Real-time three-dimensional optoacoustic imaging using an acoustic lens system

In medical optoacoustics (photoacoustics), absorbing structures, such as blood vessels, hidden inside scattering media are illuminated with short laser pulses resulting in the generation of thermoelastic pressure transients. This initial three-dimensional (3D) acoustic pressure distribution, which exactly resembles the absorption distribution, was imaged into a water container with a 4f acoustic lens system. An optical dark-field stereo imaging system using a 30ns flash illumination light was used to capture a snapshot of the pressure-induced refraction index changes in the water container at a predetermined time after the original laser pulse. The imaging system works at 20Hz frame rate and was designed toward a theoretical resolution of 50μm. The proposed method directly provides 3D images of absorbing structures without the need of computational reconstruction algorithms.