JP2023000285A - Infrared transmitting glass - Google Patents

Abstract

To provide an infrared transmitting glass having excellent light transmission properties in an infrared region.SOLUTION: An infrared transmitting glass contains, in terms of mol%, 20-90% of S+Se+Te, greater than 0% and not greater than 40% of Ge, greater than 0% and not greater than 50% of Al+Si, and 0.01-20% of Mg+Ca.SELECTED DRAWING: None

Description

The present invention relates to infrared transmitting glass.

Development of infrared cameras used for in-vehicle night vision and security systems is progressing. An infrared camera is designed by combining optical elements such as filters and lenses that transmit infrared rays.

Materials such as germanium (Ge), chalcogenide glass, and silicon (Si) are often used for the optical elements. However, Ge is an expensive material, which is disadvantageous in reducing the cost of optical elements. In addition, chalcogenide glass and Si generally have a lower light transmittance in the infrared region than Ge, which is disadvantageous for improving the performance of infrared cameras.

Therefore, a chalcogenide glass having excellent light transmittance in the infrared region has been proposed (Patent Document 1).

WO2020/105719 WO2017/086227

By the way, when oxygen is mixed into the chalcogenide glass, the constituent elements of the glass are combined with the oxygen to generate oxidative impurities, which may cause infrared absorption. The infrared absorption may significantly degrade the optical properties of the optical element.

As a method of suppressing infrared absorption caused by oxide impurities, for example, Patent Document 2 discloses a method of adding Ti to chalcogenide glass. However, since there are oxide impurities that are difficult to sufficiently suppress infrared absorption in Ti, other means for suppressing infrared absorption have been sought.

In view of the above, an object of the present invention is to provide an infrared transmitting glass having excellent light transmitting properties in the infrared region.

The infrared transmitting glass of the present invention is characterized by containing, in mol%, S + Se + Te 20% to 90%, Ge over 0% to 40%, Al + Si over 0% to 50%, and Mg + Ca 0.01% to 20%. do.

The infrared transmitting glass of the present invention preferably contains more than 0% to 50% Al in mol %.

The infrared transmitting glass of the present invention preferably contains more than 0% to 90% Te in mol %.

The infrared transmitting glass of the present invention preferably contains Zn+Ga+In+Sn+Sb+Bi 0% to 40%, Cu+Ag 0% to 40%, F+Cl+Br+I 0% to 40%, and B+C+Cr+Mn+Ti+Fe 0% to 40% in terms of mol %.

The infrared transmitting glass of the present invention preferably has an As content of 30% or less.

In the infrared transmitting glass of the present invention, the ratio (B+Al+Ga+In)/(S+Se+Te) of the content of Group 13 elements to the content of S+Se+Te is preferably 0.7 or less.

In the infrared transmitting glass of the present invention, it is preferable that the ratio (C+Si+Ge+Sn)/(S+Se+Te) of the content of Group 14 elements and the content of S+Se+Te is 0.7 or less.

An optical element of the present invention is characterized by using the above-described infrared transmitting glass.

An infrared sensor of the present invention is characterized by using the optical element described above.

An infrared camera of the present invention is characterized by using the optical element described above.

ADVANTAGE OF THE INVENTION According to this invention, the infrared transmission glass which has the outstanding light transmission characteristic in an infrared region can be provided.

The infrared transmitting glass of the present invention is characterized by containing, in mol%, S + Se + Te 20% to 90%, Ge over 0% to 40%, Al + Si over 0% to 50%, and Mg + Ca 0.01% to 20%. do. The reason for specifying the glass composition in this way and the content of each component will be described below. In the following description, "%" means "mol %" unless otherwise specified.

S, Se and Te are components that form a glass skeleton. The content of S + Se + Te (total amount of S, Se and Te) is 20% to 90%, 30% to 89%, 40% to 89%, 50% to 85%, 50% to 80%, especially 50 % to 75%. If the content of S+Se+Te is too small, it becomes difficult to vitrify. If the content of S+Se+Te is too high, S-, Se-, or Te-based crystals are precipitated, and light transmittance tends to decrease. In addition, the preferable range of content of each component is as follows.

