Two-Pion Interferometry for the Granular Source in Heavy Ion Collisions at LHC Energies

The space-time characters of the pion-emitting sources produced in the heavy ion collisions at the Large Hadron Collider （LHC） energies are investigated in a granular source model of quark-gluon plasma droplets. The results of two-pion interferometry indicate that the longi- tudinal interferometry radius is sensitive to the initial breakup time of the system. For a larger breakup time the values of the longitudinal interferometry radius for the LHC source are larger than that of the source produced in the collisions at the Relativistic Heavy Ion Collider＇s （RHIC） top energy. However, the values of the longitudinal radius are smaller if the source fragments at a smaller breakup time with a higher initial temperature of the droplets. The values of the transverse interferometry radius in the ＂side＂ direction for the LHC sources are larger than those for the RHIC source. The imaging analyses for the characteristic quantities of the granular sources are consistent with the interferometry radii.

Two-pion interferometry in heavy ion collisionsat HIRFL-CSR energy

We examine the two-pion Hanbury-Brown-Twiss （HBT） interferometry for the particle-emitting source produced in heavy ion collisions at HIRFL-CSR energy. The source evolution is described by relativistic hydrodynamics with three kinds of equations of state for chemical equilibrium （CE）, chemical freeze-out （CFO）, and partial chemical equilibrium （PCE） models, respectively. We investigate the effects of particle decay, multiple scattering, and source collective expansion on the two-pion interferometry results. We find that the HBT radii of the evolution source for the CFO and PCE The HBT lifetime for the CFO model is smaller than those models are smaller than that for the CE model. for the PCE and CE models. The particle decay increases the HBT radius and lifetime while the source expansion decreases the HBT radius. The multiple scattering effect on the HBT results can be neglected based on our model calculations.

Inhomogeneous space-time structure and two-pion interferometry in NEXSPHERIO model

We examine the space-time structure of particle-emitting source and two-pion interferometry in a smoothed hydrodynamic model with fluctuating initial conditions. An equation of state with a crossover transition between quark-gluon plasma and hadronic gas is adopted in the description of the system evolution. We find that the fluctuating initial conditions lead to inhomogeneous particle-emitting sources. The interferometry results of Rs and Ro indicate that both the source size and the duration of pion emission decrease when the freeze-out temperature increases. The values of Ro/Rs obtained by our simulated two-pion interferometry are consistent with the previous results of smoothed particle hydrodynamics, and smaller than those calculated in usual hydrodynamic models.

Two-pion interferometry for viscous hydrodynamic sources

The space-time evolution of the （1＋1）-dimensional viscous hydrodynamics with an initial quarkgluon plasma （QGP） produced in ultrarelativistic heavy ion collisions is studied numerically. The particleemitting sources undergo a crossover transition from the QGP to hadronic gas. We take into account a usual shear viscosity for the strongly coupled QGP as well as the bulk viscosity which increases significantly in the crossover region. The two-pion Hanbury-Brown-Twiss （HBT） interferometry for the viscous hydrodynamic sources is performed. The HBT analyses indicate that the viscosity effect on the two-pion HBT results is small if only the shear viscosity is taken into consideration in the calculations. The bulk viscosity leads to a larger transverse freeze-out configuration of the pion-emitting sources, and thus increases the transverse HBT radii. The results of the longitudinal HBT radius for the source with Bjorken longitudinal scaling are consistent with the experimental data.

Nonlinear time-reversal interferometry with arbitrary quadratic collective-spin interaction

Atomic nonlinear interferometry has wide applications in quantum metrology and quantum information science.Here we propose a nonlinear time-reversal interferometry scheme with high robustness and metrological gain based on the spin squeezing generated by arbitrary quadratic collective-spin interaction,which could be described by the Lipkin–Meshkov–Glick(LMG)model.We optimize the squeezing process,encoding process,and anti-squeezing process,finding that the two particular cases of the LMG model,one-axis twisting and two-axis twisting outperform in robustness and precision,respectively.Moreover,we propose a Floquet driving method to realize equivalent time reverse in the atomic system,which leads to high performance in precision,robustness,and operability.Our study sets a benchmark for achieving high precision and high robustness in atomic nonlinear interferometry.

Study on the application of optical interferometry in the measurement of the coating thickness of color-coated plates

The principle and application of optical interferometry to measure the coating thickness of color-coated plates were introduced in this paper.Additionally,several factors affecting the test results,including coating refractive index,wavelength range,and film thickness range setting,were analyzed.Among these,the refractive index of the color coating,which cannot be measured directly,was identified as the key factor.A solution to this problem was proposed.Finally,the optical interference method and the current detection methods,including the micrometer method and the magnetic eddy current method,were analyzed and compared.The results show that optical interferometry has better repeatability and reproducibility than the current methods and show no significant difference from the current methods through statistical tests.Therefore,the method can be applied to the detection of the coating thickness of color-coated plates.

