Optical phased array (OPA) can realize beam scanning in space with no need of mechanical rotating. It has a universal application prospect in many fields, such as laser ranging and free-space optical communications. Silicon-based optoelectronic integration technology can integrate large scale optical devices on the chip and fully compatible with CMOS integrated circuit technology. OPA based on this technology has the characteristics of fast scanning speed, small volume, low cost and low power consumption. At present, the maximum of scan range of OPA fabricated by silicon-based optoelectronic integration technology is 80° in horizontal direction and 36° in vertical direction. We briefly introduce the scanning principle of OPA. The newest research results at home and abroad are summarized and analyzed. Finally, the key issues that need to be solved are discussed and some solutions to improve performance are proposed.

Based on confocal imaging principle, the confocal line scanning imaging technique uses the one-dimensional scanning-line beam to illuminate the sample for increasing imaging speed. A confocal slit is used to filter the stray light from unfocused-level for improving imaging resolution and contrast ratio. Recently, the confocal line scanning imaging technology is becoming more and more popular in biomedical imaging because of its advantages such as high imaging speed, high imaging resolution, simple system structure, and so on. We introduce the basic principle of confocal line scanning imaging, and list main parameters of the imaging system and their influencing factors. Then the application in biomedical imaging especially in fundus imaging and biological tissue cell observation is illustrated. Advantages, disadvantages, and application prospect of the technique are finally summarized.

Thulium-doped fiber lasers (TDFLs) have been applied in extensive areas, such as medical treatment, plastic welding, lidar, and optical-parameter-oscillation (OPO). In this paper, the research progress of Tm3+-doped silica fibers and high power TDFLs is presented and the bottlenecks of TDFLs are discussed and analyzed. Adjustments and optimization are promoted from three aspects including fiber design, laser structure and pump approach, and high power TDFLs will be achieved by improving thermal management and non-linear effect.

Orbital angular momentum (OAM) is a natural property of beams with spiral phase. OAM beams with different topological charges are mutually orthogonal. OAM beams can be applied to OAM multiplexing as a new information carrier based on their orthogonality. OAM multiplexing greatly improves the channel capacity and spectrum efficiency without additional bandwidth. Owning to its excellent properties, optical fiber has become the best choice in modern communication network. OAM multiplexing based on optical fiber has attracted widespread concern of researchers. We introduce the basic principle of OAM firstly, and then discuss the research progress of the optical fiber, which is suitable for carrying OAM beam, OAM beam generation and detection methods, related devices and experiments of OAM multiplexing technology and so on. Finally, the existing problems and trends of the current technologies are discussed.

Compared with the traditional edge emitting semiconductor lasers, the vertical cavity surface emitting laser (VCSEL) shows many advantages, such as good beam quality, low threshold current, easy fabrication in two-dimensional arrays and low cost. In recent years, the electrically pumped and optically pumped vertical external cavity surface emitting laser (VECSEL) developed on the basis of VCSEL is a very competitive light source in the laser field. It can realize intracavity frequency doubled, tunable wavelength and mode-locked lasers technology by inserting corresponding optical element within the cavity, and obtain high output power and beam quality. We introduce the structures, working principles and performance advantages of VCSEL and VECSEL. The research status and latest progress including high power, tunable operation, and mode-locking lasers are reviewed. The development prospect of VCSEL and VECSEL are discussed.

Research and application of deep learning in recovery of three-dimensional structure from image or video, depth estimation, and real-time localization of visual sensor are introduced. Research progress of deep learning is overviewed. According to whether there is supervision, some representative deep learning algorithms and systems are introduced individually with deep analysis and comparison. Finally, the research spots on deep learning in recent years are discussed, conclusions are presented, and some research tendencies are discussed.

The traditional optical interference measurement method is relative detection method, and the detection accuracy is generally limited by the accuracy of the reference surface shape. The use of absolute detection technology can eliminate the constraint of the reference surface shape error on the interference measurement accuracy, which can realize the measurement of the surface shape in nanoscale. Firstly, N bit rotation average absolute detection method and oblique incidence absolute detection method are introduced. Then the theoretical derivation and simulation analysis of two detection methods and three algorithms (rotation average algorithm, iteration algorithm, odd even function algorithm) used in the process of surface restoration are carried out. Finally, the recovered surface shape accuracy and feasibility of the three methods are verified by the experiments. The advantage, disadvantage and applicability of each method are analyzed and compared. At last, the absolute surface measurement of mirror with aperture of 100 mm for high precision interferometer standard flat with peak valley (PV) value of nearly λ/40 is achieved.

The accelerator grid voltage of the ion thruster has an impact on the intensity of the current of accelerator grid. At present, the accelerator grid voltage is chiefly determined through multiple experiments, and the theoretical calculation can only provide the maximum value of accelerator grid voltage. In this paper, the optimum design of the accelerator grid voltage for a dual-stage accelerator ion thruster developed by Lanzhou institute of physics is carried out. Using particle-in-cell method and Monte-Carlo collision method (PIC-MCC method), the effects of five accelerator grid voltages (-150, -180, -200, -250, -300 V) on ion trajectory, beam divergence angle, number and energy of the impingement charge exchange (CEX) ion, and accelerator grid sputtering rate are studied with the specific impulse of 8000 s. The results show that the best accelerator grid voltage is -250 V. Finally, the verification experiment is carried out. The results show that when the accelerator grid voltage is around -250 V, the current of the accelerator grid is small, which verifies the correctness of the numerical simulation.

