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Graphene is a candidate material for next-generation high performance transparent conducting film (TCF) to replace indium tin oxide (ITO) materials. However, the sheet resistance of large area graphene obtained by the chemical vapor deposition (CVD) method is higher than other kinds of TCFs. The main strategies for improving the electrical conductivity of graphene films have been based on various doping treatments. AuCl 3 is one of the most effective dopants. In this paper, we investigate the influence of AuCl 3 doping on the conductive stability of CVD-grown graphene. Large area graphene film synthesized by CVD and transferred to glass substrates is taken as experimental sample. AuCl 3 in nitromethane is used to dope the graphene films to improve the electrical conductivity. Another sample without doping is prepared for comparison. The resistances of graphene under periodic visible light irradiation with and without AuCl 3 doping are measured. Results show that the resistances for all samples increase exponentially under lighting, while decrease slowly in an exponential form as well after the light is switched off. The relative resistance changes for undoped and doped samples are compared under 445nm light irradiation with 40mW/cm 2 , 60mW/cm 2 , 80mW/cm 2 , 100mW/cm 2 in atmosphere and vacuum. The change rate and degree for doped graphene are greater than that of undoped graphene. It is evident from the experimental data that AuCl 3 doping may induce conductive unstability for CVD-grown graphene on glass substrate.

The purpose of this study is to investigate the electrical properties of graphene transparent conductive film under visible light irradiation. Sample in the study is chemical vapor deposition (CVD) growth graphene on the surface of copper foils and then transferred to the SiO2 substrate. Three monochromatic visible lights with wavelength of 635nm, 520nm and 450nm representing red (R), green (G) and blue (B) lights are used as irradiation sources. Results show that the graphene resistances increase slowly under light irradiation with all the three different wavelengths, while decrease slowly after the light is switched off. Light irradiation with higher power density will induce larger relative resistance change. When graphene is irradiated at the same density, blue light irradiation may result in the largest resistance change.

Blackbody radiation of the material in high temperature has the great potential to become the light source of an optical fiber sensing system. In this paper, a blackbody radiation cavity is designed and the influence factors of light energy coupling into fiber are analyzed. Fiber Fabry-Perot sensing system based on light source of blackbody radiation has been set up and strain sensing experiment has been carried out. Results show that blackbody radiation is strong enough to support sensing of fiber Fabry-Perot sensors in high temperature, the strain sensitivity is 14.76nm / μe ~ 15.63 nm / μe.

Graphene is an emerging transparent conductor that plays a potential role in organic optoelectronic device. Here we report the fabrication of a polymer light emitting diode employing graphene as anode by solution process. The hydrophobic graphene on PET substrate is modified through interface engineering to obtain a good poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) wettability, which yields a composite electrode with low sheet resistance, high optical transmittance and high work function. The resulting device exhibits good electroluminescence emission and excellent flexibility, which is attributed to our high quality graphene and satisfying interfacial modification. Such polymer light emitting diode employing this green and smart graphene composite anode will promote the development of organic electroluminescent and photovoltaic devices toward a flexible and wearable era.

Steel cable plays an important role in modern infrastructure due to its special characteristics. Because most of structure load is transformed to the cable tension in cable stayed structures, it is very important to monitor cable tension. Being a slender element, Fiber Grating Strain Sensor is sensitive to axial strain and is regarded as a most prospective way to monitor the cable tension. The paper reviews a series of problems of FBG when embedded into the cable, and introduced five different embedded FBG strain sensors. Principle, characteristics, and application states of these five sensor has been discussed in details. The prospective of embedded FBG Strain Sensor for cable tension has been forecast.

The experimental excitations for luminescent glasses are usually monochromatic, but LED chips in applications have an emission bandwidth. In order to investigate the luminescence properties of rare earth ions doped glasses excited by broadband lights, a computational model was presented based on the dependences of excitation wavelengths on emission spectra, chromaticity coordinates and correlated color temperatures (CCTs). The simulations were carried out applying Ce/Tb/Eu co-doped calcium borosilicate glasses as examples. The results show that for the same CCTs, the center wavelengths of chips are different with the excitation wavelengths of fluorescence spectrophotometers.

