SHG Super-Resolution Microscopy Based on Point-Scanning Structured Light

Second harmonic generation (SHG) imaging technology is a powerful tool capable of imaging non-centrosymmetric biological tissues without labeling, which has become an important means of life science research. Due to the diffraction limit, SHG technology cannot resolve the fine structures below the diffraction limit. Although super-resolution microscopy has made breakthrough progress, the coherent nonlinear process of SHG limits the development of the SHG super-resolution microscopy. A point-scanning structured illumination SHG superresolution microscopy (SHG-psSIM) technology is proposed to realize the super-resolution SHG microscopic imaging of zinc oxide particles and mouse tail tendons. The electro-optic modulator is introduced into the excitation light path of the traditional SHG microscopy system. A point-scanning structured illumination pattern is generated by sinusoidally modulating of the excitation beam. Based on the moire fringe effect generated by interaction of the point-scanning structured illumination pattern with the sample structures, the undetectable high frequency information of samples is moved to the observable passband of the microscopy and detected by the photomultiplier. Finally, the algorithm software is used to reconstruct the super-resolution image. Compared with the traditional SHG system, the resolution of SHG-psSIM is improved by 1.86 times.