This PDF file contains the front matter associated with SPIE Proceedings Volume 6595, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

The history of the discovery of the physical principles of the quantum electronics and the early period of its development are discussed.

Optical fiber Bragg grating (FBG) has been appreciated as prominent high-durable local monitoring sensor and largely applied in structural health monitoring (SHM). However, it is still a big problem how to develop the feasible FBG-based sensors to fully meet the practical SHM for infrastructures. Many recent advances of FBG sensors for SHM in Harbin Institute of Technology, P.R. China are introduced in this paper, which include direct FBG-based sensors, indirect FBGbased sensors; FBG based smart structures, and the applications of FBG sensors in some typical civil infrastructures. Finally, some directions of researches and applications have been recommended. Researches and practical applications show that FBG sensors are becoming one of the key sensors in long-term SHM instead of some conventional electrical sensors.

The influence of energy-transfer up-conversion (ETU) on diode-end-pumped actively Q-switched Tm,Ho:YLF lasers is investigated by the rate equation analysis. The theoretical results show that the energy-transfer up-conversion reduces not only pulse energy but also effective upper level life. The practical example of the diode-end-pumped Q-switched Tm,Ho:YLF laser has been used to verify the present model.

In order to improve the performance of an optic system, a new evaluation and testing methodology for the light source which uses semiconductor laser is presented. A new system, combining high accuracy source and measure capabilities for pulsed testing, is developed to achieve the aim of automatic measurement of Light-Current-Power (LIV) for semiconductor laser. The test can provide customer with L-I, V-I curves and other correlative parameters, such as the threshold current and slope efficiency, and so on. Meanwhile, the change of environment temperature versus lasing wavelength under pulse injection is discussed, and the relationship between the lasing wavelength and the width and cycle of injection pulse is obtained. The temperature character of packaged laser unit is measured conveniently. Making use of the above examined curves and parameters, the reliability of semiconductor laser and quality of device can be compared directly and evaluated accurately. The technique is successfully applied for the evaluation of semiconductor laser reliability.

The influence of pump energy on the dynamics of Brillouin fiber-optical ring laser by the CW (continuous wave) DFB fiber laser was studied experimentally and theoretically. Using a 1Km-length single model 10 μm-diameter fiber in our experimental regime, half-periodic, serial identical Stokes pulses were found in the experiments when pump energy was low (less than 1.5 P_th ); then they became quarter-periodic or even smaller periodic with further increase of pump energy; until the periodic disappeared as pump power is great enough (more than 4P_th ), the output of Brillouin fiber-optical ring laser is tend to give continuous wave. At mean time, the duration of Stoke pulses became narrow gradually, and the peak power of Stoke pulses increased gradually with the increase of pump energy. Based on coupled wave equations of SBS process, using a seed of loons, theoretical simulation of temporal characteristics of pulses by SBS process in single model fiber has been given numerically and computationally. By computer modulation of dynamics of Brillouin fiber-optical ring laser by the CW (continuous wave) DFB fiber laser, the characteristic of periodic, pulse duration and peak power of Stoke were analyzed. Using both pump exhausts effect and multilevel SBS nonlinear process, we tried to explain some experimental phenomena.

In the article, theoretical model of transient thermal nonlinear refraction induced by nonlinear optical absorption is established. The simulation results of nanosecond Z-scan are shown in figures. The nonlinearities have own characters when experimental conditions change.

Optical limiting [OL] property of naphthalocyanine zinc [ZnNc] in DMSO solution was first studied with 30 Ps laser pulses at the wavelength of 532 nm. For comparison, OL measurement of C₆₀ was performed under the same experimental conditions. The results indicate that the optical limiting ability of ZnNc is similar to that of C₆₀. To investigate the mechanism of OL effect, Z-scan measurements were carried out with 30 ps laser pulses at the wavelength of 532 nm, the repetition of 2 Hz. The ZnNc solution sample displays strong reverse saturable absorption effect. The OL effect of ZnNc results from nonlinear absorption, and it can be considered as one of the most promising OL materials.

Based on Jones matrices theory, the paper researches the error source and action mechanism of the polarized interferometer in nanometer level measurement. It opens the door for selecting optical component, adjusting light set-up and compensating error. According to the theoretical analysis, the main reason that causes error is degeneration of polarization that the imperfect performance of optical components and imperfect adjusting bring. Especially the different delay angle happens more obviously. The characteristic of the passive homodyne laser interferometer based on the polarized phase-shift is that the output of interferometer is four-channel signals in quadrature. Using this characteristic, through strict selecting and fine adjusting components and differential signal processing, the interferometer can perform nanometer measurement.

A new approach to the problem of IFE laser driver based on generation and amplification of radiation with controllable coherence proposed and realized at P.N. Lebedev Physical Institute of the RAS had initiated the studies of an interaction efficiency of a partially coherent radiation with matter. Recent results of experiments carried out with the aim to study of the physical processes in targets under illumination by the laser with controllable coherence of radiation are presented and discussed, especially such important laser-matter interaction phenomena as absorption and scattering of laser radiation, the laser radiation harmonic generation, X-ray generation, crater formation and plasma expansion under laser pulse, conversion of laser radiation by means of nonlinear crystals, influence of coherence degree on the processes mentioned above.

One of the major challenges in realizing practical all-optical switching devices is the need for strong and fast material nonlinearity. The use of resonance-enhanced nonlinear effects in optical cavities has been explored as a promising way to lower the switching power. This paper provides numerically investigation of resonator-enhanced Mach-Zehnder interferometer all-optical switch by employing a nonlinear ratio-variable coupler with the merits of easy fabrication and excellent nonlinear optical controllability. This performs nonlinear optical switching with advantages of hundreds tW low switching threshold, steady switch ON/OFF states and a wide wavelength range by combining the high nonlinearity of ring and adjustable coupling ratio of RVC. Resonator finesse is controllable by incident power with potential applications in controllable photonic devices. Some undesirable effects involving attenuation, group delay and partial coherence lead to increase of switching power and low extinction ratio. Optical bistability and instability do not limit practical applications in optical switch. A desired tradeoff between response time and switching power can be achieved by controlling finesse. Picosecond ultrafast all-optical switch is predicted.

We have developed a procedure of manufacturing nonlinear elements from KDP and DKDP single crystals with aperture up to 320x320 mm. Such kind of nonlinear elements are need for the laser fusion facility to model experimentally D-T nuclear reaction. We have solved practically all problems for production large aperture elements.

In this paper the properties of phase conjugation of KNSBN:C crystal are studied. XOR and ANDlogic operation are accomplished with the erasable property of SPPC and the reversible property of ISPPC. The all-optical half-adder is realized by integrating them. For the first time to our knowledge they combined with the mutual reading property of MPPC to realize the all-optical full-adder.

Since each year all are more grown different synthetic crystal since crystals find the most broad using in science and technology. Obviously, as important efficient and fine methods of the study and analysis crystal, including optical. The interference pictures play in optical method of the study crystal important role. At imposition two coherent bunches of the light with alike polarization appears the interference picture - a spatial interleaving maximum and minimum intensive. If coherent bunch are polarized mutually perpendicular, that interference picture does not appear, but result to interferences is a light circular or elliptical polarized. For observation of the interferences in this case necessary polarization interference bunch by means of analyzer to bring about one direction. The optical scheme is offered for observation conoscopic figures of the unusual type. They are received interference pictures with light bunch, having small angular divergence in the manner of parallel stripes, rings, ellipses. Experimental is determined border corner, under which occurs transition from standard conoscopic figure to quotient case. The optical spottiness exist on background conoscopic figures. As object of the study used the crystals LiNbO₃, LiNbO₃:Fe (0,3 %), LiNbO₃:Ru (0,3%), LiNbO₃:Fe+Cu (0,3+0,01 %), LiNbO₃:Fe+Rh (0,3+0,01 %), LiJO₃, Ba_1-xSr_xNb₂,O₆, KDP. Thicknesses crystal lies within the range of from 0,5 mm before 23 mm.

Distribution and interaction of light impulses by duration in 2-3 femtosec. In a untuned nonlinear medium which is simulated by a population noninteracting is investigated singular classical oscillators. Asymptotic solutions of the equations circumscribing the response of an oscillator on action of such impulses are found. Stationary solutions of wave equations in an approximation of unidirectional distribution are analytically obtained.

The filamentary self-focusing and spot-splitting effects and dark band phenomenon are observed during the propagation of double-circle laser beam in Kerr-medium of CS₂. With solving nonlinear Schrodinger equation numerically, the effects of self-focusing and spot-splitting are observed when the input laser beam's power density over 98kw/cm², which is much lower than the single-circle spot laser beam's threshold of self-focusing and spot-splitting, and the split pulses can undergo additional splitting. The filamentary self-focusing is observed in propagation process as the input laser beam's power density over 135kw/cm² as the propagation length over 65cm and it is closely connected with the spatial splitting. The external and the internal circle's propagation characteristics on intensity, radius and focus are contrasted.

In order to achieve the highest peak power of radiation pulse and highest output energy, the primary circuit parameters are investigated to optimize the discharge circuit performance of the laser. The structure and the discharge circuit of the laser are discussed at first. To realize synchronous discharge in two discharge channels, the conjunct electrode device for two pairs of discharge electrodes is designed. Finally, the results of the experiments on the primary circuit parameters are given. The discharge is most stable at a pressure of 5.33×10⁴Pa when the pressure of gaseous mixture CO₂:N₂:He=1:1:3 is changed from 2.67×10⁴ Pa to 6.67×10⁴ Pa. The ratio of storage capacitance to peak capacitance is chosen to be about 1.5-7/3, because residual voltage is lower on this condition and residual voltage is adverse to discharge. When the inductance 330&mgr;H is used, the homogeneous glow discharge in a widest voltage range is obtained. The duration of when the stimuli voltage is increased in homogeneous glow discharge condition. The discharge circuit allows charge and discharge and the magnitude of residual voltage decrease the homogeneous glow discharge in a wide range of pressure of gaseous mixture when these circuit parameters are used. Thus it offers reference to the improvement of output characteristic of TEA CO₂ laser with two discharge channels.

A novel all-fiber self-organization Michelson coherent Erbium-doped fiber laser (MCEDFL) has been proposed and demonstrated. The laser system is composed of two independent branch lasers. The two arms of the active interferometer are spliced to a 3dB 2×2 coupler. A fiber Bragg Grating (FBG) with 95% reflectivity is spliced to one port of the coupler. It acts as wavelength selective filter and common reflection mirror to make the two branch arms emit laser with the same wavelength, which can conform to the coherent constraint exactly. The high reflection mirror of each laser cavity is composed of a 3dB fiber loop mirror (FLM). The other output port of the coupler is spliced to an isolator that acts as the MCEDFL's output port. Any feedback from this port into the MCEDFL is prevented by the isolator. When each of the two lasers is pumped to 100mW independently, the output power is 12.1mW and 16.2mW respectively. By adjusting the polarization controller (PC), the two lasers attain coherent coupling, the output power is 34.5mW, which is more than two times the output power of any single laser. Furthermore, we bring forward and discuss a novel factor to denote the effect of coherent combination—coherent coupling factor. Herein the value of coherent factor is 1.12. The advantages of the coherent fiber, such as simple structure, high efficiency and single frequency etc, can make coherent coupling easier.

For a dielectric exposure to the femtosecond hyperbolic secant pulse, the electron dominated by collisional and multiphoton ionization has been studied. Analytical description of the temporal evolution of the electron density induced by the optical pulse has been given. As the result, at the damage threshold an explicit expression of the pulse width in terms of the pulse fluence has been derived.

