Proceedings Volume 3558

Automated Optical Inspection for Industry: Theory, Technology, and Applications II

Shenghua Ye
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Proceedings Volume 3558

Automated Optical Inspection for Industry: Theory, Technology, and Applications II

Shenghua Ye
View the digital version of this volume at SPIE Digital Libarary.

Volume Details

Date Published: 10 August 1998
Contents: 7 Sessions, 117 Papers, 0 Presentations
Conference: Photonics China '98 1998
Volume Number: 3558

Table of Contents

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Table of Contents

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  • Visual Inspection I
  • Visual Inspection II
  • High-Speed Optical Inspection Systems
  • Novel Inspection Algorithms and Architectures
  • Automated Inspections I
  • Automated Inspections II
  • Automated Inspections III
  • Automated Inspections II
Visual Inspection I
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New 3D profilometry based on modulation measurement
Xianyu Su, Likun Su, Wansong Li, et al.
This article propose a new optical method for 3-D profilometry, it is not based on the conventional method of structured light triangulation, but on modulation measurement(we briefly call it MMP). Its main advantage is that it can measure the surface of a testing object in the same direction of projecting light, so it has no the difficulties due to shadow and spatial discontinuity that exist in PMP and FTP methods and needn't to know the phases. We have measured some objects to verify this method and got some meaningful results. The results proved that this method can be useful to 3-D profilometry .. 3-D sensing machine vision and so on.
Experimental study of determining the optical properties of glass online
Yufeng Liu, Weihong Bi
The system of determining the optical properties of Glass on-line is proposed. The system can determine the transmission ratio, the defects size and type. According to the optical refraction, scatter and absorption, the defects can be divided to the seed, cord or stone. The resolution of the size of the defects is 10 micrometers .
Design of image scanning and sampling system for 3D laser radar
Zhi Hong, Wei Wang, Zhinhua Gao, et al.
An active three dimension imaging laser a radar based on phase comparison technique, using an amplitude modulation cw laser diode source was established, its optical scanning system consisting of a nodding mirror and a 4-facet polygon rotor is analyzed in detail, 3D image sampling systems with real time range nonlinear calibration, light intensity-phase compensator and RS422 standard sending interface was realized. The 3D laser radar had demonstrated successfully and reliably in field test of autonomous land vehicle.
Automonitoring the status of a mobile microsphere
Hao Yin, Baixuan Shi, Caifeng Li, et al.
A method of digital image processing which is used to monitor the status of mobile microsphere automatically is described. It includes dynamic status image capture and correlation arithmetic calculation. Experiments with this method are carried out. The result are analyzed also in this paper. The sticking microsphere can be distinguished from the moving one.
Technology of online spectral response measurement
In this paper, several automatic system for determining spectral response of photocathodes are described. Some of them are use in on-line spectral response measurement. The technology of the on-line measurement is introduced and some experimental results are given. As a result, the technology is proved to be convenient and efficient.
Online turbidity measurement using light surface scattering
Zhi Hong, Chengfang Bao, Wenfa Qiu, et al.
On-line turbidity detecting is widely used in water purifying control and waste water processing. In this paper, scattering turbidity measurement is analyzed in terms of Mie scattering theory. An on-line turbidity measurement system using surface scattering technique was established. The receiving optics was elaborately designed to reduce the influence of sample's watermark change. The turbidity accuracy of smaller than +/- 5 percent was obtained over the range from 0 to 1000 NTU.
Visible automeasurement of positional accuracy to complex objects
Bangxin Shen, Changhui Tian, Min Tang, et al.
This paper offers a method to inspect the positional accuracy of the geometric factors on the gear wheel frame of the bit drilling well automatically with a photoelectric image. One non-structured light is adopted as an illuminant. Two CCD cameras are installed at an accurate position. The perspective image can be input into a computer, and the parameters of outlines measured object can be found by means of the verge operator. Applying this method of an inverse perspective transformation, the space locations of those points, lines and planes can be determined in the 3D coordinate. According to require the relations of the position between the parameters on the object those values of relations can be calculated through solving space equations. In fact, it is an available way.
Topography measurement by changing distance
Yingjie Yu, Pengsheng Li, Xifu Qiang
The paper describes the method to get a small sampling step by changing the distance between light point in the heterodyne interferometer. And it gives the method to measure topography. Finally, it analyzes the measurement error.
Photoelectric detection of the position of electric transmission contact net in electrification railway
Guohua Cao, Lizhong Zhang, Tao Jiang, et al.
This paper deals with anon-contact photoelectric detection principle on the position of electric transmission contact net in electrification railway. Both vertical distance and horizontal deviant of the electric transmission contact net is measured simultaneously by using planar array CCD components and adopting triangle indirect algorithm. We analyze systematically call kinds of factor effecting measurement accuracy and put forward a calibration method decreasing error, and we also introduce circuit principle and digit processing algorithm.
Scannerless laser three-dimensional imaging method
Huimin Yan, Zukang Lu
In this paper is presented an operation concept of sine wave and square wave correlation mode for the scannerless laser 3D imaging system based on opto-electric correlation range array implemented with a gain-controllable image intensifier. The intensity of light source is sinusoidally modulated while the gain of image intensifier is squarely modulated by means of gating photocathode. The equality of sine-square wave correlation mode with the dual sinusoidal wave correlation mode is shown. The simplicity and feasibility of photocathode gating method is demonstrated.
Measuring rotation angles in high speed with laser interference
Zhigang Fan, Shiwen Xu, Funian Long, et al.
In the existing techniques of measuring rotation angel sin high-sped, the resolutions of measuring rotation angles and the rotation velocities are restrictive for each other. In this paper, a neoteric measuring method is proposed, to which the double-frequency heterodyne interference technique and spiral metal reflector were applied, and it could improve the restrict of the rotation velocities.
Precision navigation sensor using position-sensitive detector for automatic navigation vehicle
Wenwei Zhang, Shengjiang Chang, Jinyuan Shen, et al.
This paper describes a precision navigation sensor used for real-time navigation in which position sensitive detector is used. According to the features of position sensitive detector, the special floor mark stuck on the predefined path is developed. In addition, the formulae for the centroid of the light intensity of the image of incident laser line of position sensitive detector determined by the relative position between the floor mark and the navigation senor is derived. The navigation sensor, which can obtain high navigation accuracy and proper controlling signal, navigates the automatic navigation vehicle running on the predefined path. It is suitable for application in automatic navigation vehicle and other automatic instruments. The experimental result are given.
Visual Inspection II
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Method of dynamic geometric parameter measurement by laser tracking system
Yongdong Liu, Jia Wang, Jinwen Liang
The main methods for measuring geometric parameters are used to be static or quasi-static measurement. Recently, however, dynamic geometric parameters measurement has been becoming increasingly important and turning into a new field in metrology. The laser tracking system for measuring dynamic geometric parameters of moving targets employs laser dynamic aiming technique, laser interferometry and control technique of precision instruments. The moving target is tracked and its geometric parameters are measured in real time. The measurement range is one to ten meters and the accuracy is fifty microns per meter. It is a novel computer integral system with both measuring and controlling capacity. This paper present the characteristic and concept of dynamic geometric parameters measurements and puts forward the cardinal measuring principles and methods of the laser tracking system. This paper also gives a more detailed discussion about the key techniques for this system, which are different from the static measurement, such as the self- calibration principle, the redundancy design principle, the fault-tolerant design principle, the virtual coordinate system establishment principle. We will also discuss the developing trend of laser tracking system for measuring dynamic geometric parameters at the end of the paper.
Computer-vision-based auto-alignment drilling machine for PCB
Yuekang Shan, Chang Xu, Qing Jiang
This article introduces an auto aligning drilling machine for PCB based on computer-vision. Furthermore, the tec. such as perfectly real-time inspection of image center based on least square method, two-directional mechanism resume, auto- calibration and auto-correction home is also included in this article. The accuracy of drilling is analyzed. It was indicated by theory and re-inspection that the accuracy of drilling machine is smaller than 25 micrometers , repeatability is smaller than 5 micrometers . So we can say that it is good to meet the demand of high accurate positioning hole of PCB.
Automated optical inspection for high-speed electron in synchrotron accelerator
Congliang Guo, Tonghui Liu, Rongsheng Wang
Automated optical inspection for accelerated electron beam in synchrotron accelerator or storage electron beam in storage ring is important method of electron beam diagnostic.It is also the very convenient aided method for us to se the real beam size and structure. In this paper, we will discuss the physical characters of detector and cable in both of electromagnet wave and photon beam. Our main study is how to measure the signal finest and how to transfer signal data into computer on-line fast enough. The system signal is relative to transfer model and photon sensor, and it is so easy to find a good real time beam signal for us to see moveable electron beam image as best as the system does. We can analysis the beam character and its parameters in one smart system. At the end, we introduce some analysis result and new design ideas. it will have more potential prospects on industry application and other applications.
