Scanning tomographic acoustic microscopy: Development and applications

The scanning tomographic acoustic microscope (STAM) tomographic data supplied by the rotation and frequency-varying is a device capable of performing subsurface imaging of microscopic hardware generate additional information content. Multiple-angle specimens. Using ultrasonic energy to interrogate specimens, the projections are acquired to increase spatial frequency coverage STAM nondestructively obtains accurate twoand three-dimensional and thus improve resolution. Multiple-frequency projections inreconstructions of the internal structures of materials that are crease the temporal frequency bandwidth, resulting in a smoothopaque to light. Applications include the nondestructive evaluation ing in cross-range resolution and improved range resolution [3– of integrated circuits and composite materials, characterization of the 5]. Advanced software techniques coordinate data acquisition, acoustical properties of substances, and examination of the condition error removal, and image formation. Image enhancement routines of biological tissues. This article describes the design and developare also employed to increase system resolution. ment of the STAM, its capabilities, and applications using data obtained from a fully automated and integrated prototype. q 1997 John This article is divided into several sections. In Section II, the Wiley & Sons, Inc. Int J Imaging Syst Technol, 8, 255–262, 1997 STAM system and image formation methods are described. In Section III, these techniques and the performance of the microscope are illustrated using multiple-angle and multiple-frequency tomography on specimens. Section IV describes STAM imaging in a linear