High repetition rate, narrow pulse, high beam quality and multi-watt level fiber laser seed plays an important role in the master-oscillator power amplifier(MOPA) structured high-power pulsed fiber laser. A high repetition rate linearly polarized pulsed Yb fiber laser seeder based on a directly modulated high-speed laser diode (LD) and a two-stage fiber amplifier is reported. A compact high-speed electric driver with tunable repetition rate and pulse width is developed for directly driving a laser diode operating at 1064 nm. The output from the LD is amplified by a two stage Yb fiber amplifier. A linearly polarized laser output at 1064 nm is achieved with a tunable repetition rate ranging from 5 kHz to 10 MHz and pulse duration time between 20 ns and 200 ns . Under the repetition rate of 200 kHz and pulse duration time of 100 ns, the pulsed fiber laser emits a near diffraction-limited linearly polarized pulse laser output with an average power of 800 mW, a polarization extinction ratio greater than 25 dB and a beam quality factor close to 1. It can be served as a seeder of high power linearly polarized fiber laser.

Tunable photonic crystal (PC) can control photonic band gap through changing the refractive index of liquid crystal (LC) by adding an electric filed, optical field or changing its temperature, which can change the orientation of LC′s direction vector. Plane-wave expansion method (PWM) is used to simulate the band gap of 2D tunable triangular lattice PC with structure of cylinder, square column and regular hexahedron column. The influence of changing rods shape, rotation angle and filling ratio on 2D phenylacetylene LC photonic band gap(PBG) are discussed when the substrate materials are Ge and Si respectively. It is find that there isn′t any absolute PBG in any condition, but big tuning range of TE polarized wave can be achieved by changing the index of liquid crystal. This structural parameter can provide theoretical instruction for field sensitive polarizer with great tuning range, and foundation of triturating waveguide optical switch, tunable filter and optical attenuator.

An optical-fiber fluorescence temperature detect system was proposed for hazard analysis and measurement of electromagnetic pulse of the electroexplosive devices(EED). The feasibility of the method was investigated in both theory and experiment. Different temperatures of EED can be obtained through different fluorescence lifetime, then the induced current is obtained, and finally the hazard of electromagnetic pulse of EED is measured. Experiment results show the system can analyze and measure the hazard of electromagnetic pulse of EED accurately and real-timely, so it is helpful to the research of security and reliability of EED.

Mode coupling, bend distortion and bend loss are important considerations in large mode area (LMA) fiber laser. Both mode coupling and mode distortion in the step-index fiber are studied theoretically in order to gain the effect of mode distortion on the beam quality. The dependences of mode power on propagation distance, effective bend radius are calculated with the bend radius experiencing sudden and gradual transition. Numerical simulations show that, if the distorted fundamental mode experiences smooth transition from bend fiber to straight fiber, the excitation of higher order modes could be ignored when the bend radius is larger than 3 cm. But the bend radius must be larger than 20 cm when the mode experiences sudden transition.

Phase-only spatial light modulator has been widely used in various fields for its high light efficiency and diffraction efficiency. However, the amplitude and phase of beam are required to be modulated simultaneously in some situations. To achieve complex amplitude modulation using a phase-only spatial light modulator, it is spatially varied diffraction efficiency in the first order direction by modulating the phase depth of a grating. Then, the phase modulation factor of grating is calculated using numerical inversion and construct a phase-only transfer function for complex amplitude modulation. Based on the theoretical analysis, doughnut beam is generated using a plane wave diffracted by a spiral phase plate modulated with Bessel-like amplitude based on the phase-only spatial light modulator. The experimental diffraction patterns are in good agreement with the theoretical intensity distribution.

A folded 4f pulse shaping system utilizing reflective spatial light modulator is constructed. Based on genetic algorithm and this folded 4f pulse shaping system, the two photon fluorescence′s intensity of coumarin 151 is successfully optimized by 6% with coherent control technique. Referring to the former scientists′ theory model, this experimental result is discussed.

High power operation of single-frequency Raman fiber amplifier (SF-FRA) is usually limited by the generating of stimulated Brillouin scattering (SBS). Based on the intensity equations combining SBS and stimulated Raman scattering (SRS), the limitation action to the output power of SF-FRAs for SBS is studied, the influence of different strain distributions to SBS inhibition is compared and an optimal solution of strain distribution is proposed. The simulation results indicate that strain gradients along Raman gain fibers can broaden the SBS gain profile and thereby suppress SBS. The location, stage number, value and length have the optima in the fibers′ receivable range of strain. The threshold of output power of SF-FRA can be increased about 100% under the optimum condition.

Algorithm of multipoint-pump model based on high-power fiber laser is studied. An fast approximate solution is derived by analyzing the characteristics of multipoint-pump model. This solution can quickly calculate the laser and pump power distribution along the fiber and the output power. The result of the percentage error is about 1% and up to 0.2%. The working time of approtimate fast algorithm is 2%~17% of that of numerical algorithm. The fast approximate solution solves the problem of long computing time and large amount of computation in the numerical solution. The model can be quickly and accurately used for the laser design and optimization of pumping.

The splice losses of photonic crystal fibers (PCFs) are theoretically and experimentally studied. For the two same PCFs with the triangular lattice, the splice losses are theoretically investigated by using finite element method (FEM) with perfectly matched layer (PML). The results show that the fundamental mode field mismatch induces the rotation losses with rotating one of the two PCFs when two optical axes are coincident. The rotation losses oscillate with increasing rotation angle, and the pitch between two nearest air holes has greater impact on the rotation losses than the air hole diameter. Optimizing the parameters of the arc fiber splicer, avoiding the air hole collapse and bubble generation, the rotation losses are experimentally investigated for two same PCFs. The measured rotation loss is coincident with the simulation results. Experiments can further reduce the splice losses of PCFs.

Biosensors are widely used in many fields, such as environmental detection, food analysis, military and medicine. Because of their high sensitivity and low noise, optical biosensors attract the most attention. As one kind of optical biosensors, liquid core optical ring resonator (LCORR) is small in size and has high Q-factor (up to 109), which has the potential to become a promising technology platform for future sensitive, miniaturized and lab-on-a-chip type sensors. The devices are investigated theoretically and experimentally in details. Ultra-thin micro-capillaries are fabricated by an improved technique which combines the outer etching and the stretching of the heated LCORR to accurately control the stretching velocity. The Q-factor and the sensitivity of LCORR are tested by injecting pure water, acetone, or NaCl solution of different concentrations into them. The LCORR show high sensitivity of about 61.5 nm/RIU and have great stability.

In order to analyze the amplification propertied of cryogenic Yb:YAG amplifier, based on pumping dynamics and pulse amplification performance, the ampification properties of cryogenics Yb:YAG amplifier is researched in simulation. The amplification performance on different size and concentration of crystal and different temperature and pumping power density is calculated. 3D thermal analysis model is used to simulate the thermal management effect. The results demonstrate that the pump power density, the size of laser medium and the temperature all have distinct effect on the optical to optical efficiency. In the temperature range of 100 K to 300 K, the optimal working temperature increase with the pump power density. With the same pump power density, the medium with different size have different optimal working temperature. In the condition of low temperature and strong pump, the thicker crystal has a better thermal management effect than a thinner crystal.

Adaptive optics technology is an effective way to alleviate the effect of turbulence on atmospheric optical communication. The atmospheric turbulence optical communication system model and bit-error-rate (BER) evaluation model are established, then the difference between the transmitter adaptive optics(AO) correction and receiver AO correction working in atmospheric optical communication on different turbulence intensities is simulated. The simulation results demonstrate that AO applied in communication is beneficial for increasing the received energy of detector and decreasing the BER. Correction of receiver AO is better than transmitter AO when aperture is 250 mm. However, transmitter AO can control the intensity fluctuation while receiver AO cannot. Therefore, both transmitter AO and receiver AO have the approximate efficacy to improve BER.

