大口径SiC轻量化反射镜组件的结构设计

针对某空间相机1.1 m口径反射镜的光机结构设计任务,为降低反射镜的重量,提高其环境适应性,设计了一种重力变形小、抗振性强、热尺寸稳定性高的空间反射镜结构系统。首先,详细分析了反射镜及支撑结构选材依据及应考虑的主要因素。然后,提出一种背部半封闭式扇形轻量化孔的反射镜轻量化结构方案,并利用参数化建模分析的方法对其结构参数进行了优化设计。采用背部三点柔性支撑方式对反射镜进行支撑,通过柔性铰链的柔性来调节由于装配中的过定位和热环境变化导致的反射镜面形精度降低问题。最后,对反射镜组件的力学和热特性分析结果表明,反射镜在X向1 g重力作用下反射镜面形精度PV为62.4 nm,RMS为5.7 nm,在20±4℃环境温度变化范围内面形精度达到PV为61.7 nm,RMS为6.3 nm,反射镜组件基频为150 Hz,能够满足静态刚度、动态刚度和热尺寸稳定性的设计指标要求。     

单反式光端机反射镜柔性支撑参数化设计与试验

为保证单反式光端机指向捕获跟踪(Pointing, acquisition and tracking, PAT)时反射镜在恶劣空间环境下的面形精度,设计了一种底面开槽的柔性支撑结构。由于柔性支撑结构参数较多,为避免各参数之间严重耦合,采用正交优化方法对柔性支撑结构进行参数优化设计,再利用有限元方法对反射镜组件进行热力学特性分析。仿真分析结果表明,反射镜组件一阶频率为352.61 Hz,在1g重力和10℃温升(温降)共同作用下的最大面形误差RMS为λ/54.79(λ=623.8 nm),能够满足动、静态刚度和热尺寸稳定性要求。使用ZYGO干涉仪在(20±10)℃温度范围内对反射镜面形进行检测,结果表明,反射镜面形PV值优于λ/6,RMS优于λ/43,满足RMS≤λ/40的指标要求。实验结果表明,柔性支撑参数设计可靠,满足使用要求。     

空间遥感相机大口径反射镜结构优化设计

为满足大口径反射镜在复杂空间环境下对高面形精度和热稳定性的要求,针对某Φ660 mm口径反射镜进行了轻量化研究。提出了一种采用经典理论公式创建反射镜初始结构,结合灵敏度分析和参数优化进行综合设计的方法。首先构建了反射镜参数化模型,采用灵敏度分析研究镜体结构参数对面形变化的影响规律,找到对镜面面形RMS值灵敏度高的结构参数进行优化迭代。相比于传统反射镜结构设计方法,此方法缩小了优化设计空间,节约了计算成本与时间,能够在设计空间内全局寻优,较快收敛于最优值。优化后反射镜在自重载荷工况下镜面面形PV值小于λ/10,RMS值小于λ/40(λ=632.8 nm),镜体质量为13.6 kg,轻量化率达78.4%。镜体组件一阶频率为121 Hz,满足反射镜动态刚度要求,根据优化后的结果建立了反射镜的最佳结构模型,并进行了投产制造。     

大口径空间反射镜组件结构设计与分析

设计了某1.2 m口径的空间光学反射镜结构及其支撑结构系统。首先,合理选取了反射镜及其支撑结构的材料。从反射镜镜坯制作工艺、力学特性、热特性以及反射镜重量等因素考虑,最终选取基于反应烧结SiC材料的背部半开放式扇形轻量化孔的反射镜结构形式,反射镜设计重量为87.6 kg,轻量化率达到79%。其次,确定了在光轴水平状态下进行检测装调的方案,并进行其支撑结构的设计,采用3个双轴柔性铰链从背部对反射镜支撑,使大口径反射镜同时满足静态刚度、动态刚度、强度和热尺寸稳定性的要求。最后,对反射镜进行了组件级有限元分析。结果表明,反射镜在X向重力和4℃均匀温升作用下面形RMS分别为7.8 nm和9.4 nm,反射镜组件一阶固有频率为153 Hz,满足设计指标要求。     

空间相机反射镜SiC/Al 支撑板轻量化结构优化设计

在保证空间光学遥感相机反射镜组件结构刚度、位置精度、面形精度的同时,最大限度地降低反射镜支撑板的质量,是轻量化设计的一个重要内容。提出了通过拓扑优化确定反射镜用SiC/Al 材料的背部支撑板轻量化形式的方案。采用有限元分析法对获得的优化结果进行分析。分析结果表明: 重力载荷下面形精度达到/10 PV,/50 RMS（=632.8 nm）,PV 值13.3 nm,RMS 值2.9 nm,反射镜组件一阶固有频率239 Hz,均优于传统结构形式的反射镜。拓扑优化的方法获得的轻量化背部支撑板能够满足使用要求。     

