大视场CCD成像系统像面均匀性测试技术研究

以光度学为理论基础,研究了大视场CCD成像系统像面均匀性测试技术。论述了600~800mm非对称、双半球不等半径积分球的设计方案。对像面均匀性测试系统的积分球出口进行了测试,出口处的照度不均匀性不高于2.3%,照度不稳定性不高于2.7%,积分球后半球内表面的亮度不均匀性不高于4.4%。在对测试结果进行误差分析的基础上,对大视场CCD摄像机进行了实际测试。结果表明,该装置可广泛应用于光电成像系统的像面均匀性测量。     

激光烧蚀羽流光学成像效果研究

使用YAG脉冲激光烧蚀固态POM聚合物和掺碳质量分数为5%的液态甘油混合物,形成羽流场.分别在相机镜头前添加滤光片以及在纹影系统中设置不同的刀口,观察对羽流场像的影响.实验结果表明:滤光片和暗场纹影均能够提高羽流纹影图像的显示效果.     

温度场纹影定量测量技术

为了研究纹影系统的温度场定量测量技术,本文详细阐述了纹影技术的定量测量原理,并通过分析流场纹影图像灰度大小与未被遮挡的光源像面积的关系,提出了一种新颖的流场温度定量测量的计算方法。首先,在光学平台上搭建了透射式纹影系统,将加热平台放置在该系统的测量区域,利用CCD相机将采集到的纹影图像上传到上位机进行图像处理,然后采用该算法计算得到温度场的测量值,并与热电偶的测量值相对比。实验结果表明：在室温20℃时,将加热平台的温度分别设定为50℃和90℃,纹影系统测量得到的温度值相对误差小于10%,证明了该计算方法的可靠性,实现了以纹影技术为基础的温度场定量测量。     

微光ICCD参数校准装置的弱光均匀光源系统

在微光ICCD参数校准装置中,为了获得分辨力、信噪比、最低照度及像面均匀性等参数测试中光源输出不同光照度,需要大动态范围积分球微弱光均匀光源。通过对传统的光源结构以及存在的局限性进行分析,根据微光ICCD综合参数测试中对光源照度的不同要求,设计了弱光均匀漫射光源系统。光源系统采用双积分球模式,利用楔形渐变光阑及可变孔径光阑实现在色温恒定下照度的连续变化,形成不同照度范围的均匀漫射光源,对微光ICCD参数校准装置的弱光均匀漫射光源照度输出范围及均匀性进行了测量,得到该光源的出射光照度范围为（10-7～103）lx,出射光照度均匀性优于98%,光源满足微光ICCD性能参数测试的要求。     

用于深空探测的宽谱段大视场小型光学系统设计

设计了一种宽谱段、大视场、轻小型成像光学系统.系统焦距为35mm,相对孔径为1∶7.5,工作谱段为0.4~0.9μm,全视场为2ω=60°,采用复杂化双高斯结构,透镜面形均采用球面设计,实现系统总长115mm,在70lp/mm处,最低光学传递函数大于0.45.利用负畸变法、像差渐晕法改善广角系统像面照度均匀性,使像面边缘视场照度达到中心视场的80%.像面照度不均匀性为8%,系统热光学性能良好,在0~40℃范围内均有较好的像质,满足深空探测需求.     

高动态范围激光焦斑测量数学模型研究

提出了一种高动态范围的激光焦斑测量方法.首先,构建纹影测量远场焦斑数学模型,确定重构需要的参数,并使用准直光路对参数进行标定;其次,运用综合诊断快速自动准直系统使纹影小球遮挡住旁瓣光斑中心,获得准确的旁瓣光斑;最后,改进计算纹影小球中心及图像融合等方面的纹影重构算法,克服了传统纹影重构方法中主瓣旁瓣中心误差大、合并图像拼接边缘台阶明显的缺点.对大型激光装置参数测量综合诊断系统的远场焦斑测量应用表明:通过对纹影测量远场焦斑数学模型中参数的精确标定以及对纹影重构算法的优化,能够实现高动态范围激光焦斑的准确测量.     

星载均匀像面低畸变广角气溶胶探测仪的研制

为满足空间遥感的迫切需求,设计并研制了一个星载均匀像面低畸变广角气溶胶探测仪样机.该仪器通过利用光阑像差产生的有效像差渐晕提高像面照度的均匀性,解决了广角系统中像面照度不均匀的问题.合理选择结构型式校正了畸变,并且采用全球面光学系统,易于加工和检测.广角气溶胶探测仪的中心波长为670 nm,带宽20 nm,全视场72°,相对孔径1/3.6,焦距20 mm.实验结果表明:研制的星载广角气溶胶探测仪镜头其入瞳大小5.6 mm,边缘视场的相对照度达到95.6%,在36 lp/mm处,轴上视场的调制传递函数值大于0.61,轴外视场的调制传递函数值高于0.58,最大畸变量为-1.95%,完全满足设计指标要求,体积小,适合空间遥感应用.     

