The scattering of electromagnetic radiation from free electrons is called as Thomson scattering. It is a powerful diagnostic to measure plasma electron temperature and density without perturbing the plasma. Considering the scattering cross section for a single electron is quite small, 90° scattering configuration should be chosen to maximize the differential scattering cross section. Then a Q-switched laser is utilized to produce high power linearly-polarized incident light , so that a strong signal and a high signal-to-noise ratio are obtained. This article introduces the theory and experimental techniques of laser Thomson scattering and its application on high temperature plasma diagnostics to measure the HL-2A electron temperature and density. Main components of the HL-2A Thomson scattering diagnostic system are also introduced. The experimental results of plasma electron temperature and density during ECRH phase are given.

In this paper, we report a laser diode-end-pumped Nd:YVO4 laser, doubly Q-switched by an acousto-optic (AO) Q-switch and a Cr4+YAG saturable absorber. At the pump power of 6.1 W and the pulse repetition rate of 125 kHz, the shortest pulse width of 7 ns is achieved. When the Cr4+:YAG saturable absorber is removed from the resonator, the corresponding pulse width is 13 ns. In contrast to an AO Q-switched laser, it is shown that the pulse width is obviously compressed in a doubly Q-switched laser with AO and Cr4+YAG.

1319 nm waveband sets in the window of air transparency and the low lossness of fiber, and it approaches to zero dispersion. It has been widely used in many fields, and has attracted much attention. The transition radiation energy level of the 1319 nm is analyzed. The critical technology of restraining resonance of 1064 nm so as to improve that of 1319 nm is discussed. A pulsed output static energy of 340.9 mJ at 1319 nm, Q-switched output energy of 76.8 mJ with pulsed-width of 17 ns and divergence of 2.7 mrad are acquired. Experimental results show that coating chosen-film can be used to generate the laser at 1319 nm.

Laser diode (LD) end-pumped, thermally bonded Nd:YAG/Cr4+YAG passively Q-switched laser is theoretically analysed and experimentally studied. The key laser parameters such as repetition rates, pulse width, peak power, pulse energy and mutual relation are investigated. The high peak power of 6.25 kW, pulse energy of 50 μJ, pulse width of 8 ns, repetition rate of 200 kHz laser are obtained. Experiment shows that thermally bonded solid state laser has high repetition rate, short pulse widh and high peak power.

High repetition rate and large energy passively Q-switched Nd:YAG laser side-pumped by continous-wave (CW) laser diode is reported by using Cr4+YAG crystal as saturable absorbers. Regarding operation material as thermal thick lens, the laser beam parameters of plane-plane cavity, plano-concave cavity and plano-convex cavity are calculated according to the ABCD matrix theory of resonators. By comparing the fundamental mode volume, plano-convex cavity is selected. A high repetition rate and large energy passively Q-switched laser beam is obtained, and the TEM00 mode is achieved. A single pulse energy of 2.46 mJ, peak power of 24.36 kW, repetition rate of 4.22 kHz, pulse width of 101 ns are obtained at a pump power of 136.20 W, the amplitude fluctuation and frequency fluctuation are about 5%, the corresponding M2 factor is about 1.3, and the beam divergence angle of far-field is less than 1.5 mrad.

A method of inhibiting the flow boiling instability in microchannel with the hydrodynamic cavitation effect was promoted and it was proved by experiment as well. According to experimental results, cavitation structure at the entrance of microchannel benefits to the stability of flow boiling with great range of heating input. Based on this result, a microchannel phase change heat sink with single bar by using of the hydrodynamic cavitation effect was developed, and its thermal parameters, electric-optical parameters and maximum heat dissipation potential were also tested. According to the experimental data, when the output power was about 70 W, the photoelectric efficiency achieved the maximum value, and the largest heat dissipation capacity of the heat sink exceeded 100 W whose heat flux density was 870 W/cm2.

Lasers transverse modes are often selected by the Fresnel number of the resonators. However, the Fresnel number of the thickness direction and width direction is very different in slab lasers, so lasers transverse modes of the thickness direction and width direction can not be selected only by the length of the resonators at the same time. The output coupling mirror with one-dimensional variable reflectivity is used in the stable/unstable resonators. The structure can select the low transverse modes of the thickness direction and width direction at the same time. In this paper, the losses of different resonators have been calculated. The theoretical analysis has been verified by the results of the preliminary experiments.

Active-active mode-locking laser is very strict to its cavity length, and any small changes may result in mode-locking failure. The usual way to adjust the cavity length easily leads to cavity mirror mismatch. In this paper, precision cavity length adjustment is studied and a new way to adjust the cavity length is reported, which doesn′t easily result in cavity mirror mismatch. The precision of cavity length adjustment and the effect to the laser pulse width are also studied. Moreover, it is used in active-active mode-locking laser and good result is obtained.

A small-size, high-efficiency, liquid-cooled, electro-optic Q-switched laser is obtained, by using the expanded beam lens group with rational designed resonator parameters. The electro-optical conversion efficiency of laser is 1.4% and the output energy of single pulse is greater than 100 mJ. The cavity length is 250 mm with the laser pulse width of 10～15 ns. The beam divergence angle is 1.6 mrad when the laser works on 5 Hz, while 1.8 mrad working on 20 Hz. The output laser beam diameter is 5 mm and the energy fluctuation is less than 5%.

A high efficiency 1574 nm eye-safe minitype laser without water or air cooled is reported. It is 30 mm×125 mm in size. An oval lamp-pumped with elliptical cavity was developed, and a rotationally symmetrical heat radiation structure without water or air cooled was designed. The uniformity conduction-cooled of the laser and optic parametric oscillator(OPO) crystal was achieved. By using xenon flash lamp pumped, Cr4+YAG Q-switched Nd:YAG cavity as the pump source, a KTP crystal optical parametric oscillator ( KTP-OPO) system lasing at 1574 nm wavelength was realized. In the experiment, the highest signal output of 21 mJ at 10 Hz within ten pulses was obtained, and the pulse width was about 7 ns, the beam divergent angle less than 6 mrad. The optic-optic conversion efficiency from 1064 to 1574 nm was 30% approximately and the energy stability was better than 5%.

