WO2023243407A1 - Infrared ray transmitting glass - Google Patents

Abstract

Provided is an infrared ray transmitting glass that is easily vitrified, has excellent thermal stability, and is capable of achieving excellent infrared ray transmissivity. This infrared ray transmitting glass is characterized by containing, in mol%, 25-90% of S+Se+Te, 0.1-55% of Ge+Ga, and 0% or more but less than 40% of Cu+Sn+Bi, and by having a volume resistivity of 10^3.0 (Ωcm) or more.

Description

infrared transparent glass

The present invention relates to infrared transmitting glass.

The development of infrared cameras for use in in-vehicle night vision and security systems is progressing. Infrared cameras are designed by combining optical elements such as filters and lenses that transmit infrared rays.

Materials such as germanium (Ge) and silicon (Si) are often used for the above optical elements. However, Ge is an expensive material and is disadvantageous for reducing the cost of optical elements. Further, Si has a lower light transmittance than Ge in the infrared region, which is disadvantageous for improving the performance of an infrared camera.

Therefore, various chalcogenide glasses have been proposed as materials to replace Ge and Si (Patent Document 1).

International Publication No. 2017/086227

Infrared cameras are popular as thermography and night vision cameras, and the higher the contrast of the captured image, the higher the temperature resolution and visibility in dark places. Therefore, infrared transmitting materials, particularly chalcogenide glasses, are required to have high internal transmittance in the infrared region from the viewpoint of increasing the contrast of photographed images. In addition, from the viewpoint of improving production stability, chalcogenide glasses that are easy to vitrify and have excellent thermal stability are required.

In view of the above, an object of the present invention is to provide an infrared transmitting glass that is easy to vitrify, has excellent thermal stability, and can achieve high internal transmittance in the infrared region.

Each aspect of the infrared transmitting glass that solves the above problems will be explained.

The infrared transmitting glass of embodiment 1 contains S+Se+Te 25% to 90%, Ge+Ga 0.1% to 55%, Cu+Sn+Bi 0% to less than 40% in mol%, and has a volume resistivity of 10 ^3.0 (Ωcm). It is characterized by the above.

The infrared transmitting glass of Aspect 2 preferably further contains, in mol%, Al+Si 0% to 40%, B+C+Mg+Ca+Ti+Cr+Mn+Fe+Zn+Ag+In+Sb 0% to 40%, and F+Cl+Br+I 0% to 40%.

The infrared transmitting glass of Aspect 3 preferably does not substantially contain Se and As in Aspect 1 or Aspect 2.

In any one of aspects 1 to 3, the infrared transmitting glass of aspect 4 preferably has an internal transmittance of 90% or more at a wavelength of 10 μm. "Internal transmittance" refers to transmittance excluding surface reflection loss on the incident side and exit side of the sample. Further, the "internal transmittance" in the present invention refers to the internal transmittance at a thickness of 2 mm, and specifically, it is calculated from the measured values of transmittance including surface reflection loss at thicknesses of 2 mm and 6 mm.

The optical element of Aspect 5 is characterized by using the infrared transmitting glass described in any one of Aspects 1 to 4.

The infrared camera according to aspect 6 is characterized by using the optical element according to aspect 5.

According to the present invention, it is possible to provide an infrared transmitting glass that is easy to vitrify, has excellent thermal stability, and can achieve high internal transmittance in the infrared region.

The infrared transmitting glass of the present invention contains S+Se+Te 25% to 90%, Ge+Ga 0.1% to 55%, Cu+Sn+Bi 0% to less than 40% in mol%, and has a volume resistivity of 10 ^3.0 (Ωcm). It is characterized by the above. The infrared transmitting glass of the present invention is a so-called chalcogenide glass having a glass skeleton of chalcogen elements (S, Se, and Te). The reason why the glass composition was defined as above and the content of each component will be explained below. In the following description, "%" means "mol%" unless otherwise specified. Furthermore, in the present invention, "x+y+z+..." means the total content of each component. Here, each component does not necessarily have to be included as an essential component, and there may be components that are not included (content: 0%). Also, "x+y+z+... A%~B%" can be replaced with, for example, "x=0%, y+z+... A%~B%" or "x=0%, y=0%, z+... A%~ Including the case of "B%".