Relative timing jitter compression in a Fabry-Pérot cavity-assisted free-running dual-comb interferometry

Dual-comb interferometric systems with high time accuracy have been realized for various applications.The flourishing ultralow noise dual-comb system promotes the measurement and characterization of relative timing jitter,thus improving time accuracy.With optical solutions,introducing an optical reference enables 105 harmonics measurements,thereby breaking the limit set by electrical methods;nonlinear processes or spectral interference schemes were also employed to track the relative timing jitter.However,such approaches operating in the time domain either require additional continuous references or impose stringent requirements on the amount of timing jitter.We propose a scheme to correct the relative timing jitter of a free-running dual-comb interferometry assisted by a Fabry-Pérot(F-P)cavity in the frequency domain.With high wavelength thermal stability provided by the F-P cavity,the absolute wavelength deviation in the operating bandwidth is compressed to<0.4 pm,corresponding to a subpicosecond sensitivity of pulse-to-pulse relative timing jitter.Also,Allan deviation of 10^(-10) is obtained under multiple coherent averaging,which lays the foundation for mode-resolved molecular spectroscopic applications.The spectral absorption features of hydrogen cyanide gas molecules at ambient temperature were measured and matched to the HITRAN database.Our scheme promises to provide new ideas on sensitive measurements of relative timing jitter.

Joint interferometric imaging of walkaway VSP data

In this paper,we image the subsurface reflectors by interferometric imaging using primary and downgoing first-order free-surface related multiple reflections in walkaway VSP data.By analyzing the stack fold distribution,we find that primary-direct interferometric imaging has a smaller image range,but its stack fold is higher near the well while ghostdirect interferometric imaging is the opposite.We try to solve this problem by the joint interferometric imaging of walkaway VSP data,combining primary-direct interferometric imaging with ghost-direct interferometric imaging.In this way,we can effectively widen the imaging range,simultaneously increase the fold（especially near the well）,suppress spurious interference,and improve the image SNR,so that we can get a more credible image.Test results on synthetic walkaway VSP data and field data show that joint interferometric imaging is very effective.

Research on 3D marine electromagnetic interferometry with synthetic sources for suppressing the airwave interference

In order to suppress the airwave noise in marine controlled-source electromagnetic （CSEM） data, we propose a 3D deconvolution （3DD） interferometry method with a synthetic aperture source and obtain the relative anomaly coefficient （RAC） of the EM field reflection responses to show the degree for suppressing the airwave. We analyze the potential of the proposed method for suppressing the airwave, and compare the proposed method with traditional methods in their effectiveness. A method to select synthetic source length is derived and the effect of the water depth on RAC is examined via numerical simulations. The results suggest that 3DD interferometry method with a synthetic source can effectively suppress the airwave and enhance the potential of marine CSEM to hydrocarbon exploration.

端到端的神经网络相位解包裹方法

相位解包裹为重要的信号处理过程,其目的是将被包裹相位恢复到原始相位。文章探讨了基于U型神经网络结构(UNet)对测量区域的包裹相位进行相位展开的方法,该方法可以有效地处理包裹相位区域,能够从噪声包裹相位中直接估计平滑的展开相位。以圆域和花瓣状域的包裹相位数据为例来建立训练数据库,通过模拟数据验证该方法的解包裹性能。分析表明,在噪声情况下UNet方法的均方误差小于传统解包裹算法,通过实测数据验证了UNet方法的性能。

APPLICATION OF 2-D MOIRE INTERFEROMETRYOF STICKING FILM IN HUMAN TIBIA MEASUREMENT

This paper makes use of the method of testing and measuring the human body tibia by using2-D moire interferometry of sticking film. hased on the J'--y direction moire patterns recorded synchronously by 2-D optical path,the elastic constant,strain and displacement of the tibia are measured.Compared with the electric measuring method the error is samll and the sensitivity is high.

