双光栅切换微型平场全息凹面光栅光谱仪

基于CCD的微型平场全息凹面光栅光谱仪,以其简单紧凑的结构和快速高效的工作方式在光谱分析领域获得了广泛的应用。但是,由于受限于色散距离,单纯依靠优化光栅像差很难进一步使光谱分辨率获得大幅提高。提出一种双光栅切换微型平场全息凹面光栅光谱仪的设计方法,用两个使用结构相同的光栅代替传统的单光栅设计,给出一个光谱范围为400～1000nm光谱仪的具体设计,计算显示光谱分辨率最大可提高为原来的2.5倍。通过对光栅衍射效率的计算分析,说明此方法能够显著改善仪器的通光效率。设计制作了原理样机,进行了装调测试,实验结果与理论计算相吻合。     

宽谱高分辨平场凹面全息光栅光谱仪设计

为了获得宽谱、高分辨的平场凹面全息光栅,将全息凹面光栅理论、遗传算法、衍射级次空间共用和同时消像差思想融合在一起,提出设计宽谱、高分辨平场凹面全息光栅的方法,给出了实际设计步骤。通过Zemax软件光线追迹仿真具体实例,给出了200～800nm波段的点列图变化曲线[均方根(RMS)约为11μm],以10μm×1mm狭缝入射,其光照度光谱图显示光谱分辨率在200～400nm波段为0.25nm,在400～800nm波段为0.5nm。该方法可以用于设计小型化、实用化的宽谱和高分辨平场凹面全息光栅光谱仪光学系统。     

软X射线全息平焦场光栅的条纹弯曲现象及其对光谱分辨率的影响

软X射线平焦场光栅光谱仪是等离子体诊断的重要仪器,其核心光学元件全息平焦场光栅通常采用非球面波记录光路制作,因此光栅条纹存在弯曲的现象.光栅条纹的弯曲会影响光谱成像质量,从而影响系统的光谱分辨率.记录光路的优化,只保证光栅子午面的线密度分布,因此优化的记录光路并不是惟一的,所以在保证子午面的线密度分布的同时能制作具有不同弯曲程度条纹的光栅.针对应用于0.8—6 nm的全息平焦场光栅,利用光线追迹方法分析了不同弯曲程度条纹光栅的光谱成像,发现采用柱面反射镜制作的接近于直条纹的光栅具有较好的光谱成像质量.相对于弯曲条纹的光栅,接近于直条纹的光栅理论光谱分辨率有明显的提高,入射波长为3 nm时,光谱分辨率从626提升到953,入射波长为5 nm时,光谱分辨率从635提高到1222.     

Design of aberration-corrected flat-field holographic concave grating by parameter optimization

Based on the aberration theory of concave grating [1], [2], [3], a method to design aberration-corrected flat-field holographic concave gratings by parameter optimization is introduced. And the influence of different parameters such as the incident angle, effective grating grooves and grating radii on the aberrations at diffracted order ?1 is discussed. The results indicate that for a concave grating working in a given spectral range, we can correct aberrations by optimizing the incident angle. In addition, flat-field holographic concave gratings with higher resolution and lower aberration can also be designed by choosing the effective grating grooves and larger grating radius properly.     

零像散宽波段平场全息凹面光栅的优化设计

平场全息凹面光栅的理想像面应为一平面,此时子午焦线与弧矢焦线均位于像面内且彼此重合,形成接近理想像点的光谱像。但子午焦线总是存在弯曲,只有弧矢焦线在满足一定条件的情况下可以成为直线。鉴于此,提出一种满足平场弧矢焦线条件的平场全息凹面光栅设计方法。利用光学设计软件ZEMAX研究了运用此方法设计的零像散光栅的成像特性,并与原有设计方法得到的结果进行比较。模拟结果显示,满足平场弧矢焦线条件的光栅能够达到与原有方法所设计光栅相当的光谱分辨率,而其全波段零像散特性使其拥有更加出色的弧矢方向聚焦性能,显著提高平场光谱仪的信噪比。     

