調合原料を白金製坩堝に投入し、大気雰囲気下で９００～１３５０℃に加熱して熔融し、攪拌により均質化、清澄して熔融ガラスを得た。該熔融ガラスを成形型に鋳込んで成形し、徐冷して、ブロック形状のガラスサンプルを得た。
　なお、調合原料を石英ガラス製坩堝に投入し、熔融した後、白金製坩堝へ移してさらに加熱して熔融し、攪拌により均質化、清澄して得た熔融ガラスを成形型に鋳込んで成形、徐冷してもよい。 (Example 3-1)
[Preparation of glass sample]
Sample No. shown in Table 3-1. Compound raw materials corresponding to each component, that is, raw materials such as phosphates, carbonates, and oxides, are weighed and sufficiently mixed to prepare a mixed raw material so as to form a glass having a composition of 3-1 to 3-8. did. The compounding raw material was put into a platinum crucible, heated to 900 to 1350 ° C. in an atmospheric atmosphere to melt, homogenized and clarified by stirring to obtain molten glass. The molten glass was cast into a molding die, molded, and slowly cooled to obtain a block-shaped glass sample.
The compounding raw material is put into a quartz glass crucible, melted, then transferred to a platinum crucible, further heated to melt, homogenized by stirring, and clarified, and the obtained molten glass is cast into a molding die and molded. , May be slowly cooled.
［ガラスサンプルの評価］
　得られたガラスサンプルについて、以下に示す方法にて、ガラス組成、屈折率ｎｄ、アッベ数νｄ、λ５、ガラス転移温度Ｔｇ、平均線膨張係数α、相対屈折率の温度係数ｄｎ／ｄＴ、比重を測定した。結果を表３－１に示す。 [Evaluation of glass sample]
For the obtained glass sample, the glass composition, refractive index nd, Abbe number νd, λ5, glass transition temperature Tg, average linear expansion coefficient α, relative refractive index temperature coefficient dn / dT, and specific gravity are determined by the methods shown below. It was measured. The results are shown in Table 3-1.
〔１〕ガラス組成
　得られたガラスサンプルについて、誘導結合プラズマ発光分光分析法（ＩＣＰ－ＡＥＳ）で各ガラス成分の含有量を測定した。なお、表３－１に示すＮｏ．３－１～３－８の全てのガラスサンプルにおいて、Ｆの含有量は０％であった。 [1] Glass Composition The content of each glass component of the obtained glass sample was measured by inductively coupled plasma emission spectroscopy (ICP-AES). No. 1 shown in Table 3-1. The F content was 0% in all the glass samples 3-1 to 3-8.
〔２〕比重
　日本光学硝子工業会規格ＪＯＧＩＳ－０５に基づいて測定した。 [2] Specific gravity The measurement was performed based on the Japan Optical Glass Industry Association standard JOBIS-05.
〔３〕屈折率ｎｄおよびアッベ数νｄ
　日本光学硝子工業会規格ＪＯＧＩＳ－０１に基づいて測定した。 [3] Refractive index nd and Abbe number νd
The measurement was performed based on the Japan Optical Glass Industry Association standard JOGIS-01.
〔４〕λ５
　ガラスサンプルを、厚さ１０ｍｍで、互いに平行かつ光学研磨された平面を有するように加工し、波長２８０ｎｍから７００ｎｍまでの波長域における分光透過率を測定した。光学研磨された一方の平面に垂直に入射する光線の強度を強度Ａとし、他方の平面から出射する光線の強度を強度Ｂとして、分光透過率Ｂ／Ａを算出した。分光透過率が５％になる波長をλ５とした。なお、分光透過率には試料表面における光線の反射損失も含まれる。 [4] λ5
The glass sample was processed so as to have a plane having a thickness of 10 mm, parallel to each other and optically polished, and the spectral transmittance in the wavelength range from 280 nm to 700 nm was measured. The spectral transmittance B / A was calculated with the intensity of the light beam perpendicularly incident on one plane optically polished as the intensity A and the intensity of the light beam emitted from the other plane as the intensity B. The wavelength at which the spectral transmittance is 5% was defined as λ5. The spectral transmittance also includes the reflection loss of light rays on the sample surface.
〔５〕ガラス転移温度Ｔｇ
　ガラス転移温度Ｔｇは、熱機械分析装置（ＴＭＡ）（マック・サイエンス製、ＴＭＡ-４０００Ｓ）を使用し、昇温速度４℃／分にて測定した。 [5] Glass transition temperature Tg
The glass transition temperature Tg was measured at a heating rate of 4 ° C./min using a thermomechanical analyzer (TMA) (TMA-4000S, manufactured by Mac Science).
