Chinese Version Light学术出版中心
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Issue 6 ， 2003
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Image motion compensation error analysis for TDI CCD panoramic aerial camera
Abstract：In comparison with a pushbroom aerial camera, a TDI CCD pendular aerial camera has a larger angle of view, but it has the problem of image motion in the direction of pendulum swing. A real angle IMC (image motion compensation) is therefore proposed to solve this problem. Experiments proved the correctness of real angle IMC. The error of FMC (forward image motion compensation) is analyzed taking a CT-F3 camera as an example, and the system performance suggested are as follows: the precision of TDI CCD integral time should be more than 5‰, and the compensation precision of scanning mirror should be over 1%.Keywords：aerial camera;CCD camera;pendular;pure angle;image motion compensation;error analysis- 36
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Published：2020-08-12 -
Scanning mirror supporting structure of aerial remote sensing camera
Abstract：From the viewpoint of ensuring the imaging quality of scanning mirror, the principles followed in selecting material for scanning mirror and its supporting structure are described. The ways of supporting scanning mirror and their applicabilities are discussed. The design concept of flexure supporting structure is proposed for mirrors with higher profile accuracy requirements. The mirror assemblies both before and after the flexure supporting structure are analyzed under different working conditions using CAD/CAE engineering analysis software. The effectiveness of this flexure supporting structure can be substantiated through comparative analysis of finite element model deformation. The reliability of the mirror supporting structure is finally determined by the imaging quality of camera tested under field conditions.Keywords：aerial remote sensing camera;scanning mirror;flexure support structure- 41
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Published：2020-08-12 -
Design of strip primary mirror supporting structure based on finite element analysis
Abstract：The design requirements for the primary mirror sub-assembly of a space camera are: its dynamic stiffness is above 90 Hz; the synthesis face figure error (P-V value) for the primary mirror is less than 632.28 nm, and the maximum deflection is less than 30 μm, when the primary mirror sub-assembly is subject to 1 g gravity and a uniform temperature rise of 4℃ in X, Y, Z directions. Analysis and calculations show that if the primary mirror sub-assembly is a rigid support, the synthesis face figure error will go far beyond the design requirement; but if it is a flexible support, the error will generally be within the limits specified. The primary mirror sub-assembly must therefore be a flexible support design, and the determination of height and thickness of mirror supporting ribs is the key to a good flexible support design. If flexibility is too high, dynamic stiffness and the maximum deflections of the primary mirror sub-assembly can not satisfy the design requirement; if flexibility is too low, synthesis face figure errors will not meet the design requirements. It is concluded from calculations that when the flexible support rib is 46 mm high, and 1.7 mm thick, the response value of the primary mirror sub-assembly satisfies the design requirements.Keywords：primary mirror;flexible support;finite element analysis- 45
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- 14
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Published：2020-08-12 -
Algorithms of the phase-shifting interferometer via wavelength tuning
Abstract：This paper describes the basic principle of wavelength scanning interferometer and analyzes its characteristics. Their merits and application fields are shown by comparing wavelength scanning interferometer with conventional hardware phase-shifting interferometer. For tunable semiconductor laser from American New Focus Company as example, hardware of realizing wavelength tuning is depicted simply. Algorithms of wavelength scanning interferometer are divided into three kinds: weighted multi-step phase shifting algorithm, the algorithm based on Fourier-transform technique and multi-wavelength algorithm. Their merits and application areas are pointed out through narrating and analyzing them in detial. Furthermore, a new algorithm based on Fourier-transform technique combining with different calculations is proposed, which is suitable to measure steps. The new algorithm overcomes the disadvantages of old one needing datum reference and plane of reference, increasing this algorithm's utility.Keywords：phase-shifting interferometry;wavelength tuning;phase-shifting algorithms- 30
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- 6
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- 1
Published：2020-08-12 -
Improvement of PZT phase shifter in vibration-resistant phase-shifting interferometer