Automation of temperature measurement by laser
Yue Fei, Yangang Xi, Yuanjie Chen, et al.
Temperature measurement by laser is an advanced method for measuring the temperature of optical material in vacuum or any heat insulation situations. It is accurate, rapid, non- touching and non-contaminate. But up to now, it can only be done by manual counting the laser interference fringes, which restricts the wide application of the method. Normal fringe counter can not be used, because the whole laser spot with the fringes often moves during the heating process. Using a CCD-camera and special computer software, we developed a real-time measuring system that can track the spot automatically, and currently show the temperature-time curve. The design, feature, setup and application of this measurement system are described and discussed.
Application of TDICCD on real-time Earth reconnaissance satellite
Qiaolin Huang, Xiangmin Li
This paper highlights the application of time delay integration charge couple devices (TDICCD) on real-time earth observation camera. From the angle of the design of space camera, it introduces how to compute the integration time, number of focal pane array photon detectors, video bandwidth, and signal-to-noise ratio. An example is also given. Two dynamic TDICCD imaging instruments are manufactured using the 'push-broom' imaging principle, and their confident performances are also achieved.
Method of one-dimensional optoelectronic high-speed detection on two-dimensional temperature field
Qi L. Wang, Jianxin Chang, Jianliang Jiang, et al.
In this article, we have given a real-time, high-speed, convenient, economic opt-electronic detecting method of 1D on 2D temperature field. To avoid the great expenditure of high-speed area CCD, we use coherent fiber bundle, and transform a 2D temperature image into 1D spatial optical signal. After it is fed into high-speed line CCD, the original 2D temperature field will be further processed on computer. With this, 2D temperature field will be further processed on computer. This method has been applied to the investigation on temperature measurement of combustion engine,and the frame frequency of this system has reached at 7kHz.
Visual measurement on BGA chip leaders
Shenghua Ye, Yu Qiu, Changku Sun
Sometimes the objects of isolated surfaces, such as BGA chip leaders, need to be dealt with. Here, a method of visual measurement is proposed for on-line measurement. An image split-splicing technology is developed next to the theory of the system is analyzed to develop the test speed while keeping the resolution. Based on the theory, an isolated surface measurement system is formed for gauging the BGA leaders' top coplanarity.
New method for real-time monitoring of laser power and mode online
You-qing Wang, Chengwu An, Shuzhong Gao, et al.
A new real-time measuring method, which can simultaneously monitor laser power of 10-1500 W and mode on line has been proposed in detail. The experimental result are in well agreement with the real situations and is very useful in high power laser applications in industry.
Experimental study of vibration measurement based on laser frequency splitting principle
Yi Zhang, Zhibeng Deng, Yanmei Han, et al.
A new method of measuring vibration is presented based on HeNe laser frequency splitting phenomenon and a series of experiments have been done. While a quartz crystal wedge which vibrates with the vibration of measured object is inserted to a HeNe laser cavity, each laser mode is split to two orthogonal laser modes with a frequency difference. The variation of the frequency difference is proportional to the displacement of the quartz wedge so that the frequency difference is modulated by vibration displacement signal. The vibration signal is demodulated to electrical signal through a photo-electric detector and signal processing circuit. A computer is used to adopt and analyze the vibration signal. By the system a 15nm resolution and 28nm repeatability of vibration amplitude are obtained. The method has good potential prospective to be applied in high resolution, low and middle frequency vibration measurement or random vibration measurement.
Online inspection system for steel-plate thickness
Guoyu Zhang, Jiawu Song, Zhiyong An, et al.
Based on the laser inspecting technology and optical triangulation measuring principle, an on-line inspecting system for steel plate thickness was presented, which is an optoelectronic inspecting equipment used non-contact on-line automatic measurmg thickness of rolling steel plate in steel industry. The system used two semiconductor laser probes to realize the measurement of steel plate thickness. The measured result of steel plate thickness is directly given out. According to the request of on-line inspection, the system can make real-time processing for the measured data, and provide analog or digital feedback control signal to realize the closed loop control for rolling machine. In addition, the system has also many functions such as correcting system errors, acoustic and light alarming for exceeding the tolerance .limits, displaying and printing measured results etc. In this paper, the overall structure, working principle and optoelectronic information as well as data processing electronic system of the system were described. The theoretical problems related to the design of the system were discussed in detail.
Measurement technology of ultrafast optoelectronics
Jilong Wang, Yuncai Wang, Shijie Chen
This paper reviews recent progress in ultrafast optoelectronic measurement techniques utilizing ultrafast optical pulses, with particular emphasis on the wide range of novel applications of ultrafast optoelectronics for generation and measurement of ultrafast electrical signal. Such specific high-speed optoelectronic measurement techniques as photoconductive sampling, electro-optic sampling, picosecond photoemissive sampling etc. are described.
New inline field tester on visual distance of night vision instrument with faint light
Zhibin Chen, Yong Zhang
An important problem in-line visual distance testing of night vision instrument with faint light under the condition of field environment is put forward on the basis of practical use in this paper. Based on theoretical analysis through visual distance evaluation, some key parameter which affects visual distance testing are pointed out. And practically mathematical model used to evaluate visual distance is built up. Some problems which require the instrument with small volume, lightweight, long focal length of parallel light pipe to simulate target and high quality imagery etc. have been solved by using Carthegreen's design techniques, faint light luminous devices and high accuracy processing technology to resolve pattern etc. in this instrument. Also, by adding lightproof black cavity and using computer testing technique, the testing accuracy and computerization is greatly improved.
High-Speed Optical Inspection Systems
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New scheme of high-precision visual collimator
Zhaoxiang Ge, Han Ying, Lei Chen
Machine manufacture and installation, special constructional engineering and precision engineering surveying need a very high precision collimator. In the text, we discus a plane focusing visual collimator, which had been specially made for the synchrotron accelerator. Using an electronic spirit level as the reference element, CCD automatic aiming system, photoelectric readout device and computer processing technology, the new visual collimator has a much higher precision and can be used more quickly, more conveniently and more reliably.
Television automatic video-line tester
Zhaoxiang Ge, Dongsheng Tang, Binghua Feng
The linearity of telescope video-line is an important character for geodetic instruments and micrometer- telescopes. The instrument of 1 inch video-line tester, invented by University of Shanghai for Science and Technology, has been adopted in related instrument criterion and national metering regulation. But in optical and chemical reading with visual alignment, it can cause subjective error and can not give detailed data and so on. In this paper, the author put forward an improvement for video-line tester by using CCD for TV camera, displaying and processing CCD signal through computer, and auto-testing, with advantage of objectivity, reliability, rapid speed and less focusing error.
Active trigonometry and its application to thickness measurement on reflective surface
Hong Miao, Xiaoping Wu
The paper introduces a novel method to measure accurate thickness. On the basis of the principle of active trigonometry with vertically incident mode, an obliquely incident mode is proposed. The method is specially designed for a reflective surface of an object, such as a thin steel plate, to measure its thickness in real-time. The influence of the small deflection which is caused by mechanical vibrations is discussed and the manner to reduce this influence is given too.
Interference measurements for roughness of silicon mirror with Twyman interferometer
Yaoning Zhang, Xiaoli Zhang, ZuHai Cheng
Supposed the random distribution of height deviation can be represented as Gaussian distribution, the relationship between intensity contrast C of interference fringes, determined at Twyman Interferometer, and the roughness (sigma) of mirror's surface is deduced. Roughness measurements of four silicon mirrors have performed with Twyman Interferometer. The result of measurements is agree with the data, measured by 6JA profiler in tendency. This method is a full-field, noncontacting interference measurement so that it can be developed as an inspection on line. Then, the surface profile analysis can also be performed from interference fringes. Therefore this method provide a controlling way in polish process.
Displacement quantity test and measurement system with the laser light triangle method
Guiying Li, Dianren Chen, Zhenlin Du, et al.
The principle of noncontact displacement quantity test and measurement with the laser light triangle method and CCD driving circuit design with automatic adjusting light integration time function are introduced in this paper.
Probe imaging vision coordinate measuring system using single camera
Zhi-jiang Zhang, Qingcheng Huang, Weiguo Lin, et al.
The study describes a new vision coordinate measuring system - probe imaging vision coordinate measuring system using single camera. It proposed a new idea in vision coordinate measurement with a known objective-probe to contact with the surface to be measured, deduces a linear model for distinguishing six freedoms of the objective-probe and gaining the coordinates of the contacted point on the surface to be measured. The study analyzes some factors which affect the resolutions of the system. Simulations have shown that the system model is valid.
CCD-based microscopic measurement system for precision part geometry error
GuangLin Wang, Dawei Chen, Chongde Tao, et al.
