Novel Sensing and Detection

Microelectromechanical systems, known as MEMS, are ubiquitous in modern military systems such as gyroscopes for navigation, tiny microphones for lightweight radios, and medical biosensors for assessing the wounded. Such applications benefit from the portability, low power, and low cost of MEMS devices. Although the use of MEMS sensors is now commonplace, they still operate many orders of magnitude below their theoretical performance limits. This is due to two obstacles: thermal fluctuations and random quantum fluctuations, a barrier known as the standard quantum limit.

Raman spectroscopy uses lasers to measure molecular vibrations to quickly and accurately identify unknown substances. Ultraviolet (UV) lasers have the optimal wavelength for Raman spectroscopy at stand-off distances, but the Defense Department’s (DoD) current UV-based tactical detection systems are large and expensive and have limited functionality. A new DARPA program seeks technology that may make UV-based detection equipment more readily available in the field.

DARPA yesterday issued a solicitation for proposals responsive to its Spectral Combs from UV to THz (SCOUT) program, which seeks new capabilities for highly sensitive remote detection of multiple biological or chemical agents in liquid or gaseous forms. A proposers day is set for Oct. 15 via webcast.

The process of detecting light—whether with our eyes, cameras or other devices—is at the heart of a wide range of civilian and military applications, including light or laser detection and ranging (LIDAR or LADAR), photography, astronomy, quantum information processing, medical imaging, microscopy and communications. But even the most advanced detectors of photons—the massless, ghostlike packets of energy that are the fundamental units of light—are imperfect, limiting their effectiveness. Scientists suspect that the performance of light-based applications could improve by orders of magnitude if they could get beyond conventional photon detector designs—perhaps even to the point of being able to identify each and every photon relevant to a given application.

Many essential military capabilities—including autonomous navigation, chemical-biological sensing, precision targeting and communications—increasingly rely upon laser-scanning technologies such as LIDAR (think radar that uses light instead of radio waves). These technologies provide amazing high-resolution information at long ranges but have a common Achilles heel: They require mechanical assemblies to sweep the laser back and forth. These large, slow opto-mechanical systems are both temperature- and impact-sensitive and often cost tens of thousands of dollars each—all factors that limit widespread adoption of current technologies for military and commercial use.