Phase zone photon sieve

A novel diffractive optical element, named phase zone photon sieve (PZPS), is presented. There are three kinds of phase plates in PZPSs: PZPS1, PZPS2, and PZPS3. Each of the PZPSs has its own structure and is made on quartz substrate by etching. The three PZPSs have stronger diffraction peak intensity than a photon sieve (PS) when the margin pinhole and zone line width are kept the same. The PZPS3 can produce a smaller central diffractive spot than the ordinary PS with the same number of zones on the Fresnel zone plate. We have given the design method for and the simulation of PZPS and PS. PZPS has potential applications in optical maskless lithography.     

Photon sieve for reduction of the far-field diffraction spot size in the laser free-space communication system

In the free-space laser communication, there is sometimes a strong need for reduction of the diffraction spot size in the far field. In this paper, instead of the usage of the larger size aperture lens and super-resolution technology in the free-space laser communication system, we introduce photon sieve to compress the center spot in the diffractive far field, which can decrease the weight of the emitting lens. We have designed the photon sieve and calculated its far-field diffractive intensity. We have also calculated the far field Airy diffractive field intensity. Simulation proves that the photon sieve diffractive spot is smaller than the Airy spot with the same transmit aperture. We have set up an experimental system to simulate the far-field diffraction free-space laser communication. Experimental results are in good agreement with the theoretical results. Detailed experiments are presented.     

Design and application of phase photon sieve

The imaging principle of Fresnel zone plate and photon sieve were analyzed in this paper. The design and fabrication of phase photon sieve were discussed. The feasibility of using phase photon sieve to realize nano-lithography was analyzed, a novel lithography experiment system based on phase photon sieve was presented, which not only has higher resolution and image contrast than the Fresnel zone plate lithography but also have higher diffractive efficiency than the amplitude photon sieve lithography.     

A hybrid doubled achromat based on a photon sieve

Photon sieves are diffractive optical elements with large chromatic aberration. To correct the dispersion of a photon sieve, a novel hybrid doubled achromat combined a photon sieve and a refractive lens is proposed. The design of this achromat applies the opposite dispersive characteristics of diffractive and refractive elements. Two design examples for different bandwidths of 300 nm and 80 nm in visible spectrum are given. For analyzing their focusing properties, the intensity distributions both along the axis and at the focal plane are studied. The results illustrate that the achromatic design is achieved and the secondary spectrum can be corrected for a narrow bandwidth. And compared to traditional hybrid achromat, it can focus to a sharper spot.     

Focusing properties of a modified Fibonacci photon sieve

We propose a type of diffractive optical element, a modified Fibonacci photon sieve(MFiPS), designed by using the Fibonacci sequence with two different initial seed elements. Focusing properties of MFi PS show that it not only has less secondary foci, but also presents two equal intensity foci by optimizing the diameters of pinholes of MFi PS whose ratio of the two focal distances approaches the golden mean. Higher transverse resolution on the two focal spots is improved by using a super-Gaussian amplitude modulation technology.     

实现复消色差的超常温混合红外光学系统

讨论了利用二元光学元件实现红外光学系统消热差的原理和方法,分析了二元光学元件的色散特性及其在校正二级光谱中的优越性,给出了实现复消色差和超常温消热差的混合红外光学系统设计实例.该系统焦距100mm,相对孔径1/2,视场角6°,工作波段8—11μm;采用了两种最常用的硅和锗材料,共三片,结构简单.在-80—200℃的超宽温度范围内,成像质量稳定并达到衍射极限,约在系统0.7孔径处轴向像差曲线基本相交于一点,实现了系统的复消色差. 关键词： 红外光学系统设计 消热差 复消色差 折射/衍射混合光学系统     

Large optical photon sieve

A photon sieve with 10(7) holes has been constructed for operation at optical wavelengths. Details of the design, fabrication, and performance of this device are presented. The 1 m focal-length, 0.1 m diameter element is diffraction limited over a significant bandwidth and has a moderate field of view.     

