Wavefront Correction of Optical Beam for Large Space Mirrors Using Robust Control Techniques

For an imaging spacecraft to provide higher resolution imaging capability, the satellite will require larger mirrors. Because of the weight and launch constraints for spacebased optics systems, the mirrors will have to be segmented and light-weight, resulting in increased flexibility and lower structural frequencies. Consequently, achieving surface accuracy requirements for high resolution imaging with these large aperture light-weight mirrors become a challenging task. This paper investigates the use of adaptive optics for wavefront sensing and surface control of large segmented mirrors. An H1 robust control technique is considered for the control of the adaptive optics system with the reduced number of inputs and outputs using singular value decomposition and Zernike polynomials. The robust controller design with the reduced model is validated with a computer simulation for a full plant in the presence of disturbances.