FR2737311A1 - Control of laser beam for industrial surface cleaning - has laser beam transmitted inside articulated arm, with mirrors at joints and optical imaging unit carried at free end of arm - Google Patents

Control of laser beam for industrial surface cleaning - has laser beam transmitted inside articulated arm, with mirrors at joints and optical imaging unit carried at free end of arm Download PDF

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Publication number
FR2737311A1
FR2737311A1 FR9509192A FR9509192A FR2737311A1 FR 2737311 A1 FR2737311 A1 FR 2737311A1 FR 9509192 A FR9509192 A FR 9509192A FR 9509192 A FR9509192 A FR 9509192A FR 2737311 A1 FR2737311 A1 FR 2737311A1
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FR
France
Prior art keywords
laser
management
arm
optical
target
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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.)
Pending
Application number
FR9509192A
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French (fr)
Inventor
Jean Pierre Treton
Gilles Brassart
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BM IND
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BM IND
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Filing date
Publication date
Application filed by BM IND filed Critical BM IND
Priority to FR9509192A priority Critical patent/FR2737311A1/en
Publication of FR2737311A1 publication Critical patent/FR2737311A1/en
Pending legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/08Devices involving relative movement between laser beam and workpiece
    • B23K26/0869Devices involving movement of the laser head in at least one axial direction
    • B23K26/0876Devices involving movement of the laser head in at least one axial direction in at least two axial directions
    • B23K26/0884Devices involving movement of the laser head in at least one axial direction in at least two axial directions in at least in three axial directions, e.g. manipulators, robots
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B08CLEANING
    • B08BCLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B7/00Cleaning by methods not provided for in a single other subclass or a single group in this subclass
    • B08B7/0035Cleaning by methods not provided for in a single other subclass or a single group in this subclass by radiant energy, e.g. UV, laser, light beam or the like
    • B08B7/0042Cleaning by methods not provided for in a single other subclass or a single group in this subclass by radiant energy, e.g. UV, laser, light beam or the like by laser

Abstract

The laser beam control is implemented by a moving arm with multiple articulated segments (1-8) carrying an optical unit to form an image of the laser output on the target surface. The articulated arm has mirrors at the junctions to transmit the laser beam inside the arm. The optical device at the free end of the arm incorporates a converging lens and a focus zoom. The arms carrying the laser beam may be evacuated or filled with an inert gas or with air, from which the dust has been removed. The laser emitters have Fourier or multi-mode transform cavities forming the uniform surface densities which are enlarged and delivered to the surface to be processed.

