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
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/097—Glass compositions containing silica with 40% to 90% silica, by weight containing phosphorus, niobium or tantalum
• • 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
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B11/00—Pressing molten glass or performed glass reheated to equivalent low viscosity without blowing
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B11/00—Pressing molten glass or performed glass reheated to equivalent low viscosity without blowing
  • C03B11/12—Cooling, heating, or insulating the plunger, the mould, or the glass-pressing machine; cooling or heating of the glass in the mould
  • C03B11/122—Heating
• • 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
  • C03C3/066—Glass compositions containing silica with less than 40% silica by weight containing boron containing zinc
• • 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 an optical glass in a broad sense, and more specifically, an optical glass having high dispersion characteristics and suitable for chromatic aberration correction, a glass material for press molding made of the optical glass, an optical element, a manufacturing method thereof, and an optical element blank It relates to the manufacturing method.
• a low dispersion glass lens and a high dispersion glass lens are required.
• a lens an aspherical lens, it is possible to realize an even more sophisticated and compact optical system.
• a combination of a low-dispersion glass lens and a high-dispersion glass lens is effective for high-order achromatization in imaging optical systems and projection optical systems.
• many glass materials on the low dispersion side have a large partial dispersion ratio. Therefore, when correcting higher-order chromatic aberration, in addition to high dispersion characteristics, combining with lenses using glass with a small partial dispersion ratio is more effective. It is valid.
• Phosphate glass which is currently the mainstream as high-dispersion precision press-molding glass, has a large partial dispersion ratio, making it difficult to produce a glass that meets the above-mentioned purposes.
• the silica-based glass disclosed in Japanese Patent Laid-Open No. 2 0 0 4 — 1 6 1 5 98 and the republished WO 2 0 0 4/1 1 0 9 4 2 has low glass stability.
• crystals precipitate while stirring, or cast glass is formed by casting roasted glass. This is not suitable for mass production.
• silica-based glass disclosed in Japanese Patent Application Laid-Open No. 2002-87841 has a large partial dispersion ratio and needs to be improved as a higher-order achromatic material.
• the present invention solves these problems, has high dispersion characteristics, is suitable for high-order achromaticity, and has excellent glass stability, glass material for press molding made of the glass, and
• An object of the present invention is to provide an optical element, and to provide an optical element blank and a method for producing each of the optical elements. Means for solving the problem
• the present invention provides:
• An optical glass characterized in that the Abbe number v d is 20 to 30, APg, F is 0.016 or less, and the liquidus temperature is 1200 ° C or less,
• Kappa 2 total content of 0 is 1 to 30%, a refractive index nd of 1.82 or more: 1. less than 87 (1)
• the total content of Nb 2 0 5 and T i 0 2 is 35 65% ,! ⁇ Total content is 1 ⁇ 15%, Li 2 0, Na 2 0 and K 2 0 total content :!
• the glass material for press molding comprising the optical glass according to any one of the above items (1) to (6),
• optical glass characterized by press-molding a molten glass obtained by heating and melting a glass raw material prepared so as to obtain the optical glass according to any one of (1) to (6) above.
• An optical element can be provided.
• the manufacturing method of the optical element blank which consists of the said glass, and the manufacturing method of an optical element can be provided.
• high-dispersion glass exhibits positive anomalous dispersion.
• the partial dispersion ratio Pg, F is kept small, and the partial dispersion ratio Pg ,: F—Abbe number V If the partial dispersion characteristics can be made closer to the line, by combining with a lens made of low dispersion glass, an optical glass material that is extremely effective for correcting higher-order chromatic aberration can be provided.
• the present inventors based on a silica-based composition that is advantageous for bringing the partial dispersion characteristics closer to the normal line, and in order to impart high refractive index and high dispersibility, Nb 2 0 5 and Tio 2 was introduced as an essential component.
• Nb 2 0 5 is more effective in suppressing the partial dispersion ratio between Nb 2 0 5 and T i 0 2 . Therefore, we decided to suppress the partial dispersion ratio by adjusting the ratio of Nb 2 0 5 and T i 0 2 .