〔６〕相対屈折率の温度係数ｄｎ／ｄＴの測定
　得られたガラスサンプルについて、ＪＯＧＩＳ１８―２００８の干渉法に基づき測定した。光源は波長６３３ｎｍのＨｅ－Ｎｅレーザを用い、温度－７０～１５０℃の範囲で連続測定した。測定結果のうち、２０℃～４０℃の範囲のｄｎ／ｄＴ値を表３－１に示す。 [6] Measurement of Temperature Coefficient of Relative Refractive Index dn / dT The obtained glass sample was measured based on the interferometry of JOBIS18-2008. A He-Ne laser having a wavelength of 633 nm was used as a light source, and continuous measurement was performed in a temperature range of −70 to 150 ° C. Of the measurement results, the dn / dT values in the range of 20 ° C to 40 ° C are shown in Table 3-1.
〔７〕平均線膨張係数αの測定
　１００～３００℃の平均線膨張係数αは、ＪＯＧＩＳ０８－２００３の規定に基づいて測定した。但し、試料は長さ２０ｍｍ±０．５ｍｍ、直径５ｍｍ±０．５ｍｍの丸棒とし、試料に９８ｍＮの荷重を印加した状態で、４℃毎分の一定速度で上昇するように加熱し、温度と試料の伸びを測定した。 [7] Measurement of average linear expansion coefficient α The average linear expansion coefficient α at 100 to 300 ° C. was measured based on the provisions of JOBIS08-2003. However, the sample shall be a round bar with a length of 20 mm ± 0.5 mm and a diameter of 5 mm ± 0.5 mm, and with a load of 98 mN applied to the sample, it shall be heated so as to rise at a constant rate of 4 ° C. And the elongation of the sample was measured.
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000010
（実施例３－２）
　実施例３－１で得られたガラスサンプルを、切断、研削してカットピースを作製した。カットピースをリヒートプレスによりプレス成形して、光学素子ブランクを作製した。光学素子ブランクを精密アニールし、所要の屈折率になるよう屈折率を精密に調整した後、公知の方法で研削、研磨することで、両凸レンズ、両凹レンズ、平凸レンズ、平凹レンズ、凹メニスカスレンズ、凸メニスカスレンズ等の各種レンズが得られた。 (Example 3-2)
The glass sample obtained in Example 3-1 was cut and ground to prepare a cut piece. The cut piece was press-molded by a reheat press to prepare an optical element blank. The optical element blank is precisely annealed, the refractive index is precisely adjusted to the required refractive index, and then ground and polished by a known method to obtain a biconvex lens, a biconcave lens, a plano-convex lens, a plano-concave lens, and a concave meniscus lens. , Various lenses such as convex meniscus lenses were obtained.
　今回開示された実施の形態はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.
　例えば、上記に例示されたガラス組成に対し、明細書に記載の組成調整を行うことにより、本発明の一態様にかかる光学ガラスを作製できる。
　また、明細書に例示または好ましい範囲として記載した事項の２つ以上を任意に組み合わせることは、もちろん可能である。 For example, the optical glass according to one aspect of the present invention can be produced by adjusting the composition described in the specification with respect to the glass composition exemplified above.
In addition, it is of course possible to arbitrarily combine two or more of the items described in the specification as an example or a preferable range.

Claims (9)

  1. 　屈折率ｎｄが１．６３～１．８０であり、
    　アッベ数νｄが２２～３４であり、
    　Ｎｂ２Ｏ５の含有量が２５～５５質量％であり、
    　ＷＯ３の含有量が３０質量％未満であり、
    　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］が３６～６０質量％であり、
    　Ｐ２Ｏ５、Ｂ２Ｏ３、ＳｉＯ２、Ａｌ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量の質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３＋Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が１．１０以下であり、
    　Ｐ２Ｏ５およびＢ２Ｏ３の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（Ｐ２Ｏ５＋Ｂ２Ｏ３）］が０．５０以下であり、
    　下記（Ａ）または（Ｂ）を満たす光学ガラス。
    （Ａ）　Ｐ２Ｏ５の含有量が２０～３６質量％であり、
    　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が１．５０以下であり、
    　Ｐ２Ｏ５の含有量に対するＢ２Ｏ３の含有量の質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］が０．０５～０．３９であり、
    　ＭｇＯ、ＣａＯ、ＳｒＯおよびＢａＯの合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］が８．０質量％以下である。
    （Ｂ）　Ｐ２Ｏ５の含有量が２５～３８質量％であり、
    Ａｌ２Ｏ３の含有量が５質量％未満であり、
    　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が１．８０以下であり、
    　ＭｇＯ、ＣａＯ、ＳｒＯおよびＢａＯの合計含有量［ＭｇＯ＋ＣａＯ＋ＳｒＯ＋ＢａＯ］が７．０質量％以下であり、
    　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量に対するＴｉＯ２の含有量の質量比［ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）］が０．２５以上である。     The refractive index nd is 1.63 to 1.80, and the refractive index nd is 1.63 to 1.80.
