Based on the principle of Hartmann-Shack wavefront sensor and the temporal and spatial analysis of the wavefront slope,a new method of measuring atmospheric parameters β ;the power-law exponent of the generalized phase power spectrum and ρ0 ;the strength of the turbulence is developed for non-Kolmogorov turbulence,by using the slope structure-correlation function and the generalized slope correlation coefficient measured by Hatmann-Shack wavefront sensor.The Hartmann-Shack wavefront sensor data acquired in recent horizontal atmospheric experiments for 1000 m laser beam propagation are used to evaluate β and ρ0 according to the method.

A novel profilometry with color encoded projecting grating is proposed.The grating is composed of white,red,green,blue and black strips.The white strip is used as beginning strip and followed by red,green and blue strips.The black strip is placed between two color strips to increase the period of grating.Thus eight strips form a group.Changing the order of color strips,different coding groups can be got.According to the principle of permutation,there are six kinds of arrangement of color strips for R,G,B colors,and so 48 strips is in one period of the grating.By decoding processing,the shape of an object can be obtained from single image.The obtained measurement depth is even wider than the depth of field of the CCD camera.Because the strips have only two logical states,the proposed structure-light system possesses high ability of disturbance-resistance.

An image processing method based on color filtering is proposed to realize hand tracking in a virtual reality system.Based on computer vision techniques,the method simulates the exclusive property of color vision of human eyes.Using the color of hand as a reference,the image received by CCD is processed to eliminate images of the background and other objects.After smoothing and contour extraction,only the profile of the hand is left in the image.The method can effectively eliminate the disturbance of the background and other objects.It can improve the reliability and increase the speed of hand recognition.

Learning samples significantly affect the recognition ability of neuron network models.One of selecting rules of learning samples is proposed according to the principle of the pattern recognition model.A method of selecting learning samples based on Hamming distance used in the cascade neuron network model for rotation invariance recognition is analyzed.The results of the computer recognition show that the effective selection of the learning samples can not only reduce the training time but also improve the recognition ability of the model.

The image of underwater laser imaging system ;UWLIS normally has poor contrast and high noise.To detect edges under this circumstance,two algorithms for improving anti-noise performance of Hough transform are designed.One is by adding the additional information of the direction of edge points,another by checking the connetivity between the edge points.The experiment of the mine-like object recognition with two algorithms described above is given.This result shows that the improved algorithms are evidently superior to the conventional algorithms.

The experiment of soft X-ray diffraction has been carried out with synchrotzon radiation to a two-dimensional array.Some images,which correspond to 0,2mm and 80 mm separation behind the specimen,were recorded as a relief pattern on photoresist with use of 3.2 nm X-rays from U-12A bending magnet at National Synchrotron Radiation Laboratory.The processed photoresists were enlarged with an optical microscope.The experimental result shows that patterns vary with the distance between specimen and photoresist detector,which are in excellent agreement with the theoretical results.

Numerical simulation is used to study the features of Gerchberg-Saxton ;G-S method for measuring wavefront distortion of laser beam propagation through the turbulent atmosphere.The retrieved wavefront error is analyzed and compared with that from Hartmann-Shack wavefront sensor.

Using a narrow-band tunable KrF excimer laser as a spontaneous vibrational Raman scattering ;SVRS source,spatially-resolved Raman scattering is used to measure the single shot concentrations of all major species ;N2,O2,H2O,CH4 in methane-air flames.A simple polarization technique and optimal tuning of the narrow-band KrF excimer laser are used for the minimization of OH and O2 fluorescence interference to improve the precision.Moreover a time-averaged temperature measurement technique is presented to fit the N2 spectrum to theoretical spectrum,by considering the fact that the Stokes spectrum of N2 will broden and the peak wavelength will blue-shift when temperature increases.The spectral-fit precision is less than 5% at 1500 K.

Experiments on the diagnosis of emission spectrum from glass capillary target irradiated by ultrashort intense laser pulses have been carried out with a high efficiency high resolution transmission grating spectrograph.Emission spectra among 15～25 nm at different laser energies and capillary lengths ;3 mm,6 mm,9 mm were measured.X-ray emission intensity increases obviously when the capillary length is increased.

Particle in cell ;PIC simulation is a feasible approach to understand the interaction of ultra-intense ultra-short pulse lasers.The output data from the simulation are often nonstationary signals varying in temporally or spatially.So the calculation of time-frequency distribution of these signals is introduced,and the results show that this technique is effective for diagnosing the time-varying ;or space-dependent signals from the simulation of the interaction of ultra-intense ultra-short pulse lasers.As an example,the stimulated Raman scattering for linear chirped pump laser in near 1/4 critical density of inhomogeneous plasma is investigated and a clear picture of the physical process is obtained by time-frequency distribution technique.

A detailed deduction and summary of above-threshold ionication energy calculation of multi-electron atom created by ultrashort strong laser pulses is given.The calculating methods of the threshold-intensity and saturation-intensity limits of the ion yield for each charge state produced by the laser pulse are developed,and the expression of average residual energy is deduced.A step-like saturation behavior of average residual energy with the rise of laser intensity is demonstrated in numerical simulation.

A simple average static model is proposed for studying the hamonic radiation characteristics of high power-driven electron in the laboratory frame,such as the angular distribution,the variation of the harmonic radiation with different laser power and so on.These results lend a novel way to find new coherent X-ray sources.

