Ar+离子束刻蚀制作凸面闪耀光栅

凸面闪耀光栅是研制高光谱分辨率超光谱成像系统的关键器件之一.由于要求的闪耀角度一般较小,制作工艺难度大,其衍射效率与理论值有较大差距,一直制约其应用.针对上述问题与难点进行了分析,通过光刻胶光栅掩模制作和Ar<'+>离子束刻蚀等工艺制作了凸面闪耀光栅.针对离子束大掠入射刻蚀凸球面时槽形闪耀角不易一致的难题,利用转动扫描...     

紫外光刻-湿法刻蚀硅中阶梯光栅的研制

湿法刻蚀技术作为中阶梯光栅的主要制备方法之一，具有制造成本低、周期短、杂光少、所制作光栅的闪耀角误差小等优点。为解决某高分辨率光谱仪在近红外波段（800～1100 nm）的分光需求，尝试选择70.52°槽顶角的湿法刻蚀硅中阶梯光栅来代替90°槽顶角的传统中阶梯光栅。依据（100）硅光栅的结构特点以及光学设计给出的光栅工作条件，利用有限元数值计算法求解电磁场分布，理论分析了硅中阶梯光栅在工作波段内多个级次的衍射特性。在此基础上，利用紫外光刻-湿法刻蚀技术，在单晶硅基底上制作了槽密度为42 lp/mm、闪耀角为54.74°、有效面积超过46 mm×28 mm的对称V形槽光栅，并根据制备实验结果分析讨论了工艺过程中硅光栅质量的重要影响因素。测试结果表明，该光栅在各工作级次对应闪耀波长下的衍射效率均在45%～55%范围内，满足指标要求。     

反应离子束微细加工全息闪耀光栅研究

本文报道以无透镜傅里叶全息术变换记录的全息光栅作掩膜,应用反应离子束入射角控制光栅闪耀角,选择了合适刻蚀工艺参数,制得衍射效率为67%的SiO_2全息闪耀光栅。     

空间调制干涉型和衍射光栅型成像光谱仪信噪比性能的分析比较

以Sagnac空间调制干涉型成像光谱仪和Offner凸面光栅衍射型成像光谱仪为例,着重分析和比较这两类成像光谱仪的信噪比性能。在相同观测条件下,通过推导这两类成像光谱仪所得到的图像像元的光谱辐亮度,指出空间调制干涉型成像光谱仪并不具有高通量和多路复用优势,信噪比也低于衍射光栅成像光谱仪。而且随着光谱谱段数的增加,即光谱分辨率的提高,衍射光栅成像光谱仪的信噪比优势更明显。     

光谱仪用平场凹面光栅的凸面母光栅的消像差设计思路

平场全息凹面光栅是光谱仪中的核心元件之一,其成像质量和衍射效率直接影响了光谱仪的分辨率和光能利用率。利用凸面母光栅复制制作凹面光栅,便于在凸面基底上进行离子束刻蚀以获得高的衍射效率。为了保证复制的凹面光栅具有高的成像质量,文章提出一种全息凸面光刻胶光栅的消像差设计方法,优化中考虑了凸面基底对记录光束的折射效应以及由基底折射率所引入的附加光程。通过将“光程函数级数展开法”和ZEMAX光学设计软件相结合,采用粗精两步优化的方法,显著提高了优化的效率和成功率。ZEMAX对比仿真结果显示,复制得到的凹面光栅与传统直接采用全息法制作的凹面光栅的成像质量是相当的。     

适用于宽带光的闪耀光栅衍射强度分布规律研究

变栅距光栅线位移传感器是一种新型波长编码位移传感器,为进一步提高传感器波长解调的精度和减小光源的体积,提出适用于全工作波段的恒定闪耀角变栅距光栅结构。首先采用经典光学的方法推导出变栅距闪耀光栅衍射强度分布公式,从理论上证明该光栅结构可实现在全工作波段提高变栅距光栅线位移传感器衍射光强。此外,制作出变栅距闪耀光栅样件证实了工艺可行性。在相同的条件下,对一组参数相同的闪耀光栅和矩形槽形光栅进行了衍射光强比对实验,得到变栅距闪耀光栅的衍射光强约为矩形变栅距光栅的衍射光强的1.7倍,并与按此衍射光强分布公式计算的结果一致。     

台阶光栅衍射的傅里叶分析

提出了一种台阶光栅模型 ,并应用傅里叶光学方法推导出了反射式衍射光强的表达式。分析计算了衍射光强随台阶数、入射波长、衍射角和轮廓角 (闪耀角 )的变化关系。结果表明 ,台阶光栅能起到闪耀作用 ,台阶对衍射强度分布有影响 ,但不改变衍射光极大值的位置 ,随台阶数的增加 ,能量逐渐向闪耀方向集中。当台阶数等于 8时 ,其衍射效率可接近三角形闪耀光栅的衍射。台阶光栅衍射的傅里叶分析对光栅制作有一定的指导意义     

