共查询到20条相似文献,搜索用时 31 毫秒
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A two-exposure nearly common-path point diffraction interferometric phase microscopy (IPM) is presented using polarization modulation and one-step grating shifting to implement quantitative phase imaging. The IPM is constructed by an improved Michelson configuration with a reflective grating, and its frequency spectrum generated by a circularly polarized object beam makes double copies through a beam splitter. One copy is low-pass filtered and reflected by a reflective pinhole mirror to create a reference beam, and the other copy is converted by a polarizer and then reflected by a reflective grating to achieve a 45° linearly polarized object beam. By the combination of a polarizing cube beam splitter with 45° tilted angle and a translation of the reflective grating with a π phase shift, four interferograms with π/2 phase shift can be obtained in two exposures. The standard four-step algorithm can then be used to reconstruct the phase of the specimen. The utility of the proposed method was demonstrated with measurements on a phase plate, cells and an oil drop. 相似文献
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等离子体激元(surface plasmon polaritons, SPP)因其独特的光学和物理特性, 使其具有诸如透射增强和局域共振等一系列新颖现象, 已成为当前国内外学者研究的热点. 本文对基于类表面等离子体激元(Spoof Surface Plasmons, SSP)的矩形金属光栅色散特性和模式分布进行了研究. 利用本征函数法并结合场匹配条件, 获得了矩形栅表面SSP的场表达式、色散关系和模式分布, 并通过电磁仿真进行了验证. 在此基础上分析了矩形栅各参数对SSP色散及模式分布的影响, 研究结果表明: 由本征函数法获得的SSP色散特性与仿真结果基本符合; 增大金属栅高度或减小排列周期能减小SSP的相速度; 而增大金属栅周期占空比能在一定程度上拓展SSP与电子束互作用的带宽; 改变金属盖板高度对慢波SSP色散模式基本没有影响; 减小金属栅侧面宽度能增大模式之间的间隔, 从而能有效避免模式竞争的发生. 本文对基于SSP的矩形金属光栅色散特性的研究将为进一步研究SSP与电子束的相互作用, 形成高效、宽带的新型太赫兹源奠定良好的理论基础. 相似文献
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Shun-ichi Tanaka Sanshiro Hattori Joon-Sung Chang Masana Minami 《Optics Communications》1973,9(1):54-57
A multiple object-beam holography is proposed, where a two-dimensional rectangular amplitude grating and a phase plate of matrix form placed at the frequency plane of the grating constitute the main parts of a speckle-free periodic illumination system of continuous tone transparencies. Demonstration experiments are made, where the number of diffracted orders of the grating, the ratio of the widths of transparent and opaque zones of the grating, the retardation of each matrix zone of the phase plate and the distance between planes of the image of the grating and a transparency are taken as variables. 相似文献
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The boundary-value problem of the reflection and transmission of light by a composite structure, wherein a surface-relief dielectric grating is coupled to a structurally chiral volume grating, has been formulated and solved with results showing the robust co-existence of phenomena characteristic of both types of grating: namely, Rayleigh–Wood anomalies and Bragg phenomena. A mechanism to strengthen the coupling between both grating types is included – namely, a quarter wave plate – whose birefringence converts normally incident linearly polarised light at the Bragg wavelength into transmitted circularly polarised light (and vice versa). It is possible to tailor the period of the sinusoidally corrugated surface-relief grating such that the scattering of obliquely incident light from above, by the surface grating, will lead to a specific non-specular order being scattered onto a path which is normally incident on the rest of the composite structure. Significantly, such orders exhibit the circular Bragg phenomenon in reflection and transmission only if both grating types are present, making this a “truly” coupled effect. 相似文献
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中阶梯光栅是一种特殊的衍射光栅, 它以高的衍射级次和大的衍射角来工作, 具有高分辨率、全波闪耀等特性。已广泛应用于高端光谱仪器之中,极大地促进了航天航空、天文、医疗、军事、环境等尖端科技的发展。但是专业的刻划系统需要定制,价格昂贵。使用已成熟的超精密加工设备来加工中阶梯光栅,可以大大降低中阶梯光栅母版的制备成本。超精密单点金刚石车床制备中阶梯光栅时,系统直线度不好,存在较大的累积误差,导致中阶梯光栅衍射波前较差,达不到制备要求。为了减小超精密单点金刚石车床固有的直线度误差,对超精密单点金刚石车床进行了误差补偿。首先,以累积误差曲线为依据进行第一次补偿。实验结果表明,当补偿系数为0.75~0.85时,此时衍射波前的PV(峰谷值)值在约400 nm,一次直线度补偿效果到达极限。然后,以闪耀级的衍射波前曲线为依据进行第二次直线度补偿,二次补偿后的衍射波前PV值为约83 nm。补偿后的结果表明衍射波前得到大幅改善,有利于提高所制备光栅的质量,在光栅实际刻划中具有指导作用。 相似文献
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针对传统方法难以制作结构光三维投影测量设备的灰度正弦光栅元件,并以Ronchi光栅代替从而影响测量准确度,提出了一种制作灰度按正弦分布的光栅模板的新方法.通过对银盐全息干板透过率特性曲线的理论分析,指出在对比度为一的正弦干涉条纹下曝光不能得到线性记录和变换的原因,并提出了采用均匀非相干光预曝光提供偏置点来实现线性记录的新方法.实验表明,采用空间滤波法能够获得对称双光束正弦干涉条纹记录,并准确控制正弦干涉条纹曝光在干板的线性区域,可以达到线性记录并获得尽可能高的反衬度. 相似文献
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全息照相实验的新思路 总被引:3,自引:0,他引:3
在全息照相实验中,增加两种拍摄全息光栅的光路,在一张全息底片上,经过三次曝光,拍摄一幅全息图和两种光栅常量值的全息光栅,可使学生深刻地理解一张全息底片能够记录多个不同信息的原理。 相似文献
