Fig. 3: Interaction-free quantum imaging result of the ‘NJU’ characters with undetected photons.

In the presence of the plate in arm ③ of the interaction-free measurement module, two images are obtained with ICCD at phase setting (\(\theta = {{{\mathrm{\pi }}}},\phi = 0\)) and (\(\theta = 0,\phi = {{{\mathrm{\pi }}}}\)) (see the Supplementary Fig. 4a and 4b). The difference between these two images is shown above. The signal photon inside the three characters has higher visibility than in outside regions. The three characters ‘N’, ‘J’ and ‘U’ are measured independently. The length of the scale bar (white colour) in the figure is 200 \({{{\mathrm{\mu m}}}}\).