We reported here a novel technique for laser high speed drillings on Printed Circuit Boards (PCBs). A CNC solid laser based system is developed to drill through and blind vias as an alternative to mechanical drilling. The system employs an Acousto-Optic Q-switched Nd:YAG laser, a computer control system and an X-Y moving table which can handle up to 400 X 400 mm PCB. With a special designed cavity the laser system works in a pulsed operation in order to generate pulses with width down to 0.5 microseconds and maximum peak power over 10 kW at 10 k repetition rate. Delivered by an improved optical beam transforming system, the focused laser beam can drill holes including blind vias on PCBs with diameter in the range of 0.1 - 0.4 mm and at up to 300 - 500 vias per second (depending on the construction of PCBs). By means of a CNC X-Y moving system, laser pulses with pulse-to-pulse superior repeatability can be fired at desired location on a PCBs with high accuracy. This alternative technology for drilling through or blind vias on PCBs or PWBs (printed wiring boards) will obviously enhance the capability to printed boards manufacturing.

Amorphous Si₃N₄, Si/N/C and crystalline SiC nano- powders, 5 - 50 nm in mean diameter, with yields of 250 g/h were synthesized via laser induced gas phase reactions flow cost hexamethyldisilazane (HMDS) and NH₃ (or H₂). Reaction flame temperatures, which were controlled by the total gas flow rate, greatly influenced powder composition and crystallinity. Amorphous Si₃N₄ powders (96 wt%) were obtained at 1000 degrees Celsius flow HMDS + NH₃; (beta) -SiC (93 wt%) was formed at 1600 degrees Celsius with H₂. Amorphous Si/N/C powders with various N/C ratios (0.1 - 6) were synthesized at various temperatures. The main impurities in the powders were the organo-ligands such as NH_x and CH_x (X equals 1 - 3) whose existence also resulted in a strong surface absorption of oxygen. Commercial production technologies of above mentioned powders were also stated.

Carbon nitride films were synthesized by active atomic nitrogen beams intersecting pulsed laser plumes at the substrates without heating. The properties of the films were studied by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Raman spectroscopy. AES and XPS analysis show that the as- deposited carbon nitride films are mainly composed of [N] and [C], and the composition ratios ([N]/[C]) increase as the pulsed laser repetition rate and energy. XRD results show that several diffraction peaks attributed to (beta) -C₃N₄ phase were identified. Raman spectra show that several prominent bands related to C-N bondings could be observed.

The iron atomic is evaporated directly by means of a big power laser. Blow N2 is the vertical direction of laser, iron atomic steam will move along with the flow. When the steam comes into contact with condenser, it will cooled fast and crystallized. Measure by means of the scanning electron microscope and electron probe microanalysis shows the grain size of particle is 50 nm or so and the particle is Fe₂O₃.

This paper, TiN nanometer crystalloid material is made by means of the high power laser vaporization-solidification method, which the equipment, technology process and experimental results are introduced. At same time, the mechanism study of TiN nanometer crystalloid material is carried out by this method. When Ti powder is radiated by a high power laser and N₂ is insufflated, Ti is heated and evaporated quickly, come into being vapor of Ti-molecule and Ti-ion in space of tank. At high temperature, new TiN molecule are formed after Ti-ion collide whit N-ion and then become into big molecule groups. The results of analyzing by SEM proved that the particle size of TiN crystalloid is about 100 nm. The results show that relative symmetrical nanometer crystalloid material can be obtained by means of the vaporization-solidification method.

A technique of compounding green compacts with gradient composite which combines the processes of laser sintering was applied to produce Cu/Fe based gradient materials, the microstructure and properties of the materials were studied the results show that fruitful and complex phases were formed during laser sintering and good metallurgical bonding and properties were obtained.

A novel method, pulsed-laser induced reaction at liquid-solid interface (PLIIR), which is used to synthesize nano- crystallite, is developed. Nano-crystalline diamond with hexagonal lattice and cubic lattice and carbon nitride, which phases include (alpha) -C₃N₄, graphite-C₃N₄, (beta) -C₃N₄ and cubic-C₃N₄, are synthesized by this approach. Transmission electron microscopy (TEM), high resolution electron microscopy (HREM) and other methods are used to characterize the structures of the nano-crystallite. Graphite-C₃N₄ and cubic-C₃N₄ are reported for the first time in experiment.

In this paper, it is reported that diamond films have been synthesized by the Laser Assisted Chemical Vapor Deposition (LACVD) method using the mixture of acetone and hydrogen. The XeCl excimer laser with a wavelength of 308 nm has been utilized as photo-dissociation energy source for carbohydrate, and H₂ has been predissociated by hot filament at the temperature of 2000 degrees Celsius. P-type silicone was employed as substrate, which temperature was controlled at about 800 degrees Celsius. The specimens deposited by the method of LACVD were analyzed and evaluated by Raman spectroscopy and scanning electronics microscopy (SEM) accordingly. A character peak of diamond films at 1332 cm^-1 can be observed from Raman spectrum. The experimental result have shown that a high-quality diamond film can be obtained.

The YBa₂Cu₃O_7-x (YBCO) superconducting thin films with Tc(R equals 0) of 84 K and Jc of 2 X 10³ A/cm² at 77 K, on polycrystalline Ni-based alloys with buffer layers of Yttria-Stabilized-Zirconia (YSZ), have been prepared in situ by excimer laser. The orientation of laser-deposited YSZ buffer layers on NiCr alloys can be improved by choosing the suitable preparing parameters. The microstructure of YBCO thin films, investigated with a scanning tunneling microscopy, shows that the spiral growth structure may be an important characteristic of the high quality YBCO superconducting thin films.

