Portal de Periódicos da CAPES

Effect of excitation wavelength on penetration depth in nonlinear optical microscopy of turbid media

2009; SPIE; Volume: 14; Issue: 1 Linguagem: Inglês

10.1117/1.3081544

1560-2281

Mihaela Balu, Tommaso Baldacchini, John Carter, Tatiana B. Krasieva, R. Zadoyan, Bruce J. Tromberg,

Photoacoustic and Ultrasonic Imaging

We present a comparative study of two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) imaging in turbid media at 800- and 1300-nm excitation. The depth-dependent decay of TPEF and SHG signals in turbid tissue phantoms is used to estimate the impact of light scattering on excitation intensity at each wavelength. A 50 to 80% increase in scattering length is observed using 1300-nm excitation, while peak TPEF emission intensity is obtained 10 to 20 µm beneath the surface for both sources. The increased penetration depth at 1300 nm is confirmed by TPEF and SHG microscopy of tissue phantoms composed of gelatin/microspheres and 3-D organotypic collagen-fibroblast cultures, respectively. Our results establish the feasibility of 1.3-µm excitation in nonlinear optical microscopy.