Rare earth ions doped luminescence glasses are promising phosphor candidates in the fabrication of LEDs in the future due to their specific advantages such as higher thermal stability, higher transparency, compared to current commercial LEDs. While radiation patterns of luminescent glasses are different from current commercial LEDs fabricated by phosphors, luminescent glasses play roles both in emitting light and adjusting light distribution. In order to investigate radiation pattern of luminescent glasses, luminescence physical model of flat glasses doped with single rare earth ion was presented. Process of photons acting on rare earth ions and transporting in the luminescent glasses, and output light distribution from luminescent glasses were analyzed based on violet LED. At last, the simulating of radiation pattern for luminescent glasses based on Monte Carlo ray-tracing method was proved by experiment.

In order to study the influence of road lighting standard on the photometric quantities and energy consumption, road lighting standards of CIE (International Commission on Illumination) and IESNA (Illuminating Engineering Society of North America) were compared in methodology, evaluation criteria and threshold. With the calculation of 20 typical assembly of roads and luminaries, it is found that the luminance is higher in IESNA than that in CIE. On the other hand, energy consumption is much less in IESNA than that in CIE under the same conditions.

If a surface light source is in far-field working condition, the error from using the inverse-square law about intensity and distance should be less than 1%. However, the results of where the far-field begin may be quite different with different error definition. In this paper, by comparing several formulas commonly used for error analysis, the root mean square (RMS) weighted by the sum of intensity at infinity is proposed as the preferred error formula for far-field distances calculation. The relative far-field distances (RFFDs) for LED arrays with different radiation pattern are calculated based on this error definition.

Organic light emitting diode (OLED) is a typical surface source with continuous luminous area. It is important to know its far-field condition since most of lighting designs are based on the far-field characteristics. In this paper, the relative far-field distances (RFFD) for OLEDs with round, rectangular, annular, hemispherical and semi-cylindrical shapes are calculated. The RFFDs for LED arrays with the same shapes are also given for comparison. Results show that the RFFDs for OLEDs are smaller than that of LED arrays with the same shapes and sizes for most situations.

Metal bonding layer seriously affects the strain transfer performance of Fiber Bragg Grating (FBG). Based on the mode of FBG strain transfer, the influence of the length, the thickness, Poisson’s ratio, elasticity modulus of metal bonding layer on the strain transfer coefficient of FBG is analyzed by numerical simulation. FBG is packaged to steel wire using metal bonding technology of FBG. The tensile tests of different bonding lengths and elasticity modulus are carried out. The result shows the strain transfer coefficient of FBGs are 0.9848,0.962 and their average strain sensitivities are 1.076 pm/ μe ,1.099 pm/ μe when the metal bonding layer is zinc, whose lengths are 15mm, 20mm, respectively. The strain transfer coefficient of FBG packaged by metal bonding layer raises 8.9 percent compared to epoxy glue package. The preliminary experimental results show that the strain transfer coefficient increases with the length of metal bonding layer, decreases with the thickness of metal bonding layer and the influence of Poisson’s ratio can be ignored. The experiment result is general agreement with the analysis and provides guidance for metal package of FBG.

To achieve pH detection of multi-points, a new pH sensor based on pH sensitive hydrogel swelling detection by a fiber Bragg grating is proposed. The deflection of a silica membrane due to pH value change induced hydrogel swelling is measured by the center wavelength shifts of a fiber Bragg grating epoxied on the membrane. The relation between center wavelength shifts of the fiber Bragg grating with the hydrogel swelling behavior was studied experimentally. Around 100pm shift of the fiber Bragg grating center wavelength was observed when the pH value was changed from 4 to 7 or from 7 to 10 by using pH standard solutions, which fundamentally proved the feasibility of this method for pH detection.

The double-side patterned sapphire structure was proposed to improve the light extraction efficiency (LEE) of flip-chip GaN-based light-emitting diodes (LEDs). The influences of sapphire substrate thickness, pattern shapes and sizes on LEE were analyzed by Monte Carlo simulation method. Using silicon oxide as mask membrane, double-side patterned sapphires were processed by the standard lithography and the reaction-ion-etching (RIE) technology. The LEDs with patterned sapphire were packaged. The measured light outputs of LEDs verified our predicted effects.

