An imaging system for an object such as human or animal tissue uses scattering of an illuminating electromagnetic wave by acoustic vibrations to generate a scattered electromagnetic wave including Doppler components shifted from the frequency of the illuminating electromagnetic wave by frequencies of the acoustic vibration and multiples thereof. An acoustic transducer apparatus applies acoustic vibrations localized in two or three dimensions in a plurality of regions. A transmitter simultaneously illuminates the object with an illuminating electromagnetic wave that has a frequency in the range from 100 MHz to 100 GHz, the vibration direction of the acoustic vibration having a component parallel to the propagation direction of the illuminating electromagnetic wave. A receiver receives the scattered electromagnetic wave. A signal processing apparatus derives characteristics of the Doppler components, and stores image data representing the derived characteristic.
