WO2006128054A1 - Apparatus for minimizing a heat affected zone during laser micro-machining - Google Patents
Apparatus for minimizing a heat affected zone during laser micro-machining Download PDFInfo
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- WO2006128054A1 WO2006128054A1 PCT/US2006/020606 US2006020606W WO2006128054A1 WO 2006128054 A1 WO2006128054 A1 WO 2006128054A1 US 2006020606 W US2006020606 W US 2006020606W WO 2006128054 A1 WO2006128054 A1 WO 2006128054A1
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- machining
- laser
- Prior art date
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
- B23K26/066—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms by using masks
- B23K26/0661—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms by using masks disposed on the workpiece
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
- B23K26/066—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms by using masks
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/067—Dividing the beam into multiple beams, e.g. multifocusing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/067—Dividing the beam into multiple beams, e.g. multifocusing
- B23K26/0676—Dividing the beam into multiple beams, e.g. multifocusing into dependently operating sub-beams, e.g. an array of spots with fixed spatial relationship or for performing simultaneously identical operations
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/073—Shaping the laser spot
- B23K26/0738—Shaping the laser spot into a linear shape
-
- 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
- B23K26/361—Removing material for deburring or mechanical trimming
Definitions
- Embodiments of the present invention are directed to machining processes, and more particularly, to laser micro-machining.
- HAZ Heat Affected Zone
- the energy contained in the plasma plume is dependent on raw material composition, laser fluence and the contiguous area of the machining site.
- Laser fluence is typically set to optimize parameters such as machined edge quality, material removal rate, debris formation and other attributes on the finished part. Accordingly, for a given fluence, the volume of the plasma plume is dependent on the total contiguous area of the machined site. Accordingly, the larger the area, the larger the plasma plume volume. Moreover, the volume of the plasma plume determines the magnitude of localized heating (i.e., the HAZ) of the perimeter of the machining site.
- HAZ localized heating
- Fig. IA illustrates a relatively large contiguous area being machined and an associated large plasma plume
- Fig. IB illustrates a small plume associated with a smaller machined area.
- the smaller plume will be cooled/quenched quicker since a larger fraction of the plasma plume surface area is in contact with air.
- the maximum laser pulse repetition rate is limited to a rate that produces an acceptable Heat Affected Zone (HAZ).
- HAZ Heat Affected Zone
- the laser pulse rate is too high, the magnitude and rate of plasma formation cause heating of un- machined material around the machined area causing an unacceptable HAZ.
- throughput of laser micro-machining could be increased if the one were able to limit the volume of the plume associated with the machined area.
- embodiments of the present invention increase throughput of laser micro- machining by decreasing the ratio of plasma plume volume to machined perimeter length while maintaining the total machining site area.
- some embodiments of the invention present methods and systems for minimizing a heated region created during a laser, micro- machining process. This may be accomplished by subdividing (for example) the laser beam into noncontiguous machining elements.
- a method for laser micro- machining which may include dividing a long line illumination field into a plurality of individual fields, wherein each of the plurality of fields includes an aspect ratio of about 4:1 or greater, directing the plurality of individual fields onto at least one mask, wherein each individual field illuminates a corresponding area on the mask and translating the mask and/or workpiece relative to one another along a scan axis.
- a system for laser micro-machining may include an optical source comprising a laser beam, dividing means for dividing a long line illumination field into a plurality of individual fields, wherein each of the plurality of fields includes a aspect ratio of about 4:1 or greater, directing means for directing the plurality of individual fields onto at least one mask, wherein each individual field illuminates a corresponding area on the mask and translating means for translating the mask and/or workpiece relative to one another along a scan axis.
- Fig. IA illustrates a laser plume associated with laser micro-machining a workpiece according to the prior art.
- Fig. IB illustrates a laser plume associated with laser micro-machining according to embodiments of the present invention.
- Fig. 2 is a schematic diagram of a laser micro-machining system according to another embodiment of the present invention.
- Fig. 3 illustrates an example of a finished part.
- Fig. 4 illustrates a prior art mask projection for laser micro-machining.
- Fig. 5 illustrates an example of a mask projection for laser micro-machining according to an embodiment of the present invention.