We report a new method of preparing patterned nano-crystalline Si (nc-Si) by pulsed laser interference crystallization of a- Si:H thin films. A KrF excimer pulsed laser with wavelength 248 nm and pulse duration 30 ns is employed as a coherent ultra-violet beam source; a one-/two-dimensional (1D/2D) silica phase-shifting grating is used to form a high-contrast laser interference pattern behind it. During the laser treatment, the a-Si:H film is placed behind near contact with the phase grating. A transient thermal 1D/2D grid is then directly formed on the sample, leading to the local crystallization of the a-Si:H films and forming of nano- crystalline Si. The crystallinity of nc-Si films is verified by Raman scattering. Atomic force microscopy clearly shows a morphology of 1D/2D regular sub-micron patterns formed by locally crystallized stripes/dots, which are composed of densely gathered crystallites with a lateral size of approximately 50 - 100 nm and a height of approximately 10 - 20 nm. The interfaces between the crystallized and the amorphous zones are abrupt. Transmission electron micropsy demonstrates a lateral size distribution of nc-Si within the crystallized zones. This new approach has a potential application in the nano-electronics and nano-optoelectronics.

Based on the newly developed binary optics, a new kind of optics device used for laser beam mode transforming has been developed. This kind of binary optics device is worked with the principle of optical diffraction. It can be used to transform very efficiently the beam mode of high power laser of long wavelength. Using such a binary optics device of GaAs, a circle beam of high power CO₂ laser can be transformed into a line-shaped narrow beam with uniform power distribution. Using this device to do the treatments of laser hardening, alloying and cladding, the treating efficiency can be greatly increased. A very uniform strengthening layer in hardening depth, hardness and microstructure can be obtained. The tempering effect, which will occur in the overlapped region when treating a large area with the common overlapping process, can be avoided.

This paper studies the quenching time of the laser beam with the different power density distribution, and achieves its relation with the spot size and the scanning speed of the laser beam. In conclusion, the conditions and the experiment tests of estimating the temperature field with the assumption of a semi-infinite medium are presented.

Laser Shock Processing (LSP) is a new technique for strengthening the metals. This paper investigates the effects of LSP on the fatigue crack growth (FCG) behavior of 2024-T62 aluminum alloy. The FCG tests results show that the fatigue crack growth rates (FCGRs) at a given stress intensity have been reduced by over one order of magnitude.

The method of handling boundary problems by 'image heat source' is enlarged in studying of laser heat treatment and it is possible to carry out the semi-analytic calculation about transient temperature field of non-cross-cut workpiece.

Annealed high speed steels for making tools such as W6Mo5Cr4V2, W9Mo3Cr4V1, W18Cr4V were treated with 5 kw continuous adjusting CO₂ laser. By controlling laser- processing parameters, we achieved variable datum about the depth and hardness of the surface hardening layer of the samples. The relationship between the depth of hardening layer and laser processing parameters were studied with microhardness meter, scanning electronic microscope. The results showed that the sample's micro organization was markedly fined, dislocation and twin crystal subconstruction was strikingly increased, its hardness was obviously higher than that of general heat treatment.

According to phase transformation theory of steel, thermal elastoplastic theory and laser phase transformation characteristic, conditions of austenitic transformation in course of heating and martensitic transformation during cooling, extensive equation of martensitic transformation quantity and nonlinear equations of temperature field and stress field are put forward in this paper. Also effect of applied stress on temperature field, stress field and phase transformation course is studied.

The paper introduces the laser surface hardening processing with 5 KW CNC CO₂ laser for Cam Shaft made of 45 steel. The results show that spiral scanning matching with adaptable technological parameters and water cooling achieve remarkable hardenability with less deformation, which satisfy the requirements demanded by manufacturer, simplify the manufacturing technology. The advantage of laser surface hardening is very remarkable.

In this paper, according to the theories of phase transformation, thermal elastoplastic and characteristics of laser quenching, after analyzing the process of isothermal phase transformation and variable temperature phase transformation, heating austenite transformation and cooling martensite phase transformation, and considering the properties of CCT curve, a mathematical model of martensite phase transformation has been obtained and nonlinear heat conduction equation considering the effect of the thermal physical property coefficients and phase transformation have been given, which reflects the hybrid method of F.E.M. (Finite Element Method) and F.D.M. (Finite Differential Method), the transient temperature field during laser quenching on plates and distribution of phase transformation organization have been calculated and analyzed. When calculating the temperature, distribution of austenite and martensite organization and laser hardening region can be calculated too. Comparing the results of calculation with that of experiment, we can make conclusion that our theoretic analysis is valuable for practice and physical coefficients during calculation is significant to the study of laser quenching technology and theory about predicting the material properties.

A sensing and control system of process quality in CO2 laser deep penetration welding has been developed, including plasma photo sensor (PS) and plasma charge sensor (PCS), signal processing circuit, personal computer, and optimization and control software. By using the information of plasma radiation and plasma charge, the focusing lens is adjusted to the optimum focal point position (at which the maximum penetration can be achieved) and closed-loop control is realized to assure the focal point position and penetration depth constant. In laser welding of the workpiece aslant placed with larger angle, the variation of focal point position is less than 0.2 mm and the fluctuation of penetration depth is less than 0.05 mm. The control system has been preliminarily applied in laser precision welding of 2.5 m long zircaloy fuel channel used in nuclear heat-supply reactor.

The definition of the rapid prototyping is given in this paper. Various RP processes, which build the prototypes with 2.5 or 3 dimensional layers, are introduced. The relative techniques of RP and the differences between RP technique and CNC manufacturing are analyzed. The paper discusses the RP's applied fields and methods and presents the RP development in the world. According to the idea that requirements determine the developing, the RP's tendency is discussed.

