Tracking of retro-reflective targets with fingerprints by structured illumination

An array of 16x16 blue-emitting GaN micro-LEDs was used to project binary illumination patterns onto a scene. The projected LEDs define a 16x16 spatial grid in the projection plane. Two retro-reflectors were placed in the scene, one at grid position (4,6), and the other at (14,7). A photodiode was placed next to the LED array to monitor the light reflected back from the scene. The attached hdf5 file contains three datasets, named "seconds", "volts_1", and "volts_2". These are oscilloscope traces taken from the output of the photodiode, where "seconds" contains the time axis for both traces in seconds, "volts_1" contains the photodiode signal when light was reflected from the first retro-reflector, and "volts_2" contains the photodiode signal when light was reflected from the second retro-reflector. The binary pattern sequence that was projected leads to a unique time-sequence of the optical signal for each detector, depending on their grid position. The positions of the retro-reflectors can thus be tracked remotely.