JPS6350295B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an infrared transmitting glass made of fluoride and having excellent optical properties. Glasses whose main components are zirconium fluoride or hafnium fluoride are attracting attention as materials for infrared optical components and infrared transmission paths.This type of glass can transmit infrared rays up to 8 μm, but it scatters. is large, which poses a problem for optical applications such as those mentioned above. For example, hafnium fluoride and/or zirconium fluoride is in the range of 48 to 70 mol%, and at least one of the following is selected from 10 to 35 mol% of barium fluoride, yttrium fluoride, fluorides of lanthanide elements, and thorium fluoride. Stable glass contains 1 to 8 mol% of at least one fluoride, 0 to 30 mol% of at least one fluoride selected from fluorides of alkali metal elements, and 0 to 8 mol% of aluminum fluoride. However, since all of the glasses with these compositions cause strong scattering phenomena, it is difficult to put them into practical use as materials for the optical components and optical transmission lines mentioned above. In view of the above problems, the present invention aims to reduce scattering in this type of infrared transmitting glass by adding indium fluoride to the glass, and its characteristic structure is as follows. be. That is, the infrared transmitting glass according to the present invention contains hafnium fluoride and/or zirconium fluoride.
~70 mol%, 10 to 35 mol% of barium fluoride, 1 to 8 mol% of at least one fluoride selected from yttrium fluoride, fluorides of lanthanide elements, and thorium fluoride, and an alkali metal. It is characterized by comprising 1 to 30 mol% of at least one fluoride selected from elemental compounds, 1 to 8 mol% of aluminum fluoride, and 0.01 to 5 mol% of indium fluoride. In the case of the present invention, a glass system that does not contain indium fluoride has the above-mentioned infrared transmittance and thermal stability, and by adding indium fluoride to this glass system, indium fluoride can be The light scattering intensity is reduced to about 1/100 compared to a glass system that does not contain it. Indium fluoride can be added to the fluoride glass by adding indium fluoride to the raw material mixture, or by decomposing indium oxide, hydroxide, carbonate, etc. A method is adopted in which an indium compound that produces 1 is mixed into a raw material together with a fluorinating agent such as acidic ammonium fluoride, and the raw material is then melted into glass. The amount of indium fluoride necessary to suppress the scattering phenomenon is based on all the components making up the above glass.
The content is 0.01 mol% or more, and if it is less than 0.01 mol%, the scattering phenomenon cannot be sufficiently suppressed. It can be said that the amount of indium fluoride is preferably about 0.1 to 2 mol %, but the amount may be increased arbitrarily as long as it does not adversely affect the physical properties of the glass. However, if the amount of indium fluoride exceeds 5 mol%, the glass tends to become unstable.
The upper limit of this is practically 5 mol%. Next, specific examples of the present invention will be described. Examples Each fluoride of a predetermined element was used as a glass raw material, and these were placed in a platinum crucible and melted to produce various glasses having the compositions shown in the following table.

[Table] The glasses in each example shown in the table were thermally stable and could be made into large lumps of glass, and could be processed into optical fibers without crystallization. Of course, in each of the Examples, there was no tendency for light scattering, and they had excellent infrared transmission characteristics up to long wavelength infrared rays of about 8 μm. In addition, in the above example, the amount of hafnium fluoride combined with zirconium fluoride is 0 to 6 mol%.
However, in the present invention, the amount in combination with zirconium fluoride may be greater than this as long as it is 48 to 70 mol%, and the amount in combination with zirconium fluoride may be greater than this.
It may be 48 to 70 mol%. Similar effects can be obtained in this case as well. In the above embodiments, yttrium fluoride, gadolinium fluoride, and lanthanum fluoride are cited as examples of at least one fluoride selected from yttrium fluoride, fluorides of lanthanide elements, and thorium fluoride. However, in the present invention, fluorides of other lanthanide elements may be used, and thorium fluoride may also be used. Even in this case, the same effect as described above is obtained. As explained above, the infrared transmitting glass having the structure characterized by the present invention has stable physical properties and very little scattering of light, and is therefore suitable as an infrared optical component and a material for an infrared transmission line. Become something.

Claims (1)

[Claims] 1 Hafnium fluoride and/or zirconium fluoride 48-70 mol% and barium fluoride 10-35 mol%
and 1 to 8 mol% of at least one fluoride selected from yttrium fluoride, fluorides of lanthanide elements, and thorium fluoride, and at least one fluoride selected from fluorides of alkali metal elements. An infrared transmitting glass comprising 1 to 30 mol% of fluoride, 1 to 8 mol% of aluminum fluoride, and 0.01 to 5 mol% of indium fluoride.