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Acoustic microscopy is a relative newcomer to the field of acoustic imaging which will allow the discrimination of micron‐size structural detail and will render mechanical microstructure directly observable. Because of the unique characteristics of acoustic wave propagation in materials, potential wide areas of application are anticipated in both the physical and biological sciences. This talk will present a discussion of recent developments in acoustic microscopy techniques and applications. The present efforts to develop experimentally useful systems employ optical methods of sound amplitude detection through various means of coupling. The desired acoustic pattern can be displayed as a hologram or as a conventional image. Further, phase contrast and dark field techniques are also possible. Thus far, resolution better than 10 μm has been reported, and it is reasonable to expect that the resolution will soon be improved to the point of equivalence to optical microscopy, viz., about 1 ωm. Comprehensive inv...

A side-looking sonar system which utilizes coherent electrical processing is investigated. Such a system produces a quasi-hologram of the reflected sound field which may be subsequently imaged to give a visual presentation of the insonified region. An actual working laboratory system is constructed and several quasi-holograms are depicted in the Data and Results section. Imaging is not completed, however, an optical processing arrangement to accomplish this task is presented. http://archive.org/details/investigationofq1094516218 Lieutenant, United States Navy Approved for public release; distribution is unlimited.

The authors present several three-dimensional sonographic images from a population of obstetric patients in a military medical center. The presentation includes images that demonstrate areas for which our inexpensive three-dimensional sonographic techniques have distinct advantages over traditional two-dimensional means.

In this talk, the working principles of acoustooptics are discussed briefly. A review of present‐day applications ranging from light modulation to acoustic imaging is given.

A holographic system is described for producing a 2-dimensional picture in real time using stationary transmitters and receivers. The principle of operation relies on the fact that several holograms can be recorded in one plane if multiple frequencies are used in the recording process.

A simple system for producing acoustic holograms is described, which linearly records only the phase of the object wave rather than both the phase and the amplitude, as in conventional holography. An example of a phase-only acoustic hologram and its optical reconstruction is included.

The basic elements of an underwater acoustic imaging system are presented. Each element that introduces serious problems in the design and construction of a practical system is discussed and known ways of solving the problems are outlined. Problems of specular reflection, range‐definition tradeoffs, size, weight, cost, lenses, deep submergence pressure, and data rate are presented. Techniques utilized in the HYDROCON system are used as illustrations of one practical embodiment of the principles of a system. Finally, new ideas are presented to suggest areas in which techniques now under development may provide solutions to some of our current problems.

Ultrasonic visualization systems with very high resolution can best be described using concepts similar to those developed in the study of optical imaging systems. Such systems are thus quite naturally called acoustic imaging systems. The concepts of information rate, measured in resolution elements per radian second and resolving power, which is related to the spatial frequency bandwidth of a system, are developed and used as a basis for a historical review of some of the techniques that have been applied to underwater acoustic imaging. Unfortunately, a common characteristic of most systems developed in the past is their limited success. By considering designs that will simultaneously offer high resolving power and information rate, some new techniques that may result in more successful underwater acoustic imaging systems are introduced and discussed.

Acoustic holography enjoyed its peak of activity in the late 1960s, resulting in a wealth of new approaches to acoustic imaging and image data processing. Now that much of the work in innovation is reaching completion, the field is evolving more toward demonstrating the feasibility of the holographic approach for various applications as, for example, underwater viewing. The present paper discusses some new results obtained with a real‐time holographic system for underwater viewing. This system consists of a transmit‐receive array of 20×20 piezoelectric transducers, some data processing electronics, and an electro‐optical image reconstructor.

The letter presents the results of a Bragg-imaging experiment involving acoustic fields in the 150?300 MHz frequency range. Future applications of such a probing tool are devised.