Glass, laser oscillation device, and method for producing glass

Abstract

Provided is a glass material which has a low linear thermal expansion coefficient and which can be used more stably as a laser medium. The glass is characterized by containing, in terms of mol%, 45%-85% of SiO2, 3%-23% of Al2O3, 0%-13% of B2O3, 0%-5% of Li2O, and 0.01%-11% of Ln2O3 (Ln is at least one selected from Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm). The glass is preferably used as a wavelength conversion member 26 of a laser oscillation device 2 that extracts laser light by emitting excitation light L from an excitation light source 20. The wavelength conversion member 26 is disposed between a resonator 22 and a resonator 24.

Description

Glass, laser oscillation device, and glass manufacturing method

[0001] The present invention relates to a glass containing a rare earth metal element that is suitable as a solid-state laser medium, a laser oscillator using the glass, and a method for producing the glass.

[0002] Conventionally, phosphate glass doped with rare earth elements has been used as a solid-state laser medium for high-power and high-peak energy laser systems. For example, Patent Document 1 discloses that Nd ２ O ３ , Yb ２ O ３ A phosphate glass containing phosphate for a solid-state laser medium is disclosed.

[0003] JP 2012-066996 A

[0004] However, since the phosphate glass of Patent Document 1 has a high linear thermal expansion coefficient, when the phosphate glass is used as a solid-state laser medium for higher output power than conventional applications, there is a problem that the phosphate glass may be damaged due to thermal shock when the laser light and the excitation light are turned on and off.

[0005] Given this background, there is a demand for alternative materials to phosphate glass that have a low linear thermal expansion coefficient, excellent thermal shock resistance, and can be used more stably as laser media.

[0006] An object of the present invention is to provide a glass that can be used as a laser medium and has a low linear thermal expansion coefficient and excellent thermal shock resistance.

[0007] As a result of extensive research, the present inventors have found that by appropriately designing the glass composition, it is possible to obtain a glass material that has a low linear thermal expansion coefficient and can be used more stably as a laser medium.

[0008] The glass of embodiment 1 contains, in mol %, SiO ２ 45-85%, Al ２ O ３ 3-23%, B ２ O ３ 0-13%, Li ２ O 0-5%, Ln２ O ３ (Ln is at least one element selected from Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm) 0.01 to 11%.

[0009] The glass of embodiment 2 is the same as embodiment 1 except that, in mol %, P ２ O ５ It is preferable that the content is more than 0%.

[0010] The glass of embodiment 3 is the glass of embodiment 1 or 2, further comprising, in mol %, Fe ２ O ３ It is preferable that the content is more than 0%.

[0011] The glass of embodiment 4 is the glass of any one of embodiments 1 to 3, wherein, in mol %, Lm ２ O ３ (Lm is at least one element selected from La, Y and Lu) It is preferable that the content is 0 to 10%.

[0012] The glass of Aspect 5 is the glass of any one of Aspects 1 to 4, further comprising, in mol %, SnO ２ It is preferable that the content is more than 0%.

[0013] The glass of embodiment 6, in any one of embodiments 1 to 5, preferably contains 12.5% ​​or less of ZnO in mol %.

[0014] The glass of embodiment 7 is the glass of any of embodiments 1 to 6, further comprising, in mol %, Li ２ O + Na ２ O+K ２ It is preferable that the content of O is 15% or less.

[0015] The glass of embodiment 8 is the glass of any one of embodiments 1 to 7, further comprising, in mol %, (P ２ O ５ ×TiO ２ ) / (Al ２ O ３ +P ２ O ５ ) is preferably 0.0000016 or more.

[0016] The glass of Aspect 9 is the glass of any one of Aspects 1 to 8, further comprising, in mol %, P ２ O ５×TiO ２ is preferably 0.00002 or more.

[0017] The glass of Aspect 10 is the glass of any one of Aspects 1 to 9, further comprising, in mol%, MgO+CaO+SrO+BaO 0 to 6.0%, Li ２ O + Na ２ O+K ２ O 0-2.6%, P ２ O ５ ×TiO ２ It is preferably 0.01 or more.

[0018] The glass of Aspect 11 is the glass of any one of Aspects 1 to 10, wherein the coefficient of linear thermal expansion at 30 to 380°C is 60×10 －７ / °C or less is preferred.

[0019] The glass of embodiment 12 contains, in mole percent, SiO ２ 45-85%, Al ２ O ３ 3-23%, B ２ O ３ 0-13%, Ln ２ O ３ (Ln is at least one selected from Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm) 0.01 to 11%, P ２ O ５ More than 0 to 20%, MgO+CaO+SrO+BaO 0 to 10%, Li ２ O + Na ２ O+K ２ O 0 to 5%, and the linear thermal expansion coefficient at 30 to 380 ° C is 40 × 10 －７ / °C or less.

[0020] The glass of embodiment 13 contains, in mole percent, SiO ２ 45-85%, Al ２ O ３ 3-23%, B ２ O ３ 0-13%, Ln ２ O ３ (Ln is at least one selected from Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm) 0.01 to 11%, P ２ O ５Over 0 to 20%, Li ２ O 0-5%, ZrO ２ 0-20%, MgO+CaO+SrO+BaO 0-10%, Li ２ O + Na ２ O+K ２ O 0 to 2.9%, and the molar ratio (MgO + CaO + SrO + BaO) / P ２ O ５ The linear thermal expansion coefficient at 30 to 380°C is 40 x 10 －７ / °C or less.

[0021] The glass of embodiment 14 is the glass of any one of embodiments 1 to 13, further comprising TiO ２ It is preferable that the content is more than 0%.

[0022] The glass of embodiment 15 comprises, in mole percent, Ln ２ O ３ (Ln is at least one element selected from Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm) 0.01 to 11% and having a linear thermal expansion coefficient of 5 to 40 × 10 at 30 to 380°C. －７ / °C.

[0023] The glass of Aspect 16 is preferably used as a laser medium in any one of Aspects 1 to 15.

[0024] The laser oscillation device of Aspect 17 preferably includes the glass of any one of Aspects 1 to 16.

[0025] A method for producing glass of Aspect 18 is a method for producing the glass of any of Aspects 1 to 16, comprising: a step of melting glass raw materials to obtain molten glass; and a step of shaping the molten glass, wherein the shaping of the molten glass is carried out by an overflow method, a float method, a downdraw method, a slot-down method, a containerless method, a blowing method, a pressing method, a rolling method, a bushing method, or a tube drawing method.

[0026] According to the present invention, it is possible to provide a glass that can be used as a laser medium, has a low coefficient of linear thermal expansion, and is excellent in thermal shock resistance.

[0027] Fig. 1 is a schematic perspective view showing one example of the shape of the glass of the present invention. Fig. 2 is a schematic perspective view showing another example of the shape of the glass of the present invention. Fig. 3 is a schematic view of a laser oscillation device using the glass of the present invention.

[0028] The glass of the present invention (hereinafter also simply referred to as "glass") contains, in mol %, SiO ２ 45-85%, Al ２ O ３ 3-23%, B ２ O ３ 0-13%, Li ２ O 0-5%, Ln ２ O ３ (Ln is at least one element selected from Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm) 0.01 to 11%. The reasons for restricting the content and properties of each component as described above are explained below. In the following explanation of the content of each component, "%" means "mol %" unless otherwise specified.

[0029] SiO ２ is a component that forms the glass skeleton. It is also a component that may be particularly involved in the ease with which phase separation occurs. ２ If the content of SiO is too low, the coefficient of linear thermal expansion tends to be high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Also, chemical durability tends to be reduced. ２ The lower limit of the content of SiO is 45% or more, preferably 50% or more, more preferably 53% or more, 55% or more, 56% or more, 57% or more, 58% or more, 59% or more, particularly preferably 60% or more. ２ If the content is too high, the homogeneity of the glass melt is likely to decrease. ２ Scum with a high content of SiO is likely to be generated, and devitrification such as cristobalite precipitates from the scum, which increases the production load. Here, scum refers to unreacted matter and floating matter on the surface of the molten glass in the melting furnace, and refers to a substance whose main component is cristobalite. ２The upper limit of the content is 85% or less, preferably 83% or less, more preferably 80% or less, 77% or less, 74% or less, 71% or less, 68% or less, particularly preferably 65% ​​or less.

[0030] Al ２ O ３ is a component that forms the glass skeleton. It is also a component that may be involved in the ease of phase separation. ２ O ３ If the content of Al is too low, the linear thermal expansion coefficient tends to be high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, chemical durability is reduced, and the glass surface is prone to deterioration. As a result, the surface irregularities deteriorate, making it difficult to obtain glass with the desired transmittance. Furthermore, the rare earth elements are not sufficiently dispersed in the glass, which causes concentration quenching and tends to reduce laser amplification and laser oscillation efficiency. Therefore, Al ２ O ３ The lower limit of the content of Al is 3% or more, preferably 4% or more, more preferably 5% or more, 6% or more, 8% or more, 10% or more, 12% or more, particularly preferably 13% or more. ２ O ３ If the content of Al is too high, the homogeneity of the glass melt is likely to decrease. Furthermore, crystals such as mullite tend to precipitate, causing the glass to devitrify, making the glass more susceptible to breakage. ２ O ３ The upper limit of the content is 23% or less, preferably 21% or less, more preferably 19% or less, 17% or less, and particularly preferably 15% or less.

[0031] B ２ O ３ is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component that may be particularly involved in the ease with which phase separation occurs. Furthermore, it has the effect of reducing the linear thermal expansion coefficient and improving heat resistance and thermal shock resistance. ２ O ３ The lower limit of the content of B is preferably more than 0%, and is preferably 0.5% or more, 1% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, particularly preferably 3.5% or more. ２ O ３If the content is too high, the B ２ O ３ The amount of evaporation of B increases, and B appears on the surface of the glass melt. ２ O ３ The content of SiO is relatively low ２ As a result, devitrification such as cristobalite is likely to occur from the scum, increasing the production load. In addition, the chemical durability of the glass is reduced, and the glass surface is more likely to be altered, which deteriorates the surface irregularities and makes it difficult to obtain glass with the desired high transmittance. Therefore, B ２ O ３ The upper limit of the content of is 13% or less, preferably 11.5% or less, and more preferably 11% or less, 10.5% or less, 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.85% or less, 7.8% or less, 7.7% or less, 7.5% or less, 7% or less, 6.5% or less, 6.4% or less, 6.3% or less, 6.2% or less, 6.1% or less, 6% or less, 5.9% or less, 5.8% or less, 5.7% or less, 5.6% or less, 5.5% or less, 5.4% or less, 5.3% or less, 5.2% or less, 5.1% or less, and particularly preferably 5% or less. ２ O ３ is easily mixed in as an impurity, ２ O ３ If we try to completely eliminate B, the raw material batch will become expensive and the manufacturing cost will tend to increase. ２ O ３ The content may be 0.0001% or more, 0.0003% or more, particularly 0.0005% or more.

[0032] Li ２ O is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component that can be involved in the phase separation of glass. ２ If the O content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. In addition, the chemical durability of the glass decreases, and the glass surface is likely to be altered. As a result, the surface irregularity deteriorates, making it difficult to obtain glass with a desired high transmittance. Therefore, Li２ The upper limit of the O content is 5% or less, preferably 4.5% or less, more preferably 4% or less, 3.5% or less, 3% or less, 2.5% or less, 2% or less, 1.9% or less, 1.8% or less, 1.5% or less, 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, particularly preferably 0.1% or less. ２ Since O is easily mixed in as an impurity, Li ２ If an attempt is made to completely remove O, the raw material batch becomes expensive and the manufacturing cost tends to increase. Therefore, in order to suppress the increase in manufacturing cost, ２ The lower limit of the O content is preferably more than 0%, and is preferably 0.00001% or more, 0.00002% or more, 0.00003% or more, 0.00004% or more, 0.00005% or more, particularly preferably 0.0001% or more.

