Contrast enhancement of microsphere-assisted super-resolution imaging in dark-field microscopy

We report a method of boosting the imaging contrast of microsphere-assisted super-resolution visualization by utilizing dark-field illumination (DFI). We conducted experiments on both 10-mu m-diameter silica (SiO2) microspheres with refractive index n similar to 1.46 under no and partial immersion in ethyl alcohol (n similar to 1.36) and 20-mu m-diameter barium titanate glass (BTG, n similar to 1.9) microspheres with full immersion to show the super-resolution capability. We experimentally demonstrated that the imaging contrast and uniformity were extraordinarily improved in the DFI mode. The intensity profiles in the visualization also numerically confirm the enhanced sharpness for a better imaging quality when applying DFI. (C) 2017 The Japan Society of Applied Physics