Confocal differential interference contrast (DIC) microscopy: including a theoretical analysis of conventional and confocal DIC imaging

A technique for obtaining differential interference contrast (DIC) imaging using a confocal microscope system is examined and its features compared to those of existing confocal differential phase contrast (DPC) techniques as well as to conventional Nomarski DIC. A theoretical treatment of DIC imaging is presented, which takes into account the vignetting effect caused by the finite size of the lens pupils. This facilitates the making of quantitative measurements in DIC and allows the user to identify and select the most appropriate system parameters, such as the bias retardation and lateral shear of the Wollaston prism.     

Graphic supervisory control of an automatic optical inspection for LED properties

This paper focuses on the development and manufacture of an automated optical inspection (AOI) system for light emitting diode (LED) properties, which include the luminance and forward voltage. We use the concept of graphic supervisory control to combine LabVIEW software and programmable logic controller (PLC) for the motion control. By connecting the analog input block, PLC would read the forward voltage to judge whether this value is too large or not. In LED optical inspection, LabVIEW software is employed to coordinate charge coupled device (CCD) camera interface in acquiring data and processing image analysis. The LED luminance is inspected according to whether or not it achieves the desired standard pixels of binary morphologic area. In the inspection process, LEDs quickly advance on rail, and a pneumatic cylinder will sort them into different storages by PLC. The system characteristics mainly include automated platform control and imaging inspection. From experiments, the LED inspection speed could achieve 40-45 pieces per minute. For luminance inspection, the rate of accuracy approaches 100% when the inspection in a dark room or the brightness of exterior environments is fixed.     

LED在基于光纤传输的照明系统中的应用

为了实现将LED应用于基于光纤传输的照明系统中以替代传统光源,首先简要介绍了基于光纤传输照明系统的应用及组成,描述了LED应用于光纤传输照明系统设计的光学扩展量理论。根据光学扩展量理论分析了LED选型方法,总结了基于LED光纤传输照明系统的设计原则和要点。然后应用设计实例:基于红,绿和蓝三色LED合光的光纤照明模组,详述了设计过程,给出了测试数据。结果表明:LED可以应用于光纤传输照明系统中替代传统光源,市场前景广阔。     

一种汽车LED前照灯散热器的性能分析及优化

为解决汽车用发光二极管的散热问题,将散热器的结构进行优化,对某LED车灯散热器进行参数化建模,利用仿真软件对每一组散热器进行热力学仿真分析,并结合汽车静止和行驶两种工况,通过改变不同参数的参数值研究该参数对散热器散热效能的影响。根据参数值—温度曲线选定最合适的参数值,以此对散热器进行优化设计。通过实物加工并设计实验平台对仿真计算结果进行实验,验证了优化参数的正确性。     

LED摩托车前照灯的光学系统设计

LED以其体积小、控制灵活、光色纯、耐震动、启动时间快,在功耗、寿命以及以及环保方面均有不可比拟的优越性;广泛应用于照明产品之中,地位举足轻重,更成为新一代摩托车光源技术的首选。如何设计LED摩托车前照灯的关健部件光学系统组件,成为了摩托车前照灯产品上利用LED光源的一个主要研究课题。     

Real‐time three‐dimensional imaging of cell division by differential interference contrast microscopy

Differential interference contrast (DIC) microscopy can provide information about subcellular components and organelles inside living cells. Applicability to date, however, has been limited to 2D imaging. Unfortunately, understanding of cellular dynamics is difficult to extract from these single optical sections. We demonstrate here that 3D differential interference contrast microscopy has sub‐diffraction limit resolution both laterally and vertically, and can be used for following Madin Darby canine kidney cell division process in real time. This is made possible by optimization of the microscope optics and by incorporating computer‐controlled vertical scanning of the microscope stage.     

Re-evaluation of differential phase contrast (DPC) in a scanning laser microscope using a split detector as an alternative to differential interference contrast (DIC) optics

In this paper, differential phase imaging (DPC) with transmitted light is implemented by adding a suitable detection system to a standard commercially available scanning confocal microscope. DPC, a long‐established method in scanning optical microscopy, depends on detecting the intensity difference between opposite halves or quadrants of a split photodiode detector placed in an aperture plane. Here, DPC is compared with scanned differential interference contrast (DIC) using a variety of biological specimens and objective lenses of high numerical aperture. While DPC and DIC images are generally similar, DPC seems to have a greater depth of field. DPC has several advantages over DIC. These include low cost (no polarizing or strain‐free optics are required), absence of a double scanning spot, electronically variable direction of shading and the ability to image specimens in plastic dishes where birefringence prevents the use of DIC. DPC is also here found to need 20 times less laser power at the specimen than DIC.     

A hybrid scanning force and light microscope for surface imaging and three-dimensional optical sectioning in differential interference contrast

The design of a scanned-cantilever-type force microscope is presented which is fully integrated into an inverted high-resolution video-enhanced light microscope. This set-up allows us to acquire thin optical sections in differential interference contrast (DIC) or polarization while the force microscope is in place. Such a hybrid microscope provides a unique platform to study how cell surface properties determine, or are affected by, the three-dimensional dynamic organization inside the living cell. The hybrid microscope presented in this paper has proven reliable and versatile for biological applications. It is the only instrument that can image a specimen by force microscopy and high-power DIC without having either to translate the specimen or to remove the force microscope. Adaptation of the design features could greatly enhance the suitability of other force microscopes for biological work.     

