Using high-speed,multi-cell Shack-Hartman wave-front sensor,the measurement of temporal and spatial feature to a rolling phase screen laboratory atmospheric turbulence generator is presented.In terms of spatial feature,coherence length of the atmospheric turbulence and phase spatial structure function of the wave-front are calculated,and the variance distribution of the wave-front Zernike coefficient is compared to the theory as well.In addition,on the temporal feature,the Greenwood frequency and time power spectrum of the simulated turbulence are analyzed.A new method that is called residual variance algorithm to calculate the time constant is proposed.The result shows that the atmospheric turbulence generated by the rolling phase screen is consistent with the Kolmogorov turbulence.

Adaptive optics (AO) technology is an effective way to alleviate the effect of turbulence on free space optical communication (FSO). A new adaptive compensation method can be used to optimize the communication performance without a wave-front sensor. The application process of the wavefront sensorless adaptive optics on FSO is simulated using the application of differential evolution (DE) algorithm, stochastic parallel gradient descent (SPGD) algorithm and simulated annealing (SA) algorithm. Meanwhile, the wavefront correction capabilities are analyzed by comparison of the coupling efficiency, the error rate and the intensity fluctuation under different turbulence intensities before and after the correction in FSO system. The simulation results show that the three algorithms can effectively improve the communication performance of FSO systems, especially the DE algorithm with lower iteration rate but optimal effects. Therefore, DE is suitable for strong turbulence conditions.

Based on the theory of generalized Huygens-Fresnel and the cross-spectral density matrix,the analytic expressions of mean-squared beam width of partially coherent radially polarized (PCRP) beam and Gaussian Schellmode (GSM) beam in atmospheric communication are derived.By comparing the influence of turbulence,coherence length and source wavelength on the spreading of width and angular between the two kinds of beams,it shows that the PCRP beam has superiority in atmospheric communication than GSM beam.The result shows that the propagations of the PCRP beam and the GSM beam in turbulence follow the same rules.The larger the turbulence is,the larger the spreading of width and angular is.The larger the coherence length is,then the more the effect of turbulence on the PCRP beam is,the smaller the angular spreading is.The larger the source wavelength is,then the less the effect of turbulence on the PCRP beam is,the larger the angular spreading is.But the PCRP beam is far less affected by turbulence,coherence length and source wavelength than the GSM beam,which means the spreading of width of the GSM beam is larger than that of the PCRP beam.In addition,the spreading of angular of the GSM beam not only relates to the three parameters above,but also is affected by the width of the source beam which is nothing to do with the spreading of angular of the PCRP beam.The above conclusions show that the PCRP beam is more beneficial to atmospheric communication than the GSM beam,and the study about turbulence,coherence length and source wavelength has a guiding role for the application of PCRP beam in atmospheric communication.

The propagation characteristics of terahertz (THz) wave in the turbulent atmosphere are very important to the space applications of THz wave. The horizontal propagation characteristics of THz wave in atmospheric turbulence have been studied by the random phase screen method. Through ignoring the scattering and absorption of THz atmospheric conditions and focusing on the atmospheric refractive index fluctuation, the average intensity distribution and scintillation indexes on the receiver plane were studied under different propagation distances in the atmospheric turbulence. For comparison, the visible light waves were also carried out through numerical simulation and analysis under the same conditions. The results show that under the same conditions, the influence of atmospheric turbulence on THz wave is much smaller than it on the visible light wave. Furthermore, atmospheric turbulence has little impact on the short-range application of THz wave.

Fractional vortex that carrys the orbital angular momentum is a kind of special vortex with spiral structure.Grating interference,which is made by vortex beams and the plane wave of the angle α with z axis,is used to make fractional vortex through spatial light modulator.Horizontal and vertical superposition grating is used to make the vortex arrays with different topological charge number.Through comparing the superposition of multiple sets of experimental design,the topological charge number vortex beam under the different topological superposition is analyzed.It is found that,as a carrier,the loading information fractional vortex beam is stronger than the integer vortex beam intensity,in which different fractional number,the maximum number of types of the transmission of information lays the theoretical foundation and provides the experimental basis for the reuse of vortex beam in free space communication.

The efficiency of optical heterodyne detection is not only related to the atmospheric turbulence, but also related to the optical field distribution of the signal light and the local optical on the detector photosensitive surface. The influences of the atmospheric turbulence on that are studied when the signal light and the local optical field distributions are not the same, the change of the heterodyne efficiency along with the radius is disscussed. The conclusion shows that when signal and local optical field are Airy+Gauss model, the influence of turbulence on the heterodyne efficiency is minimum, and will not change along with the detector radius after the efficiency is maximum. The influence of the turbulence is biggest under the Airy+Plane wave model, even under the weak turbulence, the heterodyne efficiency falls very quickly, and the maximum value of the drop rate is 95.13%.