A new method of laser scribing on polycrystalline diamond film is proposed in the paper, the requirements of laser machine output, the calculation of technological parameters and the best combination of voltage, pulse duration and feed rate are discussed. Finally, the paper gives the laser scribing experimental results.

Laser marking of stainless steel with a Q-switched Nd:YAG laser has been studied in this paper. In experiments, three vital factors of a Q-switched Nd:YAG laser were chosen as control factors: electric current used for generating laser beam, pulse frequency and traverse speed of laser beam. Optical microscope and scanning electron microscope, surface profile instrument were used to measure effect of control factors on mark depth and width. An image-analysis system with a frame-grabber card and a charged-couple-device (CCD) was used to test mark contrast. The relationship between control factors and mark quality characteristics has been obtained.

A mechanical chopper Q-switched CO₂ pulse laser with high peak power, short pulse duration, high pulse repetition rate and moderate average power is developed. Using this laser, a cutting process of high cutting speed and multi-pass is proposed for cutting hard and brittle materials such as engineering ceramics. Crack-free and fine cut is obtained in cutting Si₃N₄ ceramics.

Laser cutting technology has been applied to ordinary alloy steel circular sawblade, but it is very rarely used in quenched HSTS disk-shape milling-cutters due to the material particularity. In this paper, the authors systematically explain the advantages of this new technique, respecting the optimum design of HSTS disk-shape milling-cutter, the specific characteristics of laser forming cutting once for all, the technology testing, the analysis of structural performance of tooth and the small batch production for verifying. The article displays its advantages completely as follows: The design for a perfect tooth profile is not bound to the ordinary machining methods; The special laser technique does not lower the hardness on the tooth nose so that this process and needs no follow-up operational sequences, ensures the excellent dynamic-balance performance and operation properties, and prolongs the tools' service time; The new technique also has advantages of high efficiency and good economics. Therefore, this special laser cutting method, an integration of intensified heat-treatment and laser forming cutting once for all technology, will be regarded as a reform in HSTS tools Manufacturing field.

This paper is based on theory of extended Landau phase transformation, consider achievement of A. F. Devenshire and F. Falk et al, and combines with characteristics of martensitic transformation, the research of effect of applied stress on martensitic transformation during course of laser phase transformation hardening, has been in progress, and a functional analysis expression of Gibbs free energy, which applies to describe the concrete problem, has put forward and discussed. In the paper, the various law of laser phase transformation hardening layer of 45# steel under action of applied stress is studied. The conclusion shows that theoretical analysis are in accord with experimental results.

When measuring implements are marked by laser, two points must be studied, and they are calibration tails' precision and its quality. In this paper, what we are interested in is how to get qualified calibration tails. Calibration tails' quality is determined by three aspects: laser beam, optical system and workpiece. We conducted research into their effects on line quality with a 90 w Q-switch YAG laser marking system made by Rofin-Sinar. Laser beam has three factors that have effects on mark results: laser power (lamp current), Q-switch frequency and beam mode. Optical system refers to scanners and lens. Scanning velocity is one of the two parameters of scanners, and the other one is delay time for beam OFF. De-focus value is the parameter of focus lens. All these parameters' effects on calibration tails' quality are discussed one by one in the paper, and the author analyzed the effect of the surface condition of workpiece at last.

In this paper a brief description is given to introduce the activities of the manufacturing technology using the synchrotron radiation light source in the National Synchrotron Radiation Laboratory (NSRL). The light source in NSRL is a dedicated synchrotron radiation facility in China. Five beamlines and corresponding experimental stations, including soft x-ray lithography, have been constructed. The main experimental results obtained from the soft x-ray lithography station are reported. We have fabricated some devices using the synchrotron radiation lithography, for example, the high electron mobility transistor, high T_c superconductor infrared detector-array, diffraction grating, and micro condenser zone plate. A simple method for the achievement of synchrotron radiation x-ray lithography mask will also be presented. The LIGA (German abbreviation for: Lithograpie, Galvanoforming, and Abforming) technique has been developed in NSRL. It is the most promising technique for the fabrication of three-dimensional microstructures. We are successful in making several microdevices by deep x-ray lithography and microelectroforming, such as microgearwheel, micro acceleration sensor.

According to the power transmission on the high power CO₂ laser welding, a new 2-point-1-line heat transfer model about laser beam welding is put forward. In this paper, an empiric formula is also brought forward which is proved to be consistent to the result of the actual welding.

In order to process complex curve with high-speed and stringent smoothness in laser-processing, the B-splines has been applied. This parametric matrix equation of the third order B-splines curve can easily be realized in engineering. Moreover, any segment of the third order B-splines is only determined by 4 continuous control points while any control point affects 4 continuous segments.

In this paper, the temperature field influencing by applied stress during laser phase transformation hardening is analyzed by finite element method, according to the principle of heat conduction, phase transformation and thermal elasto-plastic mechanics. The function and variation theorem of the tmperature field influencing by applied stress during laser phase transformation hardening are established. Meanwhile, its FEM basic equations with triangle element are presented.

According to the quasi-neutrality equation, the law of partial pressure, pressure equation, Saha equation and the principle of superposition on plasma refractive index, the Ar, He plasma's electron density, atom density, ion density and the variation of refractive index with changing of temperature are calculated when the pressure is 1,3,5,7 atm. respectively. Moreover it is analyzed that Ar, He plasma act on CO₂ laser beam welding from the point of view that plasma and laser affect each other.

