In this paper, the principles of laser-materials interaction by UV laser have been reviewed. In addition, several successful applications by using pulsed UV laser including surface treatment, surface ablation as well as formation of nanometer particles have been presented.

Bridge-strip is a new type of electric firing device used in passivated electric detonators and related products. To cope with this tiny and delicate device a set of new techniques have been developed to solve the technical problems involved in the manufacture of bridge-strips. This research fully exploited laser advantages in welding, removal and resistance modifing. The photoetching mask is designed and ploted by computer. The bridge-strips are shaped and fabricated by photoetching. This shaping technique is faster, cheaper and more accurate than other techniques. For the sake of more convenient followed operations some strengthening wires are retained in the shaped bridge-strips and fmally removed using a laser beam after the strips are welded onto the electric detonators. The laser point welding between bridge-strips and lead wire is the most reliable mutual melting weld which guarantees the quality of the electric detonators. The high accurate resistance is realized by laser beam modification under the computer monitoring. This technique results in high uniformity of resistance which in turn guarantees the critical synchronism requirement of the electric detonators. This research comprehensively employed many functions of a laser beam in many technical steps. Some techniques presented in this paper are very creative and practical.

The use of lasers in microelectronics production for trimming, link cutting, ablating, drilling and general “micromachining” continues to grow. Several new technologies, such as alternative wavelength processing and shaped, uniform laser spots have produced better processing quality, higher reliability, and greater yields. This paper will review the latest technologies of laser micro-machining in microelectronics. Laser drilling for printed circuit board will be dressed in another paper.

In this paper two common 3D flexible processing methods using high power laser are introduced. One is high power YAG laser robot which use fiber to propagate laser beam. The robot holds laser head to move along spatial route on the surface of 3D part. The movement of robot influences laser processing result. Another is CO2 laser multi-axis system which uses mirrors to transfer laser beam. The quality of laser beam has great effect on propagation of laser beam and therefore influences laser processing quality. In these systems the programming is key to process 3D part. Currently the low efficient on-line teach-in programming is mainly used in these systems. Authors introduce their own developed high efficient off-line auto programming software for 3D laser processing---LaserCAM. The LaserCAM software in auto manufacture in China has been successfully applied.

In this paper, we discuss the effect on the average output power P by operation mode of the power supply. We experimentally showed that the initial charging would produce large interference, or even damage the switching component due to their nonzero on-set current property for high power output under CW current mode. A solution was put forward through the analyses.

The calibrating and controlling system of six degree-of-freedom (DOF) wind tunnel balance is introduced. The laser is used to test the six DOF displacements of the target. The system based on the VXIbus (the VMlEbus Extensions for Instrumentation) includes calibrating subsystem and controlling subsystem consisted of automatically loading subsystem, data gathering subsystem and automatically resetting subsystem. The paper introduces two aspects of the system, one is the construction of hardware aspect, and the other is the software for realizing the function of calibration and control. The constitution of resetting tactic is mainly introduced in detail because it is the core of this system. The construction of the VXIbus system is also included. The experiments show that all the functions can be finished perfectly. The resetting precisions of three linear DOF displacements can reach 6 ?m, the resetting precisions of three angle DOF displacements can reach 3". Not only the precision but also the efficiency and aptitude is improved greatly than before.

The diode laser transversal pump coupling technology is studied in the paper. A transversal pumped laser slab is excited by diodes coupled an optical system or the fiber cylindrical lens. A high efficiency can be reached by matching of the pump light distribution to the desired mode volume and almost complete by absorpting the pump light. We have achieved nearly 20 mrad divergence in the fast axis with the fiber cylindrical lens coupling of the diode laser bar .The beam quality of the emitter of the diode laser arrays in the two axis is very different. The radiation of the emitters is transformed by the lens duct. The experimental results show that the efficiency of the optical coupling is 85%,and an output beam with a symmetry profile has been achieved in the output face of the lens duct.

In this paper, the approximated expression of Fresnel Function is given, and that the Collins Integral for diffraction calculation can be expressed by Fresnel Function with sufficient accuracy is approved. Using this methods, in many cases the diffraction calculation could be simplified notably. Finally, the comparison of a diffraction example among the ordinary calculation, simplified calculation and experiment measurement is accomplished.

The radial sheering interference technique is used to measure the laser wave-front. In the system, the near field and far field wave-front of the laser beam of large caliber are measured respectively. Many evaluation parameters of the laser wave-front can be obtained, such as scattering angle, M2 of the laser beam, peak-to-peak-value (PPV), strehl value et. al. The interferogram is acquired by CCD camera, pretreated by high-capability computer and then used to reconstruct the wave surface. Mathematical principle to reconstruct the wave-front is expatiated in the paper. The interference system can be adjusted easily and operate real-time during the experiment.

In this paper, we propose laser-soldering method and use the process assisted with wire-mesh and soldering paste to weld the lateral electrode of piezoelectric ceramics transformer (PECT). The PECT were connected very well and were not affected much by heat. The process shows the good promise to the joint problems in multilayer heterogeneous lamination similarity to the PECT. Based on the above, our focus is on validating the finite element model, we build three-dimensional model of laser soldering temperature field in multilayer materials. Then, the reasonable simplification of heat source, materials parameters are put up in order to perform an efficient finite element analysis and the adaptive finite element technique is adopted. The temperature distribution characteristic in the laser soldering is acquired and verified by comparing experimental data. Although the finite element model contains numerous simplifications, the differences between experimental data and computed results are within 5%. The study shows that the adaptive finite element schemes give good agreement with the experimental data, which provides the theory reference for formulating correct process and optimizing joint properties. In addition, more exact material properties would improve the solution accuracy.

