受激发射损耗显微技术(STED)作为一种远场超分辨显微成像技术, 具有几十纳米甚至几纳米的空间分辨率, 是细胞生物学等研究领域的重要成像工具。圆环形空心损耗光在物镜焦点附近的光场强度分布对STED空间分辨率起决定性作用。在高数值孔径物镜聚焦下, 光场的偏振态会对聚焦光场的强度分布产生显著的影响, 此外, 显微系统的轴外像差会严重破坏空心损耗光焦斑的中心对称性。基于矢量衍射理论, 理论模拟了在高数值孔径物镜聚焦条件下, 入射涡旋光的偏振态和光学系统中的彗差和像散对空心损耗光焦场强度分布的影响。实验上使用纯相位型空间光调制器来校准光学系统相差, 优化变形的损耗光, 利用纳米探针扫描焦点区域, 测量了其焦场强度分布。测量结果与由矢量稍微理论观测的结果一致。

Stimulated emission depletion microscopy (STED) is a powerful far-field technique for super-resolution optical imaging with a few tens even a few of nanometer spatial resolution, thus it is extensively used in investigation of cell biology and so on. The spatial resolution of STED highly depends on the intensity distribution of the doughnut-shaped depletion spot, near the objective focus. The polarization state of field has influence on focal intensity focused with high numerical aperture objective. The off-axis aberrations of microscopic system bring serious damage to the central symmetry of doughnut-shaped depletion spot. The influences of different polarization states of incidence vortex beam and aberrations of coma and astigmatism is of the optical system on the intensity profiles of doughnut-shaped depletion spot simulated by using the vectorial diffraction theory. In the experiment, the deformed depletion spot is optimized by utilizing a pure phase spatial light modulator to correct the aberrations of the optical system. A fluorescent nanoparticle is used as a probe to scan the focal region to obtain a high spatial resolution of intensity distribution. The measured results are in good agreement with those predicted by the vectorial diffraction theory.