利用InSAR技术反演甘肃积石山M_(S)6.2地震同震破裂模型及形变时间序列

使用升降轨Sentinel-1A卫星数据,利用差分干涉技术获取甘肃积石山M_(S)6.2地震高精度同震形变场,并以此为约束反演同震破裂模型,然后采用SBAS-InSAR技术获取震中附近区域近6个月的累积形变时间序列。结果表明,本次地震地表形变以抬升为主,升降轨数据视线向最大同震形变量分别约为6.8 cm和7.3 cm,破裂主要集中在7~15 km深度范围内,最大滑动量约为0.55 m;震后2个月内,震中近场及西北侧的抬升形变呈扩大趋势。综合分析认为,此次积石山地震发震断层走向NW、倾向NE,隶属于拉脊山南缘断裂带东南侧的隐伏分支断层;震后的大面积突发形变可能与孔隙压力释放有关,地表稳定状态有待进一步观察。

Comparison of L-band and X-band differential interferometric synthetic aperture radar for mine subsidence monitoring in central Utah

Differential interferometric synthetic aperture radar(DIn SAR), a satellite-based remote sensing technique, has potential application for measuring mine subsidence on a regional scale with high spatial and temporal resolutions. However, the characteristics of synthetic aperture radar(SAR) data and the effectiveness of DIn SAR for subsidence monitoring depend on the radar band(wavelength). This study evaluates the effectiveness of DIn SAR for monitoring subsidence due to longwall mining in central Utah using L-band(24 cm wavelength) SAR data from the advanced land observing satellite(ALOS)and X-band(3 cm wavelength) SAR data from the Terra SAR-X mission. In the Wasatch Plateau region of central Utah, which is characterized by steep terrain and variable ground cover conditions, areas affected by longwall mine subsidence are identifiable using both L-band and X-band DIn SAR.Generally, using L-band data, subsidence magnitudes are measurable. Compared to X-band, L-band data are less affected by signal saturation due to large deformation gradients and by temporal decorrelation due to changes in the surface conditions over time. The L-band data tend to be stable over relatively long periods(months). Short wavelength X-band data are strongly affected by signal saturation and temporal decorrelation, but regions of subsidence are typically identifiable over short periods(days). Additionally,though subsidence magnitudes are difficult to precisely measure in the central Utah region using X-band data, they can often be reasonably estimated.

Orbit optimization for ASTROD-GW and its time delay interferometry with two arms using CGC ephemeris

Astrodynamical space test of relativity using optical devices optimized for gravitation wave detection （ASTROD- GW） is an optimization of ASTROD to focus on the goal of detection of gravitation waves. The detection sensitivity is shifted 52 times toward larger wavelength compared with that of laser interferometer space antenna （LISA）. The mission orbits of the three spacecrafts forming a nearly equilateral triangular array are chosen to be near the Sun–Earth Lagrange points L3, L4, and L5. The three spacecrafts range interferometrically with one another with an arm length of about 260 million kilometers. In order to attain the required sensitivity for ASTROD-GW, laser frequency noise must be suppressed to below the secondary noises such as the optical path noise, acceleration noise, etc. For suppressing laser frequency noise, we need to use time delay interferometry （TDI） to match the two different optical paths （times of travel）. Since planets and other solar-system bodies perturb the orbits of ASTROD-GW spacecraft and affect the TDI, we simulate the time delay numerically using CGC 2.7 （here, CGC stands for center for gravitation and cosmology） ephemeris framework. To conform to the ASTROD-GW planning, we work out a set of 20-year optimized mission orbits of ASTROD-GW spacecraft starting at June 21, 2028, and calculate the differences in optical path in the first and second generation TDIs separately for one-detector case. In our optimized mission orbits of 20 years, changes of arm lengths are less than 0.0003 AU; the relative Doppler velocities are all less than 3m/s. All the second generation TDI for one-detector case satisfies the ASTROD-GW requirement.

Measurement of Liquid Concentration Fields Near Interface with Cocurrent Gas-Liquid Flow Absorption Using Holographic Interferometry

Real-time laser holographic interferometry was applied to measure liquid concentrations of CO2 in the vicinity of gas-liquid free interface under the conditions of cocurrent gas-liquid flow for absorption of CO2 by ethanol. The influences of the Reynolds number on the measurable interface concentration and on the film thickness were discussed. The results show that CO2 concentration decreases exponentially along the mass transfer direction,and the concentration gradient increases as Reynolds number of either liquid or gas increases. CO2 concentrations fluctuate slightly along the direction of flow; on the whole, there is an increase in CO2 concentration. The investigation also demonstrated that film thickness decreases with the increase of Reynolds number of either of the two phases. Sherwood number representing the mass transfer coefficient was finally correlated as a function of the hydrodynamic parameters and the physical properties.

