利用导航数据的光线束法区域网平差的质量分析

精度和可靠性是任何一个大地测量和摄影测量平差系统质量分析的两个基本要素。本文对利用导航数据的光线束法区域网平差的精度和可靠性进行了模拟研究。试验研究针对不同精度等级的导航数据进行，利用了新近研制的联合平差程序系统WUCAPS（为武汉测绘科技大学联合平差程序系统的英文缩写）。得到的结论对利用导航数据——如全球定位系统GPS数据和惯性导航系统INS数据——进行空中三角测量具有重要意义。

常规摄片机X光线束的准直

要想得到较为满意的X光平片,除了机器硬件质量档次外,X线束的准直也是十分重要的,尤其是新安装X线机和已使用过一段时间后,机械磨损精度巳降低等情况下的机器,一定要对摄影装置进行精确的校准。否则,即使有高档的机器,好的投照技术,准直不好,也拍不出好的X光平片。下面以菲利浦D93床多功能X光机为例,总结一下各环节的校准方法。 进行X摄影机校准和调整时。

光CT的扇束投影重排方法及投影几何分析

在工业过程监控中,由于被测物理过程的发生时间短,因此光CT装置将不可能象医学CT那样有充足的时间进行“静态”成像,而是必须进行实时性较高的“动态”成像(或称为流动成像).其制约是光线扫描的投影视角和投影数量都不可能太多.根据这一情况,在医学CT中常用的一些图像重建算法如反投影法、滤波反投影法和投影重排方法都必须加以改进才能引用.为此,本文研究扇束投影重排方法在光学流动成像中的应用可行性,分析其计算方法和步骤,并确定光线扇束结构中的光源个数、扇形张角和探测器个数之间的约束关系,同时也分析了内插精度对图像质量的影响.在数值模拟实验中,将投影重排方法与反投影法的重建图象进行了比较,进一步评判本文方法的图象质量和成像实时性等方面的性能.

Waveguide Prism Based on Porous Silicon

The fabrication of the oxidized porous silicon waveguide prism is reported by selectively electrochemical anodisation process. The direction changes of light beams in TE and TM polarization out of this waveguide prism were respectively measured,and the experimental results were analyzed.

Practical realization of dual S arm antenna for beam steering applications

A dual S shaped micro strip antenna with a realistic feed is proposed for generation of tilted beam radiation pattern pertaining for beam steering applications. To achieve this, four feeding points are located at a distance of 5.6 mm from the antenna centre. These feeding points when excited one by one generate four tilted beams in four different space quadrants, thus yielding a beam steerable antenna, Importantly, since the proposed antenna is symmetrical in the structure, all the four tilted beams have the same radiation pattern characteristics. A further enhancement of the antenna bandwidth is also achieved using 100-μn capacitive coupling between the feed and the antenna strip.

A Beam Stabilization Algorithm Based on Nonlinear Observer for Low Cost Satcom-on-the-Move

A beam stabilization algorithm was proposed for low cost satcom-on-the-move （SOTM） to stabilize the vehicle-mounted antenna beam. The proposed algorithm utilizes the nonlinear observel to estimate the vehicle＇s attitude information based on inertial measurement unit. Then the estimated angles and angular velocities are used to stabilize the antenna beam. Experiment results show tha｜ the proposed algorithm can stabilize the antenna beam when the tracking information is available, indicating that it is competent to the SOTM system.

Elliptic Gaussian Optical Beam in Nonlinear Conical Graded-index Rod Lens

The propagation and transformation of an elliptic Gaussian optical beam(EGB) passing through a Kerr-law nonlinear conical graded-index rod lens are presented.In the rod lens, the EGB is treated as two dependent optical beams.The dimensionless beam-width parameters and the inverses of the curvature radii for the wavefront of the two beams are given semi-analytically,and the transformations of the EGB with the rod lens are derived by use of the ABCD law of Gaussian optical beam.

Er^(3+)-Yb^(3+) Co-Doped Fiber Ring and Line Laser

Er3+-Yb3+ co-doped fiber of 2 m long is used as the laser gain medium. Two fiber lasers with different structures have been set up, one is the line cavity fiber laser with the dielectric mirror being replaced by an all-fiber reflecting mirror,the other is the ring cavity all-fiber laser. Both set-ups have achieved lasing operation at the wavelength of 1.53 μm. Pumped by the 1 064 nm light from all-solid-state Nd ∶YAG laser, the two fiber lasers at 1 530 nm are operational. Their output powers are 7.8 mW and 2 mW with 130 mW and 160 mW pump powers.