Quantum efficiency measurement of luminescence glasses for high-power white LED was investigated. Luminescence glasses have transparent and anisotropic characteristics, for this reason, we adopted an integrating sphere with 20cm diameter which was connected to a CCD spectrometer to obtain fluorescence spectra of the sample. The relative spectral intensity distribution of the sample under the light source excited was derived from the measured spectra firstly, then using the standard halogen lamp to calibrate the system, we got the absolute spectral intensity distribution, finally the quantum efficiency of the sample can be calculated based on the distribution. It provides an accurate method to measure the luminescence materials’ emission characters.

The Eu 2+ and Dy 3+ co-doped luminescence high silica glass was prepared by combining porous glass preparation and sintering process. The emission spectra and excitation spectra of luminescence glasses were measured. With the excitation of ultraviolet (UV) wavelength of 365nm, there were two emission bands with central wavelength 480nm and 573nm in spectra of samples which presented the near white light luminescence. The energy transfer process from Dy 3+ to Eu 2+ and concentration quench process of Eu 2+ in samples were demonstrated by comparing the relative spectral intensity of emission spectra and excitation spectra. This type of glass might be an adoptable candidate for white LED through an appropriate UV chip excitation.

To acquire the tension of the cable body, a novel measuring method with embedded FBG strain sensor in anchor zone is proposed. This paper describes the design details of the embedded FBG sensor. Based on the analysis of bridge anchor zone, crucial requirements of this sensor are known as package layer structure and the elasticity modulus of the package layer. And the epoxy with micro silicon powder is used as the package layer. Tensile tests are conducted with the tensile testing machine. The result shows that the linearity of sensor is 0.99974, the sensitivity is 2.74pm/N, and the repeatability is excellent. Finally, the sensors are mounted into the cable anchor zone for cable tensile test. The sensor has advantages in linearity and repeatability.

In order to solve the problem of low reliability and strain transmission efficiency for optical fiber sensor packaged with epoxy adhesive, based on the particle diffusion mechanism, a system for metal bonding of optical fiber sensor was developed to research package technology of optical fiber sensor without adhesive. To improve the quality of metal bonding layer, orthogonal test of four levels was designed with four factors which were working distance, driving voltage, feeding rate, pressure of particle field and bonding strength between metal bonding layer and substrate was selected as the criterion of quality of metal bonding layer. The primary and secondary sequences of the influencing factors were acquired by the method of statistical analysis. The optimization results could be instructive to the research on metal bonding technology of optical fiber sensor.

Conventional road lighting luminaries are gradually upgraded by LED luminaries nowadays. It is an urgent problem to design the light distribution of LED luminaries fixed at the former luminaries arrangement position, that are both energysaving and capable of meeting the lighting requirements made by the International Commission on Illumination (CIE). In this paper, a nonlinear optimization approach is proposed for light distribution design of LED road lighting luminaries, in which the average road surface luminance, overall road surface luminance uniformity, longitudinal road surface luminance uniformity, glare and surround ratio specified by CIE are set as constraint conditions to minimize the total luminous flux. The nonlinear problem can be transformed to a linear problem by doing rational equivalent transformation on constraint conditions. A polynomial of cosine function for the illumination distribution on the road is used to make the problem solvable and construct smooth light distribution curves. Taking the C2 class road with five different lighting classes M1 to M5 defined by CIE for example, the most energy-saving light distributions are obtained with the above method. Compared with a sample luminary produced by linear optimization method, the LED luminary with theoretically optimal lighting distribution in the paper can save 40% of the energy at the least.

