分辨力增强技术的频谱分析

离轴照明和衰减型相移掩模作为重要的分辨力增强技术,不仅可以提高光刻的分辨力,同时还可以改善成像焦深,扩大光刻工艺窗口,实现65~32 nm分辨成像。从频谱的角度分析了离轴照明和衰减型相移掩模对成像系统交叉传递函数和像场空间频率分布的影响,研究这两种技术的物理光学本质,由此进一步优化光学成像系统设计、分辨力增强技术和确定设备使用的参量。对分辨力增强技术的频谱分析研究表明,分辨力增强技术通过调整像场频谱分布,改善了光学光刻的图形质量。对于65 nm密集图形,离轴照明和相移掩模结合后可以使成像衬比度最高达到0.948,工艺窗口在5%曝光范围内焦深达到0.51μm。     

Real-time reflection imaging with terahertz camera and quantum-cascade laser

A real-time reflection imaging employing a terahertz （THz） camera as the imager and a 3.9 THz quantum- cascade laser （QCL） as the light source is demonstrated. The imaging light is collected and guided by only one off-axis parabolic mirror. The imaging distance is about 1 m. THz images of a coin and a knife are aacquired and analyzed. An actual soatial resolution with a value of about 0.33 mm is achieved.     

太阳极紫外成像光谱仪光学系统设计

在极紫外波段对太阳进行超光谱成像观测是研究太阳上层大气,日冕中等离子物理特性的重要手段。依据太阳极紫外成像光谱仪的应用,结合国内外极紫外成像光谱仪发展现状,制定了太阳极紫外成像光谱仪的性能指标。通过比较各种光学结构的优缺点,选择望远镜与光谱仪组合的结构。讨论并选择了可用的基本元器件,望远系统采用离轴抛物面反射镜,分光器件为高密度超环面等间距光栅。设计出符合指标的光学系统。最后给出了太阳极紫外成像光谱仪的设计过程、详细参数与结果。光学系统的工作波段为17.0～21.0nm,视场是1 228″×1 024″,空间分辨率达到0.8arcsec.pixel-1,光谱分辨率约为0.001 98nm.pixel-1,系统总长度约为2.8m。     

基于离轴两反利特罗结构的棱镜高光谱成像系统的光学设计

为满足高光谱成像系统高空间分辨率和高光谱分辨率的要求,并应对实际应用中对仪器小型化、轻量化、高光学效率的新需求,研究一种基于利特罗结构的棱镜色散高光谱成像系统,采用离轴两反的利特罗结构形式减小光学系统的体积,同时为平面棱镜提供准直光路,并以宏编程的优化方式,避免系统中光路干涉。结果表明,通过非球面反射镜和双校正透镜的设计,该光学成像系统的谱线弯曲均小于2.1 μm,色畸变小于1.3 μm,控制在18%像元内,在400～1 080 nm可见—近红外(VNIR)工作波段的光学调制传递函数(MTF)均达到0.9以上,光谱分辨率为1.6～5.0 nm,光谱透过率在51.5%以上,系统在整个工作光谱范围都具有较高的透过率和像质。     

Full-field and single-shot quantitative phase microscopy using dynamic speckle illumination

We developed an off-axis quantitative phase microscopy that works for a light source with an extremely short spatial coherence length in order to reduce the diffraction noise and enhance the spatial resolution. A dynamic speckle wave whose coherence length is 440 nm was used as an illumination source. To implement an off-axis interferometry for a source of low spatial coherence, a diffraction grating was inserted in the reference beam path. In doing so, an oblique illumination was generated without rotation of the wavefront, which leads to a full-field and single-shot phase recording with improved phase sensitivity of more than a factor of 10 in comparison with coherent illumination. The spatial resolution, both laterally and axially, and the depth selectivity are significantly enhanced due to the wide angular spectrum of the speckle wave. We applied our method to image the dynamics of small intracellular particles in live biological cells. With enhanced phase sensitivity and speed, the proposed method will serve as a useful tool to study the dynamics of biological specimens.     

