Proceedings Volume 4929

Optical Information Processing Technology

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Proceedings Volume 4929

Optical Information Processing Technology

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Volume Details

Date Published: 16 September 2002
Contents: 13 Sessions, 78 Papers, 0 Presentations
Conference: Photonics Asia 2002
Volume Number: 4929

Table of Contents

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Table of Contents

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  • Theory and Applications I
  • Theory and Applications II
  • Theory and Applications III
  • Theory and Applications IV
  • Neural Networks and Wavelet Transform
  • Optical Communications
  • Photonic Device and Technology I
  • Holographic Information Processing
  • Pattern Recognition I
  • Pattern Recognition II
  • Photonic Device and Technology II
  • Photonic Device and Technology III
  • Poster Session
  • Theory and Applications I
Theory and Applications I
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Modular optical systems for nonlinear data processing and manipulation
David Mendlovic, Zeev Zalevsky, Eran Gur
The paper reviews the usage of modular optical systems for nonlinear data processing and manipulation. The paper starts with presenting an algorithm for multi stage image processing in which a derivation of instillation having N stages of binary filters is used in order to generate general transformation and then to apply it for pattern recognition. Then, optical configuration that implements second order of Volterra operator is used for non-linear control processes. In the third part of the paper a fuzzy logic based algorithm is used in order to optimize the design of multi stage interconnection network (MIN). The optimization is done in a sense of minimal number of switching modules and minimal number of switching operations per routing stage. In the fourth part we present a technique for optical generation of fuzzy based rules. In the last part of the paper we suggest a fuzzy logic based technique for improving the depth of focus in an imaging system using as single-phase only filter. All the suggested pmcessing configurations are backed up with either simulations or experimental verifications.
Spatially coded moire matching technique for genome information visualization
Jun Tanida, Kouichi Nitta, Akihisa Yahata
A simple and informative method for exploring genome information is presented. The method is based on a spatially coded moir´e matching technique to visualize a relation between two genome sequences. The basic idea and its extensions to amino acid sequence analysis and multiple sequences comparison are explained with some experimental results.
Theory and Applications II
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Fractional Fourier transform: applications in information optics
The fractional Fourier transform (FRT), which is a generalization of the well-known ordinary Fourier transform, is being increasingly used in many applications of optics. The FRT is richer in theory and more flexible in applications and at the same time not more costly in implementation. Pattern recognition, one of the widely pursued application areas in the domain of optical information processing, has benefited immensely with the use of FRT in optical correlators. Similarly optoelectronic encryption and decryption techniques have derived considerable strength from the use of FRT. The present paper reviews the recent investigations in the above-mentioned areas with special reference to the work carried out by the Photonics Group, ITT Delhi.
Novel depth extraction algorithm incorporating a lens array and a camera by reassembling pixel columns of elemental images
Stereo matching is a method to obtain the depth information from images and is one of the most important issues in the field of machine vision. Contrary to the conventional stereo matching algorithms that involve two or more wellcalibrated cameras, the depth extraction scheme using a lens array is compact and requires no calibration since only one camera is involved in its setup. In this paper, we present a novel depth extraction algorithm using a lens array. The proposed method rearranges horizontal positions of the pixels from the collection of the elemental images to form subimages horizontally leaving the vertical positions of the pixels unchanged. On this rearranged images, we apply a correlation-based multiple-baseline stereo algorithm in properly modified form. The main feature of the proposed method is its ability of exact depth extraction from the extremely periodically patterned object scenes. Additionally, the proposed method enlarges the available depth range due to the reverse dependency of the disparity on the depth between the elemental image and the sub-image. We prove our idea by applying our method on the object scene generated by a computer. The simulation result shows the proposed method extracts precise depth information from the scene of the object with a periodic texture pattern.
Digital optical electronic hybrid system for three-dimensional shape measurement
Jing Zhao, Jingang Zhong, Fengli Li
A new experiment system of three-dimensional shape measurement is presented. The advantages and the disadvantages are analyzed. In this experiment system, using digital light projector replaces traditional projector, and electronical grating replaces traditional grating. Obviously, the system has many advantages such as higher precise, easier to realize, etc. But there still are some disadvantages because of the characteristic of the system. We designed experiments to discuss the errors introduced by the system and look for the best system parameter. From the last result, we can conclude that the system has high practical value.
Boundary modulated pattern in a passive optical system
Chunping Li, Ke Shen
Pattern formation with boundary effects in a passive cavity containing Kerr medium and driven by a coherent stationary plane-wave field was studied in this paper. Through numerical simulations we conclude that many pattern characteristics are all greatly relevant to system boundary conditions in nonlinear dynamic systems besides system control parameters.
Experimental verification of screen effect and dynamic multiple scattering theory
H. C. Kandpal, Sisir Roy, Menas Kafatos
The multiple scattering theory which produces Doppler-like wavelength shift,even, when the source and the intervening medium are at rest with respect to the observer has been recently verified in laboratory experiments. In the experiments, light from Hg lines propagating through anisotropic plasma medium has been shown to produce redshift as well as broadening. These results may signify important developments in statistical optics as well as in observational cosmology.
Fourier transform property of lens based on geometrical optics
Suganda Jutamulia, Toshimitsu Asakura
Coherent optical information processing is almost entirely based on the Fourier transform property of a lens. A Fourier transform lens is actually an ordinary lens. If the input transparency is placed in the front focal plane of the lens and illuminated with coherent collimated light (planewave), the amplitude function in the back focal plane of the lens will be the Fourier transform of the input transparency as shown in Fig. 1. A 4-f coherent optical processor consists of two lenses as shown in Fig. 2, thus it performs two Fourier transforms successively. The first lens transforms the input function from space domain into frequency domain, and the second lens transforms back the frequency function from frequency domain to the output function in space domain.
Theory and Applications III
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Spatial code division multiplexing in optical data processing
Zeev Zalevsky, David Mendlovic, Jonathan Solomon
The increasing popularity of optical communication has also brought a demand for broader bandwidth. The natural trend was to implement methods from traditional communication on optical fibers. One of the most effective "traditional" methods is code division multiple access (CDMA). In this paper, we suggest the use of this approach for spatial coding applied to images, and for superresolution. In spatial coding, the approach is to multiplex several filters into one plane while keeping their mutual orthogonality. It is shown that within specific restrictions the output of all the filters can be sampled in the original image resolution and fully recovered through an all-optical setup. A theoretical analysis of such a setup is brought as well as experimental demonstrations are presented. Implementation for invariant pattern recognition is suggested. In superresolution, we propose using code division multiplexing in order to transfer a wider range of frequencies. Traditional methods for super resolution have sacrificed field of view for resolution. These methods multiplexed the signal on different carriers. Code division multiplexing for such a usage, has been shown to have superior capabilities, nearing almost Shannon's channel capacity limit. To enable such multiplexing we propose a unique setup that creates an incoherent cosine transform of the image. A theoretical analysis of the setup is brought and later compared with the empirical results.
