Effect of excitation pulse width on thermoacoustic signal characteristics and the corresponding algorithm for optimization of imaging resolution

Thermoacoustic (TA) signal amplitude, waveform, and spatial resolution related to width of the excitation pulse were theoretically explained and simulated by finite-difference time-domain (FDTD) method. TA signals and the reconstructed TA images were compared under variable microwave pulse widths tunable from 400 to 1200 ns to analyze the relationships. The peak-to-peak interval of TA signals increase and the spatial resolution of TA images decrease with the increment of the excitation pulse width in the long pulse region. Also, the experimental results clearly reveal that the TA conversion efficiency decrease with increasing microwave pulse duration under the same peak power, which have a good agreement with the theoretical predication and FDTD simulation.