Abstract: A method for producing a pattern of depressions in the friction surface of a friction component for a frictionally operating device, preferably a multiplate clutch or multiplate brake. After the preparation of the friction component, the pattern of depressions is produced by nontraditional material removal, removal of material preferably being accomplished in a contactless manner, particularly preferably with the aid of a laser beam.

Abstract: Apparatus and methods for drilling holes in a material with a laser are disclosed. An apparatus for drilling holes in a material with a laser includes a first steering element, a second steering element, and a lens. The first steering element is positioned to steer a beam from the laser. The second steering element is positioned to steer the beam from the first steering element. The lens focuses the beam from the second steering element. The first and second steering elements are configured to move with respect to the beam. Moving the first and second steering elements changes an angle of the beam where it contacts the material. The apparatus is operable to drill holes having no taper or reverse taper.

Abstract: The system comprises a buckling arm robot with a robot frame (1) and an articulated arm (2) and a fiber optic cable (5) which is connected to one end of the articulated arm (2) and through which a laser beam (11) with a beam axis (10) is coupled into the articulated arm (2) in the direction of a first axis of the articulated arm (2). The fiber optic cable (5) is indirectly connected to the stationary end of the articulated arm (2) via an alignment unit (6) which comprises a collimating lens system (13) and at least two alignment mirrors (12.1, 12.2), each of which mirrors can swivel about at least one axis of rotation and move along at least one axis of translation, with the axes of rotation and the axes of translation being disposed at right angles to each other so that the beam axis (10) of the laser beam (11) can be made to coincide with the optical axis (4).

Abstract: A laser processing apparatus including a pulsed laser oscillator for oscillating a pulsed laser beam, a focusing objective lens for focusing the pulsed laser beam, and a varifocal lens provided between the pulsed laser oscillator and the focusing objective lens. The varifocal lens has a piezoelectric device to change its focal length according to the period of radio-frequency waves produced by the piezoelectric device. A repetition frequency adjusting unit is connected to the pulsed laser oscillator, and a radio-frequency current frequency adjusting unit is connected to the piezoelectric device. The laser processing apparatus further includes a controller for controlling the repetition frequency adjusting unit and the radio-frequency current frequency adjusting unit so as to produce a phase difference between the repetition frequency of the pulsed laser beam and the frequency of the radio-frequency current to be applied to the piezoelectric device of the varifocal lens.

Abstract: A system for welding a tub of a railroad tank car includes a manipulator boom adapted to move with respect to the interior surface of the tank shell. A hybrid laser arc welding head mounted to the manipulator. A supplemental gas metal arc welding head includes dual wires of welding material and is mounted to the manipulator adjacent to the hybrid laser arc welding head. An inductive heating coil is mounted adjacent to the supplemental gas metal arc welding head. The hybrid laser arc welding head welds a seam of the railroad tank car shell with the supplemental gas metal arc welding head following to generally complete filling of a resulting weld joint with welding metal. The supplemental gas metal arc welding head is followed with the inductive heating coil to provide heat to normalize the resulting weld joint.

Abstract: A laser machining device 1 includes a laser light source 10, a spatial light modulator 20, a controller 22, a converging optical system 30, and a shielding member 40. The phase-modulating spatial light modulator 20 inputs a laser beam outputted from the laser light source 10, displays a hologram modulating a phase of the laser beam at each of a plurality of pixels arranged two-dimensionally, and outputs the phase-modulated laser beam. The controller 22 causes the spatial light modulator 20 to display a plurality of holograms sequentially, lets the converging optical system 30 converge the laser beam outputted from the spatial light modulator 20 at converging positions having a fixed number of M, selectively places N converging positions out of the M converging positions into a machining region 91, and machines an object to be machined 90.

Abstract: A laser processing system provides a burst of ultrafast laser pulses having a selectively shaped burst envelope. A burst pulse laser includes a high repetition rate ultrafast laser to deliver a pulse train with each pulse in the train having an independently controlled amplitude. The respective amplitudes of each ultrafast pulse in a group define a “burst envelope.” In addition to independently controlling the amplitude of each ultrafast pulse within the burst envelope, the system may also provide selective control of spacing between each ultrafast pulse and/or the overall temporal width of the burst envelope. Thus, the system provides selective shaping of the burst envelope for particular laser processing applications.

