Shock wave focussing equipment - uses acoustic lens with index of refraction not constant in peripheral direction

摘要

The equipment directs shock-waves into the body of a patient, being particularly for a lithotripter. Even shock-waves are generated, and focussed by a lens (L). An acoustic lens is used, its index of refraction not being constant in the peripheral direction. The lens can be cylindrical, the index of refraction in one lateral direction being double that in a second at right angles to the first. ADVANTAGE - Increased likelihood of hitting the target even with inexact setting.