WO2024251870A2 - Tête de marquage laser - Google Patents

Tête de marquage laser Download PDF

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Publication number
WO2024251870A2
WO2024251870A2 PCT/EP2024/065583 EP2024065583W WO2024251870A2 WO 2024251870 A2 WO2024251870 A2 WO 2024251870A2 EP 2024065583 W EP2024065583 W EP 2024065583W WO 2024251870 A2 WO2024251870 A2 WO 2024251870A2
Authority
WO
WIPO (PCT)
Prior art keywords
marking head
electromagnetic radiation
laser source
marking
laser
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/EP2024/065583
Other languages
English (en)
Other versions
WO2024251870A3 (fr
Inventor
Peter J. Kueckendahl
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.)
Alltec Angewandte Laserlicht Technologie GmbH
Original Assignee
Alltec Angewandte Laserlicht Technologie GmbH
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 Alltec Angewandte Laserlicht Technologie GmbH filed Critical Alltec Angewandte Laserlicht Technologie GmbH
Publication of WO2024251870A2 publication Critical patent/WO2024251870A2/fr
Publication of WO2024251870A3 publication Critical patent/WO2024251870A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • B23K26/08—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
    • B23K26/0096—Portable laser equipment, e.g. hand-held laser apparatus
    • 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
    • B23K26/352—Working by laser beam, e.g. welding, cutting or boring for surface treatment
    • B23K26/355—Texturing
    • 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
    • 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
    • H01S3/02—Constructional details
    • H01S3/03—Constructional details of gas laser discharge tubes
    • 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
    • H01S3/14—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
    • H01S3/2232—Carbon dioxide (CO2) or monoxide [CO]

Definitions

  • the present disclosure relates to a compact laser marking head comprising a CO2 laser source. Aspects and implementations of the present disclosure are directed generally to laser marking equipment.
  • Known laser marking systems comprise a supply unit and a laser marking head.
  • the supply unit typically comprises electronic components such as a power supply, a laser controller, user interfaces and one or more processors for performing various functions such as safety logic.
  • the laser marking head typically comprises optical components such as beam shaping optics and a laser beam deflection unit, as well as other components such as, for example, a cooling system.
  • the supply unit and the laser marking head are typically connected via an umbilical assembly comprising a variety of electrical connections for conveying signals and power between the supply unit and the laser marking head.
  • Known laser marking systems comprise a CO2 laser source configured to generate laser radiation for marking products.
  • the CO2 laser source is located in the supply unit.
  • the umbilical assembly comprises an optical fiber configured to transmit laser radiation from the CO2 laser source to the laser marking head. Locating the CO2 laser source in the supply unit advantageously enables a more compact laser marking head.
  • the design of the umbilical assembly becomes more complex, one or more optical components must be introduced to account for the presence of the optical fiber, and radiative losses occur along the optical fiber.
  • the CO2 laser source is located in the laser marking head.
  • the CO2 laser source or the laser beam deflection unit, or both, are relatively large, bulky components.
  • Known laser deflection units comprise perpendicularly arranged mirrors for scanning the laser radiation about a two-dimensional field of view.
  • Known CO2 laser sources comprise a plurality of bulky mounts and adjustment mechanisms for adjusting a relative positioning of components of the optical cavity. These arrangements make existing laser marking heads and systems bulkier and thus limited in positioning capabilities in a production system (e.g. when incorporated into a production line).
  • aspects and embodiments disclosed herein provide for a compact, lightweight laser marking head, allowing for easy integration and operation of a laser marking system into production systems.
  • aspects and embodiments disclosed herein include a laser marking head comprising a CO2 laser source that is inserted co-axially (i.e. substantially parallel) to the laser marking head.
  • the compact size of the resulting laser marking head facilitates integration of laser marking equipment into production lines.
  • a marking head for a laser marking system.
  • the marking head comprises a CO2 laser source configured to generate electromagnetic radiation.
  • the marking head comprises an electromagnetic radiation steering mechanism configured to steer the electromagnetic radiation to address a specific location within a two-dimensional field of view.
  • the electromagnetic radiation steering mechanism comprises a first optical element having an associated first actuator configured to rotate the first optical element about a first rotational axis to change a first coordinate of a first steering axis in the two-dimensional field of view.
  • the electromagnetic radiation steering mechanism comprises a second optical element having an associated second actuator configured to rotate the second optical element about a second rotational axis to change a second coordinate of a second steering axis in the two-dimensional field of view.
  • the electromagnetic radiation steering mechanism comprises an electromagnetic radiation manipulator optically disposed between the first and second optical elements.
  • a first angle is defined between the first and second rotational axes.
  • a second angle is defined between the first and second steering axes.
  • the electromagnetic radiation manipulator is configured to introduce a difference between the first angle and the second angle.
  • the CO2 laser source has a dimension in a first direction that is greater than a dimension of the CO2 laser source in either orthogonal direction to the first direction.
  • the marking head has a dimension in the first direction that is greater than a dimension of the marking head in either orthogonal direction to the first direction.
  • the dimension of the CO2 laser source in the first direction may correspond to a length of the CO2 laser source.
  • the dimension of the marking head in the first direction may correspond to a length of the marking head.
  • length shall be understood as meaning the greatest of three dimensions of an object. That is, a length of an object is greater than a width, height or diameter of the object.
  • the combination of the electromagnetic radiation manipulator enabling nonperpendicular optical elements to steer radiation in perpendicular directions, and the CO2 laser source and marking head both being elongate in the first direction, advantageously provides a compact arrangement.
  • the significant reduction of the size of the marking head compared to known marking heads that comprise a CO2 laser source advantageously allows greater flexibility of use.
  • the marking head is easier to move around (e.g. using a robotic arm) and can fit into tighter spaces (e.g. on a spatially busy production line).
  • the electromagnetic radiation steering mechanism may have a dimension in the first direction that is greater than a dimension of the electromagnetic radiation steering mechanism in either direction orthogonal to the first direction.
  • the dimension of the electromagnetic radiation steering mechanism in the first direction may correspond to a length of the CO2 laser source.
  • marking head and electromagnetic radiation steering mechanism being elongate in the first direction, advantageously provides a compact arrangement.
  • the significant reduction of the size of the marking head compared to known marking heads that comprise a CO2 laser source advantageously allows greater flexibility of use.
  • the marking head is easier to move around (e.g. using a robotic arm) and can fit into tighter spaces (e.g. on a spatially busy production line).
  • the CO2 laser source may be installed substantially parallel to the marking head such that a length of the marking head is substantially parallel to a length of the CO2 laser source.
  • the electromagnetic radiation manipulator enables parallel optical elements to steer the radiation in non-parallel (e.g. perpendicular) axes.
  • Having parallel optical elements (and associated actuators) allows the electromagnetic radiation steering mechanism to be installed within the marking head such that both rotational axes of the first and second optical elements are parallel with a length or primary axis of the marking head.
  • the CO2 laser source is installed substantially parallel to the marking head such that a primary axis of the marking head is substantially parallel to a primary axis of the CO2 laser source. That is, primary axes of the CO2 laser source, electromagnetic radiation steering mechanism and marking head may all be substantially parallel to one another, thereby providing a very compact arrangement.
  • the marking head described herein may therefore be installed more easily and allow greater flexibility of use (e.g. movement during marking and/or locating the marking head in a small space) compared to known marking heads.
  • the form factor, size, and weight of aspects and embodiments of the laser scanner/marker system disclosed herein provide for the disclosed laser scanner/marker system to be more easily manipulated. Aspects and embodiments of the laser scanner/marker system disclosed herein may be mounted in production systems where existing laser scanner/marker systems could not.
  • substantially parallel is intended to include arrangements in which the length of the CO2 laser source is intentionally non-parallel to a length of the electromagnetic radiation steering mechanism and/or marking head to correct for nonparallel emission of radiation from the CO2 laser source (i.e. an angular beam walk).
