微机械光读出红外成像阵列器件 机械特性对其性能的影响

研究了具有"双材料梁-微镜一体化"特征结构的光读出红外成像阵列器件的机械特性对其性能的影响。通过理论计算和ANSYS模拟,分析了器件的热-机械灵敏度,对器件的结构参数进行了优化,并得到其热-机械灵敏度为2.14×10^-3 rad/K;从器件的频率和阻尼特性出发,研究了器件的机械特性对热振动噪声和机械稳定性能的影响。研究结果表明:绝热梁断裂所需冲击载荷为8 945 g;器件的工作气压确定在50~200 Pa时,其热机械噪声和外界机械振动引起的噪声对器件性能的影响可忽略。该器件基本满足红外成像阵列器件的高灵敏度、低噪声的要求。     

铜锌合金及20CrMnTi钢中温塑性加工的规律和机理的研究

本文研究了H68黄铜和20CrMnTi 钢的动态应变时效(DSA)和动态退火(DA)对其机械性能的影响。试验是在300—1100K 的温度范围内进行的,应变速度为1.1×10^-2s^-1到1.1×10^-4s^-1,平均晶粒尺寸为10μm。试验结果表明:H68黄铜的最大均匀应变量和加工硬化参数均在某一温度范围内出现一个峰值,而20CrMnTi 钢则在高温区和低温区分别形成一个峰值。试验的另一个结果是发现动态应变时效现象与动态退火现象在靠近临界温度时有一定的重叠。建议在研究中温塑性加工的规律时,有必要考虑这两种现象的影响。     

ZnO薄膜非线性光学特性的实验研究

利用金属有机化学气相沉积(MOCVD)技术在蓝宝石衬底上生长一层高质量的ZnO薄膜。为了考察沉积温度对样品的非线性特性的影响,在200~500 ℃生长了一系列ZnO薄膜。用X射线衍射谱(XRD)及扫描电镜(SEM)对样品结构进行了评价。以Nd:YAG激光器输出的1.06 μm的激光为基频光,对ZnO薄膜样品的二阶及三阶非线性光学特性进行了实验研究。实验发现,对于250 ℃沉积温度的样品有较强的非线性效应,实验测得的二阶非线性极化张量 χ ⁽²⁾_ZZZ=9.2 pm/V, 三阶有效非线性系数χ⁽³⁾=5.28×10^－20 m²/V²。     

红外分光计:液氦冷却火箭运载圆形渐变泸光器

这里密述ICECAP极光测量计划所用一种红外分光计、从高度45公里到200公里的火箭上取得大气发射光谱,这仪器连续扫描6.75—23.2微米光谱区,扫速为2次扫描/秒,仪器使用一个圆形渐变滤光器(CVF),光谱分辨率从3%到4%.全部光学组件、矽砷探测器、CVF、Irtran6透镜、挡壳、可卸的冷却罩装在一个高真空杜瓦瓶系统内冷却到10k以下,分光计在22微米处噪音等效光谱辐射(NESR)优于1×10^-1(W厘米^-2球面度^-1微米^-1).两次火箭飞行观察到高空大气发射占优势的是9.6—微米O₃和15微米CO₂.     

滚珠轴承动量轮最佳运行状态的实验确定

对于35牛顿·米·秒偏置动量轮,在轴承加载量为2公斤到10公斤范围内,环境真空度从1×10^-4τ到1个大气压范围内,进行了实验研究.结果指出,在轴承预载为10公斤左右,环境真空度约为1τ时,达到最佳运行状态.稳态功耗小于8W,与国外同类产品一致.     

