JP6819920B2 - Calcogenide glass - Google Patents

Description

The present invention relates to infrared transmissive glass used for infrared sensors and the like.

In-vehicle night vision and security systems are equipped with infrared sensors used for nighttime biological detection. Since the infrared sensor senses infrared rays having a wavelength of about 8 to 14 μm emitted from a living body, an optical element such as a filter or a lens that transmits infrared rays in the wavelength range is provided in front of the sensor unit.

Examples of the material for the optical element as described above include Ge and ZnSe. Since these are crystals, they are inferior in processability, and it is difficult to process them into a complicated shape such as an aspherical lens. Therefore, there is a problem that it is difficult to mass-produce and it is also difficult to miniaturize the infrared sensor.

Therefore, chalcogenide glass has been proposed as a vitreous material that transmits infrared rays having a wavelength of about 8 to 14 μm and is relatively easy to process (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2009-161374

Since the glass described in Patent Document 1 has a significantly reduced infrared transmittance at a wavelength of 10 μm or more, it is particularly inferior in sensitivity to infrared rays emitted from a living body, and the infrared sensor may not function sufficiently.

In view of the above, it is an object of the present invention to provide a glass having excellent infrared transmittance and suitable for infrared sensor applications.

As a result of diligent studies by the present inventors, it has been found that the chalcogenide glass having a specific composition can solve the above-mentioned problems.

That is, the infrared transmissive glass of the present invention has Ge 34 to 80%, Te 0 to 66% (but does not include 0%), S 0 to 66% (but does not include 0%), Ga + Sn + Ag + Cu + Bi + Sb 0 in mol%. It is characterized by containing ~ 50% and F + Cl + Br + I 0 to 50%. In addition, in this specification, "○ + ○ + ..." means the total amount of contents of each corresponding component.

The infrared transmissive glass of the present invention preferably contains substantially no Cd, Tl and Pb.

The infrared transmissive glass of the present invention preferably has an infrared absorption edge wavelength of 20 μm or more at a thickness of 2 mm. In the present invention, the "infrared absorption edge wavelength" means a wavelength at which the light transmittance is 0.5% in the infrared region having a wavelength of 8 μm or more.

The optical element of the present invention is characterized by using the above-mentioned infrared transmissive glass.

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

According to the present invention, it is possible to provide a glass having excellent infrared transmittance and suitable for infrared sensor applications.

The infrared transmissive glass of the present invention has Ge 34 to 80%, Te 0 to 66% (but does not include 0%), S 0 to 66% (but does not contain 0%), Ga + Sn + Ag + Cu + Bi + Sb 0 to 50 in mol%. % And F + Cl + Br + I 0 to 50%. The reason for defining the glass composition in this way will be described below. In the following description of the content of each component, "%" means "mol%" unless otherwise specified.

Ge is an essential component for forming a glass skeleton. The infrared transmissive glass of the present invention contains a relatively large amount of Ge to improve thermal stability (stability of vitrification). The content of Ge is 34 to 80%, preferably 35 to 70%, more preferably 36 to 60%, and even more preferably 36 to 50%. If the content of Ge is too small, it becomes difficult to vitrify. On the other hand, if the content of Ge is too large, Ge-based crystals are precipitated to make it difficult for infrared rays to pass through, and the raw material cost tends to increase.

The chalcogen element Te is an essential component that forms the glass skeleton. The content of Te is 0 to 66% (but not including 0%), preferably 10 to 65%, and more preferably 20 to 65%. If the content of Te is too small, it becomes difficult to vitrify. On the other hand, if the content of Te is too large, Te-based crystals are precipitated and it becomes difficult to vitrify, and as a result, infrared rays are difficult to transmit.

Similarly, S, which is a chalcogenide element, is an essential component that enhances thermal stability. The content of S is 0 to 66% (but not including 0%), preferably 1 to 60%, more preferably 2 to 50%, and further preferably 3 to 40%. preferable. If the content of S is too small, it becomes difficult to vitrify. On the other hand, if the S content is too large, the infrared absorption edge wavelength shifts to the short wavelength side, and the infrared transmission characteristic tends to deteriorate.

Ga, Sn, Ag, Cu, Bi, and Sb are components that enhance the thermal stability of glass without deteriorating the infrared transmission characteristics. The content of Ga + Sn + Ag + Cu + Bi + Sb is 0 to 50%, preferably 1 to 40%, more preferably 2 to 30%, further preferably 3 to 25%, and 5 to 20%. Is particularly preferred. If the content of Ga + Sn + Ag + Cu + Bi + Sb is too small or too large, it becomes difficult to vitrify. The content of each component of Ga, Sn, Ag, Cu, Bi, and Sb is 0 to 50%, preferably 0 to 50% (but not including 0%), and is preferably 1 to 40. It is more preferably%, further preferably 2 to 30%, particularly preferably 3 to 25%, and most preferably 5 to 20%. Of these, Ag, Sn or Cu is preferably used because it has a particularly large effect of increasing the thermal stability of the glass.

