CRYSTAL GROWING APPARATUS Russian patent published in 2003 - IPC

FIELD: growing of optical monocrystals by Choschralsky method. SUBSTANCE: apparatus having crucible, seed holder, upper and lower ceramic screens also includes diaphragm arranged over melt. Cylindrical insert made of material permeable for heat irradiation, for example of melt quartz or leucosapphire is placed between ceramic screens. Level of lower edge of said insert coincides with upper surface of diaphragm. Height of insert s<ΔL, where , R is crystal radius, Bi is Bio number; Δh+ΔH≥sd/L, where Δh is distance from lower edge of diaphragm until initial level of melt; ΔH is melt level drop during process; d is distance between diaphragm and crystal; L is length of upper coat of insert. Diameter of upper screen is less than that of lower screen; distance from crystal until upper screen is selected equal to d. EFFECT: possibility for making optical crystals of large size and high uniformity, less number of rejected crystals at growing them. 2 cl, 9 dwg