To accurately extract the features from massive laser scanning point cloud data, a feature extraction method of laser scanning point cloud based on morphological gradients is proposed. The method first generates the digital elevation model of massive laser scanning point cloud, and then obtains the gradient of each laser footprint by mathematical morphology theory defined by mathematical morphology. The mean value of gradient local nearest points is used as local adaptive threshold. The point cloud data is divided. The characteristic part and the flat part are generated. The random sample consensus method is used to fit the plane from flat part and circles from characteristic part, then the characteristic information such as the height of the step and the radius of the hole is obtained. The experimental results show that the proposed method can effectively extract the features of massive point cloud data. The maximum error of the circles' radius is not more than 0.05 mm, and the minimum error of the step height is not more than 0.1 mm.

Large trough solar reflector surface has large size and high measurement accuracy requirements, which needs high precision measurement method to reconstruct its 3D shape. In order to improve the detection accuracy and efficiency of the large trough solar reflector surface, a large trough solar reflector shape detection method is proposed and implemented based on large scale photogrammetry technology. In the view of the large trough solar reflector surface, at first the convex envelope detection method is used to select non-collinear image points, then the five points relative orientation method is used to solve the relative external parameters of the cameras and the bundle adjustment method is implemented for the optimization iteration of 3D coordinates of measuring points. Finally, the information of the parabolic surface fitted by the measuring points and the design parameters of the reflector are compared and analyzed, then the shape detection of large trough solar reflector surface is completed. Using the proposed method, a measurement experiment is conducted on the trough solar reflector with the size of 12.0 m×5.7 m×1.4 m, the results show that the root mean square error of the measuring points on the reflector is less than 0.033 mm, the average z-axis error and the standard deviation of the fitted parabolic surface are 1.050 mm and 1.466 mm, respectively. These data can meet the surface shape detection accuracy requirements of large trough solar reflector, and the feasibility of the photogrammetry method is verified.

A highly stable acousto-optical Q-switched 532 nm Nd∶YAG laser based on a type Ⅱ LiB3O5(LBO) crystal intracavity frequency-doubling is demonstrated. Average output power of 126 W of green laser is obtained at a repetition rate of 12 kHz for acousto-optical Q-switched laser. Test results show that the pulse width is 52 ns, which corresponds to a pulse energy of 10.5 mJ and a peak power of 205.9 kW. The diode-to-green optical conversion efficiency from 808 nm to 532 nm is 9.19%. The LBO crystal's temperature is precisely controlled by a temperature control furnace with the precision of ±0.1 ℃, which directly contributes to the high efficiency high-stability second harmonic generation. The output power of the green laser is very stable. The root mean square instability of green laser at 126 W is calculated to be ±0.628% in 3 h of continuous work.

A dual-cavity stable control scheme for regenerative mode-locking fiber laser is proposed. The scheme uses phase-locked loop to detect the microwave frequency drift caused by cavity length change of resonant cavity and realizes feedback compensation with piezoelectric ceramic. We use a microwave mixer to compare the phases of two microwave signals with the same frequency in photoelectric regenerative chamber. Cavity change is obtained and compensated by phase shifter. In this study, the regenerative mode-locking fiber laser outputs optical pulses with repetition frequency of 10 GHz and pulse width of 16.6 ps. The optoelectronic regenerative cavity outputs microwave signal with repetition frequency of 10 GHz,side-mode suppression ratio of 40 dB, phase noise of -127 dBc/Hz and the frequency shift smaller than 1 Hz in 70 min. Compared with the present regenerative mode-locking scheme, the proposed scheme can control cavity lengths of optical resonator and optoelectronic regenerative cavity simultaneously, and can output microwave signal with stable frequency and high quality pulse. The regenerative mode-locking fiber laser can work stably for a long time.

The AZ31 magnesium alloy and TiB2 enhancement aluminum matrix composites are welded by a pulsed laser and the microstructures, the properties of corrosion resistance,hardness and so on for the welded joints are investigated. The effect of the addition of TiB2 interlayers on the performance of the welded joints is studied. The results show that, when the single point energy of the pulsed laser is 36.15 J, the parameters are defocusing, pulse frequency and welding speed sorted from the greatest to the least according to their influence degrees on the weld formation. Under the optimal welding parameters, there are equiaxed grains and no obvious defects in the weld zones of joints. There exist layered abundance zones on the top of the weld beams and Mg17Al12, AlMg, Al3Ti intermetallic compounds in the middle of the weld beams. As for the corrosion resistance rate, that of TiB2 enhancement aluminum matrix composite is the strongest, that of the weld microstructure is the next, and that of the AZ31 Mg alloy is the weakest.

A high-power and high-pulse-quality femtosecond all fiber laser amplification system is constructed based on the negative third-order dispersion compensation with fiber chirped pulse amplification technology. In the proposed system, the polarization maintaining large mode field of the double-clad Yb-doped fiber and the negative third-order dispersion fiber and the normal polarization maintaining fiber are utilized as the gain medium and mixed fiber stretcher, respectively. Moreover, a pre-compensation of third-order dispersion is implemented while the widening of the time domain is realized, therefore a high-quality and high-power laser is obtained. In the experiment, we use the hybrid fiber stretcher and a 1200 line·mm-1 grating-pair as the compressor, and make the net third-order dispersion of the system approach zero. Consequently, we obtain a high-quality dechirp pulse with central wavelength of 1035 nm and pulse duration of 217 fs. In addition, average output power of 8.5 W at repetition rate of 111 MHz is achieved.

