DD141973A3 - OPTICAL GLASS - Google Patents

Abstract

Optical glass with refractive indices n,> 1, 675 and Abbe numbers V,> 54. It is necessary to produce high refractive and ablative optical glasses with minimal La, O, contents in order to reduce raw material costs and at the same time increase the crystallization properties of the glasses design that a production and processing is possible even after continuous processes as a mass glass. The novel glasses consist of

Description

The invention relates to optical glass with refractive indices n _e > 1.675 and Abbezahlen v _e > 54, which is suitable for production as a cost-effective mass glass and can be further processed into a variety of optical components that are used in scientific instrumentation _e

Characteristics of the known technical solutions ; It is known that many optical glasses can be derived from the group Lanthankrone from the quaternary system La _P 0o- BaO BpO ^ nSiOp. Depending on the combination of these oxides and the addition of other compatible components, optical glasses with widely differing physical and chemical properties may be melted, which require different manufacturing and processing technologies or require differing costs. However, these glasses consistently have a relatively extreme optical quality Position, hc high crushing and Abbezahlen, which is especially known from the patents of BED JTr, 2521212 and 2500378, is achieved by a high proportion of lanthana in the glass · The DT-03 2521212 claims optical glasses with refractive indices greater 1.64 and paying off

at least 53 j i ^m essentially of four components La ₂ Oo, BaO, B ^ CU and SiO ₂ and also to contain additions of other oxides or divalent ZrOp and SnO. ₂ It is stated that to achieve refractive indices greater than 1.67, a La content of ^ v * = 15 mass% and refractive indices greater than 1.68, a La ₂ 0o content of ^ = 20 mass% is required ·

Example No. ₀ 1 of Table 1 shows the state of the art that 26.2 mass % La ₂ O ₃ in the glass

must be introduced to η = 1 _? 682 and ν = 54-, 6

4-0 ie _# to realize an optical position corresponding MAESSEN the erfindungsge- \, ₀ Since the La ₂ Oo raw materials are very expensive in relation to the other glass raw materials, due to their use very high batch costs. In DT-OS 2521212, further

Said 4-5 out that to achieve a high chemical resistance 18-36 wt% SiO ₂ and not more than 4-5% by weight of BaO must be included in the glass or may ₀ This information limiting concentrations .Can not, however, be regarded as absolute and are only valid for certain concentrations of the other components present in the glass, ie they depend on the content of B ₂ Oo, La ₂ Oo etc. In DT-OS 2500378, optical glasses with 'η =: 1.66-1.69 and v ^ 53' which are made of La ₂ Oo, BaO,

B ₂ Oo, SiO ₂ , BnO ₂ and ZrO ₂ are claimed. Examples No. 2 and No. 3 of Table 1 again show that high lanthanum oxide contents of 16.6 and 21.2 mass % are necessary for the realization of n »1.68 and v _e = 54 ^ 6. The DT-OS

60 25ΟΟ378 claims high BaO contents up to 50% by weight, without, however, proving them by examples

As another example of the prior art, in Table 1 under No. 4, there is listed a commercially available optical glass made of ZrO ₂ .

ft *

Ooi BaO, BpO. ~ And SiO ^ and to achieve η = 1.681 and ν _Ω = 54.7 a La ₀ Cu GeImIt of 14.0 mass contained ^

All glasses discussed have similar, but nevertheless different, syntheses to achieve an extreme optical position and other special properties. "Together they have the disadvantage.

that they contain relatively expensive La ₀ Oo. As for adjusting the same optical position La difference Liehe _o 0o amounts used v / ground, it is seen that the La ^ Oo content has not been minimized. The graph of FIG. 1 shows that the crystallization or viscosity properties of commercial glass No. ₀ 4 of Table 1 can not be considered optimal with regard to production and processing.

Object of the invention :

The aim of the invention is to eliminate these disadvantages by new, optimized chemical compositions of optical glasses, in order to enable the production of cost-effective, high quality optical components »

Explanation of the essence of the invention;

The object of the invention is to provide new optical glasses in the. Range of lanthanum crowns with extremely high barium oxide content and minimal lanthanum oxide content, which have the following properties due to the optimization of all glass components: · - Extreme optical position, ie _e high crushing and Abbezahlen, with low Gemgegekosteru

- Low crystallization tendency ,. i.e. "small crystallization range, low liquidus temperature and low crystallization

100 speeds *

- Suitability 2, -ur production after discontinuous and continuous Schmelaverfahrea and other

200 153

closing machine processing, ie »suitability for production as a mass glass.

- Good melting behavior.

- High light transmission in the visible spectral range.

- Reduced corrosion of the refractory material platinum through the melt.

According to the invention the object is achieved in that the glass compositions

BaO 52.0 - 54 extreme | 0 Mass % Location of n _e > 1,675 and B ₂ O ₃ 17.0 - 18 A- already , 0 Mass % , -Containing <13.5 SiO ₂ 17.0 - 17 , 5 Mass % La ₂ O ₃ 12.0 - 13 , 0 Mass % Al ₂ O ₃ 0.1 0 , 5 Mass % As ₂ O ₃ 0 0 , 5 Mass % Sb ₂ O ₃ 0 - 0 , 5 Mass% exist. Ss was' surprising found that - one optical v _e > 5 with La. a °:

Mass % is reached

- The BaO content can be significantly increased with simultaneous reduction of La ₂ Ov-Anteiis and to produce new optical glasses while maintaining the ratio B ₂ O ₃ : SiO ₂ from 0.9 to 1.1 and adding small amounts of Al ₃ O ₃ which are minimized in raw material costs and are so stable to devitrification that they are suitable for mass-produced production.

the favorable ratio B ₀ O ₃ : SiO ₂ of 0.9-1 * 1, which is favorable for the reduction of the crystallization tendency, represents ^only an optimum for given values of-BaO, La ₂ O ₃ and Al ₂ O ₀ .

the replacement of the refining agent Sb ₂ O ₃ with As ₀ O ₃ causes a substantial increase in the light transmission of the glass in the visible spectral range and at the same time the platinum dissolution of the melt

• reduced by the melt.