[0033] Ln ２ O ３ (Ln is at least one element selected from Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm) functions as a laser oscillation ion in glass. These elements can be used alone or in combination of two or more elements. From the viewpoint of obtaining glass with high transparency, it is preferable that Ln contains Nd. Nd acts as a color complementing agent for the coloration of iron contained in the raw materials of the glass, and has the advantage that if a heterogeneous phase (bubbles, uneven composition spots, devitrification particles, etc.) is present in the glass, the presence of the heterogeneous phase can be easily noticed by visual inspection or various inspection devices. Ln ２ O ３ If the content of Ln is too low, the amount of light emitted is small, and the laser amplification and oscillation efficiency are very low, making it difficult to obtain sufficient laser output. In addition, even if laser amplification is performed, the size of the glass required for amplification becomes large. Therefore, ２ O ３ The lower limit of the content of Ln is 0.01% or more, preferably 0.1% or more, more preferably 0.2% or more, 0.3% or more, 0.5% or more, 0.6% or more, 0.7% or more, 1% or more, 3% or more, particularly preferably 5% or more. ２ O ３If the content of Ln is too high, the glass is likely to devitrify and lose its translucency due to crystallization. In addition, concentration saturation will result in extremely low laser amplification and oscillation efficiency. ２ O ３ The upper limit of the Nd content is 11% or less, preferably 10% or less, more preferably 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, particularly preferably 6.0% or less. ２ O ３ In order to adjust the emission properties related to Yb ２ O ３ , Gd ２ O ３ , Eu ２ O ３ , Sm ２ O ３ , and Tb ２ O ３ Representative ranges of the oscillation wavelength for each laser oscillation ion are shown below, but the oscillation wavelength is not limited to these, and may be in the visible wavelength range of 380 to 780 nm, or in the ultraviolet range on the short wavelength side, or in the infrared range on the long wavelength side.

[0034] Ce ２ O ３ is a component that enables laser output at wavelengths of around 300 nm to 500 nm. ２ O ３ If the content of Ce is too high, the glass is likely to devitrify and lose its translucency due to crystallization. In addition, it becomes difficult to prevent a decrease in transmittance due to the glass turning yellow or orange. In addition, concentration saturation causes a very low laser amplification and oscillation efficiency. ２ O ３ If the content is too small, it becomes difficult to obtain a sufficient laser output in the wavelength range of 300 nm to 500 nm. ２ O ３ The upper limit of the content of Ce is preferably 11% or less, more preferably 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, particularly preferably 6.0% or less. ２ O ３The lower limit of the content is preferably 0.01% or more, more preferably 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 3% or more, particularly preferably 5% or more.

[0035] Nd ２ O ３ is a component that enables laser output at wavelengths of around 1000 nm to 1200 nm. It is also a component that can suppress the coloring of iron that may be contained in the raw materials of glass as a color complementing agent. Specifically, Nd ２ O ３ This is a technique that creates an achromatic color by overlaying blue coloring by Nd ２ O ３ If the content of Nd is too high, the glass is likely to devitrify and lose its translucency due to crystallization. In addition, concentration saturation results in extremely low laser amplification and oscillation efficiency. ２ O ３ If the content is too small, it becomes difficult to obtain a sufficient laser output in the wavelength range of 1000 nm to 1200 nm. ２ O ３ The upper limit of the content of Nd is preferably 11% or less, more preferably 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, particularly preferably 6.0% or less. ２ O ３ The lower limit of the content is preferably 0.01% or more, more preferably 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 3% or more, particularly preferably 5% or more.

[0036] Yb ２ O ３ is a component that enables laser output at wavelengths around 925 nm to 1100 nm. ２ O ３ If the content of Yb is too high, the glass is likely to devitrify and lose its translucency due to crystallization. In addition, concentration saturation results in extremely low laser amplification and oscillation efficiency. ２ O ３If the content of Yb is too small, it becomes difficult to obtain a sufficient laser output in the wavelength range of 925 nm to 1100 nm. ２ O ３ The upper limit of the content of Yb is preferably 11% or less, more preferably 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, and particularly preferably 6.0% or less. ２ O ３ The lower limit of the content is preferably 0.01% or more, more preferably 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 3% or more, particularly preferably 5% or more.

[0037] Er ２ O ３ is a component that enables laser output at wavelengths around 1530 to 1620 nm. ２ O ３ If the content of Er is too high, the glass is likely to devitrify and lose its translucency due to crystallization. In addition, concentration saturation results in extremely low laser amplification and oscillation efficiency. ２ O ３ If the content of Er is too small, it becomes difficult to obtain a sufficient laser output in the wavelength range of 1530 nm to 1620 nm. ２ O ３ The upper limit of the content of Er is preferably 11% or less, more preferably 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, particularly preferably 6.0% or less. ２ O ３ The lower limit of the content is preferably 0.01% or more, more preferably 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 3% or more, particularly preferably 5% or more.

[0038] Pr ２ O ３ is a component that enables laser output at a wavelength of around 630 nm to 670 nm. ２ O ３If the content of Pr is too high, the glass is likely to devitrify and lose its translucency due to crystallization. In addition, concentration saturation results in extremely low laser amplification and oscillation efficiency. ２ O ３ If the content of Pr is too small, it becomes difficult to obtain a sufficient laser output in the wavelength range of 630 nm to 670 nm. ２ O ３ The upper limit of the content of Pr is preferably 11% or less, more preferably 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, particularly preferably 6.0% or less. ２ O ３ The lower limit of the content is preferably 0.01% or more, more preferably 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 3% or more, particularly preferably 5% or more.

[0039] Sm ２ O ３ is a component that enables laser output at wavelengths around 500 nm to 700 nm. ２ O ３ If the content of Sm is too high, the glass is likely to devitrify and lose its translucency due to crystallization. In addition, concentration saturation results in extremely low laser amplification and oscillation efficiency. ２ O ３ If the content of Sm is too low, it becomes difficult to obtain a sufficient laser output in the wavelength range of 500 nm to 700 nm. ２ O ３ The upper limit of the Sm content is preferably 11% or less, more preferably 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, particularly preferably 6.0% or less. ２ O ３ The lower limit of the content is preferably 0.01% or more, more preferably 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 3% or more, particularly preferably 5% or more.

[0040] EU ２ O ３is a component that enables laser output at a wavelength of around 550 nm to 650 nm. ２ O ３ If the content of Eu is too high, the glass is likely to devitrify and lose its translucency due to crystallization. In addition, concentration saturation results in extremely low laser amplification and oscillation efficiency. ２ O ３ If the content is too small, it becomes difficult to obtain a sufficient laser output in the wavelength range of about 550 nm to 650 nm. ２ O ３ The upper limit of the content of Eu is preferably 11% or less, more preferably 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, particularly preferably 6.0% or less. ２ O ３ The lower limit of the content is preferably 0.01% or more, more preferably 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 3% or more, particularly preferably 5% or more.

[0041] Tb ２ O ３ is a component that enables laser output at wavelengths in the vicinity of 350 nm to 600 nm. ２ O ３ If the content of Tb is too high, the glass is likely to devitrify and lose its translucency due to crystallization. In addition, concentration saturation results in extremely low laser amplification and oscillation efficiency. ２ O ３ If the content of Tb is too small, it becomes difficult to obtain a sufficient laser output in the wavelength range of 350 nm to 600 nm. ２ O ３ The upper limit of the content of Tb is preferably 11% or less, more preferably 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, and particularly preferably 6.0% or less. ２ O ３ The lower limit of the content is preferably 0.01% or more, more preferably 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 3% or more, particularly preferably 5% or more.

[0042] Dy ２ O ３ is a component that enables laser output at wavelengths of around 250 nm to 600 nm. ２ O ３ If the content of Dy is too high, the glass is likely to devitrify and lose its translucency due to crystallization. In addition, concentration saturation will result in extremely low laser amplification and oscillation efficiency. ２ O ３ If the content of Dy is too small, it becomes difficult to obtain a sufficient laser output in the wavelength range of 250 nm to 600 nm. ２ O ３ The upper limit of the content of Dy is preferably 11% or less, more preferably 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, particularly preferably 6.0% or less. ２ O ３ The lower limit of the content is preferably 0.01% or more, more preferably 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 3% or more, particularly preferably 5% or more.

[0043] Ho ２ O ３ is a component that enables laser output at a wavelength of around 2050 nm to 2150 nm. ２ O ３ If the content of Ho is too high, the glass is likely to devitrify and lose its translucency due to crystallization. In addition, concentration saturation results in extremely low laser amplification and oscillation efficiency. ２ O ３ If the content of Ho is too small, it becomes difficult to obtain a sufficient laser output in the wavelength range of 2050 nm to 2150 nm. ２ O ３ The upper limit of the content of Ho is preferably 11% or less, more preferably 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, particularly preferably 6.0% or less. ２ O ３The lower limit of the content is preferably 0.01% or more, more preferably 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 3% or more, particularly preferably 5% or more.

[0044] Tm ２ O ３ is a component that enables laser output at wavelengths around 1950 nm to 2050 nm. ２ O ３ If the content of Tm is too high, the glass is likely to devitrify and lose its translucency due to crystallization. In addition, concentration saturation results in extremely low laser amplification and oscillation efficiency. ２ O ３ If the content of Tm is too small, it becomes difficult to obtain a sufficient laser output in the wavelength range of 1950 nm to 2050 nm. ２ O ３ The upper limit of the content of Tm is preferably 11% or less, more preferably 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, particularly preferably 6.0% or less. ２ O ３ The lower limit of the content is preferably 0.01% or more, more preferably 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 3% or more, particularly preferably 5% or more.

[0045] The glass of the present invention may contain the following components in addition to the above components.

[0046] P ２ O ５ In the glass of the present invention, P is a component that reduces the linear thermal expansion coefficient of the glass. It is also a component that adjusts the refractive index. It is also a component that can be involved in phase separation of the glass. ２ O ５ If the content of P is too high, the viscosity of the glass becomes too high, and the homogeneity of the glass melt tends to decrease. In addition, the chemical durability of the glass decreases, and the glass surface tends to be easily altered. ２ O ５The upper limit of the content of P is preferably 30% or less, more preferably 25% or less, 20% or less, 17% or less, 14% or less, 11% or less, 8% or less, 7% or less, and particularly preferably 6% or less. ２ O ５ The lower limit of the content is preferably more than 0%, and is preferably 0.1% or more, 1% or more, 2% or more, 3% or more, 4% or more, particularly preferably 4.5% or more.

[0047] P ２ O ５ is a component that reduces the linear thermal expansion coefficient of the glass in the present invention, while P ２ O ５ If the content of B is too high, the viscosity of the glass increases, and the melting property of the glass tends to decrease. ２ O ３ is a component that can reduce the viscosity of the glass. If the viscosity of the glass is too high, for example, higher temperatures are required when melting or molding the glass, which puts a strain on the manufacturing equipment and increases energy costs, leading to a decrease in productivity. Therefore, in order to reduce the viscosity of the glass while reducing the linear thermal expansion coefficient and obtain a glass with good productivity, B ２ O ３ / P ２ O ５ (B ２ O ３ The content in mole percent of P ２ O ５ It is preferable to strictly control the content (mol %) of B. ２ O ３ / P ２ O ５ The lower limit of B is preferably more than 0, and is preferably 0.01 or more, 0.1 or more, 0.3 or more, 0.5 or more, 0.6 or more, and particularly preferably 0.7 or more. ２ O ３ / P ２ O ５ The upper limit is preferably 1200 or less, more preferably 1000 or less, 800 or less, 550 or less, 300 or less, 100 or less, 80 or less, 50 or less, 20 or less, 10 or less, and particularly preferably 1 or less.

[0048] TiO２ is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the melting and formability of glass. It also lowers the linear thermal expansion coefficient. It also absorbs light of various wavelengths and is a coloring component of glass. In particular, when titanium and iron coexist, it produces ilmenite (FeTiO ３ It is known that when titanium and tin coexist, the yellow color becomes stronger. ２ is also a component that may be particularly involved in the ease with which phase separation occurs. ２ If the content of TiO is too high, the meltability of the glass is likely to decrease. In addition, the glass is likely to be colored, making it difficult to obtain glass with a desired high transmittance. ２ The upper limit of the content of TiO is preferably 20% or less, more preferably 16% or less, 12% or less, 8% or less, particularly preferably 5% or less. ２ The content of may be 3% or less, 2% or less, or 1% or less. ２ The lower limit of the content is preferably more than 0%, and is preferably 0.001% or more, 0.01% or more, 0.1% or more, 0.3% or more, 0.5% or more, 0.7% or more, 1% or more, 2% or more, particularly preferably 3% or more.

[0049] In the glass of the present invention, P ２ O ５ is a component that can reduce the linear thermal expansion coefficient of glass, and this effect is enhanced by TiO ２ However, in the viscosity of glass, P ２ O ５ contributes to the increase, and TiO ２ Therefore, in order to reduce the linear thermal expansion coefficient while appropriately suppressing an increase in the viscosity of the glass and obtain a glass with good productivity, it is necessary to add P. ２ O ５ ×TiO ２ (P ２ O ５ and TiO ２ It is preferable to strictly control the content (product of the respective contents in mol%) of P. ２ O５ ×TiO ２ If P is too large, the viscosity of the glass tends to increase, which reduces productivity. ２ O ５ ×TiO ２ The upper limit of P is preferably 900 or less, more preferably 500 or less, 300 or less, 150 or less, 100 or less, 80 or less, 60 or less, 40 or less, 30 or less, 20 or less, and particularly preferably 10 or less. On the other hand, in order to obtain a glass having a low linear thermal expansion coefficient, P ２ O ５ ×TiO ２ The lower limit is preferably more than 0, and is preferably 0.00002 or more, 0.0001 or more, 0.001 or more, 0.01% or more, 0.1 or more, 0.22 or more, 0.23 or more, 0.25 or more, 1 or more, 3 or more, 5 or more, and particularly preferably 7 or more.

