Study On Automatic Diameter Control (ADC) Technique Of The Laser Crystal Growth

This subject is based on the Automatic Diameter Control (ADC) technique for laser crystal growth equipment. ADC is a key technique for the Czochralski (Cz) method crystal growth equipment. As the crystal diameter and charge become larger and larger, it is necessary and urgent to research and develop the ADC system with advanced and accurate and stable technique, to improve the crystal quality and national crystal growth equipment's automatic control degree greatly.Based on years of studying experience and the laser crystal growth demand, An advanced Up Weighing method ADC system has been developed; the principle of the Up Weighing method has been analyzed from theory and the control model also has been set up; In addition, During the designing process, the mechanical part, vacuum sealing and electric control, etc, all of these key parts had been studied by optimizing every small and important unit; After finishing system's adjustment, static measurement and running actually, the accurate and stable crystal growing instantaneous rate for automatic diameter control during the crystal growing process was realized. Φ2-3 inch crystal such as Nd :YAG and LiNbO₃ had been produced successfully. This result solves the problem for laser crystal growthequipment that it is difficult to control crystal diameter. From the customer's feedback, this system reduces the undulation in crystal diameter direction, reduces the influence of workman, reduces the labor and improves the crystal quality. As a whole, it would encourage crystal industry to develop more quickly.