Structured illumination microscopy (SIM) achieves super-resolution (SR) by modulating the high-frequency information of the sample into the passband of the optical system and subsequent image reconstruction. The traditional Wiener-filtering-based reconstruction algorithm operates in the Fourier domain, it requires prior knowledge of the sinusoidal illumination patterns which makes the time-consuming procedure of parameter estimation to raw datasets necessary, besides, the parameter estimation is sensitive to noise or aberration-induced pattern distortion which leads to reconstruction artifacts. Here, we propose a spatial-domain image reconstruction method that does not require parameter estimation but calculates patterns from raw datasets, and a reconstructed image can be obtained just by calculating the spatial covariance of differential calculated patterns and differential filtered datasets (the notch filtering operation is performed to the raw datasets for attenuating and compensating the optical transfer function (OTF)). Experiments on reconstructing raw datasets including nonbiological, biological, and simulated samples demonstrate that our method has SR capability, high reconstruction speed, and high robustness to aberration and noise.

本文提出了一种共路并行荧光辐射差分超分辨显微成像方法,利用单个空间光调制器(SLM)同时产生两个相位灰度图,对入射激光的水平偏振分量和垂直偏振分量同时进行调制,使得最终的会聚光场由错开的高斯实心光斑和空心光斑组成。在样品面上,利用错开的实心光斑和空心光斑同时对样品进行扫描,与此同时在探测端利用两个探测器同时收集错开光斑所激发的荧光信号,采用荧光辐射差分(FED)方法对采集的图像进行处理,就可以实现对样品的快速超分辨成像。与传统的并行荧光辐射差分超分辨显微术相比,本方法在保留了将成像速度提高一倍的优势的同时克服了非共路并行系统中不同器件引入的噪声、漂移对图像质量的影响,并简化了光路。实验结果表明所提共路并行荧光辐射差分超分辨显微成像方法具有良好的超衍射极限成像能力。

分集接收技术主要用于解决无线传输过程中的信号衰落, 无线接收时的邻频干扰、同频干扰等问题, 能够有效改善接收信号的质量。针对分布式平台上多通道接收信号同步与分集合并算法进行研究, 提出一种适用于不同调制类型的多通道信号合并前同频同相调整方法, 并对合并前各通道信号进行信噪比估计,以确定最大比合并时的权重。经理论分析可知, N通道信号最多可获得10lgN dB的合并增益。仿真验证结果与理论分析一致, 证明了算法的有效性和可行性。

Image scanning microscopy based on pixel reassignment can improve the confocal resolution limit without losing the image signal-to-noise ratio (SNR) greatly [C. J. R. Sheppard, "Super-resolution in confocal imaging," Optik 80(2) 53–54 (1988). C. B. Müller, E. Jorg, "Image scanning microscopy, "Phys. Rev. Lett. 104(19) 198101 (2010). C. J. R. Sheppard, S. B. Mehta, R. Heintzmann, "Superresolution by image scanning microscopy using pixel reassignment," Opt. Lett. 38(15) 2889–2892 (2013)]. Here, we use a tailor-made optical fiber and 19 avalanche photodiodes (APDs) as parallel detectors to upgrade our existing confocal microscopy, termed as parallel-detection super-resolution (PDSR) microscopy. In order to obtain the correct shift value, we use the normalized 2D cross correlation to calculate the shifting value of each image. We characterized our system performance by imaging fluorescence beads and applied this system to observing the 3D structure of biological specimen.