Development of an interferometric refractive index sensor (IRIS) system for boundary layer turbulence measurements (Conference Presentation)

The IRIS system developed consists of two separate Michelson interferometers and low power frequency stabilized laser source to generate fringe patterns from air flowing across the measurement regions. For each interferometer, a line scanning camera capable of kilohertz line rates captures these fringe patterns. The turbulence structure statistics are determined from the differential phase measurements between the two-independent time-synchronous interference patterns. The IRIS prototype currently uses a modestly capable computer with a network switch for data acquisition and processing functions. Preliminary baseline comparisons using data collected in conjunction with a sonic anemometer provide initial inter-comparisons of empirical turbulence observations, and these results provide potential design considerations to explore for future revisions. An overview of the IRIS methodology, prototype design, acquisition and processing software, and environmental testing are presented.