In this paper, the CCD-based microscopic measuring system is designed and produced to make measure of geometrical error of precision micropart, e.g. dimension, shape and location errors. The system consists of the tool maker's microscope with the CCD camera, the image acquiring board and the PC processing digital image. The algonthm and software used for computer digit image processing are discussed, e.g. establishing the threshold vale using the maximum variance method, two-valuing the image, removing the noise of the image and drawing the edges. The calibration of system is introduced and the measuring error of the system is analyzed. The practical measuring example is given. The experiment results in the conclusion that the system has come to practical use in measuring dimension error, coaxial one and roundness one of the precision microparts; its resolution is 0. 1 m; its repeatability is less than 0.5m. It is pointed that the better optical microscopic amplifying system and the CCD camera with higher resolution will make the measurement of the system more accurate, and the further perfection of algorithm and software will result in the system having more functions.
Development of an optoelectronic instrument for detecting roundness of internal surface of artillery barrel
Ying Che, Yuzhi Shen, Jiong Liu
An optoelectronic detecting instrument is introduced, in which the charge-coupled device is used to detect the roundness of internal aperture in artillery barrel. In this paper, we expound the working principle and the design idea, and analyze the measuring error of it.
Parallel confocal detection method for three-dimensional surface topography with a micro-optic component
Weijian Tian, Zhengkang Bao, Zhihua Ding, et al.
The parallel confocal method for detecting whole-field 3-D surface topography is proposed in this paper. For the realization of the method, in the confocal optical system, the micro-optic array component composed of a microlens array and a matched pinhole array has been introduced to produce a symmetrical micro-array source. Thus, it can be performed to paralleling measure the tested object surface at the same time with the multi-detecting light beams. The method fully and successfully shows the advantage of optical parallel processing in the confocal system, and overcomes the problem of a long-period scanning required by the original confocal system, from which deviations occur. Meanwhile, some experimental results with the parallel confocal detecting method are presented in the paper.
High-accuracy optical prismatic scanner and its application to the measurement of large-axle angularity
Xianhe Zhang, Youbin Fang, Jiaxiong Ye
The principle and structure of linear rectangular prismatic scanner are analyzed. The linear scanning shift-mathematic model of the scanner is derived in this paper. By analyzing, we show that if the parameters of the scanner is selected correctly, the maximum linear scanning deviation can be controlled in a small interval. The angularity measurement accuracy of large axle can reach submicrometer level.
Laser diffraction measurement
Duogang Ran
In the first part of the paper, the distribution of pattern of single slit diffraction with Gaussian beam is discussed, that shows for ideal Fraunhofer diffraction with Gaussian beam the positions of diffraction minima append a nonlinear term compared with imiform coherent light diffraction and the pattern of Fresnel diffraction will approach to Fraunhofer 's as the order of pattern increases to high level. In the second part a improving scheme is introduced which can reduce all king of measuring noise and the nonlinear error arising from Gaussian beam and deviating from ideal Fraunhofer diffraction effectively. Two set of experiment results are presented in this part that shows the measuring accuracy can reach to Ad Id <0.2% and available range to the sizes to be measured can be extended to d =0.05 0.8mm without any adjusting and it can be extended to 0.025mm by simple adjusting. In additional, the scheme has very simple structure suitable for engineering application, especially for on-line measurement.
Optical method of measuring the thickness of optical films in devices
Yunsheng Qian, Rongguo Fu, Denggao Xu, et al.
When the films in the optical or photoelectric devices are produced, usually their thickness is an important parameter. The optical method can be used to measure real-time thickness of films if films are producing on the transparent substrates. Based on thin optics, the principles of measuring thickness of optical films by optical method are expounded in the paper. The measuring instruments are developed. The instruments can measure real-time the optical reflectivity of films during producing them. By processing and analyzing data the thickens of the films can be estimated. The measuring system has been applied in the courses producing experimental tubes and image intensifiers. The measured results are given and analyzed.
Large-scale form and position error measurement
Qun Hao, Dacheng Li
A research on measuring form and position deviations of large scale dimension using laser diode, optical fiber and phase plate diffraction alignment technique and a matrix CCD detecting technique was proposed in this paper. The principle of laser alignment using a (pi) step phase plate was analyzed theoretically and calculated using a computer numerically. Also in the paper, the operation principle and signal processing methods of a matrix CCD that used to detect the deviation absolutely were stated. It was emphasized on introducing some of large-scale form and position errors measuring system and the measurement accuracy of these systems are given. The comparing experiment result with HP5528 exhibited that the accuracy of the system coincides with the one of HP5528 in the straightness measurement.
Detection system of the dynamic starting characteristic of an electric motor
Lu Song, Fucang Yen, Xiaoman Wang, et al.
The characteristic of direct current servo motor is function stable, noise low, and easy control, therefore, it was applied more and more widely. The measurements of motor's dynamic start characteristic is even more important in some special applied occasion. Certainly, it is impossible that old measure device of motor turning speed. This paper introduced structure and measuring principle of the system. This system used photoelectric method to detect signal. In this system semiconductor laser is used as light source, and high sensitivity photoelectric tube is used to receive signal. The system finished dynamic measurement and record under the intelligent unit coordination. The paper gives experiment record and measurement result. This measurement device has been applied in the field of laser communications widely.
Research for the cylinder edge-checkout models
Haibao Lu, Tingzheng Shen, Weihong Zhou, et al.
In the paper, two general theoretical models of a cylinder edge-checkout with white light scanning and laser scanning are established. The simulation for the models is performed by means of a computer and their simulating curves are obtained respectively. The factors that affect the sensitivity of the cylinder edge-checkout are also analyzed. Besides, the correctness of the two models is inspected with three kinds of edge-checkout methods.
Modeling and simulation of optimization design for structure parameters of CCD intersection measurement system
Haibao Lu, Huayong Yang, Wusheng Luo, et al.
In order to obtain high measuring accuracy, a method of optimization-design is established. Then the computer simulation for the model is introduced. Finally, as results, the optimum structure parameters corresponding to two kinds of target-planes with different size are tabled. In addition, a group of 3D figures of the error distribution are given.
Computer-aided internal thread parameters testing
Dawei Tu, Jing Tao, Shan Qi
A novel device for testing internal threads' parameters is presented in this paper based on light sectioning approach, in which a line-shape light is projected on the internal surface of the tested thread, the distorted line is recorded and digitalized by a CCD camera, and a computer is used for further processing. A prototype system is built. The experiment results show that the accuracies of 10 micrometers for pitch measurement, 15 inch for tooth angle measurement and 15 micrometers for pitch diameter measurement have been achieved.
Optoelectronic noncontact inspection method of taper
Guoyu Zhang, Zhiyong An, Huilin Jiang, et al.
Through the measurement of radial and axial dimension for cone, the non-contact measurement of taper is realized by using an optoelectronic inspecting system, which is composed of a laser-scanned measuring system, a grating displacement measuring system and a servo control system. Under microcomputer control, the three system make data exchange and control information conveying each other by communicating interface, and synchro control executive mechanism, they can realize the measurement of taper. The two diameters of the cone were measured by the laser-scanned measuring system, the axial dimension of the cone was measured by the grating displacement measuring system, through the computer real-time data processing, the taper of the measured cone was given out. The measured result was displayed or printed output. The measuring method has many features such as high speed, high accuracy and non-contact automatic measurement etc. It has great applicable prospects. In this paper, the measuring method of taper, the overall constitution of the optoelectronic inspecting system and the working principle were discussed in detail, the accuracy of the optoelectronic inspecting system was analyzed, and the practicability of the measuring method was verified by experiments.
System of photoelectric automeasurement of internal diameter
Tong Song, Xinyang Lin
This paper discussed the sytsem of a photoelectric auto- measuring which is used to measurng size of the internal diameter. In this system incldue the charge coupoled devices CCD measuring unit, signal procesing unit and micro-computer controllign unit, to realize non-contact measurement. Ppaer gives structure and principle of the system, specially gives the method of increasing stability of system.
Stereo-vision system for measurement of 3D object
Wenyi Deng, Naiguang Lu, Jingcheng Zhuang, et al.
On the basis of photogrammetry, a stereo vision system has been built for 3D profile measurement. It consists of two CCD cameras, a frame grabber and a personal computer. It will be extensively used in industrial inspection and robot vision, etc. In this paper the calibration of system, the measurement procedure of a 3D object, experimental results and the factors to affect the accuracy are discussed in detail. The stereo vision system needn't precise alignment of optical system and precise measurement of system's parameters in advance. It is suitable especially for the noncontact measurement of large scale objects with complex surface.
Application of Twyman-CCD computer system in automeasurement displacement
Wensheng Wang, Yang Xiang, Haicheng Zhang
Used He-Ne laser as a light source, CCD camera as the detector of Twyman-Green interferometer, a Twyman-CCD- Microcomputer systems is consisted. With this setup, high accuracy, non-contact, real-time, auto-measuring displacement is realized. As a practical example, the shrinking of 2- components adhesive is measured for a company.
