利用计算全息产生的拉盖尔-高斯光束旋转微粒

Micro-particles′ rotation by Laguerre-Gaussian beams produced by computer-generated holograms

分析了采用计算全息再现拉盖尔-高斯(Laguerre-Gaussian,LG)光束光场的原理。将计算全息法生成的全息图载入空间光调制器(spatial light modulator,SLM),在全息光镊平台上生成了LG光束。对吸收性氧化铜(CuO)微粒进行了系列旋转操纵实验。实验发现单个微粒既可以被光学漩涡捕获在暗中空区域绕固定轴旋转,又可以被囚禁在光强最大值处绕轨道旋转;还实现了多个微粒的绕轨道旋转。通过实验观察和测量,得出了微粒旋转的周期与激光功率和角向指数的变化关系。所得结果对光致旋转微粒的精确操控具有一定的指导作用。

The theoretical reconstruction of Laguerre-Gaussian （LG） beams with computer generated holograms （CGHs） is analyzed. LG beams are generated on our holographic optical tweezers platform by loading CGHs into a spatial light modulator （SLM）. A series of experiments on trapping and manipulation of absorptive CuO micro-parti- cles are performed. Experiments demonstrate that a single CuO micro-particle can be trapped in the dark central spot of LG beams and rotated around the axis parallel to the optical axis. It can also be trapped in the region of maximum intensity of LG beams and set into rotation around the circumference. In addition, multiple CuO particles can be set in- to rotation around the circumference. The relationships of the rotation period changing with the laser power and the azi- muthal index are obtained by observation and measurement. The results play a guiding role in the accurate manipula- tion of micro-particles＇ rotation.