• optical glass of the present invention is represented by mass%
• the Abbe number vd is 20 to 30, the partial dispersion ratio P g, F is 0.580 to 0.620, ⁇ P g, F is 0.016 or less, and the liquidus temperature is 1200 ° C or less. It is characterized by being.
• the optical glass of the present invention has a high refractive index n d of, for example, 1.82 to 1.90, and an optical element made of this glass is effective for making an optical system compact.
• the partial dispersion ratio Pg, F is expressed as (ng ⁇ nF) / (nF—nc) using the refractive indexes ng, nF, and nc in the g-line, F-line, and c-line.
• the content of each component and the total content are displayed in mass%, and the ratio of the amounts is also expressed in mass ratio.
• optical glass of the present invention is roughly divided into the following two embodiments.
• An optical glass having a total content of K 2 0 of 1 to 30% and a refractive index nd of 1.82 or more and less than 1.87.
• the second aspect is a glass having a higher refractive index than the first aspect, and as an optional component,
• the total content of Nb 2 0 5 and T i O 2 is 35 to 65%, the total content of K 2 0 is 0. 1 to 15%, L i 2 ⁇ , the total content of Na 2 0 and K 2 ⁇ :! It is an optical glass having a refractive index nd force of Si. 87 to 1.90.
• First aspect from 0 2% S b 2 O 3 outside split both the optical glasses of the second aspect, may be added S n0 2 0-2%.
• S I_ ⁇ 2 is a network-forming oxide glass
• glass stability is an essential component needed in terms of the moldability maintain the molten glass. If the content is less than 12%, the glass stability is lowered and the chemical durability is deteriorated. In addition, the viscosity of the glass at the time of molding the molten glass becomes too low, and the moldability deteriorates. On the other hand, if its content exceeds 40%, the liquidus temperature and glass transition temperature rise, and devitrification resistance and meltability deteriorate. In addition, it will be difficult to achieve the required number of appe Vd. Therefore, the content of S i 0 2 is set to 12 to 40%. A preferred range for the content of S i 0 2 is 15 to 35%, a more preferred range is 18 to 33%, a more preferred range is 20 to 30%, and a more preferred range is 22 to 28%.
• Nb 2 0 5 increases the refractive index, must be agreed Sunari fraction which serves to improve the devitrification resistance by decreasing the liquidus temperature.
• Sunari fraction which serves to improve the devitrification resistance by decreasing the liquidus temperature.
• it is also a component that works to bring the partial dispersion characteristics closer to the normal line, that is, APg, F to zero. If the content is less than 15%, it becomes difficult to maintain the desired refractive index, and it becomes difficult to bring the partial dispersion characteristics closer to the normal line. However, when its content exceeds 42%, the liquidus temperature rises and devitrification resistance decreases. Therefore, the content of Nb 2 0 5 should be 15% or more and less than 42%.
• Nb 2 ⁇ 5 preferred lower limit is 18% of the content of, and more preferable lower limit is 20%, and more preferable lower limit is 22%, even more preferred lower limit is 25% and a preferable upper limit 41.5%, and a more preferred upper limit is 41 %.
• T I_ ⁇ 2 increases the refractive index, be a valid essential component der to improve the devitrification resistance Contact Yopi chemical durability. If the content is less than 2%, the above effect cannot be obtained, and if it is 18% or more, it is difficult to realize a desired Abbe number Vd. Accordingly, the content of T I_ ⁇ 2 and less than 18% or more 2%.
• less than 12% 2% in the optical glass of the second aspect more preferred range the 4% or more and less than 14% in the optical glass of the first embodiment, 3% or more and less than 2% in the optical glass of the second embodiment, and a more preferable range is 5% or more and 1 in the first embodiment.
• Less than 2%, 4% or more and less than 12% in the optical glass of the second embodiment, and a more preferable range is 6% or more and less than 12% in the optical glass of the first embodiment, in the optical glass of the second embodiment.
• 5% or more and less than 12% and there is a more preferable range in the optical glass of the second embodiment, which is 6% or more and less than 12%.
• L i 20 improves the meltability and lowers the glass transition temperature.
• Li 20 is a component that can reduce the glass transition temperature among the alkali metal components, and can maintain a relatively high refractive index.
• glass stability is improved by the mixed alkali effect due to coexistence with Na 2 O and K 2 0.
