Improved Lateral Resolution Using sub Pitch Sampling of Ultrasound Data for Pulsed Laser Diode-Based Photoacoustic Imaging

The achievable resolution in PAT is dependent on the receive transducer parameters such as element size, inter-element spacing (pitch or sampling) and aperture length among a few other parameters. Ideally, dense spatial sampling of the generated photoacoustic signals using point detectors is required for obtaining the best possible image resolution in PAT. However, in most practical cases, data are acquired with only limited number of finite-sized detector elements. Manufacturing a high density, large-aperture linear array transducer with 'sub- λ{′ ′ pitch, especially at higher frequencies, is challenging and therefore is expensive. Hence, there is a need for alternate ways of increasing discrete array sampling for PAT application. In this work, we employ a linear translation-based approach in which the array transducer is translated by sub-pitch amount to create an augmented RF frame data having denser lateral spatial sampling. The results from simulation and experiments show 34% and 38% improvement in lateral resolution (LR) estimate, respectively, when using a 1/2 λ 4 -pitch configuration in comparison to using conventional λ -pitch configuration.