A super-resolution Fresnel zone plate and photon sieve

Realizing a smaller or sharper diffractive center spot is a valuable research aim in soft X-ray focus and other related research applications. Fresnel zone plates (FZP) and photon sieves (PS) are often used to focus the X-rays or other wavelength light at present. Here, we show that combination of a super-resolution phase mask (SPM) and an FZP (or PS) as one diffractive optical element can realize a smaller or sharper diffractive center spot without significantly increasing the fabrication difficulty. All these diffractive phase elements can be applied to beam shaping, mask-less lithography, energy congregation in high power lasers, soft X-rays focus, and any other field that requires a smaller or sharper diffractive center spot.     

Toward two-dimensional nanometer resolution hard X-ray differential-interference-contrast imaging using modified photon sieves

In this Letter, we report a significant step forward in the design of single-optical-element optics for two-dimensional (2D) hard X-ray differential-interference-contrast (DIC) imaging based on modified photon sieves (MPSs). MPSs were obtained by a modified optic, i.e., combining two overlaid binary gratings and a photon sieve through two logical XOR operations. The superior performance of MPSs was demonstrated. Compared to Fresnel zone plates-based DIC diffractive optical elements (DOEs), which help to improve contrast only in one direction, MPSs can provide better resolution and 2D DIC imaging. Compared to normal photon sieves, MPSs are capable of imaging at a significantly higher image contrast. We anticipate that MPSs can provide a complementary and versatile high-resolution nondestructive imaging tool for ultra-large-scale integrated circuits at 45 nm node and below.     

卢卡斯光子筛的聚焦特性研究

介绍了一种基于卢卡斯数编码设计的轴上四焦点光子筛,其各焦距分布与黄金分割比密切相关.实验上利用相移数字全息验证了设计器件具有轴上四焦点聚焦特性,测量结果表明:轴向焦距和横向焦斑光强分布与理论设计值一致.该振幅型光子筛具有体积小、重量轻、易加工等优点,可应用于X波段显微和生物细胞阵列成像等领域.     

Data preparation and fabrication of DOE using electron-beam lithography

The application of electron-beam lithography to the generation of diffractive optical elements topology is examined. The formula for the estimation of exposure data volume for variable-shaped electron-beam lithography is presented as a function of diffractive optical element parameters and approximation accuracy. A special software dedicated to preparing exposure data for fabrication of diffractive optical elements is developed. Diffractive optical elements with an artificial refractive index are manufactured with a feature size much less than the wavelength. Design and experimental results on photomasks fabrication for an optical element focusing radiation into a ring with pregiven parameters are presented. The photomask set is manufactured for a reflecting optical element focusing the high power CO₂ laser beam into two points with required parameters for laser welding.     

X射线相衬成像光子筛

基于 Zernike相衬成像原理和光瞳切趾原理,提出一种将相位板和切趾光子筛集成为一个相衬显微物镜的 X射线相衬成像光子筛的设计方法.这种 X射线相衬成像物镜可以实现生物体组织或者其他弱吸收材料的高分辨率和高衬度成像.通过优化光子筛透镜的衍射结构,可以抑制成像系统的点扩展函数的旁瓣和消除高阶衍射焦点,从而提高成像分辨率;另外,将光子筛透镜和变相板合为一体,克服了成像透镜和变相板难以对准的缺陷.以高斯切趾光子筛为例,实验验证了设计方法的可行性. 关键词： X射线显微技术 相衬成像 光瞳切趾 光子筛     

Design of a diffractive optical element for wide spectral bandwidth

A new method for eliminating the chromatic aberration of a diffractive optical element (DOE) for wideband wavelengths is presented. The wideband-wavelength diffractive optical element (WBDOE) consists of two aligned DOE's. The use of different dispersive materials for the two DOE's eliminates chromatic aberration. The design and simulation of a WBDOE for the visible spectrum are presented.     

Zernike apodized photon sieves for high-resolution phase-contrast x-ray microscopy

We present a type of diffractive lens, Zernike apodized photon sieves (ZAPS), used as the objective for high spatial resolution and high phase-contrast imaging of weakly absorbing materials in x rays. The structure of ZAPS is based on the combination of two concepts: apodized photon sieves and Zernike phase contrast. The ZAPS is a single optic that integrates the appropriate ±π/2 rad phase shift through selective zone placement shifts in an apodized photon sieve. Analysis of the focusing properties of the apodized photon sieve in terms of point-spread function show that the sidelobes have been significantly suppressed at the expense of slightly widening the width of the main lobe. In combination with synchrotron light sources, ZAPS offers new opportunities for high-resolution phase-contrast x-ray microscopy in the physical and life sciences.     