An fiber current sensor is constructed by placing the gain magnetostrictive material (GMM) on fiber Bragg grating (FBG) system in current-induced magnetic field.The permanent magnet material is added at the two ends of GMM- FBG to form a static working point in bias magnetic field for the system.Besides,the GMM- FBG and permanent magnetic material are sealed by epoxy resin in order to insulate from external environment.Fiber Michelson interferometer linear sideband is used to demodulate the alternating strain on FBG to realize alternating current signal detection.The experimental results show that the maximum detected current is 1700 A and the voltage/current sensitivity is 0.68 mV/A when the system is working in linear region.The proposed current sensing device with simple structure,small volume and low cost provides an alternative choice for future current detecting device in power system.

The spatial diversity can be used to mitigate atmospheric turbulence over airborne optical links.Based on the direct detection receivers,the outage probability and power gain of optimal combining (OC) spatial diversity are compared with those of equal gain combining (EGC) and select-max combining (SMC) diversity.The power gain of these diversity systems is found to be substantial,and the performance of optimal combining is better than those of equal combining and select-max combining,as the performance of equal combing is found to be almost as good as that of optimal combining.But optimal combining is more difficult to implement.Hence the diversity technology should be chosed after comprehensive consideration in actual airborne laser communication engineering applications.

A modified ring fiber by introducing a high refractive index layer is proposed. With the effect of mode reorganization, index differences between the orbital angular momentum (OAM) modes are enlarged, thereby reducing the degeneracy among OAM modes. Parameters of the modified ring fiber are designed properly by numerical simulations, and modal index difference of about 10-3 is achieved, which effectively minimizes the coupling between OAM modes and thus improves the transmission property of ring fiber.

The leakage of harmful gas occasionally happens in the production process of petroleum and chemical industry.In order to accurately determine the leakage gas types and provide emergency guidance on time,a new optical infrared imaging analysis method based on the Fourier optics is proposed for the identification of leakage gas types.The experiments also study the influence of spectral resolution,the flow of gas emission on telemetry recognition identification,and use the method to detect and identify leakage gas in an ethylene unit.The experiment and field application results show that Fourier optical infrared imaging spectrum analysis can locate the gas position quickly,and identify leakage gas type.After detecting and identifying target gas correctly,reducing the spectral resolution and gas flow has no influence on gas identification.This method is beneficial to finding safety troubles and dealing with emergency accidents.

The flux density distribution on the plane photovoltaic cells of parabolic trough concentrator is theoretically studied. The results show that the flux density on plane photovoltaic cells distributed in three regions, which from the center to both sides are flux density is zero, flux density is greater than incident light and flux density is smaller than incident light. The flux density distribution curve is fitted and flux density goes down exponentially from the center to the edge. The closer the photovoltaic cell stay to parabolic focal and higher flux density is obtained and more quickly the flux density goes down. The validity of the result is demonstrated by comparing result with that in references.

By analyzing the diffraction under different wavelengths of digital micromirror device (DMD), a lensless color holographic projection system using single DMD is designed. With the reference of a single color component, the magnification chromatic aberration of the original image is eliminated. By adjusting the incident angle of these three-color lasers, the transverse chromatic aberration is eliminated. Color holographic reconstruction images with three-dimensional depth information is obtained by synthesizing the optoelectronic reconstruction image of the three color components. With this method, not only the program of color computer generated holography is simplified, but also the optical path of reconstruction is more intuitive.

A new method is proposed to measure the photon orbital angular momentum (OAM) carried by helical beams accurately through the amplitude computer-generated hologram (CGH) loaded on a liquid crystal display spatial light modulator (LCD- SLM).The diffraction processes of Hermite- Gaussian beams,Laguerre-Gaussian beams and Bessel beams with different orders passing through diffractive optics such as circular aperture,triangular aperture,Young’s double- slit,grating whose parameters are adjustable,are simulated with the help of plane wave angular spectrum diffraction formula and Collins formula.Then the propagation properties of helical beams passing through Young’s double- slit and triangular aperture are studied by theoretical simulation and experiment,and the measurement of photon OAM carried by helical beams is also realized with those two amplitude diffractive optical elements.Due to the fact that changing and controlling the CGH loaded into the SLM is able to change the configuration,dimension and location of diffractive optical elements flexibly and accurately,the accurate measurement can be achieved conveniently.

The value searching range of reference light intensity is large in Zhang′ s algorithm. Based on an analysis of the theory of holography, we can take multiple parameters into consideration to further reduce the value searching range for the reference light intensity in two-step phase-shift digital holography and verify its effectiveness experimentally through in-axis transmission and reflection holography. It is shown that the twostep phase shifting holography combined with our proposed methods is effective in eliminating the zero-order image and twin image from hologram without deteriorating the reconstructed image but being benefit for saving computation cost about 20%.

