| Because of the volume constraints of space-borne astronomical instruments,segmented reflectors，which have high-resolution, have become the main measure forfuture astro-physical missions. However, it is well known that after the segmentedmirror is deployed and during its operating, there exists discontinuity between eachsegment of primary mirror. So, an active segmented-alignment control system is thekey technique of studying the segmented reflector.This thesis is dedicated to solve the key theoretical and technical problems forthe test techniques of segmented mirror. Here, the following researches in the text arecarried out:Firstly, the three mirror anastigmatic, which has2.4m aperture,48m focal lengthand the field-view angle of0.3×0.06, is designed. The ‘1+6’ aperture-stiching modelis applied in this paper. The optical transfer function is really very near to the limit ofdiffraction. In addition, we analyse the systemic tolerance.Secondly, we present an analysis of the diffraction effects from a segmentedaperture with a very large number of segments. This analysis is based on thepoint-spread-function analytical calculation for hexagonal segmentation geometry. Weconcentrate on the effects that lead to the appearance of speckles and/or a regularpattern of diffraction peaks. These effects are related to random piston and tip–tilterrors on each segment. We deliver formulas and the typical numerical valuesassociated with each particular case of segmentation error.Finally, we demonstrate a new segmented mirror phasing sensor system, DZEUS,by theoretical and numerical study. The phasing accuracy can be further enhanced byadopting a multiple step correction approach, by which the phasing error in the idealsituation can be removed completely. |
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