- Fig. 6 illustrates another example of a mask projection for laser micro-machining according to another embodiment of the present invention.
- Fig. 7 illustrates still another example of a mask projection for laser micro-machining according to anther embodiment of the present invention.
- Fig. 8 illustrates still yet another example of a mask projection for laser micro-machining according to another embodiment of the present invention.
- Fig. 9 is a schematic diagram of components to a laser micro-machining system according to another embodiment of the present invention.
- Embodiments of the present invention enable high throughput laser micro-machining while limiting the size of a laser plume.
- an exemplary laser micro-machining apparatus which may be used with embodiments of the present invention is shown in Fig. 2.
- an illumination source 202 emits a beam of light (laser beam) which is then expanded with a 2-element telescope 204 (for example) and which may be folded down with a 45 degree mirror 206. The light may then brought to focus at a beam shaping aperture 208.
- the beam shaping aperture maybe used as a mask to create an illumination shape (e.g., square, rectangle, triangle, etc.).
- the beam shaper plane may then be imaged to infinity (for example) by a collimator lens 210, which then may impinge the beam onto an array 212 of lens elements. Each lens element may then intercept a portion of the colliniated beam and forms an image of the beam shaper plane at the mask 214.
- An imaging lens 215 may then be used to image the projection of the mask on the workpiece. Accordingly, the light emitted by the laser may be efficiently segmented into shapes which illuminate the mask. From the mask, the light is then used to ablate material on the workpiece.
- Applicants' co-pending U.S. patent application no. 10/839,026, herein incorporated by reference also discloses a micro-machining system which may be used with embodiments of the present invention.
- the mask pattern may be a planar or cylindrical pattern (i.e., a planar pattern that has been "unwrapped" from a cylinder onto a planar surface), a magnified image of a planar pattern for a planar workpiece, and that a series of masks may be used — each mask representing a portion of a planar pattern for the workpiece and used sequentially (the series of masks may also be magnified images of portions of the planar pattern).
- Fig. 3 illustrates the geometry of a planar micro-machined part that will be used in the examples that follow.
- a projected illumination distribution for a laser micro-machining system is generally the product of the illumination distribution of the laser multiplied by the mask . transmission function. As shown in Fig. 3, the opaque areas (cross-hatched areas) include a transmission of about zero, while the clear area (white area) includes a transmission near unity (for example).
- the transmitted illumination distribution may be simultaneously projected on the surface of the raw material to perform the machining operation. To make multiple parts, for example, the illuminated field maybe step-and-repeat imaged over the surface of the raw material.
- Fig. 4 illustrates the image plane of a prior art mask projection micro-machining system.
- the mask area is illuminated with a uniform beam of laser illumination (dotted line) along a large field.
- the field aspect ratio (width to height) of the beam is generally between 1 : 1 and 2:1. While larger field aspect ratios of the beam are conceivable, one skilled in the art will appreciate that such systems are impractical due to the high cost of constructing a system due to cost and size of the optics involved (e.g., see co-pending application no. 10/839,026).
- perimeter to area ratios for 1 : 1 and 2:1 aspect ratios for example correspond to a perimeter to area ratios of 4: 1 and 4.2:1, respectively (e.g., assuming a one (1) centimeter field area). Accordingly, some embodiments of the present invention increase such perimeter to area ratios to minimize the HAZ to an acceptable level, e.g., a level which does not impact material properties. This results in an increased throughput of a laser micro-machining system.
- Fig. 5 illustrates one embodiment of the invention where the illuminated field (dotted line) includes a long line shape having an increased aspect ratio.
- the increased aspect ratio results in a higher ratio of perimeter to area which results in a greater percentage of the plasma plume volume being quenched, thereby limiting HAZ.
- a one (1) centimeter field area may correspond to a 20:1 aspect ratio and a 9.4:1 perimeter to area ratio.
- the high aspect illumination field may be generated using the system disclosed in Applicants' co-pending U.S. patent application no. 10/839,026.
- the overall amount of material removed from the workpiece may be reduced due to a stenciling configuration incorporated into the mask design (for example). Specifically, as can be seen in Fig. 4, more material (e.g., additional material at the top and bottom) is removed in the prior art, while only a slug of residual material is produced at the center of the part in the current embodiment (Fig. 5). This also reduces the thermal loading of the un-machined material.
