EP0783782A2 - Lasers ameliores - Google Patents

Lasers ameliores

Info

Publication number
EP0783782A2
EP0783782A2 EP96917639A EP96917639A EP0783782A2 EP 0783782 A2 EP0783782 A2 EP 0783782A2 EP 96917639 A EP96917639 A EP 96917639A EP 96917639 A EP96917639 A EP 96917639A EP 0783782 A2 EP0783782 A2 EP 0783782A2
Authority
EP
European Patent Office
Prior art keywords
polarization
azimuthal
laser
radial
output
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
EP96917639A
Other languages
German (de)
English (en)
Other versions
EP0783782A4 (fr
Inventor
Avigdor Zajdman
Genady Klumel
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.)
Optomic Lasers Ltd
Original Assignee
Optomic Lasers Ltd
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
Application filed by Optomic Lasers Ltd filed Critical Optomic Lasers Ltd
Publication of EP0783782A4 publication Critical patent/EP0783782A4/fr
Publication of EP0783782A2 publication Critical patent/EP0783782A2/fr
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/07—Construction or shape of active medium consisting of a plurality of parts, e.g. segments
    • H01S3/073—Gas lasers comprising separate discharge sections in one cavity, e.g. hybrid lasers
    • H01S3/076—Folded-path lasers
    • 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
    • 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
    • H01S3/08054—Passive cavity elements acting on the polarization, e.g. a polarizer for branching or walk-off compensation
    • 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
    • H01S3/081—Construction or shape of optical resonators or components thereof comprising three or more reflectors

Definitions

  • the general field of the invention is in the improvement of industrial high power lasers for materials processing applications and more specifically provides methods to control the mode of high power lasers using stable resonators to improve their metal cutting and welding performance.
  • the three primary laser characteristics that determine its performance are: the output power, beam quality, beam polarization.
  • laser beams with either random or linear polarization do not perform well in metal cutting and welding applications (see, e.g., Ref. 1).
  • Beams with circular polarization typically perform much better (Ref. 1), and therefore the polarization of a laser is often circularized, typically outside of the laser cavity, to improve its metal processing performance. This is necessary since there is no technique known today to produce a circularly polarized beam inside the laser cavity.
  • the present invention is based on our discovery that axisymmetric polarized beams can be produced effectively, by following certain techniques described in the following.
  • the novel lasers produce azimuthally or radially polarized beams, optionally with extra- cavity treatment, exhibit excellent materials processing performance.
  • a.Polarization selective reflectors and coatings which are optical elements within the resonator and which reflect different polarizaitions at different intensity and/or percentage.
  • Fig. 1 is a sectional side view of a laser system of the invention
  • Fig. 2 is a sectional side view of another laser of the present invention.
  • Figures 3a and 3b illustrate mirror arrangements resulting in polarized laser beams.
  • Figure 1 shows an annular laser system, similar to that described in Ref. 2, corresponding to EP 0 390 013 Bl the laser output beam produced by this configuration in a TEM 01 . mode, which can be azimuthally polarized or radially polarized or have a polarization which is any combination of the two.
  • a beam that is azimuthally polarized is produced. This is according to 4 the different reflective properties of the copper regarding the P and S linear polarizations. We verified this by using a polarizer/analyzer technique, placing a polarizer in the output beam paths of C0 2 lasers built essentially along the guidelines of Ref.
  • Figure 2 shows an annular laser, similar to the configuration in Figure 1, without polarization selective coating, but with an addition of a transparent conical part, 21, (for a C0 2 laser this part is made of ZnSe or other suitable material).
  • the angle of the cone is the Brewster angle.
  • the laser will operate with a preferred radial polarization that is also compatible with the TEM 01 . mode.
  • the mirror arrangement shown in Figure 3 a (1) comprises a mirror 31 which reflects beam 32 by an angle of 90° and this is incident on mirror 33 which is not in the same plane as mirror 31.
  • the same arrangement, viewed along arrow 34 is shown in Figure 3a(2) where the mirrors are again not in the same plane.
  • FIG. 3a A complimentary system that can be used to convert radial polarization into azimuthal polarization or vice versa is presented schematically in Figure 3a.
  • This utilizes a pair of half-wave phase-retarding mirrors(or plates).
  • the first mirror is mounted at 45° to the beam direction, reflecting it at 90°.
  • the second mirror is mounted at 45° to the direction of the reflected beam, and its plane is not parallel to the plane of the first mirror, but is inclined to it at 45°.
  • a radially polarized beam passing through such arrangement will become azimuthally polarized.
  • the same arrangement can turn an azimuthally polarized beam into a radially polarized beam.
  • FIG. 3b Another 4-mirror arrangement is illustrated with reference to Figure 3b.
  • the ray 35 is reflected by mirrors 36, 37, 38 and 39 as shown.
  • the same mirrors are illustrated in Figure 3b(2), where the angle between mirrors 36 and 37 is equivalent to that of mirror 31 of Figure 3a(l), and mirrors 38 and 39 are the equivalent of mirror 33 of Figure 3a( 1) .
  • Figure 3b depicts an alternative arrangement to achieve the same polarization conversion, that utilizes a pair of quarter-wave phase retarder instead of each single half-wave retarder.
  • the advantage of this arrangement over the former one is that the beam exists in a direction parallel to the original beam direction.
  • the system and methods described differ significantly from the well-known systems and methods whereby linear polarization that can be generated in other industrial lasers is converted into a circular polarization.
  • the polarization is axisymmetric, either azimuthal or radial.
  • the necessity to create an axisymmetric polarized beam stems from the requirement of homogenous material processing in all directions.
  • the capability to generate laser beams with time-constant axisymmetric polarizations enables their judicious usage to optimize different industrial applications, such as high- quality, high-speed cutting of highly-reflective materials, deep penetration welding etc.
  • excellent cutting speeds and quality have been achieved with bare aluminum and bare copper, as well as with mild steel and stainless steel.
  • butt welding in stainless steel has been achieved with deeper penetration and higher speeds than was reported for other lasers with similar power, which did not have either azimuthal or radial polarization.

