Decoating apparatus and associated methods and use

Abstract

The present invention discloses a decoating apparatus designed to decoat a portion of a coating system present on a surface of a window, the decoating apparatus comprising a laser device, comprising an optical laser unit to generate a laser beam, and a housing comprising an aperture to let the laser beam going out of the housing The decoating apparatus comprising a displacement means designed to displace and / or orientate the laser device especially the laser beam substantially normal to the surface of the window. The laser device comprises an opaque means opaque to the laser beam and designed to block a majority of back reflections of the laser beam during a decoating step. The decoating apparatus comprises an opening means designed to position the opaque means from an open to a closed position and / or from the closed to the open position. The opaque means is at least partially surrounding the aperture in the closed position. The present invention also relates to decoating methods and use.

Description

Decoating apparatus and associated methods and useDescriptionTechnical Field

[0001] The present intention relates to a decoating apparatus designed to decoat a portion of a coating system present on a surface of a window.

[0002] The present invention further relates to a decoating method to decoat of a coating system present on a surface of a window.

[0003] Thus, the invention concerns multiple domains where windows need to be at least partially decoated, meaning removing part of said coating system, to improve the electromagnetic transparency while ensuring a protection to operators, people and / or animals in the area, but also to any other element around the decoating apparatus.Background Art

[0004] A standard single-layered window has poor thermal performances. This is why most windows are now built using two or more glass panels separated by a gas and / or polymer-based interlayer. This kind of windows is called a multiglazed window.

[0005] A glass panel is low in reflectance for RF radiation. Low in reflectance for RF radiation means that RF radiation is mostly transmitted through the material where high in reflectance for RF radiation means that RF radiation is mostly reflected on the surface of the material and / or absorbed by the material and the attenuation is at level of 20 decibels (dB) or more. Low in reflectance means an attenuation at level of 10 decibels (dB) or less.

[0006] A coating system is typically applied on the interface of one or several glass panels of a multi-glazed window in order to further improve the multiglazed window properties.

[0007] This coating system can either improve the multi-glazed window insulation, reduce the amount of infrared and / or ultraviolet radiation entering the multi-glazed window and / or keep the sun’s heat out of a space wherein such multi-glazed window insulation is used.

[0008] However, this type of coating systems is generally metal-based and therefore acts as a Faraday cage, preventing electromagnetic waves such asradio waves, from entering or leaving the space and then is high in reflectance for RF radiation. The coating system is high in reflectance meaning that the coating system is low in transmittance for RF radiation. Low in transmittance means a transmission with an attenuation at level of 20 decibels (dB) or more. It is understood that the dielectric substrate is low in reflectance, meaning an attenuation at level of 10 decibels (dB) or less.

[0009] Usually, when a window is mounted in situ meaning that the window is mounted on a stationary object, for instance a building, or mounted on a mobile object, for instance a vehicle, a rapid transit system such as a train, tram or alike to close an opening in the stationary or the mobile object, windows are removed from the opening to treat their surfaces.

[0010] A treatment can be a laser scribing or like, or preferably a decoating of a coating system.

[0011] In order to improve the transmittance of a multi-glazed window containing a coating system, one can use a laser decoating system to remove or at least to melt at least one portion of the coating system. The total surface to be decoated is typically between 1 and 3% of the total coating system surface, in order to both improve the transmission of radio waves through the multi-glazed-window without impairing the properties of said coating system.

[0012] Preferably, to improve the transmission of a radio wave through the window, the decoating system will remove segments from the coating system and the sum of the longest sub-segment of each segment is equal to n A / 2 wherein n is a positive integer greater than zero and lambda ( A ) is the wavelength of the radio wave. It is necessary to have a wide band frequency selective surface in order to ensure the transmission of waves of different frequencies through the multi-glazed window, typically between 2GHz and lOOGhz. For instance, the decoating system can be configured to remove a segment of a length greater than 400 mm and a width between 10 and 100 pm.

