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WO2007096462A1 - Procédé d'écrouissage - Google Patents

Procédé d'écrouissage Download PDF

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Publication number
WO2007096462A1
WO2007096462A1 PCT/FI2007/000047 FI2007000047W WO2007096462A1 WO 2007096462 A1 WO2007096462 A1 WO 2007096462A1 FI 2007000047 W FI2007000047 W FI 2007000047W WO 2007096462 A1 WO2007096462 A1 WO 2007096462A1
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WO
WIPO (PCT)
Prior art keywords
ablation
target
radiation
spot
path
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/FI2007/000047
Other languages
English (en)
Inventor
Jari Ruuttu
Reijo Lappalainen
Vesa MYLLYMÄKI
Lasse Pulli
Juha MÄKITALO
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Picodeon Ltd Oy
Original Assignee
Picodeon Ltd Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from FI20060182A external-priority patent/FI20060182L/fi
Application filed by Picodeon Ltd Oy filed Critical Picodeon Ltd Oy
Publication of WO2007096462A1 publication Critical patent/WO2007096462A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/08—Devices involving relative movement between laser beam and workpiece
    • B23K26/082—Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/08—Devices involving relative movement between laser beam and workpiece
    • B23K26/082—Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
    • B23K26/0821—Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head using multifaceted mirrors, e.g. polygonal mirror
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B23K26/362—Laser etching
    • B23K26/364—Laser etching for making a groove or trench, e.g. for scribing a break initiation groove
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001—Technical content checked by a classifier
    • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Definitions

  • the invention relates to material science related laser technology via the ablation in general, but in more specified way as expressed in the preamble part of an independent method claim.
  • the invention relates also to an ablation based ar- rangement as expressed in the preamble part of an independent claim on arrangement.
  • the invention relates also to a weapon as expressed in the preamble part of an independent claim on weapon.
  • the invention relates also to an explosive disarmament device as expressed in the preamble part of an independent claim thereon.
  • Fibre lasers and/or the comprising fibres therein for guiding the laser beam have not been able to deal with high powered compressed laser pulses in their delivery to the working area.
  • the fibres do not tolerate transfer of high power pulses.
  • Reasons why to use fibres for the transference of the laser radiation seem to relate to the problems that occur in situation in which free radiation paths were used but the path direction changes are made by deflection and/or mirroring.
  • the commercially available fibres reduce the radiation power that could have been conducted through them and thus also limit the target materials to be ablated.
  • Al can be ablated as such with reasonable pulse power, whereas higher pulse power is needed for such substances as Cu, W, etc. for getting them ablated.
  • Fibrous laser-related technology suffers also from other problems.
  • fibres can not be used to transfer high amounts of energy in short time scale without degrading effects of the fibre.
  • Such effects as melting, fragmentation and/or other deformations in the fibre structure due to the energy of the light, for instance, lead consequentially to the degeneration of the grade of the laser light pulse while directed through a path via a fibre that is suffering degrading effects.
  • Even pulse energy of 10 ⁇ J can degrade a fibre that has even smallest structural or qualitative defects.
  • Special points for defects in a fibrous optical path are the fibre connectors for instance, that are used to connect together several power sources such as diode-pumps, but the connectors are worn out during their stay in duty.
  • the pulse energy that can pass a fibre can be kept reasonable if the power of a single pulse increases, while the pulse duration is shortened in a corresponding way.
  • the problems of the fibrous lasers are not limited only to the fibres, but also to the connecting of separate diode pumps together via optical connectors for achieving the desired total power for the beam, to be directed to the working target via one fibre.
  • the applicable optical connectors should also tolerate the power levels and/or energy of a pulsed radiation as much as the optical fibre itself that is used to direct the high power pulse to the working target.
  • the pulse shape should be preserved at the optimum in each transferring phase of the pulse to the hit spot on the working target.
  • the laser beams generated by their sources and/or directed for utilisation via fibres in the optical path according to the known techniques, at the priority date of the current application, suffer power and quality related problems that limit the ap- plications of the devices to the ablation.
  • Such problems can relate to scanning of the beam by scanners that have to be used at a limited repetition frequency, but without a facility to raise the frequency to such a level that industrial mass production were realizable for good and uniformly qualified products.
  • Such scanners according to the state of the art can also suffer from the losses further caused by the optical windows that are to be used in the inserting of the beam via an optical path from outside of the chamber in which the working target is held for the ablation duration in under pressure conditions, for instance.
  • the effective power of known devices in ablation remain in the order of 10 W.
  • the repetition rate can limit to bare 4 MHz of a pulse frequency of a pulsed laser. If the pulse frequency were tried to be increased, the state of the art solutions for scanners suffer from uncontrolled directing of the beam to the walls of the laser equipment, but also directing of the beam into the plume of the already ablated material in plasma phase. Such problems have an adverse net effect on to the surface that were under manufacturing by the ablated material, by the beam directed by using such a scanner, but also adverse effects to the production rate, which effects are constituted by the uncontrollable radiation flux variations at the hit spot on the target.
  • the quality of the plasma may be inap-litistely applicable for the tolerances of a certain product to be manufactured, i.e. with the reasonable surface structure quality in question.
  • the working methods according to the state of the art may suffer degrading of the cutting power and/or the quality of the product being the object whose surface was targeted in the process. Also fragments are probable to be ejected from the hit spot on the target surface under the working methods according to the state of the art. Such fragments can deposit on to the surrounding surfaces in an unpredictable way and so degrading the resulting product.
