A new ultrasonic imaging system that employs the orthogonal function wavefronts derived from theaprioriknowledge of the second‐order moment function about a class of objects is presented. First, it is shown theoretically that this new method has the ability to reconstruct images of sample objects of a given class with a higher signal‐to‐noise ratio (SNR) in a shorter time than the conventional beamforming methods. The assumptions are confirmed by numerical analyses and experiments carried out by using a prototype of an orthogonal function applied array imaging system.