Xenics InGaAs SWIR Detector Is Part of Proba-V Space Mission

Uncooled SWIR InGaAs Detector
At SPIE DSS 2013 Xenics introduces the Xlin-1.7-3000, a line-scan detector in InGaAs technology that offers over 3,000 pixels of resolution. This is the best specification of any such device on the market. With its high sensitivity in the SWIR range (0.9 to 1.7 µm) Xlin-1.7-3000 is perfectly suited for the Proba-V (vegetation) satellite mission orbiting at an altitude of 880 km to reveal detailed long-term information on the changing crop and vegetation patterns of the planet and other vital parameters for preserving the biosphere.

Perfectly Suited for Space
Xenics' new Xlin-1.7-3000 line-scan detector is qualified for space missions with 10 krad of ionizing radiation while maintaining its specified performance. A full qualification campaign as prescribed by ESA was carried out, covering harsh environmental, radiation and life test conditions. Three of the new detectors are currently mounted on the Proba-V satellite, ready for launch with the new ESA VEGA launcher from Kourou, French Guyana. Right after the launch, the detectors will start delivering valuable earth environmental information in the SWIR range over a swath of 2,200 km with a center resolution of just 100 m.

The Xlin-1.7-3000 consists of three individual InGaAs sub-arrays of 1,024 square pixels (25 x 25 µm) each. They are mechanically butted on a gold-coated boat and mounted on an alumina substrate, together with three individual readout-ICs (ROIC). The overlap of 20 pixels enables perfect stitching of three individual images to a continuous line of 3,020 pixels over a length of 75.5 mm. The detector is assembled in a custom hermetically sealed 72-pin package with anti-reflective coated window. It is optionally also available in an open package.

Highest Sensitivity and Flexibility
With a fill factor of 100 percent, high quantum efficiency of 75 percent and adjustable sensitivity the uncooled InGaAs detector operates at very low illumination levels. The three individual readout-ICs are manufactured in a 0.35-µm CMOS technology and CTIA topology, which results in a high radiation tolerance for space applications. They allow a maximum pixel rate of 12.5 MHz, which yields a minimum line time of 100 µs, or an output frequency of up to 10 kHz.

The ROICs are designed for maximum flexibility. Thus, once on board the Proba-V mission many of their operational parameters can be controlled in real time to adapt the detectors' characteristics to specific observation conditions and get the best value in terms of line period and integration times (1 µs to 1 sec). Variable gain setting enables the operator to set pixel well depth, which results in a wide span of sensitivity values beginning at just 60 ke- (dynamic range 60:1), to a very high dynamic range of 3,200:1 (pixel well depth 10 Me-). With these features the Proba-V mission can be adapted to various conditions in terms of illumination (night/day), objects of interest (ice/desert/vegetation/water) and global or detailed imaging.