拍摄脉冲全息肖象母版的研究

本文介绍了我们在拍摄脉冲全息肖象母版方面的研究工作.讨论了拍摄工作中所需要特别注意的若干问题.如:人眼安全、对易律失效、消除双频条纹、如何获得高亮度图象等问题.此外,还介绍了我们拍摄脉冲全息母版时,在未使用Q开关的情况下,同样获得了高质量全息肖象母版的经验.     

体积全息衍射效率的分析

本文指出对于通过折射率变化来实现相位调制的全息图(无论是漂白后的银盐干版,或DCG版),在通常情况下其相位调制度都较小,不可能发生过调制现象,故拍摄参数选择范围相对较宽。要获得高衍射效率全息照片的关健应放在如何提高干涉项引起的相位调制折射率n₁上。本文还指出当反射全息处於弱布喇格衍射的情况下,再现图象的单色性下降,并存在透射象。     

级联马赫-曾德尔干涉仪光学梳状滤波的理论研究

提出一种级联马赫-曾德尔光纤进一步仪，它是采用多个3dB耦合器串联而成的。模拟与分析表明，当光纤进一步臂长度差ΔL按顺序取一系列定值时，将得到性能良好的梳状出射谱图。其进一步峰的边模抑制比随干涉臂数目的增多而变大。     

用实时全息术研究低速变化过程的一种简易系统

研制了一种用于研究物体低速过程的简易系统，它由带有液门原位化学处理的实时全息干涉装置和具有连拍功能的相机以及一台氦氮激光器组成，是一种简易实用的“低速、实时全息干涉摄影系统”。用它记录了火箭推进剂样品在室温，常压下的燃烧过程，１００瓦普通只灯逐级加压的点燃过程，对实时全息图的记录和处理采用了一种可获得高反衬度的新技术，拍摄的成功率高，干涉条纹的反衬度好，它为研究物体的低速变化过程提供了一种有力的手     

全息检测中的焦散线现象与干涉条纹的关系

在实时全息干涉计量实验中，当试件负荷甚大时，干涉条纹中会出现一些阴影区，它们在试件破裂过程中起重要作用。当负荷接近试件断裂强度时，可清晰看到并记录下阴影区的延伸、分叉、扩展直至试件破裂的过程。这些阴影区实际上就是几何光学中的焦散线现象。应用此现象可以计算应力强度因子。介绍了在寻找全息干涉条纹与应力强度因子之间关系所作的研究，导出了干涉条纹最大值与应力强度因子之间的定量关系式。从而，为使用全息法与焦散线法相结合的检测方法提供了定量计算的基础。     

Existence of travelling wavefronts of the KdV–Burgers equation

In this letter, we study the existence of travelling wavefronts of the KdV–Burgers equation from a monotone dynamical systems point of view. For any constant wave velocity, we obtain a sufficient condition for the existence. The conditions under which some exact travelling wavefronts have been found are special cases of ours.     

Photoinduced Bergman cycloaromatization of imidazole-fused enediynes

A series of 4,5-bis-(alkyn-1-yl)imidazoles—‘imidazole-fused’ enediynes—were synthesized and their reactivities in photoinduced Bergman cycloaromatization reactions were determined. The more conformationally rigid analogues gave cycloaromatized products in good yields upon irradiation (450 W low-pressure mercury lamp, ambient temperature). A bicyclic analogue (3) was shown to cleave supercoiled plasmid DNA.     

Measurement of long-range 1H-1H dipolar couplings in weakly aligned proteins

Measurement of 1H-1H dipolar couplings in macromolecules, weakly oriented by a dilute liquid crystalline medium, is generally limited to the largest such interactions. By removing dipolar couplings to nearest neighbors, either by decoupling, deuteration, or both, more remote interactions become accessible. The approach is demonstrated for measurement of amide-amide interactions in the proteins calmodulin and ubiquitin and permits observation of direct dipolar couplings between protons up to 7 A apart. Quantitative evaluation of 1H-1H dipolar couplings measured in ubiquitin shows excellent agreement with its solution structure.