A new design of light illumination scheme for deep tissue photoacoustic imaging.

A new light illumination scheme to increase imaging depth in photoacoustic (PA) imaging was designed and evaluated by in silico simulations and tested by in vitro experiments. A relatively large portion of the light energy shining into the body of a human reflects off the skin surfaces. Collecting the reflected light and redirecting it onto skin surfaces will increase the effective input energy, resulting in an increase of light penetration depth for the same light source. Its performance in PA imaging was evaluated using a finite element (FE)-based numerical simulation model composed of four modules. In the in vitro experiments with the light catcher, PA image of multiple targets at different locations exhibited an enhancement both in uniformity and in depth of the light illumination.