Method for the machining of workpieces by means of several laser beams
AssigneeDataCard Corporation
InventorsR?uuml;diger Kreuter, Ulrich Bielesch
Life of this patent
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Abstract
In material machining by means of laser beams, in particular when engraving for example metal or when blackening and marking on plastic material, there is to be provided a process in which in spite of a high frequency of machining pulses the required minimum energy per pulse is achieved. For that purpose a plurality of laser beams are brought together by way of a beam-combining means and passed by way of a common beam-guide means on to the workpiece and in particular operated in time-displaced relationship.
Claims27
A process for machining workpieces (4) by means of a machining laser beam (3, 3′, 3″),
- characterised in that
- at least two laser beams (2a, 2b) are brought together by way of a beam-combining means (5) and
- are passed by way of a common beam-guide means on to the workpiece (4).
A process according to one of the preceding claims characterised in that the laser beams (2a, 2b) are discontinuous laser beams and in particular originate from different laser sources (1a, 1b) which discontinuously output the light and the light pulses arrive in the beam-combining means simultaneously and impinge on the workpiece (4) simultaneously.
A process according to one of the preceding claims characterised in that the laser beams (2a, 2b) are linearly polarised laser beams, in particular with a polarisation plane turned through 90° relative to each other.
A process according to one of the preceding claims characterised in that at least three laser beams (2a, 2b, 2c) are brought together and jointly form the machining laser beam (3) by a procedure whereby in succession possibly a multiple of times:
- a first in particular discontinuous laser beam (2a) and a second in particular discontinuous laser beam (2b) are brought together in a beam-combining means in mutually time-displaced relationship,
- the partial machining beam (3′) obtained in that way is passed through an active optical component (6) which can alter the in particular linear polarisation of the partial machining beam (3′) and which is activated whenever the one laser beam (for example 2b) impinges on the active optical component (6) and thereby alters its polarisation to the polarisation of the other laser beam (for example 2a), but is deactivated when the other laser beam (for example 2a) impinges on the component (6),
- the altered partial machining beam (3′) which is obtained in that way and which now has linear polarisation corresponding to the one laser beam (2a) is brought together in a further beam-combining means (5b) with a further laser beam (2c) whose in particular linear polarisation differs in particular from that of the partial machining beam (3′), and
- the machining laser beam is passed by way of a beam-guide means on to the workpiece (4).
A process according to one of the preceding claims characterised in that the active optical element (6) is a Pockel cell.
A process according to one of the preceding claims characterised in that the active optical element (6) is a Kerr cell.
A process according to one of the preceding claims characterised in that the active optical element (6) is a magneto-optical modulator which operates for example on the basis of the Faraday effect or an acousto-optical modulator which changes the polarisation by the action of a sound wave field.
A process according to one of the preceding claims characterised in that the active optical element (6) utilises the birefringence which is produced in certain materials by mechanical loading, for example pressure, and in particular the material is a uniaxial transparent crystal such as for example an NaCl- or LiF-crystal, or acrylic resin.
A process according to one of the preceding claims characterised in that during the machining operation the laser pulses of the individual laser beams (2a, b . . . ) can be changed over in their time succession relative to each other from synchronous to time-displaced and vice-versa.
A process according to one of the preceding claims characterised in that after the last bringing-together of a partial machining beam (3′) and a last original laser beam (for example 2b), they no longer pass through any further active optical element which alters linear polarisation.
A process according to one of the preceding claims characterised in that the laser sources (1a, 1b, . . . ) emit laser beams (2a, 2b, . . . ) of the same wavelength.
A process according to one of the preceding claims characterised in that the laser sources (1a, 1b, . . . ) are laser sources of the same kind.
A process according to one of the preceding claims characterised in that the laser beams (2a, 2b, . . . ) have impressed thereon a polarisation of the same type, in particular linear polarisation.
Apparatus for machining workpieces (4) by means of a machining laser beam (3, 3′, 3″),
- characterised by
- at least two laser beams (1a, 1b),
- at least one beam-combining means (5), and
- at least one common beam-guide means arranged downstream of the beam-combining means (5) for the laser beams (2a, 2b) of the laser sources (1a, 1b) in a direction towards the workpiece (4).
Apparatus according to one of the preceding apparatus claims characterised in that the optical path length from the laser sources (1a, 1b) to the coupling point in the beam-combining means (5) is equal.
Apparatus according to one of the preceding apparatus claims characterised in that an adjustable direction-changing mirror (7, 7′) is arranged in the beam path of at least one of the laser beams (2a, 2b).
Apparatus according to one of the preceding apparatus claims characterised in that the beam-combining means (5a, 5b) is pivotable about an axis parallel to an axis parallel to the direction of the laser beam (2a) just passing therethrough.
Apparatus according to one of the preceding apparatus claims characterised in that the beam-combining means (5a, 5b) is pivotable about an axis parallel to an axis perpendicular to the direction of the laser beam (2a) just passing therethrough.
Apparatus according to one of the preceding apparatus claims characterised in that at least one pivotable mirror (8) is arranged in the beam path downstream of the last beam-combining means (5).
Apparatus according to one of the preceding apparatus claims characterised in that a beam shaping unit is arranged in the beam path downstream of the last beam-combining means (5b) and upstream of the last mirror (8).
Apparatus according to one of the preceding apparatus claims characterised in that the lens arranged downstream of the last mirror (8) is arranged stationarily and is of such a large diameter that the laser beams pass through the lens even upon maximum deflection of the mirror (8).
Dependencies are inferred from the claim text.