Landscapes

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

Abstract

Cette invention concerne des lasers de grande puissance, à usage industriel, et utilisés essentiellement dans le domaine du traitement des matériaux, lesquels lasers possèdent une cavité laser annulaire ainsi qu'un système (16) de génération de faisceau laser polarisé à symétrie d'axes. Les miroirs coniques peuvent être des miroirs coniques tronqués (20) ou des miroirs coniques tronqués en forme de W (18) qui possèdent un revêtement sélectif. Cette invention concerne également un procédé de production d'un faisceau laser ayant des polarisations azimutale et radiale préférées, à l'aide de miroirs coniques d'intracavité ou de leurs équivalents.
EP96917639A 1995-06-12 1996-06-11 Lasers ameliores Ceased EP0783782A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
IL11412095A IL114120A0 (en) 1995-06-12 1995-06-12 Improved lasers
IL11412095 1995-06-12
PCT/IL1996/000009 WO1996042128A2 (fr) 1995-06-12 1996-06-11 Lasers ameliores

Publications (2)

Publication Number Publication Date
EP0783782A4 EP0783782A4 (fr) 1997-04-09
EP0783782A2 true EP0783782A2 (fr) 1997-07-16

Family

ID=11067600

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96917639A Ceased EP0783782A2 (fr) 1995-06-12 1996-06-11 Lasers ameliores

Country Status (4)

Country Link
EP (1) EP0783782A2 (fr)
AU (1) AU6014396A (fr)
IL (1) IL114120A0 (fr)
WO (1) WO1996042128A2 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19747060A1 (de) * 1997-10-24 1999-05-06 Trumpf Lasertechnik Gmbh Laserresonator mit konischem Spiegel
US7019902B2 (en) * 2002-10-21 2006-03-28 Trumpf Inc. Beam forming telescope with polarization correction
EP1791229A1 (fr) * 2005-11-25 2007-05-30 Lambda Research Optics Europe Méthode pour réduire les effets thermiques d'une lentille de découpe

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4516244A (en) * 1983-09-01 1985-05-07 Rockwell International Corporation Common-pass decentered annular ring resonator with improved polarization control
EP0390013A2 (fr) * 1989-03-28 1990-10-03 Optomic Technologies Corporation Ltd. Système à laser
US5375130A (en) * 1993-05-13 1994-12-20 Trw Inc. Azimuthal and radial polarization free-electron laser system

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD256439A3 (de) * 1986-01-09 1988-05-11 Halle Feinmech Werke Veb Verfahren zur steuerung der inneren und unterdrueckung der aeusseren strahlungsrueckkopplung eines co tief 2-hochleistungslasers

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4516244A (en) * 1983-09-01 1985-05-07 Rockwell International Corporation Common-pass decentered annular ring resonator with improved polarization control
EP0390013A2 (fr) * 1989-03-28 1990-10-03 Optomic Technologies Corporation Ltd. Système à laser
US5375130A (en) * 1993-05-13 1994-12-20 Trw Inc. Azimuthal and radial polarization free-electron laser system

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO9642128A2 *

Also Published As

Publication number Publication date
IL114120A0 (en) 1995-10-31
AU6014396A (en) 1997-01-09
WO1996042128A3 (fr) 1997-02-13
EP0783782A4 (fr) 1997-04-09
WO1996042128A2 (fr) 1996-12-27

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