Yes, the laser was fired at 3 KHz, while the mirrors were slowly scanning across the room. For each laser pulse, one microsecond of the received signal was dig

Yes, the laser was fired at 3 KHz, while the mirrors were slowly scanning across the room. For each laser pulse, one microsecond of the received signal was digitized with the sample rate of 2 billion samples per second, producing a vector of light intensity indexed by time. A large number of vectors were stored, each tagged by the pixel XY coordinates which were read out from the mirror position encoders. In post-processing, this accumulated 3D block of numbers was sliced time-wise into 2D frames, making the sequence of frames for the clip.