The content of S is 0% to 90%, 10% to 90%, 20% to 89%, 30% to 89%, 40% to 88%, 50% to 88%, 50% to 80%, especially 50 % to 75%. However, S is a component that tends to reduce the light transmittance at wavelengths of 10 μm or more. Therefore, from the viewpoint of improving the light transmittance in the infrared region, the S content is preferably 30% or less, 20% or less, 10% or less, and particularly 5% or less.

The content of Se is 0% to 90%, 10% to 90%, 20% to 89%, 30% to 89%, 40% to 88%, 50% to 88%, 50% to 80%, especially 50 % to 75%. However, Se is a toxic component. Therefore, from the viewpoint of reducing the burden on the environment, the Se content is preferably 40% or less, 30% or less, 20% or less, or 10% or less, and in particular substantially no Se. As used herein, "substantially free" means intentionally not contained in raw materials, and does not exclude contamination at an impurity level. Objectively, the content of each component is less than 0.1%.

Te content is 0% to 90%, more than 0% to 90%, 10% to 90%, 20% to 89%, 30% to 89%, 40% to 88%, 50% to 88%, 50% % to 80%, especially 50% to 75%. If the Te content is too high, it becomes difficult to vitrify. In addition, Te-based crystals are likely to precipitate and the light transmittance tends to decrease.

At least one of S, Se, and Te may be contained, but Te is preferably contained in terms of easily reducing the effect on light transmittance at a wavelength of 8 μm to 14 μm. Especially preferred.

Ge is a component that forms a glass skeleton. The content of Ge is more than 0% to 40%, 0.1% to 39%, 1% to 30%, 2% to 25%, 3% to 20%, especially 4% to 20% is preferred. If the Ge content is too low, it becomes difficult to vitrify. If the Ge content is too high, Ge-based crystals are precipitated and the light transmittance tends to decrease. In addition, raw material costs tend to increase.

Al and Si are components that form a glass skeleton. It is also a component that tends to lower the Abbe number of the glass. The content of Al+Si (total amount of Al and Si) is more than 0% to 50%, 0.1% to 50%, 3% to 45%, 5% to 35%, especially 8% to 25%. Preferably. If Al+Si is too small, it becomes difficult to vitrify. If Al+Si is too much, Al-based or Si-based crystals are precipitated, and light transmittance tends to decrease. In addition, the preferable range of content of each component is as follows.

The Al content is preferably 0% to 50%, more than 0% to 50%, 0.1% to 40%, 3% to 40%, especially 3% to 30%.

The Si content is preferably 0% to 50%, more than 0% to 50%, 0.1% to 40%, 3% to 40%, especially 3% to 30%.

Both Al and Si oxidation impurities have light absorption in the infrared region. Specifically, Si oxide impurities (Si—O) absorb light with a wavelength of about 9 μm. Al impurities (Al—O) absorb light with a wavelength of about 16 μm. Therefore, the presence of these oxide impurities affects the light transmittance in the infrared region. For example, Si oxide impurities tend to have a large effect on light transmittance in the wavelength range (for example, wavelengths of 8 μm to 14 μm) often used in infrared sensors and the like. Also, Al is more easily oxidized than Si. Therefore, Al oxidation impurities are likely to occur and are difficult to remove. Note that when Si and Al are introduced into the glass at the same time, Al tends to be oxidized preferentially over Si from the viewpoint of thermodynamics. Infrared absorption by these oxide impurities can be suppressed by introducing Mg and Ca, which will be described later.

