Film thickness measurement with white light fringes

A method is described of measuring the thickness of thin films by using white light fringes obtained in a double pass Michelson interferometer. The method is suitable for the determination of thickness ranging from 15 nm to 2500 nm.     

环状干涉条纹成像技术的实验研究

 从傅里叶分析的角度来讨论环状干涉条纹成像的处理过程，并报道二维连续散射目标的成像实验。激光干涉条纹成像是利用激光源在空域形成的干涉条纹同目标间的相对运动来提取目标的图像信息。对利用环状干涉条纹的激光干涉成像，其机理常用全息理论来解释。     

环状干涉条纹成像技术的实验研究

从傅里叶分析的角度来讨论环状干涉条纹成像的处理过程,并报道二维连续散射目标的成像实验。激光干涉条纹成像是利用激光源在空域形成的干涉条纹同目标间的相对运动来提取目标的图像信息。对利用环状干涉条纹的激光干涉成像,其机理常用全息理论来解释。     

点光源劈尖干涉的条纹分布特征

在有限远的点光源照射下,导出了劈尖干涉的明、暗纹条件,通过Matlab软件,用数值分析方法给出了劈尖表面条纹分布特征,讨论了光源距离对表面条纹分布的影响.     

Collider search of light dark matter model with dark sector decay

We explore the possibility that the dark matter relic density is not produced by a thermal mechanism directly, but by the decay of other heavier dark-sector particles which themselves can be produced by the thermal freeze-out mechanism. Using a concrete model with light dark matter from dark sector decay, we study the collider signature of the dark sector particles associated with Higgs production processes. We find that future lepton colliders could be a better place to probe the signature of this kind of light dark matter model than hadron colliders such as LHC. Also, we find that a Higgs factory with center-of-mass energy 250 GeV has a better potential to resolve the signature of this kind of light dark matter model than a Higgs factory with center-of-mass energy 350 GeV.     

Controlling the diffused nonlinear light generated in random materials

We describe a method for shaping the wavefront of the second-harmonic light generated in nonlinear materials with a disordered structure using a spatial light modulator on the fundamental beam. We show that, for the case of a transparent strontium-barium niobate crystal with a random distribution of antiparallel domains, the speckle generation can be concentrated into a single spot.     

偏心环状干涉条纹对成像的影响

讨论了由激光束生成的环状干涉条纹用于目标成像的原理和使用匹配滤波器的处理方法,推导得出相应的点扩展函数(PSF)。模拟计算了主旁瓣峰值比和偏心量与相位量的关系,分析了偏心量对成像质量的影响。结果表明,适当的偏心量有利于提高环状干涉条纹成像的分辨率,又不致于产生对点扩展函数有影响的旁瓣。     

偏心环状干涉条纹对成像的影响

 讨论了由激光束生成的环状干涉条纹用于目标成像的原理和使用匹配滤波器的处理方法，推导得出相应的点扩展函数(PSF)。模拟计算了主旁瓣峰值比和偏心量与相位量的关系，分析了偏心量对成像质量的影响。结果表明，适当的偏心量有利于提高环状干涉条纹成像的分辨率，又不致于产生对点扩展函数有影响的旁瓣。     

Sampling in holography of diffused objects or with diffused illumination

Differentiation between a diffused hologram and a specular hologram is determined by criteria of the wavelength and the relief of the object. In a hologram where the object beam is diffused (due to diffused object illumination, or because the object surface is reflecting diffusively), every part in the holographic plane contains information about the whole object, but from a different angle of view. In a specular hologram, the recording is somewhere between the image recording and the diffused holography. The latter part is contributed mainly by the edges of the object.This paper describes properties of sampled diffused holograms in terms of resolution,S/N (contrast), angle of view, power spectrum and the ability of determination of the object.Different sampling functions are compared and experimentally examined, while the total diffracting areas are preserved constant.It was found that when the sampling areas were distributed over the entire plane and the observation distance was preserved, the resolution, the angle of view and the ability of determination of the object was close to the unsampled hologram. At the same conditions theS/N and the power spectrum were reduced.It seems that these techniques of sampling may be applied for multiplexing, subtracting and correlating between two adjacent recordings.     

Formation of stacking faults and dislocations in phosphorus diffused silicon

Silicon samples diffused with phosphorus at 1050°C and subsequently annealed at 600°C or 700°C in vacuum or O₂ ambients were found to contain extrinsic stacking faults or misfit dislocations. We propose that silicon interstitials are generated to form the extended defects to relieve strain.     

Dynamics of dark energy models and centre manifolds

We analyse dark energy models where self-interacting three-forms or phantom fields drive the accelerated expansion of the Universe. The dynamics of such models is often studied by rewriting the cosmological field equations in the form of a system of autonomous differential equations, or simply a dynamical system. Properties of these systems are usually studied via linear stability theory. In situations where this method fails, for instance due to the presence of zero eigenvalues in the Jacobian, centre manifold theory can be applied. We present a concise introduction and show explicitly how to use this theory in two concrete examples.     

藏在暗原子云中的光

集体效应减缓了致密原子云中受激原子的衰减,研究者可以制备并操纵这一亚辐射态。     

Observation of resonant behavior in the energy velocity of diffused light

In this Letter we demonstrate Mie resonances mediated transport of light in randomly arranged, monodisperse dielectric spheres packed at high filling fractions. By means of both static and dynamic optical experiments we show resonant behavior in the key transport parameters and, in particular, we find that the energy transport velocity, which is lower than the group velocity, also displays a resonant behavior.     

两圆偏振光以及线偏振光和圆偏振光干涉图样的衬比度

考察了两束圆偏振光之间以及线偏振光与圆偏振光之间干涉所形成图样的衬比度,并与两束线偏振光之间干涉图样的衬比度进行了比较．指出在非共面多光束干涉中有可能利用圆偏振光以改善干涉图样的整体衬比度,并简要介绍了它在光子晶体制备中的应用．     

SuperWIMP dark matter scenario in light of WMAP

The heavy gravitino in the minimal supergravity (mSUGRA) models is likely to be the lightest supersymmetric particle (LSP). Produced from the late decays of the metastable weakly interacting massive particles (WIMPs) such as the lightest neutralinos, the stable gravitinos can be plausible candidates for the cold dark matter in the universe. Such gravitino dark matter can naturally evade the current detection experiments due to its superweak couplings. However, this scenario must be subjected to the constraints from the big bang nucleosynthesis (BBN) predictions for light element abundances as well as the Wilkinson microwave anisotropy probe (WMAP) data for the relic density. Assuming the popular case in which the lightest neutralino is the next-to-lightest supersymmetric particle (NLSP), we find that requiring BBN predictions for light element abundances to agree with the WMAP data can impose upper and lower mass bounds on both the gravitino LSP and the neutralino NLSP. A scan over the mSUGRA parameter space, subjected to the BBN constraints, the WMAP data and the bounds, shows that the low ( ) region as well as the region accessible at the CERN Large Hadron Collider (LHC) will be severely constrained. Such stringent constraints on the parameter space might be instructive for testing this scenario in future collider experiments.Received: 17 August 2004, Revised: 9 September 2004, Published online: 3 November 2004