光电成像检测系统像面照度均匀性分析

非均匀发光光源、大视场角等因素会造成光学成像检测系统像面照度分布不均匀,进而导致检测效率下降。研究非均匀发光光源和大视场角对像面照度均匀性的影响程度,首先建立光源间距与受光面接收照度间的关系模型,仿真分析不同LED间距对像面照度均匀性的影响,然后建立光学耦合系统的物面张角和像面照度间的关系模型,仿真分析物面张角对像面照度均匀性的影响。实验结果表明:在非均匀发光光源和大视场角的作用下,检测系统会造成像面照度严重不均匀现象。研究结果为后续像面照度校正算法设计提供了理论依据。     

固态面阵激光雷达接收光学系统设计

在确保固态面阵激光雷达安全性的前提下,为了提高光学系统的像面能量均匀度以及增加光学系统所接收到的能量,保证在探测过程中的低信噪比以及对目标的可探测性,本文通过对发射激光能量和接收能量进行建模,给出了光学参数,研究了影响接收光学系统像面照度的因素。指出大视场大相对孔径高照度均匀性光学系统的设计要素,并通过ZEMAX优化分析给出了具体的实施过程。最终设计了λ=905(±5)nm,焦距为15 mm,相对孔径为1/1.4,视场角为2ω=76°的激光雷达接收镜头,系统总长小于77 mm,在空间频率为20 lp/mm处MTF值大于0.5,在0.85视场内的相对畸变小于8%,像面照度不均匀性小于7.2%。满足激光雷达的探测要求。     

大视场光学系统像面照度均匀性优化

为提高大视场光学系统像面照度的均匀性,从理论上分析了光学系统像面照度的影响因素,提出使用中心遮拦产生的轴外斜光束截面积与轴上光束截面积之比对像面照度进行优化的思路。以理想系统建立数学模型,得到了中心圆形遮拦影响下不同视场角光束截面积比值的变化规律,并分析了遮拦对调制传递函数(MTF)的影响。进一步提出采用Zemax与Matlab软件动态数据交换(DDE)进行像面照度自动计算优化的方法。以某焦距56mm,相对孔径=1/5.6,视场角2ω=80°的航测镜头为例进行了优化,通过在光学系统第5表面上增加半径为4.384mm的中心遮拦,像面照度的不均匀性由优化前的22.3%降低至3.5%,均匀性明显改善。在优化实例中讨论了MTF曲线的变化,指出采用中心遮拦后的传函指标仍满足CCD探测器成像使用要求。     

The leak microstructure

The capabilities of a new microstructure, anode point based, for the detection of gas ionizing radiations are presented. For every single detected ionizing radiation it gives a pair of ‘induced’ charges (anodic and cathodic) of the same amount (pulses of the same amplitudes), of opposite sign, with the same collection time and essentially in time coincidence, that are proportional to the primary ionization collected. Each pulse of a pair gives the same energy and timing information, thus one can be used for these information and the other for the position. The complete lack of insulating materials in the active volume of this microstructure avoids problems of charging-up and makes stable and repeatable its behavior. It is possible to observe primary avalanches with a size of more than 2.5 × 10⁷ electrons (4 pC), which give current pulses with a peak of more than 0.26 mA on 100 Ohm and about 30 ns duration, with 5.9 KeV X-rays of ⁵⁵Fe working in proportional region in 760 Torr of isobutane gas. Single electrons emitted by a heated filament (Ec<1 eV) can also be detected in 760 Torr of isobutane; with an estimated gas gain of 1.2 × 10⁶ and a counting rate up to 800 Kpulses/sec per single microstructure. Some new features and three different types of sensitive-position two-dimensional read-out detectors based on these microstructures, which are in developmental stage, are presented.     

光纤成像光谱仪中谱线畸变对调制传递函数的影响

将光纤传像束应用到色散型成像光谱仪中取代其狭缝,链接望远系统和光谱仪组成光纤成像光谱仪。它是二重采样系统,光谱仪的谱线畸变使光纤束采样像元的像与探测器像元之间产生对准偏差,从而对第二次采样过程产生影响,导致调制传递函数(MTF)下降。从线扩散函数角度出发推导出采样过程光学传递函数,分析了谱线畸变对系统MTF的影响,建立了一套评价光纤成像光谱仪MTF的模型。该模型比狭缝型成像光谱仪MTF计算模型多了一项光纤积分MTF因子和一项由谱线畸变引起的对准偏差MTF因子,最后用该模型评价了某机载可见近红外波段光纤成像光谱仪MTF。MTF计算模型的推导和建立方法对计算二重采样系统光学传递函数有参考意义,能指导光纤成像光谱仪的设计。     