Vibration frequency method is widely used to measure cable tension of cable-stayed bridges at present. Accurate and efficient identification of cable natural frequencies is one of critical factors in cable tension monitoring. However, it is difficult to efficiently identify accurate natural frequencies in practice. Based on the theory of vibration frequency method, this paper first gives an analysis on how the data sampling parameters affect the accuracy of natural frequencies identification, so as to propose an optimization method of setting sampling parameters. Then, according to the vibration mode of a cable, a new approach, spectrum multiplication, is put forward to help to efficiently identify these frequencies by improving SNR of the vibration spectrum. Field experiments of cable tension monitoring are done at a cable-stayed bridge. The results indicate that measurement accuracy and efficiency are both improved with the optimized sampling parameters and the spectrum multiplication.

Magnetic stress sensor has been considered as the most suitable sensor for measurement of steel cable stress because of its simple structure, low cost and long service life. However, the theoretical foundation for sensor design has never been reported, so it is necessary to study the theory and method of sensor design. Following the magneto-mechanical principle, a theoretical model of magnetic stress sensor is developed. The model indicated that the output of sensor is the function of structural parameters, excitation parameters and stress applied, respectively. A sensor is designed for an engineering steel cable and experiments are done to verify the optimization. Experimental results are in good agreement with the theoretical predictions. Compared to the previous results, the sensor sensitivity is improved by about 4 times, which shows that this model is rational and feasible and the theoretical foundation for optimization is truly of great importance for optimizing the characteristic properties of a sensor.

Since steel cables are widely used to be crucial components in cable-stayed bridges and architectural structures, stress measurement of the steel cables has been given serious attentions. Among the current stress measurement methods, magnetic method seems to be the most potential one, but its application is limited because of the complex theoretical mechanism. According to the magneto-mechanical effect, which demonstrates that magnetization in the ferromagnetic material varies with applied stress, a theoretical model of magnetic method is proposed to perfect the theoretical mechanism. Thus, an equation is derived about the relation between magnetization in steel cables and cable stress. In this model, a magnetic stress sensor is designed, with a smart steel cable as a part of it, and then a cable stress measurement system based on LabVIEW is developed. This method allows new application in non-destructive testing, such as monitoring the conditions of stayed-cable. Considering the impact of the magnetic hysteresis, positive and negative pulsed current excitation was used to demagnetize and decrease the output of heat. This method is applied to the stress measurement of prestressed steel cable in Jiangsu Fasten Nippon Steel Cable Company, the experimental results agree with theoretical assumptions, which indicates that the method is feasible and can improve the mechanical stress measurement.

Bridge structural health monitoring system is a typical multi-sensor measurement system due to the multi-parameters of bridge structure collected from the monitoring sites on the river-spanning bridges. Bridge structure monitored by multi-sensors is an entity, when subjected to external action; there will be different performances to different bridge structure parameters. Therefore, the data acquired by each sensor should exist countless correlation relation. However, complexity of the correlation relation is decided by complexity of bridge structure. Traditionally correlation analysis among monitoring sites is mainly considered from physical locations. unfortunately, this method is so simple that it cannot describe the correlation in detail. The paper analyzes the correlation among the bridge monitoring sites according to the bridge structural data, defines the correlation of bridge monitoring sites and describes its several forms, then integrating the correlative theory of data mining and signal system to establish the correlation model to describe the correlation among the bridge monitoring sites quantificationally. Finally, The Chongqing Mashangxi Yangtze river bridge health measurement system is regards as research object to diagnosis sensors fault, and simulation results verify the effectiveness of the designed method and theoretical discussions.

Performance degeneration of FBG directly affects the long-term stable work of the whole FBG sensing network. According to the formula of FBG refelectd spectrum,the impacts of refraction index modulation depth Δn on refelectd spectrum peak and zero bandwidth are deeply analysed. Based on the theoretical analysis of energy level transition theory, we can find that the temperature shock can make electrons in traps which is of certain distribution of energy overflow,and then cause the reduction of modulation depth Δn , and eventually lead to the performance degeneration of FBG. Conducted the high-low temperature cycling degenerate experiment of FBGs, experimental results show temperature cycling alternate shock will produce accelerated aging phenomenon:after 1000 alternating cycles, the reflection spectrum is almost difficult to identify, the sensing ability is basically lost. Test results prove the correctness of theoretical analysis.