  • a translational (or “lateral”) beam walk may at least partially determine an intentional angle between a length of the CO2 laser source and a length of the electromagnetic radiation steering mechanism and/or marking head needed to correct for the angular beam walk.
  • the translational beam walk may be about 0.25 mm or less.
  • substantially parallel may mean that the angle between a length of the CO2 laser source and a length of the electromagnetic radiation steering mechanism and/or marking head may be about 5 mrad or less.
  • substantially parallel may mean that the angle between a length of the CO2 laser source and a length of the electromagnetic radiation steering mechanism and/or marking head may be about 2.5 mrad or less.
  • the marking head may have a mass of about 15 kg or less.
  • the mass of the marking head may be about 10 kg or less.
  • the mass of the marking head may be about 5 kg or less.
  • the mass of the marking head may be about 3 kg or less.
  • the mass of the marking head may be about 2 kg or less.
  • the mass of the marking head may be about 1.5 kg.
  • Known marking heads have a mass of about 19 kg or more. The significant reduction of mass of the present marking head compared to known marking heads advantageously allows more flexibility in use of the marking head (e.g. the marking head is easier to move around and requires less robust support).
  • the marking head may have a volume of about 10 I or less.
  • the volume of the marking head may be about 5 I or less.
  • the volume of the marking head may be about 3 I or less.
  • the volume of the marking head may be about 2 I or less.
  • the volume of the marking head may be about 1.5 I or less.
  • the volume of the marking head may be about 1 I.
  • Known marking heads have a volume of about 19 I or more.
  • the significant reduction of volume of the present marking head compared to known marking heads advantageously allows more flexibility in use of the marking head (e.g. the marking head is easier to move around and may fit into more compact spaces).
  • the marking head may have a length of about 500 mm or less.
  • the length of the marking head may be about 400 mm or less.
  • the length of the marking head may be about 350 mm or less.
  • the length of the marking head may be about 310 mm.
  • Known marking heads have a length of about 770 mm or more.
  • the significant reduction of length of the present marking head compared to known marking heads advantageously allows more flexibility in use of the marking head (e.g. the marking head is easier to move around and may fit into more compact spaces).
  • the marking head may comprise a cylindrical housing.
  • Known marking heads comprise bulky cuboidal housings.
  • the cylindrical shape of the housing may advantageously provide for the housing to be more easily clamped in place onto a piece of manufacturing equipment than housings with rectangular cross sections.
  • the marking head may have a diameter of about 100 mm or less.
  • the marking head may have a diameter of about 90 mm or less.
  • the marking head may have a diameter of about 80 mm or less.
  • the marking head may have a diameter of about 70 mm or less.
  • the marking head may have a diameter of about 65 mm or less.
  • the marking head may have a diameter of about 64 mm.
  • Known marking heads have a width and/or height of about 140 mm or more.
  • the significant reduction of diameter of the present marking head compared to known marking heads advantageously allows more flexibility in use of the marking head (e.g. the marking head is easier to move around and may fit into more compact spaces).
  • the CO2 laser source may have a mass of about 4 kg or less.
  • the CO2 laser source may have a mass of about 3 kg or less.
  • the CO2 laser source may have a mass of about 2 kg or less.
  • the CO2 laser source may have a mass of about 1 kg or less.
  • the CO2 laser source may have a mass of about 0.6 kg or less.
  • the CO2 laser source may have a mass of about 0.5 kg.
  • Known CO2 laser sources have a mass of about 6.6 kg or more.
  • the significant reduction of mass of the present CO2 laser source compared to known CO2 laser sources advantageously allows a corresponding decrease in the mass of the present marking head compared to known marking heads, allowing more flexibility in use of the marking head (e.g. the marking head is easier to move around and requires less robust support).
  • the CO2 laser source may have a volume of about 3 I or less.
  • the CO2 laser source may have a volume of about 2 I or less.
  • the CO2 laser source may have a volume of about 1 I or less.
  • the CO2 laser source may have a volume of about 0.5 I or less.
  • the CO2 laser source may have a volume of about 0.4 I.
  • Known CO2 laser sources have a volume of about 5.7 I or more.
  • the significant reduction of volume of the present CO2 laser source compared to known CO2 laser sources advantageously allows a corresponding decrease in the volume of the present marking head compared to known marking heads, allowing more flexibility in use of the marking head (e.g. the marking head is easier to move around and may fit into more compact spaces).
  • the CO2 laser source may have a length of about 250 mm or less.
  • the CO2 laser source may have a length of about 225 mm or less.
  • the CO2 laser source may have a length of about 210 mm or less.
  • the CO2 laser source may have a length of about 200 mm.
  • the CO2 laser source may comprise a cylindrical body.
  • Known CO2 laser sources comprise bulky cuboidal housings.
  • the cylindrical shape of the CO2 laser source may advantageously provide for a more compact arrangement compared to known marking heads.
  • the CO2 laser source may have a diameter of about 60 mm or less.
  • the CO2 laser source may have a diameter of about 55 mm or less.
  • the CO2 laser source may have a diameter of about 50 mm.
  • the marking head may comprise an alignment mount configured to receive the CO2 laser source and the electromagnetic radiation steering mechanism such that the electromagnetic radiation generated by the CO2 laser source propagates to an input of the electromagnetic radiation steering mechanism in a desired direction.
  • the alignment mount may comprise a first protrusion configured to be inserted into a first cavity of the electromagnetic radiation steering mechanism.
  • the alignment mount may comprise a second protrusion configured to be inserted into a second cavity of the electromagnetic radiation steering mechanism.
  • the first protrusion of the alignment mount may comprise a first cavity configured to receive a first protrusion of the CO2 laser source.
  • the second protrusion of the alignment mount may comprise a second cavity configured to receive a second protrusion of the CO2 laser source.
  • the first and second protrusions of the CO2 laser source may act as dowel pins that are configured to be inserted into the first and second cavities of the alignment mount.
  • the desired direction may be substantially parallel to the first direction.
  • the CO2 laser source may be a CO2 slab laser.
  • the CO2 slab laser may comprise a pair of opposing mirrors arranged to form a resonator.
  • the CO2 slab laser may comprise a pair of opposing elongate electrodes configured to receive RF energy and thereby excite a gaseous gain medium located between the pair of electrodes and the pair of mirrors.
  • the marking head may comprise an actuation mechanism configured to change a relative positioning of the pair of mirrors and the pair of electrodes.
  • the marking head may comprise a deformable housing. Deformation of the housing may change a relative positioning of the pair of mirrors and the pair of electrodes.
  • the pair of electrodes may be shaped so as to each form at least part of a circle in cross-section.
  • the marking head may comprise an active fluid cooling system.
  • the active fluid cooling system may be configured to provide a flow of cooling fluid configured to cool one or more components of the marking head.
  • the cooling fluid may, for example, comprise water.
  • the active fluid cooling system may be configured to cool the pair of electrodes.
  • the active fluid cooling system may comprise a blind hole formed in each of the pair of electrodes for conveying a cooling fluid.
  • the active fluid cooling system may be configured to cool the first and second actuators.
  • the active cooling system may be configured to indirectly cool the actuators.
  • the active cooling system may be configured to cool a body that is configured to support the actuators A, B rather than cooling the actuators A, B themselves.
  • the active cooling system may be configured to cool the body of the electromagnetic radiation steering mechanism proximate the actuators A, B and thereby indirectly cool the actuators A, B.
  • Indirect cooling is advantageous because the thermal load of the two actuators (e.g. galvanometers) may be substantially different from each other depending on the marking content, and the partial absorption of laser radiation in the mirrors controlled by the actuators, as well as laser back reflections from the product to be marked, may cause heating of the electromagnetic radiation steering mechanism in general rather than just the actuators heating.
  • the active fluid cooling system may comprise a blind hole formed in a body of the electromagnetic radiation steering mechanism for conveying a cooling fluid.
