Robert Johnson (AFRL/RDS), James Brown (SAIC), James Spinhirne (The Boeing Company)
Keywords: Sensor, Tilt, Focus, Adaptive Optics, Tracking
Abstract:
We describe preliminary results of a set of laser beam propagation experiments performed over a long (149 km) near-horizontal propagation path between Mauna Loa (Hawaii Island) and Haleakala (Island of Maui) mountains in February 2010. The distinctive feature of the experimental campaign referred to here as the Coherent Multi-Beam Atmospheric Transceiver (COMBAT) experiments is that the measurements of the atmospheric-turbulence induced laser beam intensity scintillations at the receiver telescope aperture were obtained simultaneously using three laser sources (laser beacons) with different wavelengths ( 1 = 0.53 m, 2 = 1.06 m, and 3 = 1.55 m). The presented experimental results on intensity scintillation characteristics reveal complexity of the observed phenomena that cannot be fully explained based on the existing atmospheric turbulence models. %T Measurements of Tilt and Focus for Sodium Beacon Adaptive Optics on the Starfire 3.5 Meter Telescope %B Telescopes with adaptive optics systems can measure high-order aberrations using an artificial laser beacon without the need for a relatively bright object near the object being imaged. Unfortunately, tilt and focus measurements are difficult to obtain from a laser beacon. One solution is to use light from the object being imaged to measure tilt and focus. We characterize the performance of a Shack-Hartmann wavefront sensor with 2_2 sub-apertures for measuring tilt and focus. Specifically, we implemented this scheme for the sodium beacon adaptive optics upgrade to the Starfire Optical Range (SOR) 3.5 meter telescope [1]. We use a wave-optics simulation to predict the performance of the tilt and focus sensor in the SOR sodium beacon system, and compare the results to laboratory measurements.
Date of Conference: September 14-17, 2010
Track: Adaptive Optics & Imaging