JP6792566B2 - Optical glass, optics, and optics - Google Patents

Description

The present invention relates to optical glass, optical elements, and optical devices. The present invention claims the priority of application number 2015-251260 of the Japanese patent filed on December 24, 2015, and for designated countries where weaving is permitted by reference to the literature, the contents described in the application. Is incorporated into this application by reference.

In recent years, imaging devices and the like equipped with an image sensor having a high number of pixels have been developed, and high resolution is required for the optical system used for these. As an optical glass that can be used in such an optical system, for example, Patent Document 1 discloses an optical glass having a refractive index of 1.72 to 1.86 and an Abbe number of 35 to 50.

JP-A-2002-012443

As the optical glass used in the optical system, one having a high refractive index and a low dispersion is desired. It is also desired to improve the transmittance and reduce the manufacturing cost of the optical glass having a high refractive index and low dispersion. The present invention has been made in view of such circumstances, and an object of the present invention is to provide an optical glass having a high refractive index, low dispersion, good transmittance, and low cost.

A first aspect of the present invention for solving the above _{problems, SiO 2 5~9%, B 2} O 3 12~15%, La 2 O 3 50~54%, Gd 2 O 3 1~9% , Nb ₂ O ₅ 4 to 8%, TiO ₂ 3 to 8%, WO ₃ 0.5 to 4%, ZrO ₂ 3 to 7%, and substantially no ZnO. It is glass.

A second aspect of the present invention is an optical element comprising the optical glass of the first aspect.

A third aspect of the present invention is an optical device including the optical element of the second aspect.

It is a perspective view of the image pickup apparatus provided with the optical element using the optical glass which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention (hereinafter, referred to as “the present embodiment”) will be described. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of the gist thereof. Unless otherwise specified in the present specification, the content of each component shall be the mass% of the total mass of the glass in the oxide conversion composition. The oxide-equivalent composition described here is the total of the oxides, assuming that the oxides, composite salts, etc. used as raw materials for the glass constituents of the present invention are all decomposed into oxides at the time of melting. It is a composition in which each component contained in a glass is described, with the mass being 100% by mass.

The optical glass according to the present embodiment, in _{mass%, SiO 2 5~9%, B} 2 O 3 12~15%, La 2 O 3 50~54%, Gd 2 O 3 1~9%, Nb 2 O It is an optical glass containing ₅ 4 to 8%, TiO ₂ 3 to 8%, WO ₃ 0.5 to 4%, and ZrO ₂ 3 to 7%, and substantially no ZnO. In addition, in this specification, "substantially not contained" means that the component is not contained as a component affecting the characteristics of the glass composition in excess of the concentration unavoidably contained as an impurity. means. For example, it is assumed that contamination of about 100 ppm or less in the manufacturing process is substantially not contained.

The optical glass according to the present embodiment is an optical glass having a high refractive index, low dispersion, good transmittance, and low cost. With conventional optical glass, it was difficult to achieve high refractive index and low dispersion and to improve the transmittance, but the optical glass according to the present embodiment has high refractive index, low dispersion and good transmittance. All of these can be achieved. Further, the optical glass according to the present embodiment is a low-cost optical glass.

Optical glass having a high refractive index tends to suppress the content of SiO ₂ and B ₂ O ₃ that lower the refractive index. On the other hand, when the content of SiO ₂ and B ₂ O ₃ is low, the liquidus temperature (Tl) of the optical glass tends to increase. Therefore, when the glass transition temperature is low, the amount of heat dissipated required for solidification is particularly high. That time will increase. As a result, when the molten glass is cooled and solidified, there is a problem that composition fluctuation due to evaporation of volatile components is induced and veins are likely to occur inside the glass.

However, the optical glass according to the present embodiment can reduce the difference between the glass transition temperature and the liquid phase temperature. The small difference between the glass transition temperature and the liquid phase temperature acts to suppress the generation of veins. As a result, the optical glass according to the present embodiment can suppress the occurrence of veins.

The optical glass according to the present embodiment can achieve high refractive index, low dispersion, and good transmittance without containing a large amount of expensive raw materials. This contributes to the reduction of costs such as raw material costs. Hereinafter, the composition of the optical glass according to the present embodiment will be described.

