Two-photon focal modulation microscopy in turbid media

Abstract

The image formation of two-photon focal modulation microscopy (2PFMM) in turbid media is theoretically investigated. The results show that compared with conventional two-photon fluorescence microscopy, the ballistic excitation of 2PFMM is concentrated in a much smaller region around the focal point and decays more rapidly outside the focal volume, while the scattered excitation is largely suppressed. When focuses at 1600 μm, the signal-to-background ratio and signal-to-noise ratio of 2PFMM are improved by 30 dB and 18 dB, respectively, indicating that 2PFMM can achieve a large imaging penetration depth.