  • the active fluid cooling system may comprise a blower and one or more heat dissipation structures in thermal communication with a heat source in the marking head.
  • the blower may be configured to generate a flow of air across the one or more heat dissipation structures.
  • the one or more heat dissipation structure may comprise fins.
  • the fins may be formed of a thermally conductive material such as, for example, aluminium.
  • the first rotational axis and the second rotational axis may be substantially parallel.
  • the first steering axis and the second steering axis may be substantially orthogonal.
  • the first and second rotational axes may be substantially parallel to the first direction.
  • the first optical element may comprise a first reflective surface configured to receive the electromagnetic radiation.
  • the second optical element may comprise a second reflective surface configured to receive the electromagnetic radiation.
  • the first rotational axis and the first reflective surface may be substantially parallel.
  • the second rotational axis and the second reflective surface may be substantially parallel.
  • the first and second reflective surfaces may be substantially parallel to the first direction.
  • the electromagnetic radiation manipulator may comprise a first mirror and a second mirror that are fixed with respect to each other.
  • the first rotational axis and the second rotational axes may be substantially parallel.
  • the electromagnetic radiation steering mechanism may be installed substantially parallel to the marking head such that a length of the marking head is substantially parallel to the first and second axes of rotation.
  • the CO2 laser source may be configured to generate and direct the electromagnetic radiation in a direction that is substantially parallel to the first and second axes of rotation.
  • the marking head may comprise a variable optical path length assembly configured to define an optical path from an input to an output.
  • a laser marking system for marking a product comprising the marking head of the first aspect.
  • the laser marking system may comprise a supply unit.
  • the laser marking system may comprise an umbilical assembly connecting the supply unit to the marking head.
  • the umbilical assembly may be configured to transmit power and/or control signals to the marking head from another object in the supply unit such as a controller.
  • the umbilical assembly may advantageously allow easy movement of the marking head thereby further increasing the range of applications and installation environments in which the marking head may be used.
  • the laser marking system may comprise a sealing plug configured to receive the umbilical assembly at a first end and the CO2 laser source at a second end.
  • the umbilical assembly may comprise a first electrical connection between the first actuator and the supply unit and a second electrical connection between the second actuator and the supply unit.
  • the umbilical assembly may comprise a third electrical connection between a sensor located in the marking head and the supply unit.
  • the third electrical connection may comprise a plurality of electrical connections between a plurality of sensors located in the marking head and the supply unit.
  • the plurality of sensors may comprise, for example, one or more temperature sensors (e.g. for monitoring a temperature of the electromagnetic radiation steering mechanism), one or more radiation sensors (e.g. for detecting failure of the CO2 laser source) or for detecting stray radiation for satisfying laser safety requirements) , one or more position sensors (e.g. for determining whether or not the marking head is correctly mounted to a production line or robotic arm), one or more image sensors (e.g. for providing images of products to a marking feedback system), one or more gyrosensors (e.g. for determining an orientation of the marking head), etc.
  • the umbilical assembly may comprise a first conduit configured to transmit a cooling fluid from the supply unit to the marking head and a second conduit configured to transmit the cooling fluid from the marking head to the supply unit.
  • the variable optical path length assembly may comprise a third actuator.
  • the umbilical assembly may comprise a fourth electrical connection between the third actuator and the supply unit.
  • a method of marking a product using a CO2 laser source and an electromagnetic radiation steering mechanism comprises using the CO2 laser source to generate electromagnetic radiation.
  • the method comprises receiving the electromagnetic radiation at a first optical element that is rotatable about a first rotational axis to change a first coordinate of a first steering axis in the two-dimensional field of view.
  • the method comprises directing the electromagnetic radiation to an electromagnetic radiation manipulator optically disposed between the first optical element and a second optical element.
  • the method comprises directing the electromagnetic radiation to the second optical element that is rotatable about a second rotational axis to change a second coordinate of a second steering axis in the two-dimensional field of view.
  • the method comprises defining a first angle between the first and second rotational axes.
  • the method comprises defining a second angle between the first and second steering axes.
  • the method comprises using the electromagnetic radiation manipulator to introduce a difference between the first angle and the second angle.
  • the method comprises steering the electromagnetic radiation about the product by rotating the first and second optical elements.
  • the CO2 laser source and the electromagnetic radiation steering mechanism are disposed within a marking head.
  • the CO2 laser source has a dimension in a first direction that is greater than a dimension of the CO2 laser source in either orthogonal direction to the first direction.
  • the marking head has a dimension in the first direction that is greater than a dimension of the marking head in either orthogonal direction to the first direction.
  • a method of assembling a marking head comprises mounting a first optical element and an associated first actuator that is configured to rotate the first optical element about a first rotational axis to change a first coordinate of a first steering axis in the two-dimensional field of view.
  • the method comprises mounting a second optical element having an associated second actuator that is configured to rotate the second optical element about a second rotational axis to change a second coordinate of a second steering axis in the two-dimensional field of view.
  • the method comprises optically disposing an electromagnetic radiation manipulator between the first and second optical elements.
  • a first angle is defined between the first and second rotational axes.
  • a second angle is defined between the first and second steering axes.
  • the electromagnetic radiation manipulator is configured to introduce a difference between the first angle and the second angle.
  • the CO2 laser source has a dimension in a first direction that is greater than a dimension of the CO2 laser source in either orthogonal direction to the first direction.
  • the marking head has a dimension in the first direction that is greater than a dimension of the marking head in either orthogonal direction to the first direction.
  • the method may comprise attaching the CO2 laser source to the electromagnetic radiation steering mechanism.
  • the method may comprise attaching an end cap to a housing to form a hollow body.
  • the method may comprise attaching a sealing plug to an umbilical assembly comprising a plurality of connectors.
  • the method may comprise connecting the plurality of connectors to components of the CO2 laser source and the electromagnetic radiation steering mechanism.
  • the method may comprise inserting an entire functional block comprising the electromagnetic steering mechanism, the CO2 laser source, the connectors, and the sealing plug into the hollow body formed by the housing and the end cap.
  • a method of connecting a CO2 laser source and an electromagnetic radiation steering mechanism comprises inserting first and second protrusions of the CO2 laser source into first and second cavities of an alignment mount.
  • the method comprises using an alignment sensor to detect an angular offset between a direction in which radiation is emitted by the CO2 laser source and a desired direction.
  • the method comprises adjusting a position of the CO2 laser source relative to the alignment mount such that the CO2 laser source emits radiation in the desired direction as detected by the alignment sensor.
  • the method comprises fixing the CO2 laser source relative to the alignment mount when the alignment sensor detects that the desired direction has been reached.
  • the method comprises inserting first and second protrusions of the alignment mount into the first and second cavities of the electromagnetic radiation steering mechanism.
  • Fig. 1 schematically depicts a perspective view of internal components of a marking head for a laser marking system in accordance with the present disclosure.
  • Fig. 2 schematically depicts a cross-sectional side view of a CO2 laser source of the marking head of Fig. 1.
  • Fig. 3 schematically depicts a side view of an electromagnetic radiation steering mechanism comprising an electromagnetic radiation manipulator according to an aspect of the present disclosure.
  • Fig. 4 schematically depicts a laser marking system according to an aspect of the present disclosure.
  • Fig. 5 schematically depicts a head on view of an end cap, a cross-sectional view of an electromagnetic radiation steering mechanism at a first cross-sectional plane, a cross- sectional view of the CO2 laser source at a second cross-sectional plane, and a partially transparent cross-sectional view showing the relative positions of the CO2 laser source and the electromagnetic radiation steering mechanism.
  • Fig. 6 schematically depicts a cross-sectional view of the laser marking head at the second cross-sectional plane when the CO2 laser source is installed in a cylindrical housing of the marking head, and a cross sectional view of the umbilical assembly.
