Atmospheric temperature profile is an important parameter for climate, meteorology and atmospheric radiative transfer calculation. Temperature profile data of products inversed from data measured by moderate resolution imaging spectroradiometer (MODIS) exists on scanning strip per 500 m×500 m with the vertical resolution of 1 km. Based on the optimal interpolation method, the monthly averaging data of ground sounding site is used to correct the MODIS-inversed atmospheric profiles. In the area with ground sounding sites, the corrected results are compared with the profiles obtained by real-time ground sounding detection of a day, and it is shown that the average error and the root mean square error decrease more than 10%. In the area without ground sounding sites, we use the weighted average data of several sites around the target area to correct the MODIS data, and compare the correction results with real-time balloons data of the day. We find that the average error and the root mean square error greatly decrease.

A 2 μm waveband GaSb based subwavelength grating mirror is investigated, and the influence of subwavelength grating parameters on reflection spectrum is discussed. The mirror has a wide bandwidth and a high reflectivity with center wavelength of 2 μm in case of TM mode. The ratio of reflection bandwidth to central wavelength is more than 26% when the reflectivity is more than 99%. Especially, reflectivity of the mirror is more than 99.9% at the range of 1.895-2.08 μm, and the bandwidth is 185 nm, while the reflectivity in TE mode is lower than the lasing condition of the vertical cavity surface emitting laser (reflectivity is less than 95%). Each parameter of the structure has bigger fabrication tolerance, which facilitates monolithic integration of vertical cavity surface emitting laser.

In order to analyze the influence of sky background light on a space laser communication system and provide corresponding reference data for total design of communication links at the same time, a sky background light noise model is established and analyzed theoretically. Simulation results show that the sky background light causes the decrease of signal to noise ratio of the detector used in the coarse and fine tracking units, and then leads to the decrease of tracking precision and the increase of bit error rate of the communication system. According to the performance index of the system, the influence of sky background light on the system performance is effectively reduced to meet the requirements of the mission of the communication link when we choose the communication wavelength properly, use an optical system with minor-caliber and narrow bandwidth, and select the optimal zenith angle and communication time.

A long-gauge fiber Bragg grating (FBG) sensing technology is studied, and a chain array method is used to acquire dynamic response of beam. The identification of dynamic parameters of vehicle speed, frequency and vibration mode are realized. A single FBG is applied to pre-stressing, and then encapsulated to form a sensor. The measuring range of gauge is enlarged. A T-shaped reinforced concrete beam with the span of 4 m is equally divided into 8 cells. Sensors with length of 500 mm parallel to the natural axis, and they are independently installed in each cell, which can realize the overall monitoring of beam. The moving load testing is carried out when we use wheeled machine with additional weight. The location and passing time of the wheeled machine are determined when we analyze the time history curve of central wavelength based on the principle of time difference location method, and then the velocity identification is realized. The free vibration of the beam is excited by a vibration exciter. The dynamic response signal is acquired by long-gauge FBG sensors and piezoelectric accelerometers installed on the top of beam. Frequency and vibration mode are obtained by frequency-domain analyzing. The results show that the identification of frequency and vibration mode is achieved by chain array method, and the order of vibration mode identification depends on the gauge length of single sensor.

Aiming at the laser communication of geosynchronous relay satellite to earth, a servo tracking system with multiple closed loops is designed, and a mathematical model of the tracking algorithm and a proportional-integral-differential control algorithm with actuator limit for miss distance compensation of faculae are analyzed. Additionally, the composition of the servo closed-loop control system in the satellite-ground link laser communication tracking system, the performance index and work pattern of each execution module are introduced. The operating principle of the servo closed-loop system and the optical closed-loop system is explained. According to the design of the miss distance extraction algorithm and the error compensation algorithm, the optical closed-loop tracking programs in image processing module and slave machine execution module are carried out. The weak beacon tracking experiments for the whole system are carried out under static and dynamic environments, and the tracking accuracy of ±20 μrad (3σ, σ is standard deviation) in dynamic environment and ±7.5 μrad (3σ) in static environment are obtained. The experimental results verify the feasibility and the preferable operability of the design of tracking loop, and indicate that the designed tracking system has high tracking precision.