In 2005, Ningbo Design Research Institute of Mapping & Surveying started the development of concepts and an implementation of Virtual Reality Ningbo System (VRNS). VRNS is being developed under the digital city technological framework and well supported by computing advances, space technologies, and commercial innovations. It has become the best solution for integrating, managing, presenting, and distributing complex city information. VRNS is not only a 3D-GIS launch project but also a technology innovation. The traditional domain of surveying and mapping has changed greatly in Ningbo. Geo-information systems are developing towards a more reality-, three dimension- and Service-Oriented Architecture-based system. The VRNS uses technology such as 3D modeling, user interface design, view scene modeling, real-time rendering and interactive roaming under a virtual environment. Two applications of VRNS already being used are for city planning and high-rise buildings' security management. The final purpose is to develop VRNS into a powerful public information platform, and to achieve that heterogeneous city information resources share this one single platform.

In this paper, the light attenuation, fluorescence and absorbance of DOM in Lake TaiHu was mainly studied from July 2001 to December 2002. Results showed that DOM mainly contributed to the attenuation at the ultraviolet, and the best correlation coefficient was at 355 nm. The absorption of DOM could be well described by the exponential decay model. The slope value S, retrieved from absorbance of 350 nm and 440 nm, was 0.0046 nm^-1(SD=0.0015,n=284), far less than the published 0.014 nm^-1. The absorbance at 350 nm (a(350)) well correlated with DOM concentration (R^2=0.673, n=284), and also linearly correlated with fluorescence at 430 nm (R^2=0.497, n=214). The relationship between DOM concentration and fluorescence intensity was also regressed, and showed that it was polynomial.

The Opto-electronic Technology Lab of Chongqing University (OTLCU) has been working on bridge structural health monitoring using fiber optic sensors in the past decade. A remote sensing network based on the Extrinsic Fabry-Perot Interferometer (EFPI) fiber sensor was developed and implemented on several large bridges in Chongqing, China. In this paper, a brief review of the OTLCU's research progress in this field was presented. Contrastive experiments between the EFPI strain sensor and the electrical strain patch (ESP) were introduced. Both internal embedding and surface mounting of the EFPI were studied. The design of the sensing network and two implementation examples were discussed, and some representative monitoring results were given.

A brief review is given of our recent experimental results from in-depth investigations of spin depolarization and underlying physical mechanisms within semiconductor spin detectors based on II-VIs (e.g. Zn(Cd)Se quantum wells) and III-Vs (e.g. InGaN quantum wells), which are relevant to applications for spin-LEDs based on ZnMnSe/Zn(Cd)Se and GaMnN/InGaN structures. By employing cw and time-resolved magneto-optical and optical spin orientation spectroscopy in combination with tunable laser excitation, we show that spin depolarization within these spin detectors is very efficient and is an important factor limiting efficiency of spin detection. Detailed physical mechanisms leading to efficient spin depolarization will be discussed.

As the damage diagnosis of bridge structure is highly nonlinear in nature, it is difficult to develop a comprehensive model taking into account all of the independent variables, such as the structural and environmental properties, using conventional modeling techniques. In this study, a method was introduced for damage diagnosis of bridge structure by integration of BP artificial neural network (ANN) and information fusion based on D-S evidential theory. The basic probability assignment functions for data fusion were constructed according to the demand of the damage diagnosis and the real conditions of the bridge structure. And an application example of the proposed method was demonstrated. The results showed that the integration of the two strategy can remove the shortcoming of BP ANN with remaining of its advantages and promote the identified veracity of the whole diagnosis system.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In order to demodulate frequency division multiplexed optical fiber Fabry-Perot sensors with high accuracy and absolute cavity length, an improved cross-correlation method was presented. As the applying of a special correlating factor in it, the cross correlation function at every sensor's cavity length is a single peak and multiplexed sensors that cavity length is close to each other can be easily distinguished, and segment golden search method was employed to reduce computation and demodulating speed is fast. The multiplexing experiment of two sensors was accomplished with the help of general demodulating system constituted by broadband light source, spectrometer etc. The results showed that the system can demodulate the frequency division multiplexed signal of optical fiber Fabry-Perot sensors, and the least cavity length difference that can be distinguished among multiplexed sensors is less than 6μm and fluctuation of the cavity length is less than 0.073%.