In this paper, we adopt YAG Q-switch double frequency solid state laser to drill hole in the water and air on three kinds of material: stainless steel, yellow copper and purple copper separately. The results show the differences in the water and air by comparing. At last, we qualitatively and quantitatively analyze the mechanism of interaction for laser processing in the water. Put forward the feasibility and superiority of the ultra short pulse laser processing underwater. The primary parameters of the laser: the width of pulse 10—100ns; wavelength 1.06m, 0.53?m; the energy of single pulse 0---100mJ; The work piece is placed underwater close to the water surface about 0. 1—2cm, focus distance lens f=60mm, the water is tap water, the thickness of work piece is less than 1mm. The laser with different laser parameters processes the work pieces. The results of the above experinlents indicate that the efficiency of drilling hole in the water is much higher than that in the air. And the quality and sharp of the hole processed is much better than in the air. The best power density of drilled hole in the by laser is mainly determined by material characteristics and the parameters of laser.

A composite coating was produced by powder feeding laser cladding. The detailed laser cladding experiments were conducted on a 3kW continuous wave CO2 laser. The diameter of the beam was 3mm, the scanning velocity was 3-10mm/s, and the powder feeding rate was 3.26g/min. The chemical compositions, microstructures and surface morphology of the cladded layer were analyzed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). The experimental results showed that a composites coating with TiC particles of various shapes and sizes embedded in nickel based alloy could be in-situ synthesized from the mixture of nickel based alloy powder, graphite enwrapped with nickel and titanium powders by powder feeding laser cladding. An excellent bonding between the coating and the carbon steel substrate was ensured by the strong metallurgical interface. The coating is uniform, continuous and free from cracks, however there existed some pores in coatings. The microstructure of the coating was mainly composed of ?-Ni dendrite, a small amount of CrB, TiB2, M23C6 and dispersed TiC particles. The maximum microhardness of the coating was about HV021 100 after laser surface remelting .4.5 times larger than that of the steel substrate.

A new technique about evaluation of the adhesion strength of the film on the metallic substrate is presented in this article and the mechanism ofdynamic decohesion induced by the directed pulsed laser irradition forming is investigated elementarily from the theory. The procedure of laser-induced decohesion of TiN layers on SUS3O4 stainless steel has been investigated by means of in-situ laser interference ultrasonic measurements. The experiments were carried out by using a ?=532nm, ?=8ns (FWHM ) laser pulses irradiating the TiN film on the metallic substrate with a series of energy densities. The damage degree and dynamical procedure have been studied as a function of the energy density of laser pulses. The results demonstrate that interferometer measurements are a suitable non- invasive in-situ diagnostics tool for the assessment of the damage of the films that additionally provide valuable information conceming the process dynamics. Such results indicate that the dynamic decohesion procedure of the films is the most likely mechanism responsible for the laser-induced spallation process. At last the adhesion of the films on the metallic substrate are evaluated quantitatively.

The theoretical and experimental study on the mechanism of plasma current during deep penetration laser welding is made in this paper. The plasma above the workpiece surface expands to nozzle, driven by the particle's consistency gradient, so an electric potential is formed between workpiece and nozzle due to the great difference in the diffusion velocities for ions and electrons. A kind of plasma-induced current can be obtained by circuiting the nozzle and workpiece, which current value is increased by adding a negative external voltage. As the external voltage increases, the plasma current increases until to a certain saturation value. As the workpiece-to-nozzle distance increases, the plasma current decreases. The decreasing rate becomes lower gradually until the plasma cunent becomes zero. Based on above analyzing, closed-loop control of workpiece-to-distance was realized based on the monotonous relationship between the plasma current and the distance. By applying a transversal magnetic field, the plasma above the keyhole can be somewhat eliminated, therefore the attenuation of plasma to the incident laser power can be lessen and the penetration depth can be increased.

In underwater laser beam welding, the shielding condition of the local dry cavity is one of the key factors affecting the weld quality. The variation in the weld bead formation and mechanical properties of the welded joint under various shielding conditions was investigated in this paper. The welding experiments were performed with Type3O4 stainless steel as base metal and Type-ULC308 electrode as the filler wire by using a 4kW Nd:YAG laser. The experimental results show that variation of gas flow speed has important influence on the weld bead formation. The bead width and reinforcement of the welds vary slightly under different gas flow speed, but the penetration depth is much lower under higher gas flow speed. Lower gas flow speed induces poor shielding conditions and increases the oxygen content of weld metal up to 800ppm, but higher gas flow speed that may form an excellent local dry cavity could prevent the weld metal being oxidized, with only about 8Oppm in oxygen content. Although the tensile strength of underwater laser welds keeps constant no matter how the shielding conditions are, the ductility of weld metal decreases largely for the weld obtained in poor shielding conditions comparing with that of good shielding conditions. The structure of the shielding nozzle has more important effect on the shielding condition, in specific, appropriately enlarging the outside diameter can considerably improve the stability of the local dry cavity.

