Patent ID: 7637126

Claim:
A method for producing a blank for a component of laser active quartz glass, said method comprising: a) providing a dispersion with a solids content of at least 40% by wt. which contains SiO 2 nanopowder and dopants, including a cation of one or more rare earth metals or transition metals in a liquid, b) granulation by moving the dispersion with withdrawal of moisture until a doped SiO 2 granulate of spherical porous granulate grains having a moisture content of less than 35% by wt. and a density of at least 0.95 g/cm 3 is formed, c) drying and purifying the SiO 2 granulate by heating said SiO 2 granulate to a temperature of at least 1000° C. so as to form doped porous SiO 2 granules having an OH content of less than 10 ppm, and d) sintering the doped SiO 2 granules in a reducing atmosphere so as to form the blank of doped quartz glass, wherein said sintering includes a gas pressure sintering, which comprises the following steps: aa) heating the SiO 2 granules to a melting temperature of at least 1600° C. while applying and maintaining a negative pressure; bb) holding the SiO 2 granules at the melting temperature at an overpressure ranging from 5 bar to 15 bar for a melting period of at least 30 min so as to form the quartz glass blank; cc) cooling the quartz glass blank while maintaining said overpressure.