Patent ID: 7256425

Claim:
A method of producing plane-parallel structures of SiO y , wherein 0.95≦y≦1.8, comprising the steps: a) vapour-deposition of a separating agent onto a movable carrier to produce a separating agent layer, b) vapour-deposition of an SiO y layer onto the separating agent layer, c) dissolution of the separating agent layer in a solvent, d) separation of the SiO y from the solvent, in which method the SiO y layer in step b) is vapour-deposited from a vaporiser containing a charge comprising a mixture of Si and SiO 2 , SiO y or a mixture thereof, the weight ratio of Si to SiO 2 being in the range from 0.15:1 to 0.75:1, and step c) being carried out at a pressure that is higher than the pressure in steps a) and b) and lower than atmospheric pressure.