
Opto-electronic imaging and tracking system must be guaranteed to recognize a variety of targets. Meanwhile, the scheduled image processing is a hard real-time processing course. Our studies have developed a real-time tracking fusion approach including pixel-base, feature-based and decision-based fusion, which simultaneously run multiple algorithms suiting to independently analyze and obtain various feature of targets for satisfying different targets in different tasks. A prototype has been developed to adaptively track motive objects. The paper introduces in detail the idea and method of real-time tracking fusion technology, and specifies hardware design and algorithm performance by analyzing embedded parallel architecture. The reliability, stability, adaptivity and real-time performance of the approach have been widely proven in real applications.
Aiming at the algorithm of traditional total variation image denoising and restoration based on the image gradient as its edge indicator, which cannot effectively distinguish between edges and ramps and remove the isolated noise in flat regions, a new edge indicator based on the quadratic differential in the local coordinate system is proposed to improve the traditional model. The improved model can adaptively select the most appropriate denoising scheme based on the edge indicator information of each pixel, and its regularization term and fidelity term can be weighted by the image fine information. And in the aspect of the numerical implementation, a new method based on the variation of the image gradient direction is adopted to discrete the divergence term to better preserve fine details effectively. Numerical experiments demonstrate that the new algorithm is superior to the traditional ones in the aspect of avoiding the staircase effect in ramp regions and preserving fine details.
A novel algorithm for salient region extraction is presented. First, three characteristics graphs of brightness, color, the orientation of the original image are extracted respectively. Then, multi-scale image features of the three characters are combined into one saliency map. Therein the color feature is obtained in frequency domain, which can simplify the algorithm complexity and make it come true easily. In orientation feature extraction, a new characteristic function is used to make the orientation feature map more complete than Gabor function. The experiment results show that the method proposed is easier to be realized and can extract more obvious salient maps than Itti model. In image retargeting we demonstrate that using our saliency prevents distortions in the important regions.
Multi-sensor image registration is very difficult because of their different imaging principles. Referring to the registration of infrared and visible images, a registration algorithm is proposed based on the Harris corner with SIFT description. First, the scale spaces were built, and the scale-invariant Harris corners were selected as feature points. Then, by improving SIFT description method of feature points, ring operator was used to describe feature points. Finally, feature points were matched by the two-way nearest neighbor algorithm, and least squares method was employed to find optimal solutions to affine transform equations. Experimental results show that the registration algorithm is accurate, efficient and stable, and has a good registration result.
The traditional graph-cut algorithm of video moving objects detection is based on the low-order Markov Random Field (MRF). Because of the low order approximation of the energy function, the detected moving objects will be over-smoothing. In this paper, an adaptive graph-cut algorithm based on Euler’s elastica model is proposed, which uses Euler’s elastica model to optimize the objects boundary and to amend the low-order approximation of the energy function. The proposed algorithm can continuously update the model parameters of current frame by Kalman prediction which estimates the number of moving objects pixels and objectives-background pixel-pairs. So the proposed algorithm can detect video moving objects in a continuous optimal mode. Experimental results show that the proposed method can effectively and stably detect moving objects, and the detection results can better meet the requirements of person's visual effects.
Uniformity in point features distribution of feature extraction algorithm at remote sensing image automated registration is a challenging problem. For the purpose of remote sensing image automated registration, a multi-feature image automated registration algorithm is presented based on Scale Invariant Feature Transform (SIFT), Harris-Laplace and Maximally Stable Extremal Region (MSER). Multi-feature and secondary matching greatly promotes the number of matching points, screening by distance makes matching points distribute uniformly and reasonably, and local mutual information takes matching points more accurate. Finally, a high quality (uniform space distribution, accuracy matching points) automated image registration is achieved.
Infrared image with white Gaussian noise is processed by nonsubsampled Contourlet transform. The statistical characteristic of its coefficients is analyzed and generalized Gaussian distribution is used to describe the probability distribution for coefficients. According to characteristics of different energies in each direction of the nonsubsampled Contourlet transform bandpass subbands, a modified Bayesian threshold formula is proposed. In order to overcome the shortcoming of the soft and hard thresholding function, then a new adjustable and adaptive thresholding function is presented. Lastly, the new thresholding function is used to estimate coefficients without noise, and inverse nonsubsampled Contourlet transformation is performed to get denoised infrared image. Experimental results show that our denoising algorithm outperforms the usual wavelet threshold denoising method in peak signal-to-noise ratio and visual quality.
Forward Looking Infrared (FLIR) image quality is of great importance for the detection and tracking algorithms to accurately locate the targets. In the field of Automatic Target Recognition (ATR), present researches on FLIR image quality are mainly related to the content of the scene, while ignoring the influence of imaging degradations on image quality. Through analysis of the cause of noise and blur, and combination with the former simulation methods, a new method was established for noise and blur simulation in images acquired by high-performance FLIR equipment. This method has been applied to analyze the effect of different degrees of noise and blur on image quality, and it can be concluded that noise has adverse effect on image quality, while blur is not always deleterious. Based on this conclusion, denoising method has been adopted in the preprocessing of FLIR image. Comparison among experimental results reveals that denoising method can improve the matching probability more effectively than sharpening method.
