WO2012007832A1 - Découpeur au laser - Google Patents

Découpeur au laser Download PDF

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Publication number
WO2012007832A1
WO2012007832A1 PCT/IB2011/001640 IB2011001640W WO2012007832A1 WO 2012007832 A1 WO2012007832 A1 WO 2012007832A1 IB 2011001640 W IB2011001640 W IB 2011001640W WO 2012007832 A1 WO2012007832 A1 WO 2012007832A1
Authority
WO
WIPO (PCT)
Prior art keywords
waveform
light
cut
measurements
depth
Prior art date
Application number
PCT/IB2011/001640
Other languages
English (en)
Inventor
Samuel Isaac Ginsberg
Original Assignee
University Of Cape Town
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 University Of Cape Town filed Critical University Of Cape Town
Publication of WO2012007832A1 publication Critical patent/WO2012007832A1/fr

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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
    • B23K26/36—Removing material
    • B23K26/38—Removing material by boring or cutting
    • 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
    • B23K26/03—Observing, e.g. monitoring, the workpiece
    • B23K26/032—Observing, e.g. monitoring, the workpiece using optical means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/22—Measuring arrangements characterised by the use of optical techniques for measuring depth

Definitions

  • This invention relates to a laser cutter, more particularly to a laser cutter capable of determining the depth of a cut, and preferably also controlling the depth of cut.
  • Laser cutting is very widely used. Many materials can be cut cheaply, speedily and very accurately by laser and numerous companies manufacture laser cutters.
  • Laser cutters are generally 2 axis computer controlled machines. By moving the light from the laser over the material in the X-Y plane a cut may be made.
  • Some laser cutters offer rudimentary 3-dimensional control by allowing the laser power, pulse rate and speed of beam travel to be varied by the operator. However, the operator must test each material and decide on the laser settings for each different depth of cut to be made. There is no feedback mechanism, so the laser cutter cannot measure the cut depth in real time and thus accurate control of cut depth is not guaranteed. This is particularly problematic where the material being cut is non-homogenous, such as timber and other natural materials. Laser cutters with this feature are considered "2.5D" machines, implying full X-Y control and partial Z axis control.
  • a laser cutter producing a pulsed light beam characterised in that it includes a first detector for measuring the waveform of light reflected from an object to be cut and a processor configured to compare the measurements of the waveform over a period of time and to determine depth of cut as a function of a difference between the measurements of the waveform.
  • the processor to determine depth of cut as a function of the phase or time difference between the measurements of the waveform, preferably the phase difference; for the processor to further control operation of the pulsed light beam based on a set of user defined cut depths and measured cut depths; and for the processor to control movement of the beam relative to the object.
  • a second detector for measuring the waveform of light directed towards the object and for the processor to compare the measurements of the waveform from the first detector and the second detector over a period of time and to determine depth of cut as a function of the difference between the measurements of the waveform.
  • waveform of light reflected from the surface of the object to first be measured and the phase difference between it and the directed light to be determined, and for the depth of the cut to be determined from subsequent phase differences; and for the measurements to be made during cutting.
  • beam to be reflected onto the object through a partially reflective surface, and for directed and reflected light to be measured through the partially reflective surface.
  • the invention also provides a method of measuring the depth of a cut in an object made by a laser during operation thereof which includes directing a pulsed light beam produced by the laser onto the object, measuring the waveform of light reflected from the object over a period of time, and calculating the depth of the cut in the object as a function of a difference between the measurements of the waveform.
  • a further feature of the invention provides for the depth of the cut in the object to be calculated as a function of the phase or time difference between the measurements of the waveform, preferably the phase difference.
  • the waveform of the light directed towards the object to be measured and to be compared to the waveform of the reflected light and for the depth of the cut in the object to be calculated as a function of the difference between the measurements of the waveform of the directed light and reflected light.
  • Figure 1 is diagrammatic illustration of one embodiment of a laser cutter
  • Figure 2 is a diagrammatic illustration of a second embodiment of a laser cutter
  • Figure 3 is a diagrammatic illustration of a third embodiment of a laser cutter.
  • a laser cutter (1) is shown in Figure 1 and includes a laser (2) which generates a pulsed light beam (4) which is directed through four movable mirrors (6, 7, 8, 9) and a focusing lens (10) onto an object (12) to be cut.
  • the laser cutter thus far described is of conventional configuration.
  • the mirror (9) which directs the light beam (4) directly onto the object (12) is only partially reflective and allows a small amount of light to be transmitted through it.
  • a first sensor (14) is located directly above the point of incidence of the beam (4) on the object (12), on the opposite side of the mirror (9).
  • a second sensor (16) is located in line with the incident, or directed, beam (4) on the mirror (9) on the opposite side to the beam (4).
  • Both the sensors (14, 16) are high speed photodetectors, in this embodiment photodiodes, and are linked to a processor (20).
  • the laser (2) is operated to produce a high frequency, in this embodiment, 100MHz, pulsed beam (4).
  • the beam (4) is directed onto the surface of the object (12) by the mirrors (6, 7, 8, 9). However, part of the beam (4) passes through the mirror (9) and into the second sensor (16). Some of the light from the beam (4) is reflected from the object back towards the mirror (9) and is in turn reflected towards the mirror (8). However, part of the reflected light passes through the mirror (9) and into the first sensor (14).
  • Each of the sensors (14, 16) produces a waveform which has pulses at the same frequency as the laser's pulses. These form inputs to the processor (20) which measures the phase difference between the two waveforms.
  • the processor (20) is configured, in this embodiment through software, to calculate the depth of the cut (22) as a function of the measured phase differences.
  • the following example illustrates part of the calculation performed by the processor (20):
  • Modulation frequency 100x10 6 Hz
  • each additional phase difference of 0.24 degrees indicates an increase in cut depth of 1 mm.
  • higher modulation frequencies will result in better depth resolution.
  • the time taken for the beam to penetrate the surface of the object allows the distance to the surface to be measured and this permits working on objects which do not have flat surfaces.
  • the processor (20) is user programmable and controls the operation of the laser (2).
  • a user can programme into the processor the full 3D shape of an object to be cut and allow the laser cutter to continue automatically.
  • the desired depth of cut can be set without knowing the precise parameters needed to penetrate the material being cut and uniform cut depths can be made in non-homogenous materials. This allows the laser cutter to perform functions reserved for traditional 3D techniques, such as milling, and brings the cost and speed benefits of laser cutting to this area.
  • o emit laser pulses while measuring phase difference; o subtract the phase differences of the senses from the surface reference phase difference measurement.
  • the laser cutter (30) need not make use of mirrors and the laser (32), in this embodiment a laser diode, could direct the beam (34) directly onto the object (36) to be cut through a focusing lens (38).
  • a first sensor (40) is positioned to receive light (42) reflected from the object (36) while a second sensor (44) is positioned to receive light (46) reflected or dispersed from the lens (38).
  • Both sensors (40, 44) are linked to a processor (48) which operates substantially as described above with reference to Figure 1.
  • a laser cutter (50) can even have a single sensor (52).
  • the laser (54) directs the beam (56) directly onto the object (58) to be cut.
  • the sensor (52) is positioned to receive light (60) reflected from the object (58) and is linked to a processor (62) as with the other embodiments described above.
  • the phase of the reflected beam is compared with the phase of the pulsed current used to control the laser. The first measurement is made when the beam reflects off the surface of the object and this measurement is used as the reference for further measurements as cutting progresses.
  • any suitable laser could be used provided that it can be operated to provide a pulsed or modulated output.
  • any suitable signal processing could be used to effect measurements. For example, it is possible to heterodyne the signals of the incident and reflected beams in order to reduce the frequency of the signals being processed whilst preserving the phase information contained in the signals. Importantly, it is not necessary to calculate the depth of the cut in the object as a function of the phase difference between the measurements of the waveform. Any suitable difference can be measured, including a time difference.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Optics & Photonics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

