Frequency interferometric localization microscopy

We propose a new super-resolution microscopy, named frequency interferometric localization microscopy (FILM). FILM is implemented by incorporating a Michelson interferometer into wide-field fluorescence microscope, which introduces coherence time as a new auxiliary axis to obtain the spectral information of individual fluorophores. After the time–wavelength transformation, the homogeneous linewidth of individual fluorophores can be isolated from the inhomogeneous broadening distribution of the fluorophore ensemble. Thus, the nearby fluorophores with a distinguishable central wavelength can be separated in the frequency domain and localized with accuracy beyond the diffraction limit. The principle of the method, experimental schematics, and reconstruction algorithm are numerically demonstrated. With properly prepared fluorophores, FILM has the potential to reach, in principle, molecular-scale spatial resolution.