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BeiDou System Started Trial Operation at the End of 2011
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作者 Rain Liu 《Aerospace China》 2012年第1期9-9,共1页
On December 27,2011,Ran Chengqi,director of the China Satellite Navigation Office announced that,the BeiDou Navigation Satellite System (BeiDou system) had that day begun to provide initial operational service.
关键词 CASC OFFICE BeiDou System started Trial operation at the End of 2011
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Design of image-side telecentric freeform imaging systems based on a point-by-point construction-iteration process 被引量:4
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作者 杨通 金国藩 朱钧 《Chinese Optics Letters》 SCIE EI CAS CSCD 2017年第6期77-81,共5页
In this Letter, we present a novel design method of image-side telecentric freeform imaging systems. The freeform surfaces in the system can be generated using a point-by-point design approach starting from an initial... In this Letter, we present a novel design method of image-side telecentric freeform imaging systems. The freeform surfaces in the system can be generated using a point-by-point design approach starting from an initial system consisting of simple planes. The proposed method considers both the desired object–image relationships and the telecentricity at the image-side during the design process. The system generated by this method can be taken as a good starting point for further optimization. To demonstrate the benefit and feasibility of our method,we design two freeform off-axis three-mirror image-side telecentric imaging systems in the visible band. The systems operate at F/1.9 with a 30 mm entrance pupil diameter and 5° diagonal field-of-view. The modulation-transfer-function curves are above 0.69 at 100 lps/mm. 展开更多
关键词 iteration mirror desired starting entrance diagonal visible operate infinity coordinates
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