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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 44677 (08)
- University: Sharif University of Technology
- Department: Mechanical Engineering
- Advisor(s): Jalali, Mir Abbas
- Abstract:
- Light has planar wavefront as it propagates in vacuum but in the atmosphere, because it passes through layers with different refractive indices, this planar wavefront is lost. Consequently light is distorted when it enters optical instruments. This issue results in images with low resolution. Adaptive optics is a method used for compensation of these distortions in order to obtain higher resolution. So far adaptive optics systems are successfully used in ground based telescopes and an increasing effort on developing and improving these systems is made. Most of these studies are performed from the optics point of view, but techniques from control theory can be applied to adaptive optics systems for improving their performance. Considering the continuous change of the wind speed and atmospheric turbulences, a fixed parameter method is not a good choice, so adaptive minimum variance control technique is used in this project. Predictability of this technique can handle the delays of the system elements like sensor and actuator or deformable mirror. The input noise is also considered in this technique. Most studies in adaptive optics are experimental, but in the present work, since there is no adaptive optics system available and the construction process is very expensive, all elements and steps are simulated. This makes the project difficult but has advantages like possibility of performing parametric study of all system elements, possibility of generalizing the method and being less costly. The results of the project show that the adaptive control technique used in this project has better performance than usual adaptive optics controllers for different distortions scenarios
- Keywords:
- Adaptive Control ; Wavefront ; Atmospheric Turbulence ; Adaptive Optics ; Wavefront Sensor ; Deformable Mirror
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