Fig. 5
a Constructive and destructive wave interference patterns when forward echoes sent by a transducer (on the top of the image) are reflected or scattered by 2 particles located at the same depth. b Wave interference patterns when reflectors or scatterers are distributed in space. c B-mode images with different speckle patterns obtained from same reflectors or scatterers distributed in space, but with different point spread functions at lower to higher frequencies from left to right. The terminology “reflector” is generic here but formally a reflector has a dimension larger than the acoustic wavelength, whereas a scatterer has a dimension much smaller than the wavelength