Proceedings Volume 8191

International Symposium on Photoelectronic Detection and Imaging 2011: Sensor and Micromachined Optical Device Technologies

Yuelin Wang, Huikai Xie, Yufeng Jin
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Proceedings Volume 8191

International Symposium on Photoelectronic Detection and Imaging 2011: Sensor and Micromachined Optical Device Technologies

Yuelin Wang, Huikai Xie, Yufeng Jin
View the digital version of this volume at SPIE Digital Libarary.

Volume Details

Date Published: 25 August 2011
Contents: 2 Sessions, 88 Papers, 0 Presentations
Conference: International Symposium on Photoelectronic Detection and Imaging 2011 2011
Volume Number: 8191

Table of Contents

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Table of Contents

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  • Front Matter: Volume 8191
  • Sensor and Micromachined Optical Device Technologies
Front Matter: Volume 8191
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Front Matter: Volume 8191
This PDF file contains the front matter associated with SPIE Proceedings Volume 8191, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.
Sensor and Micromachined Optical Device Technologies
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Development of infrared FPA using bimaterial microcantilever arrays
Yufeng Jin, Xiaomei Yu
An optical-readout bimaterial microcantilever-type infrared detector improving both IR absorption and pixel uniformity is proposed. A Focal Plane Array (FPA) of 128×128 pixels was fabricated using 4-inch silicon Micro-Electro Mechanical System (MEMS) processes. The FPA design and process development are discussed and the Scanning Electron Microscope (SEM) photos and imaging results of the FPA are presented. The Noise Equivalent Temperature Difference (NETD) of the proposed device was measured to be 200mK by a gray level change method and the time constant was calculated to be ~15 ms under a 10 mTorr pressure.
Fabrication of ultrathin silicon PIN detector
Min Yu, Xianshan Dong, Ying Li, et al.
Ultra-thin silicon PIN detectors are applied widely in nuclear physics experiments and space exploration. It is used in ΔE-E telescope system as the ΔE detector to detect the energy loss of high energy particles so that to identify the charge and mass of the particle. The ΔE detector is required to be very thin(<50μm) in order to let low energy particles to go through the ΔE detector and enter the followed E detector. The fabrication of ultra-thin silicon detector is very difficult and challenging due to the fragility of the ultra-thin silicon membrane considering that the area of the detector is required to as large as 10~100 mm2. Several different technologies have been proposed to fabricate the ultra-thin silicon PIN detector, such as back side locally thinning of the high resistivity silicon wafer, application of the SOI technology or wafer thinning and bonding technology. The monolithic ΔE-E detector telescope technology has also been proposed. In this talk we review the development of ultra-thin silicon PIN detector technology including our research work.
Simulation and experiment of the static FTIR based on micro multi-step mirrors
Jingqiu Liang, Zhong-zhu Liang, Jin-guang Lv, et al.
In recent years, Fourier transform spectrometer (FTS) with small size and low mass is required in many applications with growing need for real-time and small platform spectral detection. In this paper, a micro Fourier transform infrared spectrometer (μFTIR) based on spatial modulation mode was designed. This spectrometer has the advantages of high stability and simplified configuration. It also promises optical path differences (OPD) with high precision, as MOEMS technology is used in manufacturing the key components. The simulation and the experiments with regard to this FTIR configuration have been done. Firstly, the diffraction effect of the micro multi-step mirrors (MMSMs) is studied. We discuss the influence to the reversed spectrum by different mirror widths and different diffraction distances. Secondly, we simulate and analyze the influence of the source solid angle to the spectral resolution. Thirdly, we set up the theoretical model of the collimation error which is mainly from the defocus of the optical system and analyze the result caused by the collimation error. Fourthly, a new discrete Fourier transform arithmetic using least-squares cosines progression (LSCP) is proposed which can reconstruct the spectrum with nonuniform sampled signals. Finally, the MMSMs are fabricated used the MOEMS technology and the structural parameters are tested.
MEMS-driven diffraction gratings for rapid scanning of laser beams with very high optical resolution
Guangya Zhou, Yu Du, Kelvin K. L. Cheo, et al.
Miniaturized low-power, high-speed scanners are tremendously useful in a variety of applications. Besides MEMS micromirrors, the in-plane vibratory grating scanner is a development in this area which possesses several unique features. The in-plane scanning mechanism minimizes the dynamic non-rigid-body out-of-plane deformation of the mirror surface, allowing for higher-resolution displays. The dispersive element permits splitting the incoming beam into its constituents for analysis. Coupling a grating platform to an in-plane moving structure is also useful for real-time motion measurement which would otherwise be difficult to pick-up. The past developments till the current design are explored in this paper. Possible alternative applications besides image display, for example spectral imaging and realtime motion sensing are also described.
Quantum dots light emitting devices on MEMS: microcontact printing, near-field imaging, and early cancer detection
Ashwini Gopal, Kazunori Hoshino, John X. J. Zhang
Controlled patterning of light emitting devices on semiconductors and micro-electro-mechanical systems (MEMS) enables a vast variety of applications such as structured illumination, large-area flexible displays, integrated optoelectronic systems and micro-total analysis systems for real-time biomedical screening. We have demonstrated a series of techniques of creating quantum dot-based (QD) patterned inorganic light emitting devices at room temperature on silicon (Si) substrate. The innovative technology was translated to create localized QD-based light sources for two applications: (1) Three-dimensional scanning probe tip structures for near field imaging. Combined topographic and optical images were acquired using this new class of "self-illuminating" probe in commercial NSOM. The emission wavelength can be tuned through quantum-size effect of QDs. (2) Multispectral excitation sources integrated with microfluidic channels for tumor cell analyses. We were able to detect the variation of sub-cellular features, such as the nucleus-to-cytoplasm ratio, to quantify the absorption at different wavelength upon the near-field illumination of individual tumor cells towards the determination of cancer developmental stage.
Optical communication components based on non-silicon MEMS technology
Xu-han Dai, Yi Huang, Gui-fu Ding, et al.
This paper presents non-silicon MEMS technology for fabrication of Optical communication components. Both pure non-silicon and combined micromachining technologies were realized. For the pure non-silicon surface micromachining technology, the Ni and permalloy were chosen as the structure layer; the photo resist and copper were chosen as the sacrificial layer. Based on the technology, the micro-hinge was realized. It may find ample application in the out-of-plane microstructure, which is common in free-space optical transmission. As an example, a MEMS variable optical attenuator is introduced. It consisted of a hinged shutter to adjust the optical power transmission between the input and output optical fibers. For the combined micromachining fabrication, the electroplating was combined with the traditional bulk silicon technology to realize some unique structure for passive alignment. For example, we had developed the micro-fabricated nickel clamps for packaging of optical fibers in photonics devices. Compared with the all silicon scheme, this approach only involves one additional sputtering, photolithography, and electroplating process.. The presented non-silicon micromachining process offered more choice of material and facilitated the implementation of structure innovation.
Study of the bullet position measuring model with six light screens
Bin Feng, Xiu-Hua Shi, Zhi-Qiang Kang
The test of firing dispersion needs to measure the bullet position on a target. But the trajectory ot the bullet requires normally incident on the scheduled panel in the conventional automatic location target measuring device, so it is more difficult to promise completely. The large errors of measure result will be got when trajectory and panel are not vertical. A kind of multiple light screens arranging structure is presented in this paper for resolving this problem. The method of space analytic geometry is used to solve the ballistic equation of bullets, which go through the target area with arbitrary direction. Accordingly the coordinates of the point of intersection is got, which trajectory with specified screen.The measuring principle is givern, and the measuring precision is analyzed.
Research on an in-situ vision inspection system of the nick depth of easy open end
Liu Huang, Yong-ming Xu, Ying-jun Zheng, et al.
The size and shape of the nick of easy open end are key parameters in ensuring high packaging quality, but the present detection methods are still rather primitive. To solve this problem and realize automatic detection of easy open end in industrial production sites, an in-situ vision inspection system based on light-section principle is developed to measure the nick depth quickly and accurately, which utilizes self-developed image acquisition and processing software and uses an automatic blocking and threshold segmentation algorithm based on projection method. Experimental results show that the inspection system has realized the positioning accuracy of ±1mm in X and Y directions, and the depth of field in the system is 700μm. The vibration characteristics of the system is tested by using shaking table with vibration frequency of 6.7Hz and amplitude of 360μm to simulate production environment of easy open end, which verifies that the system can work in similar production environments.
Highly sensitive rotation sensing based on orthogonal fiber-optic structures
Yi Yang, Zi-nan Wang, Lian-yu Xu, et al.
In traditional fiber-optic gyroscopes (FOG), the polarization state of counter propagating waves is critically controlled, and only the mode polarized along one particular direction survives. This is important for a traditional single mode fiber gyroscope as the requirement of reciprocity. However, there are some fatal defects such as low accuracy and poor bias stability in traditional structures. In this paper, based on the idea of polarization multiplexing, a double-polarization structure is put forward and experimentally studied. In highly birefringent fibers or standard single mode fibers with induced anisotropy, two orthogonal polarization modes can be used at the same time. Therefore, in polarization maintaining fibers (PMF), each pair of counter propagating beams preserve reciprocity within their own polarization state. Two series of sensing results are gotten in the fast and slow axes in PMF. The two sensing results have their own systematic drifts and the correlation of random noise in them is approximately zero. So, beams in fast and slow axes work as two independent and orthogonal gyroscopes. In this way, amount of information is doubled, providing opportunity to eliminate noise and improve sensitivity. Theoretically, this double-polarization structure can achieve a sensitivity of 10-18 deg/h. Computer simulation demonstrates that random noise and systematic drifts are largely reduced in this novel structure. In experiment, a forty-hour stability test targeting the earth's rotation velocity is carried out. Experiment result shows that the orthogonal fiber-optic structure has two big advantages compared with traditional ones. Firstly, the structure gets true value without any bias correction in any axis and even time-varying bias does not affect the acquisition of true value. The unbiasedness makes the structure very attractive when sudden disturbances or temperature drifts existing in working environment. Secondly, the structure lowers bias for more than two orders and enhances bias stability for an order higher (compared with single axis result), achieving a bias stability of 0.01 deg/h. The evidences from all aspects convincingly show that the orthogonal fiber-optic structure is robust against environmental disturbance and material defects, achieving high stability and sensitivity.
Application of an optical DPSK detector in ultra-high speed data acquisition system
Hao Guo, Shao-jing Su, Jing Zhou, et al.
Recently, differential phase-shift keying (DPSK) has become one of the considerable issues in the study of transmission formats over high-speed optical communication systems. In this paper, taking the rate of 10Gbit/s as an example, a balanced optical DPSK detector based on Mach-Zehnder delay interferometer (MZDI) is developed. With this detector as signal receiver, a data acquisition system which can receive 10Gbit/s optical DPSK signal is designed. Finally, the testing method and the experimental result of the optical data acquisition system are given. Result shows that the optical DPSK signal at 10Gbit/s can be successfully acquired by the system, with bit error rate (BER) less than 10-12.
Characteristics of PCF filled with large thermo-optic coefficient liquid
Zhe Wang, Li Wang, Tiesheng Wu, et al.
In the paper, the characteristics of the hollow-core photonic crystal fiber (PCF) filled with large thermo-optic coefficient liquid were calculated and analyzed using the Full-vector plane wave method (FVPWM). Two filling ways were used to: One is only filling the hollow core of fiber, another is filling all the air holes of the fiber. The change of the PCF' s effective refractive index was investigated by changing the size, queueing discipline, distance of air holes, and filling the air holes with gas and liquid etc. The electromagnetic theory, the character of transmitting light and the applications of PCF have researched.
Potted fiber optic sensor coil by novel adhesives for high-stability FOG
Congzhi Bi, Guofei Sun, Yanji Wu, et al.
