A tunable diode laser time-of-flight anemometer: theory and structure

摘要

A time-of-flight anemometer is described which is composed of multiple IR absorption paths between fiber connected lenses arranged in symmetric configurations which provide spatial and temporal separation of the object gas, H_2O, processes intersecting the tunable diode laser beams. The time series H_2O concentration data from two gas analyzer paths are continuously correlated in real time to provide estimates of time shift between the processes. From beam geometry and time shifts, wind velocity vectors are calculated for a two-dimensional equilateral triangle prism structure and a three-dimensional co-axial structure. The real time convolution process is described and expected resolution and accuracy in the near surface layer are included. The resolution of the wind vectors and scalar variables makes this gas analyzer-anemometer suitable for eddy correlation flux measurements.