WO2022043044A1 - Strahltransformator - Google Patents
Strahltransformator Download PDFInfo
- Publication number
- WO2022043044A1 WO2022043044A1 PCT/EP2021/072210 EP2021072210W WO2022043044A1 WO 2022043044 A1 WO2022043044 A1 WO 2022043044A1 EP 2021072210 W EP2021072210 W EP 2021072210W WO 2022043044 A1 WO2022043044 A1 WO 2022043044A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- cooling
- beam transformer
- transformer according
- front surface
- optical element
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0938—Using specific optical elements
- G02B27/0994—Fibers, light pipes
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0905—Dividing and/or superposing multiple light beams
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/30—Collimators
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/008—Mountings, adjusting means, or light-tight connections, for optical elements with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/18—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors
- G02B7/181—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation
- G02B7/1815—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation with cooling or heating systems
Definitions
- the invention relates to a beam transformer for transforming an input laser beam into a transformed beam with reduced spatial and/or temporal coherence, in particular for use in laser systems for line illumination of an object, in the form of a transparent, plate-shaped, optical element with a front surface and a rear surface , which extend essentially parallel to one another, with an entry surface, with an exit surface and with a plurality of mirrored surfaces for beam deflection.
- Such a beam transformer is known from WO 2018/019374 A1.
- a laser system is described herein for providing a laser line on a work surface for line illumination of an object.
- Exemplary applications of such laser systems include the recrystallization of silicon oxide layers deposited on glass substrates, such as in TFT displays, laser-assisted doping of solar cells, for example, and laser lift-off processes in the manufacture of microelectronic devices.
- the laser line extends in a first direction over a significant length and in a second direction only over a small distance.
- the laser system includes a laser source for providing a laser beam as a basis for an input elongated laser beam that expands along an extension direction, and a homogenizing and focusing unit for homogenizing the elongated laser beam to form a laser line.
- a beam formatter is described herein to transform the input laser beam into a transformed beam for line illumination of an object.
- the beam transformer comprises a transparent, monolithic, plate-shaped, optical element having a front surface and a rear surface which extend substantially parallel to one another. An entrance surface for entering the laser beam is provided on the front surface. An exit surface for the exit of the transformed beam is provided on the rear surface.
- the optical element has a plurality of mirrored surfaces for beam deflection.
- Such a beam transformer is certainly suitable for carrying out the desired transformation.
- practice has shown that the imaging performance is in need of improvement.
- the line width and the desired (usually trapezoidal) beam profile are not maintained precisely enough under all conditions.
- the invention is based on the object of creating an improved beam transformer with which improved imaging performance can be achieved.
- a cooling device is provided at least on the front surface or the rear surface.
- laser radiation is absorbed at each boundary layer and in the glass body of the optical element itself. This leads to uneven heating of the optical element. Since heat conduction in the glass is poor, temperature equalization through heat conduction in the glass body occurs only to a very limited extent. This leads to an uneven imaging behavior. In particular, the line width and the desired beam profile are not maintained precisely enough under all conditions.
- the temperature distribution within the optical element can be largely homogenized. This significantly improves the imaging behavior.
- the cooling device has a heat sink at least on the front surface or the rear surface of the optical element.
- the heat sink consists of a highly thermally conductive material with a thermal conductivity of at least 50 W m -1 K ' 1 , preferably made of copper or aluminum.
- an intermediate layer made of a thermally conductive material is arranged between the front surface and / or the rear surface of the optical element and the surface of the heat sink, which is softer than the material from which the heat sink is made.
- the intermediate layer consists of indium. This has the advantage that damage to the surfaces of the optical element, which are mirrored, can be avoided by differences in the thermal expansion coefficients of the heat sink and the glass body that makes up the optical element.
- Indium has good thermal conductivity, which is lower than that of copper, but because of its low melting point, indium has a very low yield stress even at room temperature or slightly elevated temperatures and is very soft. Therefore, an intermediate layer made of indium protects an underlying reflective layer of the optical element on the one hand and enables good heat transfer to the adjacent heat sink on the other. Overall, the soft intermediate layer, preferably made of indium, prevents damage to the reflective coating of the glass body and at the same time improves the thermal contact with the heat sink.