[0050] P ２ O ５ and TiO ２ are components that reduce the coefficient of linear thermal expansion, and P ２ O ５ contributes to an increase in the viscosity of the glass, and TiO ２ contributes to a decrease in the viscosity of the glass. ２ O ３ is a component that forms the glass skeleton and can contribute to reducing the linear expansion coefficient of the glass. ２ O ５ and TiO ２ If the content of (P) is too large, the viscosity of the glass will decrease and the liquidus temperature will increase, which will result in a decrease in productivity. ２ O ５ ×TiO ２ ) / (Al ２ O ３ +P ２ O ５ ) (P ２ O ５ and TiO ２ The product of the contents in mol% of each is Al ２ O ３ and P ２ O ５The lower limit of (P) is preferably more than 0, and is preferably 0.000001 or more, 0.0000013 or more, 0.0000016 or more, 0.00001 or more, 0.0001 or more, 0.001 or more, 0.01 or more, 0.1 or more, particularly preferably 0.15 or more. ２ O ５ ×TiO ２ ) / (Al ２ O ３ +P ２ O ５ The upper limit of (a) is preferably 10 or less, more preferably 5 or less, 4 or less, 3 or less, 2 or less, or 1 or less, and particularly preferably 0.5 or less.

[0051] Fe ２ O ３ is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the melting and formability of glass. It is also a component that releases oxygen-based gases through oxidation-reduction reactions and can also contribute to the clarification of glass. It is also a component that absorbs light of various wavelengths, coloring glass, and can also contribute to phase separation of glass. ２ O ３ If the content of Fe is too high, the glass is likely to be colored, making it difficult to obtain glass with a desired high transmittance. In addition, devitrification containing Fe is likely to occur, increasing the production load. ２ O ３ The upper limit of the content of is preferably 20% or less, more preferably 15% or less, 10% or less, 5% or less, 1% or less, 0.5% or less, particularly preferably 0.1% or less. ２ O ３ The lower limit of the content is preferably more than 0%, and is preferably 0.0001% or more, 0.001% or more, 0.005% or more, particularly preferably 0.01% or more.

[0052] Lm ２ O ３ (Lm is at least one element selected from La, Y, and Lu) does not itself become a luminescence center in the glass, but has the effect of suppressing aggregation of other rare earth elements that become luminescence centers in the glass. ２ O ３If the content of Lm is too high, the glass is likely to devitrify and lose its translucency due to crystallization. ２ O ３ The upper limit of the content of Lm is preferably 10% or less, more preferably 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, particularly preferably 6.0% or less. ２ O ３ The lower limit of the content is not particularly limited, but is preferably more than 0%, and is preferably 0.0001% or more, 0.001% or more, 0.005% or more, particularly preferably 0.01% or more.

[0053] La ２ O ３ is a component that prevents concentration quenching in the glass of the present invention. ２ O ３ If the content of La is too high, the glass is likely to devitrify and lose its translucency due to crystallization. ２ O ３ The upper limit of the content of La is preferably 10% or less, more preferably 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, particularly preferably 6.0% or less. ２ O ３ The lower limit of the content is not particularly limited, but is preferably more than 0%, and is preferably 0.0001% or more, 0.001% or more, 0.005% or more, particularly preferably 0.01% or more.

[0054] Y ２ O ３ is a component that prevents concentration quenching in the glass of the present invention. ２ O ３ If the content of Y is too high, the glass is likely to devitrify and lose its translucency due to crystallization. ２ O ３The upper limit of the content of is preferably 10% or less, and is preferably 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, 2.0% or less, 1.5% or less, 1.0% or less, and particularly preferably 0.5% or less. ２ O ３ The lower limit of the content is not particularly limited, but is preferably more than 0%, and is preferably 0.0001% or more, 0.001% or more, 0.005% or more, particularly preferably 0.01% or more.

[0055] Lu ２ O ３ is a component that prevents concentration quenching in the glass of the present invention. ２ O ３ If the content of Lu is too high, the glass is likely to devitrify and lose its translucency due to crystallization. ２ O ３ The upper limit of the content of Lu is preferably 10% or less, more preferably 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7.0% or less, 6.5% or less, particularly preferably 6.0% or less. ２ O ３ The lower limit of the content is not particularly limited, but is preferably more than 0%, and is preferably 0.0001% or more, 0.001% or more, 0.005% or more, particularly preferably 0.01% or more.

[0056] Na ２ O is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component that adjusts the linear thermal expansion coefficient and refractive index of glass, and is also a component that can be involved in the phase separation of glass. ２ If the O content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. In addition, the chemical durability of the glass decreases, and the glass surface is likely to be altered. As a result, the surface irregularities deteriorate, making it difficult to obtain glass with the desired high transmittance. Therefore, Na ２The upper limit of the O content is preferably 15% or less, and more preferably 10% or less, 7% or less, 5% or less, 4.5% or less, 4% or less, 3.5% or less, 3% or less, 2.5% or less, 2% or less, 1% or less, 0.7% or less, 0.4% or less, 0.1% or less, and particularly preferably 0.05% or less. ２ O is easily mixed in as an impurity, so Na ２ If an attempt is made to completely remove O, the raw material batch becomes expensive and the manufacturing cost tends to increase. Therefore, in order to suppress the increase in manufacturing cost, Na ２ The lower limit of the O content is preferably more than 0%, and is preferably 0.0001% or more, 0.0003% or more, 0.0005% or more, 0.001% or more, 0.002% or more, 0.004% or more, 0.006% or more, 0.008% or more, particularly preferably 0.01% or more.

[0057] K ２ O is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component that adjusts the linear thermal expansion coefficient and refractive index of glass, and is also a component that can be involved in the phase separation of glass. ２ If the O content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. In addition, the chemical durability of the glass decreases, and the glass surface is likely to be altered. Therefore, K ２ The upper limit of the O content is preferably 15% or less, and more preferably 10% or less, 7% or less, 5% or less, 4.5% or less, 4% or less, 3.5% or less, 3% or less, 2.5% or less, 2% or less, 1% or less, 0.7% or less, 0.4% or less, 0.1% or less, and particularly preferably 0.05% or less. ２ O is easily mixed in as an impurity, so K ２ If an attempt is made to completely remove O, the raw material batch becomes expensive and the manufacturing cost tends to increase. ２ The lower limit of the O content is preferably more than 0%, and is preferably 0.0001% or more, 0.0003% or more, 0.0005% or more, and particularly preferably 0.001% or more.

[0058] Li２ O, Na ２ O.K. ２ O is a component that reduces the viscosity of the glass and improves the meltability and formability of the glass. It is also a component that can be involved in the phase separation of the glass. ２ O + Na ２ O+K ２ O(Li ２ O, Na ２ O.K. ２ If the total content of Li and O is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. In addition, the chemical durability of the glass is reduced, and the glass surface is likely to be altered. Therefore, Li ２ O + Na ２ O+K ２ The upper limit of O is preferably 15% or less, and is preferably 10% or less, 7% or less, 5% or less, 4.5% or less, 4% or less, 3.5% or less, 3% or less, 2.9% or less, 2.8% or less, 2.7% or less, 2.6% or less, 2.5% or less, 2.4% or less, 2.3% or less, 2.2% or less, 2.1% or less, 2% or less, 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, and particularly preferably 0.05% or less. ２ O, Na ２ O.K. ２ Since O is easily mixed in as an impurity, if it is attempted to completely remove it, the raw material batch becomes expensive and the manufacturing cost tends to increase. ２ O + Na ２ O+K ２ The lower limit of O is preferably more than 0%, more preferably 0.0001% or more, more preferably 0.001% or more, and particularly preferably 0.01% or more.

[0059] MgO is a component that reduces the viscosity of glass and improves its meltability and formability. It also reduces the linear thermal expansion coefficient of glass and adjusts its refractive index. It is also a component that can contribute to phase separation in glass. If the MgO content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the chemical durability of the glass decreases, and the glass surface is prone to deterioration. Therefore, the upper limit of the MgO content is preferably 40% or less, and more preferably 30% or less, 20% or less, 18% or less, 16% or less, 14% or less, and particularly 12% or less. On the other hand, the lower limit of the MgO content is preferably more than 0%, and more preferably 1% or more, 2% or more, 3% or more, and particularly preferably 4% or more. Furthermore, because MgO is easily mixed in as an impurity, attempting to completely remove MgO tends to increase the cost of the raw material batch and the manufacturing cost. Therefore, in order to suppress an increase in production costs, the lower limit of the MgO content is preferably 0.0001% or more, 0.001% or more, and particularly preferably 0.01% or more.

[0060] CaO is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component that adjusts the linear thermal expansion coefficient and refractive index of glass. It is also a component that can be involved in phase separation of glass. If the CaO content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. Furthermore, the chemical durability of the glass decreases, and the glass surface is likely to be altered. Therefore, the upper limit of the CaO content is preferably 30% or less, more preferably 20% or less, 18% or less, 16% or less, 14% or less, and particularly preferably 12% or less. On the other hand, the lower limit of the CaO content is preferably more than 0%, and more preferably 1% or more, 2% or more, 3% or more, and particularly preferably 4% or more. Furthermore, because CaO is easily mixed in as an impurity, attempting to completely remove CaO tends to increase the cost of the raw material batch and the manufacturing cost. Therefore, in order to suppress an increase in production costs, the lower limit of the CaO content is preferably 0.0001% or more, more preferably 0.001% or more, and particularly preferably 0.01% or more.

[0061] SrO is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component that adjusts the linear thermal expansion coefficient and refractive index of glass. It is also a component that can be involved in phase separation of glass. If the SrO content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. Furthermore, the chemical durability of the glass decreases, and the glass surface is likely to be altered. Therefore, the upper limit of the SrO content is preferably 30% or less, more preferably 20% or less, 18% or less, 16% or less, 14% or less, and particularly preferably 12% or less. On the other hand, the lower limit of the SrO content is preferably more than 0%, and more preferably 1% or more, 2% or more, 3% or more, and particularly preferably 4% or more. Furthermore, because SrO is easily mixed in as an impurity, attempting to completely remove SrO tends to increase the cost of the raw material batch and the manufacturing cost. Therefore, in order to suppress an increase in production costs, the lower limit of the SrO content is preferably 0.0001% or more, more preferably 0.001% or more, and particularly preferably 0.01% or more.

[0062] BaO is a component that reduces the viscosity of glass and improves its meltability and formability. It is also a component that adjusts the linear thermal expansion coefficient and refractive index of glass. It is also a component that can be involved in phase separation of glass. If the BaO content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the meltability of glass tends to decrease. Furthermore, the chemical durability of glass decreases, and the glass surface tends to be altered. Therefore, the upper limit of the BaO content is preferably 30% or less, more preferably 20% or less, 18% or less, 16% or less, 14% or less, and particularly preferably 12% or less. On the other hand, the lower limit of the BaO content is preferably more than 0%, and more preferably 1% or more, 2% or more, 3% or more, and particularly preferably 4% or more. Furthermore, because BaO is easily mixed in as an impurity, attempting to completely remove BaO tends to increase the cost of the raw material batch and the manufacturing cost. Therefore, in order to suppress an increase in production costs, the lower limit of the BaO content is preferably 0.0001% or more, more preferably 0.001% or more, and particularly preferably 0.01% or more.

[0063] MgO, CaO, SrO, and BaO are components that reduce the viscosity of glass and improve the meltability and formability of the glass. On the other hand, MgO, CaO, SrO, and BaO are also components that increase the linear expansion coefficient of glass. If the contents of these components are too high, it becomes difficult to obtain glass with excellent heat resistance and thermal shock resistance. In addition, the chemical durability of the glass tends to decrease, and the glass surface tends to be easily altered. Therefore, the upper limit of MgO+CaO+SrO+BaO (the total content of MgO, CaO, SrO, and BaO) is preferably 40% or less, and more preferably 30% or less, 20% or less, 18% or less, 16% or less, 14% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, and particularly preferably 0.1% or less. On the other hand, in order to improve the meltability and formability of the glass, the lower limit of MgO+CaO+SrO+BaO is preferably 0.1% or more, and more preferably 1% or more, 2% or more, 3% or more, and particularly preferably 4% or more. Furthermore, since MgO, CaO, SrO, and BaO are easily mixed in as impurities, attempting to completely remove them tends to increase the cost of the raw material batch and the manufacturing cost. Therefore, in order to suppress the increase in manufacturing cost, the lower limit of the content of MgO + CaO + SrO + BaO is preferably more than 0%, and is preferably 0.0001% or more, 0.0003% or more, 0.0004% or more, and particularly preferably 0.0005% or more.

