Statistics of a random plus constant vector with application to acoustic and electromagnetic-wave scattering

A two-dimensional random-walk problem is investigated, where a vector fixed in amplitude (magnitude) is added to one that is random in phase (direction angle). This problem can arise from a study of the effect of multipath interference from an acoustic or electromagnetic-wave source, where an arrival of constant amplitude is combined with an incoherent background of randomly scattered components of the incident field. The source is considered to have harmonic time dependence. This study follows from an earlier paper, in which the required properties of the incoherent background were derived. In the present study, the joint distribution of the resultant amplitude and of the phase angle between the resultant and the fixed arrival is determined. Further, expressions are developed for the first and second moments of the resultant phase, amplitude, decibel-amplitude, and intensity. Many properties of these moments are described.This work was supported in part by Acoustic Programs, US Office of Naval Research and in part by the Electric Boat Division of General Dynamics.     

INTERFERENCE EFFECTS IN DIFFERENT FIFTH-ORDER POLARIZATIONS WITH BROADBAND NOISY LIGHT

Based on the second-order coherence function, we have studied a phase-conjugate ultrafast modulation spectroscopy due to the interference between the fifth- and fifth-order optical polarizations in cascade three-level Doppler-broadened system. It is found that the temporal behaviour of the beat signal depends on the stochastic properties of the lasers and the transverse relaxation rate of the transition. The beat signal depends on the second-order coherence function, which is determined by the laser line shape. Since different stochastic models of the laser field only affect higher than second-order coherence functions, they have little influence on the general temporal modulation behaviour of the beat signal. The cases that pump beams have either narrow band or broadband linewidth are considered and it has been found that for both cases the overall accuracy for the energy-level difference measurement is determined by the homogeneous linewidths of the optical transitions. Finally, the spatial modulation behaviour of the beat signal has also been discussed.     

High Precision Testing Method for Fabry-Perot Etalon

We present a new method for precise measurement of parallelism and relative flatness of a Fabry-Perot etalon. This method is based on the analysis of multiple-beam transmission interference fringe pattern. Two-dimensional defect information is obtained by using small apertures placed over the entire area of the etalon. Experimental results for precise testing of an etalon with repeatability better than #x03BB;/2300 to 3#x03C3; are presented.     

多重光反馈的激光自混合干涉

对多重光反馈的激光自混合干涉现象进行了实验观察,并基于含复合腔激光器结构,建立了系统模型,模型的仿真结果与实验结果相吻合,研究结果有助于设计高分辨的位移测量系统。     

Interference due to coherence swapping

We propose a method called ‘coherence swapping’ which enables us to create superposition of a particle in two distinct paths, which is fed with initially incoherent, independent radiation. This phenomenon is also present for the charged particles, and can be used to swap the effect of flux line due to the Aharonov-Bohm effect. We propose an optical version of experimental set-up to test the coherence swapping. The phenomenon, which is simpler than entanglement swapping or teleportation, raises some fundamental questions about the true nature of wave-particle duality, and also opens up the possibility of studying the quantum erasure from a new angle.     

偏振干涉成像光谱仪通量的分析与计算

论述了自行研制的偏振干涉成像光谱仪的剪切分光机理和干涉成像原理。对偏振干涉成像光谱仪的通量进行了分析和计算,推导了偏振器偏振化方向偏离理想方向时通量随偏角的变化关系。给出了最大调制度情形下的通量数值。这种偏振干涉成像光谱仪结构简单,无运动部件,能量通过率高,充分显示了超小,稳态,、大视场高通量,高调制度的优点,更加适合于航空航天遥感,野外环境操作和微弱信号探测。     

Interferometric determination of refraction and dispersion of a birefringent material: non-numerical procedure

Fringes of equal chromatic order are produced in air, immersion liquid and mica sample interferometric gaps. The three gaps are of the same thickness and simultaneously enclosed in a wedge interferometer. A single-shot interferogram contains fringes in the three gaps is sufficient to deduce the needed experimental data. A non-numerical procedure is used for determining the refractive indices of the immersion liquid and mica sample across the visible spectrum. There is no need for any numerical fitting stage nor for the application of any theoretical model concerning the dispersion behavior of the sample under test. A modified two-term Sellmeier dispersion formula has been used for fitting the experimental data and deducing the needed dispersion parameters.     

Atomic Interference Method for Direct Measurement of the Wigner Function of a Cavity Field

We propose a scheme for the reconstruction of a cavity field state.In the scheme the cavity field is first displaced by a microwave source,and then is placed in front of one slit of the two-slit apparatus.Ground state stoms pass through the apparatus,hitting upon the screen far away from the two-slit apparatus.The atom-field interaction is dispersive.The contrast of interference fringes is directly related to the Wigner function for the field state.The scheme can be easily generalized to measure the Wigner function of an entangled state of two spatially separated single-mode cavities.     

PDA－ICP－AES中光谱干扰校正的卡尔曼滤波法研究

本实验采用光电二极管阵列（ＰＤＡ）检测器消除波长定位误差、并藉平滑处理原始光谱图以减轻随机噪声影响，研究了卡尔曼滤波法在ＰＤＡ－ＩＣＰ－ＡＥＳ中光谱干扰校正方面的应用，探讨了影响滤波结果准确性的若干因素。藉此法分析了一些合成试样，回收率一般为９０％～１１０％。     

Three types of banded structures in highly birefringent poly(trimethylene terephthalate) spherulites

Poly(trimethylene terephthalate) (PTT), a highly birefringent aromatic polyester, has been utilized to understand the mechanisms of crystal assembly into diversified types of banded spherulites. PTT exhibits three main types of banded spherulites (i.e., concentric, single‐spiral, and double‐spiral) co‐existing in sample films melt‐crystallized at 165 °C, regardless of sample thickness. The three types differ in their banding structures, interference color distributions, and nuclei geometries (S‐shape, Z‐shape, or dot‐shape). Core diameter, band spacing ratio, and height difference (Δz) around the core are the three key parameters of different banding patterns in PTT spherulites. Formation mechanism for three types of banded spherulites has been interpreted, and found to be highly correlated with the initial geometry shapes of their nuclei. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1207–1216