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1.
冯军勤  吴福根  钟会林 《物理实验》2012,32(6):30-32,39
在测量超声波在空气中传播速度实验基础上,开设了超声波专题设计性实验,分别增加了测量压电换能器的共振频率、超声波在空气中的损耗系数、超声波在水中的传播速度等实验内容,丰富了大学物理实验教学内容,拓展了学生视野.  相似文献   

2.
高功率微波大气击穿的光学诊断   总被引:4,自引:3,他引:1       下载免费PDF全文
 介绍了一种高功率微波在波导内击穿光电诊断测量装置,测得了大气击穿的光电信号,获得了HPM击穿形成的等离子体衰减常数,对击穿点向源方向移动的猜想进行了实验验证。同时进行了短脉冲HPM在自由空间击穿实验,获得了HPM在自由空间击穿的系统光学图像,分析了击穿的放电特征。  相似文献   

3.
基于学习动机理论,探究了在演示实验教学过程中影响学习动机的内在因素,提出了激发学生内部学习动机的方法,并在此基础上提出了改进高中物理演示实验的教学策略,在理论上对物理演示实验教学的改进进行了反思和构建.  相似文献   

4.
在伟大的十月社会主义革命后的四十年中,我们国家在共产党的领导下经历了伟大的道路,从一个落后的农业国变成了先进的工业强国。在工业、农业以及苏联人民的文化发展方面,都获得了巨大的成就。为社会主义社会服务的科学,在我国也达到了空前的水平。在这一方面,苏联物理学的发展可以作为特别明显的例子,苏联物理学很早就跨出了实验室,给予其他科学的发展以重大的影响,它已成为现代技术的基础了。  相似文献   

5.
蒸煮液中的水分对纸浆卡伯值在线测量的影响分析   总被引:1,自引:0,他引:1  
本文结合制浆造纸工业,对水分进行了光谱定性分析,探讨了在制浆蒸煮过程中水分对纸浆卡伯值在线分析系统的影响,确立了在蒸煮液中木素浓度在线测量的合适波长,避开了在蒸煮液中的水分对测量结果的影响,为后续的研究工作打下了基础  相似文献   

6.
东汉末年爆发了张角兄弟领导的黄巾大起义,他们用革命的武装斗争沉重地打击了东汉王朝顽固执行儒家路线的暴政,猛烈地冲击了儒家反动思想在社会上的影响,在客观上为庶族地主登上政治舞台,推行法家的政治路线扫除了障碍。三国初期魏、蜀、吴都在不同程度上执行法家路线,是决非偶然的。 代表地主阶级革新力量的曹操,在农民战争动摇了东汉王朝的基础上,继承战国、秦、汉法家的耕战政策,严军纪,重法治,在一定程度上打破儒家的门第观念,用人“唯才所宜,不间远近”。这些进步措施,促进了社会经济的发展,从而完成了统一北方的大业。 在科学技术工作…  相似文献   

7.
利用循环伏安法研究了酸性介质中甲醛在粗糙铂电极上电氧化行为 ,考察了支持电解质浓度 ,电极表面结构等因素对甲醛氧化行为的影响 ,发现了甲醛在粗糙铂电极上的自发解离现象。采用共焦显微拉曼技术研究了甲醛在粗糙铂电极上解离吸附行为 ,获得了甲醛在该电极表面解离吸附的分子水平信息 ,并且从分子水平验证了甲醛在粗糙铂电极上的自发解离现象。  相似文献   

8.
在拨乱反正、百废待兴的年代里,根据中国物理学会的决定,在中国科协的支持下,经过整整一年紧张的准备和筹建,《大学物理》终于在1982年元月和读者见面了.在此期间,北京师范大学不仅给了我们生存空间,并且在刊物的行政工作、办公条件等各个方面给予了极大的支持;高等教育出版社不仅包揽了刊物的印刷、出版,并且还给了必要的活动资金,真可谓是雪中送炭;此外,在开创阶段,北京大学出版社也曾给予我们很大的支持.在此,我谨代表《大学物理》向他们致以崇高的敬意.  相似文献   