  • the state of the art techniques demands also time, especially if there are several surfaces and/or layers to be coated, but the quality of the layers may vary in a non-desired way. Especially, before the priority date of the priority application for this document, the writer did not know commercially available methods to manufacture sufficiently strong and substantial pieces for 3D-objects printing and/or copies.
  • the writer knows that the scanning speeds of the state of the art scanners are of about 3 m/s, and the speed can vary during the scan, so being not a constant. This is a consequence of the known scanner structures of the type that stop for a while the scanner mirror turns backwards after a single scan to make another scan. It is also known that during the backward movement the scanner makes a second scan similarly as the first one. Also back and forth moving mirrors of plate type are known per se, but they suffer the same problem of unequal movement and thus the unequal scanning speed during the scan. Such an ablation techniques has been shown in patent publications US 6,372,103 and US 6,063,455.
  • the scanning part of the scanner accelerates, decelerates, stops etc, consequently causes that the scanning speed is not constant, inducing also that the yield of the plasma, due to the ablation at the hit spot on the working target, varies. Especially at the ends of the scanning path on the target, the variation related adverse effects of the plasma production are highlighted so also degrading the product.
  • the material vaporizes to atomic domain particles.
  • the target material can be ejecting fragments that can have size of several micro meters, and thus degrade the surfaces on the target in question, to be worked, cut and/or to be coated with the plume material.
  • the increased pulse frequency as such is not a solution, because the speeds of the scanners according to the state of the art are inappropriately low.
  • the state of the art techniques need a separate lens assembly between the scanner and the target to focus the beam to the hit spot, contributing to absorption of the beam in wrong place.
  • the scanning width of a state of the art scanners may be a problem.
  • the line wise scanning method used with the mirror-film scanners can contribute to the nominal scanning width of 70 mm, for example, but in practice the scanning width can re-lude to 30 mm at the target, with unequal ends of the scanning path, and/or different from the parts between the ends.
  • Such small effective scanning widths can cause serious incompatibility problems in such cases that large, widely sized objects are to be worked and/or coated. The problems may even to make industrial scale production if not totally impossible, quite hard and/or unremunerative.
  • Figure 1 illustrates a problem related situation according to the state of the art.
  • the laser beam appears to be out of the focus in the Figure 1.
  • the plasma generated has a low quality.
  • the plasma can comprise fragments 116 from the target.
  • the target and/or the vapours can degenerate even to useless level of quality.
  • Such a typical problematic situation of the state of the art techniques can be occurring with a too thick target 114.
  • the target 114 should be moved towards the direction 117, z-movement, from which the laser beam 111 is coming as much as the target is used in ablation by ablating the layers 111, 112 and 113.
  • the variations of the focus in the state of the art techniques occurring in the middle of the ablation event, induce immediately a change in the plasma quality.
  • the energy density of the pulse at the surface of the target material diminishes (nor- mally), so the vaporization/plasma generation may be not any more ideal/perfect in the circumstances.
  • the plasma energy may remain in low level, and unnecessary large number of fragments may be met, and the surface morphology may be changed, the adhesive properties and/or the thickness of the coating, if applied, can also be changed.
  • the state of the art systems can have complicated control systems that are to be used as a must.
  • the target appears as a thick rod or plate.
  • the lens for focusing may be implemented as a zoom lens as applied, or the target is moved towards the beam in the rate of the target material utilisation.
  • Even the implementation attempt may be very difficult if not entirely impossible, for a reliable apparatus to be used for the industrial scale production.
  • the quality variation may be great, leading to unbearable burden to the quality control out of the scope of implementation with sufficient precision.
  • Thick targets are also expensive to be manufactured etc.
  • ablation In material science, a branch of which relating to laser technology, ablation has been known as such as a technique of removing material from a phase of the target material to plasma phase. It is known as such that such a phase transition can be made to occur by intensive laser radiation onto the target piece. Also some va- pour from the target material can be released in the process in certain conditions.
  • Stresses can dismiss by a mechanism in which the forces can enable fragmentation of the target at the hit spot, tore the material into lumps and/or pieces to be ejected around the hit spot environment, which effect is quite often a non-wanted co-effect of the long pulsed lasers.
  • the pulse energy of a long pulse finds time to be delivered into the surrounding target structure in the time scale of the heat transfer mechanism of the material structure, but a short pulse does not significantly in said time scale.
  • short pulse duration lasers can be regarded as cold work lasers, as the heat is not transferred, the ablation occurs so rapidly that the mechanism does not have sufficient time to transfer the received pulse energy into the lattice or other surrounding structure of the hit spot.
  • the material surfaces after the cold work has less fragments if not completely does not have them at all, which is important advantage of such embodiments of the invention that use in the cold-work short laser pulses for a fine and sharp results of the ablation target as the work piece.
  • the invention is aiming to show a surface handling arrangement, aiming to solve or at least mitigate problems of the state of the art.
  • the invention is aiming to show also method, device/arrangement/apparatus and/or a system for cold working a surface of the target piece, more efficiently and/or with a better quality surface material than know at the moment of the priority date of the priority application.
  • the invention is aiming to show an arrangement for handling surfaces as applied to be used in a 3D-printer by repeatable coating/carving of a body with better quality surface material than know at the moment of the priority date of the priority application.