The displacement-voltage characteristics of a pre-load structure piezoelectric ceramic is measured by using optical interferometry.The influence of the resonance of piezoelectric device and its supporting structure on the accuracy of the measurement is observed.Furthermore,the comparative experiments are set up to study a variety of piezoelectric devices under several driving frequencies.It is proved that multiple-time measurement based on traditional device is necessary to get a more rigorous result of the piezoelectric response parameters.

The equipment based on confocal principle is a kind of new setup, which can fast and automatically measure center thickness of lens without contact of lens surfaces. We investigate the spectral bandwidth of emergent light in order to obtain the factors influencing the spectrum bandwidth and the measurement precision. The result shows that the numerical aperture on image side and the confocal hole radius are the main factors. When the numerical aperture is larger, the spectral bandwidth is smaller and the measurement precision is higher. What is more, when the hole radius is smaller, the spectral bandwidth is smaller and the measurement precision is higher, too. Then, we adopt the result to guide the design and simulation, and we get a better numerical aperture and confocal hole radius, which can realize the precision of the measurement system.

A wide spectrum infrared laser source can be designed by using a super luminescent light emitting diode (SLED) and an erbium doped fiber amplifier. This laser source can be used for detecting the atmosphere CO2 concentration with high precision, and this detecting technology is based on the ultra fine atmospheric CO2 absorption spectrum. The spectrum of SLED is much wider than that of the differential absorption lidar, and it has no use for high frequency locking technology. Also, this technology can avoid differential absorption lidar measurement error by on wavelength shift. The experimental results show that the laser center wavelength is 1584 nm, spectral range is from 1564 nm to 1604 nm, output power is 2 W, and the max gain of the fiber amplifier is 34 dB at this spectral range. This laser has advantages of small size, high power, low cost and easy to carry, and it can help for the development of atmosphere CO2 concentration detecting by the wide spectrum infrared lidar technology.

Laser peen forming, while applied in the deep drawing of metal sheet, is hopeful to cut down the cost of molds and reduce the friction effect in traditional micro deep drawing. Using dynamic and mechanical load induced by high-energy nanosecond laser pulses, deformation of metal sheets under laser fluence of 15.1~27.0 J/cm2 is investigated, during which bulging effect is observed. The results show that the bugling occurs when the metal sheet collides with the die under the load induced by laser pulse. Moreover, experiment on bulging effect under different laser fluences is performed. Possible controlling method is presented through lowering laser fluence and starting from single pulse to multiple pulses, which can improve the molding rate.

A fiber laser with wavelength of 1070 nm is employed to cut the sapphire substrate. The reasons for the generation of powder materials on the sapphire substrate surface and the collapse edge during the laser cutting sapphire substrate are researched, and the relation between the laser processing parameters (laser fluence, cutting velocity, repetition frequency, the pressure of assistant gas) and the collapse edge size on both sides of sapphire substrate is analyzed. The results show that the interaction between laser and sapphire is mainly thermal effect, which makes the sapphire material melt and evaporate. With the absorption of plasma which is produced by nitrogen for laser, the phenomenon of keyhole appears inside the sapphire structure and the length of keyhole have a significant effect on cutting quality. When the sapphire which thickness is 0.31 mm cut by laser, the collapse edge size on the sapphire substrate surface is 3 mm, and collapse edge size under the surface is 8 mm with the optimized laser processing parameters，that laser fluence is 5.7 ×103 J/cm2 , cutting velocity is 6 mm/s, repetition frequency is 1.8 kHz, the pressure of assistant gas is 0.9 MPa.

We studied a kind of common aerial aluminum alloy material, 6082 aluminum alloy, by laser shock processing (LSP) in this paper. This research forced on the effect of technology parameters on the micro-hardness peened by laser, including laser pulse width, signal pulse energy, the number of laser shocks, and the thickness of ablative layer. We designed an orthogonal experiment of process parameters of LSP, and the best technological parameters are obtained. On this basis, the best performance of the SLP of 6082 aluminum alloy is analyzed: Laser pulse width is 16 ns, and energy is 6 J when 6082 aluminum alloy is peened only once with the 0.2-mm thickness of absorption layer. According to the test results, we conclude that due to the low yield strength of 6082 aluminium alloy, the highest elastic level is also lower, thus the optimal value of the strengthen effect is low. When the power density is too large, it will influence the effect of LSP. The surface microhardness will also decrease.