In order to diagnose X-ray line polarization of laser-produced plasmas, two crystal spectrometers have been used for measuring spectra. They can measure X-ray lines radiated by plasmas in directions of vertical and horizontal for detection of polarization degree. Measuring principle of X-ray polarization is studied in detail and mathematical computation is given. PET is dispersion crystal of spectrometer and X-ray spectra emitted from planar Al target are photographed by using spectrometers with two pieces of image plates (15 mm×35 mm) on 2×10 J laser facility. Experimental result shows that the spectra of He-like and Li-like in directions of vertical and horizontal can be obtained. Polarization degree of resonance line w is calculated based on intensity rate of resonance line w and intercombination line y. The relation between laser energy and X-ray polarization degree is found with experimental results of two shots and effect of polarization degree on diagnosis of plasma temperature is discussed.

A He-Ne beam is extended by a telescope system and a rotating ground glass is located near the focus of the telescope system. Different coherence degree of partially coherent beam can be obtained by changing the position of the rotating ground-glass plate. A partially coherent vortex beam can be obtained as the partially coherent beam passes through a spiral phase plate and the topological charge varies with the changing of different spiral phase plates. The research shows that the intensity distribution of vortex beam will change with the varying of the coherent characteristics. Moreover, with the decrease of the coherence degree of the incident beam, the intensity of the vortex beam center will not be zero, but increase. The image contrast of the light spot will decrease at the same time. The size of the hollow core of vortex beam has close relationship with the topological charge. The numerical simulations according to the experiment condition agree with the experiment results.

Bidirectional reflectance distribution function (BRDF) is an important reflective parameter of object surface. In many measurement systems, the value is achieved in a bow-liked mechanism which simulates the hemi-sphere space, and the incident illuminance and reflect luminance are measured respectively. To raise the uncertainty of BRDF value measuring, a new BRDF absolute value realization system is established. All factors which should be measured are translated to one factor in theory. In structure design, the movement of light source and detector are reduced indeed. The realization of angles for measurement depends on the rotation of sample in multi-dimension. This design is fit for BRDF absolute measurement and it improves the uncertainty.

The gradient and scattering force of Rayleigh dielectric particles induced by one-dimensional Airy beam were numerically investigated. The impact of particle radius and refractive index on the gradient and scattering forces were discussed. Trajectories of particles in the Airy beam were investigated and their relationships with particle radius, refractive index, and viscosity of surrounding medium were studied. Results validated that larger size and larger refractive index of particles resulted in larger gradient and scattering force. Particles in the Airy beam were firstly dragged into the nearest optical intensity peaks, and then oscillated along the parabolic trajectories and finally converged to the parabolic line. Smaller particles and larger viscosity of surrounding medium resulted in less oscillation and faster convergence to the parabolic line.

The partially polarized Gaussian Shell-model (PGSM) beam is proposed to describe the stochastic electromagnetic beam, and the array beam characteristics of PGSM beams combination are studied by means of Wigner distribution function (WDF). The analytical propagation equation of the array beams through a paraxial optical ABCD system is derived on the basis of the WDF. The intensity-moments characterization of the array beams is performed, and the important beam characteristic parameters such as the beam propagation factor (M2), beam width, far-field divergence angle and kurtosis parameter K of the array beams are expressed in a closed form. It is found that a flat-topped light-intensity profile can be obtained at a certain plane by a suitable choice of the beam number N, normalized separation, and also the coherence parameter of PGSM beams. The degree of polarization P of the array beams is no longer uniform upon propagation, it also changes additionally with normalized separation x′d.

In-situ monitoring ammonia volatilization is needed to improve nitrogen fertilizer utilization efficiency, reduce the waste of resources, and solve eco-environmental problems. Open multi-path NH3 monitoring system has been developed based on tunable diode laser absorption spectroscopy (TDLAS) technology combining with long open-path technique, wavelength modulation technique, fiber sensing technique and time division multiplexing technique, which are used for ammonia concentration in-situ detection after farmland fertilization at Fengqiu experimental station of agro-ecology, Chinese academy of sciences. Monitoring results show that the variation of ammonia concentration has an obvious diurnal periodicity, the general characteristic of diurnal variation shows that the concentration is high in the daytime and is low at night. Ammonia concentration reaches the maximum after a week for fertilization, and then decreases gradually. This system detects gas concentration with large range, high sensitivity, short response time without gas sampling. Thus, it is an effective method for ammonia volatilization monitoring in farmland environment.

The stochastic parallel gradient descent (SPGD) algorithm had been proved to be an effective system control method of image clarity in experiments and applications, which is independent of wavefront sensor and can optimize the system performance directly. The convergence speed and stability are determined by the value of the control parameters. The ranges of the control parameters are narrow, and out of range will lead to the vibration of the convergence or reduce the convergence speed. Based on SPGD, an image clarity test bed is built with a 52-element deformable mirror and a position sensitive detector. A method of automatic adjustment of parameters is proposed. The principle of SPGD control algorithm was demonstrated through examining the effects of gain and perturbation amplitude on correction capability and convergence rate, and the new method is proved to be effective. Experimental results show that by using the method of automatic adjustment of parameters, the ranges of parameters are extended. The practicality and convergence speed of the algorithm are improved with better convergence stability.

Imaging ladar can offer angle-angle-range-intensity images, which can facilitate target recognition. Imaging ladar has thus attracted much research interests. Imaging processing is a crucial technique for imaging lidar. And image denoising plays a pivotal role in image processing. A successful denoising process can greatly enhance the image quality. Image denoising for coherent ladar intensity images using non-local means (NLM) algorithm is investigated. Both simulated and real images are used. NLM algorithm and homomorphic NLM algorithm are respectively applied to denoise simulated single objective intensity images under different carrier to noise ratios. The results are compared with the denoised results of Lee filter and arithmetic mean filter. Finally, the algorithms are validated by real coherent ladar intensity images. The results show that two-level homomorphic NLM algorithm has the best performance from the aspects of background noise suppression, uniformity on the target and edge preserving.

Propagation of high intensity laser beams through long air paths suffering from energy loss and beam quality deterioration was experimentally demonstrated. For linearly polarized, 3 ns flat-topped laser pulse at 1053 nm, when the intensity-path-length product of main laser pulse was above 13.7 TW/cm, the spectrum measured at the end of propagation showed the occurrence of stimulated rotational Raman scattering as frequency shifts from main laser of 1053 nm to the sideband components produced during propagation, corresponds to the transition between rotational states of nitrogen molecules. During the process of stimulated rotational Raman scattering, the energy loss will vary dramatically with even minor changes in the intensity of input laser pulse. Furthermore, the near field degrades to intense speckle pattern and thickly dotted hot spots with characteristic diameters about 1mm were observed at an intensity-length product above 17 TW/cm.

Based on the generalized Huygens-Fresnel diffraction integral and the unified theory of coherence and polarization, properties of stochastic electromagnetic beams focused by a modulated lens are analyzed, the analytical expressions for the cross-spectral density matrix of a class of electromagnetic Gaussian Schell-model (EGSM) beams focused by an amplitude modulated lens are derived, and intensity distribution of EGSM beams focused by an amplitude modulated lens through numerical calculations is also analyzed. It shows that focused intensity distribution of EGSM beams is influenced by radius, location, transmittance of amplitude modulation, spatial position and the coherence length. When the radius of amplitude modulation takes a certain value, it appeares that focusing spot is extremely compressed and focusing central spot has a large energy at this time. Different shapes of intensity distribution can be gotten by changing the parameters of radius, location, transmittance of amplitude modulations and spatial position, and the coherence length.