A sensor coil for a fiber optic gyroscope is fabricated and potted by a novel adhesive. The kind of adhesive can match to the outer jacket of polarization maintaining fiber (PMF) to improve the potting uniformity of the whole coil, so that it could contribute to reduce the temperature-induced strain and the strain differential between the clockwise and counterclockwise-wound portions of a symmetrically-wound fiber coil, i.e. temperature-dependent Shupe stress effect. The adhesive is a compound comprising acrylate and polyurethane, which can avoid the non-wetting problem resulting from the two different types of compounds. The adhesive is a low viscosity system which exhibits a prolonged work life, an adjustable hardness. Specially, the potting compound with a low glass transition temperature (Tg), down to the lower temperature -60°C, remain stable modulus during thermal cycling between -40°C and 60°C. The potted fiber optic sensor coil with a smooth surface is clear and regular due to the completely curable adhesive. The extinction coefficient of the fiber optic sensor coil can reflect the additional stress produced by the adhesives through comparing before potting with after potting. the potted fiber optic sensor coil shows excellent bias characteristics and temperature performance.
Research on neutron-irradiated 6H-SiC crystals by x-ray diffraction
Wei Zhu, Yongfeng Ruan, Pengfei Wang, et al.
Single crystal SiC has become more and more important semiconductor material due to its excellent physical and chemical properties. The present paper reports a study of characteristics of unirradiated and irradiated SiC. 6H-SiC single crystals were irradiated at approximately 60-80oC to a neutron fluence of 5.74×1018 n/cm2.The radiation damage and the defect recovery in the single crystals were investigated by X-ray diffraction meter. The experimental observation on diffraction peaks of different crystal faces shows that there are serious damages in the neutron-irradiated 6H-SiC crystals and amorphization appears at one of the measured planes. The restoration of radiation damage occurred during the isochronal annealing process, and the recovery feature is depended on annealing temperature. The X-ray diffraction data show that the radiation damages remained almost unchanged below the temperature of 600oC, and the healing process got more and more obvious while the annealing temperature is beyond 600oC. It is found that beyond 600oC the crystal structure gradually reordered and the FWHM of face (006) peak reveals a linear recovery behavior with increasing annealing temperature. High-temperature detector can be made according to the linear recovery law in order to achieve the measurement of the high-temperature environment.
The development and property research on reflective intensity modulation fiber optic acoustic sensor
Hui Wang, Rencheng Zhang, Jianhong Yang, et al.
In order to improve the overall performance of reflective intensity modulation fiber optic acoustic sensor, the fiber-optic sensing probe was optimizing designed. Through constructing experimental platform, the sensitivity and frequency characteristics of the sensor were tested. The experimental results suggest that the sensor's sensitivity is found to be 550mV/Pa, and the measurement range lies within 50Hz ~ 10000Hz, which meets the requirements of the project indicators. Meanwhile experimental results show that the structure of fiber-optic sensing probe is simple reasonable designed and has strong practicability.
An unsymmetrical design of IMU for attitude measurement of land vehicles
Huaqiang Zhang D.V.M., Yan Zhao, Yu Chen
Focusing on the determining attitude of land vehicles which equipped with antenna platform for communication satellite, the mathematical model of the integrated navigation system of Strapdown Inertial Navigation System(SINS) and Global Positioning System(GPS) has been built at first. Then the observability of the attitude errors of the integrated navigation system has been concluded to be very weak, and the observability of the heading error is weaker than the horizontal attitude's. Due to this characteristic and the requirement of miniaturization and low-cost, a new inertial measurement unit (IMU) structure has been designed, which comprises three gyros and three accelerometers. Two MEMS gyros were installed on the horizontal plane, and a high degree of accuracy fibre optical gyro was installed in the vertical direction. During navigation period, the Kalman filter is used for calculating the navigation information. Both the theoretical analysis and simulation results show that the new unsymmetrical design of IMU can improve the precision of heading significantly, and when this IMU is integrated with GPS, the attitude precision can meet the requirement of the antenna platform control.
A novel method of freeform surface grinding with a soft wheel based on industrial robots
Sheng-chun Sha, Xiao-ling Guo
In order to meet the growing demand for high-quality images, optical elements of freeform surface are more and more applied to imaging system. However the fabrication of freeform surface optical elements is much more difficult than that of traditional spherical ones. Recent research on freeform surface manufacture often deals with precision machine tools which have limitations on dimensions and are always expensive. Little has been researched on industrial robots. In this paper, a new method of freeform surface grinding based on industrial robots was found. This method could be applied to both whole surface grinding as well as partial surface grinding. The diameter of lenses to be ground would not be restricted to the machine tool's size. In this method a high-speed-rotating soft wheel was used. The relation between removing amount and grinding time which could be called removing function was established and measured. The machining precision was achieved by means of controlling the grinding time instead of the machine tool or industrial robot itself. There are two main factors affecting the removing function: i).rotating speed of the soft wheel; ii).pressure between the wheel and the work piece. In this paper, two groups of experiments have been conducted. One is the removing function tested at constant rotating speed while under different pressure. The other is that tested under a certain pressure with variable speed. Tables and curves which can show the effect of speed and pressure on the removing efficiency have been obtained. Cause for inaccuracy between experiment data and calculated result according to the theory and the non-linearity in the curves was analyzed. Through these analyses the removing function could be concluded under certain condition including rotating speed and pressure. Finally several experiments were performed to verify the appropriateness of the removing function. It could also be concluded that this method was more efficient in comparison with traditional grinding technology particularly in the aspect of partial surface grinding. This paper also brought up a new idea that this method could be combined with other freeform surface grinding technics to realize a more flexible, efficient, reliable and economical type of optical fabrication. It would become a potential technic especially for partial optical surface grinding and repair.
The use of 2D and 3D WA-BPM models to analyze total-internal-reflection-based integrated optical switches
Pengfei Wang, Gilberto Brambilla, Yuliya Semenova, et al.
The well known beam propagation method (BPM) has become one of the most useful, robust and effective numerical simulation tools for the investigation of guided-wave optics, for example integrated optical waveguides and fiber optic devices. In this paper we examine the use of the 2D and 3D wide angle-beam propagation method (WA-BPM) combined with the well known perfectly matched layer (PML) boundary conditions as a tool to analyze TIR based optical switches, in particular the relationship between light propagation and the geometrical parameters of a TIR based optical switch. To analyze the influence of the length and the width of the region in which the refractive index can be externally controlled, the 3D structure of a 2x2 TIR optical switch is firstly considered in 2D using the effective index method (EIM). Then the influence of the etching depth and the tilt angle of the reflection facet on the switch performance are investigated with a 3D model.
Temporal shaping of the femtosecond pulse by micro-gratings array
Yongming Nie, Xiujian Li, Wenhua Hu, et al.
A temporal femtosecond pulse shaping device, based on all-diffractive method, is designed for arbitrary waveform generation. The key components of the device are micro-gratings arranged in line. By changing the period and phase pattern of each grating, the diffraction angle, phase and amplitude of the first order diffraction light can be modulated. Experimental results are consistent well with simulation results, which indicate that arbitrary temporal waveforms can be gained by using micro-gratings array. Additionally, the configuration of the device allows for multiple outputs and can operate over a large wavelength range from ultraviolet to infrared pulse.
Measuring the fluid velocity with the self-mixing speckle of the erbium-doped fiber ring laser
Li Ma, Yaqun Guo, Daofu Han
The measuring method of the fluid velocity is studied by self-mixing speckle interferometry. A measuring system making up of the ring erbium-doped fiber laser is devised to achieve the information of the fluid velocity. Through Injection- Seeded Erbium-doped fiber ring laser transcendental equation, an equation about the fluid velocity and laser power modulated by self-mixing speckle can be inferred. The relationship between average frequency of the self-mixing speckle signal and the fluid velocity is analyzed, and that how does the average energy spectrum density change with the fluid velocity is studied. In experiments, a suitable signal processing method can be chosen with the grade of the velocity. The experiment is indicated that it is the linear between self-mixing speckle signal and the fluid velocity. The result of the experiments is indicated that self -mixing speckle metrology based on the erbium-doped fiber ring laser can be applied to real time detection of the fluid velocity.
Fabrication of high-efficiency ultraviolet blazed gratings by use of direct Ar2-CHF3 ion-beam etching through a rectangular photoresist mask
In ultraviolet spectroscopy, there is a constant need to improve the diffraction efficiency. A blazed grating can concentrate most of the light intensity into a desired diffraction order, so it is the optimum choice among gratings of different kinds of profile. As the operating wavelength of most UV spectral applications is less than 200 nm, the required blaze angle is small; groove irregularity and surface roughness of nanometer magnitude can cause a significant loss of diffraction efficiency. Therefore, it is important to control the groove shape precisely , especially the blaze angle and the apical angle. We have presented a direct shaping method to fabricate EUV blazed gratings by using an ion-beam mixture of Ar+ and CHF2+to etch K9 glass with a rectangular photoresist mask. With this method, we have succeeded in fabricating well-shaped UV blazed gratings with a 1200 line/mm groove density and 8.54° blaze angles and 1200 line/mm groove density and 11.68° blaze angles, and the metrical efficiency is about 81% and 78%. The good performance of the gratings was verified by diffraction efficiency measurements. When one uses the etching model, the conditions on the ion-beam grazing incident angle and the CHF3partial pressure should be noted. Besides, since the etched groove shape depends on the aspect ratio of the photoresist mask ridge, if we wish to fabricate larger gratings with this method, we must improve the uniformity of the photoresist mask before ion-beam etching.
Design optimization and implementation of a miniature optical coherence tomography probe based on a MEMS mirror
Donglin Wang, Linlai Fu, Jingjing Sun, et al.
Optical coherence tomography (OCT) provides non-invasive cross-sectional imaging capability and high resolution, but it has very limited applications inside human body because of the stringent size requirements for accessing the internal organs. Micro-Electro-Mechanical Systems (MEMS) is an emerging technology that can make devices with small size and fast speed. This paper reports the design optimization of a MEMS mirror-based miniature OCT probe. The probe consists of three main parts: a GRIN lens module (1.3 mm in diameter), a MEMS mirror (1.7 mm x 1.55 mm), and a stainless steel mount. A special assembly holder is designed for easy placement of parts and accurate optical alignment and real-time monitoring of optical alignment and electrical characteristics is also used to the assembly process. Code V is used for the optical design and analysis. Simulation shows that the changes of the spot size and focal length are within the acceptable range when the distance between the optical fiber and the GRIN lens varies less than 0.1 mm. The fiber may tilt as much as 2.5 degrees without any considerable change of the spot size and working distance. The maximum tolerance to the lateral shift between the fiber and GRIN lens is about 0.1 mm.
Study of surface plasmon resonance of Au nanoparticles coated with dielectric layers
Jia-Yu He, Chan-yan Huang, Ning Dai, et al.
In this work, atomic layer deposition (ALD) was used to deposit different thickness layers of Al2O3 on Au nanoparticles fabricated by thermal annealing of Au thin films. The effects of the Au-coated Al2O3 layer thickness variation to local surface plasmon resonance (LSPR) in gold (Au) nanoparticles was investigated using transmission surface plasmon resonance (T-SPR) spectroscopy. Thermal annealing of ultrathin films of Au sputtered on transparent substrates can get a dispersed metal particles system which exhibit transmission spectra showing an extinction band attributed to localized surface plasmon resonance (LSPR). The particles prepared by thermal annealing are much more like elliptical rather than sphere. The dielectric medium layer Al2O3 was deposited on these Au particles with the thickness from few nanometers to tens of nanometers by ALD. We found that All the LSPR peak positions of particles on different substrates red shifted as the thickness of deposition layer increase, but the LSPR red-shift effect of particles on alumina substrate was much more remarkable than particles on glass substrate. The results in this paper show that it is a very continent method to manipulate LSPR position which is a profound useful effect in solar cell application by controlling the deposition layer thickness on particles prepared by thermal annealing on suitable substrate.
Calibration of diffractive micromirror arrays for microscopy applications
Dirk Berndt, Jörg Heber, Steffen Sinning, et al.
