Fig. 2.

Effects of optical absorption saturation on optoacoustic signals generated with tone-burst excitation. (a) Absorption coefficient as a function of optical energy modelled as μ_a=kE₀₁^1/α, where α = 1 corresponds to the linear optoacoustic signal generation regime. (b) Optoacoustic signals generated for single pulse excitation (black) versus tone-burst of 3 pulses with the same total energy for α = 1 (blue) and α = 2 (red). (c) The corresponding frequency spectra of the signals. (d) Amplitude of the optoacoustic signals generated with the tone-burst excitation normalized to the signal generated with a single pulse with the same total energy.