基于Canny算子的机械元件广义疵病无损检测系统关键技术

针对某大型实验装置机械及光学元件表面广义疵病的检测,采用无损检测方法实现了机械光学元件广义疵病的检测分析系统,并设计了机械三维电动平移台.在图像边缘提取中,采用基于Canny算子的边缘提取与阈值相结合的方式,提取元件表面图像信息,并由软件输出表面参数信息,相关实验证明系统达到设计要求.     

Direct measurement of beam size in a spectroscopic ellipsometry setup

Spectroscopic ellipsometry signals used in thin film analysis are dependent on the beam probe size. In this work, we report a technique to determine the beam size that uses the existing detection facilities in a spectroscopic ellipsometry setup without the need to rearrange the optical components. The intensity signal recorded with the technique comprises a coupled boundary diffraction and knife edge wave that can be isolated using nonlinear fitting. This then permitted an accurate measurement of the beam size with the stronger knife edge component. The technique has the added advantage of picking up chromatic aberration in the probing lens which may be a factor in ellipsometry measurement.     

Optical workstation with concurrent, independent multiphoton imaging and experimental laser microbeam capabilities

Experimental laser microbeam techniques have become established tools for studying living specimens. A steerable, focused laser beam may be used for a variety of experimental manipulations such as laser microsurgery, optical trapping, localized photolysis of caged bioactive probes, and patterned photobleaching. Typically, purpose-designed experimental systems have been constructed for each of these applications. In order to assess the consequences of such experimental optical interventions, long-term, microscopic observation of the specimen is often required. Multiphoton excitation, because of its ability to obtain high-contrast images from deep within a specimen with minimal phototoxic effects, is a preferred technique for in vivo imaging. An optical workstation is described that combines the functionality of an experimental optical microbeam apparatus with a sensitive multiphoton imaging system designed for use with living specimens. Design considerations are discussed and examples of ongoing biological applications are presented. The integrated optical workstation concept offers advantages in terms of flexibility and versatility relative to systems implemented with separate imaging and experimental components.     

螺旋槽成型铣刀的加工

介绍了螺旋槽型线铣刀的成型加工技术,阐述了使用数控磨削设备和数控检测仪在成型铣刀加工、测量中的重要作用,分析了螺旋槽成型铣刀、螺旋槽波刃成型铣刀磨削工艺。     

基于激光测距的三坐标测量系统研究

提出了基于激光测距的三维坐标测量系统。介绍了系统所采用的 PSD光学三角法测位移原理 ,并分析了影响测量精度的因素 ,提出了相应的补偿方法。最后 ,研究了系统的控制方法。     

Lateral motion and edge wear of magnetic tapes

Lateral motion and edge wear are measured on magnetic tape, and the relationship between tape edge wear and tape lateral motion is investigated. Instrumentation for measuring tape edge force is described. Tape edge force is measured at the tape guiding position using a force-calibrated cantilever spring and a linear optical probe. Typical measurements of tape lateral motion are given as a function of tape tension, tape direction, and path position. A technique for measuring tape edge wear is introduced and wear measurements are presented as a function of load and the number of passes.     

Nanometer edge profile measurement of diamond cutting tools by atomic force microscope with optical alignment sensor

This paper describes an atomic force microscope (AFM) based instrument for nanometer edge profile measurements of diamond cutting tools. The instrument is combined with an AFM unit and an optical sensor for alignment of the AFM probe tip with the top of the diamond cutting tool edge in the submicrometer range. In the optical sensor, a laser beam from a laser diode is focused to generate a small beam spot with a diameter of approximately 10 μm at the beam waist, and then received by a photodiode. The tool edge top and the AFM probe tip are brought to the center of the beam waist, respectively, through monitoring the variation of the photodiode output. To reduce the influence of the electronic noise on the photodiode output so that the positioning resolution can be improved, a modulation technique is employed that modulates the photodiode output to an AC signal by driving the laser diode with a sinusoidal current. Alignment experiments and edge profile measurements are carried out.     

Reduction of edge penetration effect in the scanning electron microscope

Electron penetration into the sample in the scanning electron microscope can give rise to bright fringes close to sharp edges in the secondary electron image. This can make it difficult to see details close to the edge. These fringes can be considerably reduced by putting a positive control electrode (CE) between the specimen and the collector. This can be mounted with an insulated clip directly onto the specimen stub. The effectiveness of this technique is demonstrated for the case of a cleaved silicon wafer containing microelectronic structures. The action of the CE is explained in terms of the effective solid angle subtended by the collector at the surface of the specimen.     

