部分相干光栅衍射效应和干涉术

本文提出一种新的部分相干照明的光栅衍射干涉仪.先分析了光栅的介于Talbot和Lan效应之间的部分相干衍射效应.部分相干干涉图的特点是条纹由频率成倍的两种光栅状载波所表征.调整光源狭缝,系统在两相干性极端分别转成Talbot和Lau干涉仪.理论分析采用了模糊函数方法.最后给出了实验.     

扩展白光编码栅谱衍射干涉仪:理论

本文提出了一种新型的扩展白光光栅衍射干涉仪.系统中两块编码光栅用透镜互相成倒像,被测物置于其间并且也用透镜成像于观察屏上.物体的任一像点的强度决定于编码光栅傅里叶谱分布经过的相应的部分物体中的相位变化,由于色散从而得到带有彩色的干涉图.干涉形式可以用不同图案的编码栅来调换.系统用菲涅耳近似衍射理论进行了分析,导出了一般性结果,研究了编码栅形状,傅里叶变换谱和干涉形式之间的关系.最后给出了实验.     

平面物体的Lau效应理论

本文提出了任何平面物体的扩展Lau效应的新概念,相应提出了离轴光学博里叶变换系统的新的解释模型,导出了产生Lau效应的必要事件,也完整分析了光栅Lau效应,其中扩展了光栅的Frsenel成像条件.     

平面周期物体的Lau效应

基于部分相干理论中交叉谱密度函数的概念研究了平面周期物体的Lan效应文章导出了平面物体Lau像光强分布式,求得了平面周期物体的Lau像光强分布及其Lau成像条件,并进行了实验验证,给出了实验结果.     

模糊函数和任何光学系统中的Talbot-Lau效应

本文用模糊函数处理了光栅的Talbot和Lau效应,并推广到任何光学系统中。得到了十分简洁的通用表达式,它能够直接描述干涉条纹的空间分布,并只与系统的传递矩阵有关。同时也讨论了Talbot和Lau效应中的相位关系。     

反向脉冲传递法——扩展白光干涉现象研究 (Ⅰ)扩展白光成像于涉仪

本文提出反向脉冲传递法的光学系统分析方法,并讨论扩展白光照明下的干涉现象,优点是数学分析简单,物理意义明确和能作为一种统一的观点。 借助于反向脉冲传递,本文提出了扩展白光干涉仪的一般性模型,讨论了产生干涉的分束和补偿光学元件必须满足的分束复合条件,导出了干涉强度的一般表达式,结论是像点光场正比于物面反向脉冲响应的平方对物体的积分。同时,还分析了振幅分束,偏振分束和编码栅衍射分束等几种干涉仪。也讨论了白光色散效应。     

编码板照相干涉法

通常光学干涉仪是基于双(多)光束干涉原理,而全息干涉仪是基于两次曝光的全息图再现时的衍射干涉效应,都应用了光波干涉原理.它们的测量是以波长为尺度的,因此对于强变化位相体本身的位相变化是无能为力的.本文提出一种不同于位相相干的方法,即非相干光的编码板照相剪切干涉法.     

分波前干涉法中空间互相关函数的传输

 在光学干涉技术中,被检信息主要包含在干涉波面的互相关函数中,并最终体现为干涉场强度分布的调制。由Fresnel衍射理论出发,运用Collins公式,分析了分波前干涉法中空间互相关函数的传递性质。得到了用光线矩阵元表示的空间互相关函数传输公式,并以此对迈克耳逊干涉仪和横向剪切干涉仪中的干涉图强度分布进行了分析。     

点衍射干涉检测技术

本文介绍了点衍射干涉仪不同发展阶段的特点和应用。点衍射干涉仪由波长量级的针孔产生高质量的球面波作为参考波前,能够得到衍射极限性能的分辨率。按照不同的光路特点,点衍射干涉仪可分为点衍射共路干涉和点衍射非共路干涉两种结构,主要应用于高精度波前检测和面形检测。共路干涉结构简单紧凑,对环境振动不敏感,对光源相干度要求不高,可利用光束偏振态及光栅衍射分束的特性对传统点衍射板进行改造,在全共路点衍射干涉仪中引入时间相位调制技术和干涉对比度可调技术,可进一步提高波前检测精度。采用反射式针孔和各种光纤结构发展了非共路点衍射干涉仪,实现了大口径、高精度球面反射镜面形的测量。本文重点阐述了用于极紫外光刻投影物镜中高精度球面反射镜面形检测的反射式针孔点衍射干涉仪,并展望了点衍射检测技术在生物检测等领域的应用前景和发展趋势。     

波前编码系统成像特性的空间域分析

波前编码技术在大幅度地增加光学系统景深的同时,可以抑制各种离焦类型的像差。目前波前编码系统的成像特性分析大多是基于空间频率域的分析,在应用稳定相法导出三次型相位板波前编码系统的点扩展函数近似解析式的基础之上,描述了点扩展函数的边界、带宽与振荡等特性,分析了波前编码系统对离焦、像散、彗差等常见像差的敏感性,从空间域进一步分析了波前编码系统的成像特性。     

Decoherence in a Talbot–Lau interferometer: the influence of molecular scattering

This work describes the interference of C₇₀ fullerenes in a Talbot–Lau interferometer with a large separation between the diffraction gratings. This permits the observation of recurrences of the interference contrast both as a function of the de Broglie wavelength and in dependence of the interaction of background gases. An exponential decrease of the fringe visibility with increasing background pressure was observed and good quantitative agreement with the predictions of decoherence theory was found. From extrapolation of the limits of matter wave interferometry it can be concluded that the influence of collisional decoherence may be well under control in future experiments with proteins and even larger objects. PACS 03.75.-b; 03.65.Yz; 39.20.+q     

Double-image encryption based on joint transform correlation and phase-shifting interferometry

An image encryption method combining the joint transform correlator (JTC) architecture with phaseshifting interferometry to realize double random-phase encoding is proposed. The encrypted field and the decrypting key are registered as holograms by phase-shifting interferometry. This method can encrypt two images simultaneously to improve the encryption efficiency of the methods based on JTC architecture, and eliminate the system alignment constraint of the methods based on Mach-Zehnder interferometer (MZI)architecture. Its feasibility and validity are verified by computer simulations. Moreover, image encryption and decryption can be achieved at high speed optically or digitally. The encrypted data are suitable for Internet transmission.     

