微小晶体生长过程的光学诊断实验研究

EXPERIMENTAL STUDY ON THE MINI-CRYSTAL GROWTH BYOPTICAL DIAGNOSTICS

将光学干涉技术与显微技术相结合,应用计算机技术、图像处理技术发展形成一种实时细观诊断的实验方法──光学细观干涉诊断技术;实时观测了KCl晶体在容积为3mm×3mm×4.5mm的生长池内的结晶过程,得到了该过程的晶体的表面形貌、生长速率、以及晶体生长尺寸与时间、浓度与时间的定量的关系,观测到由重力引起的浮力对流现象,它直接影响晶体的生长．实验表明重力对晶体生长形态有很大的影响;生长速率与浓度存在很大的依赖关系．

An optical diagnostic system consisting of the Michelson interferometer and the Mach-Zehnder interferometer with microscope, computer and image processing has been developed forthe study of the crystal growing in situ. The experimental setup is at first described in detail. Thecrystallization process of KC1 crystal has been investigated in a growth cell of 3 mm×3 mm×4.5mm.The surface pattern, the growth rate and concentration gradient in the aqueous solution weremeasured by this were diagnostic system. The surface deformation of the growing crystal has beencalculated from the Michelson interference fringes according to the calculation method of grating.The growth rate has been determined by the surface deformation at different moment, and therelationship between the growth rate and time has been given in this paper. The concentrationchange through out the crystalization was visualized by Mach-Zehnder fringes. It proved thatthe convection (a plume flow) existed in the crystalization. The buoyancy convection due to thegravity has been proved to influence crystal growth directly. These experiments further moredemonstrated that the gravity is an important factor in crystal growing, and the growth rate isheavily dependent on the concentration gradient of aqueous solution.