A technique of laser welding glass GG17 (Pyrex) was developed to get clear photographs of the keyhole for quantitative study. The geometrical characteristics of the keyholes are experimentally examined. Based on the known keyhole geometry, the Fresnel absorption and the conduction and convection heat flux loss of the keyhole wall were calculated and compared. A concept of self-regulation of the front keyhole wall for getting energy balance is proposed. The major force that balances the surface tension is also discussed

The application oftailor welded blanks in the automobile industry has brought many challenges. The properties of tailor welded blanks by laser with the combinations of different steel types and thicknesses were analyzed in this paper. Results showed that the formability ofwelded blanks dropped compared to that ofthe base metal.

The fillet welding of the locating stands is just a typical three-dimensional laser welding processing. It was just like the fillet welding along the surface of a cylinder shape. Experiment results showed that a successful laser welding should be with some technique and skills. So a special clamp apparatus was made for fixing the parts and keeping them in correct position. The welding parameters were tested and determined in the study. For the main part of welding, 3000W laser power, 3m/mim welding rate, a angle of 15 degree between laser beam and vertical plane were used and had a full penetration of weld bead and a smooth bead surface. For the beginning and the ending part, the ramp function had to be used to overcome the weld defects of burning though and inadequate joint penetration. Also, the spot position at the beginning and the ending in the welding process should be adapted to make a good joint. In order to eliminate the influence of laser induced plasma that produced from the surface of galvanized sheet when it was heated by laser energy, a flow of argon gas with the rate of 10 1/mim as a side gas was employed. The experiment results indicated that the method of a teaching program was not enough for having a good welding quality because of the flutter phenomena by the non-uniform motion of machining head in the processing. Instead of it, the offline program was employed.

Laser beam welding of aluminum alloys is expected to offer both the technical and economical advantages. In most cases welding wire addition is necessary from the viewpoints to suppress hot cracks, improve mechanical properties of the weld as well as to reduce demands on the edge preparation, fit-up tolerance, and beam alignment. In practice, the filler wire could be added to the weld pool either in the leading or trailing direction. In this experimental work reported, the influence of the wire addition direction on the weld efficiency and process stability was investigated by using a 5kW CO2 laser to weld aluminum alloy 6009 with a plate thickness of 3mm. Beam-on-plate welds were made either in the autogeneous mode or with filler wire AISi12. Illuminated by a double frequency Nd:YAG laser, the weld pool dynamics and the wire melting process were observed applying a high speed camera. The experimental results demonstrate that welding with filler wire in the trailing direction is more efficient and stable than in the leading direction. High speed camera photographs show that the filler wire is mainly melted through weld pool heating and plasma heating in the former case and through direct laser irradiation and plasma heating in the later case. The weld pool is of vibration when welding in the autogeneous mode or with filler wire in the leading direction. However, the weld pool is much calmer when the wire is added in the trailing direction to the weld pool.

It is difficult to get a good welding spot and nearly impossible to weld very thin metal foil (several microns) onto a foreign metal workpiece over 1000 times larger in size. It is often the case when the foil has been vaporized and sputtered while the bigger piece to be welded is not heated In this paper we introduce the laser powder-covered welding technique which has a high success rate. The finished welding spot forms a "micro-rivet" and the laser point welding is the most reliable mutual melting weld. Studies indicate that the laser-cladding technique poses special technical requirements to the melting dynamics of the powder materials. Some useful conclusions are given. The requirements to the parameters of laser pulse are quite different from those of ordinary laser welding. The main points of the technique and the micro-analyses of the welding spot and other features are given. The technique presented is a novel method of welding between tiny piece and workpiece of different size and properties.

The interactive effects of aided cutting gases on CO2 TEMOO CW laser cutting of silicon steel sheet are studied. The qualitative analysis of the formation and elimination of the sinter is discussed.

High temperature alloy is a complex alloy with excellent high temperature strength, thermal stability and fatigue property, which can work in 600~1000C oxidizing condition. However, it has poor machinability. This article present experimental research of laser assisted cutting of GH4169 high temperature alloy. Comparative experimental research between conventional cutting and laser assisted cutting is done to detect the cutting force variation curve with cutting depth and cutting speed. The experiment results show that cutting forces in laser assisted cutting are evidently reduced by approximately 50%, and tool wear is reduced leading to longer tool life.

Laser Direct Materials Deposition(LDMD) is one of new emerging techniques of Rapid Manufacturing(RM) supported by CAD/CAM in recent years. Although LDMD shows great potential for many industrial applications, low powder efficiency about 30% due to canying gas increases cost of production and limits its application. In this paper, based on the Beer-Lambert law, the concentration ofpowder and the beam attenuation in co-axial feed powder laser cladding are researched. The relationship of the attenuation and laser cladding parameters, such as the laser power. a new co-axial powder feeder without carrying gas for LDMD was developed. Preliminary research on LDMD was achieved by non-carrying gas powder feeder.

