单轴晶体微粒光致旋转理论模型

Theoretical Model of Optical Rotation of Uniaxial Crystal Particle

为实现单轴晶体微粒的高精度、可操控旋转,利用偏振光与单轴晶体微粒的相互作用来实现光致旋转.基于晶体波动光学理论,考虑影响单轴晶体微粒旋转角速度的主要因素（晶体微粒的厚度和半径、单轴晶体光轴与晶面的夹角、光束在晶面的反射率和透射率、光束振幅比和位相差、激光功率等）,推导出正晶体和负晶体微粒旋转角速度的一般公式.并就各种影响因素分别对正、负晶体中具有代表性的CaCO3和SiO2晶体微粒进行了模拟分析,所得到的晶体微粒旋转频率与激光功率成正比,与现有文献的实验结果一致,证明了该理论模型的合理性.依据理论分析结果,选用半径和厚度均为1~3μm的CaCO3晶体微粒作为机械转子,对单轴晶体微粒光致旋转应用于微机械转子进行优化设计,提高了微机械转子的旋转频率.研究结果为晶体转子的选材和光驱动微机械马达的设计提供了更加精确合理的理论支持.

In order to achieve high-precision,controllable rotation of uniaxial crystal particles,the optical rotation can be achieved by the interaction between the beam of light and birefringent crystal particles.Based on the theory of wave optics,the main factors influencing the rotating angular velocity of uniaxial crystal particles were considered,（such as the thickness and radius of the particle,the angle between optical axis and crystal plane,the reflection of light beam on the crystal plane,the phase contrast between the ordinary and extraordinary rays,and the laser power.）The general formula of rotating angular velocity of positive and negative crystal were derived,moreover,the optical rotation of calcium carbonate particles and silica particles which represent the positive and negative crystals chosen as experimental material were simulated and calculated,and the rationality of the proposed theoretical model was testified by comparing with previously experimental data.According to the test results and theoretical analysis,calcium carbonate particles chosen as mechanical rotor was more appopriate,meanwhile,the radius and thickness of crystal particles should be chosen from 1~3μm,further moer,the conclusions show that the parameters of mechanical rotor were optimized design to improve the rotation frequnency of the rotor.The results had directive significance to optical driven micro-mechanical motor design and the material selection of rotor.