基于系数搜索的振动补偿方法

绝对重力仪普遍采用激光干涉式或原子干涉式的测量原理来测量重力加速度的绝对值,在地球物理等领域有着广泛的应用.振动补偿是一种有效减小地面振动对绝对重力仪测量精度的影响的方法,尤其适用于复杂振动环境.本文介绍了一种基于传递函数简化模型的、用于实时修正原子干涉式绝对重力仪干涉条纹的振动补偿方法,给出了该方法的工作原理及搜索模型系数的具体算法流程,然后利用仿真运算验证算法的有效性,最后利用已有的原子干涉式绝对重力仪对算法效果进行了实验评估.结果表明,使用该振动补偿算法对原子重力仪的干涉条纹进行修正,最大可将干涉条纹的余弦拟合残差的标准差衰减58%.该振动补偿算法具有较强的自适应性,有望提升原子干涉式绝对重力仪在不同测量环境尤其是复杂振动环境中的测量精度.     

FLaser frequency stabilization and shifting by using modulation transfer spectroscopy

The stabilizing and shifting of laser frequency are very important for the interaction between the laser and atoms. The modulation transfer spectroscopy for the 87Rb atom with D2 line transition F = 2 →F＇ = 3 is used for stabilizing and shifting the frequency of the external cavity grating feedback diode laser. The resonant phase modulator with electro-optical effect is used to generate frequency sideband to lock the laser frequency. In the locking scheme, circularly polarized pump- and probe-beams are used. By optimizing the temperature of the vapor, the pump- and probe-beam intensity, the laser linewidth of 280 kHz is obtained. Furthermore, the magnetic field generated by a solenoid is added into the system. Therefore the system can achieve the frequency locking at any point in a range of hundreds of megahertz frequency shifting with very low power loss.     

Laser frequency stabilization and shifting by using modulation transfer spectroscopy

The stabilizing and shifting of laser frequency are very important for the interaction between the laser and atoms. The modulation transfer spectroscopy for the87 Rb atom with D2 line transition F = 2 → F = 3 is used for stabilizing and shifting the frequency of the external cavity grating feedback diode laser. The resonant phase modulator with electro–optical effect is used to generate frequency sideband to lock the laser frequency. In the locking scheme, circularly polarized pump- and probe-beams are used. By optimizing the temperature of the vapor, the pump- and probe-beam intensity, the laser linewidth of 280 kHz is obtained. Furthermore, the magnetic field generated by a solenoid is added into the system. Therefore the system can achieve the frequency locking at any point in a range of hundreds of megahertz frequency shifting with very low power loss.     

基于稀土上转换纳米粒子制作指示牌标识的研究

采用热解法制备NaYF4∶ Yb,Er纳米粒子,并通过TEM和XRD对纳米粒子的形貌和结构进行表征,结果表明制备的NaYF4:Yb,Er是β相纳米粒子,形态均一,尺寸约24 nm.并对Er3+典型的绿色上转换荧光的产生机制和荧光光谱进行了研究.进一步搭建指示牌标识成像系统,基于制备的NaYF4∶Yb,Er纳米粒子作为荧光标记材料,利用Er3+的2H11/2/4S3/2-4I15/2跃迁产生绿色上转换荧光对指示牌标识进行成像,得到了高对比度的荧光成像.     

用于绝对重力仪的落体旋转评估方法

介绍了一种自主搭建的测量落体在自由下落过程中旋转角速度的装置,评估了不同落体旋转角速度引入的旋转误差对重力测量的影响。针对具有旋转初速度的落体在真空腔内自由下落的运动模型,该装置采用光杠杆原理,将高精度位置传感器(PSD)作为光跟踪设备,研究并推导出落体由旋转所导致的反射光位移与下落时间的关系。然后,对PSD采集记录的时间位移曲线进行拟合,求解落体单次下落的旋转角速度值。在调整真空腔垂直度后,最大旋转角速度值可减小为16.88 mrad/s,引入的重力测值不确定度为0.57μGal,即该状态下落体的释放更加平稳。实验表明,该装置不仅可以进一步提升绝对重力仪中落体传动机构的装调精度,还可以对光学干涉绝对重力仪工作过程中的落体姿态进行监测,进一步降低落体旋转所引入的测量不确定度。     