  • the object of the invention is achieved by a surface handling arrangement that utilises according to an embodiment of the invention a turbine scanner in the radiation path between the radiation source and the target.
  • the object of the invention relate to the objectives in the following:
  • a first objective of the invention is to provide at least a new method and/or related means to solve a problem how to provide available such high quality, fine, plasma practically from any target, so that the target material do not form into the plasma any particulate fragments either at all, i.e. the plasma is pure plasma, or the fragments, if exist, are rare and at least smaller in size than the ablation depth to which the plasma is generated by ablation from said target.
  • a second objective of the invention is to provide at least a new method and/or related means to solve a problem how, by releasing such fine plasma, to produce a fine cut-path in for such a cold-work method, that removes material from the target to said ablation depth, so that the target to be cold-worked accordingly keeps without any particulate fragments either at all, or the fragments if exist, are rare and at least smaller in size than the ablation depth to which the plasma is generated by ablation from said target.
  • a third objective of the invention is to provide at least a new method and/or related means to solve how to coat a substrate area to be coated with the fine plasma without particulate fragments either at all or without fragments larger in size than the ablation depth to which the plasma is generated by ablation from said target, i.e. to coat substrates with pure plasma originating to practically any material.
  • a fourth objective of the invention is to provide a good adhesion of the coating to the substrate by said fine plasma, so that wasting the kinetic energy to particulate fragments is suppressed by limiting the existence of the particulate fragments or their size smaller than said ablation depth.
  • the particulate frag- ments because of their lacking existence in significant manner, they do not form cool surfaces that could influence on the homogeneity of the plasma plume via nu- cleation and condensation related phenomena.
  • the radiation energy in the ablation event is transformed to the kinetic energy of the plasma effectively by minimizing the heat affected zone by using preferably short pulses of the radiation pulses, i.e. in the picosecond range or shorter pulses in time duration, with a pitch between two successive pulses.
  • a fifth objective of the invention is to provide at least a new method and/or related means to solve a problem how to provide a broad scanning width simultaneously with fine plasma and high quality and broad coating width even for large bodies in industrial manner.
  • a sixth objective of the invention is to provide at least a new method and/or related means to solve a problem how to provide a high repetition rate to be used to provide industrial scale applications in accordance with at least one of the objectives of the invention mentioned above.
  • a seventh objective of the invention is to provide at least a new method and/or related means to solve a problem how to provide fine plasma for coating of surfaces to manufacture products according to at least one of the objectives from the first to sixth, but still save target material to be used in the coating phases producing same quality coatings/thin films where needed.
  • An further objective of the invention is to use such method and means according to said at least one of the first, second, third, fourth and/or fifth objectives to solve a problem how to cold-work and/or coat surfaces for such products of each type in accordance with the objects.
  • a radiation-based surface treatment apparatus which includes in its radiation transmission line a turbine scanner according to an embodiment of the invention. Then, using the surface treatment apparatus according to the invention, the removal of material from the surface treated and/or the yield for coating can be raised to a level required by high-quality coating, yet with sufficient speed and without unreasonably limiting the power of the radiation used.
  • the ablation rate along the ablation path on the target can be set to sufficient level for appropriate surface handling of the body to be machined, coated and/or to be used as target to be carved, drilled and/or otherwise cold-worked, but however, so that the rate is in sufficient range but the radiation to be used is not unnecessarily limited.
  • the cold work method according to the invention is characterized in that the method comprises ablating, along a predefined ablation path on an ablation target surface, to a predefined ablation depth by laser radiation having at least one characteristic wavelength and at least one pulse characteristic for each wavelength for the radiation to be used for ablation of said ablation target material, wherein the radiation from the source is directable via an optical path onto the working spot on said ablation target via a turbine scanner.
  • the cold work arrangement according to the invention is characterized in that the arrangement comprises a laser radiation source to provide the laser radiation be used in the ablation, and at least one turbine scanner arranged into the optical path arranged to lead laser radiation from said laser radiation source to the hit spot of the ablation target at the ablation path location.
  • Ablation based cold work system is characterized in that the system comprises at least one ablation based cold-work arrangement and automating means arranged to handle the ablation target bodies for their input, movement and/or removal from the system.
  • a weapon according to the invention is characterized in that what is characteristic to the cold work arrangement according to the invention.
  • An explosive disarmament device is characterized in that what is characteristic to the cold work arrangement according to the invention.
  • the radiation source can be a suitable laser source according to an embodiment as embodied later in the document.
  • Figure 1 illustrate some problems relating to state of the art techniques
  • FIGS. 2A, 2B, 2C, 2D each illustrate cutting results according to an embodi- ment of the invention
  • FIG. 3 illustrates an example of an arrangement according to an embodiment of the invention
  • Figure 4 illustrates a cold work method according to an embodiment of the invention
  • FIG. 5 illustrates a scan according to an embodiment of the invention
  • FIG. 6 illustrates an arrangement according to an embodiment of the invention
  • Figure 7 illustrates a turbine scanner according to an embodiment of the invention.
  • Figure 8 illustrates products according to embodiments of the invention. Ensemble of embodiments of the invention
  • a suitable pulse length for a target material is less than 30 ps to be counted as a short pulse.
  • pulses within the fs-scale duration in another embodiment or even as-scale (attosecond-) in a further embodiment can be used down to 0,05 as (attosecond).
