  As an important branch of photoacoustic microscopy, optical-resolution
photoacoustic microscopy suffers from limited depth of field due to the
strongly focused laser beam. In this work, a 3D information fusion algorithm
based on 3D stationary wavelet transform and joint weighted evaluation
optimization is proposed to fuse multi-focus photoacoustic data to achieve
large-volumetric and high-resolution 3D imaging. First, a three-dimensional
stationary wavelet transform was performed on the multi-focus data to obtain
eight wavelet coefficients. Differential evolution algorithm based on joint
weighted evaluation was then employed to optimize the block size of division
for each wavelet coefficient. Corresponding sub-coefficients of multi-focus 3D
data were fused with the proposed fusion rule utilizing standard deviation for
focus detection. Finally, photoacoustic microscopy with large depth of field
can be achieved by applying the inverse stationary wavelet transform on the 8
fused sub-coefficients. The fusion result of multi-focus vertically tilted
fiber shows that the depth of field of optical-resolution photoacoustic
microscopy is doubled without sacrificing lateral resolution via the proposed
method. Furthermore, the effectiveness of the proposed method was verified
through the fusion results of multi-focus vessel data. Our work provides a
feasible solution for achieving large-volumetric, high-resolution photoacoustic
microscopy for further data analysis, processing and applications.
