A typical ``sonogram'' of a human eye, together with a description of the anatomical parts, is shown in Fig. 5. The frequency used for these experiments is 15 mc. and the transducer is a specially cut crystal with an epoxy lens capable of providing beam diameters smaller than one millimeter. The transducer itself moves the beam in a sector scan, just like a radar antenna, while the entire transducer structure is moved over a 90 -- degree arc in front of the eye to ``look into'' all corners. The total picture is only seen by the camera which integrates the many sector scans over the entire 90 -- degree rotation period.

Drs. Howry and Holmes at the University of Colorado Medical School have applied the same sonar technique to other areas of soft tissue and have obtained extremely good results. By submerging the patient in a tub and rotating the transducer while the scanning goes on, they have been able to get cross-section views of the neck, as shown in Fig. 7, as well as many other hitherto impossible insights. As mentioned before, bone reflects the sound energy and in Fig. 7 the portion of the spine shows as the black area in the center. Arteries and veins are apparent by their black, blood-filled centers and the surrounding white walls.

A cross-section of a normal lower human leg is shown in Fig. 8 with the various parts labeled.