The laser cladding layers on the 27SiMn steel surface are obtained by the preset powder feeding method, and the heat treatment to these cladding layers is also conducted. The microstructures, phase structures, tensile properties, fracture morphologies and microhardness specimens before and after heat treatment are investigated, and the better heat treatment process parameters are obtained. The results show that the heat treatment process can refine the grain size of cladding layers, which makes microstructures denser. The heat treatment process can improve the plasticity and toughness, which enhances the tensile strength and reduces the microhardness of materials. Under the optimal heat treatment process, the grains of specimens are refined and homogeneous, and the tensile property is superior.

The geometrical optics theory is adopted to analyze the change of light transmission mode in tapered fiber, and multimode transmission is achieved when tapered fiber diameter is in the range of 1.135-60 μm. Tapered fibers are fabricated with fused biconical taper system. The relationship between the tapered fiber radius and the stretching length is obtained by Origin software. Under the given conditions, tapered fiber with waist diameter of 2.475 μm is fabricated when the stretching time is 95 s. The transmission performances of tapered fiber with waist diameter of 2.475 μm are simulated by the BeamPROP module of RSoft. We use amplified spontaneous emission (ASE) optical source to measure the output optical power change with wavelength in 1530-1580 nm. The tapered fiber is inserted into the ring cavity, and the polarization state of the signal light in the cavity is changed by the polarization controller to realize wavelength tunable in the range of 1563.828-1565.444 nm. The side-mode suppression ratio is 51.4 dB, and the double wavelength output with a maximum wavelength interval of 1.48 nm is achieved while the side-mode suppression ratio is 49.8 dB.

In order to reduce the molecular weight of konjac glucomannan (KGM), and enhance its application in the fields of food, medicine and materials, we adopt the laser combination with hydrogen peroxide to degrade the KGM solution of 0.01 g/mL. Viscosity meter and rheometer are used to determine the better degradation conditions, and then differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopy are used to characterize the selected KGM degradation products, and the degradation mechanism is studied preliminarily. The results show that the viscosity of KGM decreases from 7.2 Pa·s to 3.17 Pa·s when the laser power is 10 W, the volume fraction of hydrogen peroxide is 1.5%, and the treatment time is 2 min. For the KGM obtained under the above condition, the intersection point of storage modulus and loss modulus moves backward, the intermolecular entanglement weakens and the molecular mass reduces. The temperature corresponding to thermal absorption peak of DSC increases from 301 ℃ to 326 ℃, and the thermal stability rises. There are no significant changes in the infrared spectra of KGM before and after degradation, and the characteristic functional groups remain unchanged. This study can provide a new idea for the effective degradation of KGM.

The structure design demands of lift platform used in certain environment are studied based on the interface dimension of the bottom load optomechanical module of amplifier. The calculation model of the lift platform is designed based on the equal strength beam theory. The stiffness formula of variable cross-section platform structure is deduced, and the main structural parameters of the lift platform are calculated based on this stiffness formula. The 3D model of the lift platform is built based on ANSYS software and the structural mechanics analysis of the lift platform is carried out, then the rationality of the theoretical design parameters is verified by the analysis results. On the premise of improving the safety factor, the 3D model of the platform is reconstructed with ANSYS software and the stiffness redundancy analysis of the platform is carried out. For the sake of getting the lightest quality of the lift platform, the main structural parameters of the lift platform are optimized by using the global optimization tool of the ANSYS software. The optimization results are applied to the production of a vertical lifting mechanism sample of a system.

The principle of three-dimensional(3D) laser scanning technology for deformation monitoring is to analyze the point cloud data measured at different time intervals and determine the deformation area and the deformation amount in the monitoring object based on the contrast of the obtained data. Compared with the traditional single-point measurement technology, the 3D laser scanning technology has advantages such as high efficiency, high precision and large amount of measurement data. However, no evaluation is made on the reliability of monitoring results when applying this technology for deformation monitoring. Therefore, it is necessary to analyze the point cloud error and determine the indicators of point cloud deformation monitoring. In determining the point cloud error space, we introduce the error entropy to eliminate the influence of the error between adjacent points and control the influence of the uncertainty of the error space. According to the relationship between the error entropy and the extreme value of the error, the indicators of point cloud deformation monitoring can be finally determined. The feasibility of the indicators are verified based on the flat panel simulation experiment, and then applied to the bridge deformation monitoring.

In the high-speed optical communication network, the present optical network switching capability and transmission capability are seriously unbalanced. Therefore, building all-optical network (AON) is an effective way to solve the problem. However, all-optical packet switching technology has not been achieved due to immature all-optical logic devices. The all-optical 2-to-1 data selector is proposed based on sum-frequency generation SFG+DFG and difference-frequency generation (SFG+DFG) in quasi-phase-matched cascaded periodically poled lithium niobate (PPLN) waveguides. The waveforms and the eye diagrams are obtained by numerical calculation and simulation, and the performance of the data selector is analyzed by the parameters such as pulse width, extinction ratio and peak power delay time. The results show that the signal light is processed using the PPLN waveguide cascade method. It can not only complete the corresponding logic function, but also can guarantee the transmission quality of the signal, which expands the capability of PPLN waveguide on the all-optical logic signal processing.

