20 October 2010


Leti demos first IR single-impulse active 3D imaging matrix

Leti of Grenoble, France (the Laboratory for Electronics & Information Technology of the French government’s research and technology organization CEA) has demonstrated the first single-impulse active 3D imaging matrix operating at infrared (IR) frequency capable of returning a three-dimensional image of a distant object with a spatial resolution of 30cm from a single-laser flash, providing excellent stealth.

The infrared-active 3D imaging matrix, with a 320x256-pixel format, currently operates at a wavelength of 1.55 microns for reasons of eye safety, but is also capable of operating with infrared lasers at wavelengths up to five microns.

The research results (presented at April’s SPIE Defense, Security & Sensing conference in Orlando, FL, USA) stem from CEA-Leti’s partnership with Sofradir of Châtenay-Malabry, France, which makes cooled infrared detectors based on mercury cadmium telluride (MCT/HgCdTe), and which holds an exclusive license for CEA-Leti's technology for this line of components for military, space, industrial and scientific applications.

The infrared-active 3D imaging matrix combines two technical innovations developed by CEA-Leti:

  • The fabrication of an avalanche photodiode (APD) matrix in HgCdTe. These extremely fast avalanche photodiodes (operating in the nanosecond range) have exceptional characteristics that imitate those of a perfect amplifier. They are capable of very high gains (in excess of 100) at low polarization voltages (less than 10V), without any excessive noise.
  • The design and manufacture of a read-out circuit based on a highly original concept patented by CEA-Leti that combines time-of-flight measurement with a three-dimensional radiometric acquisition.

The collaborative work is conducted within the framework of a joint laboratory (DEFIR), supported by CEA, Sofradir, France's government defense agency DGA and the French government research aerospace laboratory Onera.

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