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We propose and experimentally demonstrate long-distance remote simultaneous measurement of strain and temperature based on a Raman fiber laser with a single fiber Bragg grating embedded on a quartz plate. A Raman fiber laser output with a high extinction ratio of more than approximately 50 dB is achieved by the fiber grating cavity. In the sensing probe, half of the fiber Bragg grating is fixed steadily on the quartz plate to respond to temperature only, while the other half of the grating is free to respond to both temperature and strain. Based on the proposed scheme, lasing wavelength shift and separation occur with temperature and strain change, respectively. Efficient simultaneous measurement of strain and temperature for long-distance sensing applications of more than 50 km is readily obtained. 相似文献
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This paper tries to introduce the reader to the method of using photochemical re-action to copy holographic optical elements(HOEs)in relief.The holographic blazing gratingso copied is groove depth adjustable phase modulability enlarged through copying and 3.3times the diffraction efficiency(DE)of the original grating.It is expected that the newmethod will lead to the mass production of the light-weight HOEs at low cost. 相似文献
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In this paper we introduce a new phase type combined optical element. The element is combined with Dammann grating and Fresnel zone plate in the same substrate by microelectronics technique, hence it has splitting functions of the Dammann grating and self-focusing function of the Fresnel plate. It can produce uniform multiple images by itself. We experimentally designed and fabricated an 9x9 multiple image element, and results show that the element can realize the multiple images we require and the intensity of each image is the same. Relative error is less than 5%. 相似文献
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A. Wirgin 《Optics Communications》1978,26(2):153-157
It is shown that a large fraction of the energy of the impinging light beam on a parallel plate grating can be injected into only one transmitted order, which is not the zeroth transmitted order, when the incident angle of the beam and the refractive indices of the lossless dielectric bounding media satisfy the condition of total reflection. This signififies that non-redundant scanning of the radiation transmitted through the grafting can be obtained by varying the frequency of the incident radiation with little of the incident energy being scattered into the reflected orders. 相似文献
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We present a method for metal coating optical fiber and in-fiber Bragg grating. The technology process which is based on electroless plating and electroplating method is described in detail. The fiber is firstly coated with a thin copper or nickel plate with electroless plating method. Then, a thicker nickel plate is coated on the surface of the conductive layer. Under the optimum conditions, the surfaces of chemical plating and electroplating coatings are all smooth and compact. There is no visible defect found in the cross-section. Using this two-step metallization method, the in-fiber Bragg grating can be well protected and its thermal sensitivity can be enhanced. After the metallization process, the fiber sensor is successfully embedded in the 42CrMo steel by brazing method. Thus a smart metal structure is achieved. The embedding results show that the plating method for metallization protection of in-fiber Bragg grating is effective. 相似文献
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K. Patorski 《Optics & Laser Technology》1984,16(1):45-48
A simple technique of optical differentiation of displacement patterns is proposed. It utilizes a single copy of a distorted diffraction grating and a plane mirror. The principle of operation, together with experimental results and the comparison with previously described differentiation methods are given. 相似文献
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The reflection grating method is a special case of the well-known reflection moiré principle. Whereas this moiré effect is suitable for measurement of the slope and curvature of deformed object surfaces by superposition of at least two grating images, the same results can be determined using only one reflected grating image without moiré lines.Some fundamental relationships between grating lines, optical setup and the desired deformation are developed and compared with the simplifications that are known from the moiré principle. The theory is tested using a circular plate, uniformly loaded and clamped at the circumference. 相似文献