The umbrella-type triplet electromagnetically induced transparency (EIT) effect driven by two coupling fields with strontium cold atoms in the magneto-optical trap as medium is observed experimentally. The Pound-Drever-Hall frequency stabilization technique and the injection locking technique are applied to the pumping laser in the experiment, and the power stabilization technique for the weak probe laser is also used. The experimental observation precision is improved by these techniques. The experimental results prove that the detuning of coupling lights has relatively great influence on the triplet EIT. Moreover, the line shape of EIT is a simple superposition of two Λ-type EIT line shapes.

A novel high-spectral-resolution lidar (HSRL) technique for atmospheric aerosol remote sensing, which uses multi-longitudinal-mode laser as the transmitting light source, is proposed. A field-widened Michelson interferometer (FWMI) is used as the spectral discriminator, and the periodic frequency discrimination characteristic in the process of FWMI designing should match with the mode interval of multi-longitudinal-mode laser to ensure consistent fine spectral discrimination for the return signal from each longitudinal mode laser. The principle and the realization way of the proposed multi-longitudinal-mode HSRL are illustrated in detail and the main factors which constrain the frequency discrimination characteristic of the FWMI in multi-longitudinal-mode HSRL are discussed quantitatively. The performance of the proposed technique is verified further at the wavelength of 1064 nm by computer simulation. The multi-longitudinal-mode HSRL technique can avoid the dependence of the current HSRLs on the single multi-longitudinal-mode lasers remarkably. The proposed technique can not only decrease the cost, volume and weight of the laser in HSRL, but also improve its stability notably, which is of great significance for airborne and satellite-borne HSRL development in our country.

Based on the analysis of the difference among the actual atmospheric environment parameters and the target-background radiation intensity, the monthly distribution characteristics of atmospheric transmissivity and target-background contrast in east China sea area and northwest area at 3.9 μm and 9.2 μm are analyzed by the MODTRAN mode. In order to study the comprehensive influence of actual atmosphere and aerosol on target-background radiation transmission, a further research about the influence of aerosol effect on the distributions of atmospheric transmissivity and target-background contrast at 3.9 μm and 9.2 μm is carried out combined local region monthly average environmental parameters. The result shows that the atmospheric parameters of atmospheric temperature and water vapor mixing ratio have influence on the distributions of atmospheric transmissivity and target-background contrast. The target-background contrast in east China sea area is always lower than that in northwest area. The target-background contrast at 3.9 μm is not only lower than that of 9.2 μm in the two areas, but also suffers more aerosol attenuation. Therefore, the 9.2 μm is highly recommended as the working wavelength in the target identification.

In order to solve the problem of the poor real-time measurement caused by a hyperspectral imaging system in passive ranging based on oxygen A absorption band, a method of multi-spectral non-imaging measurement for the average transmission of oxygen A absorption band is proposed. In this method, the radiation intensity information of targets located in oxygen A absorption band and its left and right band shoulders is collected by three narrow band filters. Experiments are carried out to measure the average transmission of oxygen A absorption band in the external field, and a photomultiplier tube is used as the photoelectric converter. A line-by-line integral model for oxygen A absorption band transmission is built， and the feasibility of the proposed method is verified when we compare the experimental results with the theoretical results. The contrast results show that the measurement error of oxygen A absorption band average transmission is from 0.146% to 1.576% within the range of 100-400 m, which proves the feasibility of the proposed method.

Wedge and strip anode(WSA) is one of charge division anodes. In the photon counting imaging detector, the role of the WSA is to decode the incident position of photon events. The anode performance parameters have an important influence on the imaging performance of the detector. The inter-electrode capacitance of WSA is studied, and its calculation formula is obtained by the theoretical model. The WSA panel with different parameters is designed and prepared. The relationship between cycle length, insulation gap width, anode collecting area, substrate material and the anode inter-electrode capacitance is analyzed. Test results show that the inter-electrode capacitance is in accordance with the theoretical calculation result and the deviation between calculated value and test value is within 10%.

Some resonant peaks in the frequency response curve of fiber laser hydrophone appear at the resonant frequency of sound pressure transfer function, which makes the working frequency band narrow. A distributed feedback (DFB) fiber laser hydrophone is designed with a sensitivity enhanced mental diaphragm structure. A sound pressure transfer function model of the DFB fiber laser hydrophone is established based on electro-acoustic theory. The influence of structural parameters of hydrophone on sound pressure transfer function is simulated, and the structure of hydrophone is optimized. Prototypes of hydrophones are fabricated and tested experimentally. The experimental results show that the average sound pressure sensitivity of the DFB fiber laser hydrophone can reach to -135.99 dB with the fluctuation range within ±0.6 dB in the frequency range of 2.5-10 kHz, and the resonant peak appears near the frequency of 16 kHz. The experimental results agree well with the simulation results. The study is of great guiding significance for the development of DFB fiber laser hydrophone.

