Simultaneously Tracking and Imaging a Moving Object under Photon Crisis

Abstract

In optical sensing, it is a fundamental principle that retrieving a certain quantity of spatial information requires a commensurate number of photons to be detected. However, on the issue of imaging moving objects under low photon flux, when the detectable photon flow is insufficient to recover the information flow formed by both motion and structural images of the object, photon crisis is induced and a more photon-efficient sensing method is urgently expected. Here we implement a simultaneous tracking and imaging method. The motion information and spatial information of a moving object are encoded by sequentially projecting the laterally shifting patterns and recording the results via a photomultiplier. Then both the trajectory and the image of the moving object are reconstructed gradually along with its evolution. As a photon-efficient encoding-decoding method is achieved, our method realizes capturing moving object with angular velocity larger than 45 mrad/s, and works well with the average number of detected photons even down to about 2.4 photons/speckle under single-laser-pulse illumination.