FIG. 6.

Experimental setup. The phantom contains six human hair crosses, which were glued to the top of optical fibers of the same length. The fibers were vertically fixed on an acrylic plastic base, and both the fiber and the acrylic base do not absorb laser light. Transducers, with or without a negative lens, scan the hair phantom along a circular path and at the same depth as the hair. Both the phantom and transducers were immersed in a tank filled with water. The laser beam is diverged so that all six hair crosses can be illuminated.