  • the pitch between two successive pulses is equal or shorter than the pulse duration, but kept constant.
  • the pitch duration is longer than the pulse duration but kept constant. Constant pitch and/or pulse length makes the radiation source simpler and easier to manufacture as a laser source.
  • a pumped laser source can be arranged to have at least some intermittency for the pitch and/or the pulse duration achievable in the energi- zation by using a plurality of pumping mechanisms timed intermittently or differently timed to yield intermittence and to make the pumping either optically and/or electrically embodied in suitable part.
  • the intermittently pulsed laser can be a pumping laser to be used to pump a power laser according to an embodiment, or the intermittently pulsed laser can be itself a power laser, that is pumped by several mechanisms.
  • the pulse characteristics of the radiation to be used for the ablation can comprise such features as the pulse power, pulse energy, pulse shape, pulse duration, pitch be- tween two successive pulses, intermittence, pulse/pitch repetition rate of the pulses on the target, repetition rate of the pulses on the scanner, cover ratio of the pulses on the target and/or a combination thereof.
  • the cover ratio of the pulses can be defined by a ratio of the common area of two successive hit spots to the area of an arbitrary hit spot.
  • characteristic wavelength means a wavelength that originates to the laser source that is used for the ablating.
  • the laser source can have several polarization modes at the characteristic wavelength, from which a certain mode can be selected to be used in the ablation in one embodiment, but in another embodiment several modes and/or characteristic wavelengths can be used when associated to the suitable pulse characteristic or characteristics.
  • the radiation to be used is in the wavelength range from radio wavelengths down to ultraviolet wavelengths or even down to low energy x-ray wave- lengths.
  • the wavelength of the radiation comprises monochromatic and coherent radiation component that has a wavelength of radio waves IR, UV, visible light. Also intermediate ranges can be applied in embodiments.
  • ab- lation path can be predefined, so as to be used for defining the order in which the material from the ablation target is to be ablated.
  • the ablation path can comprises a spot or to be a spot-like, for applications in which a dot ".” is to be formed on the ablation target.
  • the dot can be gap, cavity or an ablation-drilled hole, even through the ablation target piece from its one side to another, said dot having a shape derivable from the ablating radiation geometry.
  • the path comprises a line, which is thus a queue of the hit spot on the target surface.
  • the hit spots are essentially or completely non-overlapping, the hit spots form a line along the surface on the ablation target surface, according to the radiation geometry of the pulsed laser beam to form the dots, is referred as a carving embodiment.
  • the hit spots are essentially at the same location for making a hole and/or cavity along the normal of the surface.
  • holes that define a direction with such an angle that is between a surface and its normal can be drilled according to an embodiment of the invention.
  • the overlapping of the hit spots are arranged to define the direction of the cavity.
  • the drilling may happen at least some part so that part of the radiation of the pulse goes through the plume.
  • the plume can be further ablated by another beam arranged to remove the plasma, or the ablated plasma can be removed at least partly by electromagnetic means arranged to provide an electromagnetic field to interact with the charged plasma particles in order to deflect the plume away from the incoming radiation pulses.
  • the ablation-originating plume is kept small so to be eas- ily and quickly dismissed.
  • the pulse shape is chosen so that the laser pulse has a first pulse-part that has a first power level capable of ablating target material at the hit spot, and a second pulse-part that has a second power level, which is higher than said first power level so capable to compensate extinc- tion of the plume.
  • a pulse can be advantageous in certain embodiments in which the carving and/or drilling should be made through the plume directed radiation pulses.
  • the ablation target can be in rest in respect to the laser source.
  • the abla- tion path on the ablating target is defined by a respective movement of the laser source and the target body.
  • the target is hold by a holder that is arranged to move the ablation target body so that its surface comprises at least partly the ablation path having the characteristic dimensions of the ablation path and the appropriate ablation depth in each defined loca- tion of the ablation path, as defined according to radiation geometry of the laser source.
  • the ablation target can be arranged to rotate so having the ablation path along the surface of said target. If the rotational movement is suitably constant and occurs around a fixed axis, an embodi- ment of the invention can be used for cutting the ablating target, as in turning machines and/or reamers. Also other carving-like actions can be arranged to occur in a similar way as in a turning machines and/or reamers.
  • the target piece can be placed on to a robot providing movements in an xy-plane, z-plane and/or at least one rotating movement so providing at least in theory access of the ablating beam to any visible surface location, for a carving action and/or cutting parts of the ablation target body.
  • the carving can be made in a low pressure that is however higher pressure than the pressure in outer interstellar free space, but lower than an atmospheric pressure.
  • the carving can be made in over pressure condition, and/or in a specific gas atmosphere for yielding protection against the diffusing plume materials to the parts that may be critical for the material.
  • the laser radiation geometry can be a beam, as approximated as a one-dimensional line from the source to scanning optics and further to the ablation target, so advantageous to be utilised in formation of ablation paths that have a breadth in order of ten or several tens of times or smaller breadth.
  • the laser radiation geometry can be as a fan of beams, as approximated as a two-dimensional plane from the source to scanning optics and further to the ablation target on which the fan causes a surface oriented line by one pulse shot, so defining an area to be carved on to the ablation target by several adjacent pulses.
  • several fans of beams can be arranged to hit the ablation target simultaneously so defining an area by one pulse shot, provided that the power is sufficiently large to cause ablation at said area to the appropriate ablation depth of one pulse shot.
