Imaging of gas leaks (especially of methane, but also of other gases) has traditionally been done with portable infrared cameras based on cooled InSb and QWIP FPAs. In these, either the FPA spectral response is tuned to the absorption wavelength of the gas of interest or a spectral filter is used in front of it. Alternatively, high-end spectrally selective (Fourier Transform Infrared – FTIR) cameras (also based on cooled FPAs) are used to detect gas leaks with high sensitivity, but at a price premium.
Now, a new generation of innovative uncooled gas sensors are being developed to not just monitor large gas leaks but also act as monitors for small leaks.
The presence of uncooled infrared technology in China started more than 13 years ago when Ulis began to supply uncooled amorphous silicon (a-Si) microbolometers to companies such as SATIR, Guide Infrared and Dali.
Since then, FLIR Systems has also supplied VOx uncooled modules, but with strict export restrictions on array size and frame rate.
The success of uncooled detector technology developed in the west caused Chinese companies to undertake major development programs to initiate a domestic supply of both a-Si and VOx microbolometers.
The current status of these developments is summarized here.
Owning Some of the Night
How Real are the Claims?
Simplifying the Small Arms Video Sight
Smaller Pixels and Larger Formats
The Strategy Behind the Move
Ulis has landed a five year contract with Sagem Défense Sécurité (Paris, France) to be one of the primary suppliers of uncooled microbolometers for weapon sights and handheld infrared cameras, including those used in FELIN, the French Army’s Future Infantry Soldier System.
The Latest Attempt at Infrared Diagnostic Breast Imaging
Uncooled microbolometer development in France has been very rapid partly because of the cooperation between the CEA/Leti labs and Ulis
General Electric’s GE Commercial Finance is taking a 15% minority stake in Ulis, the supplier of uncooled amorphous silicon microbolometers.
Manufacturers of uncooled microbolometers are racing to develop and introduce focal plane arrays with 17 micron pixels. The smaller size pixels are seen by producers as a way to differentiate their products and as a path to lower cost and higher volume markets.
Amorphous silicon (a-Si) uncooled microbolometers made by ULIS are increasingly reaching performance levels previously attained only by VOx microbolometers.
Honeywell is continuing its bid to license a broad swath of uncooled microbolometer technologies. In the latest agreement, L-3 Communications has reached a license agreement for the amorphous silicon microbolometers being made by its L-3 Infrared Products unit (formerly Raytheon Commercial Infrared).
ULIS has moved it’s large format (640 x 480 with 25 µm pixels) amorphous silicon uncooled microbolometers into production. The chip is based on a single-level microbridge, thus avoiding the complexity and expense of dual-level designs.