基于全息光学元件的光纤光谱仪的光路设计

基于全息光学理论分析了全息光学元件的高斯成像性质,包括光焦度、成像位置、衍射效率以及作为光纤光谱仪光栅元件的可行性,并以全息光栅的成像理论以及光谱仪工作原理为基础,设计了光谱仪器光学系统的各个参数,通过Zemax软件的仿真、像质评价及优化,得出最终的参数和模拟结果。所使用的全息光栅记录波长为575 nm,记录光束之间的夹角为10,一束为平面波,一束为球面波,焦距40 mm,使用+1级衍射光,光栅孔径为10 mm。光谱仪的工作波长范围为400 nm～800 nm,体积140 mm*30 mm*40 mm,谱面展宽29.1 mm。通过在光学平台上搭建光路,利用已研发完成的电路系统及光谱仪软件,针对汞灯光谱进行了试验,光谱分辨率优于8 nm,测量得到的汞灯光谱与标准汞灯光谱一致,表明了所设计的基于全息元件的光纤光谱仪光学系统是可行的。     

成像光谱仪一体化设计

随着超光谱成像技术的发展,超光谱成像光谱仪的要求也随之提高,小型化、高光谱分辨率和高空间分辨率成为发展趋势,这就要求设计者在进行仪器设计的过程中不断完善和优化设计。提出了成像光谱仪一体化设计的方法,即不单纯地进行光谱仪分光系统的设计,而是将光谱仪分光系统置于整体结构中进行整体系统设计和优化,从而实现超光谱成像光谱仪的最佳设计结果,并以近年来应用较为广泛的凸面光栅成像光谱仪为例,较为详细地阐述了成像光谱仪一体化设计方法在系统研制过程中的应用,并通过对该凸面光栅成像光谱仪的测试验证了该方法的正确性。     

线偏光闪耀反射光栅衍射特性研究

通过数值方法对线偏光在Littrow装置中的理想导体闪耀光栅的偏振特性进行研究.用时域有限差分程序计算出任意偏振方向线偏光经过闪耀光栅衍射后的电磁场分布,提取衍射波的S偏振和P偏振分量,讨论了与光栅闪耀角和入射光波偏振角的关系.分析了在1530～1570nm光谱范围内,入射光波为线偏振波和园偏振波时,衍射光波的偏振色散特性与光栅闪耀角的关系,并给出了存在偏振色散的光栅闪耀角范围.这些分析和结果对工程设计具有一定的指导意义.     

Profiled hologram diffraction gratings based on As2Se3 inorganic photoresist

We devised a method of producing blaze hologram diffraction gratings by transforming symmetric grooves of the original grating into asymmetric ones using an additional oblique irradiation by monochromatic or polychromatic light and a repeated chemical etching of the additionally irradiated grating. Photosensitive As₂Se₃ film layers are used as a photoconductive material for recording gratings. A numerical computer modeling of the formation of asymmetric grooves is conducted. The calculated shape of the groove profile is in good agreement with experimental data. The manifestation of asymmetry of the profile shape of the produced gratings in angular and spectral relations for their diffraction efficiency is considered. It is shown that by varying the parameters of producing the original gratings and the conditions of their additional treatment it is possible to obtain hologram gratings with the required profile shape and blaze angle. To whom correspondence should be addressed. Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, 45, Nauka Ave., Kiev, 252028, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 4, pp. 587–590, July–August, 1999.     

High-efficiency multilayer-coated ion-beam-etched blazed grating in the extreme-ultraviolet wavelength region

We describe a simple method to fabricate blazed gratings used in the extreme ultraviolet wavelength region. The method uses an argon and oxygen mixed-gas ion beam to directly etch the grating substrate through a rectangular profile photoresist grating mask. With this method the etched grating groove profile can be well controlled. An Mo/Si multilayer-coated specimen with a blaze angle of 1.9 degrees was fabricated and measured. At an incident angle of 10 degrees and a wavelength of 13.62 nm, the diffraction efficiency of the negative second order reaches 36.2%.     

Blaze optimization for sinusoidal profile gratings

Diffraction gratings having optimized sinusoidal groove profiles are shown to have blaze properties comparable with those of triangular profile gratings of the same line density.     

Direct laser fabrication of blaze gratings in fused silica

Results of our investigations on direct laser fabrication of blaze gratings in fused silica using a special fluorine-laser mask projection technology allowing to produce plane and smooth reflecting areas and optimum blaze geometry will be presented. In particular, it will be shown that gratings with nearly optimum blaze geometry and relatively low surface roughness of the reflecting areas can be produced. The technique is a one-step method and has a high variability with regard to grating geometry and also substrate materials. We use masks made of tantalum foil, projected onto a fused silica substrate surface with a demagnification ratio of 26:1 and also novel scattering masks made of calcium fluoride. In these masks, up to 25 times smaller transmission apertures can be manufactured allowing thus grating constants in the range of a few μm. The average surface roughness of the reflecting areas along a blaze grating line was measured to be R _a=38 nm without any surface smoothing. The maximum variance of the blaze angle within one grating is about 0.5 degree.     

