Apparatus and method for pattern ablation in glass

Abstract

The present invention concerns a glass ablation apparatus comprising a support for supporting a glass panel comprising - a glass surface, - an laser source, - an optical head comprising one or more processing heads, each processing head configured for directing and focussing light from the laser source along a beam path to an ablation zone, whereby each processing head comprises a focussing component configured to controllably vary a focal zone position along the beam path, and one or more light deflector components for directing light according to a predefined beam trajectory, and a glass surface localisation system, and - a controller configured for receiving glass surface localisation information from the glass surface localisation system, computing a distance between the focussing component of at least one processing head and the glass surface on the basis of said glass surface localisation information, thereby defining a target focal zone of light focused by the focussing component, and providing a focussing signal to the focussing component, whereby said focussing component is configured to adapt the focal zone position on the basis of the focussing signal, such that the target focal zone essentially coincides with an ablation zone of the glass surface for ablating a pattern onto the glass panel.

Description

[0001] APPARATUS AND METHOD FOR PATTERN ABLATION IN GLASS

[0002] Technical field

[0003] The present invention pertains to the field of laser ablation of glass, more in particular to the formation of a pattern on a glass surface by laser ablation. One important application of the invention is its use in providing patterns on window glass panels for obtaining bird friendly windows.

[0004] Background

[0005] With the increasing use of glass in building shells, the number of bird strikes increases dramatically worldwide. Birds do not recognize the glass obstacles which appear to them as transparent and suffer serious injuries when flying against the glass facades.

[0006] US patent 9,974,298 B2 relates to a method for producing a bird protection device and to a bird protection device. According to the invention, a method for producing a bird protection device is proposed, wherein the bird protection device is made of an at least partially transparent material and contains an optical structure visible to a bird's eye. Here, the method comprises a radiation input, wherein the radiation input is implemented on and / or in the partially transparent material for forming the optical structure. The radiation input is preferably laser radiation. Suitable lasers for the radiation input are, for example, CO2 lasers with a wavelength of 1064 nm, picosecond lasers with a wavelength of 532 nm or nanosecond lasers with a wavelength of 532 nm. In one embodiment of the invention, the bird protection device furthermore comprises an element for increasing the contrast, wherein, for forming the optical structure, the radiation input is implemented on and / or in the element for increasing the contrast. The document discloses a method for producing a bird protection device, comprising the steps of: forming the bird protection device of an at least partially transparent material, and providing an optical structure visible for a bird's eye, with a source of radiation, wherein the radiation is applied for forming the optical structure on the partially transparent material. Herein,

[0007] 1) the optical structure of the partially transparent material is formed by locally printing with a laser transfer method. In this case, carriers containing metal and / or color-pigments are brought into contact with the surface of the glass and metal atoms and / or color pigments are transferred from the carrier to the glass surface and fixed by way of laser irradiation. Such a method requires additional material suitable to be diffused into the glass;

[0008] 2) layers forming the optical structure having increased absorptivity and / or reflectivity with respect to the partially transparent material are arranged on a surface of the partially transparent material, wherein the optical structure is formed through laser-assisted, partial removal of the layers. Also hereby additional material for the layers are required;

[0009] 3) for forming the optical structure the radiation is applied on and / or in an element for contrast enhancement, wherein the optical structure on a surface and / or in an interior of the element for contrast enhancement is formed by laser-assisted, local change of optical properties of the element for contrast enhancement. Again, an additional element is required, this time for contrast enhancement; or 4) for forming optical structure the radiation is applied on and / or in an element for contrast enhancement, wherein the optical structure on a surface and / or in an interior of the element for contrast enhancement is formed by laser-assisted, local formation of microcracks and / or by formation of regions of changed material density. Also here, an additional element is required for contrast enhancement.

[0010] US patent 9,974,298 B2 also discloses different types of laser-induced structures in or on the glass which show an effect on the flight behavior of birds in the flight tunnel: scattering microcracks or absorbing color centers inside the glass, absorbing and / or reflecting structures on and / or slightly below the glass surface, absorbing and / or reflecting structures on a coated glass surface, and structures on / in the element for enhancing contrast.

[0011] However, the inventors of the present invention have found that this and other prior art documents fail to disclose a manner which allows forming an optical structure in a controlled manner on the surface of a glass panel without the need for an additional material. Furthermore, the inventors have found that the methods disclosed in the prior art include a very high risk of initiating shattering on tempered glass, making the method non applicable in that case.