Chaotic synchronization of semiconductor lasers with the coupling and its application in optical logic gates are studied. The constructions of the fundamental all-optical and optoelectronic logic gates using two chaotic lasers due to the mutual coupling and their computational principle are presented theoretically. All-optical logic gates are finally performed by synchronizing or unsynchronizing appropriately the two chaotic states via modulating the coupling light. And the optoelectronic logic gate is implemented by synchronizing or unsynchronizing appropriately the two chaotic states via modulating the current and coupling light together. All-optical XNOR, NOR, NOT, optoelectronic logic gates and their logic computational methods are presented. Numerical simulative results validate the feasibility of the system.

Laser radar can provide the four-dimensional image of target (intensity image and three-dimensional range image).The clutter in the complex background is easily segmented in the searching and monitoring process. It can improved the space between the aspect of target detection and recognition. Because of the limitation of hardware, traditional laser radar is difficult to meet the requirements of high frame-rate and wide field of view (WFOV). A design scheme is presented by using the streak tube imaging lidar (STIL) with high detection sensitivity as the detector of searching and monitoring, and then the corresponding experiment equipment is built. 45° WFOV imaging is completed using the 532 nm YAG laser which pulse energy is 20 mJ. The experimental results show that the complex scene 4-D images with far-distance and WFOV are collected by using STIL, and it contribute to full-coverage and unleak pixels imaging. It has good application foreground.

The application of pulsed laser welding technology increases in precision manufacturing. The study on the deformation characteristic of pulsed laser welding has a special significance for improving the quality of welding. A three-dimensional finite element method model is established by the shell element in ANSYS. The model simulates the process of pulsed laser welding of Hastelloy C-276 with 0.5 mm thickness. Experiments are carried out to measure the welding distortion, and the simulation results have a good agreement with the experiment results. Then, the model is used to further study the effect of single-pulse laser energy input on the transverse shrinkage distortion and buckling distortion. The results show that the periodic oscillation of the immediate distortion is caused by the pulsed laser wave. With the single-pulse laser energy input increasing, the transverse shrinkage and buckling distortion are improved.

A comparatively uniform hardened layer affected mostly by dimensional intensity distribution is commonly pursued in laser hardening engineering. A semi-quantitative mathematic model is proposed for two-dimensional spot-array to get uniform hardened layers, in which a homogeneous temperature field is used to get the rates of intensity of every spot. The examples of inverse design of intensity distribution for 3×3 and 5×5 two-dimensional spot-arrays are given. The feasibility of the inverse design method is proved by numerical simulation based on finite element (FE) analysis and experiments. Results show that the uniformity of hardened layers is improved by the inverse method.

Using sapphire (Al2O3) as the substrate, the influence of the parameters of patterned substrate (PS) such as pattern choice, radius and gap of primitive cell on LED efficiency is studied by software design and simulation. The results indicate that the patterned substrate structurea hemisphere structure whose radius and gap are 1.25 μm and 0.5 μm respectively is the optimal structure. Then the LED of this kind of structure is gotten by means of wet etching, and its efficiency increases by 33% compared with normal LED. The reason why the PS technology can increase LED efficiency is analysed, which is that it can improve the chip quality and increase internal quanntum efficiency.

2011-03-02

Combining with the lαβ color space and the nonsubsampled contourlet transform (NSCT), a novel fusion algorithm for infrared and color visible images based on the color transfer and information entropy was proposed. Firstly, the R, G, B bands of the color visible image were averaged and then the intensity component image was attained. Secondly, the attained component image and the infrared image were merged based on the NSCT and then a grayscale fused image was obtained. Lastly, a color transfer method based on the lαβ color space was employed to transfer the color information of the color visible image into the fused grayscale image and then the final fused color image wss attained. When the grayscale visible image and the infrared image arefused, according to the physical characters of the infrared image, a weighted averaging scheme based on the local area mean and local area information entropy was proposed for the lowpass subband coefficients. As well, according to the distribution differences of the noise and the geometric characters of the image in the NSCT domain, a selection principle based on the local area direction entropy and the local area energy was proposed for the bandpass directional subband coefficients. Experimental results demonstrated that the proposed algorithm not only can extract the abundant background information of the visible image and the target localization information of the infrared image, but also can make the fused color image maintain the nature color information of the visible image as much as possible.

To meet the requirements of high frame rate, high resolution and large dynamic range in laser applications, a high-speed CCD camera imaging system is designed by using conventional CCD as the detector. Interline area CCD array KAI-2020D′s working principal, timing generation and driving, and two-channel image data′s processing are introduced; a integrated video processing chip is used to generate the high-speed timing signals and high-speed drivers are used to drive horizontal signals; controller′s internal memory is used for signal processing such as processing the image data and depressing the data transfer rate asynchronously; exposure time is digitally controlled through the electronic shutter, overcome the disadvantage that CCD dynamic range can not meet the requirements of the different range of incident light intensity. The results show that the exposure time can be divided into 5 stages, each stage is 100～2000 μs, minimum adjustable step is 25 ns, signal to noise ratio (SNR) is more than 40 dB, dynamic range is not less than 58 dB, and the maximum frame rate is 35 frame/s, so the camera system meets the requirements of laser applications.

High-resolution space remote sensor needs large system aperture, but it is hard to fabricate one single mirrors with large aperture, furthermore, limited by size of the rocket, and aperture of primary mirror can only be enlarged in a certain degree. This problem is solved by using several segmented mirror to build one large mirror. But surface error and radius mismatch of segmented mirror will decrease performance of the whole system. Substitute recent methods which use actuators of segmented mirrors to correct these errors, a new method using deformable mirror that lies in the exit pupil corrects those errors is proposed and simulation has been done. Simulation results show that this method can correct those errors very well in certain cases.

A design of metal-dielectric non-polarizing beam splitter in a cube is proposed, using the needle optimization. The digital simulations of the splitter′s reflectance and reflection-induced retardance are presented. The effects of incident angle on the splitter′s performance are analyzed. Both amplitude and reflection-induced retardance of the splitter meet the requirement ignoring the phese of transmitted light. The differences between both components and the reflectance target which is 50% are less than 0.22%. The reflection-induced retardance is less than 0.29° in the range of 540~560 nm with the incident angle of 45°. When the incident angle deviates with the error of 1°, the reflectance of both components is influenced slightly and the reflection-induced retardance strongly depends on the incident angle.

An online gas analyzer with taking HF gas detection as an example based on tunable diode laser absorption spectroscopy (TDLAS) technique is presented. In order to eliminate or at least reduce the measurement uncertainty and gain high reliability, a close-circle digital-control module (D-CM) with functions of digital signal generator, digital lock-in-amplifier, data acquisition and data preprocessing have been developed to substitute the multi-independent analog boards in our previous system. Meanwhile, the signal correlation method is used to lock the absorption wavelength to reduce the effects of the ambient temperature and other factors. Utilizing the digital-control module and the digital signal processing techniques in the field tests, the sensitivity and stability of the TDLAS system have been greatly improved. Furthermore, smaller volume, lower cost and weaker signal distortion are achieved.

