In order to improve the quality of ocean color satellite remote sensing data and achieve quantitative applications, the accurate calibration of satellite sensor is the key. By using the water and atmospheric optical parameters measured in the South China Sea PY30-1 platform, we have carried out the vicarious calibration of Aqua satellite′s moderate-resolution imaging spectroradiometer (MODIS) sensor by reflectance-based method. Our results show that the calibration gain factor is very close to the MODIS research. In addition to 443 nm band, the calibration gain factor relative deviations were less than 5%. This study shows that the reflectance-based method can be applied to the China Sea, we can get the accurate calibration gain factor.

By obtaining data of the CE318 automatic sunphotometer installed on the PY30-1 platform from September 2011 to October 2012, the aerosol optical characteristics in South China Sea is studied. The main aerosol optical parameters are aerosol optical thickness, Angstrom exponent, complex refractive exponent, single scattering albedo and scattering phase function. Carrying out research of the aerosol optical characteristics in South China Sea, is an important part of calibration and validation of satellites. The results show that the aerosol optical parameters are similar with the coastal mode, and can be used for calibration and validation of satellites.

A multiplexed fiber-optic sensor combining the advantages of extrinsic Fabry-Perot interferometer (EFPI) and fiber Bragg grating (FBG) is presented for simultaneous stress and temperature measurement. Ultra-high-vacuum magnetron sputter system, electroplating technology, and laser welding technology are adopted to realize fiber sensor encapsulation without adhesives, which can improve the resistance to elevated temperatures of the sensor. Experimental results show that the sensor has a stress sensitivity of 90 pm/N and a linearity of 0.9965 at the temperature of 290 ℃. FBG of the multiplexed sensor has a temperature sensitivity of about 12 pm/℃ and a linearity of about 0.9988. Broad applications based on the metal packaged multiplexed fiber optic EFPI-FBG sensor at higher temperature in this work can be expected.

The Brillouin distributed optical fiber sensing technology can measure the optical fiber strain, but the measurement precision is affected by noise easily. So a new method of wavelet denoising is developed to enhance the measurement precision of optical fiber strain. The new method not only takes the wavelet transform detail coefficients to threshold quantification, but also removes the noise from the approximation coefficients. So the new method can also obtain high precision Brillouin spectrum with fewer decomposition scales as the signal-to-noise ratio (SNR) of Brillouin spectrum is low. The research results show that the method can reduce the Brillouin spectral noise effectively. Compared with the conventional wavelet denoising method, the new method can decrease the wavelet transform calculation and the denoising effect is better, so the optical fiber strain measurement is more accurate.

The basic principle of heterodyne demodulation of fiber interferometer is introduced. The influence of optical intensity perturbation on heterodyne demodulation based on differential cross-multiply (DCM) and arctangent is researched. Theoretical analysis and numerical simulation are adopted. Theoretical analysis demonstrates that both algorithms can restrain the influence of optical intensity perturbation effectively. But the impact of higher perturbation cannot be eliminated totally, which is limited by the design of lowpass filter. Meanwhile, compared with the traditional phase generated carrier (PGC) demodulation based on arctangent, heterodyne demodulation based on arctangent has an extra advantage in eliminating the influence of the modulation depth C. Numerical simulation matches well with theoretical analysis. Experimental architecture based on heterodyne detection is constructed and demodulation experiment is implemented. The results of experiment demonstrate that both algorithms can eliminate system noise including intensity perturbation.

The infrared imaging simulation credibility evaluation model is proposed based on the decision making thought of analytic hierarchy process. The index system to evaluate the infrared imaging simulation credibility is established. The indexes′ credibility is obtained by applying the statistic analysis or expert′s graded approach. The sum and product method is used to calculate the credibility evaluation factors′ weight. Then the objective quantitative credibility of infrared imaging simulation is gained by considering all credibility evaluation factors comprehensively. The results of research and theory analyzing demonstrate that the proposed method can evaluate the credibility of infrared imaging simulation, and the evaluation result is well consistent with actual infrared image. Theory analysis and the evaluation result of credibility shows the method is reasonable and efficient, and the scientific decision basis is afforded to the simulation users.