We report on our investigation to precisely actuate diffractive micromirror arrays (MMA) with an accuracy of λ/100. The test samples consist of analog, torsional MEMS arrays with 65 536 (256x256) mirror elements. These light modulators were developed for structured illumination purposes to be applied as programmable mask for life science and semiconductor microscopy application. Main part of the work relies on the well known characterization of MEMS mirrors with profilometry to automatically measure and approximate the MMA actuation state with high resolution. Examples illustrate the potential of this strategy to control the tilt state of many thousand micromirrors within the accuracy range of the characterization tool. In a dynamic range between 0 and >250 nm the MMA deflection has been precisely adjusted for final MMA application in the deep-UV - VIS - NIR spectral range. The optical properties of calibrated MMAs are tested in a laser measurement setup. After MMA calibration an increased homogeneity and improved image contrast are demonstrated for various illumination patterns.
Fatigue research for rotating mirror of ultra-high speed camera through numerical analysis and experimental methods
Chun-bo Li, Chun-hui Yu, Chun-ping Liu, et al.
It is the major failure mode of high-cycle fatigue for rotating mirror. Test methods for fatigue are commonly used in researching the fatigue life of rotating mirror, but not practically. In this paper, numerical analysis and experimental were used for researching the fatigue life of rotating mirror. With the finite element analysis software ANSYS, a static strength about the rotating mirror was calculated at first and the results of stress from computing were imported into the nSoft as the cyclic stress load spectrum for analyzing the fatigue life of rotating mirror. According to the S-N curve of rotating mirror which defined by the material properties, the Miner linear cumulative damage law and the Goodman Mean Stress Correction Model, the fatigue life of rotating mirror was calculated by nSoft. It shows that the fatigue failure of rotating mirror does not occur under the speed of 3x104 rpm, because no node is damaged within the threshold of infinite numerical cycles in that speed. Then a fatigue life experiment was done. 10 specimens of rotating mirrors worked for 360 minutes respectively in the speed of 3x104 rpm on the bench of the rotating mirror test system. The cycle index of stress was more than one million times, and no fatigue failure was occurred for every last sample. The results from the numerical are in accord with that from experimental analysis. It is high accurate to analyze the fatigue life of the rotating mirror by the method of numerical analysis.
Numerical and experimental research for dynamic sensitivity of rotating mirror of ultra-high speed camera
Chun-hui Yu, Chun-bo Li, Chun-ping Liu, et al.
The numerical analysis and experiment about dynamic sensitivity of rotating mirror were done to verify the influence of the structural dimensions of rotating mirror on the natural frequency. Firstly, the model of dynamic sensitivity of rotating mirror was established by the ANSYS Parameter Design Language, then the dynamic sensitivity analysis of rotating mirror was done based on the Monte Carlo method and the Latin Hypercube Sampling Technique. The result shows that the spearman rank correlation coefficient of basic variables is different from each other, which reveals that the variables impact the natural frequency in different ways. The radius of rotating mirror body R5 and the radius of shaft segment R2affect mostly the natural frequency among these variables, and the length of the shaft segment L1 affects hardly the natural frequency of rotating mirror. R5 and R2 influence the same natural frequency in opposite way. With the single variable principle, the experiments for dynamic sensitivity were done to examine the results of numerical simulation. The results show that the R5 of rotating mirror increase by 4% which cause the first natural frequency value decreasing from 466.3 to 426.6 Hz. However, when the length of L1 of rotating mirror reduces about 10% the amplitude-frequency response curve of rotating mirror is almost unchanged. The results of experiment are good agree with the numerical analysis show that the numerical analysis is a high accurate method to optimize the structural size of rotating mirror for avoiding the influence of resonance.
Optical fiber network sensor system for monitoring methane concentration
Zhi-wei Zhang, Ji-long Zhang
With regard to the high accuracy optic-fiber sensor for monitoring methane concentration, the choice of light source depends on methane peak values. Besides, the environment of mine should be considered, that is to say other gas should be considered, such as vapor, CO and CO2 etc, without absorbent spectrum in the decided wavelength. It has been reported that vapor, CO and CO2 have no obvious absorption in 0.85μm, 1.3μm and 1.66μm area, CH4 has no obvious absorption in 0.85μm area. So diode laser with 1.3μm or 1.66μm peak wavelength is chosen as the optic-fiber sensor's light source for detecting methane concentration. On the basis of the principle of optic absorption varied with methane concentration at its characteristic absorbent wavelength, the advantage of optic-fiber sensor technology and the circumstance characteristic of the coal mine. An optic-fiber sensor system is presented for monitoring methane concentration. Space Division Multiple Access Technology (SDMAT) and long optical path absorbent pool technology are combined in the study. Considering the circumstance characteristic of the coal mine, the optic-fiber network sensors for detecting methane concentration from mix gas of vapor, CO, CH4 and CO2 are used. It introduces the principle of an optic-fiber sensor system for monitoring methane concentration in coal mine. It contains the structure block diagram of monitoring system, the system is mainly made up of diode laser for monitoring methane concentration, Y-shaped photo-coupler with coupled rate 50:50, optical switch 1×2, gas absorbent cell, the computer data process and control system and photoelectric transformer. In this study, in order to decrease to the influence of the dark-current of photodiode, intensity in light sources and temperature drifts of processing circuit on the system accuracy in measurement, a beam of light is broken down into two beams in the coupler of Y-shaped coupler, the one acts as the reference optical path, the other is known as the sensing optical path. The experimental result shows that diode laser with 1654.141nm in wavelength is taken as the optic source for detecting methane concentration, the detective limit of the sensor is below 4.274mg/m3 when the optical path of absorbent pool is 20 centimeters, and the prevision and stability could satisfy practical application. The whole instrument can also reach on-line measurement with multiple points on different spot.
Design of high-accuracy two-axis sun-tracking system based on optical fiber
Dan Li, Wang Zhou, Ye Li
This paper mainly introduces the system of sun-tracking control in CPV (Concentrating Photovoltaic), includes new structure design, process circuit and software design. This system includes five photoelectric sensors, five optical fibers, one microcontroller, two-axis motion mechanism and motors etc. Here a center fiber is used to determine whether the sun appears and get a reference illuminance, and other four fibers are symmetrically distributed around the center fiber. The optical fibers lead sunlight energy into photoelectric sensors and their length can be adjusted according to actual case. So that system is flexible and has good anti-jamming. The difference value of optical energy gained by each pair of opposite optical fiber is important measure data processed by MCU. Through the calculate result by a MCU, the system can gain the direction of the sun in real time. In addition, this paper presents processing circuit, software about control process as well as error analyzes. The software also provides a scheme for suiting any weather. This new structure can protect the photoelectric sensor in any case of the weather and environment, because the sensors are deeply put inside the instrument and the light energy is passed by the fibers. More than that, through calculating the difference value of each opposite pair of fiber, controlling the motors and increasing the accuracy of sun-tracking can be realized.
TiWN resistive films in an infrared scene projector device and the array fabrication
Shun Zhou, Weiguo Liu, Huan Liu, et al.
Microemitter resistor arrays are one popular approach to obtaining an infrared scene projector capable of wide dynamic range. Typically, the array operates in a two-level architecture wherein the array resides suspended on support legs. In the structure, the resistive films must provide the high resistivity and the resistivity can be easily controlled. Moreover, the resistive films also must be stable at high temperature and having low temperature coefficient of resistance (TCR). Transition metal nitrides can meet the requirement of the microemitter resistor. Among various transition metal nitrides, HfN, ZrN and TiN films have been used as resistive films in dynamic infrared scene generation. While compared the binary alloys above, the ternary compounds such as TiWN film has better performance. For example, TiWN film shows higher adhesion and corrosion resistance and provides better barrier properties. In this paper, TiWN films were deposited by reactive RF sputtering. The influence of the nitrogen partial pressure ratio on the properties of TiWN films was studied. The results show the electrical resistivity of the TiWN films can be determined by the nitrogen partial pressure ratio and the films have high temperature stability. In addition, long serpentine structure of TiWN films was fabricated in order to demonstrate the application in an infrared scene projector, The arrays were fabricated on a polyimide layer on a silicon wafer substrate or a chip by using conventional techniques for photolithography, etching, electric plating and vacuum deposition.
Properties comparison of plasma-deposited SiOx and SiNx films applied to supporting films in an infrared scene projector device
Shun Zhou, Weiguo Liu, Changlong Cai, et al.
Microemitter resistor arrays are one popular approach to obtaining an infrared scene projector capable of wide dynamic range. Typically, the array operates in a two-level architecture wherein the array resides suspended on support legs. In the microbridge pixel structure, the support legs films must have low thermal conductivity, high mechanical strength, minimal stress and good thermal stability. Usually, silicon nitride (SiNx) films can meet the requirement and have been used as support films in dynamic infrared scene generation. While compared with the silicon nitride films, the silicon oxide (SiOx) films have a lower thermal conductivity. If the SiOx films can also be used as support films in the device instead of SiNx films, it can reduce the thermal loss further. Namely, the SiOx films can make the pixel to achieve higher temperature and higher radiance with lower power than silicon nitride films do. In this work, SiOx and SiNx films were deposited in a PECVD reactor .The stress, Young modulus, Hardness, thermal stability, and infrared optical absorption properties of the two types of films were investigated and compared.
Research on fiber Bragg grating huge current sensing based on electromagnetic force
Yuan Yao, Ciming Zhou, Dongli Wang, et al.
Current sensor is the core device for the electric energy measurement. Fiber Bragg grating (FBG) sensing technology has many applications with anti-electromagnetic interference, good insulation, high reliability, small size, distributed measurement. Fiber brag grating based current sensing becomes an important direction of research and exploration. The principle of fiber Bragg grating current sensor based on electromagnetic force has analyzed. The structure of fiber Bragg grating current sensor has designed. Huge current measurement has achieved with high-speed demodulation equipment. The demodulation range of fiber Bragg grating center wavelength is 2.7nm when DC (0-700A, step 100A, 50Hz) current were inflicted.
A compact fluorescence detection system integrated with LED and PIN photodetector for microfluidic application
Wenwen Gu, Zhiyu Wen, Yi Xu, et al.
Laser Induced Fluorescence (LIF) is the most sensitivity and widely used detection method in microfluidic chip. However the tranditional LIF detection has the disadvantage of bulky which limits the promotion and widely use of microfluidic chip. A novel compact fluorescence detection system which can be generally used in glass based micro-fluidic chip is proposed. The high-powered light emitting diode (LED) is used as the exciting light source, and multimode optical fiber is also used as transmission channel to transmit exciting light into the detection window. The filter is a specially designed thin film with the thickness of only 2-3 microns and is integrated on the bottom of the glass based microfluidic chip. PIN silicon based chip is chosen as the photodetector, and is integrated on the microfluidic chip by silicon and glass bonding. The integrated microfluidic chip is packaged in a specially designed cavity to shield external stray light. Experiment results show that the best working current for LED is 200mA; the distance between optical fiber tip and detection spot is 1.5mm; the transmittance of the thin film filter of emission light can reach up to 90% at the wavelength of 520nm; the detection limits for FITC labeled Phenylalanine is 10-7mol/L, and the on-line electrophoresis detection is also achieved.
Novel ring resonator structures generating coupled resonator-induced transparency
Xiao-qi Yu, Lian-yu Xu, Zi-nan Wang, et al.
In recent years, researchers have discovered the phenomena of slow light and superluminal light in many mediums and structures. Coupled Resonator Induced Transparency (CRIT) is used to explain this phenomena and resonators which are capable of inducing CRIT can be widely used in fields like optical sensor, feedback cavity of laser, optical filter and so on. In coupled resonant cavity, mutually independent resonant states interact by weak coupling effect between different cavities, thus changing the characteristics of the whole resonant system and generating CRIT. Generally, this transparency can be produced in single mode fiber (SMF) coupled resonant cavity in both dual-ring and multi-ring coupled structure. Based on these two fundamental structures, in this paper we put forward two new structures which can also generate CRIT: multimode fiber (MMF) ring resonator and polarization maintaining fiber (PMF) ring resonator. Substantially, we change tandem resonant cavities into parallel resonant cavities and they have the same resonant effect. A section of PMF or MMF equals to dual-ring coupled structure or multi-ring structure respectively. Our proposal is verified theoretically and experimentally. Both simulation and experimental results show that the PMF ring resonator can induce more stable and symmetric transparency than the MMF ring resonator. This phenomenon can be explained from three aspects: modal energy coupling efficiency, initial phase of coupling modes and modal polarization states. Additionally, we connect several sections of PMFs and MMFs in serial with a rotation angle of 45°between each other's ends. This improvement is equivalent to increase the number of parallel resonant cavities in an exponential extent and the interference effect of light from different cavities can change the characteristics of the output transparency. We also verify this structure theoretically and experimentally.