In this paper, the grating light valve (GLV) is presented. A simple method based on multi-beam of light interference theory is put forward to analyze its optical performance. Computer simulation demonstrates that the dimension of its structure and light source have different influence on the diffractive efficiency. According to detecting system, the diffractive efficiency in the OFF state is about 3.8544x10 -16 at the wavelength of 0.66um, about 2.8218x10 -16 at the wavelength of 0.5145um, 1.7846x10 -16 at the wavelength of 0.488um, which should ideally be zero. The result indicates that such method applied in the analysis of the GLV is agreeable and simpler. In order to gain higher diffractive efficiency, the air gap should be reduced.

Dafosi Yangtze River Bridge, completed in August 2001, 1,176 meters long, with the longest main span of 450 meters in Asia in its design period, is one of the key projects of Yu-Qian Expressway and Out-Circle Ring and Round City Highway in Chongqing City. So it is significative to monitor the health of Dafosi Yangtze River Bridge after its completion. A remote health monitoring system is designed for Dafosi Yangtze River Bridge and implemented in the end of 2002. This system includes three subsystems, namely, sensing subsystem, local monitoring subsystem and remote monitoring subsystem. The sensing subsystem can gain the state information of the bridge via sensors, which installed in the key parts of the bridge, such as the fiber-optic strain sensors, the opto-electronic deflection sensors and the temperature sensors. Local sub-system can control all the sensors to collect health information periodically, store and transmit the health data to the remote subsystem via fiber cable. The remote subsystem can analyze and evaluate the health state of this bridge. In this paper, the whole system is introduced, and some monitoring results are presented.

In order to address application problem of fiber optic sensor in concrete, characteristics of concrete was analyzed deeply. Mechanical and metrological characteristics of both bare and packed fiber Fabry-Perot strain sensor were also analyzed in details. Modulus requirement and dimensional requirement of fiber strain sensor for concrete was deduced. A special measure of sleeve was proposed to get rid of drawback of packed fiber Fabry-Perot strain sensor in concrete. Corresponding procedures was also proposed to ensure survivability of the sensors when embedding fiber sensor into a concrete structure. An application example of fiber Fabry-Perot strain sensor network system in the Dafosi Bridge of Yangtze River at Chongqing has been presented to demonstrate the validity of this technique. With help of presented technique, 45 fiber Fabry-Perot strain sensors had been successfully embedded in 5 segments of gird during 9 months construction. The system was put into operation automatically from January 2003. Some typical results recorded by the system were presented. Constructing progress, tardo distortion trend, and temperature dependent fluctuation of gird was revealed in the result.

This paper briefly describes a health monitoring system designed for use on the Dafosi Bridge, the largest cable-stayed bridge across the Yangtze River in western China. The system can be divided into two major components, one for measurement, and one for control and data processing. The measurement system itself includes four sensing subsystems relating to: 1) fiber optic strain sensing, 2) displacement sensing, 3) temperature sensing, and 4) dynamic measurements. The control and data processing system consists of three subsystems: 1) a local computer, 2) a communication subsystem, and 3) a host computer. Sensor outputs are pre-processed locally and sent to the host computer at the management center via the Internet. The system design and implementation are reviewed, and the results of data from two sensing subsystems are presented.

This paper presents a remote state monitoring system designed for and installed on the Hongcaofang Crossroad Bridge in Chongqing, China. In this system, three kinds of sensor, one of which is new, are installed in the bridge to periodically collect strain and deflection information. To control the operation of the sensors, a local computer is integrated in the pier of the bridge. The local computer processes the data from sensors, records processed results, and sends the state information to a host computer through the local Public Service Telephone Network (PSTN) using an ordinary modem. At the other terminus, the host computer receives and analyzes the data, stores the history information, queries the health state, and extracts abnormity information regarding the bridge. With the interconnect technology available through the PSTN, real time state information can be obtained on command in the monitoring room far from the bridge. This on-line monitoring system operated on the Hongcaofang Bridge for over two years. This paper reviews some of the more important results regarding both the strain and the two-dimensional deflection of the bridge, and discusses the experience gained thus far.