[0012] Tempered glass, also called toughened glass, is a type of safety glass processed by controlled thermal or chemical treatments to increase its strength compared with normal glass. Tempering puts the outer surfaces into compression and the interior into tension. Such stresses cause the glass, when broken, to shatter into small granular chunks instead of splintering into jagged shards as ordinary annealed glass does. The granular chunks are less likely to cause injury. Tempered glass is used for its safety and strength in a variety of applications, including passenger vehicle windows (apart from windshield), shower doors, aquariums, architectural glass doors and tables, refrigerator trays, mobile phone screen protectors, bulletproof glass components, diving masks, and plates and cookware. Tempered glass is also used in buildings for unframed assemblies (such as frameless glass doors), structurally loaded applications, and any other application that would become dangerous in the event of human or animal impact, including bird impact. However, the same thing that makes tempered glass useful as safety glass prohibits the use of the laser-assisted methods disclosed in the prior art to provide optical structures on or in the tempered glass: it would seem that in prior art methods, the laser heats the glass to such a degree that the tensions and compressions become too large for glass such that it shatters.

[0013] The present invention aims to provide an optical pattern on the surface of a glass panel without requiring additional material, and in such a controlled manner that any type of pattern can be accurately formed on the surface, and this without breaking the glass, even if tempered glass is used.

[0014] Summary of the invention

[0015] The present invention concerns a glass ablation apparatus according to claim 1 and a glass ablation method according to claim 13. Further embodiments are disclosed in the dependent claims and further in this document. Note that the apparatus and method can be used to provide any type of pattern onto a glass panel, not only an optical pattern. However, in many applications the pattern is provided on the glass panel for optical reasons, Hence the pattern preferably is an optical pattern.

[0016] The present invention is based on the insight of the inventors that large glass panels and / or the glass surface thereof, even if deemed flat, may curve, and that it is important to compensate for such curvature when trying to ablate portions of the glass surface in a controlled manner by means of laser light. If the ablation occurs too deep within the glass, this may cause shattering of the glass panel. This is particularly important in the case of tempered glass, where it is important that the laser light is out of focus at a depth where the interior part under tension is located. Indeed, typical glass panel thicknesses are between 3 mm and 12 mm. For tempered glass, an outer surface which is under compression typically lies within about 20% of the panel thickness from the surface. In absolute numbers this means that the compressed region of tempered glass comprises a thickness of typically between 0.6 mm and 2.4 mm. This means that laser source light which is intended to ablate patterns onto the glass surface basically needs to be out of focus in the interior region of the tempered glass. This in turn requires that the position of the glass surface is measured accurately enough to allow focussing of the laser light to within the compressed region while still ensuring that the power delivered to the ablation zone on the glass surface is large enough to ablate the glass surface.

[0017] Furthermore, even if non-tempered glass is to be treated, the present invention allows to ablate patterns on the glass surface of glass panels with better accuracy and better efficiency, and much better control to the end result with respect to e.g. the optical properties of the pattern ablated onto the glass surface. Also, the present invention allows pattern ablation without any additional material to be provided onto or into the glass panel, and allows treatment of many types of glass panels, including multiple-glazed units, such as double- and triple-glazed units. Note that within the present invention, the terms “ablate” and “ablation” refer to a process whereby material is removed from the substrate, i.c. a glass panel. After ablating a few tens of microns of the glass surface, the remaining materials roughness is increased and the optical structure is generated due to the increased light diffusion within the processed area. However, secondary processes may also occur, such as melting and self-reorganisation of the glass panel surface, which may also have an effect on the resulting optical structure. The present invention allows to take into account such secondary processes due to the high accuracy and controllability of the ablation process offered by the present invention.

[0018] Overview of the figures

[0019] Fig. 1 shows a schematic overview of an apparatus according to the invention.

[0020] Figs. 2 and 3 illustrate an apparatus (100) according to the present invention.

[0021] The apparatus and method of the present invention is schematically further illustrated in fig. 4.

[0022] Detailed discussion of the invention

[0023] The present invention concerns a glass ablation apparatus in accordance with claim 1 . The apparatus comprises a support for supporting a glass panel comprising a glass surface. Preferably, the glass panel can be moved with respect to the optical head in order to allow ablation of a pattern on the glass panel surface, preferably in a stepwise manner. Hence, in an embodiment, the support comprises a support actuator and the support is configured for moving a glass panel. Preferably the support is configured for moving the glass panel in a first direction, also called machine direction, said first direction essentially parallel to the glass surface of the glass panel if said glass panel is placed on the support. In certain embodiments, the support is further configured for moving the glass panel in a second direction, also called cross direction, said second direction essentially parallel to the glass surface and perpendicular to the first direction. Hence, the support can be configured for moving the glass panel in a planar movement by combining movements along the first direction and the second direction.

[0024] The apparatus comprises an laser source, preferably a pulsed laser source. The laser source is configured to ensure ablation of a glass surface. The apparatus comprises one or more laser sources. In embodiments, the apparatus comprises more than 1 laser source, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16 or more laser sources. In some preferred embodiments, the apparatus comprises M laser sources, whereby M is equal to the number N of processing heads or M is a divisor of N such that each of the M laser sources can be configured to provide laser light to N / M processing heads.