  • Fig. 7 schematically depicts a plan view and a perspective view of a variable optical path length device according to an aspect of the present disclosure.
  • Fig. 8 shows a flowchart of a method of marking a product using a CO2 laser source and an electromagnetic radiation steering mechanism according to an aspect of the present disclosure.
  • Fig. 9 shows a flowchart of a method of assembling a marking head according to an aspect of the present disclosure.
  • Fig. 10 schematically depicts the CO2 laser source, the electromagnetic radiation steering mechanism and an alignment mount according to an aspect of the present disclosure.
  • Fig. 11A schematically depicts a first step of a method of connecting the CO2 laser source to the electromagnetic radiation steering mechanism according to an aspect of the present disclosure.
  • Fig. 11 B schematically depicts a second step of the method of connecting the CO2 laser source to the electromagnetic radiation steering mechanism according to an aspect of the present disclosure.
  • Fig. 11C schematically depicts a third step of the method of connecting the CO2 laser source to the electromagnetic radiation steering mechanism according to an aspect of the present disclosure.
  • Fig. 12 schematically depicts a cross-sectional side view of the active cooling system cooling the first and second electrodes of the CO2 laser source in accordance with an aspect of the present disclosure.
  • a marking head for scanning or steering the laser beam of a laser marking system, and a laser marking system including such a marking head.
  • Laser marking systems may be utilized in production lines for marking various types of articles. Laser marking systems may be utilized to imprint bar codes, unique identifying marks, expiration dates, or other information on items passing through a production line.
  • the marking head of the present disclosure comprises a carbon dioxide (CO2) laser source. CO2 laser sources produce beams of infrared light in four principal wavelength bands centering on 9.3, 9.6, 10.2, and 10.6 micrometers (pm). Lasers utilized in laser marking systems are typically operated at laser power levels in the tens of watts.
  • Fig. 1 schematically depicts a perspective view of internal components of a marking head for a laser marking system in accordance with the present disclosure.
  • the marking head comprises a CO2 laser source 1 configured to generate electromagnetic radiation 105 which exits the CO2 laser source 1 via a beam exit 90.
  • the marking head comprises an electromagnetic radiation steering mechanism 2 configured to steer the electromagnetic radiation to address a specific location within a two-dimensional field of view.
  • the CO2 laser source 1 has a dimension in a first direction 800 that is greater than a dimension of the CO2 laser source 1 in either orthogonal direction 810, 820 to the first direction 800.
  • the marking head 2 has a dimension in the first direction 800 that is greater than a dimension of the marking head 2 in either orthogonal direction 810, 820 to the first direction 800. That is, both the CO2 laser source 1 and marking head 2 are elongate in the first direction 800 compared to the second and third directions 810, 820.
  • the electromagnetic radiation steering mechanism 2 also has a dimension in the first direction 800 that is greater than a dimension of the electromagnetic radiation steering mechanism 2 in either direction 810, 820 orthogonal to the first direction 800.
  • the electromagnetic radiation steering mechanism 2 may also be considered as being elongate in the first direction 800 compared to the second and third directions 810, 820.
  • the CO2 laser source 1 is installed substantially parallel to the marking head such that a length of the marking head is substantially parallel to a length of the CO2 laser source 1.
  • Both the CO2 laser source 1 and the electromagnetic radiation steering mechanism 2 comprise compact arrangements of components that, when combined, provide a marking head having a significantly reduced weight and volume compared to known marking heads that comprise a CO2 laser source.
  • Fig. 2 schematically depicts a cross-sectional side view of the CO2 laser source 1.
  • the CO2 laser source 1 is a CO2 slab laser comprising a pair of opposing mirrors 938, 940 arranged to form a resonator 950.
  • the CO2 laser source 1 comprises a pair of opposing elongate electrodes 934, 936 configured to receive RF energy and thereby excite a gaseous gain medium located in the resonator 950.
  • a first mirror 938 of the pair of mirrors 938, 940 is mechanically coupled to a first electrode 936 of the pair of electrodes 934, 936.
  • a second mirror 940 of the pair of mirrors 938, 940 is mechanically coupled to a second electrode 934 of the pair of electrodes 934, 936.
  • the mechanical coupling between the electrodes 936, 938 and the mirrors 938, 940 is provided by bolts 952, 954. Mechanical coupling means other than, or in addition to, bolts may be used.
  • the CO2 laser source 1 comprises an actuation mechanism 920, 921 configured to change a relative positioning of the pair of mirrors 938, 940 and the pair of electrodes 934, 936.
  • the actuation mechanism 920, 921 comprises first and second screws 920, 921 that are mechanically coupled to opposing end faces 923, 924 of the CO2 laser source.
  • the end faces 923, 924 are also mechanically coupled to the electrodes 934, 936.
  • rotating one or more of the first and second screws 920, 921 moves the respective one or more of the end faces 923, 924 which in turn moves the respective one or more electrodes 934, 936 and mirrors 938, 940.
  • the actuation mechanism 920, 921 may comprise other actuating means.
  • the actuation mechanism 920, 921 may comprise one or more of piezoelectric elements, elastic elements, magnetic elements, expandable and contractible elements (e.g. bellows), etc.
  • the CO2 laser source 1 comprises a deformable housing 910.
  • the end faces 923, 924 are mechanically coupled to the housing 910.
  • Deformation of the housing 910 changes a spatial arrangement (e.g. a separation) of the end pieces 923, 924, and thereby also changes a relative positioning of the pair of mirrors 938, 940 and the pair of electrodes 934, 936.
  • plastic deformation of the housing 910 and/or the end faces 923, 924 of the CO2 laser source 1 would move the electrodes 934, 936 and, due to the mechanical coupling, would also move the mirrors 938, 940.
  • the position of the mirrors 938, 940 may be adjusted relative to each other to form a desired resonator 950 configuration. That is, by using the actuation mechanism 920, 921 and/or deforming the deformable housing 910 a spatial arrangement of the resonator 950 (e.g. an alignment of the pair of mirrors 938, 940) may be adjusted to a desired state.
  • a spatial arrangement of the resonator 950 e.g. an alignment of the pair of mirrors 938, 940
  • the housing 910 of the CO2 laser source 1 is cylindrical.
  • the pair of electrodes 934, 936 are shaped so as to each form at least part of a circle in cross-section. That is, the electrodes 934, 936 are shaped so as to nest within the cylindrical housing 910.
  • the electrodes 934, 936 may be substantially planar.
  • the electrodes 934, 936 may be relatively thin to increase the free space available in the resonator 950 for the gaseous gain medium comprising CO2.
  • the electrodes 934, 936 may have sufficient thicknesses to allow one or more holes to be formed in the electrodes 934, 936.
  • the holes may be configured to receive one or more fluid inlets 942, 946 and outlets 944, 948 which may form part of an active fluid cooling system.
  • the active fluid cooling system may provide a flow of cooling fluid, e.g. water, used to cool the pair of electrodes 934, 936 of the CO2 laser source 1.
  • the CO2 laser source 1 comprises fluid inlets 942, 946 when providing cooling fluid to the electrodes 934, 936 and fluid outlets 944, 948 when taking cooling fluid heated by the electrodes 934, 936 away from the electrodes 934, 936.
  • Multiple conduits may be provided and multiple holes may be formed in the electrodes 934, 936 for receiving said conduits.
  • the multiple conduits may be arranged to form a manifold. An example of an active fluid cooling system is described in greater detail below.
  • the compact arrangement of components of the CO2 laser source 1 provides a significant reduction in the mass and volume of the CO2 laser source 1 compared to known CO2 laser sources.
  • the CO2 laser source 1 has a mass of about 4 kg or less.
  • the CO2 laser source 1 may have a mass of about 3 kg or less, about 2 kg or less, about 1 kg or less, or about 0.6 kg or less.
  • the CO2 laser source 1 may have a mass of about 0.5 kg.
  • the CO2 laser source 1 has a volume of about 3 I or less.