The double hetero-junction InP/InGaAs/InP material is grown by molecular beam epitaxy. The back-illuminated 512×1 elements InGaAs photo-detectors are fabricated using the improved process including the profile etching, effective passivation and ohmic contacts. Response spectra of 512×1 elements InGaAs photo-detectors range from 0.95 to 1.7 μm and the average peak resoponsivity is 0.9 A/W. 512×1 elements InGaAs photo-detectors are connected to readout circuit with capacitive transimpedance amplifer (CTIA) input stage by transitional base plane using In bump flip chip so that 512×1 elements InGaAs module is fabricated. The 1024×1 elements InGaAs FPA are fabricated using the two 512×1 elements InGaAs modules joint by interlaced effective pixels and are sealed in metal package with thermal electrical cooler (TEC). The response non-uniformity, blind pixels ratio and average peak detectivity of 1024×1 elements InGaAs FPAs are 8%, 1% and 7×1011(cm·Hz1/2)/W, respectively at room temperature. The working temperature of FPAs assembly is stabilized by using TEC, power consumption of FPAs assembly at 5 ℃ is 3.10 W.

An all-solid-state, high-brightness and sub-nanosecond 1.319 μm continuous active mode-mocked laser was reported. The oscillator was adopted folded thermal stabilized cavity with four mirrors. The gain modules were two NdYAG modules pumped by diodes. The laser was mode-locked by an active amplitude-modulated acousto-optic mode-locker(AOM). An average output power of up to 9.6 W with an excellent stability and beam quality with a M2-value lower than 2 was obtained when the laser was mode-locked. The repetition rate was 100 MHz and the pulse width was about 630 ps.

A LED secondary-optics designing is an important step which decides the output efficiency and the uniformity of stage lighting. A green stage lighting requires that LED stage lights can increase the total flux and form a 4~6 m uniform circular spot at 30 m away. However, the LED stage lights currently on the market cannot meet these requirements. This article describes a new model of lighting design which can achieve both higher output power and more uniform circular spot. The model uses a uniform light stick, reflective prism and reflector to meet a longrange requirements. And the final output efficiency can be as high as 26%.

Based on the analysis of energy loss in a laser diode, we optimize the structure of the laser diode and metal organic chemical vapor deposition (MOCVD) growth condition. By low pressure (LP) MOCVD, GaAsP/GaInP/AlGaInP strained quantum well large optical cavity structure is grown, and high power continuous wave (CW) 808 nm laser diode is fabricated. At 25 ℃ under CW operation condition, an output power of 11.5 W is obtained at 10 A current, with the threshold current being 1.15 A. The wall-plug efficiency reaches 62%. With the operation current of 5.5 A at 40 ℃, less than 2% output power degenerates over 1000 h.

A laser solid forming/repairing system is developed based on Motoman SSF-2000 robot where high-precision robot powder feeding system, real-time vision system and inert gas protection system are integrated altogether and high-precision forming and repairing process can be achieved. The computer communicates with the robot by utilizing MotoCom32 communication interface to control all the processing parameters about the automation of the laser processing operation. When a simple part is formed or repaired, the system programs by the way of controlling teaching plate. When a complex part requires forming or repairing, the control system reads the DXF file produced by AutoCAD which records the geometric information of the curve, and calculates the curve to a large number of short lines to meet the accuracy requirement. By the real-time communication between computer and the robot, the control system can update the motion trail data. Experiments show that the system can complete the processing of laser solid forming and repairing excellently.

In optical Kerr pulse clenear, the used fibers with different mode birefringence degrees can produce different coherent coupling degrees at the two polarization light. Different coherent coupling degrees will affect the output of the optical Kerr pulse clenear. The pulse, spectrum, transmissivity of pulse itself and system with different mode birefringence degrees are simulated. For high birefringence fiber, the coherent coupling effect at the two polarization light can be neglected. For common single mode fiber with medium birefringence degree, the change of pulse′s transmissivity is about ±1%. But for low birefringence fiber, the infection of the coherent coupling is much higher, and the coherent coupling affect also has much higher infection for the temporal and spectral shape and the transmissivity of the pulse itself.

Experimental results of laser diode (LD) pumped monolithic non-planar ring resonator (NPRO) tunable single frequency lasers are reported. 1064 nm and 1319 nm lasers with the power of 1080 mW and 580 mW are obtained by LD pumped monolithic NPRO Nd∶YAG crystal, whose corresponding optical-optical efficiencies are 40.9% and 14.3%, respectively. The longitudinal mode and the linewidth of the lasers are measured using the scanning Fabry-Perot interferometer, which shows both of the two lasers are operating in single longitudinal and fundamental transverse mode, the linewidth of the two lasers are Δν1064 nm=41 MHz and Δν1319 nm=150 MHz, respectively. The beam quality of the two single frequency laser are measured by a beam quality analysis, which shows the beam quality factor are M21064 nm=1.14 and M21319 nm=1.15, respectively. The frequency tuning of the single frequency lasers are also studied by adjusting the temperature of the crystal. The maximal tuning range of 1064 nm laser is about 48.2 GHz with a average tuning coefficient of 1.42 GHz/℃; the maximal tuning range of 1319 nm laser is about 12.7 GHz with a average tuning coefficient of 1.42 GHz/℃.

3D scanning system for dam monitoring based on single-point laser sensor can obtain the spatial 3D information directly, which can realize real-time and efficient monitoring of disasters, such as translation of the dam, crack, break, landslides, etc. So it has a broad application prospect because of high degree of automation, simple operation and field scanning without stop. Research has been focused on the development of 3D laser scanning system based on single-point laser sensor, and the approach of system integration is established. The selection of the core single-point sensor is finished and control system is developed to build the prototype. Based on the statistical analysis of possible values of output parameter, the data ball model and rectangular boundary model are established to investigate the mechanism of system integration. For data distortion resulted from the inconsistence of original points of all sensors, coordinate normalization algorithm is proposed to complete the system calibration. Besides, the correctness and necessity of the system calibration work is verified through real experiment.

An empirical model of joint polynomial, with respect to direct voltage-current and junction temperature, based on direct voltage measuring method, is presented. The empirical model is applicable in on-line measurement of junction temperature of light emitting diode (LED) for appointed type in any heat dissipation environment, and the limitation and complication of conventional direct voltage measuring method is modified. On the basis of six-parameter empirical models consisting of variables of voltage-current, every parameter combination is respectively applied to the least squares fitting and the standard deviation criterion. Eventually, the result indicates that four-parameter model is an optimum empirical model. Validity analysis based on the actually measured value demonstrates that the actual values fit well with the calculated values. Under the premise of the defined model, the error is produced by the large intervals and uneven characteristics of data. Improved empirical model is carried out by enhancing the density of sampled data, relinquishing the bad data, and duplicated fitting.

A fiber Bragg grating (FBG) strain tube, which is fabricated by affixing bare fiber grating to a strain tube, is designed to solve existing problems in deep displacement monitoring of pipeline landslide. Strain measurement principle of fiber Bragg grating and deep displacement calculation method of landslide measured by FBG strain tube are presented. According to results of performance test, strain sensitive coefficient of a FBG strain tube is 0.58 pm/10-6. According to field trials, measurement results of FBG strain tube are mostly agreeable with these of declinometer.

Holographic storage characteristics of the hydrophilic Mg(OH)2 nanoparticle dispersed acrylamide-based thick photopolymer are studied. It is illuminated under the incident wavelength of 514 nm of Ar+ laser. Experimental results show that, not only the samples dimensional stability can be improved during the holographic exposure, but also the diffraction efficiency and other performance parameters can be improved in the hydrophilic Mg(OH)2 nanoparticles dispersed photopolymer compared with those traditional samples. There exists the optimum concentration of Mg(OH)2-nanoparticles that maximize diffraction efficiency to 93.7%, the maximum refractive index modulation is 2.13×10-3 and volume shrinkage reduces to 1.61%. The analog image is stored in the materials and reconstructed holograms have good fidelity. All of the results demonstrate that the Mg(OH)2 nanopartical dispersed acrylamide-based photopolymers is an effective material to improve the holographic properties.