Coherent microscopy by laser optical feedback imaging (LOFI) technique

The application of the non-conventional imaging technique LOFI (laser optical feedback imaging) to coherent microscopy is presented. This simple and efficient technique using frequency-shifted optical feedback needs the sample to be scanned in order to obtain an image. The effects on magnitude and phase signals such as vignetting and field curvature occasioned by the scanning with galvanometric mirrors are discussed. A simple monitoring method based on phase images is proposed to find the optimal position of the scanner. Finally, some experimental results illustrating this technique are presented.     

Image contrast of dielectric specimens in transmission mode near-field scanning optical microscopy: imaging properties and tip artefacts

Near-field scanning optical microscopy (NSOM) is a scanned probe technique utilizing a subwavelength-sized light source for high-resolution imaging of surfaces. Although NSOM has the potential to exploit and extend the experimental utility of the modern light microscope, the interpretation of image contrast is not straightforward. In near-field microscopy the illumination intensity of the source (probe) is not a constant value, rather it is a function of the probe–sample electronic environment. A number of dielectric specimens have been studied by NSOM to elucidate the contrast role of specimen type, topography and crystallinity; a summary of metallic specimen observations is presented for comparative purposes. Near-field image contrast is found to be a result of lateral changes in optical density and edge scattering for specimens with little sample topography. For surfaces with considerable topography the contributions of topographic (Z) axis contrast to lateral (X,Y) changes in optical density have been characterized. Selected near-field probes have also been shown to exhibit a variety of unusual contrast artefacts. Thorough study of polarization contrast, optical edge (scattering) contrast, as well as molecular orientation in crystalline specimens, can be used to distinguish lateral contrast from topographic components. In a few cases Fourier filtering can be successfully applied to separate the topographic and lateral contrast components.     

实现光学图像边缘增强的激光散斑离焦法

激光散斑干涉法是近代光学的一项新技术。对于低对比度的图像 ,由于边缘部分模糊 ,强度变化不大而难以分辩。介绍了激光散斑干涉图像离焦法 ,并将其应用于光学图像的微分滤波 ,增强图像的边缘 ,从而得到边缘对比度较大的光学图像的原理与方法     

一种基于椭圆变形模板的唇动跟踪算法

本文给出了一种新的唇动跟踪算法框架，算法结合目标的形状、运动及彩色信息，综合利用可变形模板、光流、Kalman滤波技术，得到一种快速、鲁棒的跟踪结果。该算法使用多条椭圆弧段构成唇模板，基于彩色YCrCb信息进行光流估计，由于利用模型约束的特征光流技术，故不需加入任何附加的平滑性约束；最后借助扩展Kalman（EKF）滤波器将形状与运动信息有机结合起来，给出有效的融合解，而不必直接计算光流；该算法同时利用光流测量方程给出的误差测度及EKF给出的估计方差对虚假边缘点做出判断与舍弃，提高了算法的鲁棒性。文中还给出了相应的实例。     

单机立体图象显示仪的研制

本文论述了单机立体图象显示仪的成象原理和光学系统的设计方法，并给出了光学系统的结构参数。实践结果证明，这种方法是可行的精确的。     

A Fluorimeter on the Basis of a Femtosecond Cr<Superscript>+4</Superscript>: Forsterite Laser

An apparatus for measuring luminescence lifetimes using the femtosecond up-conversion method is presented. A laser system based on a chromium–forsterite crystal with a lasing wavelength of 1250 nm is used to generate ultrashort pulses. Luminescence is excited in a sample by optical harmonics that are generated in nonlinear optical crystals. The width of the instrument function of the system is 200 fs. Methods for optimizing the signal-to-noise ratio in measurements are discussed. The results of measurements of the fluorescence- decay dynamics and the anisotropy of aqueous solutions of an inclusion complex of the 4-DASPI styrene dye in cucurbit[6]uril on short (5 ps) and long (500 ps) time scales are presented.     

Near-field optical microscope working on TEM wave

A new type of probe for the near-field optical microscope incorporating metallic strips on the surface of a dielectric cone (microstrip probe) is proposed. The numerical simulation has shown a significant improvement in optical efficiency for this type of probe compared with the conventional probe. It was found theoretically that scanning near-field optics with the microstrip probe is promising for applications in optical information recording and can be employed as optical heating elements in magnetic information recording. Application of the microstrip probe in nonlinear optical research of nanoscaled medium is possible due to strong electric and magnetic field near the aperture and weak dependence of its transmission parameters on the frequency of the incident beam. A model for the near-field strip probe with cleaved apex is proposed. A method is presented to control the distance between the probe apex and sample surface based on mechanical vibrations of the cleaved apex excited by applying voltage pulses. The oscillation amplitude and attenuation can be determined by measuring the amplitude of microwave radiation excited by oscillations of charges with opposite sign at the probe apex. The investigation was based on mathematical models and experiments necessary to confirm the theoretical prediction.     