SiO ₂ is a component that forms a glass skeleton, lowers the liquidus temperature (Tl), and improves chemical durability. The content of SiO ₂ is 5 to 9%, preferably 5 to 8%, and more preferably 6 to 8%. Within this range, it is possible to increase the devitrification resistance and improve the moldability while increasing the refractive index. If the content of SiO ₂ is too small, devitrification tends to occur easily. If the content of SiO ₂ is too large, the refractive index tends to decrease.

B ₂ O ₃ is a component that forms a glass skeleton, lowers the liquidus temperature (Tl), and improves chemical durability. The content of B ₂ O ₃ is 12 to 15%, preferably 12 to 14%, and more preferably 13 to 14%. Within this range, it is possible to increase the devitrification resistance and improve the moldability while increasing the refractive index. If the content of B ₂ O ₃ is too small, the meltability tends to deteriorate and devitrification tends to occur. If the content of B ₂ O ₃ is too large, the refractive index tends to decrease. In addition, the viscosity at the time of melting tends to decrease, making molding difficult.

La ₂ O ₃ is a component that increases the refractive index and decreases the dispersion (increasing the Abbe number). The content of La ₂ O ₃ is 50 to 54%, preferably 50 to 53%, and more preferably 51 to 53%. Within this range, high refractive index and low dispersion can be realized without lowering the devitrification resistance. If the content of La ₂ O ₃ is too small, the refractive index will decrease. If the content of La ₂ O ₃ is too large, the glass becomes unstable, the meltability decreases, and devitrification is likely to occur. The meltability of the optical glass can be evaluated, for example, by visually determining the presence or absence of undissolved residue in the batch when a predetermined amount of the batch is placed in a platinum crucible and heated at a predetermined temperature.

Gd ₂ O ₃ is a component that increases the refractive index and decreases the dispersion (increasing the Abbe number). The content of Gd ₂ O ₃ is 1 to 9%, preferably 2 to 8%, and more preferably 3 to 7%. Within this range, high refractive index and low dispersion can be realized without lowering the devitrification resistance. It also has the function of stabilizing the glass. If the content of Gd ₂ O ₃ is too small, the glass becomes unstable, the meltability decreases, and devitrification is likely to occur. If the content of Gd ₂ O ₃ is too large, the glass becomes unstable, the meltability decreases, and devitrification is likely to occur.

Nb ₂ O ₅ is a component that increases the refractive index and stabilizes the glass. The content of Nb ₂ O ₅ is 4 to 8%, preferably 5 to 8%, and more preferably 6 to 8%. Within this range, a high refractive index can be realized without deteriorating the transmittance. If the content of Nb ₂ O ₅ is too small, it becomes difficult to increase the refractive index. If the content of Nb ₂ O ₅ is too large, the meltability decreases and the liquidus temperature (Tl) rises, which requires treatment at a high temperature and deteriorates the transmittance, making it difficult to reduce the dispersion. Become.

TiO ₂ is a component having an effect of increasing the refractive index and increasing the dispersion. The content of TiO ₂ is 3 to 8%, preferably 4 to 8%, and more preferably 4 to 7%. By setting this range, it is possible to increase the refractive index of Nb ₂ O ₅ or more without deteriorating the transmittance, and the devitrification stability is also good. If the content of TiO ₂ is too small, it becomes difficult to increase the refractive index and the devitrification stability may decrease. If the content of TiO ₂ is too large, the transmittance deteriorates, and it becomes difficult to reduce the dispersion to Nb ₂ O ₅ or higher.

WO ₃ has the effect of increasing the refractive index of the optical glass. From the viewpoint of the balance between the degree of refractive index desired according to the application and the manufacturing cost, the content of WO ₃ is 0.5 to 4%, preferably 1% to 3%, and more preferably 1 to 1. It is 2%.

ZrO ₂ is a component having an effect of increasing the refractive index and increasing the dispersion. The content of ZrO ₂ is 3 to 7%, preferably 4 to 7%, and more preferably 5 to 7%. Within this range, a high refractive index can be realized without deteriorating the transmittance. If the content of ZrO ₂ is too small, it becomes difficult to increase the refractive index. If the content of ZrO ₂ is too large, the meltability is lowered and the liquidus temperature (Tl) is raised, and treatment at a high temperature is required. In addition, devitrification resistance tends to decrease, making vitrification difficult.

