Comparison of Radiometric and Chemometric Sensitivities for Heterodyne and Direct Detection DIAL

Abstract : The heterodyne / direct detection DIAL comparison (HD/DD DC) experiment series was conducted at Kirtland AFB, NM, to simultaneously characterize and compare the radiometric and chemical detection sensitivities of heterodyne and direct detection DIAL systems. The system developed by the Air Force Research Laboratory Directed Energy Directorate demonstrated the first known programmable and shot-to-shot wavelength-agile heterodyne DIAL measurements. The experiments studied radiometric issues, speckle mitigation through spread spectrum (modelocked) operation, and chemical detection sensitivities. The measurements were performed over horizontal paths at standoff ranges from 4 to 15 km, using both natural and man-made targets. Heterodyne and direct detection radiometric and chemometric results are presented and contrasted, and are compared with predictions from simulations and models.