Configurable array of single-photon detectors

Apparatus for optical sensing, comprising:

• a radiation source, which is configured to direct a series of optical pulses toward a target scene;
• a first array of single-photon detectors, which are configured to receive optical radiation that is reflected from the target scene and to output electrical pulses in response to photons that are incident thereon;
• a second array of counters, which are configured to count the electrical pulses output by the single-photon detectors in multiple different gating intervals that are synchronized with each of the optical pulses, including at least first and second gating intervals at different, respective delays relative to the optical pulses, while the delays are swept over a sequence of different delay times during the series of the optical pulses;
• and
• a processor, which is configured to compute a time of flight of the optical pulses by comparing respective first and second counts of the electrical pulses that were accumulated in the first and second gating intervals over the series of the optical pulses.