In order to solve the problem of wavelength control during the fiber Bragg grating fabrication, and to improve the precision of the existing solutions, a method based on the phase mask, including two steps of tension adjustment in the Bragg grating inscription and uniform ultraviolet irradiation, is proposed. The tension is adjusted by hanging weight at both ends of the fiber to make the grating central wavelength slightly smaller than the desired wavelength, then ultraviolet light is irradiated on the grating uniformly along the fiber to compensate the difference between the grating central wavelength and the desired wavelength. The error of grating wavelength is controlled within ±5 pm, and the change of the grating platform is small, which will not destroy the platform stability. Experiment result shows that the reflectivity of 1 cm long apodised Bragg grating reaches more than 30 dB. This method is simpler, more accurate and reliable compared with the existing methods.

Image quality assessment for multiply-distorted images is the emphasis and difficulty in image quality assessment (IQA) filed. Based on the high-order phase congruency, a no-reference IQA method for multiply-distorted images is proposed. The high-order phase congruency is computed to capture the structural information of the image. The statistical features of four orders phase congruency are extracted by gray level co-occurrence matrix，respectively. And，based on the analysis of the correlation between adjacent orders of phase congruency and the correlation between adjacent orders of local entropy of phase congruency, the mutual information and cross entropy of that are calculated. The support vector regression is utilized to build a regression model and then it is used for quality predicting. The experimental results on MLIVE and MDID2013 databases show that the proposed method has high consistency with the subjective evaluation scores and outperforms the state-of-the-art full-reference and no-reference IQA metrics.

In the field of industrial practice, the images are complicated because the conditions of imaging are usually poor and difficult to control. The image segmentation for complex imaging conditions is not easy. To solve this problem, a new threshold segmentation method is proposed based on Tsallis relative entropy and Gaussian distribution. In the method, the gray level histogram of image after segmentation is fitted by Gaussian distribution, and the difference between the histogram of original image and the fitted histogram is measured by Tsallis relative entropy. The optimal threshold is determined by minimizing the Tsallis relative entropy. Finally, the performance of the proposed method is compared with the several methods on segmentation of non-destructive testing images and synthetic aperture radar image. The results demonstrate that the proposed method has better visual effect, higher precision of segmentation, smaller segmentation error and less computational time. Thus, the proposed method has a good prospect in further applications.

In order to reduce the intra encoding complexity of the high efficiency video coding (HEVC), a novel algorithm is proposed, which is composed of the coding unit (CU) partitioning and the prediction mode decision based on image texture features. A preprocessing algorithm is employed to get the texture complexity and the direction of the current CU. On the one hand, according to the texture complexity of CU, the proposed algorithm can adaptively skip or suspend some CU divisions, and thus reduce the depth traversal time of the CU. The CU with high texture complexity is divided into four smaller equal-size sub-CUs directly. As for the CU with low texture complexity, the searching of partitioning is early terminated. On the other hand, a set of alternative patterns are confirmed according to the dominant texture direction of the prediction unit. the optimal model is chosen for the further rough mode decision algorithm and rate distortion optimization processes by traveling the alternative patterns. Moving the algorithm to the HM16.7, a normal decode software for food, the proposed algorithm can save 53.66% coding time on average, the negligible bit rate increases by 0.46%, and the peak signal-to-noise ratio reduces by 0.05 dB.

The relationship between the feature point density and the object degree of focus is analyzed, and a focus measure based on the feature point density is proposed. A novel focus measure fusing the feature point density and the edge information is proposed. The focus measure for scene depth estimation and all-in-focus imaging from focus stack is utilized. The proposed method can effectively compensate for the focus measure based on the edge information which is inaccurate in the image texture regions. The focus measure fusing the feature point density function and the sum-modified-Laplacian (SML) is used for the three-dimensional scene reconstruction, and the scene depth estimation and all-in-focus imaging algorithm are achieved. The experimental results show that the proposed method can effectively eliminate the error depth value which the SML estimates in the image texture region, retain the advantages of SML in the edge region and the high precision scene depth maps and all-in-focus images are obtained.

In order to improve the quality of circuit board infrared image enhancement, the butterfly universe algorithm is proposed. The butterfly universe topology structure and the universe information flow process are built, the multi universe information flow migration strategy is made by two-way migration between various cosmic links. The function to evaluate the circuit board infrared image enhancement effect is taken as the fitness function of the butterfly universe algorithm by the adaptive incomplete Beta function. Finally, the algorithm process is provided. Simulation results show that the butterfly universe algorithm has good circuit board infrared image enhancement effect, the enhanced image is clearer, and the two-dimensional entropy and contrast measurement index of image information are better.