Die Temperaturabhängigkeit des magnetischen Barkhauseneffekts

A theory of the interference mechanism in the Laue case interferometer is presented. Owing to the strong Borrmann effect a straightforward plane wave approach yields complete agreement with observed fringe patterns. The problem of coherence is discussed in some detail. It is shown that the geometrical precision of actual interferometers does not have to be better than 1 to 10 micron. The theory demonstrates that the “ideal” geometry can also be obtained with the transmission mirrors in different planes, allowing the construction of a modified interferometer with especially long and separated beam paths. This type is particularly suitable for practical interferometry.     

软X射线双频光栅剪切干涉法研究

本文中设计了一种利用软X射线双频光栅作为剪切干涉元件的剪切系统, 使剪切干涉法在软X射线波段得到了应用. 介绍了软X射线双频光栅的结构及衍射特性, 在同步辐射光束线对双频光栅的效率分布进行了测试实验, 两个剪切级次的效率比值高于75%, 干扰级次效率低于5%. 利用软X射线双频光栅为剪切干涉光学元件, 对待测靶进行了静态检测, 得到了对比度高, 稳定的干涉条纹, 验证了该方法在软X射线等离子体密度诊断中的可行性. 关键词： 双频光栅 剪切干涉仪 软X射线 等离子体诊断     

Ultra low head–disk spacing measurement using dual beam polarisation interferometry

In this paper, a dual-beam normal incidence polarisation interferometer is proposed to measure the flying height or head–disk spacing. Using this interferometer, the head–disk spacing can be measured both in magnetic real disk condition and in glass disk condition. It has the advantage of both the currently popular intensity interferometry method and the oblique incidence polarisation interferometry method. With this polarisation interferometer, not only the flying height can be measured down to contact without losing accuracy, but the pitch and roll of the head-slider can also be detected dynamically. The optical parameters of the head-slider can also be determined. Design details and experimental study are presented.     

光栅成像与Lau效应

本文推导了两个光栅干涉仪的光强分布。分析了光栅周期与狭缝宽度比值对Lau条纹的影响。指出有β>p/(2a)的清晰的Lau条纹存在,并在数值计算与实验上加以证实。 关键词：     

Knife-edge diffraction pattern as an interference phenomenon: An experimental reality

This paper demonstrates that a knife-edge diffraction pattern is, indeed, due to the interference of two superimposing waves: the geometrical wave and the boundary diffraction wave. Within the framework of boundary diffraction wave theory it is shown that this diffraction pattern can easily be broadened in such a manner that a single fringe covers the whole field of view. At this point the system converges to a schlieren diffraction interferometer and could be used for the study of phase objects using diffraction-limited optics. Experimental observations show that the method bears a similarity to that of any known two-beam interferometer, e.g. Mach-Zehnder interferometer. The experimental details have been presented and the results are compared with a two-beam holographic interferometer and a point diffraction interferometer.     

Fourier optics analysis of grating sensors with tilt errors

Dynamic diffraction gratings can be microfabricated with precision and offer extremely sensitive displacement measurements and light intensity modulation. The effect of pure translation of the moving part of the grating on diffracted order intensities is well known. This study focuses on the parameters that limit the intensity and the contrast of the interference. The effects of grating duty cycle, mirror reflectivities, sensor tilt and detector size are investigated using Fourier optics theory and Gaussian beam optics. Analytical findings reveal that fringe visibility becomes <0.3 when the optical path variation exceeds half the wavelength within the grating interferometer. The fringe visibility can be compensated by monitoring the interfering portion of the diffracted order light only through detector size reduction in the expense of optical power. Experiments were conducted with a grating interferometer that resulted in an eightfold increase in fringe visibility with reduced detector size, which is in agreement with theory. Findings show that diffraction grating readout principle is not limited to translating sensors but also can be used for sensors with tilt or other deflection modes.     

Quantitative coherence analysis of dual phase grating x-ray interferometry with source grating

Dual phase grating x-ray interferometry is compatible with common imaging detectors,and abandons the use of an absorption analyzer grating to reduce the radiation dose.When using x-ray tubes,an absorbing source grating must be introduced into the dual phase grating interferometer.In order to attain a high fringe visibility,in this work we conduct a quantitative coherence analysis of dual phase grating interferometry to find how the source grating affects the fringe visibility.Theoretical analysis shows that with the generalized Lau condition satisfied,the fringe visibility is influenced by the duty cycle of the source grating and the transmission through the grating bar.And the influence of the source grating profile on the fringe visibility is independent of the phase grating type.Numerical results illustrate that the maximum achievable fringe visibility decreases significantly with increasing transmission in the grating bar.Under a given transmission,one can always find an optimal duty cycle to maximize the fringe visibility.These results can be used as general guidelines for designing and optimizing dual phase grating x-ray interferometers for potential applications.