Design And Research On High Precision Crystal Weighing Device For Laser Crystal Growth Furnace

The accurate measurement of the weight of the laser crystal is a key step in the growth process of the laser crystal.The equal-diameter control of the laser crystal indirectly calculates the diameter by measuring the weight of the crystal,and the crystal growth diameter is effectively controlled by the change rate of the crystal weight.In order to solve the problem of inaccurate measurement of crystal weight due to influence factors in the growth process of the laser crystal such as mechanical vibration,motor pulling and rotating motion,the interference of electrical signal,the temperature change of Growth furnace,the flow of gas and the tension fluctuations of laser crystal growth solid solution interface and so on,the laser crystal weighing device was studied and designed.The research and design of high-precision weighing devices are mainly from the aspects of weighing mechanical structure design and weighing electronic unit design.The cantilever-type weigher structure based on the weigh-in lifting method is designed which consider the requirements of the weighing device for the stability and precision of the weighing process in the design of weighing mechanical structure,the feasibility of structural design was verified through force analysis and the rationality of the design of the weighing machine structure was verified through the finite element analysis of the weighing structure.The weighing electronic unit realize data acquisition,data processing and human-computer interaction.During the measurement of the weighing signal,a front-end signal processing circuit with third-order temperature coefficient and nonlinear digital compensation functions is used to amplify and compensate the weak signal output from the weighing bridge and calibrate the analog output signal.In the software data filtering process,a median median filtering algorithm based on bubble sorting was designed to filter the weight data to overcome the interference and ensure the accuracy and stability of the weighing device.The weighing device adopts the core design concept of virtual instrument and designs the human-machine system,the automatic operation of the weighing device is realized through the human-computer interaction interface,and the design of the database facilitates the storage and query of the process data.The test of actual system shows that the weighing device can accurately measure the weight of the crystal and has a measuring range of 1000 g,a resolution of 0.01 g,and a maximum allowable error of better than 0.1g which satisfies the weighing requirements of crystal.The weighing device works well for the actual growth of the laser crystal,the crystal is controlled evenly in the equal-diameter growth phase and the friendly man-machine interface is convenient to operate.