Abstract: The present invention relates to an ultrashort pulse laser processing device. The ultrashort pulse laser includes a stage a transfer member, a front confocal microscope, a front laser generating unit, and a front highpowered lens. A sample is provided on the stage to be processed, the transfer member transfers the stage, and the front confocal microscope is provided above the stage. The front laser generating unit is provided between the front confocal microscope and the stage to generate an ultrashort pulse laser, and the front high-powered lens focuses the laser provided from the front laser generating unit.

Abstract: A device for laser welding of a workpiece includes a laser treatment head, a receiver carrying the laser treatment head and displaceable along a linear treatment zone, and a support configured to be temporarily fixable to the workpiece.

Abstract: Apparatuses for fabricating micro patterns using a laser diode array and methods for fabricating micro patterns are presented. The apparatus includes a laser diode array having at least one laser diode wherein light emitted from each laser diode is focused by a convex lens onto a second material layer attached to a first material layer. At least one driving shaft drives motion of the first and the second material layers. An adjustment means is used for adjusting the gap and pitch between adjacent laser diodes.

Abstract: An apparatus processes a surface of an inhabitable structure. The apparatus includes a laser base unit adapted to provide laser light to an interaction region, the laser light removing material from the structure. The laser base unit includes a laser generator and a laser head coupled to the laser generator. The laser head is adapted to remove the material from the interaction region, thereby providing reduced disruption to activities within the structure. The apparatus further includes an anchoring mechanism adapted to be releasably coupled to the structure and releasably coupled to the laser head. The apparatus further includes a controller electrically coupled to the laser base unit. The controller is adapted to transmit control signals to the laser base unit in response to user input.

Abstract: The present invention relates to a laser processing method and the like having a structure for making it possible to process an object to be processed in various ways while accurately adjusting the installation state of the object. The method irradiates the object with plural adjustment laser light beams that are set in a specific positional relationship against a converging point of processing laser light beam, and adjusts the state of installation of the object while monitoring irradiation areas of the adjustment laser light beams on the surface of the object. Each irradiation directions of adjustment laser light beams is different from that of the processing laser light beam. By reflecting the irradiation condition of the adjustment laser light beam and monitored information of the irradiation areas in positional adjustment of the object, the installation state of the object can be adjusted in accordance with various kinds of processing.

Abstract: A machine for machining workpieces, especially metal sheets, comprises a machining device, a main drive and an auxiliary drive which is different therefrom. Both drives serve to generate a relative movement between the machining device and a workpiece for the purpose of machining the workpiece, wherein the machining device is movable relative to the workpiece and/or the workpiece is movable relative to the machining device with a main movement by means of the main drive and wherein the machining device is movable relative to the workpiece with an auxiliary movement by means of the auxiliary drive.

Abstract: A laser micro-machining system includes a laser source positioned to direct a laser pulse through a scan lens to a work piece mounted on a work surface and a mirror positioned between the scan lens and the work piece and tilted with respect to the work surface to reflect the laser pulse toward the work piece. The mirror can be indexed to a number of positions so that only portions of the mirror are used for a number of processing steps, extending the life of the mirror.

Abstract: A predictive pulse triggering (PPT) method enables precise triggering of a laser beam in a link-processing system. The PPT method entails triggering the laser beam based on estimated relative motion parameters of the target and laser beam axis. The PPT method allows for a six-fold improvement in laser positioning accuracy over the conventional, entirely measurement-based method.

Abstract: A method for processing a metal film (1) embedded in a carrier (2) includes the step of heating the metal film (1) in such a way that the metal film (1) is transformed in a subregion into at least one insulator section (3). The metal film (1) is preferably locally heated by laser radiation (4). Also described is a component (10, 11, 12, 13) which is produced by the method and includes an electrostatic clamp, a drive mechanism which is adapted for moving a workpiece under the action of electrical fields, a resistor element or a display device, for example.

Abstract: Embodiments of the present invention generally provide methods and apparatus for material removal using lasers in the fabrication of solar cells. In one embodiment, an apparatus is provided that precisely removes portions of a dielectric layer deposited on a solar cell substrate according to a desired pattern and deposits a conductive layer over the patterned dielectric layer. In one embodiment, the apparatus also removes portions of the conductive layer in a desired pattern. In certain embodiments, methods for removing a portion of a material via a laser without damaging the underlying substrate are provided. In one embodiment, the intensity profile of the beam is adjusted so that the difference between the maximum and minimum intensity within a spot formed on a substrate surface is reduced to an optimum range. In one example, the substrate is positioned such that the peak intensity at the center versus the periphery of the substrate is lowered.

