Single-Photon Synchronous Detection

Phase and intensity of light are detected simultaneously using a fully digital imaging technique: single-photon synchronous detection. This approach has been theoretically and experimentally investigated in this paper. We designed a fully integrated camera implementing the new technique that was fabricated in a 0.35 mu m CMOS technology. The camera demonstrator features a modulated light source, so as to independently capture the time-of-flight of the photons reflected by a target, thereby reconstructing a depth map of the scene. The camera also enables image enhancement of 2D scenes when used in passive mode, where differential maps of the reflection patterns are the basis for advanced image processing algorithms. Extensive testing has shown the suitability of the technique and confirmed phase accuracy predictions. Experimental results showed that the proposed rangefinder method is effective. Distance measurement performance was characterized with a maximum nonlinearity error lower than 12 cm within a range of a few meters. In the same range, the maximum repeatability error was 3.8 cm.