An Assessment of Nano- and Micro-particle Quantification for Laser Transmission and Extinction

When it comes to laser propagation, the atmosphere plays a large role in the propagation of the laser energy to its destination, including the effects of optical turbulence and aerosol extinction. Aerosol extinction is the result of both the scattering and absorption of light due to the aerosols in the air. This extinction causes transmission loss of the laser resulting in less energy reaching its receiver. The Weather Integration Prototype (WIP), a prototype system developed by the Air Force Institute of Technology (AFIT) that can rapidly, in-the-field calculate how a laser system will propagate, uses a minimum set of atmospheric sensors plus numerical weather prediction (NWP) and AFIT’s Laser Environmental Effects Definition and Reference (LEEDR) code to calculate the laser transmission. The minimum set of sensors needed for transmission quantification includes small, but robust particle counters and standard pressure, temperature, humidity, and wind sensors. By incorporating a MAGIC Condensation Particle Counter (CPC) to quantify the nanoparticle concentration (5nm to 2.5µm) and a PurpleAir Air Quality Monitor to assess the microparticle concentration from 0.5µm to 10µm, LEEDR can calculate the full spectrum aerosol extinction (separated absorption and scattering)—without dependence on large footprint, not in-the-field friendly, nephelometers and aethalometers. The goal of this study is to demonstrate that the WIP can rapidly and accurately calculate aerosol extinction from nano- and micro-particle counts alone.