Based on the propagation model of optical pulse in doped fiber, the split-step Fourier method is used to numerically study the generation and the transmission of Peregrine soliton in doped fiber. Based on the Peregrine soliton solution, the generation and the transmission of Peregrine soliton in doped fiber are discussed. The peak pulses of Peregrine soliton are extracted, the background waves are eliminated, and the transmission characteristics of high peak pulses are discussed. The results show that, when it is transmitted in doped fiber, the Peregrine soliton generates a high peak single pulse that is localized temporally and spatially, and then the high peak pulse splits rapidly to produce multiple sub-pulses. The saturated energy and the pulse peak intensity increase with the increasing small signal gain, the pulse width declines with the increasing gain, and the spatial separations of the excited sub-pulses are gradually reduced. When the background wave of the high peak pulse is eliminated, the pulse can be transmitted stably in doped fiber, the pulse width presents breath-type periodic change with periodic oscillation of the pulse intensity, and the average value of the pulse intensity is gradually increasing.

We analyze the limitation of the fast Fourier transform (FFT) method applied to the spectrum analysis of the optical frequency domain reflectometry (OFDR). The shortcomings of the fast Fourier transform-segmented Chirp-Z transform (FFT-SCZT) algorithm are discussed. Based on an improved genetic algorithm (IGA) and Zoom FFT (ZFFT), a fast and high-resolution spectrum analysis algorithm, FFT-IGA-ZFFT algorithm, is proposed. The computation procedures of the proposed algorithm are described and its time complexity is deduced. The experimental result shows that the FFT algorithm costs 3.130 s, the FFT-SCZT algorithm costs 1.993 s, and the FFT-IGA-ZFFT algorithm costs 0.525 s when 107 OFDR sampling data is processed in the same computing platform and with the same resolution. The FFT-IGA-ZFFT algorithm is outstanding in term of processing speed.

Optical sampling coupling technique is one of key techniques in all-optical multiple-input multiple-output (MIMO) signal processing. Both the mode dependent loss (MDL) and the insertion loss (IL) are key parameters which effect the device performance. The condition number of matrix can characterize the performance of optical sampling coupler. The optical sampling coupler which supports all-optical MIMO signal with three linear polarization modes (LP01, LP11a, LP11b) is numerically investigated. Under the condition of three sampling points, the condition number of matrix is used as the optimization condition to optimize the size and the position of sampling spots. MDL can be reduced to 0.03 dB and IL can be reduced to 1.90 dB. In order to further reduce the IL, the number of sampling points is increased. MDL is 0.04 dB and IL is 1.56 dB after the optimization for the size and the position of sampling spots. Although IL can be reduced when we increase the number of sampling points, an optimal number of sampling points exists under the geometric constraints of few mode fibers and sampling points.

In order to improve the wavelength conversion efficiency of all-optical wavelength converter, the conversion efficiency of all-optical wavelength converter based on the cross-gain modulation (XGM) effect and the cross-phase modulation (XPM) effect is analyzed on the basis of the research of wavelength conversion characteristics of quantum dot semiconductor optical amplifier (QD-SOA). Based on the XGM type all-optical wavelength converter and the three-level QD-SOA model, the effects of input pulse width, active region length, loss coefficient, maximum gain mode and electron transition time on conversion efficiency are calculated. The results show that reducing the input pulse width, loss coefficient and electron transition time and increasing the active region length and the maximum gain mode can improve the conversion efficiency of all-optical wavelength converter. The study is useful for the design of all-optical logic XOR gate and the application of QD-SOA.

Taking the mismatch angle between signal and local oscillator beams as an example, we analyze the influence of spatial phase aberration on the heterodyne non-imaging array detector based on theoretical derivation and numerical calculation, and compare the array detector with the single detector with the same size. The research results reveal that the attached phase term of the signal output from detector element will severely affect the performance of the non-imaging array detector. Therefore, when only the spatial phase aberration is concerned, the array detector with a simple linear superposition cannot contribute to the performance improvement of the system. If the attached phase in the signal of detector element is eliminated by a certain method, the non-imaging array detector can increase greatly the signal-to-noise ratio of the heterodyne system even if the aberration is severe. Our results enrich the research of the non-imaging array detector in heterodyne detection and have guiding significance for the application of this technology.