折衍射混合复消色差望远物镜中的色球差

一个正透镜、一个负透镜及一个衍射光学元件以不同的组合可以构成两种折衍射混合光学系统.当这两种系统消球差、彗差及复消色差后会产生不同的色球差.通过赛德尔像差理论,分析了这两种结构产生不同色球差的原因.计算表明当衍射光学元件以负透镜的平面为基底时产生的色球差为以正透镜的平面为基底时产生的色球差的7倍.对衍射光学元件以负透镜的平面为基底的情形,提出了减小系统色球差的解决办法,使系统色球差减小到0.307 mm.另外设计了一个传统复消色差光学系统,并和折衍射混合光学系统进行了比较,分析表明,衍射光学元件可代替传统光学系统中的特殊光学材料并使系统达到相同的成像质量.最后讨论了衍射光学元件的衍射效率对系统成像质量的影响.     

双波长共焦衍射光学元件分析与设计

报道二维纯位相环带衍射光学透镜的研究。结果表明，在确定位置的像平面的光强分布呈现相当理想的光聚焦作用；同时以１．０６μｍ和０．６３２８μｍ两种波长为例，对双波长二维成像的环带衍射透镜进行分析计算，结果表明二种波长的光束都能聚焦于同一像平面。这种元件可方便地用于非可见激光中的对焦与光路调整。     

折/衍混合LWIR凝视成像系统的杂散光分析

本文对一折/衍混合长波红外(LWIR)凝视成像系统进行了杂散光分析,在此LWIR系统中,含有一个用金刚石车削技术制作的衍射光学元件(DOE)。本文中,对DOE的不同衍射级次、光学表面的多次反射、镜筒内壁的反射等主要杂散光源利用LightTools软件进行了分析,对6种二次反射的模拟结果表明,对归一化的光源,理想光路的像面辐照度为100 W/mm2,每种二次反射会给像面带来0.01W/mm2的辐照度;对于反射率为10％的镜筒内壁,带来的像面辐照为0.01W/mm2。并利用该LWIR凝视成像光学系统进行了相关实验,实验结果证明了上述分析的正确性,有利于对LWIR凝视成像系统光学性能的进一步理解和杂散光的抑制。     

Nanostructured gradient-index antireflection diffractive optics

We describe the fabrication and characterization of a nanostructured diffractive element with near-zero reflection losses. In this element, subwavelength nanostructures emulating adiabatic index matching are integrated on the surface of a diffractive microstructure to suppress reflected diffraction orders. The fabricated silicon grating exhibits reflected efficiencies that are suppressed by 2 orders of magnitude over broad wavelength bands and wide incident angles. Theoretical models of the fabricated structure based on rigorous coupled-wave analysis and effective medium theory are in agreement with the experimental data. The proposed principles can be applied to improve the performance of any diffractive structures, potentially leading to more efficient Fresnel lenses, holographic elements, and integrated optical systems.     

The efficiency of relief-phase diffractive elements at a small number of Fresnel zones

A technique and investigation results are presented on the effect of the number of Fresnel zones on the diffraction efficiency and quality of the wave front formed by a diffractive optical element. Equations are presented for the microstructure reliefs of diffractive optical elements making (regardless of the number of Fresnel zones) the wavefront shape coinciding with the calculated one and ensuring 100% diffraction efficiency at a single wavelength and, in the case of two-layer structures, almost 100% diffraction efficiency in a wide spectral range.     

含双层衍射元件消热差长波红外光学系统设计

采用多层衍射元件是实现宽波段高衍射效率的有效方法,设计了一个含双层衍射元件-30℃～70℃消热差系统。通过合理选择衍射面的基底材料,优化衍射表面的浮雕深度,设计出红外宽波段高衍射效率的消热差光学系统。设计结果表明,在整个设计温度范围内,该光学系统成像质量良好,光学传递函数在16lp/mm时均在0.6以上。