WO2009019006A2 - Dispositif et procédé de réduction de taches dans le domaine des applications laser - Google Patents

Dispositif et procédé de réduction de taches dans le domaine des applications laser Download PDF

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Publication number
WO2009019006A2
WO2009019006A2 PCT/EP2008/006472 EP2008006472W WO2009019006A2 WO 2009019006 A2 WO2009019006 A2 WO 2009019006A2 EP 2008006472 W EP2008006472 W EP 2008006472W WO 2009019006 A2 WO2009019006 A2 WO 2009019006A2
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Prior art keywords
laser
axis
resonator
mirror
short
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German (de)
English (en)
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WO2009019006A3 (fr
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Dieter Grebner
Rico Fuchs
Alexander Kalies
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Carl Zeiss Meditec AG
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Carl Zeiss Meditec AG
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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
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
    • B23K26/073—Shaping the laser spot
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F9/00—Methods or devices for treatment of the eyes; Devices for putting in contact-lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
    • A61F9/007—Methods or devices for eye surgery
    • A61F9/008—Methods or devices for eye surgery using laser
    • A61F9/00802—Methods or devices for eye surgery using laser for photoablation
    • A61F9/00804—Refractive treatments
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F9/00—Methods or devices for treatment of the eyes; Devices for putting in contact-lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
    • A61F9/007—Methods or devices for eye surgery
    • A61F9/008—Methods or devices for eye surgery using laser
    • A61F9/00802—Methods or devices for eye surgery using laser for photoablation
    • A61F9/00814—Laser features or special beam parameters therefor
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F9/00—Methods or devices for treatment of the eyes; Devices for putting in contact-lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
    • A61F9/007—Methods or devices for eye surgery
    • A61F9/008—Methods or devices for eye surgery using laser
    • A61F9/00802—Methods or devices for eye surgery using laser for photoablation
    • A61F9/00817—Beam shaping with masks
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F9/00—Methods or devices for treatment of the eyes; Devices for putting in contact-lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
    • A61F9/007—Methods or devices for eye surgery
    • A61F9/008—Methods or devices for eye surgery using laser
    • A61F2009/00861—Methods or devices for eye surgery using laser adapted for treatment at a particular location
    • A61F2009/00872—Cornea
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F9/00—Methods or devices for treatment of the eyes; Devices for putting in contact-lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
    • A61F9/007—Methods or devices for eye surgery
    • A61F9/008—Methods or devices for eye surgery using laser
    • A61F9/00802—Methods or devices for eye surgery using laser for photoablation
    • A61F9/00804—Refractive treatments
    • A61F9/00806—Correction of higher orders
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/08—Construction or shape of optical resonators or components thereof
    • H01S3/08018—Mode suppression
    • H01S3/0804—Transverse or lateral modes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/08—Construction or shape of optical resonators or components thereof
    • H01S3/08059—Constructional details of the reflector, e.g. shape
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/22—Gases
    • H01S3/223—Gases the active gas being polyatomic, i.e. containing two or more atoms
    • H01S3/225—Gases the active gas being polyatomic, i.e. containing two or more atoms comprising an excimer or exciplex

Definitions

  • the invention relates to an apparatus and a method in the field of laser applications for reducing speckle.
  • speckle pattern of the laser beam is formed on the working plane and leads to inaccuracies.
  • speckles and the associated production of a smooth Strkahlprofils following solutions are known.
  • the Laser Guidbook (Author: Jeff Hecht, Copy Rights: McGraw-HiIl Ins., ISBN: 0071359672) describes a use of spherical HR stable resonators to reduce coherence, increase divergences and thus avoid speckles
  • Another disadvantage is the lack of adjustment of the beam axes to each other and the associated different divergence and coherence in the axes.
  • pulse shape and pulse duration can change in this solution.
  • WO 2004021529 A1 describes a resonator which uses spherical and aspherical hemispherical mirrors to equalize the divergence and coherence of the beam. Furthermore, it is described herein that diffusers mounted on or between the mirrors and acting only in the critical axis can solve the problem.
  • the known devices are not able to reduce the speckle occurring in the working plane, without having to accept energy losses, pulse duration changes or pulse shape changes.
  • the object of the invention is to reduce the speckle effect in the working plane and to provide a smooth beam profile.