    The Abbe number νd is 22 to 34,
    The content of Nb 2 O 5 is 25 to 55% by mass,
    The content of WO 3 is less than 30% by mass,
    The total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 36 to 60% by mass. ,
    TIO 2 , Nb 2 O 5 , WO 3 , Bi with respect to the total content of P 2 O 5 , B 2 O 3 , SiO 2 , Al 2 O 3 , Li 2 O, Na 2 O, K 2 O and Cs 2 O. Mass ratio of total contents of 2 O 3 and Ta 2 O 5 [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3) + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.10 or less,
    The mass ratio of the content of TiO 2 to the total content of P 2 O 5 and B 2 O 3 [TiO 2 / (P 2 O 5 + B 2 O 3 )] is 0.50 or less.
    An optical glass that satisfies the following (A) or (B).
    (A) The content of P 2 O 5 is 20 to 36% by mass, and the content is 20 to 36% by mass.
    Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.50 or less.
    P 2 O 5 mass ratio of the content of B 2 O 3 to the content of [B 2 O 3 / P 2 O 5] is 0.05 to 0.39
    The total content [MgO + CaO + SrO + BaO] of MgO, CaO, SrO and BaO is 8.0% by mass or less.
    (B) The content of P 2 O 5 is 25 to 38% by mass, and the content is 25 to 38% by mass.
    The content of Al 2 O 3 is less than 5% by mass,
    Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
    The total content of MgO, CaO, SrO and BaO [MgO + CaO + SrO + BaO] is 7.0% by mass or less.
    The mass ratio of the content of TiO 2 to the total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more.
  2. 　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比［（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が１．００以上である、請求項１に記載の光学ガラス。 Mass ratio of the total content of P 2 O 5 , B 2 O 3 and SiO 2 to the total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.00 or more, the optical glass according to claim 1.
  3. 　Ｐ２Ｏ５、Ｂ２Ｏ３、ＳｉＯ２、Ａｌ２Ｏ３、Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量の質量比［（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）／（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２＋Ａｌ２Ｏ３＋Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）］が０．５０以上である、請求項１または２に記載の光学ガラス。 TIO 2 , Nb 2 O 5 , WO 3 , Bi with respect to the total content of P 2 O 5 , B 2 O 3 , SiO 2 , Al 2 O 3 , Li 2 O, Na 2 O, K 2 O and Cs 2 O. Mass ratio of total contents of 2 O 3 and Ta 2 O 5 [(TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ) / (P 2 O 5 + B 2 O 3 + SiO 2 + Al 2 O 3 + Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 0.50 or more, according to claim 1 or 2.
  4. 　Ｐ２Ｏ５の含有量が２５～５０質量％であり、
    　ＴｉＯ２の含有量が１０～５０質量％であり、
    　Ｎｂ２Ｏ５含有量が５～３０質量％であり、
    　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］が３５～６０質量％であり、
    　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量に対するＴｉＯ２の含有量の質量比[ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）]が０．２５以上であり、
    　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量に対するＰ２Ｏ５、Ｂ２Ｏ３およびＳｉＯ２の合計含有量の質量比[（Ｐ２Ｏ５＋Ｂ２Ｏ３＋ＳｉＯ２）／（Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ）]が１．８０以下であり、
    　下記（Ａ）または（Ｂ）を満たす光学ガラス。
    （Ａ）　ＷＯ３の含有量が７質量％以下である。
    （Ｂ）　実質的にＦを含まない。     The content of P 2 O 5 is 25 to 50% by mass,
    The content of TiO 2 is 10 to 50% by mass,
    The Nb 2 O 5 content is 5 to 30% by mass,
    The total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 35 to 60% by mass. ,
    Mass ratio of TiO 2 content to total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more,
    Mass ratio of total contents of P 2 O 5 , B 2 O 3 and SiO 2 to total contents of Li 2 O, Na 2 O, K 2 O and Cs 2 O [(P 2 O 5 + B 2 O 3 + SiO 2 ) / (Li 2 O + Na 2 O + K 2 O + Cs 2 O)] is 1.80 or less.
    An optical glass that satisfies the following (A) or (B).
    (A) The content of WO 3 is 7% by mass or less.
    (B) Substantially contains no F.