The method adding electromagnetic field during laser heat treatment is a new heat treatment method that expend application expansion of laser heat treatment. In this paper, based on thermal non-elasticity, principle of metal phase transformation, deformation thermodynamics and theory of electromagnetic field and using the internal variable method of continuous medium mechanics, the heat conduction equation with magnetic-field phase transformation during laser heat treatment has been inferred. The equation and its theoretical method is the basis to study the theory and experiment of laser magnetic quenching and also the basis to study further on the material structure distribution and properties. And also by means of the equation, has the numerical analysis on temperature field in the course of laser magnetic quenching been in progress.

The factor M² is a new parameter to describe the laser beam quality, it can characterize the propagation of the fundamental and higher-order mode beam quantitatively. An automatic measurement system has been developed which is capable of measuring the laser beam quality factor M². In the paper, the concept and the measurements of the factor M² are mentioned, the measurement results and tolerance limits are given.

Design and fabrication of a weld protection drag-cover has been discussed in the paper as using high-power CO₂ laser to weld Ti6A14V in various thickness. Argon was used to protect the weld and its nearby region from contamination from hydrogen, oxygen and nitrogen as their temperature were higher than 300 degrees Celsius. The protection effect has been proven to be good, since the weld surface was smooth, the obverse side appeared silvery white, and the reverse side appeared light-yellow.

Laser Direct Writing System (LDWS) is a key equipment for manufacturing the binary optical masks. A polar coordinate laser direct writing system was developed and the maximum mask size which can be made is 4 inches. One of its main properties, namely lithography resolution, was analyzed based on the optical intensity distribution in the photoresist. Normally, 0.86 micrometer linewidth on masks can be achieved. In some special case, a super resolution of 0.5 micrometer linewidth can also be obtained, and it will require a more rigorous exposure latitude. The exposure experiment results on LDWS showed good agreement with the theoretical calculations. The approach by using the optical intensity distribution in the photoresist to predict the relations between linewidths and exposure latitude gives out a simple and clear image about the effects of photoresist on lithographic linewidths.

A flexible focus variable beam expander system with adaptive optics is designed. In this system the adaptive mirror's focus is adjusted by regulating the pressure of mirror's cooling water. The change of mirror's curvature and focus is calculated with elasticity mechanics and the conception of wavefront aberration is cited to study the difference between ideal curvature and realistic one. The results of experiments is corresponding to the theoretical data.

In this article, the mechanism of the LICVD process preparing SiO₂ powder is analyzed. We discuss a lot of parameters such as the laser power density, spot size, the mass flowing of reactant, the ration of all reactants, the torch size, etc. After series of experiments, we successfully gained the silica powder which diameter is about 100 nm by using vertical equipment.

A novel method for laser beam smoothing by rotating random phase plate is presented in this paper. A random phase plate for CO₂ laser was made, and satisfactory results were obtained. The experimental results coincide very well with theoretical analysis.

A Nd:YAG slab is partially end-pumped by a diode laser stack with three diode laser bars. The pumped volume has a rectangular cross section. A hybrid resonator which is stable in the plane of small dimension and off-axis unstable in the plane of large dimension of the gain cross section was used, in order to obtain highly efficient laser operation at diffraction limited beam quality. In this paper, the laser design and experimental results are reported. 31.2 W output power was obtained with M² equals 1.3 in the unstable plane and M² equals 1.7 in the stable plane. 38.6 W output power was obtained with M² equals 1.7 in the unstable plane and M² equals 3.9 in the stable plane.

In the paper, based on outlining the making principle of the metal material super-plasticity and some making methods, a new making technology is proposed on the super-plasticity-shaping aided by laser in the vacuum negative pressure condition. The paper discusses the laser beams coupling characters in making process and the super-plasticity-shaping technology of the alloy materials, gives the shaping conditions of the typical materials for the vacuum negative pressure case.

Laser-produced plasma is an attractive table-top x-ray source for many applications, such as microscopy and lithography. Soft x-ray conversion efficiency depends strongly on the laser parameters in use and the produced debris with metal target is an intolerable side-effect in some applications. In this paper, we will optimize laser parameters for the yield of soft x-ray, give the experimental results of low debris solid state CO₂ target.

In this paper the liquid thermal diffusivity measurement through pulsed photothermal deflection in a modified collinear configuration is presented and discussed. The condition that the pulsed beam is regarded as in the form of a Dirac delta function here is given out. Comparison between theory and experiment is also shown.

In the rapid prototyping technology with laser as an energy source, the method of laser spot scan is used usually. The laser beam is focused to a spot on the working plane through a lens. The scanners work in two ways, one is rotating mirror scan, other is guideway scan. Based on the position of the scanners, the rotating mirror scan can work in pre and behind- objective scan respectively. In this paper, a new laser scan method of alterable thread length is proposed, after analyzing the inherent weak points of the laser spot scan. The design principles of beam deformation unit (changing the laser beam into a thread of light) and the altering length unit are introduced.

LIGA process technique is a three-dimensional micromachining technology which is applied to fabricate 3D micromechanical parts. Because the LIGA process requires synchrotron radiation for deep-etch X-ray lithography, few can utilized this technique. In order to solve this problem, many efforts have been made in the world. In Shanghai Institute of Optics and Fine Mechanics, an evolutionary process named Laser LIGA process is being developed. The recent progresses in the development of this process is reported. The mechanism of UV laser ablation, the design of experiment apparatus and the experiment procedures for fabrication of micromechanical parts are introduced. In the end of the paper the experiment result is presented, which is a (phi) 500 micrometer micro-gear of 220 micrometer depth.