Volume resistivity is 10 ^3.0 (Ωcm) or more, 10 ^3.4 (Ωcm) or more, 10 ^3.6 (Ωcm) or more, 10 ^3.8 (Ωcm) or more, 10 ^4.0 (Ωcm) or more , 10 ^4.2 (Ωcm) or more, particularly preferably 10 ^4.4 (Ωcm) or more. When the volume resistivity decreases, absorption of infrared light (hereinafter referred to as electronic absorption) resulting from the vibration of free electrons in the glass tends to occur, and the internal transmittance in the infrared region tends to decrease.

S, Se, and Te are components that form the glass skeleton. The content of S + Se + Te (total amount of S, Se and Te) is 25% to 90%, 30% to 89%, 40% to 89%, 50% to 85%, 50% to 82%, 50% It is preferably 80% to 80%, particularly 50% to 75%. If the content of S+Se+Te is too small, vitrification becomes difficult. If the content of S+Se+Te is too large, S-based, Se-based, or Te-based crystals will precipitate, and the internal transmittance will tend 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 perspective of improving light transmittance in the infrared region, the S content should be 30% or less, 20% or less, 15% or less, 10% or less, 5% or less, 1% or less, 0.5% or less. In particular, it is preferable that the content is substantially not contained. As used herein, "substantially not containing" means that the material is not intentionally contained in the raw material, and does not exclude contamination at an impurity level. Objectively, the content of each component is less than 0.1%.

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 perspective of reducing the burden on the environment, the Se content should be 40% or less, 30% or less, 20% or less, 15% or less, 10% or less, 5% or less, 1% or less, especially if the It is preferable not to contain it.

Te is a component that tends to increase the light transmittance in the wavelength range of 10 μm or more. On the other hand, Te is a component that particularly tends to lower the volume resistivity, and if the content of Te is too large, the internal transmittance in the infrared region tends to decrease due to electron absorption. Therefore, the content of Te is 0% to 90%, 1% to 90%, 10% to 90%, 20% to 89%, 30% to 89%, 40% to 88%, 43% to 88%, It is preferably 50% to 88%, 50% to 80%, particularly 50% to 75%.

Note that it is sufficient to contain at least one component among S, Se, and Te, but it is particularly preferable to contain Te in terms of increasing the light transmittance in a wavelength range of 10 μm or more.

Ge and Ga are components that form the glass skeleton. The content of Ge+Ga (total amount of Ge and Ga) is 0.1% to 55%, 0.1% to 50%, 0.3% to 50%, 0.3% to 44%, 0. It is preferably 3% to 34%, particularly 0.5% to 30%. If the content of Ge+Ga is too small, it will be difficult to vitrify. If the content of Ge+Ga is too large, Ge-based or Ga-based crystals will precipitate, and the internal transmittance will tend to decrease. Note that, especially when it is desired to improve the stability of vitrification, the content of Ge+Ga is preferably 1% or more, 2% or more, 3% or more, particularly 5% or more. In addition, the preferable range of content of each component is as follows.

The content of Ge is 0% to 55%, 0% to 50%, 0% to 45%, 0% to 40%, 0% to 35%, 0% to 30%, 0.1% to 30%, It is preferably 0.1% to 25%, 0.3% to 25%, 0.3% to 24%, 0.5% to 22%, particularly 0.5% to 20%. If the Ge content is too high, the light transmittance tends to decrease. In addition, raw material costs tend to increase.

The Ga content is 0% to 55%, 0% to 50%, 0% to 45%, 0% to 40%, 0% to 35%, 0% to 30%, 0% to 28%, 0. It is preferably 1% to 25%, 0.3% to 25%, 0.3% to 24%, particularly 0.5% to 22%. If the Ga content is too high, Ga-based crystals will precipitate and the internal transmittance will tend to decrease.

