Chinese Version Light学术出版中心
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Issue 4 ， 2002
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Designing principles for a low chromatic aberration GRIN rod lens
Abstract：In this article, the contributing factors to gradient index (GRIN) rod lens chromatic aberration are discussed, and according to Fantone model, the principles of selecting ion-exchanging pairs and of determining base glass properties for a low chromatic aberration GRIN rod lens prepared by ion exchanging process are presented visually in the optical glass N d-V map. The analysis shows, using the glass with typical optical properties as the base glass, both Na+/Li+ exchanging and K+/Cs+ exchanging are suitable for preparing a low chromatic aberration GRIN rod lens, while K+/Tl+ exchanging and Na+/Ag+ exchanging might produce a GRIN rod lens with much higher chromatic aberration. These principles are instructive in the fabrication of a low chromatic aberration GRIN rod lens.Keywords：GRIN;Lens;chromatic aberration;ion exchanging- 48
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Published：2020-08-12 -
Optical design of a wide-angle lens for long-wave infrared earth sensors
Abstract：This article describes the optical design of a wide-angle lens suitable for long-wave infrared (LWIR) earth sensor whose operating wavelength range is 10 to 16 microns, and full angle of view is up to 135 degrees, having an uncooled staring focal plane array. The optical system only consists of three germanium lenses with a "negative-positive-positive" reversed telephoto telecentric structure in the image space. This type of wide-angle lens can balance the correctness of off-axis aberrations against the evenness of illumination at its image plane very well. The designed lens has the advantages of simplicity, compactness and long back working distance. Its imaging quality is nearly diffraction limited, so that its modulated transfer function (MTF) value is higher than 0.6 at the 20 lines/mm spatial frequency in the image plane, and the relative error of the linearity between its image height and field angle is lower than 15%. Its manufacture and alignment tolerance are also analyzed with the CODE V optical design software.Keywords：earth sensor;long-wave infrared (LWIR);wide-angle lens;optical design;aspheric surface- 59
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Published：2020-08-12 -
Sphericity error evaluation using the genetic algorithm
Abstract：To evaluate the form error of a sphere, a novel method based on the genetic algorithm was devised. In the paper, the problem about sphericity error is reviewed firstly. Secondly, the mathematical model of the sphericity error under the condition of minimum zone is derived from the mathematical definition of the circularity, and the fitness function of the algorithm is given as well. Thirdly, the critical such as selecting the initial value, initialing the population, and deciding genetic operators, etc. in the process of the algorithm implementation are described in detail. Finally, the method is verified by the examples in the literatures 1 and 2. The theoretical analysis and computation results indicate that the designed method not only conforms to the minimum zone condition but also assures a global solution, and is easily implemented. It is accurate and efficient in solving the problem of dimensional and tolerance evaluation.Keywords：sphericity error;fuzzy inference;genetic algorithm- 53
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Published：2020-08-12 -
Color quantization of color images in a homogeneous color space
Abstract：Color quantization is to classify the colors of an image to a few classes of colors according to the visual effect of human eyes. So these few colors can be used to creat a new image and keep the color quantization errors between the new image and the onginal one to be the least.This paper gives the quantization of a color image in a horrogeneous color space of L*a*b*, which is transformed from a nonhomageneous color spece of RGB. Therefore the problem of nonhomogeneous chromatisom to human eyes can be solved. Firstly,, the data of a color image were saved into a single chain list. Then the list was scanned, finding two nodes whose chromatism is the least. Finally,the two nodes were combined into a new node. After sufficient dynamic calculation we got the palette of the color image quantized. The experimental results show that minishing the color quantization errors and improving its veracity are the catholicity and uniqueness of this method.Keywords：color space;color quantization;color image- 50
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Published：2020-08-12 -
Modal identification of luminosity signals in frequency domain
Abstract：Object luminosity signals were identified by means of digital signal processing(DSP) and modal identification. Modified luminosity signal was transferred to frequency domain by special discrete fourier transfer(DFT) which is like gabor transfer. Then, signal was filtered and partitioned into fine frequency bands. After that, Fisher's discriminance was used in frequency domain wth characters, which were energies of a group of selected fine frequency bands. The identification function matrix(IFM) was obtaind through recognized data and identification rulers were given. After unidentified data had been put into the IFM, they were categorized under the rulers. Three satellites' luminosity signals were identified successfully and difficulties like low SNR, abnormal errors from measurement, complex model of noise were overcome.Keywords：luminosity character;object identification;frequency domain;Fisher's discriminance- 84
