We have developed a method to improve the performance of photoacoustic (PA) imaging technique by applying the acoustic echo effect. By superimposing the main and echo ultrasound signals, the axial positioning accuracy of a PA imaging system could be improved by 100 % and the signal-to-noise ratio (SNR) could be enhanced by ～2.8 dB experimentally. Using a multiwall carbon nanotubes composite structure as a sample, the occurrence conditions and properties of the echo signals were discussed. Theoretically, the SNR could be increased within a working distance of ～3.9 mm when water is used as the medium. Moreover, we found that PA images of red blood cells could also be enhanced by this method.

This work is published on Sensors and Actuators, A: Physical 329(2021):1-6.