激光驱动微纳器件为微机械领域中驱动微齿轮提供了一种新型的驱动方式。偏振光束的自旋角动量向晶体微粒传递可使其旋转,基于晶体波动光学理论分析了影响其旋转频率的各种因素(如微粒的厚度和半径;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),并推导出晶体微粒的旋转角速度的解析公式。为验证理论结果,在光镊平台上实现了碳酸钙晶体微粒的定位操控和旋转。所得实验值整体比理论值小是由于实际作用在粒子上的的激光有效功率比实验测量值要偏小;结合理论模拟与实验结果对比分析得知:碳酸钙晶体微粒的旋转角速度与激光功率成正比、与晶体微粒半径的三次方成反比、与微粒厚度成周期性变化规律。依此为提高微机械转子的旋转频率进行优化设计:选择Ca CO3晶体微粒作为微机械转子较为合适,Ca CO3晶体微粒的半径和厚度均取为1~3μm。
Technology of laser driven micro-nano devices provides a new way for driving micro gear in the field of micro mechanical. The polarization induced rotation can be achieved by the transfer of spin angular momentum of polarized light to birefringent particle. Main factors influencing the rotating angular velocity of uniaxial crystal particles are considered,(such as: thickness and radius of the particle, angle between optical axis and crystal plane,reflection of light beam on the crystal plane, phase contrast between the ordinary and extraordinary rays, laser power). The general formula of rotating angular velocity is derived based on the theory of wave optics. The precise manipulation and rotation of calcium carbonate particles is achieved by optical tweezers. By comparing numerical simulation with experimental analysis, results show that experimental results are smaller compared with theoretical data, which is caused by the smaller effective power of laser beam than the measured. The angular velocity of calcium carbonate particles is proportional to laser power, and inversely proportional to the cube of particle radius,moreover, a periodic variation with thickness. According to the test results and theoretical analysis, the parameters of mechanical microrotor are optimized design to improve the rotation frequency. The design results show that calcium carbonate particles chosen as mechanical rotor is more appropriate, furthermore, the radius and thickness of crystal particles should be chosen from 1 micrometer to 3 micrometer.