The two-temperature model has been widely used to predict the electron and phonon temperature distributions in ultra-short laser processing of metals. This paper extends the use of existing two-temperature model to high electron temperatures by using full-run quantum treatments, including the electron heat capacity, electron relaxation time and electron conductivity . A dual-hyperbolic two temperature model is solved numerically using an accurate and stabile forward-difference scheme, in which one kind of artificial viscosities and adaptive time steps method are introduced. This model predicts the damage thresholds more accurately compared with published experimental results.

We present a new experiment system to improve the original 4f coherent imaging system developed by Georges Boudebs et al. In the new experiment system we take off the monitor branch, add another 4f system before the main 4f system and place one more CCD camera after the first 4f system. Our new experiment system has five advantages: firstly, the old system needs three steps to measure the nonlinear refraction index of the nonlinear sample, however the new system only needs two steps. Secondly, in the developed system the CCD camera after the first 4f system can monitor the energy fluctuation as well as the intensity distribution of the input laser pulse, while the original system can only monitor the energy fluctuation. Thirdly, the new system realizes the real single-pulse measurement, and can avoid the energy instability completely. Fourthly, in the new system we can detach the diaphragm and the phase object, so they can adjust separately. Lastly, the added 4f system can be used as a spatial filter. The shortcomings of our improved system are that the experiment system becomes a little more complex and the additional CCD camera adds the experiment expenditure.

Pulses of longitudinal, shear and surface waves are generated when a powerful laser pulse interacts with a surface of a solid. These waves serve to control strength, structure, and dynamic modulus of elasticity of solids. They are also used for ultrasonic testing.The optical methods and means have been developed in Dalstandart, RSRI of PTM, for generation and reception of ultrasonic waves in the frequency range of 0-30 MHz. Efficient techniques have been devised to determine different parameters of ultrasonic wave propagation, such as propagation velocities, coefficients of sound attenuation, and acoustic dispersion. Based on theoretical and experimental background the devised installations offer the highest accuracy for measurement of parameters of ultrasonic wave propagation in solids.

In this paper, the nematic liquid crystal 5CB doped with 1wt% Methyl-Red was prepared. Due to optical excitation, cis-trans isomerous effect of Methyl-Red depended on the polarization direction of the incident light, so we chose Ar⁺ laser as grating recording lights. When the sample thickness is 32&mgr;m, the angle between two incident beams is 2°, the two incident beams with the equal intensity is 85mW/cm², ambient temperature is 22°C, and He-Ne laser with polarization direction normal to the dirction of grating wave vector as read-out light, the first order diffraction efficiencies of two-wave coupling were measured. The hologram images were storage and reconstruction in the samples. The theoretical analysis is given to the experimental results.

It is well known, that for large Rabi frequencies the spectrum of resonance fluorescence of a single two-level atom contains three separate lines (Mollow triplet). Question naturally arise as to what effect sidebands of this triplet might have on the spectrum of the scattered radiation in the multiatom case. The purpose of the present paper, therefore, is to obtain a space-frequency dependent spectrum of the scattered radiation in backward direction (reflection) by a system of N noninteracting atoms. We neglect the translational motion of the atoms and multiple scattering and concentrate on the effects of the collective scattering. It is shown that spectral energy of the scattered radiation consists of two different parts. One is the incoherent and isotropic emission of fluorescence. The energy of radiation in this case is the sum of the atomic energies and then is proportional to N . The other is the collective emission (interference effect). The energy of radiation in this case is spatially focused in a small solid angles about three propagation directions and then is proportional to N². Thus the frequency Mollow triplet is transformed into the space-frequency dependent triplet.

Lithium niobate single crystal has been found to be a versatile material in the field of nonlinear devices due to its excellent electric-optical, dielectric and nonlinear optical properties. When LiNbO₃ device serves as holographic storage media, it is often required a big dynamic range, a big sensitivity and a high photo-damage resistance ability. Although Fe-doped LiNb0₃ in holographic storage is one the most widely investigated crystals and takes on better comprehensive merits, its performance is severely limited by the low photo-damage resistance ability when LiNbO₃ is operated on high laser intensity. Indium is one of the beneficial impurity ions for suppressing photo damage. In this paper, we grown a series of Fe:In:LiNb0₃ crystals with a varying content of In doping by Czochraski technique. On the basis of the ultraviolet-visible absorption spectra measurement and two-wave coupling experiment, the effect of In ions on photorefractive properties is explored and discussed systematically. It is found that the photorefractive properties can be greatly enhanced by In doping in Fe:LiNb0₃. Among the four samples of Fe:In:LiNbO₃ crystals, the Fe:In(2 mol%):LiNbO₃ crystal has the highest photorefractive sensitivity and the largest dynamic range (1.79 cmJ^-1 and 2.10, respectively) and can resist higher intensity laser irradiation. Our analysis indicates that increased photoconductivity is mainly responsible for the excellent photorefractive comprehensive properties. It is believed by the experimental results that Fe:In(2 mol%):LiNbO₃ crystal is a promising holographic storage medium.

Two-dimension photonic crystals coupler is studied in present paper. The photonic band gap structure and band gap map are calculated on the basis of plane wave expansion method. The finite-difference time-domain (FDTD) method is applied for analyzing transmission and coupling characteristic of photonic crystals coupler with the square lattice. The effects of coupling length and waveguide-channel space on coupling ratio are discussed. Further, the field distribution is given in this paper. The results indicate that photonic crystal can accomplish coupler function. The performance of the coupler is more sensitive to coupling length than waveguide-channel space. The phenomenon between coupler branches will disappear gradually when the waveguide-channel space increases. In terms of appropriate coupling length and waveguide-channel space, the coupler with any coupling ratio can be achieved.

Experiments on femtosecond laser micromachining of grooves in spring steel (65Mn) were performed with Ti:Sapphire laser pulses of 5Ofs duration. The relationships between the dimensions of the grooves and the cutting parameters were analyzed. A logarithmic dependence of the groove depth on laser fluence was observed with two regimes characterized by different ablation rates and different thresholds. The groove depth was found to be inversely proportional to cutting speed and proportional to the number of passes. A depth limit was found with decreasing cutting speed or increasing number of passes. Cutting speed and the numbers of passes have little effect on the width of grooves. The morphological of period surface structures and unevenness depth was observed using scanning electron microscope. The result in the paper provides instructive guide for future research on three-dimension microstructures.

New methods of forming azimuthally and radially polarized Bessel light beams using a one-dimensional photonic crystal having photorefractive properties are proposed and elaborated. These light fields are promising for photolithography, confocal microscopy, and optical communications. The methods are based on the splitting of a polarized Bessel beam, which propagates in a one-dimensional photonic crystal, into two beams having the mutually orthogonal polarizations.

Nonlinear absorptive property of a novel metal cluster cis-Cp*₂Mo₂S₄Cu₂I₂•(CH₂Cl₂)₂ in CH₂Cl₂ solution is studied by using an open-aperture Z-scan technique with laser pulse of 8ns pulse-width at the wavelength of 532nm .The experimental results shows that the cluster has strong nonlinear absorption under the 8ns pulse excitation. A picosecond time resolved pump-probe experiments at 532nm has been used to study the nonlinear origin of the cluster. The pump-probe response of the metal cluster is similar to that of C₆₀ solution, which implies that the nonlinear mechanisms are the same of the two materials. By establishing a five-level model for the cluster, several nonlinear optical parameters, such as the relaxation time of the excited singlet state, the absorption cross sections of the excited state of the cluster arc obtained. According to the results of the experiments and numerical simulations, a conclusion can be obtained that, at 532nm , the effective absorption of the triplet state of the cluster solution is the dominant mechanism causing the reverse saturable absorption. The theoretical results are in good agreement with the experimental data, which not only shows the availability of the kinetic model but also demonstrates the close relationship between the nonlinear absorptive property of the cluster and its dynamic processes.

The carrier traps and process of charge trapping play a vital role of the Photorefractive effect (PR-effect), yet no systematic attempt has been made to understand them in photorefractive polymers, In this paper, the measurement of thermally stimulated current (TSC) spectrum and the analysis of it were completed in polyvinylcarbazole (PVK). The trap states in PVK were characterized by the TSC spectrum, Some parameters, Such as depth, density and distribution of traps were obtained, The result showed that there were 0.53∼1.0eV continuous distribution traps in PVK, and the distribution was similar to Gauss law with a 0.77eV maximum. These data can provide a reference to the deeper investigations of nature and mechanism for photorefractive polymers based on PVK.

By all-optical poling of a medium the long-lived space-periodic electrostatic field arises inside the sample and, as a result of such photoinduction, an isotropic medium gains the properties of an inhomogeneous optical single-axis crystal with the existence of the periodic &pchi;⁽²⁾nonlinearity. In this paper the results of the investigation of the temperature influence on the all-optical poling process and on the kinetics of the formation of induced gratings &pchi;⁽²⁾in optical multi-compound phosphate glasses are presented. The experimental investigatation of the all-optical poling process during the smooth variation or the step changing of the temperature of studied samples demonstrates the anomalous behavior of the process of the formation of the &pchi;⁽²⁾ nonlinearity in medium and shows the existance of the region of the critical temperature in which the sharp change of the kinetics of the all-optical poling process takes place. The study of the kinetics of the anisotropy in near critical region shows the possibility of the increase of the efficiency of all-optical poling in glass media by means of the high-temperature influence.

We investigate holographic image storage and reconstruction in the planar Disperse Red 1 (DR1)-doped liquid-crystal films. The nematic liquid crystal 5CB cells doped with Disperse Red 1 (DR1) 1%, 2%, 3%, 4% and 5% by weight are presented. And there is no an electronic field applied to the films. The diffraction efficiency of the probe beam increases with the increase of the dye concentration. The absorptivity of the liquid crystal cell as a function of the angle between the light polarization direction and the liquid-crystal molecular director axis for five different DR1 concentrations is measured at the wavelength of 488nm. We find that the +1st-order and the -1st-order reconstructed images are in centrosymmetric pattern, i.e. they are inverted, and images with readout image quality can be reconstructed from transient hologram recorded in this medium with very short response time of ~10ms. These experimental results show that this medium can be used in optical reconstruction, holographic image reversion or holographic image display.

The gel-colloidal dichromated gelatin emulsions properties doped by different multyatoms spirits are investigated. The highest diffraction efficiency results turn out at use isopropanol spirit (IPS) for dichromated gelatin (DG) gel. Influence of the IPS on holographic properties of such layers is investigated. Optimum IPS concentration depends on gelatin concentration and makes 5 vol % for 3 % gelatin water emulsion and 10 vol % for 10 % gelatin one. Optimum IPS concentration is approximately 100 % on dry gelatin weight. DG gel with IPS photoreaction speed is increased in 5-6 times in comparison with a layer without spirit and done approximately identical to layers with glycerin.

Results of experimental investigations of temperature dependences of optical absorption coefficients and their light-induced changes for Bi₁₂SiO₂₀, Bi₁₂TiO₂₀:Zn, and Bi₁₂TiO₂:Ca crystals are presented. Semiconductor light diodes emitting quasimonochromatic radiation in red (625 nm), yellow (570 nm), green (505 and 515 nm), and blue (470 nm) ranges of the spectrum were used as light sources. A theoretical model of thermal- and light-induced changes in the optical absorption is considered that describes well the observed temperature dependences of the optical absorption for the Bi₁₂SiO₂₀ and Bi₁₂TiO₂₀:Ca crystals and the dynamics of light-induced changes in light absorption for the Bi₁₂TiO₂:Ca crystal at a wavelength of 470 nm and temperatures in the interval from 24 to 100°C.

