Forward-imaging instruments for optical coherence tomography

We discuss the design and implementation of forward-imaging instruments for optical coherence tomography (OCT), which require the delivery, scanning, and collection of single-spatial-mode optical radiation. A hand-held surgical probe for use in open surgery can provide cross-sectional images of subsurface tissue before surgical incisions are made. A rigid laparoscope for minimally invasive surgical OCT imaging provides a simultaneous enface view of the area being imaged. OCT imaging is demonstrated on in vitro human specimens.     

Great expectations: Specific lexical anticipation influences the processing of spoken language

Background  

Recently several studies have shown that people use contextual information to make predictions about the rest of the sentence or story as the text unfolds. Using event related potentials (ERPs) we tested whether these on-line predictions are based on a message-level representation of the discourse or on simple automatic activation by individual words. Subjects heard short stories that were highly constraining for one specific noun, or stories that were not specifically predictive but contained the same prime words as the predictive stories. To test whether listeners make specific predictions critical nouns were preceded by an adjective that was inflected according to, or in contrast with, the gender of the expected noun.     

Interferometric precision measurements with Bose–Einstein condensate solitons formed by an optical lattice

We propose the precision measurement of both angular rotation and of the gradient magnetic of a field based on the use of matter wave interferometers with soliton states of a Bose-Einstein condensate (BEC). We consider the formation of these soliton states in a BEC with negative scattering length by an optical lattice produced by two counterpropagating laser beams. We determine the parameters of both the initial condensate and the optical radiation necessary for the formation of coherent solitons. We demonstrate that this interferometer can be used to measure magnetic field gradient with a precision of 10^-2 pT/cm. Our calculations show that the sensitivity of a gyroscope based on a ring, two-port matter wave interferometer can achieve 2.6×10^-7 rad s^-1. The precision of this method is more than ten times greater than in that of rotating interferometer with cooled atoms.     

一种用于大型光学仪器的自动检焦装置

介绍了一种小型化的自动检焦装置，该装置用2块小口径五棱镜对径放置在镜筒前，用半导体激光器做光源，用CCD作为光电转换器件，通过测量两光斑在CCD上的移动量，从而计算出离焦量，采用相关法处理数据，实现了亚像素测量精度。实验结果表明检焦分辨率力≤10μm．     

Controllable optical bistability of Bose—Einstein condensate in an optical cavity with Kerr medium

We study the optical bistability for a Bose-Einstein condensate of atoms in a driven optical cavity with Kerr medium. We find that both the threshold point of optical bistability transition and the width of optical bistability hysteresis can be controlled by appropriately adjusting the Kerr interaction between the photons. In particular, we show that the optical bistability will disappear when the Kerr interaction exceeds a critical value.     

Bose–Einstein condensates in a ring optical lattices trap

The evolution of Bose–Einstein condensates (BECs) loaded into a periodic ring optical lattices (OL) trap is studied. By means of the variational method and direct numerical simulations of the Gross–Pitaevskii (GP) equation, the ground state properties and the vortex stabilities of the condensates for both repulsive and attractive cases are investigated. The results show that the bound states exist for determinate OL strength and interatomic interaction. However, the ground states of BECs undergo delocalizing–localizing transition for both attractive and repulsive cases as the strength of the OL or the interatomic interaction is decreased below the critical value. The ring OL can suppress the delocalizing transition efficiently.     

Nonlinear optical effects in an inhomogeneous Bose—Einstein condensate

A variety of nonlinear optical effects arising upon the interaction of a signal beam with a strong pump beam at the second harmonic frequency in a nonlinear Bose-Einstein condensate is studied. Along with the ratio of signal and pump beam widths, the influence of the mutual geometry of the trap and the pump beam profile on the studied processes is investigated.     

Quantum phase transition of two-component Bose–Einstein condensates in optical lattices

In this Letter we study the superfluid–Mott-insulator (SMI) phase transition of two-component Bose–Einstein condensates (BECs) in an optical lattice. The analytic exciation energy spectrum is obtained by means of Bogoliubov transformation and hence the SMI phase transition condition is determined explicitly. Moreover, the characteristics of superfluid phase are explained from the energy spectrum.     

爱因斯坦的双重奇迹

一 今年是国际物理年，也是“爱因斯坦奇迹年”100周年，德国政府干脆称它为“爱因斯坦年”．“爱因斯坦奇迹年”指的是1905年，年仅26岁的爱因斯坦，一个在伯尔尼瑞士专利局当三级技术员，利用每天8小时公务以外的业余时间，写出了6篇物理学论文，在三个不同领域做出了四项划时代的贡献，创造了科学史（也是人类历史）上的奇迹．而这些贡献都是在短短7个月（1905年3月至9月）内完成的．     

Transport behaviour of a Bose Einstein condensate in a bichromatic optical lattice

We investigate the Bloch and dipole oscillations of a Bose Einstein condensate (BEC) in an optical superlattice. We show that, as the effective mass increases in an optical superlattice, the BEC is localized in accordance with recent experimental observations [J.E. Lye et. al. Phys. Rev. A 75, 061603 (2007)]. In addition, we find that the secondary optical lattice is a useful additional tool to manipulate the dynamics of the atoms.      