- Fig. 6 illustrates yet another embodiment of the invention, hi this embodiment, the illuminated field area is further subdivided into a plurality of long linear fields (i.e., high aspect ratio fields).
- the mask may be translated through the array of illuminated fields and/or the workpiece is moved relative to the mask (e.g., in opposite directions) to execute COM scanning.
- Some embodiments of the invention allow for the relative translation of the mask and workpiece in opposite directions multiple times.
- actuator(s) 216 or other moving means; e.g., a linear motor driven support plate, and the like
- the workpiece may also include an additional actuator(s) 218, which may be used in addition to or in place of the actuator(s) 216 of the mask, to accomplish the relative movement (e.g., along a line, in/around a plane and/or rotationally) between the mask and workpiece.
- an additional actuator(s) 218, which may be used in addition to or in place of the actuator(s) 216 of the mask, to accomplish the relative movement (e.g., along a line, in/around a plane and/or rotationally) between the mask and workpiece.
- a particular advantage of the present embodiment is that the increased subdivision of the illuminated fields may maintain machining throughput and provides a further enhancement to quench the plasma plume and further diminish HAZ.
- the division of the field area into a plurality of long line fields provides an even more substantial improvement in the perimeter to area ratio. For example, a one (1) square centimeter field can be subdivided into 20 fields, each having a 20:1 aspect ratio. Such an aspect ratio then corresponds to a perimeter to area ratio of 42:1 (for example).
- Fig. 7 illustrates a case where the scanning direction is oriented so that it is mis-aligned with the linear cut geometry of the part (e.g., at a 45 degree angle thereto).
- Exemplary configurations of this embodiment may include:
- Figs. 8 and 9 illustrate yet another embodiment whereby long line illumination fields may be subdivided into still smaller regions (e.g., square) which provide an even greater plasma plume quenching (i.e. a greater ratio of perimeter to area).
- regions e.g., square
- a full-segmentation COM configuration for this embodiment may resemble a halftone illumination pattern which maybe dithered to scan the illumination regions over the surface of the mask. Accordingly, if a one (1) square centimeter field is segmented into a 20 row by 20 column grid of small square fields of illumination, the perimeter to area ratio increases to 80:1.
- a laser micromachining apparatus such as (for example) a laser micromachining apparatus for copying an image of a planar mask onto a planar or cylindrical workpiece. This may be accomplished by translating the mask and planar workpiece synchronously, or translating the mask and rotating the cylindrical workpiece synchronously. Accordingly, at a given instance, the laser illuminates a selected area on the mask.
- An imaging system e.g., lens
- Still other embodiments of the invention may include a mask pattern which may be a representation of the planar image.
- the mask may be translated in a linear fashion while the workpiece is translated parallel to the mask motion.
- the mask and workpiece may be translated in opposite directions since the projection lens inverts the image of the mask.
- the mask pattern may be a representation of the unwrapped image of the cylinder, where the mask may be translated in a linear fashion while the cylindrical workpiece is rotated about an axis (e.g., of the cylinder).
- the cylinder and it rotation mechanism are preferably oriented such that the optical axis of the imaging system is perpendicular to its surface.
- the width of the image parallel to the scan direction of the mask may be limited.
- This may be accomplished through the use of a pre-mask aperture (see Fig. 9), which defines the instantaneous area of the mask pattern to be transmitted.
- the pre- mask aperture may be used to optimize the image width in relation to the depth of focus of the imaging system and the curvature of the cylinder.
- the pre-mask aperture may also be used to optimize the laser energy delivered locally per unit area per unit time, allowing greater control of ablation rates, and allowing thermally sensitive material to be processed at higher laser pulse repetition frequencies without altering the material.
Abstract
Embodiments of the present invention are directed to methods and systems for laser micro-machining, which may include dividing a long line illumination field into a plurality of individual fields, wherein each of the plurality of fields includes an aspect ratio of about 4:1 or greater, directing the plurality of individual fields onto at least one mask, wherein each individual field illuminates a corresponding area on the mask and translating the mask and/or workpiece relative to one another along a scan axis.