9.
基于波动力学的基本概念,提出了在能量守恒框架下建立波动力学方程的新思路与方法.首先,回顾了用牛顿第二定律推导波动力学方程,同时回顾并分析了利用Hamilton变分原理,推导了在连续介质中的Lagrange方程、Hamilton正则方程,以及相应的波动力学方程;其次,在能量守恒的框架下,建立了连续介质的Lagrange方程、Hamilton正则方程和波动力学方程,并证明其结果与利用经典力学推导的结果的一致性,特别地,澄清了用Hamilton变分原理建立保守系统下连续介质的Lagrange方程和Hamilton正则方程时在边界条件应用时的一些模糊认识.在能量守恒框架下建立一系列动力学方程,为我们在不涉及泛函求极值的变分原理等基础上刻画和表述复杂介质中波动现象的演化规律提供了另一种途径,也深入探讨了最小作用原理的物理本质.最后,在能量守恒的框架下给出了建立黏弹性介质中的波动力学微分方程的应用.  相似文献   

10.
最近,欧洲和美国的一些科学家,在丁肇中先生的领导下,研制了一台新的反物质磁谱仪(简称AMS).它把当前带电粒子探测灵敏度提高了大约4个数量级,它将工作在外层空间.本人在意大利INFN,Peruga实验室参加了这一工程,AMS样机已完工,正在美国进行统调. 地球上的人,一直在观察来自太空的粒子,特别是光子(光射线、无线电波等),研制了很多探测器,它们有的在地球表面工作,有的在太空工作,已经导致了许多重要的发现,对研究宇宙的起源和结构起了很大的作用.然而,对来自空间的带电粒子的精确测量是十分困难的,…  相似文献   

11.
A novel system for multiplexed optical fiber interferometric sensors is proposed applying the synthesis of optical coherence function with phase generated carriers. The ideal parameters of the laser diode frequency modulation for the phase generated carrier with the synthesis of the optical coherence function are discussed. A basic experimental setup including two interferometric sensors is constructed. The results show that the phase signal from the two sensors can successfully be demultiplexed by scanning the synthesized coherence peak.  相似文献   

12.
Abstract

This article reports that spectral phase coherence in the supercontinuum in long pulse regime can be measured simply and effectively by using an interference technique with the help of a Mach–Zehnder interferometer. It is also demonstrated that chromatic dispersion on the fringe visibility of interference spectral patterns is overcome in the setup. The technique is applied to characterize supercontinuum spectral phase coherence in a highly non-linear optical fiber with different input conditions: unseeded, coherent seeded, and incoherent seeded picosecond pumps. The results confirm the phase coherence characteristic predicted theoretically in previous studies.  相似文献   

13.
唐弢  赵晨  陈志彦  李鹏  丁志华 《物理学报》2015,64(17):174201-174201
本文报道了一种超高分辨率谱域光学相干层析成像(SD-OCT)系统. 该系统基于超连续谱激光光源并截取部分光谱作为宽带光源, 其中心波长为665 nm, 光谱半高全宽(FWHM) 230 nm. 系统轴向分辨率0.9 μm, 轴向扫描速率28600行/秒, 横向分辨率3.9 μm, 横向视场1 mm, 最大成像深度0.6 mm(空气中). 利用研制的超高分辨率SD-OCT系统, 对不同型号的工业砂纸精细结构进行了成像, 并与普通SD-OCT的成像结果进行对比, 充分展示了研制系统在材料无损检测中优势.  相似文献   

14.
In this paper we present a novel configuration of an NPR mode-locked Er-doped laser. This new optical setup uses voltage controlled LC cells to replace standard retarders (quarter-and half-waveplates) inside the laser cavity. Using this novel, mechanical-adjustment-free setup a mode-locking was obtained with sub-500 fs pulse duration and an average power exceeding 40 mW. Presented results show that using simple LC cells, an optical layout of an NPR mode-locked laser can be greatly simplified.  相似文献   

