A High-Resolution Acoustic Imaging System to Map Interior Fish Morphology

Abstract

AbstractAn acoustic imaging microtome system (AIMS) was constructed to map the internal structure of fish. The system consists of two pairs of high-frequency (4.5 MHz) transmit-and-receive planar arrays, with one pair in the vertical plane and the other in the horizontal plane. AIMS provides a series of acoustic images, analogous to microtome slices, along the length of a fish by combining electronically controlled sequential acoustic transmissions and receptions over 224 channels and a computer-controlled mechanical device that moves the acoustic arrays lengthwise along the fish. AIMS measures the acoustic attenuation (extinction) along the direct ray paths of each transmit-receive channel pair that penetrates the fish body in a bistatic configuration. This results in a 2-D image of the interior morphology with 4- to 5-mm resolution. The images can provide morphological information on the fish's cheekbone, backbone, rib bone, skull, fins, stomach, and swimbladder, which is important for accurately modeling fish acoustic target strength, especially for non-swimbladder-bearing fish species.