In this paper, the effects of some factors, including interval of multi-pair electrodes, interval of pulsed discharge time, pulse signal and power quality of resistance-high-voltage control circuit, laser induced medium diffusion, arc discharge and so on, upon the output stability of the multi-electrode- pairs-pulsed laser are analyzed comprehensively. And a reasonable method of improving the output stability of the multi-electrode-pair-pulsed laser is developed. This method is confirmed by experiments.

According to the more complete diffraction theory, a series of new beams was invented both outside and inside laser cavity by using (lambda) /2 phase plate. A new beam with equivalent beam quality factor M_e² less than 1 is achieved on ten-watt CO₂ laser and on hundred-Watt and thousand-Watt CO₂ laser with axial express flux. It may be named as the first kind of new beam laser. From the point of view of practical applications, we designed and produced a new structure of laser cavity whose output mirror was a special mirror with step reflectivity. We have realized 1000 W new beam on CO₂ laser with transverse express flux, which is close to the fundamental mode. It may be named as the second kind new laser beam. Its structure is simpler than others, but it brings excellent results.

The CPOB (computer processing organic-glass burning-mark) method is used to measure TEM of High Power CO₂ laser, the three-dimensional display of the TEM profile. So the center of light spot, the diameter of light spot, the distribution of power density along the line and the distribution of average power density on a circles area of different radius can be determined. This method is of great importance in the material laser machining field.

Dry and steam laser cleaning was investigated both theoretically and experimentally. The experimental results show that cleaning efficiency increases with increasing laser fluence or decreasing laser wavelength. The cleaning thresholds exist both dry and steam laser cleaning. A cleaning model was established for laser-induced removal of particles from solid surfaces by taking adhesion force, such as Van der Waals force and capillary force, and cleaning force into account. Laser cleaning forces are induced by fast thermal expansion of particles and/or solid surfaces irradiated by laser for dry laser cleaning and evaporating liquid film heated by laser irradiation for steam laser cleaning, respectively. It was found that laser cleaning forces increase with an increase of laser fluence. At the same laser fluence, cleaning forces increase with decreasing laser wavelength. Cleaning thresholds can be obtained by comparing cleaning force and adhesion force. The experimental results are good consistent with the theoretical analysis.

Laser cleaning of disk surfaces was investigated both experimentally and theoretically. It was found that laser cleaning efficiency increases with increasing laser fluence and pulse number. The optimal cleaning conditions can be selected between the two boundaries of damage thresholds and critical cleaning thresholds (100% cleaning). A cleaning model was established for laser-induced removal of particles from substrate surfaces by taking Van der Waals force and cleaning force into account. The theoretical analysis shows that the cleaning force (per unit area) increases with increasing laser fluence, which leads to a higher cleaning efficiency for removing particles from disk surfaces. The experimental results can be explained by the model and simulation.

KrF-laser ablation of poly(methylmethacrylate) (PMMA) doped with benzil was studied from the viewpoint of nonlinear absorption of the PMMA film during the laser irradiation. After measuring the relationship between the transmission and incident laser intensity, we developed a novel method to obtain absorption coefficient depending on laser intensity. Using the nonlinear absorption coefficient of PMMA doped with benzil, we succeeded in fitting the relationship of etch depth and laser intensity. The dependence of concentration of benzil in PMMA film and the difference between benzil and pyrene were also discussed.

Boron-Carbon-Nitrogen thin films were deposited by laser ablation of B₄C target under nitrogen ion-beam bombardment. The deposited thin films were set for X-ray photoelectron spectroscopy (XPS) and ellipsometry measurements. The results showed that in the ternary thin films, boron, carbon and nitrogen species were chemically bound to each other instead of simle mixtures. The B-C bonds were broken by the introduced energetic nitrogen ions and, subsequently, C-N and B-N bonds can be formed. The ellipsometry measurement gave the optical band gap of 0.48 eV for the thin films deposited under 50 eV nitrogen ion beam bombardment. According to the analyses, the nitrogen ion beam energy should be lower than 100 eV in most cases.

Carbon nitride thin films were deposited on silicon wafers by pulsed KrF Excimer (wavelength 248 nm, duration 23 ns) ablation of graphite. Different excimer fluences and pressures of the nitrogen atmosphere were used in order to achieve a high nitrogen content in the deposited thin films. In another case, a Kaufmann-type ion source was used to produce a nitrogen ion beam to assist the deposition process. X-ray photoelectron spectroscopes (XPS) were used to identify the binding structure and the content of the nitrogen species in the deposited thin films. The thin films deposited in nitrogen atmosphere had N/C ratio of 0.42, whilst those deposited with assistance of nitrogen ion beam bombardment had N/C equals 0.43. The dependence of the optical parameters of the deposited films, the refractive n and extinction coefficient k, were studied by Ellipsometry.

Pulsed laser deposition (PLD) of titanium thin films on p-type (100) silicon substrates by KrF excimer laser ablation is investigated by changing the deposition parameters during the thin film deposition. The influence of target-to-substrate distance, laser fluence and substrate temperature is studied for high quality titanium thin films. Energy dispersive x-ray (EDX) spectrum analysis of the thin films is also carried out. The surface texture of the titanium target after the laser irradiation is studied by scanning electron microscope (SEM) images. It is found that the most important deposition parameters which affect the thin film quality are target-to- substrate distance and laser fluence. A suitable target-to- substrate distance and laser fluence can minimize the deposition of micro-sized particulates on the thin films. By optimizing the deposition parameters, the less particulate, higher deposition rate and more uniform titanium thin films are grown on the silicon substrates for wafer metallization.

