The article presents the results obtained by coating a liquid glass solution to the substrates of optical elements, followed by their etching with an ion beam. Particular attention is turned on the surface roughness of the optical element both after the deposition of liquid glass and after etching. A film of the applied glass composition was studied using secondary ion mass spectrometry (SIMS).

The quality of surface preparation of various laser materials for the purpose of creating composite elements is studied. It is shown that the flatness of the samples should be no worse than λ/10, and the roughness - no more than 1.0 nm. Parameters of ion etching that do not lead to roughness degradation are found: Ar ions, Eion=800 eV and grazing angle θ=5º. Composite elements were created from yttrium aluminium garnet doped with ytterbium ions (Yb:YAG), as well as a magnetoactive TGG crystal with single crystals of sapphire.