Based on the angle hole burning model, the transmission characteristics and formation condition of spatial optical soliton through photoisomerization are studied. Under the background light, the relationship between the refractive index and the light intensity is studied by MATLAB. According to the change law of refractive index, the forming conditions of soliton are discussed. The results show that the refractive index change can be positive or negative with the background light, and the bright soliton and dark soliton can be formed.

We present a novel technique of temperature compensation for 3-dimensional fiber Bragg grating (FBG) strain sensor, and design a temperature compensation diaphragm for temperature compensation of the strain sensor by using reference optical fiber compensation method. Experiment results demonstrate that bare fiber without aging process can appear inflection temperatures between 30 ℃ to 40 ℃, which results in the decrease of the temperature sensitivity coefficient. So we must make aging process firstly before encapsulation to improve the sensitivity of the sensor. Based on the finite element thermal analysis, it is found the designed temperature compensation diaphragm's maximum strain is about 0.073 με when the temperature is increased from -10 ℃ to 50 ℃, which demonstrates the thermal expansion coefficient mismatch has less influence on the diaphragm and this system has high temperature reliability. Besides, sensing accuracy of the fiber sensor is improved by the design of cantilever structure, which makes the sensing immune to the complex environment. We fit and revise the results of joint compensation between temperature compensated diaphragm and the strain sensing diaphragm by the origin. The results show that the sensing linearity can reach more than 0.9999, and the full range accuracy is about 0.05%.

Aiming at the problem of low indoor visible light positioning accuracy, a positioning algorithm based on the received signal strength and arrival angle (RSS/AOA) information in indoor three-dimensional space is proposed. Based on the least squares (LS) criterion, the distance and angle are considered at the same time, a novel hybrid objective function is constructed, and then the least square estimator of location information is derived. For the non-convex objective function, the objective function is transformed into generalized trust region sub-problem (GTRS) to solve the global optimal solution. The simulation results show that in the 5 m×5 m×3 m two-dimensional positioning space, 20×20 test points are selected, for which the average positioning error is 8.7 cm. In addition, it can realize dynamic positioning and tracking in the three-dimensional space. The results show that the algorithm can obtain high accuracy in horizontal and vertical directions.

In view of the characteristics of cross-sensitivity between strain and temperature of fiber Bragg grating(FBG), the temperature-compensation FBG structure is in series with strain FBG structure based on holder type packaging. The structure strain can be acquired by the relative wavelength shift between temperature FBG and strain FBG. The experimental results indicate that temperature sensitivity induced by relative wavelength shift is only 0.12 pm·℃-1, which is 1.14% and 1.15% of temperature sensitivity of temperature FBG and strain FBG. The FBG strain measurement possesses good performances on temperature compensation. The principle of FBG strain sensing measurement technology with holder type temperature compensation is simple, and the operation is convenient. It can be applied widely to practical engineering.

A kind of enhancement micro fiber Bragg grating (FBG) strain sensor is used to test static pressure precast pile force during precast pile driving. We make a groove on the surface of the model pile body to bury FBG strain sensor, use static pressure precast pile penetration model experiment to test stress states in real time, and analysis profiles of axial force of pile shaft and side friction of pile with embedded depth. Experiment results show that the enhancement micro FBG strain sensor can be embedded well with model pile and can test stress states of model pile exactly. In addition, this kind of FBG sensor shows advantages of high prefabricated success rate and easy installation.

Based on the polarization detection principle and the polarization characteristics theory of reflected light, a divided aperture simultaneous type hyperspectral polarization imaging system is used to analyze hyperspectral polarization characteristics of objects under different illumination intensities and different observation angles. Taking desert camouflage net, desert camouflage board, tank shrinkage ratio target and hummer shrinkage ratio target act as the objects, which adapts to the desert background. We give a typical detection wavelength selection range of camouflage target under desert background. The analysis results provide a scientific guidance to achieve better camouflage target detection in desert background.

Surface defect detection plays an important role in the selection and utilization of wood. A method is proposed for knot defect detection and localization based on the feature of gray and texture on the wood surface. First, the image is divided into blocks with equal sizes. The gray histogram of each subimage is calculated, and the gray maximum entropy is used as the criterion to achieve the preliminary recognition of the subimage. Second, the texture features of the preliminary result are extracted by local binary patterns algorithm. The support vector machine classification algorithm is utilized to precisely recognize the knot images. Finally, the subimages judged as knot images are joined together to obtain the final result. The experimental results show that the proposed method can obtain commendable recognition results. The knot recognition accuracy reaches 95% when confusion matrix is used as the evaluation criterion.

The segmentation of point cloud play a key role in the processing of point cloud data, the regional growth is widely used in three-dimensional point cloud segmentation because it is easy to implement and use. However, due to the uncertainty of the point cloud characteristics and the unreasonable selection of seed point, the traditional regional growth method has the instability of local segmentation performance. To resolve this problem, an improved method of regional growth segmentation is presented, we set the minimum curvature point to the seed point by estimating the magnitude of the curvature of point cloud data. The reason for this is that the point with the minimum curvature is located in the flat area ,growth from the flattest area can reduce the total number of segments, then the growth criteria is determined according to the local characteristics of point cloud data. Experimental results show that this method can divide the point cloud data effectively, solve the problem of the instability of the traditional regional growth, and improve the accuracy and reliability of point cloud segmentation.

