The photographer on the left along with observers on the right plus the incoming wave of white water is simply stunning.
The resulting waveforms depend upon the amplitudes, wavelengths, and timing of the incoming waves.
The number of wave crests and wave troughs of the flame varies regularly with the change of frequences of incoming waves.
Alternatively, we can image that the incoming wave is diffracted by the object and the resulting diffracted wave is then diffracted again by the objective lens.