Description

Le dispositif de gestion de faisceau selon l'invention, remédie aux inconvénients de la propagation des champs électro-magnétiques qui modifie la densité surfacique de puissance des ondes des lumières cohérentes. Dans l'approximation des amplitudes lentement variables, et des faisceaux faiblement inclinés sur l'axe Z de propagation, le champ életro-magnétique d'une onde lumineuse s'exprime par: E = (x, y, z) = 'Y (x, y, z). exp - i (ot knz) où x et y sont les coordonnées transverses du faisceau, w et k sont respectivement la pulsation de l'onde et le module du vecteur d'onde, n est l'indice de réfraction du milieu et 'I'(x, y, z) désigne l'amplitude complexe telle que:: 'I'(x, y, z) = 'Il (x, y, z = o) * Gr (x, y, z) qui exprime un produit de convolution sur les coordonnées transverses entre l'amplitude à l'origine z = o et la fonction de Green telle que:
ikn
Gr (x, y) = - - . exp ikn (z + (x2 + y2)/2z)
2J1z la quantité ss v (x, y, z) 1 2 est interprétée comme la densité surfacique de puissance. Le mathématicien sait par ailleurs que seules les amplitudes gaussiennes des champs électro-magnétiques se propagent sans déformer la densité surfacique de puissance. La déformation, pour des amplitudes quelconques, s'étudie par les transformations de
Fourier.Dans de nombreuses applications, notamment dans le nettoyage industriel par photoablation laser, le procédé d'interaction entre le champ électro-magnétique et la matière nécessite une densité surfacique de puissance homogène et constante sur toute la section du faisceau. La physique précédemment décrite montre que cette situation réalisée à l'abscisse z=o ne peut pas être conservée pour une autre abscisse dans une simple propagation libre du faisceau.
The beam management device according to the invention overcomes the disadvantages of the propagation of electromagnetic fields which modifies the surface power density of coherent light waves. In the approximation of slowly varying amplitudes, and of weakly inclined beams on the Z axis of propagation, the electromagnetic field of a light wave is expressed by: E = (x, y, z) = 'Y ( X Y Z). exp - i (ot knz) where x and y are the transverse coordinates of the beam, w and k are respectively the wave pulsation and the wave vector modulus, n is the refractive index of the medium and I '(x, y, z) denotes the complex amplitude such that ::' I '(x, y, z) =' Il (x, y, z = o) * Gr (x, y, z) which expresses a convolution product on the transverse coordinates between the amplitude at the origin z = o and the function of Green such that:
ikn
Gr (x, y) = - -. exp ikn (z + (x2 + y2) / 2z)
2J1z the quantity ss v (x, y, z) 1 2 is interpreted as the surface density of power. The mathematician also knows that only the Gaussian amplitudes of the electromagnetic fields propagate without deforming the surface density of power. The deformation, for any amplitudes, is studied by the transformations of
Fourier.In many applications, especially in the industrial cleaning by laser photoablation, the interaction process between the electromagnetic field and the material requires a surface density of homogeneous and constant power over the entire section of the beam. The physics previously described shows that this situation realized at the abscissa z = o can not be preserved for another abscissa in a simple free propagation of the beam.
Le dispositif de gestion de faisceau selon l'invention permet par transport d'image de conserver une densité surfacique de puissance homogène et constante sur la cible dès lors où cette densité présente une telle qualité en sortie d'émetteur-laser. Par ailleurs et subséquemment le dispositif assure à la gestion de faisceau, une meilleure stabilité spatiale. Le dispositif est composé d'une part, d'un bras articulé à miroirs totalement réfléchissant à la longueur d'onde du laser et d'autre part, d'un équipage optique placé à l'intérieur du bras qui image optiquement le plan du miroir de sortie de l'émetteur-laser et le plan de l'échantillon.The beam management device according to the invention makes it possible, by image transport, to maintain a surface density of homogeneous and constant power on the target as soon as this density has such a quality at the laser emitter output. Moreover and subsequently the device provides the beam management, a better spatial stability. The device is composed on the one hand, of an articulated arm with mirrors totally reflecting at the wavelength of the laser and on the other hand, of an optical equipment placed inside the arm which optically image the plane of the laser. output mirror of the laser-emitter and the sample plane.
Selon la figure n" 1, le bras articulé est constitué par exemple, autour de six degrés de liberté. Deux tiges cylindriques creuses (1 & 2) sont associées par une jonction rotative (3) à deux miroirs sous 450 d'incidence. Le fût du bras (4) est fixé sur l'embrase (5) qui figure le plan de sortie de l'émetteur-laser et est relié à la tige (2) par la jonction rotative (6) à deux miroirs sous 45" d'incidence. Le poignet du bras (7) est constitué par une jonction double à trois miroirs sous 450 d'incidence et d'un embout (8) qui peut recevoir une poignée pour le maintien.La cible (9) sur laquelle se fait l'interaction, est située à une distance de la sortie de l'embout dont les valeurs minimum et maximum sont indiquées à l'utilisateur par un senseur inclus dans l'embout. L'utilisation d'un bras articulé dont le nombre de degrés de liberté serait différent de six ne sortirait pas de l'invention. L'équipage optique placé à l'intérieur du bras image le plan de l'embase (5) avec le plan moyen de la cible (9). Cet équipage est constitué par exemple, et selon la figure n" 2, par une lentille convergente (10) dont la longueur de la focale f est choisie de façon à ce que l'image du plan de l'embase (5) soit située à l'entrée du poignet (7) avec un grandissement g. Si L est la distance comprise entre le plan objet et le plan image, la relation entre f, L et g est la suivante g).L/(1-g)2 (avec g < o)