  • a laser beam quality improvement apparatus for laser applications, comprising a laser (1) having an asymmetric beam profile and a first, short beam axis (20) and a second, long beam axis (30) and a beam propagation axis ( 35) and one
  • Laser is preferably referred to as sources which emit coherent, hardly divergent electromagnetic radiation.
  • Gas lasers particularly preferably discharge lasers of any kind, are preferably used according to the invention.
  • the gas laser most preferably used is the excimer laser.
  • Laser applications are preferably ablative or exposing laser application. This is preferably understood to mean applications which preferably interact with material in a working plane by means of pulsed jet delivery, more preferably removing material. This is preferably done in one point (spot). In addition to punctiformly focused beams (spots), large-area, homogenized beams in the working plane are also preferably understood. The resulting profile in the working plane is called the removal profile.
  • An Abtragsprofil can preferably by the known methods of Spotscannings particularly preferred by
  • Variable aperture processes most preferably also produced by mask exposure techniques.
  • Laser lithography most preferably laser micromachining, most preferably refractive surgery or other type of laser treatment are examples of ablative laser applications.
  • the laser beam quality is defined in the laser spot in this invention.
  • the laser spot is the point where the collimated laser beam hits the working plane and exerts its effect, i. Material removes.
  • the long beam axis is preferably the direction from electrode to electrode.
  • the discharge preferably proceeds in the case of discharge-pumped gas lasers.
  • the beam profile in this direction is preferably top hat-shaped.
  • the number of transverse modes in this direction is large depending on the electrode gap.
  • the coherence length is correspondingly low and usually uncritical with regard to the interference effect on microoptical elements (for example beam guides).
  • the divergence is correspondingly large.
  • the short beam axis is at right angles to the long beam axis.
  • the beam profile in this direction is preferably Gaussian.
  • the excitation concentrates on the center of the discharge according to the distribution of the discharge excitation Gauss.
  • the formation of transversal modes in this direction is correspondingly limited and their number is lower. This results in a greater coherence length in this direction, which is has a critical effect on the interference effect when using micro-optical elements.
  • the divergence is correspondingly lower in this direction.
  • Short and long beam axes are preferably formed in their properties in cooperation with micro-optical components in the working plane.
  • the interference effect and thus speckle formation preferably occurs in the critical short beam axis.
  • the short beam axis is therefore usually the more coherent beam axis when compared to the long beam axis.
  • Short and long beam axes are also preferably used for orientation on the working plane. Particularly preferably, they span the working plane as coordinate axes.
  • the convex cornea is called.
  • the beam propagation axis is preferably the axis along which the laser beam propagates.
  • Beam propagation axis is preferably perpendicular to the short and long beam axis.
  • the resonator of the laser is an optical resonator, which serves to reflect emitted light as often as possible back and forth. Due to interference, a standing wave then forms in the resonator when the optical path length of the resonator is a multiple of the wavelength of the incident light.
  • stable resonators are preferably used.
  • the beam profile preferably also forms in the removal profile, depending on the material properties of the material being processed.
  • the beam profile is considered to be asymmetric if the Beam shape (energy-power distribution over the surface) is different in both directions. This results in preferably different properties of the beam, such as coherence and divergence, along these beam directions.
  • a beam profile is asymmetric if beam shape, coherence and the resulting divergence preferably differ in the beam axes of the machining planes.
  • An optical element is preferably an element which preferably reflects at least one electromagnetic beam, particularly preferably breaks, most preferably influences the phase or amplitude of the beam.
  • imaging optics is preferably understood optics, - with which the beam, preferably in the course of a
  • Beam shaping is imaged on the processing plane to preferably a predetermined shape and size of the intensity distribution to obtain.
  • Spatial coherence refers to the ability of a light source to produce stationary interference phenomena at two different locations, but at the same time. It is the statement of the correlation of the phase of the signal at spatially separated points at the same time.
  • Time coherence refers to the ability of a light source to still produce stationary interference phenomena at a fixed location with light that has left the light source at two different times. It is the statement of the correlation of the phase of the signal at different times in the same place.
  • Divergence is the property of a beam that diverges from a center perpendicular to the propagation direction.
  • the angle of divergence is the angle that passes through the pair of straight lines which asymptotically represents the envelope of the increasing beam dimension.