激光锁相环

本文报导了由两个激光器获得的频率相同(约为5×10¹⁴周/秒)、相位差小于1/3度的振荡试验。     

高平均功率腔内和频蓝光Nd:YAG激光器

高平均功率蓝光激光是当前固体激光技术研究热点之一。尽管通过Nd³⁺的⁴F_3/2→⁴I_9/2态谱线倍频可获得瓦级蓝光输出,然而其准三能级物理特性严重限制其更高功率输出。研究了Nd³⁺离子⁴F_3/2→⁴I_13/2态1.3 μm谱线腔内三倍频产生高平均功率蓝光激光,获得4.3 W蓝光激光输出,重复频率3.5 kHz,脉冲宽度150±10 ns,光束质量M²因子约为5±1。研究表明:Nd∶YAG晶体1.3 μm多谱线振荡是制约实验结果的重要因素,若克服多谱线振荡问题,有望获得10 W级蓝光激光输出。     

氟化锂椭圆弯晶分析器的特性及应用

设计了测试能量范围为0.6~6 keV的椭圆弯晶谱仪。此谱仪利用椭圆自聚焦原理,晶体分析器采用氟化锂材料,椭圆焦距为1 350 mm,离心率为0.958 6,布拉格角范围为30~65°。在神光Ⅱ靶室进行了实验,入射激光波长为0.35 μm,激光功率约为1.6×10¹⁴ W/cm²,与厚度为100 μm的钛平面靶法线夹角约为45°。实验结果证实,弯曲的氟化锂晶体具有极佳探测效果,弯晶分析器对波长为0.2~0.35 nm的X射线的分辨率可达500~1 000,同时具有等光程而便于空间分辨测量的优点,在同样距离条件下比平晶分析器高一个数量级的收光效率,故适合于激光等离子体X射线的光谱学研究。     

面向CMB偏振实验的220 GHz钛超导TES探测器技术研究

高灵敏度超导相变边缘探测器(Transition Edge Sensor,TES)在宇宙微波背景(Cosmic Microwave Background,CMB)辐射B模偏振探测方面具有重要的应用前景。本文设计并制备了220 GHz频段8×8像元的天线耦合钛超导TES探测器，实验表征了刻蚀前钛超导TES探测器的低温热导和噪声特性。实验结果显示，钛超导TES探测器低温电声相互作用主导热导约为485.4 pW/K，同时钛超导TES探测器噪声等效功率优于5×10^-17 W/Hz0.5。原理上，钛超导TES探测器热导在刻蚀后会进一步减小，理论计算出刻蚀后钛超导TES探测器的热导约为38 pW/K，同时，其热起伏等效噪声功率理论值约为9.2×10^-18 W/Hz^0.5，因此，钛超导TES探测器在刻蚀后的噪声等效功率性能会进一步提升。     

差动电磁作动器的超大型光学仪器 隔振基础的主动控制机理

提出了一种基于差动电磁作动器的超大型光学仪器隔振基础的主动控制机理。该控制机理采用差动布置方案,使电磁作动器变为输出力和控制电流呈线性关系的线性作动器,再利用小阻尼条件下,绝对速度反馈与Skyhook控制方法性能接近且易于工程实现的特点,采用了绝对速度反馈的控制方法,可在不改变中/高频隔振性能的前提下大幅提高谐振区隔振性能。实验结果表明:利用所提出的控制机理,在时域上,z、θ_x和θ_y三个自由度的速度(角速度)均方根值分别由10.06 μm/s、4.16×10^－6rad/s和4.65×10^－6rad/s降至3.38 μm/s、1.76×10^－6rad/s和1.49×10^－6rad/s;在频域上,三个自由度谐振区隔振性能均有约10 dB的提高。     

Niobium direct detectors for fast and sensitive terahertz spectroscopy

We report the performance of a niobium hot-electron bolometer designed for laboratory terahertz spectroscopy. The antenna-coupled detector can operate above 4.2 K and has fast (subnanosecond) response. Detailed microwave measurements of performance over a wide range of operating conditions were correlated with quantitative terahertz measurements. The maximum responsivity is 4 x 10(4) VW with a noise equivalent power at the detector of 2 x 10(-14) W/Hz(12), approaching the intrinsic thermal fluctuation limit for the device. This detector enables a variety of novel laboratory spectroscopy measurements.     

