A LED-array-based range imaging system with Time-to-Digital Converter for 3D shape acquisition

A LED-array-based range imaging system is presented for capturing the depth information of three-dimensional (3D) objects. The range image is obtained by time-division electronic scanning of the LED Time-of-Flight (TOF) range finders in array, and no complex mechanical scanning is needed. Millimeter ranging resolution can be reached thanks to the use of Time-to-Digital Converter (TDC) with picosecond resolution and some special analog phased-lock loop (APLL) filter techniques. By close packaging LED die array, a high spatial resolution and large pixels version of the proposed system can be achieved easily. Experimental tests for evaluation of the system performance are adequately described. The results show the depth resolution can be better than 5 mm in the range of 300-1000 mm, and a higher resolution 0.5 mm can be achieved when the measurement time of a depth pixel is extended to 5 s, which is sufficient for many applications, including computer vision, machine automation, 3D object recognition, reverse engineering and virtual reality.