High dynamic range imaging technique can reflect the shooting scenario comprehensively and effectively, resulting in high quality imaging in the complex environment. However, the classic high dynamic range image fusion algorithm based on high-precision registration of multiple exposure images cannot deal with the impact of dynamic problems. It fails to realize high dynamic range image fusion when there is a moving target in the exposure images. Therefore, a new high dynamic range fusion algorithm to deal with the dynamic targets is proposed. The derivative optical flow based on color gradient is first utilized to acquire the dynamic target offset of different exposure images, which is caused by the camera shark or the movement of the scenario target. The high dynamic range image fusion weighting function is established by combination of target offset and inverse camera response function, and is applied to the fusion algorithm to tackling the problem of dynamic targets in the high dynamic range images without precise mapping. The experimental results show that without image registration, the proposed algorithm is effective in the fusion of the high dynamic range images with moving targets.

To solve the problems of large computation cost, ringing and noise sensitivity in blind restoration algorithms for microscopic images, the blind restoration algorithm under Bayesian framework based on two guided filterings is proposed. The depth information of microscopic image is used to estimate the probabilistic model of point spread function, and a minimum optimization problem under the Bayesian framework is built. The guided filtering is applied to searching the optimal solution through analyzing the solving scheme of the minimum optimization problem of the maximum posterior probability. The solution scheme of the two guided filtering algorithms is designed for removing ringing and noise, which means the restoration result of the first guided filtering will serve as input of the optimization problem again. Experimental results show that the pixel error rate of recovery result is around 0.04, which increases by 20% compared to those of other commonly used algorithms, and the running time is significantly shortened. The proposed algorithm can be used in assembly of the micro-structures for defocused image blind restoration.

Deep-sky image registration is the most important step in deep-sky image applications. Due to the low efficiency of these existing algorithms based on the triangle similarity, and the hardness of applying algorithms based on star description to deep-sky image registration, an improved efficient triangle similarity algorithm is proposed and applied in the deep-sky image registration. Firstly, the proposed method analyzes the single pixel intensity and star size histograms of detected stars, and divides the stars into stable and normal stars. Then, the triangles are constructed for stable star or normal star with its nearest two stable stars respectively. Finally, by introducing the degree of similarity, the improved voting matrix is used in triangle matching. During this step, an adaptive threshold calculation method is also proposed to measure the triangle similarity. Experimental results show that the proposed method greatly enhances the star matching efficiency, reduces the resources requirement and guarantees the high level of matching precision.

In the ghost imaging, a pseudo-thermal light source is generated by illuminating a diffuser with coherent light. However, in the X-ray region, the incident light of a pseudo-thermal light source is partially coherent, and the spatially partial coherence of the light has a great influence on the imaging quality. The influence of the X-ray partial coherence on the second order correlation function of pseudo-thermal light source is analyzed theoretically using the Gaussian Schell model. The simulation results based on the statistical optics are also given. Both the theoretical and simulated results show that the visibility and resolution of the ghost imaging are influenced by the X-ray spatial coherence. In the case of limited spatial coherence, the visibility of X-ray Fourier-transform ghost imaging can be improved by using a pinhole in front of the diffuser, and the width of the pinhole should be equal to the transverse coherent length of the X-ray. It will be beneficial to achieve the wide applications of X-ray Fourier-transform ghost imaging.

We propose a fundus imaging system based on the tomographic adaptive optics instead of conventional adaptive optics to increase the limited field of view. The performance of the proposed system is studied with Zemax and the simulation object, Liou-Brennan (LB) eye model. The human eye aberrations are described by Zernike fringe polynomials within 20° field of view to obtain the type and value of fundus aberrations. The results indicate that the proposed system extends the field of view from 1.2° to 3° compared with the conventional adaptive optics system. How to select the conjugated position of the deformable mirror for adaptive optics based fundus imaging systems is investigated. It figures that the deformable mirror can be optically conjugated at 3 mm before the exit pupil of eye for both the conventional adaptive optics system and the proposed system, and the position is also conjugated with cornea.

Compared with the traditional computed tomography (CT), the spectral CT can obtain projection images of the object in different energy spectrum channels with a single scan, which is helpful to improve the contrast-to-noise ratio and distinguish the materials. Spectral CT based on photon counting detector is a hot research topic in recent years. As the energy spectrum channel narrows, the noise increases in each energy spectrum channel. In order to reduce the noise in the channels effectively, the Split-Bregman algorithm based on the total variation minimization is used for spectral CT image reconstruction. The spectral range is divided into different channels according to the prior information of the reconstructed model. The reconstructions are conducted for the projection data with noise and sparse angle based on the Split-Bregman algorithm. The simulation results show that the spectral CT image reconstruction based on the Split-Bregman algorithm can reduce the influence of the noise in spectral channels effectively, and satisfying the requirement of substance distinguishing.