Abstract: Removing material from the surface of a first circuit comprises generating a first laser pulse using a pulse generator; targeting a spot on the first circuit using a focusing component; delivering the first laser pulse to the spot on the first circuit, the first circuit including a digital component; ablating material from the spot using the first laser pulse without changing a state of the digital component; testing performance of the first circuit, the testing being performed without reinitializing the circuit between the steps of ablating material and testing performance. Targeting the spot on the first circuit comprises generating a second laser pulse using a pulse generator; delivering a second laser pulse to a sacrificial piece of material; detecting the position of the ablation caused by the second laser pulse with a vision system that forms an image; and using this image to guide the first laser to the spot.

Abstract: An insulator for a sensor arrangement of a laser processing machine comprises an outer insulating part of plastics material for electrical shielding and an inner shielding part of a non-conductive heat-resistant material for shielding against laser irradiation and/or heat.

Abstract: A laser-based workpiece processing system includes sensors connected to a sensor controller that converts sensor signals into focused spot motion commands for actuating a beam steering device, such as a two-axis steering mirror. The sensors may include a beam position sensor for correcting errors detected in the optical path, such as thermally-induced beam wandering in response to laser or acousto-optic modulator pointing stability, or optical mount dynamics.

Abstract: A tube matrix and the corresponding method of joining a plurality of tubes to a base plate to create the tube matrix. The tube matrix has a base plate from which a plurality of parallel tubes extend. The base plate has holes formed though it to receive the tubes. The tubes are placed into the holes on the base plate. The tubes may have end flares that abut against the base plate and prevent the tubes from completely passing through the base plate. Once the tubes are in place in the holes of the base plate, the tubes and base plate are welded together with individual laser welds. The laser welds enable a very dense matrix of tubes to be welded to the base plate without damaging or obstructing the tubes.

Abstract: A laser beam machining method and a laser beam machining device capable of cutting a work without producing a fusing and a cracking out of a predetermined cutting line on the surface of the work, wherein a pulse laser beam is radiated on the predetermined cut line on the surface of the work under the conditions causing a multiple photon absorption and with a condensed point aligned to the inside of the work, and a modified area is formed inside the work along the predetermined determined cut line by moving the condensed point along the predetermined cut line, whereby the work can be cut with a rather small force by cracking the work along the predetermined cut line starting from the modified area and, because the pulse laser beam radiated is not almost absorbed onto the surface of the work, the surface is not fused even if the modified area is formed.

Abstract: A laser beam irradiation apparatus irradiates a laser beam to a sealing unit disposed between a first substrate and a second substrate to seal the first substrate and the second substrate. The laser beam irradiation apparatus includes a laser head for irradiating the laser beam; and a control unit for controlling a drive-velocity and a drive-direction of the laser beam. The laser beam is controlled by the control unit which repetitively performs a backward and forward movement along a first direction, and passes a same position at least twice.

Abstract: A method and system for locally processing a predetermined microstructure formed on a substrate without causing undesirable changes in electrical or physical characteristics of the substrate or other structures formed on the substrate are provided. The method includes providing information based on a model of laser pulse interactions with the predetermined microstructure, the substrate and the other structures. At least one characteristic of at least one pulse is determined based on the information. A pulsed laser beam is generated including the at least one pulse. The method further includes irradiating the at least one pulse having the at least one determined characteristic into a spot on the predetermined microstructure. The at least one determined characteristic and other characteristics of the at least one pulse are sufficient to locally process the predetermined microstructure without causing the undesirable changes.

Abstract: A laser processing machine having a laser processing head that is open to a workpiece has a device for providing gas to the laser beam guide that introduces a first gas through a first gas inlet into the laser beam guide and introduces a second gas through a second gas inlet into the laser beam guide.

Abstract: A method for irradiating a plate (104) using multiple co-located radiation sources (108-1,108-2,108-3,108-4) includes that each of the multiple co-located radiation sources (108-1,108-2,108-3,108-4) is responsible for irradiating one of a plurality of bounded sub-regions (110-1,110-2,110-3,110-4) in the plate (104). As a result, sub-regions of the plate (104) that are to be irradiated receive relatively even, relatively well-defined radiation from the multiple co-located radiation sources (108-1,108-2,108-3,108-4). An apparatus performs the method, and a solar cell is produced using the method. The method and the apparatus can be applied in laser doping and laser cutting.