提高离子束刻蚀亚微米光栅侧壁陡直度的方法

现代亚微米光栅的应用通常要求栅脊侧壁陡直。通过比较两种配备不同离子源的刻蚀机的反应离子束刻蚀结果,认为影响亚微米光栅侧壁陡直度的一个重要因素是离子束发散角(束散角),且小束散角有利于获得陡直的光栅侧壁。国内应用最广泛的双栅考夫曼刻蚀机束散角较大(大于13°),致使用常规方法获得的熔石英光栅的侧壁倾角仅为77°。针对此刻蚀机,尝试了三种提高侧壁陡直度的方法:旋转倾斜刻蚀法、交替倾斜刻蚀法和二次金属掩模法,分别把侧壁倾角提高到86°、86°和82°。最后从掩模侧壁收缩速率和槽底部与顶部离子通量的差异对束散角对侧壁陡直度的影响给予解释,并说明了上述三种方法的工作机理。     

In situ endpoint detection of reactive ion-beam etching of dielectric gratings with an etch-stop layer using downstream mass spectrometry

Downstream mass spectrometry is successfully used in the reactive ion-beam etching of dielectric diffraction gratings of deep grooves with vertical sidewalls to achieve in situ endpoint detection. Silica (SiO₂) gratings with a Sc₂O₃ etch-stop layer are fabricated by reactive ion-beam etching with CHF₃ as etchant, and the mass spectrometric signal of SiF₃⁺ produced by the reactive etching of the SiO₂ grating material is monitored. When the etch-stop layer is reached, a drop of this signal occurs. By comparing the monitoring curves and resulting gratings of different etching methods, we find that the decrease of the monitored signal is strongly influenced by the sidewall steepness of the etched grating grooves. All conditions being equal, the greater sidewall steepness renders the faster decrease of the signal. Consequently, the proposed approach of endpoint detection applies well to the gratings with steep sidewalls. With the help of two previously developed methods, the sidewall steepness of grating grooves is increased, and the optimal endpoint is detected. Employing the proposed technique, we have reproducibly fabricated dielectric gratings with proper groove depth and even groove bottom.     

Optimizing and characterizing grating efficiency for a soft X‐ray emission spectrometer

The efficiency of soft X‐ray diffraction gratings is studied using measurements and calculations based on the differential method with the S‐matrix propagation algorithm. New open‐source software is introduced for efficiency modelling that accounts for arbitrary groove profiles, such as those based on atomic force microscopy (AFM) measurements; the software also exploits multi‐core processors and high‐performance computing resources for faster calculations. Insights from these calculations, including a new principle of optimal incidence angle, are used to design a soft X‐ray emission spectrometer with high efficiency and high resolution for the REIXS beamline at the Canadian Light Source: a theoretical grating efficiency above 10% and resolving power E/ΔE > 2500 over the energy range from 100 eV to 1000 eV are achieved. The design also exploits an efficiency peak in the third diffraction order to provide a high‐resolution mode offering E/ΔE > 14000 at 280 eV, and E/ΔE > 10000 at 710 eV, with theoretical grating efficiencies from 2% to 5%. The manufactured gratings are characterized using AFM measurements of the grooves and diffractometer measurements of the efficiency as a function of wavelength. The measured and theoretical efficiency spectra are compared, and the discrepancies are explained by accounting for real‐world effects: groove geometry errors, oxidation and surface roughness. A curve‐fitting process is used to invert the calculations to predict grating parameters that match the calculated and measured efficiency spectra; the predicted blaze angles are found to agree closely with the AFM estimates, and a method of characterizing grating parameters that are difficult or impossible to measure directly is suggested.     

平面全息光栅刻线密度的倍频式调整方法

刻线密度准确与否直接影响光栅色散及给定波长的衍射方向,进而影响光谱仪器结构设计.为了提高全息光栅刻线密度的制作精度,提出了平面全息光栅刻线密度的倍频式调整方法.将给定刻线密度的基准光栅放在干涉场曝光区域内,调节光束干涉角,干涉场曝光光束经基准光栅衍射后,根据调整光栅刻线密度的不同选择不同的衍射级次相互叠加形成莫尔条纹,...     

同步辐射Laminar光栅的研制

采用全息离子束刻蚀和反应离子刻蚀相结合的新工艺 ,在熔石英基片上成功地刻蚀出 2 0 0l/mm、线空比 4:6、槽深 70nm、刻划面积 60× 2 0mm2 的浅槽矩形Laminar光栅。对改进光栅线条粗糙度和线空比的方法进行了系统的研究。这一新工艺相对简单 ,降低了对干涉系统光学元件和全息曝光显影的严格要求     

刻划阶梯光栅的原理和应用特性

本文介绍了近年来在国际上受到重视的刻划阶梯光栅(Echelle),述及了它的诞生历史,与其他类型光栅的比较,干涉、衍射模型和若干应用方面的问题。