Everything starts in our crystal growth hall:
Here we work with custom-built furnaces, mainly using the Bridgman-Stockbarger and Nacken-Kyropoulos techniques. Using the Stockbarger process a melting crucible filled with raw material powder is inserted into a custom built furnace with different temperature zones. The raw material melts in the hotter part of the furnace before being transferred into a cooler section, which begins the crystallisation process from the seed crystal outwards. Using the Kyropoulos process the crucible is not transferred between different temperatures zones, but remains at a constant temperature. A cooled rod is inserted into the melt for the crystal to grow on. The crystal is extracted from the crucible after crystallisation by lowering the smelting temperature.
A lot of experience is needed to grow crystal as the physical processes involved will only yield high quality results under optimum conditions: every part of the process from the temperature adjustments to the speed of development of the crystal has to be just right.
In addition, the crystallisation process takes place in a vacuum over the course of several weeks – and must not be interrupted at any cost!
Thanks to many years’ of experience we rarely encounter any problems – but the quality of the raw crystal cannot be judged by the naked eye - which brings us to the next step in the process: Quality Control of the blanks.