- the intermediate layer has a thickness of 0.02 to 1 mm, preferably a thickness of about 0.1 mm.
- the heat sink has connections for supplying and removing cooling liquid.
- the heat sink has cooling fins for passive cooling. These can protrude outwards at an angle, for example, as is typically known from component cooling in electronic circuits.
- the layer on the front surface and/or rear surface made of a material with good thermal conductivity acts as a heat sink, which causes heat to be emitted to the environment.
- the cooling device has means for generating a flow of cooling air, heat pipes or Peltier elements. Effective cooling of the surfaces of the optical object can also be ensured with such cooling devices. Nevertheless, cooling by means of a heat sink in conjunction with an additional flow of cooling liquid is a preferred embodiment that is particularly cost-effective and effective.
- FIG. 1 shows a perspective representation of a beam transformer according to the invention
- FIG. 2 is a simplified side view of the optical element of FIG. 1 seen from the front;
- Fig. 3 is a rear view of the optical element
- 4 shows a simplified cross-section through the optical element with heat sinks on the front and rear and a fastening element arranged above it, with the cooling channels within the heat sink not being shown for reasons of simplification;
- 4a shows an alternative embodiment of the beam transformer according to FIG. 4, only the optical element being shown in cross section together with cooling elements in the form of heat pipes or Peltier elements;
- FIG. 4b shows a further modification of the beam transformer, the optical element being shown in connection with a cooling device in the form of a cooling air line which is fed via a fan;
- 4c shows a further modification of a beam transformer, wherein only one heat sink is shown, which is provided with cooling ribs protruding at an angle to the outside for passive cooling;
- FIG. 5a shows the change over time in the measured length of the short axis of the elongated laser beam in micrometers plotted against time in minutes, without cooling;
- FIG. 5b shows a representation according to FIG. 5a, but with cooling both on the front surface and on the rear surface, with active cooling by means of coolant flowing through the heat sink.
- a beam transformer according to the invention is shown in perspective and denoted by the number 10 overall.
- the beam transformer 10 is part of a laser system designed to provide a linear laser beam at a work surface for illuminating an object, as described in detail in WO 2018/019374 A1, which is fully incorporated herein by reference.
- the laser system has a laser source for emitting a laser beam as a basis for an input elongated laser beam along a propagation direction, and a homogenizing and focusing unit for homogenizing and focusing the elongated laser beam to form the laser line.
- a plurality of laser systems can be arranged next to one another in order to jointly form an extended laser line, which consists of a series of laser lines.
- Part of the optical system in such a laser system is a beam transformer for transforming an input laser beam into a transformed beam with reduced spatial and/or temporal coherence.
- this is a transparent, plate-shaped, optical element with a front surface and a rear surface which extend essentially parallel to one another, with an entry surface on the front surface and an exit surface on the rear surface, and having a plurality of mirrored surfaces for beam deflection.
- the structure and mode of operation of such a beam transformer are known.
- the transformation within the beam transformer generally reduces the beam quality in the X-direction (direction in which the longitudinal beam extends) and at the same time improves the beam quality in the Y-direction ("width") of the laser beam, while the Z-direction is the direction of propagation of the laser beam.
- the beam transformer 10 has a housing 12 in which a transparent, plate-shaped, monolithic optical element is accommodated, which is denoted by 14 in its entirety.
- the slab optical element 14 has a front surface and a back surface which extend parallel to each other, with an entrance surface 16 on the front surface and an exit surface on the back surface (not visible in Fig. 1).
- the optical element 14 has an essentially triangular shape, with two orthogonal longitudinal sides 33, 35 which emanate from a common edge 37.
- a substantially rectangular entry surface 16 is formed on the front surface 32 (FIG. 2), while a substantially rectangular exit surface 36 is formed on the rear surface 34 (FIG. 3) perpendicular to the entry surface. surface 16 runs.
- the entry surface 16 and the exit surface 36 intersect in a marginal area adjacent to the common edge 37.
- the entry surface 16 and the exit surface 36 are provided with anti-reflection coatings.