Aiming at the problem that the large-scale structure’s surface is large and the vision of camera is limited, a mobile videometrics method based on relay camera is proposed, and the global scanning measurement is carried out for large-scale structures. Reference mark points are acquired by relay camera fixed on the mobile platform. Extrinsic parameters of relay camera are calculated by the camera parameter calibration method, and the relative conversion relationship among mobile platform coordinates at adjoining times is obtained. A measurement camera goes around structure surface and acquires feature points, which is drived by mobile platform. After that, the real-time extrinsic parameters of the measurement camera can be obtained by the conversion relationship among mobile platform coordinates, and the equivalent binocular intersection collinear equation is established to calculate the positions of feature points. The automatic measurement is realized after completing parameter calibration at initial position. Experiments show that the measurement precision of the proposed method is 2.012 mm, and it is suitable for online monitoring large-scale structure with high degree of automation.

An accurate measurement approach to liquid refractive index of liquids with a fiber-capacitance droplet analyzer is proposed. A linear model between first peak values of liquid droplet fingerprints and refractive indexes is built by the least square method, where the surface tensions of glucose solutions and NaCl solutions are similar to that of water. The refractive index calculation model with surface tension modification is proposed based on the simulation analysis on influence of the surface tensions of ethanol and propanol solutions on droplet shape, where the surface tensions of ethanol solutions and propanol solutions have large difference with that of water. The experimental results show that, the mean error of glucose solutions and NaCl solutions by the linear model is 2.9447×10-4, the mean error of the tested solutions by the refractive index calculation model with surface tension modification is 1.4381×10-4, and the maximal relative error of tested solutions is 0.1258%. The proposed method is meaningful to extend applicability of fiber-capacitance droplet analyzers and improve the accuracy of refractive index measurement.

A high-order aberration measurement method for hyper-NA lithographic projection lens based on a test target with eight angles is proposed. A linear model between aerial image intensity distribution of the hyper-NA lithographic projection lens and high-order aberrations is built by principal component analysis (PCA) and multivariate linear regression analysis for binary target with eight angles of aerial image. And the high-order aberration measurement is achieved based on the proposed model. Compared with the binary target with six angles in the conventional method, the proposed method improves the efficiency of pupil wavefront sampling, expands the measuring range of the wavefront aberrations, and achieves the high precision measurement of high-order aberrations(Z5~Z64) of the hyper-NA lithographic projection lens. Simulations with the lithographic simulator PROLITH show that the proposed method can realize the measurement for 60 terms of Zernike coefficients (Z5~Z64) with measurement accuracy better than 1.03×10-3λ.

Maximum likelihood estimation (MLE) is the optimal estimator for target micro-motion feature parameter extracting. However, the grid search will cause the enormous computational amount, and the cost function of laser detection of micro-Doppler echo signals has high nonlinearity and exists many local maxima. A new method combining the mean likelihood estimation and the Monte Carlo method is proposed to solve this problem. A closed-form expression of maximum likelihood parameter estimation is derived. Then the compressed likelihood function is designed to obtain the global maximum. The parameters are estimated by Monte Carlo method sampling and calculating the circular mean value. The dependence of hight accurate initial values and the complex iteration algorithms are avoided in this method, and the joint estimation of parameters can be realized. Furthermore, for multi-component micro-Doppler signal, the presented algorithm can separate the micro-motion component signals at the same time with the estimations, which will not add complexity of algorithm. Applied to the simulated and experimental data, the proposed method achieves similar performance as MLE with less computational complexity. Meanwhile, this method guarantees the global convergence and realizes signals separation and parameters estimation.

Rotation of the linearly polarized light caused by spherical alkali vapor cell is studied theoretically and measured experimentally. The results show that the vapor cell has no effect on the polarization state of linearly polarized light when the light beams pass through the cell center, and the incident plane is parallel or perpendicular to the polarization orientation. While the other positions will produce a certain rotation, and the rotation angle varies with the positions. For the ideal vapor cell with the external diameter of 12 mm and thickness of 0.9 mm, the theoretical rotation is up to 0.08° when a position is off center of 0.7 mm. Therefore, the effect of polarization rotation should be considered, when using the spherical alkali vapor cell as a central element of the instrument.