[0025] The laser source preferably is a high throughput, short pulse laser source. Preferred values on pulse duration, pulse frequency, energy per pulse and optical power or optical power per processing head are given below.

[0026] In a preferred embodiment, the laser source is a pulsed laser source configured to deliver pulse with a pulse duration of between 0.1 ps and 10.0 ps, such as 0.1 ps, 0.2 ps, 0.3 ps, 0.4 ps; 0.5 ps, 0.6 ps, 0.7 ps, 0.8 ps, 0.9 ps, 1 .0 ps, 1 .5 ps, 2.0 ps, 2.5 ps, 3.0 ps, 3.5 ps, 4.0 ps, 4.5 ps, 5.0 ps, 5.5 ps, 6.0 ps, 6.5 ps, 7.0 ps, 7.5 ps, 8.0 ps, 8.5 ps, 9.0 ps, 9.5 ps 10.0 ps or any value therebetween, most preferably a pulse duration of 2.0 ps or less.

[0027] In a preferred embodiment, the laser source is a pulsed laser source configured to deliver pulses at a pulse frequency of 10 kHz and 20 MHz, such as 10 kHz, 20 kHz, 30 kHz, 40 kHz, 50 kHz, 60 kHz, 70 kHz, 80 kHz, 90 kHz, 100 kHz, 150 kHz, 200 kHz, 250 kHz, 300 kHz, 400 kHz, 500 kHz, 600 kHz, 700 kHz, 800 kHz, 900 kHz, 1 .0 MHz, 1.1 MHz, 1 .2 MHz, 1 .3 MHz, 1 .4 MHz, 1 .5 MHz, 1 .6 MHz, 1 .7 MHz, 1.8 MHz, 1.9 MHz, 2.0 MHz, 2.2 MHz, 2.4 MHz, 2.6 MHz, 2.8 MHz, 3.0 MHz, 3.5 MHz, 4.0 MHz, 4.5 MHz, 5.0 MHz, 6.0 MHz, 7.0 MHz, 8.0 MHz, 9.0 MHz, 10 MHz, 11 MHz, 12 MHz, 13 MHz, 14 MHz, 15 MHz, 16 MHz, 17 MHz, 18 MHz, 19 MHz, 20 MHz or any value therebetween, most preferably about 1 MHz.

[0028] In a preferred embodiment, the laser source is a pulsed laser source configured to deliver an energy per pulse of at least 1 microJoule, such as 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15 microJoule or any value therebetween or above, preferably at least 15 microJoule.

[0029] In a preferred embodiment, the laser source is configured to radiate laser light at a laser wavelength between 200 nm and 11000 nm, such as 200 nm, 300, nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1200 nm, 1400 nm, 1600 nm, 1800 nm, 2000 nm, 2500 nm, 3000 nm, 3500 nm, 4000 nm, 4500 nm, 5000 nm, 6000 nm, 7000 nm, 8000 nm, 9000 nm, 10000 nm or any value therebetween, more preferably between 900 nm and 1200 nm, such as 900 nm, 930 nm, 960 nm, 990 nm, 1000 nm, 1030 nm, 1060 nm, 1090 nm, 1100 nm, 1130 nm, 1160 nm, 1190 nm, 1200 nm or any value therebetween, most preferably about 1030 nm.

[0030] In an embodiment, the laser source is operated or is configured to operate at a laser optical power of at least 1 W, such as 1 W, 2W, 3W, 4W, 5W, 6W, 7W, 8W, 9W, 10W or any value therebetween or above, preferably at least 10W, such as 10W, 20W, 30W, 40W, 50W, 60W or any value there between or above, such as 70W, 80W, 90W, 100W, 120W, 140W, 160W, 180W, 200W or any value there between or above. In a preferred embodiment, the optical head of the apparatus comprises N processing heads, each of the N processing heads configured for directing and focussing light from the laser to a respective ablation zone. Hereby, N is at least 1 , and preferably is more than 1 , such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12 or more, more preferably 4 or 6. Preferably hereby, the laser source is operated or is configured to operate at a laser optical power of at least 10W per processing head, such as 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23,1 24, 25, 26, 27, 28, 29, 30 Watt per processing head or any value there between or above, most preferably about 16 W per processing head or about 24 W per processing head.

[0031] In a preferred embodiment, the pulse duration, pulse frequency, energy per pulse and / or optical power are selected such that an ablation zone is ablated within an predefined ablation period, which preferably is at most 30s, more preferably at most 20s, still more preferably at most 10s, such as 10s, 9s, 8s, 7s, 6s, 5s, 4s, 3s, 2s, 1s or any value therebetween or below.