Image encryption with virtual optics
Xiang Peng, Zhiyong Cui, Tieniu Tan
A new method based on the concept of virtual optics for both encryption and decryption is proposed. The technique shows the possibility to encrypt/decrypt digital information. Virtual wavelength, virtual focal length, and virtual diffractive distance can all be used to design locks and keys for image encryption. Numerical experiments are presented to test the effectiveness of the method. The possible dimensions of keys are roughly estimated and show a high security level.
Theory and Applications IV
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Nonscanning selective-illumination optical sectioning microscope theory
Jinyi Xiong, Ying Zhou, Guozhong Wu, et al.
By modifying the illumination of the ordinary microscope, the sectioned image of the object is then available at the image plane but with the unwanted ordinary image superimposed. After processing these composite images by decoding algorithm, the optically sectioned images substantially similar to those obtained by confocal microscope can finally be got. Here in this article, we derive the explicit formula of the image formation by using the mutual intensity theory and thus explain the sectioning ability and the decoding theory of this new sectioning microscope. We can conclude that this kind of selective-illumination microscope is actually a selective-illumination microscope.
New analytical method for design of PIF used in color separation/combination optical engine for LCOS display
Jinyi Xiong, Ying Zhou, Guozhong Wu, et al.
The principal of this new analytical method is to analytically get the coefficients of exponentials, the sum of which approximates the desired rectangular spectrum function of PIF. An arbitrary desired rectangular spectrum could be approximated by a continuous function with ripples. This function can be written in polynomial mathematically, with many unknown coefficients and known special points, such as extremum points and the point of half transmission. A set of equations could be written for those special points, through the solving of which the unknown coefficients will be determined. The following procedures will be the same as the available synthesis procedures of birefringent networks. This method will greatly simplify the design procedure and give more freedom in control of the design spectrum output. An example is given for 5-piece-birefringent-crystal PIF.
Laser application for ship anticollision
Dingyu Liu, Hong-zhi Bao
This paper provides a new technical system to preventing collision of encountered ships at water transport area.which including multi-ring detection technique (MRDT), light spot preservation technique (LSPT) and multi-ring compensation technique (MRCT) as its kernel. The comprehensive result introduces to the apparatus called automatic laser plotting aids (ALPA
Neural Networks and Wavelet Transform
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Genetic-algorithm-based tri-state neural networks
Chii-Maw Uang, Wen-Gong Chen, Ji-Bin Horng
A new method, using genetic algorithms, for constructing a tri-state neural network is presented. The global searching features of the genetic algorithms are adopted to help us easily find the interconnection weight matrix of a bipolar neural network. The construction method is based on the biological nervous systems, which evolve the parameters encoded in genes. Taking the advantages of conventional (binary) genetic algorithms, a two-level chromosome structure is proposed for training the tri-state neural network. A Matlab program is developed for simulating the network performances. The results show that the proposed genetic algorithms method not only has the features of accurate of constructing the interconnection weight matrix, but also has better network performance.
Modified CPN and its application in data fusion for target classification
LiHong Niu, GuoQiang Ni, Mingqi Liu
In view of the features of multi-sensor data fusion and target recognition, a modified counter-propagation neural network (MCPN) is proposed. The competitive layer of the MCPN is based on Dignet algorithm but not Kohonen clustering network (KCN). And the MCPN based fusion architecture at decision level is presented and applied to multi-sensor data fusion for target classification. The proposed MCPN and the fusion architecture are studied using simulated data. The experimental results show that the fusion classification can be effectively realized with the MCPN compared with standard counter-propagation neural network (CPN) and back-propagation network (BPN) of the same size. Finally, to further illustrate its effectiveness for practical uses, the experiments are conducted using real-world data acquired with a target tracing system of FUR and TV camera. The results indicate that the MCPN and its fusion architecture are workable
Particle tracking and sizing by using wavelet analysis and reconstruction of envelope function
Siriwat Soontaranon, Joewono Widjaja, Toshimitsu Asakura
A new digital method for measuring size of particle and its position from in-line particle holograms is proposed. In our proposed method, the position of particle is obtained by using a wavelet transform, while its size is retrieved by a reconstruction of envelope function. Usefulness of our proposed method is experimentally verified. The system limitation of the method is discussed.
Pattern recognition for optical PSI images of surface topography using wavelets
Xiangqian Jiang, Shaojun Xiao, Liam Blunt
This paper proposes a novel philosophical approach using Wavelet and Radon Transform for addressing topographical features of surface from a PSI image. In this work, a combined technique using the Wavelet and Radon Transforms has been investigated and developed to achieve the forensic dissection of PSI image data. As a result, the isolated point-like features on a PSI image can be extracted using the wavelet transform with artifact free thresholding method, and the curve-like features on a PSI image can be identified using the Ridgelet Transform (Multi-Wavelet-Radon transform). Case studies are conducted using a series of femoral heads to demonstrate the application of using the new wavelet model in the assessment PSI images of these surfaces.
Application of wavelet transform in characterization of fabric texture
Chandra Shakher, S. M. Istiaque, Shashi Kumar Singh
In this paper we present an opto-vision system for image processing of fabric texture using symlet wavelet transform to locate different types of defects in fabric and find the repeat texture of fabric without any priori information. The system is also capable of characterizing the texture of fabric not having obvious repeat pattern. The proposed methodology is able to measure the warp, weft diameter and spacing per unit length per yarn and percentage of their coefficient of variation (C.V%). The two dimensional wavelet transform of the image can distinguish texture feature along with yarn spacing in the weave. The information obtained from the image processing is considered to be significant for purposes of textile design to obtain a basic knowledge as to the visual information contained therein.
