提出一种利用加载到空间光调制器的振幅型计算全息图精确测量螺旋光束轨道角动量的方法.利用平面波角谱衍射公式和柯林斯公式,对不同阶数的厄米高斯光束、拉盖尔高斯光束、贝塞尔光束经过圆孔、矩孔、三角孔等参数可调的衍射光学元件的衍射过程进行仿真.理论和实验研究了螺旋光束经过杨氏双缝和三角孔后的传输特性,并利用这两种振幅型衍射光学元件实现螺旋光束轨道角动量的测量.由于通过改变和控制加载到空间光调制器上的计算全息图可以方便和高精度地改变光学器件的结构、尺寸、所在的空间位置,因此可便捷地实现螺旋光束轨道角动量的精确测量.

A new method is proposed to measure the photon orbital angular momentum (OAM) carried by helical beams accurately through the amplitude computer-generated hologram (CGH) loaded on a liquid crystal display spatial light modulator (LCD- SLM).The diffraction processes of Hermite- Gaussian beams,Laguerre-Gaussian beams and Bessel beams with different orders passing through diffractive optics such as circular aperture,triangular aperture,Young’s double- slit,grating whose parameters are adjustable,are simulated with the help of plane wave angular spectrum diffraction formula and Collins formula.Then the propagation properties of helical beams passing through Young’s double- slit and triangular aperture are studied by theoretical simulation and experiment,and the measurement of photon OAM carried by helical beams is also realized with those two amplitude diffractive optical elements.Due to the fact that changing and controlling the CGH loaded into the SLM is able to change the configuration,dimension and location of diffractive optical elements flexibly and accurately,the accurate measurement can be achieved conveniently.