Abstract: The present invention relates to an apparatus and method for capturing an image of a welding spot during a welding task and determining an accurate position of the welding spot based on the captured image in order to perform an accurate welding task. A beam splitter splits a path of light reflected from a welding section of a spacer grid from a path of a laser beam generated from a laser generator. An image sensor receives light reflected from a welding spot of the spacer grid, and senses and stores an image of the spacer grid. Welding control means controls the image sensor to capture the image of the spacer grid, receives the image of the spacer grind from the image sensor, calculates an accurate position of the welding spot based on the received image, corrects position information of the welding spot based on the calculated position, and controls a servo motor so that the laser generator can accurately collimate the welding spot based on the corrected position value.

Abstract: A laser processing system includes a beam positioning system to align beam delivery coordinates relative to a workpiece. The beam positioning system generates position data corresponding to the alignment. The system also includes a pulsed laser source and a beamlet generation module to receive a laser pulse from the pulsed laser source. The beamlet generation module generates a beamlet array from the laser pulse. The beamlet array includes a plurality of beamlet pulses. The system further includes a beamlet modulator to selectively modulate the amplitude of each beamlet pulse in the beamlet array, and beamlet delivery optics to focus the modulated beamlet array onto one or more targets at locations on the workpiece corresponding to the position data.

Abstract: The thermal processing device includes a stage, a continuous wave electromagnetic radiation source, a series of lenses, a translation mechanism, a detection module, a three-dimensional auto-focus, and a computer system. The stage is configured to receive a substrate thereon. The continuous wave electromagnetic radiation source is disposed adjacent the stage, and is configured to emit continuous wave electromagnetic radiation along a path towards the substrate. The series of lenses is disposed between the continuous wave electromagnetic radiation source and the stage, and are configured to condense the continuous wave electromagnetic radiation into a line of continuous wave electromagnetic radiation on a surface of the substrate. The translation mechanism is configured to translate the stage and the line of continuous wave electromagnetic radiation relative to one another. The detection module is positioned within the path, and is configured to detect continuous wave electromagnetic radiation.

Abstract: A method of calibrating a vision based robotic system. The method includes engaging a calibration pin with a robotic tool and moving the calibration pin to a calibration block that includes at least one set of optical sensors having an optical transmitter to transmit an optical beam and an optical receiver to receive the optical beam. Further, the transmitted optical beam includes a center point. The method further includes: moving the calibration pin to the center point of the transmitted optical beam; determining a calibration pin center position relative to the robotic tool; and commanding a machine vision assembly having a camera to capture an image of a plurality of camera reading points of the calibration block and to determine a camera center position.

Abstract: A head for the continuous precision machining on three-dimensional bodies includes a fastening means to a flange of a machining equipment, having a first mechanical rotation axis, an intermediate means having a second mechanical rotation axis in series to the first mechanical rotation axis. The second mechanical rotation axis is orthogonal to the first mechanical rotation axis which intersects at a point of intersection. A terminal processing means has in series with the first and second mechanical rotation axes a third mechanical translating axis. The intermediate means has an arc configuration of a circumference with its centre at the point of intersection. The first mechanical rotation axis and the third mechanical translating axis are radially oriented to the arc.

Abstract: To better address these problems, one or more characteristics are measured from a work piece (28). The measurement information is used to select a preferred predetermined laser processing recipe from a lookup table. The laser processing recipe is then used to process the work piece (28). The lookup table of laser processing recipes can be established from theoretical calculations, from trial an error by an operator, from an automated systematic recipe variation process with post process testing, or from some combination of these or other methods. An automated process can also reduce operator errors and may store measurement values for convenient tracking of work piece characteristics.

Abstract: A laser processing system and a laser processing method that can highly accurately and efficiently specify a focus position of a processing laser using visible lasers are provided.

Abstract: The invention relates to a method for the laser welding of a composite material (V) to a component (11) in particular for the production of a solar collector element (E), wherein the composite material (V) comprises a strip-shaped substrate (1) composed of a metal having high reflectivity to laser radiation, said substrate having a first side (A) and a second side (B), wherein a dielectric coating (7) is situated at least on the first side (A), and wherein, in order to produce a weld seam, a laser beam (L) is projected at an acute orientation angle (?) at least onto the first side (A) of the substrate (1) provided with the dielectric coating (7).