空间引力波望远镜主反射镜系统的结构设计优化

针对空间引力波望远镜主反射镜系统的结构及支撑组件进行了设计与优化。主反射镜运用了侧面3点支撑对镜体进行约束,并对支撑点的选取与布局进行了研究。反射镜采用能够实现较大弯曲刚度的背部钻孔式半封闭构型,通过有限元计算结合多目标遗传算法对反射镜轻量化结构进行了参数优化,在不降低面形精度的条件下使镜体结构轻量化率达到74%。设计了一种由两个无阻隔串联式柔度单元组合而成的可调节双轴连杆型Bipod柔性铰链结构,其可对反射镜面形误差进行补偿。建立了柔性铰链并联机构作用于反射镜的数学模型,对其进行了基于MATLAB的参数取值分析,并通过有限元方法完成了对参数取值的修正。最后进行了空间热载荷条件下的反射镜面形分析,结果表明反射镜面形误差优于λ/60,满足设计要求。     

小型反射镜中心支撑技术

所述空间遥感器反射镜的工作温度为18±15℃,要求反射镜在此复杂工况条件下满足设计要求.介绍了反射镜材料和支撑结构材料的选择;对反射镜的支撑方式、轻量化等方面进行了分析讨论;根据反射镜柔性支撑结构的设计原理,采用CAD/CAE工程软件进行了分析及优化,通过有限元法优化设计了一种反射镜中心支撑的柔性结构,在此温度变化范围内,反射镜面形误差变化量PV值小于λ/10、RMS值小于λ/40(A=632.8nm).最后,通过力学环境实验测试反射镜面形变化量和反射镜组件模拟件的动态特性,证明该结构满足设计要求.     

大口径离轴反射镜四点热锁辅助支撑设计与验证

针对大口径离轴反射镜组件高面形精度、高可靠性和高稳定性支撑的要求,设计了一种中心筒支撑配合四点可自由加、解热锁辅助支撑的离轴反射镜新型复合支撑方案,热锁部件在力学试验和发射过程中锁紧,地面测试及在轨时释放,在保证面形的同时,有效提升了反射镜组件基频及抗力学性能,并在某空间遥感器706 mm×560 mm口径离轴反射镜组件研制中进行了验证,结果表明采用四点热锁辅助支撑的反射镜组件在加锁后动态性能优良,满足基频大于120 Hz、静载30 g条件下胶应力≤3 MPa的要求,且加锁前及解锁后面形均满足RMS优于λ/40 （λ=632.8 nm）的要求,验证了该设计的有效性。     

空间引力波望远镜主镜组件的结构设计

针对空间引力波望远镜皮米量级的极高光程稳定性需求,对系统中主镜组件进行了优化设计。采用微晶玻璃（Zerodur）作为反射镜材料,支撑结构材料为铟钢（4J36）。首先,通过对反射镜参数的优化,使其在保证面形精度的同时镜体轻量化率达到了72%。然后,设计了一种双轴联杆型Bipod柔性反射镜支撑结构,并采用了侧面三点支撑的形式。以保证有效的支撑刚度及卸载效果为目的,建立了柔性铰链的数学模型,并基于Matlab对其尺寸参数进行了优化。最后,对优化设计后主镜组件进行了模态分析及振动试验,并完成了在轨分析与波前质量计算。结果显示,主镜组件的一阶固有频率为373 Hz,与试验结果的相对误差为3.5%;在轨环境下主镜面形精度达到8.9 nm（RMS）;波前精度为/5（=1 064 nm）。表明该反射镜组件满足设计指标要求。     

空间遥感器长条形平面镜的背部支撑技术

某空间遥感器的大长宽比长条形平面镜的要求是在尽量减小重量的前提下,在工作温度为20±5℃条件下,反射镜的面形误差变化量(Root Mean Square, RMS)值小于λ/50 (λ=632.8 nm)。介绍了反射镜材料和支撑结构材料的选择;对反射镜的轻量化及支撑方式进行了分析。根据反射镜的外形特点,增加了镜背的局部宽度,并将其设计成了背部三点支撑形式。通过有限元分析,优化并确定了反射镜及其柔性支撑结构。反射镜位移及面形的分析结果满足设计指标要求。最后,通过力学环境试验测试了反射镜组件模拟件的力学特性,证明该结构能满足设计要求。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

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