1 自适应光学全国重点实验室,四川 成都 610209
2 中国科学院光电技术研究所,四川 成都 610209
3 中国科学院大学,北京 100049
4 山东高等技术研究院,山东 济南 250100
Overview: Gravitational waves are spacetime oscillations radiated outward by accelerating mass objects. Significant astronomical events in the universe, such as the merging of massive black holes, emit stronger gravitational waves. Detecting gravitational waves allows for a deeper study of the laws governing celestial bodies and the origins of the universe, making accurate detection crucial. Gravitational wave detection technology utilizes Michelson interferometers to convert the extremely faint spacetime fluctuations caused by gravitational waves into measurable changes in optical path length. Recently, ground-based large Michelson interferometers have achieved direct detection of high-frequency gravitational waves. However, the detection of low-frequency gravitational waves, which is equally important, is not feasible on the ground due to arm length and ground noise issues. This necessitates the construction of ultra-large Michelson interferometers in space for low-frequency gravitational wave detection. Spaceborne gravitational wave detection telescopes play a vital role in collimating bidirectional beams in ultra-long interferometric optical paths in space. The extremely subtle changes in optical path caused by gravitational waves impose high demands for pm-level optical path length stability and below 10?10 level backscattered light in these telescopes. The ultra-high level index requirements exceed the precision limits of current ground testing techniques for telescopes. To ensure that spaceborne telescopes maintain their ultra-high design performance in the orbital environment, developing testing and evaluation techniques for these key indicators is a crucial prerequisite for the success of the space gravitational wave detection program. This paper provides an overview of the development of spaceborne gravitational wave detection telescopes, both domestically and internationally. It focuses on the current status and some test results of optical path length stability and backscattered light testing of telescopes under development, as well as further testing plans, providing a reference for the testing and evaluation of Chinese space gravitational wave detection space-borne telescopes.
空间引力波探测 星载望远镜 地面测试 光程稳定性 后向杂散光 space gravitational wave detection spaceborne telescope ground test optical path length stability backscattered light
1 自适应光学全国重点实验室,四川 成都 610209
2 中国科学院大学,北京 100049
3 中国科学院光电技术研究所,四川 成都 610209
4 中国科学院自适应光学重点实验室,四川 成都 610209
5 北京空间机电研究所,北京 100094
6 中国科学院西安光学精密机械研究所,陕西 西安 710019
7 华中科技大学物理学院引力中心,精密重力测量国家重大科技基础设施,基本物理量测量教育部重点实验室,湖北 武汉 430074
8 “天琴计划”教育部重点实验室,天琴中心 & 物理与天文学院,天琴前沿科学中心,国家航天局引力波研究中心,中山大学(珠海校区),广东 珠海 519082
探测空间引力波有望揭开更多的宇宙奥秘。在国家重点研发计划项目的支持下,《光电工程》组织了“空间引力波探测星载望远镜专题(二)”。专题围绕空间引力波探测星载望远镜设计与分析、建造与装调、测试与评估等几个方面介绍了近期的主要研究进展,将为相关领域学者和专家提供技术研究的参考和合作交流的平台,并将积极推动我国空间引力波探测计划的研究进程。
星载望远镜 空间引力波 引力波探测 天琴计划 专题出版 sapace telescope space gravitational wave gravitational wave detection TianQin project special issue
宋奇林 1,2,3,4李杨 1,3,4周子夜 1,3,4肖亚维 1,2,3,4[ ... ]饶长辉 1,2,3,4
1 自适应光学全国重点实验室,四川 成都 610209
2 中国科学院大学,北京 100049
3 中国科学院光电技术研究所,四川 成都 610209
4 中国科学院自适应光学重点实验室,四川 成都 610209
Overview: Since the groundbreaking discovery of gravitational waves, the scientific community has fervently pursued the exploration of low-frequency gravitational waves to glean deeper insights into the cosmos. The inherent limitations of ground-based conditions, however, pose formidable challenges for detectors in capturing gravitational waves below the 1 Hz threshold. Consequently, the imperative has shifted toward the deployment of space-based gravitational wave detectors as the paramount solution for effective low-frequency gravitational wave detection. At the crux of space-based gravitational wave detection lies the pivotal role of spaceborne telescopes. Given the expansive transmission distances spanning magnitudes of 109 m between celestial constellations, the demand for nanoradian-level precision in telescope pointing accuracy becomes non-negotiable. The concomitant necessity for high-precision measurements and calibration emerges as a prerequisite for achieving the exacting standards of pointing accuracy in spaceborne telescopes dedicated to gravitational wave detection. To ameliorate the deleterious effects of pointing deviations on gravitational wave detection, this study strategically optimizes key parameters, including microlens structures, detector selection, and algorithmic frameworks, thereby achieving a breakthrough in high-precision pointing deviation measurements. Leveraging a low-density microlens array with extended sub-aperture focal lengths enhances the spatial scale of the light spot within each sub-aperture. This, coupled with detectors boasting a high signal-to-noise ratio, synergistically elevates the pointing detection accuracy of each discrete lens. Moreover, the paper introduces an innovative, Hartmann principle-based methodology for high-precision pointing deviation measurements, deploying a spatially reused paradigm across multiple sub-apertures. By aggregating measurement results from diverse sub-apertures, the approach effectively mitigates the influence of assorted random errors on measurement accuracy, thereby markedly enhancing the precision of pointing deviation measurements. Illustrating the efficacy of these methodologies, the paper exemplifies their application within the ambit of the "Tianqin Plan" for space-based gravitational wave detection. Employing numerical simulations and factoring in the design parameters of the Hartmann sensor, the study performs a meticulous analysis of pointing deviation measurement accuracy. Comparative analysis between single sub-aperture and sub-aperture correlation reuse technologies reveals a compelling enhancement in measurement accuracy, approximating a sevenfold improvement with the latter. The pointing deviation measurement accuracy achieved through sub-aperture correlation reuse technology is quantified at approximately 18.81 nanoradians. Considering the optical magnification inherent in spaceborne telescopes, estimated at around 30 times, the resultant pointing deviation measurement accuracy reaches an impressive 0.62 nanoradians. This design precision significantly surpasses the stipulated 1 nanoradian accuracy requirement for ground-based gravitational wave pointing deviation measurements. As a prudential measure, the proposed design incorporates a substantial margin to accommodate potential accuracy diminution attributable to external perturbations during empirical testing.
