A Medical Imaging Acoustical Holography System Using Linearized Subfringe Holographic Interferometry

Abstract

Linearized subfringe interferometric holography, described in Chapter 4, has been used for detection and recording in an acoustical holography system which is presently under development at McDonnell Douglas Corporation. This paper describes the laboratory system used to test the feasibility of the concept and to work out some of the problems associated with this technique. Acoustical hologram movies have been recorded at 16 frames per second, with each frame being recorded in 6 microseconds from a 100microsecond burst of sournd. Each movie frame is the recording of a complete acoustical hologram of 30-cm aperture at a sound frequency of 1 MHz. With a sound wavelength of 1.5 mm we have resolved about 2.5 mm and imaged objects less than 1 mm. The threedimensional image volume is about a 30-cm cube. There is no acoustic lens in the system and thus the resolution is limited by the 30-cm aperture of the acoustic hologram. We have resolved about 1.5 times the Rayleigh limit.

We are presently constructing a new version of this system which is intended to be used clinically to obtain images of soft tissues and structures and organs in the human body.