[0064] MgO, CaO, SrO, and BaO are components that reduce the viscosity of the glass and improve the meltability and formability of the glass. ２ O ５ is a component that greatly contributes to the low expansion of glass, and is also a component that increases the viscosity of glass and enhances phase separation. ２ O ５ (The total content of MgO, CaO, SrO, and BaO in mol % is P ２ O ５If the ratio (MgO+CaO+SrO+BaO) / P is too large, the linear thermal expansion coefficient becomes too high, making it difficult to obtain a glass having excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. Therefore, it is preferable to set the ratio (MgO+CaO+SrO+BaO) / P to (MgO+CaO+SrO+BaO) / P. ２ O ５ The upper limit is preferably 88,000 or less, more preferably 10,000 or less, 100 or less, 20 or less, 15 or less, 10 or less, 5 or less, 4.0 or less, 3.8 or less, 3.6 or less, 1 or less, particularly preferably 0.1 or less.

[0065] ZnO is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component for adjusting the linear thermal expansion coefficient and refractive index of glass. It is also a component that can be involved in glass phase separation. If the ZnO content is too high, glass phase separation is more likely to occur. This can lead to a decrease in the homogeneity of the glass melt and to unintended clouding of the glass. Therefore, the upper limit of the ZnO content is preferably 20% or less, more preferably 18% or less, 17% or less, 15% or less, 14% or less, 13% or less, 12.5% ​​or less, 11% or less, and particularly preferably 10% or less. In particular, when suppressing glass phase separation and reducing the risk of glass clouding, the upper limit of the ZnO content is preferably 3% or less, more preferably 2% or less, 1% or less, 0.5% or less, and particularly preferably none. On the other hand, the lower limit of the ZnO content is preferably more than 0%, and more preferably 0.5% or more, and particularly preferably 1% or more.

[0066] SnO ２ is a component that acts as a fining agent. It is also a component that adjusts the linear thermal expansion coefficient and refractive index of the glass. It is also a component that can be involved in the phase separation of the glass. ２ If the content of SnO is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. In addition, devitrification containing Sn precipitates, which increases the production load. Furthermore, the homogeneity of the glass melt is likely to decrease. In addition, the chemical durability of the glass decreases, and the glass surface is likely to be altered. As a result, the surface irregularities deteriorate, making it difficult to obtain glass with the desired high transmittance. Therefore, SnO２ On the other hand, from the viewpoint of clarity, the upper limit of the content of SnO is preferably 20% or less. ２ The lower limit of the content is preferably more than 0%, and is preferably 0.0001% or more, 0.001% or more, 0.005% or more, 0.01% or more, 0.03% or more, 0.05% or more, particularly preferably 0.1% or more.

[0067] ZrO ２ is a component that improves the Young's modulus and modulus of rigidity of glass. It is also a component that adjusts the linear thermal expansion coefficient and refractive index. It is also a component that can be involved in the phase separation of glass. ２ If the content of ZrO is too high, devitrification increases, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt decreases, making it difficult to melt, and the viscosity increases, making it difficult to refine. In addition, molding of the glass becomes difficult, making it prone to lower productivity. Therefore, ZrO ２ The upper limit of the content of ZrO is preferably 20% or less, more preferably 18% or less, 16% or less, 14% or less, particularly preferably 12% or less. ２ The lower limit of the content of ZrO is preferably more than 0%, and is preferably 0.0001% or more, 0.0002% or more, 0.0003% or more, 0.0004% or more, 0.0005% or more, 0.0006% or more, 0.0007% or more, 0.0008% or more, 0.0009% or more, 0.001% or more, 0.002% or more, 0.003% or more, 0.004% or more, 0.005% or more, 0.006% or more, 0.007% or more, 0.008% or more, 0.009% or more, 0.01% or more, 0.1% or more, 0.2% or more, particularly preferably 0.3% or more. ２ is easily mixed in as an impurity, ２ However, if an attempt is made to completely remove ZrO, the raw material batch becomes expensive and the manufacturing cost tends to increase. ２ The lower limit of the content is preferably more than 0%, more preferably 0.0001% or more, more preferably 0.001% or more, and particularly preferably 0.01% or more.

[0068] HfO ２is a component that improves the Young's modulus and modulus of rigidity of the glass, and also a component that reduces the viscosity of the glass and improves the meltability and formability of the glass. It is also a component that can be involved in the phase separation of the glass. Depending on the application of the glass of the present invention, HfO ２ It is preferable to control the content of HfO and design it so as to obtain the desired mechanical strength. ２ If the content of HfO is too high, the mechanical strength of the glass becomes too high, making processing difficult and making it difficult to obtain glass with the desired surface condition and therefore the desired high transmittance. ２ Since the raw materials are expensive, it leads to an increase in manufacturing costs. ２ The upper limit of the content of is preferably 10% or less, more preferably 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, 0.5% or less, 0.4% or less, 0.3% or less, particularly preferably 0.2% or less. ２ The lower limit of the content of HfO is not particularly limited, ２ is a component that can be mixed in from the raw materials used, and the amount of the mixed in varies depending on the raw material composition. ２ The lower limit of the content is preferably 0.0001% or more, more preferably 0.0003% or more, and particularly preferably 0.0005% or more.

[0069] Pt is a component that can be mixed into glass in the form of ions, colloids, metal, etc., and causes a yellow to brown coloration. It is also a component that can contribute to glass phase separation. If the Pt content is too high, devitrification containing Pt will precipitate, increasing the production load. Therefore, the upper limit of the Pt content is preferably 0.05% or less, and more preferably 0.001% or less, 0.0005% or less, 0.0001% or less, 0.00005% or less, 0.00001% or less, and particularly preferably 0.000005% or less. On the other hand, although the lower limit of the Pt content is not particularly limited, when using general melting equipment, the use of Pt components may be necessary to obtain homogeneous glass. Therefore, completely removing Pt tends to increase production costs. Therefore, in order to suppress an increase in manufacturing costs, the lower limit of the Pt content is preferably more than 0%, more preferably 0.0000001%, and particularly preferably 0.0000005% or more, provided that it does not adversely affect coloration.

[0070] Rh is a component that can be mixed into glass in the form of ions, colloids, metal, etc., and causes a yellow to brown coloration. It is also a component that can contribute to phase separation in glass. If the Rh content is too high, devitrification containing Rh may precipitate, increasing the production load. Therefore, the upper limit of the Rh content is preferably 0.05% or less, and more preferably 0.001% or less, 0.0005% or less, 0.0001% or less, 0.00005% or less, 0.00001% or less, and particularly preferably 0.000005% or less. While there is no particular limit on the lower limit of the Rh content, when using general melting equipment, the use of Rh components may be necessary to obtain homogeneous glass. Therefore, attempting to completely remove Rh tends to increase production costs. Therefore, in order to suppress an increase in production costs, the lower limit of the Rh content is preferably more than 0%, more preferably 0.0000001%, and particularly preferably 0.0000005% or more, provided that it does not adversely affect coloring.

[0071] The upper limit of Pt+Rh (the total content of Pt and Rh) is preferably 0.01% or less, more preferably 0.005% or less, 0.001% or less, 0.0005% or less, 0.0001% or less, 0.00005% or less, 0.00001% or less, particularly preferably 0.000005% or less. The lower limit of Pt+Rh is not particularly limited, but when using general melting equipment, the use of Pt and Rh components may be necessary to obtain homogeneous glass. Therefore, completely removing Pt and Rh tends to increase production costs. Therefore, in order to suppress increases in production costs, the lower limit of Pt+Rh is preferably greater than 0%, and is preferably 0.0000001% or more, particularly preferably 0.0000005% or more, provided that it does not adversely affect coloration.

[0072] V ２ O ５ V is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the melting and formability of glass. It also absorbs light of various wavelengths and serves as a coloring component for glass. It is also a component that can be involved in phase separation of glass. ２ O ５ If the content of V is too high, the meltability of the glass tends to decrease. In addition, the glass tends to be colored, making it difficult to obtain glass with a desired high transmittance. ２ O ５ The upper limit of the content is preferably 20,000 ppm or less, more preferably 10,000 ppm or less, 7,000 ppm or less, 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 100 ppm or less, particularly preferably 50 ppm or less. ２ O ５ is easily mixed in as an impurity, ２ O ５ If an attempt is made to completely remove V, the raw material batch becomes expensive and the manufacturing cost tends to increase. ２ O ５The lower limit of the content of V is preferably more than 0 ppm, and is preferably 1 ppm or more, 2 ppm or more, and particularly preferably 3 ppm or more. ２ O ５ The transmittance may be adjusted by controlling the content of the element.

[0073] Cr ２ O ３ is a component that reduces the viscosity of glass and improves the melting and formability of glass. It also absorbs light of various wavelengths and is a coloring component of glass. It is also a component that can be involved in the phase separation of glass. ２ O ３ If the content of Cr is too high, the glass is likely to be colored, making it difficult to obtain glass with a desired high transmittance. ２ O ３ The upper limit of the content is preferably 20,000 ppm or less, more preferably 10,000 ppm or less, 7,000 ppm or less, 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 100 ppm or less, particularly preferably 50 ppm or less. In addition, devitrification containing Cr precipitates, which tends to increase the production load. Depending on the application of the glass of the present invention, Cr may be added. ２ O ３ The transmittance may be adjusted by controlling the content of the element.

[0074] Cr ２ O ３ and V ２ O ５ is a component that, when contained in an appropriate amount, reduces the viscosity of the glass and improves the meltability and formability of the glass. ２ O ３ +V ２ O ５ (Cr ２ O ３ and V ２ O ５ If the content of Cr is too high, the melting property of the glass is likely to decrease. ２ O ３ +V ２ O ５The upper limit is preferably 200,000 ppm or less, more preferably 100,000 ppm or less, 50,000 ppm or less, 30,000 ppm or less, 20,000 ppm or less, and particularly preferably 10,000 ppm or less.

[0075] MoO ３ is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It also absorbs light of various wavelengths and is a component that colors glass. It is also a component that can be involved in phase separation of glass. ３ If the content of Mo is too high, the glass is likely to be colored, making it difficult to obtain glass with a desired high transmittance. In addition, devitrification containing Mo occurs, which increases the production load. Therefore, MoO ３ The upper limit of the content of MoO is preferably 20,000 ppm or less, more preferably 10,000 ppm or less, 7,000 ppm or less, 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 100 ppm or less, particularly preferably 50 ppm or less. ３ The transmittance may be adjusted by controlling the content of the element.

[0076] MnO ２ MnO is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the meltability and formability of glass. It also absorbs light of various wavelengths and serves as a coloring component for glass. It is also a component that can be involved in phase separation of glass. ２ If the content of MnO is too high, the meltability of the glass tends to decrease. In addition, the glass tends to be colored, making it difficult to obtain glass with a desired high transmittance. ２ The upper limit of the content is preferably 20,000 ppm or less, more preferably 10,000 ppm or less, 7,000 ppm or less, 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 100 ppm or less, particularly preferably 50 ppm or less. ２ is easily mixed in as an impurity, ２However, if an attempt is made to completely remove MnO, the raw material batch becomes expensive and the manufacturing cost tends to increase. ２ The lower limit of the content of MnO is preferably more than 0 ppm, and is preferably 1 ppm or more, 2 ppm or more, and particularly preferably 3 ppm or more. ２ The transmittance may be adjusted by controlling the content of the element.

[0077] CoO is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the meltability and formability of glass. It is also a coloring component of glass that absorbs light of various wavelengths. It is also a component that can be involved in phase separation of glass. If the CoO content is too high, the meltability of glass tends to decrease. Furthermore, the glass tends to be colored, making it difficult to obtain glass with the desired high transmittance. Therefore, the upper limit of the CoO content is preferably 20,000 ppm or less, more preferably 10,000 ppm or less, 7,000 ppm or less, 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 100 ppm or less, and particularly preferably 50 ppm or less. However, because CoO is easily mixed in as an impurity, attempting to completely remove CoO tends to make the raw material batch expensive and increase the production cost. Therefore, in order to suppress an increase in production cost, the lower limit of the CoO content is preferably more than 0 ppm, and is preferably 1 ppm or more, 2 ppm or more, and particularly preferably 3 ppm or more. The CoO content may be controlled to adjust the transmittance depending on the application of the glass of the present invention.

