色散聚焦分离式彩色共聚焦测量系统研究

为了满足先进制造工艺的对检测技术越来越高的要求,对材料表面的测量既有高精度的要求,同时也有快速检测的需求。彩色共聚焦测量技术从原理上避免了轴向扫描过程,与传统的激光共聚焦技术相比,具有明显的测量速度优势,可针对大尺寸的被测物表面形貌进行快速化检测。通常情况下,针对不同测量需求的被测对象,需要设计不同的彩色共聚焦系统核心部件-色散物镜,增加了系统的复杂性。针对这一情况,采用色散和聚焦分离的设计方式,通过切换物镜参数的方式,快速有效地实现不同测量需求。所设计的大范围色散元件结合不同聚焦物镜时,能实现对色散范围的调制,并以此为基础搭建了聚焦和色散分离的彩色共聚焦系统。实验结果表明,采用不同参数物镜时,可实现对量程和分辨率的调制;其中,当采用10×(NA=0.3)物镜时,可获得轴向225μm的线性色散,此时测量系统的轴向测量精度优于0.2μm。     

光谱共焦显微镜的线性色散物镜设计

由于色散物镜轴向色散与波长间的非线性会导致仪器整体性能下降,本文研究了光学系统轴向色散与透镜组之间的关系,推导了轴向色散的传递公式.为得到较大的线性轴向色散,根据轴向色散的传递公式提出了一种正负透镜组均采用线性色散光焦度组合且正负透镜组分离的镜头结构.光学优化设计表明,具有正负透镜分离结构的色散物镜可以得到低的球差和大的轴向色散,而且具有较大的工作距离.设计的色散物镜在430～710 nm得到了1 mm的轴向色散,轴向色散与波长之间的相对非线性度为4.6％,灵敏度的波动量小于整体的1/3,优于之前的研究.采用所设计的色散物镜,光谱共焦显微镜能够得到优于0.3 μm的轴向分辨率和优于5 μm的横向分辨率,满足精密测量的需求.     

基于数字微镜器件的并行彩色共聚焦测量系统

彩色共聚焦技术因其高分辨率、高测速的特点,在表面形貌测量领域备受关注,然而现有的彩色共聚焦技术多为单点测量,一定程度上限制了测量效率。本文在彩色共聚焦技术的基础上,以DMD作为光分束器件,结合自主研发的大口径色散管镜,利用面阵彩色相机作为光电接收器件,研究和建立了基于数字微镜器件的并行彩色共聚焦实验平台,实现了对被测物面上多个探测点的并行图像处理。最终,利用所搭建的并行彩色共聚焦测量系统,对50μm高的台阶和自制台阶进行了测量,并对硬币的表面形貌进行了三维恢复。实验结果表明,该测量系统的轴向测量范围为300μm,测量精度达到微米级;同时,能够较好地恢复硬币的表面形貌特征,具有较好的测量效率与可靠性。     

共聚焦激光扫描显微系统光学设计

为了实现非接触式、快速高精度的光学检测,设计了一种共聚焦激光扫描显微光学系统。在保证设计指标的前提下,简化了各光组的结构,采用7片球面透镜并以K9玻璃作为透镜材料。使用Zemax软件对光学系统进行了设计和仿真。结果表明:物镜的数值孔径为0.49;系统的径向和轴向光学分辨率分别为0.400μm和0.772μm;显微聚焦系统聚焦弥散斑直径小于2μm;照明系统聚焦弥散斑直径小于10μm;探测系统的聚焦光斑直径小于20μm;根据仿真结果确定了针孔1和针孔2的尺寸均为20μm,且厚度不超过0.1mm;各子系统的MTF曲线均接近衍射极限,具有很高的光学传输效率。     

激光共聚焦扫描显微镜的光学设计

为获得较高分辨率的细胞图像,设计了激光共聚焦光学系统。通过较复杂结构物镜实现了照明光路系统和发射光路系统的设计。用Zemax对照明光路和发射光路进行了设计,仿真过程中照明光路的聚焦弥散斑直径小于1μm,照明针孔处的聚焦弥散斑直径小于20μm,发射光路的聚焦弥散斑直径小于20μm,同时照明光路和发射光路的MTF曲线接近衍射极限,达到较理想的情况。     

群相可控光学延迟线色散特性分析

分析了光学相干层析(OCT)成像系统的色散特性。分析表明,系统色散与振镜离焦量成正比关系,且在一倍焦距以内为负色散,在一倍焦距以外为正色散。设计了纵向分辨率为8 μm的OCT系统,测得振镜位于傅里叶透镜焦点外0.5 mm处时,系统产生的色散值约为77 fs²,实验结果与理论相符合。     