Optical Communications
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IP router by using spectral hologram as address bank
A new method for implementing optical header recognition by using spectral hologram as address bank is proposed as a cost-effective way of realizing routing in IP-over-photonic networks. The spectral hologram is employed to store the header addresses. The header recognition is performed by taking a correlation between an incoming optical address with those stored in the hologram. Due to a difference of spectral response between commercially available holographic media and optical fibers, a second-harmonic optical header-address signal is generated and used both in a synthesis of the spectral hologram and in a recognition processes of the header addresses
Improved model for jitter analysis in optical communication system
Chung Jung Kuo, Hung C. Chien, Ni Y. Chang
In an ideal digital transmission system, the pulse stream should consist of a sequence of points equally spaced in time by a quantity T, the inverse of the pulse transmission rate. In practice, the points of actual sequence are randomly deviated from their desired positions. Such timing deviations called timing jitter is usually classified into two main categories; systematic jitter and nonsystematic jitter. The former depends on the transmission signal, while the latter is produced by noise source. It has been verified that systematic jitter accumulation exceed nonsystematic one's. Nowadays, optical systems use optical amplifiers to enhance the transmission signal and recover its timing. Therefore, the influence of clock recovery circuit (CRC) inaccuracies is very significant in optical communication systems since a small timing error may influence the system performance a lot. In this paper, we proposed a new CRC model that can be more powerful to analyze the jitter performance and get the better optical communication results.
Photonic Device and Technology I
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Profile of refractive index of light induced array waveguides in photorefractive crystal
Jifang Liu, Hongwei Zhuang, Manli Hu
In steady state and two dimensions the distributions of the nonlinear refractive index in a photorefective crystals under the conditions of supporting low intensity spatial solitons are studied. It is shown that steady state spatial bright solitons of modulated ThM00 mode Gaussian waveform can form and induce planar array waveguides in photorefractive crystal. The effects of modulating conditions, the intensity of spatial solitons and the external bias electric field on profile of refractive index of the array waveguides is investigated.
Measurement of phase-only characteristic of a commercial LCD
Xiaogai Hu, Wei Xue
In this paper, using redesigning driving and controlling circuit ofliquid crystal panel to measure phase-only modulation characteristics of a commercial LCD. The LC molecule voltage range ofrealizing LCD phase-only modulation characteristics has been found. The experiment results have been given and analyzed. The results indicate that nearly 1.5? phase-only modulation has been obtained.
Optical image amplification in phase-sensitive parametric amplifier
Dezhong Cao, Yue Fei Gong, Lin Zhang, et al.
The scheme of parametric image amplification without using lenses is discussed. The theoretical analysis shows that the scheme is appropriate to a broadband amplifier which assures a high linear gain, a better resolution and noiseless amplification.
Holographic Information Processing
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Holographic memory for high-density data storage and high-speed pattern recognition
As computers and the internet become faster and faster, more and more information is transmitted, received, and stored everyday. The demand for high density and fast access time data storage is pushing scientists and engineers to explore all possible approaches including magnetic, mechanical, optical, etc. Optical data storage has already demonstrated its potential in the competition against other storage technologies. CD and DVD are showing their advantages in the computer and entertainment market. What motivated the use of optical waves to store and access information is the same as the motivation for optical communication. Light or an optical wave has an enormous capacity (or bandwidth) to carry information because of its short wavelength and parallel nature. In optical storage, there are two types of mechanism, namely localized and holographic memories. What gives the holographic data storage an advantage over localized bit storage is the natural ability to read the stored information in parallel, therefore, meeting the demand for fast access. Another unique feature that makes the holographic data storage attractive is that it is capable of performing associative recall at an incomparable speed. Therefore, volume holographic memory is particularly suitable for high-density data storage and high-speed pattern recognition. In this paper, we review previous works on volume holographic memories and discuss the challenges for this technology to become a reality.
Quinone-based-molecule-doped poly(methyl methacrylate) photopolymer for holographic data storage
We present our studies on the photopolymer of poly(methyl methacrylate) (PMMA) doped with quinone-based molecules for holographic data storage. We discuss the recording mechanism involved with the photoreaction of the quinone and olefin bonds. Experimental characterizations, including sensitive wavelength, holographic recording and material M/# are also presented.
All-optical systems based on volume holography
Three all-optical systems, including a fiber displacement sensing system, an angular sensing system and a 2D-to-2D pattern transfer system based on holography interconnect are presented. Photorefractive crystals, the volume hologram recorder serves as the database and signal processor in the systems. All the processes include detection of the external signal, signal transfer, signal processing and the display of results are performed by optical means. Keywords: Volume hologram, Holographic interconnection, Random phase encoding, Angular multiplexing.
Holographic grating recorded in photopolymer composed of photosensitive polymer binder
Dong Hoon Choi, Dejun Feng, Hanna Yoon, et al.
The diffraction gratings in novel photopolymer were fabricated by optical interference method. Holographic recording in new polymer layers can be applied for optical information storage. The hydrophilic and hydrophobic polymers are used with the monomer of acrylamide, which are well miscible with the sensitizing dye of yellow eosin and the charge transfer agent of triethanolamine. Addition of the crosslinking agent bisacrylamide stabilizes the formed structures against thermal and environmental relaxations. We compared the diffraction efficiencies of new polymer samples with that of the conventional photopolymer. Relatively high diffraction efficiency can be obtained from LPOMPP-02 series. The influence of the UV curing on the diffraction grating is also studied when the diffraction efficiency becomes stable. The diffraction efficiency under UV irradiation shows slight decrement and becomes stable at a lower value. The surface topographical change of the photopolymer layer was observed after irradiation of the two polarized lights. The actual periodicity of the surface relief grating is about 1.95-1.98 ?m according to the AFM profiles close to the theoretical value of 1.92 ?m .
Photorefractive holographic interferometry for the measurement of object tilt and in-plane displacement
Yurong Wang, Qingpu Wang, Ping Li, et al.
A novel optical configuration in holographic interferometry (HI) is proposed for measuring object tilt and in-plane displacement. In this holographic interferometer a photorefractive crystal (PRC) is used as holographic recording material, which can be reusable and do not require additional processing (development, fixing, etc.), and the procedure of real-time interferometry is adopted. Theoretical analysis and preliminary experimental results are given.
Pattern Recognition I
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High-speed optical object recognition processor with massive holographic memory
Tien-Hsin Chao, Hanying Zhou, George F. Reyes
Real-time object recognition using a compact grayscale optical correlator will be introduced. A holographic memory module for storing a large bank of optimum correlation filters to accommodate large data throughput rate needed for many real-world applications has also been developed. System architecture of the optical processor and the holographic memory will be presented. Application examples of this object recognition technology will also be demonstrated.