Beam shaping with limited amplitude weight values for satellite active phased array antenna

To gain the tradeoff between lower sidelobe and higher power amplifiers efficiency,a transmitting beam shaping scheme with limited amplitude weight values for satellite active phased array antenna is presented. The scheme is implemented by a dual coding genetic algorithm(GA). Phase and amplitude of array weight vectors for beam shaping are encoded by real coding and finite length binary coding,respectively,which,maintaining accuracy of results,reduces the amplitude dynamic range and improves the efficiency of power amplifiers. The presented algorithm,compared with complex-coded GA,increases the convergence rate due to the search space's decrease. In order to overcome the prematurity and obtain better global optimization or quasi-global optimization,a new dual coding GA based on "species diversity retention" strategy and adaptive crossover and mutation probability are presented.

Generation of Four-Photon Cluster State with Coherent Light via Cross-Kerr Nonlinearity

We propose two schemes for preparing four-photon cluster state through cross-Kerr nonlinearity. Two coherent fields interact when they enter a nonlinear Kerr medium. If the interaction time is chosen appropriately in each Kerr medium, four-photon cluster state can be generated based on the results of two homodyne detectors in the first scheme. These schemes only use Kerr medium and homodyne measurements on coherent light fields, which can be effciently made in quantum optical laboratories. In addition, weak cross-Kerr nonlinearity is sufficient. All of the properties make these schemes feasible in experiments.

Simulation of Influence of Partially Coherent Gaussian Laser Beam on Gradient Force Acting on Dielectric Nanoparticle inside Random Medium

The partially coherent beams propagating through random media have been used in the past to enhance effect of nonlinear optical interaction. Moreover, after propagation through a random （or turbulent） medium the coherent beam becomes a partially coherent one. In this research, the analytical formula for the average intensity of Gaussian beam propagating through random medium is derived and the influence of coherent partiality on optical gradient force acting on dielectric particle rounded by a random media is investigated.

Superpositions of Laguerre-Gaussian Beams in Strongly Nonlocal Left-handed Materials

We present beam solutions of the strongly nonlocal nonlinear Schrodinger equation in left-handed mate- rims （LHMs）. Different Laguerre-Ganssian （LG） necklace beams, such as symmetric and asymmetric single layer and multilayer necklace beams are created by the superposition of two single beams with different topological charges. Such superpositions are then propagated through LHMs, displaying linear diffraction. It is found that the superposition of two LGnm beams with opposite topological charges does not show rotational behavior and that there exists rotation for other topological charge combinations. Our theory predicts that the accessible solitons cannot exist in LHMs.

Scheme for Realizing Probabilistic Teleportation of Bipartite Photonic States via Linear Optical Elements

We propose a probabilistic scheme for realizing teleportation of bipartite photonic states using linear optical elements where only requires a two-photon Bell state used as quantum channel. It reduces the requirement of the entanglement of quantum channel, but requires an additional photon and an auxiliary maximally entangled photon pair locally.

Attosecond x-Ray Pulse Generation by Linear Thomson Scattering of Intense Laser Beam with Relativistic Electron

Abstract Linear Thomson scattering of a short pulse laser by relativistic electron has been investigated using computer simulations. It is shown that scattering of an intense laser pulse of -33 fs full width at half maximum, with an electron of γ0 = 10 initial energy, generates an ultrashort, pulsed radiation of 76 attoseconds with a photon wavelength of 2.5 nm in the backward direction. The scattered radiation generated by a highly relativistic electron has superior quality in terms of its pulse width and angular distribution in comparison to the one generated by lower relativistic energy electron.

