Spatially distributed two-photon excitation fluorescence in scattering media: Experiments and time-resolved Monte Carlo simulations
Spatially distributed two-photon excitation fluorescence in scattering media: Experiments and time-resolved Monte Carlo simulations
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DOI：
10.1016/j.optcom.2006.11.007
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发表时间：
2007-04-01
影响因子：
2.4
通讯作者：
Le Grand, Y.
中科院分区：
文献类型：
--
作者：
Leray, A.;Odin, C.;Le Grand, Y.
We report on measurements and Monte Carlo analysis of the spatial distribution of light in two-photon excitation fluorescence (TPEF) microscopy operating through scattering media. The axial profile of TPEF produced by a high numerical aperture microscope objective focusing through a tissue-like optical phantom at depths more than five photon mean-scattering lengths is studied. The measured profile is quantitatively interpreted with time-resolved Monte Carlo simulations that take into account the spatio-temporal distribution of the photons within the turbid medium under a femtosecond excitation regime. It is shown that considering only the ballistic photons leads to an under-estimation of the actual out-of-focus distribution of the fluorescence, whereas it is over-estimated when the ballistic and scattered photons are treated alike. Comparison of the in-focus signal to the overall out-of-focus background clearly pointed out that the signal-to-background ratio of TPEF microscopy images benefits from a shortening of the excitation pulses. Moreover, in homogeneously labeled specimen, the background is shown to overcome the signal at imaging depths of about five to six photon mean-scattering paths. (c) 2006 Elsevier B.V. All rights reserved.
