Time-of-flight 3D Cameras

The first developments in 3D Vision at SOI were done in the framework of the Opto3D project since year 2000, with the development of an intelligent electro-optical sensor for driving scenarios detection and object recognition [1]. Since then, SOI investigated and developed a number of different operating principles for indirect time-of-flight imaging using CMOS technologies, from the simulation and development of the sensing device, to the integrated circuit and 3D camera system.

Small pixels: 10um pixel pitch

The smallest pixel design in the SOI research unit about 3D sensors exploits a novel device to perform electro-optical demodulation of modulated light. The developed camera prototypes, have a resolution of 80x60 and 160x120 pixels with a record pitch of 10um, the smallest to date [2]. The operating principle is based on the use of modulated light, which allows using near-infrared LED to illuminate the scene. Centimeter resolution in real time has been obtained with the camera prototype.

Large resolution: QVGA with multiple exposure

The SOI research unit demonstrated the scalability of the approach by developing a 320x240-pixel array with 15um pixel pitch [4]. Thanks to the 4 high-speed parallel outputs, the sensor can support multiple exposure and readout in order to increase the dynamic range, covering at 20fps a distance range from 30cm to more than 4m.

A novel approach: avalanche photodiodes gain modulation

Recently, SOI research unit demonstrated the possibility to employ avalanche photodiodes as efficient photodemodulators, by applying a variable bias to modulate their gain. A 64x64-pixel imager and a compact USB prototype camera have been developed, capable to operate as fast as 200fps (3D).

References

[1] D. Stoppa, L. Viarani, A. Simoni, L. Gonzo, M. Malfatti, G. Pedretti, "A 50x30-pixel CMOS Sensor for TOF-based Real Time 3D Imaging", 2005 Workshop on Charge-Coupled Devices and Advanced Image Sensors, IEEE, 2005, pp. 230-233, Nagano, Japan, 09/06/2005 - 11/06/2005

[2] D. Stoppa, N. Massari, L. Pancheri, M. Malfatti, M. Perenzoni, and L. Gonzo, "An 80x60 Range Image Sensor based on 10um 50MHz Lock-In Pixels in 0.18um CMOS", International Solid-State Circuits Conference ISSCC 2010, San Francisco, 7-11 February, 2010

[3] L. Pancheri, D. Stoppa, N. Massari, M. Malfatti, L. Gonzo, Q. D. Hossain, G.-F. Dalla Betta, "A 160x120 pixel CMOS range image sensor based on current assisted photonic demodulators", SPIE Photonics Europe 2010 - Optical Sensing and Detection, Bruxelles, 2010

[4] L. Pancheri, N. Massari, M. Perenzoni, M. Malfatti, D. Stoppa, "A QVGA-Range Image Sensor Based on Buried-Channel Demodulator Pixels in 0.18μm CMOS with Extended Dynamic Range", International Solid-State Circuits Conference ISSCC 2012, San Francisco, 19-23 February, 2012

[5] O. Shcherbakova, L. Pancheri, G.-F. Dalla Betta, N. Massari, D. Stoppa, "3D Camera based on linear-mode gain-modulated avalanche photodiodes", International Solid-State Circuits Conference ISSCC 2013, San Francisco, 17-21 February, 2013