Wear and corrosion resistant multi-functional Cr3Si-Cr2Ni3Si composite coatings were fabricated on substrate of an austenitic stainless steel 1Cr18Ni9Ti by laser cladding using different Cr-Si-Ni alloy powders. Microstructure, metallic dry sliding wear and electrochemical corrosion behaviors of the metal suicide matrix composite coatings were investigated as a function of the Cr3Si volume fraction. The laser clad composite coatings have a rapidly solidified microstructure consisting of Cr3Si primary dendrites and the interdendritic Cr2Ni3Si ternary metal silicide. The volume fraction of primary Cr3Si dendrites was shown to have a remarkable influence on wear and corrosion resistance of the laser clad composite coatings. The higher the volume fraction of Cr3Si, the higher he wear and corrosion resistance of the coatings.

Laser surface alloying and laser cladding were applied to enhance the tribological properties of titanium alloys. Wear resistant Cr7C3/NiCr, Ti5Si3/Ti and Ti5Si3/NiTi2 in-situ metal matrix and intermetallic matrix composite coatings were fabricated on substrate of titanium alloys by the laser surface processing processes. The room and elevated temperature tribological properties of the laser surface processed wear resistant composite coatings were evaluated as functions of coatings microstructural parameters and laser processing conditions. The responding wear mechanisms were discussed based on worn surface and debris morphologies observations. The potential applications of laser surface modifications of titanium alloys for the aerospace industries are prospected.

The laser controlled reactive synthesis method was developed to realize the synthesis and cladding of Ni3A1 intermetallic coating with expected thickness, width and low dilution on a steel substrate at a lower laser density of 3~3.5x 103W/cm2 by using the exothermic reaction. The clad is continuous and smooth, with few defects and excellent bonding with the steel substrate. Compared with the laser cladding of other alloys and ceramics without exothermic reaction, the cladding of intermetallic coating by laser controlled reactive synthesis can save a great amount of energy.

Since Fresnel diffraction integral can be expressed in convolution form, it can be calculated by Fast Fourier Transform (FFf) method. It is regarded that the FFT diffraction calculation can be achieved only in the region of Fresnel diffraction. But in fact, Kirchhoff's formula and Rayleigh-Sommerfeld's formulae can be also rewritten in convolution form so that the diffraction problems can be calculated very accurately with FFT method. In this paper we will deduce the convolutional form of the formulas of Kirchhoff's and Rayleigh-Sommerfeld's diffraction calculation. Finally, according to the principle of conversation of energy, we present a criterion to judge whether the numbers of sampling for FFT diffraction calculation is reasonable.

This paper presents a method of laser texturing, and a new type of regular surface roughness profile has been produced on the roll surface. A series of experiments have been developed to produce regular surface roughness profiles using a Nd:YAG laser. According to the analysis of the principle of laser texturing, the laser parameters are primely selected and matched. Consequently, the predesigned surface roughness profile and size have been successfully obtained. Furthermore, The measurement and analysis on the surface roughness hardness and abrasion resistance are carried on. The results show: the surface roughness has higher hardness rather than matrix, which adapted to the requirements of laser texturing. The surface roughness also has good abrasion resistance. In addition, the influence regulations between pulsed laser parameters and main profile parameters of roll surface have been investigated.

Graft copolymerization of acrylamide (AAm) onto poiy (ethylene terephthalate) using a XeC1 excimer laser was performed to improve surface hydrophilicity. Laser irradiation and graft polymerization were conducted simultaneously. The samples treated were characterized by contact angle measurements, XPS analysis, and microscopic observation. The surface hydrophilicity was improved significantly after AAm was grafted onto the film. The factors influencing the graft reaction were studied to understand the mechanism of laser-induced graft polymerization, deducing that a peroxide-initiated radical polymerization occurs during laser-induced graft polymerization. The N/C ratio of the surface changed from nil for untreated sample and irradiated but non-grafted sample to 0. 11 for grafted sample. The O/C ratio increased gradually in the order of untreated, irradiated but non-grafted and grafted under the chosen treatment condition. Carbon particles formed on the grafted surface as higher laser fluence was employed were observed.

A new method is used to measure optical opacity of exhaust gas from diesel engine. Measurements of opacity performed through opacimeter are compared with measurement of laser extinction obtainable near turbocompressor group of diesel engine, under stationary speed and load conditions. For this purpose an optical based on laserfotodetector is used. Laser beam goes through an optical window located along the exhaust pipe, after the interaction with diesel particulate, is detected by means of a silicon photodetector which supplies a photocurrent proportional to laser intensity. This kind of measurement allows, using Lambert-Beer's law, to compare the opacity values obtained with traditional opacimeter and those obtained with laser beam extinction. Three wavelengths are investigated, 635nm 785nm and 1523 nm, and the opacity values are plotted as a function of opacity given directly by the opacimeter. The empirical correlations obtained are exponential equations, which exhibit the following form: N1=K N^h, where Ni and N are respectively laser beam opacity and opacity given by opacimeter. K and h are factors depending on wavelength, particulate, engine and load conditions. These measurements are obtained in real time, data are acquired with a sample rate of 25 kHz, rather than the opacimeter which had a response time of about 0, 1 seconds while the opacimeter had a response time of about 0, 1 s. This real time opacity measurement methodology could be used, as starting point, to develop an on-board diagnostic device able to measure the exhaust opacity of diesel engine. The on-board diagnostic device for diesel engine will be obligatory from 2005.