Cu, Sn, and Bi are components that expand the vitrification range and particularly tend to improve the thermal stability of glass. However, these components tend to lower the volume resistivity and also tend to lower the internal transmittance in the infrared region due to electron absorption, so the content of Cu+Sn+Bi (total amount of Cu, Sn, and Bi) is 0%. - less than 40%, 0% to less than 30%, 0.1% to less than 35%, 0.1% to less than 30%, 1% to less than 20%, particularly preferably 1% to less than 10%. Note that the content of each component of Cu, Sn, and Bi is preferably 0% to less than 40%. To describe in more detail, the content of each component of Cu, Sn, and Bi is preferably 0% or more, 0.1% or more, particularly 1% or more, and less than 40%, less than 35%, and less than 30%. , less than 20%, less than 10%, particularly preferably 9% or less. In addition, from the viewpoint of improving the internal transmittance in the infrared region in particular, the content of each component of Cu, Sn, and Bi is less than 5%, less than 3%, less than 1%, less than 0.5%, and 0.4%. %, less than 0.3%, less than 0.2%, 0.1% or less, particularly preferably substantially not.

From the viewpoint of suppressing a decrease in volume resistivity, the molar ratio (Cu+Sn+Bi)/(S+Se+Te) is preferably 0.8 or less, 0.7 or less, 0.6 or less, particularly 0.5 or less, and 0 or more. , 0.010 or more, 0.020 or more, 0.030 or more, 0.050 or more, 0.100 or more, 0.150 or more, 0.200 or more, 0.250 or more, 0.290 or more, especially 0.300 It is preferable that it is above. Note that (Cu+Sn+Bi)/(S+Se+Te) means a value obtained by dividing the total amount of Cu, Sn, and Bi by the total amount of S, Se, and Te.

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

Al and Si are components that expand the vitrification range, tend to increase the thermal stability of glass, and are components that improve volume resistivity. The content of Al+Si (total amount of Al and Si) is 0% to 40%, 0% to 30%, 0% to 20%, 0% to 10%, 0% to 5%, especially 0% to 2. Preferably it is 5%. If the content of Al+Si is too large, Al-based or Si-based crystals will precipitate, and the internal transmittance will tend to decrease. Note that the content of each component of Al and Si is preferably 0% to 40%. More specifically, the content of each component of Al and Si is preferably 0% or more, 0.1% or more, especially 1% or more, and less than 40%, less than 35%, less than 30%, and less than 20%. %, less than 10%, particularly preferably 9% or less. In addition, from the viewpoint of improving internal transmittance in the infrared region in particular, the content of each component of Al and Si is less than 5%, less than 3%, less than 1%, less than 0.5%, and less than 0.4%. , less than 0.3%, less than 0.2%, 0.1% or less, particularly preferably substantially not contained.

It may contain B, C, Mg, Ca, Ti, Cr, Mn, Fe, Zn, Ag, In, Sb, etc. The content of B+C+Mg+Ca+Ti+Cr+Mn+Fe+Zn+Ag+In+Sb (total amount of B, C, Mg, Ca, Ti, Cr, Mn, Fe, Zn, Ag, In and Sb) is 0% to 40%, 0% to 30%, 0% to 20 %, 0% to 10%, 0% to 5%, 0% to 1%, particularly 0% to less than 1%. If the content of these components is too large, it may be difficult to obtain desired optical properties. The content of each component of B, C, Mg, Ca, Ti, Cr, Mn, Fe, Zn, Ag, In, and Sb is 0% to 10%, 0% to 5%, 0% to 1%. , particularly preferably from 0% to less than 1%.

From the viewpoint of obtaining desired optical properties, the molar ratio Ag/(S+Se+Te) is 0.0300 or more, 0.0325 or more, 0.0350 or more, 0.0375 or more, 0.0400 or more, 0.0425 or more, 0.0450. Above, it is preferably 0.0475 or more, particularly 0.0500 or more. Note that Ag/(S+Se+Te) means the value obtained by dividing the content of Ag by the total amount of S, Se, and Te.

F, Cl, Br, and I are components that tend to expand the vitrification range and increase the thermal stability of the glass, and are components that improve the volume resistivity. The content of F + Cl + Br + I (total amount of F, Cl, Br and I) is 0% to 40%, 0% to 30%, 0% to 20%, 0% to 10%, 0% to 5%, 0% It is preferably from 0% to less than 1%, particularly from 0% to less than 1%. If the content of these components is too large, it may be difficult to obtain desired optical properties. Note that the content of each component of F, Cl, Br, and I is preferably 0% to 10%, 0% to 5%, 0% to 1%, particularly 0% to less than 1%.

