Improving resolution of second harmonic generation microscopy via scanning structured illumination

Second harmonic generation microscopy (SHGM) is a well-known technique for examining the noncentrosymmetric structures in biomedical research. However, without realstate transitions, fluorescence-based superresolution methods cannot be applied. To improve the resolution, fringe-scanning SHGM (FS-SHGM), which combines SHGM with structured illumination based on point-scanning, is introduced in this paper. The scanning path was modulated to generate illumination patterns. For the coherent parts of SHG signals, a mathematical model of image formation and reconstruction was established. Both simulations and experiments showed a resolution improvement factor of similar to 1.4 in the lateral and 1.56 in the axial directions for chicken tendons and mouse skin. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement