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.

Overview: Space gravitational wave detection missions typically consist of three identical satellites, with two laser links between the satellites at an angle of sixty degrees forming a Michelson interferometer. The arm length changes are measured using high-precision inter-satellite laser interferometry. As a key component of the inter-satellite laser interferometry system, the telescope system needs to have picometer-level optical path stability, a wavefront error of λ/30, and stray light less than 10^?10 of the transmitted power. To meet the requirements of space gravitational wave detection for the telescope system, an optical and mechanical integrated analysis and optimization method is proposed to design and optimize the primary mirror and its supporting structure. The off-axis parabolic primary mirror adopts the side three-point support method, and the influence of the support point position on the mirror surface shape and the rigid body displacement under gravity conditions has been studied. Optimization of the size of the triangular lightweighting holes on the primary mirror has been performed, and density-based topology optimization has been used to optimize the support backplate while ensuring that the first-order mode of the primary mirror component remains essentially unchanged. The flexural matrix of the primary mirror component supported by a parallel bipod linkage structure was derived based on spinor theory, and an evaluation function for the support structure was established. The size parameter range of flexible support was preliminarily determined by Matlab analysis. A optical-mechanical integrated simulation platform is set up to optimize the parameters of the support structure using a weighted sum method to convert the multi-objective optimization problem into a single-objective optimization problem. The results showed that the first-order frequency of the primary mirror component system was 392.43 Hz. Under gravity and temperature loads, the deformation of the primary mirror surface was better than λ/60, the translational rigid body displacement was better than 2.5 μm, and the rotational rigid body displacement was better than 0.5 μrad, all of which met the design specifications. Under space thermal disturbance of 10 μK/Hz^1/2, the size stability of the primary mirror component, represented by the displacement of the central point of the mirror, was at a level of 10 pm/Hz^1/2.

近年来，近红外荧光粉转换发光二极管（NIR pc-LED）在夜视、生物成像和无损检测等领域引起了广泛关注。然而，获得兼具高量子效率和优异热稳定性的近红外荧光粉仍然是一个巨大挑战。本文利用高温固相法合成了一种新型近红外荧光粉BaY₂Al₂Ga₂SiO₁₂∶Cr³⁺（BYAGSO∶Cr³⁺），并系统研究了材料的结构和发光性质。在440 nm蓝光激发下，BYAGSO∶Cr³⁺荧光粉的发射光谱在650~850 nm范围内呈现锐线和宽带的混合发射，源于Cr³⁺：²E→⁴A₂自旋禁戒跃迁和⁴T₂→⁴A₂自旋允许跃迁发射。该近红外发光表现出可观的量子效率和良好的热稳定性，最优化样品的外量子效率可达30.3%，在200 ℃时样品的发光强度可保持其在室温时强度的99%。通过将BYAGSO∶Cr³⁺荧光粉与450 nm蓝光LED芯片结合，我们封装了一个NIR pc-LED器件。该器件在300 mA驱动电流下，输出功率为70.83 mW；在20 mA驱动电流下，光电转换效率为11.20%。研究结果表明，BYAGSO∶Cr³⁺在NIR pc-LED领域具有良好的应用前景。

为了开发出高效稳定的单一基质白光发射荧光材料，本工作通过高温固相法成功合成了一系列La₄GeO₈∶Bi³⁺，Eu³⁺荧光粉样品，并通过X射线衍射、室温光谱、变温光谱等手段研究了实验样品的结构与发光性能。研究发现，Bi³⁺离子在该结构中占据两种不同的格位（Bi³⁺（Ⅰ）和Bi³⁺（Ⅱ）），且在紫外光激发下呈现两个峰值分别在475 nm和620 nm的宽带发射。对于Bi³⁺、Eu³⁺共掺样品，由于Bi³⁺（Ⅰ）与Eu³⁺之间的竞争吸收、Bi³⁺（Ⅰ）至Bi³⁺（Ⅱ）以及Bi³⁺（Ⅱ）至Eu³⁺的能量传递作用，可实现蓝色至红色、橙红色至红色的可调发光。特别地，样品La₄GeO₈∶0.07Bi³⁺，0.06Eu³⁺在313 nm光激发下可获得CIE值为（0.335，0.319）的优异白色发光。此外，该白光发射材料具有较佳的发光热稳定性，当温度升高至380 K时，发光积分强度仍然为室温的59%，表明其在白光二极管上具有潜在的应用价值。