Nonideal heterojunction of AgBr-AgI has been considered. The Poisson equations for heterojunction in planar, spherical and cylindrical geometries have been solved in linear approximation. The expressions for band bending of heterojunctions are derived. Calculations of band bending vs. the size, forms of the core and the surface charge on the interface have been carried out.

In this paper, we have proposed a new type of DIRIM with suspended membrane resistor (SMR) structure, while mainly focusing on its implementation technology which includes selection of resistance material and fabrication technique of the membrane; design of Read-In-Integrated-Circuit; and implementation of silica-base MEMS process. Some performance parameters of the device are quoted to conclude the advantages of this new type of DIRIM and make an outlook on the key development in the future.

The electro-mechanical properties of epoxy resin(EP)/polyimide(PI) composites containing conductive and sprayed carbon black(CB), respectively, are experimentally studied. The test results indicate that the value of the fractional change in electric resistance of the EP/PI composites containing conductive GB is too small ,and the electro-mechanical properties of the EP/PI composites containing sprayed GB under cyclic load is not good enough. However, the EP/PI composites containing the mixture of sprayed GB and conductive GB behave good electro-mechanical properties and this kind of conductive films can be used as monitoring material after they are trained through cyclic load.

The theory of atomic motion in resonant radiation in the vicinity of the material surface has attracted considerable attention in recent years because of the possibility of applying the theory to different problems of micro- and nanophysics. In the present paper the influence of the thermal field on the atomic motion near the surface of dielectric matter is analyzed. Thermal field due to fluctuations of charge in matter, exist not only inside every dissipative matter but externally including standing waves and plane running waves. We derive expressions for the corresponding forces F₁ and F₂ and discuss their. If the distance z between the atom and surface is large ( kz >> 1 ) the force F₂ which is independent from z is substantial. This force is directed opposite to atomic velocity. The spectral density of the F₁ is proportional to the gradient of spectral density of thermal energy which is proportional (at z → 0 ) to z^-3 . Therefore if the distance z is small ( kz << 1 ) the force F₁ can be quite substantial. If the atomic frequency lie in the visible or infrared areas of spectrum the forces F₁ and F₂ tends to reflect the atom from the dielectric surface.

Microring resonator-coupled Mach-Zehnder interferometer (MRCMZI) is attractive for its applications in the field of all-optical switch, with low threshold, fast response speed and compact scale suitable for integration. The paper provides analytically and numerically investigation on optical pulse transmission characteristics of MRCMZI. The analytical formulations of dynamic process are derived in an easy-understood method of light beam tracing. These formulations can degenerate gradually to steady-state response when incident pulse becomes quasi-continuous wave (CW) or adequately broad with duration much more than cavity lifetime. For the coupled-microresonator system, several interesting signal processing tasks, such as optical differentiation, integration, pulse compression and trigger pulse generation, can be realized. Because of the complementarity between two output ports of MZI, the optical pulse differentiation and integration operations can be carried out synchronously at two output ports through optical interference between the reference light of direct-bus and the modulated light of coupled-microresonator bus. The interesting functions related to optical pulse shaping have potential applications in future all-optical communication.

Mastering of the middle IR range is attractive for many applications, such as lidar gas analyzers, optoelectronic countermeasures for suppression of IR detecting, optical communication systems, and scientific and medical instrument. However, until now this has been held back by the lack of commercial coherent radiation sources with necessary energy parameters and efficiency. AgGa_1-xIn_xSe₂ and Hg_1-xCd_xGa₂S₄ are well-known middle IR crystal families introduced in recent years. The main advantage of them is that their physical properties including refractive indices and birefringence can be engineered by varying the contents of Ga, In, Cd and Hg. Consequently, the phase matching range can be extended and the 90° non-critical phase matching in three-wave interaction can be realized within a certain wavelength band. In consideration of influence of composition ratio, acceptable composition ratio and group velocity mismatch of ultra-short pulses on nonlinear properties of AgGa_1-xIn_xSe₂ and Hg_1-xCd_xGa₂S₄ are investigated for the first time. The corresponding phase-matching diagrams and spectral dependence of the acceptable composition ratio on wavelengths for second harmonic generation and optical parametric oscillation pumped by the popular Nd³⁺:YAG (1.06 &mgr;m) and Ho³⁺:ILF (2.08 &mgr;m) lasers are estimated and demonstrated with accounting of available Sellmeier coefficients. Group velocity matching for second harmonic, optical parametric generation under the pump of the two lasers in AgGa_1-xIn_xSe₂ and Hg_1-xCd_xGa₂S₄ are carried out as well. All relative results are compared and analyzed within a number of sampling values or continuum of composition ratios. In addition, the utilities of AgGa_1-xIn_xSe₂ and Hg_1-xCd_xGa₂S₄ for second harmonic generation are also discussed finally.

Symmetric air waveguide and antisymmetric air waveguide made with left-handed material (LHM) cladding are constructed. Guided modes in the two kinds of air waveguides are studied on condition that the permittivity and permeability of LHM are simultaneously negative. When absolute value of refraction of cladding is less than that of air, fast modes and slow modes are possible to exist at the same time; when absolute value of refraction of cladding is more than that of air, only slow modes could exist.

The optical limiting (OL) properties of the novel cluster cis-Cp*₂Mo₂S₄Cu₂(SCN)₂ in CH₂Cl₂ solution are studied by using nanosecond duration laser pulsed at 532 nm wavelength. The OL effect of this cluster can be observed with a linear transmittance of 75%. The limiting threshold can be derived from the OL experimental results. In order to provide direct evidence on the physical origin of the observed OL effects, the nonlinear effects for this cluster in CH₂Cl₂ solution have also been investigated by time-resolved pump-probe experiments. The pump-probe experimental results of this cluster are compared with that of C₆₀, which is measured by using the same experimental setup. And it reveals that the nanosecond OL effect may be due to the reverse saturable absorption (RSA), which is related to the excited triplet states. A theoretical model of the five-level system is presented to analyze the pump-probe results.

A passively Q-switched pulse-LDA(laser-diode-array)-pumped Nd:YVO4 laser using As⁺ion-implanted GaAs as a saturable absorber is demonstrated. In the Q-switching experiment, the laser produces one Q-switching pulse in every pumping pulse duration and a Q-switching pulse width 7 ns is achieved. When the pumping power is increased a Q-switched mode-locked laser is achieved. Using a 60% initial transmission GaAs wafer, the modulation depth of larger than 95% is obtained. The repetition rate of the mode-locked pulses in the Q-switched envelope is 991MHz. The effects of the pumping pulse energy, pumping pulse width and repetition rate on the characteristics of the Q-switched mode-locked pulses are also investigated respectively. The experimental results are discussed as well in the paper.

Solid heterogeneous photocatalytic system consisting of polyvinyl alcohol (PVA), ZnO and BiCl₃ exhibits photosensitivity to UV light. Under irradiation the change of composition surface color occurs. In other words, direct blackening is produced by this way. Such material differs from similar systems by relatively high photosensitivity, simplicity and image stability. Therefore PVA-ZnO-BiCl₃ composition can be regarded as a prospective material for the optical information recording and irradiation detecting. Some photostimulated processes which lead to direct blackening involve all components of composition. For the improvement of photosensitive characteristics (maximal density of blackening, sensitivity and so on) and production of a materials with predictable properties it is necessary to investigate which namely processes occur in this system under irradiation. Have a sequence of the processes known it is possible also to make a conclusion about underlying mechanism of photographic effect. To solve this problem it is necessarily first of all to determine which compounds are produced in photosensitive composition under irradiation.

In this letter, we put forward a new kind of polarization-maintaining index-guiding photonic crystal fiber (PM-IG-PCF). It is made up of a solid silica core, two big circular air holes near the core and a cladding with elliptical air holes. By making use of a full-vector finite-element method (FEM), we study the modal birefringence and polarization mode dispersion (PMD) as a function of the normalized wavelength of fundamental modes in the PM-IG-PCF we proposed. Numerical results show that very high modal birefringence with magnitude of order of 10^-3 has been obtained, which is higher than the birefringence induced by adding two big air holes near the core or elliptical air holes in cladding separately. Furthermore, the chromatic dispersion curves of the two orthogonal polarizations for the birefringence PCF are presented as a function of the normalized wavelength.

Built on the maser oscillator power amplifier configuration including a single mode erbium-doped fiber laser used as the signal source and a large-mode-area Erbium/Ytterbium double-clad fiber used as the gain medium, the polarization states of the signal light and the amplified signal light are experimentally investigated. The results show that the polarization degree of the output of the amplifier is low without taking any polarization control measure; after inserting a polarizer in the loop of the signal source, the degree of polarization is improved evidently and the stability of the polarization state becomes better, whether for continuous wave operation or for mode-locked operation. The mode-locked operation had a little lower polarization degree and a better PS's stability than the continuous wave operation of the output of the amplifier. When introducing a polarizer in the loop of the signal, the instability of the polarization state of the output of amplifier is mainly caused by the polarization parameter azimuth. So, the combination use of a polarizer and a polarization controller is supposed to improve the polarization degree and the stability of the output of the amplifier, furthermore, polarization-maintaining gain fiber is recommended to be used to avoid the random perturbation of the environment. This work offers an important experimental basis for the control of the PS in the laser beam coherent combination.

In this paper, the Goos-Hänchen shift on the interface between one regular isotropic medium and another anistotropic LHM is analyzed extensively. The analytical expression of Goos-Hänchen shift on the uniaxially anisotropic LHM is derived for the configuration where the optical axis of the LHM is perpendicular and parallel to the interface of two media, respectively. Meanwhile, the expression of Goos-Hänchen shift on the surface of biaxially anisotropic LHM is also presented. The result shows that the Goos-Hänchen shift on the surface of the anisotropic LHM is significantly different from that of isotropic LHM. And under certain conditions, anomalous Goos-Hänchen shift shall occur, i.e., the Goos-Hänchen shift is negative on the surface of the anisotropic LHM. The constraints for the existence of anomalous Goos-Hänchen shift in anisotropic LHMs are identified, respectively.

It was earlier discovered that oxide layers conditioned with polymers and metal salts could be used as photographic materials producing a pronounced direct blackening when exposed to UV-light. In this paper the UV-induced blackening process in such layers is investigated and the mechanism of the underlying process is discussed. The possibility of a layer modification is examined. The aim of such modification is to obtain a group of photosensitive materials with properties that can be adjusted to the different application requirements. The application of the layers as sensors in form of disposable UV-sensitive labels is discussed.

Phase diverse speckle (PDS) is a novel imaging technique, can be used to overcome image degradation arising from unknown phase aberrations, such as atmospheric turbulence. The wave-front phase expanded on the Zernike polynomials is estimated from a pair of images (in focus and out of focus). This paper analyses the principle of PDS, uses genetic algorithm as the iterative algorithm, verifies its validation with numerical and experimental data, and studies some characteristics in simulation, such as the influence of Zernike polynomials' mode, defocusing amount and amplitude of turbulence on the phase estimation.

This paper proposes a new motion estimation method based on the adaptive break successive elimination algorithm and multi-resolution in a digital image stabilization (DIS) system. A computational scheme that facilitates the estimation of the local motion vectors is developed. First, the images are transferred to layers with different resolutions by the linear or wavelet transition and the performances of the translations are compared in the later experiments. With multi-resolution, the size of the sub-image and the search area were broadened and little moving objects can be eliminated. Then, positions which were calculated with lower possibility to be the destination by successive elimination algorithm were removed before they are matched. Finally, also with the adoption of the principle of adaptive break, the threshold which decides the times of a block matching is set adaptively according to the errors during the match while the accuracy remaines. Experimental results show that with similar performance as that of TSS, the computational load of the proposed motion estimation algorithm is 3% of the full-search matching and 34% of TSS..

