Session Ca - Turbulent Jets & Wakes.
ORAL session, Sunday, November 23
301, Moscone Center
Linear Stochastic Estimation (LSE) of optical beam deflection (or jitter) produced by a heated jet was used in an open-loop control system. A thin laser beam was propagated through the near-field region of a heated round jet. A piezoelectric steering mirror was controlled to minimize beam deflection based on measurements of temperature within the shear layer. Beam deflection produced by refractive-index gradients in the flow was measured simultaneously with temperature using two anemometer probes. This data was used to "train" the estimation algorithm by computing the LSE coefficients. These coefficients were then used with new temperature inputs to control the steering mirror to mininize the resulting beam deflection. Results will be presented with and without acoustic excitation of the jet and for different choices for LSE temperature references. The results show promise for multi-aperture adaptive-optic control based on multi-point temperature measurements.