DD153202A1 - OPTICAL FILTER GLASS - Google Patents

Abstract

The invention relates to a novel composition of matter for the production of optical filter glasses with a steep absorption edge towards the boring spectral range. These filters are represented by the BG 18 glass type. The object of the present invention is to produce an optical filter glass having similar optical properties to those of BG18. The use value, with respect to weathering and crystallization resistance, should be increased significantly. According to the invention, the object is achieved in that a phosphate glass based on metaphosphates with a defined composition and copper oxide addition can be prepared. Thus, in addition to the glass properties above all melting technical improvements are achieved. Such filter discs find e.g. in the laser technology and in the scientific Geraetebau an application.

Description

The invention includes phosphate glass optical filter glasses with steep absorption edge towards the long wavelength spectral region, the color being caused by copper ions.

For the use of optical filter glasses, for example in Pilterkombinationen ject glasses with a steep Äbsorptionskante to short-wave spectral range towards j such glasses with a steep absorption edge as possible to the long-wave spectral range needed. Sin example of such -optical filter glasses' represents the optical filter 18 is glass BG _$ which the part of the visible spectral range with wavelengths longer than 5 ^ 0 nni absorbed and the adjoining part of the infrared spectral selectively strong "

Optical filter glasses from the BG 18 "3" are used in laser technology as filters in scientific instrument construction and as infrared radiation absorbing windscreens in exposure apparatuses.

Phosphate glasses are to z \ i shorter wavelengths permeable than corresponding netswerkänclereroxidhaltige silicate and borate glasses. The use of phosphate base glasses for certain optical filter glasses is based on

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on this high transmission for the short-wave visible and the subsequent part of the ultraviolet spectral range. · -

Previously known optical filter glasses with steep absorptive

• tion edges to the long-wave spectral range, 'for example optical filter glasses of BG 18 type, contain about 75 mass% Pp ^ B ^{un (} ^ · ^ iS ^ mass% AIpO .. mainly alkali and alkaline earth oxides and CuO. Such glasses are described in Japanese Patent 92 179 73 (and corresponding U.S. Patent 3,923,527 and BED-OS 2,408,380), as well as in United States Patent Nos. 48-92,178 and 48-92,179. and alkaline earth metal content, hitherto known optical filter glasses of the BG 18 type have a high tendency to crystallize and a low weathering resistance The high crystallization tendency of known glasses of the BG 18 type only permits small-volume production of these glasses that result from increased material and energy consumption as well as increased workload.

The low weathering resistance of known glasses of the BG 18 type make these glasses very susceptible to weathering in their practical application. "To protect against weathering of the glasses, they must be tempered by a suitable protective layer or protected against direct moisture attack by means of appropriate windscreens Increase of Effort and Associated Costs If the glass components as oxides or their suitable precursors are suspended in liquid phosphoric acid for known glasses of BG 18 type for batch preparation, the water present in large quantities in the batch results in a strong and uncontrollable evaporation of mainly Phosphoric acid and / or phosphorus (V) oxide in addition to boric acid, which causes considerable difficulties in terms of Arbeitsschutz and environmental protection In addition, resulting from the strong evaporation of one of its components from the molten glass Komogenitätsp roblems.

The object of the invention is an optical filter glass with optical absorption properties similar to BG'18-TYP filter glasses but with a higher utility in terms of less streaking, improved homogeneity and good weathering resistance and environmental pollution ver * repaired. ,

The reduction of crystallization tendency of the glass according to the invention over previously known optical -. Filter glasses of BG 18 ~ type allows a more economical production "This is achieved" that the volume of the glass melt can be significantly increased due to the reduced crystallization tendency of the glass according to the invention.

The use value is increased by a higher weathering resistance of the glass according to the invention compared to previously known glasses of BG 18- (DyP.) This results from the omission of the surface compensation required by BG 18-3-3rp in previously known glasses or protection by windscreens At the same time costs are saved, "the application γ / ird more economical., As compared to procedures that go out of suspension Gegegeigen some efficiency enhancing technological simplifications in the preparation of mixtures and glass melt are sought" The use of metaphosphates and other phosphates reduces the evaporation of batch components in the glass melt This results in much more homogeneous glasses, and handling of solid matter is easier with respect to occupational safety than with suspension mixtures, and at the same time reduces environmental impact.

Explanation of the essence of the invention

The technical effect of the invention is that by incorporating Eupfe; e (U) -oxide as coloring. Means in a phosphate glass of the system -P ₀ (V

Properties succeeded. The glasses according to the invention have steep absorption edges towards the long-wave spectral range. At the same time, however, they are distinguished by increased crystallization stability and great weathering resistance compared to previously known glasses of the BG-IS type. "Copper (II) ions can undergo different coordination in phosphate glasses. The position and the shape of the absorption band of the copper (II) ions are determined by these different coordinations. * With the incorporation of copper (II) oxide into the glass according to the invention, it was possible to adjust the coordination ratios Porm the absorption band of copper (II) ions in the base glass was obtained according to the desired optical absorption behavior of the glasses according to the invention.