• L i 2 0 content not above effect is obtained to be less than 1% 0.1 of more than 20%, the liquidus temperature increases, devitrification resistance is decreased. Therefore, the content of L i 2 0 is set to 1-20% 0.1.
• a preferred range for the Li 2 O content is 0.1 to 17%, and a more preferred range is 0.1 to 15%.
• more preferable range is 1% to 10% of the content of L i 2 0 in the optical glass of the first aspect, and even more preferably in the range of 1-5%.
• a more preferred range is 1 to 12%, and a more preferred range is 1 to 10%.
• N a 20 improves the meltability and lowers the glass transition temperature. In addition to Li 2 O, it also functions to dramatically improve the glass stability by the mixed alkali effect. If the content of Na 2 O is less than 0.1%, the above effect cannot be obtained, and if it exceeds 15%, the liquidus temperature rises and devitrification resistance decreases. Therefore, the content of Na 2 0 is set to 0.1 to 15%.
• a preferred range of the content of N a 2 0 is from 0.1 to 12%, a more preferred range is 5-10% 0.1.
• K 2 0 also improves the meltability and lowers the glass transition temperature. In addition to Li 2 0 and Na 2 0, it also functions to dramatically improve the glass stability by the mixed alkali effect. If the content of K 20 is less than 0.1%, the above effect cannot be obtained, and if the content of K 20 exceeds 25%, the liquidus temperature rises and the devitrification resistance decreases. . Accordingly, the content of kappa 2 0 is set to 1 to 25% 0.1.
• 0.1 to 1 5% preferred range of kappa 2 ⁇ content in the optical glass of the second aspect good more preferable range is 0.1 to 12%, still more preferably in the range of 0.5 to 10%, more A preferable range is 0.5 to 7%, and an even more preferable range is 0.5 to 5%.
• the Abbe number vd of the optical glass of the present invention (including the optical glass of the first and second embodiments) is 20-30.
• the desired partial dispersion characteristics are realized while the devitrification resistance is improved. Therefore, a preferable range of the Abbe number Vd is 21 to 29, and a more preferable range is 22 to 29.
• ⁇ Pg, F of the optical glass of the present invention is not more than 0.016, but APg, F is preferably not more than 0.015, in order to make the above properties more favorable, and preferably not more than 0.014. Is more preferably 0.013 or less, and still more preferably 0.012 or less.
• the lower limit of APg, F is not particularly limited, but is usually 0 or more, preferably 0.001 or more, more preferably 0.002 or more, and more preferably 0.005 or more from the viewpoint of improving the above properties. Preferably, 0.007 or more is more preferable.
• the partial dispersion ratio Pg, F is preferably set to 0.580 to 0.620.
• a more preferable range of Pg and F is 0.585 to 0.620, a more preferable range is 0.590 to 0.619, a more preferable range is 0.595 to 0.618, and a still more preferable range is 0. .600 to 0.618.
• the optical glass of the present invention has a liquidus temperature of 1,200 ° C. or lower and excellent stability.
• the preferable range of the liquid bath temperature is 1 180 ° C or lower, and the more preferable range is 1 160 ° C or lower.
• B 2 0 3 is a glass network-forming oxide that improves the meltability and lowers the liquidus temperature. In addition to functioning, it is an effective component for realizing low dispersibility. However, the refractive index and to introduce more than 10% is reduced, since the deteriorated chemical durability, the content of 8 2 0 3 0 to 10%.
• a preferred range for the content of B 2 0 3 is 0-8%, a more preferred range is 0-7%, a further preferred range is ⁇ -6%, and a more preferred range is 0-5%.
• Z r0 2 works to increase the refractive index and improve chemical durability. However, if its content exceeds 20%, devitrification resistance decreases and the glass transition temperature increases. Thus, 0 to 20% of the content of Z r O 2.
• wo 3 works to increase the refractive index, lower the liquidus temperature, and improve devitrification resistance.
• the content of wo 3 is 0 to 22%
• the content of W0 3 is 0 to 20%.
• the preferred range of the content of W0 3 is 0 to 20%, the more preferred range is 0 to 17%, the more preferred range is 1 to 15%, and the more preferred range is 1 to 12%. It is.