Mg and Ca are components that are highly effective in suppressing infrared absorption caused by oxidation impurities. More specifically, since Mg and Ca are preferentially oxidized over the above-described constituents (Al, Si, Ge, S, Se and Te), infrared absorption caused by these oxide impurities can be easily suppressed. On the other hand, Mg oxidation impurity and Ca oxidation impurity have no absorption in the above-mentioned infrared wavelength region. Therefore, by adding Mg or Ca, it is easy to reduce the influence on the light transmittance in the above wavelength range. The content of Mg+Ca (total amount of Mg and Ca) is 0.01% to 20%, 0.01% to 15%, 0.01% to 10%, 0.01% to 8%, 0.01% to 10%. 01% to 5%, 0.05% to 5%, 0.1% to 5%, especially 0.3% to 5%. If the content of Mg+Ca is too small, there is a possibility that infrared absorption cannot be sufficiently suppressed. If the content of Mg+Ca is too large, Mg-based or Ca-based crystals are precipitated, and light transmittance tends to decrease.

From the viewpoint of thermodynamics, it is preferable to use Ca rather than Mg because it easily reacts with oxygen and has a particularly large effect of suppressing infrared absorption.

The infrared transmitting glass of the present invention may contain the following optional components in addition to the above components.

Zn, Ga, In, Sn, Sb, and Bi are components that widen the vitrification range and tend to improve the thermal stability of the glass. The content of Zn + Ga + In + Sn + Sb + Bi (the total amount of Zn, Ga, In, Sn, Sb and Bi) is 0% to 40%, more than 0% to 40%, 0.1% to 40%, 0.1% to 30% , 0.1% to 20%, 0.1% to 10%, especially 0.1% to 5%. If the content of Zn+Ga+In+Sn+Sb+Bi is too high, vitrification becomes difficult. The content of each component of Zn, Ga, In, Sn, Sb, and Bi is 0% to 40%, 0% to 40%, 0% to 40%, 0% to 30%, 0% to 20%. , 0% to 10%, 0% to 5%, especially 0.1% to 5%.

Cu and Ag are components that tend to widen the vitrification range and improve the thermal stability of the glass. The content of Cu + Ag (total amount of Cu and Ag) is 0% to 40%, more than 0% to 40%, 0.1% to 40%, 0.1% to 30%, 0.1% to 20% , particularly preferably 0.1% to 10%. If the content of Cu+Ag is too high, it becomes difficult to vitrify. The content of each component of Cu and Ag is 0% to 40%, 0% to 40%, 0% to 40%, 0% to 30%, 0% to 20%, 0% to 10%, especially It is preferably 0.1% to 10%.

F, Cl, Br and I are components that tend to widen the vitrification range and improve the thermal stability of the glass. The content of F+Cl+Br+I (total amount of F, Cl, Br and I) is preferably 0% to 40%, 0% to 30%, 0% to 20%, particularly 0% to 10%. If the content of F+Cl+Br+I is too high, vitrification becomes difficult. Moreover, the weather resistance tends to decrease. The content of each component of F, Cl, Br and I is preferably 0% to 40%, 0% to 30%, 0% to 20%, particularly 0% to 10%.

In addition to the above components, B, C, Cr, Mn, Ti, Fe, etc. may be contained. The content of B + C + Cr + Mn + Ti + Fe (total amount of B, C, Cr, Mn, Ti and Fe) is 0% to 40%, 0% to 30%, 0% to 20%, 0% to 10%, 0% to 5 %, 0% to 1%, especially 0% to less than 1%. If the content of these components is too high, it may become difficult to obtain the desired optical properties. The content of each component of B, C, Cr, Mn, Ti, and Fe is 0% to 10%, 0% to 5%, 0% to 1%, particularly 0% to less than 1%. preferable.