Based on discrete-ordinate-method radiative transfer in multiple scattered theory, the solar direct and scattering radiation with observation band (0.29~3.0 µm) on 5 layers have been computed using the retrievals of Tiros Operational Vertical Sounder (TOVS) in clear/cloud sky over southeast China. The errors between the computed values of solar direct and scattered radiation derived from TOVS and that from radiosond data are then given. The purpose of this research is to show if the satellite measurements (TOVS DATA) can be directly used to estimate spatial distribution of solar radiation with observation band.

The principle, capabilities, advantages and limitations of the optically detected magnetic resonance (ODMR) technique will be briefly described. The ability of the ODMR technique to provide important information on physical properties of semiconductor thin films and layered structures will be highlighted. These include chemical identification, electronic and geometric structures of defects, carrier recombinations, etc. The important role in providing valuable feedback for improvement of growth process and in engineering material properties for device applications will be demonstrated. Representative cases from Si/SiGe- and InP- based structures grown by molecular beam epitaxy will be discussed as examples. The most recent progress, on-going efforts and prospects in achieving unprecedently high spectral, time and spatial resolution of the ODMR technique, meeting the demands and challenges raised by the increasing miniaturization of future electronic and optoelectronic devices, will also be outlined.

The development of fiber optic sensors for safety control of civil structures is over viewed in this paper. Main principle of fiber optic sensors such as Fiber Bragg Grating sensors, fiber F- P sensors and low coherent fiber Michelson interferometer is discussed. Some typical applications of fiber optic sensors in bridges, buildings and etc. are provided. The tendency of fiber optic sensors is forecasted.

An optical waveguide sensing method is proposed for monitoring the corrosion of steel in reinforced concretestructures. The method depends on the absorption oflight in the waveguide by a metallic cladding which is appliedat a particular location. When this cladding is exposed to a corrosive environment, it degrades, and the opticalwaveguide output increases. This sensing principle is analyzed, as is an electrochemical method proposed to laythe metal film onto the waveguide. In order to establish a reliable procedure for electroplating an Fe-C alloy filmonto fused silica, we first investigated the use of a planar waveguide substrate, and electroless plating of silver ontoSiO was introduced as the electroplating cathode. After analysis, an optical fiber version of the corrosion sensorwas then fabricated using the electrochemical method. The sensor was intensively corroded with HNO, NSS, andsimulated concrete pore solution. The experimental results are presented and to some degree coincide with theory.Keywords: corrosion monitoring; fiber optic corrosion sensor; smart structures

Based on the theory of multiple scattering of radiation in a plane parallel atmosphere, solar direct and diffuse radiations in various spectral bands at different heights have been computed with the discrete ordinate algorithm using the radio observations, radiative observations, and retrieval from the TIROS/N operational vertical sounder (TOVS). The LOWTRAN program is also used for computation of radiative transfer parameters such as optical thickness. The computed radiation are then used to set up the statistical relationship with satellite observations in the VIS and IR. The results have shown that the correlation coefficient is up to 0.9 in the upper atmosphere and 0.70-0.85 in the lower atmosphere. Thus satellite observations in the VIS and IR channel may be used to estimate the solar direct and diffuse radiations in a cloudless atmosphere.

The surface radiation budge is an important essential radiation parameter. In this paper, the basic relation between the measurements from the visible/IR channel in satellite and the surface radiation budgets has been derived. According to this relation, some useful models of estimating the surface radiation budget are obtained by the observational data from the visible/IR channel in GMS satellite and the observational data from surface radiation budget stations. With the most excellent one of these models, the distribution of radiation budget across China is obtained by the interpolation method. Compared to the actual observational data, this distribution has a better consistency with the actual result, which shows that this model is very effective in estimating the radiation budgets in China.

In distributed optical fiber temperature measuring system, temperature information is involved in Raman scattering light. In order to separate weak Raman scattering light from other stronger, adjacent scattering light, interference filter is commonly used and must be specially designed and fabricated. A group of fine tunable optical interference filters is presented to avoid the special procedure of filter. The principle of the filter group is discussed. The experimental results is presented. Results show that the accuracy of central wavelength is upgraded from +/- 0.8nm to +/- 0.2nm and the bandwidth is narrowed to the half of original filter's.

