A Method for Imaging the Spatial Coherence of Pulsed Ultrasound Fields

Abstract

The pulsed ultrasound fields employed in conventional medical ultrasound systems are considered to be ‘highly’ coherent. The development of concepts and definitions of coherence stem from the field of optics, and are well known. However, there are differences between optical fields and the acoustic fields employed in medical ultrasound applications, and the devices available for their measurement, which make direct application of the optical concepts to the acoustic case problematic. Abbott and Thurstone¹ comment that the concept of coherence has been applied to acoustic energy without explanation and the definition of coherence is best taken “simply as the ability to interfere ”. Gehlbach² notes that “the concept of incoherence in acoustic imaging is difficult to define due to the short pulse lengths involved”.