Low profile lenses for ultrasound surgery

Several flat lens designs have been simulated that focus a planar transducer at various depths and angular deflections. The use of flat lenses with planar phased-arrays to create multiple focus patterns has also been explored. The simulations have shown that the discrete element size is such that is practical to machine. Simulations predict that a flat polystyrene lens with an f-number of 1.0 can produce a focal peak intensity that is 80% that of a geometrically focused transducer with the same focal depth by utilizing four discrete phase steps. These predictions were verified with a simplified experimental lens utilizing only two phase steps. Simulations predicted an attenuation of 18% and a focal peak intensity of 38%. Measurements resulted in an attenuation of 30% and a focal peak intensity of 30%. Experimental lens studies have indicated that sufficient power can be transmitted through the lenses that these designs are feasible for use in ultrasound surgery.