To guarantee good quality of butt laser welding with filler wire, a sensor, that is used to detect gap width and seam tracking and a wire feeding system have been developed in this paper. The sensor contains a laser diode as assistant optical source and a photoelectric cell as receiving component. A step-motor drives the sensor transversally scanning above the work piece so as to detect the gap width as basis of adjusting welding parameters and the center position of the butt gap as benchmark of seam tracking. A computer calculates the required wire feeding speed and welding speed according to the gap width and transfers these values to wire feeding system and speed adjusting system. In the welding of 2mm-thick low carbon steel sheet, the wire feeding speed and welding speed are respectively changed according to gap width detection and weld bead appearance is analyzed. The results show that it is better to adjust wire feeding speed for narrower gap and adjust welding speed for wider gap. According to the detected signal of the sensor, the appearance quality of the total weld could be guaranteed by choosing wire feeding speed or welding speed as the control variable for different gap widths.

In this work, excimer laser (XeC1 308nm) is adopted to ablate the carbon target in order to deposit high quality nano-crystalline diamond films via electron assisted chemical vapor deposition (EACVD). In experiment, the temperature of substrate is about 300~450 degree Celsius, reacting gas is the mixture of methane and hydrogen in which volume ratio of methane to hydrogen is about 0.7 %, laser power density is 10-710b0 W/cm2. Experimental results show that the sharp peak in Raman spectra of sample films appears at 1332cm-1, which indicates crystalline diamond phase is formed in the samples. And the (lii) characteristic diffraction peak of diamond appears at 20=43.9° in X-ray diffraction spectra. Finally, the growth mechanism of diamond film at low temperature is discussed.

Amorphous diamond thin films have been deposited by pulsed excimer laser (XECL 308nm, 23ns, 300mj) and eched by O plasma. The films were studied with CCD microscopy, SEM, Raman spectroscopy. The films showed an increased surface particle density, a decreased optical transparency, as well as a higher sp3 content. The plasma particle have more higher energy and the duration is very short, so the plasma flux is intensive and this is suitable to deposit amorphous thin films and other metestable material. The role of O plasma have concluded, the characteristic of graphite to diamond have been discussed.

With Ni/Al cladding powders and coaxial powder-feeding mode, Ni35A12OFe intermetallic coating was successfully prepared by laser cladding. The optimizing principles of processing parameters of laser cladding were proposed. The shaping and microstructure of laser cladding coating were analyzed. The experimental results indicated that lower laser power; slower scanning velocity and larger beam diameter could ensure excellent shaping and metallurgical quality. Under the optimum processing, laser cladding Ni35Al2OFe intermetallic coating was free of porosity and cracks and a fully metallurgical adhesion was achieved between the coating and the substrate. The microstructure was composed of refine ?-NiAl intermetallic phase as the base and a few dispersed ? phase particles precipitated along crystal grain boundaries and within the grains. The formation of ?-NiAl phase dissolved with Fe, precipitation of ductile ? phase and refined crystal grains were favorable of not only higher strength but also enough ductility and toughness of laser cladding coating.

NiTi shape memory alloy thin film has been proved to be the best micro actuation mechanism due to the largest displacement and the highest actuation force as compared with other mechanisms. The combination of laser and traditional MEMS techniques might provide a better and cheaper solution for the fabrication of micro devices. In this paper, we present some preliminary results of cutting and annealing of NiTi shape memory alloy thin films using different types of lasers.

Laser drilling has emerged in the last five years as the most widely accepted method of creating microvias in high-density electronic interconnect and chip packaging devices. Most commercially available laser drilling tools are currently based on one of two laser types: far-IR CO2 lasers and UV solid-state lasers at 355 nm. While CO2 lasers are recognized for their high average power and drilling throughput, UV lasers are known for high precision material removal and their ability to drill the smallest vias, with diameters down to about 25 –30 micron now achievable in production. This paper presents an overview of techniques for drilling microvias with the lasers.

Metal matrix composites (MMCs) layers reinforced by in situ carbide particles were formed by laser cladding using preplaced (2.4%Zr+1.2%Ti+15%WC)/FeCSiB alloy powders on a medium carbon steel matrix. The microstructures of cladded layers, composition and distribution of in situ particles in the cladded layers were observed with optical microscopy (NEOPHOT), scanning electron microscopy (OPTION CSM-950, KYKY2000) and metallographic microstructure computer analysis system. HX-200 micro-Vickers was used to examine the cladded layer microhardness. The microstructure characteristics of MMCs layers are typical hypoeutectic which y austenite dendrites distributed on the FeCSiB quaternary eutectic substrate. The energy dispersive spectroscopy (EDS) analysis shows the reinforcements are in situ synthesis carbides which compositions consist of main transition elements Zr, Ti, w and carbon. The compound carbide particles distributed within dendrite and interdendritic regions with 3.6— 5.8% volume fractions. The martensite transformation went with the rapid cooling processes also. The MMCs layers are dense and free of cracks with a good metallurgical bonding between the layer and matrix. The microhardness values across layer cross section vary between HV0.2 8OO—HV0.2 1000.

Fabrication of an object image inside glass material can be realized by laser direct writing with a programmable motion system. In the focus depth direction, namely Z-direction, the really formed dimension will have some difference from the distance moved by the motion system because of light refraction effect, which causes a deformation of the image from the object. Therefore, it is necessary to modify the object dimension in Z-direction in the executive program. The required amount of the dimension modification depends on the refractive index of the glass and the numerical aperture of the focus lens used. A formula for the dependence of the amount of dimension modification on the refractive index and the numerical aperture is presented based on Snell’s law. Experimental results show that the image created inside glass really reflects the dimension feature of the object with a programming dimension modification in Z-direction in terms of the formula presented. A comparison of a sphere and a cub images created inside glass with the dimension modification with that without the modification is produced for making sure the importance of the dimension modification.

