The two-point-resolution of a novel two-color far-field super-resolution fluorescence microscopy has been evaluated. This microscopy is based on a combination of two-color fluorescence dip spectroscopy and a phase modulation technique for the laser beam. The two-point-resolution of the microscopy has been evaluated by using the fluorescent beads of which the size is specified by the observation with AFM. By introducing two color lasers, the observed fluorescence image shrunk down beyond the diffraction limit. In the observation of neighboring two fluorescence beads, pronounced separation between two individual fluorescence spots has been investigated. By taking the focal depth into consideration, FWHM and profile of the fluorescence images were well reproduced. It is proved that our technique breaks the diffraction limit and the spatial resolution of the optical fluorescence microscope can be improved by 2 times higher than the diffraction limit.
