基于微光机电系统的微光学自适应微镜的研究

提出了一种利用热应力改变镜面曲率的可调焦微光学自适应微镜。与传统自适应微镜相比,采用该原理制作的微镜具有驱动电压低和驱动力较大的优点,而且制作简单。以硅为基底进行了表面热氧化、光刻显影、HF酸刻蚀、KOH湿法刻蚀,溅射铝膜等微加工工艺的研究,获得硅铝双金属可调焦微反射镜4×4阵列,单元尺寸3 mm×3 mm,单晶硅基底厚60μm,硅表面溅射的铝膜厚150 nm。该微镜的镜面填充率为100%,可变形镜面占总镜面面积的79%。利用激光波面干涉仪对可调焦微反射镜的动态性能进行了测试。实验表明,该微镜可产生单向连续变形,最大变形量15.8μm,非线性滞后27%,工作电压0~2.5V,可调焦范围∞~0.036 m。     

基于遗传LM算法的涂层目标光谱偏振BRDF建模分析

通过比较测量方法测量得到绿漆涂层木板探测目标在400～720 nm的光谱偏振二向反射分布函数值,从获得的户外试验测量数据入手,分析与探测角、波长之间的关系,通过有限探测条件得到的光谱偏振二向反射分布函数值(BRDF)建立光谱偏振BRDF模型,来描述探测目标的偏振二向反射特性。其中利用基于小面元的模型建立光谱偏振BRDF模型,利用遗传算法和Levenberg-Marquardt(LM)算法相结合的优化算法来获得非线性模型参数。仿真实验结果表明采用的遗传LM优化算法具有较好的性能,能较快较准确得到非线性的模型参数。真实实验数据证明了基于小面元模型的正确性,表明光谱偏振二向反射分布函数建模方法结果的可靠性。最后与绿漆涂层铁板目标的模型反演参数进行比较得出：2种不同材质、相同颜色涂层的目标,具有较为接近的折射率,其较小差别可以理解为由涂层的厚度、均匀程度的不同导致,而非不同的材质所引起。     

Influence of annealing treatment on as-grown Ib-type diamond crystal at a high temperature and high pressure

In this paper,we report on the influence of annealing treatment on as-grown Ib-type diamond crystal under high pressure and high temperature in a china-type cubic anvil high-pressure apparatus.Experiments are carried out at a pressure of 7.0 GPa and temperatures ranging from 1700 C to 1900 C for 1 h.Annealing treatment of the diamond crystal shows that the aggregation rate constant of nitrogen atoms in the as-grown Ib-type diamond crystal strongly depends on diamond morphology and annealing temperature.The aggregation rate constant of nitrogen remarkably increases with the increase of annealing temperature and its value in octahedral diamond is much higher than that in cubic diamond annealed at the same temperature.The colour of octahedral diamond crystal is obviously reduced from yellow to nearly colorless after annealing treatment for 1 h at 1900 C,which is induced by nitrogen aggregation in a diamond lattice.The extent of nitrogen aggregation in an annealed diamond could approach approximately 98% indicated from the infrared absorption spectra.The micro-Raman spectrum reveals that the annealing treatment can improve the crystalline quality of Ib-type diamond characterized by a half width at full maximum at first order Raman peak,and therefore the annealed diamond crystals exhibit nearly the same properties as the natural IaA-type diamond stones of high quality in the Raman measurements.     

Enhanced luminescence of Tb by efficient energy transfer from Ce in Sr2B5O9Cl host

Ce³⁺ and Tb³⁺ co-doped Sr₂B₅O₉Cl phosphors with intense green emission were prepared by the conventional high-temperature solid-state reaction technique. A broad band centered at about 315 nm was found in phosphor Sr₂B₅O₉Cl: Ce³⁺, Tb³⁺ excitation spectrum, which was attributed to the 4f-5d transition of Ce³⁺. The typical sharp line emissions ranging from 450 to 650 nm were originated from the ⁵D₄ → ⁷F_J (J = 6, 5, 4, 3) transitions of Tb³⁺ ions. The photoluminescence (PL) intensity of green emission from Tb³⁺ was enhanced remarkably by co-doping Ce³⁺ in the Tb³⁺ solely doped Sr₂B₅O₉Cl phosphor because of the dipole-dipole mechanism resonant energy transfer from Ce³⁺ to Tb³⁺ ions. The energy transfer process was investigated in detail. In light of the energy transfer principles, the optimal composition of phosphor with the maximum green light output was established to be Sr_1.64Ce_0.08Tb_0.1Li_0.18B₅O₉Cl by the appropriate adjustment of dopant concentrations. The PL intensity of Tb³⁺ in the phosphor was enhanced about 40 times than that of the Tb³⁺ single doped phosphor under the excitation of their optimal excitation wavelengths.     

Phase Dependence of Fluorescence Spectrum of a Two-Level Atom in a Trichromatic Field

We examine the phase-dependent effects in resonance fluorescence of a two-level atom driven by a trichromatic modulated field. It is shown that the fluorescence spectrum depends crucially on the sum of relative phases of the sideband components compared to the central component, not simply on the respective phases. The appearance or disappearance of the central peak and the selective elimination of the sideband peaks are achieved simply by varying the sum phase. Once the sum phase is fixed, the spectrum keeps its features unchanged regardless of the respective relative phases.     

有限自由度系统的定域Lie对称性和守恒量

研究有限自由度系统定域Lie对称性的正问题和逆问题。给出了定域Lie对称性的定义、确定方程、结构方程和守恒量。进一步从定域Lie对称性导出在有限连续群无限小变换下的Lie对称性。最后给出一个例子去说明这些结果。     

不同窑口古代青瓷的产地特征的中子活化分析

产地属性是科学鉴别遗址和墓葬中出土的古陶瓷烧制产地的重要依据.用仪器中子活化（INAA）有损分析了浙江寺龙口越窑、江西洪州窑和陕西耀州窑出土的古瓷碎片样品,通过实验数据的统计分析,结果表明3个窑口古瓷的元素组成具有各自的特征,它们之间具有可以区分的依据,寺龙口越窑与南方江西洪州窑的制胎原料关系较近,与北方陕西耀州窑的关系较远.这些试验结果将为古陶瓷地研究提供重要参数.Provenance characteristic is an important scientific parameter to identify ancient porcelain wares unearthed from sites and graves.The porcelain samples of Si Long Kou kiln of Zhejiang Province,Hong Zhou kiln of Jiangxi Province and Yao Zhou kiln of Shanxi Province have been analyzed with neutron activation analysis(NAA) in this paper.The experimental data were studied with statistic methods.The results show that the chemical compositions of porcelain body samples for three kilns were different. The difference was been able identified. The body materials of both Si Long Kou Yue kiln and Hong Zhou kiln of Jiangxi were similar. The samples of Yao Zhou kiln in north of China existed obvious difference.     

热声系统中回热器特征阻抗与传播常数的研究

针对本实验室一台声驱动热声系统,采用传递函数法研究声驱动系统中回热器的特征阻抗和传播常数.通过调节谐振管长度,改变回热器表面的阻抗,从理论上分析了回热器网络传输方程中的声传播常数、特征阻抗与系统网络元件中的阻抗、导纳和流的关系.并且进一步讨论有无换热器以及不同的加热功率对回热器网络参数的影响.结论有利于进一步量化回热器的网络参数.