  • This can be also provided by a bunch of optical fibres and/or beam expanders with sufficient tolerance to tolerate high energy level of the laser.
  • the ablation target is kept in rest and the ablating ra- diation is directed via an optical path to the ablation target that is held still.
  • both the ablation target and the ablating radiation are to be moved in respect, in each other, but also in respect to a virtual third party observer.
  • the system can be embodied so that in one embodiment the system comprises a measurement unit to be used to measure the measures of a body to be copied, and a cold-work means embodied according to an arrangement according to an embodiment of the invention so to cold work a target by carving and/or drilling to the measures of the body to be copied.
  • the copy is scaled to different measures as the original, but according to another embodiment to the same measures as the original.
  • the system according to an embodiment of the invention can also embody a copy machine, to be used in copying a body in 3D. According to an embodiment of the invention such a copy machine is implemented as a turning machine or alike.
  • the copy machine can be implemented by repeatable way constructing layers that originate to an ablated material.
  • the ablated material is used so that the plume is directed to coat a surface layer by layer so forming the object to be copied with the measures of the original or with scaled measures.
  • the method has also embodiments that are directed to destruction of enemy and/or the military material of such.
  • the working method embodied applicable as to weapons also long pulsed lasers can be used having the pulse duration over 80 ps, even up to micro second scale.
  • the fragments may be not the problem of the weapon user, and thus also the thermal transfer does not have a role to play, does a destroyed enemy the material, vehicle and/or tank have smooth cut line or not.
  • cold-work lasers can be used also in disarmament of explosives, so cutting by ablation the detonating path from the ig- nition primer to the essential explosive material away, or by ablating critical parts of a bomb so to disarming it.
  • the explosive material is cut to smaller pieces to be removed so that if the ignition occurs, only the primer and/or a small amount of the explosive goes off. That is possible because the material structure of the explosive is not sufficient enough capable to relay the ther- mal transmission from the hit spot to the surrounding material.
  • the detonation speed can be in order of 10 km/s, may be much lower in reality, which shown estimate speed is quite slow in comparison to the actions that happen in the material between its structural parts.
  • the cold-work by ablation can be used in purification of materials, provided that the plume is to be handled as such, so as at least some of the constituents to be separated in suitable part from the other.
  • the material that is ablated from the ablating path is arranged to originate from such a target that has a material layer arranged to be used in coating by the ablation released plasma, by plac- ing and/or moving the body to be coated into the plume of the plasma of high quality (an ensemble of examples on embodiments, see Fig.8).
  • the ablating radiation is directed from the source to the working spot at the ablation target via an optical path, which can be embodied in one embodiment by a fibre based path in suitable part, but in an- other embodiment in suitable part in vacuum.
  • the path comprises a scanner arranged to scan the radiation to the working spot of the ablation target.
  • the scanner is a turbine scanner, which has a rotatable structure arranged so that it comprises a first mirror surface part that is arranged to direct said radiation towards the working spot while another, a second mirror surface part of a previous location of the radiation spot on a mirror surface of the scanner is arranged to cool.
  • the turbine scanner comprises a polygon geometry so that there are at least three mirrors and/or angles from which said first and second mirror surfaces are selectable due to the rotation.
  • the polygon geometry can be arranged by more than three mirrors and/or angles.
  • the angles at the corners are rounded so better to define the direction of the radiation pulses when shifting from a first mirror to the next one.
  • the rounded corners are surface-worked to comprise structure aiming to minimum turbulence of the medium so to avoid influence of the eddies in the medium to the laser beam power level.
  • a flat, disk like turbine scanner is used; preferably for radiation geometries that are arranged to provide a dot oriented hit spot.
  • geometry of the beam can be adjusted by a suitable beam expander where necessary to apply the scanned beam to a certain geometry to enlarge the hit spot to a hit area, provided that sufficient power for the ablation at the area is available.
  • a prismatic-like but longer than a disk turbine scanner, in direction of the rotation axis length can be used for radiation geometries that are arranged to provide a line oriented hit spot.
  • the number of sides of the polygon is not limited in theory, but for practical reasons of manufacture precision the number of polygon sides is lower than or equal to 300, preferably lower or equal to 64, but most preferably in an embodiment equal or lower than 16.
  • the mirrors comprise a curved surface part so arranged to deflect the ablation path at the ablation target in a certain repeatable way.
  • the curvature can be, as arranged in the plane of the rotation, positive but according to another embodiment negative, as respectively defined by the distance of the nearest part of the mirror to the rotation axis as being in minimum with the positive curvature and as maximum with the negative curvature.
  • the curvature can be arranged in the plane of the rotation axis, i.e. in perpendicular to the rotation defined plane.
  • multiple curvatures can be used in order to arrange a repeatable ablation path on the ablation target.
  • the rotation speed of the turbine scanner can be larger than 100 000 revolutions per second. According to another embodiment of the invention the rotation speed of the turbine scanner is lower than 1000 000 revolutions per second. According to an embodiment of the invention the revolution speed is constant during the operation of the scanning, but ar- ranged to be adjustable between a maximum value and zero, to be set on to the suitable level to have sufficient amount of pulses to the working spots of the ablation path.
  • the turbine scanner to be used comprises parts made of nano-tube material because of the tolerance against the forces in a high-speed rotation.