Optical correction capability of piezoelectric deformable mirror based on unimorph microactuator array
Jianqiang Ma, Yong Liu, Ying Liu, et al.
Piezoelectric DM based on unimorph microactuator array has advantages of large stroke with low voltage and high operating bandwidth. In this paper, we estimate the correction capability of this DM by fitting Zernike polynomials shapes. First, the influences of actuator arrangement, actuator number and coupling on correction capability were investigated to optimize the correction performance. Then low-order Zernike shapes were reproduced by a fabricated DM using measured influence function matrix. Experiment and simulation results show that the DM has a satisfying correction performance.
Surface plasmon resonance sensor based on supercontinuum source
Zhi-he Huang, Jing Hou, Yang Peng, et al.
Current research on Surface plasmon polaritons (SPPs) is widely spread to surface adsorption, surface roughness and other related phenomena. It has also been used in the chemical and biological high-precision detection fields. More and more high-precision sensors have been created. Supercontinuum (SC) is a laser source with advantages as broad and flat spectra, high brightness and good coherent characters. By researching the SC laser source based surface plasmon resonance (SPR) effect, we can get a more comprehensive reflection of the SPR effect from factors as the light intensity reflectivity and the phase change. The SC laser source based SPR effect is a subject with important theoretical and practical significance. The testing principles and testing methods of the SPR effect in the installations with the Au-coated prism structure were studied. Using a SC laser, the wavelength-scanning and angle-scanning methods can be carried out in one system. The SC laser source based SPR effect in the installations with the Au-coated prism structure was tested. The SPR effect sensors based on SC were designed and realized. The theoretical results matched with the experimental results. Through the relation between the refractive index and the resonance wavelength, we could demarcate different substances.
A portable digital detection technique of building surface crack
Bo Zhang, Lifang Lai, Guiying Yu, et al.
Crack detection is important in safety assessment of buildings. However, for the present there is still no crack detection equipment available which can encompass both short-distance and long-distance examination functions. In view of existing problems, this paper develops a portable digital building surface crack detector integrating short-distance and long-distance examination functions. The crack detector can acquire images of building surface cracks and transmit the images through USB interface to computer for postprocessing. It has the functions of image acquisition, image storage, image processing and results display. Some experiments are performed at different distances and the measured results are calibrated with standard elements. The experiments show that the minimum resolution of the detector is better than 0.01mm, and the measurement accuracy is better than 0.02mm when surveying cracks at a distance shorter than 2m. When surveying cracks at a distance of 2 ~ 100m, both the minimum resolution and the measurement accuracy of the detector are better than 0.5mm.
Performance evaluation method of scene matching algorithm based on automatic statistical experiments
Jia-bin Huang, Fang-fang He, Xin-guo Wang
Precision-guided weapons in the terminal guidance techniques commonly used scene matching, in order to guarantee and improve the accuracy of terminal guidance, related to the scene matching technology research has been a hot issue, and its research areas include fit selection criteria, matching algorithm and so on. Researchers of the domestic staff in the field a lot, there have been many encouraging results. However, whether these algorithms or theory to meet the demand for precision-guided weapons, no rigorous experimental analysis and testing is difficult to prove. In view of this, funding from the ministries, we constructed a practical computer-based matching algorithm for automatic statistical experimental performance evaluation methods. The method used to evaluate performance of the matching algorithm can not only verify the adaptability of the algorithm, but the entire scene matching navigation systems theory to the simulation of great significance.
Study of dynamic weighing system based on photoelectric detecting technique
Gui-cai Song, Yan-xiang Na, Shi-hao Cao, et al.
Dynamic weighing is a process that it reckons the weight of vehicles according to measuring the tires which are moving. It makes use of sensors and some others auxiliary apparatus to measure the appearance of a certain vehicle and tires, then calculates the weight and the speed of vehicles. Finally it can note and read this information. To analyze the dynamic weighing system at home and abroad, it can be easily discovered that these are based on the sensors of electricity. The disadvantages of those sensors are very obvious. For example, when vehicles are dynamic weighed, the speed and accuracy can not be ensured at the same time. Dynamic weighing system is designed in the research of papers. Linear CCD can be used as Sensor to be applied in the mold of weighing. This paper describes the dynamic weighing system, analyses the dynamic of the system, and also investigates the modules of the dynamic weighing system.
Uncooled IR sensor based on lateral polysilicon pn junction diode: initial results
De-hui Xu, Bin Xiong, Yue-lin Wang
These days, uncooled IR image sensors utilizing MEMS technologies have been widely studied for night vision and temperature sensing. Compared with other uncooled IR image sensor, uncooled IR image sensor utilizing p-n junction diode detector has merits of good CMOS compatibility, better mass-production, and better detecting uniformity. In this paper, we proposed a novel uncooled IR sensor based on lateral polysilicon p-n junction diode. In the CMOS process, p-type polysilicon is used for PMOS gate electrode material, while n-type polysilicon is used for NMOS gate electrode material. Due to that polysilicon diode is adopted for sensing, the silicon substrate under the microstructure can be completely removed, and a better thermal isolation and a small thermal mass can be achieved. By using the FEM software Ansys, 3D models of the silicon diode and polysilicon diode have been built for thermal simulation. Simulation results verify that a better thermal isolation can be achieved for polysilicon diode. The device was fabricated by standard CMOS process and a XeF2 post-CMOS maskless dry etching step. Measurement results of the fabricated lateral polysilicon p-n junction diode is also reported.
Figures deduction method for mast valuating interpolation errors of encoder with high precision
Jie Yi, Li-min An, Chun-xia Liu
With the development of technology, especially the need of fast accurately running after and orientating the aim of horizon and air, the photoelectrical rotary encoder with high precision has become the research hotspot in the fields of international spaceflight and avigation, the errors evaluation of encoder with high precision is the one of the key technology that must to be resolved. For the encoder with high precision, the interpolation errors is the main factor which affects its precision. Existing interpolation errors detection adopts accurate apparatus such as little angle measurement apparatus and optics polyhedron, requesting under the strict laboratory condition to carry on. The detection method is also time-consuming, hard to tackle and easy to introduce detect errors. This paper mainly studies the fast evaluation method of interpolation errors of encoder with high precision which is applied to the working field. Taking the Lissajou's figure produced by moiré fringe as foundation, the paper sets up the radius vector's mathematical model to represent figure's form deviation, analyses the implied parameters information of moiré fringe, the relation of the radius vector deviation and interpolation errors in the figures and puts forward the method of interpolation errors figures evaluation. Adopting figure deduction method, and directly from harmonic component of radius vector deviation toward harmonic component of interpolation errors, the interpolation errors can be gotten in the paper. Through data collecting card, the Moiré fringe signal is transmitted into the computer, then, the computer storages the data, using figures evaluation method to analyses the data, drawing the curve of interpolation errors. Comparing with interpolation errors drawing from traditional detect method, the change trend of the interpolation errors curve is similar, peak-peak value is almost equality. The result of experiment indicates: the method of the paper can be applied to evaluate interpolation errors of high precision encoder, which need simple equipment and the examination method is efficient and feasible; Apart from these, the data processing can be realized by valuation analysis software, and the time is short, the result manifestation is intuitionistic; the system can be used in the working field, avert the influence of the speed, and has important meaning to the research of high precision encoder's dynamic precision characteristics.
Research for fluid impurity detection based on ANN and infrared spectrum analysis technology
Huiping Ma, Feng Yuan
A series of economic losses is caused by the biofilm of water pipe in industrial real water systems. Combined optical fiber self-relative technology with infrared spectrum analysis technology, real time detection technique for forming thickness and ingredient is put forward in the paper, which provides technical support and reliable data for analyzing biofouling influencing factors, contaminant separation and warning. Schematic diagram of biofouling detection is presented. Compensation technology based on radial basis function (RBF) neural network and learning algorithm are studied in order to solve the problem of measurement precision and range. Biofouling forming and optical characteristics in industrial real water systems are researched and standard specimen collection is set up. Correcting model explaining quantitatively relation between substance ingredient content and infrared spectrum based on partial least squares (PLS) method. A new method is provided for the research on biofouling in real water system, which can be used in other fields such as mining, environment protection, medical treatment and transportation of oil, gas and water.
Optimization design and fabrication of a novel optical-readout uncooled thermal imaging chip
Yuxiu Zhou, Hong Zhou, Yanxiang Liu, et al.
Infrared imaging systems are widely used in many fields, so it's of great importance to develop thermal imaging systems of independent intellectual property rights. In this paper, a novel MEMS optical readout uncooled thermal imaging chip was developed. The front-side-etching design with narrow windows shortened the etching time and greatly increased the yield. The theoretical thermal-mechanical analysis was carried out to optimize the structure parameters. Thermal conductance can be adjusted by removing part of the gold layer to compromise between the temperature response and time constant. The finite element simulation demonstrated that the performance of the pixel is in good agreement with the theoretical results, which gives a good support to the theoretical analysis. The pixels were successfully fabricated and released with high yield.
Photovoltaic and photoconductive effects in different individual single-walled carbon-nanotube-based devices
Yuxiu Zhou, Tie Li, Yuelin Wang
In this paper, photovoltaic and photoconductive responses were observed respectively in different individual single-walled carbon nanotube based devices of similar device configurations. Under IR lamp illumination in vacuum, photocurrent at zero voltage bias was found in one device while resistance change instead of photovoltaic effects was observed in the other device. The photocurrent was found to decrease as the temperature decreased from room temperature to 78K; on the contrary, the photoconductive effect was enhanced as the temperature decreased. Schottky barriers are suggested to be asymmetric for the photovoltaic device while symmetric for the photoconductive device. The barrier heights of the photovoltaic device were also calculated based on hot electron emission mode of Schottky barrier.
Catalysis of Fe(II) phthalocyanine to the oxidation of 2-chlorophenol and its application in fiber optic biosensor
Yi-lin Tong, Jun Huang, Da-peng Li, et al.
Fiber optic biosensors have many advantages over traditional sensors. For an enzyme based fiber optic biosensor, the sensing performance can be improved by improving the enzymatic activity of the sensing materials. Metallophthalocyanines (MPc) are effective biomimetic enzymes for the catalytic oxidation of pollutants such as phenols and their chlorinated compounds by oxygen. The study on the catalysis of MPc to the oxidation of chlorophenol will be very important to the development of fiber optic chlorophenol sensor. In this paper, Fe(II) phthalocyanine (FePc) was used as a catalyst for the oxidation of 2-chlorophenol (2-CP). The best solution pH for the 2-CP oxidation is pH6.0, and O2 is oxidant. The oxidation of 2-CP caused the consumption of O2 and result in a quantitative relationship between the concentration of 2-CP and O2. A fiber optic 2-CP sensor based on oxygen sensing and mimic enzyme catalysis was prepared and its properties were studied. There is a good linear relationship between the phase delay φ and 2-CP concentration, which was defined by the equation of y = 0.00119x - 0.03267 and R2 = 0.997. It has good repeatability and its response time is 16 min.
Synthesis of CdSe/PMMA nanocomposite and its application in nitric oxide detection
Yun-ming Zhong, Li-yun Ding, Jun Huang, et al.