静电悬浮转子微陀螺微位移信号检测系统的设计

为实现对悬浮转子微陀螺转子五自由度的测量,提出了一种频分复用的微位移检测原理,主要介绍了多频率信号发生器,前置放大器,锁相放大器组成的测试系统,设计了一种基于DDS技术的多频率信号发生器和基于锁相放大原理的解调电路。实验和分析结果表明,该电路能实现多自由度微位移检测,设计的多频率信号发生器的频率分辨率能达到0．005821Hz,相位分辨率可以达到0．006rad,检测轴向灵敏度为1．34V／μm,检测径向灵敏度为0．092V／μm,测量电路的轴向位移分辨率为0．45nm,径向位移分辨率为6．6nm,转角的分辨率为0．25μrad,位移检测电路的分辨率,灵敏度和测量范围能够满足静电悬浮转子微陀螺的控制需要。     

斜入射法测量蓝宝石基片仿真分析与实验

为获取具有微米量级变化的蓝宝石基片的面形分布,采用斜入射法拓展数字干涉仪测量范围。根据斜入射测量原理,推导了斜入射角、平面面形偏差与系统波像差之间的关系。通过Zemax构建了斜入射测量仿真光路,研究了面形偏差及入射角度对检测结果的影响。通过仿真实验得出最佳斜入射角度等关键参数,并在斐索干涉仪上测量了直径为100 mm的蓝宝石基片,测量结果的PV为5.182μm,RMS为1.251μm。研究了斜入射角对分辨率、灵敏度因子、条纹对比度的影响。研究表明,斜入射角为70°时,适宜测量矢高值≤5μm的蓝宝石基片,引入误差小于0.1μm,测量范围是正入射测量范围的1.46倍,且能获得适宜的条纹对比度。     

高精度非接触式三维轮廓扫描仪设计

三维轮廓扫描仪是广泛应用于微纳表面三维形貌测量的高精度设备。基于白光共焦测量技术,提出了非接触式三维轮廓扫描仪设计方案和工作原理。扫描仪由精密扫描工作台、测量系统、光学辅助系统及控制系统组成。试制的扫描仪样机垂直测量范围为(20～400)μm,分辨率10nm,水平测量范围(100×100)mm,分辨率小于1μm。实验表明,该扫描仪可实现二维轮廓曲线和三维形貌测量,具有精度高、非接触、测量快速和测量范围宽等特点,对于实现高精度非接触式三维轮廓测量具有较高的实用价值。     

光谱共焦位移传感器镜头设计研究

光谱共焦位移传感器是一种高精度、非接触式位移传感器。本文讨论了光谱共焦法用于位移测量的基本原理,用Zemax光学设计软件完成了一个镜头组的设计,并给出了光谱共焦位移传感器镜头组的设计方法以及像差分析。该镜头组采用密接透镜结构,工作波段为486.13nm-656.27nm,测量范围约为91μm,轴向响应FWHM优于5μm。通过线性回归分析得出波长与位移间判定系数为0.99523,在测量范围内,位移与波长间的线性关系较好。     

Optical microscopy with flexible axial capabilities using a vari‐focus liquid lens

The axial imaging range of optical microscopy is restricted by its fixed working plane and limited depth of field. In this paper, the axial capabilities of an off‐the‐shelf microscope is improved by inserting a liquid lens, which can be controlled by a driving electrical voltage, into the optical path of the microscope. First, the numerical formulas of the working distance and the magnification with the variation of the focus of the liquid lens are inferred using a ray tracing method and conclusion is obtained that the best position for inserting a liquid lens with consistent magnification is the aperture plane and the rear focal plane of the objective lens. Second, with the liquid lens embedded in the microscope, the numerical relationship between the magnification and the working distance of the proposed flexible‐axial‐capability microscope and the liquid lens driving voltage is calibrated and fitted using the inferred numerical formulas. Third, techniques including autofocus, extending depth of field and three‐dimensional imaging are researched and applied, improving the designed microscope to not only flexibly control its working distance, but also to extend the depth of field near the variable working plane. Experiments show that the presented flexible‐axial‐capability microscope has a long working distance range of 8 mm, and by calibrating the magnification curve within the working distance range, samples can be observed and measured precisely. The depth of field can be extended to 400 μm from the variable working plane and is 20 times that of the off‐the‐shelf microscope.     

二元光学内调焦望远物镜的设计

对内调焦望远物镜进行设计,利用二元透镜独特的色散特性,在提高成像质量的同时对传统结构进行简化。选取合适的初始结构,通过CODE V软件对物镜进行设计、优化及像质分析,得到成像质量颇佳的系统。在此基础上,对系统进行了调焦及优化,实现了对1.5m到无穷远物距在分划板上清晰成像的目的。在所有变焦范围内,系统各视场在50lp/mm处的MTF值均大于0.4,且各视场的畸变均小于0.5%。     

Chromatic two-photon excitation fluorescence imaging

We report on a chromatic axial scanning method for two-photon excitation fluorescence imaging. Effective axial scanning is achieved by incorporating a Fresnel lens in the system, which has large chromatic aberration and can therefore focus the excitation beam to different axial positions depending on its wavelength. We experimentally demonstrated this technique and used it to image the cross-section of fluorescent microspheres.     

