The strain effect on fiber Bragg grating (FBG) wavelength, 3 dB bandwidth reflectivity and characterizatin of delay is experimentally studied. Change of the center wavelength and 3 dB bandwidth is linear with the strain, but the reflectivity decreases when the strain increases. Linearity of delay becomes better, root-mean-square deviation of delay ripple reduced and compensation lessens, when the strain increases.

A fiber Bragg grating is slantingly bonded to the side of the rectangle cantilever beam, and the chirp effect of the grating would appear by adjusting the displacement of the beam's free end. The displacement sensing using the chirp effect of fiber Bragg grating under strain-gradient is demonstrated in this paper. Because the bandwidth of the grating is temperature-insensitive, the cross talk between displacement and temperature is avoided. The good linear response has been obtained.

When GS method are used for retrieving wavefront, the results are not determinate. This paper reported our work of the uniqueness of phase in which GS method are used for retrieving wavefront of laser beam propagation through the turbulent atmosphere by using Numerical simulation, and put forward some new quadratic driving mends to GS method. Meanwhile, the results getting from GS method are given, and wavefront errors are also compared and analyzed. It is shown that the mends of GS method can not only resolve the uniqueness problems of GS method, but also quicken the speeds of the convergence.

The paper reports the experimental results of CO2 laser and Er: YAG laser making holes in myocardium. It gives three experimental curves: h-t curve of CO2 laser's making hole in myocardium when power is 100 W, h-W curve of CO2 laser's making hole in myocardium when irradiating time is 0. 3 s, h-n curve of Er: YAG laser's making holes in myocardium when pulse energy is 500 mJ. It analyses the experimental results and provides a reference for clinical application of laser transmyocardial revascularization.

A new acrylamide-based photopolymer sensitive to green light is reported in this paper. This material is composed of monomer, crosslinker, photoinitiator, coinitiator, and polymeric film-forming binder. Holographic diffraction efficiency as high as 50% can be attained. The best dye concentration is got by optimization of material's composition. A hologram can be stored in this photopolymer and the image can be reconstructed clearly. So this photopolymer is promising to high-density holographic recording.

In this paper the relationship of Bragg-mismatch and recording angles of holographic photopolymer is deduced, and compared with the experimental result. It showed that the theory tallied with the experiment well. The result indicated that with the decrease of the angle between reference beam and object beam, the Bragg-mismatch increases, this result is important to the design of photopolymer holographic memory system.

The comparative experimental researches demonstrated that laser cladding NiCrSiB alloy was of great tendency to cracking, with its microstructure mainly composed of small amount tough phases and a great deal of brittle disorder-distributed coarse hard phases. Laser cladding NiCrSiB + 50% Ni was a dendrite microstructure without cracks. Laser cladding Stellite 6 alloy was not sensitive to cracking, its microstructure consisted of tough dendrites and inter-dendrite eutectics. Cracks appeared in laser cladding layers of Stellite 6 plus over 18% of WC, their microstructures changed to be more brittle with more eutectics, more precipitated carbides and more complex shaped carbide precipitates. The basic reason for cracking is the big tensile stress induced in the cladding process, and the principal reason for cracking was attributed to the high brittleness of the as-clad layers due to the random shapes and disorder distribution of the hard phases in the microstructure. The method to decrease the cracking tendency was proposed to change the morphology of the strengthening phases, in which the hard phases precipitated dispersively within the microstructure and gradient distributed in the clad layers, in wuch a way the clad layer will be strong enough with good toughness and the tensile stress in the interface will be dramatically decreased at the same time.

The high power Nd3+ : YAG laser is selected in the experiments owing to the light absorptivity of energetic materials and the light transmission in the optical fiber. Several kinds of energetic materials are ignited using laser energy. The ignition curve of energetic materials is successfully obtained. The factors which affect the laser ignition characteristics of energetic materials are analyzed, which include laser energy, pulse width, the grain size etc. The experimental results show: the laser ignition features of different energetic materials exists distinction. It is mainly caused by the thermal physical quality of individual energetic materials. This will provide references for the design of laser ignition systems.

In this paper, the effects of thickness and flexibility of confining medium on laser shock strengthening and laser shock forming have been successfully investigated with different experimental method, and the relationship between the rigidity of confining medium and laser-induced shock wave was demonstrated. The experimental results revealed that an appropriate overlay thickness can not only use laser energy effectively but also provide optimal peak pressure of shock waves. It was also apparent from the experimental results that an appropriate overlay rigidity can increase peak pressure of laser-induced shock wave more effectively than flexible overlay, and attain the better effects of laser shock processing (LSP).

This paper is focused on the research of the 316 L stainless steel prepared by laser direct deposition, especially on the influence of laser power on the microstructure and properties of the parts by laser direct deposition. The results show that the obtained microstructure of the thin wall of stainless steel is composed of dendrites with the condition of the laser power less than 900 W, however, when the laser power reached to 1150 W, the dendrites become shorter. The mechanical property testing indicates that the as-formed 316L stainless steel under different laser power can meet the need to actual utility.

This paper investigates laser forming of Ti-7Al-2Zr-2Mo-2V with a 2000 W fast-axial flow CO2 laser unit. The study has been on the influence of accumulated energy density (AED) on the microstructure and Hvs hardness of laser bent Ti-7Al-2Zr-2Mo-2V. The paper presents a concept of critical value on AED. Microscopy observations have revealed that there are no effect on the microstructure of Ti-7Al-2Zr-2Mo-2V with the AED values less than 40 J/mm2, but the effects occur with the AED values higher than the critical value. With the increasing of AED the HAZ size grows in quadratic function.