Si Z est la distance comprise entre le plan objet et le plan dans lequel se trouve la lentille, la relation entre Z, L et g est la suivante Z=L/(1 -g)
En application, pour un grandissement de - 0,5, la lentille convergente a une focale f = L/4,5 et Z est égale à L/1,5. Le passage au foyer se fait à une distance de
L/1,125 à partir du plan de l'embase. Le foyer, où le faisceau est concentré, se situe dans la tige cylindrique (1) qui constitue le bras. Pour des faisceaux lasers impulsionnels de forte puissance la tige cylindrique qui reçoit le foyer est étanche et est placé sous vide primaire. Un gaz propre de type azote, argon ou air dépoussiéré peut être placé dans la tige étanche. Le poignet reçoit un zoom (11) qui image l'image plan de l'embase (5) sur le plan moyen de la cible (9).Le grandissement du zoom est ajustable à partir du poignet.
According to Figure No. 1, the articulated arm is constituted for example around six degrees of freedom Two hollow cylindrical rods (1 & 2) are associated by a rotary junction (3) to two mirrors under 450 incidence. arm shaft (4) is fixed on the fuse (5) which is the output plane of the laser transmitter and is connected to the rod (2) by the rotary junction (6) with two mirrors under 45 "d 'impact. The wrist of the arm (7) is constituted by a double junction with three mirrors under 450 of incidence and a tip (8) which can receive a handle for maintenance. The target (9) on which the interaction takes place , is located at a distance from the end of the tip whose minimum and maximum values are indicated to the user by a sensor included in the tip. The use of an articulated arm whose number of degrees of freedom would be different from six would not go beyond the invention. The optical assembly placed inside the arm image the plane of the base (5) with the mean plane of the target (9). This crew is constituted for example, and according to FIG. 2, by a convergent lens (10) whose length of the focal length f is chosen so that the image of the plane of the base (5) is located at the wrist entry (7) with a magnification g If L is the distance between the object plane and the image plane, the relation between f, L and g is the following g) .L / (1-g) 2 (with g <o)
If Z is the distance between the object plane and the plane in which the lens is, the relation between Z, L and g is Z = L / (1 -g)
In application, for a magnification of -0.5, the convergent lens has a focal length f = L / 4.5 and Z is equal to L / 1.5. The transition to the home is at a distance of
L / 1,125 from the plane of the base. The focus, where the beam is concentrated, is located in the cylindrical rod (1) which constitutes the arm. For pulsed laser beams of high power the cylindrical rod which receives the focus is sealed and is placed under a primary vacuum. A clean gas of nitrogen, argon or dedusted air type can be placed in the sealed rod. The wrist receives a zoom (11) which images the plane image of the base (5) on the mean plane of the target (9). The magnification of the zoom is adjustable from the wrist.
Une variante à l'équipage optique consisterait à utiliser toute combinaison optique qui image le plan de l'embase et le plan moyen de la cible avec un grandissement fixe ou ajustable.An alternative to the optical crew would be to use any optical combination that image the plane of the base and the average plane of the target with a fixed or adjustable magnification.
Il est courant de constater dans les bras articulés que les défauts de mécanique induisent une instabilité spatiale du faisceau en sortie de l'embout du poignet quand le bras décrit l'espace. Cette instabilité est minimisée par la présence de l'équipage optique.It is common to note in articulated arms that mechanical defects induce spatial instability of the beam at the end of the wrist tip when the arm describes the space. This instability is minimized by the presence of the optical crew.
L'utilisation du dispositif selon l'invention avec des émetteurs-laser à cavité à transformation de Fourier ou à cavité multi-mode pour lesquelles la densité surfacique de puissance en sortie est constante et homogène, permet de disposer sur le plan de la cible d'une densité surfacique de puissance constante et homogène.The use of the device according to the invention with Fourier transform cavity or multi-mode cavity laser emitters for which the surface density of power output is constant and homogeneous, makes it possible to have on the plane of the target of a surface density of constant and homogeneous power.
Le dispositif de gestion de faisceau, selon l'invention, est utilisé pour toutes les applications industrielles du laser et notamment le nettoyage par laser par photoablation. The beam management device, according to the invention, is used for all industrial laser applications and in particular photoblation laser cleaning.