[0013] Preferably, for some applications such as Wi-Fi, toll communication systems, 4G and / or 5G receptors and transmitters, a small decoating portion is desired instead of a large decoating portion. For instance, a small decoating portion has typically a length less than 400 mm.

[0014] A simple approach to solve this problem of RF energy reflection is to remove a portion of the coating system. This approach, however, reduces thesolar control benefits offered by the multi-glazed window. Moreover, for multiglazed window located inside the building, the vehicle or the car, the decoated region would be unacceptably large. On top of that, the transition between the decoated portion and the coating itself is eye-visible and usually non-accepted by users.

[0015] Another solution has been to cut lines in the coating system to create a surface which is frequency selective: it has relatively high reflectivity / absorbance for solar energy but relatively low reflectivity / absorbance in the RF region of the electromagnetic spectrum. The cutting may be performed by laser ablation and the spacing of the slits is chosen to provide selectivity at the desired frequency.

[0016] To improve the transmittance of said multi-glazed window, WO 2015 / 050762 describes an apparatus comprising a laser light source and a lens array configured to focus said laser light source on a coating system of a multi-glazed window. Said apparatus is mounted on suction pads to secure said apparatus on said multi-glazed window. Said apparatus also comprises at least two motors configured to move said laser along rails along the X and Y axis. Said laser is capable of scribing a grid shape on said coating system to improve the electromagnetic transmission of said multi-glazed window.

[0017] However, said laser is always focused on a single point and cannot be adapted. In fact, this apparatus is only built to have a focal point in a specific surface and thus such apparatus are built for a single type of double-glazed window being two glass panels separated by a spacer creating a space filled with gas, where the coating system is positioned on the internal interface of the window. Hence, it is not possible to use this apparatus to other types of windows where the glass thickness is different or where the coating system is applied on a different interface.

[0018] On top of that, such system needs to move the whole laser device. This movement is complicated, dangerous and implies heavy elements such as motors.

[0019] In another domain, US6,559,411 describes an apparatus for laser scribing a tin oxide layer coated on a glass panel substrate.

[0020] A predetermined scribing is formed on the tin oxide layer by focusing a laser on said tin oxide layer and by displacing said glass panel substrate by aconveyor along the X or Y axis. Moreover, the position of the laser is adjusted in the Z direction during the laser scribing to maintain the focusing on said tin oxide layer.

[0021] However, this focusing requires a precise and complete understanding of the glass panel substrate including the thickness of each layer and the position of said tin oxide layer as well as the knowledge of the exact distance between the conveyor and the laser.

[0022] Laser beam of prior art is always placed and fixed orthogonally to the surface to be decoated. To create a decoated surface the decoating apparatus must be displace along said surface using motors and complex drive systems.

[0023] Moreover, systems described in prior art are heavy to mount on a multiglazed window due to displacement elements (rails,---) and motors. The precision and the quality are hence not appropriate for small decoating portions due to movements of the apparatus. The decoating time is also long due to displacements of the laser light source especially for small decoating portion where many small displacements are needed within a short distance.

[0024] Thus, this apparatus can only be used in factories on glass panel that have just been manufactured. Hence, this apparatus cannot be used on a multi-glazed window of unknown structure, such as the number of glass panels, the number of lamination layers, the numbers of spacers, the number, nature and position of the coating system, ••• and that is already mounted on an object, for instance a building or a vehicle.

[0025] In addition, a large number of windows are already installed and are known to prevent the transmission of electromagnetic wave. Such windows cannot be replaced or be removed without important costs. The multi-glazed windows cannot be retrieved from the object, sent back to a factory to remove the part of the coating and then, sent back to be assembled again on the object. Such situations require the decoating process to be carried out in situ, when the multi-glazed window is mounted on the object. In most cases, the structure of these multi-glazed windows and the exact position of their coating system is completely unknown. It is therefore impossible for such apparatus to focus the laser properly on the coating system.