星载望远镜 指向偏差测量 哈特曼 多子孔径空间复用 spaceborne telescope pointing deviation measurement Hartmann multi-subaperture spatial multiplexing
Youming Guo 1,2,3,4Kele Chen 1,2,3,4,5Jiahui Zhou 1,2,3,4Zhengdai Li 1,2,3,4[ ... ]Changhui Rao 1,2,3,4,*
Author Affiliations
Abstract
1 The Key Laboratory on Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China
2 Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
3 University of Chinese Academy of Sciences, Beijing 100049, China
4 School of Electronic, Electrical and Commutation Engineering, University of Chinese Academy of Science, Beijing 100049, China
5 National Key Laboratory of Optical Field Manipulation Science and Technology, Chengdu 610209, China
Integrating deformable mirrors within the optical train of an adaptive telescope was one of the major innovations in astronomical observation technology, distinguished by its high optical throughput, reduced optical surfaces, and the incorporation of the deformable mirror. Typically, voice-coil actuators are used, which require additional position sensors, internal control electronics, and cooling systems, leading to a very complex structure. Piezoelectric deformable secondary mirror technologies were proposed to overcome these problems. Recently, a high-order piezoelectric deformable secondary mirror has been developed and installed on the 1.8-m telescope at Lijiang Observatory in China to make it an adaptive telescope. The system consists of a 241-actuator piezoelectric deformable secondary mirror, a 192-sub-aperture Shack-Hartmann wavefront sensor, and a multi-core-based real-time controller. The actuator spacing of the PDSM measures 19.3 mm, equivalent to approximately 12.6 cm when mapped onto the primary mirror, significantly less than the voice-coil-based adaptive telescopes such as LBT, Magellan and VLT. As a result, stellar images with Strehl ratios above 0.49 in the R band have been obtained. To our knowledge, these are the highest R band images captured by an adaptive telescope with deformable secondary mirrors. Here, we report the system description and on-sky performance of this adaptive telescope.
adaptive optics deformable secondary mirror visible imaging Opto-Electronic Advances
2023, 6(12): 230039
1 中国科学院自适应光学重点实验室,四川 成都 610209
2 中国科学院光电技术研究所,四川 成都 610209
3 中国科学院大学,北京 100049
在天文大视场高分辨率成像领域,对地表层自适应光学(Ground-Layer Adaptive Optics, GLAO)系统作出准确的理论评估是系统设计与优化的关键前提。在GLAO技术中,地表层湍流特性与导引星布局是影响系统性能的重要因素。针对不同湍流环境与导引星位置分布,基于空间频谱滤波理论和蒙特卡洛方法对GLAO系统进行理论分析与性能评价工作,从而验证两种方法的正确性与准确性。结果表明,两种模型得到的系统校正规律呈现明显的一致性。在一定条件下,两种方法数值模拟偏差最大不超过4.6%。空间频谱滤波原理将系统简化为线性模型,其计算速度更快,便于发现系统特征规律,但是该方法适用于导引星呈对称布局的系统性能分析,不适用于非对称排布的任意导星布局解析分析。蒙特卡洛方法结合真实系统的物理过程进行实时模拟,其导引星布局可以任意设置,对于系统实际运行状态的预测更加准确。在两种分析方法对比的基础上,进一步针对系统布局给出了初步的优化结果,相关工作对未来GLAO系统的设计与优化具有指导意义。
地表层自适应光学 空间频谱滤波理论 蒙特卡洛 导引星 ground-layer adaptive optics spatial frequency spectrum filtering theory Monte Carlo guide stars 红外与激光工程
2022, 51(7): 20210744