What is the primary requirement of a paintbrush transducer?

• A. All crystals be mounted equidistant from each other
• B. The intensity of the beam pattern not vary greatly over the entire length of the transducer
• C. The fundamental frequency of the crystals not vary more than 0.01%
• D. The overall length not exceed 3 inches

Answer: (B)

Uniform sensitivity along the transducer’s length is the key aim for a paintbrush transducer. It uses many small crystals arrayed along a bar to produce a continuous, sweeping beam. If the beam’s intensity varied significantly from one end of the length to the other, parts of the aperture would be more or less sensitive, leading to inconsistent echoes, unreliable flaw indications, and degraded image quality. Keeping the beam pattern intensity roughly the same across the entire length ensures uniform detection capability and makes interpretation consistent across the scanned area. While even spacing or tight frequency tolerances matter in other contexts, they don’t address this core need as directly as maintaining uniform beam intensity throughout the aperture.