Instrumentation for investigating the propagation of infrared radiation over long atmospheric paths

Equipment is described that has been developed to investigate the propagation of infrared radiation through low altitude layers of the atmosphere over various broad-band wavelength regions from 1 to 12 μm for pathlengths up to 10km. Propagation studies undertaken to date have included absolute transmission and relative transmission measurements in a terrain environment, and terrestrial scintillation observations: the measured transmission data compare favourably with lowtran3B predictions. The various errors associated with transmission measurements are discussed.