  • the resonator mirror is preferably one of the two outermost mirrors in a resonator, which enclose the active medium (gain medium) with mutually directed mirror surfaces.
  • This resonator mirror is preferably an HR mirror on the non-outcoupling side, particularly preferably an OC mirror on the outcoupling side of the resonator.
  • the highly reflective mirror preferably has the highest possible degree of reflection.
  • the resonator mirrors are preferably parallel to the mirror surfaces.
  • the invention preferably has the following configurations (the form of the resonator mirror on the outcoupling side being called first, and then the shape of the resonator mirror on the noncoupling side): concave-plane, plano-concave, concave-concave.
  • the mirror surface of the concave resonator mirror is preferably cylindrical.
  • the concave mirror surface is preferably a segment of a cylinder.
  • the radius of curvature of the cylindrical inner surface is preferably 1 mm to 1000 m, more preferably 50 mm to 200 m, most preferably 10 m to 10 m.
  • the best possible adjusted radius of curvature is preferably dependent on the resonator length, the coherence and the size of the individual elements of a microoptical component.
  • Optical elements are also preferably diffractive elements such as gratings or refractive elements such as lenses, which may affect spatial coherence.
  • step structures can shift the beams temporally relative to one another and thus reduce the temporal coherence.
  • the interference effect on micro-optical elements can preferably be reduced.
  • the cylindrical mirror surface (13) of the concave resonator mirror (11) is arranged so that the curved axis of the mirror is perpendicular to the long beam axis (30) and / or perpendicular to the beam propagation axis (35) of the laser (1) ,
  • the curved axis of the mirror is the center axis of the imaginary cylinder.
  • this direction of curvature perpendicular to the long beam axis i. along the short, usually more coherent beam axis and perpendicular to the beam propagation axis
  • the coherence of the coherent short axis is reduced and the divergence in that direction is increased.
  • the energy yield remains the same, because despite the focusing by the Gaussian excitation distribution in the short axis sufficient emission is produced. For the same reason, the pulse duration and shape are retained.
  • the divergence of the beam outside the resonator preferably increases with increasing curvature of the concave mirror. This is particularly preferred in the case of cylindrical mirrors in the direction of curvature. The increase in divergence is equivalent to a reduction in spatial coherence.
  • the laser (1) is an excimer laser.
  • the excimer laser is an ultraviolet gas laser whose resonator is filled with gas.
  • the excimer laser is preferably used according to the invention since it provides an asymmetric beam profile.
  • the gases used in the resonator are preferably Fe 2 or Xe or ArF or KrF or XeBr or XeCl or XeF.
  • the excimer laser provides high UV pulse energies.
  • the optical element (10) is a homogenizer (42) and / or an integrator and / or a beam shaper.
  • a homogenizer is preferably an optical element that converts an incident intensity distribution into a changed uniform intensity distribution.
  • a beam shaper (beam shaper, beam integrator) is preferably a homogenizer, with which an incident intensity distribution is converted into an intensity distribution with a laterally predetermined shape.
  • the optical element (10) is an imaging optics (44).
  • An imaging optics is preferably at least one optical lens, more preferably parallel in-line lenses, which image the laser beam in one point.
  • the invention may preferably be with a micro-optical
  • Element particularly preferably also be used with an enlarging or reducing acting imaging optics.
  • a refractively effective beam shaper and a telescope are used to reduce image size.
  • the optical element (10) is a microoptical element (40).
  • a micro-optical element is an element which preferably lies outside the laser apparatus, particularly preferably behind the exit opening of the laser, particularly preferably in the axis of the laser beam.
  • the exiting laser beam On the properties of the Micro-optical element is preferably aligned, the exiting laser beam.
  • the adjustment of the laser beam preferably reduces the speckle effect which would occur without adaptation of the laser beam to the microoptical element.
  • the spatial coherence is preferably reduced and the divergence of a preferred excimer laser beam in the short beam direction is increased while the pulse properties (pulse energy, pulse duration, pulse shape) remain the same.
  • the disturbing speckle effect in the working plane is preferably reduced.
  • Micro-optical elements are preferably optical elements. whose geometrical dimensions are only a few orders of magnitude above the wavelength of the light transmitted through them. Due to these size ratios, the wave characteristic of the light strongly comes to the fore.