• the preferred range of the content of W0 3 is 0 to 17%, the more preferred range is 0 to 15%, the more preferred range is 1 to 12%, and the more preferred range is 1-10%.
• C aO works to improve meltability and increase light transmittance.
• a defoaming effect can be obtained by introducing a carbonate raw material or a nitrate raw material into glass.
• the content of the optical glass of the first embodiment exceeds 17%, and if the content of the optical glass of the second embodiment exceeds 13%, the liquidus temperature increases. And devitrification resistance decreases.
• the refractive index also decreases, in the optical glass of the first aspect, the content of C a ⁇ is 0 to 17%, and in the optical glass of the second aspect, the content of C a O is 0 to 13%.
• the preferable range of the content of C aO is 0 to 15%, the more preferable range is 0 to 12%, the more preferable range is 0 to 10%, and the more preferable range is 0 to 8%. %.
• the preferred range for the content of CaO is 0-12%, more preferred range is 0-10%, more preferred range is 0-7%, and more preferred range is 0-5%.
• SrO also works to improve meltability and increase light transmittance.
• a defoaming effect can be obtained by introducing a carbonate raw material or a nitrate raw material into glass. However, if its content exceeds 13%, the liquidus temperature rises and devitrification resistance decreases.
• the SrO content is set to 0 to 13%.
• a preferred range for the content of SrO is 0-12%, a more preferred range is 0-10%, a more preferred range is 0-7%, and a more preferred range is 0-5%.
• B a O also works to improve meltability and increase light transmittance.
• a defoaming effect can be obtained by introducing a carbonate raw material or a nitrate raw material into glass.
• a preferable range of the content of BaO is 0 to 17%, and in the optical glass of the first embodiment, a more preferable range is 0 to 15%, and a more preferable range is 0 to 12%, and even more preferable.
• the range is 0 to 10%, and the more preferable range is in the optical glass of the second embodiment.
• a more preferable range of the content of BaO is 1 to 15%, a further preferable range is 2 to 12%, and a preferred layer range is 3 to 10%.
• the total content of CaO, SrO and BaO is preferably 0 to 25%.
• a more preferable range of the total content of CaO, SrO and Ba is 1 to 22%, a more preferable range is 2 to 20%, a more preferable range is 3 to: L 7%, and a more preferable range is 5 ⁇ 15%.
• L a 2 0 3 , Gd 2 0 3 , Y 2 0 3 , Yb 2 0 3 are all 0-2%, A more preferable range is 0 to 1%, and even more preferably, neither L a 2 0 3 , Gd 2 0 3 , Y 2 0 3 , or Yb 2 0 3 is introduced.
• Ta 2 0 5 also works to increase the refractive index and improve the chemical durability, but when introduced over 10%, the liquidus temperature rises and the devitrification resistance decreases. Accordingly, the content of Ding & 2 ⁇ 5 to 10% 0.
• a preferable range of the content of Ta 2 0 5 is 0 to 7%, and a more preferable range is 0 to 5%.
• Ge_ ⁇ 2 is a network-forming oxide, also serves to increase the refractive index. However, because it is expensive component, the content of Ge_ ⁇ 2 0-3%, preferably 0-2%. It is more preferred not to introduce Ge_ ⁇ 2.
• B i 2 0 3 works to increase the refractive index and improve the glass stability. However, if it is introduced in excess of 10%, the coloration of the glass increases, so the content of B i 2 0 3 is 0 to 10%. %, Preferably 0 to 5%. In the optical glass of the first aspect, more preferred correct range 0 to 4% of the content of B i 2 0 3, in the optical glass of the second aspect, preferred more of the content of B i 2 0 3 The new range is 0 to 3%.
• the total content of Nb 2 0 5 and Ti 0 2 is 35 to 65%, preferably 38 to 62%, more preferably 40 to 62%, and still more preferably 43 to 60%. %, More preferably 45-58%.
• the total content of Nb 2 0 5 and T i O 2 is 30-60%, preferably 33-59%, more preferably 35-58%, still more preferably 38-57. %, More preferably 40-55%.
• the total content of Li 2 0, Na 2 0 and K 2 0 is 1 to 30%, preferably 2 to 27%, more preferably 3 to 25%, more preferably 4 to 22%, more preferably 5 to 20%.