Orbit optimization and time delay interferometry for inclined ASTROD-GW formation with half-year precession-period

ASTROD-GW （ASTROD [astrodynamical space test of relativity using optical devices] optimized for gravitational wave detection） is a gravitational-wave mission with the aim of detecting gravitational waves from massive black holes, extreme mass ratio inspirais （EMRIs） and galactic compact binaries together with testing relativistic gravity and probing dark energy and cosmology. Mission orbits of the 3 spacecrafts forming a nearly equilateral triangular array are chosen to be near the Sun-Earth Lagrange points L3, L4, and L5. The 3 space, crafts range interferometrically with one another with arm length about 260 million kilometers. For 260 times longer arm length, the detection sensitivity of ASTROD- GW is 260 fold better than that of eLISA/NGO in the lower frequency region by assuming the same acceleration noise. Therefore, ASTROD-GW will be a better cosmological probe. In previous papers, we have worked out the time delay interferometry （TDI） for the ecliptic formation. To resolve the reflection ambiguity about the ecliptic plane in source position determination, we have changed the basic formation into slightly inclined formation with half-year precessionperiod. In this paper, we optimize a set of 10-year inclined ASTROD-GW mission orbits numerically using ephemeris framework starting at June 21, 2035, including cases of inclination angle with 0° （no inclination）, 0.5°, 1.0°, 1.5°, 2.0°, 2.5°, and 3.0°. We simulate the time delays of the first and second generation TDI configurations for the different inclinations, and compare/analyse the numerical results to attain the requisite sensitivity of ASTROD-GW by suppressing laser frequency noise below the secondary noises. To explicate our calculation process for different inclination cases, we take the 1.0° as an example to show the orbit optimization and TDI simulation.

Hole-drilling method using grating rosette and Moire interferometry

The hole-drilling method is one of the most wellknown methods for measuring residual stresses. To identify unknown plane stresses in a specimen, a circular hole is first drilled in the infinite plate under plane stress, then the strains resulting from the hole drilling is measured. The strains may be acquired from interpreting the Moire signature around the hole. In crossed grating Moire interferometry, the horizontal and vertical displacement fields （u and v） can be obtained to determinate two strain fields and one shearing strain field. In this paper, by means of Moire interferometry and three directions grating （grating rosette） developed by the authors, three displacement fields （u, v and s） are obtained to acquire three strain fields. As a practical application, the hole-drilling method is adopted to measure the relief strains for aluminum and fiber reinforced composite. It is a step by step method; in each step a single laminate or equivalent depth is drilled to find some relationships between the drilling depth and the residual strains relieved in the fiber reinforced composite materials.

Review of Electronic Speckle Pattern Interferometry(ESPI) for Three Dimensional Displacement Measurement

Three dimensional（3D） displacements, which can be translated further into 3D strain, are key parameters tor design, manufacturing and quality control. Using different optical setups, phase-shift methods, and algorithms, several different 3D electronic speckle pattern interferometry（ESPl） systems for displacement and strain measurements have been achieved and commercialized. This paper provides a review of the recent developments in ESPI systems for 3D displacement and strain measurement. After an overview of the fundamentals of ESP! theory, temporal phase-shift, and spatial phase-shift techniques, 3D deformation measurements by the temporal phase-shift ESPI system, which is suited well for static measurement, and by the spatial phase-shift ESPI system, which is particularly useful for dynamic measurement, are discussed. For each method, the basic theory, a brief derivation and different optical layouts are presented. The state of art application, potential and limitation of the ESPI systems are shown and demonstrated.

Monitoring elevation change of glaciers on Geladandong Mountain using Tan DEM-X SAR interferometry

Glaciers play an important role in the climate system. The elevation change of a glacier is an important parameter in studies of glacier dynamics. Only a few ground-based measurements of high mountain glaciers are available due to their remoteness, high elevation, and complex topography. The acquisition from the German Tan DEM-X(Terra SAR-X add-on for Digital Elevation Measurement) SAR imaging configuration provides a reliable data sources for studying the elevation change of glaciers. In this study, the bistatic Tan DEM-X data that cover the Geladandong Mountain on the Tibetan Plateau were processed with SAR interferometry technique and the elevation changes of the mountain's glaciers during 2000–2014 were obtained. The results indicated that although distinct positive and negative elevation changes were found for different glacier tongues, the mean elevation change was about-0.14±0.26 m a-1. Geoscience Laser Altimeter System(GLAS) data were obtained for comparison and verification. The investigation using GLAS data demonstrated the efficacy of the proposed method in determining glacier elevation change. Thus, the presented approach is appropriate for monitoring glacier elevation change and it constitutes a valuable tool for studies of glacier dynamics.

Precision measurement with atom interferometry

Development of atom interferometry and its application in precision measurement are reviewed in this paper. The principle, features and the implementation of atom interferometers are introduced, the recent progress of precision measurement with atom interferometry, including determination of gravitational constant and fine structure constant, measurement of gravity, gravity gradient and rotation, test of weak equivalence principle, proposal of gravitational wave detection, and measurement of quadratic Zeeman shift are reviewed in detail. Determination of gravitational redshift, new definition of kilogram, and measurement of weak force with atom interferometry are also briefly introduced.