影响玻璃微珠回向反射性能的主要因素分析

从理论和实验两方面分析了玻璃微珠的回向反射特性,主要讨论了玻璃微珠的折射率和其反射层面积这两个因素对回向反射性能的影响. 研究结果表明,折射率增大, 折射率小于2时,回向反射性能逐渐增强, 相反, 在折射率大于2时, 回向反射性能减弱; 反射层面积的大小会影响入射光线的完整回向反射过程; 最后定义了有效回向反射角度, 并给出了玻璃微珠在激光照射下的二维回向反射光照度分布.     

高折射率玻璃微珠色散特性及影响

基于二次彩虹法用三种不同波长(632.8 nm、532 nm、404 nm)的激光测量了玻璃微珠的折射率,并由柯西色散公式拟合得到三种典型高折射率玻璃微珠1.90、1.93和2.2的色散方程,得出现行的玻璃微珠具有正常色散但色散较大的结论.通过分析在不同入射角情况下,色散对玻璃微珠回归反射性能的影响,得出折射率1.90和1.93的玻璃微珠具有优良的回归反射性能.此外,用光线追迹模拟了色散对回归反射后光能量在近轴区域分布的影响,折射率1.90和1.93的玻璃微珠回归反射光线的能量主要集中在5°范围内.     

高折射率玻璃微珠折射率的测量

用激光作为测量光源,利用激光经玻璃微珠一次或多次内部反射后出射,形成最小偏转角的原理,对高折射率玻璃微珠折射率的测量进行了理论分析和实验测试.比较了不同内反射次数对测量精度的影响.该测量方法尤其适用于已在微珠列阵逆向反光膜上大量使用的、折射率位于1.8～2.4之间的高折射率玻璃微珠折射率的测量,较传统方法具有简便、快捷和安全的特点.经分析和对不同类型微珠样品的实测比较,获得了测量精度优于1%的结果.     

彩虹法和成像法测量玻璃微珠折射率对比研究

基于几何光学原理,彩虹法使用激光作为光源,利用激光在玻璃微珠中进行一次或者多次内反射后出射形成最小偏向角,在最小偏向角附近形成彩虹条纹,通过测量彩虹条纹来反演计算玻璃微珠的折射率。然而,成像法则根据厚透镜的成像原理,对玻璃微珠所成的像经过显微物镜放大后使用CCD相机进行接收,获得玻璃微珠的焦距,进而测得对应玻璃微珠的折射率。较传统方法来说,彩虹法和成像法具有安全、简便和快捷的优点。对型号不同的玻璃微珠,分别使用彩虹法和成像法测量其折射率,并对它们的测量结果进行了对比分析,都获得相对于名义值的误差小于1%的结果。     

梯度折射率微球回归反射材料的研究

提出一种回归反射面材的新结构,以梯度折射率微球代替传统的超高折射率匀质玻璃微球.利用四阶Runge-Kutta方法进行光线追迹的理论计算,确定了制作新型回归反射面材的工艺参数.结果表明,按此条件制作回归反射面材可大幅度降低原先对折射率的过高要求,并显著提高回归反射的性能.     

基于光电技术的玻璃折射率测量

折射率是玻璃的重要光学性能之一,其测量方法很多。为了准确、快速、适应性好地测量玻璃折射率,提出一种基于光电技术的新测量方法。利用平行平板玻璃对入射光线的侧向偏移特性,可以得到不同折射率的玻璃对光线的不同偏折程度来确定折射率和偏移量之间的关系式,并通过采用位置敏感探测器将光斑像点的位移转化为电信号的输出,从而实现折射率转化为电信号。设计了光学系统和信号处理单元,通过实验测得了K9玻璃的折射率,并与最小偏向角法测量折射率进行对比,测量数据表明该方法可行,测量精度可达到10-4,可以满足测量高精度玻璃折射率的要求。     

高折射玻璃微珠粒径与折射率关系的研究

利用激光照射高折射率玻璃微珠下形成的二次彩虹现象,以艾里的虹理论为基础对玻璃微珠折射率进行了测量。推导了玻璃微珠尺寸对折射率影响的计算公式,表明半径差异在10μm时,折射率的测量误差为10^-3数量级。此外,通过软件模拟计算玻璃微珠的二次彩虹现象,并对微珠的折射率进行了测量,验证了二次彩虹方法的正确性,同时也表明玻璃微...     

二次彩虹法测量高折射率玻璃微珠折射率研究

基于米氏散射理论解释了激光照明下玻璃微珠的二次彩虹精细结构的成因,发现折射率的差异将直接影响二次彩虹精细结构的位置.对于实验中玻璃微珠半径变化引起二次彩虹精细结构间距变化的现象亦用米氏散射理论进行了模拟分析和实验研究.利用米氏散射的近似理论——艾里理论对玻璃微珠的折射率进行了测量.在对玻璃微珠二次彩虹精细结构所计算得到的折射率的统计分析基础上,通过校正测量误差后得到了玻璃微珠折射率的准确数据.     