The Yb3+:Y3NbO7 polycrystalline powder is fabricated by the solid-phase method using Li2SO4 as flux. The structure of Yb3+:Y3NbO7 is determined by Retvield fitting to X-ray powder diffraction. The photoluminescence spectra of the Yb3+:Y3NbO7 power show three peaks at 975, 1040 and 1083 nm. The absorption spectra has the peaks at 863, 913, 975 and 1040 nm. The Yb3+:Y3NbO7 has relatively strong crystal field with the group 2F7/2 state splitting value 1022 cm-1. Compared with Yb3+YAG, Yb3+:Y3NbO7 with the large absorption and emission spectra bands is advantageous for tunable and ultrafast pulse laser output and will become a new promising Yb laser material.

Annealing experiments are performed at 450 ℃ in N2 atmosphere for different time on vanadium oxide films prepared by RF magnetron sputtering. Changes in surface morphology, electrical, structural properties and chemical composition are studied. From resistance-temperature (R-T) measurement and calculation, it is found that both R and temperature coefficient of resistance (TCR) of the films are increased after annealing. From scanning electron microscope (SEM) and (AFM) atomic force microscope images, it is observed that both grain size and surface roughness are aggrandized greatly after annealing. X-ray diffraction (XRD) analysis shows that the as-sputtered film is almost amorphous while new phases V2O5(0 0 1), VO2(0 1 1, 1 -1 0) and V2O3(1 1 3) appear in the annealed films. X-ray photo-electronic spectrum (XPS) quantitative analysis indicates that the annealed films are oxidized possibly due to adsorbed oxygen to lattice oxygen transition.

A Fabry-Pérot fiber-optic humidity sensor with porous silicon film as sensitive element is proposed. The volume of liquid water in porous silicon film tends to dynamic equilibrium due to capillary effect. Water content in porous silicon film increases with the increase of the relative humidity, which results in the change of effective refractive index of porous silicon, and therefore shifts the reflected spectrum. Based on theoretical study, the experimental results demonstrate the feasibility of use of porous silicon thin film as humidity sensor. The characteristic wavelength shifts 9.6 nm as the relative humidity changes from 11% to 97%. By data fitting of the experimental results; the effective refractive index changes under different humidity conditions can be reckoned. A red-shift of interference spectrum fringe is monitored, which is consistent with the theoretical calculation.

GeC coatings with different refractive index, DLC coatings and dual band IR protective coatings are deposited onto Ge substrates by means of magnetron sputtering. The IR transmittance and micro hardness are investigated by Fourier transform infrared spectroscopy (FTIR) and micro hardness meter, respectively. The hardness of the samples is enhanced obviously by GeC, DLC and the dual band IR protective coatings. Furthermore, the dual band IR protective coatings have high transmittance of larger than 94% in both 3.7~4.8 μm and 7.5~10.5 μm range, and also have greater hardness than both GeC and DLC samples. The dual band IR protective coatings pass the environmental testing according to GJB2485-95.

A graphene-water solution and graphene-polyvinyl alcohol composite are fabricated from graphite by wet-chemistry techniques. The research shows that both of graphene solutions and the composite have saturable absorption ability. The atomic layer grapheme possesses wavelength-independent ultrafast saturable absorption, which can be realized mode-locking in a large-wide-range wavelength. The cost of the atomic layer graphene is far lower than that of semiconductor saturable absorber mirror (SESAM) as a mode-locker.

It is difficult to determine the mixtures of phenol, m-cresol and thymol directly by routine analytical method since their fluorescent spectra are overlapped closely. Excitation-emission matrix fluorescence technology combined with parallel factor (PARAFAC) algorithm is used to determine phenol, m-cresol and thymol simultaneously. Results show that the concentrations of phenol and thymol resolved by PARAFAC are better than the actual one when three compounds are determined simutaneously, and the average recoveries are (95.23±2.55)% and (102.8±1.97)% respectively. However, the result of m-cresol is not satisfied, and the resolved concentration deviates from the actual one severely. Moreover, two component compounds mixed with each other among phenol, m-cresol and thymol are also studied, and the result is better than that obtained in the mixtures contained all of three phenolic compounds. In addition, the accuracy of the PARAFAC algorithm is also evaluated through figures of merit. The method using excitation-emission fluorescence combined with PARAFAC algorithm can determine phenol, m-cresol and thymol simultaneously with a good selectivity, and the limit of detection achieves to 1 μg/L.

In laser cladding, the movement of the metal powder particles influences the cladding results directly. However, the movements of the metal powder particles are too hard to measure because the average diameter of the particles is about 50 μm and the movement behavior is very complex (collision of each other). The image process method based on digital particle image velocimetry (DPIV) technology is used to recognize the most particles. By this means, two images of the particle stream with a time interval are provided to determine the displacements of particles. Therefore, the velocity-vector field of the whole powder stream is obtained. Then, the convergence angle and the divergence angle of the powder flow can be measured by the velocity vectors, and the convergence region can be determined by the region of the maximum intensity of light. Results show that DPIV meets the needs of laser cladding and plays the role of guidance.

The core glass and cladding glass of gain guided index-antiguided (GGIAG) fiber doped with Yb3+ are prepared and Yb3+GGIAG fiber with core diameter of 120 μm, inner cladding diameter 220 μm and outer cladding diameter 260 μm is drawn by the rod-in tube technique. Yb3+GGIAG fiber has a lower core refractive index than the surrounding cladding′s, Δn=-0.00094. The beam quality factors in both horizontal and vertical directions are observed, M2x≈2.724 and M2y≈2.642 when signal light (at 1040 nm) with single mode is propagating in Yb3+GGIAG fiber with different length, which indicates single mode approximation behavior of Yb3+GGIAG fiber. The mode field diameter of Yb3+GGIAG is calculated to be more than 150 μm.

Aluminum and lanthanum doped zinc oxide transparent conductive films were prepared by sol-gel dip-coating method, all the films were annealed under reducing atmosphere (VN2VH2=964). The effect of the aluminum doping concentration and the annealing temperature on the microstructure, optical and electrical properties of the ZnO(Al,La) films were investigated by a D/Max 2500 X-ray diffractometer (XRD) with CuKα radiation, a Hitachi S-4700 field-emission scanning electron microscope (FE-SEM), UV-2110 spectrophotometer and SDY-5 four-point probe instrument. The results showed that with the annealing temperature increasing, the film grew more preferentially along the (002) plane of the film, the average grain size increased, the electrical resistivity decreased and the optical transmittance increased; With the Al doping concentration increasing, the diffraction intensity of the films which were annealed at high temperature was high, the average grain size decreased, the porous morphology of the films increased, the electrical resistivity decreased, after up to 1%, the electrical resistivity increased with Al doping mole fraction. The average optical transmittance of the best film is more than 85% in the visible region and the electrical resistivity is as low as 1.78×10-3 Ω·cm, it was obtained under the Al doping concentration 1% and annealing temperature 550 ℃.

The photorefractive effect of the organic/inorganic polymer composite based on the chemically hybridized CdS-PVK nanocomposite doped with DO3 NOL chromophores and plasticizer 9-ethylcarbazole (ECZ) is reported. The CdS particles, acting as photosensitizers, show a nanoscale size in PVK adopting transmission electron microscopy. The photoluminescence (PL) spectra of CdS-PVK nanocomposite are studied. In order to approximate relative energy-level positions, the oxidation/reduction potentials of the chromophore DO3 are investigated by cyclic voltammetry. An asymmetric two-beam coupling confirms the photorefractivity of CdS-PVKDO3ECZ gain of 35.4 cm-1 and a diffraction efficiency of 3.4% is obtained without the external field.

