JPH02283635A - UV Transparent Fluorinate Glass - Google Patents

Abstract

PURPOSE:To provide the title glass having high light transmissivity in short wavelength region, easy to produce, made up of P2O5, Al2O3, BaO, AlF3, MgF2, CaF2, SrF2, BaCl2, BaF2 and NaF at a specified molar ratio. CONSTITUTION:The objective glass made up of (A) 0.5-8mol% of P2O5, (B) 0.1-2mol% of Al2O3, (C) 0.5-7mol% of BaO, (D) 29-42mol% of AlF3, (E) 5-13mol% of MgF2, (F) 15-30.5mol% of CaF2, (G) 10-22mol% of SrF2, (H) 0.5-16.5mol% of BaCl2, (I) 0-11mol% of BaF2 and (J) 0-7.5mol% of NaF. To produce the present glass, the above raw materials are mixed at a specified ratio and melted at ca. 900-1100 deg.C followed by casting in a conventional way. The present glass has high light transmissivity over a short wavelength region of 200 to 300nm, thus being suitably used for various kinds of optical instruments, etc., to be used over said short wavelength region.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fluorinate glass having high light transmittance in the short wavelength range from 200*m to 300 mm. The ultraviolet-transmissive fluorinate glass of the present invention is useful for various optical devices used in the short wavelength region, optical parts such as lenses and prisms of medical devices, and fibers as light guide paths.

[Prior Art] In recent years, advanced technology that uses extremely short wavelength light, such as that seen in semiconductor manufacturing equipment, is being applied to films. In connection with this, there is a growing demand for optical materials that can be used in extremely short wavelength regions. Silica glass is well known as a glass material that has high transparency in the short wavelength region. In addition, alkali halides and alkaline earth halides, which are crystalline in other materials, have very good transmittance due to their material properties, but these crystalline materials have low optical homogeneity and chemical Because it is not durable enough, it is difficult to use as optical components such as lenses in high-performance, high-precision optical systems. Other UV-transmitting glasses other than quartz glass include calcium phosphate glass, borate glass, and borosilicate glass. Salt-based glass is used.

These oxide glasses are based on the idea of reducing so-called non-bridging oxygen, which has a large effect on the absorption of ultraviolet rays. However, these oxide glasses do not have sufficient transparency in the ultraviolet region having a wavelength of 300 am or less, and also have a major problem in optical homogeneity. Furthermore, in such glasses, the influence of heavy metal ions that absorb in the ultraviolet region is significant, and there are also problems with their removal.

Fluorinate glass is considered to be the most excellent glass among YG glasses with optical homogeneity and good UV transmittance. Since this glass contains a large amount of fluorine, which absorbs ultraviolet light at shorter wavelengths than oxygen ions, it is expected to have much better ultraviolet transmittance than oxide glass. However, it is very difficult to obtain optical homogeneity in fluorinate glass containing a large amount of fluorine, and there are only a few glasses that can be produced on an industrial scale at present, as disclosed in Japanese Patent Application Laid-Open No. 63-INNi. Fluorinate glasses, such as those found in However, even in glass containing large amounts of fluorine ions, wavelengths of 300
Sufficient transmittance cannot be obtained in the nm or less region, and therefore the development of glass materials with better ultraviolet transmittance is thought to become of great importance in the future.

[Problems to be Solved by the Invention] The object of the present invention is to reduce the oxygen ion content compared to conventionally known fluorinate glasses, and to prevent metals from being mixed into the glass melt from the precious metal container during melting. The purpose of the present invention is to provide a new ultraviolet-transmitting glass that is resistant to crystallization and can be produced industrially.

[Means for solving the problem] Taking into full consideration the above points, the present inventors have developed a P2O
5-Al2O3-8JO-＾IF3RP2 1]*cl
In the glass system based on z (R=Mg+Cs+Sr), we have found a very stable fluorinate glass that has high light transmittance in the short wavelength range from 200nl to 30On11.