A head-mounted vein imaging optical system composed by the infrared imaging system and see-through head-mounted eyepiece displayer is designed to greatly improve the success rate of intravenous medication. The near infrared imaging system has large numerical aperture of F/1.59, which is beneficial to the collection of the weak infrared scattered light. We choose quadric surface design of rotational symmetry, the weight of the imaging system is 22.2% lighter than the corresponding spherical system. The structure of the see-through head-mounted eyepiece displayer is simple and compact, because of its quadric surface design of rotational symmetry, which is 44.4% lighter than the corresponding spherical system. The design results show that the imaging quality of the near-infrared imaging system is excellent, and its resolution can reach extended graphics array (XGA) (1024 pixel×768 pixel). The see-through head-mounted eyepiece display gets a 10 mm exit pupil, a 50 mm eye relief, a maximum field curvature of 0.068D (D is diopter), a maximum relative distortion of 0.372% and display model resolution of XGA (1024 pixel×768 pixel). The total weight of binocular system is about 44 g. Comparing with the current vein display system, it has the characteristics of simple and compact structure, large numerical aperture, high resolution and light weight, etc.

By means of data simulation, the laser ranging data, attitude data and location data of portable coal inventory instruments under ideal conditions are simulated. According to the actual situation, each error parameter is determined and brought into the simulation data. By comparing the theoretical volume with the simulation volume after errors introduced, the influence laws of all kinds of error factors on volume are obtained. The producing mechanism for each error is analyzed and the influence degree of each error factor on volume is compared. The above research results provide a theoretical basis for the suppression or compensation of main error factors in the portable coal inventory instruments.

Large-aperture optical telescope of next generation has two features. One is that the primary telescope is segmented, and the piston and tilt/tip errors of sub-mirrors are controlled by active optics. Another is that the adaptive optics is used to eliminate the influence of atmospheric turbulence. So it is very important to analyze the effect of segmented errors on image quality of segmented telescope for the development of next generation telescope. The effects of piston, tilt/tip and edge errors of segmented primary telescope on image quality of segmented telescope are analyzed by using the theory and numerical simulation. The results of theory and simulation indicate that the effects of piston error and tilt/tip error on image quality of segmented telescope are mutual independent, and the effect of edge error on image quality of segmented telescope is little.

There are numerous control parameters of metal surface marking by laser which providing great influence on image quality. Pulse fiber laser is used to mark the two-dimensional code on Al99.70 aluminum ingot surface. The optimal mathematical model is established between processing parameters and gray value. The interaction between related processing parameters is analyzed, the process parameters are simplified and integrated. The single factor experiment is carried out with the simplified parameters, and the reasonable parameter range is obtained through the analysis of both distribution and change law of gray value of marked image. Finally, based on the results of single factor experiment, a multivariate nonlinear regression mathematical model between process parameters and gray value is put forward, and then the multi-factor orthogonal experiment data and immune clone algorithm are utilized for the fitting of model parameters. The effectiveness of mathematical model is demonstrated by verification experiment which provides the theoretical basis for the realization of laser two-dimensional code marking on aluminum ingot surface.

In order to guarantee the information security of the mobile phone, a user identity authentication scheme based on multi-sensor information fusion is proposed. Firstly, the signal features are extracted from the attitude angle changes, range of motion, and the rotation degree of user′s gesture. Then the dynamic time warping(DTW) recognition results of each single feature are used as independent evidence to construct the basic probability distribution function, respectively. And the Dempster/Shafer evidence theory is used for decision fusion. Also, a weighted evidence method is introduced in this work to alleviate conflict among the evidences, which can avoid the negative impact of this phenomenon. The conflict degrees between each pair of evidences are measured by calculating the similarity between them, by which the evidence credibility is determined. Afterwards, the evidence weights are revised to depress the negative effects of the evidences with low credibility when making the fusion process. Hence the final decision can be made according to the fusion result. The simulation results show that the performance of the proposed algorithm is better than the compared algorithms, which can effectively recognize the user's identity of mobile phone.

