An electro-optical device includes a laser light source, which is configured to emit at least one beam of light. A beam steering device is configured to transmit and scan the at least one beam across a target scene. In an array of sensing elements, each sensing element is configured to output a signal indicative of incidence of photons on the sensing element. Light collection optics are configured to image the target scene scanned by the transmitted beam onto the array, wherein the beam steering device scans the at least one beam across the target scene with a spot size and scan resolution that are smaller than a pitch of the sensing elements. Circuitry is coupled to actuate the sensing elements only in a selected region of the array and to sweep the selected region over the array in synchronization with scanning of the at least one beam.