Standoff Detection via Single-Beam Spectral Notch Filtered Pulses
  We demonstrate single-beam coherent anti-Stokes Raman spectroscopy (CARS), for detecting and identifying traces of solids, including minute amounts of explosives, from a standoff distance (>50 m) using intense femtosecond pulses. Until now, single-beam CARS methods relied on pulse-shapers in order to obtain vibrational spectra. Here we present a simple and easy-to-implement detection scheme, using a commercially available notch filter, that does not require the use of a pulse-shaper. 
Adi Natan, Jonathan M. Levitt, Leigh Graham, Ori Katz, and Yaron   Silberberg
physics.optics