Aerosol absorption measurement by a Shack–Hartmann wavefront sensor

Abstract

Researchers at the U.S. Army Space and Missile Defense Command have developed a method for quantifying high energy near-infrared (NIR) laser heating of air resulting from laser absorption of suspended dry aerosols in a controlled environmental chamber. The measurements were accomplished using an ISO standard test dust and NIR high energy laser using a Shack–Hartmann wavefront sensor. This paper presents the methodology of the measurement as well as the quantitative reconstruction of the air temperature profile, absorption efficiency, and imaginary refractive index of the aerosol. The resulting measurement of the aerosol imaginary index of refraction was significantly lower than values typically found in the literature from measurements using low power techniques. These findings are in general agreement with other recently published works that have found that previously published values of mineral dust aerosols could be significantly overestimated.