Stress in the media is one factor which limits the performance of high-power solid-state lasers. The piezooptic tensor of reduced-suffix matrix form in laboratory coordinate system was revised, and the depolarization loss induced by assembly-stress was analyzed under plane-strain approximation. The results indicate that great stress will induce unignored depolarization loss. Especially the depolarization induced by shear stress cannot be reduced by controlling the angle between the crystalline [101] axis and the x axis of the laboratory coordinate. When assembling the slab and heat-sink, it is necessary to reduce the assembly-stress, especially the shear stress.

Lasing experiment of inorganic liquid system pumped with laser diode under flowing status is carried out, high repeat frequency laser pulse output is achieved in long time, the maximum single laser pulse energy is 5 mJ and the maximum pumping frequency is 400 Hz. The laser pulse energy is simulated according to the experiment parameters, and the influence of pumping frequency, flowing parameter and environment humidity to the laser output capability are analyzed initially. The experiment results show that the inorganic liquid laser system pumped with laser diode can avoid heat deposition effectively under flowing status and obtain high repeat frequency laser pulse output in long time; the flowing parameter and environment humidity possess very important influence to the laser output, it is very necessary to design the conduit structure excellently and control the environment humidity.

The potential application of 2 μm laser is introduced. A 793 nm fiber-coupled laser diode is used to end pump TmYAP laser. A high efficient and 1990 nm laser at room temperature is obtained. 933 mW output power is attained at 1990 nm when pumping power is 4.5 W. The optical-to-optical efficiency is 27%, and the slope efficiency is 37%. The influencing factors of the laser output are also analysed, such as the curve radius of output mirror, the output transmission and the length of the laser resonator.

Laser diode (LD) pumped Nd:YAG laser is widely used in precise manufacture. A kind of simplified LD side pumped acousto-optic Q-switched Nd:YAG laser used for Al2O3 ceramic wafer micro drilling is described. The taper of the hole in Al2O3 ceramic wafer is reduced effectively when the laser beam quality is optimized by modifying the resonator structure. The TEM00-mode output power is above 20 W and the pulse width is about 200 ns when the laser is working at 10 kHz. And the M2 factor of the beam is lower than 1.5 in each direction.

A red laser at 670.7 nm is obtained with high-power continuous-wave laser diode array (LDA) off-axis stagger side-pumped Nd:YAP laser crystal and type-I critical phase matching of LBO crystal. The prefect matching of gain field inside the crystal and fundamental mode of cavity can be made by this structure, then high beam quality, high power output can be easily obtained. By using a short folded-cavity resonator, the thermal focal length of Nd:YAP crystal is measured, and the parameters of laser cavity are selected by computer optimum design. With incident pump power of 800 W for the Nd:YAP crystal, the red laser output of 8.3 W at 670.7 nm is obtained, the beam quality M2 value equals 5.6 in both horizontal and vertical directions at the maximum output power, and the power stability is better than 3% at the maximum output power during 30 min. The experimental results show that the intracavity frequency-doubled by the pump structure is an effective method for high power red laser.

Keeping the heat flux and the temperature of water inlet constant, three full cone nozzles are applied to study the temperature uniformity of spray cooling in non-boiling regime. The influences of nozzle geometry characteristics, spray distance and inlet pressure are studied respectively. The results show that the standard deviation of the surface temperature is affected by nozzle diameter, spray distance and inlet pressure, while the nozzle cone angle has no significant impact on the temperature uniformity.

We present a multiwavelength mode-locked fiber ring laser incorporating two semiconductor optical amplifiers (SOAs) and a fiber Mach-Zehnder interferometer (MZI). One SOA is modulated by an injected external optical signal act as loss modulator, another SOA is not modulated by injected signal but services as cavity gain medium, and a fiber MZI functions as a tunable comb filter. Twelve synchronized wavelength channels with each channel of mode-locked at 10 Gb/s and pulse width of about 30 ps are achieved from the presented multiwavelength laser source. Oscillation wavelengths can be smoothly tuned by adjusting temperature of fiber MZI. Also, by adjusting the current of the SOA, oscillation wavelengths can be freely tuned in a large wavelength range. The output power is rather stable. This fiber laser has potential applications in longer waveband (L-band) within the low-attenuation window.

A computational fluid dynamics (CFD) method for semiconductor laser external heat dissipation numerical simulation is introduced. For fluid-solid coupled heat transfer problems, convection-conduction coupled heat transfer model and mass conservation, energy conservation, momentum conversation, k-ε equation governing equations are established; precise numerical solution can be acquired by iterative calculation according to specified boundary conditions. The forced air cooling design for a semiconductor laser (15 W maximum heat load) with external heat dissipation, which consists of an aluminum alloy heat sink and an axial fan, is simulated with CFD method; the result of numerical simulation indicates that the design is applicable for the thermal requirements of the system.

A theoretical model on the intra-cavity adaptive optic (ICAO) system is proposed. The method of numerical simulation is used to prove its possibility in the high power solid-state lasers. The study on a heat capacity laser with larger intra-cavity aberrations and kilo-watt output shows that the ICAO system improves the beam quality significantly. Therefore, the ICAO configuration and the control process are checked theoretically. Physically there are complicated non-linear couplings among ICAO and other physics processes inside the resonator. The simulations show that the ICAO system is sensitive to certain errors due to these couplings. Therefore, a subtle match among number of the sub-piles of the wavefront sensor, unit distribution of the deformable mirror and order of the aberrations expected to be compensated is required.

Detectors will be saturated when exposed to intense light. There is certain dependence among saturated area, light intensity and saturation threshold. The energy distribution of far-field spot is described with Airy function, due to the constraint of pupil. Saturated area formula has been obtained by the study of the envelope of Airy function. Exposed to a beam of intense light, the saturated area is proportional to the 2/3-th power of light intensity and inversely proportional to the 2/3-th power of saturation threshold. The formula is verified by irradiation experiment. The result has certain significance in saturation estimation and laser blinding.