• the total content of Li 2 O, Na 2 0 and K 2 0 is 1 to 25%, preferably 2 to 22%, more preferably 3 to 20%, and still more preferably 4 to 18%, more preferably 5 to 15%.
• the total content of L i 2 0, Na 2 0 and K 2 0 is too small glass transition temperature rises, also decreases meltability.
• the total amount is too large, the liquidus temperature rises and devitrification resistance decreases.
• the optical glass of the first embodiment has a refractive index nd of 1.82 or more and less than 1.87, preferably 1.82 to 1.865, more preferably 1.82 to 1.860,
• the optical glass of the present invention has a relatively low refractive index.
• the optical glass of the second embodiment has a refractive index nd of 1.87 to 1.90, preferably 1.87 to 1.895, more preferably 1.87 to 1.89. It corresponds to glass with a relatively high refractive index.
• the glass of the present invention does not need to contain components such as Lu and H f. Since Lu and H f are also expensive components, it is preferable to suppress the contents of Lu 2 0 3 and H f 0 2 to 0 to 1%, respectively, and more preferably to suppress to 0 to 0.5%, It is particularly preferable that Lu 2 0 3 is not introduced and H f 0 2 is not introduced.
• the optical glass of the present invention can be added to S N_ ⁇ 2 0-2%.
• S b 2 0 3 can suppress coloration of glass due to impurities was mixed, such as F e.
• the preferred addition amounts of S b 2 0 3 and Sn 2 are 0 to 1%, more preferably 0 to 0.5%, respectively.
• the glass of the present invention has a glass transition temperature of preferably less than 600 ° C, more preferably 590 ° C or less, and further preferably 580 ° C or less. Since the glass transition temperature is low in this way, it is suitable for precision press molding, and it has excellent formability when reheated and softened to form glass. Since the glass transition temperature is low as described above, the heating temperature during molding can be kept relatively low. Therefore, chemical reaction between glass and molds such as press molds is unlikely to occur. Therefore, a glass molded body having a clean and smooth surface can be molded. In addition, deterioration of the mold can be suppressed.
• the above optical glass is prepared by weighing and blending raw materials such as oxides, carbonates, sulfates, nitrates and hydroxides so that the desired glass composition can be obtained. It can be obtained by heating, melting, defoaming and stirring in a melting container to produce a molten glass that is homogeneous and free of bubbles, and is molded. Specifically, it can be made using a known melting method.
• the glass material for press molding of the present invention is characterized by comprising the above-described optical glass of the present invention.
• the said glass raw material means the glass lump used for press molding.
• the glass material may include a glass lump corresponding to the mass of the press-molded product, such as a precision press-molding preform and an optical element blank press-molding glass gop.
• Preform for precision press molding means a glass preform that is heated and used for precision press molding.
• precision press molding is a well-known In this way, it is also called mold optics molding, in which the optical functional surface of the optical element is formed by transferring the molding surface of the press mold.
• the optical function surface means a surface that refracts, reflects, diffracts, or enters and exits the light to be controlled in the optical element.
• the lens surface of the lens corresponds to this optical function surface.
• the release surface is coated on the * surface of the preform so that the glass stretches along the molding surface. It is preferable to do.
• As a type of release film As a type of release film,
• the preform is made as follows.
• the first production example is a method of separating a molten glass lump of a predetermined weight from the molten glass and cooling, and molding a preform having a mass equal to the molten glass lump.
• glass material is melted, clarified, and homogenized to prepare a homogeneous molten glass, which flows out of a temperature-adjusted platinum or platinum alloy outflow nozzle or outflow pipe.
• the molten glass is dropped as molten glass droplets of the desired mass from the outflow nozzle, which is received by the preform mold and molded into the preform.
• a preform is formed by dropping molten glass droplets of the desired mass into liquid nitrogen from an outflow nozzle.
• molten glass flow flow down from the outflow pipe, receive the tip of the molten glass flow with the preform mold, and constrict between the nozzle of the molten glass flow and the preform mold.
• the preform mold is lowered immediately below, the molten glass flow is separated at the constricted part by the surface tension of the molten glass, and the molten glass lump of the desired mass is received by the receiving member into the preform. Mold.
