A grouping of a number of crystals in one search unit, with all contact surfaces in the same plane, and vibrating in phase with each other to act as a single transducer is called a:

• A. Crystal mosaic
• B. Focusing crystal
• C. Scrubber
• D. Single plane manipulator

Answer: (A)

Grouping several crystals in one search unit with all contact surfaces in the same plane and vibrating in phase creates a single, larger transducer aperture. This arrangement, called a crystal mosaic, uses many small crystal elements tiled together so their motions add up coherently. When driven in phase, the acoustic energy from each element combines constructively, giving higher sensitivity and a wider, more uniform beam than a single crystal of the same size. The term mosaic reflects the tile-like layout of the individual crystals forming one effective transducer.

This is different from a focusing crystal, which relies on curved surfaces or electronic focusing to steer or concentrate the beam; a scrubber is unrelated to transducer construction, and a single plane manipulator refers to a mechanical scanning device rather than how the crystal elements are arranged.