The basic principle of Phase-Inversion Symmetric Method was studied, this method was applied to Spread Spectrum communication system, and a system frame of Spread Spectrum communication system based on Phase-Inversion...
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The distributed routing protocol is widely used in wireless sensor networks. But it is mainly designed for homogeneous networks and also has the disadvantages of irrationality of choosing cluster head and unbalanced e...
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Based on fractional Fourier transform, the double folding operation is studied and introduced into image encryption. This method can implement a kind of the encoding with real number. This characteristic is convenient...
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At present, there are two main types for medical CT image surface reconstruction: one is way of the slice contour, the other is voxel reconstruction, the former method is simple, easy for calculation and much classica...
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The optically modulated scatterer (OMS) technique is developed for the electromagnetic field distribution measurement with minimum disturbance to the field under test. In this letter, we present a novel method to meas...
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Free space optical communicationtechnology approach has a number of advantages;unfortunately, it can be severely affected by atmospheric turbulence. Adaptive optics is the technology for correcting random optical wav...
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To solve the problem of online measuring large-scale equipments, the paper proposes a stereo vision coordinate measuring system based on optical bar with the function of measuring and calibration, which overcomes the ...
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Based on analyzing the structure characteristics of a multivariable grey model, a novel design method of grey prediction PID control is proposed according to the control requirements of a discrete system. Combining th...
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Fiber laser gas sensors based on the intra-cavity absorption spectroscopy require the use of gas cells. We propose a simple and reliable gas cell using graded-index fiber lens (GFL) based all-fiber collimator. Convent...
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ISBN:
(纸本)9780819476630
Fiber laser gas sensors based on the intra-cavity absorption spectroscopy require the use of gas cells. We propose a simple and reliable gas cell using graded-index fiber lens (GFL) based all-fiber collimator. Conventional gas cells usually utilize direct fiber-to-fiber coupling without collimators or graded-index (GRIN) lens as collimators. Direct fiberto- fiber gas cell has simple configuration, but it suffers from high coupling loss and stray light interference. Gas cells applying fiber pigtailed GRIN lens are advantageous to achieve low coupling loss. However, fiber pigtailed GRIN lens requires accurate and complicated alignment and glue packaging which could compromise long term reliability and thermal stability. The proposed technique fabricates all-fiber collimators by simply splicing a short section of gradedindex fiber to single mode fiber which is both compact and durable. With that collimator, the gas cell can be fabricated very thin and are suitable for extreme environments with high temperature and vibration. In this paper, we have carried out experiment and analysis to evaluate the proposed technique. The coupling efficiency is studied versus different GFL gradient parameter profiles using ray matrix transformation of the complex beam parameter. Experiments are also done to prove the practical feasibility of the collimator. The analysis indicates that gas cell using GFLs can overcome the disadvantages of traditional design;it may replace the conventional gas cells in practical applications. 2009 SPIE.
In order to enlarge the measurement range of stereo vision measurement system and realize the accurate measurement for large-scale workpiece, the paper proposes the 3D(three-dimensional) splicing method based on contr...
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