Materials having the skutterudites structure such as CoSb₃, IrSb₃ and RuPdSb₆ have been investigated for their magnetic and thermoelectric properties in the bulk form. Nevertheless, in this form they are difficult to synthesize, and their fabrication requires a long process, involving successive cycles of high pressure melting and grinding. Moreover, this process produces only polycrystalline materials with a small grain size that prevent their practical use for thermoelectric devices. Excimer laser sputtering enables us to sputter and vaporize of a large variety of materials, and as for skutterudites, allowed us the choice of sputtering a target with the complex final composition of the film or the choice of sputtering targets of each elements of the final composition of the film in sequence. By tuning other deposition parameters such as substrate temperature and background pressure it is also possible to adjust the final quality of the deposited thin films. We introduce our experiments using a Lambda-Physics LP240i ArF excimer laser (160 mJ/pulse, 5 Hz). The composition of deposits is studied as a function of deposition parameters. The crystalline structure of deposits is investigated by XRD and compared to previous reports for bulk materials. Thermoelectric properties are also to be discussed.

Under ultra high vacuum, (beta) -FeSi₂ thin films were formed by laser ablation method using poly crystal (beta) - FeSi₂ as target material that was prepared by horizontal gradient freeze method. In order to compare the physical properties of thin films prepared by laser ablation with those of bulk crystal, (beta) -FeSi₂ single crystal was prepared by chemical vapor transport method. The (beta) -FeSi₂ plate-like and needle-like crystals were formed at 7 mg and 1.0 g of iodine quantity, respectively. To check a crystal symmetry and orientation, Laue transmission patterns were taken. Anisotropic Raman signals were observed from polarized Raman scattering measurements. Further, electron spin resonance measurement was carried out to examine the residual impurities and to determine g values. From (beta) -FeSi₂ films during laser ablation growth, streaky signals were obtained in the RHEED observation. Highly oriented (202)/(220) (beta) -FeSi₂ films were predominantly identified in XRD measurements. Raman scattering and optical absorption measurements for these layers revealed that the grown samples are nearly epitaxially-like and have approximately 0.85 eV as its direct optical band-gap.

A photochemical reaction method in a liquid phase using an argon-fluoride (ArF) excimer laser has been developed to precipitate carbon with nanometer-sized structures in zeolites. This method has the advantages of low-damage and simple process compared with conventional gas phase reaction process. Carbon precipitated in zeolites using this method has shown a broad absorption band located at 3.0 eV which is lower photon energy than that of benzene, Furthermore, a visible photoluminescence (PL) band with a peak around 2.0 eV has been observed at room temperature. These results indicate that benzene ring has been decomposed by the ArF excimer laser and nanometer-sized carbon comparable to fullerene molecules has been precipitated in/on the zeolites.

A new ceramic coating technique using a CO₂ laser has been developed. A high power density laser beam passes near the substrate. Coating materials are supplied by an extra-high accuracy powder supply device and pass across the laser beam. The coating materials are melted in the laser beam and deposited on the substrate surface. A YSZ (Yttria Stabilized Zirconia) layer and a LaCoO₃ layer are made for high temperature solid oxide fuel cells. The crystal structures of the coated layers are the same as that of the original coating materials. Superconducting BPSCCO ceramic films are also made with this process. The films show super-conductivity with T_c at 81 K. The J_c of the specimen is 440 A/cm² at 77 K. We can easily handle and arrange not only metal but also refractory materials. By adopting a multi-axis robot and a surface treatment laser technique, the laser spraying method described here makes it possible to produce highly functional and three dimensional parts of devices directly from raw powder materials. Thus the proposed method will open the path to an unexplored field of key production technology.

CuInSe₂ (CIS) is expected to be applicable to the solar cell materials. We prepared CIS thin films by pulsed laser ablation technique using CIS targets and investigated the influence of the laser energy density, laser repetition frequency and substrate temperature on the fabrication of CIS thin films. The characterization of CIS thin films were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), electron probe micro-analyzer (EPMA). Further, as-deposited CIS thin films were annealed in Se vapor in order to improve the crystallinity of CIS thin films. We obtained CIS single phase thin films deposited at laser repetition frequency of 10 Hz and deposition time of 120 min. It confirmed that crystallinity in CIS thin films is improved by increasing substrate temperature. In particular, CIS thin film deposited at substrate temperature of 600 degrees Celsius showed a good crystallinity and smooth surface morphology and few droplets. From the results of optical absorption spectra of CIS thin film deposited at 600 degrees Celsius, it showed high absorption coefficient of the order of 10⁴ to approximately 10⁵ cm^-1 in the wide range of wavelength and determined optical band gap Eg equals 1.0 eV. It is found that crystallinity and chemical composition of CIS thin films improved by annealing in Se vapor. CIS thin films was constructed with column-like grains which were grown by annealing.

We report on an electroluminescent (EL) diode with novel active layers of silicon (Si) nanocrystallites. The Si nanocrystallite active layer was prepared by pulsed laser ablation (PLA) in an ambient of reduced pressure inert gas. The structure of the EL diodes was semitransparent platinum (Pt) electrode/Si nanocrystallite layer/p-type Si/Pt electrode. We have observed visible spectra of not only photoluminescence (PL) around 2.07 eV, but also EL around 1.66 eV at room temperature. The EL diodes initially showed a rectifying behavior which degraded after current stresses. Furthermore, we have found that the EL diodes showed strong nonlinear dependence of EL intensity on current density. A possible mechanism of the EL diode emission is impact ionization by minority hot carriers injected through the surface oxide layers and the successive radiative recombination.