Optical Gain of V-groove Zn_(1-x)Cd_x Se/ZnSe Quantum Wires

The subband structures, distributions of electron and hole wave functions, state density, optical gain spectra, and transparency carrier density of the V-groove Zn 1-x Cd x Se/ZnSe quantum wires are investigated theoretically using four band effective-mass Hamiltonian, which takes into account the effects of the valence band anisotropy and the band mixing. The biaxial strain effect for quantum wires is included in the calculation. The compressive strain in the Zn 1-x Cd x Se wire region increases the energy separation between the uppermost subbands. The optical gain with xy -polarized light is enhanced, while optical gain with z -polarized light is strongly decreased. The xy -polarized optical gain spectrum has a peak at around 2.541 eV, with the transparency carrier density of 0.75×10 18 cm -3 . The calculated results also show that the strain tends to increase the quantum confinement and enhance the anisotropy of the optical transitions.

Beam Line Design and Construction of Gas Target for a 30MeV Medical Cyclotron

The first medical high intensity cyclotron CYCIAE-30 and its beam line for the isotope production were built in 1994 at China Institute of Atomic Energy.Now,an upgrading beam line system is designed based on the existing beam line of CYCIAE-30 to transport the beam extracted from the cyclotron to a gas target for the new isotope production,including elements location design,optics simulation and magnet design.The machining and installation of all the elements are accomplished based on the design.The beam tuning is finished and the transmission of 96.5% is obtained.

Physics issues in diffraction limited storage ring design

Diffraction limited electron storage ring is considered a promising candidate for future light sources,whose main characteristics are higher brilliance,better transverse coherence and better stability.The challenge of diffraction limited storage ring design is how to achieve the ultra low beam emittance with acceptable nonlinear performance.Effective linear and nonlinear parameter optimization methods based on Artificial Intelligence were developed for the storage ring physical design.As an example of application,partial physical design of HALS(Hefei Advanced Light Source),which is a diffraction limited VUV and soft X-ray light source,was introduced.Severe emittance growth due to the Intra Beam Scattering effect,which is the main obstacle to achieve ultra low emittance,was estimated quantitatively and possible cures were discussed.It is inspiring that better performance of diffraction limited storage ring can be achieved in principle with careful parameter optimization.

Two-beam based two-stage EEHG-FEL for coherent hard X-ray generation

The ability to generate stable and coherent short wavelength radiation is a great promise of the externally seeded free-electron laser. However, the fre- quency up-conversion efficiency is limited to a small number in a single stage setup. In this paper, we propose a new scheme to produce coherent hard X-ray FEL with two- beam based two-stage echo-enabled harmonic generation configuration. Electron beams with quite different proper- ties are separately used in each stage and a monochromator is adopted to purify the radiation from first stage for seeding the second stage. Three-dimensional start-to-end simulations have been performed with realistic parameters to show the feasibility of the proposed scheme.

Dual-lens beam compression for optical coupling in superconducting nanowire single-photon detectors

The optical coupling of superconducting nanowire single-photon detectors （SNSPDs） has always been restricted to a single-mode fiber for a limited detection area. In this study, for enhancing photon coupling, a dual-lens system operating at 2.2 K was used to compress the beam size on the basis of the Gaussian beam theory and geometric approximation. A magnification of approximately 0.3 was obtained, and a focused spot with diameter of approximately 10 ~m was measured from a multimode fiber. Assisted with the compressed beam, a system efficiency of 55 % （1550 nm） was achieved for a SNSPD with a detection area of 10 μm × 10 μm and 62.5 pm multimode fiber coupling. At the same time, a high speed of 106 MHz was measured with the proposed system. The realization of a highly compressed optical beam reduced the optical coupling requirement and helped maintain a high speed for the SNSPD.

Room-temperature epitaxial growth of V_2O_3 films

Herein we report the room-temperature epitaxial growth of V203 films by laser molecule beam epitaxy. X-ray diffraction pro- files show the room-temperature epitaxial V2O3 films orient in the [ 110] direction on α-Al2O3 （0001） substrates. Atomic force microscopy measurements reveal that the ultra-smooth surfaces with root-mean-square surface roughness of 0.11 nm and 0.28 nm for 10-nm-thick and 35-nm-thick V2O3 film, respectively. X-ray photoelectron spectroscopy results indicate the V3＋ oxida- tion state in the films. Typical metal-insulator transition is observed in films at about 135 K. The resistivities at 300 K are ap- proximately 0.8 mΩ cm and 0.5 mΩ cm for 10-rim-thick and 35-nm-thick V203 film, respectively.