Papers by Keyword: Charge Coupled Devices (CCD)

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Authors: Dong Xiang Shao, Guang Lin Wang, T.Z. Cui, H.C. Zhu
Abstract: This paper introduces a method of auto focusing based on fuzzy-control. Using this method, we design the scheme of optimization for focus. Variance function is used as approximately evaluate function for a large-scale in this system, and Square-gradient function is used as precise evaluate function in certain scale. Fuzzy-control is adopted the control of optimization for focus. The experiment testified that auto-focusing in this system is so accurate that accord with the required precision, and the image of collecting is clear. The machine of auto-focusing is simple, and the control of whole system is easy to implement.
Authors: S. Iqbal, Anand Krishna Asundi
Abstract: A Multipoint Diffraction Strain Sensor (MISS) with the novel feature of simultaneous strain measurement at multiple points is characterized. Unlike conventional interferometry based systems, this patented sensor uses principles of diffraction to directly measure strain at large number of points. In this sensor, a high-frequency diffraction grating is illuminated by two symmetric laser beams and the diffracted beams are sampled on a CCD camera via a micro-lens array into an array of dots. The shift of the individual dots is sensed and strains or rigid body tilt are calculated directly. This novel technique is expected to be very valuable in numerous industrial applications.
Authors: Hua Guo, L. Bai, J. Liu, Y. Shi
Abstract: This paper adopted the photoelectric micro measurement system based on CCD which was independently developed by Laboratory of Process Automatic and Detection Harbin Institute of Technology to detect dimension of the small precise parts. Under the various focusing status, it was discovered that articulation of focusing has huge effect on the measurement of measurand. According to the characteristics of measurand, we adopted the entropy function as the evaluation function of automatic focusing, developed a special software to process entropy value of the picked images, and obtained the relationship of focusing evaluation function and measurement error through a large number of experiments. The experimental result effectively verified the effect of articulation of focusing on dimension measurement.
Authors: John Österman, Anders Hallén, Mikael Jargelius, Uwe Zimmermann, Augustinas Galeckas, Bo Breitholtz
Authors: Qi Zhu
Abstract: Using high-resolution CCD chip and high-speed A/D converter chip, the design of the Video Communication System is given in this article, which successfully realizes the drive of the high-resolution area CCD and achieves the digital image signal. Based on the thought of SoPC’s (System on Programmable Chip) high integration, on the ALTERA company's DE2 platform, FPGA is used to achieve the driving timing of CCD, Silicon delay lines are used to properly align the pixel rate CCD clock signals with respect to one another, and the push-pull transistor circuits are designed to translate TTL level driving clock signal to the voltage levels required by the CCD. The system demonstrates some application values by analysis.
Authors: Z. Cao, Xi Chen Yang
Abstract: In this paper, a measurement system of temperature field in laser molten pool by CCD based on DSP is presented. The paper also presents the system of hardware, software process, and the method of image processing by DSP. To solve the real time problem in the processing of measuring the temperature field, the system uses DSP as the main CPU, processing the image without a computer. By this method, the system can become simple and efficient and measure the laser molten pool temperature field quickly and exactly. Gradient image of temperature field is displayed on LCD after real time processing by this system. The final picture of temperature field can be directly analyzed.
Authors: Xi Chen Yang, N. Yang, Z. Dong
Abstract: Laser direct manufacturing and re-fabricating have been used in many important fields in recent years. However, simulation and measurement of velocity fields in carrying gas and powder particles are still a challenge. In this paper finite difference method has been selected to simulate the velocity fields of powder/gas fluid. A novel DPIV system has been developed to measure the velocity fields. The DPIV system mainly consists of Nd+:YAG laser and CCD camera. Comparing the result of DPIV measuring with computer simulating, a good agreement can be obtained. After further developing, DPIV will become a useful device for laser manufacturing.
Authors: Yu Mei Luo, De Jin Hu
Abstract: This paper deals with an on-line mismachining error measurement for curve grinding based on digital image processing. Using CCD camera, the contour of the workpiece’s finished surface is captured and the image is preprocessed for denoising and edge detecting. The worktable is guided by the image of the finished workpiece to follow the path of the finished contour and then the real curve of the finished workpiece is measured by fitting a curve according to the moving path of the worktable. Finally, the machining error is obtained by comparing the measured curve with the theoretical curve of the workpiece. This method is applied to a CNC curve grinding machine MD9040. A measurement experiment is given. The experiment results show that the measurement method offers high detection precision and can be used in wide fields, especially for measuring the parts with complex curve.
Authors: Wen Li Wei, Xiu Fang Yang
Abstract: A kind of dynamic tracking system for conducting high accuracy measurement of transparent liquid concentration is designed by means of line matrix CCD receiving fringes in accordance with the relations between liquid concentration and refractive index as well as the relations among refractive index, interference light wavelength of optical fiber F-P interferometer and grade orders. The detecting system can recognize or detect 0.01% of concentration variations via measuring a group of alcohol.
Authors: Yong Hong Zhang, Hui Qiang Tang, Quan Lin Bu, De Jin Hu
Abstract: An on-line image measurement system for curve grinding was schemed out according to the working process. Because of interaction between detection precision and field of view, it is difficult to realize high detection precision at a large field of view. In order to settle this problem, a detection method based on circular tolerance zone was presented according to grinding process and wheel shape. Real-time images of work piece can be gathered while using synchronal control and outer trigger technology. Using curve fitting method, the work piece image edge can be located to sub-pixel values. Experiments show that the proposed method in this paper is effective, and its detection precision and results are reasonable.
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