Similar glasses from the basic glass system P ₂ Oe-AIpO ₀ -ZnO-MgO-B ₂ O-are used for a heat protection glass (DDR-W? 43 207), but with these glasses go through the incorporation of iron oxide goose other objectives in terms of optical absorption properties achieved _s as in the present case.

By incorporating up to 5% by mass of SiO ₂ in the glasses according to the invention, the glass structure is further solidified. This becomes visible, inter alia, by an increase in the transformation temperature of corresponding glasses. The solidification of the glass structure leads to a further increase in the weathering resistance _s without significantly changing the optical absorption properties. '·

The crystallization tendency of the glass according to the invention from the base glass system Al ₂ O ₀ -MgO-ZnO-P ₂ OJr-BpCU is lowest at BgO-y contents at the upper limit of the stated composition range. However, this results in a significant reduction of the transmission in the spectral range below 400 nm. The lowering of the P ^^ content likewise leads to a significant reduction in the transmission of the

60

Glasses according to the invention in the spectral range below 400 mmol. The complete or partial incorporation of the coloring agent copper (II) oxide as nitrate into the glass according to the invention results in an increase in the transmission in the glass. Spectral range below 4Ό0 nm. This increased transmission absorption is caused by the Mtrat induced oxidation potential of the glass melt. The use of preferably metaphosphates and phosphates other than mixed raw materials for the glass according to the invention avoids the use of phosphoric acid in the preparation of suspension granules. This entails a sharp decrease in the evaporation rate of mainly phosphoric acids (and / or phosphorus (Y) oxide). sovrLe Borsäures resulting u _e a _e results in a reduced environmental impact. This reduced evaporation of mixed components leads on the same side to more homogeneous glasses.

Table 1 shows some embodiments of the composition of the inventive glass. The transmission curves belonging to the glass according to the invention, corresponding to the composition for glass 1, glass 3 and glass 5, are shown in FIG. The Trans mission curve of the glasses not shown in Figure 1 is substantially identical to the three curves shown, More detailed information can be found in Table 2, where in addition to the transmission for 5 wavelengths di © fililenlänge with the Heintransmissionsgrad ^ 5 κ O ₅ 5 of the steep absorption edge to the long-wave spectral range and the "steepness" of this edge - pressed out of ~ as the wavelength difference between the wavelengths with -ö ~ Qj3 and Ό = O _? 7). If these values are used to characterize the position of the absorption edge towards the long-wave spectral range, the wavelengths with their energy transmittances / J? s 0 _s 3 and Ό κ Ό _# Ί are given for absorption in the short-wave spectral range * For comparison, the values for a

20 9 A 60

known glass of BG 18 type indicated. The values are valid for layer thicknesses of 1 mm * *

The weathering resistance (according to CDGL 22 149) is determined for the glasses 1 to 6 with class 1. On the other hand, the weathering resistance for a known glass of BG Ί8-Φ ^ ρ can only be assigned to class 3. "As a measure of the crystallization stability, the mean linear crystallization rate V is given. It amounts to 2.50 mm * h for known glasses of the BG "IS type V s. For the glass according to the invention, corresponding to the compositions for the glasses 1 to 6 _$ , a mean linear crystal growth rate results

-1

is equal to or less than V s O _s 25 mm "h. This value is of the same order of magnitude as in the case of glasses which can be produced without conventional production. The glasses according to the invention also have a larger (temperature difference between maximum crystallization and transformation temperature Tg and a lower partial dependence of toughness than previously known glasses of BG 18-0? Yp. This achieves fundamental improvements in terms of melting and processing technology.

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Table 2% Optical Parameters

Transmissivity

for% ie wavelengths?>, (mn)

A S 334 436 509 578 700 Ϊ , CV = 0.5) 42 360 BG 18 2 0.18 0.80 O ₉ 9O; 0 _f 66 ^ 0 _f 02 596 41 360 Glass 3 0.16  0> 7S 0 * 90 0.66 0.00 594 41 355 Glass 4th O ₅ 17 0.84 0 ₉ 92 0.64 0.01 590 41 355 Glass 5 0.18 ' 0.85 0.93 0.66 0 _? 01 594 43 , 355 Glass 6 , 0 _f 20 0.78 0.90 0.66 0.03 595 40 340 Glass 0 _? 36 0.89 O _s 95 0.66 0.01 594 43 340 Glass 0 _s 40 0.87 0.93 0 _s 67 12:01 595

Claims (2)

1 _Ö Optical filter glass , characterized in that it 'hin'besitzt a steep absorption edge to the long-wave spectral range, has good weathering resistance and low crystallization tendency and from the components indicated as oxides 2 «Optical filter glass according to point 1, characterized by? the metaphosphates and other phosphates of the components and, if appropriate, the improvement of the weathering resistance SiO 2 are used as batch constituents for the G-round glass *.