A sol-gel PZT/PZT transducer for coaxial photoacoustic imaging

Photoacoustic (PA) imaging employs a pulsed laser to generate acoustic waves to be detected with a piezoelectric transducer. A coaxial, or even confocal, optical-acoustic arrangement has been desired to achieve high resolution and high sensitivity PA imaging. This research reports several designs and fabrications of sol-gel based PZT/PZT single-element transducers for coaxial PA imaging. At first, a planar transducer is fabricated by a sol-gel spray method on a 0.5 mm thick stainless steel substrate with a hole of 3 mm in diameter. Using the planar transducer, in-vitro experiments is conducted, in which pulsed laser with a wavelength of 1053 nm and an energy of 1.15 mJ is used to generate the PA signal. Secondly, a focused transducer, which center frequency is approximately 5 MHz (-6dB bandwidth of 86 %), is fabricated on a stainless steel rod with a 3 mm diameter hole. Using the planar transducer, PA imaging experiments is conducted, in which pulsed fiber laser with a wavelength of 532 nm and a power of 0.235 W before focus lens is used. As results, PA signals are obtained with good SNR and two-dimensional PA image is reconstructed.