[0026] On top of that, when apparatus of the prior art are mounted on a multiglazed window, the tolerances of manufacture, the variability of mountingsystem occurs a variability of the distance between the coated surface and the decoating apparatus. Such variability implies that the focal point of the laser beam is not focused on the coated surface. The decoating of such apparatus of the prior art is not efficient, the laser beam being not focused at the right position.

[0027] Additionally, apparatus of the prior art cannot be aligned perpendicularly to the coating system to be treated causing a problem with the quality of the decoating. In fact, apparatus of the prior art are fixed to the window (or around) via suction pads, thus the parallelism in not possible with tolerances of the pads and the whole apparatus on top of the possible misalignment of the window or the curvature of said window. Then, misalignment needs to be calculated for each window once the apparatus is installed taking time, handling issues, •••

[0028] Back reflections can cause serious eye injuries, skin burns, or even ignite flammable materials, making it crucial to protect the operator and anyone else in the vicinity. Protective goggles can be used to minimize the risks associated with laser operations and ensure the safety of the operator but often said protective elements are not enough to protect around a decoating apparatus.

[0029] Additionally, during a decoating step of apparatus of the prior art, meaning while the laser beam is shot, back reflection against surface of the window can occur and can cause harm to operators, people and / or animals in the area or damage to the equipment.

[0030] Hence, the ongoing technical issue is to obtain a decoating apparatus and process that can be used on multiple kind of multi-glazed windows, wherein the position and the thickness of the glass panels and the position of the at least one coating system are not known; and that are able to work when said multiglazed window is already mounted on an object while accessibility is limited.Summary of invention

[0031] The present invention relates, in a first aspect, to a decoating apparatus. The decoating apparatus is designed to decoat a portion of a coating system present on a surface of a window.

[0032] The decoating apparatus comprises a laser device and a displacement means. The laser device comprises an optical laser unit to generate a laser beam. The laser device further comprises a housing comprising an aperture tolet the laser beam going out of the housing. The displacement means, preferably an articulated arm, is designed to displace and / or orientate the laser device especially the laser beam substantially normal to the surface of the window.

[0033] Preferably, the frequency of the laser beam equals to or is higher than substantially 20kHz.

[0034] The solution as defined in the first aspect of the present invention is based on the laser device comprises a opaque means opaque to the laser beam and designed to block a majority of back reflections of the laser beam during a decoating step.

[0035] The solution as defined in the first aspect of the present invention is also based on the decoating apparatus comprises an opening means. The opening means is designed to position the opaque means from an open to a closed position and / or from the closed to the open position.

[0036] The solution as defined in the first aspect of the present invention is also based on the opaque means is at least partially surrounding the aperture in the closed position.

[0037] The present invention also relates, in a second aspect, to a decoating method to at least partially decoat a portion of a coating system present on a surface of a window. The decoating method is performed with a decoating apparatus according to the first aspect. The decoating method comprises, for ensuring the protection against back reflection of the laser beam:Bl. a step of placing the opaque means in the closed position with the opening means,B2. after the step Bl, a step of decoating a frequency selective surface on the portion.

[0038] The present invention also relates, in a third aspect, to a multi windows decoating method to decoat a portion of a coating system present on a surface of a first window and a portion of a coating system present on a surface of a second window; each window are mounted on a stationary object, for instance a building, or mounted on a mobile object, for instance a vehicle, a rapid transit system according to the first aspect of the present invention. The decoating method comprises following steps :A. Placing a decoating apparatus according to the first aspect near the first window;B. Decoating a first window with the decoating method according to the second aspect of the invention;C. Repeating the step of placing and step of decoating for the second window.

[0039] The present invention also relates, in a fourth aspect, to the use of an opaque means and an opening means of a decoating apparatus according to the first aspect of the present invention to position the opaque means to a closed position to block a majority of back reflections of the laser beam during a decoating step.