高分辨率星载真空紫外成像光谱仪设计与研究

为了实现对大气层中辐射波长分布在真空紫外和近紫外波段(115～300 nm)的粒子探测,完善大气遥感,设计了一种高分辨率成像光谱仪,并开展了原理样机的研制.根据国外已有载荷进行分析,选用了以离轴抛物镜为望远系统、Czerny-Tumer结构为成像光谱系统的光学方案;针对真空紫外波段辐射弱的特点选取了带有MCP的二维光子...     

离轴微粒场全息术中记录介质分辨率要求

本文从离轴微粒场全息记录光路的一般模型出发,导出了离轴微粒场全息术中记录介质分辨率要求的普遍公式。讨论了三种典型形状微粒对记录介质的分辨率要求。结果表明,除了参考光的倾角外,微粒的尺寸和参、物光的波前曲率差及微粒重心偏离光轴的距离也都是影响记录介质分辨率要求的主要因素。     

Effective bandwidth reduction for a high-power laser-diode array by an external-cavity technique

bandwidth of a high-power laser-diode array was effectively suppressed by use of an off-axis external-cavity technique. The external cavity consisted of a beam-transformation system and a pair of off-axis volume Bragg gratings. During operation at a drive current of 40 A, we reduced the bandwidth's full width at half-maximum from 3.3 to 0.24 nm (14-fold reduction) and achieved an output power of 20 W, or as much as 87% of the power radiated by a free-running laser-diode array without an external cavity.     

193nm光刻曝光系统的现状及发展

投影曝光工艺是集成电路制造过程中的关键环节,曝光系统的工艺水平已成为衡量微电子制造技术的重要标志。重点介绍了目前193 nm光刻设备曝光系统的发展现状和趋势,以及为提高曝光质量所采用的相关分辨率增强技术;通过分析曝光系统的构成和其中的关键技术,探讨了国内研制相关曝光设备所面临的挑战。     

空间高层大气遥感远紫外成像光谱仪的光学系统

空间高层大气遥感远紫外成像光谱仪主要用于观测高层大气中的远紫外辐射和实现对其内部中尺度现象成像的功能。目前我国该类的相关仪器研究基础还比较薄弱,针对这种情况,在光学系统设计的角度上给出了一种适用于130～180nm波段探测的光学系统方案。该成像光谱仪光学系统以离轴抛物镜为物镜,串联Wadsworth结构为成像光谱系统;这种串联Wadsworth成像光谱系统采用离轴抛物镜做准直镜,分光器件为平面光栅和球面光栅串联,实现二次色散,同时球面光栅起到聚焦成像作用;在像差理论的基础上,对该结构的光程函数和各像差进行了分析,获得了改进结构的宽波段完善成像条件。针对低轨空间探测应用要求设计了相关改进型Wadsworth结构成像光谱仪光学系统,设计结果证明系统像差得到了充分校正,在奈奎斯特频率(20lp/mm)下全视场全波段调制传递函数值在0.6以上。该优化结构同时具备高空间分辨率和高光谱分辨率,性能优越。     

Structural characterization of La0.9Ba0.1MnO3/Y-ZrO2 film by X-ray diffraction

Perovskite manganite La_0.9Ba_0.1MnO₃(LBMO) films were deposited on (0 0 1)-oriented single crystal yttria-stabilized zirconia (YSZ) substrate by 90° off-axis radio frequency magnetron sputtering. The film thickness ranged from 10 nm to 100 nm. Grazing incidence X-ray diffraction technique and high resolution X-ray diffraction were applied to characterize the structure of LBMO films. The LBMO film mainly consisted of (0 0 1)-orientated grain as well as weakly textured (1 1 0)-orientated grain. The results indicated that an amorphous layer with thickness of about 4 nm was formed at the LBMO/YSZ interface. The strain in LBMO film was small and averaged to be about -0.14%. The strain in the film was not lattice mismatch-induced strain but residual strain due to the difference in thermal expansion coefficient between film and substrate.     