• a preform with a smooth surface such as a free surface, that is free from scratches, dirt, scratches, surface alteration, etc.
• it is floated by applying wind pressure to the molten glass lump on the preform mold.
• Methods such as molding into a preform, or molding at a room temperature such as liquid nitrogen at normal temperature and normal pressure by pouring molten glass droplets into a liquid medium by cooling the gaseous material, are used.
• a gas (called floating gas) is blown to the molten glass lump and an upward wind pressure is applied.
• the floating gas enters the glass and remains as foam in the preform.
• the viscosity of the molten glass block can be floated without the levitation gas entering the glass.
• the gas used when the floating gas is blown into the preform air, 1 ⁇ 2 gas, O 2 gas, A r gas, H e gas, and steam.
• the wind pressure is not particularly limited as long as the preform can float without coming into contact with solids such as the mold surface.
• a homogeneous molten glass is put into a mold and molded, and then the distortion of the molded product is removed by annealing, cut or cleaved, and divided into predetermined dimensions and shapes.
• Individual glass pieces are produced, the glass pieces are polished to smooth the surface, and a preform made of glass having a predetermined mass is used. It is preferable to use the preform thus produced by coating the surface of the preform with a carbon-containing film.
• a glass gob for press molding of an optical element blank which is a glass material, is a glass lump used when press-molding an optical element blank that is finished into an optical element by grinding and polishing.
• the optical element plank has a shape obtained by adding a processing margin to be removed by grinding and polishing to the shape of the target optical element.
• the distortion of the molded body is removed by annealing, cutting or cleaving, dividing into predetermined dimensions and shapes, and a plurality of pieces
• the glass piece is barrel-polished to round the edge of the glass piece, and the mass of the glass gob is adjusted to be equal to the mass of the optical element blank.
• the barrel-polished gob surface is rough, and the powder mold release agent applied to the gob surface for press molding has a surface that is easy to apply uniformly.
• the tip of the flowing molten glass flow is received by a gob mold, and a constriction is formed in the middle of the molten glass flow.
• the molten glass is separated at the part.
• a molten glass lump of a desired mass is obtained on a gob mold, and gas is blown into this glass to form a glass lump while being lifted by applying upward wind pressure.
• the thus obtained glass lump is annealed and then barrel-polished to obtain a glass gob having a desired mass.
• the optical element of the present invention is characterized by comprising the above-described optical glass of the present invention.
• lenses such as aspherical lenses, spherical lenses, or plano-concave lenses, plano-convex lenses, biconcave lenses, biconvex lenses, convex meniscus lenses, concave meniscus lenses, micro lenses, lens arrays, lenses with diffraction gratings, prisms, lenses
• An example is a prism with a function.
• an anti-reflection film or a wavelength selective partial reflection film may be provided on the surface.
• the optical element of the present invention is made of glass having high dispersion characteristics and a small partial dispersion ratio, it can be combined with an optical element made of other glass to perform higher-order color correction. it can. Further, since the optical element of the present invention is made of glass having a high refractive index, the optical system can be made compact by using it in an imaging optical system, a projection optical system, and the like.
• the first method for producing an optical element blank of the present invention is a method for press molding by heating and softening the above-described glass material for press molding of the present invention.
• a powder mold release agent such as boron nitride is uniformly applied to the surface of the glass material, placed on a heat-resistant dish, placed in a heat softening furnace, heated until the glass is softened, and then pressed. It is introduced into a mold and press-molded.
• the press-molded product is taken out of the mold and annealed to remove the distortion and adjust the optical characteristics so that the optical characteristics such as the refractive index become a desired value.
• the second optical element blank manufacturing method is a method for manufacturing an optical element plank in which molten glass is supplied to a press mold and press-molded, and a glass raw material prepared so as to obtain the optical glass of the present invention described above is used.
• This is a method characterized by press-molding molten glass obtained by heating and melting.
• the homogenized glass melt flows out onto a lower mold surface uniformly coated with a powder release agent such as boron nitride, and a roasted glass stream whose lower end is supported by the lower mold is interrupted in the middle. Cut with a cutting blade called. In this way, a molten glass lump having a desired mass is obtained on the lower mold surface.