[0032] The apparatus further comprises at least one optical head. Optionally, the apparatus may comprise 2, 3, 4, 5 or more optical heads, preferably said optical heads being essentially identical. Preferably the optical head can be moved with respect to the support in order to allow ablation of a pattern on the glass panel surface, preferably in a stepwise manner. Hence, in an embodiment, the optical head comprises an optical head actuator and the optical head is configured for moving with respect to the support. Preferably the optical head is configured for moving in the cross direction, said cross direction essentially parallel to the glass surface of the glass panel if said glass panel is placed on the support. In certain embodiments, the optical head is further configured for moving in a machine direction, said machine direction essentially parallel to the glass surface and perpendicular to the cross direction. Hence, the optical can be configured for moving in a planar movement by combining movements along the cross direction and the machine direction.

[0033] In a particularly preferred embodiment, the support comprises a support actuator and the support is configured for moving a glass panel in a machine direction essentially parallel to the glass surface of the glass panel if said glass panel is placed on the support, and the optical head comprises an optical head actuator and the optical head is configured for moving with respect to the support in the cross direction, said cross direction essentially parallel to the glass surface of the glass panel if said glass panel is placed on the support and perpendicularto the machine direction. As such a two dimensional pattern can be ablated onto the glass surface. In a preferred embodiment, the optical head and / or the support are configured for moving in a stepwise manner, whereby preferably the optical head and / or the support are configured for moving during a repositioning period during which the laser source is configured not to provide laser source light, and whereby the optical head and / or the support are configured to remain static during an ablation period during which the laser source is configured to provide laser source light. Such embodiment allows to provide an optical structure with discrete optical units onto the glass surface.

[0034] Each optical head comprises one or more processing heads, each processing head configured for directing and focussing light from the laser source along a beam path to an ablation zone. As indicated above, in a preferred embodiment, the optical head comprises N processing heads, each of the N processing heads configured for directing and focussing light from the laser source to a respective ablation zone. Preferably each optical head comprises N processing heads. Hereby, N is at least 1 , and preferably is more than 1 , such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12 or more, more preferably 4 or 6. The presence of multiple processing heads allows to split the light from a laser source into multiple beams, thereby allowing to ablate multiple ablation zones using the same laser source. As such, a high quality laser can be used to ablate multiple ablation zones in parallel, thereby limiting the amount of lasers needed to treat large surfaces, which tends to significantly reduce the total cost and / or production time.

[0035] In a preferred embodiment, the N processing heads are essentially aligned along the cross direction.

[0036] In embodiments, the N processing heads are positioned on the optical head in positions which form a unit cell of the pattern which is to be ablated onto the glass surface. A unit cell hereby refers to an elementary pattern which, when repeated in a regular manner along the machine direction and / or along the cross direction, results in the pattern which is to be ablated.

[0037] Each processing head comprises a focussing component configured to controllably vary a focal zone position along the beam path, and a set of one or more programmable light deflectors, hereafter referred to as light deflector components (e.g. two-mirror galvo scanner, or polygon scanner) for directing light according to a predefined beam trajectory. Note that each processing head hereby defines its respective beam trajectory. Hence, the N processing heads result in N beams if the apparatus is in a working condition, each of which beam follows a predefined beam trajectory to a predefined ablation zone.

[0038] The focussing component is configured to controllably vary a focal zone position along the beam path. The focal zone position hereby refers to the position along the beam path at which the laser light is focussed to such a degree that ablation of glass is possible. The controlled varying of the focal zone position can be achieved in different manners. In an embodiment, the focussing component preferably comprises a focussing lens attached to a linear displacement motor, and the linear displacement motor is configured to alter the position of the focussing lens on the basis of the focussing signal, thereby controllably altering the focal zone position. An exemplary embodiment of such a focussing component is disclosed in European patent application EP 2437382 A1 . Hence, in a preferred embodiment, the focussing component comprises an electromagnetic motor for controlled linear displacement of an optical element along an axis of movement (A-A) comprising: an armature provided with a mounting for the optical element, and a stator provided with a seat in which the armature lies, which seat is configured for linear movement of the armature along the axis (A-A1), wherein the armature further comprises a hollow inductive coil through which hollow the mounting for the optical element is disposed, the stator is provided with one or more permanent magnets polarized radially with respect to the axis (A-A1), and the motor is configured for linear displacement of the armature relative to the stator responsive to an electrical signal provided to the coil.

[0039] Alternatively, or additionally, the focussing component comprises a separation actuator configured for controllably varying a separation distance along the beam path between the processing head and the glass panel. As such the focal zone position can be controllably varied with respect to the glass panel surface.

[0040] Preferably, the set of one or more light deflector components comprises a light deflector component capable of rotating and / or shifting an optical element with respect to an optical beam axis. An exemplary embodiment of such a light deflector component is disclosed in European patent application EP 3158381 A1. Hence, in a preferred embodiment, the light deflector component comprises: a positionable part to which the optical element can be mounted; a base part; a suspension system, said positionable part being mounted on said base part in a movable manner with said suspension system; and an actuation system for actuating movement of said positionable part with respect to said base part, a control system for controlling movement of said positionable part, wherein said control system comprises a sensing system for measuring the position of the positionable part, said sensing system comprising a high-frequency electrical signal generator which is arranged to make a high-frequency current component flow through an electrical conductor, preferably an electrical coil, on said positionable part, said electrical conductor preferably being an electrical conductor of an actuation element, and said sensing element comprising an induction-based proximity or distance sensor, preferably located on the base part, more preferably longitudinally near or next to said conductors on the positionable part.