计算光谱成像技术的成像质量评价

计算光谱成像是一种新型的光谱成像技术,具有高通量、快照式成像等优点,但关于其成像质量评价的研究还很少。工作中探索了一种计算光谱成像系统成像质量的定量评价方法。该方法利用ISO 12233靶标作为目标源,进行成像、图谱信息重构,并通过测量重构图的调制传递函数(MTF)作为计算光谱成像系统的成像质量评价标准。结果表明,对于单帧采样,随着混叠谱段数的增加,重构图MTF迅速下降,当混叠波段的数目达到9个时,重构图MTF与目标场景图像相比已下降50%。该研究有助于理解计算光谱成像技术的优缺点,合理安排混叠谱段的数量,以精确地复原目标信息。     

Acoustic imaging using a volumetric array

A method is described for producing images of acoustic sources using a volumetric array. Theoretical results are presented and compared to those obtained experimentally from an acoustic 64 element random spherical volumetric array. Application areas for such a system include auditorium characterisation, recording studio optimisation and covert surveillance operations.     

Prospective tissue-mimicking materials for use in NMR imaging phantoms

Water-based proteinaceous gels, which—with appropriate additives—are stable with time and possess a high melting point, have been used as base materials in ultrasonically tissue-mimicking materials. In the present work, versions of these gels having various concentrations of glycerol and graphite particles were studied regarding their NMR T₁ and T₂ dependencies at a proton Larmor frequency of 10.7 MHz. It has been found that T₁ depends primarily on the concentration of glycerol and T₂ depends primarily on the graphite particle concentration. Also, the ranges of T₁ and T₂ likely span those which exist for soft tissue parenchymae. Thus, these materials are good candidates for use as NMR tissue-mimicking materials. T₁ and T₂ also vary with gelatin concentration. The latter fact, together with the strong dependence of T₂ on graphite concentration, mean that effective contrast-resolution phantoms and anthropomorphic phantoms with stable T₁ and T₂ distributions can be produced.     

Multispectral imaging of continuum emission for determination of temperature and density profiles inside implosion plasmas

In inertial confinement fusion experiments, implosion of a cryogenic hydrogen isotope-filled capsule produces a plasma with a high-temperature, low-density core (the hot spot) surrounded by a low-temperature, high-density main fuel layer. Experimental measurements of temperature and density profiles in the hot spot are critical for implosion diagnosis. In this paper, we propose a simple technique for measuring core temperature and density profiles in cryogenic implosion plasmas. This technique uses absolutely calibrated continuum emission spectroscopy coupled with two-dimensional imaging to allow temperature and density profiles to be measured directly. We develop the technique analytically, and validate it using synthetic data and hydrodynamics simulation results. We find that the technique should be sufficiently accurate to measure central temperatures and densities to better than 20%. The technique may also find application to the diagnosis of other types of plasmas.     

自聚焦透镜成象矩阵公式的近似性

本文从光线方程出发,对自聚焦透镜成象矩阵公式做了详细推导,由推导过程即可看出该公式的近似性及其应用范围,纠正了一些文献上认为该公式可应用于非高斯光学成象的看法。     

HL-2A Tokamak Gas Puff Imaging

Gas puff imaging （GPI） is one of the important diagnostics for the （ITPAC international tokamak physics activity ） and entering the ITPA IDD （ international diagnostics database ） . GPI is related to many investigations, for example, edge radiations, etc.     

The influence of |ω| filter on nonlinearity parameter imaging using filtered convolution method

I.IntroductionThenon1inearityparametcrB/AisanimportantparametcrtomcasurcthenonlinearityofamediumandisdcfincdbythcratioofcoefficientsofquadratictermtolineartermintheTay1orexpansion.Itdcscribcsthedistortionofasinewaveasitpropagatesthroughtheme-dium.Inreccntycarsmuchattcntionhasbccnfocusedontheinvestigationofnon1incarityparameterinbio;ogicalmediasinceitcanprovidedynamicalinformationofthemediaandgivemoresensitivediffcrcnccbctwccnnorma1andabnorma1tissuesthantheotherlinearultrasonicparametcrssucha…     

Motion imaging of objects in layers hidden by scattering media using low-coherence speckle interferometry

A novel method is proposed for motion imaging of objects in layers hidden by a scattering medium in a depth-resolved manner by means of the intensity difference in a temporal sequence of low-coherence speckle images. Depth-resolved motion imaging was demonstrated with a semi-transparent scattering plate and an aluminum diffusive plate behind Intralipid solution. Experimental results confirmed feasibility of the proposed method for imaging of moving objects by their relative velocity.