  • At least one micro-optical element 40 is a beam shaper 41 or a beam homogenizer 42 or a beam integrator 43 or an imaging optics 44.
  • the micro-optical element is a beamshaper to preferably form the radiation distribution.
  • the setting of erosive laser beams is preferably possible.
  • the micro-optical element is preferably one
  • Beam homogenizer with which irregularities in the laser beam profile are compensated and preferably a uniform beam is formed.
  • the micro-optical element is a beam integrator to preferably produce relatively flat intensity profiles of the laser beam.
  • Micro-optical devices eg, beam shaper or homogenizer or integrator
  • the micro-optical component is preferably a refractive-effective micro-optical element.
  • the microlenses have a preferred diameter of 0, l ⁇ m to 2mm, more preferably a diameter of l ⁇ m to lmm and most preferably a diameter in the range of lO ⁇ m to 600 ⁇ m.
  • the microoptical component is furthermore preferably a diffractive microoptical element with a lattice spacing of 0.1 ⁇ m to 1 mm, particularly preferably 1 ⁇ m to 500 ⁇ m, and most preferably in a range of 2 ⁇ m to 200 ⁇ m.
  • the resonator is an anamorphic stable resonator.
  • An "anamorphic stable resonator” is a stable resonator with beam axis differential effects in terms of coherence and divergence, ie, axis-dependent optimization of coherence and thus reduction of speckle in the critical, short beam axis.
  • the object of the invention is further achieved by a method for providing a smooth beam profile, ie by reducing the speckle in the working plane, wherein a laser beam with asymmetric beam profile comprising a first, short beam axis (20) and a second, long beam axis (30) provided and the spatial coherence is reduced and / or the divergence of the short beam axis of the laser beam is increased.
  • laser beams are optimized by this method so that they form a smooth beam profile.
  • a precise material removal is preferably made possible during refractive surgery.
  • a smooth beam profile preferably has no "outliers" in the profile section of the laser spot, but preferably a slight deviation in shape and roughness with respect to the desired beam profile
  • the profile section is most preferably preferably Gaussian, and profile shapes such as top hat are also preferred ,
  • Smooth beam profiles are particularly preferred in refractive corneal surgery.
  • smooth steel profiles are used in lithography or micromachining.
  • lasers are used in this invention, which are preferably pumped by two opposing electrodes and / or form an asymmetric beam profile.
  • the long beam axis is the distance from electrode to electrode, the short beam axis is at right angles to the long beam axis.
  • the reduction of the spatial coherence and / or increase in the divergence of the short beam axis of the laser beam is preferably generated by a concave cylindrical resonator mirror.
  • the laser beams of the short beam axis are preferably collimated. Due to the preferred Gaussian excitation distribution in this axis is sufficient Emission and only a slight reduction in energy yield.
  • the reduction in spatial coherence and / or increase in divergence is due to the increase in the number of transverse modes due to the changed resonator arrangement.
  • the focused laser beams preferably strike one point. This point is called a spot.
  • the spot is the site of intervention, for example during an operation.
  • material is preferably removed.
  • a method is provided, wherein the laser beams with an imaging optical system (44) is imaged on a working plane (45), an examination of the existing speckle pattern is carried out, an adaptation of the radii of curvature of the resonator mirror (11) takes place, the spatial Coherence and / or increase in the divergence of the short beam axis (20) of the laser beam is further reduced, rechecking of the speckle pattern is performed.
  • Imaging optics is preferably understood to mean an optic with which the beam, preferably in the course of beam shaping, is imaged onto the working plane in order to preferably obtain a predetermined shape and size of the intensity distribution.
  • the beam is preferably imaged in the focus.
  • the test surface is a surface that allows the beam profile to be examined.
  • a profile section through the spot can preferably be represented visually, particularly preferably calculated.
  • a beam observation system is positioned in the working plane. The examination of the incident laser beam in the working plane and thus the analysis of the speckle pattern can preferably be accomplished automatically with known methods and systems.
  • the method of moving slit is used.
  • a slit diaphragm with the smallest possible slit width (with respect to the beam size) in the working plane is moved through the laser beam step by step, and the energy measured after the iris with an energy detector.