In the modulation profilometry, the fringe projection axis coincides with the observation axis, and the height information of measured object is encoded into fringe defocus, which completes the measurement with complex surface, the problems of shadows, shutoff and phase truncating. However, in the practical measurement, extraction of modulation distribution from fringe patterns will be affected on account of high-order harmonics produced by photoelectric response nonlinearity of CCD detector, which will reduce the measurement accuracy. The wavelet transform method is applied to modulation retrieval, and the frequency-domain description analysis is deduced for the fringe pattern influenced by nonlinearity. With the advantages of local analysis and multi-resolution, an adaptive optimized filtering operation is adopted to demodulate the image, which mitigates the effect of nonlinearity on measurement accuracy effectively and obtains better reconstruction results compared with Fourier transform method, both the computer simulation and practical experiment verified the validity of the proposed method.

In the study of laser damage mechanism, the change rule of incident laser reflectivity by materials versus the irradiated surface temperature is always concerned. Under the irradiation of a 915 nm laser, the change of the 3.8 μm probe laser reflectivity by 915 nm laser irradiated 45# steels is measured by the reflectivity measurement system based on the integrating sphere method. The temperature change of the irradiated regions is determined. The results show that the steep decrease of reflectivity is caused by the rapid oxidation of specimen surfaces at high temperature, and the slow variation of reflectivity with temperature is the result of the variation of conductivity with the temperature change.

Based on the columnar to equiaxed transition (CET) map, the geometrical relationship for the cross section of the molten pool is established and the relationship between the solidification condition and the microstructure for Ni-based single crystal superalloys fabricated by selective laser melting (SLM) is obtained. The SLM experiments are conducted on the (100) crystallographic plane of SRR99 single crystal substrate along the ［001］ direction. The results show that the minimum angle between the solidification velocity and the laser scanning velocity is about 46.4° (larger than 45°) under the conditions of laser power of 160 W, powder-layer thickness of 20 μm and scanning speed of Vb≤30 m·min-1. It can be predicted that the microstructure of the laser molten pool is composed of ［001］ dendritic crystals growing from bottom to top and ［010］ dendritic crystals on two sides. The experimental results coincide well with the theoretical analysis results. In addition, good metallurgical bonds are formed between layers and the crystallographic orientation of substrates gets extended.

Lateral confinement of the current is significant to semiconductor lasers. Lateral confinement can be achieved and threshold current density can be decreased in certain range if lateral confinement structure is embedded in active region of semiconductor lasers. But conventional lateral confinement method cannot suppress the lateral spread current effectively no matter whether lateral waveguide structure or shallow isolation groove is adopted. A new type of deep isolation groove structure is proposed, and lateral confinement is stimulated based on Comsol software. The deep isolation groove structure with etching depth more than the thickness of epitaxial layer is more effective when enhancing current injection efficiency. Two deep isolation grooves of 4 μm depth located at 100 μm away from the ridge type at both sides are etched by inductively coupled plasma etching. Experimental results show that, given the current of 5 A, the output power of semiconductor laser chip with cavity length of 4 mm and deep isolation groove is 3.6 W. The threshold current is 0.3 A. The threshold current density is 78.95 A/cm2. It indicates that the new type of deep isolation groove structure can suppress the lateral spread of the current effectively.

In order to fabricate a microcavity with a complex structure on the surface of stainless steels, the electrochemical micromachining technology based on fiber laser surface modification is adopted. First, the 304 stainless steel surface is masked with a predefined pattern by using a fiber laser. Then, by virtue of the corrosion resistance property of laser masked layers, a microcavity can be locally machined by the electrochemical etching technology. A composite machining system based on electrochemical micromachining in combination with fiber laser masking is developed. The system parameters are optimized through process comparison experiments by using 304 stainless steel as specimens. The results show that a microcavity with any typical structure can be fabricated quickly with this system.

The research on laser welding and laser welding with filler wires of 3-mm thick C18000 copper alloy plates is conducted. The microstructures, compositions and mechanical property of welds are analyzed emphatically. The results show that, in the case of direct laser welding, the growth of weld grains appears, the weld microhardness is 90 HV, and the weld strength is only 313 MPa. While in the case of laser welding with ERNiCu-7 filler wires, the mass fraction of Ni from top to bottom of the welds drops from 31% to 10%, the weld structure is single-phase solid solution, the weld microhardness increases to 130-180 HV, and the weld strength increases to 391 MPa. These performances are superior to those for the direct laser welding.