Carbon fiber reinforced polymer (CFRP) is widely used for making leaf joint and cartridge receiver with the development of material science and structural mechanics. The main kind of flaw is delamination, but this type of flaw can not be tested easily by using tradition method. In order to promoting the product quality, pulse theography is developing and becoming perfect. But the test sensitivity of pulse theography can not be definited exactly, in order to solve this problem, pulse thergraphy method is used for testing artifical parts with different delamination flaws. Pulse theography method can find and locate the delamination flaw in CFRP, can measure the size and depth of the flaw. When the percentage of wide and depth is lower than 3, the test sensitivity is lower than 10%, and the sensitivity is becoming low as the size become small and the depth become deep.

The stealthy effectiveness of optic/laser stealth coating is affected by many factors, so it is hard to evaluate its synthetic stealthy effectiveness. To quantize the stealth effectiveness of optic/laser stealth coating exactly, analytic herarchy process (AHP) method acquiring relative weight of the factors which affect the stealthy effectiveness of optic/laser stealth coatings is used, and the stealthy effectiveness synthetic evaluation model of the optic/laser stealth coated by fuzzy synthetic evaluation method is established to quantize the stealth effectiveness of the coatings. The model is applied to some optic/laser stealth coatings samples, the result conforms that the model can quantize the stealth effectiveness of optic/laser stealth coatings accurately, and the model also can provide scientific decision-making for the selective preferencs of coatings.

Considering optical thin films irradiated by laser at oblique incidence, the electric vector is orthogonally decomposed into s-polarization and p-polarization. And based on the Maxwell equations, electromagnetic-field distribution in optical thin films is obtained. Then the optical properties of optical thin films are numerically analyzed. The results about high-reflection thin film show some features as follows. With the increase of the angle of incidence, the reflectance, transmittance and absorptivity of s-polarized light have tiny fluctuations. But for p-polarized light, obviously, the reflectance shows gradually decrease while the transmittance and absorptivity are opposite. And near the central wavelength in high-reflection thin film, both s-polarized light and p-polarized light have a high-reflectance broadband. Compared with s-polarized light, the broadband for p-polarized light is manifestly narrower and the absorptivity is relatively higher.

An analytic solution to the scattering of an arbitrary incidence Gaussian beam by a coated spheroidal particle is constructed by expanding the incident and scattered electromagnetic fields in terms of spheroidal vector wave functions. The unknown expansion coefficients are determined by a system of linear equations derived from appropriate boundary conditions. Numerical results of the normalized differential scattering cross section of the conducting and coated spheroidal particle are evaluated, and the scattering characteristics are discussed concisely.

Laser detectors based on manganite oxide heterojunctions of LaxCa1-xMnO3/Si, with x=0.67 and 0.40 respectively, were fabricated, and their photovoltaic effects were investigated induced by 532 nm and 1064 nm continuous wave laser. The photovoltage obtained in heterojunctions with good p-n characteristics were large when irradiated under 532 nm laser. The transient peak voltage of the heterojunctions were observed when the laser was turned on and off, and increased with chopping frequency and showed saturate tendency finally. Double peak in photovoltaic signals were observed in the heterojunctions when 1064 nm laser was turned on and off, which was contributed to be the combination of photovoltaic effect and thermoelectric effect.

Adsorption of Cu on the polar GaN(0001) surface in a 2×2 geometry is studied by the generalized gradient approximation (GGA) with ultrasoft pseudopotential within the density functional theory (DFT). Different adsorption sites and the effects of different coverages are considered. It is found that copper atoms preferentially adsorb at the H3 sites compared with doing at the T4 site, while the copper adsorption on top of a gallium atom (atop position) is totally unfavorable in each coverage considered. Both GaN(0001) surface and its adsorption have the semi-metallic behaviour and remain to be of n-type conduction character.

Four water-soluble benzylidene cyclopentanone dyes are synthesized for photodynamic therapy (PDT) by introducing different numbers of carboxylate groups on their periphery. Their photophysical and photochemical properties are investigated systematically. The results show that the water solubility of these dyes is significantly enhanced after modification. All dyes exhibit large two-photo absorption (TPA) cross-section in near infrared (IR) range, which can generate both superoxide anion radical and singlet oxygen species under visible illumination. One-photon PDT experiments indicate that four novel dyes displaye low dark cytotoxicity. However, only the dye Y1 presents excellent photodynamic activity, which highlights the role of moderate lipophilicity for PDT dyes. Further cellular experiments reveals that Y1 had obvious two-photon induced cytotoxic effect on human rectal cancer 1116 cells. The result indicates that Y1 is a potential photosensitizer for two-photon induced PDT.

By using DMo13 software of first-principle pseudo-potential approach based on the density functional theory, theoretical calculation is done on ZnO nanowires at the condition that N atoms are incorporated at different positions and surfaces passivated and not passivated by H. Structural parameter, doping formation energy and electrical structure are analyzed systematically. The result shows that lattice parameter of ZnO nanowires in the growth orientation of [0 0 0 1] plane changes under the conditions of these two kinds of surfaces. Passivation of H leads to an increase in the bond length of Zn-O and makes it easier for N atoms to gather at the surface when doping. Besides, under the condition of two kinds of surfaces, solid solubility will be higher, electro-conductibility will be stronger and p-typed ZnO nanowires will be formed more easily when doped N atoms are nearer to the surface.

Experiments of laser aided direct metal deposition of 1Cr13 martensitic stainless steel thin walls are carried out. Thermal histories of two specified points in the substrate are recorded during the whole deposition process. Microstructure and microhardness in the vertical direction of the thin walls are observed and tested respectively. The results show that the microstructure and mirohardness distribution in the martensite stainless steel parts made by laser aided direct metal deposition usually exhibit specific features because of the multilayer deposition process. Microhardness near the joint region is higher than 350 HV due to the exist of pearlite. However, the microhardness in the upper region is about 200 HV.

In conventional mechanical punching, the size of the punched holes is limited due to the difficulties of tool fabrication, the difficulties of punch-to-die alignment and the increasing costs of tool fabrication. In order to overcome these problems, a novel micro-hole manufacturing technique based on laser-driven flyer punching is presented. A flyer is irradiated by a short and intense laser pulse, resulting in a high speed and high punch pressure. When the flyer is loaded on the workpiece, the bending and axial stretching of workpiece would take place, and the workpiece could be sheared off around the corner of die. The single micro-hole mould with 1 mm diameter is machined by the micro-milling cutter on printed circuit board. The micro-punching experiment is conducted on copper successfully by controlling the laser energy and good edge quality is obtained. The experimental results are observed by an XTZ-FG stereo-microscope and an AxioCSM700 scanning microscope. The novel process of punching is also numerically studied, which confirms the feasibility of this method and lays the foundation for optimizing the process parameters and reducing the number of experiments.

In order to obtain wear and corrosion resistant Fe-based alloy coating, laser cladding of D577 alloy powder on 45# steel is conducted using CO2 laser. The microstructure, hardness, friction and wear performance are investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometer (XRD), micro-hardness meter, and reciprocating wear test machine. The experimental results show that the coating consists of γ-Fe single phase, there is a good metallurgical bond between coating and substrate, and the coating is free of crack and pore defect. The micro-hardness of the coating is 630~650 HV. The nano-hardness and elastic modulus of the coating are 8.58 GPa and 235.82 GPa, respectively. D577 alloy laser cladding coating can effectively improve the wear resistance and electrochemical corrosion performance of 45# steel substrate.