An apparatus for pulse chemical vapor deposition of layers

An apparatus for chemical deposition of layers of different materials with pulsed automated dosing of a hot gas phase of volatile metal-organic compounds (precursors) admitted into a reaction chamber is described. The apparatus has three channels for dosing the gas precursor phase and three channels for dosing reacting gases. As an example, a technique for depositing HfO₂ films on a (100)Si substrate is presented, and the deposited films are analyzed. It is shown, that this apparatus can be used to deposit layers on complex 3D systems with a large aspect ratio using an example of the deposition of HfO₂ layers on the inner surfaces of channels of a microchannel plate.     

Orthogonal-plane fluorescence optical sectioning: Three-dimensional imaging of macroscopic biological specimens

An imaging technique called orthogonal-plane fluorescence optical sectioning (OPFOS) was developed to image the internal architecture of the cochlea. Expressions for the three-dimensional point spread function and the axial and lateral resolution are derived. Methodologies for tissue preparation and for construction, alignment, calibration and characterization of an OPFOS apparatus are presented. The instrument described produced focused, high-resolution images of optical sections of an intact, excised guineapig cochlea. The lateral and axial resolutions of the images were 10 and 26 μm, respectively, within a 1·5-mm field of view.     

On-Line Non-Contact System for Grinding Wheel Wear Measurement

An on-line non-contact method for measuring the wear of a form grinding wheel is presented. A CCD (charge coupled device) camera with a selected optical lens and a frame grabber was used to capture the image of a grinding wheel. The analogue signals of the image were transformed into corresponding digital grey level values. Using the binarisation technique, the images of background and the grinding wheel were segmented. Thus the grinding wheel edge was identified. The 'mapping function method' is used to transform an image pixel coordinate to a space coordinate. An auto-focus technology is also developed. The statistics of pixels are used as the focusing index. The signal was sent through an 8255 control card to drive a d.c. motor, and then to control the lens focusing movement to acquire the focal plane. The images before and after the grinding process were captured. The position deviation of the grinding wheel edge was analysed. Then, the grinding wheel wear was evaluated. The wear detection accuracy is about 1 μm.     

Combining optical tweezers and patch clamp for studies of cell membrane electromechanics

We have designed and implemented a novel experimental setup which combines optical tweezers with patch-clamp apparatus to investigate the electromechanical properties of cellular plasma membranes. In this system, optical tweezers provide measurement of forces at piconewton scale, and the patch-clamp technique allows control of the cell transmembrane potential. A micron-size bead trapped by the optical tweezers is brought in contact with the membrane of a voltage-clamped cell, and subsequently moved away to form a plasma membrane tether. Bead displacement from the trapping center is monitored by a quadrant photodetector for dynamic measurements of tether force. Fluorescent beads and the corresponding fluorescence imaging optics are used to eliminate the shadow of the cell projected on the quadrant photodetector. Salient information associated with the mechanical properties of the membrane tether can thus be obtained. A unique feature of this setup is that the patch-clamp headstage and the manipulator for the recording pipette are mounted on a piezoelectric stage, preventing relative movements between the cell and the patch pipette during the process of tether pulling. Tethers can be pulled from the cell membrane at different holding potentials, and the tether force response can be measured while changing transmembrane potential. Experimental results from mammalian cochlear outer hair cells and human embryonic kidney cells are presented.     

基于偏振分像的制冷器件晶粒双面等光程共焦成像缺陷检测装置

针对待测晶粒大的情况,为解决晶粒双面检测时双面之间产生光程差导致的的成像清晰度问题,提出了一种基于偏振分光成像法的半导体制冷器件晶粒相邻双面同时成像缺陷检测的装置。利用偏振分光器与直角转像棱镜对采用偏振分束器与偏振相机的晶粒天面和侧面同时等光程共焦成像检测装置进行了光学设计,完成了晶粒相邻双面同时等光程偏振成像缺陷检测的实验验证。结果表明,该偏振分光成像检测技术可以实现晶粒相邻面的同时缺陷检测,并能很好地满足相邻面等光程成像缺陷检测的性能要求。当晶粒相邻面等光程共焦时,检测分辨率可达到110 lp/mm以上,而当晶粒相邻面离焦（准共焦）仅±0.20 mm时,分辨率则降至45 lp/mm以下。本检测装置具有双面成像清晰度好、成像光路共焦调整方便、检测装置结构简单可靠,以及提高的缺陷检测性能等优点。