Circular Disc Linear Refractometer for Liquids

提出一种具有线性响应的圆盘型液体光电折射率计。光线在圆盘内的多次反射显著地消除了非全内反射的影响，有效地改善了测量线性度。这种圆盘型光电折射率计甚至可对非平行入射光束仍保持相当好的线性度。     

圆盘型液体线性光电折射率计

提出一种具有线性响应的圆盘型液体光电折射率计，光线在圆盘内的多次反射显著地消除了非全内反射的影响，有效地改善了测量线性度，这种圆盘型光电折射率计甚至可对非平行入射光束仍保持相当好的线性度。     

Self-organization of five species in a cyclic competition game

Cyclic competition game models, particularly the “rock–paper–scissors” model, play important roles in exploring the problem of multi-species coexistence in spatially ecological systems. We propose an extended “rock–paper–scissors” game to model cyclic interactions among five species, and find that two of the five can coexistent when biodiversity disappears, which is different from the “rock–paper–scissors” game. As the number of fingers is five, we named the new model the “fingers” game, where the thumb, forefinger, middle finger, ring finger, and little finger cyclically dominate their subsequent species and are dominated by their former species. We investigate the “fingers” model in two ways: direct simulations and nonlinear partial differential equations. An important finding is that the number of species in a cyclic competition game has an influence on the emergence of biodiversity. To be specific, the “rock–paper–scissors” model is in favor of maintaining biodiversity in comparison with the “fingers” model when the variables (population size, reproduction rate, selection rate, and migration rate) are the same. It is also shown that the mobility and reproduction rate can promote or jeopardize biodiversity.     

Contrastive analysis on tone between Putonghua and Taiwan Mandarin

The differences of the pitch and duration of Chinese syllables between Putonghua （PTH） and Taiwan Mandarin （TM） were studied. The speech materials to be used are not only isolated syllables, but also sentences. The results reveal that： For the isolated syllables, T1 and T2 in TM are influenced by Minnan dialect, therefore their pitch are lower than those in PTH. T3 is fall-rise in PTH, while it is fall in TM. Moreover, the syllable duration sequence for different tone is T3〉T2〉T1〉T4 in PTH, while it is T1〉T2〉T3〉T4 in TM. For the syllables in sentences, T2 is mid-rise in PTH, while it is mid-level in TM. And the T3 is longer than T4 but shorter than T1 or T2 in PTH, while it is the shortest in TM. Furthermore the effects of prosodic phrase boundary on duration for different tones are almost the same in PTH, but the lengthening part of T1 or T2 is longer than that of T3 or T4 in TM.     

Experimental study on downstep in Chinese intonation

Downstep in pitch contour of Chinese Putonghua is examined using subtly designed sentences by controlling tone combinations. The results show both automatic and nonautomatic downstep phenomena exist in Chinese. In non-automatic downstep, low tones compress downwards the pitch range of the following syllables. and the main influence of downstep is on topline. Low tone not only lower the topline behind it, but also raise the high tones before it, the effects are compatible with each other. In automatic downstep, the topline of pitch contour in intonational phrase is presented as a linear downtrend, but it differs among speakers due to the effect of personal stress practice. In comparison with downstep phenomenon in other tone or non-tone languages, the downstep ratio in Chinese is not constant, and the domain of downstep is not limited within the adjacent tones.     

Abelian-Higgs phase of SU(2) QCD and glueball energy

It is shown that SU(2) QCD admits an dual Abelian-Higgs phase, with a Higgs vacuum of a type-Ⅱ superconductor. This is done by using a connection decomposition for the gluon field and the random-direction approximation. Using a bag picture with soft wall, we presented a calculational procedure for the glueball energy based on the recent proof for wall-vortices [Nucl. Phys. B 741(2006)1].     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Signal generation in an isotropic medium in scanning electron acoustic microscope

Based on the research in Ref. [5][Materials Science and Engineering, 1989; A122： 57 63], an improved model of heat source is set up, the different modes of Lamb wave in an isotropic sample generated by a chopped electron beam at frequency f are obtained with integral transform and normal function expansion method, and the output signal of PZT coupled at the back surface of the sample is found out. The generation mechanism of SEAM （Scanning Electron Acoustic Microscopy） signal is discussed. It shows that the SEAM is a near field imaging technique with high spatial resolution and its best lateral spatial resolution is about 2√2α （α is the radius of the focused electron beam）. Some of experimental results of SEAM images are presented in the paper and it shows that the spatial resolution of SEAM is better than 0.5 μm and smaller than the thermal diffusion length of the sample. Therefore the character of near field imaging in SEAM is also proved experimentally.     

High efficiency filtering using two-dimensional photonic crystal coupled cavity structures

Transmission spectra of coupled cavity structures (CCSs) in two-dimensional (2D) photonic crystals (PCs) are investigated using a coupled mode theory, and an optical filter based on CCS is proposed. The performance of the filter is investigated using finite-difference time-domain (FDTD) method, and the results show that within a very short coupling distance of about 3λ, where λ is the wavelength of signal in vacuum, the incident signals with different frequencies are separated into different channels with a contrast ratio of 20 dB. The advantages of this kind of filter are small size and easily tunable operation frequencies.