With the disk laser as an optical source,the delay time of the experimental device is set through the laser cutting method.The delay time between the numerical control system and the laser control system is studied,thus the synchronization is achieved in order to guarantee the cutting quality.The theory and implementation of laser power control by the speed are studied to achieve the real-time adjustment and closed-loop control of power .The cutting qualities of HC1030/1300 MS high-stress steel of 1 mm in thickness are presented which are cut under the real time synchronous condition.Hot affected zone and burr edge are tested which can meet users requirements.Besides,the study on the laser cutting of car-body steel from 0.7 mm to 2.0 mm in thickness shows that laser energy is linear with respect to the thickness of plate.

Airy beams generated by the four-wave mixing (FWM) process in a homogeneous atomic medium is investigated.It is shown that Airy beams generated by both pure- FWM (PFWM) and dressed- FWM (DFWM)processes exhibit accelerating dynamics with a parabolic trajectory.The acceleration rate of these Airy beams can be dramatically modified by changing the detuning and strength of the external fields applied to the system.Due to nonlinear change of atomic coherence and the refractive index of resonant atoms induced by the dressing field,the amplitude suppression (enhancement) and the deflection position variation of DFWM signals can be achieved simply by changing the detuning of the dressing field.Airy beams generated via the FWM process can possibly be a powerful tool for delivering optical power,resonant particle manipulation and optical information processing.

Steady state and instantaneous availability have limitations in shot tasks.Based on a general model of mission-availability of inertial confinement fusion (ICF) facilities,a complete mission-availability model for disk amplifier system is proposed.A multilevel reliability block diagram is established.Equal relationship of expected accumulative failure number between Weibull distribution and exponential distribution is gained during each shot.Mission-availability model for disk amplifier modules with multi-failure modes of Xe-flash lamps and a method to evaluate mission-availability of the system with redundant modules are given successively by hierarchical modelling ideas.According to experimental data,the effectiveness of the method is verified and increasing trends of missionavailability of national ignition facility (NIF) and Shenguang (SG) facility are compared with each other,and then the suggested reliability index of Xe- flashlamps is obtained.The results provide designers a theoretical and methodological basis to optimize reliability design of the large ICF laser facilities.

The morphology of ends of single-track laser cladding layer has an important influence on the processing precision and stability in laser solid forming. Based on the principle of powder accumulation, the formation process of ends of single-track laser cladding layer is analyzed. An analytical model of constructing the ends is developed. Some single-track laser cladding layers are prepared. By laser scanning confocal microscope, the ends of single-track laser cladding layers are observed. And the profiles of a series of cross section along the scanning direction and longitudinal section are measured. The result indicates that the width/height of the ends increase inward along the scanning direction. Beyond the distance of the radius of molten pool, the width of the ends equal to the one of the cladding layer and keep stable. Moreover, the height of the zone out of the initial/tail molten pool reaches stable while the one in the initial/tail molten pool keeps increasing. Between those two zones, a boundary of broken line is formed. Beyond the distance of the length of molten pool, the cross section of laser cladding layer reaches stable. The constructed result shows good agreement with the experimental one in the main geometry characteristics, which indicates the powder accumulation is the primary mechanism in determining the morphology of ends of single-track laser cladding layer. The developed model provides a foundation to get insight into the morphology of ends of singletrack laser cladding layer.

To improve the measuring efficiency and avoid the influence from artificial error in the traditional contact method, and to overcome some limits presented in the Hough transform circle detection algorithm that often uses to machine vision, such as heavy calculation amount and inapplicable to the concentric circles detection, a new vision measurement method to measure the ring object diameter is proposed. The proposed method obtains the contour image of object through threshold segmentation and edge detection.Then the Radon transform to the contour image is executed, and the pretreatment result that includes in four light stripes reflects the measuring data of the ring diameter in the all direction angle. Finally, the central lines are extracted from the light strips with the gray gravity algorithm, furthermore the ring diameters are calculated according the distances between central lines. The simulation and experiment indicate that the proposed method holds scientific and reliable measurement result with higher measuring accuracy. Also, it can realize the automatic and non-contact measurement of concentric and eccentric object diameter and hence will hold good engineering application prospect.

The electronic structures and optical properties of Sb-doped SnO2 are studied by first principle calculation based on density functional theory (DFT). The computed results show that, with the increase of Sb doping concentration, the Fermi energy level passes through conduction band, and the band gap is narrower in succession, meanwhile, the energy level of shallow donor impurity is shifted away from the conduction band bottom, which makes the conductivity enhanced. The calculated results of charge density indicate that Sb-doping can change the property of SnO2 bond formation, which makes the covalent weakened and the metallicity enhances with the increase of Sb doping concentration. The calculated results of optical properties show that the imaginary part of the dielectric function has a red shift like the total density of state (TDOS) with the increase of Sb doping concentration, which indicates the internal relationship between electronic structure and optical properties theoretically.