[0040] The present invention in these different aspects permits to decoat a large scope of type of windows such as curved, strong geometric and dimensional disparities between windows in a same row, strong geometric and dimensional disparities of surfaces while be able to decoat in situ, where the object comprising said window to treat is positioned. In case of a mobile object, the present invention permits also to decoat at any location without moving the mobile object in a specific shed to treat windows to reduce cost, immobilisation time, handling, logistics, •••

[0041] The present invention in these different aspects permits to decoat in situ or in a factory while operators, people can pass around the decoating apparatus without limited risk of receiving part of the laser beam via back reflections. Then, operators can prepare another window, can operate / do some maintenance / repair / ••• on other parts of the stationary or mobile object near the area where the decoating apparatus is operating.

[0042] The present invention further permits to easily decoat windows even if windows not directly accessible meaning that even if the access to the window itself is very limited due to the presence of elements blocking access or preventing access to the surface itself, the present invention allows to decoat such windows. In fact, the decoating apparatus is able to decoat without being fixed or attached to the window or round the window.

[0043] The present invention further permits to decoat windows in situ without the need to remove window from the object to decoat in a factory reducing the handling, the risk of breakage, the logistics, •••

[0044] Another advantage of the present invention is equipment longevity. Back reflections can damage the laser apparatus, reducing its lifespan and requiringcostly repairs. Protective measures such as polarizers or beam expanders can be used to reduce the risk of damage and extend the equipment's longevity. By stabilizing the laser beam and reducing fluctuations or distortions, the laser apparatus can operate more efficiently and last longer.

[0045] It is noted that the invention relates to all possible combinations of features recited in the claims or in the described embodiments.

[0046] The following description relates to rapid transit system applications, but it’s understood that the invention may be applicable to others fields like automotive or building applications.Brief description of the drawings

[0047] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing various exemplifying embodiments of the invention which are provided by way of illustration and not of limitation. The drawings are a schematic representation and not true to scale. The drawings do not restrict the invention in any way. More advantages will be explained with examples.

[0048] FIG. 1 is a schematic view of a decoating apparatus, according to the present invention.

[0049] FIG. 2 is a 3D view of a laser device and an opaque means mounted on an articulated arm of a decoating apparatus according to the invention.

[0050] FIG. 3 is a schematic view of an opaque means in a closed position, according to the present invention.

[0051] FIG. 4 is a schematic view of an opaque means in an open position, according to the present invention.

[0052] FIG. 5 is a schematic view of a laser device during a decoating step according to the invention.

[0053] FIG. 6 illustrates a patchwork of decoated sub-frequency selective surfaces.

[0054] FIG. 7, FIG. 8 and FIG. 9 illustrate some embodiments in which the displacement means comprises at least a slide.

[0055] FIG. 10, FIG. 11 and FIG. 12 illustrate some embodiments in which the displacement means comprises at least a first jaw and the opening meanscomprises a rotating means to displace the first jaw from the open to the closed position.

[0056] FIG. 13 represents a decoating apparatus according the invention positioned to decoat in situ a window already mounted on a rapid transit system from the outside of the rapid transit system.

[0057] FIG. 14 represents a decoating apparatus according the invention positioned to decoat in situ a window already mounted on a rapid transit system from the inside of the rapid transit system.

[0058] FIG. 15 illustrates a decoating method according to the invention.

[0059] FIG. 16 illustrates a multi windows decoating method according to the invention.Detailed description

[0060] It is an object of the present invention to alleviate the above described problems and to decoat a window especially when the window is already mounted in a way to that reduces handling while be able to decoat in many location and environments while ensuring the security around .

[0061] In this document to a specific embodiment and include various changes, equivalents, and / or replacements of a corresponding embodiment. The same reference numbers are used throughout the drawings to refer to the same or like parts.

