Flow imaging by use of femtosecond-laser-induced two-photon fluorescence.
A novel technique is demonstrated for the imaging of turbulent flows in which a single window to the flow is the only optical access required. A femtosecond laser is used to excite two-photon fluorescence in a disodium-fluorescein-seeded water jet. The fluorescence signal is generated at only the focal point of the laser because of the highly nonlinear nature of the two-photon absorption, and it is collected in a direction counterpropagating to the excitation beam. Tight focusing of the laser is used to limit the probe volume, and the two-dimensional mean and rms concentration images are collected by raster scanning the laser.
Kelman
James B
JB
Cranfield University, Cranfield MK43 0AL, United Kingdom. j.kelman@cranfield.ac.uk
Greenhalgh
Douglas A
DA
Ramsay
Euan
E
Xiao
Dong
D
Reid
Derryck T
DT