  • the scanning surfaces can be coated with carbo- nitride (C 3 N 4 ) for improved mechanical and/or thermal durability to tolerate high- energy pulses of the laser source.
  • ablation to be used in the cold work is made by a laser source radiating laser-radiation that has at least one characteristic wavelength.
  • single cavity can provide also harmonic waves with a different wavelength, but such may be not directly utilizable as such to the ablation according to an embodiment of the invention.
  • the laser source is selected for the cold-work so that its radiation is pulsed so that the pulses have duration that is shorter than 50 ns (nanoseconds), but according to an embodiment advantageous for a probability to cause less fragmentation of the ablation target the pulse duration is shorter than 50 ps (picoseconds), but according a further advantageously for a probability to cause less fragmentation shorter than 10 ps.
  • the pulse length can be even shorter, as in one embodiment in the fs-range (femtosecond) arranged to be used for the ablation along the ablation path.
  • a new turbine scanner was used to demonstrate the effect of scanning speed on the groove and particle production in a carving like application to make grooves on the ablation target with an arrangement according to an embodiment of the invention.
  • the ablation path was selected along the surface of the target material, and the laser beam was having a dot like geometry at the hit spot at the locations of the ablation path.
  • Samples were (100) Si wafers (mirror finish, commercial grade) 0.5 mm in thickness.
  • Laser fluence power/area was manually adjusted to exceed ablation threshold of Si, then surface (groove) was ablated for the same time (30 s) at different scanning speeds of the focus spot (1.5, 15, 150 and 300 m/s) of the radiation. Each scanning speed was obtained by adjusting the rotation speed of a scanner head.
  • Figure 3 indicates a scanner head (exemplified with a protective Al shield) just before installation on the arrangement frame on the left.
  • Example on the scanner controlling electronics is indicated on the right.
  • Figure 4 illustrates a cold work method according to an embodiment of the invention.
  • the method has phase 6001 of selecting and/or exposing the target to be exposed to the radiation to ablate material along the ablation path on the target.
  • a radiation beam is directed to the selected target material in phase 6002 in order to expose a target material to the radiation at the hit spot.
  • the second ablation phase 6004 is not necessary a parallel phase, but can be a serial phase according to one embodiment.
  • the target can comprise a constituent of the coating, but part of the coating can be formed by the atmosphere at the substrate, and/or the substrate surface constituent or several.
  • the target material is the same as the coating.
  • the coating phase 6005 can be used as only coating phase according to one embodiment, but the second coating phase 6006 illustrates that in another embodiment there can be several phases of coating.
  • the carving and coating phases can alter so at least partly remove parts of the just made coating to the ablation depth. This can be achieved by making the target to the substrate and/or vice versa to achieve the desired layers for the application.
  • the method comprises a phase of checking if all the coating layers were already made. That is illustrated by the arrows directed as shown in figure backwards from higher reference numerated phases to the lower reference numerated phases.
  • the body whose surface is to be carved, machined and/or coated by the cold-work can be a surface of a body per se or an already coated, or a surface at least partly coated, optionally or in addition in suitable part, such a surface that is indicated in the priority document FI20060182, to be incorporated herein by reference.
  • Fig. 5 illustrates an operation of a scanner to be used in the radiation path according to an embodiment of the invention.
  • the scanner is a conventional turbine scanner, or an improved turbine scanner 1502 according to an embodiment of the invention, i.e. with coated mirror surfaces with a high temperature tolerating reflec- tive material, or totally manufactured from carbo-nitride and/or diamond in suitable part.
  • the rotation direction is apparent in the figure.
  • the radiation source 1600 (not shown in Fig 5, but demonstrated by the beam 1510) can be embodied as a laser source embodied according to diode-pump of PDAD-system or any other cold ablation capable laser, i.e.
  • the wavelength can be in the visible light region, but is not limited to that only. Although just one drawn, there can be also two or more radiation sources, operable in the same path in parallel or in se- ries, which are not limited to the embodiment of similar source nor to that with all- different sources.
  • the radiation beam is reflected as a reflected beam 1503 via the turbine scanner 1502 mirror surface to an optical lens 1501 , to the target 1400.
  • the target can have a smooth surface structure, roughened arbitrarily or so to have a certain surface structure optimized for the ablation and the coating formation, but in an embodiment in which the target is addressed to mere carving phase, the structure of the target may be unoptimized for the carving as such.
  • the ablation path provided by the hit spots at the target is illustrated by H and the related number to illustrate also the scan on the surface of the target along the abla- tion path at the numbered points of the path. So, the H1 defines a moment when the beam 1503P, which can be polarized to a certain polarization by its production and/or the optics 1501.
  • polarization of the beam can be used for the ablation optimum at the ablation path on the target surface, espe- cially, if the polarization can be used for certain selectiveness of the ablation during a scan.
  • the Fig. 5 demonstrate the scan points H1, H2, H3, H4 and H5 which forms a series of arbitrary points from the scan path, i.e. the beam path to produce on the target 1400 surface the ablation path.
  • the scan path can be continuous, according to an embodiment, from the scanner mirror part edge to the next edge, but can be discrete according to another embodiment, as depending the exact repetition rate of the radiation source, and/or the rotation speed of the turbine scanner 1502, in a certain fixed geometry. Also the inter-point times T1, T2, T3, T4 and T5 are shown, and thus the rotation direction is demonstrated.