The grating spectrometer is used to measure the spatially resolved emission spectrum of plasma in single pulsed laser ablation of bronze-bonded diamond grinding wheel. The electronic temperature of plasma in single pulsed laser ablation is 5220 K by calculation. The electron density is about 0.5×1016-1.8×1016 cm-3 at the range of 0-0.35 mm away from the grinding wheel surface. The spatial distribution model of plasma concentration and the dynamic equation of isothermal expansion are built. The simulation results show that the maximum isothermal expansion speed of plasma appears approximately at 25 ns during the single pulse time. The maximum plasma concentration of 1.8943×1016 cm-3 appears at 0.05 mm away from the grinding wheel surface, and the plasma shielding effect is so small that it can be ignored in the actual process. The experimental results have the same order of magnitude with the numerical simulation results, which verifies the correctness of the plasma physical model. The research results offer guidance to the optimization of pulsed laser ablation process.

The 426 nm blue light frequency doubling output based on the pumping light corresponding to D2 line of cesium atom is realized by the semi-monolithic resonant cavity embedded with a periodically poled potassium titanyl phosphate (PPKTP) crystal. Relatively loose focusing is adopted in experiment, which obviously improves the thermal effect induced by the absorption of fundamental frequency light and frequency doubling light. Frequency doubling blue light with the power of 117.2 mW is obtained based on the mode-matched fundamental frequency light with the power of 305 mW, and the highest optical-optical conversion efficiency in the frequency doubling process is up to 42%. The power fluctuation of blue light with the power of 84.5 mW is 0.48% in about an hour. Results show that the proposed method can realize the stable output of frequency doubling light, and has wide application prospects in the field of quantum optics and the interaction between light and matter.

Aiming at the echo characteristics of the plane target of the pulsed laser circular-viewing detection, the pulsed laser circular-viewing detection system is designed. Based on the traditional laser radar equation, a single station laser radar scattering cross section equation is used to derive the general equation of the echo power with spatial and temporal distribution. Based on surface characteristics of the tilted plane target, the echo power equations of the extended and the non-extended target are derived. The pulse broadening characteristics and the echo characteristics of Lambertian plane and non-Lambertian plane are simulated. The circular-viewing detection system is manufactured and tested, and the experimental results show that the echo waveform is consistent with the actual echo waveform of the rough flat plate. It provides a theoretical basis for the measurement of the pulsed laser circular-viewing detection system.

In order to clarify the mechanism of fatigue life enhancement of IN718 alloy strengthened by laser peening (LP), the relationship between the grain rearrangement and fatigue property of the alloy before and after LP is studied. The results show that, after LP, the maximum plastic deforming depth of sample surface reaches 33.7 μm, and the maximum fatigue life enhancement of the alloy reaches 188%. With the increase of laser power density, the surface residual compressive stress induced by laser shock wave increases, but the amplification decreases gradually. After the fatigue test, the release of the surface residual stress of 52% appears. The grain refinement phenomenon is found on the sample surface after LP, and the refining depth reaches 175 μm. The interaction among the dislocation sliding, dislocation climbing and twin crystal results in the generation of subgrains, and eventually the grain structure is refined.

This work presents the application of graphene oxide (GO) thin films, which are prepared on indium tin oxide (ITO) electrodes by solution spin coating method, as the hole transport layer in organic photovoltaics (OPVs). The thickness of GO films is optimized by adjusting the spin speed, and the effect of GO thickness on the performance of solar cells is investigated. Based on this, the performance of solar cell devices is further improved by using such methods as ultraviolet ozone (UVO) and annealing treatments. The results show that when the temperature of UVO and annealing treatments reach 250 ℃, the OPV devices achieve the highest power conversion efficiency of 3.16%, which is close to the result using a classical poly (3,4-ethylenedioxythiophene): polystyrene sulfonic acid (PEDOT: PSS) material. This result has indicated that GO, with such advantages as low-cost, solution processing, and excellent light transmittance, will become a promising and effective material for hole transport layer in OPVs.

In the spectral domain optical coherence tomography (SDOCT) system, we can get high transverse resolution only within the focal depth field. The transverse resolution degrades away from the focal plane. Interferometric synthetic aperture microscopy (ISAM) is a three-dimensional image reconstruction algorithm, which can make the out-of-focus image clearer, and a resolution in all planes that is equivalent to the resolution at the focal plane can be obtained. At the same time, the contradiction between the transverse resolution and the imaging depth in the SDOCT system can be solved. The principle of ISAM and its possible applications are introduced and the comparison between the reconstructed images by the traditional SDOCT method and the ISAM is performed. The nonuniform fast Fourier transform (NUFFT) algorithm is applied in ISAM. Experimental results show that the NUFFT can greatly reduce the operation time, improving the performance of real-time and high-resolution SDOCT system.