This article analyzes how the image motion of infrared imaging equipment is generated in detail, and the infrared imaging equipment is fixed on an unstable platform. The method and algorithm of using micromachined accelerometer to get the image motion vector is proposed, and a measurement system of image motion vector which can be fixed on the infrared imaging equipment is developed. The experiments of image motion measurement and image stabilization are conducted, the results of which are compared to image stabilization through software. The effectiveness of theory and equipment are verified.
Based on a weak reflection Bragg grating, a new distributed temperature sensing network is proposed by combining Wavelength Division Multiplexing (WDM) with Optical Time-domain Reflectometry (OTDR). WDM technology is used to enhance the FBG multiplexing capacity, and OTDR is used for each weak grating for real-time detection, so as to realize the intensive serial multiplexed grating and improve the spatial resolution. Using the tunable pulsed laser as the light source, multiple groups of different center wavelength grating are engraved in weak isometric in one fiber. Reflectivity of three groups is 3%. The center wavelengths are 1 544.660 nm, 1 545.802 nm and 1 546.900 nm three FBG, divided into three groups. In one fiber, quasi-distributed measurement is realized. Experimental results show that, in 5~80℃ temperature range, FBG center wavelength with temperature change shows good linearity, linearity reaching more than 99.6%, the temperature measurement resolution of up to 0.11℃, a spatial resolution of 2 m.
The relationship of effective index and ridge height under different ridge width, core height and the short side width of the core plate were systematically studied in effective index method with organic polymer asymmetric ridge waveguide as the object. The result shows that both the structures of ridge waveguide had the same characteristics. They were the effective index increased with increasing of ridge height, ridge width when core height was constant and with increasing of core height when the ridge height, ridge width were constant. For the asymmetrical ridge waveguide, the effective index decreased with reduction of the short side width of the core plate when other conditions were constant. The result is valuable for reference in terms of application of the organic polymer asymmetric ridge waveguide.
A distributed optical fiber sensor system based on coherent Rayleigh backscattered theory is set up, and an optimized Erbium-doped fiber amplifier (EDFA) is designed. The influence of few key factors such as extinction ratio, sensing distance and reflections from the sensing fiber on backscattered profile are analyzed. Experiments show that: the peak power and extinction ratio of injection pulse can be obviously improved through properly adjusting the offset voltages of Electro-Optic Modulator and EDFA. Because of the limit of extinction ratio of pulse, the short distance sensing is easier to obtain good scattered waveforms than long distance sensing. Eliminating the Fresnel reflections from the front-end and back-end of the sensing fiber can also improve the quality and stability of the scattering signals.
Based on the index modulation method, an Interleaved Sampled Fiber Bragg Grating (ISFBG) is designed by changing the index modulations of the adjacent sub-gratings in each seeding grating. And the characteristic of reflecting spectrum of ISFBG is analyzed by transfer matrix method. The results show that the number of reflection channels of ISFBG can be tuned for the structure of adjacent sub-gratings with varying index modulations. The reflectivity of main reflection peaks is dependent on the sub-gratings with large index modulations and decreases slightly with the increase of index modulation difference. The secondary reflection peaks are uniformly distributed in the middle of two main reflection peaks and their reflectivity increases with the increment of index modulation difference. Furthermore, the channel spacing of ISFBG can be compressed with channel number increasing by the multiple-phase-shift technique.
In various types of mechanical spindle drive, the torque is one of typical variables for reflecting the dynamic performance of mechanical system. By analyzing the torque, it can be available for the performance parameters of the whole drive system. There is no effective method for torque measurement under extreme environment, such as high temperature, strong impact, and strong vibration and so on. The paper brought out a new non-contact torque sensor, which adopt alternating electromagnetic induction ball grid technology, and was composed of specially designed ring-space arrays and dedicated magnetic detector. And it took emphases on the structure, principle of torque sensor. A simulation model was built to study the electromagnetic distribution characteristics of the detector by ANSYS. The experimental results verify that the detector can meet the dynamic torque measurement requirement in the extreme environment.
To reduce the acceleration time and improve the stability of the scanning speed during the exposure process of the wafer stage, a fifth-order S-curve is proposed. The third derivative of the acceleration is designed as a constant, and the position and speed formulas are calculated based on integration method. Optimization index with minimum time and jerk is proposed, and a modified fifth-order S-curve is designed. Simulation results show that the S-cure can ensure that the wafer stage speeds up to the scanning speed quickly and can stabilize in a short time. The modified S-curve can reduce the step time effectively, and the step movement curve is smooth.
The fabrication of X-ray grating and silicon-based micro-channel plate on the large area silicon wafer involves the thermal oxidation of silicon which can greatly deform the wafer with microstructures of high-aspect-ratio, hindering the practical applications of the silicon-based devices. The thermal oxidation deformation of a 5-inch silicon wafer was experimentally studied and the mechanical factors affecting the deformation were analyzed. The method to decrease the deformation was also provided. The wafers with microstructures of high aspect-ratio were firstly fabricated by use of the photo-assisted electrochemical etching technique, and then different thermal oxidation methods were experimented, and lastly the deformation was compared. The results show that the deformation of large area silicon wafer can be decreased greatly by adjusting the thermal oxidation temperature to minimize the thermal expansion coefficient and by exerting an external force on silicon wafer during the thermal oxidation process.