Abstract：The structure of an ordinary piezoelectric transducer (PZT) used as an optical phase-shifter is optimized using the active vibration-resistance techniques for phase-shifting interferometer to improve its mechanical properties with adequate micro-displacement. As the kernel part of a mechano-electronic feedback system of the vibration-resistant interferometer, the optimized PZT works as an optical phase-modulator and a vibration-compensated controller at the same time. On-line testing shows the new structure of PZT phase shifter has gained a time response above 1 000 Hz at amplitude of (/2, and a displacement of about 6 μm.Keywords：Phase-shifting interferometry;active vibration resistance;PZT phase shifter;time response;Displacement- 63
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- 9
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- 2
Published：2020-08-12 -
Improved design of splitters
Abstract：An improved design of splitters has been proposed using the vector diffraction theory to narrow the gap between the design and the splitting effect due to the fact that the real period length, grating depth and substrate depth are not considered in the traditional splitter design. The major difference between the traditional design and the improved design lies in whether the effect of the real grating parameters on the incident beam is taken into consideration while the transmittance function is calculated. Experimental results show that, in comparison with the traditional design, the improved design is closer to reality.- 36
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- 6
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Published：2020-08-12 -
Optical and structural characteristics of low background radiometric calibration facility
Abstract：A low background radiometric calibration facility (LBRCF) consists of chambers and blackbodies, and it features modular structure and optical deflection. The modular structure enables LBRCF to perform several functions, such as radiator calibration, radiometer calibration and radiometric tracing to the source. In LBRCF, standard radiation, reference radiation and the radiation under calibration are coaxial by optical deflection, and the use of large-scale sliding tables is therefore avoided. During operation, LBRCF can be pumped to a vacuum level of 1.33×10-2 Pa (10-4 mmHg). With liquid nitrogen filled, the background temperature of LBRCF is below 80K. All these characteristics enables LBRCF to do spectroradiometry calibration in the target temperature range -60℃ to 80℃.Keywords：radiometric calibration facility;spectroradiometry;low background;vacuum;module structure;calibration- 28
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Published：2020-08-12 -
Design and development of fire control target verifiers
Abstract：The functional requirements, operating principles, and design schemes, including optical systems and mechanical structures, of fire control target verifiers are briefed. The line field of view of the camera gun calibrator reaches 35.36±0.5 mm; the field of view of OB reading observation mirror reaches 24°, its diopter is +3°～-4°, and both horizontal and vertical adjustments are 180°; the accuracy of the graduation scale is 1', the eccentricity at the central intersection point is less than ±0.01, the nonstraightness of reticle is no more than 0.002, the tolerance for the coincidence of the cross center of the adjusting plane glass on the camera gun with the reticle center of the head-up display is ±03 micrometer, and the tolerance for the reticle center on the head-up display and the camera gun calibration point on the target board is 20 mm.Keywords：camera gun;head-up display;target verifier- 53
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- 9
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- 3
Published：2020-08-12 -
Design of control system for X-ray industrial computed tomography (CT) generation-Ⅱ scanning motion
Abstract：Two motion control schemes are proposed to realize the generation-Ⅱ scanning by analyzing the characteristics of X-ray industrial computerized tomography (CT), and two scanning schemes are suggested to improve the scanning efficiency by analyzing and comparing the scanning motion with rotation of the generation-Ⅱ scanning method. The distributed control system consisting of upper and lower computers is then designed together with control circuits and computer software, and experimental results have been obtained as expected.Keywords：X-Ray tomography;scanning imaging;motion control;upper computer and lower computer;single chip computer- 27
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- 7
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Published：2020-08-12 -
Finish cutting of GFRP by ultrasonic vibration
