Characterization and applications of a fieldable single-laser standoff coherent anti-Stokes Raman scattering detection system

The development of a field-portable fiber-laser based hyperspectral imaging system for standoff detection and identification of trace levels of explosives is presented. The prototype system combines a hybrid of frequency and time-resolved coherent anti-Stokes Raman scattering (CARS) spectroscopy techniques with spatial scanning for rapid detection of microscopic traces of explosives on liquid or solid surfaces. An all-fiber light source architecture enables generation of three CARS excitation beams from a compact, single-unit femtosecond fiber laser and a highly nonlinear optical fiber. The light backscattered from the target surface is collected by a spectrometer, and a high-resolution automated stage system allows for two-dimensional microscopic CARS imaging. We demonstrate trace explosive detection in <100 ms.