[0062] As used herein, spatial or directional terms, such as "inner", "outer", "above", "below", "top", "bottom", and the like, relate to the invention as it is shown in the drawing figures. However, it is to be understood that the invention can assume various alternative orientations and, accordingly, such terms are not to be considered as limiting. Further, all numbers expressing dimensions, physical characteristics, processing parameters, quantities of ingredients, reaction conditions, and the like, used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical values set forth in the following specification and claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention. In the following description, unless otherwise specified, expression “substantially” mean to within 10%, preferably to within 5%.

[0063] Moreover, all ranges disclosed herein are to be understood to be inclusive of the beginning and ending range values and to encompass any and all subranges subsumed therein. For example, a stated range of "1 to 10" should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g. 1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10. Further, as used herein, the terms "deposited over" or "provided over" mean deposited or provided on but not necessarily in surface contact with. For example, a coating "deposited over" a substrate does not preclude the presence of one or more other coating films of the same or different composition located between the deposited coating and the substrate.

[0064] Where the term “comprising” is used in the present description and claims, it does not exclude other elements or steps. Where an indefinite or definite article is used when referring to a singular noun e.g. "a" or "an", "the", this includes a plural of that noun unless something else is specifically stated. In this document, "configured to (or set to)" may be interchangeably used in hardware and software with, for example, "appropriate to", "having a capability to", "changed to", "made to", "capable of", or "designed to" according to a situation. In any situation, an expression "device configured to do" may mean that the device "can do" together with another device or component.

[0065] Furthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. When it is described that a constituent element (e.g., a first constituent element) is "(functionally or communicatively) coupled to" or is "connected to" another constituent element (e.g., a second constituent element), it should be understood that the constituent element may be directly connected to the another constituent element or may be connected to the another constituent element through another constituent element (e.g., a third constituent element).

[0066] In the following description, unless otherwise specified, expression “substantially” mean to within 10%, preferably to within 5%.

[0067] The following description relates to a decoating apparatus but it’s understood that the invention may be applicable to any laser apparatus to treat a surface of a window mounted in situ. Preferably, the laser apparatus is a decoating apparatus and the laser device is designed to decoat at least partially a portion of a coating system presents on a surface of the window.

[0068] Especially, FIG. 1 illustrates a part of a decoating apparatus according to the invention and especially a part of a displacement means 3 and a laser device 5 in front of a window 2 comprising two glass sheets and a coating system 23. The window has two external surfaces 21, each of the external surface is facing outside of the window.

[0069] According to some embodiments, the decoating apparatus can comprises a body on which the displacement means, as an articulated arm, is fixed. Said body can comprise an calculation unit to calculate and to control movements of the displacement means, a generator unit to generate a laser light and to control the laser device and a management unit to manage the calculation unit and the generator unit.

[0070] In some embodiments, the decoating apparatus can further comprise a control unit to interact with the displacement means and the laser device to be able to move the laser device in space while the laser beam is decoating. The control unit can drive the generator unit to adapt the power, the frequency of the laser light.

[0071] In some preferred embodiments, the decoating apparatus further comprises at least a battery and an inverter to avoid to turn off and restart the decoating apparatus during the displacement between two windows.

[0072] The body can also comprises a power supply to use electricity from the grid.

[0073] The displacement means can comprises motors to independently displace a specific part of the displacement means to increase the flexibility of the movement.

[0074] The displacement means can transmission kinks or similar to move horizontally and vertically the laser device, orticulated arm>

[0075] In some preferred embodiments, the displacement means comprises an articulated arm and the laser device is mounted on an end of the articulated arm.

[0076] In some embodiments, the control unit can also drive the calculation unit to articulate the articulated arm to move and orientate the laser device, especially the laser beam substantially normal to the surface of the window, to the desired position. The control unit can also drive the optical laser unit to focalise the laser beam and / or to adapt the scanning surface of the laser beam.

[0077] In such embodiments, the articulated arm is designed to displace and orientate the laser device, especially the laser beam substantially normal to the surface of the window, while avoiding to fix a part of the decoating apparatus on the window or on the frame, wall,--- to avoid risks of not be correctly attached and fall or risks to scratch the surface.