To extract four-dimensional computed tomography (CT) images of lesion blood vessels with real-time interaction in imaging examination, we propose a parallel region growing algorithm with optimized mind evolutionary algorithm (MEA). The parallel region growing algorithm with optimized MEA based on the three-level thread processing queue can avoid local optimum through self-evolution, and can improve convergence speed and blood vessel segmentation accuracy. Any part of the interactive cardiac lesion vascular extraction and four-dimensional visualization can be achieved with the aids of the visualization toolkit (VTK) and computer graphics library. The results show that extraction time and volume rendering velocity with ten phases of local blood vessels of interest are significantly improved, and frames per second (FPS) of local blood vessel extraction can reach about 30. If interactive manipulations such as rotation, shrinkage, and enlargement appear in the display process, the FPS will decrease to about 21, but the real-time display of cardiovascular can be obtained successfully. The local cardiovascular regional extraction technique can assist doctors to observe the lesion area of cardiovascular disease, and provide an intuitive and effective visual basis for the diagnosis of cardiovascular disease.

By using the moving atom-field interaction model, the effects of the atomic motion and the linear change of coupling coefficient on quantum correlations are investigated when the two atoms are in the entangled states and the light field is in the vacuum state. The results show that, as for the single-photon process, the quantum correlations increase with the increment of the structure parameters of field mode. The linear change of coupling coefficient plays a positive role on the quantum correlations. As for the two-photon process, the positive effects of the structure parameters of field mode and the linear change of coupling coefficient on the quantum correlations are more obvious if compared with the case that the coupling coefficient is constant.

Based on the equivalent circuit model theory, a rectangular metal ring with two interlaced multi-openings is placed on one side of the dielectric substrate, and thus a new kind of material structure is formed. Its effective electromagnetic parameters are extracted via the theoretical analysis and simulation. The results show that, the effective permittivity and effective permeability of this structure are both negative in the spectral range of 40.8-61.8 GHz, the absolute bandwidth is up to 21 GHz, and the wideband characteristic is achieved. These results provide an important reference for the application of left-handed materials in millimeter wave communication.

The tin-doped indium oxide (ITO) thin films are fabricated on the float glass substrates by the direct current (DC) magnetron sputtering method. The ITO thin films with different thicknesses are fabricated by changing the deposition time. As the film thickness gradually increases from 16 nm to 271 nm, the crystallinity is enhanced and the corresponding carrier concentration is increased from 4.79×1020 cm-3 to 2.41 ×10 21 cm-3. Thus the corresponding surface plasmon resonance (SPR) wavelength blueshifts from 1802 nm to 1204 nm. The controllable modulation of near infrared SPR wavelength within a relatively broad range is realized. The SPR wavelength of the ITO films with different film thicknesses are theoretically calculated by using the Drude free electron gas model, which further confirms that the effective modulation of SPR wavelength is determined by the influence of film thickness on carrier concentration.

The influence of rapid thermal annealing (RTA) on the structural and luminescence properties of GaAs/AlGaAs quantum wells is investigated. The results show that, when the annealing temperature is 800 ℃, the crystal quality and photoluminescence (PL) intensity is significantly improved. When the annealing temperature is 900 ℃, the crystal quality and PL intensity decrease. According to the peak energy theory, the luminous mechanism at room temperature of PL peaks is obtained. A whole RTA-induced blue shift of PL peaks is observed by peak-differentiating and fitting. The PL mapping demonstrates that RTA can significantly improve the whole crystal quality and the luminous uniformity of materials.

Silver nanowire (AgNW) films are prepared by using the spin-coating technique and processed by solvent vapor annealing. The sheet resistance, transmissivity, microstructures and surface morphologies of AgNW films are investigated. The current-voltage characteristics of the polymer solar cells with these annealed AgNW films as the anodes are analyzed. The results show that, after 3 h of methanol annealing treatment, the sheet resistance of these films decreases from 45.3 Ω/□ before annealing to 28.7 Ω/□, and finally saturates. The quality factor increases by 72.7% and the properties of films are improved. With the increase of the boiling point of the alcoholic solvent, the decrease of the sheet resistance of AgNW films becomes slow. The photoelectric conversion efficiency of polymer solar cells with these annealed AgNW films as anodes increases from 0.94% before annealing to 1.60%. The AgNW films with superior properties can be obtained after 3 h of annealing treatment.

The ZrO2∶Eu3+, Y3+ (Eu-YSZ) light conversion films are prepared on the fused silica substrates by using the chemical solution deposition method. The effects of Eu3+and Y3+ doping concentrations on crystal structure, surface morphology and optical properties of thin films are investigated. Under the irradiation of ultraviolet light with a wavelength of 396 nm and blue light with a wavelength of 466 nm, the Eu-YSZ thin films show bright red emission bands centered at 593 nm and 609 nm, which are attributed to the energy level transitions of Eu3+ ions. In addition, the thin films show a relatively high visible light transmittance. The study suggests that the Eu-YSZ light conversion films are beneficial to reduce the damage of short wave blue light to the retina of human eyes.

The filtering characteristic of the one-dimensional photonic crystal structure composed of Ag-ITO thin films in the spectral range of 300-800 nm is investigated by the finite difference time domain method. The influences of metal defect layer thickness, incident angle, and ITO film thickness on filtering characteristics of photonic crystals are simulated. The dispersion relationships of the photonic crystal under different parameters are simulated and calculated, and the corresponding mechanisms are analyzed. The results indicate that, the filtering range and filtering waveform of the photonic crystal can be modulated by tuning defect layer thickness. The change of the incident light in the small angle range (0°-20°) has little influence on the filtering performance of the photonic crystal. With the increase of ITO film thickness, the filtering spectrum shows a periodic change.