Description
APPARATUS FOR MINIMIZING A HEAT
AFFECTED ZONE DURING LASER MICRO-MACHINING
Field Of The Invention :
Embodiments of the present invention are directed to machining processes, and more particularly, to laser micro-machining.
Background
In micro-machining, a number of different material transformations exist which allow a laser beam to remove or machine material: ionization, melting/boiling, photo-chemical material modification and photo-chemical reaction with process gasses (for example). Material removal is typically accompanied by a plasma plume rising from the surface of the machined regions after a laser pulse is delivered. The duration of the plasma plume is short (typically 1 to 10 microseconds) but it possesses a very high temperature and the ions produced have high velocities.
Through a combination of conduction, convection and radiative transfer of energy from the region of the laser beam's interaction with the machining material and from the plasma plume arising from the decomposition products of the machined material a Heat Affected Zone
(HAZ) is created. The heat energy in the HAZ can alter the material properties of the un- machined material in an undesirable manner.
The energy contained in the plasma plume is dependent on raw material composition, laser fluence and the contiguous area of the machining site. Laser fluence is typically set to optimize parameters such as machined edge quality, material removal rate, debris formation and other attributes on the finished part. Accordingly, for a given fluence, the volume of the plasma plume is dependent on the total contiguous area of the machined site. Accordingly, the larger the area, the larger the plasma plume volume. Moreover, the volume of the plasma plume determines the magnitude of localized heating (i.e., the HAZ) of the perimeter of the machining site.
Larger plumes do not get cooled or quenched as quickly as smaller plumes since there is proportionately less surface area exposed to the air relative to the volume of the plume. For example, Fig. IA illustrates a relatively large contiguous area being machined and an associated large plasma plume, while Fig. IB illustrates a small plume associated with a smaller machined area. Thus, the smaller plume will be cooled/quenched quicker since a larger fraction of the plasma plume surface area is in contact with air.
For many materials undergoing pulsed laser micro-machining, the maximum laser pulse repetition rate is limited to a rate that produces an acceptable Heat Affected Zone (HAZ). When the laser pulse rate is too high, the magnitude and rate of plasma formation cause heating of un- machined material around the machined area causing an unacceptable HAZ. Although it is possible to reduce the laser pulse rate to allow material cooling between pulses, such a reduction results in a direct decrease in the throughput of the machining process. Thus, throughput of laser
micro-machining could be increased if the one were able to limit the volume of the plume associated with the machined area.
SUMMARY OF THE INVENTION
Accordingly, embodiments of the present invention increase throughput of laser micro- machining by decreasing the ratio of plasma plume volume to machined perimeter length while maintaining the total machining site area. To that end, some embodiments of the invention present methods and systems for minimizing a heated region created during a laser, micro- machining process. This may be accomplished by subdividing (for example) the laser beam into noncontiguous machining elements.
Accordingly, in one embodiment of the present invention, a method for laser micro- machining is presented which may include dividing a long line illumination field into a plurality of individual fields, wherein each of the plurality of fields includes an aspect ratio of about 4:1 or greater, directing the plurality of individual fields onto at least one mask, wherein each individual field illuminates a corresponding area on the mask and translating the mask and/or workpiece relative to one another along a scan axis.
hi another aspect of the present invention, a system for laser micro-machining is presented and may include an optical source comprising a laser beam, dividing means for dividing a long line illumination field into a plurality of individual fields, wherein each of the plurality of fields includes a aspect ratio of about 4:1 or greater, directing means for directing the plurality of individual fields onto at least one mask, wherein each individual field illuminates a
corresponding area on the mask and translating means for translating the mask and/or workpiece relative to one another along a scan axis.
These and other embodiments, objects and advantages of the invention will be readily apparent in view of the attached figures, briefly described below and following detailed description.
BRIEF DESCRIPTION OF THE FIGURES
Fig. IA illustrates a laser plume associated with laser micro-machining a workpiece according to the prior art.
Fig. IB illustrates a laser plume associated with laser micro-machining according to embodiments of the present invention.
Fig. 2 is a schematic diagram of a laser micro-machining system according to another embodiment of the present invention.
Fig. 3 illustrates an example of a finished part.
Fig. 4 illustrates a prior art mask projection for laser micro-machining.
Fig. 5 illustrates an example of a mask projection for laser micro-machining according to an embodiment of the present invention.