• the lower mold on which the molten glass lump is placed is transferred to a position just below the upper mold waiting in another position, and the molten glass lump is pressed with the upper mold and the lower mold to form an optical element blank shape.
• pre- The molded product is removed from the mold and annealed to remove the distortion and adjust the optical characteristics so that the optical characteristics such as the refractive index become the desired values.
• Both of the above manufacturing methods can be performed in the atmosphere.
• well-known conditions and things can be used for the molding conditions, the material of the press forming mold, the heating softening furnace and the dish on which the glass gop is placed when heating and softening.
• the first method for producing an optical element of the present invention is characterized in that the optical element blank produced by the above-described method of the present invention is ground and polished. A known method may be used for grinding and polishing.
• the second method for producing an optical element of the present invention is characterized in that the press-molding glass material of the present invention is heated and precision press-molded using a press mold. Here, the glass material is a preform.
• the pressing and pressing process of the press mold and preform is performed using nitrogen gas or a mixture of nitrogen gas and hydrogen gas to prevent oxidation of the molding surface of the press mold or the release film provided on the molding surface. It is preferably performed in a non-oxidizing gas atmosphere such as a gas. In the non-oxidizing gas atmosphere, the carbon-containing film covering the preform surface is not oxidized, and the film remains on the surface of the precision press-molded product. This film should eventually be removed, but to remove the carbon-containing film relatively easily and completely, the precision press-molded product may be heated in an oxidizing atmosphere, for example, in the atmosphere. . Oxidation and removal of the carbon-containing film should be performed at a temperature that prevents the precision press-molded product from being deformed by heating. Specifically, it is preferably performed in a temperature range below the glass transition temperature.
• a press mold whose surface has been processed to a desired shape with high precision is used, but a mold release film is formed on the molding surface in order to prevent glass fusion during pressing. May be.
• the release film include a carbon-containing film, a nitride film, and a noble metal film, and the carbon-containing film is preferably a hydrogenated carbon film or a carbon film.
• the viscosity of the glass is 10 5 to 10 9 d Pa ⁇ s
• Both the mold and the preform are heated to a temperature equivalent to s to soften the preform, and this is pressure-molded to precisely transfer the molding surface of the mold to glass.
• the preform is heated to a temperature equivalent to 10 4 to 10 8 d Pa ⁇ s, and the molding surface of the mold is precisely transferred to the glass by pressing the preform. be able to.
• the pressure and time during pressurization can be appropriately determined in consideration of the viscosity of the glass.
• the press pressure is about 5 to 15 MPa
• the press time is 10 to 300 seconds. be able to.
• the pressing conditions such as pressing time and pressing pressure may be appropriately set within a known range according to the shape and dimensions of the molded product.
• the mold and the precision press-molded product are cooled, and when the temperature is preferably below the strain point, the mold is released and the precision press-molded product is taken out.
• the annealing treatment conditions of the molded product during cooling such as the annealing speed, may be appropriately adjusted.
• the manufacturing method of the second optical element can be roughly divided into the following two methods.
• the first method is a method of manufacturing an optical element in which a glass material is introduced into a press mold and the mold and the glass material are heated together. Emphasis is placed on improving molding accuracy such as surface accuracy and eccentricity accuracy. This is the recommended method.
• the second method is a method of manufacturing an optical element in which a glass material is heated, introduced into a preheated press mold and precision press-molded, and is recommended when emphasizing productivity improvement.
• the optical element of the present invention can be produced without going through a press molding process.
• a homogeneous molten glass is put into a mold to form a glass block, and annealed to remove distortion, and the annealing conditions are adjusted so that the refractive index of the glass becomes a desired value, thereby improving the optical properties.
• the glass block can be cut or cleaved to make a glass piece, and further ground and polished to finish the optical element.
• Table 3 shows the properties of the optical glass thus obtained.
• Refractive indices nd, ng, nF, nc, and Abbe number vd were measured by the refractive index measurement method of the Japan Optical Glass Industry Association standard for the glass obtained by lowering the temperature at a temperature drop rate of 30 ° C / hour.
• the glass was placed in a furnace heated to a predetermined temperature and held for 2 hours. After cooling, the inside of the glass was observed with a 100 ⁇ optical microscope, and the liquidus temperature was determined from the presence or absence of crystals.