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Published：2020-08-12 -
Research on the perspective texture mapping of free-form surface
Abstract：Based on texture mapping, a perspective texture mapping is proposed in this paper. First, the principle of perspective transformation and its application in the texture mapping of free-form surface are presented. During the perspective texture mapping, the precision of approximation of bicubic patches is better than that of polyhedrons, so bicubic Bezier patches are used to approximate free-form surface. Then, the arithmetic of the perspective texture mapping is introduced: through getting the corresponding relationship between the texture space and the object space, and the corresponding relationship between the object space and the screen space, we get the corresponding relationship between the texture space and the screen space. Finally the aliasing is discussed. This method can also be effectively used for polyhedron and free-form body.Keywords：free-form surface;perspective transformation;texture mapping- 68
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Published：2020-08-12 -
Digital imaging and its data quick acquisition in high quality X-ray testing
Abstract：X-ray digital imaging testing technology is a new method of nondestructive testing. Non-film real time digital radiography , which has high efficiency and low cost, especially the characteristics of digital image exchangeability and storage convenience, has become the development direction. The commonly used system consisting of a X-ray image intensifier, a video camera, an image acquisition card and a computer has the disadvantage of low imaging quality and only being used at low X -ray energy. By repetitive investigating and testing, a high spatial resolution and high contrast sensitivity system based on crystal scintillation and scientific CCD camera has been developed, which can be used both at low energy and high energy. This paper introduces the constitution of the system, including the scientific grade CCD camera which must be refrigerated, an output signal pre-processing circuit of CCD, A/D circuit, and quick data acquisition circuits using the EPP mode of computer and softwares. An aluminium casting (150mm) image obtained by the system at accelerator high energy X-ray is offered.The experimental results show the system has merits of adapting a wider X-ray energy range and imaging quality better than the system based on an image intensifier and a video camera(imaging time longer than the latter). The spatial resolution of the system is over 3lp/mm, the contrast sensitivity, when the thickness of the object to be inspected exceeds 50mm equivaled steel thickness, is below 1%.- 60
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Published：2020-08-12 -
Adaptive model-based real time tracking algorithm
Abstract：The correlation-matching algorithm determines the matching degree of model and grabbed image by calculating their correlation value. Because the algorithm has high precision and strong adaptability, and is robust to the linear change of grayscale, it is widely used in projects as a classic matching algorithm. But correlation-match computing is very time-consuming and difficult to satisfy the real time request. Besides, when the target is only small part in the model, it is hard to confirm the model position. In this paper, an adaptive model-based real time tracking algorithm is introduced,in which the grabbed image is segmented by threshold and the noise is removed. Then a contour segment method is used to determine the size of model. The matching algorithm chosen for calculating the degree of match is a normalized correlation algorithm accelerated by pyramid algorithm. The results show that when the target is very small in the model, the tracking algorithm has better matching precision and real time.Keywords：target tracking;correlation match;Algorithm;model- 64
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Published：2020-08-12 -
Software interface technology of the CAD/CMM system in paperless inspection
Abstract：After introducing the necessity of integrating the CAD/CMM system in paperless inspection, this paper proposes a new method of setting up geometrical modeling of parts, which is based on IGES-files. By this method, the CAD data of parts to be measured are extracted and recognized automatically, and their models are rebuilt in the CMM system. The principles of parts modeling and the algorithms are presented. Furthermore, an experiment is shown to certify the correctness of the modeling way.Keywords：computer aided design;coordinate measuring machines;interface techniques- 60
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Published：2020-08-12 -
Vectorization technology for engineering image
