高效双螺旋点扩展函数相位片的设计与实验研究

Design and experimental demonstration of high-efficiency double-helix point spread function phase plate

双螺旋点扩展函数具有随离焦连续旋转变化的特性,结合单分子定位方法可用于厚样品三维超分辨成像及分子定位追踪研究.但双螺旋点扩展函数不足之处是光能利用率低,对于光子数受限的荧光显微成像而言其应用受限.本文通过对双螺旋点扩展函数在空域、频域和拉盖尔-高斯模式面等三个不同域中进行约束优化.模拟结果表明,优化后的双螺旋点扩展函数的光能效率提高了30多倍.同时,基于最优设计方案制备了相位片,并实验验证了该设计的正确性.与文献报道相比较,本文结果在成像深度和光能利用率方面都有所改善.

Double helix point spread function possesses continuously rotating invariant features with defocus, and it can be used for per- forming nano-resolution image of thick samples and for studying singleparticle tracking by combining the single-molecule localization method. However, the inadequacy of the original double helix point spread function is that the transfer function efficiency is very low, so it is difficult to achieve photon limited applications for the bio-imaging. The double-helix point spread function is optimized by introducing an iterative algorithm so that the constraints of the point spread function can be optimized best in three different domains： the Laguerre-Gauss modal plane, the spatial domain, and the Fourier domain. The simulation results show that the peak intensity of high efficiency double helix point spread function is 30 times higher than the original one. The design and fabrication of the phase plate are also proposed. The experimental results are in good agreement with the theoretical predictions, thus proving the feasibility of this method.