[0078] CuO is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the meltability and formability of glass. It is also a coloring component of glass that absorbs light of various wavelengths. It is also a component that can be involved in phase separation of glass. If the CuO content is too high, the meltability of glass tends to decrease. Furthermore, the glass tends to be colored, making it difficult to obtain glass with the desired high transmittance. Therefore, the upper limit of the CuO content is preferably 20,000 ppm or less, more preferably 10,000 ppm or less, 7,000 ppm or less, 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 100 ppm or less, and particularly preferably 50 ppm or less. However, because CuO is easily mixed in as an impurity, attempting to completely remove CuO tends to make the raw material batch expensive and increase production costs. Therefore, in order to suppress an increase in production costs, the lower limit of the CuO content is preferably more than 0 ppm, and is preferably 1 ppm or more, 2 ppm or more, and particularly preferably 3 ppm or more. The CuO content may be controlled to adjust the transmittance depending on the application of the glass of the present invention.

[0079] WO ３ is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the meltability and formability of glass. It also absorbs light of various wavelengths and serves as a coloring component for glass. It is also a component that can be involved in phase separation of glass. ３ If the content of WO is too high, the glass is likely to be colored, making it difficult to obtain glass with the desired high transmittance. ３ The upper limit of the content is preferably 20,000 ppm or less, more preferably 10,000 ppm or less, 7,000 ppm or less, 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 100 ppm or less, particularly preferably 50 ppm or less. ３ The transmittance may be adjusted by controlling the content of the element.

[0080] NiO is a component that, when incorporated in an appropriate amount, reduces the viscosity of glass and improves the meltability and formability of glass. It is also a coloring component of glass that absorbs light of various wavelengths. It is also a component that can be involved in phase separation of glass. If the NiO content is too high, the meltability of glass tends to decrease. Furthermore, the glass tends to be colored, making it difficult to obtain glass with the desired high transmittance. Therefore, the upper limit of the NiO content is preferably 20,000 ppm or less, more preferably 10,000 ppm or less, 7,000 ppm or less, 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 100 ppm or less, and particularly preferably 50 ppm or less. However, because NiO is easily mixed in from SUS members and the like during the manufacturing process, attempting to completely remove NiO tends to increase the cost of the raw material batch and the manufacturing cost. Therefore, in order to suppress an increase in manufacturing cost, the lower limit of the NiO content is preferably more than 0 ppm, and is preferably 1 ppm or more, 2 ppm or more, and particularly preferably 3 ppm or more. The NiO content may be controlled to adjust the transmittance depending on the application of the glass of the present invention.

[0081] As ２ O ３ and Sb ２ O ３ is highly toxic and may pollute the environment during the glass manufacturing process and waste glass disposal. ２ O ３ +As ２ O ３ (Sb ２ O ３ and As ２ O ３ The upper limit of the total content in mol % of the elements (amount in mol %) is preferably 20,000 ppm or less, and is preferably 10,000 ppm or less, 7,000 ppm or less, 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 100 ppm or less, 10 ppm or less, 5 ppm or less, 1 ppm or less, and particularly preferably less than 1 ppm.

[0082] The glass of the present invention may further contain, in addition to the above components, SO 4 , only when the desired chemical durability, transmittance, heat resistance, thermal shock resistance, etc. of the glass can be obtained. ３ , Cl ２ , Ta ２ O ５ , Nb ２ O ５ , RfO ２ The total content of these components may be up to 10%. However, since raw material batches of the above components are expensive and tend to increase production costs, they may not be added unless there are special circumstances. The total content of these components is preferably 5% or less, and is preferably 4% or less, 3% or less, 2% or less, 1% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, 0.05% or less, 0.049% or less, 0.048% or less, 0.047% or less, 0.046% or less, and particularly preferably 0.045% or less.

[0083] The glass of the present invention may further contain, in addition to the above components, for example, H only when the desired chemical durability, transmittance, heat resistance, thermal shock resistance, etc. of the glass can be obtained. ２ , CO ２ , CO, H ２ O, He, Ne, Ar, N ２ It may contain trace components such as the above up to 0.1% each.

[0084] Furthermore, intentional addition of Ag, Au, Pd, Ir, Sc, Pm, Gd, Ac, Th, Pa, U, etc. increases raw material costs, resulting in increased manufacturing costs. However, Pd and other elements have various catalytic effects, and their inclusion can impart unique functions to glass. In light of these circumstances, when the purpose is to promote crystallization or to impart other functions, the above components may be contained in an amount of 1% or less, 0.5% or less, 0.3% or less, or 0.1% or less, respectively. When such a purpose is not particularly desired, the amount is preferably 500 ppm or less, more preferably 300 ppm or less, 100 ppm or less, and particularly preferably 10 ppm or less.

[0085] The glass of the present invention may be glass-ceramic. In this case, the content ranges of each component are the same as those described above. The crystal species in the glass-ceramic may be Al.２ SiO ５ , ZrO ２ etc.

[0086] The glass of the present invention having the above composition is likely to achieve a low linear expansion coefficient, excellent laser oscillation characteristics, and excellent laser amplification characteristics.

[0087] When the glass of the present invention is a crystallized glass, the glass having the above composition also makes it easier to achieve a low linear expansion coefficient, excellent laser oscillation characteristics, and laser amplification characteristics.

[0088] In the glass of the present invention, the upper density limit is 3.50 g / cm ３ Preferably, it is 3.40 g / cm or less. ３ Below, 3.35g / cm ３ Below, 3.30g / cm ３ Below, especially 3.25 g / cm ３ If the density is too low, the gas permeability of the glass increases, and there is a risk that the glass may be contaminated during long-term storage. On the other hand, the lower limit of the density is 2.20 g / cm ３ It is preferable that the density is 2.30 g / cm or more. ３ Above, 2.40g / cm ３ Above, 2.50g / cm ３ or more, especially 2.55 g / cm ３ If the density is too high, the weight per unit area increases, making it difficult to handle.

[0089] In the glass of the present invention, the upper limit of the coefficient of linear thermal expansion at 30 to 380°C is 60 × 10 －７ / °C or less, and －７ / ℃ or less, 52 × 10 －７ / ℃ or less, 48 ​​x 10 －７ / ℃ or less, 44 x 10 －７ / ℃ or less, 40 x 10 －７ / ℃ or less, 36 x 10 －７ / ℃ or less, 34 × 10 －７ / ℃ or less, 32 × 10 －７ / ℃ or less, 29.5 × 10 －７ / ℃ or less, 27.5 × 10 －７ / ℃ or less, 25.5 × 10－７ / ℃ or less, 23.5 × 10 －７ / ℃ or less, 23.0 × 10 －７ / ℃ or less, 22.5 × 10 －７ / °C or less, especially 22.0 x 10 －７ / °C or less. If the linear thermal expansion coefficient is too high, the heat resistance and thermal shock resistance are low, making it difficult to use when the glass is exposed to high temperatures. In addition, it becomes difficult to apply to applications requiring positional stability. In particular, when use in laser medium applications is envisaged, a low linear thermal expansion coefficient is preferred to avoid breakage due to heat or strain. On the other hand, although there is no particular lower limit for the linear thermal expansion coefficient, in reality, the linear thermal expansion coefficient at 30 to 380°C should be -70 x 10 －７ / °C or higher.

[0090] In the glass of the present invention, the temperature at which the slope of the thermal expansion curve of the glass changes is treated as the glass transition point (glass transition temperature). In the glass of the present invention, the upper limit of the glass transition point is preferably 670°C or higher, and is preferably 672°C or higher, 674°C or higher, 676°C or higher, 678°C or higher, 680°C or higher, 682°C or higher, 684°C or higher, 686°C or higher, 688°C or higher, and particularly preferably 690°C or higher. If the glass transition point is too low, the glass will flow too much, making it difficult to mold into a desired shape. Furthermore, if the glass transition point is too low, the glass will be prone to deformation when used at high temperatures.

[0091] In the glass of the present invention, the temperature at which the slope of the thermal expansion curve of the glass changes at temperatures equal to or higher than the glass transition point is regarded as the sag point. The upper limit of the sag point of the glass of the present invention is preferably 730°C or higher, more preferably 732°C or higher, 734°C or higher, 738°C or higher, 742°C or higher, 744°C or higher, 746°C or higher, 748°C or higher, and particularly preferably 750°C or higher. If the sag point is too low, the glass will flow too much, making it difficult to mold into a desired shape. Furthermore, the glass will be prone to deformation when used at high temperatures.

[0092] In the glass of the present invention, when high transmittance in the infrared region is required, the lower limit of the transmittance at a thickness of 1 mm and a wavelength of 1200 nm is preferably 0.1% or more, and is preferably 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 81% or more, 83% or more, 85% or more, 86% or more, 87% or more, and particularly preferably 88% or more. On the other hand, when low transmittance in the infrared region is required, the upper limit of the transmittance at a thickness of 1 mm and a wavelength of 1200 nm is preferably 50% or less, and is preferably 40% or less, 30% or less, 20% or less, 10% or less, 8% or less, 6% or less, 4% or less, 3% or less, 2% or less, and particularly preferably 1% or less. Note that the suitable transmittance is not limited to the specific numerical ranges described above.

[0093] In the glass of the present invention, when high transmittance in the near-infrared region is required, the lower limit of the transmittance at a thickness of 1 mm and a wavelength of 800 nm is preferably 0.1% or more, and is preferably 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 82% or more, 84% or more, 85% or more, 86% or more, 87% or more, and particularly preferably 88% or more. On the other hand, when low transmittance in the near-infrared region is required, the upper limit of the transmittance at a thickness of 1 mm and a wavelength of 800 nm is preferably 50% or less, and is preferably 40% or less, 30% or less, 20% or less, 10% or less, 8% or less, 6% or less, 4% or less, 3% or less, 2% or less, and particularly preferably 1% or less. Note that suitable transmittances are not limited to the specific numerical ranges described above.

[0094] In the glass of the present invention, when high transmittance in the visible range is required, the lower limit of the transmittance at a thickness of 1 mm and a wavelength of 555 nm is preferably 0.1% or more, and is preferably 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 82% or more, 84% or more, 85% or more, 86% or more, 87% or more, and particularly preferably 88% or more. On the other hand, when low transmittance in the visible range is required, the upper limit of the transmittance at a thickness of 1 mm and a wavelength of 555 nm is preferably 50% or less, and is preferably 40% or less, 30% or less, 20% or less, 10% or less, 8% or less, 6% or less, 4% or less, 3% or less, 2% or less, and particularly preferably 1% or less. Note that suitable transmittances are not limited to the specific numerical ranges described above.

[0095] In the glass of the present invention, when high transmittance is required in the UV-A ultraviolet region, the lower limit of the transmittance at a thickness of 1 mm and a wavelength of 380 nm is preferably 0.1% or more, and is preferably 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 36% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 82% or more, 83% or more, and particularly 84% or more. If the transmittance at a wavelength of 380 nm is too low, the glass will be colored yellow, making it difficult to achieve the desired colorless transparency. On the other hand, when low transmittance is required in the UV-A ultraviolet region, the upper limit of the transmittance at a thickness of 1 mm and a wavelength of 380 nm is preferably 50% or less, and is preferably 40% or less, 30% or less, 20% or less, 10% or less, 4% or less, 3% or less, 2% or less, and particularly 1% or less. Note that suitable transmittances are not limited to the specific numerical ranges described above.

[0096] In the glass of the present invention, when high transmittance in the UV-B ultraviolet region is required, the lower limit of the transmittance at a thickness of 1 mm and a wavelength of 300 nm is preferably 0.1% or more, and is preferably 1% or more, 5% or more, 10% or more, 20% or more, 24% or more, 28% or more, 30% or more, 40% or more, 43% or more, 44% or more, and particularly 45% or more. On the other hand, when low transmittance in the UV-B ultraviolet region is required, the upper limit of the transmittance at a thickness of 1 mm and a wavelength of 300 nm is preferably 50% or less, and is preferably 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, 4% or less, 3% or less, 2% or less, and particularly 1% or less. Note that suitable transmittances are not limited to the specific numerical ranges described above.

[0097] The glass of the present invention preferably has a haze at a thickness of 1 mm of 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, 0.5% or less, 0.3% or less, 0.2% or less, 0.1% or less, 0.05% or less, 0.01% or less, 0.005%, and particularly preferably 0.001% or less. The haze can be measured in accordance with JIS K7136 using a haze meter (NDH 8000SP manufactured by Nippon Denshoku Industries Co., Ltd.) or the like.

