以射线光学模型为基础,研究了特殊形状微型物体在涡旋光束照射下的所受力矩。根据动量和角动量守恒定理,推导了微型物体在z、y和z方向上受力旋转的力矩公式。通过数值计算,得到了微型物体在不同表面倾斜角度的情况下的旋转特性。研究结果表明,由于涡旋光束的轨道角动量与光束动量的相互作用,改变涡旋光束的拓扑荷数,既可以使微型物体保持静止,也可以改变微型物体旋转的方向和旋转的速度。
The torque on a specially shaped micro object produced by a vortex beam is studied based on a ray-optic (RO) model. Based on conservation of momentum and orbital angular momentum, the formulas for the torque along x, y and z directions are derived. The numerical calculation is given to show the dependence of the optical torques on the inclination angle of the micro object. It is shown that the torque is dependent upon both the light momentum and orbital angular momentum (OAM) of the incident vortex beam. We can control the rotation of the micro object by modulating the topological charge of the incident light beam. Moreover we can make the micro object stop.