The content of the above-described optional components Zn+Ga+In+Sn+Sb+Bi+Cu+Ag+F+Cl+Br+I+B+C+Cr+Mn+Ti+Fe is preferably 0% to 40%, 0% to 30%, 0% to 20%, 0% to 10%, and particularly preferably 0.1% to 5%.なお本発明において、「Ｚｎ＋Ｇａ＋Ｉｎ＋Ｓｎ＋Ｓｂ＋Ｂｉ＋Ｃｕ＋Ａｇ＋Ｆ＋Ｃｌ＋Ｂｒ＋Ｉ＋Ｂ＋Ｃ＋Ｃｒ＋Ｍｎ＋Ｔｉ＋Ｆｅ Ｘ％～Ｙ％」は、例えば「Ｆｅ＝０％、Ｇａ＋Ｉｎ＋Ｓｎ＋Ｓｂ＋Ｂｉ＋Ｃｕ＋Ａｇ＋Ｆ＋Ｃｌ＋Ｂｒ＋Ｉ＋Ｂ＋Ｃ＋Ｃｒ＋Ｍｎ＋Ｔｉ＋Ｆｅ Ｘ％～Ｙ％」や「Ｆｅ＝０％、Ｔｉ＝０％、Ｉｎ＋Ｓｎ＋Ｓｂ＋Ｂｉ＋Ｃｕ＋Ａｇ＋Ｆ＋Ｃｌ＋Ｂｒ＋Ｉ＋Ｂ＋Ｃ＋Ｃｒ＋Ｍｎ＋Ｔｉ＋Ｆｅ Ｘ％～Ｙ％」の場合including.

As is a component that enhances the thermal stability of glass. However, since As is a toxic component, from the viewpoint of reducing the burden on the environment, the content of As is 30% or less, 25% or less, 20% or less, 10% or less, 5% or less, especially substantially It is preferable not to contain in

It is preferable not to contain Cd, Tl and Pb substantially. In this way, environmental impact can be minimized.

Ratio of the total content (mol%) of the Group 13 elements (B, Al, Ga, In) to the total content (mol%) of the chalcogen elements (S, Se, Te) (B + Al + Ga + In) / ( S+Se+Te) is preferably 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, particularly 0.2 or less. The lower limit is preferably 0.01 or more, for example. When the content ratio of the group 13 element and the chalcogen element satisfies the above, vitrification is facilitated.

The ratio (C+Si+Ge+Sn)/(S+Se+Te) of the content of Group 14 elements (C, Si, Ge, Sn) and the content of chalcogen elements (S, Se, Te) is 0.7 or less, 0.6 or less, It is preferably 0.5 or less, particularly 0.4 or less. The lower limit is preferably 0.01 or more, for example. When the content ratio of the group 14 element and the chalcogen element satisfies the above, vitrification is facilitated.

The infrared transmitting glass of the present invention preferably has an infrared absorption edge wavelength of 15 μm or more, 16 μm or more, particularly 17 μm or more. The larger the infrared absorption edge wavelength, the more infrared rays on the longer wavelength side can be transmitted. Here, the infrared absorption edge wavelength means the wavelength on the longest wavelength side at which the light transmittance is 10% with a thickness of 2 mm in the infrared region with a wavelength of 1 μm or longer.

The infrared transmitting glass of the present invention can be produced, for example, as follows. First, raw materials are blended so as to have a desired composition. Next, the prepared raw materials are put into a quartz glass ampoule which has been evacuated while being heated, and the tube is sealed with an oxygen burner while being evacuated. Next, the sealed quartz glass ampoule is held at about 650° C. to 1000° C. for 6 hours to 12 hours. After that, by rapidly cooling to room temperature, an infrared transmitting glass can be obtained.

As raw materials, element raw materials (Ge, Ga, Si, Te, Ag, I, etc.) may be used, and compound raw materials (GeTe ₄ , Ga ₂ Te ₃ , AgI, etc.) may be used. Moreover, you may use these together.

An optical element can be produced by processing the obtained infrared transmitting glass into a predetermined shape (disk shape, lens shape, etc.).

For the purpose of improving transmittance, an antireflection film may be formed on one side or both sides of the optical element. Methods for forming the antireflection film include a vacuum deposition method, an ion plating method, a sputtering method, and the like.