Nitric Oxide (NO) is a biological messenger molecule involved in multiple physiological processes, which plays an important role in the regulation of blood pressure, immune response, and neural communication. A novel fluorescent probe CdSe/PMMA nanocomposite was synthesized by a simple physical blending method for trace NO detecting. It was confirmed that the CdSe QDs are spherical and monodispersed in PMMA matrix adopting transmission electron microscopy and UV-Vis absorption spectroscopy. The sensitivity of CdSe/PMMA nanocomposite for NO detection and its optical properties were also investigated. The fluorescence intensity of CdSe/PMMA nanocomposite was obvious quenching in the presence of NO and the quenching mechamism was also discussed.
Modeling and simulation of sea clutter for missile-borne radar
Xiaobo Luo, Zheng Liu, Zaiqi Lu, et al.
A simple modeling and simulation method of sea clutter for missile-borne high-resolution radar is presented by introducing the K distribution sequences to represent the characteristics of amplitude fluctuation distribution and correlation of clutter cells. Its model parameters and implementation steps are discussed in detail. The sea clutter simulation was performed after elaborately setting the simulation environment and radar parameters. Simulation results show that the method is effective, and provides a feasible method for simulation and engineering implementation of sea clutter for missile-borne radar.
The research of non-uniformity correction technologies for resistor array dynamic infrared scene projector
Hong-ming Zhao, Jin-dong Fei, Hong Yu, et al.
The resistor array devices are commonly used to produce dynamic two dimensional infrared images in the infrared scene projectors. A non-uniformity caused by many factors is the main source of image fixed pattern noise of the projectors based on resistor array devices. A prior non-uniformity correction procedure must be done before the dynamic infrared image generation for the hardware-in-the-loop simulation test and evaluation. In this paper, the developments and details of the non-uniformity correction technologies for resistor array dynamic infrared scene projector are investigated. The research is commenced directed towards understanding the cause of spatially-distributed radiance non-uniformities of resistor array device, and the fundamental elements that underlie the non-uniformity correction technologies in dynamic infrared scene projection system.
Design and performance of a compact miniature static Fourier transform imaging spectropolarimeter
Jie Li, Jing-ping Zhu, Hai-ying Wu, et al.
We propose a compact, miniature static Fourier transform imaging spectropolarimeter (SFTISP). The spectropolarimeter is formed by cascading two high order crystal retarders and a Wollaston birefringent interferometer. Compared with previous instruments, the most significant advantage of the described model is that without any internal moving parts, electrically controllable or micro-components, the entire wavelength-dependent state of polarization (SOP) is acquired simultaneously along a one-dimensional spatial image by a single snapshot. Also, we show that in this configuration we can benefit from the advantages of the element: compact, robust and high throughput of the Wollaston birefringent interferometer. The theory of the birefringent SFTISP is provided, followed by details of its specific embodiment. A simulation and an experimental demonstration of the sensor are also presented. The core optics of the breadboard sensor is as small as 8×Φ 3.5 cm3 in size. The operation spectral range is from 450 nm to 850 nm. The experiment results were shown to yield accuracy better than 3% over most of the operation spectral band.
Detecting the possibility of train derailment based on FBG sensor system
Yu Quan, Dawei He, Tao Wang, et al.
Detecting the possibility of train derailment and preventing the happening of derailment are very important to railway safety affairs. The FBG has the anti-electromagnetic interference, anti-corrosion and strong stability characteristics which make it very practical for high-speed train's safety detection. A quasi-distributed Fiber Bragg Grating (FBG) based strain sensing system for railway derailment detecting is presented in this paper. The FBG sensor system is designed to detect possible factors which may lead to train derailment, such as the speed of train, the max value of coefficient of derailment and off load ratio R. Then there is algorithm to analysis the possibility of train derailment with detected data. The FBG's characteristic of multiplexing make the railway safety networks service becomes possible.
A new type of silicon drift detector with curved surface
Lu Cai, Min Yu, Dayu Tian, et al.
A new Silicon Drift Detector (SDD) with curved surface has been proposed and analyzed by simulation. The adjacent drift cathodes punch-through problem in traditional SDD has been eliminated in the novel SDD. The potential distribution and advantages of this new SDD in comparison with the normal one are presented and discussed in this paper.
Constant fraction discriminator for fast high-precision pulsed TOF laser rangefinder
Jian-yong Chen, Dong-qing Shen, Wan-cai Li
A low cost high performance constant fraction discriminator (CFD) for laser rangefinder using pulsed TOF (time of flight) is proposed with the accuracy and measuring speed been improved. A distance measuring system has been established and experimental evidence is presented to show the feasibility of solving the time walking error problem to amend the precision and improving the environmental applicability.
Temperature sensor characteristics of photonic crystal fiber in filling methanol
Tiesheng Wu, Li Wang, Zhe Wang, et al.
In this paper, the affection of the effective index and normalized frequency with the temperature have researched based on filling methanol in photonics crystal fiber with the hexagon structure. The theoretical model of the total internal reflection photonics crystal fiber has studied on plane-wave expansion technique. The results of the total internal reflection photonic crystal fiber (TIR-PCF) temperature characteristics have obtained in filling the high refractive index temperature coefficient liquid material. The refractive index of filling liquid and temperature affect on the effective refractive index and normalized frequency. The effective refractive index will reduce and normalized frequency will increase as the temperature increases. When the distance between adjacent holes Λ remains unchanged, the ratio of diameter of holes d and Λ of d/Λ is greater and the input wavelength is longer, the effective refractive index with the temperature becomes the most sensitively. The properties are valuable for design and application of temperature sensors.
Lateral comb-drive MEMS structure for micro-measuring probe application
Fengming Sun, Sai Gao, Xing Fu, et al.
Electrostatic comb-drive actuators, which consists of two interdigitated finger structures with one fixed and the other connected to a compliant suspension, are the most widely used micro actuators in micro-electro-mechanical systems(MEMS). In the actuator applications, applying a voltage between the interdigitated fingers will generate a relative displacement between the fixed and the movable comb structures. The capacitance of the comb-drive structures will vary according to the variation of the relative displacement. The relationship between displacement and resulting capacitance variation is linear. With this principle, the comb-drive structure is employed as a micro measuring probe in this paper. A main shaft connected with the movable comb structures protrudes out of the MEMS chip to sense the surface topography of a specimen under test. A ruby sphere which is mounted onto the end of the actuator's main shaft is employed as a tip. The displacement of the shaft will vary with the variation of the surface topography of the specimen. Accordingly, the capacitance of the comb-drive structures will change. A capacitance readout circuit is designed to convert the capacitance variation into a voltage variation. The results of the designed electronics will be presented. And a drive and sensing system which consists of the micro measuring probe, the capacitance readout circuit, and computer controlled piezoelectric stages is constructed to measure the surface topography of the specimen. To calibrate the drive and sensing system, a standard step of 68nm is one-line scanned.
Frequency division multiplexing of etrinsic Fabry-Perot interferometric (EFPI) optical fiber sensor
Huali Hao, Zhenguo Jing, Wei Peng, et al.
As an important member of optical fiber sensor, fiber optic Extrinsic Fabry-Perot Interferometric (EFPI) sensor has prospects for a wide range of industrial applications due to its small size, compact configuration, good reliability and flexibility. In a white light based fiber optic EFPI sensor system, which has the advantages of large dynamic range and high resolution, spectral analysis equipment is the most important part which takes the major cost of the system. Therefore, multiplexing spectral analysis equipment to measure multiple sensors simultaneously is an effective and necessary way that can save the cost of the whole sensor system. In this paper, a scheme based on the frequency division multiplexing of EFPI optical fiber sensors is proposed. Two EFPI sensors with different gap lengths are parallely connected through the optical fiber coupler. The overlapped interference spectrum of the two EFPI sensors is measured by using an optical spectrum analyzer, which is separated into two individual interference spectrums with a Finite Impuse Response (FIR) band-pass filter. Their envelope components are extracted with Hilbert transform, and then the interference spectrums are normalized by the envelope components. The respective gap lengths of the two EFPI sensors are achieved with the cross correlation calculation. Using this frequency division spectral analysis method, a two-channel multiplexing EFPI sensor system is implemented in the laboratory. The deployment of this frequency division multiplexing technology can greatly reduce the cost of the whole system which has extensive potential applications for distributed fiber optic EFPI sensor system.
Analysis for the stick-slip motion of differential power screw actuator
Jun-bo Zhang, Ping Yao, Xue-jun Zhang, et al.
The model for differential power screw transmission is established, and the mathematical expression of the stick-slip motion is derived based on the friction, in addition, influences of parameters of differential power screw transmission on the stick-slip motion are analyzed qualitatively. Based on dynamical equations of the analysis, the precision and stability of the designed differential power screw actuator is obtained, and the result is compared to it with software SIMULINK to verify.
SCREEN photometric property detection system based on area CCD
Fu-cai Yan, Wei Ye, Yu Xu, et al.
The photometric property detection of screen display is crucial for screen display quality test. Traditional photometry detection technologies were based on photoelectric sensors such as silicon photocell, photo-electric multiplier and CdS, which can detect only some isolated points. To break the limitation of randomness, incompleteness and detection accuracy in current technologies, we designed a screen photometric detection system based on area CCD. The system consists of photometric image sensor, photometric image acquisition hardware and photometric image analyzing software. The photometric image sensor, which adopts optical lens, optical filters and area CCD, adapts its spectrum response property to fit the spectrum luminous efficiency curve V (λ) by adjusting the thickness and quantity of appropriate optical filters. photometric image acquisition hardware adopts the DSP as a core processor to drive the area CCD, to sample, acquire , process and save the image from image sensor, to transmit the image to computer. For real-time performance of transmitting, the hardware system adopts the transmission protocol of USB2.0. The uploaded image will be processed by photometric image analyzing software, and then displayed in real time with detection results. The screen photometric detection technology based on area CCD can detect specifications of the whole screen such as luminance, contrast, onoff ratio and uniformity, breaks the limitation of randomness and incompleteness in current detection technology, exactly and fully reflects the integrated display quality of the whole screen. According to the test results, the accuracy of this system has reached the accuracy level one in China.
Theoretical study of high-sensitivity surface plasmon resonance fiber optic sensing technology
Hong Li, Zhenguo Jing, Wei Peng, et al.
Surface Plasmon Resonance (SPR) has been widely investigated for chemical and biological sensing applications. Especially, fiber optic SPR sensors have recently drawn considerable attention because of their fundamentally simpler structure, lower cost, and suitability for remote-sensing applications. This paper will present a research work for a novel multichannel SPR sensing technology. Based on the Kretschmann's SPR theory, we theoretically investigate the surface parameters effects to SPR wavelength changes. Emphasis will be placed on a theoretical design and numerical simulation of a multichannel fiber optic SPR sensing scheme based on a geometrical tapered fiber optic sensor probe that coated with nanoparticles imprinted polymer on the SPR sensing region. The parameter effects of SPR sensing area that include metal thickness, sensing area length and dielectric overcoat layer. SPR spectra that change with incidence angle and wavelength are investigated by using numerical calculations and simulations. While nanoparticles imprinted polymer for enhancement of sensitivity can serve as an enhanced transduction mechanism for recognition and sensing of target analytes in accordance with different requirements, the scheme of a multichannel fiber optic SPR sensor can be further adapted to the design and development of multi-channel optical fibers SPR sensor probes by combining SPR with other technology as a comprehensive sensor design.
Study on effect of polarization for improving signal noise ratio of stellar objects in daytime
Rui-jin Zhang, Hao Xian, Kai Wei, et al.
Sky background is one of the main noise sources in astronomy observation. Most of the telescopes work well in nighttime with low sky background, but do not work anymore in daytime with strong sky background. Polarization filtering is a critical method that can be used to suppress the sky background and improve the signal noise ratio (SNR) of object signal. Experimental device with polarization filtering technology was constructed in 1.8m adaptive optics (AO) telescope of Yunnan observatory, to identify the effect of polarization filtering technology. Experimental results indicate that the SNR (ratio of object energy to noise's mean square deviation) of stellar objects could be improved to 1 to 3 times at different observation conditions, which is significative to star detection in daytime. Experimental results also indicate that polarization filtering technology is effective and important in observing different kinds of stellar objects in daytime condition. Furthermore, it also makes it possible to apply our AO system in daytime in future.
