The sodium laser guide star experiment for adaptive optics and the development of a high bandwidth tracking system for the University of Chicago Adaptive Optics System (Photometry).

摘要

This dissertation consists of two parts. The first part describes the generation and observation of the laser guide star for adaptive optics (AO). The second part describes the development of a tracking system with high bandwidth for the Chicago Adaptive Optics System (ChAOS).; A requirement for the laser guide star (LGS) from the point of view of the wavefront sensor of an adaptive optics system is discussed. The design and characteristics of a diode pumped sum-frequency laser designed for astronomical AO system is described. The experiment using this laser to generate and observe the sodium LGS undertaken on the National Solar Observatory's R. B. Dunn Solar Telescope is described and the result data presented. LGS as bright as 9.5 magnitude and as small as a natural star with FWHM size of 1 arcsecond has been formed with about 1.1 watts of laser power incident at the mesosphere. Experimental data has indicated that the optical pumping effect has enhanced the LGS, return by about 40% to 50%. The laser has shown to be an efficient and robust as a facility instrument for the astronomical adaptive optics system. Analysis using the returned flux and LGS spot profile has shown that the wavefront measurement error would be 0.155 rad2 with current ChAOS system at the winter (maximum) sodium abundance level and 0.208 rad2 with the improved ChAOS and laser system at the summer (minimum) sodium abundance level.; ChAOS is a high order adaptive optics system designed for the 3.5-meter telescope at the Apache Point Observatory. High frequency jitter from the secondary mirror mount of the telescope has limited the performance of the original tracking system of ChAOS. A high bandwidth tracking system with the sampling frequency of more than 700 Hz was developed to overcome the problems of telescope jitter and the excess power of the high frequency atmospheric turbulence. An upgrade of the sensor will be needed for the tracking system to be able to track on the fainter objects and further reduce the power of the high frequency tilt.