[0041] In embodiments, the predefined beam trajectory of a processing head is predefined taking into account the shape, the size and / or the ablation intensity of the ablation zone. The programmable light deflection system, can mark any possible shape consisting of single line trajectory, parallel lines or spirals. For instance, the ablation zone may essentially have the form of a circle with radius r, which can for instance be about 2.5 mm. In such case, the predefined beam trajectory may preferably be configured such that the beam spot describes a spiral on the glass surface starting from the center of the circle and spiralling outwards to a particular radius r or from a radius r of the circle and spiralling inwards to the center, thereby ablating a circle onto the glass surface. The ablation intensity can be controlled independently of the marking shape and beam trajectory by controlling the distance between two adjacent lines or the incremental step between spiral lines, and the speed at which the beam spot moves. In embodiments, the ablation zone may essentially have the form of any or any combination of the following: one or more circles, ellipses, triangles, rectangles and / or squares, one or more spirals, lines, straight lines and / or curved lines, one or more grids and / or hatchings, one or more meander patterns. it is one of the main advantages of the present invention that ablation zones of any form, shape or size can be ablated on the glass surface because of the accuracy and controllability offered by the present invention. Hereby, the size of the ablation zone is basically determined only by the processing field of the lens or lenses used in the processing heads, which may preferably be 30mm x 30mm or 100mm x 100mm.

[0042] The focussing component is configured to adapt the focal zone position on the basis of a focussing signal, such that the target focal zone essentially coincides with an ablation zone of the glass surface for ablating a pattern onto the glass panel.

[0043] Note that in an embodiment, the focussing component and one or more light deflector components may be integrated in a single component.

[0044] Optionally, and in particular in the case multiple processing heads are comprised in the apparatus, the set of light deflector components of a processing head, and preferably of each processing head, comprises a beam divider, preferably comprising a polarization direction control element, such as a half wave plate, coupled with a polarizing beam splitter. The beam divider is employed for splitting a predetermined fraction of the light from the laser source and for redirecting said fraction along the predefined beam trajectory. The particularly preferred couple of polarization direction control element and polarizing beam splitter permits the accurate and controlled beam splitting to multiple processing heads from the same main laser beam. Since the predetermined fraction may vary between processing heads, i.e. the value of this fraction may be different for different beam dividers belonging to different processing heads positioned in sequence. Such sequential splitting is impossible to be achieved using fixed ratio beam splitters. Furthermore, the predefined fraction may depend on the position of the processing head relative to other processing heads along the laser beam. In the case of 1 processing head, preferably the predetermined fraction of the beam divider of the single processing head is about 100%. In the case of 2 processing heads, the fraction of the first beam divider of the first processing head with respect to the light beam coming from the laser source, is about 50%, meaning that about 50% of the light from the laser source is deflected to follow the beam trajectory defined by the first processing head. The other 50% of the light from the laser source is undeflected by the first beam divider and is preferably deflected with a predetermined fraction of about 100% by the second beam divider of the second processing head. In the case of N processing heads, the predetermined fraction (f) of the i’th beam divider of the i’th processing head comprises a value of preferably according to Formula (F1) below: f = 1 / ( N - i + 1) (F1) where i is at least 1 and at most N. This basically ensures that the light of the laser source is split equally over N processing heads and N respective beam trajectories.

[0045] The optical head further comprises a glass surface localisation system. The glass surface localisation system is configured to localize the glass surface of a glass panel on the support at least with respect to the optical head. In embodiments of the invention, the glass surface localisation system comprises a triangulation localisation system, a confocal localisation system, an optical localisation system, an acoustic localisation system or any combination thereof.

[0046] Preferably, the glass surface localisation system hereto comprises one or more, and preferably at least two, optical sensors configured, and one or more, and preferably at least two, measurement light sources, whereby each measurement light source is configured to project a light beam towards a glass panel placed on the support and whereby each optical sensor is configured to detect reflected light from a measurement light source, said reflected light being reflected from a glass panel on the support. As such, a distance between optical head and the glass surface can be obtained, e.g. using a time-of-flight technique.

[0047] Preferably each measurement light sensor is positioned near a processing head and / or essentially between two processing heads. This allows accurate measurement of the distance at or near the position of the processing head.

