Schott Ag

Thorsten Doehring

Ina Mitra

Hauke Esemann

Ralf Jedamzik

Eva Hoelzel

Silke Wolff

Burkhard Speit

Volker Seibert

Thomas Westerhoff

Hans-Joachim Nowak

Martin Schaeffer

In a substrate, particularly in a substrate for a mirror support, in which recesses are introduced in one surface, preferably in the back side of the substrate, as a result of which, in particular, bridging pieces are defined between the recesses, in order to achieve the situation that despite a reduced weight, a high rigidity still remains, which means only a slight sagging after its correct uptake in a holding device provided for it, it is provided that at least one first portion of the bridging pieces has a width that is different than a second portion of the bridging pieces.

Substrate for a mirror support with reduced weight as well as mirror with reduced-weight mirror support

The space glass has a composition, in wt. % based on oxide content, of: SiO, 5-65; BO, 0-40; AlO, 0-12; PbO, 25-50; NaO 0-8; KO, 0-20; &#x3a3; alkali metal oxides, at least 0.25; and at least 0.1 wt. % of a total amount of three or more doping agents selected from CeO, MoO, BiO, WO, AgO, SnO, SbOand AsO. In addition, it contains one or more of the following doping agents in the following amounts: at most 1 wt. %, CeO; at most 0.02 wt. %, AsO; at most 0.3 wt. %, SbO; and at most 0.5 wt. %, SnO. Light-weight optical systems for space are made from it, because of its high radiation resistance. A preferred process for making space glass includes melting the oxide starting ingredients at 1050&#xb0; C. to 1200&#xb0; C. to form a melt and refining the melt at 1230&#xb0; C. to 1350&#xb0; C.

Lead-containing space glass, its production and its use

The space glasses have a composition, in wt. % based on oxide content, including SiO, 12-45; BO, 0-4; AlO, 0-4; TiO, 0-5; PbO, 50-82; NaO, 0-4; KO, 0-8; and at least 0.1 wt. % of a total amount of at least three doping agents selected from CeO, MoO, BiO, WO, AgO, SnO, SbOand AsO. Light-weight and space-saving optical systems for outer space applications can be made with these space glasses, which have high UV- and VIS-transmittance and high transmittance stability, because of their high radiation resistance based on their dopant content. A preferred process for making the space glass includes melting the above-stated oxide ingredients in a quartz crucible at 1050&#xb0; C. to 1200&#xb0; C. to form a melt and refining the melt at 1230&#xb0; C. to 1350&#xb0; C.

Lead-containing space glass, its production and use

An optical glass for the manufacture of large transmission optics, such as lenses having a thickness of 100 millimeters or more, comprises 35 to 70 wt.-% SiO, 17 to 35 wt.-% AlO, 3 to 17 wt.-% PO, 0 to 6 wt.-% LiO, 0.5 to 4 wt.-% MgO, 0.5 to 3 wt.-% ZnO, a maximum of 1 wt.-% CaO, a maximum of 0.5 wt.-% BaO, 0.5 to 6 wt.-% TiO, 0.5 to 3 wt.-% ZrO, 0 to 1 wt.-% NaO, 0 to 1 wt.-% KO, a maximum of 1 wt.-% of refining agents (AsO, SPO) and a maximum of 500 ppm of other contaminants. The glass composition may be equal to the composition of the glass ceramic Zerodur&#xae; and allows to manufacture large transmission optics in a cost-effective way, has a maximum of transmittance which is in the range of a He&#x2014;Ne lasers and has a CTE of about 3&#xb7;10/K.

Large transmissive optical component

An optical glass for the manufacture of large transmission optics, such as lenses having a thickness of 100 millimeters or more, comprises 35 to 70 wt.-% SiO, 17 to 35 wt.-% AlO, 3 to 17 wt.-% PO, 0 to 6 wt.-% LiO, 0,5 to 4 wt.-% MgO, 0,5 to 3 wt.-% ZnO, a maximum of 1 wt.-% CaO, a maximum of 0,5 wt.-% BaO, 0,5 to 6 wt.-% TiO, 0,5 to 3 wt.-% ZrO, 0 to 1 wt.-% NaO, 0 to 1 wt.-% KO, a maximum of 1 wt.-% of refining agents (AsO, SPO) and a maximum of 500 ppm of other contaminants. The glass composition may be equal to the composition of the glass ceramic Zerodur&#xae; and allows to manufacture large transmission optics in a cost-effective way, has a maximum of transmittance which is in the range of a He&#x2014;Ne lasers and has a CTE of about 3&#xb7;10/K.

A lithium-aluminosilicate glass ceramic is transformed by a suitable heat treatment into a glass ceramic comprising at least 80 vol.-% of keatite mixed crystals. This may be utilized for the preparation of optical or mechanical high-precision parts having a high temperature resistance, a good stability and compatibility with components consisting of metals having a small coefficient of thermal expansion based on nickel and iron, such as Invar&#xae;.

Lithium-aluminosilicate glass ceramic with high keatite content and structural member made thereof

A process for forming glass or glass ceramics is disclosed, wherein a glass ceramics form () is made from a starting glass by molding, which is transformed by a heat treatment into a keatite glass ceramic comprising predominantly keatite mixed crystals. With such a keatite glass ceramics form () formed bodies can be prepared from blank parts by sagging under gravity force at a temperature above the glass transition temperature of the blank part () (FIG.).

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Mainz, Germany

Thorsten Doehring