Detect guided optical fiber′s some imperfections which are produced in the winding process with X-ray. Through the analysis of traditional X-ray image and the simulation of point X-ray scanning, the feasibility of optical fiber imperfection scanned by X-ray is confirmed theoretically, and propose that through the two-dimensional scanning of flaw to locate it, then the influence of suitable winding gap is analyzed. Finally the relevant experimental results are given, the relevant issues of the experiments are analyzed.

The detection ability of high resolution photoelectric detection system, to a great extent, is limited by the stray light. Since various factors influence stray light of optical system, its stray light must be tested in order to control the final indicators, such as point source transmittance (PST). On the base of star-simulator with huge dynamic range, the stray light test facility is designed, and the problem that dynamic range of single detector cannot cover 108 is solved. Under a reasonable signal-to-noise ratio, the test range of stray light PST with electron-multiplying CCD (EMCCD) is analyzed. Through analysis, the range of the stray light PST can reach 10-2～10-8, and meet the requirement for testing high resolution photoelectric detection system's PST.

3D laser scanning radar is one of the most effective sensors in landing guidance, navigation and control. The study of key technologies of lidar are valuable in science and application. A fast 2D scan system is important for 3D lidar. A scheme is proposed for designing the driving and controlling circuit for the scan system by mixing analog and digital method. Based on virtual instrument technology, A test and calibrate system of motor is designed by adopting NI data acquisition (DAQ) board. Through this test system, the non-linear and dynamic performance of scan system is measured. Experimental results show that this scan system can meet the requirement of 3D lidar.

The aerodynamic effect or the explosive and shock effect on spinel and sapphire domes of the mid-infrared (mid-IR) imaging missiles are studied. Based on the aerodynamic simulation analysis and the arc wind tunnel experimental results, a protective diamond coating applied to a spinel dome to realize the athermalization design is carried out. To suffer great impact, exciding and spreading experiments testify that a transited structure layer buffer added between the spinel dome and the metal shell could weaken the conducting stress along the shell greatly. The results show that applying spinel instead of sapphire to make domes is feasible under different technique requirements.

The microsatellite has many advantages, such as shorter development cycle, higher mobility and lower cost than those of conventional satellites. It becomes a hot area of the remote sensing. The developing CCD camera is one of the most important payloads of the microsatellite and it has 0.98/0.5 year reliability rate at a low cost. The optical system adopts catadioptric structure with wide working temperature range and uses spherical-surfaces components which are fabricated and assembled easily. Stray light reduction and environmental adaptation design can further improve imaging capability of the system. The electric circuit system applies many new technologies such as frame transfer CCD, field programmable gate array (FPGA), correlated double sampling (CDS), low-voltage differential transferring (LVDS) and buck/boost voltage conversion, so the system has low cost, low power consumption and good stability. The commercial-off-the-sheft (COTS) components are screened by destructive physical analysis (DPA), additional screening, boarding tests and so on. The reasonable reliability methods are used in the developing process of the CCD camera. The CCD camera maintains good imaging performance in the environmental tests, calibration experiment and imaging capability tests.

In order to obtain higher responsivity and spatial resolution under poor illumination condition, interline transfer CCD camera can be designed to work in time delay and integration (TDI) mode similar to TDI CCD. Whereas it is found that outputs of some pixels are obviously lower than others′ as interline transfer CCD camera works in TDI mode in laboratory radiometric calibration experiments. In result, photo response non-uniformity(PRNU) and signal noise ratio(SNR) of the system become worse. An improved radiometric calibration method of interline transfer CCD camera based on TDI working mode is put forward. In this method, TDI stage is taken into account in PRNU and SNR algorithms and system performance is improved remarkably with few influences on use. Results of validation experiments prove that the improved radiometric calibration method can efficiently improve SNR and lower PRNU of the system. In addition, characteristic of the system can be reflected better with the improved radiometric calibration method. As working in 32 TDI stages, PRUN is reduced from 4.88% to 0.86% and SNR is improved about 2.9%.

When the irradiation light intensity is low, the gray value distribution of CCD camera output image represents power density distribution. Using the gray value distribution and the corresponding laser power, we calculated the laser power density on the centre pixel of laser facula area. Because laser power density is proportional to laser power, we got a series of power density value on the centre pixel of laser facula from the laser power measured in experiment. The corresponding pixel output voltage value was measured throgh oscillograph. And then we got the photoelectric response curve of CCD to 1064 nm laser. From the gray value and laser power density value, the approximate threshold value of laser intensity inducing CCD camera system saturation was 0.11 mW/cm2. And from the photoelectric response curve of CCD, the value causing CCD chip saturation was 0.20 mW/cm2.

In order to realize the detection of dark and weak target in space, the optical system of visible light detection camera with a large aperture is designed. Its effective focal length is 350 mm, F-number is 1/1.6, field of view is 3.2°, and working wavelength ranges from 450 to 950 nm. The structure of the visible light detection camera is described, and the structure form is determined to be Maksutov′s two reflection system whose primary and secondary mirrors are spherical. CODE-V optical design software was used to iptimize the optical system. The image quality evaluation and thermal analysis result are presented. The result shows that each field spot diagram is nearly circular, 80% energy encircled is within the spot diameter of 26 μm, maximum distortion is less than 0.05% and lateral color is less than 5 μm, which meet the requirement of detection.

Silicon photonics is a novel technique for high scale optic/electronic integration, with which most kinds of optical devices can be designed. Based on free carrier plasma dispersion, silicon Mach-Zehnder electro-optic modulator (MZM) can achieve high modulation speed over 10 GHz. For silicon MZM, one of the critical techniques is how to effectively change the free carrier concentration in order to obtain the needed modification of the optical refractive index. Considering the need for modulation speed and power consumption, a kind of silicon MZM based on metal-oxide-semiconductor(MOS) capacitor electrodes is studied by a simulation method combining electric and optic analytic mode. The results show that under the driving voltage of -1.5 V, when the doping concentration is 1015 cm-3, the effective refractive index change of the optical waveguide in silicon MZM is about 3.82×10-6, which result in the Vπ length of 13.5 cm and the loss of less than 0.04 dB/cm. When doping concentration is 1018 cm-3, the effective refractive index change can reach 6.96×10-5, which result in the Vπ length of 0.7 cm and the loss of about 24.8 dB/cm. Varied capacitor electrode structures of silicon MZM may make the visible difference of the modulation performance, and its effective refractive index change may reach 1.53×10-5, which result in the Vπ length of 3.3 cm and the loss of about 0.09 dB/cm.