- the front surface 32 and the back surface 34 are coated on the outside with highly reflective coatings. This results in multiple reflections within the optical element 14 for an obliquely incident laser beam that has been expanded in an elliptical shape by the upstream, anamorphic, optical arrangement, before the beam emerges from the exit surface 36 again. Laser beams incident perpendicularly in the overlapping region between the entry surface 16 and the exit surface 36 emerge directly from the exit surface 36 without being reflected.
- a heat sink 18 or 24 (FIG. 1) is provided on both the front surface 32 and the rear surface 34, which extends over the entire front surface 32 or over the entire rear surface 34, with only the entry surface 16 and the exit surface 36 are excluded.
- the heat sinks 18, 24 are made of copper and each has a coolant flowing through it.
- the associated coolant lines 20, 22 of the heat sink 18 can be seen on the front and the coolant lines 26, 28 of the heat sink 24 on the rear surface.
- the heat sinks which are preferably made of copper, have a significantly higher coefficient of thermal expansion, there is a relative movement between the optical element 14 and the heat sinks 18, 24 when the temperature changes. are each provided with a highly reflective layer, they could be damaged by relative movement.
- an intermediate layer 38, 40 is provided between the heat sink 18 on the front surface 32 and between the heat sink 24 on the rear surface 34 (FIG. 4), which consists of a thin indium foil with a thickness of about 0.1 mm . Indium has a melting temperature of 157 °C.
- indium The thermal conductivity of indium is about 81.6 W m -1 K′ 1 , lower than that of copper (398 W′ 1 K′ 1 ), but due to its very low flow stress, indium enables it to be at about 1 MPa at room temperature lies, a good adaptation to the mutual contact surfaces. Indium is very soft, so the indium foil adapts to surface irregularities and creates a good balance with temperature fluctuations.
- the contact area between the heat sinks 18, 24 and the optical element 14 is thus maximized, while at the same time protecting the sensitive reflective coatings on the front surface 32 and on the back surface 34 from damage (note that in the illustration according to FIG of the intermediate layers 38, 40 made of indium is shown clearly exaggerated compared to the thickness of the heat sinks 18, 24 for the purpose of clarity; in addition, for the purpose of simplification, the coolant channels in the heat sinks 18, 24 to which the coolant lines 20, 22 and 26, 28 are connected, not shown).
- An enclosing fastening element 30 in the form of a U-shaped flange is used to fasten the two heat sinks 18, 24, which is screwed to the side of the heat sinks 18, 24 in each case.
- the cooling device can also have other coolants.
- a plurality of heat pipes or Peltier elements could be provided on the front surface 32 and on the rear surface 34, as is shown by way of example in FIG. 4a.
- the beam transformer is denoted overall by 10a.
- the beam transformer is denoted overall by 10b.
- a cooling air line 44 is provided at a certain distance from the front surface 32 and from the rear surface 34 and is supplied with cooling air via a blower 46 . Cooling air exits the cooling air ducts 44 via associated nozzles toward the optical element 14 to cool the front 32 and back 34 surfaces.
- 4c shows a further variant of a beam transformer denoted overall by 10c.
- the heat sink 18 is shown on the front. This is designed as a passive heat sink on which a plurality of cooling ribs 48 protruding at an angle to the outside are provided.
- FIG. 5a, b shows the effect of active cooling of the beam transformer 10 both on the front surface and on the rear surface in comparison.
- the width of the line changes significantly over a period of 1-2 minutes. If the width of the line changes, the power density also varies as the radiation spreads over the smaller or larger area. This is undesirable.
- the uneven heating leads to a (local) deformation of the mirror surfaces on both sides, possibly also to a change in the refractive index.