The resonance tunneling characteristic of sandwich structure made of two different single-negative materials is investigated by means of the transfer matrix method. Merging of the resonance tunneling frequency is found when the conjugate matched condition is satisfied. The resonance frequency has nothing to do with the layer thickness when the thickness ratio remains unchanged. The only influence is to cause the resonant peak to be much narrower and quality factor enhanced when layer thickness increases. The electric fields corresponding to frequencies of the resonance modes are found to be strongly localized at interface of two media. When the losses are considered, the losses make the symmetry of electric field distribution destroyed and transmittance depressed.

A polycarbonate base tube is fabricated by using glass-draw technique. The base tube is of smooth inner surface, which guarantees low- loss properties for the hollow fiber. The big- bore polycarbonate hollow fiber is flexible and provide convenient and efficient coupling with various light sources. The fiber is of high safety because no debris comes out even when it is broken. A glass-draw tower and a corresponding control system are developed. Components and the fabrication parameters are optimized. Big-bore and flexible polycarbonate silver-coated hollow fiber is fabricated. Both uniform and gradually tapered base tubes are successfully used. Preliminary tests show that uniform hollow fiber has a constant output divergence angle. Gradually tapered hollow fiber has larger output divergence angle when laser light input from big end, and it has a smaller output divergence angle when laser light input from small end.

Fluorescence spectroscopy provides a noninvasive method to quantify biochemical and structural changes in tissues and it is regarded as an early subtle indicator of disease or injury.One challenge facing the rapid growth of fluorescence application is the inability to insure the accuracy of fluorescence measurements.The calibration protocols that include excitation energy calibration,collection efficiency calibration,wavelength calibration,system nonlinearity calibration,system response calibration,background subtraction and spectrum signal filtering,for optical instruments that ensure measurement accuracy are proposed.Three fluorescence spectroscopy systems are built and the fluorescence spectra of fluorescence standard and human skin are collected.The result shows that the spectrum intensity variation coefficient among these systems for the same reference standard is 7.4% and for the same human skin is 10.4% before calibration.By comparison,the spectrum intensity variation coefficients after calibration are 0.9% and 2.0%,respectively.

The paper studied the effect of spraying different concentration of He-Ne laser and 6-benzylaminopurine (6-BA) on protective enzymes system under Cd2+ pollution.The result shows that 6-BA and He-Ne laser have the relieving effects on heavy metal injury.Super oxide dismutase (SOD)、peroxidase (POD) and catalase (CAT) activities can effectively improve in different degree,and the increase of malondialdehyde (MDA) content and electrolyte leakage become much slower.It shows that action of exogenous 6-BA and He-Ne laser can alleviate the injury caused by cadmium stress and increasing the cadmium resistance of wheat seedlings.

To investigate and compare the biological effect of proliferation,enzyme activity and growth factor after double wavelength low level laser therapy (LLLT) on human embryonic skin fibroblasts (CCC-ESF) in vito,and explore the molecular mechanism of wound healing,in vitro culture of CCC-ESF is divided into control group and experimental groups (635 nm group,808 nm group,635 nm/808 nm group),laser of 20 mW/cm2,12 J/cm2 is applied to detect cell proliferation,reactive oxygen species (ROS) production,antioxidant enzyme activity [catalase (CAT)and superoxide dismutase (SOD)],lipid oxidation (MDA) and amount of cytokines related.Cell proliferation rate in the 635 nm group is significantly higher than that in other groups;ROS levels are 14.55%,7.49% and 14.92% respectively in 635 nm,808 nm and 635 nm/808 nm groups,which are higher than that in the control group;CAT and SOD enzyme activity increases after LLLT;808 nm laser promotes the level of MDA and expression of interleukine-1 (IL-1) and fibroblast growth factor (FGF);808 nm laser can stimulate the secretion of insulin-like growth factor 1 (IGF-1) and glial cell line-derived neurotrophic factor (GDNF).Low levels of oxidative stress induced by LLLT can promote the proliferation of CCC-ESF,improve cell viability,and enhance cellular resistance to the external environment.LLLT stimulates the secretion of a variety of cytokines and regulates the wound healing process.Biological effect produced by double wavelength LLLT is better than that with a single wavelength in CCC-ESF.

Bioluminescence tomography (BLT) has recently emerged as a promising preclinical imaging modality.Iterative methods based on sparse regularization play a critical role in solving the ill-posed BLT inverse problem.Four kinds of typical iterative methods based on l1 regularization were briefly introduced and applied to reconstruct the bioluminescent source location and intensity,which include interior-point methods,homotopy methods,firstorder methods,and augmented Lagrangian methods.Numerical experiments on a digital inhomogeneous mouse model and in vivo experiments were conducted to evaluate the performance of these methods in terms of localization accuracy,reconstructed intensity and power.

