Spiral scanner with electronic control

摘要

A scanning device, typically ultrasonic, can make a volumetric scan of a conical scanning field. A transducer having a permanent magnet at its back end is gimbal mounted in a housing. Behind the permanent magnet is a hemispheric electromagnet coil assembly having at least two wound electromagnet coils. The coils are energized in turn with an alternating current signal, with the signal applied to any coil being out of phase with the signal applied to any other coil by 180°/n, where n is the number of coils in the hemispheric electromagnet coil assembly. Volumetric scanning is possible by periodically modulating the magnitude or frequency of the signals applied to the coils.