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Proceedings Paper

Bahamas Optical Turbulence Exercise (BOTEX): preliminary results
Author(s): Weilin Hou; Ewa Jorosz; Fraser Dalgleish; Gero Nootz; Sarah Woods; Alan D. Weidemann; Wesley Goode; Anni Vuorenkoski; B. Metzger; B. Ramos
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Paper Abstract

The Bahamas Optical Turbulence Exercise (BOTEX) was conducted in the coastal waters of Florida and the Bahamas from June 30 to July 12 2011, onboard the R/V FG Walton Smith. The primary objective of the BOTEX was to obtain field measurements of optical turbulence structures, in order to investigate the impacts of the naturally occurring turbulence on underwater imaging and optical beam propagation. In order to successfully image through optical turbulence structures in the water and examine their impacts on optical transmission, a high speed camera and targets (both active and passive) were mounted on a rigid frame to form the Image Measurement Assembly for Subsurface Turbulence (IMAST). To investigate the impacts on active imaging systems such as the laser line scan (LLS), the Telescoping Rigid Underwater Sensor Structure (TRUSS) was designed and implemented by Harbor Branch Oceanographic Institute. The experiments were designed to determine the resolution limits of LLS systems as a function of turbulence induced beam wander at the target. The impact of natural turbulence structures on lidar backscatter waveforms was also examined, by means of a telescopic receiver and a short pulse transmitter, co-located, on a vertical profiling frame. To include a wide range of water types in terms of optical and physical conditions, data was collected from four different locations. . Impacts from optical turbulence were observed under both strong and weak physical structures. Turbulence measurements were made by two instruments, the Vertical Microstructure Profiler (VMP) and a 3D acoustical Doppler velocimeter with fast conductivity and temperature probes, in close proximity in the field. Subsequently these were mounted on the IMAST during moored deployments. The turbulence kinetic energy dissipation rate and the temperature dissipation rates were calculated from both setups in order to characterize the physical environments and their impacts. Beam deflection by multiple point patterns are examined, using high speed camera recordings (300 to 1200 fps), in association with measured turbulence structures. Initial results confirmed our hypothesis that turbulence impacted optical transmissions. They also showed that more research will be needed to better quantify and mitigate such effects, especially for the U.S. Navy's next generation EO systems, including active imaging, lidar and optical communications.

Paper Details

Date Published: 12 June 2012
PDF: 10 pages
Proc. SPIE 8372, Ocean Sensing and Monitoring IV, 837206 (12 June 2012); doi: 10.1117/12.920740
Show Author Affiliations
Weilin Hou, U.S. Naval Research Lab. (United States)
Ewa Jorosz, U.S. Naval Research Lab. (United States)
Fraser Dalgleish, Florida Atlantic Univ. (United States)
Gero Nootz, Florida Atlantic Univ. (United States)
Sarah Woods, U.S. Naval Research Lab. (United States)
Alan D. Weidemann, U.S. Naval Research Lab. (United States)
Wesley Goode, U.S. Naval Research Lab. (United States)
Anni Vuorenkoski, Florida Atlantic Univ. (United States)
B. Metzger, Florida Atlantic Univ. (United States)
B. Ramos, Florida Atlantic Univ. (United States)


Published in SPIE Proceedings Vol. 8372:
Ocean Sensing and Monitoring IV
Weilin Will Hou; Robert Arnone, Editor(s)

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