  • the aperture positioning can preferably be ensured via automatic translation stages with stepper motor. The energy is thus split into small location-dependent parts, and one obtains the spatial fluence distribution of the
  • Laser beam the beam profile, as well as the speckle pattern.
  • the beam profile with recognizable speckle pattern is preferably stored in digital form.
  • the method of beam testing and / or speckle pattern testing by means of a beam camera is particularly preferably used.
  • the beam is e.g. via a beam splitter in a suitable direction coupled to the beam camera.
  • the beam may be necessary to make a frequency conversion to make the beam visible to the camera chip.
  • a 193nm laser beam is preferred for a
  • Fluorescence disc used.
  • the image of the laser beam must lie in the working plane.
  • the fluorescent light is imaged by a lens on the camera chip (usually CCD or CMOS) and can be stored digitally.
  • the digitized beam profiles and / or speckle patterns of both preferred measurement methods are preferably mathematically analyzed.
  • the roughness is preferably determined as the difference of a fit function with the measured data.
  • the roughness is then preferably a measure of the strength of the speckle effect and can preferably be reduced iteratively in the process according to the invention.
  • the beam is thus visually inspected for speckle.
  • the beam observation system preferably also checking other laser parameters such as energy, pulse duration, pulse shape can be monitored. This ensures preferably that the bacon effect is minimized with only minimal influence on the other laser parameters.
  • the beam profile preferably offers the possibility of representing the possible speckle pattern of the beam, if the beam profile or the spot profile is not smooth, a speckle pattern is formed.
  • the resonator elements By adapting the resonator elements, preferably by changing the radius of curvature of one or both resonator mirrors, it is possible to influence the spatial coherence and / or the increase in the divergence of the short beam axis of the laser beam. This is preferably carried out iteratively until the speckles no longer occur. As a result, the beam or the spot profile is preferably optimized.
  • Another test identical to the first test described above, checks the beam quality again.
  • a method which images the laser beam with a wavelength of 193 nm onto the cornea, scans the laser beam over the cornea with a pulse duration of 4 to 15 ns, removes refraction-improved profiles with reduced roughness and optimized form fidelity and with energy in the Range from 0.5 mJ to 1.5 mJ.
  • lasers with a wavelength of 193 nm are used, which depart from the cornea of the eye.
  • a spot scanning method is used for scanning the cornea, wherein the laser beam preferably used is reduced in size in the working plane (cornea).
  • the reduced beam image is preferably referred to as a spot.
  • the laser beam with a preferred pulse duration of 4 to 15 ns is preferably moved across the cornea by means of lateral beam deflecting optics (preferably Galvoscanner).
  • the spot is preferably the location where the laser beam interacts with the matter (the corneal tissue).
  • the preferred crossing of a minimum energy surface density (Schwellfluence) leads to the ablation of tissue.
  • the energy range is preferably 0.5 mJ - 1.5 mJ.
  • Ablation is preferably referred to as non-thermal molecule decomposition, in which the material is removed. By distributing many such spots over the cornea, this can be changed by ablation
  • the size of the beam during the treatment is preferably varied via diaphragms and variable diaphragms in order to obtain a removal which alters the refractive properties of the cornea.
  • the method according to the invention preferably leads to smoother, more faithful removal profiles when used in refractive corneal surgery. Improved smoothness may cause the formation of haze (clouding) as a result of
  • Invention used in a method for micromachining. Particularly preferred among these methods are applications such as patterning, cutting, drilling and structuring.
  • materials such as ceramics, glass and polymers are preferably processed.
  • the laser beam in the working plane interacts with these materials. If the laser exceeds a minimum energy surface density in the working plane, non-thermal ablation of the materials occurs. Preferred are with these methods
  • Inkjet heads masks and fiber structures generated.
  • the roughness can be significantly reduced and the dimensional accuracy of the structures produced can be improved.
  • Fig. 1 is a schematic representation of a laser
  • Fig. 2a, 2b a laser spot with profile section without
  • Fig. 3a, 3b a laser spot with profile section with inventive device.
  • 4a, 4b, 4c are three-dimensional views of
  • 6a, 6b is a schematic representation of the pulse curve with a curved resonator mirror.
  • FIG. 1 shows a schematic representation of a laser.
  • the excimer laser 1.1 comprises a resonator 60 filled with excimer gas.
