Image-free few-target tracking via single-pixel sensing

Without imaging, single-pixel sensing aims to utilize a single-element detector to directly extract features of interest from a target. We demonstrate an optoelectronic framework for image-free tracking of a few moving targets. It integrates a Fourier filter for background suppression and a nonlinear power-law model that uniquely encodes spatial positions into optical responses. The all-optical encoder is designed based on a specific target template, which allows it to filter out the background and other types of irrelevant targets. The responses are decoded into coordinates via least-squares inversion with cross-target optimization. Using only 12 patterns, the system tracks two and three points with average errors of 1.00 and 1.77 macro-pixels experimentally at 0.67 ms temporal resolution. This work advances single-pixel tracking beyond single-target scenarios toward simultaneous localization of multiple targets with background suppression.