Experimental study on resonator micro-optic gyroscope
Meng Zhao, Bang-ren Shi, Chen Chen, et al.
Resonator optic gyroscope (ROG) based on Sagnac effect has been investigated over the past years and developed as an attractive device for many applications. Resonator micro-optic gyroscope (R-MOG) with an only several-cm-long ring on a wafer is a promising candidate for the new generation inertial rotation sensor. Using micro machining process, R-MOG was manufactured on the silicon or LiNbO3 wafer by etching passive optical ring resonator devices. It has great advantages by realizing the minitype. R-MOG is a kind of optic gyroscope by detecting the resonance frequency difference of the clockwise and counterclockwise resonance to measure the angular velocity. The Sagnac effect is extremely weak, so the detection method has been the key point in researching R-MOG. Using the multi-beam superposition principle, we theoretically analyzed the signal detection scheme based on laser frequency modulation and experimentally investigated the equivalent open-loop signals of a R-MOG chip. The passive ring resonator (PRR), the core component of R-MOG, was composed of a ring waveguide with a radius of 2cm and an optical coupler with the coupling ratio of 12%. The resonance curve showed that the free spectral range (FSR), full width at half maximum (FWHM) and fineness were 3.0378GHz, 74.09MHz and 41, respectively. In the equivalent open-loop experiment, the counterclockwise (CCW) light frequency was locked to its resonant point, and the clockwise (CW) optical frequency changed around the CW resonant point. The experimental results illustrated that the sensitivity of the R-MOG was 6.15 rad/s.
The fast automatic interpretation of digital holographic interference fringes
Jun Guo, Kun Yang, Jie Sun
The holographic interference fringes recorded in the holography experiment often have many defects. The method put forward in this paper, which is based on the properties of Hough transform and Fourier transform, is an effective way to interpret the holographic interferogram of poor quality and can be used to count the number of the fuzzy linear interference fringes accurately. When interferogram is processed by Hough transform, the transformed fringes in Hough space will be convenient to count. After the Hough transform, the result is processed by Fourier transform for accurately calculating fringe number, the gray maximum, which demotes the period number of interference fringes, will be easily calculated out in the frequency domain. At first, in order to obtain accurate fringe number and avoid the noise influence, the interferogram is processed by the edge extraction of canny. Then the orientation of holographic interference fringes can be obtained by Hough transform and Fourier transform after the edge extraction result is processed. At last the original interferogram is processed by Hough transform and Fourier transform. This method can be used in the automatic interpretation of holographic interferogram, which are recorded in the holographic interferometry experiments for displacement measurement or deformation measurement. The holographic interference fringes have been successfully recognized and exactly counted. The experiments show that not only the method has avoided the influence of the uneven gray and the serious blur of fringes, but the test precision and efficiency of the digital holographic interferometry has also been greatly raised. The test result shows that the measure precision can be reached up to 1/100μm.
Introduction of new optical fiber monitoring system of fluid flow with nonintrusion
Ying Shang, Xiao-hui Liu, Chang Wang, et al.
In the oil field development and production, fluid flow is an extremely important parameter which determines the transmission characteristics of the oil production, real-time monitoring of fluid flow parameter provides a scientific basis for oil and gas optimization exploration and increase of reservoir recovery. A method for interrogating fiber optic sensors non-intrusively sensing fluid flow is proposed, those sensors are positioned between pairs of low reflectivity fiber Bragg gratings, the fiber optic sensors wrapped closely around the outside wall of pipe are used to sense the internal information of fluid flow, new optical fiber monitoring system of fluid flow bases on optical signals. When optical signals are transported in optical fibers, phase is changed due to the effects of the fluid flow , the size of which can be determined by measuring the relative changes of the phase. So the optical fiber monitoring system of fluid flow making use of modulation and demodulation techniques of phase generated carrier accurately determines the size of fluid flow with non-intrusion.
Hybrid zirconium sol-gel thin films with high refractive index
Arnaud Gorin, Robert Copperwhite, Salem Elmaghrum, et al.
We describe the synthesis of optical quality thin film materials with high refractive index, employing zirconium based hybrid sol-gel precursors. As the zirconium propoxide precursor is unstable in the presence of a strong nucleophilic agent such as water, two synthesis routes have been performed employing a chelating agent and an organosilane precursor to avoid the formation of any undesired ZrO2 agglomerates, leading to organo-zirconate complexes and silicato-zirconate copolymers, respectively. The prepared hybrid sol-gel materials were deposited by spin-coating to form a transparent thin film on silicon substrates, and heat treated at 100 °C for the final stabilisation of the layer. The effect of the two synthesis routes on the optical properties of zirconium based hybrid sol-gel material is discussed. It was found that the nature and concentration of the organosilane precursor can significantly affect the structural properties of the deposited films. A correlation was also demonstrated between the concentration of the organosilane precursor and the refractive index of the material. By reducing the concentration of organosilane precursor, high refractive index materials were obtained. Similar behaviour was observed for the materials synthesised via chelating agent. The synthesis employing an organosilane precursor produces films with higher refractive index. A maximum refractive index of 1.746 was measured at 635nm for the deposited thin films.
The photocurrent modulation of quantum dot resonant tunneling diode with forward bias voltage
Daming Zhou, Wangping Wang, Ning Li, et al.
The light response mechanism of quantum dot resonant tunneling diode (QDRTD) has been investigated experimentally. The QDRTD is constructed by an InAs layer of self-assembled quantum-dots (QDs) being placed on the top of AlAs barrier layer. The work bias of the device is set in the positive differential resistance region. It is found that the charging InAs quantum dots can effectively control the carrier transport properties of the device. The photo-excited holes can lower the electrostatic energy of the quantum dot state. Thus, the electrons in the emitter can easily tunnel to the collector, and the current increases under illumination. It is found that the increment (or decrement) of photocurrent depends on the amount of photo-excited holes captured in the dots. Furthermore, due to the quantum multiplication effect, the QDRTD can be applied as a photon counting device.
Closed-loop control of a MOEMS mirror integrated with angle sensor
Rong-rong Qian, Zhi-yu Wen, Li Chen, et al.
There is currently considerable interest in MOEMS mirrors because of their wide applications. As the majority of application systems require accurate control of reflection optical beams, We have developed a MOEMS mirror integrated with angle sensor. In this paper, a closed-loop control scheme for the MOEMS mirror integrated with angle sonser is proposed. Following establishment of theoretical model of the mirror, mathematical model of the closed-loop control system is presented and simulated using CAD software. Based on the study of the closed-loop control method, a closed-loop control circuit is developed. The circuit consists of signal producing module, angle detecting module, feedback control module and VGA module. The signal producing module is a frequency divider based on CPLD to provide driving signal with steady frequency. The signal frequency generated by the signal producing module is 542Hz, which matches the resonant frequency of the mirror, 543.22Hz. Key component of the circuit is variable gain amplifier made up of an analog multiplier. It controls the amplitude of the driving signal utilizing the measurement signal of the integrated angle sensor to achieve constant deflection angle of the mirror. We applied the circuit to the fabricated mirror, and experiment results show that, with the closed-loop control, the accurate control of the mirror is achieved.
Spatial 3D display based on DMD and swept-volume technology
Jianfang Xing, Huajun Gong, Wenping Pan, et al.
Display devices play important roles in the interaction between human and digital world of computer. Building devices which can display 3-D images in true 3-D space has aroused researchers' concern for many years. In this paper, we develop a novel spatial display by projecting 2D profile slices of the 3-D models in rapid succession onto a synchronous rotating double bladed helical screen periodically. It is a high speed light-addressed system base on Texas Instruments TM(TI TM) Digital Mirror Device TM (DMD TM) technology, and high frame fresh rate is achieved by accurate control over DMD micro-mirrors. When the rotation frequency of the screen higher than critical flicker fusion frequency, the stroboscopic time-varying slices are fused into a whole flicker-free 3-D spatial imagery because of persistence of vision. The display generate volume-fill 3-D imagery consist of an array of voxels that can be seen hovering in the swept volume. The design and manufacturing of prototype is performed. It has a resolution of 1024x768x132 voxels at a volume refresh rate of 10 Hz. The 3-D imagery occupies real physical space about 203 cm3, each voxel scatter visible light from the position in which it appears. It provides full parallax, not only enable 3-D imagery to be viewed without any eye wears or headsets, but also support "look around" function. Different viewers from practically any orientation can see different sides of the imagery, as if people watch sculptures.
Research on the relation between the contact angle and the interface curvature radius of electrowetting liquid zoom lens
Cunhua Zhao, Huiqin Liang, Dongqing Cui, et al.
In the ultralight or ultrathin applied domain of zoom lens, the traditional glass / plastic lens is limited for manufacture technology or cost. Therefore, a liquid lens was put forward to solve the problems. The liquid zoom lens has the merits of lower cost, smaller volume, quicker response, lower energy consumption, continuous zoom and higher accuracy. In liquid zoom lens the precise focal length is obtained by the contact angle changing to affect the curvature radius of interface. In our works, the relations of the exerted voltage, the contact angle, the curvature radius and the focal length were researched and accurately calculated. The calculation of the focal length provides an important theoretical basis for instructing the design of liquid zoom lens.
A polarization-insensitive fiber optic sensor based on Faraday rotator mirror
Ya-bin Zhang, Xin-tong Sun, Chao Cai, et al.
Fiber-optic sensors are widely used and researched in-depth. Interferometric fiber optic sensor is an important category of fiber optic sensor because of its high sensitivity. However, polarization-induced fading phenomena always appear in the output of sensors which constructed of low-birefringence single mode fibers. In this paper, we firstly give the structure of a fiber-optic sensor based on M-Z fiber optic interferometer. And we use polarization optics to study the light state in this sensor. Taking the polarization state of input light in fiber-optic interferometer is random we calculate the Jones vector of the output light. To study the polarization fading phenomena we calculate the intensity of output light. We caculate the degree of polarization fading by computer software. The result shows that sensing signal will completely vanish. Thus we can't get steady sensing signal and we must use depolarization fading technology. We give a simple structure of a polarizationinsensitive optical fiber sensor. Two Faraday rotator mirrors (FRM) are added into Michelson optical fiber interferometer to improve the visibility. We also use polarization optics to study the output light of this structrue. Theoretical analysis and experimental study indicates that this convenient method can improve visibility to 1. The feature of the method is convenient, accuracy and practical. And it can apply to various kinds of complex construction.
Optimized design and simulation of high temperature pressure pipeline strain monitoring with optical fiber sensing technology
Feng Zhang, Yueming Liu, Jun Lou
High temperature pressure piping have been applied widely in the chemical industry, the petroleum enterprises and the electrical power plants, and corresponding accidents happened frequently every year owing to the pipeline leakage and explosion. By massive accident statistics and analysis, the high temperature creep and the pipeline inside wall corroding are the main causes to result in the pipeline leakage and explosion accident. By real time sensing the strain change of pipeline outer surface, the online working status of the high temperature pipeline could be monitored and the leakage and explosion accidents would be avoided. Now several methods can be considered to sensing and monitoring the strain change of the high temperature pipeline surface, including Electricity sensor examination method, ultrasonic wave examination method and infrared thermal imagery examination method. After careful analysis and contrast, Electricity sensor examination method was given up for it couldn't be working steadily under high temperature conditions and easily excitated electric sparks which would result in flammable explosive danger in chemical industry and petroleum enterprises. Ultrasonic wave examination method and infrared thermal imagery examination method could avoid the shortages of Electricity sensor examination method based on the non-destructive examination theory, but the ultrasonic wave method could be applied only in examining the pipeline wall thickness, the inside wall crack as well as the material air bubble flaws restricted in its working principle. Consequently ultrasonic wave method examination method wasn't suitable to sense and monitor the strain change of the high temperature pipeline surface; Infrared thermal imagery examination method has low sensing resolution and can only examine internal etching pit and wall thickness attenuating, so it is unable to examine the pipeline surface strain change on time. Therefore three reported real-time examination methods mentioned above cannot satisfy the strain change monitoring of high temperature pressure piping. In this paper a novel method is presented using optical Fiber Bragg Grating sensor to carry on the real-time monitoring of the high temperature pressure piping surface strain change. firstly the stress and strain analysis of the high temperature pressure piping surface is given based on the established theoretical model, then optimized design and simulation is accomplished with computer ANSYS software. In the end a optimized set-up is put forward and discussed.