The digital speckle correlation method based on bivariate quadratic polynomial curved surface fitting method for precise sub-pixel localization has the advantages of simple calculation and high efficiency. The original method usually selects nine pixels around the integer pixel for surface fitting. We use the nearest six pixels around the integer pixel and the correlation coefficient to directly solve the bivariate quadratic polynomial through analyzing the possible improvement schemes of surface fitting. The speckle patterns are generated by computer simulation, as well as the rigid body translation experiments and uniaxial tension experiments are simulated respectively. Experimental results show that the improved scheme has the advantages of high computational efficiency and small computational error.

A contrast enhancement model based on the image retrieval is proposed to achieve the image contrast enhancement. We use the image retrieval technology to retrieve the high quality image as a reference image whose content is similar to the image to be enhanced to guide the enhancement of the image. The image entropy and aestheticis features between the image to be enhanced and the image retrieved are used to solve the multi-criteria optimization problems which combined the images via three enhancement methods such as the context-free, context-sensitive and brightness adjustment. Finally, the enhanced image is gotten by the quality constraint. In the context-sensitive enhancement, we use filter for unsharp masking to achieve edge enhancement. The context-free enhancement methods map transformations based on the Sigmod function to meet the human visual perception. The part of brightness adjustment firstly performs adaptive brightness equalization processing on the image, and then, a contrast limit adaptive histogram equalization transform is performed. Experimental results show that the proposed model can effectively adjust the contrast of the image and has better performance than other methods.

The series of new information acquisition methods are spawned with the rapid popularization of mobile devices. The most representative one is the two-dimensional code technology, which is widely used in the field of mobile payment. It implements a new type of communication method, in which two-dimensional code is displayed on the screen and recognized by camera. We introduce an information hiding technology to build invisible two-dimensional code information based on this new mode of communication, so that the users can obtain information while reducing the information perception of adverse effects from the introduction of visible two-dimensional code to the carrier. According to the digital video resources, the proposed algorithm embeds the specific information into the carrier by frequency constraint method, and takes pictures when the camera or mobile phone is played on the video screen. After the video information is obtained, the hidden information is extracted to achieve the effective transmission of the specific information. At the same time, the energy statistics model and error correction mechanism are introduced to ensure the accuracy of the extracted information. A large number of experimental tests show that the algorithm can achieve high accuracy of information extraction within 1-2 m distance.

Based on texture transfer principle of sample blocks, the influences of edge gradient information of texture image, the minimum error path and luminance information in the nonlinearity luma/chroma (YUV) color space on texture transfer results are studied. We take edge gradient information of texture image and the minimum error path of overlapping region as the measure of the texture synthesis at the same time, and introduce luminance information of the source texture image and the target image in YUV color space as constraint measure of the texture transmission. The found matching block is more suitable for texture transfer. At the same time, we use iterative method in the process of texture transmission to solve the problem that the transmission effect is not good after the texture transmission for one time. Experimental results show that, compared with the traditional texture transfer algorithm, the improved texture transfer algorithm can achieve better transmission effect.

Aiming at the problems that traditional lung nodules detection methods can only get low sensitivities and a lot of false positives, this paper presents a retrieval method for lung nodules CT image based on end-to-end two-dimensional full convolution object recognition network (2D FCN) and three-dimensional target classification convolution neural network (3D CNN). Firstly, the method builds the 2D CNN for candidate selection to detect and locate the suspected regions on axial slices, and outputs an image that is the same size as the original image and is marked. Secondly, the three-dimensional patches of each candidate are extracted to train the 3D CNN. Finally, the trained 3D model is used to classify the false positive nodules. Experimental results on the LIDC-IDRI dataset show that the proposed method can achieve the recall rate of nodules of 98.2% at 36.2 false positives per scan. In the false positive reduction, the method respectively achieves high detection sensitivities of 87.3% and 97.0% at 1 and 4 false positives per scan. Experimental results on the LIDC-IDRI dataset show that the proposed method is highly suited to be used for lung nodules detection, achieves high recall rate and accuracy and outperforms the current reported method. Meanwhile, the proposed framework is general and can be easily extended to many other 3D object detection tasks from volumetric medical images, and it has an important application value in clinical practice with the aid of radiologists and surgeons.

Resultsof standard graphics library ALOI and many other real images indicate that the proposed algorithm improves the image matching accuracy and shortens the image matching time in the complex environment.

Smoke detection in storage yard has great signification for fire early warning and protecting the safety of personnel and property. To solve the problem of insufficient features extraction, high false positive rates and poor robustness of traditional smoke detection methods, a new method of smoke detection in storage yard based on the parallel deep residual network is proposed. This method builds the parallel deep residual network with R, G, B components of the smoke RGB image and H, S, I components of the HSI transform image to adaptively extract the features. Meanwhile, the discriminant ability for the target like-smoke of the model is enhanced by the strategy including expanding the sample scale and reinforcement learning of the negative samples. The experimental results show that the proposed algorithm can effectively reduce the false positive rate caused by target like smoke and improve the detection rate and robustness of network.

