ABSTRACT
Spatial resolution is one of the most important parameters in photoacoustic (PA) tomography. In most cases, laser pulses with a short duration are used to excite PA signals, and small-aperture detectors with a limited-frequency-bandwidth are positioned around to pick up the outgoing PA signals. Then, algorithms based on point measurements are used in the reconstruction. In this case, two major factors limit the spatial resolution—the finite frequency bandwidth, and the finite detector aperture size. The bandwidth limits the obtainable spatial resolution. In the case of small-aperture measurement, the detector aperture blurs lateral resolution greatly at different levels for different recording geometries, but the effect on axial or radial resolution is slight. This chapter presents a complete theoretical explanation of spatial resolution. It explicitly derives analytic expressions of point-spread functions (PSFs) on the spherical, planar, and cylindrical recording geometries. The chapter summarizes the exact Fourier algorithms for spherical, planar, and cylindrical geometries, which will be used to derive the PSFs.
