There are an increasing number of the upcoming space missions that require thermal imaging from space, notably to study climate and land use and to conduct remote forest fire surveillance. Until now, none of the detectors on the market have met the performance, mass, and power consumption requirements of micro and nano satellite missions. The coolers required by conventional photonic infrared detector arrays increase the mass and power consumption of infrared cameras. In addition, the uncooled arrays currently available on the market are designed for video applications and are not optimized for pushbroom satellite imaging.
Our specialists drew on their previous experience to develop the brand new IRL512A linear uncooled array of microbolometers to be incorporated into compact, energy-efficient infrared cameras compatible with micro and nano satellites. This is the first uncooled microbolometer detector array optimized for satellite-based infrared imagery.
No other uncooled array can provide this combination of performance and features, even when more complex interfaces such as time delay integration are considered.
A custom product, from design to fabrication
The reputation and experience INO has acquired over the years with the IRL256B and IRM160A convinced the European Space Agency and Canadian Space Agency to jointly finance the project. From the drawing board to production of the end product, our team of designers and researchers delivered an entirely custom product. The results: a linear array that consists of three parallel lines of 512 pixels on a 39 µm pitch. Each pixel includes both active and reference detectors to reduce pixel-to-pixel offset variation, eliminate common mode bias noise, and increase the circuit’s immunity to die temperature drift. The thin films making up the active detector structure are designed to provide high and uniform infrared absorption between 8.3 and 13 µm. The pixels are fabricated monolithically over a custom CMOS readout integrated circuit using a surface micromachined post-processing approach. The circuit integrates the signals of all pixels and provides 14 bit digital output.
Despite the small pixel size, the projected thermal resolution over the 8–12 µm spectral band for f/1 optics is below 50 mK, and below 250 mK for any 1 µm wide spectral band between 8.3 µm and 12.5 µm.