The scheme of recording of reflective volume Fourier holograms in monochromatic light with partial spatial coherence is presented. The scheme contains posed on one optical axis an illuminated or self-luminous object, Fourier-objective, photosensitive medium and concave mirror. The light is proposed to be monochromatic with partial spatial coherence. The object is located in a front focal plane of the Fourier-objective. Photosensitive medium is placed in a back focal plane of the Fourier-objective, and the mirror is posed on a double focal length of the mirror from photosensitive medium. The light from input object is focused by the Fourier-objective in a volume of photosensitive medium, shaping a far field diffraction pattern of input object. This pattern is partial coherent analog of Fourier transform of input object. The light transmitted through the medium falls on the concave mirror and is reflected back, thus the mirror shapes the second copy of far field diffraction pattern of input object in the volume of photosensitive medium. Thus, these two light waves, propagating in the opposite directions, form the interference pattern in photosensitive medium, and a reflective volume Fourier hologram is recorded by monochromatic light with partial spatial coherence. The experiments on recording of these holograms and image reconstruction were realized. Patent by Russian Federation No2176099 on the device of recording of reflective volume holographic Fourier-filter in light with partial spatial coherence was taken out. Described reflective volume Fourier-holograms can be used in optical correlators as the spatial filters and spectral selectors at image recognition both in monochromatic and polychromatic light.

In this study we measured the variation of brain blood quantity (Oxy-Hb, Deoxy-Hb and Total-Hb) in the temporal lobes using near infrared spectroscopy (NIRS) when the tasks of the memories were presented to the subjects. The memories are classified into the short-term memory (STM) and the long-term memory (LTM) including the episodic and semantic memories. The subjects joined in this study are 11 persons who are university students including graduate students. We used the language task of letter-number sequencing, also reverse sequencing to measure STM and the task of the episodic memory to measure LTM. As a result of analysis, concerning the episodic memory, the variation of Oxy-Hb in the left temporal lobe was larger than that of Oxy-Hb in the right temporal lobe. The result might suggest that the episodic memory has a relationship with cerebral dominance concerning language area in the left temporal lobe. It seems that the episodic memory meditated with the function of language used in this study is much stored in the left temporal lobe than in the right temporal lobe. This result coincides with the principles of lateralization. The variation of Oxy-Hb in the language task of letter-number sequencing was smaller than that of Oxy-Hb in the language task of the episodic memory.

Dim object detection is the key technology to space objects surveillance. The space detection data model (SDDM) and space dim moving object detection algorithm (SDMODA) are investigated systematically in this paper. SDDM is set up, which consists of the circuit Gaussian noise, dark current Poisson noise, background light Poisson noise, non-moving objects noise and moving object signal sub-model. By digital simulation, time sequence image data of each CCD pixel is built to input SDMODA as raw data. SDMODA computes maximum value projection, pixel average and pixel standard deviation in each CCD pixel of every time sequence data. By subtracting pixel average from maximum value projection and then divided by pixel standard deviation in each pixel, SDMODA produces a new standard frame. The standard frame is processed to find candidate object streaks by threshold filter, which can eliminate non-moving objects and suppress the circuit Gaussian noise, dark current Poisson noise and background light Poisson noise. Since the invariability of object streak in streak angle and streak length, SDMODA can eliminate false streaks and find true object streak. By simulation experiment, SDDM can produce time sequence data with different signal-to-noise ratio and SDMODA can detect object streak with signal-to-noise ratio of 3.5dB.

In this paper, two important subjects are dilated. One is trying to explan by simple model how NO production is suppressed in "High Temperature Air Combustion", and another is the method of flame detection which made by diluted fuel and air, dimished in visibility and buried in background radiation. To estimate NO production, the mixing process of fuel and air and combustion gas in a combustion furnace having air and fuel ports separately is analyzed, in particular without solving detailed conservation equations of flow, energy and momentum and full chemical kinetics. The author suggests even the extremely simple model how validation of intuition is possible to predict and evaluate combustion efficiency and the NO production, using the some parameters for mixing and chemical reaction. Then the experimental data provided by a proof examination of high temperature air combustion can be evaluated with this estimation by satisfactory precision. Adding this, this may reports about new combustion diagnostics using optical device that detects ultraviolet emission.

Laser forming is a technique of using the energy from a laser beam to modify and adjust the curvature of sheet metals or hard materials. 2-dimensional laser forming can reasonably accurately control bend angles with various materials. To advance this process further for realistic forming applications in a manufacturing industry, it is necessary to consider larger scale controlled 3-dimensional laser forming. However, this is a different situation for 3-dimensional laser forming. The work presented in this paper uses the spider scanning path to form the thin square sheet to spherical dome by laser forming. The explicit dynamic analysis on 3-dimentional laser forming is shown in the article. On the base of temperature gradient mechanism of 2-dimensional laser forming, depending on the geometry and the thermo-physical properties of stainless steel lCrl8Ni9Ti, develop the mechanism of laser forming of thin square sheet to the spherical dome. This paper discusses the interaction between moving laser beam and sheet, the temperature field on the sheet, and the step transition of stress and deformation in laser forming. In order to give the verification on the results of simulation, the correlative experiment has progressed with Lumonics JK7O2H Nd:YAG laser. The results of experiments are in accord with the simulation.

Laser Target Alignment Sensor (LTAS) focus high energy laser beams on the sub-centimeter size fusion targets at the precise location and adjusts the final focus lenses to set the spots size in Initial Control Fusion (ICF) experiment. The operational requirements of the ICF system place tight constraints upon the precision of the LTAS. Therefore, a calibration system which can adjust conjugation distance of the LTAS, compensate the location of the beam spots, and calculate the axis and magnification of the objectives is designed. The system is composed of a long focal-length telemicroscope, a high resolution CCD, a NC dividing head, an X-Y linear stage, a multidimensional target positioner and two simulated laser beam generators. Feedbacks based on the LTAS images of the target and laser points are used to null offsets of the LTAS on conjugation distance. The methods of objective and CCD parameter calibration are presented. Experiments for the positioning accuracy test show that after calibration, the repeatability error of the LTAS for the target center location is better than ±0.7&mgr;m. The system can realize accurate calibration of the LTAS before putting it into target chamber, which will improve the precision of ICF experiments effectively.

The correlation method for processing signals from a single-fibre multimode interferometer by using a digital charge-coupled device is studied experimentally and theoretically. Optimal conditions are determined for recording multimode interference patterns with charge-coupled devices. It is found that the nonlinearity of characteristics of such devices affects the results of correlation measurements. The method for eliminating this influence is proposed. The correlation method considered in the paper allows one to measure a linear deformation of the interferometer within 0-80 &mgr;m with an accuracy of ~ ±3&mgr;m for typical single-mode fibres with the core diameter 50 &mgr;m.

The FWD (Falling Weight Deflectometer) is an instrument which makes the weight fall freely on its loading plate to apply impact load and measures the displacement caused by the fall at the center of impact load and also at the points in radial direction from the center of impact load. A kind of instrument which is mounted on or drawn by a vehicle used for construction of concrete pavement or asphalt pavement of a runway is usually called FWD. The impact load of FWD is 49KN to 196kN and it can obtain the modulus of elasticity of each pavement layer by back analysis based on the theory of multi-layer elasticity using 6 to 8 of extemal displacement sensors. On the other hand, the small FWD is an FWD which is constructed small and easy and is applicable for hand carry. It makes the weight fall freely on the loading plate to apply impact load and measures the load and displacement caused by the fall. It was developed for mainly assessing the rigidity and bearing capacity of the subgrade easily and promptly. It can measure many points in short term and obtain coefficient of subgrade reaction and modulus of subgrade elasticity without using reaction facilities like as plate bearing test or CBR test. It has also been tried to apply the small FWD to low cost asphalt road pavement (later called as low cost road pavement). Application examples of small FWD test for earth structure and low cost load pavement in Japan are shown and the methods and test results are stated in this report.

The traveling salesman problem, which is one of combinatorial optimization problems, is solved by using two different methods: the Hopfield type network and the Kohonen type network. In the Hopfield type network the energy function is defined, whose global minimum must be searched. The energy is shown analytically to decrease monotonically. The time behavior can be discussed analytically, because the input-output function is piecewise linear. The network can always find the optimum solution. In the Kohonen type network the modified version is proposed, in which the mechanism of choice of winner neuron is included automatically in the time evolution equation of the internal state. In usual Hopfield 's network N x N neurons are needed to solve TSP with N cities. It is shown that only N neurons are needed in modified Kohonen's network, which means that the network has a great advantage in the case of the application to TSP with higher number of cities or in the application to more complicated combinatorial optimization problems. The relation between the Hopfield type network and the modified Kohonen type network is discussed.

There will be many stations in Optical Theodolite Coordinate Measurement System (OTCMS) to measure different part of the object; data from each station must be fused together. Traditionally, the data will be transformed to a global coordinate system and combined directly, therefore errors may be brought in and redundant information may exist. In order to reduce the errors and integrate the redundant data, a fusion algorithm based on multi-sensor system is discussed and a distributed multi-sensor data fusion model based on Kalman filtering is developed. Experimental results indicate that the method produces precise estimation.

A novel ultrasonic phased array detection system is developed for nondestructive testing (NDT). The purpose of the system is to make acquisition of data in real-time from 64-element ultrasonic phased array transducer, and to enable real- time processing of the acquired data. The system is composed of five main parts: master unit, main board, eight transmit/receive units, a 64-element transducer and an external PC. The system can be used with 64 element transducers, excite 32 elements, receive and sample echo signals form 32 elements simultaneously at 62.5MHz with 8 bit precision. The external PC is used as the user interface showing the real time images and controls overall operation of the system through USB serial link. The use of Universal Serial Bus (USB) improves the transform speed and reduces hardware interface complexity. The program of the system is written in Visual C++.NET and is platform independent.

One of the most perspective types of invariant correlation filters are LPCC (Linear Phase Coefficient Composite) filters. Application of the given type of filters allows the receiving of invariance of correlation peak to various types of distortions of object. In the given paper results of studies LPCC filters designed for various types of correlators are discussed. Results of synthesis of filters and calculations of correlations of images with the constructed filters are presented in comparison.

In this paper results of the analysis of realistic architectures of optoelectronic vector-matrix processors are submitted. Possible variants using various perspective number systems are considered. Throughput, accuracy, fan-in and fan-out, and required volume of pre- and postprocessing depending on used architecture and number system are estimated.

The nonlinear absorption mechanisms in transparent materials under ultrashort laser pulses irradiation are considered theoretically. Nitride semiconductor, sapphire and others transparent dielectrics was investigated. The ablation threshold for theses materials is in multi-TW/cm² range. The model is used based on the tunneling absorption under the irradiation by high intensity ultrashort pulses in terms of theory of ionization of solid in a field of strong electromagnetic wave. Sartisfactory explanation is found of the influence of the material energy bandgap on the laser ablation threshold.

A computer holography is the optical hologram recording on the CCD-matrix with digital reconstruction of the 2Dimages for the different volume object cross-sections. The possibility to use compact semiconductor laser diodes in the computer holography for 3D-scene registration is experimentally proved in the D. Gabor's scheme. For off axis hologram recording the S. Benton's scheme for holography using is suggested.

The discrete system mathematical model with casual chaotic structure for algorithms synthesis to radar-tracking coherent and noncoherent images of spreading surface is investigated. Discrete systems with casual chaotic structure are understood observably in the discrete moments of time as stochastic dynamic systems which structure has final number of possible conditions, varied each other at the casual moments of time. Radar images processing (segmentation) by two new algorithms in remote distance problems applications are discussed.