Three-dimensional profile measurement by using an artificial neural network
Naiguang Lu, Wenyi Deng, Shaofeng Sun, et al.
This paper introduces 3D profiles noncontact measurement method by using a kind of artificial neural network- backpropagation network. It makes a detail discussion on optical system, data acquisition, and how to train the BP network. An object is projected by a laser stripe light, and the lien image of the object is captured by a CCD camera. The input data of BP network is given from a series of image on CCD by certain image processing technology. Once a mapping relationship of coordinates between CCD camera image plane and related position in object's space is set up by sing BP network, the image plane coordinates of any objects are used as the input data of BP network it will immediately obtain the corresponding coordinates in space according to the output. Thus the profile can be easily established by these coordinates. This method reduces the requirement for system accuracy, and no need to test and a light the whole system in advance accurately.
Nonlinearity of optical triangulation
Xinming Zhang, Yongxin Sui, Jiandong Yang, et al.
After discussing the out-put characteristic of optical triangulation system in detail, some points of the relation between nonlinearity of triangulation and optical system parameters are concluded. These parameters include included angle, the magnification of imaging lens and objective distance of imaging lens. Then, to correct the nonlinearity a new method-asymmetrical gains method has been developed, the principle and the theoretic calculation result are given eventually.
Photoelectric automeasurement system for shape and position
Weina Liu, Jinsong Xie, Jiandong Yang, et al.
This paper discusses a main unit of photoelectric automeasurement system for shape and position which is composed of slit scanning optical system with semiconductor laser and fine servo mechanical system. A single chip micro- computer, real-time data processor and other hardware are used to form a main controller to realize high sped, non- contact auto-measuring roundness, cylindricity, axiality and parallelism for revolving part C language is used to program for software. The computer is used for real-time data processing and controlling, displaying measuring result and printing output. Whole work of the system is done accurately and automatically with high speed. So it has good future in production.
Realization of spherical absolute testing
Qingyun Wang, Rihong Zhu, Jinbang Chen, et al.
Today, high quantities lens is more and more important to the optic-electric fields, and it brought about the demand of high accuracy testing of spherical surfaces. Absolute interferometric testing of spherical surfaces is a technical basis for establishing the spherical standard, and it is also an important application of computer aid interferometry. Partly work in the course of establishing the national spherical standard is introduced. A new method based on image processing has been developed instead of typical absolute testing which requires an eight-dimension mount whose cost is expensive and adjustment is very difficult. Interferograms sampled by phase-shifting interferometry can be processed to recognize the border of spherical surfaces. The key coefficients of position are in real time feedback to the operator to adjusting sphere precisely relative to the interferometer. This method can get more accuracy because of the high unison of three interferograms. This paper shows results of testing a 1/10 wave P-V sphere using two aplanats. It is easy to measure spherical surfaces to the accuracy better than 1/15 wave p- v.
Submicron position and measurement system for optical edges
JiaHu Yuan
Optical edges refer to the cut-lines of difference of optical transmissivity. They exist widely on optical coder. Generally the accuracy of edge's positions shows its quality. This paper describes an opto-electric measuring scheme, which integrates the edge's signal by means of linear CCD camera and identifies automatically its position through computer analysis. In the meantime a precise grating is used as measuring unit and a 2D scanning stage which is derived by stepping motors is designed for searching the edges. A microcomputer performs the functions of the system management, data sample and analysis. The measuring error is less than 0.3 micrometers .
Computer-aided testing for contact-type interferometer
Qingyun Wang, Lei Chen, Yu Zhu, et al.
Contact type interferometer is widely used equipment for testing relative length. It has been used to verify gauge block by metrology department because of its high accuracy. A computer-aided system based on it is introduced. There is a data acquisition system, including CCD and grabber etc., to detect and digitize interferograms instead of estimated by operator and avoids eyestrain. This system can analyze 2D interferogram automatically and quickly while both calibrate with monochromatic fringes and test with achromatic fringes. Many methods were used to analyze the 2D interferogram. It has been used by metrology department and its accuracy is better than 0.02 micrometers . Its resolution is better than the range per 1000 which is higher than the resolution estimated by operator. Different software has been developed to suit for different applications. One is the process-controlling software for verifying gauge block. The other is continuous- measuring software for testing tiny displacement about micron, such as measuring the responsive function of PZT.
Noncontact optical sensor for inside-diameter measurements
Xiangjun Wang, Xinyu Kou
This paper presents a new sensor method for achieving automatic non-contact fast inspections and measurements of the inside diameters or sizes of cylindrical parts with serial kinds of material in industrial environments. The method is based on optic surface reflection principle. The 2D geometric optic gouge is constructed in inside of cylinder in terms of laser diode and line scanning charge coupled device. The method has the advantage of simple and fast operation, long live for use, easy data process and error correction. The paper outlines in detail the principle of the 2D geometric optic sensor, the relation among reflection angle, position of light point on LCCD and measuring range. Some algorithms are introduced in the paper too. FInally, the actual experiment results are given.
Portable laser roughometer
Shihua Wang, Jun Wu
A portable laser roughometer based on the principle of laser scattering on machined surface is described in this paper. The laser diode and novel telecentric optical system are adopted and the light-scattering band modulated from rough surface of sample is processed by the way of half scattering band of light. So, the measuring result is insensitivity to position of sample. The measuring range: Ra value from 0.005 micrometers to 2 micrometers . The contradictory between better measuring accuracy and larger measuring range is solved effectively. Besides, sample which has special form and internal surface can be measured with different accessories. The instrument is simple in structure and easy to handle. This noncontact measuring device also has sufficient measuring accuracy for practical uses.
Calibration errors in laser-scanning 3D-vision measurement using the space encoding method
Space encoding is the effective method saving image- acquisition time in structure light 3D vision. In this paper, we propose calibration parameters, which do not include camera inner parameters, of the rangefinder using scanning-based spatial code pattern. We discuss the influence of calibration errors on rangefinder measuring. A model of the systematic calibration errors is developed based on the geometry of the rangefinder. According to given rangefinder accuracy, the limits to calibration errors are set from the model. An example is cited. Moreover, we discuss the influence of the shifting of the camera lens center and the polyhedral mirror reflecting point on the rangefinder precision.
Automated inspection of chip type using image analysis method
Xianli Liu, Hong Teng, Fugang Yan, et al.
We take the C-type chip, spiral chip and random-curl chip commonly produced in automated turn processing as the objects of study to inspect the angle of chip flow by using image recognition, the results of test shows that the changing scale of angle of C-type chip and spiral chip flow is 2 degrees and the changing scale of random curl chip flow is 8 degrees.
Novel Inspection Algorithms and Architectures
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Distortion compensation in large-FOV CCD optical measurement system
Yun Zhang, Rensheng Xiong
The CCD television and theodolite measuring system, composed by CCD camera and electronic theodolite, is able to measure spatial angles and coordinates of space targets. Optical distortion is a major factor to influence the system accuracy because of the large FOV. This paper introduces the method to compensate optical distortion. By means of establishing mathematical models to compensate the optical distortion, we can promptly correct the error of optical distortion in the course of our practical measurement. The mathematical models have two kinds of expressions, the form of integer power and the form of decimal power. Each has its advantages and disadvantages. After being corrected, the system accuracy of angel measurement is superior to 40 seconds. Compared with its original accuracy. It is improved by 7-8 times.
Exploiting potentialities of linear CCD arrays in real-time dynamic measurement
Changgui Li, Jinghai Liu, Youna Lin, et al.
It is well known that linear CCD arrays have many advantages in static measurement, but many problems exist in dynamic measurement. For example, frequency bandwidth of an optical signal that can be tested is narrow and precision of sampled values is low in the case of continuous laser used as light source for a specific linear CCD array now available. So a method in which pulse laser is used is given to solve the problems. Not only precision of sampled values is improved, frequency bandwidth of an optical signal that can be tested is also extended. Potentialities of the specific linear CCD array now available is fully exploited. In this paper, how to make pulse laser and how to design electric circuits of a linear CCD array are discussed. The key step is how to synchronize them. Then, the sampling of placement signals using linear CCD array is compared with the sampling of voltage signals using A/D converters in concept. This would give us more clear image on comprehending the important role of pulse laser. At last, dynamic range of linear CCD arrays and some problems needing solving are discussed.
Application of CCD camera to test radar-angle tracking performance
Yusheng Wang, Zhiyun Wang, Qingshan Han, et al.
This paper advances the radar angel tracking performance and index test by the system composed of the CCD camera and slice microcomputer this new method can record the error of radar angle tracking system automatically. It is used to record the target and appraise the radar tracking quality when a radar tracking is tracking the aerial target. In the measurement system a CCD camera held on radar antenna turn around radar. When radar follows a step-moving target, the coordinate of a flag light installed for the measurement system changes in the film of CCD camera. The trace of the flag light is the step-response curve of radar tracking performance.