  • the CO2 laser source 1 may have a volume of about 2 I or less, about 1 I or less, or about 0.5 I or less.
  • the CO2 laser source 1 may have a volume of about 0.4 I.
  • the CO2 laser source 1 has a length of about 250 mm or less.
  • the CO2 laser source 1 may have a length of about 225 mm or less, or about 210 mm or less.
  • the CO2 laser source 1 may have a length of about 200 mm.
  • the CO2 laser source 1 comprises a cylindrical body.
  • the CO2 laser source 1 may have a diameter of about 60 mm or less, or about 55 mm or less.
  • the CO2 laser source 1 may have a diameter of about 50 mm.
  • FIG. 3 schematically depicts a side view of an electromagnetic radiation steering mechanism 2 comprising an electromagnetic radiation manipulator “a”, “b” according to an embodiment of the invention.
  • the electromagnetic radiation steering mechanism 2 (or “deflection unit”) may be of the type described in international patent application W02019/101887, which is incorporated herein by reference.
  • the electromagnetic radiation steering mechanism comprises a first optical element 100A having an associated first actuator A configured to rotate the first optical element 100A about a first rotational axis 160 to change a first coordinate of a first steering axis in the two-dimensional field of view.
  • the electromagnetic radiation steering mechanism further comprises a second optical element 100B having an associated second actuator B configured to rotate the second optical element 100B about a second rotational axis 170 to change a second coordinate of a second steering axis in the two-dimensional field of view.
  • the first and second actuators A, B may get hot during use. Cooling fluid inlets 943, 947 and outlets 945, 949 of an active fluid cooling system (described in greater detail below) are configured to provide cooling to the first and second actuators A, B.
  • the first optical element 100A is adjacent the second optical element 100B.
  • the first optical element 100A is offset from the second optical element 100B along an axis that is substantially parallel to the first and second rotational axes 160, 170.
  • the first optical element 100A comprises a first reflective surface configured to receive and reflect electromagnetic radiation 105 and the second optical element 100B comprises a second reflective surface configured to receive and reflect the electromagnetic radiation 105.
  • the first rotational axis 160 and the first reflective surface are substantially parallel, and the second rotational axis 170 and the second reflective surface are substantially parallel.
  • the first and second rotational axes 160, 170 are substantially parallel to the first direction 800.
  • the first and second reflective surfaces are substantially parallel to the first direction 800.
  • the electromagnetic radiation steering mechanism further comprises an electromagnetic radiation manipulator “a”, “b” optically disposed between the first and second optical elements 100A, 100B.
  • the first optical element 100A is configured to receive electromagnetic radiation 105 and direct the electromagnetic radiation 105 to the electromagnetic radiation manipulator “a”, “b”.
  • the electromagnetic radiation manipulator “a”, “b” is configured to direct the electromagnetic radiation 105 to the second optical element 100B.
  • the second optical element 100B may be configured to direct the electromagnetic radiation 105 to an optical output of the electromagnetic radiation steering mechanism.
  • the electromagnetic radiation manipulator comprises a first mirror “a” and a second mirror “b”.
  • the first mirror “a” is configured to receive the electromagnetic radiation 105 after the electromagnetic radiation 105 has interacted with the first optical element 100A and direct the electromagnetic radiation 105 to the second mirror “b”.
  • the second mirror “b” is configured to receive the electromagnetic radiation 105 after the electromagnetic radiation 105 has interacted with the first mirror “a” and direct the electromagnetic radiation 105 to the second optical element 100B.
  • the first mirror “a” and the second mirror “b” are fixed with respect to each other.
  • the first mirror “a” is arranged so as to apply about a 90° change in a propagation direction of the electromagnetic radiation 105. To achieve this, the first mirror “a” may be optically disposed at a 45° angle with respect to incident electromagnetic radiation 105.
  • the second mirror “b” is arranged so as to apply about a 90° change in a propagation direction of the electromagnetic radiation 105. To achieve this, the second mirror “b” may be optically disposed at a 45° angle with respect to incident electromagnetic radiation 105.
  • a first angle is defined between the first and second rotational axes 160, 170 and a second angle is defined between the first and second steering axes.
  • the electromagnetic radiation manipulator “a”, “b” is configured to introduce a difference between the first angle and the second angle.
  • the first rotational axis 160 and the second rotational axis 170 are non-orthogonal.
  • the first rotational axis 160 and the second rotational axis 170 are substantially parallel.
  • the first steering axis and the second steering axis are substantially orthogonal. That is, the electromagnetic radiation manipulator “a”, “b” is configured to introduce a difference of about 90° between the first angle and the second angle.
  • the electromagnetic radiation steering mechanism comprises a third reflector 110.
  • the electromagnetic radiation 105 is turned by the third reflector 110 by 90° to hit the first optical element 100A of the first actuator A.
  • This is useful in the formation of a coaxial device in which the electromagnetic radiation 105 generally propagates in a direction parallel to the first and second axes of rotation of the first and second optical elements 100A, 100B (e.g. when the electromagnetic radiation enters and exits the electromagnetic radiation steering mechanism).
  • the electromagnetic radiation propagates in a direction that is not along an axis parallel to the first and second axes of rotation.
  • the electromagnetic radiation manipulator advantageously enables the first and second rotational axes to be parallel with one another.
  • Further optical elements such as reflectors may be introduced to allow electromagnetic radiation to enter and exit the electromagnetic radiation steering mechanism along an axis parallel to the first and second rotational axes.
  • the electromagnetic radiation 105 may be turned by a fourth reflector (not shown) by 90°.
  • the electromagnetic radiation 105 may then exit the electromagnetic radiation steering mechanism and be incident upon an object such as a product that is to be marked by the electromagnetic radiation 105.
  • the first rotational axis and the second rotational axes are substantially parallel and the electromagnetic radiation steering mechanism is installed substantially parallel to a length of the marking head 500 of the laser marking system such that an axis of the marking head 500 that is parallel to the length (i.e. the greatest of three dimensions) of the marking head 500 is substantially parallel to the first and second axes of rotation of the first and second optical elements 100A, 100B.
  • the compact arrangement of the components of both the CO2 laser source 1 and the electromagnetic radiation steering mechanism 2 provides a significant reduction in the weight and volume of the marking head compared to known marking heads.
  • the marking head has a mass of about 15 kg or less.
  • the marking head may have a mass of about 10 kg or less, about 5 kg or less, about 3 kg or less, or about 2 kg or less.
  • the marking head may have a mass of about 1.5 kg.
  • the marking head has a volume of about 10 I or less.
  • the marking head may have a volume of about 5 I or less, about 3 I or less, about 2 I or less, or about 1.5 I or less.
  • the marking head may have a volume of about 1 I.
  • the marking head has a length of about 500 mm or less.
  • the marking head may have a length of about 400 mm or less, or about 350 mm or less.
  • the marking head may have a length of about 310 mm.
  • the marking head comprises a cylindrical housing.
  • the marking head has a diameter of about 100 mm or less.
  • the marking head may have a diameter of about 90 mm, or less, about 80 mm or less, about 70 mm or less, or about 65 mm or less.
  • the marking head may have a diameter of about 64 mm.
  • the marking head comprises an active fluid cooling system 942, 944, 946, 948.
  • the active fluid cooling system comprises a first fluid inlet 942 and outlet 944 pair and a second fluid inlet 946 and outlet 948 pair.
  • Each fluid inlet 942, 946 conveys cool fluid into the marking head and thereby cools components of the marking head.
  • Each fluid outlet 944, 948 conveys fluid heated by the components of the marking head out of the marking head.
  • the fluid inlet and outlet pairs 942, 944, 946, 948 may form part of a cooling system in which the cooling fluid is cooled and recycled as is conventional in the art.
  • the fluid may, for example, comprise water. Other fluids may be used.
