The theoretical model is established for photonic crystal fiber (PCF) intrinsic Fabry-Pérot (F-P) interferometric fiber pressure sensor, and its pressure responsibility, related to several parameters, is also discussed with the results simulated by Matlab software. The improvement of single/multi-mode intrinsic F-P interferometric fiber pressure sensor is demonstrated by theoretical analysis, which is easier to fabricate. The structure is constructed by fusing single-mode fiber and multi-mode fiber with different diameters. The theoretical model of pressure response is also given. The key parameters concerned with pressure responsibility are analyzed with simulation curves. By the comparison between two kinds of sensors, the single/multi-mode intrinsic F-P interferometric fiber sensor is more attractive because of its high responsibility and simple fabrication.

The Levenberg-Marquardt (LMA) is used for the demodulation of absolute Fabry-Pérot (F-P) cavity based on the optical fiber white-light interferometry that is more efficient than cross correlation algorithm. High immunity to the perturbation of the source power is achieved by its Gauss-fitting and setting limitation to the parameters of LMA. Signal data selection principle is discussed and standard deviations of experimental device and LMA under the perturbation of power are measured.

The three-dimensional (3D) reconstruction technology based on machine vision is researched. We use the pictures shot by ordinary digital cameras to achieve 3D reconstruction through camera calibration, feature-point detection and matching, and the calculation of fundamental matrix and essential matrix. We complete the camera calibration by Camera Calibration ToolBox for Matlab based on Zhang Zhengyou′s method. The scale invariant feature transform (SIFT) method is used for image feature-points detection and matching, and the random sample consensus (RANSAC) algorithm is adopted to calculate the fundamental matrix and the essential matrix. Then we use the camera internal parameters got in advance and the essential matrix obtained from the fundamental matrix to reconstruct the feature points of the objects and achieve the 3D effect by pasting pictures of texture. The experimental results show that it can complete the reconstruction and can well reflect the 3D feature of the objects.

In lots of cases, it′s difficult to obtain appropriate image training set, but single-image zooming is an ill-posed problem. Using the self-similarity feature among local structure in an image which can be maintained in the scale space and the advantage of nonsubsampled contourlet transform (NSCT), a single image super-resolution reconstruction (SRR) algorithm based on image analogies and NSCT is proposed. NSCT is performed on the original image and the degraded image at different scales and directions, thus varieties of directional bandpass subband pairs are obtained. The relationships between the subband pairs by image self-analogies are learned to generate high resolution varieties of directional bandpass subband. The super-resolution reconstructed image is obtained by transforming these changed subband coefficients and the zoomed-original image by bicubic interpolation back to the spatial domain. The experimental results show that the algorithm can be executed independently without any supposed outliers. It can generate more reasonable details than general methods, thus the edges are much clearer and the image is more natural-looking.

A range-gated underwater imaging system is designed for solving the problems in detection in shallow waters. The system is built around a pulsed 532 nm NdYAG laser and a self-made gated intensified charge-coupled device (ICCD) camera, and the laser pulse is used as the trigger for sync control of the system. The camera gating is timed to collect light reflected from the target to produce the target in the image. The range-gated underwater laser imaging experiment is done based on the sync control circuit designed by field programmable gate array (FPGA) technology. The experimental results indicate that the laser pulse jitter can be restrained by using laser pulse as trigger. As a result, water surface reflection and water backscattering are eliminated effectively and the imaging quality is enhanced. It is also proved that the imaging depth of the system is 7 m in the lake whose effective attenuation coefficient is 0.52 m-1, and the target can be effectively detected and recognized in shallow waters.

Modulation transfer function (MTF) is an important imaging quality indicator of optical system. On the basis of MTF testing theories, knife edge and slit as testing targets, a testing system which has low cost, simple structure, but high precision and high stability is developed to evaluating MTF of industrial lens. Besides, a correlative testing software is built according to the above. This testing software basing on the principles of the automatic focusing, and giving consideration to efficiency and precision, includes an automatic focusing system which rough focusing uses the method of mountain climbing as search algorithm, and which elaborate focusing uses the traditional method as search algorithm. In addition, different focusing evaluation functions are used in sharpness evaluation according to the trait of objective. Experimental data indicates this MTF fast testing system has high stability.