F, Cl, Br, and I are also components that enhance the thermal stability of glass. The contents of F, Cl, Br, and I are 0 to 50%, preferably 1 to 40%, more preferably 1 to 30%, and even more preferably 1 to 25%. It is particularly preferably 1 to 20%. If the content of F + Cl + Br + I is too large, it becomes difficult to vitrify and the weather resistance tends to decrease. The content of each component of F, Cl, Br, and I is 0 to 50%, preferably 1 to 40%, more preferably 1 to 30%, and 1 to 25%, respectively. Is more preferable, and 1 to 20% is particularly preferable. Among them, it is preferable to use I because an elemental raw material can be used and the effect of enhancing glass stability is particularly large.

In addition to the above components, the infrared transmissive glass of the present invention may contain the following components.

Zn, In, and P are components that widen the vitrification range and enhance the thermal stability of glass. The content thereof is preferably 0 to 20%, more preferably 0.5 to 10%. If the content of these components is too high, it becomes difficult to vitrify.

Se and As are components that widen the vitrification range and enhance the thermal stability of glass. The content thereof is preferably 0 to 10%, more preferably 0.5 to 5%. However, since these substances are toxic, it is preferable not to contain them from the viewpoint of reducing the influence on the environment and the human body.

It is preferable that the infrared transmissive glass of the present invention does not substantially contain toxic substances Cd, Tl and Pb. In this way, the impact on the environment can be minimized. Here, "substantially not contained" means that it is intentionally not contained in the raw material, and does not exclude contamination at the impurity level. Objectively, it means that the content of each component is less than 0.1%.

The infrared transmissive glass of the present invention has excellent infrared transmittance at a wavelength of about 8 to 18 μm. As an index for evaluating the infrared transmittance, the infrared absorption edge wavelength can be mentioned. It can be judged that the larger the infrared absorption edge wavelength, the better the infrared transmission. The infrared absorption edge wavelength at a thickness of 2 mm of the infrared transmissive glass of the present invention is preferably 20 μm or more, and more preferably 21 μm or more.

The infrared transmissive glass of the present invention can be produced, for example, as follows. First, the raw materials are prepared so as to have a desired composition. Put the raw material in a quartz glass ampoule that has been evacuated while heating, and seal it with an oxygen burner while evacuating. The infrared transmissive glass of the present invention can be obtained by holding a sealed quartz glass ampoule at about 650 to 1000 ° C. for 6 to 12 hours and then rapidly cooling it to room temperature.

As the raw material, an elemental raw material (Ge, Te, S, Ag, I, etc.) may be used, or a compound raw material (GeTe ₄ , GeS ₂ , AgI, etc.) may be used. It is also possible to use these in combination.

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

Tables 1 to 3 show examples and comparative examples of the present invention, respectively.

Each sample was prepared as follows. The raw materials were mixed so as to have the glass compositions shown in Tables 1 to 3, and raw material batches were obtained. After vacuum exhausting the quartz glass amplifier washed with pure water while heating, a raw material batch was put in, and the quartz glass amplifier was sealed with an oxygen burner while vacuum exhausting.

The sealed quartz glass ampoule was heated to 650 to 1000 ° C. at a rate of 10 to 20 ° C./hour in a melting furnace and then held for 6 to 12 hours. During the holding time, the quartz glass ampoule was turned upside down every 2 hours to stir the melt. Then, the quartz glass ampoule was taken out from the melting furnace and rapidly cooled to room temperature to obtain a sample.

The obtained sample was subjected to X-ray diffraction, and it was confirmed from the diffraction spectrum whether or not it was vitrified. In the table, those that are vitrified are marked with "○" and those that are not vitrified are marked with "x". In addition, the light transmittance at a thickness of 2 mm was measured for each sample, and the infrared absorption edge wavelength was measured.

As shown in Tables 1 and 2, the samples of Examples 1 to 14 are vitrified, have an infrared absorption edge wavelength of 24.1 to 24.4 μm, and are good in the infrared region near a wavelength of 8 to 18 μm. It showed the light transmittance.

On the other hand, the samples of Comparative Examples 1 to 4 were not vitrified, and the light transmittance was almost 0% in the wavelength range of 2 to 24 μm.

The infrared transmissive glass of the present invention is suitable as an optical element such as a cover member for protecting the sensor portion of the infrared sensor and a lens for condensing infrared light on the sensor portion.

Claims (3)

In mole%, Ge 34~ 60%, Te 30 ~6 1%, S 3 ~ 20%, Ga + Sn + Ag + Cu + Bi + Sb 0~ 30%, and F + Cl + Br + I 0~ chalcogenide glass, characterized in that it contains 30%. The chalcogenide glass according to claim 1, which is substantially free of Cd, Tl and Pb. The chalcogenide glass according to claim 1 or 2, wherein the infrared absorption edge wavelength at a thickness of 2 mm is 20 μm or more.