  • the active fluid cooling system 942, 944, 946, 948 is configured to cool the pair of electrodes 934, 936 of the CO2 laser source 1.
  • Fig. 12 schematically depicts a cross-sectional side view of the active cooling system 942, 944, 946, 948 cooling the first and second electrodes 936, 934 of the CO2 laser source 1 in accordance with an aspect of the present disclosure.
  • the first fluid inlet and outlet pair 942, 944 is configured to cool the first electrode 936 of the CO2 laser source 1.
  • the second fluid inlet and outlet pair 946, 948 is configured to cool the second electrode 934.
  • the active fluid cooling system 942, 944, 946, 948 comprises a blind hole 700, 710 formed in each of the pair of electrodes 934, 936 for conveying a cooling fluid.
  • a flow of the cooling fluid is shown by arrows in Fig. 12.
  • Each fluid inlet 942, 946 comprises a conduit formed of a thermally conductive material (such as, for example, tin) having a diameter smaller than the diameter of its respective blind hole 700, 710.
  • the conduits may be inserted into the blind holes 700, 710 such that an annular gap exists between an outer wall of the fluid inlets 942, 946 and an inner wall of the blind holes 700, 710.
  • a cooling fluid such as, for example, water may be provided through the fluid inlets 942, 946.
  • the cooling fluid flows back within the annular gap between the outer wall of the fluid inlets 942, 946 and the inner wall of the blind holes 700, 710 thereby cooling the inner wall of the blind holes 700, 710 formed in the electrodes 934, 936.
  • the fluid that has removed heat energy from the electrodes 934, 936 exits the blind holes 700, 710 via the fluid outlets 944, 948.
  • the active fluid cooling system is configured to cool the first and second actuators A, B of the electromagnetic radiation steering mechanism 2.
  • the active cooling system may comprise third 943, 945 and fourth 947, 949 pairs of fluid inlets 943, 947 and outlets 945, 949.
  • the third fluid inlet and outlet pair 943, 945 is configured to cool the first actuator A.
  • the fourth fluid inlet and outlet pair 947, 949 is configured to cool the second actuator B.
  • the fluid inlet and outlet pairs 943, 945, 947, 949 may be arranged in blind holes 720, 730 formed in a body that is configured to support the actuators A, B rather than inside the actuators A, B themselves.
  • the third and fourth fluid inlet and outlet pairs 943, 945, 947, 949 may cool a body of the electromagnetic radiation steering mechanism 2 proximate the actuators A, B and thereby indirectly cool the actuators A, B.
  • separate flows of cooling fluid may be provided to each fluid inlet and outlet pair 942, 944, 946, 948, 943, 945, 947, 949 such that each fluid inlet 942, 946, 943, 947 conveys cool water in parallel and each fluid outlet 944, 948, 945, 949 conveys heated water in parallel.
  • the active fluid cooling system may comprise a blower (not shown) and one or more heat dissipation structures (not shown), such as one or more fins, in thermal communication with the electrodes 934, 936 and/or the actuators A, B.
  • the blower is configured to generate a flow of air across the one or more elongate heat dissipation structures and thereby transfer heat energy away from the electrodes 934, 936 and/or actuators A, B.
  • any suitable cooling system may be used.
  • the gas mixture comprising CO2 acts as a heat source when in use.
  • Any appropriate heat sink e.g. a cooler of a cooling fluid system, ambient air receiving heat from heat dissipation structures, etc.
  • a distance between the heat source and the heat sink may depend upon the type of heat sink used.
  • the heat transfer medium between the heat source and the heat sink is a cooling fluid (e.g. water) and the distance between the heat source and the heat sink may be a few meters or less. If the heat source and heat sink are closer (e.g. about 25 cm or less), then solid heat pipes may be used as the heat transfer medium.
  • heat dissipation structures e.g. aluminium fins
  • cooling fins may surround and project from a body of the CO2 laser source 1.
  • the marking head may form part of a laser marking system for marking a product.
  • the laser marking system comprises a supply unit 150 and an umbilical assembly 160 connecting the supply unit 150 to the marking head.
  • the umbilical assembly 160 may have a length of about 3 m or more.
  • the umbilical assembly 160 may have a length of about 10 m or less.
  • the umbilical assembly 160 is configured to transmit signals (e.g. power signals such as an RF power input provided to the CO2 laser source 1 via a coaxial cable, control signals, sensor signals, etc.) and the cooling fluid between the supply unit 150 and the marking head.
  • signals e.g. power signals such as an RF power input provided to the CO2 laser source 1 via a coaxial cable, control signals, sensor signals, etc.
  • the laser marking system comprises a sealing plug 170 configured to receive the umbilical assembly 160 at a first end and the CO2 laser source 1 at a second end.
  • the marking head comprises a cylindrical housing 180.
  • the marking head comprises an end cap 190 having a window for emitting the electromagnetic radiation towards a product to be marked.
  • a first cross-sectional plane 210 is shown through the electromagnetic radiation steering mechanism 2.
  • a second cross-sectional plane 220 is shown through the CO2 laser source 1.
  • the cross-sectional planes 210, 220 are shown from a head on view in Fig. 5.
  • Fig. 6 schematically depicts a cross-sectional view 230 of the laser marking head at the second cross-sectional plane 220 when the CO2 laser source 1 is installed in the cylindrical housing 180 of marking head, and a cross sectional view of the umbilical assembly 160.
  • the umbilical assembly 160 comprises a first electrical connection 161 between the first actuator A and the supply unit 150 and a second electrical connection 162 between the second actuator B and the supply unit 150.
  • the umbilical assembly 160 comprises a third electrical connection 163 between a sensor (not shown) located in the marking head and the supply unit 150.
  • the third electrical connection 163 may comprise a plurality of electrical connections between a plurality of sensors located in the marking head and the supply unit 150.
  • the plurality of sensors may comprise, for example, one or more temperature sensors (e.g. for monitoring a temperature of the electromagnetic radiation steering mechanism 2), one or more radiation sensors (e.g. for detecting failure of the CO2 laser source 1 or for detecting stray radiation for satisfying laser safety requirements), one or more position sensors (e.g. for determining whether or not the marking head is correctly mounted to a production line or robotic arm), one or more image sensors (e.g. for providing images of products to a marking feedback system), one or more gyro-sensors (e.g. for determining an orientation of the marking head), etc.
  • one or more temperature sensors e.g. for monitoring a temperature of the electromagnetic radiation steering mechanism 2
  • one or more radiation sensors e.g. for detecting failure of the CO2 laser source 1 or for detecting stray radiation for satisfying laser safety requirements
  • one or more position sensors e.g. for determining whether or not the marking head is correctly mounted to a production line or robotic arm
  • image sensors e.g. for providing images
  • the umbilical assembly 160 comprises a first conduit 942, 946, 943, 947 (for providing cooling fluid to the fluid inlets) configured to transmit the cooling fluid from the supply unit 150 to the marking head and a second conduit 944, 948, 945, 949 (for providing cooling fluid to the fluid outlets) configured to transmit the cooling fluid that has received heat from the components of the marking head from the marking head to the supply unit 150.
  • the umbilical assembly 160 comprises a fourth electrical connection 164 between a third actuator of a variable optical path length assembly (described below with reference to Fig. 7) and the supply unit 150.
  • the umbilical assembly 160 comprises a fifth electrical connection 165 between an RF energy supply (not shown) in the supply unit 150 and the pair of electrodes in the CO2 laser source 1.
  • the first, second, third and fourth electrical connections 161-164 and the first and second conduits 942, 946, 943, 947, 944, 948, 945, 949 are arranged in a space between the CO2 laser source 1 and the cylindrical housing 180 of the marking head.
  • Fig. 7 schematically depicts an embodiment of a variable optical path length device 301 in a plan view and a perspective view, respectively.
  • the variable optical path length device may be housed in a marking head along with the electromagnetic radiation steering mechanism.
