Fig. 5.

The present approach involves sending n beams together, as shown for n = 2 in (a)–(d) and n = 6 in (e)–(h). As several time frames are acquired, a different acquisition process is used for even and odd frames. For every even time frame, every even beam in a given shot is inverted. Comparing the circular region of interest (ROI) in (d) to the same region in (b), and the ROIs in (h) to corresponding locations in (f), it can be noted that all bright crests have been inverted into dark ones, and vice versa. This change in the acquisition process greatly simplifies the task of separating overlapped signals from overlapped beams.