In order to improve the diffraction efficiency of light-induced little-period photonic lattices, the periods of written photonic lattice are controled and the diffraction efficiency curve varying with writing time in different angles is recorded by changing the angle between two induced beams when writing one-dimensional photonic lattice in double doped Mg∶Fe∶LN crystal. The results show that the diffraction efficiency of double doped Mg∶Fe∶LN crystal drops sharply when the angle between two induced beam is more than 24°. The intensity oscillation caused by second harmonic increases the diffraction efficiency of photonic lattices. Greater angle between two induced beam makes shorter time of intensity oscillation.

Based on the paraxial approximation of propagation of optical beam, the analytical expression of electric field is derived on the observation plane for the Gaussian beam passing through spiral phase plate (SPP). Based on the derived result, the intensity and phase distributions of the generated Gaussian vortex beam by SPP are analyzed. It is found that, different from the case of ideal SPP, the intensity of the beam from multi-level SPP is periodically distributed in the azimuthal direction. The periodicity is equal to the order of the SPP. A suitable choice of the SPP is 16-level structure to obtain good quality of intensity and phase distributions of the generated vortex beam. On the same condition, obtaining good quality of phase distribution requires longer propagation distance of the beam after SPP. In addition, the topological charge decided by the SPP has almost no influence on the above points. The decisive element is still the order of the SPP. The results can provide guidance on the use of SPP in the experiment.

The nonlinear electro-optical modulation method is analyzed for optical mixing, and an optical mixing using cascade nonlinear modulation is designed to inhibit the generation of high-order intermodulations effectively as well as to improve conversion efficiency by changing phase relations. Meanwhile a mixing properties simulation including woise with Optisystem has been done, indicating the good performance of this scheme.

In this paper,we study the transmission performance of the normal launched charge-2 vortex beam in the self-focusing saturated nonlinear photorefractive crystal which has an optically induced negative defect state in the center,where the width of the input beam can be compared with the lattice waveguide.Numerical simulation shows that,when the depth of the lattice can match with the light power,the input beam evolves into a similar quadrupole,and all the energy is kept in the defect site.What is more important,it′s phase doesn′t keep the initial spiral structure.But the diagonal points have the same phase,while the adjacent points have opposite phase.If we change the ratio of the depth of lattice and the power of the input beam,stable local solitons will not exist.

Considering the programmable phase modulation ability of liquid crystal spatial light modulator (LCSLM), the implementation of phase grating wavefront curvature sensor based on LC-SLM is introduced. A closeloop phase retrieval method based on eigenfunctions of Laplacian is proposed, and its accuracy and effective range and stability are analyzed through numerical simulation. The simulation results show that comparing with the open-loop phase retrieval method the close-loop phase retrieval method has a higher accuracy and a larger effective range. Moreover, the close-loop phase retrieval method is stable regardless of modal cross coupling.

Dynamics of quantum correlation of two atoms going through a cavity one after another are investigated by means of numerical analysis method. Effects of the initial atom states and the Fock state and the atomic movement on entanglement and quantum discord and a comparison of entanglement and quantum discord are analyzed. The results show that the initial atom state can change the time evolution of entanglement and quantum discord, the increase of Fock state number can make the entanglement and quantum discord from periodic evolution to nonperiodic evolution. The nozero of the number of Fock state can lead to entanglement sudden death and nonzero quantum discord. Atomic movement can make the entanglement and quantum discord from nonperiodic evolution to periodic evolution, and can make the period shorter and it is found that the increase of the field model structure parameter can increase the entanglement and quantum discord. In some cases, the evolution law of entanglement and quantum discord are nearly same.

The error ellipsoid is introduced into the evaluation of point cloud precision analysis.The relationship between error ellipsoid and point covariance is studied emphatically.The scale factor used to describe point error ellipsoid is acquired according to the point probability of error ellipsoid corresponding to the different scale factors.The overlap of adjacent error ellipsoid is determined according to the relationship between the adjacent error ellipsoid and the scanning interval.The point cloud error ellipsoid is calculated in the case of intersection between the error ellipsoid.The average point error ellipsoid is acquired according to the point cloud error ellipsoid.The average point mean square error is calculated by using the relationship between error ellipsoid and point mean square error.The evaluation of point cloud precision is realized according to the error ellipsoid.

In recent years, with the continuous miniaturization of components and the requirements for more compact and highly reliable products, effective microjoining has become one of the important parts of micromanufacturing. Several methods have been successfully used to microjoin similar or dissimilar materials. However, for transparent and fragile materials, such as glasses, the effective microjoining has been being a challenge. Nowadays, a few kinds of lasers have been widely used for welding many materials, but for lasers with long pulse width,the energy can hardly be absorbed and the thermal expansion may make the glasses broken, which is not suitable for glasses microjoining. Due to the excellent characteristics of little thermal effect of heating materials and nonlinear absorption, ultrashort pulsed lasers are very suitable for microjoining glasses, which has become a hot research field of micromanufacturing. The mechanism of ultrashort pulsed laser microwelding of glasses, the existing problems and the potential applications are elaborated. The future trends of ultrashort pulsed laser microwelding of glasses are also prospected.