Under the action of ultrashort-pulse pump light, the dynamical evolution processes of nonlinear absorption and nonlinear refraction of polycrystalline diamond are studied by using two-photon excitation. In the dynamic experiment of nonlinear absorption, two different recombining processes of activated carriers are observed in the diamond sample, whose time scales are hundreds of picosecond scale and nanosecond scale, respectively, and the time constant of each process under the action of pump light with different energies is obtained accurately. In the dynamic experiment of nonlinear refraction, the positive change of nonlinear refractive index induced by the nondegenerate two-photon absorption process is observed and the third order nonlinear coefficient of the sample is obtained.

An optical design of double freeform surface semiconductor light-emitting diode (LED) collimating lens is proposed based on relevant theories such as geometrical optics, law of energy conservation, and the Fresnel′s law. Detailed algorithm design for constructing collimating lens model is presented as well. A freeform surface is a surface that is rotationally symmetric around a central axis. The 2D contour of this surface is constructed on the basis of non-uniform rational B-splines (NURBS) method and by ProE software. Through Monte Carlo ray tracing simulation, it is found that, compared with conventional single freeform surface collimating lens, double freeform surface collimating lens has greatly enhanced the illumination uniformity as well as the energy utilization. The research results have shown that, by using double freeform surface design, the design space can be remarkably extended, and the optical performance of collimating lens can be improved.

Catadioptric omnidirectional view infrared imaging system has the advantage of large field of view in the field of safety monitoring. But current usual catadioptric omnidirectional view system with a conical surface mirror have the problem that the detection ranges under different vertical pitch angles are greatly different. The detection range of catadioptric omnidirectional view infrared imaging system is related with the target dimension, task criteria, and resolutions of azimuth and pitch angles. In this paper, the geometric mean of the resolutions of pitch and azimuth angles is set as a constant, which is considered as the condition of the constant detection range in the catadioptric omnidirectional view system. Then, the corresponding system design method is deduced. The data simulation results verify the realizability of the constant detection range system. What′s more, the results show that the proposed method not only obtains the same detection range under different vertical pitch angles, but also makes the detection ranges in most of the field of view range better than those in the traditional catadioptric omnidirectional view systems with conical surface mirror by reasonable parameter adjustment.

To guarantee the measurement accuracy of the space-borne imaging spectrometer, the dual Babinet compensator pseudo-depolarizer (DBCP) is designed. The principle of the DBCP is analyzed by utilizing the electromagnetic wave theory and light wave transmission theory, and a suitable wedge angle of the DBCP is schemed out based on the formula of polarized light propagation in birefringent crystal. The depolarization performance of the DBCP is worked out with a set-up polarization testing device. The results show that the DBCP has a better depolarization performance within the incidence angle range of -15～15 ℃. When the wedge angle is 6°, the depolarizer can realize depolarization at detection band with degree of depolarization better than 99%. Which is independent of the azimuth angle and frequency, and without affecting the imaging quality. Furthermore, the DBCP has many advantages, such as high degree of depolarization, high transmittance, stable performance and small volume. The uncertainty of measurement is 0.00290, because of the systems error.

The present work solves the dispersion equation for high viscous fluid surface waves. It is found that the relaxation characteristics of surface waves change from exponential decay to oscillation decay, and the dispersion equation for fluid surface waves makes a fundamental change when the waves step over the extreme point (Y ≈ 0.145) with the increasing of dimensionless number Y. To verify the correctness of the proposed result, the relaxation and viscosity-temperature characteristics of fluid di iso decyl phthalate (DIDP) with high viscosity fluid by using surface light scattering method while the temperature is in the range of 286.27-373.32 K. The results show that Y value decreases with the increase of the temperature. When Y0.145, surface waves spread with oscillation decay form. The average deviation of measured viscosity and the viscosity in the reference is within ±2%. When Y→0.145, measured viscosity deviation increases sharply, and we cannot get reliable fluid viscosity. The present work will be helpful to understand the relaxation characteristics of high viscous fluid surface wave and offer the theoretical background for accurate and reliable measurement of the viscosity of high viscous fluid with surface light scattering method.

The experiment involves normal-hemisphere reflectance/transmittance from foam slices with different thickness at incident wavelength of 0.4-2.2 μm. The pore-scale radiative transfer simulation is modeled with Monte Carlo method applied in foam reconstruction from computed tomography. The radiative properties of Ni foam obtained from experiment and simulation are compared and the pore-scale distributions of radiative properties are analyzed. The results show that the pore-scale radiative transfer model is valid to simulate the radiative properties of Ni foam. The absorptance decreases and reflectance increases as the incident wavelength becomes longer. With samples thick enough, the absorptance increases to a stable value, while the transmittance decreases to zero. In addition, the pore-scale distributions of radiative properties are strongly dependent on the local structure. With incident wavelength of 1.5 μm, the absorptance in void pores is 1.5 times of that on solid skeletons. However, the reflectance on solid skeletons is 3.7 times of that in void pores.