There are many problems of using weighing and cutting method for optical glass based on artificial experience, such as large errors, low efficiency and poor security. In order to solve the above problems, an automatic weighing and cutting equipment for strip optical glass is built based on machine vision, and an automatic weighing algorithm is designed for the equipment combined with structured light. The position feature of the glass cross section is identified after the optical glass image is collected by the high speed industrial camera. The cross sectional area is calculated by using the location information. Then the area is integrated with the help of the glass propulsion feed of the servo motor. And the cumulative volume and the mass size are calculated. When the cutting conditions are satisfied, the glass will be cut. Experimental results and practical application in the factory show that, the system has the characteristics of high precision, high efficiency and high safety, and the actual cutting error is less than 0.3 g. Therefore, The automatic weighing and cutting method can cut the strip optical glass efficiently and accurately.

The Ag-doped TiO2、Ce-doped TiO2 and Ag-Ce co-doped anatase TiO2 systems are built by the substitution doping of Ag and Ce atoms at the anatase TiO2. The electronic structures and optical absorption properties of the doped systems are investigated with the first principle. The results show that, as for the Ag-Ce co-doped anatase TiO2, a shallow impurity energy level conducive to electronic transition is introduced with the synergy of Ag-4d and O-2p electron orbits; its forbidden bandgap is reduced because of the strong synergy of Ag-4d and Ce-4f electronic orbits, which results in the red shifts of the absorption spectra; the introduction of Ce ions effectively reduces the recombination rate of electron-hole pairs in the impurity system, which improves the quantum efficiency of the system. Therefore, the Ag-Ce co-doped anatase TiO2 not only extends the range of the absorption spectra but also increases the quantum efficiency of TiO2, and the photocatalytic property of TiO2 is improved.

A new scheme to generate localized hollow beam (LHB) reshaped by Gaussian beam with bi-nonlinear ZnSe crystals is proposed. According to Huygens-Fresnel diffraction theory, the intensity distribution and dark-spot size of generated LHB in the conditions of ZnSe crystals with different thicknesses and Gaussian beams with different waist radii are calculated. The results show that the intensity distribution shape of LHB is a hollow ellipsoid, and the two-dimensional intensity in the propagation direction shows symmetrical distribution along the center. The aspect ratio of dark spot of generated LHB is obtained by numerical calculation, and it is found that the aspect ratio increases linearly with the increase of waist radius of the incident Gaussian beam. The parameters of generated LHB can be adjusted flexibly, and the generated LHB can be applied to the optical non-contact trapping and the manipulation of atoms and molecules, biomolecules as well as insulating particles with larger size.

A method of beam focusing control based on the spatial light modulation is proposed. In order to realize the rapid and precise adjustment on the axial and transverse deviations of the beam focusing, the liquid crystal spatial light modulator is adopted to produce the dynamic phase structure of binary Fresnel lens. An area array detector is used to detect the size and position of the light spot. And combining the feedback control mechanism, the automatic calibration and stability control on the beam focus point of three-dimensional position can be realized. In the adjustment process of this method, there is no coupling among different deviations, and the transverse deviation adjustments are insensitive to the propagation distance. Furthermore, the real-time feedback control system of beam focusing based on this method is introduced. The experiment results show that the axial calibration of the beam focal spot can converge precisely and rapidly. The transverse deviation calibration can converge with single step in the case of short focal length. In the case of long focal length, the combination of proportion-integration-differentiation algorithm is need to adjust. The convergence with single step can be also realized if an experiential correction on the adjustment errors based on the data fitting are corrected experimentally.

In order to improve the heat dissipation performance of light emitting diode (LED), based on the principle of the chimney effect, a special cooling radiator with straight chimney structure for LED is designed. The three-dimensional model is built by Solidworks software, and the model is simulated by its plug-in called Flow Simulation. The effects of various heights, vent shapes and sizes on the heat dissipation of chimney effect are studied. Studies show that chimney effect effectively improves the convection cooling performance of the radiator. When the height of chimney is 50 mm and the equivalent diameter of trapezoidal vent is 8 mm, the highest temperature of the LED is 61.6 ℃， which is 6.54 ℃ lower than the original model. Compared with the traditional radiator, the highest temperature of LED reduces 8.89 ℃. Through experiments, the average error between the actual temperature of the 4 monitoring points and the simulated temperature is 4.0%, and the average error is in the allowable range. It confirms the correctness of the simulation steps. In conclusion, the designed radiator can better satisfy the working requirements under the nature convection conditions.

