2D spiral array with single element microlenses for 3D optoacoustic imaging

Fully populated matrix arrays typically require a very high number of electronic channels for allowing real-time volumetric imaging. Reducing the element count by sparse approaches will either lead to smaller elements (large opening angle but low sensitivity) or densely packed arrays with large elements (small opening angle, better SNR). We investigated the possibility to apply defocusing micro-lenses on a 2D spiral array based on a 4 MHz piezocomposite material for improving the opening angle and thereby increasing the FOV. We showed that our microlens structure can increase the opening angle from 16 to 37°. First phantom measurements showed the suitability of the array for optoacoustic imaging by reconstruction a point targets with a FWHM of 420 μm.