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The Lund dual conjugate adaptive optics demonstrator
2003 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The purpose of this Master's thesis was to test principles of dual conjugate adaptive optics, i.e. multi-conjugate adaptive optics using two deformable mirrors, on a breadboard test model of a telescope and an atmosphere. Although the theory has existed for 15 years now, only limited testing of multi-conjugate adaptive optics has been accomplished. When using conventional adaptive optics, with only one deformable mirror, the corrected field is limited. This effect is called anisoplanatism. The purpose of multi-conjugate adaptive optics, using more than one deformable mirror, is to increase the corrected field. A downscaled atmosphere and telescope, representing a static layered atmosphere at a wavelength of 2.2 microns respectively a 7.5 m telescope, was used to evaluate the effects of dual conjugate adaptive optics. Five natural guide stars in a cross with an armlength of 45'' were studied. Since the atmosphere used in the experiment was static, the temporal aspects of a dual conjugate adaptive optics system were not studied. Correction of tip and tilt in the wavefront was excluded in the reconstruction process. Hardware and software updates on the system were achieved throughout the work. A Tcl/Tk-script was written to allow dual conjugate adaptive optics wave-front reconstruction. Correction of tip and tilt in the wavefront was excluded in the reconstruction process. This method was compared to conventional (single conjugate) adaptive optics respectively to field averaged single conjugate adaptive optics. The effect of anisoplanatism, when using conventional adaptive optics, was demonstrated. Field averaged single conjugate adaptive optics was demonstrated to trade image quality for a wider field. The expected increase in image quality over the entire field was confirmed when using dual conjugate adaptive optics. This Master's thesis was carried out at Lund Observatory, for the Telescope Group.

Place, publisher, year, edition, pages
Keyword [en]
Physics Chemistry Maths, Multi-conjugate Adaptive Optics, Strehl Ratio, Point Spread, Function, Wave-front Reconstruction, Shack-Hartmann Sensor, Deformable Mirror
Keyword [sv]
Fysik, Kemi, Matematik
URN: urn:nbn:se:ltu:diva-57768ISRN: LTU-EX--03/337--SELocal ID: e6523167-2e37-48d6-818d-ffd0d9d44d5dOAI: diva2:1031156
Subject / course
Student thesis, at least 30 credits
Educational program
Space Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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