Lunar laser ranging (LLR) has the characteristics of far measurement range and small number of return laser photons, so the position of detector receiving return photons should be adjusted properly during LLR observation to improve the detection success probability. Synchronization control system for multiple step motors is researched and realized with the technique of field programmable gate array (FPGA), and control interview program is developed with VC++ software developing instrument. Finally, computer control of the detector position is realized on xoy detecting plate. Test result indicates that two step motors can run separately or simultaneously, so that the detector could move along x axis or y axis alone, or along x axis and y axis at the same time. The minimal step length is 2.5 μm, which allows for precise detector position control.

On the basis of previous work that oil spill polarized light detection methods, the polarization station of reflected light in in the Poincare Sphere is analyzed, and physical analysis of the detection methods is given. Using linearly polarized light as incident light, with the incidence angle near the Brewster angle, the trajectory of reflected light polarization state in the poincare sphere is used to identify different types of oil、 water、 oil film thickness. In further, experiments are condusted with 650, 850, 1064, 1310 and 1550 nm wavelengths linearly polarized light and different oil, and experimental results and physical analysis are well confirmed.

According to the requirements of resolution of nanometrology, a confocal Fabry-Pérot (F-P) interference microscopy probe is designed. The laser source is directly conveyed into the system by the single polarization-maintaining fiber, and passes through F-P cavity. In order to reduce the optical common mood noise, the differential optical path is designed. Through the establishment of model, the physics characters of the system are analyzed. The best reflectivity of the reflection plate can be obtained and how the confocal impacting the interference process can be found. The experiment results show that the system can get interference fringes with high-contrast and high signal to noise ratio when the reflectivity of the reflection plate is 40%. Pinhole aperture is favorable for finding the focus of the measure lens and reduces the noise of stray light. The axial resolution of the system can reach up to 0.2 nm.

Signal-to-noise ratio (SNR) of lidar system affects directly the quality of the range image and intensity image. Using the theory of signal correlation detection, SNR of non-scanning lidar system is analysed under multi-pulse-accumulation condition. Simulation and analysis of SNR are conducted under considering APD arrays, work environment factors, lidar system parameters. SNR is improved by 9.35 dB under 100 pulses accumulation, and the sequential improvement is not obvious with increase of pulse accumulation. It is shown that SNR of lidar system can be improved by using pulse-accumulation method.

Narrow linewidth semiconductor lasers are widely used in the field of radar and sensor. So the research of narrow linewidth laser is necessary. Using electric feedback structure, and with a frequency discriminators, the center wavelength is stablized. The laser from frequency discriminators is converted to current by photoelectric detector. Different signals of inherent detector and the current are injected into laser to reduce the frequency noise. So the laser line width of 0.5 nm reduces to 0.08 nm.

According to application purposes concerning focusability of laser energy, three kinds of lasers, i. e., the annular lasers generated from unstable resonators, Gaussian lasers generated from stable resonators and combined lasers of several Gaussian lasers are taken as analyzing objects. The advantages and drawbacks of beam quality parameters available are discussed, and some key issues on definition of beam quality are calculated and analyzed. The results show that, the parameter of laser brightness or laser energy density on the target is a very important standard for evaluating the performances of laser systems, which is suitable for measuring performance of the same system, as well as different systems objectively.

Angular drift is one of the most important parameters of the optimization of microchip lasers′ design and application, but such drift data haven′t been reported. A measurement system of angular drift based on the four-quadrant photodetector and the LabVIEW software platform is developed to realize the real-time operation to angular drift signal, including display, reading and recoding. This system realized the measurement of angular drift′s order of magnitude and the variation regularity with pump power, provided the basic data for the optimization of microchip lasers′ design and application.