The design of light emitting diode (LED) solar simulator needs to establish a high accuracy mathematical model with good stability for LED spectra. According to the characteristics of nonlinear LED spectrum mathematical model, a back propagation (BP) neural network optimized by improved genetic algorithm (GA) is proposed to identify LED spectral model. By improving the operator of GA, the convergence effect and the identification accuracy is improved. The improved GA is used to optimize the initial weights and thresholds of BP neural network, which is used to establish reliable LED spectral model. Under different driving current conditions, white and red LED are selected as experimental samples to verify the experiment. Experimental results show that the LED spectrum model is very close to the measured spectrum, and it has higher precision and better universality than other models.

The electromagnetic local density of states (EM-LDOS) near the surface of metal with periodic hole arrays is studied. The influences of the filling factor and the filling material in holes on the EM-LDOS are also discussed. Compared with that near the surface of the metal plate, the EM-LDOS resonance peak near the surface of metals with periodic hole arrays can split. When the filling factor increases, the resonance peak of transverse surface plasmon polaritons shifts in the low-frequency direction, while the resonance peak of longitudinal surface plasmon polaritons shifts in the high-frequency direction. When the dielectric constant of the filling material increases, both of the splitted peaks shift in the low-frequency direction, while the low-frequency peak shifts more remarkably.

The energy band structure of a lossy 2D metallic photonic crystal is solved and analysed. The transverse magnetic mode and energy band structure are obtained under the non-lossy free-electron model with the interfacial operator approach. When the Drude model with loss is considered and the homotopy method is employed to correct the eigen-frequency, the corresponding imaginary parts are obtained. The results show that the loss reaches the maximum value at the surface plasma frequency. When the frequency changes, the loss diminishes rapidly and varies with the change of reciprocal-lattice vector value. Even though the metal loss is considered, the real part of the eigen-frequency changes a little. The combination of the interfacial operator approach and the homotopy method provides an efficient technique support for the study of metallic photonic crystals.

A real-time data acquisition inverse synthetic aperture ladar system is designed. The continuous m-sequence phase modulation method is employed to image a rotating target at a distance of 33.5 m by a 1550 nm laser with the average power of 2 W. The range-Doppler domain imaging result reveals the characteristic of the target, distinctly. In the imaging demonstration, the range resolution and the cross-range resolution are 18 cm and 1.576 kHz, respectively.

An echo model of one-dimensional lidar range profile of airborne targets is introduced. The factors which affect the property of the detecting system are analyzed. The influences of atmospheric attenuation, receiving system noise and laser speckle effect on the resolution of target images are analyzed and simulated. The analysis results are verified by the principle experiment and the conclusion is obtained. Based on this, the suggestions are presented.

Vortex beams have wide application prospects in optical communications, interaction with matters and laser processing owing to their special spatial structures, have great significance in the discovery of new phenomena and effect of atomic physics in the extremely intense field, and can bring new methods of controlling physical systems. The main generation methods of high power vortex beams in recent years at home and abroad are summarized, and their principles are introduced briefly. The advantages and disadvantages of each method are analyzed, and some suggestions for improvement are proposed.

The progress on laser metallization of aluminium nitride (AlN) ceramics and the problems in the process of metallization are introduced. The major solutions to these problems are proposed as well. Based on the laser thermal effect, the thermal decomposition occurs on the AlN surface by laser metallization, and the metal conductive layer is generated directly, which has the advantages of low cost, high efficiency, simple equipment maintenance and so on. The optimization methods of laser, beam quality and process parameters and the applications of AlN ceramic metallization are introduced. The development of AlN ceramic metallization in the future is prospected.

Three-dimensional (3D) reconstruction is one of the most rapidly developing and widely used technologies. From a broad perspective, any method of obtaining the object′s 3D information can be called the 3D reconstruction. The 3D reconstruction data can be used to measure the 3D parameters of the target. There are many methods of measurement based on 3D reconstruction at present. Because of the problems in the contact measurement, how to choose the appropriate non-contact measurement method according to the different requirements and conditions is the key to obtain the required 3D data. Based on the principle analysis，a systematic classification of non-contact reconstruction measurement is given in this paper. The appropriate method of non-contact measurement based on 3D reconstruction can be chosen in the task of actual measurement according to the precision demand, environmental constraints, parameter types, cost control and other factors.

