共查询到20条相似文献,搜索用时 546 毫秒
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Due to the fact that traditional ray field tracking approaches require a large number of geometrical optical(GO) ray tubes,they are very inefficient in many practical applications.An improved ray model scheme for a complex source beam(CSB) tracking technique is proposed in this paper.The source field can be expressed by a superposition of CSBs,then every CSB basis function has a Gaussian-type amplitude distribution and is suitable for replacing a GO ray tube in the ray tracing approach.The complex phase matching technique is adopted to find the reflected beam in the reflection point where local approximation is used to represent the curved surface in its neighborhood.A new solution to multiple reflections using the conventional right-handed reflected system is used to track the field easily.Numerical results show the accuracy of the proposed method. 相似文献
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Generation of a radially polarized laser beam by use of the birefringence of a c-cut Nd:YVO4 crystal 总被引:1,自引:0,他引:1
We demonstrated the generation of a radially polarized laser beam from an extremely simple laser resonator including a c-cut Nd:YVO4 crystal as a laser medium. The oscillation in the radial polarization was based on the optical path difference between an extraordinary ray and an ordinary ray induced by the birefringence of the crystal. By simply adjusting the distance between two cavity mirrors, only the extraordinary ray became stable for the oscillation, resulting in the generation of a radially polarized beam. The beam was very stable even at low power output and is expected to be a promising radially polarized laser source because of its excellent simplicity. 相似文献
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The use of a vertical radiating antenna array for generation of a wave beam propagating in an underwater sound channel along
the reference ray trajectory is discussed. The method for selecting the starting field in the antenna aperture for maximum
compression of a beam in the specified vicinity of the reference ray is proposed. The estimates showing up to what distances
a beam can propagate while remaining narrow as compared to the range of depths between the rotation horizons have been obtained.
The problem concerning the distances from the antenna array at which a beam can still be effectively focused in the vicinity
of the selected reference ray point is investigated. 相似文献
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The geometrical-acoustics approach is used to calculate the vertical structure of the sound field in an oceanic waveguide. The profile of the sound speed is specified to be canonical and range-independent along a 1000-km propagation path. A monochromatic sound source lies on the waveguide axis. It is shown that, at long distances from the source, the sound field formed by the water-path rays is mainly concentrated in the caustics, the number of which is determined by the number of the overlapping ray cycles at a given distance. A method for estimating the amplitude of the sound field produced by individual rays is proposed. The amplitudes obtained are used to calculate the total sound field along the vertical. A possible cause of the chaotic distribution of ray coordinates is considered. This cause may consist in the arbitrary choice of the number of rays and their departure angles without taking into account the discrete character of one of the variables. This mechanism of ray chaos formation furnishes an explanation for the fact that the chaos obtained in calculations is mainly associated with the flat rays. 相似文献
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S. Y. Lee I. H. Cho J. M. Kim H. C. Kang D. Y. Noh 《Journal of synchrotron radiation》2011,18(2):143-147
Focused hard X‐ray microbeams for use in X‐ray nanolithography have been investigated. A 7.5 keV X‐ray beam generated at an undulator was focused to about 3 µm using a Fresnel zone plate fabricated on silicon. The focused X‐ray beam retains a high degree of collimation owing to the long focal length of the zone plate, which greatly facilitates hard X‐ray nanoscale lithography. The focused X‐ray microbeam was successfully utilized to fabricate patterns with features as small as 100 nm on a photoresist. 相似文献
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同步辐射X光束空间相干性的物理分析 总被引:2,自引:2,他引:0
从量子力学的不确定原理出发,推导出光源相干性和光束相干性的关系,并应用所得的结论南步辐射X光束的空间相干性进行物理分析,讨论了X光相干我学实验对X光束的一些要求。 相似文献
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Consistent with earlier work by Kravtsov and Orlov, a simple general expression for the width of a Fresnel zone deltar(F) in a smooth inhomogeneous environment is derived; this is the diffractive contribution to the width of a ray. In a stratified environment at long range, the general Fresnel zone width expression is shown to reduce approximately to one that is proportional to [equation in text] where alpha is the ray stability parameter, sigma is the acoustic frequency, r is the range from the source to the field point of interest, and R is the source to receiver range. In a stratified environment on which a weak small-scale perturbation is superimposed, deterministic rays in the background environment that connect fixed end points break up into bundles of micromultipaths at moderate to long range and a second, scattering-induced, contribution deltar(s) to the width of a ray must be considered. It is shown that deltar(s) is proportional to /alpha/r(R-r) and argued that in a micromultipathing environment the total effective width of a background ray is deltar(tot)= [equation in text] . Theoretical predictions are shown to agree well with travel-time sensitivity kernel calculations. 相似文献
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M. A. Krasnogolovets 《Technical Physics》1999,44(4):390-393
The interaction of intense electron beams with plasmas in a nonuniform magnetic field is studied for the purpose of obtaining
a magnetoactive plasma ion source. The resulting experimental data are used to trace the dynamics of the changes in the basic
parameters of the source, both during the stage where it interacts with the beam and in the cooling stage. It is found that
the charged particles are contained for a long time and that the efficiency of energy transfer from the beam to the source
is high. This source is intended to be used for shaping and accelerating multiampere ion beams.