A new method to eliminate the noise of vacuum microelectronic high precision accelerometer
Hai-tao Liu, Zhi-yu Wen, Li Chen, et al.
The vacuum microelectronic high precision accelerometer was developed based on the vacuum field emission theory; it has many advantages such as high precision, good linearity in theory, but the inherent low frequency such as 1/f noise of the accelerometer decreases the signal-to-noise ratio greatly, and it is the main influencing factors to precision and linearity of accelerometer. In this paper a new method to eliminate noise of vacuum microelectronic high precision accelerometer was first bring forward by using modulation and demodulation and coherent detection technology. The system mainly includes AC signal generator, current obtain, phase shift, demodulator, differential amplification and feedback control. At last, the noise between 0 Hz and 200Hz contrast test experiment of the accelerometer was carried out by oscilloscope, the result shows the mean spectrum density of output signal is 29μV/√Hz between 0 Hz and 200Hz. Static gravitation field rolling experiment in ±1 g is also performed to measure the linearity of the accelerometer; the least-square linear fitting curve shows the maximum nonlinear is 0.41%. Through the results we can draw conclusion that the noise and linear performs have been greatly improved through eliminated noise.
The effect of PCF combiners on the whole loss under different lengths of transition zone
Hang Zhou, Zilun Chen, Jie Li, et al.
Because of the diversified properties Fiber Laser affords a wide field of application. But restricted by nonlinear effects, heat damage and other elements, it is impossible to increase the output power unlimitedly. When single fiber can't meet, it needs to use Fiber Laser through beam combination to get high output power. Undoubtedly combiners play an important role for increasing the output power of Fiber Laser. The advent of Photonic crystal fiber (PCF) abound the kinds of combiners. It has numerous benefits and widespread application value. First, build the model of PCF combiners. Then through Finite Difference Method(FDM), calculate the effect of PCF combiners on the whole loss under different lengths of transition zone. Finally, compare the results. Through the results of numerical simulation calculation: when the length of Transition zone L is shorter than the diffraction length of the tapered L0, loss will go down with the increase of L; however, when L is far longer than L0, the increase of L will have negligible effect on the decrease of loss. So the conclusion is significant to both increase the performance of Photonic crystal fiber combiner and decrease the loss.
A large-scale strain sensor based on fiber Bragg grating
Xiaoyan Shen, Yuchi Lin
As a sensing cell, Fiber Bragg grating (FBG) can transduce physical quantities like strain, temperature, etc, having attractive merits of being small and light, resistance to corrosion and immunity to electromagnetic interference, etc. Commercial FBG strain sensor has a sensing range of no more than 9000 με (0.9%), however, larger-range strain sensor is demanded in industry such as heavy structural distortion and crack-happening. A new kind of large strain sensor based on FBG is studied here. The sensing element has a metal trapezoidal frame. The two feet of the frame can sense a large strain of the body, which is converted to a small strain on the surface of the frame' beam. The attached FBG senses this small strain, and then the body's strain can be known from the FBG's wavelength shift. The trapezoidal frame is taken theoretically analysis adopting the 'unit load method' and numerical simulation by finite element method. The sensitivity model of the sensor between the body's strain and the FBG's wavelength shift is deduced and verified. Real large strain sensors are homemade, with verifying sizes. The large strain is controlled by a motorized translation stage, and the FBG's wavelength shift is interrogated by MOI sm125 interrogator. The experimental results show an outstanding large-strain sensing ability of the sensors, having the sensing range of -20~40%, with the linearity of less than 1%, the hysterisis error of less than 1% and the repeatability of less than 0.9%.
Ultrabroad bandwidth and high-coupling-efficiency compact coupler using multilevel grating structure
Wei Zhou, Hualiang Zhang, Junbo Yang, et al.
A compact multilevel grating coupler based on SOI material structure is proposed to realize coupling between waveguide and waveguid, which has the ultrabroad bandwidth and extremely compact dimension (with the grating length of 3μm). The incident wave is TE polarization and designed as normal incidence. The influences of the grating coupler characteristics, for instance, grating period, grating height and grating length, as well as the thickness of SiO2 layer on the coupling efficiency have been discussed. The simulation results indicate that the 3dB bandwidth of 160nm from 1390nm to 1550nm can be obtained, accompanied by the coupling efficiency of approximately 50% around 1550nm. Simultaneously, the sufficient high coupling efficiency of 67.5% at the wavelength of 1460nm has also been observed.
Research on pointing of piezoelectric fast steering mirror under vibration condition
Bingna Zhang, Liang Zhang, Genghua Huang, et al.
Piezoelectric Fast Steering Mirror (PFSM) is widely used to realize fast and precise pointing in optical systems. To eliminate the nonlinearity, close-loop driving circuit must be used through position sensors such as strain gauge. Since PFSM not only works in static condition, but also needs pointing precisely under dynamic condition, it is necessary to research the pointing performance under shock and random vibration. The platform was established and the experiment was done to verify the deviation angle of PFSM during vibration in this paper. The conclusion is got finally.
Design of a MOEMS-based electromagnetic driven high efficacious phase grating with angle sensor
Biao Luo, Zhi Yu Wen, Li Chen
A novel design for fabricating the high efficacious rectangular phase grating with angle sensor by MOEMS fabrication process is presented in this paper. The purpose of this design is for increasing the Signal-to-Noise of output signal and reducing the size of near infrared spectrometer by using MOEMS grating. Diffraction efficiency is designed and optimizing at first. We used Fourier optical theory and diffraction optical theory analyzed the diffraction efficiency of the rectangular phase grating, and used the PCgrate simulated the design. After analysis and calculation, we found the best parameter of this grating. According the former design of infrared spectrometer by ZEMAX, the angle resolution of angle sensor is 60mV/°, maximal angle is ±4.7° and the size of grating is 5x6mm2. Because of the large deflection angle, the electromagnetic force is used for driving this grating. For sensing the grating deflexion angle, we design the angle sensor in the torsion bar of this grating. This sensor is P-type piezoresistive sensor and fabricated on n-(100) high-resistance silicon wafer by boron ion implantation. Analyses stress of torsion bar and piezoresistive angle sensor with Wheatstone bridge theory, the scanning angle θ in a linear relation with output voltages (Vout) of Wheatstone bridge. The size of torsion bar is 2100μmx220μmx75μm, the frequency of first step model is 550Hz. The size of the sensor is 100μmx15μmx0.5μm. Finally, the compatible fabrication process of this device is given. The results of experiments and theory analyzing demonstrate that MOEMS phase grating could work effectively, and angle sensor achieve the real time need. This MOEMS grating is suitable for infrared spectrometer.
Optical properties of square-aperture planar microlens array
Jie Chen, Fengjun Zhang, Xiaomei Chen, et al.
In this part, to improve fill factor of microlens array, we designed a new type of square-aperture planar microlens array which is used for collecting and transferring optical information efficiently. By lithographic ion-exchange and a special technology to remove the 1.0 micron layer of titanium on the glass substrate, square-aperture planar microlens array is buried in the substrate and the fill factor of microlens array are larger than 98%. Each microlens unit of the array is square and has an aperture size of 0.2mm with the excellent capabilities of external stress and temperature. At last, many optical feature parameters of square-aperture planar microlens array are tested and analyzed, and the experimental results show that good performance can be used farther in studies and tests later.
Spherical aberration of planar square aperture microlens array
Xiaomei Chen, Fengjun Zhang, Zhifang Zhao, et al.
Ion thermal diffusion theory was applied to analyze the influence on numerical aperture and focal length of planar square aperture microlens array (PMLA). Moreover, numerical aperture and focal length with different ion-exchanging time but the same size of mask aperture were measured experimentally. Then, we measured the longitudinal and transverse spherical aberration by the method of parallel light incidence and emergent light pupil and improved the aberration of square-aperture PMLA by annealing treatment. Experiment results show that the spherical aberration is decreased obviously after annealing process. Meanwhile, imaging resolution is also improved more greatly. PMLA optical system with continuously adjustable focal length was proposed, which was made up of two pieces of square aperture PMLA and an aspherical lens and focal length can be adjusted continuously just by precisely adjusting the distance between the two pieces of square aperture PMLA.
A novel electromagnetically actuated MEMS scanning mirror integrated with rotation angle sensor
Li Chen, Zhi-yu Wen, Zhong-quan Wen, et al.
Aiming at application of micro-spectrometer systems, a novel electromagnetically actuated MEMS scanning mirror with large size and integrated rotation angle sensor is proposed for the application of micro-spectrometer. The size of the mirror plate is 6x5mm2, which is supported by two torsion beams. The scanning mirror is fabricated on a 500 μm-thick single crystal silicon wafer using bulk micromachining process. Two gold coils are deposited on back side of the mirror using electroplating technology. One of them is used to generate Lorentz force to drive the mirror, and the other is used to monitor the rotation angle by measuring the induced voltage which is proportional to the angular rate. The silicon substrate is heavily doped (0.02 ohm•cm) to connect the coil central end to outside pad. A 500 nm-thick aluminum film is sputtered on the front side of the mirror plate to form a high quality mirror surface. The whole structure is released by wet etching technology, and corner compensation structure is designed to avoid convex corner undercutting. In order to achieve large deflection angle, NdFeB permanent magnets are used to provide high magnetic field. Testing results show that maximum mechanical rotation angle of the scanning mirror can achieve ±10°at the resonant frequency of 344Hz with low driving voltage of less than 1Veff, corresponding to a Q-factor of 137 at atmospheric pressure, and the output voltage of the angle sensor has high linearity.
Research of a micro-ultraviolet spectrometer system
Zhi-yu Wen, Tian-ling Zeng, Zhong-quan Wen, et al.
A novel micro-ultraviolet spectrometer system with characteristics of small size, low price and high performance was developed and the main performance parameters were tested. The wavelength range is 190-410nm, the wavelength accuracy is less than 1nm, and the resolution is less than 3nm (using 100um fiber). To verify the system performance, a pollution-free water quality testing platform was built based on the micro-ultraviolet spectrometer and experiments of chemical oxygen demand (COD) testing were made. The results indicated that the system performance can meet the practical demands of real-time water quality monitoring.
A novel MEMS field emission accelerometer based on silicon nanotips array
Li Chen, Zhi-yu Wen, Zhong-quan Wen, et al.
A novel MEMS field emission accelerometer based on silicon nanotips array with about 10000 silicon tips in total is proposed. It consists of a proof mass, four L-shaped springs, silicon nanotips array, anode and feedback electrodes. The sensor is fabricated on one N-type (1 0 0) single crystal silicon wafer and one #7740 glass wafer using bulk silicon micromachining technology. The silicon tip arrays are form by wet etching with HNA (HNO3, HF and CH3COOH) with I2 as additive. After oxidation sharpening, the curvature radius of the tips is smaller than 50nm, and the tip arrays are metalized by sputtering TiW/Au film. ICP process is utilized to release the sensor chip. In order to improve the linearity of the sensor, a feedback control circuit is used to rebalance the proof mass. The accelerometer is tested on a dividing head and test results show that the sensitivity is about 420mV/g and nonlinearity is about 0.7% over a range of -1g~1g.
Ultrafast photoluminescence features analysis of In-doped ZnO nanowires
ZnO has been researched for its excellent properties for optoelectronic, sensing, piezoelectric application, solar cells, light emitting diodes and laser diodes. Transparent oxide semiconductor (TOS) thin films made of ZnO nanocomposites, which are used as transparent electrodes in optoelectronic devices, have been widely reported. Among the TOSs, the thin films of a homologous compound, with a so-called superlattice structure have attracted considerable interest. Because of the spatial confinement of conductive electrons in the two dimensional layer, their interesting electronic, optical, and magnetic properties, along with small size and chemical reactivity, have led to a wide range of applications in nano-optoelectronics, medical diagnostics, catalysis, and chemical sensing. In this paper, the ultrafast dynamics and the nonlinear optical response of metal nanocomposites were investigated. Heat treatment has been proven to be a feasible way to improve the performance of ultrafast response for this kind of materials. Based on the experimental results of In-doped ZnO materials excited by intense fs pulses near 800 nm, nonlinear optical effects that may emerge under an intense field are attributed to be responsible for the efficient two-photon absorption process under detuned excitation.