Claims (11)

Revendicationsclaims
1/ Dispositif de gestion de faisceau caractérisé en ce qu'il est composé d'un bras articulé qui inclut un équipage optique pour imager le plan de sortie de l'émetteur-laser et le plan de la cible sur laquelle l'interaction du champ électromagnétique lumineux du laser et la matière de la cible s'effectue.1 / beam management device characterized in that it is composed of an articulated arm which includes an optical equipment for imaging the output plane of the laser-emitter and the plane of the target on which the interaction of the field electromagnetic light of the laser and the material of the target is effected.
2/ Dispositif de gestion de faisceau selon la revendication 1, caractérisé en ce que le bras articulé est constitué de deux tiges cylindriques, d'un fût, de jonctions à miroirs à 45" d'incidence et d'un poignet pour assurer six degrés de liberté et qui reçoit un équipage optique composé d'une lentille convergente et d'un zoom placé dans le poignet.2 / beam management device according to claim 1, characterized in that the articulated arm consists of two cylindrical rods, a barrel, mirror junctions at 45 "incidence and a wrist to ensure six degrees of freedom and which receives an optical crew composed of a convergent lens and a zoom placed in the wrist.
3/ Dispositif de gestion de faisceau selon les revendications 1 et 2, caractérisé en ce que l'une des tiges cylindriques du bras dans laquelle le faisceau laser est focalisé, est étanche et est mise sous vide primaire.3 / beam management device according to claims 1 and 2, characterized in that one of the cylindrical rods of the arm in which the laser beam is focused, is sealed and is placed under primary vacuum.
4/ Dispositif de gestion de faisceau selon les revendications 1 et 2, caractérisé en ce que l'une des tiges cylindriques du bras dans laquelle le faisceau laser est focalisé, contient un gaz propre de type azote, argon ou air dépoussiéré.4 / beam management device according to claims 1 and 2, characterized in that one of the cylindrical rods of the arm in which the laser beam is focused, contains a clean gas nitrogen, argon or air dust.
5/ Dispositif de gestion de faisceau selon les revendications 1 et 2, caractérisé en ce que l'équipage optique est composé de toute combinaison optique qui assure l'imagerie du plan de sortie de l'émetteur-laser sur le plan de la cible.5 / beam management device according to claims 1 and 2, characterized in that the optical assembly is composed of any optical combination which provides imaging of the output plane of the laser transmitter on the plane of the target.
6/ Dispositif de gestion de faisceau selon la revendication 1, caractérisé en ce que le bras articulé puisse avoir un nombre quelconque de degrés de liberté.6 / beam management device according to claim 1, characterized in that the articulated arm can have any number of degrees of freedom.
7/ Dispositif de gestion de faisceau selon les revendications précédentes, caractérisé en ce que l'équipage optique minimise l'instabilité spatiale du faisceau en sortie de poignet.7 / beam management device according to the preceding claims, characterized in that the optical equipment minimizes the spatial instability of the beam at the wrist exit.
8/ Dispositif de gestion de faisceau selon les revendications précédentes, caractérisé en ce que le grandissement de l'équipage optique est fixe ou ajustable.8 / beam management device according to the preceding claims, characterized in that the magnification of the optical equipment is fixed or adjustable.
9/ Dispositif de gestion de faisceau selon les revendications précédentes, caractérisé en ce qu'il est associé à des émetteurs-lasers dont les cavités à transformation de Fourier ou multi-mode fournissent des densités surfaciques de surface constantes et homogènes qui se sont imagées sur le plan de la cible selon le grandissement de l'équipage optique.9 / beam management device according to the preceding claims, characterized in that it is associated with laser-emitters whose Fourier transform or multi-mode cavities provide constant and homogeneous surface area densities which are imaged on the plane of the target according to the magnification of the optical crew.
10/ Dispositif de gestion de faisceau selon les revendications, caractérisé en ce qu'il existe un senseur inclus dans l'embout du poignet qui indique à l'utilisateur la distance maximum et minimum entre la cible et la sortie du poignet.10 / beam management device according to the claims, characterized in that there is a sensor included in the wrist tip that tells the user the maximum and minimum distance between the target and the wrist exit.
11/ Dispositif de gestion de faisceau selon les revendications, caractérisé en ce qu'il est utilisé pour les applications industrielles du laser et notamment pour le nettoyage par laser par photoablation. 11 / beam management device according to the claims, characterized in that it is used for industrial laser applications and in particular for cleaning by laser photoablation.
FR9509192A 1995-07-25 1995-07-25 Control of laser beam for industrial surface cleaning - has laser beam transmitted inside articulated arm, with mirrors at joints and optical imaging unit carried at free end of arm Pending FR2737311A1 (en)