The properties of Modified Laguerre-Gaussian beams (MLGBs) propagating through a fractional Fourier transform (FRFT) optical system are investigated. The analytical transformation formula for MLGBs propagation through an FRFT optical system is derived based on definition of the FRFT in the cylindrical coordinate system. By using the derived formula, the normalized intensity distribution of MLGBs in the FRFT plane is graphically illustrated with numerical examples, and the influence of different parameters on the normalized intensity distribution is discussed.

In this paper, the wavefront properties of large aperture optics such as neodymium glass, reflecting mirrors and crystals have been systematically studied. Static and dynamic wavefront aberration of multi-beams laser system have been statistically analyzed. The results show that one kind of optics have similar wavefront properties, and different laser beams also have similar characteristics on static wavefront aberration. The chief static aberration of main amplifier is astigmatism with the PV value about 2λ～3λ (λ=1053 nm), and in 90° rotation reversal multi-pass amplifier laser system, the chief dynamic aberration of main amplifier is defocus with the PV value about 4λ～5λ. After excluding defocus, the dynamic wavefront aberration PV value is about 1λ～2λ, and maximum aberration of the whole laser system is likely to exceed 6λ.

In order to improve the accuracy of an off-axis reflected space optical system, researches have been made to its distortion feature. In the research, some distortion features different from the radial distortion model are found. So the previous solutions are no longer suitable for this problem. A method using two-dimension Lagrange interpolation is introduced to correct the distortion of the off-axis system. As the system is still in design, these methods are verified and analyzed by simulating in computer. The results show that by using this method, the distortion of the off-axis system can be well corrected.

Laser synthesis aims at synthesising a number of discrete laser beams into a coaxial beam to achieve higher output power which is several times of that of a single laser to achieve the higher output power. A novel hollow beam convertor is designed, which can be used in N (N≥3) way coaxial laser beam synthesis, and the numerical calculation and experimental study are done. Using this technology in the three-beam synthesis, laser synthesis efficiency is 89%, the time jitter is no more than 2 ns, laser pulse-width reaches about 10 ns (FWHM), and laser beam divergence angle is no more than 2 mrad.

In angular multiplexing excimer laser system, studies on energy amplification of a train of laser pulses are crucial to determine beam number for reducing optical complexity, while strict requirements on alignment are needed for experiments. Based on principles of displacement and angular drift adjusted by near field and far field respectively, an optical automatic alignment system is designed, and corresponding computer software for closed-loop feedback controll is compiled. High adjustment accuracy with allignment errors of 21 μm in near field and 1.3″ in far field is obtained by using He-Ne laser. This system is applied to two pulse amplification experiment and works effctively.

By Fraunhofer diffration theory and numerical analysis method, the relation of beam separation distance, fill factor, phase change and far-field intensity distribution of laser coherent combination is calculated. The influences of transformation characteristic of phase and polarization on intensity distribution of coherent combination are studied by heterodyne method and liquid phase modulator. The characteristics of phase change for beam in fiber transmission is obtained. As a result of the random change of phase, the intensity of laser combination is reduced and the excursion of background comes forth. The contrast of fringes can be changed with the transformation of polarization. In vibrant and temperature changed environment, the frequency for phase change in beam is higher than that in natural environment.

A novel three-dimensional (3D) imaging method based on orthogonal-stacked lenticular sheets and computer holography is proposed. Elemental image array (EIA) of 3D object propagated through the orthogonal-stacked lenticular sheets (OLS) are captured by a CCD camera. Sub-image array (SIA) used for generating the Fourier hologram of 3D object is obtained by recombination operation of the EIA. A complex value point in the hologram plane is determined by the two-dimensional (2D) integral operation after the corresponding sub-image is multiplied by an inclination phase factor. Numerical reconstruction of the calculated Fourier hologram at different distances based on Fresnel diffraction shows that the method is feasible for 3D imaging.

A combined method based on improved principal component analysis(PCA) and integer wavelet transform is proposed for hyperspectral image compression. PCA can effectively reduce the spectral correlation of hyperspectral image and integer wavelet transform by using lift scheme is widely used for spatial decorrelation. The code speed dramatically decreases when the spatial size becomes large. The hyperspectral images are partitioned into several blocks with same size and each block is encoded by PCA and integer wavelet transform independently. A non-linear model is setup to estimate the optimal retained number of principal component(PC) at any compression ratio. When the optimized compression methods are using on the hyperspectral images of the AVIRIS instrument and our developing hyperspectral imager, the compression effects is competitive and it runs fast comparing with common PCA followed by integer wavelet transform. This method is also easily completed on the hardware.

There are rich edge and texture features in the remote sensing image. The common integer wavelet transform (IWT) can only reduce the image energy of horizontal and vertical edges or textures of high frequency subbands, while that of non-horizontal and vertical edges or textures are still high. For resolving the above problem, a new remote sensing image compression algorithm using adaptive directional lifting-based integer wavelet transform (ADL-IWT) and partial even optimal threshold (PEOT) is presented. The new algorithm can reduce the non-horizontal and vertical edge and texture energy of remote sensing image, by using ADL-IWT. Additionally, the new algorithm optimizes partial encoding quantization threshold intervals to improve the search efficiency of the significant coefficients on these threshold intervals. Experimental results based on the SPECK coding algorithm with ADL-IWT and PEOT show that the new algorithm can not only support both lossy and lossless compression of remote sensing image using a single bitstream, but also perform better in peak signal to noise ratio (PSNR) than the SPECK algorithm using the common IWT for lossy compression.

