This beautiful pattern is a false-color plot of the intensity vs. time (horizontally) and transverse position (vertically) for a pulse transmitted by a complex aperture with multiple rings (placed to the left of the picture; light is propagating to the right).  It is nicely explained by the "Boundary Wave" theory of diffraction, which is equivalent to the standard Fresnel approach but is more intuitive in this case.  This work was performed using the SEA TADPOLE technique by Pam Bowlan in collaboration with Prof. Peeter Saari's group in Estonia.  You can read more about it in one of several papers that resulted from this productive collaboration.