Axial Signal Analysis and Image Reconstruction in Acoustic Lens Photoacoustic Imaging System

The lateral imaging characteristic of an acoustic lens is similar to the well-known object-image relationship of an optical lens. In this paper, axial signal analysis is carried on and reconstruction methods for a sample's axial photoacoustic (PA) image are researched based on the acoustic-lens PA imaging system. The integral and envelope methods are both proposed to reconstruct a sample's axial PA image, which has only been achieved approximately by the PA signals' peak values obtained by a peak-holding circuit in previous reports. And the envelope method is proposed for the first time. Hilbert transform was used to obtain the envelope of the sample's PA signals and axial PA images. Simulation results show that the integral method is appropriate for low frequency samples, and that the envelope reconstruction method can provide low frequency information of the PA images of samples. So for a sample, it would be best to combine the two methods together.