In terahertz (THz) scanning imaging system, the image resolution is constrained by the size of beam spot, while the image quality is greatly affected by the fluctuation of the laser output power. Considering the prior information, Bayesian rule is applied to improve the confidence of image processing based on Markov random field (MRF) and simulated annealing (SA) algorithm. An MRF model is applied to denoise the simulated THz scanning image. Simulations are carried out to study the effect on the denoising result from the parameters such as Gaussian noise, cooling times, and inner iterative times. The effect of the denoising method is evaluated by observing the signal to noise ratio (SNR) and the root mean square error (RMSE). The relationships among cooling times, inner iterative times, SNR and RMSE are obtained. The simulation results show that the MRF method can effectively suppress the Gaussian noise while preserving the image details as well.

Imaging synthesis plays an important role in the defects testing of large aperture optics. To make sure the successful synthesis of sub-apertures, the template matching is used for sub-aperture stitching, by analyzing all kinds of stitching method and combining the needs of defects testing of large aperture optics. Template matching gets great success in the experiment of defects testing of large aperture optic, so it is useful for detecting surface defects of large aperture optics accurately, efficiently and automatically.

Micro-relief lines were formed on the surface of 45# steel by photonic crystal fiber femtosecond laser with a repetition rate of 50 MHz and 1 MHz respectively. The heights and the widths of the micro-relief lines were affected by the input laser power, the laser scanning velocity and the pulse repetition rate. The specific structure of the micro-relief can be controlled by properly adjusting these parameters. The mechanism for the formation of the micro-relief was also analyzed preliminarily. The heat accumulation of the high repetition rate femtosecond laser induces the surface melting of the 45# steel, which results in the micro-relief structures by the combination of the liquid surface-tension and the temperature gradient.

Taking example for alumina ceramic, this paper briefly introduces the mechanism of CO2 laser-controlled thermal stress cutting of brittle materials. In order to study the distributions of temperature field and thermal stress field, a three-dimensional axial symmetric model of alumina ceramic is established by using APDL programming language of Ansys software. The normal stress σy of nodes which are in the laser scanning path, is in the process of "no stress-tensile stress-compressive stress-tensile stress-no stress" during cutting process, until the crack grows. The study reveals that laser power and the maximum temperature is directly proportional during the cutting process. While the laser power increases, the crack initiates earlier and the microcrack of the fracture surface becomes bigger with greater tensile stress. The results are proved by comparative experiments.

Due to the many factors affecting the quality of the laser welding, though there are a lot of process parameters researches on the laser welding, the effective means of the optimization of the process parameters is deficient. Taguchi approach is used as statistical design of experiment(DOE) technique for optimizing the laser welding parameters in this paper. The experiments for laser welding common 304 stainless steel with the Taguchi method is designed. The experiments result is analyzed by signal to noise ratio and ANOVA using the softwares of Minitab14 and Design-expert7. The effects of the parameters of the Nd:YAG pulsed laser on the weld width and the tensile are studied. The mathematical models which can predicted the weld quality(the weld width and the tensile) and optimize the process parameters are developed. As a result, the influences of pulse width and voltage on the weld width are greater than frequence and speed, and the speed and the pulse width play a major role on the tensile, which shows that the mathematical models developed by softwares can predicted the results very well.

Since the difference between accuracy of modeling software, the conversions from surface to solid often fail in model reconstruction. Therefore, the replacement of the solid modeling by grid model can simplify process of surface models and obtain high efficiency in some applications. So high-quality triangular grid model is crucial in the reconstruction. However, the shape of the current grid model of points is not well controlled and lacks detailed characterization. Therefore a normal vector filter criteria on the basis of body algorithm is present in this paper. The experiment proves that improved algorithm greatly enhances the precision of space point cloud mesh. That method guarantees that final triangular mesh has the same topology as the prototype, which can be well used for laser remanufacture to guide the robot processing.

The Fe40NiCrSiAl alloy in different treatments is strengthened by laser shock processing, and the hardness, elastic modulus, friction of coefficient and wear behavior are tested and analyzed. The results indicate that, Fe40NiCrSiAl alloy is in rolling, which has been treated by laser shock processing, the hardness of the strengthened zone increases by 25.22%, the elastic modulus enhances by 7.17%, friction of coefficient reduces by 13%, and the wear behavior is mainly delamination wear. Fe40NiCrSiAl alloy is in rolling, which has been treated by laser shock processing plus annealing, the hardness of the strengthened zone reduces by 7.59%, the elastic modulus reduces by 6.25%, the friction of coefficient reduces by 13% too, and the wear behavior is mainly abrasive wear. Fe40NiCrSiAl alloy is rolling, which has been treated by annealed, the hardness reduces by 21.65%, the elastic modulus reduces by 28.58%, the friction of coefficient is almost unchanged, and the wear behavior is mainly abrasive wear.

Highly ordered porous anodic alumina(PAA) films are fabricated with the sulfuric and oxalic acid as electrolyte and by the two-step anodization method. The crystal structure of aluminum foil before and after annealing process is examined with X-ray diffraction(XRD). Field-emission scanning electron microscope(FE-SEM) and atom force microscope(AFM) are used to observe the surface and cross morphology of PAA films. The pore diameters(20～100 nm), pore distances (50～150 nm), depths(0.2～70 μm) and densities 109～1012 /cm2 can be well controlled. The forming process and mechanism of PAA film are discussed. The effects of aluminium pre-treatments, the electrolytes type, anodizing voltages and electrolyte concentrations on PAA film′s stractures are analyzed.

Epitaxial growth of As-doped HgCdTe is essential of HOT infrared (IR) detector and helpful to suppress dark currents at high temperature. Segregation coefficients for incorporating As employing Te-rich liquid phase epitaxy (LPE) are very low, thus concentration of As in the HgCdTe film grown by LPE is very low (about 1015 cm-3). Though a portion of the total As do not appear to be activated as acceptors, As is fully activated as an acceptor(AsTe) under Hg-saturated conditions. As-doped HgCdTe films are obtained by Te-rich LPE, and after annealing at 400 ℃ in Hg-rich ambient, and P-type HgCdTe films are obtained. The concentration of As is determined by secondary ion mass spectroscopy (SIMS). The Hall effect and resistivity are measured in the temperature range between 10 and 300 K. Electrical properties of As-doped HgCdTe film are reported.