Abstract：Engineering image vectorization is the key technology in CAD. In this paper,a new method is proposed for engineering image vectorization, and the technology of image manipulation such as image binarization, etc. is explicated. With the vectorization software developed, engineering images can be converted into lines and arcs, and the NC file can be produced from the vectorization file in DXF format by CAD/CAM software.Keywords：engineering drawing;vectorization;image binarization- 54
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Published：2020-08-12 -
Influence on the intensity modulation of a reflective fiber optic displacement sensor induced by reflector shape
Abstract：In a reflective fiber optic displacement sensor, the influence on intensity modulation property caused by the reflector shape was studied theoretically with the mathematic model found. The computer simulation was performed. Results show that with the radius of the convex reflector increasing, the starting distance of the sensor property curve will decrease, the front slope will change unobviously, while the linear range of the back slope enlarges, and its sensitivity decreases. When the radius of the concave reflector increases, the starting distance of the sensor property curve will decrease, the linear ranges of the front and back slopes become smaller while their sensitivities enhance.Keywords：fiber optic sensor;intensity modulation;reflector;shape- 62
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Published：2020-08-12 -
Application of a single chip microprocessor in the optical fiber Bragg grating sensor
Abstract：For a long time, a spectrograph is used to inspect the reflective wavelength of a fiber Bragg grating sensor. But with the wide application of the fiber Bragg grating sensor, the spectrograph gradually brings more and more limitation. The text introduces regulating the cavity length according to the principle of Fabry-Perot cavity multiple light beam transmission. When Fabry-Perot cavity meets given conditions, its transmitted light will become the strongest or weakest, thus the model of cavity demodulation system is established. And relevant variables can be obtained by checking F-P parameters. According to the characters of a fiber Bragg grating, a matching filter demodulation model is established, in which another fiber Bragg grating is used to follow the change of the measured fiber Bragg grating and then the measured parameters are obtained. The paper points out the key issues to be solved when the demodulation projects are used. To improve the accuracy and real time capability of the demodulation system, a single clip processor is used to deal with related data information of the system. Its applications in the demodulation system and related interfaces are expatiated, and the design of hardware and software are presented in detail.Keywords：fiber Bragg gratings;Fabry-Perot cavity;matching-filters;single chip processors- 72
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Published：2020-08-12 -
Research on force sensors in a micro-friction test rig
Abstract：In this paper, the problem of friction testing in micro-components is discussed.The experimentation made by Bhushan and Koinkar shows that the coefficients of macro friction and nano friction are different.But in MEMS, the size of the part is several microns,or even greater than that, and the interface area is beyond nano with the load between N and nN. So the MEMS's friction is neither macro friction nor nano one, which should be studied further.But there is no any appropriate instrument to do so because the present instruments are designed for macro or nano friction testing. This paper discusses the force sensor which is used in the instrument for testing the MEMS's friction.The general force sensor's resolving power and sensitivity are too low. And we make the force sensor by MEMS technics,which has many advantages such as low cost,high precision and reliability, low drive and power consume,etc. Finally, the performance of the force sensor is present.Keywords：MEMS;micro-friction testing;force sensors;structure design- 57
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Published：2020-08-12 -
Research on miniature hexapod bio-robot and its tripod gait
Abstract：Based on the principle of bionics and analysis of the movement mechanism of hexapod, a new type of miniature hexapod bio-robot was developed by using four-bar linkage, screw gearing, belt gear, driven by D.C. micromotor and controlled by PC.The external dimensions of the model machine are 30mm?40mm?20mm and its weight is 6.3 g. The robot's movement gait and the movement stability are analyzed in this paper. The experimental results show the robot has good mobility.Keywords：Hexapod robot;bionic robot;link curve atlas;tripod gait- 45
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Published：2020-08-12 -
New method for realizing the film-supplying characteristic of a high-speed camera
Abstract：The realization of the film-supplying disc's damped torsion of a prism compensation high-speed camera is one hard-to-solve problem when the camera adjusted, especially when the speed is high and the film long, because of the inertial, the film-supplying disc's rush for ward leads to film crushing up. The traditional damped torsion-supplying device is composed of both a mechanical friction damper and an electromagnetic clutch, manually adjusting a multi-screw thread to get different damped torsion at different speed. Qualitatively analyzing the film-supplying characteristic of the camera in derail, a new method for realizing the film-supplying disc's damped torsion is presented, in which a program controllable electromagnetic clutch is used to replace the former device to fulfill the damped torsion, and a single-chip computer is used to control the electric current of the electromagnetic clutch's coil, so that the damped torsion is changed. By this method, the device is simplified and makes the adjusting of the camera easier. The practical use shows this method is effective and valid.Keywords：prism compensation high-speed camera;film-supplying characteristic;film-supplying device;damper- 43