Investigation of the thermal adaptability for a mobile cold atom gravimeter

The cold atom gravimeter offers the prospect of a new generation of inertial sensors for field applications. We accomplish a mobile atom gravimeter. With the compact and stable system, a sensitivity of 1.4×10~(-7)g·Hz~(-1/2)is achieved.Moreover, a continuous gravity monitoring of 80 h is carried out. However, the harsh outdoor environment is a big challenge for the atom gravimeter when it is for field applications. In this paper, we present the preliminary investigation of the thermal adaptability for our mobile cold atom gravimeter. Here, we focus on the influence of the air temperature on the performance of the atom gravimeter. The responses to different factors(such as laser power, fiber coupling efficiency,etc.) are evaluated when there is a great temperature shift of 10℃. The result is that the performances of all the factors deteriorate to different extent, nevertheless, they can easily recover as the temperature comes back. Finally, we conclude that the variation of air temperature induces the increase of noise and the system error of the atom gravimeter as well, while the process is reversible with the recovery of the temperature.     

尺寸对NaYbF4纳米晶活性氧产生速率的影响

本文采用热分解法制备了NaYbF4纳米晶,并通过控制反应时间调节纳米晶尺寸来增加其比表面积,进而提高活性氧产率.通过TEM图像对NaYbF4纳米晶的尺寸进行表征.利用化学探针法检验NaYbF4纳米晶分散液中活性氧的产生,并计算了活性氧产生速率.结果表明纳米晶尺寸在影响Yb3+与O2的能量传递过程中占主导因素.同时,当生长时间较短时,晶格缺陷较多,无辐射弛豫过程增加,也影响活性氧产生速率.尺寸约8 nm时,NaYbF4纳米晶活性氧产生速率最大.     

Participation in the absolute gravity comparison with a compact cold atom gravimeter

The first Asia-Pacific Comparison of Absolute Gravimeters(APMP.M.G-K1) was organized by the National Institute of Metrology(NIM) of China from December 21, 2015 to March 25, 2016 in Changping, Beijing. Our compact cold atom gravimeter(CCAG) was transported from Hangzhou to Beijing with a long distance of about1200 km to participate in this comparison. The CCAG is the only one, to the best of our knowledge, that is based on the principle of atom interferometry among all the instruments. Absolute gravity in the indicated three test sites has been measured as requested by the organizer. The sensitivity of our CCAG is estimated to be90 μGal∕Hz p, even when the measurements are carried out without any vibration isolation. Besides, the accuracy of this gravimeter has been evaluated to be about 19 μGal by considering the significant system errors.Our results show a good agreement with the given reference value.     

Detecting the vector of nanoscale light field with atomic defect

Modulation of a vector light field has played an important role in the research of nanophotonics. However, it is still a great challenge to accurately measure the three-dimensional vector distribution at nanoscale. Here, based on the interaction between the light field and atomic-sized nitrogen-vacancy(NV) color center in diamonds, we demonstrate an efficient method for vectorial mapping of the light-field distribution at nanoscale. Single NV centers with different but well-defined symmetry axes...     

原子能级粒子数热布局虚拟仿真实验的设计开发与教学实践

本虚拟仿真实验探究稀土离子热耦合能级粒子数随温度的变化规律。使学生掌握温度对原子能级粒子数的影响，并建立温度与荧光强度、荧光强度比之间的关系，深入探究温度对荧光强度和荧光强度比影响的区别和联系，加强对此部分理论知识的理解。进一步将理论知识进行实际应用，利用荧光强度比测量温度。通过本实验的学习，使学生对原子能级性质的理解更加深刻、掌握正确的荧光测试系统搭建过程，光路调节方法以及光谱数据的计算分析方法。激发了学生的学习兴趣，夯实了理论基础，并能学以致用，使学生对知识理解透彻，获得事半功倍的教学效果，仿真实验成绩优秀率达81%。