A digital phase manipulation for images processing on the algorithm similar to the optical Foucault knife considers by means of computer modeling method. The images quality preservation at decomposition in Walsh-Hadamard and Haar spectrum was investigated. It is shown, that Foucault knife for the digital image can be simulated on the basis of calculations in real numbers space. In this case there is a possibility to select the image contours, too.

Image recognition methods based on evaluation of intensity Fourier-spectrum circular and radial harmonics are attractive for applications due to the possibility to obtain a range of features invariant to the shift, rotation and change scale of the input image. Application of array of photodetectors with special topology in a combination with digital postprocessing allows to achieve high accuracy of measurement of harmonics in optics. In paper results of experiments of high accuracy measurement of circular and radial harmonics are presented.

Conflicts among high speed, large amount of data rate and long time to record are still problems in the field of frame grabbing. It has been settled partly and temporarily by the development of raid technology. A frame grabbing system with the characteristic of high speed and large storage is generated using raid technology and Fibre Channels. It is able to keep recording frames at a high speed for a long time without reducing resolution. The system has been set up successfully whose recording and displaying process can be generally controlled. Problems that show stable live video in real time while recording have been solved. The composition of hardware in this system is given out in the paper. The principle how it works is described. For the purpose of recording at a high speed without dropping frames and to insure the imaging quality while synchronized with outer signals that generated from an outer circuit, several synchronizing ways are discussed and compared. The most suitable way is chosen through analyzing theoretically and tested out by experiment.

An automated system is developed and described for the inspection of the surface distress of highway pavements in this paper. The system comprises of four modules: artificial illumination module, image acquisition module, sync control module, data storage and analysis module. The system is capable of collecting and analyzing highway cracks with high-resolution digital images. The system can carry out crack surveys at a nominal speed of 72km/h with full coverage of pavement surface. Crack recognition is performed offline. The prototype has been tested in laboratory conditions and completed a survey of about 15,000km real road at normal running speed (72km/h).

We report on simple high-sensitivity interferometric technique of detecting vibrations and present characteristics of laser vibrometer using GaAs, CdTe and CdZnTe adaptive photodetectors based on the effect of the non-steady-state photoelectromotive force. It enables efficient direct conversion of high-frequency phase modulation of speckle-like optical wave reflected from the vibrating object into an output electrical signal with concomitant setting of optimal operation point of the interferometer and suppression of amplitude laser noise. The results of measurements of semiconductor material's parameters of CdTe and CdZnTe are presented. The experiments are carried out for diffusion regime of signal excitation at light wavelength &lgr;=1.15 &mgr;m. The sign, conductivity and diffusion length are estimated from the dependencies of the signal on the temporal and spatial frequencies. Preliminary studies at 1.06 &mgr;m showed that it is possible to detect ultrasonic vibrations with the amplitude of 0.2 Å with a signal power of 20 mW and a bandwidth of 15.5 MHz. This optical phase-to-electrical signal converter is not sensible to ambient vibrations, thermal drift, amplitude laser noise and is therefore appropriated for industrial applications.

In this work we tried to create a mathematical model of thermal response of laser irradiated multilayer biological tissue. The tissue has 4 horizontal radial symmetric layers with its own optical-physical characteristics. We used the results of Monte Carlo modeling to describe the propagation of light (laser beams) in tissue and receive the function of heat source after we multiply the density of thermal emission by absorption coefficient. As we usually have radial symmetric laser beams we can use cylindrical coordinates. The solution of the 2D heat conduction equation is based on finite-element theory with using square finite elements. We simulated constant laser fluency and as result there are temperature fields. The analysis of the results represents, that heat does not localize on the surface, but collects inside of the tissue. By varying the boundary condition on the surface and type of laser irradiation we can reach high temperature inside the tissue without formation of necrosis at the same time.

A wireless acceleration sensor network is proposed for the purpose of structural global monitoring of civil engineering structures. The multi-layer network structure is provided and the communication protocol is designed; Several modules are constructed using commercially available parts, and integrated into complete wireless acceleration sensors and base stations. And the life of wireless acceleration sensor is calculated and the performance test is performed. The acceleration test is finished on cable-stayed bridge of Songhua River, and the experimental results are given to show the feasibility of the designed wireless acceleration sensor network.

The ultrasonic phased array inspection imaging system was developed in this paper, which is integrated on the basis of the each module and the exploitation of subsystem, it is made up of computer, ultrasonic circuit system, scanning device, phased array transducer and imaging software. The ultrasonic phased array inspection imaging system has the functions of controlling ultrasonic transmission and reception, controlling sound beam steering and focusing, controlling scanner moving, receiving flaw information and position formation, restructuring flaw image and commenting damage. Experiment was done on the fillet weld block of T shape flat plate with some artifical flaws using the ultrasonic phased array system, the flaws characteristic could be exactly estimated through comparing and analyzing the flaws position in B-scan image and the waveform feature in A-scan curve, and the flaws size could be measured from the image of C-scan and D-scan. Experiment results indicate that the flaws detected by the manual ultrasonic inspection technology could be found over again by the ultrasonic phased array inspection technology, the flaws size measured by the latter is close to the former, the whole trend of development of flaws are factually imaging by the latter.

The sufficient attitude knowledge including location of recognized stars in star image can be obtained with Lost-in-Space case. In order to make use of the sufficient attitude knowledge, the star sensor may work in star tracking case. To achieve this, a star tracking algorithm is proposed in this paper. The previous location of recognized stars in star image may be used to obtain location of observed star in proper region of current star image with the star tracking algorithm. The simulations and real sky experiment results show that the star tracking algorithm proposed in this paper not only improves update rate of star sensor, but also avoids fault star pattern recognition. Finally, a star sensor featuring star tracking algorithm proposed in this paper was for on-orbit demonstration.

The bubble backscattering intensity between 140 and 160 degree is achieved utilizing bistatic method, and the bubble scattering signal is detected, analyzed and processed. The photo multiplier tube is used to detect the weak signal. Threshold detection distinguishes between the bubble backscattering and water backscattering. Bubble scattering pulses are stationary random signals and have statistic properties. So the sample average for an enough long time may be as the scattering intensity at a certain angle. Experimental results have the same trend as the theoretical results. The experimental research on the bubble backscattering properties is importance to the ocean sensing and wake homing.

The water-jet guided laser processing is a new compound micro-machining process in which the laser beam passes through the water-jet by full reflection onto the workpiece. In this paper, a new key component:the coupling unit was designed and which would form a long, slim, high-pressure and stable water-jet. The couple unit made the fluid field in the chamber symmetry; the coupling quality of the laser beam and the water-jet could be easily detected by CCD camera. For its excellent surface quality, the nozzle with a &fgr; 0.18mm hole got better machining effect than other nozzles. Aiming at finding optimum machining parameters, experiments were carried out. The results showed the attenuation of laser energy bore relation to water-jet stability. The energy intensity distributed over the water-jet cross section nearly homogeneous and the laser energy nearly did not decrease in long working distance. When water-jet pressure was high, efficient cooling of the workpiece prevented burrs, cracks and heat affected zone from forming. During cutting Si wafer process, nearly no cracking was found; Adjusting reasonable laser parameters grooving 65Mn, the machining accuracy would combine with the speed.

To solve the problem of slow speed in single point scanning confocal measurement, a new way to make 3-D morphology confocal detection by optical fiber beam is presented. In the new system, with the point light source produced by optical fiber array and light intensity information detected by pinhole array, the synchronous scanning of the measured surface is done. Compared to the multi-probe detection system of lens array, the new system has the characteristics of simple structure and low price. Based on the general confocal principle and with Fourier optics theory, the 3-D point spread function of a simple fiber pinhole pair is got. With the matrix operating form, the imaging characteristic of the multi-probe measurement system is analyzed. Meanwhile, the conclusion of theoretical analysis shows the total light distribution of the multi-probe detection system conforms to the multiplication form of each detection light path.

Optical coherence tomography (OCT) is a recently developed imaging technology. By using Zeiss STRATUS OCT one could obtain clear tomography pictures of retina and macula lutea. The clinical use of image processing requires both medical knowledge and expertise in image processing techniques. This paper focused on processing of retina OCT image to design the automatic retina OCT image identification system that could help us evaluate retina, examine and clinically diagnose the fundus diseases. The motivation of our work is to extract the contour and highlight the feature area of the focus clearly and exactly. Generally it is related to image segmentation, enhancement and binarization etc. In the paper we try to reduce the image noise and make the symbolic area connected through color segmentation, low-pass filter and mathematical morphology algorithm etc., finally discern some common and different properties of postprocessing image compared with the real OCT image. Experiments were done on cystoid macular edema, macular hole and normal retina OCT image. The results show that the project raised is feasible and suitable for further image identification and classification according to ophthalmology criteria.

Optical correlation enables the rapid identification of targets within an input signal. This is due to the inherent Fourier-transforming property of an optical lens system. The quick development of Liquid Crystal Display (LCD) brings opportunity to simply the optical inspection system. The most important part of the system is the joint transform correlator (JTC). The self-correlated peaks of target image and reference image display overlapped in the center of output plane. Its high-intensity and wide-breadth affect the correlation peak recognition. A Gaussian filter of power spectrum processing is proposed. It can weaken the zero-order bright spot in the correlation plane, narrow the bandwidth of the zero-diffractive peak, leach noises efficaciously and sharpen the correlated peak. This method is simple and efficacious, adapts to real-time JTC.

The application of optical systems may be conveniently grouped into guidance applications, in which the position of a star, planet, or other body is sensed in order to maintain vehicle attitude and position; into surveillance applications, in which a view is maintained toward space to detect and track missiles, other space vehicles, or celestial bodies. When spacecraft moves around earth, volatile condensable material (VCM) recondensing on the surface of the window induces the degradation of optical performance. In order to insure spacecraft fulfilling its work successfully, space optical designers must think of sublimation, decomposition, and offgassing of materials in vacuum and the possible deposition of products from such actions onto optical surfaces. Still now, lots of antipollution works have been done. But little work is done to analyze VCM how to influence imaging. However, it not means that such work is not important. First of all, it is supposed that the VCM which looks like circle grain spreads on the surface of optical system equably. Then the point spread function (PSF) of optical system under kinds of contamination spread density is obtained. The result indicates that the envelope line of PSF widens. This means that the resolution of optical system will reduce, which induce low detection sensitivity. It is obtained that VCM leads not only low optical transmissivity but also worse imaging quality. And it is emphasized PSF effecting on imaging quality in this paper.

In the given article the method of optical information gathering from the fiber-optical measuring network with its subsequent processing is offered. In this method the algorithms of neural-like networks in computation process is introduced. Each sensitive area of the fiber-optical measuring line is associated with the own amplifier. Adjustment of amplifiers gain factors carries out modification of the weighting coefficients of the matrix of connections of the neural network. The training principles to external physical influences are represented. The selection of the type of the neural network for decision of the fiber-optical tomography problem of spatial distribution reconstruction has been considered.

Based on the actuation and sense function of piezoceramic materials, PZT active health monitoring for fatigue accumulative damage of concrete beam containing nano-particles (TiO₂) for pavement is experimentally studied. The test results indicate that the vibration signals received by PZT patches have three development stages obviously: the damage-formation stage, the damage-steady-growth stage and the damage-sharp-growth stage, which shows that PZT patch can monitor the whole course of the formation and growth of cracks in concrete and the failure of concrete beam. The fatigue damage index of concrete based on wavelet packet decomposition is established, and its change trend is similar to that of fatigue damage of concrete. In the range of 0%-10% of fatigue life, the damage index is approximately zero, which means that the concrete beam is basically in a healthy state and internal cracks are germinating. In the range of 10%-90% of fatigue life, the damage index increases from zero to a smaller value slowly, which means that the cracks in concrete propagate slowly. After the 90% of fatigue life, the damage index increases rapidly, which means that the cracks in concrete extend sharply and run through up to the fracture failure of concrete beam. The magnitude of damage index can show the serious extent of fatigue damage in concrete and the healthy status of concrete. The fatigue damage in concrete can be located by comparing the amplitude character of break signals or the change regularity of damage indices of PZT patches attached on concrete beam in different position. Moreover, the smaller the distance of PZT patch from the damage is, the more obvious the signal break and the change of damage index of PZT patch are, and the more sensitive the identification of PZT patch to the damage is.

