טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentGlazer Oded
SubjectConstruction of a Control Loop for an Adaptive Optical
System
DepartmentDepartment of Mechanical Engineering
Supervisors Dr. Erez Ribak
Professor Leonid Mirkin


Abstract

An adaptive optics system measures and manipulates the characteristics of the incoming wavefront to the optical system, using a Hartmann- Shack sensor to measures the distortions in the beam of light. The technology was basically developed for astronomical and military use and expanded to medical projects and could be used in the future to develop more efficient lasers, underwater imaging devices and confocal microscopes. Today the basic systems correct by means of a deformable mirror as a phase modulator in real time, controlled by a computer. The calculation must be done fast, otherwise the state of the atmosphere or other media may have changed, rendering the wavefront correction inaccurate, so there is a need for faster and more efficient algorithms. We managed to implement an alternative adaptive optics system using a modal and zonal correction. We used Fourier demodulation and direct demodulation (smoothing), techniques which were developed in the Technion to replace the customary Hartmann processing. Given a set of spatial modes or zonal averaged grids to be compensated, the command matrix uses the subaperture sampled gradients to derive the offset voltages to the mirror. A discrete- time PI servo ontroller was designed and implemented to reduce static and dynamics distortions and achieve good transient performances. Its real time implementation shows a good agreement with the analysis and numerical simulations.