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Published：2020-08-12 -
Study of the drift angle control in a space camera
Abstract：Image motion compensation(IMC) is the key technology of a high-resolution space camera. Image motion speed is seperated into two vectors in the image coordinate for existence of the drift angle:the forward direction image motion speed and the crosswise image motion speed.In fact,drift angle control eliminates the crosswise image motion speed,so it is a part of image motion compensation. Different kind space cameras use different image motion compensation methods and drift angle controls, respectively. The applications of drift angle control in the mechanical image motion compensation and electronic image motion compensation are introduced and analyzed in this paper.The drift angle control method in a TDICCD image tansfer space camera is emphasized.Keywords：space cameras;image motion compensation;drift angle control- 62
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Published：2020-08-12 -
Small portable video technoscope for parts detection
Abstract：Compared with average technoscopes, a small portable video technoscope is introduced in this paper. It consists of four parts: lighting, imaging lens, CCD camera, computer for monitoring and image processing,which has the advantages of small volume (80?20?20mm3), simple structure and being easy to carry. The original picture and the one processed with the method of edge sharpening and intensity adjustment show and prove that the quality of the image meets the demand for the inner surface detection of small-diameter parts.Keywords：technoscope;video technoscope;image processing- 57
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Published：2020-08-12 -
Design of a sagittally focusing double-crystal monochromator in synchrotron radiation
Abstract：This article briefly remarks the optical design, structure design and control design of a sagittally focusing double-crystal monochromator, and introduces the structure design of the sticking point (homochromatism, focusing and the wheeling of the Bragg) and the adjustment frame of yaw, pitch and roll in the monochromator based on the right circular flexure hinge.Keywords：sagittal focusing;monochromator;synchrotron radiation;diffraction- 51
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Published：2020-08-12 -
Analysis of the axial accuracy of the GD-220 photoelectric theodolite
Abstract：The axial accuracy of a photoelectric theodelite greatly determines the measuring accuracy of the whole instrument. Taking the photoelectric theodolite GD-220 as an example, this paper discusses various kinds of errors in the vertical and horizontal axial systems i.e. radial runout, angular swing and axial shifting, and quantitatively analyzes the axial swing error caused by the surface figure error and position error of the axial system parts. The measured results of 9 sets of GD-220 photoelectric theodolites are listed, showing that the analysis of the axial accuracy and structure design of the axial system are both reasonable.Keywords：vertical axial system;horizontal axial system;theodelites- 44
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Published：2020-08-12 -
Method used in the suppression of DTG output noise
Abstract：The jitter in line-of-sight (LOS) can result in the degraded performance of a gyro stabilized platform directly.And one of the main reasons leading to the jitter is the output noise from the dynamically tuned gyro (DTG). Analyzing the characteristics of DTG output noise, it is available for us to suppress the DTG output noise by applying Kalman filtering algorithm. The simulation results have shown that the output noise is suppressed by 4.7dB with Kalman filtering effectivelyKeywords：LOS;DTG;gyro stabilized platform;output noise;Kalman filtering- 52
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Published：2020-08-12 -
Application of VXI bus technology in ATE for space net-load
Abstract：This set of ATE(Auto Test Equipment) based on VXI bus technology includes an intelligent interface, a data acquisition system of VXI bus module devices and an auto test software developed via VEE. The intelligent interface isolates the test signals provided by DUT(device under test) successfully. The use of VXI bus module devices improves the ATE hardware reliability, while the use of VEE reduces the software development complexity,shortens its period and keeps the auto test software in guarantee. This set of ATE accomplishes online measurement and test for the space net-load automatically, and provides various reliable data to test the functions of the space net-load.- 49
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Published：2020-08-12
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