According to the “element life and death” technique of finite element method, with ANSYS parametric design language (APDL), we simulated the effects of long edge reciprocating scanning method, short edge reciprocating scanning method and direction orthogonal changing in different layers reciprocating scanning method to thermal-stress couple field and residual stress distribution during whole laser metal deposition shaping (LMDS) process. The dynamic regularities of thermal stress, temperature and residual stress distribution under different scanning methods are studied in detail. With the same process parameters, the samples fabricated by LMDS show good agreement with the simulation results.

Deep-ultraviolet photoluminescence technique is used to investigate the band gaps of AlxGa1-xN epitaxial films. The bowing parameter of AlxGa1-xN is studied by CASTEP module of Material Studio simulation software and the Al molar fractions of AlxGa1-xN epitaxial films are researched. The result shows that the HeAg laser with 224.3 nm emission wavelength can make AlxGa1-xN material produce luminescence. The bowing parameter of AlxGa1-xN epitaxial film is calculated with CASTEP software simulation to be 1.01462±0.06772 eV, from which we can calculate the Al molar fractions of AlxGa1-xN epitaxial films.

The Laplace Transfer-current density convolution (LT-JEC) finite difference time-domain (FDTD) method is used to deal with the complex magnetized plasma. By using the periodic boundary condition, the abstract model transfers into the practical model which can be calculated by FDTD. The plasma photonic crystals consist of the media embedding in the plasma .The algorithm is applied to calculate their power reflection and transmission coefficients of the different plasma parameters, and some useful conclusions are obtained. This work provides theory basis to make the practical plasma photonic crystals.

Chaos control and synchronization in long-delay electrical-optical bistable systems are researched through modified active-passive method. Unidirectional driving method and driving-coupling method are used in the study on chaos control and synchronization, respectively. The results of numerical simulation show that the chaos of driven system is controlled by the driving system through unidirectional driving method. The driven system′s periodic state lies on the driving system′s periodic state. By adjusting the driving intensity and the coupling coefficient, the chaos synchronization is realized between the driven system and the driving system with these two methods. The effects of driving-coupling method are better than those of unidirectional driving method. Driving-coupling method needs less coupling coefficient and has a larger range of effective coupling coefficient.

A theoretical investigation is carried out into the Kerr nonlinear effect of an asymmetric double quantum dots system. Using voltage tunneling, electromagnetically induced transparency can appear synchronously at two different frequency windows. By tuning tunneling voltage and control field suitably, the absorption property is significantly modified and therefore the enhanced Kerr nonlinearity without liner and nonlinear absorption occurs at one of the transparent windows. Analysis shows that voltage controlling between two quantum dots is key factor of the enhancement of Kerr nonlinearity.

One grand challenge of silicon-based microchannel plate (MCP) fabrication is to make the micro-pore array of high aspect ratio on the silicon wafer. Photo-assisted electrochemical etching technique is used to make such micro-pore arrays on n-type silicon substrate. Considering that the influences of matter transportation, solution concentration, illumination and temperature are reflected by the etching current and voltage under the actual etching conditions, the research is focused on the effects of the etching voltage and current on the morphology of the micro-pores. According to the structure and morphology of deep etching pores, the current, voltage and illumination are modified. Finally, the micro-pores of depth over 200 μm are fabricated on a 5 inch (1 inch=2.54 cm) silicon wafer. The large-area uniform pore array of high-aspect ratio is obtained. It meets the structure parameter requirements of MCP post-production.

It briefly describes the radio-frequency identification technology (RFID) middleware and its current research, based on the study and analysis of the limitations and inadequacies of the existing food tracing system; it designs a layered RFID middleware architecture, and conducts an in-depth study. Layered middleware shields the differences of different devices, centralizes to manage distributed reader devices, according to a protocol rule to filter large amounts of the redundant data; and extract semantic information using publish-subscribe model for the more efficient, real-time information sharing mechanism.