A linear photodiode array spectrometer based, high resolution interrogation technique for fiber Bragg grating sensors is demonstrated. Spline interpolation and Polynomial Approximation Algorithm (PAA) are applied to the data points acquired by the spectrometer to improve the original PAA based interrogation method. Thereby fewer pixels are required to achieve the same resolution as original. Theoretical analysis indicates that if the FWHM of a FBG covers more than 3 pixels, the resolution of central wavelength shift will arrive at less than 1 pm. While the number of pixels increases to 6, the nominal resolution will decrease to 0.001 pm. Experimental result shows that Bragg wavelength resolution of ~1 pm is obtained for a FBG with FWHM of ~0.2 nm using a spectrometer with a pixel resolution of ~70 pm.

Fiber interferometer sensors are widely used in sensor technology, and have considerably high sensitivity. PGC(Phase Generator Carrier) technology is the most useful modulation method. Traditional PGC methods have quite complex demodulation algorithm since they use sinusoid phase modulation. This complexity limits their use in large scale multiplexing. In this article, we will first introduce a two step modulation and its demodulation algorithm with two sample rates: one sample points per one step and two per one. Furthermore we will amend it to a four-step phase modulation. Also a method of modulation depth feedback is introduced. With this method we can control the modulation step to be exactly &pgr;/2 . An estimation for DC content required by the demodulation is introduced too. The demodulation algorithm requires 4 sample points for one demodulation output point. The most advantage of this modulation method is that it is quite easy to realize with AOM(Acoustic optic modulator) and has a very simple demodulation algorithm. For every output point we should do two additions and one arc-tangent calculation. With 8 sample points, with five additions and two multiples, we can have one modulation step feedback point( the output rate is 1/8 of input rate). Only the power estimation needs to be carried out every sample period, but it is only some additions. Also there will be no need for digital filters during demodulation.

In this work, a study of a new type of optical fiber interferometer with three-beam system has been carried out. Some analyses of the performances of the interferometer have been considered and reported upon. A theoretical model of the optical fiber interferometer and demonstration that such system could be constructed by optical fiber structures are presented. To achieve the goal which ensures higher performance and stability of the interferometer the simulations for intensity noises, phase noise in the interference path and phase shift noise of the certain three-beam optical fiber interferometer have been carried out. The results indicate that the 3 ×3 coupler is key factor. The optical fiber interferometer could be used to constitute an optical fiber sensor such as optical fiber hydrophones array. Other applications of optical fiber sensor with the three-beam interferometer also have been discussed.

A novel method based on interferometry for measurement of fine surface roughness is proposed, designed and completed. The polarization state of the optical beam in one path is changed utilizing a half wave-plate in this design, avoiding the reversibility of the beam in similar systems previously reported, so that the stability of the system is ensured. A quarter-wave plate is used to make the consistency of the polarization states of the coherent light to obtain the better visibility. The absolute measurement values of the surface roughness are achieved using two concentrical beams scanning the surface. The set-up is simple and easy to be realized. Experiment results show that roughness of R_a=0.012&mgr;m is achieved.

A fiber optic intensity based sensor for remote inclination measurement has been developed based on light beam displacement caused by a free hanging deflector glass plate as it changes its angular position relative to the body of the sensor. Light intensity drift compensation is achieved through the comparison of two output signals obtained from the two spaced measuring channels integrated in the sensing element. The specifications of the sensor are as follows: threshold sensitivity - O,01°, dynamic range - 25 dB, measuring angle range - ±4°. As a result of sensor performance equalization its output signal variation corresponding to 30% input light intensity decrease does not exceed ±4%.

An optical sensor based on the theory of Fabry-Perot interferometer for the measurement of electrical voltage is presented. A structure of the fixed cross beam with a salver is designed by ANSYS. The deflection of the salver forced by an electromagnetic force leads to the displacement of the beam. This displacement causes the change of the length of the FP microcavity. Interrogation of the microcavity is achieved by FBG correlative demodulation. The arms of the fixed beam are identical, all with 10mm in length, 2mm in width and 0.25mm in thickness. The salver is 0.3mm in thickness and has a radius of 16mm. The voltage changes from 0kV to 10kV in this work and the output light intensity is as 4.25 times as the initial value. The simulation results are also given in this work.

Insulation failures caused by partial discharges (PD) in power transformers affect safety and financial terms in power systems. The method to measure acoustic pressure generated by PD is researched widely. An all-fiber sensor that is dielectric structure is potential demand in high voltage power equipment. In this paper, an optical fiber system based on Fabry-Perot (FP) sensor is established to detect ultrasonic signals generated by PD in transformer oil. As a sensing unit of the sensor, Fabry-Perot cavity is formed between a quartz diaphragm sensitive to dynamic signal and an end of fiber pigtail. The output optical signal is modulated by acoustic signal reacted on the diaphragm. A new demodulation method to FP sensor using Fiber Bragg Gating is presented. The system has inherent immunity to electromagnetic interference and resistance to harsh environment. According to theoretic analysis and computer simulation, the system shows high sensitivity and resolution.

For many defects existing in the traditional voltage converter, a voltage probe is constructed by sticking a FBG on a PZT bar and the FBG sensor is demodulated with a CWDM based demodulation scheme and the high potential monitoring is realized. The FBG dynamic demodulation principle is introduced in this paper. The dynamic performances of the system were verified through experiment. The system repeatability is not worse than ±4% although there is no any kind of compensation based on data analyzing. A new realizable method was proposed in this paper.

The Operating principle of Fiber Bragg Grating Strain Sensor is introduced. A new demodulation method, which is by making use of the linear decline section of an amplified spontaneous emission (ASE) light source, was propose for Fiber Bragg Grating (FBG) sensor. The setting is simple, broad measurement range, appropriate sensitivity and measurement of static and dynamic. We have measured the strain of the cantilever, got the linear relation between output voltage and axial strain of the cantilever. The output voltage and theoretical value is fitted very well.

In this paper, the optimized Fiber Bragg Grating Sensor Arrays system, which was based on Optical Frequency Domain Reflectometry(OFDR) Multiplexing and Fabry-Perot Tunable Optical Filter(TOF) Demodulation Technology was Introduced, that FBG sensors in the same operating waveband can be used in different beat frequencies positions was proposed, and then a simulation was made for this proposition. As a result, in the case of duty ratio of the modulation signal w=1, the maximum amplitude B=4OMHz, and saw-tooth frequency f_s=5kHz,the maximum measurement range can reach 4000m and , the minimum resolution can be reduced to 2.58m. In addition, A/D converting circuits and a DSP COMS chip were suggested to be designed for the function of frequency mixing, wavelength filtering and Fast Fourier Transform so that instead of expensive frequency analyzer, so that the system cost can be reduced.

One of the most significant limitations of FBG sensors is their dual sensitivity to temperature and strain. Many methods have reported to avoid this problem by using a tapered fiber grating for the strain measurement free from temperature influence. But all of them are based on the measurement of the reflected power from the tapered fiber grating (TFG). In fact, they have abandoned the major advantage that the measured information is encoded in light wavelength instead of light intensity of FBG sensors, and the revolution of these sensors is begin to depend on the light power fluctuation, connection loss and many other elements. All of these would enlarge the cost of the sensing system. On the basis of the theory calculation and experiment, we demonstrate the feasibility to make a temperature-independent strain sensor by measuring the bandwidth of the reflected light from the tapered fiber grating. In this paper, we also present a novel demodulating method based on a scanning FBG. In the experiment, a PZT is used to make the reflected wavelength of FBG scanned from short wavelength to long wavelength to measure the bandwidth of the reflected light from TFG. From the experimental results, it could be seen that the influences of the light power fluctuation and connection loss are eliminated thoroughly. This simple and low-cost sensor approach has a considerable potential, particularly application for strain sensing in the smart structures.

A novel FBG obliquity sensor is proposed. In this sensor one half of the FBG is stick to the fixed end of a cantilever, and the other half remains at freedom state. The difference of the center reflection wavelength of the two half of the FBG changes linearly with the sine of the obliquity from 0284 to 0393(linear degree 0.9956) . In this sensor cross sensitivity is alSo eliminated by the different strain coherent of the two half FBG. If combined with another sensor of the same structure, the sensing of two dimensional obliquity is achieved. The research demonstrates that the new sensor system has the advantages of simple and compact structure, easy manipulation, low cost, light weight, etc.

A novel laser interferometer which adopts alternating modulation phase tracking homodyne technique is proposed. The vibration of nanometer-accuracy is measured with the improved Michelson interferometer by adding cat's eye moving mirror and PZT phase modulation tracking structure. The working principle and the structure of the interferometer are analyzed and the demodulation scheme of alternating phase modulation and tracking is designed. The signal detection is changed from direct current detecting to alternating current detecting. The signal's frequency spectrum transform is achieved, the low-frequency noise jamming is abated, the Signal-to-Noise of the system is improved and the measured resolution is enhanced. Phase tracking technique effectively suppresses the low-frequency noise which is caused by outside environment factors such as temperature and vibration, and the stability of the system is enhanced. The experimental results indicate that for the signal with the frequency of 100Hz and the amplitude of 25nm, the output Signal-to-Noise is 30dB and the measured resolution is 1nm.

This paper presents an interrogation system based on the linear nGaAs photodiode array and volume phase grating. By applying SDM and WDM technology, we have developed the interrogation system based on the linear lnGaAs photodiode array and volume phase grating. The system has the following advantages: small size, low power consumption, high resolution, interrogation speed, repeatability and reliability. Experimental results show that the interrogation system can be used to interrogate the FBG sensors with wavelength bandwidth of 42nm, SNR of about 30dB, wavelength accuracy of ±15pm, and it shows a good prospect.

A multi-parameters measurement technique that uses four-core fiber as the sensing element has been proposed and demonstrated. The four-core fiber act as a four-beam interferometer in which phase differences is a function of curvature, twisting angle, and the variation of temperature in the plane containing the cores results in the shift of the farfield interferometric grid pattern. The relationship between the far-field grid pattern shift and the multi-parameters has been established and the experimental results were also confirmed this.

Fluorescence fiber sensors are broadly used to measure temperature, concentration, and pH value etc. The fluorescence sensing systems are based on different principles, namely fluorescence intensity, fluorescence intensity ratio, and fluorescence lifetime. The fluorescence lifetime is an effective parameter for sensing purpose, because it is independent on the intensity of the pumping source and does not need expensive narrow-band filter. An experiment system has been established. Some samples are produced to measured the fluorescence lifetime of temperature characteristic and get the relationship of strain and temperature versus the fluorescence lifetime at the same time. The experiment result was fitted and analyzed. The test results show that the fluorescence lifetime decreased with the increasing of temperature. The change of fluorescence lifetime with the strain is inconspicuous comparing to that with the temperature.