Medical image processing is an important and key problem in image processing. High-resolution images with abundant details contribute to assisting physicians and computer aided diagnosis programs. According to the characteristics of magnetic resonance images, we propose a single-frame super-resolution reconstruction method based on wavelet features and clustered dictionaries. In the training phase, the multiscale wavelet features of low-resolution images and all high-frequency components of high-resolution images are extracted, and all of these feature images are overlapping and separated into patches. Then, K-means algorithm is used to cluster feature patches into several classes, for each class a pair of dictionaries is learned using K-singular value decomposition. In the reconstruction phase, each low-resolution patch is classified and sparsely represented with its corresponding dictionary atoms. Iterative back projection is used for post-processing to further improve the reconstruction quality. Experimental results show that the proposed method outperforms other main-stream methods, both visually and quantitatively.

The double threshold method based on the combination of bilateral filter and local grayscale difference is proposed to extract crack segments, and tensor voting algorithm is adopted to solve the problem of crack extraction caused by low contrast between cracks and background, as well as unevenness of gray values within the crack region. The double threshold method is introduced to obtain crack segments, and then based on proximity and continuity of crack fragments, the significant map and complete center line are obtained with tensor voting. Accurate crack extraction is realized by connecting crack fragment and removing discrete points with center line. Experimental results show that, compared with the method based on the beginning and end of crack fragments to connect, the proposed algorithm can increase F-measure about 27% to process the surface image of ceramic elements with cracks.

With respect to the problems of the fuzzy edge and difficulty in automatic segmentation of human organs during the computed tomography (CT) scanning, a local prior shape information and active contour based model is proposed. For an object whose shape is similar with the shapes in the dictionary, the prior shape in the shape dictionary is used to supervise and guide the high-level object segmentation while underlying segmentation is performed based on the image information. On the basis of the existed shape dictionary sparse representation, dictionary shapes are decomposed by mask matrix, and supplemental dictionary is generated, so the local shapes of the object can be described by the constraint of sparse shape of partial prior shapes. By the decomposition and recombination of the local shapes instead of the traditional prior shapes, shapes which are not included directly in the dictionary can be segmented, and the application range is extended. Experimental results of the segmentation experiments show that even if the edge of the object is fuzzy, the image can be recovered and segmented accurately with the proposed method, and the proposed method can be applied to medical image segmentation.

Aiming at the problems of non-contact images acquisition such as blur phenomenon, poor system identification systems and poor recognition effect, a palmprint and palm vein feature fusion recognition method based on block strengthened local directional pattern(BSLDP) and canonical correlation analysis is proposed. Firstly, we improve the traditional local directional pattern(LDP),and proposed the BSLDP algorithm to obtain the texture direction feature of palmprint and palm vein images. Secondly, the palmprint and palm vein feature fusion is realized effectively based on the canonical correlation analysis. Finally, the match identification is realized based on the chi-square distance. The experimental results show that the equal error rate is only 0.63% and 1.21% in the CASIA-M and the self-built non-contact image database. The results indicate that compared with other traditional and newest algorithms, the proposed method can eliminate redundant information, retain accurate feature information of palmprint and palm vein and improve system identification performance.

A key frame extraction algorithm of sign language based on compressed sensing and speed up robust features(SURF) feature is proposed to recognize the real-time, large vocabulary sets and continuous sign language videos efficiently and accurately. The sign language videos are reduced to the image features of low dimensional and multi-scale frame with compressed sensing. The segmentation of sub lens is completed by a adaptive threshold value, and a large number of sign language frame data are processed. We use SURF feature points to complete the feature matching, and the SURF frame similarity curve is drawn for extracting the key frames. In the pre-processing stage, we use the HSV space adaptive color detection to abstract the sign language area. Experimental results show that the key frames extracted by the proposed algorithm have high accuracy, and the proposed algorithm has the ability to process large amounts of complex data.

The folds on the surface of a satellite have a significant effect on optical scattering properties of the satellite, thereby affect the detection of the satellite by using optical devices. As far as the optical scattering characteristics of the satellite fold surface are concerned, most previous studies treat the folds as diffuse reflection materials, which results in large approximation errors and lack of basis. Taking the silver coated polyimide film of the satellite as the research object, we adopt the three-dimensional (3D) modeling technology to simulate the space target fold surface. The effect of folds with different degrees on optical scattering characteristics of the target is quantitatively investigated by calculating the optical cross section (OCS) of the target with different incidence angles and observation angles. The results show that the folds make the scattering peak of the target lower, but make the observation range of the detector extended, which is from specular reflection angle of 5° of the flat surface to the observable reflection angle of about 42° of the fold surface. Thus a huge impact on the scattering characteristics is produced. In the study of optical properties of the satellite, the corresponding surface fold treatment of the space target should be implemented by considering processing situations of the satellite to improve the accuracy of the analysis.

In order to realize high precision long-distance laser ranging, a laser ranging method based on the techniques of pseudo-random code (PRC) phase modulation and coherent detection is proposed. An experiment system for the free space target detection is set up. When laser outputs power, local oscillator power, modulation rate, PRC sequence length in a single cycle and telescope aperture are respectively 2.0 mW, 117.8 μW, 100 MHz, 81.9 μs and 2 cm, the system can achieve a ranging accuracy of 11.8 cm for the free space target located in about 8 m far away. The experimental results prove the feasibility of the proposed method. The experimental results are back-propelled to the spaceborne conditions and compared with the GLAS (Geoscience Laser Altimeter System) system parameters. The comparison results show that the system operates under lower peak power and longer pulse width conditions, so high-frequency detection can be achieved.