As is a component that increases the thermal stability of glass. However, since As is a toxic component, from the perspective of reducing the burden on the environment, the As content should be 30% or less, 25% or less, 20% or less, 10% or less, 5% or less, 3% or less. , 1% or less, particularly preferably substantially no content. Note that, from the viewpoint of particularly reducing the burden on the environment, it is particularly preferable that Se and As are not substantially contained.

It is preferable that Cd, Tl, and Pb are substantially not contained. In this way, the impact on the environment can be minimized.

The infrared transmitting glass of the present invention preferably has an internal transmittance of 90% or more, 92% or more, 94% or more, 96% or more, particularly 98% or more at a wavelength of 10 μm. By using an infrared transmitting glass having such internal transmittance, it is possible to manufacture an optical element that exhibits relatively high transmittance in the infrared wavelength region. Although the upper limit of the internal transmittance is not particularly limited, it is realistically less than 99.99%.

The infrared transmitting glass of the present invention can be produced, for example, as follows. First, raw materials are mixed to have a desired composition. Next, the prepared raw materials are put into a quartz glass ampoule that has been heated and evacuated, and the ampoule 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. Thereafter, by rapidly cooling to room temperature, an infrared transmitting glass can be obtained.

As the raw material, elemental raw materials (Ge, Ga, Si, Te, Ag, I, etc.) may be used, or 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 example, optical elements such as lenses can be suitably used in various infrared devices such as infrared cameras.

For the purpose of improving transmittance, an antireflection film may be formed on one or both sides of the optical element. Examples of methods for forming the antireflection film include vacuum evaporation, ion plating, and sputtering.

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

Hereinafter, the present invention will be explained based on Examples, but the present invention is not limited to these Examples.

Tables 1 to 8 are Example Nos. of the present invention. 1 to 58 and Comparative Example No. 1 is shown.

Examples and comparative examples were produced as follows. First, a quartz glass ampoule was evacuated while being heated, and then raw materials were prepared to have the glass compositions shown in Tables 1 to 8 and placed in 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, and the temperature was raised to 650°C to 1000°C at a rate of 10°C to 40°C/hour, and then held for 6 to 12 hours. During the holding time, the quartz glass ampoule was turned upside down and the melt was stirred. Finally, the quartz glass ampoule was taken out of the melting furnace and rapidly cooled to room temperature to obtain a sample. The internal transmittance and volume resistivity of the obtained sample were determined.

Using samples with a thickness of 2 mm and 6 mm, the light transmittance in the infrared region was measured, and the obtained light transmittance was used to calculate the internal transmittance at a wavelength of 10 μm when the thickness was 2 mm.

The resistance between the Al electrodes provided on both sides of a sample with a thickness of 2 mm was measured, and the volume resistivity was calculated from the obtained resistance value, sample thickness, and Al electrode area. The following formula was used for calculation.

Volume resistivity (Ωcm) = resistance value between Al electrodes (Ω) x Al electrode area (cm ² )/sample thickness (cm)

As is clear from Tables 1 to 8, Example No. Nos. 1 to 58 had a volume resistivity of 10 ^3.0 Ωcm or more and an internal transmittance of 90% or more. Comparative example no. No. 1 had a small volume resistivity of 10 ^2.9 Ωcm. Furthermore, the internal transmittance was as low as 84.0%.

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 (6)

1. It is characterized by containing S+Se+Te 25% to 90%, Ge+Ga 0.1% to 55%, Cu+Sn+Bi 0% to less than 40% in mol%, and having a volume resistivity of 10 ^3.0 (Ωcm) or more. Infrared transparent glass.
2. The infrared transmitting glass according to claim 1, which contains, in mol%, Al+Si 0% to 40%, B+C+Mg+Ca+Ti+Cr+Mn+Fe+Zn+Ag+In+Sb 0% to 40%, and F+Cl+Br+I 0% to 40%.
3. The infrared transmitting glass according to claim 1 or 2, which does not substantially contain Se and As.
4. The infrared transmitting glass according to claim 1 or 2, having an internal transmittance of 90% or more at a wavelength of 10 μm.
5. An optical element using the infrared transmitting glass according to claim 1 or 2.
6. An infrared camera using the optical element according to claim 5.