Teachings disclosed herein provide a method for performing multiple measurements of an object. The first method comprises the step of providing a plurality of non-focused excitation signals, receiving a plurality of response signals and reconstructing image based on the received signals. A second method serves for a reconstruction of an image of an object based on received signals and prior knowledge, wherein information available twice within the prior knowledge and the received signals are removed before reconstructing. A third method refers to the performing of multiple measurements of an object. This third method comprises the steps of performing a first measurement starting with reconstruction based on the first measurement, performing a second measurement and continuing the reconstruction based on the first and second measurement. A fourth aspect refers to a combiner comprising a plurality of interfaces for a plurality of ultrasonic transducers, a computer interface and a mixer.