Compared to conventional waveform-digitizing altimeters or laser time-of-flight lidar techniques, photon-counting lidar is a more efficient technique as it requires only one detected photon to make a range measurement rather than hundreds or thousands. Sigma Space Corp. (Lanham, MD) has taken advantage of this ranging sensitivity to develop its single-photon counting lidar system, which can be operated day or night with two to three orders of magnitude greater efficiency and spatial resolution than conventional multiphoton-threshold or waveform-based lidar systems. Read More