Radial shearing interferometry has been widely used to test distorted wavefront. However, the result of wavefront measurement by using this technique includes two parts, one is the real phase information of wavefront under test and the other is the system errors in radial shearing interferometer. A calibration method of a radial shearing interferometer is presented. First of all, several fringe patterns of the phase difference distribution are obtained by a tested component with different positions. Then, the maximum likelihood method is used to combine the phase difference data and create a maximum likelihood function. After that, the wavefront under test and system errors can be separated. The simulation results show that the maximum likelihood method can deal with the issue of the calibration of a radial shearing interferometer. Furthermore, the method is used to reduce the effect of the system errors on extracting and reconstructing the wavefront under test.

Laser triangulation system with single imaging lens is not suitable for measuring the groove profile. Diffuse reflected light of illumination point on object surface is blocked by steep groove edges and a measurement blind zone is formed, because the projection axis and the imaging axis are in a certain angle. To solve this problem, a laser dual-triangulation system based on the laser triangulation method with Scheimpflug condition is developed for groove profile measurement. The autoregulation of integral time of image spot detector and the digital filtering of image intensity data are discussed. Extraction of image spot center and discriminance of imaging point due to imaging beam shaded by groove edge are also studied. The dual-triangulation mapping relationship is determined by calibration experiment. The compressive deformation measurement of tread profile indicates the validity of this system and the measurable depth-to-width ratio of the groove profile is more than or equal to 5 mm.

In order to obtain the lifetime index of the single-bar 808 nm high power semicondutor laser, an on-line monitoring system under ten workspaces is set up. Subsequent lifetime tests are completed. The conditions of these tests are 25 ℃,100 A, 50 ℃,100 A and 50 ℃, 115 A, respectively. According to the linear regression analysis, the method of least squares, goodness-of-fit test and other statistical knowledge, the power degradation model is obtained. Based on this degradation model the extrapolated lifetime of cm-bars at 25 ℃ is 2.86×109 shots. This lifetime extrapolative method based on the parameter degradation model has some advantages such as short experiment time and high veracity than other traditional accelerated aging test methods.

We demonstrate a 532 nm and 1 kHz picosecond laser amplifier which is made up of one home-made picosecond oscillator seed, a regenerative amplifier, two-pass amplifier, a main amplifier, and a frequency doubler. The green laser has a beam quality factor of 1.39 and 1.96 for tangential direction and sagittal direction, respectively, and the long-term stability root mean square (RMS) is less than 0.3%.

Based on the vectorial Debye diffraction theory and taking linearly polarized anomalous hollow beam as an example, the phase singularities in the focal region are studied. It is found that electric and magnetic phase singularities depend on the truncation parameter and numerical aperture. By varying the truncation parameter, the motion, creation and annihilation of phase singularities of electric and magnetic field take place in the focal region. By companying phase singularities, a pair of saddle points may appear and behave similarly. A pair of saddle points and the corresponding pair of phase singularities approach, and then annihilate each other, which leads to the subwavelength structure. However, the singularities annihilate behind saddle points. There exists the different critical point of truncation parameter, where the creation or annihilation occurs at the same numerical aperture. The results are illustrated and compared by numerical examples.

Smoothing by spectral dispersion (SSD) technology has been widely used for many high-power laser drivers. However, due to the engineering design reasons, national ignition facility (NIF) and technical integration experiment line (TIL) use only one grating. It will affect the smoothing efficiency, especially at the beginning time. But we can reduce it by the way of optimizing the modulation frequency. Finally we analyse the SSD technology with one grating and provide a theoretical basis for the optimization of high-power laser drivers.