Real-time error compensation of coordinate measurement system using combined gratings
Wenjun Tang, Yukun Zhang, Minmo Duan, et al.
This paper is concerned with enhancing the accuracy of the coordinate measurement system by compensating the Abbe error in real-time through combined gratings. This research is carried out on a 2D measuring system with a maximum moving range of 200mm X 100mm. According to its structure, a mathematical model using the rigid body assumption is deduced and altogether five metrology gratings are installed along two moving axes to compensate three angel errors according to this model. A special grating subdividing system is designed to realize 200 times subdivision for each of the five gratings. Experiment shows that this system can largely raise the accuracy of the coordinate measurement device. Besides, this research is also very valuable in the upgrading of machine tools.
Measuring the space direction of a laser beam by means of linear-array CCD
Bingqi Liu, XueJu Shen, Fu Wang, et al.
The principle of determining passive incident laser beam's space direction by use of linear array CCD deice and structural design of the system are analyzed theory and experiment show passive incident laser beam's space direction can be determined accurately and quickly.
LED automatic grader
An automatic grader with testing light intensity and forward voltage of LED is presented in this paper. It mainly includes three parts: automatic conveying, automatic testing and automatic classification of LED. Automatic conveying of LED is operated by industry controlling computer controlling vibration salver. The light intensity and forward voltage of lighting LED is measured, they are compared with set grade value and the LED's grade is determined. Then the LED is sent in relative bin by computer controlling pneumatic components and synchronizing motor.
Vibration measurements using CCD
Qingyou Wang, Liu He, Qing Guo, et al.
With the use of several high-speed and high-sensitivity linear CCD as photoelectric displacement senor, multi-point simultaneous measurement can be carried out to get vibration parameters such as vibration amplitude, vibration frequency and collision acceleration, etc. This high-precision and fast-response method takes the advantages of non-contact measuring and synchronous data sampling. The sampled data also can be displayed, stored and processed by computers.
Measuring instantaneous planar motion of rigid body with a linear CCD
Kaiming Li, Qingyou Wang, Wei Li, et al.
A high-speed, external-triggered, remote-driven linear CCD sensor and its data collecting system have been introduced in this paper. By using this system in measuring instantaneous planar motion of rigid body, we get the angular velocity and angular displacement of a rigid body or the velocity and displacement of a given point. Results from the system are well identical with that from other measuring systems.
Test of the time and space domain in three-dimensional image
Zuoming Huang, Qiushi Cong
The property test of low light level (LLL) CCD TV system is an important part in the area of LLL imaging. In this paper, the testing model of the time and space domain 3D image noise is put forward, the test and analysis system is set up. By using these the signal and noise property of LLL CCD TV system is ted and analyzed, the 3D curves of distribution of the time domain noise and the space domain noise are obtained.
Computer vision application for weld defect detection and evaluation
Yue Liu, Xiaohong Li, Dahai Ren, et al.
This paper introduces the components of the hardware, software, working principle and the defect detection capacity of computer vision system for x-ray real time radiography weld defect detection and evaluation. Meanwhile, the image processing system is studied in which an image transformation algorithm is presented for defect extraction. Moreover, a sectional curve fitting algorithm and an algorithm based on probability are proposed to locate the defects. At the end of the paper, a pattern recognition method is introduced for the automatic identification of weld defects.
Analysis of CCD output signal in velocity measurement system
The wave shape of CCD output signal, on the one hand, reflect the result of synthetic influence between CCD itself and the parts before it. On the other hand, it reflects the degree of difficulty to derive and process signals for the circuits after it. Thus, relative factors affecting measurement accuracy can be known by analyzing the CCD wave shape. This analysis not only built the foundation for measuring total error of the system, but also obtained some important designing parameters. Basis can be provided for definite relative parameters in the case of whole system designing. It can be known from the analysis that slope of the wave shape and its amplitude difference (Delta) Vs directly influence deriving the CCD signal. It also affect the measurement accuracy of the system. (Delta) Vs also relates to the number of photoelements m passed by image during the period of CCD photo-integral.
Range finding precision analysis of long-distance high-precision laser range finder
BaoYing Liu
To improve range finding precision of long-distance laser pulse radar, it can adopt dynamic launching angle controlling, dynamic error correction and precision measuring-time and so on besides contracting light pulse and improving responding speed of receiving system. This article analyzed the primary error source of a kind of long-distance high precision laser range finder which adopts the techniques above from the engineering POV. The conclusion has been proved by experiment.
Tool-damage analysis based on imaging
Xianli Liu, Bo Chen, Xiaoyang Yu, et al.
This paper researches two shapes of the tool face damage, i.e. damage and crater wear, using image analysis method. The principle of detecting them is presented; the judging standards of tool damage are given; two experiments are cited.
Technology of speed measurement by CCD
Xiaoman Wang, Lu Song, Bo Xu, et al.
The CCD camera is being used more and more widely now. In the technology of space flight, each line's distance of a picture taken by a CCD camera is in direct propagation to the ratio of the flying altitude and flying speed of an airplane when a CCD camera is taken a picture of the ground. But this ratio is constantly changed as the atmospheric changing and some reasons of the airplane. Therefore, we should measure and record the ratio on time for the purpose of reappearing the picture correctly. Because of the moving speed of a picture is related to the ratio, we must measure the speed accurately. This paper introduces the principle and the method of measuring the moving speed of a picture by means of a CCD camera. The overall structure of system, the error analyses have been given in the paper.
Automated Inspections I
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Extracting multiple lines from the Hough domain
Linsen Chen, Yang Shen, Jianfong Xie
An optimized algorithm based on the exact peak search method and the digital error reducing technique is proposed to get the complete line segments from the Hough domain. In particular, this algorithm is robust to extract the multiple lines in which the lines have high length ratio and relative close positions. The accuracy of detecting the endpoints and lengths of lines is stable. The different patterns, which have multiple lines including the long and short lines, are used as the test of the method. Results have been given.
Theoretical model for IR imaging of buried object sites
Jianqi Zhang, Xiaoping Fang, Weidong Yang, et al.
By studying 2D coupled heat and water flow within the soil layer with a buried object, a theoretical model for IR imaging buried object sites is presented. The model uses the soil surface energy and water balance equations to determine soil surface temperature. The inputs required for the computer simulations are weather data, solid thermal and hydraulic properties, and object data. Numerical experiments are performed to examine the effect of soil type, object species, and weather conditions on the variations in skin temperature, which show that the object species, object size, and burial depth can evidently affect image feature of the soil surface. The present model reasonably described the soil thermal and hydrological environments and thus can be applied successfully to IR imaging buried object sites.
Design of a measurement and control system of partial environmental illuminance
Yuefeng Wang, Yanxiong Niu, Xiaowei Guo, et al.
In order to measure and control the illuminance of a partial environment, a measuring and control system has been established. In this paper the designing principle of the system, the major structure and the flowchart of software will be introduced.
Measurement of two-dimensional vector velocity using spatial filtering technique
Ping Li, Baomin Ma, Bingrong Zhang, et al.
In this paper, we show theoretical analysis and calculation of spatial-filtering method for measurement of 2D vector velocity. About the data processing, we used A/D conversion and interfaced with a microcomputer, so that the data can be processed automatically by the microcomputer. The preliminary experiment was performed and the experimental results show the usefulness of the proposed method.
Laser-scanner-based self-localization for autonomous mobile robots using neural network
Dongbing Gu, Zhengxun Song
This paper presents an approach to global self-localization for autonomous mobile robots based on the laser scanner. There are some reflective beacons fixed in the operating environment and their coordination is known a prior.The laser scanner can detect the angle between the robot's heading and the beacon by rotating the laser and receiver, but fail to recognize the exact beacon from which the scanner receives the signal. The Kohonen neural networks have been developed in this approach to recognize the beacons based on the measurement of the laser scanner. With the three of the recognized beacons, the localization of the mobile robots can be estimated by the triangle calculation.
Quantitative detection of subsurface defects by pulse-heating infrared thermography
Mingcheng Zong, Tieying Ding, Shuwen Xue, et al.
The principles and methods are introduced to quantitatively detect the subsurface defect depth and size by pulse-heating IR thermography. The subsurface defects in different metal and insulating materials were quantitatively measured by using our home-made pulse-heating IR thermography non- destructive testing system. From our experimental results, it is shown that accurate information can be obtained during a shortly time after the surface of a target is heated by a thermal pulse. Especially for metals a fast recording of the images is required.
Using digital spatial phase-shifting technique to gain quasi-hologram
Shaoming Zhu, Xiang Peng, Zonghua Zhang, et al.