  5. 　Ｐ２Ｏ５の含有量が２５～５０質量％であり、
    　Ｎｂ２Ｏ５含有量が１４～４０質量％であり、
    　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量［ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５］が３５～６０質量％であり、
    　ＴｉＯ２、Ｎｂ２Ｏ５、ＷＯ３、Ｂｉ２Ｏ３およびＴａ２Ｏ５の合計含有量に対するＴｉＯ２の含有量の質量比[ＴｉＯ２／（ＴｉＯ２＋Ｎｂ２Ｏ５＋ＷＯ３＋Ｂｉ２Ｏ３＋Ｔａ２Ｏ５）]が０．２５以上であり、
    　Ｐ２Ｏ５の含有量に対するＢ２Ｏ３の含有量の質量比［Ｂ２Ｏ３／Ｐ２Ｏ５］が０．０５～０．３９であり、
    　Ｌｉ２Ｏ、Ｎａ２Ｏ、Ｋ２ＯおよびＣｓ２Ｏの合計含有量［Ｌｉ２Ｏ＋Ｎａ２Ｏ＋Ｋ２Ｏ＋Ｃｓ２Ｏ］が１０質量％以上であり、
    　Ｋ２Ｏの含有量に対するＮａ２Ｏの含有量の質量比［Ｎａ２Ｏ／Ｋ２Ｏ］が１．５０以上である、光学ガラス。     The content of P 2 O 5 is 25 to 50% by mass,
    The Nb 2 O 5 content is 14-40% by mass.
    The total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3 + Ta 2 O 5 ] is 35 to 60% by mass. ,
    Mass ratio of TiO 2 content to total content of TiO 2 , Nb 2 O 5 , WO 3 , Bi 2 O 3 and Ta 2 O 5 [TiO 2 / (TIO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3) + Ta 2 O 5 )] is 0.25 or more,
    P 2 O 5 mass ratio of the content of B 2 O 3 to the content of [B 2 O 3 / P 2 O 5] is 0.05 to 0.39
    The total content of Li 2 O, Na 2 O, K 2 O and Cs 2 O [Li 2 O + Na 2 O + K 2 O + Cs 2 O] is 10% by mass or more.
    K 2 O weight ratio of Na 2 O content to the content of [Na 2 O / K 2 O ] is 1.50 or more, an optical glass.
  6. 　実質的にＦを含まない、請求項５に記載の光学ガラス。 The optical glass according to claim 5, which does not substantially contain F.
  7. 　１００～３００℃の平均線熱膨張係数αが１００×１０－７～２００×１０－７℃－１である、請求項１、２、４～６のいずれかに記載の光学ガラス。 The optical glass according to any one of claims 1, 2, 4 to 6, wherein the average linear thermal expansion coefficient α of 100 to 300 ° C. is 100 × 10 -7 to 200 × 10 -7 ° C. -1.
  8. 　Ｈｅ－Ｎｅレーザの波長（６３３ｎｍ）における相対屈折率の温度係数ｄｎ／ｄＴが２０～４０℃の範囲で－０．１×１０－６～－１３．０×１０－６℃－１である、請求項１、２、４～６のいずれかに記載の光学ガラス。 The temperature coefficient dn / dT of the relative refractive index at the wavelength (633 nm) of the He-Ne laser is −0.1 × 10 -6 to -13.0 × 10 -6 ° C -1 in the range of 20 to 40 ° C. The optical glass according to any one of claims 1, 2, 4 to 6.
  9. 　請求項１～８のいずれかに記載の光学ガラスからなる光学素子。 An optical element made of optical glass according to any one of claims 1 to 8.
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EP3943458A4 (en) * 2019-03-18 2022-12-07 Hikari Glass Co., Ltd. Optical glass, optical element, optical system, interchangeable lens, and optical device

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JPH08157231A (en) * 1994-12-02 1996-06-18 Hoya Corp Low melting point optical glass
JP2002293572A (en) * 2001-01-29 2002-10-09 Hoya Corp Optical glass
JP2011230991A (en) * 2010-04-30 2011-11-17 Ohara Inc Optical glass, preform, and optical element
JP2014185075A (en) * 2013-02-19 2014-10-02 Hoya Corp Optical glass, optical glass blank, glass raw material for press molding, optical element and their manufacturing method
JP2019019011A (en) * 2017-07-12 2019-02-07 日本電気硝子株式会社 Glass used for wavelength conversion material, wavelength conversion material, wavelength conversion member and light-emitting device

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JPH08157231A (en) * 1994-12-02 1996-06-18 Hoya Corp Low melting point optical glass
JP2002293572A (en) * 2001-01-29 2002-10-09 Hoya Corp Optical glass
JP2011230991A (en) * 2010-04-30 2011-11-17 Ohara Inc Optical glass, preform, and optical element
JP2014185075A (en) * 2013-02-19 2014-10-02 Hoya Corp Optical glass, optical glass blank, glass raw material for press molding, optical element and their manufacturing method
JP2019019011A (en) * 2017-07-12 2019-02-07 日本電気硝子株式会社 Glass used for wavelength conversion material, wavelength conversion material, wavelength conversion member and light-emitting device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3943458A4 (en) * 2019-03-18 2022-12-07 Hikari Glass Co., Ltd. Optical glass, optical element, optical system, interchangeable lens, and optical device

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