In this paper, we will describe a new method to fabricate optical diffractive gratings on glass surface with direct CW CO2 laser irradiation. A laser beam with linear polarization was focused and scanned on a glass substrate. The interaction of the beam with the material irradiated results in a periodic ridge structure formation on the substrate under a well-controlled laser irradiation dose. Using multi-path scanning method, with a suitable overlap, diffractive grating with large area can be achieved. In this experiment, laser irradiation dose was 50 J/cm2, laser scanning speed was 0.2 mm/s, the diameter of focused beam was 30 ?m, and the grating period was about 8 ?m.

UV-laser induced changes on surface structure and properties of Poly(ethylene terephthalate) (PET) fabric were discussed. Scanning electron microscope (SEM) observation revealed the morphological modification of PET fabrics with the ablation of 308nm excimer laser. The contact angle measurement and vertical drop test were used to find out the difference in the wetting property of the untreated and laser ablated PET fabric. Extra carboxylic radicals and increased amorphous part on the surface of the laser-ablated fabric were estimated by the attenuated total reflectance Fourier-transform infrared spectrum (ATR FT-IR) analysis. Dyeing property of the PET fabric was changed evidently by laser irradiation.

A new technique about microfabrication and Rapid Prototyping named Laser-induced Chemical Deposition based Rapid Prototyping (LCD&RP) is proposed. Laser-induced chemical deposition can further be sub-divided as vapor, solid and liquid. The Laser-induced Chemical Vapor Deposition based Rapid Prototyping (LCVD&RP) process has been used in for several years, and it has faced some critical problems in deposition rate and facility cost. To overcome these shortcomings and explore new chemical deposition methods and materials, Laser-induced Chemical Liquid Deposition based Rapid Prototyping (LCLD&RP) is based on the following experimental fact: when a laser beam expanded passes through a reflector and a lens, then the beam is focused on a substrate immerging in cold (room temperature) liquid reactant, which makes the areal substrate heated and takes place chemical reaction to deposit a solid material. By controlling the motion of laser beam and process parameters, a desired three-dimensional microstructure of deposited material can be formed through layer-by-layer scanning. According to the initial experimental results, the feasibility of LCLD&RP is discussed and demonstrated.

In this paper two common 3D flexible processing methods using high power laser are introduced. One is high power YAG laser robot which use fiber to propagate laser beam. The robot holds laser head to move along spatial route on the surface of 3D part. The movement of robot influences laser processing result. Another is CO2 laser multi-axis system which uses mirrors to transfer laser beam. The quality of laser beam has great effect on propagation of laser beam and therefore influences laser processing quality. In these systems the programming is key to process 3D part. Currently the low efficient on-line teach-in programming is mainly used in these systems. Authors introduce their own developed high efficient off-line auto programming software for 3D laser processing---LaserCAM. The LaserCAM software in auto manufacture in China has been successfully applied.

The action of slot pipe is much importance in petroleum exploitation. Despite the method to defend sand contain variety in course of artesian well and over well, It is still the most in common method to use slot pipe to over well and defend the sand. Use laser process slot pipe is function superiority and price cheap. Not only is this type of slot pipe relatively inexpensive but also durable, easily installed, and efficiently developed. So many oil-fields are positive to use it.

Pulsed lasers can generate ultrasound from stresses due to rapid thermal expansion. In this low power thermoelastic regime the material is not damaged. This paper concentrates on epoxy resins and aims to relate the observed amplitude of the longitudinal wave to the optical absorption depth of the epoxy. The ultrasound is generated using a high power pulsed laser and the absolute amplitude of the ultrasound is measured with a Michelson interferometer. In the thermoelastic regime, the laser beam is focused onto the sample, causing rapid expansion in times that are comparable to the rise time of the laser pulse. In metals, the laser radiation is absorbed in the thin electromagnetic skin depth but in non-metals the phenomenon is dominated by the optical absorption depth. The latter can vary from a few microns to several millimetres for materials such as epoxy resins. As a consequence, a bigger volume of the material is affected, the temperature rise is less and the amplitude of the longitudinal wave is greater. This condition is referred to as “a buried thermoelastic source”. Two lasers were used in this study: a TEA CO2 and a XeCl excimer laser. The results are compared with optical transmission measurements.

Gradient titanium- carbon films were grown by hybrid deposition arrangement combining laser deposition and DC magnetron sputtering. Laser was used for deposition of carbon films and magnetron simultaneously sputtered Ti on the same substrate. Depth profile of carbon and nitrogen species, films adhesion and microhardness are studied in connection with deposition conditions.

Er- doped YAG and YAP layers were grown by nanosecond (20 ns) and subpicosecond (450 fs) KrF laser ablation under a wide set of deposition conditions. Results of characterization of films crystallinity and luminescence are presented and discussed. Films grown in ns regime were almost amorphous for substrate temperature to Ts ~ 1000 oC, while films grown in subps regime were partly crystalline, even at low Ts. Film crystallinity was also studied after annealing of amorphous layers under vacuum with CO2 and KrF excimer lasers. Luminescence corresponding to Er+3 ions was observed for all samples.