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FR9509192A FR2737311A1 (en) 1995-07-25 1995-07-25 Control of laser beam for industrial surface cleaning - has laser beam transmitted inside articulated arm, with mirrors at joints and optical imaging unit carried at free end of arm

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FR9509192A FR2737311A1 (en) 1995-07-25 1995-07-25 Control of laser beam for industrial surface cleaning - has laser beam transmitted inside articulated arm, with mirrors at joints and optical imaging unit carried at free end of arm

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2910977A1 (en) * 2006-12-28 2008-07-04 L M Sarl Optical device for focalizing a laser beam, comprises an optical block having a first plane mirror receiving the laser beam and reflecting the beam on an optical element, and an articulated optical block having two superimposed parts
WO2018084961A1 (en) * 2016-11-04 2018-05-11 General Electric Company In-situ laser machining using mirrored optics

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE8812043U1 (en) * 1988-09-23 1988-12-01 Zeiss, Carl, 7920 Heidenheim, De
WO1989011260A1 (en) * 1988-05-19 1989-11-30 Refractive Laser Research & Development Program, L Handpiece and related apparatus for laser surgery and dentistry
US5018848A (en) * 1987-09-04 1991-05-28 Nikon Corporation Laser beam transmitting apparatus
FR2660492A1 (en) * 1990-03-30 1991-10-04 Bm Ind Fourier transform optical resonators
EP0509933A1 (en) * 1991-04-19 1992-10-21 Commissariat A L'energie Atomique Procedure for the alignment of a laserr beam to the opening of a nozzle and focussing head matched for machining by laser beam
EP0521194A2 (en) * 1991-07-03 1993-01-07 Mitsubishi Denki Kabushiki Kaisha Laser machining apparatus for welding and cutting
EP0536951A2 (en) * 1991-10-10 1993-04-14 Coherent, Inc. Apparatus for delivering a defocused laser beam having a sharp-edged cross-section

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5018848A (en) * 1987-09-04 1991-05-28 Nikon Corporation Laser beam transmitting apparatus
WO1989011260A1 (en) * 1988-05-19 1989-11-30 Refractive Laser Research & Development Program, L Handpiece and related apparatus for laser surgery and dentistry
DE8812043U1 (en) * 1988-09-23 1988-12-01 Zeiss, Carl, 7920 Heidenheim, De
FR2660492A1 (en) * 1990-03-30 1991-10-04 Bm Ind Fourier transform optical resonators
EP0509933A1 (en) * 1991-04-19 1992-10-21 Commissariat A L'energie Atomique Procedure for the alignment of a laserr beam to the opening of a nozzle and focussing head matched for machining by laser beam
EP0521194A2 (en) * 1991-07-03 1993-01-07 Mitsubishi Denki Kabushiki Kaisha Laser machining apparatus for welding and cutting
EP0536951A2 (en) * 1991-10-10 1993-04-14 Coherent, Inc. Apparatus for delivering a defocused laser beam having a sharp-edged cross-section

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2910977A1 (en) * 2006-12-28 2008-07-04 L M Sarl Optical device for focalizing a laser beam, comprises an optical block having a first plane mirror receiving the laser beam and reflecting the beam on an optical element, and an articulated optical block having two superimposed parts
WO2018084961A1 (en) * 2016-11-04 2018-05-11 General Electric Company In-situ laser machining using mirrored optics

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