Infrared sensing

On the battlefield and elsewhere, there are growing concerns about the possible use of chemical agents. Such materials are relatively easy to make, hide and release, and pose a potentially lethal threat to troops and civilian populations. Infrared sensing is showing significant promise as a technique for quickly detecting chemical effluents in the environment.

Scientists in the Infrared Technologies Program at Pacific Northwest National Laboratory are developing a new generation of remote and point sampling chemical sensors for the U.S. Department of Energy, the Defense Advanced Research Projects Agency (DARPA) and others. Envisioned applications include a wide variety of defense and homeland security operations, environmental and industrial applications and medical diagnostic equipment.

The chemical sensors are based on spectroscopic sensing techniques enabled by miniature, selectively tunable lasers operating in the mid-wave and long-wave infrared regions of the spectrum. These particular regions are known as atmospheric transmission windows because water and carbon dioxide, two gases present in large concentrations in the atmosphere, do not absorb here. It thus becomes possible to detect minute concentrations of other gases present in the local environment because interference effects are minimal.

The particular lasers that the Infrared Technologies Program is using are quantum cascade and interband cascade lasers, which currently are being developed at Lucent and Maxion Technologies.

PNNL's Infrared Sensing Initiative, which was completed in 2003, served to help PNNL establish a broad technical capability in designing and building components critical to infrared sensing, an attribute now considered unique among DOE laboratories.