15.
An optical speckle-displacement correlator based on hybrid optical–digital joint transform correlator architecture with a digital first stage and an optical second stage has been used to determine the correlation peak position with subpixel accuracy, without the use of intricate interpolation algorithms. A thorough analysis and a calculation of the parameters of the second optical stage are performed in order to achieve the necessary magnification of the correlation peak, so as to obtain an accurate definition of the peak position. The experiment setup for the realization of the optical speckle-displacement technique was constructed with a digital Fourier processor as its basic component, making possible a joint power spectrum median and ring median binarization, and an optical Fourier processor. The results which were obtained demonstrate that a setup of this kind can produce sharp and narrow correlation peaks, and can provide the necessary magnification for finding the peak position with subpixel accuracy.  相似文献   

16.
吕德胜  屈求智  汪斌  赵剑波  李唐  刘亮  王育竹 《中国物理 B》2011,20(6):63201-063201
Using modularized components, we have built a miniaturized optical system for 87Rb atomic fountain clock that is fitted on an 80 cm × 60 cm optical breadboard. Compared with the conventional optical setup on the table, our system is more compact, more robust and miniaturized. Taking advantage of this system, laser beams are transmitted through eight optical fibre patch cords from the optical breadboard to an ultra high vacuum system. This optical setup has operated for five months in our fountain system and required no alignment.  相似文献   

17.
We apply here spectral‐domain optical coherence tomography (SD‐OCT) for the precise detection and temporal tracking of ferroelectric domain walls (DWs) in magnesium‐doped periodically poled lithium niobate (Mg:PPLN). We reproducibly map static DWs at an axial (depth) resolution down to ~ 0.6 μm, being located up to 0.5 mm well inside the single crystalline Mg:PPLN sample. We show that a full 3‐dimensional (3D) reconstruction of the DW geometry is possible from the collected data, when applying a special algorithm that accounts for the nonlinear optical dispersion of the material. Our OCT investigation provides valuable reference information on the DWs’ polarization charge distribution, which is known to be the key to the electrical conductivity of ferroelectric DWs in such systems. Hence, we carefully analyze the SD‐OCT signal dependence both when varying the direction of incident polarization, and when applying electrical fields along the polar axis. Surprisingly, the large backreflection intensities recorded under extraordinary polarization are not affected by any electrical field, at least for field strengths below the switching threshold, while no significant signals above noise floor are detected under ordinary polarization. Finally, we employed the high‐speed SD‐OCT setup for the real‐time DW tracking upon ferroelectric domain switching under high external fields.  相似文献   

18.
艾剑锋  陈爱喜  邓黎 《中国物理 B》2013,22(2):24209-024209
We discuss the influences of two different types of mechanisms of quantum coherence on optical bistability in a semiconductor quantum well structure.In the first mechanism,only quantum coherence induced by the resonant coupling of a strong control laser is considered.In the second mechanism,the decay coherence is taken into account under the condition where the control field is weak.In two different cases,optical bistability can be obtained through choosing appropriate physical parameters.Our studies show quantum coherence makes the optical nonlinear effect of the system become stronger,which takes an important role in the process of generating optical bistability.A semiconductor quantum well with flexibility and easy integration in design could potentially be exploited in real solid-state devices.  相似文献   

19.
Theoretical investigations made not long ago regarding the construction of spatial-coherence spectral filters (SCSFs) are rendered into experiments by designing and fabricating a Fourier-achromat experimental setup analyzed in the theoretical studies. It is shown that the phenomenon of spectral shift due to spatial coherence also known as the Wolf effect can be exploited to make special types of low-pass and band-pass spectral filters with special spectral characteristics that are not shown by the conventional filters. A Fourier-achromat is employed to construct the SCSFs. The experimental results within the experimental limitations and measurement uncertainty agree well with the theory. These filters might find applications in (i) astronomy (in the search of particular spectral lines) (ii) developing spectrum-selective optical interconnects or (iii) in cryptography.  相似文献   

20.
By using an amplitude-type spatial light modulator to load angular spectrum of Mathieu function distribution along a narrow annular pupils, the Durnin's experimental setup is extended to generate various types of Mathieu beams. As a special type of Mathieu beams, Bessel beams are also generated using this optical setup. Furthermore, the optical morphology of the Mathieu beams family are also presented and analyzed.  相似文献   

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