METHOD FOR PRODUCING LARGE-SIZED WORKPIECES OF VOLUME-HOMOGENEOUS QUARTZ GLASS Russian patent published in 2022 - IPC C03B20/00 

FIELD: quartz glass production.

SUBSTANCE: invention relates to the production of quartz glass, the characteristics of which meet the requirements regarding the homogeneity of the material in terms of refractive index in the manufacture of large-sized blanks with a diameter of up to 1000 mm. The method consists in the fact that parts with a high concentration of silicon dioxide are melted in a crucible, while raw materials from high-purity silicon dioxide with a purity of at least 99.999% are used as melted parts. Before melting in the crucible, the parts are melted in a continuous furnace, obtaining measuring rods cut to a measured length equal to the thickness of the future workpiece. Measuring rods are placed in a melting crucible, orienting the rods vertically with their longitudinal geometric axes, ensuring that the cavity of the crucible is filled in the range of 85-95%. After filling the cavity of the crucible, it is placed in the melting chamber, the cavity of the crucible is evacuated, removing air from it, the temperature of the melting chamber is brought to 1800°C at a rate of not more than 100-150°C per hour. When the set temperature is reached, the process of evacuating the crucible cavity is stopped and the melting chamber is filled with inert gas, maintaining the gas pressure in it at least 25 atmospheres, withstanding the excess gas pressure at a temperature of 1800°C for no more than 2 hours. Then the temperature in the melting chamber is reduced to 1200°C and the pressure in it is reduced to atmospheric, followed by cooling the crucible to room temperature, thus obtaining a workpiece.

EFFECT: ensuring high volumetric uniformity of large-sized optical blanks with a difference in refractive indices ΔN≤1,0×10⁶.

3 cl