  • the resonator are two parallel resonator 11.1 and 11.2 opposite, wherein the resonator mirror 11.2 on the output side and
  • Resonator mirror 11.1 is on the non-decoupling side.
  • Resonator mirror 11.2 is a planar resonator mirror.
  • Resonator mirror 11.1 is a concave highly reflective mirror 12 with a cylindrical mirror surface 13.
  • the side of the resonator 60 are the electrodes 70.1 and 70.2. 70.1 and 70.2 are arranged so that they are parallel to each other and perpendicular to the direction of curvature of the cylinder mirror.
  • the micro-optical element 41 is in the beam direction in front of the imaging optics 44, in front of the processing plane 45. 41,44 and 45 are arranged so that the emerging laser beam is imaged on the processing plane 45 in the desired manner.
  • output energies at the laser source of not greater than 50 ⁇ m, more preferably 10 ⁇ m and very particularly preferably less than 2 ⁇ m, and machining energies (in the working plane) are preferred 10 ⁇ J to 15mJ, more preferably from 0, ImJ to 5mJ and most preferably from 0.5mJ to 1.5mJ.
  • a wavelength in the UV range is used, preferably 150 nm to 250 nm, particularly preferably 180 nm to 200 nm. It is particularly preferred ArF used as Excimergas. It will be one
  • Pulse duration in the range of preferably less than 2 ⁇ s, more preferably used 0.1ns to 50ns, most preferably in the range of 3ns to 8ns. It is preferably used a Gaussian beam shape to make the removal of composite spots smoother. It is preferably a
  • Beam size used in FWHM Frill Width at Half Maximum range of less than 5mm, more preferably in the range of lO ⁇ m to 2.5mm, most preferably from 0.5 to 1.5mm. It is a pulse repetition rate in the range of preferably IHz to 5kHz, more preferably from 5Hz to IkHz, most preferably from 10Hz to 500Hz used.
  • a pulse repetition rate in the range of 1 Hz to 10 kHz is particularly preferred in the range of 500 Hz to 5 kHz, very particularly preferably in the range of 1 kHz to 4 kHz.
  • a wavelength in the UV range is used, preferably 150 nm to 250 nm, particularly preferably 180 nm to 200 nm. And most preferably in the range of 240nm to 260nm.
  • the excimer laser gas is preferably ArF, and more preferably KrF.
  • a pulse duration in the range of preferably less than 2 ⁇ s, more preferably 0.1 ns to 50 ns, very particularly preferably in the range of 5 ns to 25 ns is used.
  • Energys of 0.1mJ / cm_ to 10J / cm_, more preferably 0, lJ / cm_ to 5J / cm_ are used.
  • the ignition voltage for the gas discharge is generated by the electrodes 70.1 and 70.2.
  • the gas discharge provoked by the two opposite electrodes 70.1 and 70.2, leads to the development of an asymmetric beam profile.
  • the short beam axis 20 of the laser 1 has a greater coherence and a smaller divergence than the long beam axis 30.
  • the curvature of the resonator mirror 12 lies along the short beam axis 20 of the laser 1.
  • the coherence of the coherent short axis 20 is reduced and the divergence in this direction is increased.
  • the energy yield and pulse duration / shape remain the same because, despite focusing by the Gaussian excitation distribution in the short axis, sufficient emission is produced.
  • the thus changed laser beam now exits through the OC mirror 11.2 and hits first the micro-optical element 41, then the imaging optics 44 and then the processing plane 45.
  • the task of the micro-optical element is to homogenize the beam in the working plane and / or to provide the desired beam shape.
  • the imaging optics has the task of scaling the beam in the working plane to the desired size.
  • FIG. 2 a shows a laser spot 2 of a laser beam on a working plane 45 according to the prior art. You can see a spot 2 with a non-homogeneous border. That in the focused laser beam interference occur which lead to a speckle effect in the spot 2. This structure would be mapped on the machined material during removal.
  • FIG. 2b shows a profile section 3 of the "rough" laser beam in spot 2, from FIGURE 2a.
  • the profile section clearly shows an inhomogeneous, non-Gaussian distribution.
  • a laser spot 2 of a laser beam bundle according to a device according to the invention is placed on a laser beam
  • FIG. 4 a shows an embodiment of the resonator according to the invention.