After forming an antireflection film on the infrared transmitting glass, the glass may be processed into a predetermined shape. However, since the antireflection film tends to peel off during the processing step, it is preferable to form the antireflection film after processing the infrared transmitting glass into a predetermined shape unless there are special circumstances.

Thus, the infrared transmitting glass of the present invention contains 20% to 90% S + Se + Te, more than 0% to 40% Ge, more than 0% to 50% Al + Si, and 0.01% to 20% Mg + Ca. have a configuration. The infrared-transmitting glass having such a structure tends to suppress infrared absorption due to oxidation impurities, and tends to exhibit excellent light-transmitting properties in the infrared region.

EXAMPLES The present invention will be described below based on examples, but the present invention is not limited to these examples.

Tables 1-4 show Examples 1-26 and Comparative Examples 27 and 28 of the present invention.

Samples of Examples and Comparative Examples were prepared as follows. First, after heating and evacuating a quartz glass ampoule, raw materials were mixed so as to have the glass compositions shown in Tables 1 to 4, and charged into the quartz glass ampoule. Next, the quartz glass ampoule was sealed with an oxygen burner. Next, the sealed quartz glass ampoule was placed in a melting furnace, heated to 650° C. to 1000° C. at a rate of 10° C. to 40° C./hour, and held for 6 to 12 hours. During the holding time, the quartz glass ampoule was turned upside down to stir the melt. Finally, the quartz glass ampoule was removed from the melting furnace and rapidly cooled to room temperature to obtain a sample. The obtained sample was measured for light transmittance in the infrared region to examine the presence or absence of infrared absorption.

A sample with a thickness of 2 mmt was used to measure the light transmittance in the infrared region with a wavelength of 8 μm to 14 μm. In the obtained transmittance spectrum, the wavelength region in which the transmittance decreased by 10% or more from the light transmittance at a wavelength of 10 μm was judged to be oxidation absorption, and was described as "present" in Tables 1 to 4. It was determined that oxidation absorption of Ge occurred when the wavelength range was 13 μm to 14 μm, and oxidation absorption of Al occurred when the wavelength range was 14 μm to 18 μm. When absorption was not observed, it was described as "none".

As is clear from Tables 1 to 4, the addition of Mg or Ca can suppress the infrared absorption caused by the bonding of Ge, Al and oxygen.

The infrared transmitting glass of the present invention can be suitably used for optical elements such as filters and lenses used in infrared sensors, infrared cameras, and the like.

Claims (10)

An infrared transmitting glass containing, in mol %, S+Se+Te 20%-90%, Ge >0%-40%, Al+Si >0%-50%, Mg+Ca 0.01%-20%. 2. The infrared transmitting glass of claim 1, containing more than 0% to 50% Al in mol %. An infrared transmitting glass according to claim 1 or 2, containing more than 0% to 90% Te in mol%. Infrared transmission according to any one of claims 1 to 3, containing, in mol%, Zn+Ga+In+Sn+Sb+Bi 0% to 40%, Cu+Ag 0% to 40%, F+Cl+Br+I 0% to 40%, B+C+Cr+Mn+Ti+Fe 0% to 40%. glass. The infrared transmitting glass according to any one of claims 1 to 4, wherein the As content is 30% or less. The infrared transmitting glass according to any one of claims 1 to 5, wherein the ratio (B+Al+Ga+In)/(S+Se+Te) of the content of Group 13 elements and the content of S+Se+Te is 0.7 or less. The infrared transmitting glass according to any one of claims 1 to 6, wherein the ratio of the content of Group 14 elements and the content of S + Se + Te (C + Si + Ge + Sn) / (S + Se + Te) is 0.7 or less. An optical element using the infrared transmitting glass according to any one of claims 1 to 7. An infrared sensor using the optical element according to claim 8 . An infrared camera using the optical element according to claim 8 .