Theoretical and numerical analysis of lateral resolution improvement characteristics for fluorescence microscopy using standing evanescent light with image retrieval

This paper presents a lateral resolution improvement for TIRF (total internal reflection fluorescence) microscopy that employs a combination of standing evanescent light and a fluorescence distribution retrieval algorithm with successive approximation. In this method, variations in fluorescence images are detected by shifting the standing evanescent light illumination. Lateral resolution improvement beyond the diffraction limit can be achieved by using multiple fluorescence images. In this paper, the expression of lateral resolution improvement based on the Rayleigh criterion was theoretically formulated from the aspect of Fourier optics. This derived formula and numerical simulations indicate that the proposed method has about twice the resolution of conventional optical microscopy and under 100 nm resolution is achievable even in the case of the long working distance condition. For the special specimen consisting of the discrete distribution, the proposed method has more resolving power beyond the optical spectrum limit extended by the structured illumination of the standing evanescent light by performing its position shift over the peak-to-peak distance of the illumination distribution