Land desertification can cause significant economic losses. The point cloud data obtained by airborne light detection and ranging (LiDAR) technology is of great significance in monitoring the deformation of sand dunes and studying its laws. The acquired two-period airborne LiDAR data from desert area are processed to generate digital elevation model (DEM) and slope maps, and the combination of geographic object-based and pixel-based change detection methods is used to accurately monitor the deformation of dune and its movement. The toe lines of dunes extracted from multi-temporal slope maps provide horizontal deformation of dunes. Difference analysis of two-period DEM can be used to analyze vertical movement of dunes. The interpolate lines analysis combined with the dominant wind direction can quantify the topographic deformation and movement laws of dunes. The analysis results show that there is an overall settlement in the whole study area, which is the movement of sand material. The deformation law of dunes is highly related to the main wind direction. The stoss slope of dune is mainly subsidence, and the leeward slope of dune is prone to slip-off, so settlement occurs at the top and sand material deposition occurs at the bottom.

The bidirectional reflectance distribution function (BRDF) of target surface can be used to describe the scattering characteristics of targets, which has been widely used in the applications such as target detection and identification, feature analysis and extraction. In this paper, based on five parameter BRDF model, two simplified five parameter models (BRDF model of semi glossy material and BRDF model of rough surface material) are presented according to the characteristics of different target surface material attributes. Furthermore, the model parameter fitting algorithm is optimized. The simulated annealing algorithm (SA) is adopted in the particle swarm optimization algorithm (PSO) to enhance the local search ability of the algorithm and improve the efficiency of the algorithm. The BRDF data of 2024 aluminum alloy samples with different roughnesses and three kinds of large roughness samples are experimentally measured. The trend of the BRDF variation of target sample with scattering angle, the relationship between the BRDF of target sample and surface roughness, are analyzed. Simulated annealing particle swarm optimization algorithm (SAPSO), genetic algorithm (GA) and particle swarm algorithm are used to fit the experimental data. The comparison between the model calculation results and the experimental results shows that the simulated annealing particle swarm algorithm has a smaller fitting error and is more suitable for BRDF optimization modeling, which proves the effectiveness of the algorithm.

Raman spectroscopy has been used in forensic science widely. In this paper, laser Raman spectroscopy analysis technology and K nearest neighbors algorithm are used to study 25 plastic steel window samples. The five principal components are extracted by principal component analysis, and the experiment built interactive verification test with the method regarding the training sample as the test sample. When the K value equals to 1, the lowest training sample error rate appears. Taking the three highest contribution value characteristic variables as parameters to build the classification model to realize the accurate classification of the unknown variables, and the total correct rate is 71%. The above method is more accurate than the direct observation of the spectra.

Based on the mid-infrared tunable diode laser absorption spectroscopy, we study the measurement method of nitric oxide (NO) with low concentrations and high signal-to-noise ratios. A mid-infrared NO absorption line at about 1926 cm-1 with strong absorption line strength is selected, and the NO measurement at ambient temperature is conducted with wavelength modulation method using an interband cascade laser (ICL). By changing the modulation parameters of the ICL, we investigate measurement results and signal-to-noise ratios of NO with different volume fractions (0.46×10-4-1.31×10-4) at different modulation currents (3-25 mA). The results show that the signal-to-noise ratio is the best when the modulation current is 11 mA. The measurement results of NO with volume fractions from 0.5×10-5 to 2.0×10-5 have high signal-to-noise ratios.

Based on tunable diode laser absorption spectroscopy technique, the measurement method of CO2 temperature and concentration in high temperature environment is studied. The CO2 absorption line near 4996 cm-1 is selected as the target detection line to measure CO2 temperature and concentration in high temperature environment. The CO2 concentration and temperature of CO2/N2 mixed gas in the gas absorption cell at different temperatures (873-1273 K) and different CO2 volume fraction (4%-10%) are measured. The results show that, compared with the setting values, the average deviation and peak deviation of the measured temperature are 2.07% and 3.49%, respectively. The average deviation and peak deviation of the measured concentration are 2.25% and 4.75%, respectively. The results indicate that the proposed method is accurate, and it provides references for CO2 detection in the high temperature environment.

To solve problems in common algorithms for spectral reflectance reconstruction such as the principal component analysis method producing ill-posed situation after reconstruction, we propose a spectral reflectance reconstruction method based on dimension reduction regularization polynomials. The principal component analysis method is used to conduct dimension reduction for high-dimensional spectral data of training samples. Based on the dimension reduction, the polynomial regression expansion is carried out for channel response numbers of the samples to improve the accuracy of spectral reflectance reconstruction, and Tikhonov restrictions are added to avoid ill-posed situation produced by data instability and random noise due to polynomial expansion. The results show that the precision evaluation effect of the proposed spectral reflectance reconstruction method based on dimension reduction regularization polynomials is better than that of the principal component analysis method and the polynomial regression expansion method. The proposed method can reduce the amount of spectral data, optimize the channel response, and improve the accuracy of reflectance reconstruction.

With the theory of the modified color difference saliency algorithm as a base, the fabric image texture clearance regions are characterized by the area and roundness of the highlighted and significantly connected regions. By the statistical extraction of the distribution laws of the standard fabric image texture clearance and by the setup of the color difference rating standard, not only the big serious color difference region is quickly detected, but also the background color noise of the fabric texture clearance region of the fabrics without the big serious color difference is distinguished. Based on the color difference rating standard, the weighted average method is used to complete the tested fabric color difference grating for the fabric images beyond the fabric texture clearance region. The results show that the proposed algorithm has the minimum error mean and variance, which can reflect the true color difference of fabrics.