Fig. 1

Schematics of experimental setup. a Experimental setup to validate different channels in a scattering medium. The switch of channels is realized by inserting a rotating diffuser and a stationary diffuser into the optical path. b Experimental setup to demonstrate no valid channels in phase-grids, although they constitute shift-invariant systems and can convey light energy to the camera. The lower row shows the structures of the two phase-grids loaded on the SLM. d is the cell period, and a is the width of the phase square with a value of π in each cell. The color bar on the right denotes the phase value. The insert on the left is the zoom-in of the dash red square. Abbreviations: DMD - digital micromirror device; SLM - spatial light modulator