A new confocal scanning beam laser MACROscope using a telecentric,f-theta laser scan lens

A new confocal scanning beam system (MACROscope) that images very large-area specimens is described. The MACROscope uses a telecentric, f-theta laser scan lens as an objective lens to image specimens as large as 7·5 cm × 7·5 cm in 5 s. The lateral resolution of the MACROscope is 5 μm and the axial resolution is 200 μm. When combined with a confocal microscope, a new hybrid imaging system is produced that uses the advantages of small-area, high-speed, high-resolution microscopy (0·2 μm lateral and 0·4 μm axial resolution) with the large-area, high-speed, good-resolution imaging of the MACROscope. The advantages of the microscope/MACROscope are illustrated in applications which include reflected-light confocal images of biological specimens, DNA sequencing gels, latent fingerprints and photoluminescence imaging of porous silicon.     

后组调焦高清变焦镜头调焦凸轮曲线分析与设计

后组调焦高清变焦镜头适用于前端口径较小、近距离成像要求较高及光路需要偏折的场合。近摄时,后组调焦方式获得的成像质量比用前组调焦方法更好,焦距小于50mm时,近摄距可达0.35m,不需要加近摄镜(前组调焦要加近摄镜),可以兼顾远近距离的高清成像要求。由于后组调焦高清变焦镜头物距与后截距的关系不是线性关系,调焦组的移动在不同焦距段的不同物距时对应不同的特征曲线,差异较大。为使调焦灵敏度处在一个合理区间,后组调焦位移不能采用通常使用的线性关系,需设计一条能覆盖这些特征曲线的非线性凸轮,因而根据其原理与结构进行了分析与设计。     

Spatial and spectral performance of a chromotomosynthetic hyperspectral imaging system

The spatial and spectral resolutions achievable by a prototype rotating prism chromotomosynthetic imaging (CTI) system operating in the visible spectrum are described. The instrument creates hyperspectral imagery by collecting a set of 2D images with each spectrally projected at a different rotation angle of the prism. Mathematical reconstruction techniques that have been well tested in the field of medical physics are used to reconstruct the data to produce the 3D hyperspectral image. The instrument operates with a 100 mm focusing lens in the spectral range of 400-900 nm with a field of view of 71.6 mrad and angular resolution of 0.8-1.6 μrad. The spectral resolution is 0.6 nm at the shortest wavelengths, degrading to over 10 nm at the longest wavelengths. Measurements using a point-like target show that performance is limited by chromatic aberration. The system model is slightly inaccurate due to poor estimation of detector spatial resolution, this is corrected based on results improving model performance. As with traditional dispersion technology, calibration of the transformed wavelength axis is required, though with this technology calibration improves both spectral and spatial resolution. While this prototype does not operate at high speeds, components exist which will allow for CTI systems to generate hyperspectral video imagery at rates greater than 100 Hz.     

激光共焦透镜曲率半径测量系统

基于共焦技术独特的轴向层析定焦能力并结合气浮导轨平移台和激光干涉仪测长系统,研制了一套高精度、非接触激光共焦透镜曲率半径测量系统。该系统利用共焦轴向光强响应曲线的峰值点对应系统物镜聚焦焦点这一特性,使用峰值点对被测透镜的猫眼位置及共焦位置进行精确定位,并结合激光干涉仪获得透镜猫眼位置及共焦位置坐标值,从而计算得到透镜的曲率半径。系统由主控软件控制气浮导轨带动被测透镜在猫眼位置及共焦位置附近进行扫描测量,并实现信号采集和数据处理。实验表明,利用该系统测量透镜的曲率半径时,测量重复性优于2 μm,满足国内高精度透镜曲率半径测量的精度需求。该系统测量速度快、操作简便、结构简单且易于实现小型化。     

平行式Schmidt型龙虾眼X射线光学系统研究

龙虾眼X射线系统是实现大视场X射线成像的有效手段。现研制了由多组平行玻璃平板构成的Schmidt型X射线龙虾眼光学系统,开展了X射线聚焦和成像的演示实验。基于掠入射反射理论,以210μm厚的超光滑平板玻璃作为光学元件,通过堆叠的方式制作了放大倍数为1的演示系统。用8keV的X射线光源对系统进行了聚焦和实验,直径280μm的光源聚焦半高宽约为320μm,与理论模拟结果基本一致。利用X射线背光照明,得到2mm×2mm大小图样的成像。实验结果表明,该龙虾眼光学系统可以在几毫米视场下达到百微米分辨。