Development of CdZnTe radiation detectors
Cadmium Zinc Telluride (CdZnTe or CZT) is a very attractive material for room-temperature semiconductor detectors because of its wide band-gap and high atomic number. Despite these advantages, CZT still presents some material limitations and poor hole mobility. In the past decade most of the efforts developing CZT detectors focused on designing different electrode configurations, mainly to minimize the deleterious effect due to the poor hole mobility. A few different electrode geometries were designed and fabricated, such as pixelated anodes and Frisch-grid detectors developed at Brookhaven National Lab (BNL). However, crystal defects in CZT materials still limit the yield of detector-grade crystals, and, in general, dominate the detector's performance. In the past few years, our group's research extended to characterizing the CZT materials at the micro-scale, and to correlating crystal defects with the detector's performance. We built a set of unique tools for this purpose, including infrared (IR) transmission microscopy, X-ray micro-scale mapping using synchrotron light source, X-ray transmission- and reflection- topography, current deep level transient spectroscopy (I-DLTS), and photoluminescence measurements. Our most recent work on CZT detectors was directed towards detailing various crystal defects, studying the internal electrical field, and delineating the effects of thermal annealing on improving the material properties. In this paper, we report our most recent results.
A novel nano-mechanical displacement detection based on a photonic nanowire waveguides coupler
Xiongyeu Chew, Guangya Zhou, Fook Siong Chau
Microoptoelectromechanical systems (MOEMS) are promising choices in achieving compact and yet precise sensors with intensity / phase modulation techniques or resonance shift based techniques. Particularly in the area of displacement sensing, MOEMS device may potentially offer a high accuracy and yet compact solution for highly sensitive portable sensors. We propose a novel approach of a hybrid device consisting of nano-mechanical structures and nanowire silicon photonics to achieve a new displacement sensing mechanism that does not require segmentization or intersecting of waveguides. In this work, we demonstrate that by optimizing a relatively broadband air-suspended nanowire waveguide directional coupler design that is integrated using silicon photonics structures, we can achieve sufficient attenuation without the need of waveguide segmentization thus effectively reducing the undesired insertion and coupling losses. First, we numerically design and optimize, utilizing a 3D FDTD numerical method, a nanowire waveguide directional coupler that is capable of achieving a -13 dB extinction ratio at submicron displacements. Next, we fabricate the proposed nanowire photonic waveguide directional coupler utilizing a simple and monolithic fabrication approach. The nano-mechanical structures are then characterized and calibrated in-situ under a scanning electron microscopy (SEM). The optical sensitivities of the waveguide directional couplers are then characterized on a vibration isolation optical table under low noise conditions. The noise spectrum densities are also characterized by driving the structures under an AC actuating voltages to understand the minimum detectable nano-displacements.
Nonsilicon micro-machined variable optical attenuator
Hai-lin Zhou, Xu-han Dai, Gui-fu Ding, et al.
Optical power equalization between wavelength-path slots in wavelength division multiplexing (WDM) networks is an increasingly concerning issue in all-optical networks, and this made variable optical attenuators (VOAs) play an increasingly important role in fiber optic transmission systems. Various types of optical attenuators have been realized, but conventional available mechanical VOAs are bulky, costly, and slow. MOEMS technology provides new approaches to improve the characteristic mentioned above. Previous attempts to realize MEMS variable optical attenuators include the use of a micro-driven shutter, a mechanical antireflection switch (MARS) modulator, a micro-machined tilted mirror, and a micro-machined membrane-type waveguide. In this paper, we report the design and fabrication of two types of electromagnetically actuated variable optical attenuator (VOA). They are both driven by a similar construction containing of a plane coil and a FeNi armature. The first one adjusts the attenuation by moving a shutter between the two fibers, the second one by moving one of the fibers directly. The first one is fabricated by nonsilicon surface micromachining technology. In which a copper layer was used as the sacrificial layer, and the electroplated FeNi as the structure layer. This scheme provides another way to fabricate the optical microstructure. According to the experiment results, it has insertion loss less than 3 dB at 1550-nm wavelength, dynamic range greater than 40 dB, 0.2-dB repeatability, and return loss better than 40 dB, driving voltage less than 20 V. For the second one, it included the silicon platform for adjustment of optical coupling between two optical fibers. The main fabrication process of the silicon platform is was the KOH antistrophic wet chemical etching of <100> silicon wafers. The silicon wafer is further selectively etched from the bottom side to subtract the thickness of the silicon elastic platform. In addition, two V grooves were fabricated for alignment of the input and output optical fibers. One of the V grooves is on the mobile elastic platform; the other is on the fixed framework. When the platform is attracted downward by the electromagnetic force, the central axes of the two fibers are mismatched to adjust the attenuation. The insertion loss is less than 1 dB, the polarization dependent loss is less than 0.1 dB, dynamic range is larger than 50 dB, and the driving voltage is less than 5 V. The design, fabrication, and test of the two devices are all introduced detailedly below. The first device is suitable for fast adjustment. The second one may be adopted in applications where, the fabrication cost and polarization-dependent loss is of more concern.
Design and optimization of a clamping mechanism for piezoelectric inchworm actuator
Geng Wang, Chunlin Guan, Xiaojun Zhang, et al.
This paper presents the structure design and optimization of a clamping mechanism for an inchworm-type piezoelectric actuator. Since the performance of clamping mechanism will decide the feasibility of inchworm-type actuator, design and fabrication of better clamping mechanism will continuously be part of the focus in inchworm-type piezoelectric actuator design. Currently the driving force of piezoelectric inchworm actuator is usually not high enough. In order to more efficiently design the clamping mechanism, numerical simulation is performed to select the geometry parameters that can improve the performance. As a kind of numerical simulation method, ANSYS Optimization Design Method is used to analyze and optimize the performance of the clamping mechanism. In this design, a special kind of piezoelectric ceramic and 65Mn are chosen as the main materials; the dimensions of clamping mechanism and a pre-load force are chosen as design variables; the maximum von Misses stress and the holding forces are chosen as state vectors. When clamping the holding force should reach the maximum and when releasing the holding force should arrive at the minimum. In accordance with this requirement, an objective function is constructed. When the objective function reaches the minimum value, the best design set will be attained. The results of simulation experiments and optimization analysis show that the clamping mechanism can reach the desired performance and has an adequate self-locking force when power off. A prototype of the clamping mechanism has been fabricated and tested to validate the simulation results.
Polymeric nanostructures fabricated by dynamic nanoinscribing technique and its applications
Liangjin Ge, Xudi Wang, Qisheng Tang, et al.
Nanoscale grating structure can be utilized in many practical applications in optics, flat-panel displays, and biosensors. Dynamic nanoinscribing (DNI) technique was newly developed to create large-area and truly continuous nanograting patterns in a variety of metal or polymer materials with feature size down to sub-50 nm and at very high speed. In this paper we investigate the nanopatterning of PC and SU-8 by DNI process and then take advantage of its superior optical and thermal properties to explore its applications in nanooptics and nanofluidics. To carry out nanoinscribing, silicon grating templates with different periods were first fabricated. The inscribing property of PC and SU-8 under various pressures and temperatures was systematically studied, in which the experimental results were compared with the simulation results described by a modified equation of Squeezed flow. Inscribed polymeric gratings with period of 700nm were achieved and excellent uniformity can now be routinely replicated using this optimized process. Using this technique, free-standing subwavelenth gratings based on SU-8 are successfully fabricated and their performance are characterized. The inscribed polymeric gratings could also be sealed with another bare layer thermally to serve as enclosed channels after oxygen plasma treatment. The fabricated nanofluidic channels were characterized using spontaneous capillary filling with dyed water, demonstrating good quality of sealing.
Monitoring and evaluation of interface delamination in reinforce concrete using ultrasonic guided waves
Dong-Sheng Li, Tao Ruan
In order to test the interface conditions between concrete and rebar, the propagation properties of ultrasonic guided waves (UGW) are explored. Numerical methods are employed to calculate the disperse curves. Optimal excitation signal and frequency are selected. Then UGW test installation is designed to test the prepared specimens, which include different artificial defects. Time-domain and frequency-domain analysis are employed in processing the received signals. In order to obtain more accurate correlation, energy attenuation parameter is proposed, and the linear curve was obtained. This study indicates UGW is an accurate tool in evaluating the condition of interfaces between concrete and rebar on the condition that frequency and modes are properly selected. Also promising is the UGW technology being used in non-destructive test of reinforced concrete.
The theoretical basis of the moiré fringe signal quality detecting by observing the figures
Jie Yi, Li-min An, Chun-xia Liu
The moiré fringe signal quality decides the precision of the encoder. In the production process of RESR, usually, the moiré fringe signal quality is detected by the Lissajou graphs observing by the oscilloscope. Lissajou graph is the common method for analyzing the dc level of two analog signals, the amplitude of alternating current, the phase of signal, the relation of frequencies and other parameters. It is convenient, intuitive, and would not be affected by the rate; furthermore, it applies to be used for field detection. The ideal moiré fringe signal has two sine signals which phase difference is 90°, and prefect round Lissajou graph. However, in practice, for a variety of factors, moiré fringe photoelectric signal has dc level, higher harmonic, orthogonality deviation, equal amplitude deviation, and so on; that is why Lissajou graph will appear offset or distortion. So we can observe the shape's deviation of the Lissajou graph in order to judge the signal deviations. This paper introduces the diameter deviation to describe deviation between the Lissajou graph of actual signal and the Lissajou graph of ideal signal, establishes the mathematical model of diameter deviation, and theoretically analyzes the relationship between the diameter deviation and the parameters of moiré fringe photoelectric signal. Using the VB6.0 simulation software to prove the results of the theoretical analysis, we find that the simulation results agree with the previous detection, which supply theoretical foundation for the observation of Lissajou graph. After analyzing the character of the encoder's signal when the encoder works in a uniformly accelerated motion, we point out the applicative conditions of the observation of Lissajou graph detecting moiré fringe signal. The conclusions of this paper have important significance for detecting the signal quality of encoder, and have certain reference value for detecting other signals.
Study on modeling and filtering of random drift on FOG
Dong-jian Duan
At present the precision of fiber optic gyroscope (FOG) is so lower that it is necessary to analyze the performance of FOG and set up its drift error model to raise the precision. There are many noise source in FOG, these noise sources and environment intrusion cause many random error terms, such as bias instability, angular random walk,rate random walk and rate ramp. It is impossible to adopt general analytical method (such as calculating mean and covariance) to confirm these random errors. Now, the precision of FOG made in our country is low and to improve it cost high and is difficulty. So this paper improve the system precision by software in the error modeling and filtering of the FOG random drift. Now, the main method to minish the FOG random drift is Kalman filter. In this paper,the FOG drift data is processed by Kalman filter,and the effect of filtering is analyzed. The simulation result show that Kalman filter can minish the FOG random drift more simply and more efficiently. Because the Kalman filter is based on the steady time series model of FOG random drift, in this paper, FOG random drift data is validated to be a non-stationary time series, so the unsteady sample of FOG drift needs statistical test and corresponding pretreatment using stochastic signal processing methods, and then the mathematical model is establishing by time series analysis theory. It is proved that the random noise can be represented by a single equivalent ARMA(auto-regressive moving average) or ARIMA model that is simple to implement. The data pretreatment is made, the model is identified,the method of using long autoregression method to estimate the coefficients are studied. In the end, experimental modeling of the FOG random drift is carried out, the random noise of FOG is processed by using Kalman filter. Experimental results demonstrate that the performance of the filter is feasible and the model can reject the random noise of FOG.