Diode pumped monolithic nonplanar ring laser has the advantages of compactness,reliability and high efficiency.When it was placed in a magnetic field,a unidirectional travelling-wave can be obtained with a high power single-frequency output.270 mW single-frequency,TEM00 output has be obtained from a Nd:YAG monolithic nonplanar ring laser.The working principles of this kind of laser is discussed in detail,and two kinds of new nonplanar cavities are proposed.Because of the similarity of the working principles,these kinds of nonplanar ring cavities are called the pan-triangle nonplanar unidirectional ring cavity.

A narrow-linewidth single-mode distributed Bragg reflection ;DBR fiber laser is discussed.Through theoretical analysis,the single longitudinal mode operation domain is obtained.Then according to this theoretical result,a single-mode DBR fiber laser is fabricated.This laser is pumped by a semiconductor laser at 975.50 nm and the operating wavelength is 1556.91 nm.Its output power reaches 1.43 mW and the lasing linewidth is less than 1.2 MHz;instrument resolution limited .The measurement shows that the laser operates at single-mode.

The probabilities of the cross-relaxation between Yb3+ and Er3+ ions in Yb,Er:YAG crystal are calculated.The energy up-conversion processes in this crystal are analyzed.By solving transfer rate-equations,the optimums doped concentration of Yb3+ and Er3+ ions are obtained.

The transient fluorescence characteristics and mechanism of Alq3 compound films have been studied.It has been found that the fluorescence peak wavelengths of Alq3 compound films blueshift and the fluorescence lifetimes are shorter than those of Alq3.The reductions of the fluorescence lifetimes of the compounds are attributed to the quenching of host molecules and the blue shifts of the fluorescence peak wavelengths are asigned to the interactions between Alq3 and the host molecules.

Based on Yb3+-doped laser glass reported abroad,the Yb3+-doped glasses with higher emission cross section are obtained experimentally.In these glasses,the Yb3+-doped tellurogermanate,borate and niobosilicate glasses have emission cross sections over 1.9 pm2,the phosphate glass has lower cross section but longer fluorescence lifetime.The better spectroscopic properties should make these glasses to be candidates of gain medium for high average power and high peak power lasers.

The technique of optical parametric chirped pulse amplifier proposed recently is introduced,and some characteristics such as phase match angle,gain and bandwidth are analyzed taking LBO crystal as an example.In addition,the dependence of the gain varying with length of the crystal is studied,and the transforms of the pulses after amplification with sech2 and Gauss shapes are given.

The multiple-carrier model for thermal/electrical poling is presented.Under the approximation of the full depletion,the calculating formulas for the width and electrical field of depletion region are obtained.They show that the relationship for the width and the maximum electrical field in depletion region against the applied voltage is square-root,while the conversion efficiency of second-harmonic generation is square with voltage.The width of the depletion region is 3～8 μm,and the maximum electrical field below the anode surface 1～6 μm is 1～4 V/nm.

An all-reflective system with compact structure and wide field-of-view is designed on the basis of the three-mirror aberration theory.Coaxial design is adopted whereas its off-axis rays is used,so that the length of its lens barrel can be of f′/7～f′/9,field-of-view more than 3°,the obstruction ratio less than 6%,and the image of quality reaches to the limit of diffraction.The optical system suits the needs of long focus remote sensing CCD camera.

On the basis of experiments,the nonuniform models of modulation of refraction index and variation of spatial frequency are obtained by using nonuniform coupled-wave theory.The nonuniform distribution characteristics of the filters having high diffraction efficiency and narrow bandwidth are analyzed on the nonuniform model,and a method for improving properties of notch filter is proposed.The holographic notch filters with high optical density and narrow bandwidth are fabricated using dichromated gelatin ;DCG .The characteristics of these filters are that the optical density of peak wavelength is between 4 and 5,and the half-bandwidth is smaller than 20 nm.

The flattened Gaussian beam is regarded as a whole beam,and its propagation through a paraxial optical ABCD system has been studied in detail.The general closed-form propagation expressions have been derived for the unapertured case,whereas for the apertured case numerical integral is applicable.Typical numerical examples have been given,showing the equivalence of this method and the finite Laguerre-Gauss function expansion.

The influences of dipole-dipole interaction between atoms on the mean photon number of radiation field,the photon antibunching effect and the properties of the light squeezing in the Tavis-Cummings ;T-C model with a single-mode vacuum field are studied.

The cavity field spectrum of a pair of two-level atoms coupled by dipole-dipole force in a ideal cavity with two-mode radiation field is studied.It is found that the field intensities of one mode do influence the spectrum of another mode.Three-peak structure appears when two mode cavity fields are all strong and all in pure number states or in coherent states initially.If fields intensities of two mode are different,single-peak structure appears for strong field mode and three-peak for weak one.However,squeezed vacuum fields exhibit rather different features showing the classical resonance fluorescence spectra at large .

An important property of apodized weak fiber Bragg grating ;FBG is demonstrated.It shows that if the reflection spectra R;Δβ of an apodized weak FBG is needed to be narrowed to ′1/n′,i.e.from R;Δβ to R;nΔβ,then the apodizing function g;z should be broadened ′n′ times,i.e.from g;z 0<z<L to g;z/n /n,0<z<nL.Two examples are given to validate this property.

An improved method using white-light interferometry and optical fiber Michelson interferometer to measure group refractive index is introduced.The measurement process is simplified when sandwiched sample is used and contacted with detecting fiber surface.The collimating between sample and the detecting fiber can be adjusted according to the change of the bandwidth of the reflective peak.

The metal multilayers were sputtering deposited on K9 glass,and their simple structural parameters were obtained by the small angle X-ray diffraction.A formula for calculating the thickness of transfer layers is proposed,and the calculated results of samples is presented.Compared to the results obtained from the fitting method,these results are similar.