Label-free difference super-resolution microscopy based on parallel detection

In this paper, a new method is proposed for super-resolution imaging of non-fluorescent samples. This approach is based on the intensity difference between confocal image and negative confocal image, which are simultaneously acquired at one sample scanning. In order to get these two different images simultaneously, the sample was illuminated by two different focused spots from the same laser source: the doughnut spot and the solid spot. The effectiveness of the label-free difference microscopy based on parallel detection was validated by experiments on some samples including 80 nm gold beads, 100 nm silver nanowires, and Blu-ray DVD without fluorescent dyes. By subtraction of the reflected light intensity from the sample, the final resolution of the image without deconvolution was enhanced about 1.6 times compared with confocal imaging. This technique can be applied to surface topography detection of metallographic or other non-fluorescent materials.