Ultra-sensitive thermal conductance measurement of one-dimensional nanostructures enhanced by differential bridge

Thermal conductivity of one-dimensional nanostructures, such as nanowires, nanotubes, and polymer chains, is of significant interest for understanding nanoscale thermal transport phenomena as well as for practical applications in nanoelectronics, energy conversion, and thermal management. Various techniques have been developed during the past decade for measuring this fundamental quantity at the individual nanostructure level. However, the sensitivity of these techniques is generally limited to 1 × 10(-9) W∕K, which is inadequate for small diameter nanostructures that potentially possess thermal conductance ranging between 10(-11) and 10(-10) W∕K. In this paper, we demonstrate an experimental technique which is capable of measuring thermal conductance of ～10(-11) W∕K. The improved sensitivity is achieved by using an on-chip Wheatstone bridge circuit that overcomes several instrumentation issues. It provides a more effective method of characterizing the thermal properties of smaller and less conductive one-dimensional nanostructures. The best sensitivity experimentally achieved experienced a noise equivalent temperature below 0.5 mK and a minimum conductance measurement of 1 × 10(-11) W∕K. Measuring the temperature fluctuation of both the four-point and bridge measurements over a 4 h time period shows a reduction in measured temperature fluctuation from 100 mK to 0.6 mK. Measurement of a 15 nm Ge nanowire and background conductance signal with no wire present demonstrates the increased sensitivity of the bridge method over the traditional four-point I-V measurement. This ultra-sensitive measurement platform allows for thermal measurements of materials at new size scales and will improve our understanding of thermal transport in nanoscale structures.     

激光测距与跟踪系统低噪声电子设计方法

各种电子元器件,光电转换器件存在着各种各样的噪声,如散弹噪声、1/f噪声、热噪声在系统中还存在背景噪声等等.降低噪声,一直是提高系统作用距离的主要研制任务.本文以噪声的基本理论为基础,从工程的角度论证在激光测距与跟踪系统设计中主要的噪声源与低噪声设计方法.并以实例介绍了在工程中应用的前置放大器设计方法.     

Trace gas detection based on off-beam quartz enhanced photoacoustic spectroscopy: optimization and performance evaluation

A gas sensor based on off-beam quartz enhanced photoacoustic spectroscopy was developed and optimized. Specifically, the length and diameter of the microresonator tube were optimized, and the outer tube shape is modified for enhancing the trace gas detection sensitivity. The impact of the distance between the quartz tuning fork and an acoustic microresonator on the sensor performance was experimentally investigated. The sensor performance was evaluated by determining the detection sensitivity to H(2)O vapor in ambient air at normal atmospheric pressure. A normalized noise equivalent absorption coefficient (1σ) of 6.2×10(-9)?cm(-1)?W/Hz(1/2) was achieved.     

钬激光碎石术中结石位移的影响因素

为了减小钬激光碎石术中结石产生的位移,研究了钬激光脉冲峰值功率、激光烧灼尺寸和工作距离对于结石位移的影响。分析了影响结石位移的因素,搭建了一个体外模型装置以此来模拟输尿管内钬激光碎石的过程,实验使用0.25 g的正方体石膏模型来代替人体结石,钬激光功率选择12 W(0.6 J×20 Hz,0.8 J×15 Hz,1.2 J×10 Hz)和20 W(0.8 J×25 Hz、1.0 J×20 Hz、2.0 J×10 Hz),脉冲持续时间为200μs和800μs,光纤使用272μm以及550μm,工作距离从0~5 mm。最后,将体外模型置于水中,在室温进行实验。实验结果表明,结石位移随着脉冲峰值功率的增大而增大;较长的脉冲持续时间可以减小16.95%~27.27%的结石位移;272μm的光纤相比于550μm的光纤能够减少35.59%~54.17%的结石位移;增大工作距离可以减小结石位移,同时降低消融效率,但当结石模型与光纤顶端接触时,会产生吸附挣扎的现象。上述结论为改进国产钬激光器设计以及钬激光参数精细化设置提供了参考,对于临床手术有借鉴意义。     

