Super-resolution microscope using a two-color phase plate for generating quasi-Laguerre-Gaussian beam

To achieve high lateral resolution overcoming the diffraction limit, a two-color phase plate (TPP) for generating a quasi-Laguerre-Gaussian beam was applied to super-resolution microscopy (SRM) based on fluorescence depletion. Putting the TPP into a robust optical path in a commercial laser-scanning microscope, we obtained a point spread function with a full width at half maximum three times smaller than diffraction limit. The measured contrast transfer function shows that line and space patterns finer than the diffraction limit were clearly resolved and the image contrast was improved. Since the TPP can easily improve lateral resolution in SRM without any precise adjustment, our setup provides a practical super-resolution microscope.