Abstract: Device for remote laser welding of metal sheet structures comprises an anthropomorphous robot onto whose wrist is mounted an accessory device carrying a focusing head for the laser beam coming from a laser source, as well as means for oscillating the pointing direction of the focused laser beam around one oscillation axis. During welding the robot shifts the accessory device along a given trajectory and at a given speed, while the pointing direction of the focused beam is oscillated to as to allow the area of structure that is lighted by the laser beam to shift at a speed and/or along a trajectory not depending directly on the shifting trajectory and speed of the accessory device carried by the robot.

Abstract: Systems and methods cut trenches of multiple widths in a material using a single pass of a laser beam. A first series of laser pulses cut a work surface of the material at a first cutting speed using a first spot size. In a transition region from a first trench width to a second trench width, a second series of laser pulses sequentially change spot sizes while gradually changing from the first cutting speed to a second cutting speed. Then, a third series of laser pulses continue to cut the work surface at the second cutting speed using a second spot size. The method provides for increased depth control in the transition region. A system uses a selectively adjustable optical component in the laser beam path to rapidly change spot size by adjusting a position of a focal plane with respect to the work surface.

Abstract: A laser processing apparatus including a height detecting device for detecting the height of a workpiece held on a chuck table. The height detecting device includes an annular spot forming unit for forming the spot shape of a detecting laser beam into an annular spot shape, a pinhole mask for passing the reflected light reflected on the upper surface of the workpiece held on the chuck table, but blocking the reflected light reflected on the lower surface of the workpiece, and a reflected light analyzing unit for analyzing the reflected light passed through the pinhole mask and transmitting the result of analyzation to a control unit. The laser processing apparatus further includes a focusing unit having an objective lens for focusing a processing laser beam having a circular spot shape and the detecting laser beam having the annular spot shape and a window lens for focusing the detecting laser beam focused by the objective lens without focusing the processing laser beam.

Abstract: The present invention relates to hard coating of ferrous metal substrates using a laser beam with diamond particles in a metal matrix produced from precursor powders of metals which bond to the diamond particles and to the ferrous substrate. The hard coating is particularly useful for white iron castings for pumps (200) used in piping tar sand and water mixtures.

Abstract: The machining device is equipped with a fiber laser oscillator for oscillating laser light of a top hat shape, and a light collecting lens and a machining head for collecting the laser light of the top hat shape and emitting the laser light onto a machining target such that the beam diameter of the laser light of the top hat shape at a position where light intensity becomes the one corresponding to a machining threshold of the machining target is about three times the size of the beam diameter of laser light in a Gaussian mode at the same position, when the laser light in the Gaussian mode has a beam quality substantially the same as that of the laser light of the top hat shape.

Abstract: In the thermal cutting of a workpiece by means of a laser beam, said beam is generated by means of a laser source and supplied to a movable laser head. In the laser head, an optical deflection element is provided for deflecting the laser beam such that, when viewed in working direction, it encloses a tilt angle (?) differing from 0 degrees with the longitudinal axis of the laser head. Starting therefrom, to produce the inclination of the collimated laser beam to the vertical with a very small number of optical components if possible, the invention suggests that the laser beam is supplied to the laser head by means of an optical fiber and the laser beam is collimated, passes through the deflection element laterally offset to the longitudinal axis of the laser head and is deflected by means of said element onto the workpiece surface and focused at the same time.

Abstract: Methods for laser scribing a film stack including a plurality of thin film layers on a substrate are provided. A pulse of a laser beam is applied to the film stack, where the laser beam has a power that varies as a function of time during the pulse according to a predetermined power cycle. For example, the pulse can have a pulse lasting about 0.1 nanoseconds to about 500 nanoseconds. This pulse of the laser beam can be repeated across the film stack to form a scribe line through at least one of the thin film layers on the substrate. Such methods are particularly useful in laser scribing a cadmium telluride thin-film based photovoltaic device.

Abstract: The present invention relates to a method and apparatus having a structure that enables laser processing of an object even when the object has a surface formed with irregularities. The laser processing method irradiates objects, each having a cylindrical form extending in a first direction, with laser light. Here, the objects are arranged on a first plane along a second direction orthogonal to the first direction. The arranged objects are irradiated with first and second laser light beams in irradiation directions different from each other to the first plane. At least during when the first and second irradiation light beams are respectively emitted, irradiation positions of the first and second laser light beams to the first plane are relatively moved.