中心波长为28.5nm多层膜镜反射率测量

在“星光-Ⅱ”装置上以类Ne铬x射线激光作为标定源，以平场光栅谱仪为分光元件进行了285nm的Mo/Si多层膜反射镜效率测量.介绍了实验方法，给出了实验结果，本次研制的两块多层膜镜反射率分别为31%和9.6%. 关键词： x射线多层膜反射镜 反射率测量 x射线激光     

Design, Fabrication and Test of a Soft X-Ray Even-Order Transmission Grating

Most transmission gratings in the x-ray region work with their first orders and dispersion is limited by the line density achievable with current fabrication technology. We present a novel design of a two-dimensional x-ray transmission grating. The grating works with higher dispersion using its second orders, and the influence from first and third orders can be suppressed. A grating according to the novel design is fabricated and its diffraction performance is tested in comparison with a traditional x-ray transmission grating with the same line density. The novel grating could be especially useful when high dispersion is desired while the fabrication of high-density gratings becomes more difficult.     

Quasi-sinusoidal single-order diffraction transmission grating used in x-ray spectroscopy

A novel design of quasi-sinusoidal single-order diffraction transmission grating (QSTG) is proposed, which can achieve a line density up to thousands line/millimeter as that of traditional transmission gratings with the current level of nanofabrication technique. We fabricate a 1000?line/mm QSTG using the new design approach, and display the calibration results of such QSTG on the soft x-ray beam of synchrotron radiation.     

掠入射平场光栅谱仪消级次重叠技术的实验研究

利用掠入射反射短波截止原理,成功地实现了平场光栅谱仪的无级次重叠摄谱.实验结果表明,利用该方法来消除平场光栅谱仪中短波长的高级谱对所考察波段的一级谱的影响是简便而有效的.实验获得了镁激光等离子体在4.4～5.6nm,5.9～11.8nm,7.0～14.0nm三个不同波段的近似的纯一级谱.     

Single-order soft x-ray spectra with spectroscopic photon sieve

A single-order diffraction transmission grating named spectroscopic photon sieve(SPS) for soft x-ray region is proposed and demonstrated in this paper. The SPS consists of many circular pinholes located randomly, and can realize both free-standing diffractions and the suppression of higher-order differations. In this paper, the basic concept, numerical simulations, and calibration results of a 1000-lines/mm SPS for soft x-ray synchrotron radiation are presented. As predicted by theoretical calculations, the calibration results of a 1000-lines/mm SPS verify that the higher-order diffractions can be significantly suppressed along the symmetry axis. With the current nanofabrication technique, the SPS can potentially have a higher line density, and can be widely used in synchrotron radiation, laser-induced plasma diagnostics, and astrophysics.     

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.     

A method to accurately control the period of subwavelength planar holographic grating in the fabrication process of guided mode resonance filter

Subwavelength optical element such as guided-mode resonance filter has gained much interest recently due to its properties and applications. It is very hard to fabricate an ideal guided-mode resonance filter with the same parameters as the designed one. The reason is that the resonance wavelength of guided-mode resonance filter is susceptible to the fabrication errors of its parameters, such as the period, the groove depth, the thickness of a guided-wave layer, and the refraction indexes of materials, etc. In this article, a method to accurately control the period of subwavelength planar holographic grating which was used as a sub-layer of the guided mode resonance filter is investigated. Results show that utilizing a convex lens placed in the exposure position can cause the adjusting of the period of subwavelength planar grating more convenient in the holographic optical path during the fabrication process. Accuracy controlling the period of grating which was used as the sub-layer of guided-mode resonance filter has great significance in the fabrication of guided-mode resonance filter.     