In this paper, we measure the object profile using digital Moire based on digital spatial phase-shifting technique. Perform phase unwrapping based on improved composite mask technique. Finally, add the gray image to the real coordinate 3D map of the object, we can acquire a 3D texture image of the object - the quasi-hologram of object. Theoretical analysis and experiment results are given to demonstrate the technique.
Near-field optical imaging properties by passive and active fiber probes
Guoping Zhang, Hai Ming, Ming Bai, et al.
Passive and active fiber probes, used for the scanning near- field optical microscope, show different image properties. For the passive fiber probe, a better optical image contrast has been obtained with a parabolic taper than with a linear taper. The reflected fields in different fiber tapers have been discussed. For the active fiber probe, an ASE probe made of Er3+-doped fiber has shown a higher efficiency of several times and a lower image noise than the usual passive probe.
New intelligent target for laser shooting practice
Bingming Dai, HongYan Ren, Bing Zhou
This paper is to present a new intelligent target for use in shooting practice in a simulated laser training system. It has many notable characteristics, including novel structure and high precision. It can distinguish and display the ring- number and the orientation automatically. It is low in cost and has many uses.
Simple and easy automation test and measurement method of large-size optical glass homogeneity
Wenku Yang, Yujing Yang, Tao Yang, et al.
The relation between the optical nonhomogeneity and the birefringences of the edge stress and the end stress is given under the condition of ideal linear anneal in this paper. The optical nonhomogeneity of 4 glass samples with diameter 565mm and thickness 75mm for OIIC and K508 has been measured, which agrees very well with the calculation results of the calculation method given in this paper. the calculation result precision can reach 1 by 10-6. The complex measurement processes of various interferences measurement methods for optical homogeneity can be omitted. The optical homogeneity calculation method of the large size glass based on simple measurement is given under its linear anneal in this paper, which not only have practical, but also can be widely spread.
Development of infrared nondestructive testing system with laser scanning automatic heat loading
Fengming Bai, Weina Liu, Li Ma, et al.
Considering laser scanning technique, IR method and electronic technology, studied and design a set of IR NDT system with laser scanning automatic, heat loading method in this paper. To make use of this device, it may detect internal defects of metal material parts, such as micro- craze, refraction, blowholes, etc. This paper also introduce the work principal of testing system. It heats automatically pretreatly to workpiece with CO2 laser scanning and through IR technique received temperature field from workpiece heat conduction. After the filter and the A/D converter system, the changed signal is sent into a single chip computer and the computer make it complete data analysis, data processing, save and display. Therefore, it can achieve detecting characteristic and property of internal defects of parts.
Automeasurement system of belt transmission parameters
Zhanguo Li, Xiaoman Wang
The paper introduces an auto measuring system of belt transmission parameters. In the paper, the auto measuring method and device of the torque, slip ratio and pulling force measurement are described in detail finally, the paper gives an agreeable measuring results of some parameters in belt transmission.
Automated Inspections II
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Surveying converter lining erosion state based on laser measurement technique
Hongsheng Li, Tielin Shi, Shuzi Yang
It is very important to survey the eroding state of the steelmaking converter lining real time so as to optimize technological process, extend converter durability and reduce steelmaking production costs. This paper gives one practical method based on the laser measure technique. It presents the basic principle of the measure technique. It presents the basic principle of the measure method, the composition of the measure system and the researches on key technological problems. The method is based on the technique of the laser range finding to net points on the surface of the surveyed converter lining, and the technology of angle finding to the laser beams. The angle signals would be used to help realizing the automatic scanning function also. The laser signals would be modulated and encoded. In the meantime, we would adopt the wavelet analysis and other filter algorithms, to denoise noisy data and extract useful information. And the main idea of some algorithms such as the net point measuring path planning and the measure device position optimal algorithm would also be given in order to improve the measure precision and real time property of the system.
Detecting laser-range-finding signals in surveying converter lining based on wavelet transform
Hongsheng Li, Xiaofei Yang, Tielin Shi, et al.
The precision of the laser range finding subsystem has important influences on the performances of the whole measurement system applied to survey the steelmaking converter lining erosion state. In the system, the object of laser beams is some rough lighting surfaces in high temperature. the laser range finding signals to reach the microcomputer system would be submerged in intense disturb environments. Common laser range finding devices could not work normally. This paper presents a method based on the wavelet transform to test solving the problem. The idea of this method includes encoding the measuring signals, decomposing the encoded received signals of components in different frequency scales and time domains by the wavelet transform method, extracting the features of encoded signals according to queer points to confirm the arrival of signals, and accurately calculating out the measured distances. In addition, the method is also helpful to adopt some digital filter algorithms in time. It could make further in improvement on the precision.
Optoelectronic technology for detecting flaws on internal surface of cylinder
Ying Che, Yuzhi Shen, Hong Ma
An optoelectronic instrument is introduced, in which the charge-coupled device camera and an optoelectronic probe are used to inspect the internal surface quality of cylinder with real-time and automatically. In this report, the working principle of the device is expounded, and the structure of the optoelectronic probe is explained.
Development of high-precision system for measuring rotational inertia of bullet
Ying Che, Zhanguo Li, Hong Ma, et al.
Appraise the properties of bullet synthetically, a fine instrument for measuring the equatorial rotational inertia and polar rotational inertia of various bullets and rifle grenades is precisely developed. In this measuring instrument, a double suspensions structure is adopted, and a reflecting photoelectric coupler is used to extract the signal of torsional-oscillation period of the measured bullet, the extracted signal is processed by computer, and the data concerned is output on the displayer, furthermore, the measuring precision of the instrument has been analyzed with theoretically, main factors affect the precision has been discussed. The maxima of radial deviation of the measured bullet to the ideal position and the maxima inclination of the axis of the bullet to the axis of steel wires are calculated, and measured to ensure measuring precision are proposed.
New method of measuring photoelastic properties of optical materials by using laser heterodyne interferometry
Ge Kou, ChunKan Tao, Wanrong Gao, et al.
Laser heterodyne interferometry is a kind of photoelectric phase measuring technique, it measures the optical path difference between the reference wavefront and the measured wavefront directly and needs not to deal with the interference figure. This technique can give very high phase measuring precision and can be used in dynamic optical phenomenon. This paper studies the basic principles of laser heterodyne interferometer, and the heterodyne interferometry has successfully been applied to the field of photoelastic properties of selected optical materials. A new method of measuring some parameters of photoelastic is presented. A device which brings atmosphere to bear on the optical materials has been developed to measure the change of refractive index at different pressures, and the relationship between the given pressure and the corresponding change of refractive index has been obtained through a series of experiments. Also, a careful analysis is given to the result of the experiments. At last, a feasible scheme is discussed on applying laser heterodyne interferometry to the measurement of refractive change.
Digital optical profiler with automatic reference phase calibration
Chunlong Wei, Mingyi Chen, Zhijiang Wang
A digital optical profiler has been developed by our group. It is based on a Linnik interference microscope. The high precision measurement is obtained by introducing the phase-stepping interferometry. The phase stepping procedure is implemented by applying the high voltage to a piezoelectric transducer (PZT) and forcing it to extend or compress. It is commonly known that the PZT components have strong nonlinearity. So it is very difficult to obtain accurate reference phase steps. An effective A-bucket phase-stepping algorithm has been proposed by Okada et.al., G.S.Han et.al.,I.B.Kong et.al., and S.W.Kim et.al.,respectively. The algorithm is insensitive to reference phase stepping errors and each phase step can be calculated by iterative least-squares fitting. However, the initial values of the iteration are given by guessing. A new initial values determination method is presented in this paper. The new method calculates the initial phase steps by means of one dimension FFT. The measurement results confirm that the new method is very effective. Because of the new method, the reference phases can be automatically calibrated on line. The about 0.4 nm repeatability of Ra measurement can be achieved without vibration-resistant system. The profiler has good prospect in the measurement of smooth conventional optical components, optical disk, optoelectronics devices etc..
Robust phase-unwrapping algorithm for flat measurement in phase-stepping interferometry
Chunlong Wei, Mingyi Chen, Weidong Hou, et al.
Phase-stepping interferometry has been extensively applied in optical metrology. But the phases calculated by the phase-stepping algorithm are wrapped into the range [-it, it] because of the arctangent function. The procedure of recovering the real phase from thd range [-it, it] is known as phase-unwrapping. The phase unwrapping may be a trivial problem with the cases of noisy, low modulation, corrupted regions etc. in the interferograms. The conventional algorithm always failed in those cases. Many algorithms were developed to solve the problem. A new phase unwrapping algorithm is proposed by our group. It is very suitable for the flat measurement. The new algorithm first fits the measured flat data to an ideal flat by a group of new formulas derived by ourselves. Then do operation of plus or minus 2it for the wrapped phases calculated by phase-stepping algorithm according to the ideal flat. Since the measured flat data do not affect each other in the phase unwrapping procedure, the conventional phase unwrapping problem is avoided. A flat metal plane is measured with many corrupted regions in a Linnik interference microscope. The experimental results indicate that our new algorithm is robust and fast.
