1. A probe for an ultrasonic imaging system for providing an output ultrasonic beam to scan human or animal tissue having a surface, said probe comprising: a) means for defining said surface in a manner rigidly supporting said human or animal tissue for imaging the same over the area of an image plane; b) transducer means for providing an output ultrasonic beam; and c) means for positioning said transducer means closely adjacent said supporting means in a manner directing said ultrasonic beam on said surface in a direction always substantially perpendicular to said image plane and so that the size of said beam at its focal point is as small as possible to maximize the resolution of said system in a plane substantially perpendicular to the direction of said beam.