  This paper presents an approach to characterize ultrasonic imaging arrays
using pin targets in commercial test phantoms. We used a 128-element phased
array transducer operating at 7.5 MHz with a fractional bandwidth of %70. We
also used a tissue-mimicking phantom in the measurements. This phantom consists
of pin targets with a 50-micrometer diameter. We excited the transducer with
pulsed and coded signals. We used Complementary Golay Sequences to code the
transmitted signal and Binary Phase Shift Keying for modulation. We
characterized the transducer array using the transfer function, line spread
function, range resolution, and beam width in an attenuating and scattering
medium. We showed that the pin targets, which are very thin compared to the
diffraction-limited focus of the transducer array, are suitable for the
transducer characterization under weak reflected signal conditions.