TiN thin films were deposited on glass substrates by KrF excimer laser ablation of Ti in very broad N₂ pressure range with different target-substrate distance at room temperature. The as-deposited TiN thin films were analyzed by x-ray diffraction and transmission electron microscopy. It is found that normally the as-deposited thin films are the mixture of TiN and Ti and the ratio of TiN to Ti of the as- deposited thin film depends on both the N₂ pressure and the target-substrate distance. The high purity TiN thin films can be obtained only in a very narrow deposition parameter range. A compound parameter (the product of the N₂ pressure and the target-substrate distance) is proposed to optimize deposition for high purity TiN thin films and the possible mechanism is also discussed. It is also revealed that the as-deposited TiN thin films were polycrystalline with an average grain size about 20 nm.

Hardening and microstructure of aluminum metal surface with CO₂ laser alloying process have been investigated. Mixtures of Al, Ti powder and organic flux used as alloying elements was painted onto the metal surface and irradiated by one step specimen move technique. To address uniformly distribution of the fine dendrite structure and eliminating of many pores occurred within alloyed layer, new complex technique of laser irradiation with ultrasonic radiation methods was attempted together to modify them. Evaluations of the microstructure within the alloyed surface, hardness and tribological properties have been conducted. The alloyed surface consisted of dendrite structures of the Ti₃Al and Al-Ti solid solution. The Ti₃Al dendrite crystallized leads to adhere effectively to the aluminum phase, and the surface approaches Hv equals 600 kg/mm² in hardness. As substantial tribological property, the wear resistance of the alloyed specimen to cast iron was around less 1/7 time than that with comparing of Al metal.

Laser buffing of nickel-phosphorous (NiP) surface after mechanic texturing has been investigated. A KrF excimer laser ((lambda) equals 248 nm, (tau) equals 23 ns) was employed in the experiment as an irradiation source. The sample is a mechanic- textured hard disk. Atomic force microscope (AFM) was used to analyze the surface morphologies before and after laser irradiation. The results show that the surface was buffed in micro-scale after laser irradiation. The surface root mean square roughness and average roughness decreased. One- dimensional thermal conduction model was used to simulate the temperature distribution in the irradiated region. The mechanisms of laser buffing are proposed based on the investigation. It is more likely due to selectively localized melting during laser irradiation.

Laser texturing on NiP substrate is a promising method for high-density hard disk manufacturing. The tribology property at the head-disk interface depends on the morphology of laser textured bumps. A model has been made to find the relationship of bump morphology on the hard disk, the parameters employed in laser texturing and the properties of the substrate material. We can find type of bumps through numerical calculation of the model. The model involves two steps. The temperature distribution is calculated first by solving heat conduction equation. The surface structure formation is studied at the second step. The surface structure is formed by thermocapillary force. The model treats the melting substrate as a kind of viscous liquid. The final shape of the substrate surface depends on the movement of the liquid. The viscosity of the liquid plays an important role because it increases sharply when the liquid cools down. This will stop the further movement of the melted surface. Our model can not only help to understand the mechanism of pulse laser microprocessing, but also has applications in laser texturing, which can increase the storage density of the hard disk. By comparison of the calculation results and experimental results, appropriate parameters can be chosen for manufacturing purpose.

Pulsed green laser with 532 nm wavelength and 270 ns pulse duration was first used to produce a textured zone on a Ni-P disk substrate. Combining a so-called tip-writing method, typical small bumps of interest with bump diameter around 3 micrometer and with bump height about 10 - 20 nm were successfully created. A dependence of bump height on bump diameter was discussed under the case of tip-writing. And the changes of bump shapes with laser pulse energy were studied and bumps with sunflower-like shape were observed under low laser pulse energy.

Excimer laser-induced surface structures at the interfaces of Silicon dioxide/Silicon have been investigated experimentally. It is found that a stable, fine and homogeneous ripple structure is preferentially generated under a comparatively larger laser beam. The ripple periodicity seems to have no angular dependence and is enhanced with the increased laser pulses only before the irradiation of certain pulse numbers. The initial substrate temperature also represents an important parameter which can be used to control the interface ripple structures. The correlation between the threshold laser pulse for the ripple formation and laser fluence, the threshold laser pulse and the oxide thickness is studied as well. This study will be helpful in understanding the physics of laser- induced ripple formation by some key parameters, and hence be useful in controlling the ripple structures within the range required for the laser texturing for the high density magnetic recording media.

Precision Nd:YAG laser cladding was investigated to achieve laser clads with specific pattern and roughness on very thin metal sheets (0.1 - 0.15 mm) to meet industrial requirements. Characterization of pulsed laser cladding on thin sheet substrate, side nozzle, coaxial nozzle and development, high speed video visualization of powder flow for both nozzles, microstructure evolution, vacuum clamping, chiller cooling were presented. Sound laser clad pattern with height/width ration 0.88 or 0.50 and identical quality was obtained. The present work demonstrates that precision laser cladding and/or direct laser manufacturing on thin sheet is another attracting field on laser cladding.

Interactions of polymer surfaces with excimer laser irradiation provide new techniques for surface modification of polymer materials. One is physical and chemical changes on polymer surface by laser ablation, and the other is a chemical change by laser-induced photochemical reactions. This paper focused on a morphological change on polymer films after laser ablation and a chemical change of fluorocarbon polymer film. This paper shows that the morphological change in laser- induced periodic surface structures in of interest is not only basic science but also industrial applications. In addition, we report that surface modification of fluorocarbon polymer has provided a new processing to fabricate printed wiring boards for high-frequency electronics.