Based on the major and difficult issues in the area of researching on photonic crystals, The partial differential equations of the monochrome electromagnetic wave transmitted in periodical dielectric medium and the theoretical basis for the laser holography to achieve photonic crystal templates are analyzed. With holographic grating theory, crystal lattice structure of the three-dimensional photonic crystals is designed. 632.8 nm red light crystal templates of the three-dimensional face-centered cubic photonic with double-beam three exposures methods are produced. The contrast ration, the rotation accuracy control and the index of refraction change influenceing the quality of photonic crystal templates end-product and how to solve are discussed. During the work process, double-beam three exposures methods are used to eliminate the modulation of recording beam polarized direction. At last, system of optical path and system performance during the work process of producing large area photonic crystal templates to eliminate the modulation of recording beam polarized direction are simplified and stabilized, seperately.

A fast nondestructive testing method using the normal terahertz time domain spectroscopy system (THz-TDSS) is presented and demonstrated in this paper. In the method a parallel THz wave with the beam size of 4 cm in diameter is used and an echelon is introduced in front of an object. The THz wave, passing through the echelon, is therefore delayed differently in one dimension. Then the THz wave takes the information in different positions of the object, which is corresponding to different delay times. Theoretical analysis indicates that the detected THz signal is sum of the information in different object positions and the information could be obtained from the compacted THz signal by deconvolution signal processing. In the experiment, top and bottom position of foil strip make signal having depression in the front and back respectively after deconvolution processing, and a number of foil strips corresponde to number of depressions. The different positions of foil strip with 4 mm width are detected successfully, and the number of foil strips is also distinguished clearly. A pushpin in diameter of 11 mm is tested twice and located by calculation. The experiments verfy that the theoretical prediction is correct and the fast non-destructive testing method is feasible. Beside the time saving, the other advantage of this method is simplicity in experiment because no any changes on the THz-TDSS is required.

As the laser induced breakdown spectroscopy (LIBS) method can rapid, real-time, measurement in situ, and analyzing heterogeneous element at the same time and has many other merits, making it a most promising tool in soil heavy metals analysis. A Nd:YAG based LIBS experimental set-up is developed. The soil LIBS spectral is experimental measured, the calibration lines and corresponding LIBS detection limits of six most important soil heavy metals are decided. Initial indications show that the LIBS is suitable for soil heavy metals pollution determination.

Tunable diode laser absorption spectroscopy (TDLAS) technique is a method to detect trace-gas qualitatively or quantificationally based on the scan characteristic of the diode laser used to obtain the absorption spectroscopy in the characteristic absorption region. The dissolved gas analysis (DGA) is essential for the insulation state assessment and the fault diagnosis of transformers. In order to monitor the fault gases CO2 and C2H2, a set of system of simultaneous online monitoring the concentrations of CO2 and C2H2 is designed, and this system makes use of TDLAS technique combined with multiple reflection pool, harmonic detection and time-division multiplexing optical switch technique. The system has benefits of high accuracy, selectivity, fast response and the nature of explosion-proof, which is suitable for power transformer fault gases on-line monitoring.

A double grating displacement measurement system with the resolution of nanometer order is analyzed theoretically. A mathematic model of the double grating displacement measurement is established. An ultra-precision positioning set based on laser Moiré signals is designed, which achieves high-accuracy position detection and full automatic precision plane alignment. In view of the existing non-linearity and the difficulty in establishing precision controlled model, fuzzy control method is used in the precision positioning control. The bach propagation(BP) neural network is used to set up a fuzzy neural network controller (FNNC) model. Driving signal is obtained by mapping Moiré signals′ intensities and their intensity rates. The improved fuzzy control system can obtain corresponding operation knowledge according to working environment. The experimental result shows that FNNC can perform excellent control effect such as good stability and strong robustness, and that the positioning speed and positioning accuracy can be effectively improved. The device based on fuzzy neural network can achieve positioning accuracy of ±0.4 μm.

Laser self-mixing interferometer has advantages of simple architecture, compact size, naturally self-aligned optical characteristics, and low cost. It can replace conventional interferometers to measure displacement, distance, velocity, vibration and other physical quentities. When it is used in the micro-electro-mechanical system (MEMS) dynamic measurement, a system with simple architecture and low cost can be developed, which is suitable for fast and accurate characterization measurement of vibrating micromachined devices. Based on the three-mirror cavity model, self-mixing interference measurement principle is discussed. The laser self-mixing interference MEMS dynamic measurement system is designed, and the key components are discussed detailedly. Experiments are studied when the target moves in different forms. The results prove that laser self-mixing can measure target’s different movement forms. The laser self-mixing interference measurement system can support MEMS dynamic measurement.

Optical thermometry is a research hotspot in current industrial combustion fields for flame monitoring and combustion diagnostics. A new temperature measurement method of optical double-color imaging based on grayscale inversion has been proposed. The functional block diagram of temperature measurement system has been given and the temperature measurement algorithm based on grayscale inversion has also been deduced. The analysis has demonstrated that, compared with the three-color thermometry, this thermometry has eliminated the negative effects of flame′s gray body hypothesis and non-ideal spectral responsive bandwidth, and overcome the drawbacks of nonlinear three-channel output and few energy share occupied by solar visible radiation. The research has shown that, this method has high temperature measurement accuracy, and can measure the 2D-temperature distribution of boiler flame. It can provide the good instruction for flame detection and combustion diagnosis, which will be widely used in future.

In experiment, it has been found that a possible failure in process of solving the fitting coefficients or sudden changes of measurement results can not be absolutely prevented in fitting interference wave surface with Zernike polynomials. The equivalence of the algorithm of least squares method and Gram-Schimdt is strictly proved. It is demonstrated that both two algorithms of solving Zernike polynomial coefficients have the same stability. The basic requirement to ensure the measuring reliability of interference optical detection system is found through a series of comprehensive and systematic experimental researches. The condition is that the order of Zernike polynomial to fit interference wave surface must be less than the number of interference fringes in the diaphragm, and it also has been proved in theory.