[0098] In the glass of the present invention, when the end face 11 is a circular rod-like shape as shown in FIG. 1 , the upper limit of the diameter of the end face 11 is preferably 100 mm or less, and more preferably 80 mm or less, 60 mm or less, 40 mm or less, 30 mm or less, 20 mm or less, and particularly preferably 10 mm or less. When the diameter of the end face 11 is equal to or less than the above upper limit, it is easy to form a homogeneous glass and improve the yield. On the other hand, the lower limit of the diameter of the end face 11 is preferably 0.1 mm or more, and more preferably 0.5 mm or more, 1 mm or more, 3 mm or more, and particularly preferably 5 mm or more. When the diameter of the end face 11 is equal to or greater than the above lower limit, the glass of the present invention can be used as a laser medium for oscillating a large-diameter laser. Furthermore, the laser excitation density can be reduced, making it easier to avoid damage to the laser medium. While the figure shows a cylindrical shape for convenience, the shape is not limited thereto, and shapes such as an approximately cylindrical, approximately elliptical cylinder, or approximately rectangular parallelepiped may also be used. The schematic diagrams of the approximately cylindrical and elliptical cylindrical shapes are the same as those in Fig. 1. The schematic diagram of the approximately rectangular parallelepiped shape is shown in Fig. 2. In either case, the circle-equivalent diameter is regarded as the above-mentioned diameter value.

[0099] The upper limit of the length of the glass of the present invention is preferably 400 mm or less, and more preferably 350 mm or less, 300 mm or less, 250 mm or less, 200 mm or less, 150 mm or less, and particularly preferably 100 mm or less. When the glass length is less than the above upper limit, it is easy to form a homogeneous glass and improve the yield. Furthermore, when used in laser applications, it is easy to ignore the effects of thermal expansion. On the other hand, the lower limit of the glass length is preferably 1 mm or more, and more preferably 5 mm or more, 10 mm or more, 30 mm or more, and particularly preferably 50 mm or more. When the glass length is greater than the above lower limit, it is easy to improve the cooling efficiency when used in laser applications, and it is easy to extend the usable period of the glass. Furthermore, since the laser optical path length can be increased, it is easy to oscillate a high-output laser power.

[0100] In the glass of the present invention, the upper limit of the arithmetic mean roughness (Ra) of the end face 11 is preferably 200.00 nm or less, and is preferably 100.00 nm or less, 50.00 nm or less, 25.00 nm or less, 10.00 nm or less, 5.00 nm or less, 4.00 nm or less, 3.00 nm or less, 2.00 nm or less, and particularly preferably 1.00 nm or less. When the arithmetic mean roughness of the end face 11 is below the above upper limit, incident light is less likely to be scattered, and the amount of incident light entering the glass increases, making it easier to improve the emission intensity. In addition, emitted light is less likely to be scattered, making it easier to obtain high-output laser power. The lower limit of the arithmetic mean roughness of the end face 11 is preferably 0.01 nm or more, and is preferably 0.05 nm or more, and particularly preferably 0.10 nm or more. When the arithmetic mean roughness of the end face 11 is above the above lower limit, it is easier to reduce manufacturing costs.

[0101] In the glass of the present invention, the upper limit of the arithmetic mean roughness (Ra) of the side surface 12 is preferably 200.00 nm or less, and more preferably 100.00 nm or less, 50.00 nm or less, 10.00 nm or less, 5.00 nm or less, 1.00 nm or less, and particularly preferably 0.50 nm or less. When the arithmetic mean roughness of the side surface 12 is below the above upper limit, excitation light incident from the side surface 12 is less likely to be attenuated. Furthermore, when total reflection of laser light at the side surface 12 is utilized inside the laser medium, the amount of laser light leaking out of the laser medium during total reflection can be suppressed, making it easier to obtain high-power laser light. The lower limit of the arithmetic mean roughness of the side surface 12 is preferably 0.01 nm or more, more preferably 0.05 nm or more, and particularly preferably 0.10 nm or more. When the arithmetic mean roughness of the side surface 12 is above the above lower limit, manufacturing costs are more likely to be reduced.

[0102] When the glass of the present invention is in the form of a plate, the upper limit of the arithmetic mean roughness (Ra) of its end face is preferably 100 nm or less, and more preferably 50 nm or less, 25 nm or less, 15 nm or less, 10 nm or less, 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, and particularly preferably 1 nm or less. If the arithmetic mean roughness of the end face is too large, it becomes difficult for light to enter the glass from the end face of the glass into the glass, and it becomes difficult for light to exit from the inside of the glass to the outside of the glass, making it difficult to obtain glass with the desired high transmittance. In addition, the glass is more likely to break. On the other hand, if the arithmetic mean roughness of the end face is too small, when attempting to physically support the glass at the end face of the glass, the contact area between the glass and the support becomes small, reducing frictional resistance and potentially making it difficult to reliably support the glass. Therefore, the lower limit of the arithmetic mean roughness of the end face of the glass of the present invention is preferably 0.00001 nm or more, more preferably 0.0001 nm or more, 0.001 nm or more, 0.01 nm or more, or 0.1 nm or more.

[0103] The upper limit of the waviness of the glass of the present invention is preferably 10 μm or less, and more preferably 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 0.8 μm or less, 0.7 μm or less, 0.6 μm or less, 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, 0.2 μm or less, 0.1 μm or less, 0.08 μm or less, 0.05 μm or less, 0.03 μm or less, 0.02 μm or less, and particularly preferably 0.01 μm or less. If the waviness is too large, a distribution of the incident angle of light onto the glass surface at a specific position is likely to occur, the amount of light scattering on the glass surface increases on average, and it becomes difficult to obtain glass with the desired high transmittance. On the other hand, the lower limit of the waviness is not particularly limited, but in reality it is 0.01 nm or more.

[0104] The upper limit of the thickness of the glass of the present invention is preferably 30 mm or less, and more preferably 20 mm or less, 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, and particularly preferably 4 mm or less. If the glass thickness is too thick, the attenuation rate of light inside the glass increases, making it difficult to obtain glass with the desired high transmittance. On the other hand, the lower limit of the thickness of the glass of the present invention is preferably 0.1 mm or more, more preferably 0.5 mm or more, and particularly preferably 1 mm or more. If the glass thickness is too thin, sufficient laser amplification cannot be achieved. Furthermore, when the area is large, there is a concern that the glass may deform under its own weight.

[0105] The upper limit of the difference between the maximum thickness and the minimum thickness of the glass of the present invention is preferably 50 μm or less, and is preferably 25 μm or less, 10 μm or less, 5 μm or less, 1 μm or less, 500 nm or less, 300 nm or less, 100 nm or less, 50 nm or less, 25 nm or less, 15 nm or less, 10 nm or less, 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, and particularly preferably 1 nm or less. If the difference between the maximum thickness and the minimum thickness is too large, the angle of incidence of light incident from either the front or back surface will differ from the angle of emergence when emitted from the other surface, which tends to result in undesirable light scattering and a glaring appearance.

[0106] The arithmetic mean roughness (Ra) of the main surface and edge surface of the glass can be measured by a method conforming to JIS B0601:2001. Furthermore, waviness can be measured using a stylus-type surface profiler in accordance with SEMI STD D15-1296 "Method for measuring surface waviness of FPD glass substrates." Thickness can be measured using common devices such as digital calipers or a point-contact roughness meter.

[0107] Generally, when spinodal decomposition (a phase separation pattern in which secondary and subsequent phases exist in an intricate manner within the first phase with the largest volume fraction and are continuously mixed) occurs, irregularities tend to form on the glass surface due to differences in the chemical durability of each phase. After extensive research, the present inventors have discovered that annealing the glass of the present invention at a temperature above its glass transition point can cause phase separation into two or more distinct phases, and have found that in many cases, this phase separation results in binodal decomposition (a phase separation pattern in which secondary and subsequent phases are scattered within the first phase with the largest volume fraction and are mixed in spherical or other shapes). Furthermore, they have found that by appropriately controlling the glass composition, annealing conditions, and the like, phase separation due to binodal decomposition can be optionally manifested, resulting in a glass surface with a desired transmittance. For these reasons, the glass of the present invention may be composed of only a single glass phase or may contain two or more phases. The secondary and subsequent phases may be in a glassy, ​​crystalline, gaseous, or liquid state. The second and subsequent phases may be composed of metal oxides, metals, organic substances, etc., and their compositions are not limited. The shapes of the second and subsequent phases are preferably sheet-like, granular, spherical, circular, elliptical, linear, etc., and may be any of these shapes alone or in combination. The state of phase separation can be determined by measuring the surface shape using a scanning electron microscope (SEM) or atomic force microscope (AFM) after etching with a liquid such as hydrofluoric acid. It is also possible to confirm the chemical bonding state in a sample using FT-IR spectroscopy or Raman spectroscopy, and obtain information about phase separation nondestructively. The phase separation state described in this specification can be determined by methods readily conceivable by those skilled in the art.

[0108] The upper limit of the size of the second and subsequent phases is preferably 100 μm or less at the longest part, and is preferably 50 μm or less, 30 μm or less, 10 μm or less, 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 0.5 μm or less, 0.3 μm or less, 0.2 μm or less, and particularly preferably 0.1 μm or less. If the longest part of the second and subsequent phases is too long, the surface roughness of the glass increases, making it difficult to obtain glass with the desired high transmittance. Note that there is no particular limitation on the lower limit of the size of the longest part of each of the second and subsequent phases, but in practice it is 0.01 nm or more.

[0109] When the second and subsequent phases are crystalline, the crystal system is preferably one of hexagonal, trigonal, cubic, tetragonal, orthorhombic, or monoclinic. The crystal system may be triclinic, but in this case, birefringence is likely to occur within the crystal, resulting in light scattering and making it difficult to obtain glass with the desired high transmittance. When the crystal system is triclinic, the composition of the first phase must be designed so that the refractive index difference between the crystal and the first phase is small.

[0110] When the glass of the present invention contains two or more phases, if the difference in refractive index between the first phase and the second or subsequent phases is large, light will be scattered at the boundaries between the phases, making it difficult to obtain a glass with the desired high transmittance. The upper limit of the difference in refractive index between the phases is 1.5 or less at each of the typical wavelengths used in refractive index measurement: nd (587.6 nm), nC (656.3 nm), nF (486.1 nm), ne (546.1 nm), ng (435.8 nm), nh (404.7 nm), ni (365.0 nm), nF' (480.0 nm), n785 (785 nm), n1310 (1310 nm), and n1550 (1550 nm). Preferably, the refractive index is within 1.3, 1.1, 0.9, 0.7, 0.5, 0.3, 0.1, 0.09, 0.07, 0.05, 0.03, 0.01, 0.008, 0.006, 0.004, 0.002, 0.0009, 0.0007, 0.0005, 0.0003, 0.0002, and particularly preferably within 0.0001. The refractive index of each phase can be measured according to the following procedure. First, the refractive index of the glass is measured, and the obtained value is used as nｍ Next, at least one phase is removed by etching or the like to obtain sample A. A hydrofluoric acid solution or the like can be used for etching. The refractive index of sample A is measured and the obtained value is taken as n Ａ The weight before etching is W ｍ , the weight after etching is W Ａ When the refractive index of the removed phase 1 is １ is calculated using the following formula: １ = {n ｍ -n Ａ (W Ａ / W ｍ )×{W ｍ / (W ｍ -W Ａ The refractive index can be measured using a precision refractometer (KPR-2000 manufactured by Shimadzu Corporation) or the like.

[0111] The upper limit of the refractive index nd (587.6 nm) of the glass of the present invention is preferably 2.50 or less, and more preferably 2.40 or less, 2.20 or less, 2.00 or less, 1.80 or less, 1.70 or less, 1.60 or less, 1.58 or less, 1.55 or less, 1.54 or less, and particularly preferably 1.53 or less. If the refractive index of the glass is too high, light may be scattered at the surface or end face, making it difficult to obtain a glass with the desired high transmittance. On the other hand, the lower limit of the refractive index nd of the glass of the present invention is preferably 1.20 or more, and more preferably 1.25 or more, 1.30 or more, 1.35 or more, 1.38 or more, 1.40 or more, 1.42 or more, and particularly preferably 1.43 or more. If the refractive index is too low, the difference in refractive index between the glass of the present invention and air becomes small, making it difficult to visually recognize the glass of the present invention and potentially making it difficult to handle during production.

[0112] The glass of the present invention preferably has an unpolished surface. The theoretical strength of glass is inherently very high, but it often breaks even at stresses far lower than the theoretical strength. This is because nano-scale defects called Griffith flows occur on the glass surface during processes after glass molding, such as a polishing process. Therefore, if the surface of the glass of the present invention is unpolished, the inherent mechanical strength is less likely to be impaired, and the glass is less likely to break. Furthermore, the polishing process can be omitted, thereby reducing manufacturing costs. For example, when the glass of the present invention is in a plate shape, the glass of the present invention becomes even more resistant to breakage if the entire effective surfaces of both main faces are unpolished. Furthermore, in order to make the entire effective surface an unpolished surface, it is effective to make the portion corresponding to the effective surface a free surface at the time of molding. Furthermore, even if the portion corresponding to the effective surface comes into contact with a solid member or the like during molding, a smooth surface similar to a free surface can be created by reheating the portion that came into contact with the solid member or the like after molding at a temperature above the glass transition point.