Because of the characteristics of low density and good recycle, magnesium alloys are praised of the green engineering material, which have a widely applied prospect in the fields of automobile, motorcycle, aerospace and other industries. But the welding problem has become a key constraint on their application. Laser welding will be an important joining technique for magnesium alloys with their increasing applications. Compared with other fusion welding techniques, laser welding is one of the ideal methods for magnesium alloy because of its characteristics such as deep penetration of welds and excellent performance of joints. To date, two types of industrial lasers, i.e., CO2 and Nd:YAG lasers, have been used to investigate the weldability of magnesium alloys. In this paper, the process methods, welding materials, joint properties (mainly for mechanical properties and corrosion resistance) and metallurgical defects (mainly including porosity and cracking) of laser welding of magnesium alloys are analyzed. The research status of laser welding of magnesium alloys at home and abroad is summarized. The development trends of research and application of laser welding of magnesium alloy are reviewed.

Computer-generated hologram (CGH) dynamic three-dimensional (3D) display is one of the hot areas in optical science and application. The research development of the CGH dynamic 3D display is reviewed. The computational complexities, relation between reconstructed image size and viewing angle, and the influence of the main factors on quality of reconstructed image are introduced. The methods of reconstructing 3D image with high quality, big size and wide viewing angle are analyzed. Prospect of holographic dynamic 3D display is also given.

High-temperature resistant fiber gratings have attracted lots of research interest in recent years due to their potential applications in several industrial and military areas such as aerospace, missile and smelting. Their research development is introduced by classifying them into five types, including type-Ⅱ gratings, type-ⅡA gratings, chemical composition gratings (CCGs), special ion-doped fiber gratings and structural modification-induced long period fiber gratings. The fabrication methods, high temperature performances, and merits and drawbacks are reviewed. Their future developments and applications are discussed.

According to the development roadmap of airborne laser test bed (ALTB) and the evaluation results of its battlefield effect made by scholars from Germany and USA, the foreground of ALTB against missile and satellite is favorable and encouraging, whereas there is still a long way to go to deploy and employ it on future battlefield. Based on the near-term development and experimental results, we point out the main factors which have significantly negative influences on the long-range strike capability of ALTB.

Since the terahertz time-domain spectroscopy has been developed, there-has been great interest in the fabrication of terahertz waveguides, especially flexible and low-loss ones. Firstly, terahertz time-domain systems are introduced, and some shortcomings of conventional waveguides are summarized. Three working mechanisms of novel terahertz waveguides are presented in details, including reflection from metal surface, total reflection from the interface of two dielectric media and anti-resonant reflection. Characteristics of these waveguides are discussed. At last, some applications about flexible and low-loss terahertz waveguides are demonstrated, and continuing research is introduced.

With the development of THz imaging technique, there have been great demands for the improvement of THz imaging performances such as imaging resolution, imaging speed, image dimension, etc. To eliminate the influence of diffraction on imaging results and to improve the performance of THz imaging system, a lot of researchers have turned their attentions to THz digital holography. Firstly, some fundamental theories for THz digital holography are briefly introduced. Then a comprehensive description on the advances in the domestic and international research of THz digital holography is povided. These investigations exhibit that THz digital holography has great potentials to improve the imaging resolution and extend image dimension, etc. Moreover, THz digital holography has the capability of real time imaging. Those characterizations make THz digital holography a promising technique which has an exciting application and development prospect.

The reflection spectra of the one-dimensional (1D) photonic crystal is researched with the transfer matrix method. The variation characteristics of bandgap of TE and TM modes with rectangular size were analyzed in detail. The results indicate that single mode propagation of the highest mode can be obtained in 1D rectangular restricted photonic crystal, and the smaller the size of rectangular is, the easier single-mode propagationis. The structure with X=1 and Y=1 is the best one.

Two-dimensional performance of uniform irradiation with the smoothing by spectral dispersion (SSD) and distributed phase plates (DPP) is researched on the SG II laser facility. The results of experiments in free space show that 1D-SSD makes the root mean square (RMS) focus drop to 0.3685 from 0.7634 (without SSD), and 2D-SSD supplied RMS is 0.2638. Other appraising methods of focus verify the conclusion. This experiment is especially meaningful for on-line 2D-SSD experiment.