Dispersive objective is the key component of Chromatic Confocal Microscope (CCM). The measuring range of CCM depends on the chromatic aberration of dispersive objective, and the nonlinear axial chromatic aberration of dispersive objective would lower the sensitivity of CCM. To achieve large axial chromatic aberration, optimization method of selecting materials combination is proposed based on the principle of linear axial chromatic aberration. The optimization model is presented and solved to get the optimal solutions, which are the materials combinations of largest linear axial chromatic aberration. The results from optical design software indicate that lenses of optimal materials combinations could achieve largest linear axial chromatic aberration among the glass catalog. With the optimal materials combination, a dispersive objective was designed for CCM. The well designed objective could provide large linear measuring range while having a short tube length. Optimization and selection of materials are significant for dispersive objective design to heighten the performance of CCM.
A method which adopted plane-parallel plate as active optics element is proposed to compensate the astigmatism because of non-uniformed illumination in projection objective. The supporting structure is designed and analyzed for the plane-parallel plate with Φ140 mm diameter. The key parameters of supporting structure, the thickness of lens and the driving force are analyzed to receive the influence rules to the surface quality. The results indicate that the influence of the key parameter and driving force on the surface quality seems to be linearity, and the influence of lens thickness on the surface quality seems to be exponential. The figure is received by changing the value of driving force. The results indicate that high order aberration which the supporting structure brings is negligible when compensating. The resolution of astigmatism compensation is 2 nm. The designed and analyzed results provide reference for selecting of active optics lens, designing of supporting structure and experiment.
Rational lightweight design is the practical and effective method which can reduce the weight of large aperture mirror and decrease the influence of deadweight and other deformation on the surface figure. The 1 200 mm aperture primary mirror is taken as the research object. According to the principle of equal rigidity and considering current process technology, two lightweight design schemes are worked out. Based on the results of finite element analysis, the structure with RB-SiC technology, semi-closed back, partial cone rear surface and sector hole are judged to be the preferred scheme at last, and the primary mirror is manufactured successfully.
Dynamic backlight plays an important role in reducing power consumption of liquid crystal displays. Considering it is more important to make sure a high quality of the displayed image when reducing power consumption, a new algorithm was proposed for local backlight dimming of liquid crystal displays. According to the algorithm, PSNR (the peak signal-to-noise ratio) =30 was the lowest standard to guarantee the quality of image, by which the backlight luminance was gained and the distortion was controlled into a certain range. Meanwhile, a method is also proposed to simplify the calculation. Successive searches will be made on the basis of the 0.7, 0.8 and 0.9 times of the maximum luminance, and stop when RPSNR≥30. In order to guarantee the quality of the image, the 0.7 times of the maximum luminance is used as the minimum backlight luminance. It saves much time in calculation and is better applied in hardware.
Head-up Display (HUD) is a large aperture optical system with a large view field. Head-moving is the usual measurement, but has a low accuracy, and relying on the subjective judgment of the inspector. In order to improve the testing accuracy and efficiency of head-up display’s optical parallax, and avoid the subjective judgment of the inspector, an optical parallax auto-testing system was introduced. The image of head-up display was collected by the CCD camera, and then the camera moved in the out aperture. The difference was calculated by comparing the image collected at the edge of the out aperture, and then the head-up display’s optical parallax was obtained. The testing principle was introduced in detail, and the structure of the optical parallax testing instrument was introduced in detail. Then the parameters and testing accuracy were also analyzed. At last, the testing accuracy of optical parallax was analyzed in several.
A solid-state volumetric true 3D display consists of a data transmission, image processing module, a high-speed color projection module, a display module and control circuits. The display module contains of light shutters, which display a dark and fuzzy picture due to the brightness decay when lights transmits. In addition, the display has a serious problem of screen flicker owing to the low response time and low refresh rate. This paper exploits a new polymer stabilized cholesteric texture shutter by adding a small amount of ploymer and chrial dopants to liquid crystal. The maximal transmittance is 88% and the response time is lower than one millisecond. When applied in true 3D display, it can display a clear, stabilized and non-flicker picture, completely satisfying the demands of true 3D display.
Two-dimension photonic crystal slab micro-cavity exist radiation loss in the vertical direction, which decreases the quality factor and restricts its application. According to the Fourier analysis of photonic crystal slab micro-cavity loss, this paper adopts the method of modulating cavity mode profile, which reduces the distribution of wave vector in radiation lead area, decreases the cavity loss, and realizes the optimization of cavity quality factor. Facing to the structure design of two-dimension photonic crystal slab L3 micro-cavity, this paper gives a numerical simulation to photonic crystal slab L3 micro-cavity. The simulation results show a great improvement of cavity quality factor, and validate effectiveness of the optimization method for photonic crystal micro-cavity quality factor in this paper.