In order to overcome the low efficiency of anomaly detection for hyperspectral images based on sparse representation, a joint spatial preprocessing and spectral clustering based collaborative sparsity anomaly detection algorithm is proposed, which makes full use of the spatial and spectral properties of hyperspectral images, and establishes a cooperative processing mechanism between the spatial and spectral properties, according to the imaging principle and structure of the hyperspectral imagery. The spatial properties of the hyperspectral images are analyzed, and the spatial preprocessing is combined with the spectral properties, which makes the anomalous targets in hyperspectral images easier to be detected. Then, the spectral clustering method based on spectrogram division is used to divide the band subsets, and the spectral clustering method has the features of convergence to the global optimal solution and fast speed. The anomalous targets in each band subset are detected with the proposed new space and spectral collaborative sparsity divergence index method. This collaborative sparsity method considers the spatial and spectral properties of the hyperspectral imagery. Final anomaly detection result is obtained by the superposition of the results of each band subset. The real AVIRIS and synthetic hyperspectral imagery data sets are used for simulations. Simulation results demonstrate that the proposed algorithm is robust, and has higher precision and lower false alarm probability.

In order to improve the automation level and the precision of building extraction, an automatic building extraction method based on shifted shadow analysis is proposed. It is guided by the principal line of segmentation-classification-optimization. The object oriented multi-resolution segmentation method is adopted to perform the initial image segmentation. The segmentation results are classified by the support vector machine (SVM) classifier into four categories, i.e., shadow, vegetation, building and bare land. The initial results are extracted. The shadow rate on the intersection boundary is designed to accurately validate the existence of buildings and remove the disruptions of non-buildings without shadows, and the final results are obtained. The large amount of experimental results validate that the proposed method is very effective, and the automation level is significantly improved. The completeness is more than 85%. The correctness and the F1-score can both reach more than 90%.The proposed method only needs data from images in the visible band and has a wide application range.

The original data acquired by Raman lidar system is calibrated by ten equations. The temperature is inversed, and it is compared with standard temperature at the same moment and the same effective altitude qualitatively. Then 50 groups of data are selected as statistical samples. From the perspective of quantitative analysis (similarity evaluation, difference evaluation, and comprehensive evaluation), the characteristic statistics of the samples is carried out by weight coefficient, error diagnosis and standard processing. Quality evaluation parameters and analysis method of each level are filtered. The acquired evaluation standards of each level are all based on the sample library with lager amount, which can represent average behavior of the temperature detection of lidar better. The test of real-time detection samples beyond the sample library indicate that the comprehensive multilevel control technique can describe the advantages and disadvantages of temperature data detection of lidar effectively. Temperature detection effect of lidar at different weather conditions exists differences.

One differential absorption lidar (DIAL) for measuring NO2 concentration profile is developed by using atmospheric backscattered signals. Two Nd∶YAG lasers are used to pump two dye lasers to produce two laser beams with the wavelengths of λon and λoff, respectively. Retrieval of acquired data provides the vertical and the horizontal distributions of NO2 concentration. The experimental results show that the volume fraction of NO2 at Huainan Institute of Atmospheric Sciences, fluctuates in the range from 0 to 2.5×10-8 in the atmospheric vertical height range of 0.4-3.0 km and 0 to 3.0×10-8 in the horizontal distance range of 0.4-3.0 km, respectively.

Optical polarimetric imaging technique is a novel kind of optical imaging technique. The unique information is obtained by detecting the polarization characteristic of light, which is unavailable by other imaging techniques. Therefore, this technique can effectively enhance the detecting dimensions. In recent years, the optical polarimetric imaging technique is proved useful in the fields of clear imaging through haze or some other turbid media. Later, the optical polarimetric dehazing methods are developed rapidly as an independent branch, and many achievements are obtained so far. The principles, realization approaches and methods, developments and status quo are fully introduced.

Accurate estimation of the floating green tide biomass has great significance to make the emergency response plan and realize the highly efficient allocation of resources. Relationships among the biomass per unit area of the floating green tide, spectral characteristics and the most frequently used indices for the green tide detection are analyzed with the in-situ data of floating green tide biomass and reflectance. Based on the analysis the estimation models are established and verified. Results show that the near infrared reflectance is strongly correlated with the biomass per unit area of green tide (correlation coefficient R≈0.8); strong correlation exits between the biomass per unit area and the frequently used indices, the reflectance peak value is located at 960 nm and 1060 nm (R>0.7); estimation models of the floating green tide with exponent form based on R960/R670 and R1060/R670 (R670，R960，R1060 are the reflectance at 670,960,1060 nm, respectively) have the highest accuracy (R2≈0.9, relative error RPE≈27%). Research results can provide references for the floating green tide estimation on the sea surface by the remote sensing technology.