There are many defects in the Gaussian model, which is used to describe the far-field distribution of semiconductor lasers. Though the Gaussian distribution is applicable to the description of the far-field distribution parallel to the junction, it is not suitable to describe the far-field distribution perpendicular to the junction. With the same spatial extensions, the angular spreading of the Lorentz-Gauss distribution is higher than that of the Gaussian distribution. Therefore, the Lorentz-Gauss distribution provides more appropriate model than the Gaussian distribution to describe the far-field distribution perpendicular to the junction of semiconductor lasers. However, the researches show that the Lorentz-Gauss beams are only valid for the description of the highly divergent fundamental mode. Moreover, the high power semiconductor lasers also generate the highly divergent higher-order modes. The purpose of this paper is to construct an orthogonal and complete family of higher-order Lorentz-Gauss beams. By analyzing the propagation properties of higher-order Lorentz-Gauss beams, it is proved that higher-order Lorentz-Gauss beams are more appropriate than Hermite-Gauss beams to describe the highly divergent higher-order far-field distribution of semiconductor lasers.

The influences of gauge blocks gestures on calibration of coordinate measuring machine attach increasing attention. In particular, the effects of gauge blocks gestures on metrology coordinate measuring machine of which the measurement accuracy is hyper-0.6 μm+1000/L cannot be ingnored. Adopting laser interferometer as measuring datum, length deflection of gauge blocks are measured in different gestures by developing an adjustable platform. An advance multi-point bracing means is proposed to minish length variation of gauge blocks. The results of experiments indicate that the maximum length deflection of gauge blocks is +0.21 μm by adopting multi-point bracing means. According to the formula of error uncertainty for coordinate measuring machine the standard uncertainty is recalculated to be 0.75 μm.

Theoretical and experimental vibration spectra of biochanin A in frequency range from 0.5 to 2.4 THz are investigated. Under room temperature and vacuum conditions, the absorption peaks were observed at 0.86, 1.15, 1.60, 1.74, 2.12 and 2.28 THz. In parallel with experimental study, 6-31G* basis set and density functional theory (DFT) are applied to obtain structure and vibrational frequencies of isolated genistein molecule at gas phase. The observed vibrational spectra are assigned according to DFT calculations. Results show that theoretical calculations are in good agreement with experimental data. The observed vibrational peaks in frequency range of 0.5~2.4 THz are mainly induced by collected vibrations of molecule. The research is helpful to understand the role of biochanin A in biological reactions.

Infrared polarization imaging technology is a new detection technique, and it can distinguish background and target through the infrared polarization characteristics of target. At the present time, infrared polarization characteristics of targets are always studied by experiments that acquire images including degree and angle of linear polarization. It is known that the infrared polarization information is closely related with many factors, therefore it can be not acquired required data only through polarization image. In order to study infrared polarization imaging theory and infrared polarization characteristics of object closely, infrared polarized emissivity model and control equation for infrared polarized imaging through polarized bidirectional reflectance distribution function are derived, and mathematical expression for polarization information is given, and it is analyzed in theory by considering the influence of effect refractive index and roughness of target surface. This work will provide theory guidance for target detection based on infrared polarization imaging.

A new digital detail enhancement algorithm based on Gaussian and restriction filter is proposed. This algorithm adopts a base component and a detail component extracted by Gaussian and restriction filter, and the two components are compressed through gamma transform to fit the display dynamic range, and then they are recombined to obtain the output-enhancement image.The proposed algorithm is compared with traditional unsharp masking (UM) algorithm and the effectiveness of the proposed algorithm on restricting the ripple phenomenon is shown. Experimental results demonstrate that the proposed algorithm has good performance in detail enhancement.

Three airborne campaigns with ALADIN (an atmospheric laser doppler instrument) airborne demonstrator (A2D) were performed in November 2007, December 2008, and September 2009, respectively. Sea surface return measured during the campaigns is analyzed for the sea surface reflectance. With consideration of the contribution of whitecaps, specular reflection and the subsurface volume backscattering to the sea surface reflectance models, the measured sea surface reflectance was compared to the models for the wavelength of 355 nm. The observations show that the expected effect of the wind stress on the sea surface reflectance and allow new insights into the significant contribution of subsurface reflectance, and contribution from the subsurface is estimated by using lidar signal for large incidence angles.

A nonlinear Tavis-Cummings model describing interaction of two atoms with a single mode nonlinear field is presented. The relation between it and other cavity quantum electrodynamics (QED) model is analyzed. Berry phase and eigenvalues of this quantum system are evaluated explicitly, and how they change with system parameters is studied by numerical simulation. The results show that they relate to the dipole-dipole coupling strength between two atoms and atom-field coupling constant and nonlinear coefficient of field. Besides, the influence on Berry phase of nonlinear coupling effect increases with the addition of the number of the photon.

The enhanced transmission spectra of sub-wavelength Sierpinski fractal structure are presented by means of THz time domain spectroscopy (THz-TDS). It is found that there are several transmission peaks and forbidden band gaps with the frequency selectivity in the transmission spectra. The transmission peaks and forbidden band gaps increase with increase of the structure arrays. Further analysis reveals that the transmission enhancement is caused by a complicated waveguide coupling effect, that is, THz transmission enhanced in low frequency region mainly results from the waveguide coupling in low level square holes, while in high frequency region mainly results from the waveguide coupling in high level square holes.

A new method to measure real-time sensitivity of Doppler lidar is presented, to solve the sensitivity uncertainty problem caused by the spatial and temporal change of aerosol during wind detecting. Two receive channels of rotational Raman spectrum are added, system receives elastic scattering spectrum and rotational Raman spectrum respectively with beam splitters and interference filter so as to acquire the aerosol backscattering ratio for sensitivity calculation. The two rotational Raman spectrums, central wavelength of 531.3 nm and 528.7 nm, are detected with 532.25 nm wavelength single longitudinal mode laser. Data simulation and analysis show that the system is capable of measuring aerosol backscattering ratio profile of low-altitude troposphere (within 5～8 km) under conditions of laser energy of 300 mJ, 270 mm diameter telescope, and the on-line calibration can improve the accuracy of wind measurement.

An approach is presented to detect and compensate position variation, which adopts complemented fringe projection technique. It can effectively solve the problem of measurement error aroused by inexact positioning in the in-line inspection. Firstly, complemented fringe relative to referenced sample are generated and projected onto its surface. Then the fringe pattern images are captured. Secondly, fringe analysis techniques are adopted to acquire the phase when referenced sample is perfect positioned; the same way is employed onto the product which is inaccurate positioning. The phase of non-distortion and overlap area are chosen to compute difference caused by the inexactly positioning. This phase differences are added to the absolute phase for referenced sample to obtain a new absolute phase after positioning error, 3D coordinate of actual product are acquired using phase and depth mapping relation. At last, position variations are computed by least squares overlap iteration, and the rigid transform is employed to compensate error. Simulation analysis and experimental results prove the validity and feasibility of the approach.

A dynamic and adaptable method for choosing the time window and step size is given, based on the split-step Fourier method for solving the nonlinear Schrdinger equation. In this method, the time window is adjusted based on the diffusion of input pulse, and the step size is controlled by using a measure of the local error. This method has a high accuracy, which is most efficient for the improvement of calculation efficiency. How to choose positive and negative Fourier transformation forms during the calculation process is discussed, and how to get the approximate continuum waves in the time and frequency domain from the discrete results is analyzed. Supercontinuum generation in a high-nonlinearity photonic crystal fiber is investigated numerically, which validates the correctness of the calculation method.