With the rising cost of building and replacing civil infrastructure systems, as well as increased demands placed on such system, has come an elevated concern about monitoring their health. This requires the development of smart sensors suitable for real-time and in-situ measurement of concrete-based structures. Many smart sensor have been investigated to meet this requirement in the past several years. This paper describes some of the recent research activity undertaken at the Center for Intelligent Structures at Chongqing University regarding both optical sensor and monitoring strategies aimed at civil infrastructure damage assessment and integrity evaluation. Several experiments and sensor applications are also briefly described.

A method for detecting interstory drift and chord drift in buildings is proposed and demonstrated based on the motion of a laser generated cross hair in free space. The beam is projected form ceiling to floor onto an arrangement of four position sensitive detectors, each with two separate outputs. Every lateral displacement and relative angle between ceiling and floor gives a unique set of detector voltages, so that as floors shift with respect to one another due to wind and earthquake loads, voltages vary, the new beam axis location is determined, and the 3D interstory drift, velocity, and acceleration can be obtained. Experimental results show excellent linearity and sensitivity of roughly 10 microns for lateral displacement and 0.02 degrees for relative rotation between ceiling and floor.

This paper reports the research of a Fiber Optic Corrosion Sensor (FOCS) fabricated by electroplating an Fe-C alloy film onto an optical fiber core within the sensing region. Fabrication of the sensing film involves removal of the cladding, metallization of the optical fiber core, and electroplating of the Fe-C alloy layer. The initial results show that the sensor output power increases by about 35 percent when the film is corroded with the sensor of the film passivated, and that the time taken to rise to maximum output power is prolonged by almost 3 times, compared with that for non-passivated film. These result demonstrate the feasibility of using optical fiber corrosion sensors for monitoring corrosion of steel in civil structures.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Fourier transform technique for moire deflectogram is proposed to automatically map the phase object. The moire deflectogram is generate by conventional deflectometer and is analyzed by means of Fourier transform algorithm, in which the fringe phase is retrieved and phase object message is obtained automatically. Theoretical analysis, simulation calculation and application example are presented.

In this paper, a fiber optic modal domain sensor system for the evaluation of bridge pavement samples is developed. The sensing principle based on intermodal interference is analyzed. The method of embedding and surface-mounting sensors within or on the concrete pavements is presented, and the test results of the pavement samples are given. The experiments show that the fiber optic sensor system is an effective means for evaluating concrete pavements and monitoring the cracks and damage of concrete structures in-situ.

A new kind of practical fiber optic flow sensor system is studied in this paper. Combining the matured technology of conventional Rhodes flowmeter with advanced technology of fiber optic sensor, we proposed a practical scheme of hybrid fiber optic flow sensor system which remains the advantage of high accuracy of conventional Rhodes flowmeter, improves its characteristic in low speed and has large measuring range well over that the magneto-electric Rhodes flowmeter has. Thanks to the advantages of isolation, nonconduction and immune from electromagnetical interference, fiber optic flow sensor has steady output signal and can work without electricity on worksite. So it is used specifically in hazardous environments such as oil depot for oil and chemicals measuring. In this paper, the working principle of the flow sensor is introduced, the structure of the fiber optic Rhodes wheels rotary displacement probe is designed, and the signal-processing system is described. Finally the in-situ test of the system in the oil terminal of Zhanjiang Harbor in China is introduced.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Fluorescence properties of stomach tissues have been investigated to determine whether malignant specimens can be discriminated in vitro. Differences between normal and tumor tissues are found that concern both the intensity distribution and spectral shape of the autofluorescence emission. According to the distinctions tumor tissues would be differed from the normal tissues. The resulting spectra could be differentiate histologically stomach abnormal tissues from normal tissues with a sensitivity and specificity value of 90 percent and 92 percent. Furthermore, fluorescence spectra from human stomach normal and malignant tissues have been measured in real time in vivo.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.