Coherent detection technology can improve the sensitivity of homodyne receiver effectively.In the system of space laser communication,homodyne receivers make the phases of a local oscillator (LO) signal and a signal wave synchronize,and the optical phase locked loop (OPLL) is the most efficacious technology.Firstly,by including the theoretical model of the optical phase locked loop,the corresponding transfer function is derived.Meanwhile the main parameters affecting the performance of the optical phase-locked loop are discussed,such as the loop noise bandwidth,the natural frequency,the damping factor of the loop.The basic structure and characteristic of each OPLL type are described including:balance OPLL,Costas OPLL,syncbit OPLL,dither OPLL and sub-carrier OPLL,and their properties are compared.Finally,the development and application of OPLLs are summarized,and the prospect of the OPLL technology is prospected.

With the development of terahertz (THz) technology, THz waveguides have always been a research hot spot and various waveguides arise at the historic moment. Compared to metal waveguides, polymer waveguides have obvious advantages in both propagation loss and flexibility. The recent researches on THz polymer waveguides are summarized. Different mechanisms of polymer tube terahertz waveguides, including total reflection guiding and anti-resonant reflecting guiding, are concluded. Finally, possible further applications of such terahertz polymer waveguides are briefly described.

White illumination light emitting diode (LED) has the characteristics of energy efficiencies,reliability,long lifetimes,lower cost and high- speed modulation.LED can be used not only as illumination,but also simultaneously as the source of visible light communication (VLC).Due to the advantages such as energy saving,no electromagnet interference,high communication speed and accuracy position,visible light communication has wide application prospects.It is a hot research topic in optical communication field.The VLC potential applications and achievements in indoor positioning navigation,intelligent transport system,high speed communication,airport and underwater areas are reviewed,and some of the challenges and it′s development direction in the future are also discussed.

Laser inertial fusion energy is a well-known safe,carbon-free,sustainable and clean energy source.A brief introduction to laser reference design in high power laser energy research (HiPER) project is presented.Then two schemes of multi kilojoule level laser chains concepts for HiPER program are emphasized on amplifier geometry,thermal,amplified spontaneous emission management,and beamline architecture,etc.Finally,the time schedule of the HiPER program for laser energy,namely the production of electricity using laser inertial fusion,is also introduced.

Cardiovascular disease and coronary artery stenosis are closely related.Detection and quantification of coronary artery stenosis is important for cardiovascular disease prevention,detection and diagnosis.As the rapid growth of medical imaging and image processing techniques,automatic and semi-automatic stenosis detection,as well as quantification,has become an important development direction in the field of medical image processing.The related technologies include automatic coronary artery tree labeling on computed tomography angiography (CTA),vessel tractography,and robust kernel regression,etc.The latest advance in coronary artery stenosis detection and quantification in the recent years is reviewed,the technological process of stenosis detection is summarized,and the tendency and application prospect in the future is discussed.

In nuclear accident radioactive dust,Cesium is one of the main nuclear.So establishing fast and effective detection of the cesium and other elements is an important research direction of nuclear accident emergency.This study establishes a collinear double pulses laser induced breakdown spectroscopy (DP-LIBS) technology of nuclide cesium detection method.Optimization experiment of gate delay time finds that the signal spectrum reach maximum enhancement,when the gate delay time is 2.0 ms.When the delay time between two lasers is 3.8 ms,the signal spectrum is best.Through the quantitative analysis of the leaf sample tablet,when the analysis line is CsI:894.3 nm,fitting coefficient R2 of fitting curve is 0.91.Further using DP-LIBS to analysis Photiniaxfraseri leaf which is dealt with different concentrations of Cscl,and the result shows that:leaf which is dealt with different concentrations of Cscl has obvious spectrum in CsI:894.3 nm,fitting coefficient of fitting curve is 0.73.The feasibility are proved that LIBS technology can achieve rapid detection of radionuclide cesium content in environment.