• the temperature was measured with a differential scanning calorimeter (DSC) at a heating rate of 10 ° C / min.
• Refractive index ng, n F was calculated from nc.
• Nb205 / Ti02 is the value obtained by dividing the Nb205 content by the Ti02 content
• R20 is the total content of Li20 Na20 and K20.
• R0 is the total content of GaO S) and BaO.
• LT is the liquidus temperature
• Tg is the glass transition temperature
• Glass Nos. 1 to 11 are the optical glasses of the first embodiment. 51400 Table 2
• Nb205 / Ti02 is the value obtained by dividing the Nb205 content by the Ti02 content.
• R20 is the total content of Li20, Na20 and K20.
• R0 is the total content of GaO, SrO and BaO.
• LT is the liquidus temperature
• T g is the glass transition temperature
• LT is the liquidus temperature
• Tg is the glass transition temperature
• Example 3 the glass was obtained by casting the melt into a mirror shape, but precipitation of crystals was observed inside.
• Example 2 Melting, clarifying, and homogenizing the glass raw material prepared so that each optical glass produced in Example 1 is obtained, making a molten glass, dropping a molten glass drop from a platinum nozzle, and receiving it by a preform mold, It was formed into a spherical preform made of the above-mentioned various glasses while being floated by applying wind pressure.
• the molten glass is continuously discharged from the platinum pipe, the lower end of the molten glass is received by a preform mold, a constriction is formed in the molten glass flow, and then the preform mold is rapidly lowered directly below the molten glass.
• the flow was cut at the pierced portion, and the molten glass lump separated on the preform mold was received and molded into preforms made of the above-mentioned various glasses while being floated by applying air pressure. (Example 3)
• the molten glass prepared in Example 2 was continuously flown out and poured into a bowl, formed into a glass block, annealed, and cut to obtain a plurality of glass pieces. These glass pieces were ground and polished to prepare preforms made of the various glasses.
• the molten glass prepared in Example 2 was continuously flowed out and poured into a bowl, formed into a glass block, annealed, and cut to obtain a plurality of glass pieces. These glass pieces were barrel-polished to produce press-molding glass gobs composed of the various glasses described above.
• the preform produced in Examples 2 and 3 was introduced into a press mold including SiC upper and lower molds and body molds, in which the surface of the preform was coated with a carbon-containing film and the molding surface was provided with a carbon-based release film.
• the mold and preform are heated together in a nitrogen atmosphere to soften the preform and precision press-molded to form an aspherical convex meniscus lens, aspherical concave meniscus lens, aspherical biconvex lens, non-spherical
• Various lenses of spherical bilateral lenses were produced.
• a powder mold release agent composed of boron nitride is uniformly applied to the surface of the glass gob produced in Example 4, then heated and softened in the atmosphere, and press-molded with a press mold to form a spherical convex meniscus lens and a spherical concave meniscus. Blanks for various lenses such as lenses, spherical biconvex lenses, and spherical biconcave lenses were made. Thus, the lens blank which consists of said various glass was produced.
• Example 7 The molten glass prepared in Example 2 was flown out, the molten glass flow was cut using a shear, the molten glass mass was separated, and press molded using a press mold, and a spherical convex meniscus lens, spherical concave meniscus lens Various blanks of spherical biconvex lenses and spherical biconcave lenses were produced. Thus, the lens blank which consists of said various glass was produced.
• the lens plank fabricated in Example 6 and Example 7 is annealed to remove distortion and adjust the refractive index to a desired value, and then ground and polished to produce a spherical convex meniscus lens, spherical concave meniscus lens, spherical biconvex lens, Various lenses of spherical biconcave lenses were produced. In this way, lenses made of the various glasses described above were produced.
• Example 2 The molten glass prepared in Example 2 was flown out and inserted into a bowl shape to produce a glass block. This block was cut, ground and polished to produce various spherical lenses and prisms. Industrial applicability
• the optical glass of the present invention is an optical glass having high dispersion characteristics and suitable for correcting high-order chromatic aberration, and is a glass material for press molding such as a precision press molding preform, an optical element blank, and an optical element. It is used suitably for producing.

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