  • a light beam 305 is illustrated entering the device through a first lens 310.
  • the light beam 305 may be received from the laser source along an optical fibre, or may be generated within the marking head itself.
  • the first lens 310 may have a diameter of, for example, about 10 mm. After passing through the first lens 310, the light beam 305 impinges onto a first optical element 315, for example, a first of a pair of movable mirrors 315, 320.
  • the light beam 305 is reflected from the reflective surface 315a of the first movable mirror 315 onto the reflective surface 320a of the second mirror 320 of the pair of movable mirrors 315, 320.
  • the pair of movable mirrors 315, 320 is mounted to a rotating base 325 that may rotate about an axis normal to the surface of the rotating base 325.
  • the axis of the rotating base passes through a center point 302 between the pair of movable mirrors 315, 320.
  • a rotational actuator e.g. a galvanometer motor
  • the light beam 305 is reflected from the reflective surface 320a of the second movable mirror 320 into a corner reflector 330, which may include a pair of perpendicular mirrors 330a, 330b (or alternatively, a reflecting prism with perpendicular reflecting facets).
  • the light beam 305 is reflected from the corner reflector 330 back in the opposite direction from which it entered the corner reflector 330 and impinges back onto the reflective surface 320a of the second movable mirror 320.
  • the light beam 305 impinges on the second movable mirror 320 after being reflected back from the corner reflector 330 at a different vertical position from a position at which the light beam impinged on the second movable mirror 320 after being directed toward the second movable mirror 320 by the first movable mirror 315.
  • the difference in vertical position is related to the vertical distance between portion of the mirrors 330a, 330b of the corner reflector 330 that the light beam 305 reflected off of.
  • the light beam 305 is reflected from the reflective surface 320a of the second movable mirror 320 back onto the reflective surface 315a of the first movable mirror 315.
  • the light beam 305 impinges on the first movable mirror 315 after being reflected back from the second movable mirror 320 at a different vertical position from a position at which the light beam impinged on the first movable mirror 315 from the first lens 310.
  • the light beam 305 is then reflected from the reflective surface 315a of the first movable mirror 315 onto a reflective surface 335a of an output mirror 335.
  • the output mirror 335 is vertically displaced from the first lens 310.
  • the light beam 305 is reflected from the output mirror 335 though a second lens 340, which may also be referred to as an output lens.
  • the second lens 340 is vertically displaced relative to the first lens 310.
  • the light beam passes through the second lens 340 and out of the variable optical path length device 100.
  • the mirrors 315, 320 may be referred to collectively, along with the base 325 as a rotatable path length adjuster 360.
  • a rotatable path length adjuster 360 It will be appreciated that the relationship between focal length and the orientation of the rotatable path length adjuster 360 will depend upon the optical power of the input and output lenses, as well as the geometry of the rotatable path length adjuster 360, and the other components of the variable optical path length assembly 100. For example, by increasing the distance of the mirrors from the axis of rotation, the change in geometric path length for a given rotational change will also increase.
  • the variable optical path length assembly 100 may comprise alternative actuation means for adjusting the focal length of the marking head such as, for example, voice coils, piezoelectric elements, linear drives, etc.
  • FIG. 8 shows a flowchart of a method of marking a product using a CO2 laser source and an electromagnetic radiation steering mechanism.
  • a first step 400 of the method comprises using the CO2 laser source to generate electromagnetic radiation.
  • a second step 410 of the method comprises receiving the electromagnetic radiation at a first optical element that is rotatable about a first rotational axis to change a first coordinate of a first steering axis in the two-dimensional field of view.
  • a third step 420 of the method comprises directing the electromagnetic radiation to an electromagnetic radiation manipulator optically disposed between the first optical element and a second optical element.
  • a fourth step 430 of the method comprises directing the electromagnetic radiation to the second optical element that is rotatable about a second rotational axis to change a second coordinate of a second steering axis in the two-dimensional field of view.
  • a fifth step 440 of the method comprises defining a first angle between the first and second rotational axes.
  • a sixth step 450 of the method comprises defining a second angle between the first and second steering axes.
  • a seventh step 460 of the method comprises using the electromagnetic radiation manipulator to introduce a difference between the first angle and the second angle.
  • An eighth step 470 of the method comprises steering the electromagnetic radiation about the product by rotating the first and second optical elements.
  • the CO2 laser source and the electromagnetic radiation steering mechanism are disposed within a marking head.
  • the CO2 laser source has a dimension in a first direction that is greater than a dimension of the CO2 laser source in either orthogonal direction to the first direction.
  • the marking head has a dimension in the first direction that is greater than a dimension of the marking head in either orthogonal direction to the first direction.
  • the CO2 laser source is installed substantially parallel to the marking head such that a length of the marking head is substantially parallel to a length of the CO2 laser source.
  • FIG. 9 shows a flowchart of a method of assembling a marking head.
  • a first step 500 of the method comprises mounting a first optical element and an associated first actuator that is configured to rotate the first optical element about a first rotational axis to change a first coordinate of a first steering axis in the two-dimensional field of view.
  • a second step 510 of the method comprises mounting a second optical element having an associated second actuator that is configured to rotate the second optical element about a second rotational axis to change a second coordinate of a second steering axis in the two-dimensional field of view.
  • a third step 520 of the method comprises optically disposing an electromagnetic radiation manipulator between the first and second optical elements. A first angle is defined between the first and second rotational axes.
  • a second angle is defined between the first and second steering axes.
  • the electromagnetic radiation manipulator is configured to introduce a difference between the first angle and the second angle.
  • a fourth step 530 of the method comprises disposing a CO2 laser source within the marking head.
  • the CO2 laser source has a dimension in a first direction that is greater than a dimension of the CO2 laser source in either orthogonal direction to the first direction.
  • the marking head has a dimension in the first direction that is greater than a dimension of the marking head in either orthogonal direction to the first direction.
  • the CO2 laser source is installed substantially parallel to the marking head such that a length of the marking head is substantially parallel to a length of the CO2 laser source.
  • the CO2 laser source 1 is configured to generate and direct the electromagnetic radiation 105 in a direction parallel to the first and second axes of rotation of the electromagnetic radiation steering mechanism 2.
  • An alignment between the CO2 laser source 1 and the electromagnetic steering mechanism 2 may be achieved using an alignment mount located between the CO2 laser source 1 and the electromagnetic radiation steering mechanism 2.
  • the alignment mount may, for example, comprise one or more dowel pins.
  • the marking head may comprise an alignment mount configured to receive the CO2 laser source 1 and the electromagnetic radiation steering mechanism 2 such that the electromagnetic radiation generated by the CO2 laser source 1 propagates to an input of the electromagnetic radiation steering mechanism 2 in a desired direction.
  • Fig. 10 schematically depicts the CO2 laser source 1, the electromagnetic radiation steering mechanism 2 and an alignment mount 600 according to an aspect of the present disclosure.
  • the CO2 laser source 1 may emit radiation in a direction 601 that is angularly offset from a desired emission direction 602.
  • the angular offset may arise through manufacturing tolerances (e.g. imperfections present in the optical components of the CO2 laser source 1 and/or misalignment of components of the CO2 laser source 1 during manufacture) and/or operating variables (e.g. irregularities in an electric field generated between the electrodes 934, 936 and/or thermal expansion of one or more components of the CO2 laser source 1).
  • the angular offset may be referred to as an angular beam walk 601.
  • the desired emission direction 602 may be parallel to a length of the CO2 laser source 1.
  • the CO2 laser source 1 emits radiation in a direction 601 that is non-parallel with the length of the CO2 laser source 1.
  • the extent of the non-parallel emission of radiation from the CO2 laser source 1 has been exaggerated in the example of Fig. 10 for ease of viewing.
  • the electromagnetic radiation steering mechanism 2 is configured to receive radiation from the CO2 laser source 1 in the desired direction 602.