激光等离子体脉冲软X光标定源

 利用神光Ⅱ上激光与等离子体相互作用得到的软X光，建立了基于多层镜的四通道软X光单色器系统。研究了光源的性能，测量了光源强度、单色器系统稳定性、相应通道的一致性。研究表明，采用多层镜作为脉冲光源的分光元件，可以得到具有较好单色性的强脉冲软X 光标定源。光源的光子能量为253 eV和820 eV，两能道的光源强度分别为1.8×10¹⁹ photon/(s·cm²)和3.2×10¹⁹ photon/(s·cm²)。在该标定源上可以实现XRD、平面镜、多层镜、透射光栅和滤片的标定。     

Ray tracing method for the grazing incidence flat-field imaging soft X-ray spectrometer

A ray tracing method is introduced for helping adjustment and spectra analysis of the grazing incidence flat-field imaging soft X-ray spectrometer. For a single point source, the spectra images obtained by separate components, the toroidal mirror, and the grazing incidence flat-field concave grating with varied line spaces are given respectively. The calculated spectral images of the single point source by the spectrometer are also given for comparison with measurements with different experimental alignments.     

全息液晶/聚合物透射光栅光学各向异性的研究

基于聚合物支撑(polymer scaffolding)形貌的全息液晶/聚合物透射光栅, 系统研究了光栅的光学各向异性. 在这种形貌的光栅内, 液晶不是以液滴的形态存在于富液晶区, 据此建立了相应光栅的简化模型, 然后在各向异性耦合波理论框架下研究了光栅的衍射特性. 详尽的衍射效率实验值和计算值比较, 很好解释了液晶/聚合物光栅的光学各向异性, 也证实了液晶分子大致沿着光栅矢量排列.     

利用铌酸锂晶体制作体全息光栅的设计性实验

利用双光束干涉,通过控制双光束的记录角度,在铌酸锂晶体中写入光折变体全息布拉格光栅.将该光栅应用于光通信系统中作为滤波器使用,利用ASE光源和光谱仪对其进行测试,在1 548nm波长处获得了峰值半高全宽为4nm,衍射效率为10%的滤波效果.     

透射光栅谱仪的整体标定

 提出了透射光栅谱仪整体标定的建议,并在北京同步辐射源上首次对ICF实验中所用的透射光栅谱仪进行了整体标定, 获得了与分别标定基本一致的结果。与分别标定相比,整体标定具有实验步骤少、实验数据处理简单、标定结果使用更加直接等优点。     

光源线宽和色散对DWDM通信系统光纤光栅滤波器的码率限制

分析了DWDM系统中光纤光栅滤波器透射色散特性,光源线宽和光栅透射色散对啁啾高斯光脉冲的展宽及对通信系统码率的限制,在适当的参量条件下,对系统码率进行了计算;结果表明,在接近单色时,啁啾是限制码率的主要因素,在线宽较大时,线宽成为限制码率的主要因素,光栅长度的增长,也将制约码率.     

新型透射式全息窄带带阻滤光器的光谱特性分析

滤光器在光谱学、光学测量和激光物理中有着极其重要的应用。全息滤光器是一种新型滤光器,特别是利用重铬酸明胶(DCG)记录的全息透射式窄带滤光器,其主要特点为对主谱线有很窄的带宽。文章主要用紫外-可见分光光度计测定用DCG记录的透射式全息窄带带阻滤光器的光谱特性,测量结果分析表明,滤光器在可见光区域(400～800 nm)对其中心波长的相对透射率小于2%,其他谱线的相对透射率大于85%。且滤光器有较窄的带宽,其半宽度小于12 nm,十分之一宽度小于15 nm。对氩离子激光(Ar+)主谱线514.5 nm有优良的滤光特性。     

数字全息图的非同步采样对再现像的影响

基于香农采样定理和傅里叶频谱分析,通过模拟数字全息光栅的实验,对非同步采样数字全息图的一些基本问题进行了分析。模拟实验结果表明：全息图透射率函数中的低频调制现象随非同步采样光栅空间频率的增大而变得更明显;全息图再现过程中的频谱泄漏使再现波前发生高频起伏,其影响大小取决于非同步采样的偏离程度,与光栅本身的空间频率无关。另由数值模拟实验表明,频谱泄漏对再现波前的影响可通过数字全息图加窗切趾方法来抑制,以提高再现像质量。