Patterning of vanadium pentoxide (V2O5) visible light absorbing amorphous films was attempted using a SHG beam (? =532nm) of Q-switched Nd:YAG laser. Amorphous V205 films (350nm thick) were deposited on an optical glass slide substrate 1.4mm thick by normal resistance-heating vacuum evaporation. A sheet beam ofthe pulse laser with an output power of 1 .4J/pulse was used, having a pulse width of iOns, and a calculated laser fluence of 46. 1J/cm2. The beam with pulse repetition of 10Hz was irradiated in air at room-temperature on the film sample that moved to the direction normal to that of the sheet beam with a speed of 5mm/s. Both direct and indirect beam irradiation through the glass substrate produced a regular stripe pattern due to film removal. Characterization of removed and non-removed film portions in a laser track reveals a molecular and/or nanocluster sublimation of amorphous V2o5 caused by laser irradiation. This patterning has an advantage of short-time film processing.

Finite element simulation of measuring the film-matrix interface strength was the most concern of this paper. Instead of in previously reported measurements the experimentally measured free surface velocity, enegry and pessure of laser pulse in the present article allowed definition of the loading conditions in the numerical model. On the basis of theory for laser hypervelocity impact dynamics, experiment was predigested into two relative but non-coupling processes, transient thermal analysis and transient dynamics analysis. In the former, the procedure employed for the solution of thermal equation was the generalized trapezoidal rule. In the latter, the Crank-Nicholson difference time integration method was employed for the solution of wave equation. Based on the experiments, a model for laser-induced film spallation was proposed to study the propagation of stress wave and to evaluate the spall resistance of sputtered films. The analyzed result showed the dynamic adhesive strength of the TiN coating on the 304 stainless steel substrates is 183.64Mpa. It is theoretically proved that the interface stress triggering the film pry-offs was not single superimposition of pressure pulse and reflected tensile pulse, but multi-superimposition of pressure and tensile pulses.

Laser nanocrystallization of the amorphous silicon (a-Si) deposited on Si (100) or glass substrate with and without metal catalyst is investigated. SEM results indicate that the surface morphology is presented as many nanograins are studded on the former's surface after crystallization, whereas, only with plenty of spots scattering on the latter's surface. HRTEM studies show that the nanograins are Si nanocrystallites and the spots are actually crystalline Si nanowires. Further analysis on the crystallizing process of the two kinds of annealing has been performed to explain the morphology difference oftwo kinds ofannealing techniques.

In this paper, the results of experiment that using YAG laser and CO2 laser to weld 6009 Aluminum alloys are investigated. The experimental results show that the weld depth and area using CO2 laser are both larger than using YAG laser under the condition of the same power and the same welding speed. The reasons are analyzed through the aspects of absorption, beam quality, focal depth and plasma. The absorption of materials to YAG laser is higher than that of CO2 laser, but the CO2 laser has high beam quality and focal depth. On the other hand, laser induced plasma strengthen the absorption of materials, so using CO2 laser can get good weld quality. These two kinds of laser processing system are compared at last in this paper.

In this paper, a finite element model has been developed to numerically calculate the temperature field and velocity field of fluid in laser material remelting process. The effects of fluid flow on the temperature field and the shape of laser pool are investigated carefully and presented graphically to display the subtle changes of temperature field. The numerical results show that (1) in general, there are two opposite vortices in the pool and one is greater than other due to the translation of workpiece; (2) the mainly driven force in the pool is the thermocapillary force compared with the nature convection; (3) the shapes of the molten pools, due to the convection of flow, become flat compared with that without the effect of fluid flow.

The diode laser transversal pump coupling technology is studied in the paper. A transversal pumped laser slab is excited by diodes coupled an optical system or the fiber cylindrical lens. A high efficiency can be reached by matching of the pump light distribution to the desired mode volume and almost complete by absorpting the pump light. We have achieved nearly 20 mrad divergence in the fast axis with the fiber cylindrical lens coupling of the diode laser bar .The beam quality of the emitter of the diode laser arrays in the two axis is very different. The radiation of the emitters is transformed by the lens duct. The experimental results show that the efficiency of the optical coupling is 85%,and an output beam with a symmetry profile has been achieved in the output face of the lens duct.

When laser acts on an optical film, the film will be damaged even unable to work. In this article, a kind of measurement system of optical film's damage threshold is introduced, and it is applied to the experimental research of the reflection coating. The wavelengths of reflection and transmission extremums are determined, according to their spectral characteristic curve. The absorption of the film and the capacity of the film's bearing laser damage can be decided according to the displacement ?? of relative extremum. We can determine whether the film reaches the technical requirements by this means through the measurement of the sample film. Thus we can avoid the multi-repairs of the formal workpiece. There is a fine practical value of this method.

This paper reports on the characterization and analysis of drilling with a novel high power acousto-optical Q-switch pulse laser. The laser is a flash-lamp pumped pulse Nd:YAG laser which can be used in the free running mode with repetition rates up to 10Hz. Additionally it is possible to modulate these pulses using acousto-optical modulator which enables a burst between 1 and 10 Q-switch pulses with a duration of typically 200ns during each flash-lamp pulse. The repetition rate of the burst is 5kHz-50kHz, the pulse energy is 30-8OmJ, and the peak power is more than 400kW with a beam parameter product of about 5mm mrad. The drilling process and the combination of different repetition rate of the bursts enables drilling 2.5mmthick Cu and Ni-alloy for 0.2mm micro-hole. The recast layer is nanower. Oxidation of the walls of the hole is prevented by a high-pressure inert gas.

