Laser Source Technology for UAVs

  • Published
  • By Maria Callier
  • Air Force Office of Scientific Research
ARLINGTON, Va. --  An AFRL-funded Multidisciplinary University Research Initiative program is examining the use of lasers to remotely probe and identify aircraft exhaust and track chemical smoke plumes without harm. The University of Wisconsin (UW) based research is occurring under the leadership of Dr. Daniel van der Weide, professor of Electrical and Computer Engineering. His team is developing instruments that can measure the complete infrared (IR) and terahertz (THz) electric fields, a capability that will benefit sensing requirements for aircraft such as unmanned air vehicles (UAV).

Known collectively as frequency comb spectrometers, these measurement instruments emit repetitive pulses resembling the teeth of a comb. These short pulses have correspondingly broad spectral content. Professor van der Weide's team uses ultra-short-pulse lasers to generate the combs, subsequently converting the near-IR laser signals into far-IR or THz signals, depending on the application. One laser provides the test signal, and another probes the signal. The resulting output can be transformed to provide information on the full electric field, at hundreds of frequencies, and all at once.

Scientists worldwide have recognized these research techniques, and many laboratories are proceeding with rapid development of associated methods. The most challenging problem lies in reducing the size of the lasers used for generating and measuring the full-field (magnitude and phase) signals. The team is addressing these challenges with support from an AFRL Small Business Technology Transfer program that enables the researchers to work with an advanced fiber laser supplier.

The program is gaining widespread academic attention as a result of Prof van der Weide's work featured in the New Journal of Physics publication's "Best of 2008" collection of articles. Selected for its diversity, originality, and quality, the "Vector Frequency-Comb Fourier-Transform Spectroscopy for Characterizing Metamaterials" article referenced the magnitude and phase field measurements used for stealth applications.

Prof van der Weide and his team are continuing their research on laser source and remote field measurement technologies, areas of particular relevance for accurately measuring the Air Force's high-power, high-frequency antennas.