Multi-Aperture Laser Transmissometer System For Long-Path Aerosol Extinction Rate Measurement

Abstract

We present the theory, design, simulation, and experimental evaluations of a new laser transmissometer system for aerosol extinction rate measurement over long paths. The transmitter emits an ON/OFF modulated Gaussian beam that does not require strict collimation. The receiver uses multiple point detectors to sample the sub-aperture irradiance of the arriving beam. The sparse detector arrangement makes our transmissometer system immune to turbulence-induced beam distortion and beam wander caused by the atmospheric channel. Turbulence effects often cause spatial discrepancies in beam propagation and lead to miscalculation of true power loss when using the conventional approach of measuring the total beam power directly with a large-aperture optical concentrator. Our transmissometer system, on the other hand, combines the readouts from distributed detectors to rule out turbulence-induced temporal power fluctuations. As a result, we show through both simulation and field experiments that our transmissometer system works accurately with turbulence strength C2n up to 10−12 m−2∕3 over a typical 1-km atmospheric channel. In application, our turbulence- and weather-resistant laser transmissometer system has significant advantages for the measurement and study of aerosol concentration, absorption, and scattering properties, which are crucial for directed energy systems, ground-level free-space optical communication systems, environmental monitoring, and weather forecasting.

Publication Date

1-20-2018

Publication Title

Applied Optics

Volume

57

Issue

3

Number of Pages

551-559

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1364/AO.57.000551

Socpus ID

85040798530 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85040798530

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