TiO2纳米线阵列干涉传感器

开发一种新型TiO₂纳米线阵列干涉传感器。首先,通过水热合成法在FTO导电玻璃表面制备了TiO₂纳米线阵列薄膜。然后,以此复合结构作为传感芯片,利用Kretschmann 棱镜耦合结构,构建了基于Kretschmann结构的波长调制型薄膜干涉传感器。最后,以氯化钠水溶液为待测液体介质研究了该传感器对环境介质折射率的灵敏性能。结果表明：该传感器对1.333 5~1.360 4范围内的折射率有很好的响应。TM模式下,在0~3%与3~15%浓度范围内,氯化钠浓度与该传感器的反射光强度分别呈现了良好的线性关系。TE模式下,在0~3%浓度范围内,氯化钠浓度与吸收强度存在良好的线性关系,而波长基本不变;而在3~15%浓度范围内,随着氯化钠浓度的增加,波长逐渐红移,氯化钠浓度与波长也具有良好的线性关系。     

高能闪光照相密度测量的LEPM方法

研究了利用高能闪光照相方法实现密度分布测量的技术.根据闪光照相投影成像原理,将成像过程中的非线性成像因素看成一个综合性的非线性算子,利用先验测量的方法该非线性算子的响应曲线,利用该曲线校正成像图像得到待测客体的光程分布图像.采用以最小误差为重建准则的代数重建法,从光程分布图像中重建出照相客体的线吸收系数分布.最后利用相对等效质量吸收系数以及客体总质量不变的约束条件,获得照相客体的空间密度分布.在高能闪光照相实验平台上进行了静态客体的密度测量实验,测量的均方根误差约为10％.     

High resolution spectroscopy of Rb in magnetic field by far-detuning electromagnetically induced transparency

We have presented a high resolution spectroscopy of Rb in magnetic field by far-detuning electromagnetically induced transparency (EIT). The EIT spectrum in the $Xi$-type configuration is usually companied by a double resonance optical pumping (DROP) due to the strong optical coupling between the two upper states, leading to the spectral lines seriously deformed and widely broadened for complex relaxation processes in DROP. Here we demonstrate a high resolution spectroscopy by far-detuning EIT for $^{87}rm{Rb}$ $rm{5S_{1/2}rightarrow5P_{3/2}rightarrow5D_{5/2}}$ in magnetic fields. The method of far-detuning eliminates the relaxation in DROP to the most extent and decreases the spectral linewidth from more than 20 MHz down to its natural linewidth limit (6 MHz). The deformation of the spectral lines also disappears and the observed spectra are well in accordance with the theoretical calculation. Our work shows that far-detuning EIT is a reliable high resolution spectroscopic method when the relaxation in DROP cannot be neglected, especially for the case of transition to low excited states.     

银纳米颗粒复合超材料的数值和模拟研究

理论分析了单层银纳米颗粒及其复合超材料的电磁特性,并采用MATLAB数值计算和CST模拟对理论进行了验证.结果显示:4.75 nm银颗粒所形成的单层阵列的数值和模拟结果都有Lorentz共振效应出现,模拟结果相对于数值计算有红移现象,且有微弱的磁共振效应,进一步对采用4.75 nm颗粒复合而成的100 nm大颗粒模拟,...     

同步辐射压弯准直镜姿态的检测--大曲率半径小口径光斑的波前检测

提出了利用微小楔角剪切干涉仪测量同步辐射压弯准直镜姿态的方法。利用透镜和针孔产生与同步辐射发散度相同的激光束。通过剪切干涉仪．测量经压弯准直镜输出激光束的平行度,可将准直镜的位置、俯仰角度和镜面曲率皆调整到最佳。该剪切干涉仪结构简单,可根据条纹图样判断光束的平行度,每一幅干涉条纹图样与准直镜的一种姿态对应,因而这种方法能确定准直镜表面各点反射X射线的整体效果。该方法适用于测量波前曲率半径大竖直口径小的光束,不但精度高．而且具有实用价值。     

基于FPGA和蓝牙的远程图像采集同步系统

针对核物理实验中高精度时间同步触发图像采集系统的要求,设计了一套基于FPGA和蓝牙的远程图像采集同步系统。该系统以FPGA作为主控制器,负责USB 接口通信、命令解析、蓝牙通信和同步控制等,触发信号延时精度可达10 ns;使用RS485 或TTL 标准以适应长距离触发和短距离触发,通过GigE 千兆网口实现远程图像数据采集。采用LabVIEW 开发了上位机图形化软件界面,基于蓝牙BLE4.0 协议,实现了基于手机APP的无线终端控制,完成了对相机延时时间、同步触发脉冲宽度、图像采集等命令的同步控制。A image acquisition and synchronization control system based on FPGA (Field Programmable Gate Array) and bluetooth is studied in this paper. FPGA as the main controller is responsible for USB (Universal Serial BUS) interface, command analyze, delay control, and trigger signal generation. Trigger signal can be RS485 or TTL. RS485 signals can be used for long-distance transmission without distortion while TTL is suitable for near field. The system's delay accuracy is reached to 10ns. It can be obtain images from GigE Ethernet port. Meanwhile,a PC graphical control software is developed by LabView. And based on the Bluetooth BLE4.0 protocol, a Android mobile phone APP is developed for wireless control.     

X射线衍射增强相衬成像相位信息提取方法研究

基于同步辐射的X射线衍射增强相衬成像有效地应用于低吸收轻物质(例如软组织)材料的内部结构检查,其关键技术是如何从DEI图像中提取出反映物体相位梯度信息的折射角图像.本文在综合研究了光学几何近似方法和多图统计方法等相位信息提取技术之后,提出了``统计--几何光学近似'相位信息提取的新方法, 并在北京BSRF形貌站上进行了实验验证. 实验表明,新方法能够大大提高光学几何近似求解的精确度和折射角图像的信噪比.     

X射线光栅相位成像的理论和方法

通过对X射线光栅相位衬度成像实验装置的理论分析,提出了光栅位移曲线的表达式,推导出了X射线光栅相位衬度成像方程.根据该成像方程,提出了基于光栅成像相位提取方法.这些理论结果将简化光栅相位衬度成像实验步骤,提高信息获取效率,并为X射线光栅相位衬度成像和计算机断层成像的结合,进一步提出光栅相位衬度CT的简化理论奠定基础. 关键词： X射线 相位衬度成像 光栅衍射 Talbot效应     

Waveguides Induced by Screening-Photovoltaic Solitons in Biased Photorefractive-Photovoltaic Crystals

We investigate theoretically waveguides induced by screening-photovoltaic solitons in biased photorefractive-photovoltaic crystals. We show that the number of guided modes in a waveguide induced by a bright screening photovoltaic soliton increases monotonically with the increasing intensity ratio of the soliton, which is the ratio between the peak intensity of the soliton and the dark irradiance. On the other hand, waveguides induced by dark screening-photovoltaic solitons are always single mode for all intensity ratios and the confined energy near the centre of a dark screening-photovoltaic soliton increases monotonically with the increasing intensity ratio. When the bulk photovoltaic effect is neglectable, these waveguides are those induced by screening solitons. When the external field is absent, these waveguides predict those induced by photovoltaic solitons.