A light-emitting diode light standard for photo- and videomicroscopy

A light calibration system consisting of a compact light-emitting diode (LED) source with feedback control of intensity is described. The source is positioned in the focal plane of the microscope objective and produces flat-field illumination of up to 31 μW. The source can be easily used to determine the performance of microscope optics and camera response. It can also be used as a standard light source for calibration of experimental systems. Selectable light intensities are produced by controlling the LED input power via a feedback circuit consisting of a photodiode that detects output light intensity. Spectral coverage extends between 550 and 670nm using green, yellow and red LEDs mounted side by side, which are selected individually. The LED chips are encapsulated in plastic diffusers which homogenize the light, and a flat field of illumination is obtained through a thin 1-mm-diameter aperture positioned directly over each chip. Provision is made for insertion of Ronchi rulings over the aperture to enable measurements of contrast modulation in a uniform field. The light may be pulse-modulated to assess camera response times and the device can be synchronized with video frames. Narrow bandpass interference filters can be placed between the objective lens and the LED source to produce monochromatic light without affecting the spacing of controlled light intensities since emission spectra do not shift appreciably over the range of LED powers chosen in this design. Results of tests using controlled light intensity and uniform illumination are presented.     

基于椭流线法的LED射灯菲涅耳反射器设计

基于非成像光学中的边光原理和椭流线理论提出一种菲涅耳反射器设计方法。通过对光源的通量均分、椭流线虚实焦点的配对,以及光学仿真优化三个步骤实现对LED射灯二次均匀配光。该方法可避免引入色散,降低光学设计难度,并实现在目标面上光照度分布均匀的投射效果。模拟考察了距光源3m远,直径为1.2m的圆形平面上的实际效果,其中包括目标面上的照度分布和均匀性、安全性、机械加工公差等相关方面,仿真结果表明,设计是安全、可靠和可行的。     

Using the Hilbert transform for 3D visualization of differential interference contrast microscope images

Differential interference contrast (DIC) is frequently used in conventional 2D biological microscopy. Our recent investigations into producing a 3D DIC microscope (in both conventional and confocal modes) have uncovered a fundamental difficulty: namely that the phase gradient images of DIC microscopy cannot be visualized using standard digital image processing and reconstruction techniques, as commonly used elsewhere in microscopy. We discuss two approaches to the problem of preparing gradient images for 3D visualization: integration and the Hilbert transform. After applying the Hilbert transform, the dataset can then be visualized in 3D using standard techniques. We find that the Hilbert transform provides a rapid qualitative pre-processing technique for 3D visualization for a wide range of biological specimens in DIC microscopy, including chromosomes, which we use in this study.     

Measurement of the optical thickness of transparent tissue layers

The method of Due de Chaulnes was employed to determine the mechanical and optical thickness, as well as the refractive index, of transparent tissue layers in living specimens. To this end the reproducible accuracy of the method and its dependence on the adjustment in focusing and on the numerical aperture of the objective was evaluated on test specimens using the procedures of transmitted light, phase-contrast (PC), and differential interference contrast (DIC) microscopy. The best working conditions were then applied to the actual measurements.     

Laser scanning microscopy of surface spread polytene chromosomes

A new type of a Laser Scan Microscope (Zeiss) was used for the analysis of the band-interband pattern of polytene chromosomes in Chironomus. In contrast to the previously used techniques of transmission light and electron microscopy, we used differential interference contrast (DIC) in incident light to depict the pattern. Instead of using common squash preparations, we carried out this investigation with surface spread polytene (SSP) chromosome preparations of salivary glands. The combination of techniques used enabled a more detailed light microscopic presentation of polytene structures in individual preparations than conventional techniques used so far for chromosome mapping.     

基于光敏耦合定时器的压频转换器的实现

研制了基于定时器的压频转换器, 电路主要由工作于非稳态多谐振荡器模式下的定时器LM555和两个光敏电阻构成. 由于数字存储振荡器测得的定时器输出波频率与所施加的输入电压基本呈线性比例关系, 所研制的转换器为类数字输出, 因此具有线性输入/输出关系、 体积小、 易携带和高性价比等优点. 此外, 定时器输出波可以直接与PC机、 微处理器或微控制器相连, 不需要模/数转换器就能完成对输入电压信号的进一步处理.     

3-D reconstruction from optical sections of the traps of the nematophagous fungus Arthrobotrys oligospora

A technique is described for the 3-D reconstruction from serial optical sections of the traps and invasive hyphae of the nematophagous fungus Arthrobotrys oligospora, using differential interference contrast optics and 3-D acquisition and reconstruction programs on an Apple Macintosh microcomputer. The technique preserves the true morphology of the trap, enables its complex arrangement to be correctly interpreted, is non-destructive and uses relatively inexpensive hardware.     

LED粘片机运动摆臂的优化设计与分析

LED粘片机在正常工作时,摆臂往往存在运动不平稳、振幅较大及趋稳时间较长等问题,影响粘片效率与精度。通过分析摆臂的整个运动过程,提出新的设计方法。首先,利用5次多项式运动曲线来替代梯形运动曲线,保证摆臂运动过程的平滑性;其次,结合静力学分析、模态分析及瞬态动力学分析,对摆臂进行外形优化设计;然后,为减少摆臂转动惯量对运动的影响,对摆臂进行拓扑优化,得到摆臂的优化模型;最后,通过瞬态动力学分析验证,证实了此方法的可行性。     

Light microscopical detection of single 5 and 20 nm gold particles used for immunolabelling of plasma membrane antigens with silver enhancement and reflection contrast

To detect plasma membrane antigens, cytocentrifuge preparations of the macrophage-like cell line P388D1 were incubated with monoclonal antibodies and labelled with 5 and 20 nm gold particles conjugated to immunoglobulins or protein A. The 20 nm, but not the 5 nm, particles could be observed by reflection-contrast light microscopy. Single 5 nm particles, however, were clearly demonstrable with silver contrast enhancement, both in absorption contrast and in reflection contrast. The method proved to be compatible with cytochemical methods such as acid phosphatase.