980 nm Yb-doped fiber laser can be used to pump Er-doped and Yb-doped fiber lasers to achieve high power laser output. Besides, it can be used to obtain the blue-green light at 490 nm by frequency doubling technique. As a result, it has drawn wide attention and become research hotspots. This review focuses on the related research achievements and experimental progress at home and abroad based on three operating modes (continuous fiber oscillator, pulsed fiber oscillator and fiber amplifier), and gives an outlook of the potential development of 980 nm Yb-doped fiber laser.

Due to the difference in energy band and mobility of material in the charge transfer layers of the quantum dot light-emitting diode (QLED), the unbalanced charge injection inevitably occurs. In order to fabricate a high-performance QLED with the most balanced charge injection, the interfacial control is commonly used. Combined with the QLED structures, the recent research progress on the QLED interfacial control for anodes, cathodes, and two-phase interfaces is reviewed. The interfacial control mechanisms and the effects of the interfacial control on the QLED performance are discussed. Challenges and trends in the development of QLED are presented.

Photonic crystal fiber (PCF) has many characteristics which are different from those of traditional optical fiber, and the application of PCF in sensing field becomes a hot research topic in recent years. The basic structure, guiding principle and preparation method of PCF are introduced. The principle and research progress at home and abroad of interference, absorption, fluorescence, surface plasmon resonance, Raman scattering and grating PCF sensors are summarized. The application fields, advantages and disadvantages of PCF are analyzed. The development trend of PCF sensors is prospected.

The preparation methods of GaSb single crystal are introduced, which include the Czochralski (CZ) method, the vertical Bridgman (VB) method, the horizontal Bridgman (HB) method, the vertical directional solidification (VDS) method, and the vertical gradient freeze (VGF) method. Their merits and demerits are also summarized. Research results show that the VB, VDS, and VGF methods are more suitable for the growth of GaSb single crystal. Research progress of the ternary alloy GaInSb crystal growth technology is introduced. The microgravity environment can effectively suppress the component segregation of In in the crystal and improve the uniformity of the crystal. The applications of GaSb single crystal materials in the fabrication of devices are introduced, and the development of GaInSb materials is prospected.

Sodium methylparaben is a common food additive, and long-period or excessive ingestion will do harm to the human body. An FS920 fluorescence spectrometer is used to detect sodium methylparaben in orange juice and aqueous solutions. The experimental results show that the characteristic peaks of the orange juice and the aqueous solutions have obvious difference. It is inferred that the interference is mainly from the fluorescence characteristics of orange juice. There exists notable difference between the two solutions with certain concentration range of sodium methylparaben, and the relationship between the relative fluorescence intensity and the sodium methylparaben concentration is complex. Therefore, in order to accurately detect the content of sodium methylparaben in orange juice, fluorescence spectroscopy and least squares support vector machine are combined to establish a model to detect sodium methylparaben in orange juice, and the regularization parameter and the kernel function are obtained with the improved particle swarm optimization algorithm. Compared with ordinary back-propagating (BP) neural network and least squares support vector machine based on particle swarm optimization, the model proposed has optimal performance, the average recovery rate is 97.05%, the average relative error is 2.71%, the root mean square error is about 3.04%, and the correlation coefficient between the model output and the real value is about 0.9999. This method can be used for accurate determination of sodium methylparaben in orange juice.

This paper introduces the detection principle of wavelength modulation spectroscopy, and analyzes the advantages and disadvantages of the traditional field programmable gate array (FPGA)-based wavelength modulation and demodulation algorithm. Then this paper proposes a FPGA wavelength modulation and demodulation algorithm based on coordinated rotation digital computer (CORDIC) principle. The principle of the proposed algorithm and the implementation process based on FPGA are introduced. Its advantages relative to the traditional algorithm in precision, resource occupancy, time consumption and other aspects are summed up. Finally, synthesis and simulation results of the proposed algorithm are given. The computational accuracy of the algorithm is verified by comparing the simulation result and the theoretical result. The accuracy and synthesized resource occupancy of the two algorithms are also compared.