Fig. 6 illustrates another example of a mask projection for laser micro-machining according to another embodiment of the present invention.
Fig. 7 illustrates still another example of a mask projection for laser micro-machining according to anther embodiment of the present invention.
Fig. 8 illustrates still yet another example of a mask projection for laser micro-machining according to another embodiment of the present invention.
Fig. 9 is a schematic diagram of components to a laser micro-machining system according to another embodiment of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Embodiments of the present invention enable high throughput laser micro-machining while limiting the size of a laser plume. To that end, an exemplary laser micro-machining apparatus which may be used with embodiments of the present invention is shown in Fig. 2. As shown, an illumination source 202 emits a beam of light (laser beam) which is then expanded with a 2-element telescope 204 (for example) and which may be folded down with a 45 degree mirror 206. The light may then brought to focus at a beam shaping aperture 208. The beam shaping aperture maybe used as a mask to create an illumination shape (e.g., square, rectangle, triangle, etc.).
The beam shaper plane may then be imaged to infinity (for example) by a collimator lens 210, which then may impinge the beam onto an array 212 of lens elements. Each lens element may then intercept a portion of the colliniated beam and forms an image of the beam shaper plane at the mask 214. An imaging lens 215 may then be used to image the projection of the mask on the workpiece. Accordingly, the light emitted by the laser may be efficiently segmented into shapes which illuminate the mask. From the mask, the light is then used to ablate material on the workpiece. Applicants' co-pending U.S. patent application no. 10/839,026, herein
incorporated by reference, also discloses a micro-machining system which may be used with embodiments of the present invention.
It is worth noting that the mask pattern may be a planar or cylindrical pattern (i.e., a planar pattern that has been "unwrapped" from a cylinder onto a planar surface), a magnified image of a planar pattern for a planar workpiece, and that a series of masks may be used — each mask representing a portion of a planar pattern for the workpiece and used sequentially (the series of masks may also be magnified images of portions of the planar pattern).
Fig. 3 illustrates the geometry of a planar micro-machined part that will be used in the examples that follow. A projected illumination distribution for a laser micro-machining system is generally the product of the illumination distribution of the laser multiplied by the mask . transmission function. As shown in Fig. 3, the opaque areas (cross-hatched areas) include a transmission of about zero, while the clear area (white area) includes a transmission near unity (for example). The transmitted illumination distribution may be simultaneously projected on the surface of the raw material to perform the machining operation. To make multiple parts, for example, the illuminated field maybe step-and-repeat imaged over the surface of the raw material.
Fig. 4 illustrates the image plane of a prior art mask projection micro-machining system. The mask area is illuminated with a uniform beam of laser illumination (dotted line) along a large field. Typically, the field aspect ratio (width to height) of the beam is generally between 1 : 1 and 2:1. While larger field aspect ratios of the beam are conceivable, one skilled in the art will appreciate that such systems are impractical due to the high cost of constructing a system due to cost and size of the optics involved (e.g., see co-pending application no. 10/839,026).
With regard to the limited aspect ratio of prior art illumination fields, perimeter to area ratios for 1 : 1 and 2:1 aspect ratios, for example correspond to a perimeter to area ratios of 4: 1 and 4.2:1, respectively (e.g., assuming a one (1) centimeter field area). Accordingly, some embodiments of the present invention increase such perimeter to area ratios to minimize the HAZ to an acceptable level, e.g., a level which does not impact material properties. This results in an increased throughput of a laser micro-machining system.
Accordingly, Fig. 5 illustrates one embodiment of the invention where the illuminated field (dotted line) includes a long line shape having an increased aspect ratio. The increased aspect ratio results in a higher ratio of perimeter to area which results in a greater percentage of the plasma plume volume being quenched, thereby limiting HAZ. In Fig. 5, for example, a one (1) centimeter field area may correspond to a 20:1 aspect ratio and a 9.4:1 perimeter to area ratio. The high aspect illumination field may be generated using the system disclosed in Applicants' co-pending U.S. patent application no. 10/839,026.
