A 3D imager is presented capable of capturing the depth map of an arbitrary scene. Depth is measured by computing the time-of-flight of a ray of light as it leaves the source and is reflected by the objects in the scene. The round-trip time is converted to digital code independently for each pixel using a CMOS time-to-digital converter. To reach millimetric accuracies an array of 32×32 highly sensitive, ultra-low jitter CMOS detectors capable of detecting a single photon is used. The scene is illuminated using a cone of low power pulsed laser light, thus no mechanical scanning devices or expensive optical equipment are required.