DD221163A1 - HIGH-BREAKING ULTRAVIOLET AND INFRARED THROUGH OPTICAL GLASS - Google Patents

Abstract

The invention relates to high-index Bismutfluorogermanatglaeser with a refractive index ne 2.0 a UV transparency lti50 360 nm at a layer thickness d 10 mm and an IR permeability lt 80 to 5 mm at a layer thickness d 1 mm. The aim of the invention is to eliminate yellowing from Bismuthgermanatglaesern while increasing IR permeability. This is achieved according to the invention by the addition of bismuthoxyfluoride, the glasses being composed as follows: BiO1.5 0-25 mol% BiOxFy20-45 mol%, where x is 0.7-1.02 and y is 0.9-1 , 6 and the condition 2x y 3 applies to the values x and y. GeO250-65 mol% Guenstig is an addition of PbF2 to 5 mol%. These optical glasses are used in scientific instrumentation for use in optical imaging systems in a large wavelength range.

Description

Title of the invention

High refractive ultraviolet and infrared transparent optical glass

Field of application of the invention

The invention relates to an optical glass which, with a refractive index χι μ 2.0 and a Abbezahl V ** 20, a UV transmission ee

A _C j ₅₀ (ds 10 mm) 5: 360 nm and has a permeability (d = 1 mm) to "5 / um, which is used in scientific instrument construction

Characteristic of the Known Technical Solutions High-index optical glasses from the field of heavy and / or heavy-duty guns with refractive indices η << 2.0 are based on the glass forming systems PbO-GeO ₂ (JA Topping, IT Harrower, MK Murthy, J. Amer. Soc. J., 7, 210 (1974)), PbO-Bi ₂ O-GeO ₂ (EM Miljukov, SP Lunkin, SS Malzewa, Fiz. Khim. Stekla £, 612 (1979)), Tl ₂ O-Bi ₂ O ₃ -GeO ₂ (K. Nassau, DL Chadwick, J. Amer. Ceram Soc., J6 £, 197 (Ι9δ2)) and Bi ₂ O ₃ -SiO ₂ -GeO ₂ (JA Topping, N. Cameron, MK Murthy J. Amer. Ceram. Soc. ^ 2, 518 (1974)) and as tellurite glasses with TeO ₂ as a glass former (DDR-P 158176). Their transmission in the ultraviolet spectral range is limited due to the absorption behavior of the heavy metal cations surrounded by the oxide particles of the glass structure, and usually a more or less pronounced yellowing is observed. This also applies to the glasses of the system Bi ₂ O ₃ -GeO ₂ or (BiO ₁ (GeOp) ₁ , which can be prepared up to a bismuth oxide content of χ = 0.46 A glass of the composition Bi ₂ Ge ^ Og ( x = 0.2)

indicates ζ. B. a pure transmission of $ 50 for the wavelength ¹ X =. kl8 on, and in the infrared, the transmission limit of about 4.5 / um, due to a low residual water content in the molten glass, limited by an intensity-weak OH-valence vibration band in part. Single crystals of the compound Bi ₂ Ge ^ Og (BC Grabmaier, S. Haussühl, P. Klüfers, Z. Krist. 149 , 261 (1979)) or Bi ^ Ge ₃ O ₁₂ (R. Nitsche, J. Appl. Phys. ^ 6, 2358 (1965)), however, can be obtained colorless and without OH-gfuppenbedingte absorption in the infrared. The yellowing of the glasses is apparently caused by the high polarizability of a proportion of the oxide particles in the structural framework of the glass.

Object of the invention

The aim of the invention is to increase the transmission properties in the UV and IR spectral range through the use of suitable additional components to high-index Bismutgermanatgläsern to tap into the use of optical imaging systems in the broadest possible wavelength range.

Explanation of the essence of the invention

The object of the invention is to eliminate the yellowing occurring in high-index Bismutgermanatgläsern by the addition of components which have a lower polarizability and at the same time further reduce the residual water content in the glass, however, while maintaining the high refractive indices.

According to the invention the object is achieved in that the glasses

BiO _{1 5} 0 - 25 BiO ^ F 20 - 45 πκ> 1- #, where χ = 0.7 - 1.02 and y = 0.9-1.6 and the condition 2x + y = 3 for the values χ and y,

GeO ₂ 50 - 65 mol ~ / l are composed.

In addition, the glasses may contain other components which increase the number of refractive index components, the addition of PhF ₂ to 5 % by weight being favorable

 By this composition range of the invention

optical glasses with high refractive indices η & 2,0 with simultaneously high transmission at the short-wave boundary of the visible spectral range and in the infrared range of the spectrum. At higher bismuth oxide or Bismutoxyfluoridgehalten than specified only strongly colored glasses are obtained or exceeded the glass formation limit. If the amounts of bismuth oxide or bismuth oxyfluoride added are below those listed

Limits, then the glasses have refractive indices η <2.0. 'e'

Exemplary embodiments

Table 1 shows examples (Nos. 2-5) of the glasses according to the invention for melt formulations of about 100 g. In addition to the glass compositions, the refractive index (n), Abbe number (V), the re- transmission at Λ = 50 % and a layer thickness d = 10 mm, the permeability / £ 80 ^c ß> at a layer thickness of d ~ 1 mm in infrared spectral range and the transformation (T _g ) and crystallization temperatures (T-,) indicated. For comparison, the properties of a yellow-colored bishnutgerraanate glass (# 1) are listed.

Table 1 No. Composition ^Bi0 1.5 GeO ₂ bIOF ⁿ e 19 * 50 mn ^ 80 4 ° c ^{G T} K ⁰ C 40 60 21.8 28.7 1 BiO ₁ ^ ₅ GeO ₂ 27.4 2.07 23 22 418 5, 2 468 570 14.9 12.9 63.3 58.4 ^BiO O, 85 20 2 3 22.9 49.7 38.1 1,985 2,00 360 390 434 393 574 498 504 4 PbF ₂ GeO ₂ 2,024 21 400 4 385 507 4.8 57.1 ^F 1.29 5 2,001 380 5

In the drawing, the transmission spectra of the glasses (Nos. 1-5) are shown.

I

The glasses are made as follows:

A mixture of bismuth oxynitrate and germanium dioxide

is subjected to a sintering reaction by slow heating to 800 ^° C. and a four-hour hold at this temperature, and after homogenization BiO P is added. The glass batch prepared at this stage is melted at 900 ° -950 ° C., briefly purged at 1000 ° C. and, after a melting time of 20-30 minutes, the glass melt is heated at temperatures of 950-1000 ° C. Poured preheated mold and cooled to room temperature.

Claims (2)

1. High-refraction ultraviolet and infrared-transmitting optical glass having a refractive index of n_ * 2.0, which consists at least of BiO _{1 K} and GeO ₉ , characterized in that it contains at least BiO F and follows the mixture as follows: Composed approach: BiO / 0-25 mol-56
•>_> BiO F 20-45 mol- #, where χ = 0.7 - 1.02 and χ y y = 0.9 - 1.6 and the condition 2x + y = 3 holds for the values χ and γ , GeO ₂ 50 - 65 mol- £ 2. High-refractive ultraviolet and infrared-transmitting optical glass according to item 1, characterized in that the batch mixture additionally contains up to 5 mol- $ Pb ^ o. "For this 1 page drawings"