A portable and practical fiber micro-drop sensor, with which can determine the refractive index and the concentration of the liquid, has be designed and realized. The advantages of this sensors combines simplicity of structure, facility of operation, wide range of measurement and low price. Liquid drops formed at the tip of a liquid sensing head are measured by a fiber sensor. The fiber sensor works as follows: infrared light source is injected into the drop through an optical fiber and the total internal reflections and absorptions are detected by a photo detector. A drop speed independent one-dimensional waveform, fiber fingerprint drop trace (FFDT), is generated. Liquid surface tension, refractive index and dielectric constant can be estimated from the fingerprint. For the effective use of the sensor, a new on-line method of liquid drop analysis is proposed, which is used for liquid discrimination with the orderliness of the fiber fingerprint drop trace. To compare two fingerprints effectively, signal analysis is required. Comparing fiber fingerprint drop trace, which might cause peaks and valleys in the trace at almost the same wavelet, digital signals process is more intuitionist. Analyzing every part of the fingerprint drop trace with impactful signal analysis method, as Fast Fourier Transform algorithm and correlative analysis, some orderliness can be revealed. Colligating the orderliness, we can discriminate all kinds of liquids or their characteristic parameters, such as liquid concentration, refractive index and so on.

In this paper, we demonstrated a distributed Brillouin sensor based on the offset locking of two 1550nm DFB lasers. We use PID controller and optical delay line to lock and tune the frequency difference between two DFB lasers and we also use lock in amplifier to stabilize the DC level of the EOM. The power depletion in the Brillouin scattering has been studied to show optimized strain and temperature accuracy. With this sensor system, we can get the spatial resolution which is 1m with temperature resolution of < 1°C.

Firstly, Wavelength shift of Fiber Bragg Grating (FBG) sensors that monitor the arch bridge suspender tension due to strain or temperature change has been studied theoretically, and theirs sensitivity coefficient is gotten through calibrating experiment. Secondly, the FBG strain and temperature sensors have been successfully installed in some key suspenders of Sichuan Ebian Dadu river arch bridge. Techniques of installation of FBG sensors and suspender repairing have been explored in-service arch bridge. Thirdly, the change of suspender strain and temperature, and the effect of the same loading to different length suspender have been monitored with the FBG sensors. The monitoring results show that the FBG sensors can monitor correctly the change of traffic loading and temperature, possible fatigue damages, FBG sensors are more adaptive to long-term structural health monitoring than the electric strain gauges.

Conventional non-destructive methods can't be dynamically monitored the suspenders' damage levels and types, so acoustic emission (AE) technique is proposed to monitor its activity. The validity signals are determined by the relationship with risetime and duration. The ambient noise is eliminated using float threshold value and placing a guard sensor. The cement mortar and steel strand damage level is analyzed by AE parameter method and damage types are judged by waveform analyzing technique. Based on these methods, all the suspenders of Sichuan Ebian Dadu river arch bridge have been monitored using AE techniques. The monitoring results show that AE signal amplitude, energy, counts can visually display the suspenders' damage levels, the difference of waveform and frequency range express different damage type. The testing results are well coincide with the practical situation.

Fiber reinforced polymer (FRP) has gained much attention in civil engineering due to its high strength-to-weight and stiffness-to-weight ratios, corrosion resistance and good fatigue resistance. Optical Fiber Bragg Grating (OFBG) is now widely accepted as smart sensor due to its advantages of electric-magnetic resistance, small size, distributed sensing, durability, and so on. Combined the FRP with OFBG, new kind of smart FRP-OFBG composite laminates was developed. Fabrication method of the smart composite laminates was introduced in this paper. The study presented the basic principle of OFBG sensors. Then the strain and temperature sensing properties of the proposed smart FRP-OFBG composite laminates were experimentally studied on material test system and under hot water, respectively. The experimental results indicate the strain sensing properties of the smart FRP-OFBG composite laminates are nearly the same as that of bare OFBG, however, the temperature sensing abilities of the smart FRP-OFBG composite laminates are improved and the sensitivity coefficient is nearly 3.2 times as much as that of bare OFBG. The strain and temperature sensing precisions of the smart FRP-OFBG composite laminates are 1 &mgr;&Vegr; and 0.03 °C, respectively. The smart FRYOFBG composite laminates are very proper for application in civil engineering.

Based on the mode equations of the core mode LP₀₁ and the cladding mode LP_0M, combining with the phase matching condition, a method for simultaneous measurement of liquid refractive index and temperature using a single resonance peak of long-period fiber grating's transmission spectrum is proposed. The operational principle is analyzed; experiments are conducted. The theoretical results are compared with those of the experiments. The results show that they are in accordance with each other.

The FBG bending gauge developed by POFC is applied in several situations involving bridge safety/health monitoring. Under static loading conditions, the FBG bending gauge serves as an excellent tool to deduce an overall deflection curve on the bridge section under study. The gauge also works well in dynamic situations where instantaneous vertical deflections of bridge structures resulting from a cruising dump truck were accurately measured.

A remote multiplexed methane sensor system taking advantage of low cost 1.33 1&mgr;m SLD is demonstrated. it has long time stabilization, immunize from the influence of the temperature changing. Reference light is adopted in the system to reduce the affection of attenuation caused by long distance transmission of light in fiber and the drift of the SLD output power. Resolution of 0.01% (10-s time constant) is obtained by introducing intensity modulation and Lock-In-Amp.

The dispersion properties of the reflection-induced retardance of the polarization- preserving reflecting medium layer and its effect upon the sensitivity of an optical current sensor are theoretically analyzed taking the Jones' Matrix as a mathematical tool and simulated with a computer. The investigation results show that the dispersion will obviously affect the scale factor of the system. Therefore, it is necessary to stabilize the driving current and the ambient temperature of the optical source by some technical means. These results might be useful for the researchers and designers working in the optical current sensing techniques area.

The effect of the dispersion of Verdet constant of ZF-7 optical glass upon the sensitivity of a bulk-glass optical current sensor are theoretically analyzed taking the Jones' Matrix as a mathematical tool and simulated with a computer. The investigation results show that the dispersion will obviously affect the scale factor of the current sensor. Therefore, it is necessary to stabilize the driving current and the ambient temperature of the optical source by some technical means. These results might be useful for the researchers and designers working in the optical current transforming techniques area.

Construction monitor is an important way to ensure safety and economical efficiency at construction stage of civil engineering, and monitor technique is one of the key elements to actualize the monitoring scheme. During construction of the foundation of the Third Nanjing Yangtze Bridge, FBG techniques were adopted due to complex site environment and high quality requirement of the engineering. The study group not only presented applicable embedding method of FBG sensors, but also developed monitor software according to mechanical analysis of each object. The practice demonstrates that the sensors worked well and had provided reliable data for decision-making in construction.

A new fire alarm system based on FBG sensor has been investigated to determine its potential in fire alarm applications for highway tunnel. The system has been experimentally tested and some of its application are reported. The results show that the new fire alarm system is capable of fixed temperature alarm and rate-of-rise alarm promptly; the fire place can easily determined according to the location of maximum temperature; the temperature distribution and the rule of temperature development in the tunnel can be obtained at the same time.

State-of-the-art of bare fiber end polishing techniques are introduced and demonstrated. It is essential for many applications such as in low loss, high bit rate communication system and special requirement for fiber sensing probe.

Long lasting service performance has been one of the most important qualities in high way engineering. In this paper, one type of strain sensor used for measuring and monitoring of asphalt pavement is presented and relevant numeric analysis is introduced. Application of this kind of sensor in an express highway shows that the sensors based on Fiber Bragg Grating technique and their embedding craft are applicable.

Using a fast polarization mode dispersion (PMD) with 15-second interval and long measurement duration (>24h), we found the correlation between polarization effects, tides and sun radiation on submarine fibers. We also found that using state of polarization measurement we can measure the vibration frequency of the optical fibers.

Distributed Brillouin sensing Technique represents a new physical approach for temperature and strain measurements, which is based on optical time domain reflectometry (OTDR), and seems extremely promising for Structural Health Monitoring (SHM) and being received most attention. Due to the intrinsic distributed sensing capability, Brillouin can measure the temperature and strain using a single-mode fiber, which retains other typical advantages of Fiber Optic Sensors (FOS). This paper stated the current situation and prospect of distributed Brillouin sensing.

The effects of reciprocal optical parameters of a bulk glass current sensing head upon the polarization state of the output optical beam of a Faraday Mirror-typed Optical Current Transformer (FMOCT) are theoretically analyzed, digitally simulated and compared with that of an optical current transformer with polarization-preserving total reflection coatings in this paper. The results show that the FMOCT design can effectively suppress the polarization state fading of the output optical beam induced by the reciprocal optical parameters of the bulk glass current sensing head. The work reported here might have some reference significance to the performance improvement and development of bulk glass optical current transformers for practical applications.

New polarization properties have been observed from the Fresnel reflection on the waveforms of OTDR with the commercial OTDR produced by Anritsu company. Then a better POTDR system was established in order to discover the accurate properties, and more remarkable result was obtained by the Serial Data Analyser(SDA5000A).

A novel electric current sensor based on FBG and magnetostrictive composites, which is made from epoxy resin and Terfenol-D particulates, was fabricated. The relationship between the strain of the sensing head and the magnetic field intensity was obtained. The new sensor exhibited a good linearity and repeatability, which indicates its potential to be a practical electric current sensor.

A new kind of optical liquid drop detecting sensors is presented, using a tapered fiber as the sensing head. The dripping speed of the liquid drop influences the intensity of the reflected and transmitting light inside the tapered fiber, because the reflected or transmitting light intensity depends on the refractive index of the material outside the tapered fiber. The advantages of this type of sensors are experimentally demonstrated such as high sensitivity, reliability and immunity from interferes. The detecting veracity is 100% when dropping speed below 6 drops per second in the experiment. The change of liquid dropping-speed can be monitored.

We report a new hybrid optical bistable device by using a 98OnmLD pumped, electrically tunable widely wavelengthswept fiber laser. We use digital oscillograph observed the optical hysteresis in a fiber Fabry-Perot and analyze the optical bistable operating principle, keeping the input light power constant and adjusting the bias voltage V_B gradually. We also discuss this optical bistable device applications in demodulate the fiber Fabry-Perot sensor.

The information and the necessity of engineering monitoring of Dongying Yellow River Bridge are briefly introduced firstly. And then the application of optical fiber sensors in construction supervision, loading test and health monitoring of this bridge is illuminated. The distribution of the internal force monitoring sections, strain and temperature monitoring points and the measuring contents are concisely analyzed. The Encapsulation techniques, installation means and protective measures of optical fiber sensors used in this bridge are also clarified. The author emphasizes the comparison between the theoretical results and actual measuring data derived from optical fiber sensors under some load cases of all the three monitoring phases, which shows that the measuring data is accurate and reliable. Considering its other merits, the author proves that the optical fiber sensors fit the monitoring of large bridge. At last, the outline of health monitoring system integration, especially the accessing of sensors to Interrogator, is showed and the mode of date acquisition, display and analysis, through the long range wireless transmission, is specified.

A blind area occurs when the background in the field of view varying from above-the-horizon to below-the-horizon in air to air detection of the moving target. Factors that effect on the detection blind area are emphatically analyzed in terms of the relative distance between sensors and targets and the velocities and altitudes of the targets. A range capability of IR sensors is modeled and verified by using experiment data, a reasonable result is obtained. At last, some suggestions that would overcome the problem are given.

In this paper, we present a novel design of spectral detection circuit for demodulating fiber Bragg grating (FBG). New type field programmable gate array (FPGA) has been used to make the circuit more compact. We use NIOS-II operating system in FPGA to deal with the real-time data measurement, so needn't any extra micro-programmed control unit (MCU) and other processing electronic devices. The circuit system in this paper, including the charge coupled device (CCD) driver, signal processing, analog-digital conversion and processing of optoelectronic image data, can be widely used in FBG sensor field.