  • the electromagnetic radiation steering mechanism 2 is configured to receive radiation in a direction 602 that is parallel to a length of the electromagnetic radiation steering mechanism 2.
  • the alignment mount 600 comprises a first protrusion 610 configured to be inserted into a first cavity 620 of the electromagnetic radiation steering mechanism 2.
  • the alignment mount 600 comprises a second protrusion 630 configured to be inserted into a second cavity 640 of the electromagnetic radiation steering mechanism 2.
  • the first and second protrusions 610, 630 of the alignment mount 600 may act as dowel pins that are configured to be inserted into the first and second cavities 620, 640 of the electromagnetic radiation steering mechanism 2.
  • the first protrusion 610 of the alignment mount 600 comprises a first cavity 660 configured to receive a first protrusion 650 of the CO2 laser source 1.
  • the second protrusion 630 of the alignment mount 600 comprises a second cavity 680 configured to receive a second protrusion 670 of the CO2 laser source 1.
  • the first and second protrusions 650, 670 of the CO2 laser source 1 may act as dowel pins that are configured to be inserted into the first and second cavities 660, 680 of the alignment mount 600.
  • the first protrusion 650 of the CO2 laser source 1 may solely act as an alignment feature.
  • the first protrusion 650 of the CO2 laser source 1 may be dual purpose.
  • the first protrusion 650 of the CO2 laser source may also correspond to a connector for receiving power or cooling fluid.
  • the second protrusion 670 of the CO2 laser source 1 may correspond to a beam exit of the CO2 laser source 1.
  • the second protrusion 630 of the alignment mount 600 is open-ended in order to allow radiation generated by the CO2 laser source 1 to pass through both the second protrusion 630 and the second cavity 640 and into the electromagnetic radiation steering mechanism 2.
  • An alignment between the first and second protrusions 650, 670 of the CO2 laser source 1 and the first and second cavities 660, 680 of the alignment mount 600 may be adjusted to correct for the angular beam walk 601 before being fixed in place.
  • the first and second protrusions 610, 630 of the alignment mount 600 may then be inserted into the first and second cavities 620, 640 of the electromagnetic radiation steering mechanism 2 to complete mounting of the CO2 laser source 1 to the electromagnetic radiation steering mechanism 2.
  • Figs. 11 A-C show this process in greater detail.
  • Fig. 11A schematically depicts a first step of a method of connecting the CO2 laser source 1 to the electromagnetic radiation steering mechanism 2.
  • the first step comprises inserting the first and second protrusions 650, 670 of the CO2 laser source 1 into the first and second cavities 660, 680 of the alignment mount 600.
  • the first step comprises using an alignment sensor 690 to detect an angular offset 601 of the radiation emitted by the CO2 laser source 1 relative to a desired emission direction 602.
  • the alignment sensor 690 may, for example, comprise a quadrant detector configured to detect infrared radiation generated by a CO2 laser source 1.
  • Fig. 11 B schematically depicts a second step of the method of connecting the CO2 laser source 1 to the electromagnetic radiation steering mechanism 2.
  • the second step comprises adjusting a position of the CO2 laser source 1 relative to the alignment mount 600 such that the CO2 laser source 1 emits radiation in the desired direction 602 as detected by the alignment sensor 690.
  • the second step comprises fixing the CO2 laser source 1 relative to the alignment mount 600 when the alignment sensor 690 detects that the desired direction 602 has been reached.
  • Fixing the CO2 laser source 1 relative to the alignment mount 600 may comprise providing an adhesive 695 between the first and second protrusions 650, 670 of the CO2 laser source 1 and the first and second cavities 660, 680 of the alignment mount 600.
  • the adhesive 695 may, for example, comprise an ultraviolet (UV) cured glue that is applied and cured through one or more gaps or holes provided in the alignment mount 600.
  • UV ultraviolet
  • Fig. 11C schematically depicts a third step of the method of connecting the CO2 laser source 1 to the electromagnetic radiation steering mechanism 2.
  • the third step comprises inserting the first and second protrusions 610, 630 of the alignment mount 600 into the first and second cavities 620, 640 of the electromagnetic radiation steering mechanism 2.
  • the alignment mount 600 and alignment method ensures that the CO2 laser source 1 emits radiation in the desired direction 602 relative to the electromagnetic radiation steering mechanism 2.
  • Embodiments of a marking head disclosed herein may include at least two actuators A, B such as piezoelectric or magnet drives, direct current drives, stepper motors, servomotors, or galvanometers having mirrors attached.
  • actuators A, B such as piezoelectric or magnet drives, direct current drives, stepper motors, servomotors, or galvanometers having mirrors attached.
  • the electromagnetic radiation steering mechanism may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and/or other types of optical components, or any combination thereof, for directing, shaping, and/or controlling electromagnetic radiation.
  • optical components such as refractive, reflective, magnetic, electromagnetic, electrostatic, and/or other types of optical components, or any combination thereof, for directing, shaping, and/or controlling electromagnetic radiation.
  • the mirrors used in embodiments of the marking head disclosed herein may be silver coated or gold coated mirrors or any other suitably coated material.
  • Windows and lenses used in embodiments of the marking head disclosed herein may be, for example, germanium, zinc selenide, quartz, BK7 borosilicate glass, or any other suitable material.
  • the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
  • the term “plurality” refers to two or more items or components.
  • dimensions which are described as being “substantially” similar may be considered to be within about 25% of one another.
  • the terms “comprising,” “including,” “carrying,” “having,” “containing,” and “involving,” whether in the written description or the claims and the like, are open- ended terms, i.e. , to mean “including but not limited to.” Thus, the use of such terms is meant to encompass the items listed thereafter, and equivalents thereof, as well as additional items.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Optics & Photonics (AREA)
  • Plasma & Fusion (AREA)
  • Electromagnetism (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Laser Beam Processing (AREA)

Abstract

Tête de marquage pour un système de marquage laser comprenant une source laser CO2 configurée pour générer un rayonnement électromagnétique, et un mécanisme de direction de rayonnement électromagnétique configuré pour diriger le rayonnement électromagnétique vers un emplacement spécifique dans un champ de vue bidimensionnel. Le mécanisme de direction de rayonnement électromagnétique comprend un manipulateur de rayonnement électromagnétique configuré pour introduire une différence entre un premier angle défini entre de premier et second axes de rotation et un second angle défini entre de premier et second axes de direction. La source laser CO2 comprend une dimension dans une première direction qui est supérieure à une dimension de la source laser CO2 dans une direction orthogonale à la première direction. La tête de marquage comprend une dimension dans la première direction qui est supérieure à une dimension de la tête de marquage dans une direction orthogonale à la première direction.
PCT/EP2024/065583 2023-06-07 2024-06-06 Tête de marquage laser Ceased WO2024251870A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB2308474.2 2023-06-07
GBGB2308474.2A GB202308474D0 (en) 2023-06-07 2023-06-07 Laser marking head

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WO2024251870A2 true WO2024251870A2 (fr) 2024-12-12
WO2024251870A3 WO2024251870A3 (fr) 2025-01-16

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019101887A1 (fr) 2017-11-22 2019-05-31 Alltec Angewandte Laserlicht Technologie Gmbh Mécanisme d'orientation de rayonnement électromagnétique

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Publication number Priority date Publication date Assignee Title
JP4614443B2 (ja) * 2005-08-31 2011-01-19 パナソニック電工Ｓｕｎｘ株式会社 レーザ加工装置
US8422528B2 (en) * 2011-02-24 2013-04-16 Iradion Laser, Inc. Ceramic slab, free-space and waveguide lasers
CN109906534B (zh) * 2016-09-20 2021-04-23 依拉迪激光有限公司 具有缩进孔口的激光器

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019101887A1 (fr) 2017-11-22 2019-05-31 Alltec Angewandte Laserlicht Technologie Gmbh Mécanisme d'orientation de rayonnement électromagnétique

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