4kHz重复频率卫星激光测距系统及其应用

分析了上海天文台皮秒激光器系统在不同重复频率下的输出功率、输出波形等性能,实现了重复频率为4 kHz、功率为3 W、波长为532 nm的激光稳定输出。建立了4 kHz重复频率卫星激光测距系统,实现了4 kHz重复频率卫星测距,其测量数据量和标准点数据精度比1 kHz重复频率的分别提高了约2.62倍和1.62倍,提升了卫星观测性能。采用Lomb算法获得了Ajisai卫星自转频率(平均值为0.4234 Hz)以及自转频率准确度(0.0054 Hz),与1 kHz激光观测系统相比,4 kHz重复频率卫星激光测距系统的卫星自转测定精度显著提升。     

高时间稳定性的雪崩光电二极管单光子探测器

雪崩光电二极管单光子探测器是一种具有超高灵敏度的光电探测器件,在远距离激光测距、激光成像和量子通信等领域有非常重要的应用.然而,由于雪崩光电二极管单光子探测器的雪崩点对工作温度高度敏感,因此在外场环境下工作时容易出现增益波动,继而导致单光子探测器输出信号的延时发生漂移,严重降低了探测器的时间稳定性.本文发展了一种稳定输出延时的方法,采用嵌入式系统控制雪崩光电二极管,使其处于恒定温度,并实时补偿由环境温度引起的延时漂移,实现了雪崩光电二极管单光子探测器的高时间稳定性探测.实验中,环境温度从16 ℃变化到36 ℃,雪崩光电二极管的工作温度稳定在15 ℃,经过延时补偿,雪崩光电二极管单光子探测器输出延时漂移小于±1 ps,时间稳定度达到0.15 ps@100 s.这项工作有望为全天候野外条件和空间极端条件下的高精度单光子探测应用提供有效的解决方法.     

上海天文台亚厘米级单次测距精度的卫星激光测距试验

2001年8月, 中国科学院上海天文台与捷克技术大学合作在上海天文台进行了亚厘米级单次测距精度的卫星激光测距试验. 采用皮秒事件计时器作为激光往返脉冲的时间间隔测量仪器, 配合原有的发射和接收系统, 对Lageos-1, 2, Starlette, Stella, Topex和ERS-2等卫星进行了测距试验. 分析表明: 对这些卫星的单次测距精度达到了7~8 mm. 为了对比, 原有的测距系统同时对这些卫星进行了测量, 单次测距精度为12~15 mm. 表明新测距系统的测量精度比原有系统提高了约80%. 同时还对原有测距系统的系统偏差进行了检测.     

人工选育F5代萍乡肉红鲫RAPD遗传分析

萍乡肉红鲫是分布于江西萍乡的具有地方特色的品种,经过人工选育获得了较为稳定的遗传特征。用经过筛选的23个随机引物对25个人工选育F5代萍乡肉红鲫基因组DNA进行RAPD分子标记。结果显示扩增片段大小在250 bp至2 100 bp,共扩增的条带数为229,差异标记条带大多数为弱带,多态位     

Satellite laser ranging experiment with sub-centimeter single-shot ranging precision at Shanghai Observatory

The Shanghai Astronomical Observatory, Chinese Academy of Sciences, incollaboration with the Czech Technical University, carried out the experiment of satellite laser ranging with sub-centimeter precision in Shanghai in August 2001. A pico-second event timer was used for the measurement of the time interval between the transmitted and returned laser pulses for Lageos 1, 2, Starlette, Stella, Topex/Poseiden and ERS-2 in coordination with the existing laser transmitting and receiving system at the Shanghai Observatory. The analysis of the measurement showed that the single-shot ranging precision with these satellites is 7-8 mm. In order to compare ranging precision, the existing ranging system has tracked simultaneously these satellites and obtained the ranging precision of 12-15 mm. It means that the ranging precision with the new system is 80% better thanthe existing system. The systematic biases with the existing system have also been checked in the experiment.     

Space debris laser ranging with a 60 W single-frequency slab nanosecond green laser at 200 Hz

Space debris laser ranging was achieved with a 60 W, 200 Hz, 532 nm nanosecond slab, single-frequency green laser at the Shanghai Astronomical Observatory's 60 cm satellite laser ranging system. There were 174 passes of space debris measured in 2017, with the minimum radar cross section(RCS) being 0.25 m~2 and the highest ranging precision up to 13.6 cm. The RCS of space debris measured with the farthest distances in 174 passes was analyzed. The results show that the farthest measurement distance(R) and RCS(S) were fitted to R = 1388.159 S0.24312, indicating that this laser can measure the distance of 1388.159 km at an RCS of 1 m~2,which is very helpful to surveillance and research on low-Earth-orbit space debris.