A diode-pumped Yb:YAG microchip laser with good beam quality was presented. At room temperature, 91.5 mW output power at 1.049 μm was obtained with 10 at.-% doped Yb: YAG microchip crystal and 1 W InGaAs diode. The slope efficiency was about 30 % . The M2 values were found to be 1.14 and 1.07 in the vertical and horizontal directions respectively. When the crystal was cooled, 111 mW output power and 40% slope efficiency were obtained.

Using a novel, all-fiber structure composed of WDM, fiber grating and home-made Yb 3+ -doped single-mode fiber, the F-P cavity laser operating at 1060 nm with narrow-FWHM is realized. Optimal length to be 9 m are found through the experiment for different length of the YDF. The threshold of launched pump power is 30 mW. When launched pump power is 42.8 mW, the maximum laser output is 8.8 mW with a FWHM<0.5 nm. The slope efficiency is 70.4% with respect to the launched pump power.

The 1.57μm signal light produced by non-critically phase-matched KTP optical parametric oscillator (OPO) pumped by the depleted 1.064 μm Nd: YAG laser after frequency-doubled conversion is injection-seeded into another non-resonant KTP OPO pumped at 532 nm with dual-crystal walk-off compensating configuration. The threshold of non-resonant OPO is reduced by 30% , and energy conversion efficiency is increased by a factor of 5 %.

Powder SHG method is one of the main methods to study new materials. This paper carries out more detailed research, concerning the angel distribution of reflected light and its relations with incidence angle and powder size. The study validates correctness of experimental setup by taking 60° as incidence angle, and detecting at reflection angle. When samples have different powder size, it is suggested to use small incidence angle and detect at normal to reduce granular effect.

Absorption of CO_2 laser on the surface film-metallic substrate was discussed. The relation between absorptivity and electromagnetic properties as well as optical properties of thin film have been established via the resolution of the electromagnetic wave equations. The criteria and the optimal range of selection of high absorptivity films were given.

The amendatory Bragg formula may be used for calculating the periodic thickness of multlayers deposited on the plane substrate by small X-ray diffraction spectrum. However, the diffraction peak angle of multilayer deposited on the curved substrate will be different from that of multilayer fabricated on the plane substrates though they have the same periodic thickness. Thus, the calculated periodic thickness of the above multilayer with the Bragg formula is not well agreement with the real value of the multilayer. This paper gives an analysis of phenomenon of diffraction peak excursion, and gives a revised formula derived from the amendatory Bragg formula for accurately calculating the periodic thickness of multilayer deposited on any substrates. The experimental results show that the periodic thickness calculated with the formula is consistent with the practical periodic thickness.

The measuring accuracy of four-beam laser tracking system for 3D coordinate measurement in large degree depends on the arrangement of the interferometers. In this paper the arrangement of four laser tracking interferometers is discussed and three kinds of the optimal arrangements of four laser tracking interferometers are obtained through minimizing the position dilution of precision of the measured point. One of those arrangements of four laser tracking interferometers is considered as the most reasonable arrangement according to the limited receiving angle of the cat's-eye and the restriction on the arrangement in the process of system self-calibration.

The optimal measuring zone under the optimal arrangement of four laser tracking interferometers is discussed, and the distribution of PDOP of the measuring points in 3D space is also given. The relationship between system arrangement and the self-calibration is also studied by using of computer simulation. The results show that the nominal setup of all the optimal measuring arrangements plays the least role in the process of the system self-calibration and has the minimal value of PDOP of the measuring points. So, it is finally reached out that the nominal setup is just the optimal arrangement of the whole system.

In static gas target, the 5th -17th (40-160 nm) high harmonic generation soft X-ray laser radiation has been obtained using linearly-polarized Ti: sapphire ultra-short laser pulses( central wavelength is 795 nm, pulse duration is 105 fs, repetition rate is 10 Hz and one pulse energy is 50 mj) . The change of high harmonic spectra intensities vs input laser power is especially observed. Because the incident laser intensities verge on or even exceed the saturation intensities in this experiment, the high-order harmonic intensities begin to decrease after increase with incident laser power increase, and the ion spectra of gas have been observed in the same time, which verify the conversion relationship between the high harmonic generation and ion spectra radiation.

The characteristics of L-band erbium doped fiber are investigated by numerical simulation and experiment. Gain spectrum is flat on optimum population inversion level (-40% ). High gain ( >36 dB) and low noise ?.4 dB) are achieved with dual-stage configuration. The flattened amplification bandwidth is 33.5 nm ( ± 0.5 dB) (1569 -1602.5 nm) without gain equalized filter (GEF).

By using the experiment results of R. H. Stolen's, a polynomial formula of the SRS Stokes spectrum is got by sampling and digitized fitting. Based on the formula, the Raman gain and noise figure properties of multi-wavelength pumping broadband Raman amplifier are obtained with considering the inter-amplifying between multi pumps. After numerical analyze, the characteristic curves of Raman gain and noise figure of different fibers G652, G653, G655 and LEAF are got.

The factors that restrict the isolation of an in-line dual stage optical isolator are analyzed using equivalent Jonse matrix. A new project for dual stage optical isolator is reported, which uses wedges of different angle for each stage. According to theoretical analysis, the isolation will be more than 58 dB. The result of volume production shows that the isolation of 80% products is more than 58 dB and the average isolation is 61 dB. So, this project can increase the isolation of a dual stage optical isolator largely.