The thermal radiation from a weld pool is focused on an aperture and the transmitted thermal radiation is monitored at two wavelengths with high-speed single-element detectors. Due to the chromatic aberration introduced in the focusing optics, the transmittance curve of thermal radiation varies by the wavelength. Likewise, the detector field of view varies by the wavelength. Owing to this difference in the transmittance and in the field of view, the local variation in a weld pool can be monitored by processing the two spectroscopic signals from two detectors. In this paper, the algorithms to monitor the weld pool size and the focus shift are presented and the performances of weld pool size monitoring and auto-focus control are shown for a pulsed Nd:YAG laser welding. The size variation monitoring has been applied to the weld depth and weld defects monitoring. The effects of laser power change and weld defects on the weld pool size variation are also shown.

Pulsed laser deposition of Ti thin films for wafer metallization is investigated by optical spectroscopy. Ti plasma emission spectra are captured to study plasma generation, expansion and recombination during the thin film deposition. Ti plasma has a very rich emission spectrum in a region from 180 to 650 nm. There exist two phases of plasma characterization. The first phase is plasma ionization by the laser heating near the target surface. Gate delay is up to 200 ns at this phase. There is continuum emission resulted from free-free and free-bound transitions. The second phase is plasma recombination in its propagation process. The dependence of Ti spectral line intensities on gate delay, laser fluence and chamber pressure is also studied. The intensities decrease with gate delay, but increase with laser fluence and tend to saturate at laser fluence higher than 4.6 J/cm² due to the plasma shielding effect. The spectral line intensities do not vary with chamber pressure up to 0.1 Torr. At the higher pressure, plasma is confined by air molecules and the intensities increase greatly with the chamber pressure. Plasma electron density is calculated as the functions of gate delay, laser fluence and chamber pressure from the Stark broadening of the spectral lines. Electron temperature is also estimated as 1.5 eV from the local thermodynamic equilibrium (LTE) assumption. Fast time-resolved photography is applied to analyze the plasma plume evolution in its propagation. The plasma expands outwards and flies from target to substrate at speeds up to 10⁶ cm/s.

Recent advances in the performance and the price of high power diode lasers and their beam shaping techniques are enabling to build up diode laser systems for pumping of solid state lasers and direct industrial applications. In this paper some recent development in high power diode laser system designs and their applications will be presented.

Recently, the development of multi-kW all solid-state lasers for industrial applications has been evaluated for the energy saving characteristics. We report the laser oscillator using the LD pumped slab Nd:YAG producing the highest efficiency on the cooling condition of room temperature. The two-side pumping is generally used for realizing symmetrically distributed excitation and temperature in the crystal. However, there exist two demerits coming from the useless LD pump light which is not absorbed in the slab. The first demerit is the fact that this light does not contribute to laser oscillation and the second one that the same light degrades the performances of LDs locating on the opposite side. We have eliminated these demerits by employing the one- side pumping method in which LDs are located on one side of the slab and a highly reflecting mirror is located on the other side. Based on this concept, the LD pumped slab Nd:YAG laser has been developed using a 6 X 25 X 206 mm³ slab crystal. The average output power of 1109 W and the peak output power of 4900 W have been obtained with the optical efficiency of 40.6% and the electrical efficiency of 15.3% on the cooling condition of 299 K.

The optical contact method has been developed to obtain a large volume slab Nd:YAG crystal for achieving a multi-kW output power. The bonded crystal with the dimension of 6 X 25 X 402 mm³ (tip to tip) is mounted in a single laser head and is pumped with four krypton arc lamps. In continuous wave (CW) operation, the maximum output power of 2480 W, the overall efficiency (eta) _E-O of 4.0% and the slope efficiency of 5.5% have been obtained. A beam quality which is defined as the product of full divergence angle and diameter of the beam waist is better than 10 mm (DOT) mrad and 80 mm (DOT) mrad in the directions of the thickness and the width of the slab, respectively. The output laser beam was transmitted through a GI type 600 micrometer-core optical fiber completely. This configuration has realized a simple resonator laser producing high processing performance.

Laser-induced removal of organic contaminants, such as grease and wax, on Cr substrate surfaces was studied. The laser cleaning efficiency was analyzed by an optical microscope and an Auger Electron Spectroscopy (AES). It was found that the contaminants in the irradiated area can be effectively removed by pulsed laser irradiation and cleaning efficiency can be reached to 80% above under a certain cleaning condition without damage. The damage threshold of Cr substrates was obtained by numerical simulation, which is in good consistency with the experimental threshold.

A holographic stroboscopic method is useful especially for large vibration amplitude analyses but a vibration mode cannot be judged by this method. In this paper it is shown that a vibration mode can be analyzed by using two stroboscopic holographic interferograms synchronized with a slight difference. Experimental results of a cantilever vibration measurement show us the proposed method is useful.

In the late of this century the great success of VSIC impacts into almost every fields of our social. Following this idea people starts to integrate microsensor microprocessor and microactuators into a small space to forming a Micro Electro and Mechanical System. Such small robot parts are applied to including satellites, computer communication, medical, chemical, biological and environment and so on research fields. The development of MEMS would strongly influence industrial revolution in the next century. LIGA technology including X-ray deep etching lithography; electroplating and plastic molding developed by Karlsruhe Nuclear Research Center, Germany since the beginning of 1980. Its advantages are: it could make three-dimensional microstructures with lateral dimension in several micron range and thickness of several hundred microns with sub-micron precision. In principle all kinds of materials such as polymer, metal and ceramic could be used as microcomponents and could be mass- produced by plastic molding to a commercially available fabrication. LIGA process has become one of the most promising Microfabrication technologies for producing micromechanical, microfluid and micro-optical elements. It opens an additional field in the microstructure market.