Image invariant moments for shape description
Yunlong Sheng, Ziliang Ping, RiGeng Wu
We show that the transformation with radial polynomial and circular Fourier kernel of two-dimensional image can generate image moments, which are invariant to rotation, translation and scale changes. Among them the orthogonal Fourier-Mellin moments using the generalized Jacobi radial polynomials show better performance that the Zernike moments. We introduce new Chebyshev-Fourier moments using Chebyshev radial polynomials, which improve the behavior of the orthogonal Fourier-Mellin moments in regions close to the center of image. Experimental results are shown for the image description performance of the Chebyshev-Fourier moments in terms of image reconstruction errors and sensitivity to noise. In the cases of binary or contour shapes the Fourier-Mellin moments of single orders are able to describe and reconstruct the shapes.
Phase-shifting joint transform correlator with a wavelength-shifted laser diode
A joint-transform phase correlator is presented for processing multiple-pattern recognition that uses the six-step phaseshifting interferometer with a wavelength-shifted laser diode. The correlation peaks are obtained by the numerical Fourier transformation of a measured phase in an on-axis joint power spectrum. Multiple-pattern phase correlation can be performed to demonstrate high discrimination without the intermodulation owing to zero optical path differences between multiple targets in the interferometer. The experimental results are shown.
Pattern Recognition II
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Distortion-invariant color image recognition by the joint transform correlator with a real-valued reference function
Chulung Chen, Wei-Jun Wu
A novel phase-encoded amplitude-modulated joint transform correlator (PAJTC) technique is presented, which yields superior output correlation signals and better noise robustness than a classical JTC. In the proposed PAJTC technique, firstly, the input targets are encoded with an application of a phase mask, and then the joint power spectrum (JPS) is multiplied by an amplitude-modulated filter (AMF) of the reference object before the inverse Fourier transforming. An enhanced amplitude-modulated filter, in which the modulation factor varies according to the noise presented in the input scenes, is used in the PAJTC technique. The PAJTC technique eliminates extraneous signals especially for the JTC with multiple input targets. An optoelectronic implementation schematic diagram for the PAJTC technique and computer simulations of the performances of the classical JTC and the PAJTC for comparison are presented.
Phase-encoded amplitude-modulated joint transform correlation
Chun Li, Yuying An, Xiaodong Zeng
A novel phase-encoded amplitude-modulatedjoint transform correlator (PAJTC) technique is presented, which yields superior output correlation signals and better noise robustness than a classical JTC. In the proposed PAJTC technique, firstly, the input targets are encoded with an application of a phase mask, and then the joint power spectrum (JPS) is multiplied by an amplitude-modulated filter (AMF) of the reference object before the inverse Fourier transforming. An enhanced amplitude-modulated filter, in which the modulation factor varies according to the noise presented in the input scenes, is used in the PAJTC technique. The PAJTC technique eliminates extraneous signals especially for the JTC with multiple input targets. An optoelectronic implementation schematic diagram for the PAJTC technique and computer simulations of the performances of the classical JTC and the PAJTC for comparison are presented.
Real-time weld defect inspection system in x-ray images
Yi Sun, En-Liang Wang, Peng Zhou, et al.
Detection of weld defects is still done by the human interpreter. The problems of this process are subjective, inconsistent, labor intensive and fatigue of the interpreter. It is desirable to develop a computer-aided system to assist the human interpreter in evaluating the quality of welded part. In this paper, a real-time weld inspection system is presented. The system consists of three steps. First, extracting the weld part within the whole image by a fast algorithm based on the gray level, then the defect detection is applied on this part. Second, reducing the affection of the noise and making the defect more evident. A method to average several consecutive frames is used in the preprocessing part. Last, detecting the flaw. A more effective fuzzy theory that is based on the local image characteristics such as spatial contrast and spatial variance is used to determine the existence of a weld defect. The result shows success of the system in detecting weld defects.
Recognition of man-made target in smoke background
Xianjun Yue, Zeying Chi, Wenjian Chen
Many images to be processed are made up of man—made targets and natural background in many occasions, especially in military applications. Now that smoke can be regarded as natural object, in this paper, with the author applying fractal theory to target recognition in smoke background, a procedure is presented that can distinguish the man-made target from the smoke background. And some experimental results for real images show that the procedure in this paper is applicable.
Vision-based hybrid tracking scheme for accurate registration in AR system
Nowadays one of the key problems that influence the performance of an AR (Augmented Reality) system is the registration error. It is common that in the current AR systems a virtual object appears to swim about as the user moves, and often does not appear to rest at the same location when viewed from different directions. In order to provide a stable tracking result for our AR application, a hybrid tracking scheme that combines the robustness of the magnetic tracking and the static accuracy of the vision based tracking is developed. The principle of the vision-based tracking is presented and the tracking accuracy of the rotation angle is studied. A magnetic tracker composed of magnetoresistive sensors and accelerometers is proposed to compensate the shortcomings of the vision-based tracking. The algorithm to calculate the position and orientation of the tracked object by combining the calculation result of the magnetic tracking and the vision-based tracking is analyzed. The setup and the experimental results of the proposed AR system are given. The results validate the feasibility of the proposed AR system.
Photonic Device and Technology II
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Polymer optical fiber sensing
Gang-Ding Peng, Pak Lim Chu
Development of single-mode polymer optical fibres, polymer materials and polymer fibre Bragg gratings has provided new opportunities for optical communication and other related applications. In this paper we report on recent progress and development of polymer optical fibres and devices that would have a significant impact on fibre sensing applications. We also present some of our preliminary experimental work on polymer optical fibre sensing.
Photorefractive nanocrystalline silicon: materials, science, and application
Charles M. Fortmann, A. H. Mahan, Wayne A. Anderson, et al.
In recent years the prospect of engineering an integrated photonic technology based on amorphous siliconbased has focused efforts on providing a unified understanding of the optical properties of this material. From a optical properties prospective the science of amorphous silicon is most transparent from a nanocrystalline material framework. Of particular interest for photonic engineering is the tunable range of the refractive index in amorphous silicon, the fast and slow light induced changes in epsilon 1 and 2, the means by which to deposit films of sufficient thickness and smoothness for the photonic application and the relationships among deposition conditions, material properties, and in particular the optical parameters. The present work reviews some of the previous work and examines the experimental and theoretical basis for the fast light induced refractive index change with the hope of providing the insight needed for device engineering. This work suggests several novel designs for light amorphous silicon based light valves and other devices.
Modulated pattern in second-harmonic generation
Chunping Li, Ke Shen
Spatially modulated pattern in a second-harmonic generation planar resonator with a quadratically nonlinear medium and with the incident field at the fundamental frequency was studied. Through linear stability analysis and numerical simulations we obtain different patterns in focusing and defocusing case.
Ultrafast study of near-field hexagonal array illumination
Peng Xi, Changhe Zhou, Enwen Dai, et al.
