Fig. 6

Illustration of the concept of constructive and destructive wave interferences. a Constructive wave interference occurs when both interfering waves (in blue and red) are in phase (i.e., aligned as indicated by the dashed line); the resulting wave (in purple) has doubled its amplitude. b Partial destructive wave interference observed when both interfering waves are phase delayed (as indicated by nonmatching dashed lines); in that case, the resulting wave (in purple) has a lower amplitude than both interfering waves (in blue and red). c A complete destructive wave interference occurring when both interfering waves are phase shifted to obtain a maximum when the other wave has reached its minimum (as indicated by dashed lines); in this case, the resulting wave (in purple) has zero amplitude