A universal and convenient matrix series method to solve the Raman Nath equation of normal ultrasonic light diffraction is presented. The results show that the diffraction efficiency for Bragg approach is only 97.5% at Q=4.1π, and that for asymmetry incidence, there is large error in previous Raman Nath approach. The formula of the optimum length of the acousto optics modulator is given. Increasing the ratio of acoustical frequency to optical frequency is a effective way to improve the diffraction efficiency.

The output characteristic of fiber optic voltage sensor is analyzed. It is found that the response of the voltage sensor is nonlinear and the sensor suffers from the influence of temperature over a wide measuring range. A method for temperature tracking compensation of fiber optic voltage sensor based on artificial neural network is presented in this paper. In order to realize temperature tracking compensation over a full range, the neural network is trained to properly represent the nonlinear mapping between the sensor reading and their represented output accurately at different environmental temperature. It is revealed from the computer simulation result that not only the influence of temperature fluctuation can be eliminated effectively, but also a desired linear relationship between the sensor input and the neural network output can be obtained.

A new structure of all fiber interferometer is constructed based on the analysis of beat frequency character of 2×2 optic fiber. The interferometer can be used for adjustment the alternate interference signal and used wide in the field of test for vibration character, length of optic fiber and speech signal collection.

Kinetics of thermally induced damage of rat liver at different constant temperature (55～95℃) were studied with continuous wave transillumination technique. It showed that thermal damage could be described by scattering coefficient. According to the relation of change in scattering coefficient and time at different temperature, the activation energy (E=135 2 (kJ/mol)) and entropy of activation  (Δ S=116 7 (J/K·mol)) were calculated. The thermal damage of rat liver was analyzed. This work provides a new method to measure thermal damage properties.

The initialization conditions have great effect on the reflectivity contrast and CNR of Ge 2Sb 2Te 5 phase change optical disk. It is indicated that the reflectivity contrast increases at low velocity, while decreases at high velocity, as the initialization power increases and the reflectivity contrast decreases as the initialization velocity increases. Also the reflectivity contrast is very different when the measurement wavelength changes from 400 to 900 nm. The CNR of Ge 2Sb 2Te 5 phase change optical disk first increases and then decreases when the initialization power and velocity increase. The most favorable initialization conditions are those that power ranges from 1100 to 1300 mW and velocity ranges from 3.0 to 4 2 m/s.

Phase unwrapping is an ill posed problem. A new 2 D phase unwrapping method, based on the global continuity of the physical information, is proposed in this paper. The method, which is derived from the least cross section difference of the physical quantity, has shown to produce a reliable result in the presence of error sources, such as noise, phase discontinuity more than π and insufficient sampling, etc. In addition, the algorithm is very simple and fast.

To avoid the forming of cracks in iron based laser cladding, the volume fractions of austenite and cemetite in cladding layers were adjusted through adjusting the contents of Ni. The claddings were produced on gray irons without preheating. Based on the optimum parameters of laser processing, the effects of Ni contents on the volume fraction of austenite and surface cracking were investigated, the cracking mechanisms were revealed, and a sort of Fe C Si Ni cladding material was obtained which could form crack free 25 pass cladding layers on iron. By adding Ti powders into the Fe C Si Ni cladding material, endogenous TiC could form in cladding layers. The effects of endogenous TiC on wear resistance of cladding layers were also investigated. As a result, Fe C Si Ni Ti cladding materials were obtained which could improve the cracking and wear resistance significantly.

This paper reported a technique of adopting laser welding to joint the diamond core drill segments and canister which improved the coalescent intensity compared with common brass solder. The laser welding technique and the structure performance of welding line were investigated. It showed that the laser welding diamond core drill bit can conquer the defect of segments desquamate, can adapt more work conditions, and can increase the using time by 25%～108%.

The SNR of faint signal is very low in the long distance laser ranging or bad circumstance laser ranging, so it is very difficult to recognize the echo wave. This paper introduces digital correlation detection method and uses it to process the signal. Single signal correlation and multi signal correlation are simulated and calculated with laser ranging radar and a good results is got. This study will help to greatly improve the ability of laser ranging radar.

The influence of the etalon effect of the two plano plano face Nd∶YVO 4 crystal on the frequency tuning characteristics of single frequency laser is investigated. Using the 1° wedged Nd∶YVO 4 on one face and mode selection property of the etalon inserted inside laser resonator, the precise frequency tuning of LD pumped single frequency ring Nd∶YVO 4 laser has been demonstrated experimentally by means of adjusting the inclined angle of the etalon. The maximum tunable frequency range is about 100 GHz.

The design and experiment results of MOPA single longitudinal mode Nd∶YAG laser are introduced. The seeder laser with 1 μJ, 22 ns is amplifed for six times. More than 100 mJ, near diffraction limited laser beam is obtained.