空间光谱成像仪热设计参数的灵敏度

针对空间光学遥感器在轨运行期间其热物理属性的实际参数与热设计参数之间存在一定的偏差,从而影响整机热设计的问题,本文基于系统灵敏度理论,对空间光学遥感器的热设计进行了分析,并建立了在轨条件下的热平衡方程组.通过分析热平衡方程组的设计变量,总结出影响整机温度分布的热设计参数.以某空间光谱成像仪热设计为例,分析了上述影响整机温度分布的设计参数的灵敏度.灵敏度分析结果表明:整机平均温度对太阳吸收系数的灵敏度几乎为零;对红外半球发射率的灵敏度为2.2～14.55℃;对内部热源的灵敏度为1.8～2℃/W;对导热率的灵敏度为2.25×10-3～4.39×10-2 m℃2/W:对接触导热系数的灵敏度为0～1.1×10-3 m2℃2/W.试验验证结果表明,基于灵敏度分析结果的热控设计方案有效且可行.     

Highly sensitive thermal conductivity measurements of suspended membranes (SiN and diamond) using a 3ω-Völklein method

A suspended system for measuring the thermal properties of membranes is presented. The sensitive thermal measurement is based on the 3ω dynamic method coupled to a Vo?lklein geometry. The device obtained using micro-machining processes allows the measurement of the in-plane thermal conductivity of a membrane with a sensitivity of less than 10 nW/K (+∕-5 × 10(-3) Wm(-1) K(-1) at room temperature) and a very high resolution (ΔK/K = 10(-3)). A transducer (heater/thermometer) centered on the membrane is used to create an oscillation of the heat flux and to measure the temperature oscillation at the third harmonic using a Wheatstone bridge set-up. Power as low as 0.1 nW has been measured at room temperature. The method has been applied to measure thermal properties of low stress silicon nitride and polycrystalline diamond membranes with thickness ranging from 100 nm to 400 nm. The thermal conductivity measured on the polycrystalline diamond membrane support a significant grain size effect on the thermal transport.     

Sensitive Faraday rotation measurement with auto-balanced photodetection

A magneto-optic polarimetry based on auto-balanced photodetection is investigated. In this experiment, a commercial auto-balanced photoreceiver is adopted to measure the Faraday rotation of air. With a proper setup to utilize its noise cancellation capability, the measurement can be flexible and sensitive. The angular sensitivity is 2.99×10(-8) rad Hz(-1/2), which is about 2.7 times the shot noise limit. The measured Verdet constant of air is +1.39×10(-9) rad G(-1) cm(-1) at 634.8 nm. Significantly we applied a small AC current to induce the magnetic field, so there was no heating in the coil. In addition, a double current modulation scheme was used to demonstrate that there was no zero drift and amplifier instability in the measurement. The possibility of improvement of the angular sensitivity and the potential applications are also discussed.     

Extraction of Barkhausen noise from the measured raw signal in high-frequency regimes

This paper deals with extraction of pure Barkhausen noise from the raw signals received in high-frequency regimes. The raw Barkhausen noise signals measured in high-frequency regimes contain components which cannot be attributed to the interaction of Bloch Walls with pinning sites and stress states such as the thermal noise of the sensor and the mechanical vibrations of the sensor-exciting core. Due to the variable ratios of thermal noise to Barkhausen noise as well as distortion of the signal due to vibrations, the raw signal as received and the pure Barkhausen noise signal can differ remarkably, thus making signal interpretation a debatable issue. For this reason, the post-processing method of the measured signal is presented here. In addition, the properties of μScan 500 device are analysed in detail.