The optical glass according to the present embodiment preferably contains substantially no ZnO. When ZnO is contained, the glass transition temperature (Tg) tends to decrease, and the difference from the liquid phase temperature (Tl) tends to become larger. The optical glass according to the present embodiment can be an optical glass having good high refractive index, low dispersion, and good transmittance even if it does not substantially contain ZnO.

Further, the optical glass according to the present embodiment contains at least one selected from the group consisting of Y ₂ O ₃ , Ta ₂ O ₅ , BaO, Al ₂ O ₃ , and Sb ₂ O ₃ as optional components. You may. Among them, as the particularly preferred _{combination, Y 2 O 3 0~5%,} Ta 2 O 5 0~4%, BaO 0~4%, Al 2 O 3 0~1%, Sb 2 O 3 0~1 A combination of% can be mentioned.

Y ₂ O ₃ has the effect of increasing the refractive index without deteriorating the transmittance. The content of Y ₂ O ₃ is preferably 0 to 5%, more preferably 0 to 4%, and even more preferably 0 to 2%.

Ta ₂ O ₅ has the effect of increasing the refractive index of the optical glass and improving the devitrification resistance. The content of Ta ₂ O ₅ is preferably 0 to 4%, more preferably 0 to 3%, and is substantially reduced in weight (reduction of specific gravity) and cost (raw material cost, etc.). It is more preferable that it is not contained in. The optical glass according to this embodiment can achieve high refractive index, low dispersion, and good transmittance even if it does not contain a large amount of Ta ₂ O ₅ .

BaO is useful for promoting meltability and adjusting optical constant values. The content of BaO is preferably 0 to 4%, more preferably 0 to 3%, still more preferably 0 to 2%.

Al ₂ O ₃ is useful for adjusting the optical constant value of optical glass. The content of Al ₂ O ₃ is preferably 0 to 1%.

Sb ₂ O ₃ has the effect of promoting defoaming of the optical glass, but its content tends to deteriorate the transmittance. The content of Sb ₂ O ₃ is preferably 0 to 1%.

Other components other than the above, such as known fining agents, coloring agents, defoaming agents, fluorine compounds, and phosphoric acid, for the purpose of clarifying, coloring, decolorizing, fine-tuning the optical constant value, etc., as necessary. Can be added in an appropriate amount to the glass composition as long as the effects of the present embodiment can be obtained. Further, not limited to the above components, other components may be added as long as the effects of the present embodiment can be obtained.

As each of the above-mentioned raw materials, it is preferable to use a high-purity product having a low content of impurities. For example, it is preferable to use a high-purity product for one or more of the SiO ₂ raw material, the B ₂ O ₃ raw material, and the TiO ₂ raw material. A high-purity product contains 99.85% by mass or more of the component. As a result of reducing the amount of impurities by using a high-purity product, for example, the internal transmittance of light having a wavelength of 410 nm or less tends to be higher.

Next, the physical properties of the optical glass and the like according to the present embodiment will be described.

The optical glass according to the present embodiment has a refractive index (nd) range of preferably 1.84 to 1.91, and more preferably 1.86 to 1.91. As described above, the optical glass according to the present embodiment can realize a high refractive index (high refractive index (nd)). When optical glass having a high refractive index is used, for example, it is possible to design an optical element such as an optical lens to be thin.

The optical glass according to the present embodiment has an Abbe number (νd) in a range of preferably 34 to 39, more preferably 35 to 39. In general, the higher the refractive index, the higher the dispersion (the Abbe number (νd)) tends to be, and the optical glass according to the present embodiment has a low dispersion (Abbe number (νd)) as an optical glass having a high refractive index. ) Is large). When such an optical glass having a high refractive index and a low dispersion is used, it is possible to design an optical system in which chromatic aberration and other aberrations are satisfactorily corrected, for example, by combining with other optical glasses.

From the viewpoint of melt molding, it is preferable that the optical glass according to the present embodiment has a glass transition temperature (Tg) that is not too low. This is because the larger the difference from the liquidus temperature (Tl), the easier it is for pulse to enter. In this respect, in the optical glass according to the present embodiment, the glass transition temperature (Tg) can be set to 670 ° C. or higher. Further, in the optical glass according to the present embodiment, the difference (Tl-Tg) between the liquid phase temperature (Tl) and the glass transition temperature (Tg) is preferably 550 ° C. or lower, more preferably 530 ° C. or lower.

