Fig. 4: Scenario layout and the temporal response in the fog.

a The scenario layout of the target and the fog chamber. Taking the target ‘Bunny’ as an example, its depth range is 40–60 cm and the total depth of the fog chamber is 150 cm. The object depth range is defined as the distance range between the object and the front surface of the media. b The temporal response at one of the scanning points is captured by the ultrafast detector in the scenario shown in (a). Affected by the time variability of the fog, the temporal response is disturbed by the dynamic noise. Since the backscattered light has little effect on signal photons in the fog, the photons reflected by the object and those do not reach the object can be distinguished in the temporal response taking depth as a prior as the dashed line divided.