交叉非对称型Czerny-Turner光谱仪光学系统设计

根据Czerny-Turner结构光谱仪工作原理,以便携式微型光学系统为设计目标,设计了一种光谱范围为200900nm的交叉非对称型Czerny-Turner光谱仪光学系统.通过分辨率、光谱范围等设计要求确定光谱仪大致结构后,引入初级像差对初始结构进行进一步优化.首次提出将球差约束条件与光阑面选取相结合,设计流程确定准直镜通光口径、光栅初始尺寸及聚焦镜中心波长对应口径,继而结合彗差约束条件,确定球面镜离轴角,并基于几何光学确定聚焦镜初始通光口径的方法.利用ZEMAX软件对初始参量进行模拟优化,并采用自主研制的样机进行光谱测量,分析结果表明,该光学系统能够在狭缝宽度为25μm,光栅常数为1.667μm/line条件下,实现中心波长分辨率优于1nm,边缘波长分辨率优于1.5nm.     

空间遥感大气痕量气体临边探测仪设计与研究

为满足空间大气痕量气体探测的迫切需求,设计并研制了一个空间遥感大气痕量气体临边探测仪原型样机.该样机光学系统由离轴抛物面望远镜和改进型Czerny-Turner光谱仪组成,工作波段为380~570 nm.在工作波段内,点列图半径的均方根值均小于9 μm,校正了像散,整个工作波段内同时获得了良好的成像质量.原型样机质量12 kg,体积420×350×200 mm³,空间像元分辨力0.6 km,光谱分辨力0.86 nm,各项指标均满足要求.利用临边探测仪原型样机进行了外场观测试验,外场观测光谱数据与模拟光谱数据进行了比对,二者具有很好的一致性,表明大气痕量气体临边探测仪功能和性能良好,满足大气痕量气体探测的应用要求.     

棱镜分光光谱仪的光学系统设计与光谱特性计算

设计了离轴全球面成像光谱仪和离轴校正透镜棱镜分光成像光谱仪两种光学系统.在离轴全球面成像光谱仪的基础上,提出了改进型离轴校正透镜光谱仪,仅采用一个色散棱镜,避免了大口径同心透镜;有效校正了大视场像差,色散非线性修正效果显著.通过调节离轴角和光谱仪的焦距控制了畸变,补偿了与波长相关的狭缝弯曲,减小了残余像差,并降低了整个光谱仪工程实施的难度.从工程合理性、加工可实现性和光学性能等方面比较了两个系统的特点,推导和给出了光谱分辨率和狭缝弯曲的计算结果.从设计结果看,改进型离轴校正透镜光谱仪的传递函数最小值大于75％,而离轴全球面成像光谱仪的最小值只大于60％.从加工难易程度看,离轴全球面成像光谱仪采用一个接近Φ200 mm的石英透镜,其透射材料远不如改进型离轴校正透镜光谱仪透镜材料的均匀性和面形准确度高,而且大口径透镜大大增加了制备难度和成本.从工程布局看,改进型离轴校正透镜光谱仪充分考虑了与机械结构的匹配,狭缝与第一面反射镜的轴向距离较合理.从光谱特性看,两个光学系统的光谱分辨率结果基本接近,离轴全球面成像光谱仪光谱弯曲结果略好于离轴校正透镜结构.因此,综合比较得出离轴校正透镜光谱仪是最佳的选择方案,该系统可应用在短波红外波段的光谱成像的遥感探测.     

