Pulsed near-infrared laser diode excitation system for biomedical photoacoustic imaging.

A pulsed laser diode system operating at 905 nm has been developed for the generation of photoacoustic signals in tissue. It was evaluated by measuring the photoacoustic waveforms generated in a blood vessel phantom comprising three dye-filled (mu(a)=1 mm(-1)) tubes of diameters 120-580 microm immersed to a maximum depth of 9 mm in a turbid liquid (mu'(s)=1 mm(-1)). The system was then combined with a cylindrical scanning system to obtain two-dimensional images of a tissue phantom. The signal-to-noise ratio of the detected signals in both cases and the image contrast in the latter suggest that such a system could provide a compact and inexpensive alternative to current excitation sources for superficial imaging applications.