微弱信号探测关键技术在空间目标激光测距中的应用研究

For realizing of the weak laser signal detection from the deep space far-distance laser ranging, the pivotal factors lie with the laser power on the ground, performance of detector and the telescopic receiving ability for laser signal. Research on the particular laser technology with the characters of the narrow pulse envelope including the multi-pulses with picosecond’s width and the laser output with the hundred watts is achieved at the frequency of 1kHz. Development of independent innovation and self-owned intellectual property rights of superconducting photon detector technology with characteristics of low noise, high detection efficiency, low timing jitter and the diameter of hundred microns is performed. The method of receiving telescopes array with the advantages of strong gathering laser signals and running flexibility is proposed in order to the implementation of the equivalent receiving ability produced from the large aperture of telescope. Through researching on the above techniques and applications, the dominant technologies of detecting weak laser signal in the filed of astronomical observation are solved with the well expansibility..Based on adopting 1.56m/60cm dual receiving telescopes and the high power picosecond’s laser and superconducting photon detector, the far-distance geosynchronous satellites with laser retro-reflector and small size debris targets are measured to validate the key techniques of the weak laser signal detection. The production of this project will lay the significance foundation for making the breakthrough of high efficient laser signal detection for future lunar laser ranging and development of the space technologies for detecting weak laser signals at the interplanetary far distance in China. This project will also provide the significance supports for increasing the technical level and international impact in the field of deep space astronomical observation and space scientific research.

实现深空远距离激光测距的微弱激光信号探测，地面激光功率、探测器性能和望远镜接收能力是关键。研究独特的窄包络多脉冲皮秒激光技术，实现千赫兹重复率百瓦级皮秒基频激光输出；发展国际领先具有自主知识产权百微米级靶面超导光子探测器技术，满足低噪声、高效率及皮秒测量精度要求；提出阵列式望远镜接收激光信号新思路，实现大口径望远镜同等接收能力。上述测量技术研究与突破，将成为我国天文观测中提升微弱激光信号探测能力的关键优势技术，并具有很好推广应用价值。.本项目基于1.56m/60cm双望远镜激光接收平台，研制千赫兹重复率高功率皮秒激光器和高性能超导光子探测器，以带有反射器同步轨道卫星和小尺寸漫反射碎片为主要观测目标，开展微弱激光信号探测关键技术应用研究。项目研究为我国未来激光测月高效率激光回波探测技术突破，以及行星际深空激光探测技术发展奠定基础，应用于提升我国深空天文观测能力、空间科学研究水平及国际影响力。

本项目针对深空远距离、漫反射激光测距微弱信号探测关键问题，从地面激光功率、信号探测与接收等方面开展了前瞻性研究工作，主要成果如下：.本项目独创采用多个迈克尔逊干涉光路组合，获得1ns等间距多脉冲激光(脉冲包络3ns)，国际首次获得1kHz、4脉冲123W(1064nm)皮秒激光，脉宽59ps；倍频后功率达42.7W(532nm)，其中单脉冲功率达12W(532nm)，成功应用于空间目标测量，为更高功率皮秒激光在微弱信号目标测量奠定基础。.国际首次实现了100um大靶面纳米线单光子探测器(SNSPD)，实现了探测效率大于60%、暗计数8Hz、探测精度达29ps。以接收面积200um、数值孔径0.22光纤集成五维可调光纤耦合非球面透镜，实现了望远镜高动态下自由光与窄光纤高效率耦合。通过空间目标测量验证了微弱信号高信噪比探测技术优势。.国内率先提出阵列式望远激光测量方法，基于双望远镜完成了多望远镜接收能力验证，为甚大口径等效接收能力实现提供了方法；国内首次实现相距2.5km望远镜接收漫反射信号，为数百公里、千公里单站发射多站接收空间碎片测量与轨道精度提升奠定基础。.完成了同步轨道卫星和小尺寸碎片目标微弱信号探测试验研究，采用532nm 波长多脉冲激光实现最远距离1726.8km、截面积(RCS)0.91m^2目标测量，等效距离1000km 时截面积达0.1m^2，最佳测距精度(RMS)优于20cm；采用1064nm 波长激光最远距离2494km、散射截面积(RCS)2.4m^2, 等效1000km 时截面积0.06m^2,最佳测距精度优于10cm。获得了一大批高精度激光观测数据，验证了皮秒激光和近红外波长激光对微弱信号碎片测量技术优势。.项目研究为高精度深空探测能力突破提供了有效方法，也为中国激光网多台站联合测量提高碎片轨道精度打下坚实基础，将促进激光技术在深空探测、空间碎片等领域应用。