A stable argon plasma plume is generated at atmospheric pressure by a plasma jet in dielectric barrier discharge configurations. The applied voltage, the current and the light emission signal are simultaneously recorded by an oscilloscope. Results indicate that the plasma plume is composed of successive fast-moving plasma bullets. Based on collisional-radiative model, the electron density of the plasma plume is investigated by optical emission spectrum in the range from 300 nm to 800 nm. Optical diagnosis shows that the electron density increases with the increasing applied voltage or gas flow rate. However, it decreases with the increasing driving frequency. The vibrational temperature and the rotational temperature of the plasma plume are also studied by optical emission spectroscopy. It is found that both of them increase with the increasing applied voltage or gas flow rate, and decrease with the increasing driving frequency. The aforementioned phenomena are qualitatively explained by analyzing the electric field of discharge.

A Doppler asymmetric spatial heterodyne interferometer can be used to detect Doppler frequency shift of airglow spectrum lines of the O2 band, and thus the wind speed in the high-level atmosphere can be retrieved. The absolute phase frequency shift of interference fringes caused by wind speed is small, and the absolute phase drift caused by system error has significant influence on the wind retrieval precision. Different with the single arm interferometer, the dual-arm interferometer has the absolute phase of its interferograms affected not only by the field-widened prisms and gratings, but also by the thermal expansion of spacers used to produce optical path difference. Therefore, the absolute phase drifts at different temperatures are measured experimentally and simulated numerically, and the reason of absolute phase drift is analyzed. Based on this, a absolute phase drift correction method is proposed. The distance between two linear phase fitting curves under the conditions of zero wind speed and a given wind speed is calculated, the temperature dependent absolute phase drift is corrected, and the wind speed is retrieved accurately. Results show that the measured phase drift fits well with the simulated phase drift. After the absolute phase drift correction, the retrieved wind speed error is 3.5 m/s, which is greatly improved compared with the result before absolute phase drift correction.

Laser plasma flash is induced when a nanosecond Nd∶YAG pulsed laser with wavelength of 1064 nm is focused on monolayer aluminum film. The ignition time of laser-induced film plasma (tm) is calculated with simulation method, and the relationship between tm and the laser wavelength, incident laser energy, focusing spot radius and pulse width is obtained, respectively. The results show that tm increases with laser focusing spot radius and pulse width increasing, and decreases with laser wavelength and incident laser energy increasing. In addition, the smaller the ionization energy of thin film materials, the smaller tm. When impurities and defects exist in films, tm becomes small. Such results provide a certain reference to the research on the generation mechanism of laser-sustained combustion and detonation wave.

The 2.5-m optical infrared telescope KDUST will be built in Antarctica by our country. In order to solve the problem of mirror frosting, the anti-frosting method by heating the indium tin oxide (ITO) film is proposed. With this method, the Antarctic Survey Telescope (AST) with sealed transmission structure has successfully been applied at the Antarctic Dome A. The anti-frosting feasibility of ITO thin films integrated in the reflecting film system, the preparation process and the surface shape variation of the anti-frosting reflector at different heating powers are discussed. The experimental results show that the ITO thin film integrated reflector has anti-frosting ability and little influence on the shape of the reflector surface, which can be applied to the large telescope system with reflection configuration in Antarctica.

Absorption gratings are the key devices in grating-based X-ray phase-contrast imaging (XPCI). The low cost and fitness for the fabrication in general laboratories make bismuth absorption grating favored. A calculating method for fringe visibility in bismuth grating-based XPCI is proposed, and the moire fringe visibilities of bismuth absorption gratings with different thicknesses are calculated through modeling. Results show that fringe visibility increases with the increasing thickness of bismuth structure. The fringe visibility for π phase grating can reach 48% under the 40 kV tube voltage, but only 22% under 60 kV, when the thicknesses of bismuth structure in source gratings and analyzer gratings are 150 μm and 110 μm, respectively. Furthermore, when the bismuth structure thicknesses of the two absorption gratings are equivalent, fringe visibilities are obtained by use of the π phase and π/2 phase gratings, respectively. Their quantitative comparison shows that the result of employing π/2 phase grating is slightly better than that of π phase grating. The quantitative calculation of fringe visibility will be beneficial to the design of grating-based XPCI system, which may promote the practicality of this technology.