[0078] The articulated arm delocalises the laser device from the body of the decoating device.

[0079] The articulated arm comprises at least an articulation to displace the laser device in the space.

[0080] As illustrated in FIG. 2, according to some embodiments, the articulated arm can comprises several rotation components 331, 332, 333, 335, 337, 338 such as wrist, elbow, shoulder or alike acting as an articulation. Each of the rotation component can be directly fixed to another rotation component or can be fixed using a rigid bar 334, 336. The rigid bar can have different dimensions, such as lengths and / or diameter, depending on the desire application.

[0081] In some preferred embodiments, each of the rotation components is driven and controlled by the calculation unit.

[0082] According to the invention, the articulated arm is designed as a type of mechanical arm that is used for positioning precisely the laser device according to the window shape and geometry and the surface to decoat. The arm may be the sum total of the mechanism allowing either rotational motion or translational displacement of the laser device. These movements are usually programmed, but can be performed by remotely controlling the articulated arm (for instance via a remote, or computer, or tablet), or by piloting the articulated arm via the control panel of the equipment, or by manually moving the laser equipment along the desired movement to let the control unit of the articulated arm acquire this movement, to then repeat it.In some preferred embodiments, the articulated arm can allow the laser device to be moved along the 3 axis (cartesian coordinates: X, Y, Z: 1 vertical axis and 2 horizontal one, perpendicular to each other) or rotate around these 3 axis, allowing all 6 degrees of movements, such as all translation and rotation possible in or around each direction, so the amount of articulations of the articulated arm have to be sufficient to allow such movements. Amount of articulations is preferably more than 2, more preferably around 6.<Laser device>

[0083] According to the invention, the decoating apparatus comprises a laser device 5.

[0084] The laser device is mounted on an end of the articulated arm. In some embodiments in which the decoating apparatus comprises a body, the articulated arm the laser device is mounted on the end opposite to the end fixed to the body. The articulated arm allows the laser device to be moved and oriented in space to decoat correctly the coating system to be decoated.

[0085] According to some embodiments, the length of the laser device of about 180 mm to be able to facilitate the positioning and the movement of the laser device by the articulated arm.

[0086] According to some embodiments, the width of the laser device of about 180 mm to be able to facilitate the positioning and the movement of the laser device by the articulated arm.

[0087] According to some embodiments, the height of the laser device of about 180 mm to be able to facilitate the positioning and the movement of the laser device by the articulated arm.

[0088] In some other embodiments, the dimensions of the laser device can be different such as 100 x 100 x 100 mm depending on the elements comprised inside the laser device and the desired application.

[0089] In some other embodiments, the dimensions of the laser device can be different such as 200 x 200 x 200 mm depending on the elements comprised inside the laser device and the desired application.

[0090] The weight of the laser device is preferably equal to or smaller than about 5 kg to limit the vibration of the articulated arm while avoiding to over dimension said articulated arm while limiting the destabilization risks and jerky movements. cOptical laser unit>

[0091] The laser device 5 comprises an optical laser unit to generate a laser beam 51 from the laser light generated by the generator unit. The laser light is transmitted from the generator unit, disposed in the body to the optical laser unit of the laser device by a cable 405.

[0092] The laser beam is focalised at a focus point on the coating system to decoat when the decoating apparatus is ready to decoat. The laser beam has a specific direction. Preferably, said decoating device can comprise a lens array configured to focus said laser beam at a focus distance.

[0093] Due to surfaces of the window, the laser beam can be partially reflected creating back reflections 52 of the laser beam with a certain angle of incidence. It is understood that the opaque means protects against back reflections but also against any deviated ray in any manner, even coming directly out of the laser device in case of an error, or damaged laser and / or galvo for instance.

[0094] The articulated arm allows the laser beam to be substantially normal to the surface of the window at least during the decoating step.