Single frequency Yb 3+ doped fiber lasers operating at 1053 nm pumped by laser diode have been achieved. Characteristic of the lasers was researched in this paper. The power of 18 mW with F P cavity, and 1.3 mW with the structure of phase step DFB were obtained, respectively.

Noncollinear phase and group velocity matching of femtosecond OPA based on periodically poled lithium niobate were discussed, which differ from that based on birefringent phase matched traditional crystals such as BBO. The noncollinear phase matching was investigated in noncritical phase matched PPLN and tilted PPLN.

Based on waveguiding mode theory and non paraxial vectorial moment theory, the beam quality of TE 00 mode propagating in GaAs/AlxGa1-x As strip buried heterostructure semiconductor laser is investigated theoretically, and the emphasis is laid on the variational relation between the beam quality factor in the direction parallel to the junction plane M2y and the active layer width W. The results show that M2y fluctuates with the active layer width W, which is useful for the proper design of the active layer width.

On the basis of the light scattering theory of spherical particles and the characteristic of the water mist, by theoretical computation and experiment study, the lay out parameters of the APV (adaptive phase/Doppler velocimeter) system are given. Experiment measurement and analysis are carried out to study the characteristic parameters of the particles in the water mist flow field. The particle size and the velocity distribution and the water mist volume flux flow field are obtained from the experiments.

Aluminum targets with three kinds of thickness (6,10 and 20 μm) were driven by laser at 0 35 μm wavelength on "Xingguang Ⅱ" facilities. Shock wave images were recorded by optical streak camera, heat wave and rarefaction wave images were measured using X ray streak camera. The experimental investigation on the interactions among shock wave, heat wave and rarefaction wave was made. Through several measure technique, the three wave interaction physical images were obtained in which shock wave early heat wave was late and rarefaction wave was last.

In this paper, a novel straightness/coaxiality measurement system using transversal Zeeman dual frequency laser is introduced. In contrast to longitudinal Zeeman system, the size of instrument is shortened and the non linearity error generated from quarter wave plate is avoided. The system is self adaptive and quite resistant to air turbulence. Phase measurement can reach 0.1 degree equivalent to 1 μm. Measuring component can be removed from light path during measuring process. Using 8098 singlechip computer to stabilize the beat frequency intelligently, experiment has shown that the change of beat frequency is less than 0.5 kHz in 10 hours. The measuring stability is about 2 μm/h. Correlation coefficient of linearity of indicating value is better than 0 9999. It realizes the straightness/coaxiality measurement of long range.

In this paper, a model was put up to non invasively measure capillary blood flow using diffusion light auto correlation. The influences of the Brownian motion of scatterers and the capillary blood flow on the auto correlation of diffusion light were theoretically analyzed. The theoretical and Monte Carlo simulation results show that the characteristic correlation time exponentially decays as the mean square velocity of capillary blood flow increases.

The frequency doubled output of a single frequency Nd∶YVO 4 laser centered at λ0=532 nm was used as input pump to excite single mode fused silica fibers with length of 250 m and 920 m, respectively. The study on broadband SRS Stokes spectrum within range of visible spectrum in fused silica fibers was made. The first order to the fourth order SRS Stokes spectra were obtained, and frequency shift peak was at 450 cm-1, 1064 cm-1, 1610 cm-1 and 2168 cm-1, respectively.

Equations describing circular Gaussian beams (CGB) propagating inside the absorptive Keer medium have been derived from nonlinear paraxial equation. Based on these equations, an evolution equation of the beam waist has been obtained. The evolution equation indicates that, depending on the beam and material parameters, the circular Gaussian beams may be convergent or divergent when travelling inside the nonlinear medium. There is a special threshold beam whose waist approaches zero at the point where the self focusing can just compensate for the diffraction. After solving the evolution equation, the threshold intensity and threshold focal length of the threshold beam have also been specified.

Analytical expressions of equivalent noise figure and other noise characteristics of distributed fiber Raman amplifier (DFRA) are derived under complex conditions. These conditions include difference in polarization state and attenuation coefficients between pump and signal light as well as multiple wavelength pumping. Accordingly, their impact on DFRA performance and optical signal to noise ratio improvement (ΔOSNR) of concatenated DFRA+EDFA is investigated. With increasing DFRA on off gain, ΔOSNR increases first linearly and then logarithmically, resulting in saturation. Results of this work agree well with numerical simulation of existing work.

The impacts of phase errors induced by the fabrication errors on the transmission characteristics of an AWG are studied in this paper. The non random phase error makes the central wavelength of the channels shift, the studies show that when the 0 02 μm change of the width of the waveguide will cause 0 1 nm shift of the central wavelength. The random phase error deteriorates the crosstalk of an AWG, the studies show that the maxium random error of 0 00004 rad/μm will make the crosstalk increase 42 dB.