[0113] The glass of the present invention preferably has high water resistance, which is a typical chemical durability. Specifically, when the amount of alkali elution is measured by a method in accordance with JIS R3502 (1995), the amount of Li ２ O, Na ２ O.K. ２ The upper limit of the amount of O elution is preferably 2 mg or less, and more preferably 1.8 mg or less, 1.6 mg or less, 1.4 mg or less, 1.2 mg or less, 1.0 mg or less, 0.8 mg or less, 0.6 mg or less, 0.4 mg or less, 0.2 mg or less, 0.1 mg or less, 0.005 mg or less, and particularly preferably 0.003 mg or less. If the water resistance is low, ion exchange between alkali metals and protons or the like on the glass surface is likely to proceed, and the parts where ion exchange has progressed are altered, making them more susceptible to cracking and the like.

[0114] The glass of the present invention may be subjected to chemical strengthening or the like. The conditions for chemical strengthening treatment may be appropriately selected by taking into consideration the glass composition, the volume fraction of each phase, the type of molten salt, etc., and the treatment time and treatment temperature. For example, in order to facilitate chemical strengthening, Na, which may be contained in the remaining glass phase, may be added. ２A glass composition containing a large amount of O may be selected. The molten salt may contain monovalent cations such as Li, Na, and K, or divalent cations such as Mg, Ca, Sr, Ba, and Zn, either singly or in combination. Furthermore, in addition to the usual single-stage strengthening, multi-stage chemical strengthening may be selected. Examples of molten salts that can be used include nitrates (potassium nitrate, sodium nitrate, lithium nitrate, etc.), carbonates (potassium carbonate, sodium carbonate, lithium carbonate, etc.), sulfates (potassium sulfate, sodium sulfate, lithium sulfate, etc.), chlorides (potassium chloride, sodium chloride, lithium chloride, etc.), and combinations thereof. Nitrates with low melting points are preferred, with sodium nitrate being particularly preferred. The ion exchange temperature is preferably 330 to 550°C, 350 to 500°C, and particularly 390 to 450°C. The ion exchange time is preferably 30 minutes to 12 hours, or 45 minutes to 10 hours. The above strengthening conditions may be changed as desired depending on the required application and strength, and the preferred conditions are not necessarily limited to those described above.

[0115] When compressive stress is imparted to the glass of the present invention by chemical strengthening or the like, the lower limit of the compressive stress value (CS) of the glass is preferably 50 MPa or more, more preferably 100 MPa or more, 150 MPa or more, 200 MPa or more, 230 MPa or more, 260 MPa or more, and particularly preferably 300 MPa or more. If the compressive stress value of the glass is too small, there is a risk that the Vickers hardness and bending strength will be low.

[0116] When compressive stress is applied to the glass of the present invention by chemical strengthening or the like, the lower limit of the compressive stress depth (DOC) of the glass is preferably 10 μm or more, more preferably 50 μm or more, 100 μm or more, 110 μm or more, particularly preferably 120 μm or more. If the compressive stress depth of the glass is too small, there is a risk that the fracture strength will be low. The compressive stress value (CS) and the compressive stress depth (DOC) can be measured using a scattered light photoelastic stress meter SLP-1000 (manufactured by Orihara Seisakusho Co., Ltd.) and a surface stress meter FSM-6000 (manufactured by Orihara Seisakusho Co., Ltd.).

[0117] In the glass of the present invention, the lower limit of the scratch four-point bending strength is preferably 150 MPa or more, more preferably 200 MPa or more, 235 MPa or more, 245 MPa or more, and particularly preferably 250 MPa or more. If the scratch four-point bending strength is too low, when used as a cover glass for a smartphone, etc., it is prone to breaking when dropped. On the other hand, the upper limit of the scratch four-point bending strength is not particularly limited, but in reality it is 1500 MPa or less. The scratch four-point bending strength can be measured by the following procedure. First, a glass plate processed to 50 mm x 50 mm x 0.6 mm thick is placed vertically, and 1.5 mm thick SUS plates are placed on the main surface and the opposite surface of the glass plate to fix the glass plate. The tip of a pendulum-shaped arm is collided with the glass plate through P180 grit sandpaper to cause scratching. The tip of the arm is an iron cylinder with a diameter of 5 mm, and the arm weighs 550 g. The arm is swung down to a height of 5 mm from the impact point. The four-point bending strength of the damaged glass plate is measured.

[0118] When evaluating Vickers hardness, first, each sample is placed on the stage of a Vickers hardness tester in a thermo-hygrostat maintained at 30% humidity and 25°C, and a Vickers indenter (a diamond indenter shaped like a diamond) is pressed against the glass surface (optically polished surface) for 15 seconds at various loads. Next, the number of cracks generated from the four corners of the indentation is counted within 15 seconds after unloading, and the ratio to the maximum number of cracks (4) is calculated as the crack occurrence rate. This crack occurrence rate is calculated by averaging 20 measurements under the same load. Finally, the load at which the crack occurrence rate reaches 50% is taken as the crack resistance value, and crack resistance values ​​of 140 gf or more are evaluated as "○", and crack resistance values ​​of less than 140 gf are evaluated as "×".

[0119] When evaluating Young's modulus and rigidity modulus, a plate-shaped sample (40 mm x 20 mm x 20 mm) whose surface has been polished with a polishing solution containing dispersed No. 1200 alumina powder is measured at room temperature using a free resonance type elastic modulus measuring device (JE-RT3 manufactured by Nippon Technoplus).

[0120] When the glass of the present invention is crystallized glass, it is preferable that it has the same properties as those described above.

[0121] The shape of the glass of the present invention is usually a plate or rod, but is not limited thereto and may be appropriately selected depending on the application. For example, it may be a spherical, lens, or slab shape, and the direction of emitted light may be controlled by these shapes.

[0122] The glass of the present invention can also be suitably used as an optical element in an optical device. Figure 3 shows a schematic diagram illustrating an example of the configuration of a laser oscillator using the glass according to this embodiment. The laser oscillator 2 comprises an excitation light source 20, resonators 22 and 24, and a wavelength conversion member 26. The wavelength conversion member 26, made of the glass according to this embodiment, is disposed between the resonators 22 and 24, which are arranged parallel to each other. The resonator 22 is designed to transmit excitation light L and totally reflect the wavelength-converted light, while the resonator 24 is designed to transmit a portion of the wavelength-converted light. The wavelength conversion member 26 is made of the glass according to this embodiment, and its surface (end face 11) parallel to the resonators 22 and 24 is mirror-polished. The wavelength-converted light generated by irradiating excitation light L from the excitation light source 20 onto the wavelength conversion member 26 is amplified by traveling back and forth between the resonators 22 and 24 and the wavelength conversion member 26. Then, a part of the wavelength-converted light generated by the wavelength converting member 26 passes through the resonator 24 and is extracted to the outside as laser light. The excitation light source 20 may be, for example, a solid-state laser or a semiconductor laser.

[0123] The optical elements and optical devices using the glass composition according to this embodiment are not limited to the laser oscillation devices described above, but can be used in a variety of devices.

[0124] Next, the method for producing the glass of the present invention will be described.

[0125] The method for producing glass of the present invention includes a step of melting glass raw materials to obtain molten glass, and a step of shaping the molten glass.

[0126] Specifically, in the step of melting glass raw materials to obtain molten glass, first, a raw material batch (glass raw materials) prepared to obtain glass of the above composition is charged into a glass melting furnace and melted at 1200 to 1800° C. to obtain molten glass. When melting glass, any one of the following melting methods may be used, or two or more of them may be combined: a flame melting method using a burner or the like, an electric melting method using electrical heating, a melting method using laser irradiation, and a melting method using plasma.

[0127] In the step of forming the molten glass, the obtained molten glass is formed to obtain glass. Forming methods in this step include the overflow method, float method, down-draw method, slot-down method, containerless method, blow method, press method, roll method, bushing method, and tube drawing method. After forming, the glass may be reheated to a temperature equal to or higher than the glass transition point. In this way, the glass of the present invention having good surface quality can be produced.

[0128] When forming by the overflow method, the viscosity of the glass at the bottom end of the trough-shaped refractory is 10 ３．５ ~10 ５．０ dPa·s is preferred. If no force is applied to the lower apex portion of the trough-shaped structure, the glass will fall downward while shrinking due to surface tension. To prevent this, it is necessary to pinch both sides of the glass material with rollers and stretch it in the width direction so that the glass material does not shrink. When forming the glass of the present invention, since the heat quantity of the glass itself is small, the cooling rate of the glass increases rapidly the moment it leaves the trough-shaped refractory. Therefore, the viscosity of the glass at the lower apex portion of the trough-shaped refractory is preferably 10 ５．０ dPa・s or less, 10 ４．８ dPa・s or less, 10 ４．６ dPa・s or less, 10 ４．４ dPa・s or less, 10 ４．２ dPa·s or less, especially 10 ４．０ In this way, when a tensile stress is applied in the width direction, it becomes possible to increase the plate width while preventing breakage, and it becomes possible to stably stretch the plate downward.

[0129] Next, the obtained glass is annealed. The purpose of annealing is mainly to remove distortion and residual stress. In this case, it is preferable to heat treat the glass by staying in a temperature range near the strain point (≈glass transition point -5 to -20°C) for at least 1 minute, more preferably 3 minutes or more, 16 minutes or more, and most preferably more than 30 minutes. This makes it easier to obtain glass composed of only a single glass phase, resulting in increased chemical durability of the glass, making it easier to control the glass surface as desired, and making it easier to obtain glass with a desired high transmittance. On the other hand, annealing may also form phase separation in the glass in addition to removing distortion and residual stress. In this case, it is preferable to heat treat the glass by staying in a temperature range higher than the strain point for at least 1 minute, more preferably 3 minutes or more, 16 minutes or more, and most preferably more than 30 minutes. This allows the glass to undergo phase separation, and in many cases, the phase separation state becomes binodal decomposition. Note that when the glass of the present invention is phase separated, SiO ２ The glass is divided into a first phase rich in α- and other secondary and subsequent phases, but the chemical durability of the secondary and subsequent phases is often lower than that of the first phase. In such cases, unevenness is likely to occur on the glass surface due to differences in the chemical durability of each phase. However, by designing the glass to the preferred composition described above, the unevenness can be suppressed to a level that allows the desired transmittance to be obtained. Furthermore, imparting fine unevenness can improve the releasability of the glass of the present invention from objects that come into contact with the glass. In addition, increasing the surface area of ​​the glass surface compared to the free surface state can increase frictional force and physical and chemical adsorption, leading to higher functionality of the glass of the present invention. Annealing may also be performed while applying or irradiating sound waves or electromagnetic waves.

[0130] Furthermore, the cooling rate when cooling the glass of the present invention after heating to a high temperature may be a specific temperature gradient, or may be two or more levels of temperature gradient. To obtain sufficient thermal shock resistance, it is desirable to control the cooling rate to sufficiently relax the structure of the remaining glass phase. In this case, the average cooling rate from the maximum annealing temperature to 25°C is preferably 3000°C / min or less, 1000°C / min or less, 500°C / min or less, 400°C / min or less, 300°C / min or less, 200°C / min or less, 100°C / min or less, 50°C / min or less, 25°C / min or less, 10°C / min or less, and particularly preferably 5°C / min or less, in the inner part of the glass farthest from the surface of the glass of the present invention. Furthermore, to obtain long-term dimensional stability, it is more preferably 2.5°C / min or less, 1°C / min or less, 0.5°C / min or less, 0.1°C / min or less, 0.05°C / min or less, and particularly preferably 0.01°C / min or less. Except when physical tempering treatments such as air cooling or water cooling are performed, it is desirable that the cooling rate of the glass surface is close to the cooling rate of the inner wall, farthest from the glass surface. The value obtained by dividing the cooling rate of the inner part of the glass farthest from the surface by the cooling rate of the surface is preferably 0.0001 to 1, 0.001 to 1, 0.01 to 1, 0.1 to 1, 0.5 to 1, 0.8 to 1, or 0.9 to 1, and particularly 1. A value close to 1 makes it difficult for residual strain to occur at all positions in the glass of the present invention, making it easier to achieve long-term dimensional stability. The cooling rate of the surface can be estimated using a contact thermometer or a radiation thermometer. The temperature inside the glass can be estimated from the numerical data obtained by immersing the glass at a high temperature in a cooling medium and measuring the heat quantity and rate of heat change of the cooling medium, as well as the specific heat and thermal conductivity of the glass and the cooling medium.