It is another feature of the long line embodiment illustrated in Fig. 5 that the overall amount of material removed from the workpiece may be reduced due to a stenciling configuration incorporated into the mask design (for example). Specifically, as can be seen in Fig. 4, more material (e.g., additional material at the top and bottom) is removed in the prior art, while only a slug of residual material is produced at the center of the part in the current embodiment (Fig. 5). This also reduces the thermal loading of the un-machined material.
Fig. 6 illustrates yet another embodiment of the invention, hi this embodiment, the illuminated field area is further subdivided into a plurality of long linear fields (i.e., high aspect ratio fields). In this case, the mask may be translated through the array of illuminated fields and/or the workpiece is moved relative to the mask (e.g., in opposite directions) to execute COM
scanning. Some embodiments of the invention allow for the relative translation of the mask and workpiece in opposite directions multiple times. As shown in Fig. 2, actuator(s) 216 (or other moving means; e.g., a linear motor driven support plate, and the like) may move the mask pattern relative to the workpiece (e.g., along a line, in/around a plane and/or rotationally). Moreover, the workpiece may also include an additional actuator(s) 218, which may be used in addition to or in place of the actuator(s) 216 of the mask, to accomplish the relative movement (e.g., along a line, in/around a plane and/or rotationally) between the mask and workpiece.
It is worth noting, that a particular advantage of the present embodiment is that the increased subdivision of the illuminated fields may maintain machining throughput and provides a further enhancement to quench the plasma plume and further diminish HAZ. Moreover, the division of the field area into a plurality of long line fields provides an even more substantial improvement in the perimeter to area ratio. For example, a one (1) square centimeter field can be subdivided into 20 fields, each having a 20:1 aspect ratio. Such an aspect ratio then corresponds to a perimeter to area ratio of 42:1 (for example).
In the case where machined cuts are oriented in a rectilinear manner, the fields of illumination may be made into curved shape and/or oriented at angles other than 0 degrees or 90 degrees. For example, Fig. 7 illustrates a case where the scanning direction is oriented so that it is mis-aligned with the linear cut geometry of the part (e.g., at a 45 degree angle thereto). Exemplary configurations of this embodiment may include:
a) rotation of the illumination field and scan axis with respect to the mask (as shown in Fig. 7);
b) rotation of the mask with respect to the illumination field and scan axis; and
c) rotation of only the illumination field.
Figs. 8 and 9 illustrate yet another embodiment whereby long line illumination fields may be subdivided into still smaller regions (e.g., square) which provide an even greater plasma plume quenching (i.e. a greater ratio of perimeter to area). For example, a full-segmentation COM configuration for this embodiment may resemble a halftone illumination pattern which maybe dithered to scan the illumination regions over the surface of the mask. Accordingly, if a one (1) square centimeter field is segmented into a 20 row by 20 column grid of small square fields of illumination, the perimeter to area ratio increases to 80:1.
Additional Embodiments
Other embodiments of the invention may include a laser micromachining apparatus, such as (for example) a laser micromachining apparatus for copying an image of a planar mask onto a planar or cylindrical workpiece. This may be accomplished by translating the mask and planar workpiece synchronously, or translating the mask and rotating the cylindrical workpiece synchronously. Accordingly, at a given instance, the laser illuminates a selected area on the mask. An imaging system (e.g., lens) may be used to image this selected area on the surface of a planar or cylindrical workpiece.
Still other embodiments of the invention may include a mask pattern which may be a representation of the planar image. The mask may be translated in a linear fashion while the workpiece is translated parallel to the mask motion. By synchronously translating the mask from
one end of the pattern to the other, while translating the planar workpiece relative to the mask, an entire pattern can be imaged from the planar mask to the planar workpiece. The mask and workpiece may be translated in opposite directions since the projection lens inverts the image of the mask.
In still other embodiments of the invention, the mask pattern may be a representation of the unwrapped image of the cylinder, where the mask may be translated in a linear fashion while the cylindrical workpiece is rotated about an axis (e.g., of the cylinder). The cylinder and it rotation mechanism are preferably oriented such that the optical axis of the imaging system is perpendicular to its surface. By synchronously translating the mask from one end of the pattern to the other while simultaneously rotating the cylinder about its axis for a full rotation, the entire pattern can be imaged from the planar mask to the cylindrical surface. The mask may also be translated and the cylinder rotated such that the relative motions are in opposite directions since the projection lens inverts the image of the mask.
