Abstract: The present invention relates to the technical field of preparing artificial calcium fluoride (optical fluorite) single crystals by growing from a melt by the directed crystallization and by using a seed crystal. The aim of the invention is to obtain oriented single crystals with a small deviation from the given direction. The technical result is achieved by the selection of a concrete technological mode in which the leading role has a period for melting of seed crystal. The optical fluorite single crystals are grown by crystallization on the oriented seed inserted into the central part of a bottom of crucible. Before the beginning of crystallization the crucible with a melt is maintained in a melt zone for a time that is sufficient for the homogenization of the whole melt and in this time the bottom part of a seed crystal appears below a melt zone. Subsequently, the crucible with a melt and with a seed crystal is moved from the melt zone into the annealing zone with the given speed.

Abstract: The invention provides a process for growing UV region <200 nm transmitting calcium fluoride monocrystals, which includes crystallization from the melt, the annealing of the crystals and subsequent cooling, in a vacuum furnace, and which is effected by the continuous transfer of the crucible containing the melt from the crystallization zone into the annealing zone, each of these two zones having its own independent control system for the process parameters, characterized in that there is a temperature drop of 250-450° C. from the crystallization zone to the annealing zone, with a gradient of 8-12° C./cm, the crucible containing the material to be crystallized is moved from the crystallization zone to the annealing zone at a speed of 1-3 mm/hour, it is first kept in the annealing zone at a holding temperature of 1100-1300° C. for 20-40 hours and is then cooled first to 950-900° C. at a rate of 2-40° C./hour and then to 300° C. at a rage of 5-8° C.

Abstract: The invention provides a method of making UV<200 nm transmitting optical fluoride crystals for excimer laser lithography optics and a multicompartment container for growing optical fluoride crystals, comprising a number of graphite bowls that are placed on top of one another to form a stack and which have a central conical orifice in the bottom of each of them, and also comprising a seeding unit that has a central cylindrical orifice and is arranged under the lowermost bowl, characterized in the each bowl is fitted with a heat-removing device that is made in the form of a graphite cylinder with a central conical orifice, is mounted under the bottom of each bowl, and adjoins, with its other surface, the cover of the next bowl down, in which design the cover of each bowl, apart from the uppermost one, has a central conical orifice.

Abstract: The present invention is directed to the technical field of the manufacture of calcium fluoride single crystals by growing from a melt by the directed crystallization and by using a seed crystal, such crystals having high optical homogeneity and small birefringence. The method includes crystallization from a melt and an annealing of crystals with the subsequent cooling in the vacuum furnace by continuous transfer of the crucible containing a melt from a melt zone into the annealing zone at independent regulation of modes of both zones in which the cooling of crystals in the range 1100-700° C. is carried out with a rate of 1.3-2.0° C./hr, a constant axial temperature drop with a gradient 20-50° C./m at is provided in the absence (or minimum) radial gradient, and this is provided by moving downwards a water-cooled rod moving at a speed of 0.8-1.4 of the speed of the crystal movement, the water-cooled rod being arranged towards a crucible bottom at a distance equal to 0.3-0.

Abstract: The present invention relates to the technical field of preparing artificial calcium fluoride (optical fluorite) single crystals by growing from a melt by the directed crystallization and by using a seed crystal. The aim of the invention is to obtain oriented single crystals with a small deviation from the given direction. The technical result is achieved by the selection of a concrete technological mode in which the leading role has a period for melting of seed crystal. The optical fluorite single crystals are grown by crystallization on the oriented seed inserted into the central part of a bottom of crucible. Before the beginning of crystallization the crucible with a melt is maintained in a melt zone for a time that is sufficient for the homogenization of the whole melt and in this time the bottom part of a seed crystal appears below a melt zone. Subsequently, the crucible with a melt and with a seed crystal is moved from the melt zone into the annealing zone with the given speed.

Abstract: The invention provides a method of making UV<200 nm transmitting optical fluoride crystals for excimer laser lithography optics and a multicompartment container for growing optical fluoride crystals, comprising a number of graphite bowls that are placed on top of one another to form a stack and which have a central conical orifice in the bottom of each of them, and also comprising a seeding unit that has a central cylindrical orifice and is arranged under the lowermost bowl, characterized in the each bowl is fitted with a heat-removing device that is made in the form of a graphite cylinder with a central conical orifice, is mounted under the bottom of each bowl, and adjoins, with its other surface, the cover of the next bowl down, in which design the cover of each bowl, apart from the uppermost one, has a central conical orifice.

Abstract: The invention provides a process for growing UV region <200 nm transmitting calcium fluoride monocrystals, which includes crystallization from the melt, the annealing of the crystals and subsequent cooling, in a vacuum furnace, and which is effected by the continuous transfer of the crucible containing the melt from the crystallization zone into the annealing zone, each of these two zones having its own independent control system for the process parameters, characterized in that there is a temperature drop of 250-450° C. from the crystallization zone to the annealing zone, with a gradient of 8-12° C./cm, the crucible containing the material to be crystallized is moved from the crystallization zone to the annealing zone at a speed of 1-3 mm/hour, it is first kept in the annealing zone at a holding temperature of 1100-1300° C. for 20-40 hours and is then cooled first to 950-900° C. at a rate of 2-40 C./hour and then to 300° C. at a rage of 5-8° C.