Fig. 2.

For faster imaging, we sent several beams at a time. Examples are shown for n = 2, 4, and 6, shortly after the beams were emitted (a, c, and e) and shortly after they impacted with the object, near their focus point (b, d, and f). Although sending n simultaneous beams allows images to be acquired n times faster, it also leads to a complicated scattered field, as seen in (f), for example. Sections II-B and II-C explain how this signal can be reconstructed into images.