~ '^ ζυν ι 3 j

140 exemplary embodiment;

The operation of the invention will be explained in more detail with reference to the drawing. Ss show I? Ig _e 1 is a diagram of the Abhängigice it Kristallwachstumsgesrchwindigkeit and the viscosity on the temperature and tfig · 2 is another diagram of the dependence of the spectral transmittance of the wavelength,

In Table 2, syntheses, crushing and Abbezahlen or * spectral transmittance of glass according to the invention are reproduced »Am. Example No. 1 of Table 2 shows that. even at a low IoOo content _VO n 12.7 mass %, the refractive index n. = 1.680 and Abbe number ν = 54.5 are reached. Comparing Example No. 1 with No. 4, it is clear that when using ASpO-, instead of Sb ^ O-, spectral transmittances, measured on glass samples with a layer thickness of 100 mm, of 60.0 % rises to 72.1 %. "The spectral-analytically determined content of platinum, which is introduced into the glass by the attack of the melt on the refractory material, gives a value of about 22 ppm for the glass ITr, 1 and a value for the glass Wr ₀ 4 of about 40 ppm, Figure 1 shows that z, B _e the erfindungsgeraäße glass No. 1 of Table 2 for production and processing as a mass glass is much better than the commercially available comparative glass Nr _β of Table 1 «To assess the suitability as mass glass, the crystallization and viscosity are. properties of the glasses. The crystal growth rates were determined by the KG of U, Hoff and R. Katzschmann / silicate technology 17 »1966 S _e 285 - 290 determines described, Abschrecianethode. It is in ^ m / h. specified. The viscosity * i is measured with a rotational viscometer «The viscosity ^ i, or _o . Ig- ^ is in unit of measure · poise

(1P = s1dyn sec / cm) indicated.

Curve 1 corresponds to KG = f (1/1) glass No. 1 Table 2

Curve 2 corresponds to KG = £ (J ") Glass No. 4 Table 1

• Curve 3 corresponds to Ig ^ = f '(#) Glass # 1 Table 2

Curve 4 - corresponds to Ig ^ s f (-t7) Glass No. 4 Table 1

When the glass is processed = 3-4 at viscosities of about Ig, the inventive glass No. 1 of Table 2 has _e th much more favorable than the commercial comparative .Kristallisationseigenschaf

185 glass.

FIG. 2 shows the spectral transmittance of two glasses as a function of the wavelengths of the visible spectral range at a layer thickness of 100 mm. The curve 5 characterizes the glass No. 1 of Table 2, the curve 6 corresponds to the glass No. ₀ 4 of the table It is clearly visible that the replacement of SbpO by ASoOo causes an improvement of the light transmission «

BaO 52.0 - 54.0 Dimensions B ₂ O ₃ 17.0 - 18.0 Dimensions SiO ₂ 17.0 - 17.5 Dimensions La ₂ O ₃ 12,0 - 13.0 Dimensions AIpOo 0.1 - 0.5 Dimensions Cm J ÜOaU q 0 0.5 Dimensions Sb ₂ O ₃ 0 0.5 Dimensions

2 "optical glass to point Λ characterized in that it contains as refining agent exclusively As ₂ O ₃ .

Hierzii.JLS9! Ien drawings Table 1 :

Compilation of examples of optical glasses that characterize the state of the art

Lfd, No. ₀ patent specification and glass syntheses in mass % Nr ¹ , the example BaO B ₂ O SiO ₂ La ₂ O ₃ ZrO ₂ SnO ₂

Optical layer refractive index Abbezahl

ⁿ e V ·

DT-OS 2521212 Tab, I, No. «8

DT-OS 25ΟΟ378 Tab »I, Nr * 1

Tab «I, Nr» 4

29.0 20.0 20.9 26.2 3.7 0.2 1.682 54.6

43.0 19.4 18.0 16.6 1.5 1.3 0.2 34, .9. 19.9 19.8 21.2 1.3 2.7 0.2

1.6798. 54.6 '1.6825 54.6

Commercially available optical Gla3

46.1 19.0 18.3 14.0 2.2 0.4

1,681 54.7

Table 2:

Examples of glasses according to the invention

Glass syntheses in mass %

Lfd.Hr ', BaO B _? 0 ~ SiO

Al ₂ O ₃ Optical layer Spectral trans refractive index Abbezahl mission grade

T (TZ = 436 nm) [%]

52.3 17.5 16.9 12.7

53.4-16.7 17.6 11.7

52.0 17.4 16.9 12.7

52.3 17.5 16.6 12.7

0.1 O ₉ I

0.5

0.1

0,5 0,5

0.5

1,680 1,676

1,679 1,681

55.1

72.1 70.2 71.0 60.0

Claims (1)

godfather tanspruch 1. Optical glass with refractive indices η> 1.675 and Pay off v _ö > -54 · suitable for manufacturing e as inexpensive bulk glass containing at least barium oxide, boron oxide, silicon dioxide and lanthanum oxide, characterized by the following composition