铟镓砷磷半导体激光的生物特性及73例椎基底动脉供血不足者的治疗

通过对甸镓砷磷半导体激光和常用He-Ne激光生物特性进行初步比较,说明半导体激光对治疗椎基底动脉供血不足疗效较明显。     

Line Narrowing of a Tunable High Pressure CO2 Laser by Means of an Improved Non-Littrow Cavity

A model is reported to foresee ,for different mirror choices, the spectral properties of a high pressure, frequency tunable, CO₂ laser, operating with a non-Littrow grating mounting. The calculations show a larger frequency selectivity for not collimated plane cavities. The model is experimentally verified in a suitable high pressure laser. In particular narrowed linewidths less than 300MHz ( FWHM) are obtained.     

死髓变色前牙的激光漂白治疗临床评价

本文的研究目的是探讨激光冠内漂白治疗死髓牙变色的治疗作用。材料与方法 :漂白基本操作同激光活髓牙变色的漂白操作程序。先将牙龈及口唇有效防护 ,将漂白药物放在唇舌两面并同时封入根冠内。结果 :所有牙齿的灰暗变色均有 3- 5级的色度提高。平均治疗次数为 3.4± 0 .75 ,脱色 85 %以上的占 89%。结论 :牙齿创伤和牙髓分解是冠内变色的常见原因 ,激光冠内漂白是治疗这种变色的有效手段 ,可以完全恢复患者的自信。     

用频域法实现圆环形目标物的计数

研究了用频域法实现圆环形目标物计数的方法。对空域中含有圆环形目标物的二值图像，经傅里叶变换后在频域内进行滤波，再经傅里叶反变换后取一阈值进行处理，则对应于圆环形目标物即变为一个实心体，然后对实心体进行计数即可实现对圆环形目标物的计数。对该方法进行了数学描述，并分别用模拟图像和实际图像进行了实验。结果表明，该方法消除噪声的效果好，对部分封闭圆的检测同样有效，且可用于目标物有粘连的情况。该方法对圆环形目标物的尺寸相差不大的情况更为有效。     

激光标线的原理和实验

根据几何光学知识分析了激光标线原理.理论和实验表明:激光标线长度与激光光束形状、光学元件形状及材料折射率有关.并讨论了激光标线向两侧扩展的原因.     

Skin-Depth Theory Explaining Anomalous Picosecond-Terawatt Laser Plasma Interaction II

The anomaly of ion emission at laser irradiation of targets measured by Badziak et al. was analyzed on the background of the extensive research in the past. In contrast to the irradiation with lasers of longer than 100 ps pulse duration, a drastic decrease of the maximum ion energies was measured with ps pulses. Very strange was the observation that the number of emitted fast ions was intensity independent. The usual ponderomotive or relativistic self-focusing theory and related processes could not explain the results. Instead a direct interaction within the skin depth of the irradiated target was concluded. This model confirms the plane geometry nonlinear force interaction in the ps range producing fast plasma blocks moving perpendicular off or into the target. The block moving into the target opens a new scheme of laser fusion by modifying the experiments of Norreys et al. The use of relatively low subrelativistic laser intensities for the new scheme of laser fusion is evaluated on the background of the long years studies of nonlinear force driven plasma blocks and earlier interpenetration fusion reactions for providing the parameters for expected fusion gains much higher than the experiment of Norreys et al. for a fusion power scheme.     

Scalar and axial-vector mesons

Almost thirty years ago, Penny G. Estabrooks asked “Where and what are the scalar mesons?” (P. Estabrooks, Phys. Rev. D 19, 2678 (1979)). The first part of her question can now be confidently responded (E. van Beveren et al., Z. Phys. C 30, 615 (1986)). However, with respect to the “What” many puzzles remain unanswered. Scalar and axial-vector mesons form part of a large family of mesons. Consequently, though it is useful to pay them some extra attention, there is no point in discussing them as isolated phenomena. The particularity of structures in the scattering of --basically-- pions and kaons with zero angular momentum is the absence of the centrifugal barrier, which allows us to “see” strong interactions at short distances. Experimentally observed differences and similarities between scalar and axial-vector mesons on the one hand, and other mesons on the other hand, are very instructive for further studies. Nowadays, there exists an abundance of theoretical approaches towards the mesonic spectrum, ranging from confinement models of all kinds, i.e., glueballs, and quark-antiquark, multiquark and hybrid configurations, to models in which only mesonic degrees of freedom are taken into account. Nature seems to come out somewhere in the middle, neither preferring pure bound states, nor effective meson-meson physics with only coupling constants and possibly form factors. As a matter of fact, apart from a few exceptions, like pions and kaons, Nature does not allow us to study mesonic bound states of any kind, which is equivalent to saying that such states do not really exist. Hence, instead of extrapolating from pions and kaons to the remainder of the meson family, it is more democratic to consider pions and kaons mesonic resonances that happen to come out below the lowest threshold for strong decay. Nevertheless, confinement is an important ingredient for understanding the many regularities observed in mesonic spectra. Therefore, excluding quark degrees of freedom is also not the most obvious way of describing mesons in general, and scalars and axial-vectors in particular.     

Flat-top interleavers with chromatic dispersion compensator based on phase dispersive free space Mach-Zehnder interferometer

In this paper, novel interleavers using circular cavities (CC) in a Mach-Zehnder interferometer (MZI) has been presented and demonstrated for the first time, in which CCs act as phase dispersive mirrors which exhibit a periodic dependence on the frequency of light. Three implementation schemes have been proposed and investigated. Theoretical analysis shows the spectral characteristics of each scheme in a 50-GHz channel spacing application. Furthermore, the chromatic dispersion (CD) of each output comb can be flattened within passband by appending an additional CC. The result shows that the proposed designs with novel interferometer technique can simultaneously provide flat top passbands, high isolation stopband and low CD value as well.     

Comparative Study on Large and Small Signal Theory for Intensity Modulation Response of Semiconductor Lasers Including Higher-Order Dispersion Terms

In this article, the comparison of large signal theory and small signal theory has been done with dispersive propagation of optical signal with IMDD (Intensity Modulation Direct Detection) systems for semiconductor lasers with higher-order dispersion terms. The expressions for an exact large signal theory and small signal theory including higher-order dispersion terms for propagation of an optical wave with sinusoidal amplitude and frequency modulation in a dispersive fiber have been derived. It is observed that small signal theory is more sensitive compared to large signal theory in terms of intensity modulation/direct detection systems. Also, it is reported that for large signal analysis the higher-order effects of dispersion can be ignored, whereas for small signal theory, the higher-order effects can be ignored for lower modulation frequencies only. The variation in the transfer function for various values of modulation indices are greater for small signal analysis than for large signal analysis. Also, as the intensity modulation index is increased, there is a decrease in the value of transfer function. The large signal model approximates the small signal model for lower values of the intensity modulation index.     

光束偏转法自动测试激光等离子体冲击波系统的研制

根据光束偏转原理，研制了激光等离子体冲击波自动测试系统的硬件和软件。该系统使用计算机与可编程序控制器作为上下位机，采取上下位机通讯的方式控制步进电机及二维移动架的移动，以改变探测光的相对位置，并利用单模光纤和光电倍增管将探测到的光偏转信号传入数字示波器进行存储，最后计算机将示波器中采集到的光偏转信号进行分析处理。使用该系统对激光等离子冲击波的衰减过程进行了实际测试，得到了较为理想的实验结果。