It uses an array of LIDARs (scanning laser beams) to gather this information about size and distance, using an optical concept called coherence (wherein waves of the same frequency align perfectly).
[1] NCIs can capture 3D images of objects with sufficient accuracy to permit the creation of high resolution replicas using 3D printing technology.
[1] An NCI using a 4×4 pixel grid of 16 grating couplers[2] operates based on a modified time-domain frequency modulated continuous wave (FMCW) ranging scheme, where concurrent time-domain measurements of both period and the zero-crossing time of each electrical output of the nanophotonic chip allows the NCI to overcome the resolution limits of frequency domain detection.
[3] Each pixel on the chip is an independent interferometer that detects the phase and frequency of the signal in addition to the intensity.
It was capable of detecting a 1% equivalent refractive index contrast at 1 mm thickness.