Zh. Tekh. Fiz. 69, 44–47 (April 1999) 相似文献
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Based on the ray acoustics approach, the trapping effects on a microsphere by an ideally spherically-focused ultrasound are discussed. The acoustical radiation force from a focused ultrasound beam on a spherical particle in a three-dimensional sound field is calculated considering the effect of the attenuation of the ultrasound beam both inside the particle and in the surrounding medium. The results show that as long as the particle is in the range of the ultrasound beam and as long as the appropriate parameters of the transducer are selected, the particle will be captured in the vicinity of the focus of the ultrasound beam. Also, the particle radius and different parameters of the transducer are analyzed for their affect on the radiation force. 相似文献
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A dedicated small‐angle X‐ray scattering beamline with a superconducting wiggler source at the NSRRC
Din‐Goa Liu Chien‐Hung Chang Chin‐Yen Liu Shih‐Hung Chang Jwei‐Ming Juang Yen‐Fang Song Kuan‐Li Yu Kuei‐Fen Liao Ching‐Shiang Hwang Hok‐Sum Fung Ping‐Chung Tseng Chi‐Yi Huang Liang‐Jen Huang Shih‐Chun Chung Mau‐Tsu Tang King‐Long Tsang Yu‐Shan Huang Chien‐Kuang Kuan Yi‐Chih Liu Keng S. Liang U‐Ser Jeng 《Journal of synchrotron radiation》2009,16(1):97-104
At the National Synchrotron Radiation Research Center (NSRRC), which operates a 1.5 GeV storage ring, a dedicated small‐angle X‐ray scattering (SAXS) beamline has been installed with an in‐achromat superconducting wiggler insertion device of peak magnetic field 3.1 T. The vertical beam divergence from the X‐ray source is reduced significantly by a collimating mirror. Subsequently the beam is selectively monochromated by a double Si(111) crystal monochromator with high energy resolution (ΔE/E? 2 × 10?4) in the energy range 5–23 keV, or by a double Mo/B4C multilayer monochromator for 10–30 times higher flux (~1011 photons s?1) in the 6–15 keV range. These two monochromators are incorporated into one rotating cradle for fast exchange. The monochromated beam is focused by a toroidal mirror with 1:1 focusing for a small beam divergence and a beam size of ~0.9 mm × 0.3 mm (horizontal × vertical) at the focus point located 26.5 m from the radiation source. A plane mirror installed after the toroidal mirror is selectively used to deflect the beam downwards for grazing‐incidence SAXS (GISAXS) from liquid surfaces. Two online beam‐position monitors separated by 8 m provide an efficient feedback control for an overall beam‐position stability in the 10 µm range. The beam features measured, including the flux density, energy resolution, size and divergence, are consistent with those calculated using the ray‐tracing program SHADOW. With the deflectable beam of relatively high energy resolution and high flux, the new beamline meets the requirements for a wide range of SAXS applications, including anomalous SAXS for multiphase nanoparticles (e.g. semiconductor core‐shell quantum dots) and GISAXS from liquid surfaces. 相似文献
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匹配场定位作为一种水声被动定位方法,其拷贝场计算方法的精度和速度对定位效果和定位效率有着直接的影响。尤其在深海,目前浅海中常用的拷贝场计算方法如简正波法、抛物方程近似等在深海中往往存在计算效率不够、内存需求大、难以满足实际应用的需求。高斯射线束方法具有计算速度快,物理意义清晰,易于并行化处理等优点,非常适合于深海近程声场计算。通过数值仿真算例和海上实验数据的处理验证了高斯射线束方法用于拷贝场计算的有效性。仿真和实验数据处理结果表明,采用高斯射线束方法计算拷贝场在深海匹配场定位中有很好的定位效果. 相似文献
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A SPLEEM (spin polarized low energy electron microscope) has been designed with a numerical simulation of electrostatic and magnetic field distributions and electron ray trajectories. Highly (more than 90%) spin polarized electron source has been used. A Wien type spin manipulator and a magnetic lens type spin rotator are used to align spin direction. A magnetic field free objective lens is designed to observe magnetic domain structure of magnetic materials. High or low magnification mode can be selected by using a combined electrostatic and magnetic objective lens for a high spatial resolution and a wide imaging area observation. An electrostatic mirror aberration corrector is installed after the image forming objective lens. A double deflection 45° beam separator is used to bend the direction of electrons from the source to the objective lens and from the objective lens to the mirror aberration corrector. 相似文献
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The possibility of using a vertical array for the generation of a narrow wave beam that propagates in the underwater sound
channel along a given reference ray is discussed. The variational problem of choosing the initial field at the array aperture
to provide the minimal possible average beam width along the propagation path of a fixed length is solved. 相似文献