[0131] The glass of the present invention thus obtained may be cut. For example, when cutting using a wire saw, it is preferable to cut the glass while supplying a slurry containing abrasive grains to the wire saw.

[0132] The method may include a step of crystallizing the glass obtained in the step of forming the molten glass by heat treatment.

[0133] Specifically, crystallized glass can be obtained by heat-treating the annealed glass to crystallize it. The crystallization conditions are as follows. First, nucleation is performed at 700°C to 1200°C (preferably 750°C to 900°C) for 0.1 to 60 hours (preferably 0.25 to 50 hours, more preferably 1 to 40 hours), followed by crystal growth at 800°C to 1300°C (preferably 850°C to 1100°C) for 0.1 to 50 hours (preferably 0.2 to 10 hours, more preferably 0.25 to 5 hours). The heat treatments in each of the nucleation and crystal growth steps may be performed only at a specific temperature, or may be held at two or more temperatures and heat-treated stepwise, or may be heated while applying a temperature gradient. Alternatively, only the heat treatment for crystal growth may be performed without nucleation. By doing so, for example, crystallized glass can be obtained in which the following crystals are precipitated. Specifically, Al ２ SiO ５ (aluminum silicate), zirconia, zirconia titanate, tin-containing zirconia-based oxide, titania, aluminotitanate, β-quartz solid solution, α-quartz, β-quartz, β-spodumene solid solution, spodumene, zircon, cordierite, enstatite, mica, nepheline, anorthite, lithium disilicate, lithium metasilicate, wollastonite, diopsite, cristobalite, tridymite, feldspar, spinel-based crystals, metal colloids, etc. Only one type of these crystals may be contained, or two or more types may be contained.

[0134] In addition, crystals can be precipitated by annealing, and crystallization can be promoted by applying or irradiating sound waves or electromagnetic waves.Furthermore, the cooling rate when cooling the crystallized glass of the present invention that has been heated to a high temperature can be a specific temperature gradient, or can be two or more levels of temperature gradient.The cooling rate is preferably the same as the cooling rate of the above-mentioned glass.

[0135] The precipitated crystals can be evaluated using an X-ray diffractometer (Rigaku Smart Lab, fully automated multipurpose horizontal X-ray diffractometer). The scan mode is 2θ / θ measurement, the scan type is continuous scan, the scattering and divergence slit width is 1°, the receiving slit width is 0.2°, the measurement range is 10-60°, the measurement step is 0.1°, and the scan speed is 5° / min. The main crystals and crystal grain size can be evaluated using the analysis software installed in the same model package. The average crystallite size of the main crystals can be calculated using the measured X-ray diffraction peaks based on the Debye-Scherrer method. In the measurement for calculating the average crystallite size, the scan speed is 1° / min.

[0136] The present invention will now be described based on examples, but the present invention is not limited to the following examples. Tables 1 to 6 show the compositions and characteristic values ​​of glasses according to the examples of the present invention (Example Nos. 1 to 23) and a comparative glass (Comparative No. 24).

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143] First, each raw material was mixed in the form of oxide, hydroxide, carbonate, nitrate, etc. to obtain a glass batch having the composition shown in each table. The obtained glass batch was melted at 1200 to 1800°C for 0.5 to 400 hours, and the obtained molten glass was rolled by a roll method while cooling and formed into a glass having a width of 100 mm and a thickness of 5 mm. Subsequently, the glass was heat-treated in an annealing furnace at the glass transition point of -150 to -50°C for 30 minutes, and the temperature of the annealing furnace was lowered to room temperature at a rate of -100°C / h to obtain a glass having the composition shown in each table.

[0144] The obtained glass was processed by physical polishing, chemical polishing, chemical etching, fire blasting, etc. to prepare evaluation samples for density, linear thermal expansion coefficient, viscosity, etc., and evaluations were performed. In addition, the above molten glass was formed into a length of 400 mm by the overflow method, and heat-treated in an annealing furnace at the glass transition point of −150 to −50° C. for 30 minutes, and the temperature of the annealing furnace was lowered to room temperature at a rate of −100° C. / h to obtain a glass plate.

[0145] Li in the obtained glass ２ The O content was analyzed using an atomic absorption spectrometer (ContrAA600 manufactured by Analytik Jena). First, the glass was crushed and wetted with pure water, and then melted by adding perchloric acid, nitric acid, sulfuric acid, hydrofluoric acid, etc. Then, the Li content of the melted glass was analyzed. ２ The O content was measured using an atomic absorption spectrometer. ２ Based on the calibration curve prepared using the O solution, the Li content of the melted glass was ２ The O content was determined. Furthermore, other components were measured using an ICP-MS device (Agilent 8800 manufactured by AGILEINT TECHNOLOGY) or an atomic absorption spectrometer. Alternatively, a glass sample with a known concentration previously measured using an ICP-MS device or an atomic absorption spectrometer was used as a calibration curve sample, and a calibration curve was created using an XRF (X-ray fluorescence) analyzer (ZSX Primus 4 manufactured by RIGAKU). Based on the calibration curve, the actual content of each component was determined from the XRF analysis value of the measurement sample. During the XRF analysis, the tube voltage, tube current, exposure time, etc. were adjusted as needed depending on the components being analyzed.

[0146] The density was evaluated by the Archimedes method.

[0147] The linear thermal expansion coefficient was evaluated as the average linear thermal expansion coefficient measured in a temperature range of 30 to 380°C using a sample processed to 20 mm x 3.8 mmφ. A NETZSCH dilatometer was used for the measurement. The same measuring device was also used to measure the thermal expansion curve of the glass sample in a temperature range of 30 to 750°C, and the glass transition point and yield point were evaluated by calculating the inflection point.

[0148] The high-temperature viscosity was evaluated by the platinum ball pulling method as follows. A lump glass sample was crushed to an appropriate size and placed in an alumina crucible. The alumina crucible was then heated to melt the sample, and the viscosity of the glass was measured at multiple temperatures. The constants of the Vogel-Fulcher equation were calculated to create a viscosity curve. The viscosity of each viscosity (10 ４ dPa·s, 10 ３．５ dPa·s, 10 ３ dPa·s, 10 ２．５ dPa·s and 10 ２ The temperature at which the viscosity of the material is 100 dPa·s was calculated.

[0149] Transmittance, brightness, and chromaticity were evaluated using a spectrophotometer with a 1 mm thick sample having a surface roughness equivalent to optical polishing. A JASCO V-670 spectrophotometer was used for the measurements. The V-670 was equipped with an integrating sphere unit, the ISN-723, and the measured transmittance corresponds to total light transmittance. The measurement wavelength range was 200 to 2500 nm, the scan speed was 200 nm / min, the sampling pitch was 1 nm, and the bandwidth was 5 nm in the wavelength range from 200 to 800 nm and 20 nm in other wavelength ranges. Prior to measurement, baseline correction (100% alignment) and dark measurement (0% alignment) were performed. Dark measurement was performed with the barium sulfate plate attached to the ISN-723 removed. Using the measured transmittance, tristimulus values ​​XYZ were calculated based on JIS Z8781-42013 and corresponding international standards, and lightness and chromaticity were calculated from each stimulus value (illuminant C / 10°).

[0150] The color appearance was judged visually.

[0151] Fluorescence was evaluated using an excitation light wavelength of 808 nm and a fluorescence wavelength of 1060 nm. Fluorescence was evaluated as "Good" when fluorescence was observed, and "Poor" when fluorescence was not observed. The excitation light and emission were measured using a fluorescence spectrophotometer. Although 808 nm, which is known as the optical absorption wavelength of Nd, was used as the excitation light in this study, wavelengths other than 808 nm may also be used as the excitation light. Furthermore, although 1060 nm was used as the fluorescence wavelength in this study, fluorescence can actually be emitted at wavelengths other than 1060 nm. Therefore, wavelengths other than 1060 nm may also be used as the fluorescence wavelength for evaluation depending on the application of the present invention.

[0152] The glasses of Examples 1 to 23 of the present invention were materials with a low coefficient of linear thermal expansion and high heat resistance and thermal shock resistance. The color appearance of glasses Nos. 1 to 9 and Nos. 18 to 23 was light blue. Furthermore, glasses Nos. 1 to 23 exhibited fluorescence. The excitation light wavelength was 808 nm, and the fluorescence wavelength was 1060 nm.

[0153] The glass of Comparative Example No. 24 did not contain any rare earth elements and did not exhibit fluorescence.

[0154] The glass of the present invention having a low linear thermal expansion coefficient is preferably used as a laser medium. In addition, when the glass of the present invention having a low linear thermal expansion coefficient is a crystallized glass, it can also be suitably used as a laser medium. However, the applications of the glass of the present invention having a low linear thermal expansion coefficient are not limited to those described above.

[0155] DESCRIPTION OF SYMBOLS 1... Glass 11... End face 12... Side face 2... Laser oscillation device 20... Excitation light source 22... Resonator 24... Resonator 26... Wavelength conversion member

Claims

1. SiO in mole percent ２ 45-85%, Al ２ O ３ 3-23%, B ２ O ３ 0-13%, Li ２ O 0-5%, Ln ２ O ３ (Ln is at least one selected from Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm) 0.01 to 11%.

2. P in mole percent ２ O ５ 2. The glass of claim 1, wherein the glass contains more than 0% of SiO 2 .

3. Fe, in mole percent ２ O ３ 3. The glass of claim 1, wherein the glass contains more than 0% of Cr.

4. In mole percent, Lm ２ O ３ 3. The glass according to claim 1, wherein Lm is at least one element selected from the group consisting of La, Y, and Lu, and the glass contains 0 to 10% of Lm.

5. SnO in mole percent ２ 3. The glass of claim 1, wherein the glass contains more than 0% of Cr.

6. The glass according to claim 1 or 2, characterized in that it contains, by mole percent, 12.5% ​​or less of ZnO.

7. In mole percent, Li ２ O + Na ２ O+K ２ 3. The glass according to claim 1, containing 15% or less of O.

8. In mole percent, (P ２ O ５ ×TiO ２ ) / (Al ２ O ３ +P ２ O ５ 3. The glass according to claim 1, wherein σ is 0.0000016 or more.

9. In mole percent, P ２ O ５ ×TiO ２ 3. The glass according to claim 1, wherein the σ is 0.00002 or more.

10. In mol%, MgO + CaO + SrO + BaO 0 to 6.0%, Li ２ O + Na ２ O+K ２ O 0-2.6%, P ２ O ５ ×TiO ２ 3. The glass according to claim 1, wherein the refractive index is 0.01 or more.

11. The linear thermal expansion coefficient at 30 to 380°C is 60 x 10 －７ 3. The glass according to claim 1, wherein the temperature is 100° C. or less.

12. SiO in mole percent ２ 45-85%, Al ２ O ３ 3-23%, B ２ O ３ 0-13%, Ln ２ O ３ (Ln is at least one selected from Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm) 0.01 to 11%, P ２ O ５ More than 0 to 20%, MgO+CaO+SrO+BaO 0 to 10%, Li ２ O + Na ２ O+K ２ O 0 to 5%, and the linear thermal expansion coefficient at 30 to 380 ° C is 40 × 10 －７ / °C or less.

13. SiO in mole percent ２ 45-85%, Al ２ O ３ 3-23%, B ２ O ３ 0-13%, Ln ２ O ３ (Ln is at least one selected from Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm) 0.01 to 11%, P ２ O ５ Over 0 to 20%, Li ２ O 0-5%, ZrO ２ 0-20%, MgO+CaO+SrO+BaO 0-10%, Li ２ O + Na ２ O+K ２ O 0 to 2.9%, and the molar ratio (MgO + CaO + SrO + BaO) / P ２ O ５ The linear thermal expansion coefficient at 30 to 380°C is 40 x 10 －７ / °C or less.

14. TiO in mole percent ２ 14. The glass of claim 1, 2, 12 or 13, containing more than 0% of ZnO.

15. In mole percent, Ln ２ O ３ (Ln is at least one element selected from Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm) 0.01 to 11% and having a linear thermal expansion coefficient of 5 to 40 × 10 at 30 to 380°C. －７ / °C.

16. The glass according to any one of claims 1, 2, 12, 13 and 15, which is used as a laser medium.

17. A laser oscillator comprising the glass according to any one of claims 1, 2, 12, 13 and 15.

18. A method for producing glass according to any one of claims 1, 2, 12, 13 and 15, comprising the steps of melting glass raw materials to obtain molten glass, and shaping the molten glass, wherein in the step of shaping the molten glass, the shaping is carried out by an overflow method, a float method, a downdraw method, a slot-down method, a containerless method, a blowing method, a pressing method, a rolling method, a bushing method or a tube drawing method.

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