[0048] Preferably at least two optical sensors and at least two measurement light sources are used, which are positioned separated on the optical head, and each of the sensors and / or measurement light sources being located near to a processing head and / or in between processing heads. This allows to obtain the distance between each of N aligned processing heads, even in the case the glass panel is tilted and / or if the distance between glass panel and the optical head varies essentially linearly along an alignment direction of the N processing heads. In case of slightly a curved glass surface, the two pairs of sensors and measurement light sources still allow an improved accuracy of the glass surface localisation information.

[0049] In a preferred embodiment, at least three optical sensors and at least three measurement light sources are used, which are positioned separated on the optical head, and each of the sensors and / or measurement light sources being located near to a processing head and / or in between processing heads. This allows to obtain the distance between each of N non-aligned processing heads, even in the case the glass panel is tilted or to improve accuracy in obtaining the distance between each of N processing heads in the case the glass panel is curved, e.g. by using a fitting curve.

[0050] The apparatus further comprises a controller configured for o receiving glass surface localisation information from the glass surface localisation system, o computing a distance between the focussing component of at least one, and preferably each, processing head and the glass surface on the basis of said glass surface localisation information, thereby defining a target focal zone of light focused by the focussing component, and o providing a focussing signal to the focussing component.

[0051] As indicated before, the focussing component is configured to adapt the focal zone position on the basis of the focussing signal, such that the target focal zone essentially coincides with an ablation zone of the glass surface for ablating a pattern onto the glass panel. Note that the focussing signal refers to a signal comprising information representing the target focal zone.

[0052] The present invention also concerns a glass ablation method, comprising the steps of:

[0053] (a) providing a glass panel comprising a glass surface;

[0054] (b) obtaining glass surface localisation information, thereby localising the glass surface;

[0055] (c) guiding laser source light to an ablation zone of the glass surface by directing the light according to a predefined trajectory and by focussing the light to a target focal zone, whereby the target focal zone essentially coincides with the ablation zone, thereby ablating a pattern onto the glass surface of the glass panel.

[0056] Preferably the glass surface localisation information localizes the glass surface to within 300 pm, preferably to within 200 pm, still more preferably to within 100 pm, such as to within 100 pm, 90 pm, 80 pm, 70 pm, 60 pm, 50 pm, 40 pm, 30 pm, or to within any value therebetween or below, such as 30 pm, 25 pm, 20 pm, 15 pm, 10 pm, or to within any value therebetween or below, very preferably to within 10 pm, 9 pm, 8 pm, 7 pm, 6 pm, 5 pm, 4 pm, 3 pm, 2 pm, 1 pm, or to within any value therebetween or below.

[0057] In many cases, it may be preferred to ablate the optical structure on the glass panel from below. For instance, the glass panel may comprise a coating layer which may not be damaged during the ablation process. In such case, the glass panel may be placed on the support with the coated surface at the top such that the coating layer does not get damaged by movement of the glass panel by and / or over the support, while the ablation can be performed from below, i.e. on the glass surface opposite to the glass surface with the coating layer. Hence, in a preferred embodiment, the support of the apparatus is located such that a glass panel placed on the support is located above the optical head and the optical head is arranged to provide laser source light upwards for ablating the glass panel from below thereby providing the pattern on a bottom surface of the glass panel. Furthermore, preferably the method of the present invention comprises the step of ablating the pattern on a bottom glass surface of the glass panel.

[0058] If the optical head is positioned underneath the glass panel during ablation, dust may settle on the optical components of the optical head. Thus preferably, the apparatus comprises a dust removal system, such as an airflow generating system, configured to remove dust from optical components of the optical head. Such dust removal system may also be present if the optical head is not positioned underneath the glass panel.

[0059] The present invention also relates to a glass panel comprising an optical structure obtained by ablating the optical structure from the glass panel, preferably whereby the glass panel is tempered. This can be obtained by providing a tempered glass panel with an optical structure. As indicated above, the present invention allows providing the optical structure on tempered glass by ablation without shattering the glass due to its accurate distance measurement in an industrial environment.

[0060] Preferably the glass panel is at least 1 m wide and 1 m long. More preferably the glass panel is at least 1 m wide, more preferably at least 1 ,5m wide, still more preferably at least 2.0m wide, still more preferably at least 2.5m wide, yet more preferably at least 2.9m wide, such as 3m wide. Also preferably, the glass panel is at least 1 m long, such as 1 m, 2m, 3m, 4m, 5m, 6m, 7m, 8m, 9m, 10m or any value therebetween or above. Note that the width and length of the glass panel may preferably refer to the dimensions of the glass panel in accordance with the cross direction and the machine direction of the apparatus, i.e. the width and length of the glass panel are preferably defined with respect to the manner in which the glass panel is or has been placed on the support of the apparatus.

[0061] Fig. 1 shows a schematic overview of an apparatus according to the invention.