[0095] In the sense of the present invention, the term “normal to the surface” is measured when the laser beam is in the zero position 590 as illustrated in FIG. 5. The zero position is in front of the laser beam when the laser beam is not orientable. The zero position is the (0, 0) point of the scanning area in case of the laser beam can be oriented with an orientation means. The scanning area 59 is defined in positive and negative value centred in the zero position as illustrated in FIG. 3. The articulated arm is able to displace and to orientate the laser device to keep this specific direction of the laser beam. The laser head can be orientate in a XI, Yl, Zl axis, especially the laser beam substantially normal at the position zero 590 to the surface of the window.

[0096] In some preferred embodiments, to avoid to have a laser beam with a fixed orientation, the laser device can further comprise an orientation means configured to control the direction of said laser beam 51 and / or the distance from the external surface of the window. In this way, the laser beam scans the portion to be decoated thanks to this orientation means. In such embodiments, the combination between an orientation means and the articulated arm allows to rapidly decoat a large coated portion of a coating system. Preferably, said orientation means may comprise at least a rotatable mirror or a mirror using agalvanometer based motor, to provide a light and fast orientation of the laser beam and to control and manage such orientation.

[0097] In some preferred embodiments, the laser beam generated by the generator unit goes through an optical fibre from the body to the laser device. The laser beam is transformed and shot by the laser device in direction of the surface to decoat. The transformation of the laser beam can be based on reflections by at least one mirror (or more) to go into a Control Unit Adapter (CUA), from where the laser beam can be then emitted toward the glass panel with correct size and shape, and angle and thickness, to remove the coating according to the predetermined pattern.

[0098] The invention permits to very fast remove a large portion of a coating system, for instance to improve the electromagnetic transmission of a window.

[0099] To avoid to adapt the focus point of the laser beam inside the decoated grid, the laser apparatus comprises a F-theta lens to flatten the focus point on a surface.

[0100] Preferably, the laser apparatus is a pulse laser apparatus and the frequency of the laser beam equals to or is higher than substantially 20kHz.

[0101] In some embodiments, in order to keep the focal point on the coating system, the laser device can comprises a focal device designed to measure the distance between the coating system and the laser device. Measurements are transmitted to the management unit that can drive the laser device and / or the calculation unit and / or a control unit to adapt the focal point on the coating system.

[0102] According to the invention, the laser device can comprise a housing to hide and to protect components. The housing comprises an aperture, such as an opening, in which the laser beam can go out of the laser device.

[0103] In some embodiments, the laser device can further comprise mirror or set of mirrors to aim and redirect laser beam in the correct direction.

[0104] In some embodiments, the laser device can further comprise an inclinometer to aim the laser device and the laser beam in the correct direction.

[0105] In some embodiments, the laser device can further comprise a camera to control the decoating pattern and a light to provide good luminosity to camera. < opaque means >

[0106] According to the invention, the laser device comprises an opaque means 6 opaque to the laser beam and designed to block a majority of back reflections 511 of the laser beam during a decoating step.

[0107] The term “opaque” means in the sense of the invention that the 100% of the laser beam reflected in the direction of the opaque means are blocked and cannot pass though the opaque means. The opaque means can be not opaque to other wavelengths than the range of the wavelength used by the laser beam. The opaque means can be in some embodiments transparent to a part of the spectrum of the visible light. The term “transparent” means that at least 0.1% is passing through.

[0108] It is understood in the sense of the invention that the opaque means is not reflecting the laser beam.

[0109] Preferably, to easily produce the parts while keeping the lightness, the opaque means can be made of a plastic suitable to be opaque for the wavelength of the laser beam.

[0110] Preferably, the opaque means can be made of ABS as for the housing.

[0111] In some preferred embodiments, the opaque material can be a multilayer material. The multilayer has preferably a plastic-based material and at least one metallic layer. The metallic layer can be an aluminum layer. More preferably, the multilayer material comprises two metallic layers and a plastic-based layer. The metallic layer can be treated to reduce risk of scratches such as applying a brush effect.

[0112] In some embodiments, the thickness of the opaque means is about 4 mm.