Using hyperspectrum technology to measure the soluble solid content (SSC) of pitaya can provide a scientific method for the non- destructive measurement of interior quality of pitaya.Pretreatment methods are used to process diffuse reflectance spectroscopy.The successive projections algorithm (SPA) is used to select characteristic variables.The partial least squares model (PLS) and back propagation neural network model (BPNN) are built to predict the SSC of pitaya.The influence of the pitaya peel on the SSC model prediction accuracy is also analyzed.The result of moving average smoothing (MAS) pretreatment method is best.The correlation coefficient of cross calibration (Rcv) of the PLS model built is 0.8635,root mean square error of cross validation (RMSECV) reaches 0.6791.Based on the 15 characteristic variables,the correlation coefficient of prediction (RP) of the BPNN model for predicting SSC of pitaya is 0.8411,and the root mean square error of prediction (RMSEP) is 0.8171.The peel has influence on prediction results of models,RP of the whole pitaya model is 0.8999,and RMSEP is 0.7208;RP of the pitaya model without peel is 0.9304,and RMSEP is 0.5291.The prediction accuracy of the pitaya model without peel is higher than the whole pitaya model.The results indicate that the non-destructive measurement for SSC of pitaya based on hyperspectrum technology is feasible.

Three-chips of light emitting diodes (LEDs) are flexible in spectrum composition,and the whole performance is easy to control.Through studying the range of luminous efficacy of radiation (LER),mesopic efficacy of radiation (MER) and circadian efficacy of radiation (CER) based on various combinations of threechips of LEDs,basic theories for spectrum optimization are provided.Three chips from six groups of single chip LED are chosen,which uniformly distributed on the chromatic diagram to fabricate three- chips of LED at different color temperatures of 2000 K,3000 K,4000 K,5000 K and 6000 K.ηLER,S/P ratio and acv value are calculated,and ranges of corresponding characters are achieved.Results show that ranges of corresponding ηLER ,S/P ratio and acv value are large,respectively reach 0.4,0.6 and over 0.4.Overall trends conform to former studies,high color temperature leads to high S/P ratio and acv value.But low color temperature LEDs may also reach moderately high S/P ratio and acv value,and high color temperature LEDs may also reach moderately low S/P ratio and acv value.Spectrum optimization of three-chips of LEDs effectively helps improving performance.

Interferograms of the spatially modulated imaging Fourier transform spectrometer can be distorted with the nonuniformity of array sensors,little deviation will result in notable variation in the recovered spectra,so it is very important to calibrate the interferogram and eliminate the nonuniformity of array sensors before recovery.A new method of on-orbit relative calibration for the spatially modulated imaging Fourier transform spectrometer based on radiometric calibration field is introduced without the calibration coefficient in laboratory,it only needs the spectra of a uniform field which covers several lines of CCDs across the orbit,each line of spectra corresponds to a frame of interferogram.Simulation and phase matching is carried out to calculate the calibration coefficient.The result shows that the method can get good performance.After calibration,interferogram has a steady tendency and shows significant streaks away from zero point,eliminating the strips in the recovered spectra.

According to the spectroscopic analysis results of ruby samples from Burma,Madagascar and China Yunnan before and after heat treatment,the main color element of ruby is Cr and Fe/Ti is the reason why ruby shows blue-violet color.After the heat treatment,1986 cm- 1 and 2123 cm- 1 infrared (IR) absorption peaks produced by diaspora disappear.Burma ruby optimization process should premeditate the content of Fe.The treatment temperature is very important for Madagascar ruby optimization.The Raman spectrum demonstrates that there are different types of solid solution forming in ilmenite inclusions of Madagascar ruby with the temperature variation.The IR spectrum reveals 3310 cm-1 O－H absorption peak in untreated China Yunnan ruby.The spectral changes of rubies before and after heat treatment can be considered as reliable theoretical basis for non-destructive testing of gemstones.

The high quality β-FeSi2/Si films whose surfaces are smooth and even on Si (1 1 1) are fabricated by pulsed laser deposition (PLD), and the sizes of β-FeSi2 nanocrystals are about 20~50 nm. Photoluminescence (PL) characteristics of hybrid β-FeSi2/Si films are investigated at low temperature (20 K). The β-FeSi2/Si films show a relatively PL peak at 1540 nm, which corresponds to the band-band recombination of β-FeSi2. Er3 + is doped into Si layer, and the β-FeSi2/Si∶Er shows increase of PL intensity and is a novel approach to decrease the nonradiative centers. The infrared emission of β-FeSi2/Si∶Er films originat from the stark of 4I13/2→4I15/2 in Er3+ and band-band recombination in β-FeSi2.

According to the requirement of testing system for infrared up-conversion materials, Ta2O5 and SiO2 are chosen as high and low refractive index materials. The film system is designed and optimized by film software after testing the dispersive curve of the materials by spectroscopic ellipsometer. The edge filter is prepared on the quartz substrate through electron-beam evaporation system, and the end-Hall ion source assisted deposition is used to improve the refractive index of the materials. By adjusting parameters of the filter and improving optical controlled method, the error accumulation of thickness at the monitor wavelengths is solved. The transmittance of the films at 808、980 and 1064 nm wavelengths are less than 0.01%, and the average transmission is over than 90% at visible band. The test results show that the edge filter meets the requirements of the testing system for infrared up-conversion materials.