Abstract：In order to improve the machinability and machining accuracy of glass fibre reinforced plastic (GFRP), GFRP is finish cut using ultrasonic vibration. Experimental results indicate that the phase parameters of GFRP fibres with respect to cutting direction change in the circumferential direction at cycle; the variation of surface roughness with the phase angle under different cutting conditions is sinusoidal with maximum roughness at 45?; an increase in amplitude causes an obvious drop in roughness; the variation of roughness with cutting speed is extremal, and roughness is minimum at 100 m/min; the surface roughness goes down when the feed is less than 0.06 mm, the roughness increases much faster when the feed is more than 0.06 mm, and the increase in roughness slows down when the feed is more than 0.09 mm; the influence of cutting depth on roughness is a monotonous rising trend. It is concluded from the experimental results that ultrasonic vibration cutting can half the surface roughness and improve the machining quality of GFRP.Keywords：ultrasonic vibration;cutting;glass fiber reinforced plastics;surface roughness- 40
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- 7
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- 1
Published：2020-08-12 -
Application of pseudorandom code in absolute photoelectric angle encoder
Abstract：The encoding method, the key technology and the characteristics of pseudorandom code absolute photo electric axial angle encoder are detailed. M sequence pseudorandom code is used for encoding the pseudorandom code absolute encoder, double slit technique is used to perform time sharing reading and ROM is used as the coding device. Multi-bit information can therefore be stored on a single track, using pseudorandom code.Keywords：photoelectric angle encoder;absolute encoders;Gray code;matrix code;pseudorandom code- 49
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- 20
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- 7
Published：2020-08-12 -
Image composition based on EIS model
Abstract：The characteristics of image sequence acquired in a ship-borne TV reconnaissance system are analyzed, and an electronic image stabilization algorithm based on these features is proposed. Detection of image features, estimation of image motion vector, and ways of image composition are detailed. The algorithm can be simplified according to the real motion state of the ship-borne TV reconnaissance system to achieve high precision. The ship image sequence can be stabilized using this algorithm and the results can be assessed by the fidelity of image sequence and image difference. Test results show that this algorithm can be used to achieve better real-time stabilization of image sequence.Keywords：electronic image stabilization;image sequence;features- 60
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- 11
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- 7
Published：2020-08-12 -
Miss distance error due to rotation of CCD sensor imaging surface and its testing method
Abstract：The miss distance measurement error due to the rotation of the CCD sensor imaging surface in a video measurement system is analyzed with some relative mathematical models established, and the variation of this kind of error is discussed for different rotation angles of the imaging surface. How this measurement error can be checked and corrected are briefly discussed. Actual inspection shows the ways mentioned above can correct the miss distance measurement error resulting the rotation of the CCD sensor imaging surface and improve the accuracy of miss distance measurement, and it is suitable for an IR video measurement system.Keywords：quantity of miss distance;error-correction;CCD sensor;imaging surface;testing method- 53
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- 6
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- 2
Published：2020-08-12 -
Principle and application of miniature aspheric surface profilometer
Abstract：A miniature aspheric surface profilometer with a usable accuracy of 1～2 μm was designed and assembled to compensate the LOH SPHEROMATIC 50SL in our lab to ensure the grinding precision of optics. Experiments and analyses proved that the miniature aspheric surface profilometer meets the testing requirements of laboratory and optical shop for surface finishing, and it is suitable for final testing of optical elements with medium and low accuracy requirements.Keywords：profilometer;aspheric processing- 46
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- 11
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- 6
Published：2020-08-12 -
Improvement of DSP image processing real-timeness
Abstract：Data-joint transmission, a new way of data transmission, is proposed to make the data transmission easy in the DSP real-time image processing system. Taking TMS320C6201 DSP as an example, DMA is used to support several structural data transmission functions, and rational joint of image data can be easily achieved by writing the control words into the DMA registers, thereby improving the DSP data transmission efficiency. Experimental results prove that data-joint transmission is feasible and efficient, and it can be used to significantly improve the real-timeness of DSP image processing system.Keywords：TMS320C6201;data-joint transmission;image processing;real-time processing- 31
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- 6
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- 6
Published：2020-08-12 -
Restoration of field-curved images