The above noted embodiments enable high speed/throughput in a laser micro-machining system which, as indicated above, may be achieved by imaging a long line perpendicular to the direction of translation of a planar workpiece, or parallel to the axis of a cylinder.
However, in some embodiments, it may be necessary to limit the width of the image parallel to the scan direction of the mask because of the depth of focus of the imaging system and the curvature of the cylinder. This may be accomplished through the use of a pre-mask aperture (see Fig. 9), which defines the instantaneous area of the mask pattern to be transmitted. The pre- mask aperture may be used to optimize the image width in relation to the depth of focus of the imaging system and the curvature of the cylinder. The pre-mask aperture may also be used to optimize the laser energy delivered locally per unit area per unit time, allowing greater control of
ablation rates, and allowing thermally sensitive material to be processed at higher laser pulse repetition frequencies without altering the material.
Having now described a number of embodiments of the present invention, it is apparent to those skilled in the art that the present disclosure is not limited to those embodiments, and that the above embodiments may be used in combination. Moreover, numerous other embodiments and modifications of the disclosed embodiment are contemplated as following within the scope of the present invention and the following claims.
Claims
1. A method laser micro-machining comprising:
dividing a long line illumination field into a plurality of individual fields, wherein each of the plurality of fields includes a aspect ratio of about 4:1 or greater;
directing the plurality of individual fields onto at least one mask, wherein each individual field illuminates a corresponding area on the mask; and
translating the mask and/or workpiece relative to one another along a scan axis.
2. The method according to claim 1 , wherein at least one of the individual fields comprises a linear or curved shape.
3. The method according to claim 1, wherein at least one of the individual fields is orientated at an angle to at least one of the mask, the workpiece and the scan axis.
4. The method according to claim 3, wherein the angle is between 0 and 90 degrees.
5. The method according to claim 1, wherein at least one of the plurality of individual fields is subdivided into a plurality of sub-fields.
6. The method according to claim 1, wherein the workpiece comprises a cylindrical shape and wherein the mask is a representation of an unwrapped image of the shape.
7. The method according to claim 1 , further comprising limiting a width of one or more fields parallel to the scan direction of the mask.
8. The method according to claim 1, wherein the mask is an image of a planar pattern.
9. The method according to claim 1 , wherein the mask pattern comprises a magnified image of a planer pattern.
10. The method according to claim 1, wherein the mask and the workpiece are translated in opposite directions.
11. The method according to claim 10, wherein translation occurs multiple times.
12. The method according to claim 1 , wherein the mask projects an image on the workpiece via an imaging lens.
13. The method according to claim 1 , wherein a plurality of masks are used.
14. The method according to claim 13, wherein each mask and an associated portion of the workpiece are utilized sequentially and translated in opposite directions multiple times.
15. A system for laser micro-machining comprising:
an optical source comprising a laser beam;
dividing means for dividing a long line illumination field into a plurality of individual fields, wherein each of the plurality of fields includes an aspect ratio of about 4:1 or greater;
directing means for directing the plurality of individual fields onto at least one mask, wherein each individual field illuminates a corresponding area on the mask; and
translating means for translating the mask and/or workpiece relative to one another along a scan axis.
16. The system according to claim 15, wherein at least one of the individual fields comprises a linear or curved shape.
17. The system according to claim 15, wherein at least one of the individual fields is orientated at an angle to at least one of the mask, the workpiece and the scan axis.
18. The system according to claim 17, wherein the angle is between 0 and 90 degrees.
19. The system according to claim 15, wherein at least one of the plurality of individual fields is subdivided into a plurality of sub-fields.
20. The system according to claim 15, further comprising a pre-mask aperture.
21. The system according to claim 20, wherein the pre-mask aperture is used to optimize the field width relative to a depth of focus.
22. The system according to claim 20, wherein the pre-mask aperture is used to control and/or optimize the laser energy delivered locally per unit area per unit time.
23. The system according to claim 15, wherein the laser beam is from an excimer laser.
24. The system according to claim 15, wherein the beam is homogenized.
25. The system according to claim 15, wherein the workpiece is cylindrical and positioned such that the laser beam is normally incident to the cylindrical surface.