From the viewpoint of the visible light transmittance of the optical system, the optical glass according to the present embodiment preferably has an internal transmittance of 80% display value (wavelength at which the internal transmittance is 80% at an optical path length of 10 mm; λ ₈₀ ). Is 415 nm or less, more preferably 410 nm or less.

From the viewpoint of the visible light transmittance of the optical system, the optical glass according to the present embodiment has a 70% display value of the internal transmittance including surface reflection (wavelength at which the degree of coloring is 70% at an optical path length of 10 mm; λ ₇₀ ). Is preferably 425 nm or less, and more preferably 415 nm or less.

The specific gravity of the optical glass according to this embodiment is preferably 5.0 or less, more preferably 4.9 or less. As a result, it is possible to reduce the weight of the optical element or the like.

The optical glass according to the present embodiment has a high refractive index, a low liquidus temperature, and excellent transmittance performance, although the content of expensive components such as Ta ₂ O ₅ is low.

The method for producing the optical glass according to the present embodiment is not particularly limited, and a known method can be adopted. Further, as the production conditions, suitable conditions can be appropriately selected. For example, raw materials such as oxides, carbonates, nitrates, and sulfates are mixed so as to have a target composition, melted at preferably 1100 to 1500 ° C., more preferably 1200 to 1400 ° C., and homogenized by stirring. , A manufacturing method or the like in which foam is cut off and then cast into a mold can be adopted. The optical glass thus obtained can be made into a desired optical element by performing reheat pressing or the like as necessary to process it into a desired shape and polishing or the like.

The optical glass according to this embodiment is suitable as an optical element such as a lens provided in an optical device such as a camera or a microscope.

The optical glass according to this embodiment can be used, for example, as an optical element included in an optical device. FIG. 1 shows a perspective view of an image pickup apparatus (optical apparatus) including an optical element using optical glass according to an embodiment of the present invention. The image pickup device 1 is a so-called digital single-lens reflex camera, and the lens barrel 3 is detachably attached to a lens mount (not shown) of the camera body 2. Then, the light that has passed through the lens 4 of the lens barrel 3 is imaged on the sensor chip (solid-state image sensor) 5 of the multi-chip module 7 arranged on the back side of the camera body 2. The sensor chip 5 is a bare chip such as a so-called CMOS image sensor, and the multi-chip module 7 is, for example, a COG (Chip On Glass) type module in which the sensor chip 5 is bare-chip mounted on a glass substrate 6.

The optical device is not limited to such an image pickup device, and includes a wide range of devices such as a projector and the like. The optical element is not limited to the lens, and examples thereof include a prism and the like.

Next, Examples and Comparative Examples of the present invention will be described. Each table shows the composition of each component of the optical glass according to the examples and the comparative examples based on the oxide-based mass%, and the evaluation results of the physical properties of the obtained optical glass. The present invention is not limited to these examples.

<Making optical glass>
The optical glass according to the examples and comparative examples of the present invention was produced by the following procedure. First, glass raw materials such as oxides, hydroxides, phosphoric acid compounds (phosphate, orthophosphoric acid, etc.), carbonates, and nitrates were weighed so as to have the compositions (% by mass) shown in each table. Next, the weighed raw materials were mixed and put into a platinum crucible, melted at a temperature of 1380 ° C., and stirred and homogenized. After the bubbles were cut off, the temperature was lowered to an appropriate temperature, cast into a mold or the like, slowly cooled, and molded to obtain each sample.

<Measurement of optical glass>
-Refractive index (nd) and Abbe number (νd)
The refractive index (nd) and Abbe number (νd) of each sample were measured and calculated using a refractive index measuring device (manufactured by Shimadzu Device Manufacturing Co., Ltd .: KPR-2000). The Abbe number (νd) was calculated based on the following equation (1). The value of the refractive index was up to the sixth decimal place.
νd = (nd-1) / (nF-nC) ... (1)
nd: Refractive index of glass with respect to light with a wavelength of 587.562 nm nF: Refractive index of glass with respect to light with a wavelength of 486.133 nm nC: Refractive index of glass with respect to light with a wavelength of 656.273 nm

・ Liquid phase temperature (Tl)
The liquidus temperature (Tl) of each sample is such that about 0.1 g of glass is placed on a platinum plate with holes, held in a test furnace with a temperature gradient of 10 ° C. for 18 minutes, and then taken out of the furnace and rapidly cooled. Then, the presence or absence of devitrification was observed with a microscope having a magnification of 100 times. The liquid phase temperature was set to the lowest temperature at which devitrification did not occur when viewed from the high temperature side.

