传统的荧光各向异性显微成像技术往往只能够观察简单样本的荧光偏振。对于复杂样本，荧光的偏振由于阿贝衍射极限的存在会受到众多荧光团的影响，从而只能观察到平均效果。SDOM技术不仅提升了成像的空间分辨率，也提升了探测荧光团偶极子方向的精度。同时，SDOM技术具有很快的成像速度(最快可达每秒5帧超分辨)，对激发光功率要求很低(毫瓦量级)，非常适用于活细胞观察。偶极子取向的超分辨解析，使得通过强度无法看到的结构细节能够被角度信息反映出来。课题组对Walla文章中的海马神经元图像重新进行了分析，经SDOM重建后(图2 c下)发现偶极子取向的异质性分布，揭示了树突棘的不同膜边界结构，而这在Walla的工作中，是无法得到这一信息的(图2c上)。

图 1: SDOM的原理示意图。SDOM不仅带来了分辨率的提升，且能够为超分辨提供一个全新的荧光偶极子的维度，能够更清晰地认识其标记的蛋白结构。

图2: Walla的SPoD超分辨成像(a图左)和SDOM成像解析(a图右)的对比

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When excited with rotating linear polarized light, differently oriented fluorescent dyes emit periodic signals peaking at different times. We show that measurement of the average orientation of fluorescent dyes attached to rigid sample structures mapped to regularly defined (50 nm)2 image nanoareas can, in combination with application of the SPEED (sparsity penalty-enhanced estimation by demodulation) deconvolution algorithm, provide subdiffraction resolution (super resolution by polarization demodulation, SPoD). Because the polarization angle range for effective excitation of an oriented molecule is rather broad and unspecific, we narrowed this range by simultaneous irradiation with a second, de-excitation, beam possessing a polarization perpendicular to the excitation beam (excitation polarization angle narrowing, ExPAN). This shortened the periodic emission flashes, allowing better discrimination between molecules or nanoareas. Our method requires neither the generation of nanometric interference structures nor the use of switchable or blinking fluorescent probes. We applied the method to standard wide-field microscopy with camera detection and to two-photon scanning microscopy, imaging the fine structural details of neuronal spines.