Characteristics of laser scanning for bar code recognition
Shuqun Shen, Yuchao Shen, Rong Fan, et al.
The needs which should be met in bar code scanning of all kinds of scanners are described. The size of the spot, the depth of focus, the scanning velocity, the data rate of signals and how many effective sans there should be in omni- directional scanning are also analyzed. The formula dealed with or deduced are of advantage to designs of bar code laser scanners.
Measurement and accuracy analysis of refractive index using a specular reflectivity close to the total internal reflection
Hui Li, Zukang Lu, Shusen Xie, et al.
A new method to measure refractive index and the accuracy analysis as well is presented. The characteristic includes that the direction of incident light is not perpendicular to the interface but close to the critical angle of total internal reflection. That the specular reflectivity changes sharply near the critical angle implies that a high measuring sensitivity be reached easily. A narrow p- polarized laser beam and a prism or a quasi-semi-cylindrical lens in contact with a sample are applied in the apparatus. In order to match a high accuracy, a photoelectronic receiver with dual-channel divider is designed to compensate the stability of output of laser. One of the advantages of the method is its high accuracy. The uncertainty in the refractive index measurement is in the fourth decimal place at least. The exact direction of incident laser beam depends on the accuracy of result expected. Another outstanding advantage is its particularly straightforward in use experimental techniques. The method will be the most promising tool to study the response of refractive index to subtle changes of different conditions.
New method of two-color calibration and one-color measurement for real-time inspection of temperature field
Hua Zhang, Jiluan Pan, Huiqin Wang
Based on the research of a colorimetric method with tow RI images, a new method of two-color calibration and one-color measurement for real-time inspection of welding temperature field was developed, which can not only eliminate disadvantages of one-color measuring method, such as dependence of the measured temperature on the distance of object and the emissivity of object and the parameters of the measurement system, but also overcomes disadvantages of two-color measuring method, such as the low speed and sensitivity on the noise in the measurement. The method is applied successfully in welding temperature field measurement, the measuring time is less than 0.5 second per temperature field and the error of measurements is within 30 degrees C. Weld shape control is another important application of the developed method. Using the width of isotherm from welding temperature field as input and welding current as control parameter, a penetration control system for TIG weld was installed. Experiments proved that the even penetration be obtained under very unstable weld condition.
Automated Inspections III
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Intelligent measuring equipment for the width of fibers
Jinxiang Chen, Benkang Chang, Yunsheng Qian, et al.
In this paper, we describe high accurate non-contact measuring equipment together with its principle, hardware structure and idea for software design. Its principle is using optical modulation to modulate and amplify the figure of fibers' width, then convert the optical signa into electrical signal. The electrical signal is processed by an automatic processor which comprises MCS-51 single-chip microprocessor and other interface circuits. Finally the processed data is displayed or printed. This equipment can exclude the system error with calibration. Multivariate linear regression algorithm is used in calibration software design. It can discriminate the overlapping and across of fibers and eliminate the system errors. All proceeding is automatically completed without the interference of people. It excludes the personal influence and ensures the reliability of measurement.
Picosecond optical sampling method to measure S-parameter of microwave monolithic integrated circuit
Fuyun Lu, Shuzhong Yuan, Jiaqi Pan, et al.
The fundamental principles to measure S-parameter of microwave monolithic integrated circuit by photoconductive sampling technique has been reported. Photoconductive sampling technique has been used to measure the S-parameter of a wide-band low noise three-stage amplifier for the first time. The measurement results agree well with those measured by network analyzer. And a measurement band width of 100GHz has been achieved by photoconductive sampling technique.
Fault signal detection with autocorrelation method
Xuexian Yang, Qin-Yan Zhang, Yueqiu Han
Signal's autocorrelation characteristic is used for fault detection and the fault detection formula is presented in this paper. The implementation schemes under periodic and non-periodic signals are discussed respectively. The fault detection algorithm is presented at the base of Bayesian Decision and corresponding implementation a scheme. In computer simulation, linear frequency modulated signa is selected. The simulation results confirm that the autocorrelation method is applicable. As the conclusion,this method can apply to electronic equipment built-in self-test and can accomplish on-line fault detection of period signals.
Stress-induced birefringence and extinction ratio
Gaoping Li, Zhaojing Yang, Chunli Lu, et al.
The stress-induced birefringence, extinction ratio and their relation are studied in this paper. By means of building up their relation and measuring stress-induced birefringence, we can get more precise extinction ratio of relevant materials, expand the extinction ratio measurement range, and improve the measurement repeatability error greatly.
Optical measurement method of necking process in the material tensile test
Lizhong Zhang, Xueping Song, Guohua Cao, et al.
This paper puts forward a new method of optical real-time measurement in the necking process of material tensile test, including the change of the necking position and the necking value with the gradually applied load. Two dimension measurement is completed by the scanning of polygon mirror at the emitting end and the adoption of linear array TDI CCD components. The interference of stray light is restrained effectively because we use semiconductor laser as light source and optical filter at the receiving end. Furthermore, this paper deals with the correction method of non-uniform speed scanning beam at the receiving area, the factors effecting the ultimate measurement accuracy and the countermeasures.
Infrared detection technique based on multicorrelation of frequency and time
In IR detection, frequency modulation or time correlation is the important technique. In some signal detecting system, it is not enough of the technique. In this paper, multi- correlation of time and frequency is discussed, and the method of the technique is given. Time-position encoding technique is also discussed in the paper. When the new technique is applied in IR detecting system, the DC and adjacent radiation interference can be removed easily, and the system can work more reliably.
New kind of spectral analysis instrument for measuring time-resolved spectrum of single-pulse light
Jingguo Yang, Cangli Yang, Yuanqian Ha, et al.
A new kind of spectral analytical instrument has been developed for measuring pulse time-resolved spectra. In this instrument, a special light beam modulator translates the time-distribution of optical spectra into the space- distribution of light intensity, and then the time-dependent spectra is detected by an ordinary 2D CCD device. The time resolution of 25 microsecond(s) and the wavelength range of 224-824 nm have been attained in the experiment of a Xe flash-lamp emission.
Constraint of Laplace transform method used in the reconstruction of axisymmetric field
Donglou Wu, Anzhi He, Wei Yao
In this paper, we use Laplace Transform Method (LTM) to reconstruct the temperature field generated by cylinder radiator, which can be treated as axisymmetric field. In the experiments, we found that LTM leads to fetal mistake when the relative shift of the fringe is large. We analyze the LTM and the reason is found, which shows that LTM constrained strictly in the reconstruction of axisymmetric field. We compared the different results under different conditions with the results measured by thermocouple axisymmetric field. We compared the different result under different conditions with the result measured by thermocouple.
Apparatus for highly accurate measurement of transmittance and reflectance of large-sized optical components
Yongming Hu, Zhe Chen, Yanbiao Liao, et al.
In the paper, an apparatus for high accurate measurements of transmittance and reflectance of large size optical components will be described. The working wavelengths of apparatus are 1.06 micrometers and 0.53micrometers respectively. It can measure both transmittance and reflectance of optical components simultaneously. And both plane and spherical optical component can be easily tested. The apparatus' measurement precision is less than 0.1 percent. The maximum measured size of components is 450 mm in diameter. The heaviest weight of measured component is about 20 kilograms. In this paper, the method of data processing and the schematic diagram will be presented.
Design of weak-signal detection filters
Yang Cao, Fang Li, YongChang Lin, et al.
This paper discusses the overall design of the weak signals detection filters, gives a design example of weak signals detection filters in the visible light range, its coating technique and the experiment result applying for weak signals detection.
Mine dust optical measurement method
Bin He, Jidong Chen, Xiaoyan Tian, et al.
This paper analyzes the reasons that the dust concentration can not be measured accurately by the present optical methods, and proposed a new optical technique which employs the principles of interference of light to measure the dust concentration. The laboratorial experiment shows the feasibility of the new method.
Photoelectric detection system in equipment for recognition and sorting of bills
Jihong Liao, Baozhi Yin, Wenwei Lao, et al.
This paper reports a photoelectric detection system in the recognition and sorting equipment of bills. A SSPA line scan image senor is used as the photodetector in the system. A new type fiberoptic lens is used in the optical subsystem instead of the ordinary optical lens. The video output of the SSPA sensor is processed by a microprocessor in real- time. When properly programmed, the system can determine the detected bills; quality as well as denominations. This paper discuses the principle and composition of the system. The drive of the SSPA sensor,the video output processing, the collection of the binary video output and the data processing program are discussed in detail. The resolution in the movement direction and in the scan direction and in the scan direction are also analyzed. The system can efficiently recognize the RMB bills of Y10, Y50 and Y100 denomination and can also detect the bills with holes and/or tears whose series are larger than 1 mm by 1 mm.