26. The system according to claim 15, wherein the beam comprises a high aspect ratio rectangular shape having a short axis perpendicular to a direction of translation of the workpiece.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP06771397A EP1924390A1 (en) | 2005-05-27 | 2006-05-26 | Apparatus for minimizing a heat affected zone during laser micro-machining |
Applications Claiming Priority (2)
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US11/140,341 | 2005-05-27 | ||
US11/140,341 US8278590B2 (en) | 2005-05-27 | 2005-05-27 | Apparatus for minimizing a heat affected zone during laser micro-machining |
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WO2006128054A1 true WO2006128054A1 (en) | 2006-11-30 |
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PCT/US2006/020606 WO2006128054A1 (en) | 2005-05-27 | 2006-05-26 | Apparatus for minimizing a heat affected zone during laser micro-machining |
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EP (1) | EP1924390A1 (en) |
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WO2007062130A1 (en) * | 2005-11-22 | 2007-05-31 | J.P. Sercel Associates Inc. | System and method for laser machining of three-dimensional structures |
US8344286B2 (en) * | 2007-01-18 | 2013-01-01 | International Business Machines Corporation | Enhanced quality of laser ablation by controlling laser repetition rate |
JP2010089094A (en) * | 2008-10-03 | 2010-04-22 | Disco Abrasive Syst Ltd | Laser beam machining apparatus |
US9669613B2 (en) | 2010-12-07 | 2017-06-06 | Ipg Photonics Corporation | Laser lift off systems and methods that overlap irradiation zones to provide multiple pulses of laser irradiation per location at an interface between layers to be separated |
WO2011071889A1 (en) * | 2009-12-07 | 2011-06-16 | J.P. Sercel Associates, Inc. | Laser lift off systems and methods |
WO2011158617A1 (en) * | 2010-06-14 | 2011-12-22 | 三菱電機株式会社 | Laser processing device and laser processing method |
US8461481B2 (en) * | 2011-04-19 | 2013-06-11 | Primestar Solar, Inc. | Methods and apparatus for reducing variations in the laser intensity during scribing a photovoltaic device |
EP2564974B1 (en) * | 2011-09-05 | 2015-06-17 | ALLTEC Angewandte Laserlicht Technologie Gesellschaft mit beschränkter Haftung | Marking apparatus with a plurality of gas lasers with resonator tubes and individually adjustable deflection means |
EP2564972B1 (en) * | 2011-09-05 | 2015-08-26 | ALLTEC Angewandte Laserlicht Technologie Gesellschaft mit beschränkter Haftung | Marking apparatus with a plurality of lasers, deflection means and telescopic means for each laser beam |
DK2564975T3 (en) * | 2011-09-05 | 2015-01-12 | Alltec Angewandte Laserlicht Technologie Ges Mit Beschränkter Haftung | Selection apparatus with a plurality of lasers and sets of deflecting agents that can be individually adjusted |
ES2544034T3 (en) | 2011-09-05 | 2015-08-27 | ALLTEC Angewandte Laserlicht Technologie Gesellschaft mit beschränkter Haftung | Marking apparatus with at least one gas laser and one thermodisipator |
DK2565673T3 (en) | 2011-09-05 | 2014-01-06 | Alltec Angewandte Laserlicht Technologie Gmbh | Device and method for marking an object by means of a laser beam |
ES2452529T3 (en) | 2011-09-05 | 2014-04-01 | ALLTEC Angewandte Laserlicht Technologie Gesellschaft mit beschränkter Haftung | Laser device and procedure for marking an object |
ES2530069T3 (en) * | 2011-09-05 | 2015-02-26 | ALLTEC Angewandte Laserlicht Technologie Gesellschaft mit beschränkter Haftung | Marking apparatus with a plurality of lasers and a combination deflection device |
EP2565996B1 (en) | 2011-09-05 | 2013-12-11 | ALLTEC Angewandte Laserlicht Technologie Gesellschaft mit beschränkter Haftung | Laser device with a laser unit, and a fluid container for a cooling means of said laser unit |
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Also Published As
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EP1924390A1 (en) | 2008-05-28 |
US8278590B2 (en) | 2012-10-02 |
US20060266742A1 (en) | 2006-11-30 |
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