Hexagonal array devices are widely used in optical communication and optical computing. Near field Talbot array illuminator is an ideal method for the illumination of these devices. Ultrafast pulse provides high transmission bit-rate and high peak energy, thus it is favorable for optical communication, diffractive optics, and other applications. In this paper we studied the hexagonal array Talbot effect under ultrafast pulse illumination. Ultrafast pulse has wide wavelength spectra range, and each spectral component corresponds to a unique wavelength that is directly relating to the Talbot distance. Thus the Talbot effect of hexagonal array is different from those of continuous wave in a whole. From the experimental result we can see that, comparing with that of the monochromic illumination, the efficiency and contrast of ultrafast pulse illumination are decreased. The result should be highly interesting for ultrafast fiber communication as well as other optical devices.
Photonic Device and Technology III
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Phase and amplitude modulation of a two-dimensional subwavelength diffractive optical element on artificial distributed-index medium
In this paper, we investigate the characteristics of the binary lamellar grating having the period smaller than the wavelength of the incident light and propose the structure of a novel binary subwavelength diffractive optical element (SWDOE). The effective medium theory and the birefringence multi-layer analysis method are used to analyze the proposed DOE structure. It is shown that the polarization sensitivity of the subwavelength scale lamellar grating can be used to design the SWDOE that can modulate both the phase and the amplitude of the incident light. In view of the synthesis of DOE, that is, the nonlinear optimization, the amplitude modulation means the extension of the degree of freedom for the design of DOE. So the relation between the phase and the amplitude modulation is derived through the numerical analysis.
Synchronized hyperchaos under drive response with applications to communication of semiconductor laser
Fengming Bai, Ke Shen
This paper investigated phenomenon of hyperchaos based on the semiconductor laser with the non-linearity dynamics, research synchronize of hyperchaos under drive-response. Make used of the semiconductor laser and their equations about take to adjust and design some of parameters. Last realize some aim of the optical communication. In this paper, it analyzed and investigated chaotic produce and chaotic modulation, further underline and point out, hyperchaos is an important physical phenomenon in the optical information processing technology. The chaos strange attractor, it has a property that is the most susceptivity toward initialization condition, and it is an important method for research secrecy communication. About study some regular and characteristic in the hyperchaos how to obtain synchronize at two or more systems. It is favorable to extend some fields of application in the optical communication and optic information processing.
Light quantum transmission in optical coupling
Jun Lu, Mucui Ni, Jing Zhang, et al.
This paper employing concepts of the quantum theory of photo-flow-line to analogize light coupling problem in I-D wave-guide as symmetrical potential well of refractive index. Getting the relationship among quantum of refractive index, potential well of refractive index and well width corresponding to photonic resonance phenomenon through calculation. Thus we study the problem of the efficiency of optical coupling.
Photon restricting effect in porous silocon luminescence
Jun Lu, Mucui Ni, Jing Zhang, et al.
In this paper, micro-column of porous silicon is analog as column "photonic potential well". By resolving light quantum mechanics equation, mode function of porous silicon luminecence is obtained, from which we can see it is the restricting effect of "photonic potential well" that makes the quantized oscillating mode output of porous silicon. The relationship between the mode and the dimension of "photonic potential well" is discussed, which can supply a law for designation and fabrication of porous sillicon.
Poster Session
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Optical neural networks based on wavelet transforms
Chunling Fan, Zhihua Jin, Weifeng Tian
The Fourier transform has been widely applied in the optical signal processing, yet it is just fit for analyzing the stationary signals. By extending the Fourier transform into wavelet transform, a new type of filter is proposed and its analogy to neural networks is developed. Optical neural networks (ONNs) are the new type networks, which possess good capacity of super parallel processing, signal transmission and high-density connecting lines. Although neural networks' implementations have been limited by the availability of high-resolution optical devices, by virtue of simple optical architectures for the wavelet transforms, the new neural network is easy to implement in large-scale by applying photoelectric technology. In this paper, the basic principles of ONNs and optical wavelet transform (OWT) are presented respectively, and the principle and structure of their combination—optical neural networks based on the wavelet transform are also proposed. For the optical neural networks and optical wavelet transforms, their optical implementations have many unique superiority, yet theirs combination takes on characteristics better than such structures just using neural networks or wavelet transform. Furthermore, their application perspectives are predicted in the paper.
Wavelet transform applied in the microdistance measurement of wavelength scanning Fabry-Perot interferometer
Chunling Fan, Zhihua Jin, Weifeng Tian
In this paper, the characteristics of wavelength scanning micro-displacement measurement signal is analyzed, and it is pointed out to be uncontinuous and unstable, so using Fourier transform to process must bring about error. Because of wavelet transform having good localization property in time-frequency domain and strong effects for the filtering of white noise and sharp pulse, it can overcome shortcomings of original signal's edge fuzzy caused by average filtering and median filtering. In this paper, wavelet transform is applied to process detected displacement signal in the wavelength scanning Fabry-Perot interferometer. Theory and test have shown that using this method is more accordant with reality of optical measurement and can eliminate noise. The measurement resolution and precision can be improved.
Multi-mother adaptive wavelet transform and its application in feature extraction
De Cai, Yingbai Yan, Guofan Jin
Adaptive wavelet transform, using an adaptive wavelet as a linear combination of different wavelets, has been applied in optical information processing successfully. Most of the adaptive wavelets are built by daughter wavelets from only one mother wavelet. In this paper, we construct a new adaptive wavelet for feature extraction under noise as prepossessing in face pattern recognition. To have the ability of de-noising, daughters for construction are generated by two different mother wavelets. We call this transform multi-mother adaptive wavelet transform. It is important that the new wavelet combines advantages of different mother wavelets. With artificial neural network, the parameters are adaptively computed. Simulation results show the wavelet is not only robust to noise, but also keep good recognition performance. In frequency domain, the spectrum of our wavelet is real and easy to be realized as an optical filter.
Approach to matching partial word image and its application to document image retrieval
Yue Lu, Chew Lim Tan, Lin Lin
An approach with the capability of matching partial word image is proposed in this paper, to facilitate the issues of document image retrieval, such as detection of user-speci ed query words, and similarity measurement between documents. Each word image is represented by a feature string. Then, an inexact string matching technology is utilized to measure the similarity between the two feature strings generated from two word images, based on which we can estimate how one word image is relevant to the other one and thereby decide whether one is a portion of the other word. The approach is applied to two issues in the area of document information retrieval: word spotting and document similarity measurement. Experimental results on real document images show that it is a promising approach.
