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TRIS: "Time-of-flight Range Image Sensor"
Funding agency: MIUR (Italian Ministry for Education, University and Research) under the PRIN-2007 programme (contract n. 2007AP789Y)
Project members/Partners
University of Trento, Italy  (national coordinator)
FBK – Fondazione Bruno Kessler, Trento, Italy
University of Pavia, Italy
University of Modena and Reggio Emilia, Italy
Project manager @ UniMORE: Giovanni Verzellesi
Start date: 22/09/2008
End date: 22/09/2010

Three-dimensional (3D) vision is acquiring increasing importance in various application fields such as computer-aided manufacturing, robotics, biometrics, surveillance, entertainment, biomedical appliances.  3D vision requires the acquisition of the third dimension (i.e. the depth or range) in addition to the conventional 2D intensity map. In the time-of-flight (TOF) approach, the depth of different points on the scene is extracted by correlating the modulated light signal reflected by the scene with a reference signal synchronous with the modulated light source used to illuminate the scene itself. This extraction is extremely simplified by using special photo-mixing detectors as light-sensitive elements of the pixel image sensor. The TRIS project has led to the development of a  120x160  CMOS 3D image sensor, based on 10x10 um2 pixel-size Current-Assisted Photonic Demodulators (CAPDs). Fabricated CAPDs have shown good demodulation capabilities up to a modulation frequency of 45 MHz, excellent linearity error lower than 0.11% in phase measurements, and maximum distance accuracy error of 3.3% with maximum pixel noise of 8.5% in the distance range from 1.2 m to 3.7 m.  Power consumption of the 120x160 pixel array chip is 200 mW, mainly due the contribution of the CAPD modulation currents. The prototype camera system provides real-time 3D images of the scene at 7 frames per second.