研究了粉末原子层沉积技术（ALD）在白光LED用K₂SiF₆∶Mn⁴⁺（KSFM）红色荧光粉包覆和表面改性中的应用，以及对其结构特性、发光性能和湿热环境中稳定性的影响。结果表明，采用ALD技术以三甲基铝作为前驱体、臭氧作为氧化剂，可以在KSFM表面形成氧化铝包覆层。X射线衍射、表面形貌分析表明，ALD处理过程不会影响KSFM荧光粉的晶相和形貌特征。发光光谱分析表明，由于氧化铝钝化特性还会增强KSFM荧光粉的发光强度，并且不改变其发光波长。相较于未经包覆的KSFM荧光粉，包覆层可以显著改善KSFM粉末的湿热环境稳定性，ALD包覆后样品的相对发光强度在85%湿度/85 ℃环境中老化处理24 h后仍能保持初始值的84%。

针对深空探测超宽光谱定标黑体源的关键技术问题，构建了一种基于优化微结构和纳米超黑涂层的深空探测星上黑体定标源。基于有限元方法仿真，验证了微锥结构不同宽高比与黑体发射率间的对应关系，确定了周期性线阵V槽结构相对于平面结构在黑体发射率方面的提升作用。优化星上黑体源高发射率微结构，优选空间超黑高发射涂层，设计星上黑体源高精度测温系统，进而完成黑体源工程设计。最后，通过星上黑体源发射率计量及实验室辐射定标稳定性测试进行验证。检测结果表明，深空探测超宽光谱定标黑体源具有超宽光谱范围、高发射率、高温度稳定性等特点，其光谱范围为5~50 μm，法向平均发射率为0.986，温度稳定性达到0.16 K。该定标黑体源可大幅提升高发射率辐射定标源的光谱范围，为深空探测载荷的在轨高精度星上辐射定标提供支撑。

光学电压传感器在温度稳定性方面仍有亟待解决的问题，一是电光晶体在温度变化时存在温度梯度，导致表面温度与光路温度不等；二是晶体物性参数也会受到温度影响。为此提出一种基于温度场与双卡尔曼滤波（Dual Kalman，D-Kalman）参数估计的温度补偿方法。以锗酸铋晶体为研究对象，在对传感器输出信号进行交直流分离的基础上，先利用半解析法建立晶体暂态温度场模型，再分别通过卡尔曼滤波与中心差分卡尔曼滤波实现对晶体内部温度和初始温度下晶体折射率的状态估计，最后将修正参数与传感器输出信号高频分量相结合计算补偿电压。实验结果表明，传感器在外界温度为［20 ℃，40 ℃］以0.5 ℃/min速率不断升高的环境下，暂态温度场解析式的仿真精度在0.02%以内，实验测量精度在0.2%左右，补偿输出电压测量精度优于0.52%。与同平台下反向传播神经网络温度补偿效果以及不同平台下的补偿效果相比，该方法提高了传感器测量精度。

本研究在不同气氛（空气、氮气）、分散液（水、甲醇、乙醇）以及不同剂量条件下对4种典型的金属有机框架材料（MOFs）（MIL-101（Cr）、ZIF-8、UiO-66和UiO-66-NH₂）进行了电子束辐照处理。通过傅里叶变换红外光谱、X射线衍射谱和扫描电子显微镜等方法对MOFs材料在辐照前后的化学组成、晶体结构和表面形貌进行表征。结果表明，上述4种MOFs材料在高于5 000 kGy的剂量辐照后，其相应的红外特征峰、衍射峰和表面形貌特征均未产生显著变化，表现出了良好的辐射稳定性。这为MOFs材料在辐射环境下的进一步应用提供了研究基础。

液晶空间光调制器通过改变驱动电压强度控制液晶分子排布实现对光的调制。紫外区域可用的液晶空间光调制器随光聚合式3D打印等应用的兴起，重要性日益显现。然而绝大多数液晶材料都是有机物，在紫外波段存在光吸收和光反应。为了拓宽液晶材料的应用波段，本文通过选择在应用波段不发生紫外吸收和光反应的官能团，设计了一类可在325~400 nm波段应用不发生光吸收和光反应的液晶材料，并对液晶材料的紫外-可见光光谱进行仿真以验证设计的合理性。将耐紫外液晶化合物配置成混合液晶材料后与常见的两种混合液晶材料的紫外稳定性进行比较。在经过120 min的325 nm紫外光源的辐照后，液晶材料的吸光度和相变温度几乎不变，双折射率变化0.04%，阈值电压变化1.39%，响应时间变化0.32%。