We demonstrate an ultrastable miniaturized transportable laser system at 1550 nm by locking it to an optical fiber delay line (FDL). To achieve optimized long-term frequency stability, the FDL was placed into a vacuum chamber with a five-layer thermal shield, and a delicate two-stage active temperature stabilization, an optical power stabilization, and an RF power stabilization were applied in the system. A fractional frequency stability of better than 3.2×10-15 at 1 s averaging time and 1.1×10-14 at 1000 s averaging time was achieved, which is the best long-term frequency stability of an all-fiber-based ultrastable laser observed to date.

为了满足空气动力学要求，采用共形薄壁结构的整流罩或光学窗口成为未来高速飞行器的发展趋势。但是这类零件在加工过程中，切削力会随着轴向位置发生改变，一次加工难以达到精度要求，需要通过在位测量、补偿加工来控制切削力变化所引起的面形误差。以超精密车床作为运动平台，设计高陡度薄壁光学零件的在位检测系统，研究测点分布的优化算法，实现测量效率和测量精度的统一；建立热变形误差修正模型，提高高陡度薄壁光学零件在位测量的精度。针对某型高陡度薄壁头罩，通过在位测量为补偿加工提供指导，将头罩表面误差由峰谷比（peak-to-valley, PV）3.1 μm控制到PV 0.7 μm，将同轴度控制到1.02 μm，满足光学系统的性能要求。

We demonstrate an all-fiber-based photonic microwave generation with 10-15 frequency instability. The system consists of an ultra-stable laser by optical fiber delay line, an all-fiber-based “figure-of-nine” optical frequency comb, a high signal-to-noise ratio photonic detection unit, and a microwave frequency synthesizer. The whole optical links are made from optical fiber and optical fiber components, which renders the whole system compactness, reliability, and robustness with respect to environmental influences. Frequency instabilities of 3.5×10-15 at 100 s for 6.834 GHz signal and 4.3×10-15 at 100 s for 9.192 GHz signal were achieved.

In this article, taking advantage of the special magnetic shieldings and the optimal coil design of a transportable Rb atomic fountain clock, the intensity distribution in space and the fluctuations with time of the quantization magnetic field in the Ramsey region were measured using the atomic magneton-sensitive transition method. In an approximately 310 mm long Ramsey region, a peak-to-peak magnetic field intensity of a 0.74 nT deviation in space and a 0.06 nT fluctuation with time were obtained. These results correspond to a second-order Zeeman frequency shift of approximately (2095.5±5.1)×10-17. This is an essential step in advancing the total frequency uncertainty of the fountain clock to the order of 10-17.

使用实验室自主研发的等离子抛光与刻蚀系统，研究了不同入射能量下不锈钢杂质辅助Ar⁺离子束刻蚀蓝宝石表面自组织纳米结构的形成机制。采用Taylor Surf CCI2000非接触式表面测量仪和原子力显微镜分别对刻蚀后蓝宝石样品的粗糙度、纳米结构的纵向高度和表面形貌进行了分析。研究表明：引入不锈钢杂质后，当离子束入射角度为65°、束流密度为487 μA/cm²、刻蚀时间为60 min、离子束入射能量为1 000 eV时，蓝宝石样品表面出现了纵向高度为11.1 nm高度有序的条纹状纳米结构；随着入射能量的增加，表面开始出现岛状纳米结构；当入射能量为1 200 eV时，形成了岛状与条纹状相结合的纳米结构，其纵向高度为13.6 nm；入射能量继续增加，蓝宝石表面岛状结构密度变大；当入射能量达1 400 eV时，样品表面岛状结构的纵向高 度为18.8 nm；入射能量为1 600 eV时，样品表面出现较为有序且密集的岛状结构，其纵向高度为20.1 nm。自组织纳米结构先是以“条纹”形状出现，随着入射能量的增加，引入的金属杂质打破了在离子束溅射过程中表面生长机制和表面平滑机制的平衡状态，形成了岛状结构，该结构促进了纳米结构的生长，改变了纳米结构的有序性。

使用微波回旋共振离子源刻蚀蓝宝石（C向）表面，引入金属不锈钢杂质，研究了不同靶距处蓝宝石表面自组织纳米结构的演化规律及光学性能。采用原子力显微镜来观察样品表面的形貌变化，Taylor Surf CCI 2000白光干涉表面测量仪测量蓝宝石样片表面的粗糙度；选择X射线光电子能谱对样品表面的化学成分进行了表征。实验结果表明：当离子束能量为1000 eV，束流密度为487 μA/cm²，入射角度为65°，刻蚀时间为60 min，蓝宝石样片与杂质靶距离从1 cm增加到4 cm时，样片表面出现岛状结构并逐渐演变为连续的条纹结构。同时，自组织纳米结构随靶距增加，有序性增加，纵向高度逐渐减小，空间频率基本不变。刻蚀后样品表面的金属杂质残留很少，微结构的形成对蓝宝石具有增透作用。在离子束溅射过程中，岛状结构的出现促进了样品表面条纹纳米结构的生长，破坏了纳米结构的有序性。