@article{87ae020b8c46417b9d8598ba3fd4d95a,
title = "Thermal Effects in Scanning Acoustic Microscopy for Fine Resolution Applications",
author = "G. Golan and Kenyon, \{A. J.\} and G. Griffel and Pitt, \{C. W.\}",
note = "Funding Information: I. INTRODUCTION Nondestructive measurement of internal structure using scanning acoustic microscopy (SAM) techniques has been an active subject of research for many years [ 1],[3]. Ultrasonic spectroscopy has been frequently employed in studying the mechanical properties of defects in elastic solids [4],[5]. Scanning acoustic microscopy is recognised as a valuable tool for observing some types of microstructure which lack the necessary contrast, or optical transmission, for standard optical techniques. A practical example of SAM application is the observation of small subsurface defects within microelectronic circuits for which a high spatial resolution is needed [6]. The particular subject of this study is the observation of structure lying at a depth of several hundreds of microns inside dense materials. Due to the high values of acoustic attenuation in the system of interest and the use of water as coupling medium, experiments are performed at frequencies of around 40 MHz. In order to determine the limit of spatial resolution for SAM, it is essential to consider the influence of the sample surface on the imaging system [7]. The clearest acoustic images are obtained when the acoustic propagation velocities of the coupling medium and the material under test are matched, minimising the acoustic losses. In such cases, the spatial resolution will be limited primarily by diffraction effects, and spherical aberration of the surface plane may be neglected. This situation is realised, however, only in the case of biological tissues which are observed using water Manuscript received October 5, 1993; revised February 10, 1994. The work of G. Golan was supported by a British Council Research Grant. G. Golan is with the Department of Electronic and Electrical Engineering, University College London, London, England WClE 7JE, on leave from the Open University of Israel, Tel Aviv, Israel 61392. A. J. Kenyon and C. W. Pitt are with the Department of Electronic and Electrical Engineering, University College London, London, England WClE 7JE, G. Griffel is with the Polytechnic University of New York, Brooklyn, NY 11201 USA. IEEE Log Number 9401996.",
year = "1994",
month = jul,
doi = "10.1109/58.294119",
language = "אנגלית",
volume = "41",
pages = "565--568",
journal = "IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control",
issn = "0885-3010",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
number = "4",
}