Optical beams carrying orbital angular momentum (OAM) play an important role in micro-/nanoparticle manipulation and information multiplexing in optical communications. Conventional OAM generation setups require bulky optical elements and are unsuitable for on-chip integration. OAM generators based on metasurfaces can achieve ultracompact designs. However, they generally have limited working bandwidth and require complex designs and multistep time-consuming fabrication processes. In comparison, graphene metalenses based on the diffraction principle have simple designs and can be fabricated by laser nanoprinting in a single step. Here, we demonstrate that a single ultrathin (200 nm) graphene OAM metalens can integrate OAM generation and high-resolution focusing functions in a broad bandwidth, covering the entire visible wavelength region. Broadband graphene OAM metalenses with flexibly controlled topological charges are analytically designed using the detour phase method considering the dispersionless feature of the graphene material and fabricated using ultrafast laser nanoprinting. The experimental results agree well with the theoretical predictions, which demonstrate the accuracy of the design method. The broadband graphene OAM metalenses can find broad applications in miniaturized and integrated photonic devices enabled by OAM beams.

为使空间振幅调制偏振光谱仪对系统误差具有最小的灵敏度，以测量矩阵条件数作为目标函数，采用遗传算法对仪器调制模块中双复合光楔晶轴方位角和偏振片方位角的优化组合进行仿真分析，并给出了相应的最优角度组合。以偏振度测量精度为评价函数，在给定的器件误差范围内，对多种不同角度组合设置进行仿真实验。仿真结果表明，当仪器角度参数组合的测量矩阵条件数为1.733时，偏振度测量精度优于0.01的概率为98%，比测量矩阵条件数为1.966和3.257的角度参数组合的概率分别提高了23%和64%。该研究为空间振幅调制偏振光谱仪元件参数设计与选取提供了理论依据。

基于空间振幅调制的偏振测量技术，通过由复合光楔和检偏器组成的偏振调制模块将入射光偏振信息调制到空间维，再结合色散模块能够在单次测量中同时获取目标的偏振信息和光谱信息。首先，介绍了系统测量原理，推导出系统调制和解调方程。然后，通过对解调方程的分析，证明了系统具有区分不同偏振态入射光的能力，评估了检偏角对测量结果的不确定度和系统调制效率的影响。最后，给出了系统空间维和光谱维的定标方法，利用系统原理样机进行了偏振测量实验。实验结果表明，系统偏振度测量误差小于0.060，斯托克斯参数Q、U、V的测量误差分别小于0.052、0.035、0.057，测量结果说明了理论分析的正确性。

高精度的质心定位是基于单平行光管与分离式二维转台的几何定标方法的关键,但仪器的相对响应差异会影响质心定位精度。因此,提出了一种基于相对响应校正的质心定位精度提升方法,可有效地提升质心定位精度,进而提升几何定标精度。基于多角度偏振成像仪的实验室几何定标实验证明了所提方法的提升效果。提升效果在大视场区域中更为显著,最大几何定标精度约为0.1 pixel。最终,基于所提质心定位精度提升方法在实验室中获得了高精度的多角度偏振成像仪几何模型参数,模型拟合残差优于0.1 pixel。

为提高多角度偏振成像仪(DPC)的实验室几何定标精度,分析了平行光管发散角对像点定位精度的影响,建立了误差模型,并通过改进几何模型参数拟合时的目标方程来校正像点定位误差。对比验证实验结果表明,所提方法提升了基于平行光管的几何定标方法的定标精度,在视场角较大时提升效果更明显,当平行光管发散角为2°且入射视场角50°时,定标精度至少提升0.15 pixel。高精度的实验室几何定标将为DPC实现在轨高精度地理定位,多角度、多光谱及偏振图像配准提供精确的初始几何参数。