Photons can hide where they have been

Recently,the nested Mach–Zehnder interferometer[Phys.Rev.Lett.111,240402(2013)]was modified by adding Dove prisms in a paper[Quantum Stud.:Math.Found.2,255(2015)],and an interesting result is that,after the Dove prisms were inserted,a signal at the first mirror of the nested interferometer was obtained.But,according to the former original paper,the photons have never been present near that mirror.In this work,we interpret this result naturally by resorting to the three-path interference method.Moreover,we find that even though the photons have been somewhere,they can hide the trace of being there.     

Spatially modulated polarimetry based on a vortex retarder and Fourier analysis

We report a spatially modulated polarimetry scheme by using a zero-order vortex half-wave retarder(ZVHR)and a spatial Fourier analysis method.A ZVHR is employed to analyze the input polarized light and convert it into a vectorial optical field,and an analyzer is set after the ZVHR to form an hourglass intensity pattern due to the spatial polarization modulation.Then,the input light’s Stokes parameters can be calculated by spatial Fourier analysis of the hourglass pattern with a single shot.The working principle of the polarimeter has been analyzed by the Stokes-Mueller formalism,and some quantitative measuring experiments of different polarization states have been demonstrated.The experimental results indicate that the proposed polarimeter is accurate,robust,and simple to use.     

Highly transparent ceramics for the spectral range from 1.0 to 60.0μm based on solid solutions of the system AgBr-AgI-TlI-TlBr

The article is devoted to the technology for obtaining optical ceramics of Ag Br-Tl I and Ag Br-Tl Br_0.46I_0.54 systems and manufacturing samples with different compositions.The new heterophase crystal ceramics are transparent without absorption windows in the spectral range from 1.0 to 60.0μm.In the ceramics’transparency spectra based on the Ag Br-Tl I and Ag Br-Tl Br_0.46I_0.54 systems fusibility diagrams,with an increase in the thallium halides mass fraction,as well as the replacement of the bromine ion with iodine,the maximum transparency shifts to a long infrared region.     

松木-聚氯乙烯复合材料催化热解特性的研究

通过热重法研究了松木与聚氯乙烯复合材料的催化热解特性,结果表明聚氯乙烯脱氯阶段与松木的纤维素、半纤维素热分解阶段温度区间重合,二者共热解时存在协同效应,并且HCl的释放对纤维素的脱水反应能够产生催化作用,HCl释放也对木质素的热分解及碳化反应有着明显的催化作用,导致二者共热解制备的碳化物产率提高,约为29.61%。并且利用元素分析仪、扫描电镜和能谱仪对成碳材料进行表征分析,结果表明成碳材料表面粗糙呈现多孔结构,其碳元素含量较高达到74.67%。     

Hierarchical structure observation and nanoindentation size effect characterization for a limnetic shell

In the present research, hierarchical structure observation and mechanical property characterization for a type of biomaterial are carried out. The investigated biomaterial is Hyriopsis cumingii, a typical limnetic shell, which consists of two different structural layers, a prismatic "pillar"structure and a nacreous "brick and mortar" structure. The prismatic layer looks like a "pillar forest" with variationsection pillars sized on the order of several tens of microns.The nacreous material looks like a "brick wall" with bricks sized on the order of several microns. Both pillars and bricks are composed of nanoparticles. The mechanical properties of the hierarchical biomaterial are measured by using the nanoindentation test. Hardness and modulus are measured for both the nacre layer and the prismatic layer, respectively.The nanoindentation size effects for the hierarchical structural materials are investigated experimentally. The results show that the prismatic nanostructured material has a higher stiffness and hardness than the nacre nanostructured material.In addition, the nanoindentation size effects for the hierarchical structural materials are described theoretically, by using the trans-scale mechanics theory considering both strain gradient effect and the surface/interface effect. The modeling results are consistent with experimental ones.     

单晶硅晶格间距的测量技术进展及应用

单晶硅晶格间距是许多重要物理常数测量的基础。本文介绍了硅晶格间距测量技术的发展历程,包括X射线干涉仪直接测量和晶格比较仪间接测量两种方法,以及影响测量结果不确定度的关键因素。得益于晶格间距测量的进展,在纳米尺度,硅晶格间距被国际计量局(BIPM)批准成为新的米定义复现形式。最后介绍了硅晶格在计量学中的应用,以及基于硅晶格实现纳米几何量测量的溯源体系的研究趋势。     

Infrasonic waves generated from the volcano eruption in Tonga

The Hunga-Tonga-Hunga-Ha’apai volcano in Tonga erupted violently on January 15, 2022. After 8 hours and 39 minutes, an infrasound array in Kunming at a distance of 10151 km away from the volcano recorded a sequence of strong infrasonic waves. The average period of the first four infrasonic waves is 443 s with propagation speed of 321 m/s. The azimuth angle of this event has been estimated by applying the progressive multi-channel correlation(PMCC) method to process the received signals. During c...     

紫外可见偏振成像光谱仪的光谱定标与匹配方法

紫外可见偏振成像光谱仪中沃拉斯顿棱镜的色散效应会导致探测器同一空间通道的中心坐标发生偏移，影响目标信号探测精度。根据偏振解调算法，利用沃拉斯顿棱镜出射的两正交分量调制光谱(S光和P光)实现偏振信息解调时，还需要完成光谱匹配。针对这一问题，提出了一种光谱定标与匹配方法。首先利用平行光源标定了仪器视场角与空间维像元的对应关系，提取出各空间通道对应的像元坐标集合并确定了视场定标方程；在同一空间通道内，通过低压汞灯标准光源对波长与像元的对应关系进行标定，得出光谱定标方程；利用视场定标和光谱定标结果完成正交分量光谱的匹配；最后利用太阳光谱中Fraunhofer线的特征波长对定标结果进行了检验。结果表明：紫外可见偏振成像光谱仪正交分量的光谱吸收峰位具有较好的一致性，定标值和标准值的偏差在0.1 nm以内，这验证了定标结果的准确性。     

惯性约束聚变实验中空间干涉检测与预警系统设计

针对惯性约束聚变实验中多诊断系统在有限空间同时作业引发碰撞风险的问题，设计了基于碰撞目标检测和空间距离测算方法的空间干涉检测与预警系统，分析了真空靶室特定环境下不同实现方法的适用条件和可行性。实验室条件下模拟验证结果表明，基于结构光深度图像获取方法可获得较好的碰撞距离测量精度，在靶室半径探测距离内空间测距误差不大于3cm，为靶室空间干涉检测与预警提供了一种可行的解决方案。