Off-line signature verification with generated training samples
Bin Fang, C. H. Leung, Yuan Y. Tang
It is often difficult to obtain sufficient signature samples to train up a signature verification system. With insufficient training samples, the estimation of the statistical parameters such as the mean feature vector and covariance matrix becomes unreliable and system performance would be degraded. In this paper, a two-dimensional elastic matching method to generate additional samples is proposed to expand the limited training set so that a better estimate of the statistical variations can be obtained. The method differs from existing ones in that it is more suitable for the generation of signature samples. Besides this, a set of peripheral features, which is useful in describing both the internal and external structures of signatures, is employed to represent the signatures in the verification process. Results showed that verification system with the additional samples could reduce the error rate from 15.6% to 11.4%. It also outperformed another existing method which estimates the class covariance matrix through optimization techniques. Results also demonstrated that the peripheral features are useful for signature verification.
Ge-doped film process in waveguide application
Nick Singh, Sean Weng Kong Lee, Chris Hodson, et al.
Plasma Enhanced Chemical Vapour Deposition (PECVD) was used in the development of silica layers for use in planar waveguide applications. The addition of GeH4 to silica was used to control the refractive index of core layers with index differences core-clad in the range of 0.2%-1.3%. High rate SiO2 and Ge-doped SiO2 films have been deposited on to 4” Si <100> wafers. The ‘as deposited’ and ‘annealed’ film properties have been compared, including film uniformity, RI, RI uniformity and stress have been compared. Ge-doped SiO2 films up to 10 um thickness have been deposited and annealed for the above study. Refractive index uniformity of ± 0.0002 was achieved after annealing for 4” silicon wafers. The core layers were shown to be capable of producing optical losses of <0.1dB/cm when incorporated into a typical waveguide design.
Method of laser target echo signal identification
Dianren Chen, Huilin Jiang, Chao Zhou
This thesis introduced the identifying method of the laser target echo signal from the reflector which is used as the cooperate target and the optic modulator, build a mathematical model about the laser pulse coding and modulation, decoding and demodulation. Provied a demodulation method in frequency domain which do echo signal's FF1' with DSP high speed digital signal processor, this method can solve one frequency interference that cann't be eliminated in the time domain demodulation in the OOK system ,improve the system's detecting sensitivity and decrease the fault code rate, which was proved by theoretical analysis.
Binary Gabor zone plate generating special pattern
Jianping Ding, Meng Tang, Jin Zhou, et al.
We have proposed a novel principle for design of the binary GZP that can produce the desired pattern in the focal plane. The modified GZP can be fabricated as easily as the FZP. The proposed GZP has great flexibility in terms of manipulating the focusing properties. Optical experiments have confirmed the reliability of the GZP in focusing light into the specified area. The low cost and easy production of the element show that it can serve an alternative to refractive lens in the short wavelength region where refractive optics is not applicable owing to possible strong absorption.
Extraction of character of four-bacilliform target image in the objective measurement of MRTD
Wei Dong, Yuefeng Wang, Feng Huang, et al.
The objective measuring method of MRTD based on artificial neural network is using computer to judge the four bacilliform target image automatically and objectively replacing of human eyes' subjectively judgment. The characteristic vector of four bacilliform target image is extracted firstly before using computer to identify the image. The reasonable choosing of the characteristic vector not only affects the determination of the neural network, but also directly relates the identifying speed and accuracy (the judging efficiency of the neural network). The wavelet analysis of four bacilliform target image can well simulate the identifying procedure of the eye to four bacilliform target image. The experiment of identification of four bacilliform target image shows that using the total energy of the images of different frequency range as the characteristic vector is more suitable than using images average value, square-error, information entropy, etc.
Optical study of the fractional Fourier transforms for a regular fractal pattern
In this paper we have successfully applied optical diffraction method to the study of fractional Fourier transforms of a regular fractal pattern—a snowflake. Fractals may be divided into two kinds: the 1stkind is called regular fractal which may be generated artificially according to a set of mathematical rules and it exhibits strict self-similarity; while the 2nd kind is called irregular fractal in which strict self-similarity is replaced by statistical self-similarity. We have obtained fractional Fourier transforms of a snowflake by optical method as an example of regular fractal. Different orders of fractional Fourier transforms are obtained. These are compared with ordinary Fourier transform of the same pattern. These experimental results are discussed in the light of the fractional Fourier transform for pattern recognition. These results may be readily extended to the case of irregular fractals which closely correspond to most of natural patterns.
Improving the temperature resolution and response speed of distributed optical fiber temperature sensor with wavelet
Distributed optical fiber temperature sensor system can sense the temperature changes along the optical fiber by the continuous form of distance. For the characteristics of insulation and resistance to electromagnetic interference, it has a wide using prospect in the field of petroleum and gas pipeline, tunnel and mine. The distributed temperature measurement is realized by using single channel anti-Stokes light, and the temperature and space resolution of the system can be assured. But the anti-Stokes signal will be submerged by noise because of the weakness of anti-Stokes light signal, the loss of scattering light and the system noise. In order to reduce the influence of various noises in distributed temperature measurement, the method of increasing the times of signal accumulating is used to increase temperature resolution. But this will lengthen the period of temperature measurement and influence the practical application of the system. By using the multi-resolution analysis of Wavelet to handle the distributed temperature signal, we can shorten the period of temperature measurement and enhance the response speed of system on the basis of the assurance of time and space resolutions.
Real-time measurement of ping-pong ball velocity based on image processing
Tao Hu, Jing Yang, Zhaobang Pu
In this paper, we described a real-time measurement technique for analyzing flying ping-pong ball movement. A high picking rate CCD camera was selected, and the ping-pong ball was marked with two different colors. A fast algorithm which applied dynamic windows to determine the position of object was introduced. Through position-finding of mass center, measurement of the highest linear speed 40m/s can be obtained. Technique of FFT processes video images of marks on a ping-pang ball to get rotational speed. The highest rotatory speed of this measurement can reaches 200 r/s. The preliminary experimental results were obtained and its performance coincided with the theory. Relative error of this system was better than 5%.
Self-focusing difference frequency grating filter
Xianming Ji, Renwang Mu, Liangkai Han, et al.
A phase type optical image differential filter made by binary optical method is presented in this paper. It combines two phase type Ronchi gratings which have close frequency with off-axis phase-Fresnel-zone plate, called self-focusing differential frequency grating filter. It has several advantages such as high diffraction efficiency, simple optical path and convenient operation.