The surfaces of X70 pipeline steel welded joints are strengthened with laser shock wave. The test of impact toughness at low temperature is carried out. The available grain sizes of the structures by laser shock processing are analyzed, and its fracture morphologies are observed with scanning electron microscope (SEM). The affecting mechanism of laser shock processing on impact toughness of X70 pipeline steel welded joints is investigated. The experimental results show that uniform refined ferrite grains are obtained in the surface of X70 pipeline steel welded joints by laser shock processing, which has excellent impact toughness. The fractures of X70 pipeline steel welded joints in primitive state exhibit embrittlement characteristics, while those after laser shock processing exhibit strengthening characteristics. The impact properties of X70 pipeline steel welded joints at low temperature are improved by laser shock processing, which is beneficial to increasing the usage security of pipeline steel transmission.

The stability of output energy is an important parameter for ultra-short laser facility. To improve the energy stability of the front amplifier in SILEX-I ultra-short laser facility, the energy fluctuation of regenerative amplifier and pre-amplifier and their pump laser are measured by experiment. It reveals that the fluctuation of the pump energy has great influence on the stability of regenerative amplifier. It is the main cause of the energy fluctuation of the front amplifier. To solve this problem, the fluctuation of the main laser caused by the unstable pump laser is simulated based on Frantz-Nodvik equation and statistical method. Ways of improving the stability have been analyzed such as delaying the output, saturated amplification, and using multiple pump lasers. Stabilization is achieved by adopting an amplitude stabilizer. The root mean square (RMS) of energy output is lowered from about 4% to below 1%.

A double gratings displacement measurement system with the resolution of nanometer order is analyzed using optics theory. A mathematic model of the double gratings displacement measurement is established. The characteristics of laser Moiré signals is studied by numerical simulation of Moiré signals. To improve position detection signal sensitivity and positioning accuracy, two methods of precision positioning are brought forward: differential Moiré positioning method and modified Moiré positioning method. The positioning accuracy of the system using differential Moiré technique is better than that of the system using modified Moiré positioning technique. It is because that in-phase noise in the Moiré signals are cancelled and S/N ratio is improved. But modified Moiré positioning system is simple in construction because of only using one grating pair. The compound control system for precision positioning is set up using two kinds of the Moiré alignment technique, in which the modified Moiré alignment technique is used as the coarse alignment and the differential Moiré alignment technique is used as the fine alignment. By using the two-step alignment, the high alignment accuracy and quick alignment speed are obtained in large positioning range. The experimental result shows the two-step alignment can perform positioning accuracy of ±10 nm in ±500 μm positioning range.

Locking to the laser cavity length of ultra-stable cavities is an important method to gain ultra-short line width laser output. The stability of the laser relies on the length stability of the Fabry-Perot (F-P) cavities. Vibration induced cavity deformation is one of the dominate factors that affect the stability of ultra-stable optical cavities. The elastic deformation of two general cavities with different mounting configurations in vibration environment is quantitatively analyzed. Numerical results offer the optimum mounting configurations of the two cavities, where the change of vibration-induced cavity is minimized to 10-12 m

Channeling atoms can be used to produce deposited nano-structure of high quality in laser-focused atomic deposition which is one of the technologies of laser manipulating atoms. We deduce the analytic solutions of atom equation of motion in the second approximation of Gauss function form. Through calculation simulation and analytic comparison, it is shown that there are many advantages in laser-focused atomic deposition when channeling atoms are used. These advantages demonstrate that atoms channeling is the content of complement in technology of laser-focused atomic deposition.

According to the analysis of stray light in high power solid-state laser system, ghost image is 3D demonstrated in the structure model of the facility by ghost-analysis (GA) software. The simulation model to describe ghost-image distribution is also established. The position of the one-or-more-order ghost image in the facility can be fully displayed in all directions so that the ghost-image harm can be avoided. This paper takes some of the “dangerous surfaces” as example,simulating the energy distribution on it by tracing numerous real rays. According to the shape of ghost energy and its corresponding optical stucture, suggestions are made to effectively mitigate the damage on the srudied optical surfaces. This analytical result is in good accordance with that in practice. It is proven that such an analytical method has provided a detailed reference for mitigation of ghost-caused damage.

By using the method of combining photo-thermal/photoelectric array, a measuring system of near infrared high energy laser beam and time-space distribution of the spot is developed. The system can be used for laser beam parameter measurement of the wavelength range of 0.9～1.7 μm and the power density range of W/cm2～kW/cm2 with the characteristic of large detection area of spot and small measurement uncertainty. The result shows that the system has the effective sensitive area of 22 cm×22 cm, and the spatial resolution of 1.1 cm. The energy measurement uncertainty is less than 10%, and the power density measurement uncertainty is less than 15%. This method is an available approach for parameter measurement of near-infrared laser beam.

In the thermal fatigue test of cylinder head, the shaped laser beam is chosen as the heating source to simulate the real fatigue. In order to make the experimental and simulated results agree with each other, the model parameters need to be verified. According to the surface structure, different laser loading experiments are proposed to measure the temperature on the cylinder head. The finite element model is set up and the parameters like density, specific heat, thermal conductivity, absorptivity, need to be adjusted until the experimental results are coincident with the simulated one and the error between them is the same as the experimental error. These results build the simulation foundation for the next thermal fatigue test. References for the selection and optimization of the model parameters of other partials in thermal fatigue test are also provided.

The temperature characteristic of basic substances in ring laser gyro (RLG) can generate bias drift, and the long time continued manipulation of RLG increases the bias drift which will deteriorate the performance of gyroscope dramatically. Then the method for temperature compensation is investigated, and the compensating model is gained by effects with different models. The relationship between mechanically dithered RLG′s bias and multi-temperature is studied too. Based on the influence of different experimental temperature models, two temperature sensors can be simplified for the redundancies. Thus the experiment of data subsection is designed to validate the practicability of this temperature model. The result shows that multi-temperature compensation models are better than single-temperature models; the simplified multi-temperature model can reduce the computing scale, and still satisfies the requirement of real-time compensation; by using this simplified model, the compensation precision can be improved by 1.6 times at least, and the bias stability compensated are all on 10-3(°) /h level.

A new type of the double-vortex beam is generated by the coaxial superposition of vortex beams with two different topological charges, whose intensity distribution is double-ring. The propagation characteristics of this kind of beams theoretically and experimentally are studied. It is found that each ring of the double-vortex beam carries different orbital angular momentum, and is propagating independently. In addition, when the internal topological charge of the double-vortex beam remain unchanged, the distance between the two rings of the double-vortex beam gets bigger with increasing the external topological charge.

The target characteristic research of micro-laser plasma thruster (μLPT) is introduced, and propulsion performance of different target structures and doped concentrations is discussed. Results indicate that there can be an optimum impulse coupling coefficient for the confined target. The thinner the target is, the bigger the optimum impulse coupling coefficient is, the lower the laser energy is, and the higher the specific impulse is. The absorption of laser energy can be intensified by the doped carbon, ablation efficiency can be enhanced, and there might be still other energy dissipation enhanced, and that can result in the decrease of impulse coupling coefficient.

Backscattering coupling effect in square ring resonator is studied. Vector method has been proposed to analyze the optical path variation induced by reflectors′ displacement in square ring resonator. A mathematic model of backscattering coupling analysis has been established. This model can be applied to analyze backscattering coupling effect in any form of ring resonators. Backscattering coupling coefficient r as a function of mirror′s axial displacements has been obtained. The absolute value of r has a period of two wave lengths in optical path length. It shows that the initial machining error of the resonator has a great effect on backscattering coupling effect. It is important for the research on the backscattering coupling effect in ring resonator.