Laser transmitting wavefront is near diffraction-limited in space laser communication. Wavefront measurement is the basis of system adjustment and testing. Optical plate interferometer is a traditional valid method for wavefront sensing but it is invalid to meet the needs of measuring the wavefront of wave height less than 0.3 wavelength, aperture over 100 mm and laser diode coherence length short. Lateral double shearing laser interferometer is designed based on Maeh-Zehnder interferometer for the application. It includes two plane lens and four mirrors with one of which is vertically divided into two parts. The two parts turn around vertical line oppositely to be a small angle of several seconds between them. The wavefront aberration can be differentially analyzed from the fringes of the two parts and the accuracy is improved. The interferometer of 290 mm diameter suited for short-coherence laser is developed. Optical paths of the interference are equal length that is useful for laser diode etc. The wavefront of a tuning laser is measured by the interferometer. The experimental interferograms are analyzed with the software. The value of the wave height (PV) is 1.0 wavelength.

Composite material is normally affected by anomalies such as delaminations and disbandings. Pulsed thermography is a new non-destructive inspection technology, which has been widely used in aerospace. In this paper, the detectability of pulsed infrared thermography is studied by establishing the theory for the detect ability of carbon fiber reinforced plastics (CFRP). Meanwhile by utilizing the designed specimens buried with different depths, different sizes and different distances between adjacent flaws to represent disbonding and delamination in the CFRP composite material. The detectability of CFRP composites using pulsed infrared thermography is experimentally studied. The results of the experiment show that the designed defects in the CFRP with thickness of 0.5 mm and 1.0 mm are all detected. Meanwhile, the relationship between depth size and distance of adjacent flaws and detectability are analyzed. According to this study, it will provide some theoretical basis and experimental references for the inspection of the CFRP composites.

In the system of magnetic field measurement based on the polarization properties of fiber grating, the polarization dependent loss (PDL) is influenced by the structure of fiber grating. From the principle of the measurement system, the bandwidth and slope of transmission spectrum corresponding to the measurement range and sensitivity respectively which relate to the grating structure are analyzed. The measurement performance on uniform, phase shifted, and logarithm-triangle fiber gratings is simulated, which shows that the logarithm-triangle fiber grating can broaden the bandwidth of PDL peak values and improve the measurement responsibility. The experiment with logarithm-triangle fiber grating designed by the technology of reconstruction equivalent chirp is implemented, and the result provides reference for grating structure selected in the measurement system.

The pattern of thermal excitation is one of the main factors which affect the detection reliability in infrared thermal wave nondestructive testing. The experiment is designed to establish the basic principle for selecting pattern of thermal excitation. In experiment, glass fiber reinforced laminate which embeds artificial defects is a tested object, and four patterns of thermal excitation are organized as follows: pulsed flash lamp, boiling-water bath, oven thermostatic heating, and pulsed ultrasound. The thermal stimulus-response signal which is the intensity of infrared radiation of specimen surface is acquired and processed. The influence of four heating ways on the testing results is analyzed and contrasted from three respects: signal to noise ratio of thermal imaging, curves of infrared radiation intensity, and degree of defect′s detectable, and a basic principle for selecting pattern of thermal excitation for fiber-reinforced composites is gotten. In order to improve the detection reliability, this principle should be followed when selecting thermal excitation pattern.

The definition, measuring methods and principle of size-of-source effect (SSE), and also the measuring principle of radiation thermometer are introduced in this paper. The SSE results with direct and indirect method of RT9032 and LP4 are shown in this paper. The data of SSE got by indirect method is bigger than that of direct method in our measurement system. There are several aspects contributed to the difference of SSE, such as the reflections from the inner cone and edge of the aperture into the black spot, the radiance of the sphere reduced by black spot, and other aspects including the reflections between the front element of the thermometer and the black spot, optical misalignment radiation thermometers and so on. If SSE is measured by direct method employed the integrating sphere, the monitor is necessary to revise the drift of the radiation.

The principle and instrument for the measurement of atmospheric coherence are described and the results measured at Changsha are reported in this article. The impact of the atmospheric coherence length on the probability of "lucky image" is analyzed. The experimental data is coincide with the near-earth line turbulence strength, changes in atmospheric coherence length significantly affect the probability of "lucky image" , it is verified that the measurement method can provide certain reference significance of the parameter selection of lucky imaging.

In order to obtain the relationship between the white light interference color and the physical quantities of a sample such as the thickness, the standard computer representation of an interference color on a given optical path difference is studied. Based on the CIE1931XYZ color space, we use the known spectral power distribution of standard illuminant to calculate XYZ values of each point in Michelson interference field. The problem of the negative RGB values which convert from XYZ values is solated to realize the continuity of color display. The simulated white light equal-thickness and equal-inclination interferograms of an ideal wavefront are demonstrated. A real interference wavefront and a real lamp are used to obtain simulated white light interferograms. This method makes it easy to obtain the interference color distribution of an interference field on the condition that the spectral power distribution is known. It provides the basis for glass stress measurement, film thickness measurement, and other related field.

Optical mounts structure stability is crucial to beam position accuracy. The study on optical testing method for structure stability of mirror /lens mounts was involved and optical stability testing software was compiled. Structure stability of different kinds of mirror /lens mounts was measured. The variation of beam position drift versus time was experimentally obtained, and the comparison of stability properties among different kinds of mounts and different levels of adjustment were made. Stability test system was able to gives on accuracy of as high as 3.13 μm. A rapid and handy testing mean for stability of optical mounts was provided, and the results can be used as a key guide to optical mounts choice for high power excimer laser system.

Based on cablevision technology, a robot ending′s attitude measurement using VC++, Matlab and other tools is proposed. By the monocular or binocular stereo vision technology, the robot operating path image is acquired. According to the camera imaging principle, the camera and the image calibration is established. How to use the cablevision technology to get the space point coordinates is described in detail, and the spatial surface normal vector, which is the robot ending attitude, is determined. When the robot offline planning is making, towards the special posture requirements of the operational targets and the robots ending offline planning, the method can achieve a desired effect.