New approach to classification of surface defects in steel plate based on fuzzy neural networks
Kangsheng Lai, Haidong Zhang, Dongming Dai
An automated vision system is presented intending to detect and classify surface defects on steel strip. The framework of the system is briefly introduced and the realization, mainly focused on image processing and pattern classification, is discussed in detail. Original images of defects obtained from CCD camera are preprocessed firstly by using of DSP, which includes threshold segmentation, morphological operations, edge detection, and contour extraction. After several key features have been selected, they are inputted into fuzzy neural network functioned as classifier. The result shows that the fuzzy neural network classifier provides better classification accuracy and lower iteration times.
Parameter recognition of steel plate nondestructive testing based on fuzzy neural network
Haidong Zhang, Kangsheng Lai, Dongming Dai
An innovative neruofuzzy network is proposed herein for parameter recognition, specifically for steel plate's defects size inspection through different NDT sources data fusion. A neural network architecture is used to automatically deduce membership function based on a hybrid supervised learning scheme and a set of activation functions are used to adapt to different fuzzy states. The realization of this model and its characteristics are discussed in detail. The application of this model on the inspection of surface defect sizes shows that a quantitative method for determining the actual defect size is successfully developed to make full use of the measured defects sizes from different NDT sources.
Indirect-contact collection and identification of fingerprint images
The fingerprint (FP) provides an optimal foundation for Automatic Personal Identification Systems. In this paper, A new method of fingerprint collection that based on the improvability of images quality is proposed. The approach is mainly to enhance the accuracy of Automatic Fingerprint Identification Systems (AFIS) by indirect-contact collection. In a preliminary stage, The capture of fingerprint images is tested with an available contact approaches. Similarly captured clear images by using semiconductor capacitive sensor. And then, The integrited nondistortion fingerprint is indirect-contact collected by using a super-hemisphere-immerge lens and CCD camera with laser or incoherent light. It compares both of two collect methods on the basis of the experiments. The methods of fingerprint optical correlate identification and pattern recognition are discussed. The methods simply achieves on system.
Intelligent ground monitor system
Dongmei Liu, Junxin Shen
This paper presents a total project design and analysis of intelligent ground monitor system. This study uses the technology of computer digital images processing to realize dealing with the ground of open-air by intelligent monitor method.
New method for the measurement of aeroengine blade edge
Guodong Liu, Zhaobang Pu, Zuo Zhang, et al.
A new high accuracy method for blade edge measurement based on light-section principle is proposed. The section image is captured by CCD and processed by computer. The structure of the system and mathematic model are introduced, and the method for decreasing the influence of stray light is proposed. the algorithm of edge extracting based on direction estimating and the arc least square fitting methods are discussed, the experiment results are given at the end of the paper.
Particle shape recognition using digital holography
Qieni Lu, Yimo Zhang, Bao-Zhen Ge, et al.
3D object recognition is now an increasing interest in the optical information processing. In this paper, a method of 3D particle shape recognition by using in-line digital holography and optical correlation techniques is presented. The complex amplitude distribution generated by particle field at any plane located in the Fresnel diffraction region is recorded directly by CCD. The original field is then reconstructed numerically by wavelet transform. The scale parameter of the wavelet family, ? , is related to the distance between the particle hologram and the plane of observation. The whole information of particle field can be obtained by changing the value of ? .Holographic information of the 3D reference object can also be gained by the same method, and act as complex filter. Correlation techniques are then applied to recognizing the particle shape, and experimental results are also given.
Separation of translation and rotation information using fractional Fourier transformation
Lin Ma, Yingzong Wang, Haitao Dai, et al.
The Fractional Fourier transform (FRT) is shown to be of potential use in the Optical Information processing. The effects of displacement and inclination in space domain on the intensity distribution in fractional Fourier transformation domain are studied. It is shown that the translation and rotation information can be separated simultaneously by experiment. The experiment setup has been built based on the principle proposed in this paper. Experimental results demonstrate that this method is feasible.
Transmissive kinform fabricated using binary optical technique
Renwang Mu, Xianming Ji, Jianping Ding, et al.
The kinoform is attractive because of the high diffraction efficiency and the manner of on-axial reconstruction. In this work, we use the Gerchberg-Saxton iterative algorithms to optimize phase distribution of the kinoform. The phase in each pixel is then quantized into a set of eight-level values. The surface of quartz glass plate is etched to a depth determined by the corresponding phase retard, forming a kinform with stair-like surface relief. The optical experiments are canied out. The on-axial reconstruction image with high fidelity and high efficiency is obtained.
Error analysis and correcting 3D profilometry based on quadrature demodulation
Ting Su, Yong-Lin Zhang
In this paper, the errors of three-dimensioned profilometry based on quadrature demodulation are analyzed, and the corrected results are present. We found the method had three primary errors: the error that is caused by speckle of laser interference system, the error that is caused by mixing in quadrature demodulation and the error that is caused by the cosine fringe distortion in the structure light. We analyzed these three errors by experiment and theory. At last, we gave the corrected results.
New multiple-channel image plane holography realized by multiple reference beams
Xin Sun
Based on the multiplicity and redundancy of holographic recording and reconstruction, the paper presents a new kind of multi-channel image-plane holography, which used the method of multiple reference beams in one exposure to record and give the object' s information in different field angles simultaneously. The construction principle of dual-reference-beam multiple-image- plane recording with the diffraction wave theory is also presented. As an example, a dual-reference-beam image-plane hologram is given. Image plane holography was noted for its colorfulness and low dependence of reconstruction. But the view field of usual image hologram was largely limited. The accessible research in multiple channel holography can only reconstruct object's image in a fixed directional single channel, which limited the visual range and collected object's information in multiple channels at the same time. So it is very worthful.
Cancer cell recognition with hybrid optical neural network
Xiong Wan, Yiqing Gao, Shenglin Yu
In this paper, we consider a promising method of pattern recognition based on Texture Features (TF) to classify cancer cell. With this technique, the TF characters are calculated among different cells or different regions of cells. Then these texture features are transmitted to the input neurons of the Back Propagation (BP) neural network. After training phase of neural network, the structure is determined. At last, we design an opto-electronic neural network to complete the cancer cells recognition.
Software detection and capturing of pulse signal
Haiyan Wang, Yulong He, Dufang Shi, et al.
In allusion to measuring the wavelength of plus laser using the FabryPerot etalon, we put forward a concrete method to detect and capture the plus signal: Firstly basing on the gray characteristic of the sequential images captured real-timely by image card and the trait of the interferogram, select the average gray-value of given region of image as the characteristic value, then acquire the characteristic value of each frame to draw the statistical histogram, calculate threshold based upon the statistical histogram through selecting reasonable algorithm. Secondly write callback program of image processing on the basis of the development library provided with the image card together to complete parallel image processing, image capturing and image processing at the same time. Judging whether this frame contains the plus information that we wanted through comparing the characteristic value with the predefined threshold, decide whether or not to give out the command of stopping capturing and freezing image. The key of this method is correctly calculating the threshold and redeveloping the user program of image card to complete parallel image processing.