・ Internal transmittance (λ ₈₀ )
The internal transmittance (λ ₈₀ ) of each sample is 80% by measuring the transmittance without loss due to surface reflection per 10 mm thickness in the wavelength range of 200 to 700 nm when light is incident in parallel with the thickness direction. The wavelength is expressed as λ ₈₀ .

・ Coloring degree (λ ₇₀ )
The degree of coloration (λ ₇₀ ) of each sample is 70% by measuring the transmittance including the loss due to surface reflection per 10 mm thickness in the wavelength range of 200 to 700 nm when light is incident in parallel with the thickness direction. The wavelength is expressed as λ ₇₀ .

・ Glass transition temperature (Tg)
The glass transition temperature (Tg) of each sample was determined from the DTA curve measured at a heating rate of 4 ° C./min. At the same time, the presence or absence of pulse was also evaluated from the Tg value and the like.

-Devitrification resistance The devitrification resistance of each sample was obtained by polishing the prepared glass and visually confirming the presence or absence of devitrification using a microscope (magnification 100 times). “With devitrification” in each table means that a devitrified portion was observed in the sample, and “no devitrification” means that no devitrified portion was observed in the sample. “No reaction” means that the prepared raw material was not melted even when heated at 1380 ° C. and was not vitrified as it was.

It was confirmed that each of the examples had a high refractive index, low dispersion, good transmittance, and could be manufactured at low cost. Furthermore, no devitrification was observed in any of the samples of each example.

On the other hand, in Comparative Example 1, the prepared raw material did not melt at the above-mentioned heating temperature, and the raw material did not undergo a vitrification reaction as it was. In Comparative Examples 2 to 5, it was difficult to measure various physical property values because devitrification was observed in the sample. Further, Comparative Examples 6 and 7 have a composition containing more Ta ₂ O ₅ than the examples, and are inferior in terms of production cost. Although the composition of each example has zero or a small content of Ta ₂ O ₅ , there is no significant difference from the physical properties evaluated in Comparative Examples 6 and 7, and the composition of each example is superior. You can see that.

1: Imaging device, 2: Camera body, 3: Lens barrel, 4: Lens, 5: Sensor chip, 6: Glass substrate, 7: Multi-chip module

Claims (10)

By mass%
SiO ₂ content: 5-9%,
B ₂ O ₃ content: 12-15%,
La ₂ O ₃ content: 50-54%,
Gd ₂ O ₃ content: 1-9%,
Nb ₂ O ₅ content: 4-8%,
TiO ₂ content: 3-8%,
WO ₃ content: 0.5-4%,
ZrO ₂ content: 3-7%,
Y ₂ O ₃ content: 0-5%,
And
It is substantially free of ZnO, optical science glass. In mass%,
T a ₂ O ₅ content: 0-4%,
BaO content: 0-4%,
Al ₂ O ₃ content: 0 to 1%,
Sb ₂ O ₃ content: 0 to 1%,
In it, the optical glass according to請Motomeko 1. The optical glass according to claim 1 or 2, wherein the refractive index (nd) is 1.84 to 1.91 and the Abbe number (νd) is 34 to 39. The optical glass according to any one of claims 1 to 3, wherein the glass transition temperature (Tg) is 675 ° C. or higher. The optical glass according to any one of claims 1 to 4, wherein the wavelength (λ ₈₀ ) at which the internal transmittance is 80% at an optical path length of 10 mm is 415 nm or less. The optical glass according to any one of claims 1 to 5, wherein the wavelength (λ ₇₀ ) at which the degree of coloring is 70% at an optical path length of 10 mm is 425 nm or less. The optical glass according to any one of claims 1 to 6, which has a specific gravity of 5.0 or less. The optical glass according to any one of claims 1 to 7, wherein the liquidus temperature is 1220 ° C. or lower. An optical element comprising the optical glass according to any one of claims 1 to 8. An optical device comprising the optical element according to claim 9.

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