[0062] Shown in figure 1 are: the “Laser” the beam path (*), which may comprise one more optical components, e.g. a set of one or more mirrors, beam expansion optics etc. six aligned processing heads (A), each comprising: o a half-wave plate (1) and a polarizing beam splitter cube (2) which form a beam divider o a focussing component (3) comprising a variable and steerable focussing distance for focussing the light to a focal zone position, e.g. a focus shifter such as an Elevathor® component from Newson o one or more light deflector components (4), such as a galvo scanner or a Cyclops™ actuator scanner from Newson o an optical component such as an Ftheta lens preferably positioned after the light deflector components. Such an Ftheta lens allows to direct the light according to a beam trajectory whereby the focus of the beam remains within a focal plane, which can be arranged to essentially coincide with the glass panel surface. a glass surface localisation system comprising two pairs (5) of an optical sensor combined with a measurement light source, the pairs being positioned in between the first and second processing heads and in between the fifth and sixth processing heads respectively.

[0063] The two pairs (5), each pair comprising a sensor and light source, allow obtaining the distance between the glass surface and the optical head, thereby also allowing to obtain the distance between the glass surface and each of the processing heads and allowing to compute the required value of the focal zone position of the focussing. Two pairs may be required to define the plane of the glass surface. Based on that measurement the focus shifters (3) are adjusted to compensate the focussing distance accordingly.

[0064] The light beam radiated by the laser can preferably be adjusted in position using mirrors and in size using e.g. a beam expander.

[0065] The beam is split using the half waveplate (1) and a polarizing cube (2) at the beginning of each processing head to define accurately enough the splitting ratio, with a relative accuracy of 5 % or less, preferably less than 0.5 % in power.

[0066] The beam following the beam trajectory of a processing head then enters the focus-shifter optics (3) to adjust the focal zone position.

[0067] The one or more light deflector components, e.g. a Galvo® scanner (4), moves the beam according to a predefined beam trajectory to ablate an ablation zone on the glass surface.

[0068] Figs. 2 and 3 illustrate an apparatus (100) according to the present invention. A glass panel (10) can be positioned onto a support (17), which is configured to move the glass panel (10) along a machine direction (12). Preferably this is done in a stepwise manner. An optical head (14) comprising a laser (13) and a set of 4 processing heads (15A, 15B, 15C, 15D) are movably arranged underneath the support (17) and the glass panel (10) placed thereon. The apparatus comprises an optical head actuator (16) connected to the optical head (14) for moving the optical head (14) along the cross direction (11), preferably also in a step wise manner. The apparatus can be operated as follows: a) first a glass panel is placed on the support b) the support then moves the glass panel to a first panel position along the machine direction c) the optical head is then moved to a first optical head position along the cross direction d) the distance between the glass panel's bottom surface and the optical head is measured, and focussing signals for each processing head are computed based on the measured distance e) the focussing component of each of the processing heads is provided with the respective focussing signal and the focussing component adapts its focal zone position accordingly f) the laser source is turned on, thereby providing laser light to each of the four processing heads, and the light deflector components direct the laser source light according to a predefined beam trajectory, thereby ablating four ablation zones in parallel g) after the ablation in step f, the optical head can be moved to a second optical head position and steps d to f can be repeated h) when the glass panel is provided with the optical structure at the first panel position across its width in the cross direction, the support can move the glass panel to a second panel position and steps c to g can be repeated As such, the complete glass panel can be repeated to provide the glass panel with an optical structure anywhere on the glass surface thereof.

[0069] The apparatus and method of the present invention is schematically further illustrated in fig. 4. Hereby, a glass panel (10) is provided for treatment. Ablative light from a laser is directed to a set of processing heads (15D, 15C), each processing head comprising a half wave plate and a polarizing beam splitter (20) for tapping a portion of the laser light and sending said portion to an ablation zone (30) on the glass surface. The laser light passes through a focussing component (21) and a light deflector system (22), which can deflect the laser light according to a predefined beam trajectory (23), e.g. a spiralling trajectory, which results in an ablation zone having a spiral or disk shape. A first pair of an optical sensor (27) and measurement light source (26) and a second pair of an optical sensor (29) and a measurement light source (28) are positioned on either side of the processing head and are functionally connected to a controller (24) which receives the measurement signals indicative of the position of the glass surface with respect to the optical head and / or the processing heads thereof. Note that the controller can be calibrated relatively easy e.g. using a test surface. The controller (24) then computes a focussing signal and sends (25) the focussing signal to the focussing component (21), thereby ensuring that the focussing component adapts its focal zone position accurately, preferably such that laser source light is provided only to the top portion of the glass panel, said top portion preferably being located within 300 microns, more preferably to within 100 microns of the glass surface.