By studying the basic principle of C02.laser processing system, energy-adjust method, concentration parameter method and dither method which was used to process computer image are introduced to laser processing system to process gray image. Some new soft modules for these methods are developed which have been used in laser processing system for processing different material such as wood, marble, plastic. The data of the three processing time and the image quality are also given. By comparing the laboratory data, the conclusion is drawn out that the image quality can be improved with concentration parameter method and the processing time is shorted greatly at the same quality of image for different material by using dither method. This result can be popularized in the other laser processing system.

A method and the device for obtaining a high peak output power laser with the ns-regime pulse are presented. A Q-switched laser with a novel configuration and a special Q-switched method for the resonator energy storage are proposed. We put a piece of glass with a small hole and special parameters into the resonator which is composed of two totally reflective mirrors in order to obtain the coupling output and realize the step alternation of Q value from "1" to "0" in the resonator. The photons emit out ofthe resonator after a transmission back and forth so as that the output laser pulses with a few ns lifetime are obtained. Simultaneously, the output laser distributes with a circle-axisymmetic pattern and demonstrates good space-transmission and focusing characteristics.

The laser hardening of gear is a new surface hardening technology. According to the characteristics of the broad-beam laser hardening, the techniques have been put forward to obtain the uniform hardened case alone the surface of gear. The question that temper of the first hardened flank has been improved evidently. The measurement results show that the deformation of laser-hardened gear is very small, which does not influence the grade of gear. The results of contact fatigue comparison tests show that the contact fatigue limit stress of laser hardened gear is a little less than that of carburized gear, with an amplitude lower than 9%. The spread of contact fatigue life of laser hardened gear is lower than that of carburized gear.

The mechanism of laser cleaning rust deposit on the steel surface was studied experimentally. Especially, the parameters and mechanism of cleaning rust deposit from steel surface with pulsed YAG laser was studied in detail. The practical application of laser cleaning in maintenance was discussed in this paper. A pulsed YAG laser and a continued CO2 laser was used to do some experiment comparatively. The results demonstrated that the effect of pulsed YAG laser is better than continued CO2 laser. The pulsed YAG laser can accomplish complete cleaning by regulating parameters of laser, however, the continued CO2 laser can not. There are cleaning threshold and damage threshold in laser cleaning. Between the initial cleaning threshold and complete cleaning threshold, cleaning percentage of the surface increases with the increasing of laser fluence and pulse number, but does not depend on repetition rate. The mechanism of laser cleaning rust deposit with pulsed YAG laser is suggested: the vibration of deep rust deposit and thermal shock action induced by laser-supported detonation (LSD) to make rust particles sputter is primary, however, the thermal effect of laser irradiation is secondary.

PCI bus has become the primary bus standard of PC. It is widely used in numerical-control-system, such as 3D laser formation, high speed laser marking, laser cut atid so on. This article analyze several technique problems and puts forward solving strategy. A graphic processing card for high speed laser marking machine has been designed, which can raised the efficiency by 25%~3O‰.

The current method of continuous welding for cubic battery is centrality-rotating lateral welding. By this method, the rotation axis is the geometrical center of the cubic. The laser beam moves to the battery edge in processing, and the battery keeps fixed. Contrast to this method, the rotation of ours is the four edges of the baftery, and the laser beam doesn't move. Certainly, our method simplify the laser mechanism. We have already applied for patent.

In this paper, four kinds of pretreatment methods for laser cladding ceramic coatings were given. And characteristics of two kinds of cladding methods were compared and evaluated. It was found that laser ion composing cladding is an ideal method for obtaining dense ceramic coatings.

Using laser quenching technology can improve the hardness, the strength and the abrasive resistance of metal material. Heat treatment of automobile cylinder block markedly improves its quality, increases its service life, and greatly reduces the cost. This article mainly discusses the control circuit of the laser quenching machine based on phase control IC TC787. Experiment shows that the project is successfully fulfill the need of the engineering practice.

Laser direct forming experiments were carried out systematically with 316L stainless steel and nickel-base alloy to investigate the technical characterizations deeply and some metal components were fabricated. It is found that, the height of single cladding layer, which was affected by almost all the processing parameters and was quite hard to be precisely controlled, was very important to laser direct forming for not only the accuracy of vertical direction but also the fabrication stability. The variation of the width of single clad, which was mainly affected by laser power, spot diameter and scanning velocity, was similar to that in laser surface melting. The surface quality was another important characterization for laser direct forming and was remarkably affected by oxidation and powder attachment. In order to improve the surface quality, the flow flux ofshielding gas should not less than 10l/mm.

Physical vapor deposition in horizontal systems has been used to grow crystal thin-film of organic semiconductor pentacene. Using 10~30mg of starting material, 20~30mm sized crystals thin-film, suitable for characterization measurements or device fabricated, have been grown. And we have measured the sample of pentacene crystal thin-film using TEM. X-ray diffraction electron microscopy. The results indicated that the crystal lattice array order.