In this paper, we propose a novel scheme of fiber Bragg grating interrogation by use of hybrid fiber optical bistable device (OBD). The OBD is realized in the fiber Bragg grating (FBG) sensing element. Light source is an electronic tuned widely swept ring fiber laser. In this experiment, FBG's are acting as optical intensity modulator and sensing elements at same time. Combined with feedback control circuit, the OBD can be used as an optic-fiber sensor working in digital type through bistable switching phenomenon. We discuss the mechanism of this bistable sensor. Scanning the bias Voltage on PZT, the bistable pulse signal can be counted by circuit that operates in the manner of a pulse-equivalent. If we use 16 bit Digital Analog Converter (DAC), the resolution will achieve 1pm level. High accuracy, high speed and high ratio of signal to noise are the advantages of this scheme.

The general information of the Dongying Yellow River Bridge is introduced. And then the integrated monitoring system including construction supervision system, system of static and dynamic loading test and health monitoring system is designed. The constitution and internal relationship of the system are illustrated and the function of each subsystem is analyzed. The author emphasizes the distribution and installation of optical fiber sensors and demonstrates their merits. Some data acquired by the integrated monitoring system are presented in this paper. For comparison, the corresponding theoretical calculated values are also shown in this paper. The validity ofthe monitoring system is then verified.

Concrete-filled fiber-reinforced polymer (FRP) tube is a type of newly developed structural column. It behaves brittle failure at its peak strength, and so the health monitoring on the hoop strain of the FRP tube is essential for the life cycle safety of the structure. Herein, the optic fiber Bragg grating (FBG) strain sensor was chosen as the strain measuring gauge and embedded in the inter-ply of fibers in the middle height and the hoop direction of the FRP tube. The compressive behaviors of the concrete-filled FRP tubes were experimentally studied. The hoop strain of the FRP tube was recorded in real time using the embedded FBG strain sensor as well as the embedded or surface electric resistance strain gauges. Results indicated that the FBG strain sensor can faithfully record the hoop strain ofthe concrete-filled FRP tubes in compression as compared with the embedded or surface electric resistance strain gauges, and the strain recorded can reach more than 7000με.

The determination of traffic-load effects, which guarantee the safety evaluation results credibility, is an important step for safety evaluation of arch bridge suspenders. Focusing on the traffic-load effects calculation for arch bridge suspenders, firstly, the special feature of traffic-load effects, "sit-specific" "component -specific', was talked about, and the importance of traffic-load effects measured value was pointed out too; secondly, the component of suspenders' load effect monitoring system with fiber sensor was introduced in detail; finally, the theory and process of the maximum value of suspender's traffic-load effects during the rest service period using in-service data was researched. Using this maximum value in safety evaluation, the evaluation result is closer to the real situation.

Fiber Bragg Grating sensors are widely used in the field of optical sensing system for the Structure Health Monitoring (SHM) during the last 10 years. It can be used for monitoring the strain, temperature pressure and some other characters of the structure. In this paper a new kind of surface sticking strain sensor with sensitivity enhanced has been studied and developed. The structure of the sensors is presented and the Ansys software has been used to optimize the structure. A novel theory about how to enhance the sensitivity or widen the scale of the strain sensors based on FBG is introduced too. Based on the theory two types of sensor have been developed. One is the long-scale sensor that is able to monitor the big strain such as crack, the other is the high-precision sensor that is able to monitor the micro strain as O.5,&mgr;&Vegr; , and we conclude the sensitivity enhancing coefficient. As the sensitivity coefficient of bare fiber is 1 .2pm/&mgr;&Vegr; ,the theoretical enhancing sensitivity coefficient of long-scale sensor is K=3.3811 and the theoretical enhancing sensitivity coefficient of high-precision sensor is K=O.58. Then groups of experiments were carried out to validate the theory. The experimental sensitivity coefficient of long-scale sensor is O.35pm/&Vegr; with the coefficient of enhancing sensitivity is K=3.4286. The experimental sensitivity coefficient of high-precision sensor is 1.96pm/&mgr;&Vegr; with the coefficient of enhancing sensitivity is K=0.61 . Comparing the experimental results with the theory results, it proves that the two types of strain sensors can really reflect the strain status and the damage information of the structure, and it is stable and reliable for the practical project.

FBG sensors are more and more accepted in most area of Structure Health Monitoring. However, due to the fact that FBG senses both strain and temperature is monitored simultaneously, temperature compensation for FBG strain sensors of long-term structural monitoring is indispensable. In this paper, based on the FBG's strain and temperature sensing principles, a novel FBG-based sensor for simultaneous dual-measurement of pressure and temperature has been developed. Firstly, in consideration of the requirement of sensors, a novel sensor structure has been designed and its sensing principle is given in details. Secondly, the properties of FBG-based sensor for simultaneous dual-measurement of pressure have been tested by some experiments. Finally, theoretical sensitivity has been compared with that from experiments. The research results show that the FBG-based sensor for simultaneous dual-measurement of pressure has good linearity, repetition, immunity of temperature changes. Such kind of FBG-based sensor for simultaneous dual-measurement ofpressure can be used to practical monitors.

The recent progress in fiber-optic Fabry—Perot interferometric (FPI) sensors at University of Electronics Science & Technology of China (UESTC) and Chongqing University, China, is reviewed in this paper.

One of the most important errors in the IFOG system is polarization noise which is derived from the cross-talking between two individual modes in the fiber. How to decrease polarization noise is one of the key technologies to increase the accuracy of IFOG, especially of high precision IFOG. In this paper, a whole mathematical model of the light path transferring system of polarization maintaining interferometric fiber optic gyroscope (PM-I-FOG) is first established by making use of Jones matrix. Based on the model mentioned above, theoretic analysis on the optic path polarization is made, the influences of each apparatus on polarization noise are discussed, including super-fluorescent fiber source, polarization maintaining coupler, Y-junction waveguide modulator and polarization maintaining fiber ring, which are the most important optical devices in the IFOG. This paper also simulates the polarization noises of the PM-I-FOG. We first break down the optic fiber system and simulate polarization noise of every part mentioned above, then simulate the characters of the whole fiber optic gyroscope system, which is consistent well with the theoretic analysis results. At last we suggest a new technology to restrain the polarization noise, which has reference value in designing high precision PM-I-FOG.

Time-division-multiplexing(TDM) demodulation technique of Fiber Bragg Grating(FBG) sensor arrays based on a tunable pulsed laser is studied. A tunable fiber laser based on a matched FBG is applied, and the wavelengths of the sensing FBGs are obtained by determining the maximum voltages by using a photodiode. The advantages of this scheme include simple structure, high signal-to-noise ratio, and the sensing signals are obtained by determining the maximum voltages.

The line width of pulse laser is key index to some laser applications. Using finite interferences of high accuracy Fabry- Perot etalon we can measure line width of pulse laser. By this method the line width of a single-longitudinal-mode Nd:YAG laser can be obtained. Reflectance of the etalon used reach 99.8%. The finesse was 300. The accuracy of full width of half height(FWHH) was about 2MHz. It is suitable to measure pulse laser with about 10ns pulse width and 100MHz line width with these parameters.

Temperature-insensitive pressure measurement using a single fiber Bragg grating (FBG) based on reflection spectrum bandwidth modulation and optical power detection is proposed. A specially designed double-hole cantilever beam (DHCB) is used to provide pressure induced axial strain gradient along the sensing FBG and further modulate the reflection bandwidth of the grating. The bandwidth modulation immunes to spatially uniform temperature effect and the pressure can be unambiguous determined by reflected optical power measurement, avoiding the complex wavelength interrogation system. The thermal fluctuate of the system is less than 1.2 % F.S. for temperature range from -10°C to 80 °C without any temperature compensation.

A technique for temperature-insensitive displacement measurement using a single fiber Bragg grating (FBG) based on strain-gradient-induced reflection spectrum bandwidth modulation and optical power detection is demonstrated. Linear displacement measurement up to 20mm with displacement resolution of 0.054 mm and thermal stability of < 0.8 % F.S. for temperature range from 20 °C to 80 °C are respectively achieved without any temperature compensation.i

In this paper, an in-line optical fiber spectral analysis system is presented and analyzed, which will be used in the field for measuring the mount of components of oil, water and gas in down-well. Instead of full spectrum analysis of crude oil with a spectroscopy on the ground, this system uses a disperse-spectrum-selecting algorithm, which makes the system in small and compact size and easy to use in down-well. The correlation of the model of disperse wavelengths is equivalent to the model of full range wavelengths and the system measurement accuracy reaches 2 percent by experiments. In addition, the math's model of the system is established, and several regression methods such as Multivariate linear regression (MLR) and Principle components regression (PCR) are discussed and compared in detail. The performance of the system is analyzed with the math's model also. The result indicates that the PCR has a higher accuracy then MLR and 6 channels are enough for practical system used in the field. Besides, an accuracy of less than 1 percent may be got by the results of performance analysis.

A 32 points distributed temperature-sensing system based on the technology of FBG is presented. This system is reliable and the electromagnetic interference is avoided. It suffices to the measurement in harsh environments. The scanning demodulation is used here, which is built on the ground of the central wavelength of the measuring FBG. But the wavelength drifts with the ambience and this drift will cause some errors. Meanwhile, the inherent characteristics of PZT may affect the temperature measurement precision. So we use a thermal etalon reference filter to calibrate the FBG. The system works in the temperature between 0°C and 70°C and the average wavelength drift is 6.4pm. There are nine periods in the work of our temperature measurement system. The first one is the calibration period, in which the FBG is adjusted by the thermal etalon reference filter. The other eight periods are measurement periods. The eight light switches open in turn and are measured. Then the current temperatures of 32 points are obtained.

In this paper, a temperature insensitive fiber Bragg grating (FBG) sensor based on wheel-type structure pressure box is presented. Using two fiber Bragg gratings, within the pressure range of 0~30KN, its linearity and sensitivity reach 99.98% and 13.89N, respectively.

The optical instruments based on the Pockels effect for DC voltage measurement show great advantages in comparison with the traditional type voltage transformers, but the development is impeded due to the presence of the space charge and the charge drift effect in DC voltage measurement. In this paper, the author will analyze the reason of the space drift phenomena and the errors to the measurement accuracy. A method using the octagonal LiNbO₃ crystal with a polyurethane ring with &Vegr;_r=3.4 to suppress the space charge is proposed in the paper. A better result of the electrical field distribution is obtained from the simulation with the ANSOFT software. It can improve the measurement accuracy and sensitivity. At the same time, a new method in which the chopped DC voltage applied to the crystal is also introduced. It can suppress the charge drift effectively with the appropriate frequency. We will show the theoretical analysis and simulation result, and can find the new method can provide a better result, the new instruments are to be more stable and accurate.

The influence of lateral pressure on the propagation constant of grapefruit microstructure optical fibers is theoretically investigated using a full-vector finite element method in this paper. With the different direction of lateral pressure, the change of the propagation constant of grapefruit microstructure optical fibers is different. At present, the report of this aspect has not been found out. The research has great signification in microstructure fiber sensors especially multidimensional optical fiber sensors.

In order to overcome the problems existed in current transducer, A method was proposed to realize large current measurement in high voltage application, which based on the combination of traditional CT and FBG by making use of the high resolution and the perfect electrical isolation strength of FBG. The principles of current transducer and FBG dynamic demodulation were introduced. The dynamic performance of the system was verified with experiments. After signal processing, the repeatability of the system is no more than ±4% without any means of compensation. And the linearity of the system sensitivity is of R² = 0.9958. A new and effective method for large voltage measurement in high voltage field was proposed in this paper.