La présente invention se rapporte à un découpeur au laser qui produit un faisceau de lumière pulsée et qui est caractérisé en ce qu'il comprend un premier détecteur servant à mesurer la forme d'onde de la lumière réfléchie par un objet à découper. Un processeur est conçu pour comparer les mesures de la forme d'onde sur une période de temps et pour déterminer la profondeur de coupe en fonction d'une différence entre les mesures de la forme d'onde. La différence de phase est de préférence mesurée. Un second détecteur peut permettre de mesurer la forme d'onde de la lumière dirigée vers l'objet, le processeur étant conçu pour comparer les mesures de la forme d'onde en provenance des premier et second détecteurs sur une période de temps et pour déterminer la profondeur de coupe en fonction de la différence entre les mesures de la forme d'onde.
PCT/IB2011/001640 2010-07-14 2011-07-14 Découpeur au laser WO2012007832A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA2010/04951 2010-07-14
ZA201004951 2010-07-14

Publications (1)

Publication Number Publication Date
WO2012007832A1 true WO2012007832A1 (fr) 2012-01-19

Family

ID=45468992

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2011/001640 WO2012007832A1 (fr) 2010-07-14 2011-07-14 Découpeur au laser

Country Status (1)

Country Link
WO (1) WO2012007832A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2536434A (en) * 2015-03-16 2016-09-21 Sony Corp A cutting device, cutting equipment and method
CN108526719A (zh) * 2018-04-25 2018-09-14 王天牧 一种复合材料的切割设备及切割方法
CN112648932A (zh) * 2020-12-04 2021-04-13 武汉锐科光纤激光技术股份有限公司 激光切割面条纹深度的检测方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57187851A (en) * 1981-05-14 1982-11-18 Nec Corp Secondary ion mass analyzing unit
WO2002038323A1 (fr) * 2000-11-13 2002-05-16 Micmacmo Aps Ablation par laser
WO2006119214A1 (fr) * 2005-04-29 2006-11-09 University Of Florida Research Foundation, Inc. Système et procédé de retour en temps réel de l’ablation de la rate pendant une chirurgie réfractive laser
US20080055588A1 (en) * 2006-09-01 2008-03-06 Disco Corporation Via hole depth detector

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57187851A (en) * 1981-05-14 1982-11-18 Nec Corp Secondary ion mass analyzing unit
WO2002038323A1 (fr) * 2000-11-13 2002-05-16 Micmacmo Aps Ablation par laser
WO2006119214A1 (fr) * 2005-04-29 2006-11-09 University Of Florida Research Foundation, Inc. Système et procédé de retour en temps réel de l’ablation de la rate pendant une chirurgie réfractive laser
US20080055588A1 (en) * 2006-09-01 2008-03-06 Disco Corporation Via hole depth detector

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SABBAH, A.J ET AL.: "Development of a novel femtosecond micromachining workstation using spectral interferometry", CFG1, 2005 CONFERENCE ON LASERS & ELECTRO-OPTICS (CLEO), 22 May 2005 (2005-05-22) - 27 May 2005 (2005-05-27), pages 2166 - 2168, XP010877091 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2536434A (en) * 2015-03-16 2016-09-21 Sony Corp A cutting device, cutting equipment and method
CN108526719A (zh) * 2018-04-25 2018-09-14 王天牧 一种复合材料的切割设备及切割方法
CN112648932A (zh) * 2020-12-04 2021-04-13 武汉锐科光纤激光技术股份有限公司 激光切割面条纹深度的检测方法

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