  • the resonator mirrors 11.1 as a highly reflecting mirror and 11.2 as a coupling-out mirror face each other with the reflecting surfaces and enclose the active medium 80.
  • 11.1 is a concave mirror 12 with a cylindrical mirror surface 13.
  • 11.2 is a flat surface.
  • the axis 30 is the axis between the electrodes that is the direction of the discharge.
  • the axis 30 is the long beam axis.
  • the axis 20 is the short beam axis and is perpendicular to 30.
  • the axes 30 and 20 span a plane on which the axis 35 is perpendicular.
  • the axis 35 is the optical axis of the beam.
  • the discharge voltage discharges, producing a top-hat shaped excitation and beam profile.
  • a Gaussian similar excitation and beam profile is formed.
  • the laser beam propagates.
  • FIG. 4b shows an embodiment of the resonator according to the invention.
  • the resonator mirrors 11.1 as a highly reflecting mirror and 11.2 as a coupling-out mirror face each other with the reflecting surfaces and enclose the active medium 80.
  • 11.1 is a mirror with a flat surface.
  • 11.2 is a domed mirror with a cylindrical mirror surface.
  • the Axis 30 is the axis between the electrodes that is the direction of discharge.
  • the axis 30 is the long beam axis.
  • the axis y is the short beam axis and is perpendicular to 30.
  • the axes 30 and 20 span a plane on which the axis 35 is perpendicular.
  • the axis 35 is the optical axis of the beam.
  • the discharge voltage In the direction of the axis 30 discharges the discharge voltage with a top hat-shaped excitation and beam profile is formed. Perpendicular to the discharge direction, i. in the direction of axis 20, a Gaussian similar excitation and beam profile is formed. In the direction of axis 35, the laser beam propagates.
  • FIG. 4c shows an embodiment of the resonator according to the invention.
  • the resonator mirrors 11.1 as a highly reflecting mirror and 11.2 as a coupling-out mirror face each other with the reflecting surfaces and enclose the active medium 80.
  • 11.1 is a concave mirror 12 with a cylindrical inner surface 13.
  • Mirror 11.2 is also curved outward and has a mirror surface 13.
  • the axis 30 is the axis between the electrodes so the direction of discharge.
  • the axis 30 is the long beam axis.
  • the axis 20 is the short beam axis and is perpendicular to 30.
  • the axes 30 and 20 span a plane on which the axis 35 is perpendicular.
  • the axis 35 is the optical axis of the beam.
  • the discharge voltage In the direction of the axis 30 discharges the discharge voltage with a top hat-shaped excitation and beam profile is formed. Perpendicular to the discharge direction, i. in the direction of axis 20, a Gaussian similar excitation and beam profile is formed. In the direction of axis 35, the laser beam propagates.
  • FIG. 5a a resonator 60, viewed from the direction of the axis 20, is shown. Furthermore, the figure shows an HR Mirror 11.1 and a coupling-out mirror 11.2.
  • the long beam axis 30 lies along the direction of discharge between the electrodes.
  • the concave cylindrical mirror is not curved according to the device according to the invention in this direction.
  • the intensity distribution of the laser beam in the direction of the axis 30 is top-hat-shaped according to the discharge distribution.
  • Axis 35 is the propagation direction of the laser beam, i. the optical axis.
  • FIG. 5b a resonator 60, viewed from the direction of the axis 30, is shown. Furthermore, the figure shows an HR mirror 11.1 and a coupling-out mirror 11.2.
  • the short beam axis 20 is perpendicular to the direction of discharge between the electrodes 70.1 and 70.2.
  • the concave cylindrical mirror 11.1 is curved according to the device according to the invention in this direction.
  • the intensity distribution of the laser beam is similar according to the discharge distribution Gauss.
  • Axis 35 is the propagation direction of the laser beam, i. the optical axis.
  • FIG. 6 a shows a representation of the pulse progression 100 when using a curved resonator mirror 11. 1 in the long beam axis 30.
  • FIG. 6b shows a representation of the pulse progression 100 when using a curved resonator mirror 11.1 in the short beam axis 20.
  • the limitation of the range of the feedback by the curved mirror 11.1 has less influence in the Gaussian discharge distribution. Since the majority of the population inversion is used, in this case, no change in the pulse duration and shape of the pulse course 100 is induced. This effect is used in the device according to the invention.