Improved real-time fingerprint verification by four-channel JTC
Hongxia Wang, Junfa He, Xuanke Zhao, et al.
In this paper the four-channel real-time joint transform correlator (JTC) for fingerprint verification is proposed which is consists of right-angle prism, 4f system, liquid crystal light valve, hololens array and CCD. Fingerprint image is inputted real-timely using a right-angle prism and processed by 4f system optically to insure the higher contrast. To avoid refusal phenomenon owing to fingerprint images distortion, the single channel correlation identification is changed to four-channel correlation recognition using hololens array. A little different reference fingerprint images from an identical finger are placed in different channels. When a object fingerprint image is inputted, four kinds of correlation results are presented. Not only the recognition accuracy is increased but the processing speed and capability of the system is enhanced. The experimental results are given in this paper.
Moving-object detection and recognition by using joint transform correlator
Wensheng Wang, Ye Zhang, Huiying Song, et al.
Optical image recognition is an important branch of optical information processing. It has extensive practical meaning and applied prospects. In recent years, joint transform correlator has taken place of matched filter, and pure optical experiments have developed into optoelectronic hybrid experiments. Optoelectronic Joint transform correlator has not only the optical advantages of parallel processing, large capacity and high speed, but also the advantages of computers, such as flexibility, programmability and accuracy. In this paper, electrically addressed liquid crystal displays (EALCD) are used as space light modulator (SLM), by the use of EALCD and CCD matrix camera which is controlled by microcomputer, and the optical Fourier transform (OFT) system, the moving object is detected and recognized. Because of using CCD matrix camera to detect the power spectrum of OFT, many kinds of digital processing algorithms can be adopted to improve signal noise ration (SNR), and to detect and recognize accurately moving objects.
Optical phase retrieval by lateral shear interferometer based on wavelet transform
Xiaojun Xu, Qisheng Lu, Zejin Liu
A new optical phase retrieval algorithm by lateral shear interferometer with wavelet transform is introduced. It can reconstruct the smooth wavefront faster than conventional polynomial fit. And to rough wavefront function, it also can do better. The computer simulation is also given.
Phase-compensated encoding of kinoform
Maotian Yang, Jianping Ding
A phase-compensated encoding method is proposed in this paper for the design of phase-only optical element (also called kinoform). The proposed elements are surface relief plates, i.e. , phase-only elements, which are based on the concept of computer-generated masks fabricated by common etching processes. The new encoding method can reduce the reconstructed errors such as quantization error through multi-level phase compensations. The number of subcells of every encoded cell is determined by the requirement of error reduction in actual implementation. Computer simulation confirms that the proposed encoding scheme can produce reconstruction with higher signal-to-noise ratio, higher diffractive efficiency and better uniformity than conventional encoding methods.
Multidimensional isotropic acousto-electro-optic effect
Kuanxin Yu, Shiya He, Baoseng Zhao, et al.
In this paper longitudinal electro-optic (EO) effect and multi-dimensional isotropic Raman-Nath acousto-optic (AO) effect in square system and cubic system are researched. KDP of the square system and GaP of the cubic system are chosen as crystals for multi-dimensional isotropic Acousto-electro-optic (AEO) devices. Through calculation of function characters of multi-dimensional isotropic AO interaction in the two crystals, optimum operating modes are determined for their two-dimensional (2-D), three-dimensional (3-D) and four-dimensional (4-D) isotropic AEO effect. The research results will lay the foundations for design and manufacture of the multi—dimensional isotropic AEO device.
Properties of degenerate four-wave mixing with Ce:KNSBN photorefractive fiberlike crystal
Hongli Liu, Zhaoqi Wang, Xinjun Yang, et al.
Properties of degenerate four-wave mixing in a Ce:KNSBN photorefractive fiber-like crystal under the conditions that the angle between the pump beam and the signal beam is smaller and bigger was studied. It is found that there are two interaction regions of degenerate four-wave mixing in the sample when the angle is bigger, and four-times enhancement of the maximum phase-conjugate reflectivity compared with that in smaller angle condition is obtained. The experimental results of the phase-conjugate reflectivity versus the intensity of signal beams, and versus the ratio of the pump beams are presented, which are numerically fitted by theoretical equations. They are coincident quite well. The property of the four-wave mixing gratings and the phase-conjugate response time of Ce:KNSBN photorefractive fiber-like crystal were studied. The response time could be faster, in an order of second in our experimental conditions.
PS optical interconnection realized by 2x2 holographic lens array with symmetrical focuses
Yi Liu, Shifan Wang
In this paper, 2X2 holographic lens array with symmetrical focuses was used for realizing PS optical interconnection. All cases with virtual focus, real focus imaging system and corresponding system after inserting imaging lens were carefully analyzed. The imaging distance and magnification are given, and the edge obscurity problem of PS imaging was analyzed, the object distance condition to gain clear image was obtained. The derivation and analysis indicated: The 2x2 holographic lens array with r = (1-1/2N)d/2 could not realize PS. After inserting imaging lens, the imaging distance and magnification of the system are closely in keeping with the position of focuses. In the case of real focus imaging fashion, when object distance ut=(1-1/2N)dfH/(2r), holographic lens array could gain clear PS images. The experiments proved correctness of the formulae.
Study on automatic detecting for straightness of the chamber of artillery body
Baoxing Bai, Hong Ma, Jingying Zhao
The automatic detecting system for straightness of artillery chamber takes advantage of computer real-time control to achieve the purpose of detecting in high precision and high efficiency. The system, combining the technology of computer, electronics, mechanics and photoelectric detection as well, has solved the key technical problem existed in the detecting and monitoring of the artillery manufacture system. The study has provided a new practical method for the automatic detecting of straightness.
Theory and Applications I
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Improved wave unwrapping algorithm based on the region growing theory
Rihong Zhu, Zhi Chao Wang, Xuxing Ding, et al.
Wave unwrapping is an important part of fringe analysis. However, the ultimate result of wave unwrapping is usually impaired by bad data and noise from the phase shifting procedure. This paper presents a robust improved algorithm of region growing, which combines the procedure both of error point seeking and of region growing and ultimately gains a perfect wave unwrapping result. The whole processing is illustrated with images and charts obtained by both the computer simulation and practical operation.