The scanning acoustic microscope utilizes a beam of fixed angular illumination with large numerical aperture limiting the amount of information that is obtainable. It is suggested that a multizone transducer–spherical‐lens configuration can yield a more flexible acoustic illumination source. Numerical calculations indicate that it should be possible to vary the half‐angle of the illumination from about 5° to 57°, thus allowing an estimate of the specimen acoustic impedance to be made and critical angles determined experimentally. A fast, programmed microprocessor will be essential for phase‐amplitude control of individual zones and signal detection.

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