Agile acousto-optic delay line for fast impulsive stimulated Raman imaging

We introduce and characterize a fast (50 kHz), long range (50 ps) and random-access optical delay line based on an acousto-optic deflector inserted in the Fourier plane of a zero-dispersion line. The advantages of this agile delay line are demonstrated in the context of impulsive stimulated Raman imaging in the low-frequency range (<200 cm^-1). Besides fast imaging with a spectral resolution of 1.5 cm^-1, we show that random-access delay may be exploited to selectively image molecular species at high speed.