Abstract: A method of aligning a wafer when lithographically fabricating a light-emitting diode (LED). The method includes forming on the wafer at least one roughened alignment mark having a root-mean-square (RMS) surface roughness ?S. The roughened alignment mark is formed as a consequence of forming a plasma etch to roughen a LED surface on which the wafer alignment mark resides. The method also includes imaging the at least one roughened wafer alignment mark with alignment light having a wavelength ?A that is in the range from about 2?S to about 8?S. The method also includes comparing the detected image to an alignment reference to establish wafer alignment. Once wafer alignment is established, p-contacts and n-contacts can be formed on the LED upper surface in their proper locations.

Abstract: The invention is a method and apparatus for laser marking a stainless steel specimen with commercially desirable marks. The method includes providing a laser processing system having a laser, and laser optics and a controller with pre-determined laser pulse parameters, selecting the pre-determined laser pulse parameters associated with the desired mark, and directing the laser marking system to produce laser pulses having laser pulse parameters associated with the desired marks including temporal pulse widths greater than about 1 and less than about 1000 picoseconds.

Abstract: Disclosed herein is a laser irradiation apparatus, including: an optical system configured to form laser light of a linear cross section to be irradiated on an irradiation object; and a cutting member having a light blocking portion configured to block the laser light formed in the linear cross section by the optical system to cut the laser light so as to have a predetermined length along a line longitudinal direction; the light blocking portion having a plurality of fins provided on the light blocking portion thereof so as to fetch and absorb the laser light.

Abstract: A method for joining dissimilar materials of sensor button for measuring torque is illustrated. The dissimilar materials can be welded together by laser welding. The parts can be cleaned and held together firmly by a fixture and welded with established machine parameters. The method of micro-crack free weld joint can give a robust joint for the life time of the automotive which mandate for the function of torque sensor to facilitate the positive strain transfer from the parent material.

Abstract: A laser shock peening process for producing one or more compressive residual stress regions in a medical device is disclosed. A high-energy laser apparatus can be utilized to direct an intense laser beam through a confining medium and onto the target surface of a workpiece. An absorption overlay disposed on the target surface of the workpiece absorbs the laser beam, inducing a pressure shock wave that forms a compressive residual stress region deep within the workpiece. Medical devices such as stents and guidewires having one or more of these compressive residual stress regions are also disclosed.

Abstract: A weld zone of T-piping and its neighborhood are efficiently laser-heated to remove residual stress. For this purpose, the weld zone of a T-piping (50) is irradiated and heated with a laser beam emitted from a laser head (10) to remove residual stress. At this time, a rotating travel cart (3) travels along a ring rail (2) to adjust the position of the laser head (10) in a ?-direction, a vertical slide (4) slides to adjust the position of the laser head (10) in a Z-direction, a radial slide (5) slides to adjust the position of the laser head (10) in an L-direction, an arcuate piece slide (7) slides along an arcuate piece to adjust the ?-direction of the laser head (10), a laser head support portion (9) turns to adjust the ?-direction of the laser head (10), and oscillation adjusts the position of the laser head (10) in a ?-direction.

Abstract: A method and apparatus for targeting a beam of radiation is provided. A beam steering mirror and a beam capture mirror are movably disposed along an optical pathway. A controller moves the beam steering mirror and the beam capture mirror in an x-y plane, and rotates the mirrors, to target the beam to a target location on a surface, while keeping the optical path length substantially constant for all target locations on the surface. The surface is rotated by a rotational actuator to bring all target locations to positions accessible by the beam targeting optics. Imprecision in targeting and optical path length may be compensated by providing an actuated aperture at the beam entry point and/or a variable focus lens with an optical range finding detector, all in communication with the controller.

Abstract: A laser welding apparatus and method for easily adjusting a laser focusing position according to a distance from a laser irradiating device to a laser irradiating point on a work piece, or a welding point. A post-collimation laser diameter is measured when the laser emitting end has an optimal laser diameter on the work piece with respect to the distance from the laser processing head to the work piece. Corresponding data is stored with the above distance and the post-collimation laser diameter corresponding to each other. During welding, a diameter of the laser beam passing through a collimate lens is measured by a laser diameter measuring device. The post-collimation laser diameter is adjusted to be an optimal value according to the corresponding data.