Mapping of electrostatic potential in deep submicron CMOS devices by electron holography

Quantitative two-dimensional maps of electrostatic potential in device structures are obtained using off-axis electron holography with a spatial resolution of 6 nm and a sensitivity of 0.17 V. Estimates of junction depth and variation in electrostatic potential obtained by electron holography, process simulation, and secondary ion mass spectroscopy show close agreement. Measurement artifacts due to sample charging and surface "dead layers" do not need to be considered provided that proper care is taken with sample preparation. The results demonstrate that electron holography could become an effective method for quantitative 2D analysis of dopant diffusion in deep-submicron devices.     

A high-resolution spatial heterodyning interference spectrometer

A novel spectrometer which has a resolution of 0.013 nm with high throughput is described. The system uses a Michelson interferometer in which the mirrors have been replaced with Littrow-mounted diffraction gratings. First-order diffracted beams returning from the gratings interfere at the interferometer output to produce a spatial interferogram which is heterodyned about an optical frequency determined by the setting angles of the gratings. The heterodyning process leads to increased resolution, but limits the free-spectral range of the instrument to, in our case, about 3 nm. This is sufficient for characterizing narrow-band sources such as laser diodes. We present the theory of operation of the instrument and some sample spectra obtained from a sodium vapor lamp, a HeNe discharge, and a 670 nm diode laser.     

Off-Axis Imaging in Keel-Edge Pinhole Single Photon Emission Computed Tomography System Based on Monte Carlo Simulation

Monte Carlo simulation is applied to investigate the off-axis effect in keel-edge pinhole single photon emission computed tomography imaging.Aiming at finding the effective Geld of view(FOV) for imaging,we simulate point source in off-axis imaging(0,4,8 and 12 mm from the central rotation axis) of different collimator designs(channel height with 1.38,1 and 0.5 mm) with a fixed aperture diameter.Tradeoff curves of rms resolution and sensitivity are plotted to determine the effective FOV for different channel height pinhole collimators.The parameterized model can be further incorporated into image reconstruction algorithms,which compensates for the off-axis effect and is used as a reference for multi-pinhole design.     

Coherent x-ray diffraction imaging with nanofocused illumination

Coherent x-ray diffraction imaging is an x-ray microscopy technique with the potential of reaching spatial resolutions well beyond the diffraction limits of x-ray microscopes based on optics. However, the available coherent dose at modern x-ray sources is limited, setting practical bounds on the spatial resolution of the technique. By focusing the available coherent flux onto the sample, the spatial resolution can be improved for radiation-hard specimens. A small gold particle (size <100 nm) was illuminated with a hard x-ray nanobeam (E=15.25 keV, beam dimensions approximately 100 x 100 nm2) and is reconstructed from its coherent diffraction pattern. A resolution of about 5 nm is achieved in 600 s exposure time.     

Off-axis re-entrant cavity ring-down spectroscopy with a mid-infrared continuous-wave optical parametric oscillator

We demonstrate an off-axis cavity ring-down spectroscopy system, which uses a mid-infrared continuous-wave optical parametric oscillator as a light source. Off-axis injection with re-entrant configuration of the ring-down cavity is used to achieve high spectral resolution while maintaining high measurement speed. This makes the setup suitable for sensitive molecular spectroscopy in the mid-infrared region, particularly for studies that require high temporal resolution. Formaldehyde (H₂CO) absorption spectrum at 3.4 µm is measured using the off-axis re-entrant cavity ring-down spectrometer.     

超短脉冲激光瞄准装置光学系统设计

为了提高超短脉冲激光的瞄准精度,基于自准直原理提出瞄准装置光学系统。以670 nm光纤耦合激光器为光源,设计指示光准直、扩束光学系统,准直光的不平行度达到3.2,设计焦距为350 mm,相对孔径1/5,离轴量50 mm的主激光离轴抛物面镜,其成像质量达到衍射极限,基于准直束光学系统和离轴抛物面镜,设计可适应670 nm和800 nm两种波长的20和100的瞄准和监测成像光学系统。提出一种小孔准直的安装调试方法,以指示光进行实验验证,结果表明:设计的光学系统成像光斑均匀,其物方分辨率达到4.1 m。