P2O5 is 0.5 to a in mol% as a glass component ratio,
0%, Al2O, 01-20%, BaO 02-7
0%, ^lF3 is 29.0-42.0% 1M section F2 is 5
．． 0 to 13.0, ClF3 15.0 to 30.5%,
5rP2 is IQ, o-22,0%, B*C12 is 05
-16.5%, BaF2 is in the composition range of 0 to 11.0%, and NiF is in the composition range of 0 to 7.5%. .

P2O5 is a component involved in glass formation, but 80%
When the amount is more than 05, the ultraviolet transmittance deteriorates, and when it is less than 05 tsuta, glass formation becomes difficult.

Al2O3 works to increase the viscosity of glass melt, but
Outside the above range, it brings about the same effect as P2O5.

LO is a necessary component for lowering the liquidus temperature, but if it is outside the above range, the ultraviolet transmittance decreases.

^lF3 is a necessary component for glass formation and as a source of fluorine ions, but outside the above range it increases the crystallization tendency of the glass.

When M(F2) exceeds 130%, the crystallization tendency increases, and when it is less than 5.0, the melting temperature becomes high, causing volatilization of the components.

When C*Fz is outside the above range, the crystallization tendency increases.

If BaF2 exceeds 22.0%, it tends to crystallize; if it is less than 10.0%, the liquidus temperature increases, the viscosity decreases, and the homogeneity of the glass deteriorates.

By introducing BJC12 into fluorinate glass, the range of vitrification is greatly expanded, and it has the effect of reducing the oxygen ion concentration in the glass.In addition, BaC1□ improves the wettability with platinum, which is the melting container. However, if it exceeds 165%, the crystallization tendency increases, and if it is less than 0.5%, the above effect cannot be obtained.

When B&F2 exceeds 110%, it is difficult to obtain glass.

LP is a component that lowers the melting temperature of the glass melt and has a particularly large effect on volatilization, but it has a 7.5
%, crystallization tends to occur.

Both alkali metal and alkaline earth metal fluorides are used for the purpose of improving the meltability of glass.

According to the present invention, the glass within the above range has a wavelength of 10II.
It has high light transmittance in the short wavelength range from n to 30 ha, can be obtained relatively stably as glass, and can be produced on an industrial scale.

This glass can be easily produced by mixing raw materials in a predetermined ratio, melting at a temperature of 900 to 1100°C, and performing normal casting.

[Example] Examples will be described below with reference to tables. Example 1 in Table 1
and glass compositions of Examples 2 to 8 are shown.

Example 1 Using the compounds shown in Table 2 as starting materials, a mixture of heavy fik\A compound such as N001 was heated to qu~1100°C.
It was melted at a temperature of 100 mL and poured into molds made of iron or carbon. The glass was obtained relatively stably.

Figure 1(a) shows the transmittance curve of the glass obtained here,
(c) shows the transmittance curve of Comparative Example I.

Examples 2 to S Glasses were obtained by melting mixtures of Nos. 2 to 8 in Table 2 at weight ratios in the same manner as in Examples.

FIG. 1(b) shows the transmittance curve of Example 2.

[Effects of the Invention] The ultraviolet-transmitting fluoric acid glass of the present invention can be obtained very easily and can be produced on an industrial scale, so it can be used in various optical devices or medical devices used in the short wavelength region. It can be used for optical components such as lenses and prisms, and fibers as light guides.

[Brief explanation of drawings]

In Figure 1, (a> is the transmittance curve of Example 1, (b) is the transmittance curve of Example 2, and (c) is Comparative Example 1. Patent applicant Sumita Optical Glass Co., Ltd. Table 1 ( 100%)

Claims (1)

[Claims] P_2O_5 is 0.5-8.0% in mol%, Al_2O
_3 is 0.1-2.0%, BaO is 0.5-7.0%,
AlF_3 is 29.0-42.0%, MgF_2 is 5.
0-13.0%, CaF_2 15.0-30.5%,
SrF_2 is 10.0-22.0%, BaCl_2 is 0
．． 5-16.5%, BaF_2 0-11.0% and N
UV-transparent fluorophosphate glass consisting of 0-7.5% aF.