  • the 1503Tr illustrates the beam part, which can go through the substrate in certain embodiments, for instance if the embodiments are used for a cut into the shape application and/or with partly transparent targets.
  • the component 1503Tr thus can be used for the estimating of even each individual pulse intensities and thus for the quality monitoring.
  • the 1503Tr can be neglibly small or a zero component at the drawn side.
  • that component may be replaced an available reflection at the same side as the incoming radiation.
  • the beam 1510 formed in the radiation source meets an expander 1508, which expands the beam to tapered shape, then the collimator unit 1507 to form a curtain-like broad but thin radiation wedge to be deflected by the turbine scanner 1502, through the correction optics 1501 optionally or in addition to polari- zation operation so that the beam 1503P hit the ablation target 1400 at the H1.
  • Fig. 6 illustrates an arrangement 5700 according to an embodiment of the invention.
  • the example shown comprises a radiation source 5701 and/or another radiation source 5707.
  • the number of the sources as such is not limited only on one or two.
  • Fig. 6 also illustrates radiation path 5703 as arranged to guide radiation from a radiation source 5701 to the target 5706, to used for ablating the target material.
  • the path comprises a scanner 5704, but the number of scanners per path is not limited to the shown only.
  • the figure illustrates adapter 5702, 5705 arranged to adapt the path 5703 to the source 5701 and the target 5705, respectively.
  • the adapter can comprise an expander, contractor and/or a correction optics parts, which are necessary for the focussing in such embodiments, in which the geometrical beam shape is necessary to change in the path from the source to the target.
  • Fig.6 also embodies such variations of the arrangement 5700 in which there is also an additional source 5707 to be used in parallel and/or in addition to the source 5701.
  • the additional source can be exactly the same according to one embodiment but according to another a different one.
  • the source is a heater arranged to heat the target.
  • the adapter 5708 can be the same as 5702, but is not necessary such. It can be also an integrated adapter as an expander.
  • the scanner 5709 can be same as the scanner 5704, but is not Hm- ited only thereto.
  • the scanner is advantageously a turbine scanner according to an embodiment of the invention.
  • the adapter 5710 is arranged so that the radiation from source 5707 arrives to the target 5706, as the radiation from the source 5701.
  • the arrangement do not necessary need the adapters at all, provided that the geometry of the beam directed via the scan- ner is sufficiently uniform and/or in correct focus, above, beneath or on the surface of the target material or its base.
  • the radiation of the radiation source can be in one embodiment directed to several targets, although only 5706 shown as an example.
  • Fig. 7 illustrates a prismatic low-faced turbine scanner 3321 , but especially the ro- tor part of it 3321.
  • the part 3321 can be a conventional turbine scanner part, but also a part according to an improved embodiment of the invention, provided with at least a coating of the mirrors with high durability for the high laser power pulses.
  • the part 3321 has faces 3322, 3323, 3324, 3325, 3326,
  • the arrow 3320 illustrates the rotation of the part 3321 around the axis 3103.
  • the faces are mirrors, each of which in-duty, arranged by its own turn, to deflect the incoming radiation beam via the radiation path and to cool when the mirror is off-duty. Tilt angles of the faces are shown for various embodiments.
  • Fig. 7 illustrate one revolution of the turbine scanner part in time scale from the first mirror, mirror 1 , to the last mirror, mirror 8.
  • An ablation path on the target can be thus demonstrated.
  • the ablation path is indicated to hit the target, which can be any target to be cold-worked, at the right by reference 3329, but in the left indi- cated with the same reference number the scanning path to be used to provide the ablation path.
  • the return of the beam is indicated by the line 3330.
  • the mirrors are indicated by the apparent reference number.
  • the location of the scan line on the target material may be the same in one embodiment for at least two successive scans, but the scan line for two successive scans can be different in another embodiment, if for example, the material is likely to form fragments even in cold-work based on ablation.
  • the number of faces is not limited to the 8, which is only an example in the figure. Faces can be of tens or even hundreds in number, however, influencing possibly to the scan line length.
  • the mirrors can be also curved, although not shown in the Fig.7.
  • the corners can be rounded according to an embodiment of the invention.
  • number of different scan lines at the target surface can be achieved by variation of the tilt from face to the next face of the turbine scanner, or in another embodiment by changing the face tilt of at least one mirror or several mirrors.
  • the turbine scanner has an advantage that the beam won't stop one location at the target and thus the yield is rapid and homogenous during a scan resulting a homogenous plume from the target.
  • the size of the turbine scanner is freely scalable for a skilled man in the art who has read the application text.
  • the embodiments comprise variations of microscopic scaled to macroscopic scale so that in the macroscopic scale according to one embodiment the diameter is about 12 cm and height 5 cm.
  • the distinction of low-faced turbine scanner from a high face turbine scanner can be made by the measures of the height of the mirror in an axial direction in relation to the width of the mirror in a perpendicular direction of the axial direction. If the height and width are essentially the same, or exactly the same such an intermediate embodiment is included to either low- or high- faced embodiment according to the ratio so that if the height is smaller than the width, it is low-faced but if the height is larger than the width it is high-faced.
  • turbine scanner in the radiation path for such systems in which use pico-second laser systems whose repetition rate is above 4 MHz, advantageously over 20 MHz and/or the pulse energy is above 1 ,5 ⁇ J. It is also advantageous to control the radiation power at the hit spot on the target, according to the possibilities. Thus, even each pulse can be evaluated and the knowledge on the departures of the pulse/radiation properties from pre-defined values can be used in a feed-back loop for controlling the radiation beam focus, the ablation of target material, substrate coating, and/or the plume formation.
