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Conventional ultrasonic imaging techniques, including holographic, have high resolution in angle, but relatively poor resolution in range, because resolution in range is obtained only by use of selective focus or parallax, which is useful only with small focal ratio. The paper presents the principle and some experimental results of new ultrasonic imaging techniques that use a linear FM ultrasonic pulse and a pulse of light. This method gives high resolution both in angle and in range; it may be considered to be an application of pulse-compression techniques, used in chirp radar, to ultrasonic imaging, but it has image-forming as well as range-discriminating capability.

In recent years, there has been much research on the applications of ultrasonic techniques to medicine. This paper discusses some of the projects being carried out in the fields of diagnosis, therapy, dentistry, and bacteriology. The diagnostic investigations presented include brain tumor detection, soft tissue visualization, and analysis of cancers for malignancy. The therapy studies include tissue diathermy, brain surgery, and tumor inhibition. Drilling of teeth is the application discussed in dentistry. In all cases, an attempt is made to elucidate the mechanisms pertinent to the applications.

An analytical approach to obtain the relative heating pattern due to the propagation of ultrasonic waves in a fat-muscle-bone layered tissue system is presented. The effects on the relative heating pattern due to the change of incident angle and the change of frequency are discussed in this paper. The contribution to heating due to mode conversion at the bone surface is also discussed.

For the past seven years, Stanford Research Institute has been active in the area of ultrasonic imaging. This paper is intended to give a brief description of some of the past work, a look at our current projects, and a projection for future research.

It is becoming increasingly apparent that ultrasonic imaging (focused and holographic) will develop into a useful tool for diagnostic medicine. In this paper we examine the benefits to be derived with this application, particularly as they compare to the results obtainable with currently-used techniques of diagnostic ultrasonics.

Preparations for and results of a democratic expression of opinion by 15 scientists who ranked 29 potential research topics according to the priorities they perceived in April 1970 forbasic research on diagnostic and therapeutic ultrasonic radiation are reported. Recommendations are included on methods of funding and on the design, conduct, and reporting of such research. This paper is intended to be of interest to established workers in the field, recent graduates seeking research topics, and program directors of funding agencies.

The materials available for the construction of acoustic lenses provide a far wider choice of physical constants than one has in optics. As yet, little effort has been made to design lenses that effectively combine these materials to provide improved imageforming capability. The use of a digital computer for lens design can greatly facilitate such investigations. In this paper we present the results of a study of both simple and compound acoustic lenses, demonstrating the aberrational characteristics and overall merit of lens configurations optimized for a variety of materials and combinations. Also discussed are the effects on image resolution of lens apodization, and the results of experiments with coated acoustic lenses that exhibited considerably reduced surface reflections. [This work has been supported in part by a grant from the National Institutes of Health.]