Automated Inspections II
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Effective approach for detecting bands of EBSP with Hough transform
Linsen Chen, David P. Casasent
An effective approach for the detection of the electron backscatter diffraction patterns with the Hough transform has been described in this paper. Based on the peak-finding method and the enhancement filter in the Hough space, this approach can give automatically the orientations, widths and coordinates of the central intersection points of the bands in the patterns. Comparison with other Hough approaches shows that our approach is more robust for the very low quality patterns and has an advantage of low time cost. No further fitting scheme or constrain conditions are needed to get correct bands. Results have been presented.
Experimental method for underwater acoustic field detection from water surface using laser probe
Chenbo Zhou, Kaihua Liu, Junqing He, et al.
The physical phenomenon of the perturbation on the water surface caused by underwater acoustic signals has been analyzed in this paper. A laser probe detection system in laboratory with a semiconductor laser to measure signal underwater from the water surface was developed. Meanwhile, the synchronous measurement utilized a -200dB standard hydrophone was also done.The signal frequencies from 200Hz to 10KHz was measured and the results have been given. The experimental results show that the system is available.
Application of SPD to fast spectral color measurement
A technical approach and system scheme for fast high- precision spectral measurement of color appearance are proposed. This system is equipped with the modern self- scanning photodiode array devices as the photodetectors, the pulsed xenon lamp as the light source, and with the dual light paths and multichannel configuration. The related function modules of the instrument are designed. As the result of such a photo-electric arrangement, the measurement accuracy is improved a lot and the repeatability is also very satisfactory.
Multifunctional photoelectric detection and measurement system
Weina Liu, Fengming Bai, Tiejun Zhao, et al.
The thesis demonstrates mainly about 2D photoelectric universal detection and measurement system's theory and application to measure rotator findings' size and shape tolerance in mechanical manufacture. It tells how to detect and measure automatically rotator findings' axial size, redial size and shape tolerance,. attaching laser scanning detection and measurement technique with Raster displacement detection and measurement technique controlled by microcomputer. The system is a high-technique product, which are multi-subject and multi-field.
Measuring the thermography of friction-welding process
JiaoBo Gao, Jing Li, Yue-you Feng
The full process for measuring the thermography of friction welding by AGEMA 900 is described. The typical thermography pictures and temperature data curers are given. It provides scientific basis for parameter design of the friction- welding process.
Wedge-ring wavelet detector
Wenyi Feng, Yingbai Yan, Guofan Jin, et al.
The wedge-ring detector is useful in Fourier frequency analysis, and is widely used in industry. The drawback is that the detector only gives the global frequency distribution about a signal, whereas details of the local frequency information are not provided. A wedge-ring wavelet detector is designed and fabricated to overcome the shortcomings in this paper. Simulation and experimental results are given to testify the performance. Primary applications to automation detection and pattern recognition are presented.
New Monte Carlo method of backscattered lidar signals
Zhufeng Du, Yimin Lu, Tiexia Huang
Monte Carlo method is a classical method to simulate the backscattered lidar signals, but its disadvantage is that the calculation efficiency is very low. Based on the traditional semianalytic Monte Carlo method, the new method use a distorted Henyey-Greenstein (H-G) function to approximate the scattering phase function, obtain the expression of the scattering angle (theta) from H-G function, and compte photoelectric transform according to the characteristic of photomultiple. From the calculation efficiency is improved greatly.
Optical method for measuring electric current
Junliang Zhao, Rongfeng Guan, Yilu Wang
The principle of optical method for measuring electric current utilizing the Faraday magneto-optical effect is stated in the paper. A practical power source of semiconductor laser diode is presented, the sensing head designed by ourselves is introduced. The signal processing technique with one chip microcomputer is described. In addition, the experimental results are given. The study shows that this method has many advantages. Therefore, it is expecting to be used in electric system in the future.
Technological research on an application of neural network in character recognition
Ping Li, Xiaofeng Mu
The artificial neural network Abstract simulates the principle of human neural element movement. It has many abilities such as study independently, adaptation itself , association,reasoning from analogy and generalization. The application of the artificial neural network in character recognition. The two procedurcs of character recognition ,i. e. ,the procedure of learning and the procedure of recognition ,were comprehensively described in this paper. The procedure of learning, that is, the procedure of training, the characteristic parameters produce the standard sample, and characters are recognized by using the standard sample, it can make continuously adaptation itself correction in use by the results of recognition. Because, of adopting the improved BP algorithm, reasonably selecting initial values, the adjusting method of learning rate, putting in momentum and introducing the simulated annealing method, the problems of the slow convergence speed of the original algorithm, bogging the local minimum and training paralysis was solved to improve the recognizing rate and obtained satisfactory results.
Spectroellipsometric study of optical and electrical properties of buried CoSi2 layers in silicon produced by MEVVA implantation
Wensheng Guo, Saipeng Wong, Ziqing Zhu
Cobalt ion implantation of silicon substrate by Metal Vapor Vacuum Arc ion source has been studied by spectroscopic ellipsometry (SE) over the wavelength range of 400-2000nm. A series of annealed samples with different substrate temperatures during implantation have been investigated. From the interpretation of the ellipsometric data, the depth profiles of the samples can be derived. And the derived layer thicknesses are found to be consistent with the results of RBS and XTEM studies. At the same time, the optical properties of the buried CoSi2 layers in Si can be derived. To represent the optical properties of these buried CoSi2 layers, a three-term model is used with two classical Lorentz oscillators representing the electronic transitions, and one Drude term modeling the effect of free electrons. The derived Drude parameters can be used to calculate the optical resistivities of these buried CoSi2 layers. And the calculated optical resistivities are consistent with the dc electrical resistivities deduced from electrical measurements.
Spectroellipsometric study of diamondlike carbon films
Wensheng Guo, Saipeng Wong, Ziqing Zhu
Diamond-like carbon film (DLC) is well known for its optical, electrical and mechanical properties. However, its properties can vary widely from graphite to diamond-like, strongly depending on the film preparation. So the determination of sp3/sp2 ratios of the DLC films is very important. In this work, a series of DLC films have been prepared on silicon substrates by Filtered Arc Deposition (FAD) and an optical method - spectroscopic ellipsometry (SE) has been applied to study these samples in the visible wavelength range. In the analysis of SE spectra, a single DLC layer on Si substrate model has been used and the DLC layer simply consists of sp3, sp2 and void constituents. The Bruggeman effective medium approximation has been applied to calculate the dielectric response of these three components. From the interpretation of SE spectra, the film thicknesses and the volume fractions of sp3, sp2 and void have been derived. SE results show: the fitted film thicknesses are consistent with those of Rutherford Backscattering spectroscopy; the fractions of sp3 correlate wit results of electron energy loss spectroscopy studies; for all these samples, the concentrations of void are very small which implies the compact DLC layers. It shows that SE is a very useful and promising optical method to determine the sp3/sp2 ratios of the DLC films.
Spectroellipsometric study of SiC/Si heterostructures produced by MEVVA implantation
Wensheng Guo, Ziqing Zhu, Saipeng Wong
SiC material is of intense interest because of its unique features. Two samples of SiC/Si heterostructures were prepared by ion beam synthesis (IBS) with metal vapor vacuum arc ion source at an energy of 65keV and a dose of 1.0 by 1018 cm-2. After implantation, one sample was annealed in nitrogen ambient at 1250 degrees C for 10 hours. Spectroscopic ellipsometry (SE) was then performed to study these two samples with the wavelength range of 400-2000nm at a fixed angle of incidence. For the interpretation of SE spectra, the material and optical properties of the annealed sample had been derived. SE result confirmed the formation of a thick buried SiC layer for the annealed sample, but the optical property of this buried layer was found to be different from that of bulk SiC material even if a long time annealing at high temperature was performed. These results were further substantiated by other techniques, including FTIR, XPS and RBS. For the as-implanted sample, different models had been tried but they were not reasonable enough to fit the SE spectra well, the point was how to simulate the optical response of the free carbon atoms distributed in the sample. Further investigation is needed.
Processing of infrared thermography images in pulsed-heating infrared thermography nondestructive testing
Huijun Tang, Tieying Ding, Shuwen Xue, et al.
In the IR thermography non-destructive testing, image blurring introduced by noises and heat diffusion in the sample is an important problem. In this paper, a serial of image processing methods are proposed to eliminate the influence caused by noises and heat diffusion. By use of these methods, image averaging, median-value, binarization and gradient alternation have been done. The processed images' characteristics are clear, and the error of detection is smaller than 5 percent. It is showed that the technique can effectively remove the blurring in images, improve image resolution and give us distinct images that meet the need of IR thermography non-destructive testing technology.