  • the radiation source to be used in the arrangement according to an embodiment of the invention can comprise at least one or several diode-pumped radiation sources and each radiation source can have an optical path of its own, but not necessarily the same as another.
  • the radiation is laser radiation originating to radiation source arrangement according to an embodiment.
  • a radiation source arrangement comprises a first feature and/or a second feature, which is at least one of the fol- lowing:
  • said first feature is different than said second feature.
  • said feature is considered as an aspect of a radiation source.
  • a radiation source to be used in the arrangement according to an embodiment of the invention has at least one radiation source which is arranged to produce radia- tion having a wave length in range which wave length is at least one of the following:
  • the optical path is arranged to comprise at least one path for plurality of radiation sources comprising at least one radiation source arranged to direct at least one radiation beam to a plurality of targets comprising at least one target. If an embodiment is using intermittent pulsing for the cold working, the intermittency can be arranged in periodical way by using several sources each having own period, to be superposed at the hit point of the ablation path.
  • the laser source can be embodied, optionally or in addition, in suitable part according to the priority document FI20060182 incorporated herein by reference.
  • One further example embodies a laser arrangement according to an embodiment of the invention.
  • the mentioned parameter values are examples, and are thus not restrictive only to the mentioned values.
  • the turbine scanner as embodied is only an example, and thus not restrictive.
  • Pico-second laser system A
  • Turbine scanner B
  • target feed C
  • the products can be of single crystalline diamond and/or silicon to be used as a substrate for semiconductor industry for instance, produced in vacuum, or in a gas atmosphere.
  • the coating can be formed on a surface of any kind, for example, on metal, plastics and/or paper to mention few. In one embodiment the coating has a coating layer thickness of 5 ⁇ m.
  • the semiconductor material can be a silicon as pure or as a compound, but in a flexible form, suitable into use of electronics, micro and/or nano-electronics.
  • the points D, E, F and G help the manufacturing of high quality products in industrial scale, repeatable and promote the quality control.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Laser Beam Processing (AREA)

Abstract

L'invention concerne un procédé d'écrouissage basé sur l'ablation. Ce procédé consiste à réaliser une ablation le long d'une voie d'ablation prédéfinie sur une surface cible d'ablation, à une profondeur d'ablation prédéfinie, au moyen d'un rayonnement laser présentant une longueur d'onde caractéristique et au moins une caractéristique d'impulsion pour chaque longueur d'onde pour le rayonnement à utiliser pour l'ablation du matériau cible d'ablation. Le rayonnement de la source peut être dirigé par une voie optique sur le point de travail de la cible d'ablation au moyen d'un scanneur à turbine. L'invention concerne un dispositif d'écrouissage basé sur l'ablation. Ce dispositif comprend une source de rayonnement laser qui produit le rayonnement laser destiné à être utilisé dans l'ablation et au moins un scanneur à turbine disposé dans la voie optique conçue pour acheminer le rayonnement laser de la source de rayonnement laser sur le point d'impact de la cible d'ablation à l'emplacement de la voie d'ablation. Ce dispositif peut être utilisé dans la technologie de fabrication de systèmes automatiques mais également dans la technologie des armes.
PCT/FI2007/000047 2006-02-23 2007-02-23 Procédé d'écrouissage Ceased WO2007096462A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
FI20060182 2006-02-23
FI20060182A FI20060182L (fi) 2005-07-13 2006-02-23 Ablaatiotekniikkaan liittyvä pinnankäsittelytekniikka ja pinnankäsittelylaitteisto
FI20061165 2006-12-29
FI20061165A FI20061165L (fi) 2006-02-23 2006-12-29 Kylmätyöstö

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Cited By (1)

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CN102658076A (zh) * 2012-05-11 2012-09-12 中山大学 一种微纳米材料及其制备方法、装置、应用

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US5948172A (en) * 1996-08-12 1999-09-07 Neiheisel; Gary L. Descaling metal with a laser having a very short pulse width and high average power
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EP1430987A1 (fr) * 2002-12-20 2004-06-23 Caterpillar Inc. Micro-usinage par plasma induit par laser
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US4099830A (en) * 1976-12-15 1978-07-11 A. J. Bingley Limited Optical systems including polygonal mirrors rotatable about two axes
GB2155754A (en) * 1984-03-22 1985-10-02 Gd Spa Device for piercing holes in rod-shaped items
US5948172A (en) * 1996-08-12 1999-09-07 Neiheisel; Gary L. Descaling metal with a laser having a very short pulse width and high average power
US6134041A (en) * 1998-10-17 2000-10-17 Samsung Electronics Co., Ltd. Polygonal mirror assembly, laser scanning unit for printer adopting the same, and printer
US6839156B2 (en) * 2002-09-16 2005-01-04 Samsung Electronics Co., Ltd. Laser scanning unit and electrophotographic image forming apparatus adopting the same
EP1430987A1 (fr) * 2002-12-20 2004-06-23 Caterpillar Inc. Micro-usinage par plasma induit par laser

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Publication number Priority date Publication date Assignee Title
CN102658076A (zh) * 2012-05-11 2012-09-12 中山大学 一种微纳米材料及其制备方法、装置、应用

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