<title>Pulsed optoacoustic tomography of soft tissue with a piezoelectric ring sensor</title>

Abstract

Time-resolved optoacoustic tomography is based on thermoelastic pressure generation with shot laser pulses. The pressure wave contains information about the depth and type of light absorbers in the sample. Scanning over the surface of the same yields an optoacoustic image. To measure the pressure wave at the same side as the incident laser pulse, a ring geometry for the pressure transducer was used. The tissue was irradiated through the center of the ring. The ring geometry of the pressure transducer leads to a high directivity because bipolar acoustical signal generated off axis interfere destructively. This improves the spatial resolution of the transducer in scanning direction. The behavior of the detector was calculated for different sample-detector distances. The optoacoustic technique was used to visualize the coagulation of Holmium laser- irradiated chicken breast and to detect a hidden absorber embedded in chicken breast.