Application for optical thermometers calibration based on virtual instruments

In this paper we present a new developed application for calibration of optical thermometers which is implemented in the Serbian Metrology Institute. The method for calibration of optical thermometer–pyrometer is based on measuring blackbody temperature via thermocouple standards and measuring voltage on pyrometer in temperature range from 550 to 1650 °C. The objective is to precisely determinate calibration curve of pyrometer—transfer function. The metrology traceability was realized through thermocouples standard which has traceability to the international standard. A developed application has a role to control and supervise calibration process. Based on virtual instruments (VI), application offers monitoring measurement parameters in real time on three charts. The main advantage of the developed VI application is reduction of measurement uncertainty of type A by increased accuracy with multi—temperature measurement up to 3 thermocouples on temperature equilibrium in the measurement system and automatic data processing by converting voltage to temperature, calculating the mean value and standard deviation of the mean value. Advantage is also reflected in permanent data logging while application is running and low cost and user friendly interface One of the goals is to improve quality of metrological services through this application and support the establishment of a traceability chain to SI.     

爱因斯坦1905年创造"奇迹"的五篇论文--纪念布朗运动理论、狭义相对论、光量子论创建100周年

2004．年6月10日联合国大会通过决议，把2005年定为“国际物理年”．之所以选择2005年为“国际物理年”，其原因之一在于2005年是爱因斯坦关键性科学发现100周年，这些发现为现代物理学奠定了基础．     

Transmission of radiation with rapid temporal modulation through optical instruments

We examine theoretically the transmission of radiation with rapid temporal modulation (short pulse or rapid statistical modulation) through a grating or focused by a concave mirror (lens). It is shown that the far-field diffraction patterns from a grating may be considerably modified because of such rapid modulation and that these patterns may be used for estimation of the coherence time or the pulse duration. In the case of focusing, the focal spot size slightly increases on decreasing the pulse duration.     

Chaotic synchronization in Bose Einstein condensate of moving optical lattices via linear coupling

A systematic study of the chaotic synchronization of Bose–Einstein condensed body is performed using linear coupling method based on Lyapunov stability theory, Sylvester's criterion, and Gerschgorin disc theorem. The chaotic synchronization of Bose–Einstein condensed body in moving optical lattices is realized by linear coupling. The relationship between the synchronization time and coupling coefficient is obtained. Both the single-variable coupling and double-variable coupling are effective. The results of numerical calculation prove that the chaotic synchronization of double-variable coupling is faster than that of single-variable coupling and small coupling coefficient can achieve the chaotic synchronization.Weak noise has little influence on synchronization effect, so the linear coupling technology is suitable for the chaotic synchronization of Bose–Einstein condensate.     

光学仪器胶粘剂应用现状及进展

本文是在对国内光学零件加工及光学仪器产品胶粘剂的应用现状与研究动态的调研基础上，结合作者的工作，综合介绍了光学零件加工过程中工艺用粘接材料与工艺材料用树脂结合剂；光学零件、光学分划元件、光学偏振元件、光学塑料元件等的胶合用光学胶；光学仪器产品结构用结构胶及非结构胶；光学仪器产品及部件用密封胶等的应用现状及其进展概况     

Stable all-optical formation of Bose–Einstein condensate using pointing-stabilized optical trapping beams

By stabilizing the beam pointing of optical trapping beams, we have succeeded in stable formation of Bose–Einstein condensate (BEC) of ⁸⁷Rb with all-optical method. The thermal effect of acousto-optic modulator (AOM) is usually one of the most serious problems to induce beam-pointing instability, especially for high power CO₂ laser. By passing the beam through AOM twice, we have improved the beam pointing from about 4.8 mrad to less than 0.4 mrad, which has been experimentally confirmed to be small enough to stably form BEC at the crossed region of CO₂ lasers as well as to perform experiments using an optical lattice which might have been affected by beam-pointing instability. PACS 32.80.Pj; 42.79.Jq; 03.75.Mn     

Stability of trapped Bose-Einstein condensates in one-dimensional tilted optical lattice potential

Using the direct perturbation technique,this paper obtains a general perturbed solution of the Bose-Einstein condensates trapped in one-dimensional tilted optical lattice potential. We also gave out two necessary and sufficient conditions for boundedness of the perturbed solution. Theoretical analytical results and the corresponding numerical results show that the perturbed solution of the Bose-Einstein condensate system is unbounded in general and indicate that the Bose-Einstein condensates are Lyapunov-unstable. However,when the conditions for boundedness of the perturbed solution are satisfied,then the Bose-Einstein condensates are Lyapunov-stable.     

Dimensional crossover of a Rabi-coupled two-component Bose–Einstein condensate in an optical lattice

Dimensionality is a central concept in developing the theory of low-dimensional physics.However,previous research on dimensional crossover in the context of a Bose-Einstein condensate(BEC) has focused on the single-component BEC.To our best knowledge,further consideration of the two-component internal degrees of freedom on the effects of dimensional crossover is still lacking.In this work,we are motivated to investigate the dimensional crossover in a three-dimensional(3D) Rabi-coupled two-compon...