【摘 要】
:
General relativity establishes the equality between matter-energy density and the Riemann curvature of spacetime. Therefore, light or matter will be bent or trapped when passing near the massive celestial objects, and Newton’s second law fails to explain
【机 构】
:
InstituteofElectromagneticsandAcousticsandDepartmentofPhysics,XiamenUniversity,Xiamen361005,China
【出 处】
:
PhotonicsResearch
论文部分内容阅读
General relativity establishes the equality between matter-energy density and the Riemann curvature of spacetime. Therefore, light or matter will be bent or trapped when passing near the massive celestial objects, and Newton’s second law fails to explain it. The gravitational effect is not only extensively studied in astronomy but also attracts a great deal of interest in the field of optics. People have mimicked black holes, Einstein’s ring, and other fascinating effects in diverse optical systems. Here, with a gradient index lens, in the geometrical optics regime, we mimic the Schwarzschild precession in the orbit of the star S2 near the Galactic Center massive black hole, which was recently first detected by European Southern Observatory. We also find other series of gradient index lenses that can be used to mimic the possible Reissner–Nordstr?m metric of Einstein’s field equation and dark matter particle motion. Light rays in such gradient lenses will be closed in some cases, while in other cases it would be trapped by the center or keep dancing around the center. Our work presents an efficient toy model to help investigate some complex celestial behaviors, which may require long period detection by using high-precision astronomical tools. The induced gradient lenses enlightened by the gravitational effect also enrich the family of absolute optical instruments for their selective closed trajectories.
其他文献
An efficient scheme for photon statistics measurement is presented based on the Hanbury-Brown-Twiss configuration. We set the sampling time Ts to satisfy the relationship of Ts
本文讨论了连续波环形染料激光器的单向运转特性。采用改进的Ganiel速率方程模型,分析了在单向运转条件下泵浦光通量、染料分子密度等参量对激光光通量、激发单重态粒子集居数密度以及增益的影响;揭示了在连续波环形染料激光器中单向运转条件下存在粒子集居数密度的非对称性、激光光通量与激活介质内空间位置的相关性和增益峰值波长的扫描现象。本文给出了数值计算结果。
为了研究爆炸物在太赫兹波段的光谱特性, 进而对爆炸物进行检测和识别, 利用太赫兹时域光谱系统(THz-TDS),对RDX, HMX,DNT,PETN,TNPG 五种纯品炸药以及以RDX为基底的混合炸药(8701,PW0,R791,R852,塑性炸药(SU-1))和以HMX为基底的混合炸药(8702)的太赫兹吸收光谱在真空条件下进行了测量。然后用两种人工神经网络(ANNs)—自组织(SOM)神经网络和多层感知器 (MLP)神经网络—对爆炸物吸收光谱进行了识别, 经过不断地学习和训练, 取得了较好的鉴别结果,
11月16日至20日在波士顿材料研究学会年会期间召开的激光和电子束与固体相互作用专题讨论会,是至今为止该领域的一次最大集会。来自14个国家的代表提交了128篇论文,内容包括基本作用机理,束加工技术应用于半导体器件制作和材料特性转变等。出席讨论会的代表多达400人。下面是会议付主席,贝尔实验室的塞拉(G. K. Oeller)和橡树岭国家实验室的阿普尔顿(Β. R. Appleton)为“Laser Focus”准备的报导。
根据距离选通微光ICCD组件及水下高速成像组件中对于门控电路的需求, 本文解决了在外触发模式下, 系统输出脉冲与外触发之间的同步效果差与抖动大问题, 提出一种基于FPGA精细调节单元IODELAY的高精度低抖动的同步脉冲控制技术。此单元具有受温度影响小、时间分辨率高的优势, 充分满足了组件中像管对于门控时间精度与抖动的要求, 此技术在各类门控组件中有很好的应用价值。
The article provides information about the image on the cover of Advanced Photonics, Volume 3, Issue 5.
结合茂名外场观测数据以及气象要素再分析数据,对台风外围环流影响和局地海陆风环流(SLBC)影响下沿海地区的大气边界层(ABL)结构识别方法和特征规律展开研究。利用气象要素探空数据和微脉冲激光雷达(MPL)观测数据进行了大气边界层高度(BLH)识别方法的适用性分析,提出了一种新的基于微脉冲激光雷达的BLH识别方法,以有效提高复杂边界层结构情况下激光雷达识别BLH结果的准确性,进而分析了受大尺度和局地环流影响的ABL结构以及BLH的时空变化特征。结果表明:沿海地区在没有大尺度天气系统的控制时,局地SLBC的影
面对当前复杂场景下异常事件检测算法过度依赖帧级别标记,以及I3D模型耗时长、内存占用大等问题,设计了一种基于I3D的M-I3D模型并将其作为特征提取器,提出一种了基于深度时空特征和多示例学习的异常检测方法。所提方法将正常视频和异常视频作为包,并将视频片段作为多示例学习中的示例。利用M-I3D模型提取每个视频片段的特征,并将提取到的特征向量输入到三层全连接层中,进而自动学习一个深度异常排序模型,该模