The optical element’s figure error can be express as Fringe Zernike polynomial and vector form, based on the vector wavefront aberration theory, the figure error of optical element induced aberration’s characteristic of optical system has been analyses in this paper. The figure error on stop aperture affects all the field angles equally and induced the same type aberration as figure error. If the surface of optical element is not the pupil of optical system, the aberration observed in the focal plane is different from the figure error itself, it will not only induced the same type aberration as figure error but also induced lower order aberration in the optical system, the relationship between aberration and field of view is different and the location zero for the lower order aberration always reside at the center of the field of view.
The 470mm lightweight primary mirror of a space telescope is made of ULE, and supported on a titanium hexapod. The hexapod consists of six bond pads, six titanium struts with flexures and three support parts. The hexapod provides a quasi-kinematic mount for the lightweight mirror, and the flexures are used to isolate optical elements from the mechanical and thermal deformations of the support structure, then the surface figure distortion of the mirror is minimized. In this paper, the finite element method is used to analyze the static and dynamic characteristics of the mirror assembly. Then, six pads are bonded to the mirror and the support hexapod is assembly. The vertical optical test of the primary mirror assembly is implemented. Vibration test of the mirror assembly is performed, and the test results are consistent with the results of the finite element analysis.
Due to extended objects are influenced by occluded and blurred edge, the stability of target tracking is not good by the figure algorithms or the corner algorithms. In order to solute this problem, an improved multi-resolution(MR) fuzzy clustering algorithm based on Markov random field(MRF) is firstly used to segment the candidate targets of the extended objects from the observed images, then a new proposed target tracking structure algorithm, based on the stabilization of the extended objects’ skeletons and the partially un-occluded and un-blurred edge feature of the extended objects, is applied to extract the skeletons, corners, intersection points and their spatial location relationship of the candidate extended targets to determine the true tracking target or not. The experimental results show that the established algorithm can effectively complete the segmentation and extraction of the partially occluded and blurred extended objects with a very satisfied reliability and robustness.
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