Application of machine vision for automatic control of the process of growing monocrystals of thallium halides using the Bridgman-Stockbarger method

The article discusses the issue of controlling the growth process of monocrystals of thallium halides using the Bridgman-Stockbarger technique. The significance of maintaining a stable temperature gradient in the crystallization zone, which has a direct effect on the quality of the final monocrystal, is determined. The use of machine vision techniques to determine the position of the melt-crystal interface and subsequently automatic control of the temperature regime is proposed and scientifically justified. To control the temperature gradient automatically, it is suggested to utilize an algorithm that relies on visual tracking of the crystallization front. This front is identified using machine vision techniques, that allow calculating the corrective action on the upper heating zone of the apparatus. A brief overview of the main steps of the algorithm is provided, and a flowchart illustrating the process is included. Using the example of one iteration of the production cycle, the over time dynamics of changes in the height of the melt-crystal interface and the temperature of the upper furnace are analyzed. The compliance of the product obtained at the pilot apparatus with the accepted technical conditions confirms the effectiveness of the proposed approach in stabilizing the temperature profile. The developed algorithm eliminates manual parameter control at each apparatus, providing opportunities for horizontal scaling of production. It demonstrates advantages over traditional control methods, increasing the repeatability and quality of grown monocrystals. It can be used in the design and modernization of Bridgman-Stockbarger apparatuses. The main limitation of proposed approach is that it can only be applied to processes involving the growth of monocrystals with specific coloration.

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