Abstract：A restoration scheme is proposed for space-variant image degradation resulting from curvature of field in imaging systems. Providing that the inverse transfer function of an imaging system is represented as the Taylor polynomial series, due to the fact that the product of the inverse transfer function and a degraded image is the Fourier transform of the corresponding restored image, and consequently, the image is restored by computing the linear combination of the original image and its derivative images. The actual restoration results demonstrate that the restoration scheme makes the definition of a space-variant degraded photo roughly uniform in the entire image region.Keywords：curvature of field;space-variant system;image restoration- 48
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- 6
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- 2
Published：2020-08-12 -
Image segmentation approach based on new multifractal feature vectors
Abstract：By computing the spectra associated with different kinds of capacities defined from the grey levels, a new feature vector composed of different kinds of multifractal spectrum of Choquet capacities is proposed, the adaptive FKCN model presented in this paper overcomes the shortcomings of classical algorithms and determines the network structure automatically according to the singularity exponents and spectrum for sum, max, min, iso and capacities of the image. The approach proposed can fully extract the texture information and provide accurate classification results for different textures. Experimental results indicate that, in comparison with the Jacques LEVY, the algorithm proposed has better segmentation quality, improves convergence, and reduces clustering errors as well.Keywords：multifractal;Choquet capacities;image segmentation;fuzzy neural network- 48
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Published：2020-08-12 -
Extraction of symbol line-features based on improved Hough transformation
Abstract：In order to correctly extract the line-features of symbols and some of their attributes, Hough transformation has been improved based on the analysis of its limitations, and it has therefore the additional inspection of line continuity and extraction of associated attributes, such as number, direction (angle), start and finish of lines. Experimental results show that the algorithm proposed can be used to extract symbol lines and some of their attributes, and it can be used for extraction of symbol features in other recognition systems as well.Keywords：mathematical expression recognition;Hough transformation;line detection;feature extraction- 38
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- 9
Published：2020-08-12 -
Study of fault signals from main bearing of internal-combustion engine using chaos and fractal theories
Abstract：In order to study the nonlinear dynamics of unsteady signals from reciprocal machines, taking the relation between vibration signals and fault clearances of a main bearing in an internal-combustion engine as an example, in addition to the mechanical analysis of the main bearing, fault experiments were carried out with varied main bearing clearances to get vibration signals, and those signals were proved to be chaos signals. The changing relation between clearances and their related dimensions and kolmogorov entropies was established by calculating their correlation dimensions and kolmogorov entropies. And the feasibility of studying this kind of non-steady signals using chaos and fractals theories was proved.Keywords：internal-combustion engine;Chaos;fractals;main bearing- 36
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- 8
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Published：2020-08-12 -
Design of multiple-channel filter based on Fabry-Perot structure
Abstract：Based on Fabry-Perot structure, a multiple-channel filter is obtained in theory by changing the structure of spacer layers. In order to control the position and width of adjacent routeways, several materials with different refractive indexes and different cavity structures were studied. It is concluded that the width of adjacent routeways can be changed by changing the structure of spacer layers or adopting different materials.Keywords：multiple-channel filter;Fabry-Perot structure;reflection-phase;cutting band- 36
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- 3
Published：2020-08-12 -
Polarization effects in optical thin films
Abstract：Optical thin film at non-normal incidence is equivalent to a combination of a dichroic linear polarization and a retarder, and it can be described in Jones calculus. This feature can be used to cancel the unwanted polarization effect in an optical system, and to fabricate phase retarders. The polarization characteristics of the corner-cube prism for YAG laser are analyzed, and two kinds of optical thin films are designed to compensate its polarization properties. The phase shift of a dielectric media HR film is then analyzed and optimized to obtain a dielectric media polarization-preserved HR film.Keywords：optical thin film;polarization effects;phase retarder;Jones calculus;corner-cube prism- 58
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Published：2020-08-12
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