- the emerging jet changes its shape and height. Since this geometry affects the machining plane is imaged, this also changes the geometry of the line in the processing plane, mainly the line width and also the trapezoidal beam profile.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lasers (AREA)
- Recrystallisation Techniques (AREA)
- Welding Or Cutting Using Electron Beams (AREA)
- Surgical Instruments (AREA)
- Mechanical Light Control Or Optical Switches (AREA)
- Laser Beam Processing (AREA)
- Optical Elements Other Than Lenses (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN202180053010.XA CN115997149A (zh) | 2020-08-27 | 2021-08-10 | 射束变换器 |
JP2023513421A JP2023540231A (ja) | 2020-08-27 | 2021-08-10 | ビーム変換器 |
KR1020237009914A KR20230053688A (ko) | 2020-08-27 | 2021-08-10 | 빔 변환체 |
US18/173,805 US20230194885A1 (en) | 2020-08-27 | 2023-02-24 | Beam transformer |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102020122484.2 | 2020-08-27 | ||
DE102020122484.2A DE102020122484B4 (de) | 2020-08-27 | 2020-08-27 | Strahltransformator |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US18/173,805 Continuation US20230194885A1 (en) | 2020-08-27 | 2023-02-24 | Beam transformer |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2022043044A1 true WO2022043044A1 (de) | 2022-03-03 |
Family
ID=77519105
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP2021/072210 WO2022043044A1 (de) | 2020-08-27 | 2021-08-10 | Strahltransformator |
Country Status (7)
Country | Link |
---|---|
US (1) | US20230194885A1 (de) |
JP (1) | JP2023540231A (de) |
KR (1) | KR20230053688A (de) |
CN (1) | CN115997149A (de) |
DE (1) | DE102020122484B4 (de) |
TW (1) | TWI818300B (de) |
WO (1) | WO2022043044A1 (de) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5553088A (en) * | 1993-07-02 | 1996-09-03 | Deutsche Forschungsanstalt Fuer Luft- Und Raumfahrt E.V. | Laser amplifying system |
US20090168450A1 (en) * | 2007-12-26 | 2009-07-02 | Victor Company Of Japan, Limited | Light source device, lighting device and image display device |
WO2018019374A1 (en) | 2016-07-27 | 2018-02-01 | Trumpf Laser Gmbh | Laser line illumination |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN104950433B (zh) * | 2014-08-15 | 2017-09-05 | 中国水利水电科学研究院 | 激光束片光源系统 |
DE102018115126B4 (de) | 2018-06-22 | 2020-02-13 | Trumpf Laser- Und Systemtechnik Gmbh | Optische Anordnung zur Umwandlung eines Eingangslaserstahls in einen linienartigen Ausgangsstrahl sowie Lasersystem mit einer solchen optischen Anordnung |
TWI680307B (zh) * | 2019-02-25 | 2019-12-21 | 台灣彩光科技股份有限公司 | 白光光源系統 |
-
2020
- 2020-08-27 DE DE102020122484.2A patent/DE102020122484B4/de active Active
-
2021
- 2021-08-10 KR KR1020237009914A patent/KR20230053688A/ko unknown
- 2021-08-10 WO PCT/EP2021/072210 patent/WO2022043044A1/de active Application Filing
- 2021-08-10 CN CN202180053010.XA patent/CN115997149A/zh active Pending
- 2021-08-10 JP JP2023513421A patent/JP2023540231A/ja active Pending
- 2021-08-19 TW TW110130626A patent/TWI818300B/zh active
-
2023
- 2023-02-24 US US18/173,805 patent/US20230194885A1/en active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5553088A (en) * | 1993-07-02 | 1996-09-03 | Deutsche Forschungsanstalt Fuer Luft- Und Raumfahrt E.V. | Laser amplifying system |
US20090168450A1 (en) * | 2007-12-26 | 2009-07-02 | Victor Company Of Japan, Limited | Light source device, lighting device and image display device |
WO2018019374A1 (en) | 2016-07-27 | 2018-02-01 | Trumpf Laser Gmbh | Laser line illumination |
Also Published As
Publication number | Publication date |
---|---|
KR20230053688A (ko) | 2023-04-21 |
US20230194885A1 (en) | 2023-06-22 |
JP2023540231A (ja) | 2023-09-22 |
DE102020122484A1 (de) | 2022-03-03 |
TWI818300B (zh) | 2023-10-11 |
DE102020122484B4 (de) | 2022-03-24 |
CN115997149A (zh) | 2023-04-21 |
TW202208939A (zh) | 2022-03-01 |
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