The theoretical model of high-power fiber incoherent combined beams propagating in atmospheric turbulence is established, including single mode laser and multi-mode laser. The influences of collimating system, mechanical jitter and atmospheric turbulence are considered. The results show that the beam quality′s degeneration ratio of 10 kW single mode fiber laser is 10% resulting from the collimating system. And the ratio of 30 kW multi-mode fiber laser is 1%. For six incoherent combined beams without tip-tilt correction, the advantage in propagation performance of single mode beam decreases with the increase of the intensity of turbulence when the propagation distance is longer than 5 km. The maximum intensity gain due to tip-tilt correction of single mode beams is 1.32 times than without tip-tilt correction when the propagation distance is 5~15 km, while the gain of multi-mode beams is not obvious.

In order to study the effect of laser shock processing (LSP) on mechanical properties of welded magnesium alloy, tungsten inert-gas (TIG) welded AZ31B magnesium alloy sheets are processed using NdYAG laser with wavelength of 1064 nm, pulse width of 15 ns, pulse energy of 4 J and spot diameter of 3 mm. The microstructures of welded joint are examined through optical microscope (OM) before LSP. The microstructures of welded joint surface layer of sample are characterized by transmisstion electron microscope (TEM) and X-ray diffractometer (XRD) after LSP, and fracture surfaces are analyzed by scanning electron microscope (SEM). The mechanism which causes the mechanical properties improvement is discussed. The results show that nanocrystalline can be produced on the surface layer of TIG welded joint by using optimized laser parameters, and nano grain size is about 35 nm. The surface residual stress of heat affected zone is converted from tensile stress (60 MPa) to compressive stress (-125 MPa) by LSP. Tensile strength and yield strength are improved by 15.2% and 15.7%, respectively, and surface micro-hardness is enhanced by 78.2%. Furthermore, the mean impact energy of samples is increased by 58.8% after LSP. The mechanical properties improvement is attributed to a combination effect of surface nanocrystallization, strain hardness and residual compressive stress.

In order to broaden the industrial application range of laser shock peening (LSP), a system with 10 MW laser pulses delivered by a standard 1000 μm multi mode optical fiber is developed. The system is composed by three units, laser coupling unit, laser delivery unit and laser collimation unit. First of all, N-ON-1 method is selected to measure optical fiber damage threshold and laser pulse energy is determined accordingly. Then, fiber-coupled LSP is carried out on 6061-T6 aluminum alloy sheet metal, and two spot layout schemes are studied to obtain the optimum residual stress. Residual stress is measured by X-ray diffraction method. The largest residual stress induced by LSP on the surface of sample is -160.55 MPa. This system can provide some strong theoretical basis for the flexible manufacture of laser shock technology.

Laser transmission joining of fiber reinforced polyamides (FRPA) has potential application in industry. Based on a central composite rotatable design, comprehensive experiments of laser transmission joining of FRPA are carried out by a diode continuous laser source. The microscopic cross-section observation shows that the joining area is good. The effect of process parameters on the joint quality is analyzed by processing of the experimental data. Finally, mathematical models between the process parameters, the lap-shear strength and the joint width are determined by response surface methodology. The results show that the process parameters of laser transmission welding play a significant role in determining the joint quality; and the predicted data of the models are in good agreement with the experimental results. So this study could provide an effective instruction to choose the reasonable process parameters for enhancing the joining efficiency.

The optical activities of organic compounds are dertermined by their energy band gaps. By extending the conjugated system of phthalocyanine molecule and adding peripheral electrophilic subunits, near-infrared emitting of organic molecule materials is realized. A new aza phthalocyanine containing four 1,10-phenanthroline subunits is synthesized and thin-film samples are prepared. The maximum absorption wavelength reaches beyond 1 μm. The photoluminescence (PL) spectra show emission wavelength is at the range of 1.3 μm, which is one of the important optical communication wavelengths. The cyclic voltammetry measurement is performed. The energy band-gap is determined to be 1.1 eV. The narrow band-gap further verifies its near-infrared optical activity. This paper provides some experimental data for developing organic NIR materials.

