Detection of close-range specular targets

A computer software product for use with a camera including an autofocus mechanism and a range sensor including a transmitter, which includes multiple emitters configured to transmit optical pulses at different angles toward the scene, and a receiver, configured to receive and sense respective times of flight of the optical pulses that are reflected from the scene,

• wherein the product comprises a tangible, non-transitory computer-readable medium in which program instructions are stored, which instructions, when read by a processor, cause to processor to capture images of a scene using the camera, to drive the emitters in alternation to transmit the optical pulses, to estimate a range to a target in the scene responsively to the times of flight sensed by the receiver, to receive a signal from a photodetector that is indicative of an intensity of reflections from the scene in response to the transmitted optical pulses, to detect a difference in the signal output by the photodetector in response to the pulses transmitted by different ones of the emitters, and to set the autofocus mechanism responsively to the estimated range as long as the detected difference is no greater than a predefined threshold difference.