  • Figures 6a and b show the effect of curved resonator mirrors on the beam axes.
  • Spherical mirrors would cause a pulse change according to FIG. 6a.
  • the cylindrical, concave mirror of the device according to the invention (curved only in the short axis and effective) a pulse duration change can be avoided.

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Abstract

La présente invention concerne un dispositif d'amélioration de la qualité de rayons laser pour les applications de retrait, comprenant un laser (1) avec un profil de rayonnement asymétrique, comprenant un premier axe de rayonnement court (20), un deuxième axe de rayonnement long (30), et comprenant au moins un élément optique (10) et/ou un miroir résonateur (11) avec une surface de miroir cylindrique (13) pour la réduction de la cohérence spatiale et/ou l'accroissement de la divergence dans l'axe de rayonnement court.
PCT/EP2008/006472 2007-08-06 2008-08-06 Dispositif et procédé de réduction de taches dans le domaine des applications laser Ceased WO2009019006A2 (fr)

Applications Claiming Priority (4)

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DE102007036988.5 2007-08-06
DE102007036988 2007-08-06
DE102008035898A DE102008035898A1 (de) 2007-08-06 2008-07-31 Vorrichtung und Verfahren zur Specklereduktion im Bereich der Laseranwendungen
DE102008035898.3 2008-07-31

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WO2009019006A3 WO2009019006A3 (fr) 2009-04-16

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107851955A (zh) * 2015-08-19 2018-03-27 极光先进雷射株式会社 激光装置
US10667949B2 (en) 2015-10-21 2020-06-02 Amo Development, Llc Laser beam calibration and beam quality measurement in laser surgery systems
CN116616996A (zh) * 2022-02-18 2023-08-22 施温德眼科技术解决方式有限公司 用于眼睛治疗的治疗设备、方法、计算机程序和计算机可读介质

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DE102011102166A1 (de) * 2011-05-20 2012-11-22 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren zu Homogenisierung des Laserstrahlprofils bei Prozessen unter Einsatz eines flüssigkeitsstrahlgeführten Lasers und entsprechende Vorrichtung
DE102022107633B3 (de) 2022-03-30 2023-06-15 Carl Zeiss Smt Gmbh Optisches System, insbesondere für die Mikrolithographie, sowie Verfahren zum Betreiben eines optischen Systems

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JP2531788B2 (ja) * 1989-05-18 1996-09-04 株式会社小松製作所 狭帯域発振エキシマレ―ザ
DE4225781A1 (de) 1992-08-04 1994-02-10 Lambda Physik Gmbh Laser mit einem instabilen Resonator
US5684822A (en) 1994-11-17 1997-11-04 Cymer, Inc. Laser system with anamorphic confocal unstable resonator
JP4154003B2 (ja) * 1996-10-01 2008-09-24 キヤノン株式会社 露光装置及びデバイス製造方法
AU7821898A (en) * 1997-07-01 1999-01-25 Cymer, Inc. Very narrow band laser with unstable resonance cavity
US5946337A (en) 1998-04-29 1999-08-31 Lambda Physik Gmbh Hybrid laser resonator with special line narrowing
SE0202584D0 (sv) 2002-09-02 2002-09-02 Micronic Laser Systems Ab A Method and device for coherence reduction
EP1722449B1 (fr) * 2005-05-12 2008-10-22 Innovavent GmbH Utilisation d'un laser à disque pour la cristallisation des couches de silicium

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107851955A (zh) * 2015-08-19 2018-03-27 极光先进雷射株式会社 激光装置
US10447001B2 (en) * 2015-08-19 2019-10-15 Gigaphoton Inc. Laser unit
US10667949B2 (en) 2015-10-21 2020-06-02 Amo Development, Llc Laser beam calibration and beam quality measurement in laser surgery systems
US11896526B2 (en) 2015-10-21 2024-02-13 Amo Development, Llc Laser beam calibration and beam quality measurement in laser surgery systems
CN116616996A (zh) * 2022-02-18 2023-08-22 施温德眼科技术解决方式有限公司 用于眼睛治疗的治疗设备、方法、计算机程序和计算机可读介质

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