3D laser scanning technology is an active remote sensing technology with stable, fast and precise performance, and it can scan thousands of points to a point cloud of 3D data of the object and be operated at night. 3D laser scanning technology is used to make an inventory of warehouse, takes the horizontal bin of Beijing Qingyundian grain storage and the squat silo of Zhuozhou grain storage of China grain reserves corporation for examples, emphasizes the method of its application on this aspect, including the processing of situ measurement of 3D laser scanner, data processing and volume calculating. The results of the experiments show that the application of 3D laser scanning technology on surveying of grain volume has great practicality for its high accuracy and fast speed.

Properties of the endlessly single mode of photonic crystal fiber(PCF) are analyzed theoretically with the effective-index model. Numerical calculation shows that PCF can be single mode for any wavelength if the proportion of the diameter of the air holes to the pitch in the cladding is small enough. Structure parameters of a single-mode PCF for wavelength above 200 nm are calculated exactly, which provide us with theoretical instruction for the ultroviolet (UV) light single-mode delivery of PCF. Based on 260 nm femtosecond pulses output from a frequency-quadrupled fiber laser, transmission of the UV laser is experimentally demonstrated using a piece of PCF with small air hole. With a core diameter of 4.54 μm, the transmission loss and the coupling efficiency of the PCF are measured to be 0.043 dB/cm and above 31%, respectively.

Optical performance monitoring (OPM) is one of the key techniques of the reconfigurable wavelength-division-multiplexing (WDM) optical networks. When the optical communication speed rises from 10 to 40 Gb/s and above, the residual chromatic dispersion (CD) tolerance of the optical channel is only 1/16 of the former 10 Gb/s system. So CD monitoring is the critical technique for WDM optical channels. Integration and all-optical domain can be achieved when using the nonlinear effects of optical waveguides to realize CD monitoring. Silicon optical waveguides have the relatively large nonlinearity with the nonlinear refractive index as 5×10-18 m2/W. After going through the WDM network with CD effects, the signal light wave has the four wave mixing (FWM) effect with the probe light in the silicon waveguide. This FWM effect induces changes in the output spectrum, and different dispersions of the optical channel lead to the varied effects of FWM. So, when detecting the different spectrum changes relates to FWM, the optical channel CD can be monitored. In this paper a 3 cm silicon optical waveguide is adopted with the loss index of 0.2 dB/cm. The monitoring dispersion range can be ±40 ps/nm. The results indicate that this OPM technique can be used to monitor the CD of the optical network on chip level.

Based on the 2D triangular rods photonic crystal two-defect coupled-cavity waveguides, the new structure of slow-light waveguide is designed with better characteristics. The slow-light characteristic is simulated analyzed using plane wave expansion method. It is found that the mode outside the band will move into the band to form a guide mode by adjusting the radius of the defect rods. The waveguide structure with group velocity 0.0055c is obtained and the bandwidth is 135 GHz when c is the light velocity in vacuum. When the group velocity is about 0.01c, the bandwidth of up to 260 GHz is about to meet the needs of practical application. In addition, the waveguide structure is simple and tunable, and it can be applied to optical delay lines, all-optical buffer and other slow light devise.

This paper focuses on discussing the millimeter-wave amplitude fading problems caused by fiber chromatic dispersion for the millimeter-wave generated by optical frequency multiplication in the millimeter-wave radio-over-fiber (ROF) system. A novel millimeter-wave generation technique using dual-electrode Mach-Zehnder modulator (MZM) is proposed. Light-wave injected into dual-electrode MZM is split into two optical carriers, which are phase modulated by two microwave signals respectively and then combined together to fulfill the phase-intensity conversion and is transmitted through the fiber, and finally photo-detected to generate electrical signal consisting of harmonics of the microwave signal. The desired millimeter-wave signal is one of the harmonics and can be maximized just by adjusting the phase modulation index. The chromatic dispersion affection on millimeter-wave fading for two different bias states of the dual-electrode MZM is analyzed and compared. This study finds that the tolerance of ROF system to fiber chromatic dispersion is better when the two direct current (DC) biases of dual-electrode MZM are earthed. Optical fiber chromatic dispersion does not cause the appearance of odd harmonics, in addition, the amplitudes of even harmonics do not decline to zero. The conclusion of mathematical analysis has been verified by computer simulation and experiment.

Space optical communication demands harsh power budgets. Since the actual channel characteristics of the atmosphere is very complex, the channel power budgets tends to introduce large deviation with the general link equation. By the comprehensive analysis of the factors of effecting characteristics of atmospheric channel, such as atmospheric attenuation, turbulence effects and refraction, etc. Combined with a large number of the derivation and calculation, a correction method of the link equation is put forward to get a link equation that positively responds to the channel characteristics. By this equation, budgets optical power for the actual ground optical communications with the link distance of about 6 km and the bit error better than 10-8. Experiments and analysis show that the link equation correction method is reasonable, the power budget is consistent with experimental results, and the near ground optical communication is equivalent demonstration to satellite-ground optical communication.

Polarization maintaining fiber (PMF) resonator is the core component of a resonator fiber optic gyroscope. Polarization fluctuation induced by polarization coupling in resonator is one of the main sources of gyroscope’s measure error, and 90° docking of fiber polarization axis is an effective way to overcome the polarization fluctuations in resonator. In this paper, resonance characteristics and polarization characteristics of 90° docking in double couplers polarization maintaining fiber resonator are analyzed theoretically to obtain theoretical response curve, then sawtooth scanning method is experimentally used to obtain response curve with 24 finesse, 0.9615 resonant depth and 179.65° phase interval of the two polarization eigenstates. In consequence, good polarization characteristics of 90° docking in double couplers polarization maintaining fiber resonator are proved.

A compact high power supercontinuum source is designed and explored. A 1.5 m Yb-doped double cladding large-mode area photonic crystal fiber is employed as gain media of the laser. 0° end face of the fiber serves as a cavity mirror and output coupler. Stable mode-locking is obtained by using a semiconductor saturable absorber as another cavity mirror. A pair of grating is used for intra-cavity dispersion compensation. As a pump source, the laser generates 1.5 W, 494 fs pulses at 55 MHz repetition rate. Systemic study of the dynamics in the laser cavity is presented. Mode locking mechanism of the laser is demonstrated. Over an octave (680～1450 nm) ultra-flat supercontinuum with an average power of 500 mW is generated in a 1 m photonic crystal fiber.