Y2O3 nanoparticles codoped with Yb3+/Li+ ions are synthesized by glycine combustion method. Codoping with 5% mole fraction of Li+ ions leads to about 12 times enhancement of the photoluminescence (PL) intensity around 1 μm under diode laser excitation of 940 nm. The movements of the X-ray main diffraction peak indicate that the codoping of Li+ ions changes the lattice environment of Yb3+ ions. Theoretical investigations based on the steady-state rate equations indicate that the PL enhancement arises mainly from the increased ground state absorption cross section of Yb3+ ions by codoping with Li+ ions. The codoping of Li+ ions can disturb the local crystal field around the Yb3+ ions in Y2O3 crystals, change the PL transition selection rules of Yb3+ ions, resulting in enhanced intra-4f electric-dipole transitions and oscillator strength, which leads to the increase of ground state absorption cross section.

From Mar. 21 to Apr. 19 in 2011, atmospheric observations with mobile Doppler wind lidar at Beijing observatory are operated by China Meteorological Administration. Atmospheric boundary layer is observed and analyzed by the gradient of lidar range-corrected signal. The processed results of lidar observation data indicate that the average mixing layer or surface stable boundary layer height is (1.44±0.75) km at 800AM and (2.23±1.13) km at 800PM, the average atmospheric boundary layer height is (2.88±0.92) km at 800AM and (3.37±0.82) km at 800PM, respectively. Compared with the gradient of potential temperature and relative humidity of synchronous radiosonde, the correlation index is as much as 94%, which shows good consistency with lidar.

Frequency-modulation continuous-wave (FM-CW) ladar is a new kind optical incoherent ladar. In its emission source, how to get a broadband modulated high-power continuous laser emission is the key technology. Two kinds of “seed laser” source, CQF935/5624 and EM650, are studied respectively. The performance of the related devices is tested and the results are given. The modulation performance is researched by conducting a series of experiments. The influence of the nonlinear factor on the modulation performance is discussed. The experimental results indicate that both the two “seed laser” sources have a good modulation performance, which can lead to a further application in the future. EM650 has more advantages for its integration.

The inhibitions of scenedesmus obliquus, chlorella pyrenoidosa and chlorella vulgaris stressed by the same concentration of Hg2+, Cd2+, Cu2+, Zn2+ are investigated with pulse amplitute modulation (PAM) technology.The chlorophyll-a fluorescence parameters of PSⅡ system are measured and the inhibition rates and response times of three kinds of algals offer reference for the sensitive microalgal species. From the results, chlorella pyrenoidosa is determines as a sensitive microalgal species to Hg2+, Cd2+, Cu2+, Zn2+. The sensitivity of three microalgals can be expressed as chlorella pyrenoidosa>scenedesmus obliquus>chlorella vulgaris.The toxicity results of four kinds of heavy metal ions can be expressed as Hg2+>Cu2+>Cd2+>Zn2+. Compared to algal growth inhibition experiment, this new method for a sensitive microalgal specie selection is simple and rapid.

Microcystis aeraginosa is cultivated in BG-11 medium and nature water for 100 d. Dynamic law of microcystic toxins MC-LR released by microcystis aeraginosa in different growth phrases is studied. The results show: the chlorophyll-a concentration maximum of microcystis aeraginosa appears 10 d ealier than the MC-LR concentration maximum, whatever algal is cultivated in BG-11 culture medium and nature water. Similar dynamic laws showe in both culture medium are that chlorophyll-a concentration and MC-LR concentration are positively corelated in the logarithmic period and negatively correlated in the stabilization period, and chlorophyll-a concentration reduces while MC-LR concentration first increases, then decreases in the decline period. This regularity maybe closely linked to the characteristics that pigment in vivo cells released into medium could catalytic MC-LR photodegradation. The linear relationship from fitting between the chlorophyll-a concentration and MC-LR concentration, of purebred microcystis aeraginosa cultivated in laboratory condition, is used to provide a basis of approximately estimating microcystic toxins MC-LR concentration by chlorophyll-a concentration of water.