Claims

CLAIMS1 . A glass ablation apparatus comprising a support for supporting a glass panel comprising a glass surface, a laser source, preferably a pulsed laser source, an optical head comprising o one or more processing heads, each processing head configured for directing and focussing light from the laser source along a beam path to an ablation zone, whereby each processing head comprises■ a focussing component configured to controllably vary a focal zone position along the beam path, and■ one or more light deflector components for directing light according to a predefined beam trajectory, and o a glass surface localisation system, a controller configured for o receiving glass surface localisation information from the glass surface localisation system, o computing a distance between the focussing component of at least one processing head and the glass surface on the basis of said glass surface localisation information, thereby defining a target focal zone of light focused by the focussing component, and o providing a focussing signal to the focussing component, whereby said focussing component is configured to adapt the focal zone position on the basis of the focussing signal, such that the target focal zone essentially coincides with an ablation zone of the glass surface for ablating a pattern onto the glass panel.

2. A glass ablation apparatus according to claim 1 , whereby the focussing component comprises a focussing lens attached to a linear displacement motor.

3. A glass ablation apparatus according to any one of the preceding claims, whereby the support comprises a support actuator and the support is configured for moving a glass panel for moving the glass panel in a machine direction.

4. A glass ablation apparatus according to any one of the preceding claims, whereby the optical head comprises an optical head actuator and the optical head is configured for moving with respect to the support in the cross direction, said cross direction essentially parallel to the glass surface of the glass panel if said glass panel is placed on the support.

5. A glass ablation apparatus according to claims 3 and 4, whereby the support comprises a support actuator and the support is configured for moving a glass panel in a machine direction essentially parallel to the glass surface of the glass panel if said glass panel is placed on the support, and the optical head comprises an optical head actuator and theoptical head is configured for moving with respect to the support in the cross direction, said cross direction essentially parallel to the glass surface of the glass panel if said glass panel is placed on the support and perpendicular to the machine direction.

6. A glass ablation apparatus according to any one of the preceding claims, whereby the laser source is a pulsed laser source configured to deliver pulses with a pulse duration of between 0.1 ps and 10.0 ps, at a pulse frequency of between 10 kHz and 20 MHz, and to radiate laser light at a laser wavelength between 200 nm and 11000 nm.

7. A glass ablation apparatus according to any one of the preceding claims, whereby the optical head of the apparatus comprises N processing heads, each of the N processing heads configured for directing and focussing light from the laser source to a respective ablation zone, whereby, N is more than 1 , preferably N being 4 or 6.

8. A glass ablation apparatus according to claim 7, whereby the laser source is operated or is configured to operate at a laser optical power of at least 10W per processing head, preferably about 16 W per processing head or about 24 W per processing head.

9. A glass ablation apparatus according to any one of the preceding claims, whereby the laser source is a pulsed laser source which is configured to deliver an energy per pulse of at least 1 microJoule, preferably at least 15 microJoule10. A glass ablation apparatus according to any one of the preceding claims, whereby the set of light deflector components of a processing head, and preferably of each processing head, comprises a beam divider for splitting a predetermined fraction of the light from the laser source and for redirecting said fraction along the predefined beam trajectory.11 . A glass ablation apparatus according to any one of the preceding claims, whereby the predefined beam trajectory of a processing head is predefined taking into account the shape, the size and / or the ablation intensity of the ablation zone.

12. A glass ablation apparatus according to any one of the preceding claims, whereby the glass surface localisation system comprises one or more optical sensors and one or more measurement light sources, whereby each measurement light source is configured to project a light beam towards a glass panel placed on the support and whereby each optical sensor is configured to detect reflected light from a measurement light source, said reflected light being reflected from a glass panel on the support.

13. A glass ablation apparatus according to claim 12, whereby the glass surface localisation system comprises at least two optical sensors and at least two measurement light sources, which are positioned separated on the optical head, and each of the sensors and / or measurement light sources being located near to a processing head and / or in betweenprocessing heads for obtaining the distance between each of N aligned processing heads in the case the glass panel is tilted and / or if the distance between glass panel and the optical head varies essentially linearly along an alignment direction of the N processing heads.

14. A glass ablation method, comprising the steps of:(a) providing a glass panel comprising a glass surface;(b) obtaining glass surface localisation information, thereby localising the glass surface;(c) guiding laser source light to an ablation zone of the glass surface by directing the light according to a predefined trajectory and by focussing the light to a focal zone, whereby the focal zone essentially coincides with the ablation zone, thereby ablating a pattern onto the glass surface of the glass panel.

15. A glass ablation method according to claim 14, whereby the glass surface localisation information localizes the glass surface to within 300 pm.

16. Aglass ablation method according to any one ofthe claims 14 or 15, whereby the predefined beam trajectory of a processing head is predefined taking into account the shape, the size and / or the ablation intensity of the ablation zone.

17. A glass ablation method according to any one of the claims 14 to 16, comprising the step of ablating the pattern on a bottom glass surface of the glass panel.

18. A glass panel comprising an optical structure obtained by ablating the optical structure from the glass panel.

19. A glass panel according to claim 18, whereby the glass panel is tempered.

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