Fig. 3: Results of the feedback-based OCIS.

a Simplified system setup for measurement. A galvo mirror was used to steer light into different channels of the scattering sample. As the galvo mirror scanned forward, the photodetector measured the temporal signal that fluctuated as light (continuous wave) coupled into different channels. b The measured signal was binarized and used to modulate the intensity of the laser in a time-reversed order as the galvo mirror scanned backward. In this case, we can measure the optical channels and inject light (PW, pulsed wave) into the bright channels during a galvo mirror round trip. c At different sample decorrelation times, optical spots were created in free space and captured by a camera with an exposure time of 125 μs. The CNRs for τ from 500 ms to 1 μs are 12.6, 12.3, 9.3, 6.5, 5.1, and 0.3. Scale bar: 20 μm. d CNR as a function of the sample decorrelation time. The error bar indicates the standard deviation of four points. e, f Feedback-based OCIS for null energy display. e By injecting light into the dark optical channels instead of the bright ones, we can obtain a null energy spot on the target plane. f Control image. By sending light into randomly selected channels, no null energy spot was observed. Scale bar: 20 μm. g Line plots of the arrow-indicated lines in (c, τ = 500 ms and 1 μs), normalized by the mean value of the background. h Line plots of the arrow-indicated lines in (e, f), normalized by the mean value of the background.