[0113] In some embodiments, the opaque means can comprise a soften lips in at least a part of the edge the opaque means and made of a material soften than the material of the opaque means. The soften material is designed to be in contact with or at least to be able to touch the external surface while limiting scratches and / or damages of said external surface. Preferably, the soften lips is placed on the whole edge of the opaque means to ensure the tightness against back reflections. The soften lips can be a thermoplastic-based, a rubber-based material or any other suitable material.

[0114] The soften lips can be on a part of the edge of a side of the opaque means. Preferably the soften lips is positioned symmetrically on a part of the edge of a side and the opposite side (to the front side).

[0115] In some preferred embodiments to adapt the decoating apparatus, especially the opaque means to the irregularity and / or the non-flat shape of the window and / or to compensate the variation of the distance between the opaque means and the external surface, the soften lips is flexible, meaning that is able to be bent easily.

[0116] In some preferred embodiments, to avoid any back radiations in any directions due to default or any other reason, the opaque means can surround at least 80 % of the perimeter of the aperture in the closed position, preferably the opaque means surrounds at least 90 % of the perimeter of the aperture in the closed position and more preferably the opaque means surrounds at least 95 % of the perimeter of the aperture in the closed position and even more preferably the opaque means surrounds substantially 100 % of the perimeter of the aperture in the closed position.< opening means >

[0117] According to the invention, the decoating apparatus comprises an opening means 7 between the laser device and the opaque means, the opening means being designed to position the opaque means from an open 61 to a closed position 62 and / or from the closed to the open position.

[0118] In some preferred embodiments, The opening means is between the laser device and the opaque means and more preferably the opening means is attached to the laser device, especially the housing.

[0119] FIG. 3 illustrates an opaque means 6 in a closed position 61 while FIG. 4 illustrates an opaque means 6 in an open position 62. This change of position is done by the opening means 7. The closed position is the position in which the opaque means is at the minimal distance from the external surface. An opened position is any intermediate opened position between the closed position and the farthest opened position.

[0120] According to the invention, the decoating apparatus can comprises several open positions from the closed position to the furthest open position compared to the closed position. These several open position can be any intermediary opened position that could be needed due to shape of window 2, the coating position according to external surface 21, any obstacle in the way, or depending to the desired applications.

[0121] According to some embodiments, as illustrated in FIG. 7 to FIG. 9, the opening means can comprise a slide 501, 502 to displace the opaque means along the slide from the open to the closed position.

[0122] FIG. 7 illustrates an opaque means in an opened position, the furthest open position while FIG. 8 illustrates an opaque means in an intermediate open position and FIG. 9 illustrates an opaque means in the closed position.

[0123] In some preferred embodiments, the opening means can comprise several slides 501, 502 to stabilize the slide along them.

[0124] In preferred embodiments, slides are positioned symmetrically on the housing.

[0125] In FIG. 7 to FIG. 9, the opaque means comprises an opened box having lateral faces 503 made of an opaque-to-the-wavelength-of-the-laser material such as ABS. The front face 504 can comprises an opening to let the laser beam passing through. In some embodiment, this front face is absent as illustrated in said figures.

[0126] It is understood that the opaque means can comprises the corresponding mechanism to the opening means. In such embodiments, some lateral faces can comprises an element 561, 562, 563, 564 corresponding to the corresponding slide such as an elongated slot, an inverted T-shape into which the slide can move or any other suitable element able to cooperate with the corresponding slide.

[0127] In such illustrated embodiments, the housing comprises on a lateral face two slides 501 and 502 and (not shown) on the opposite lateral face two other slides, symmetrical to the slides 501 and 502. The opaque means comprises four slits 561, 562, 563, 564; each of the slits corresponds to one of the slides. The slits and slides allows the opaques means to move from a farthest open position 62 or any intermediate open positions 63, 64 to the closed position 61 and from the closed position 61 to any intermediate 63, 64 or farthest 62 open position by a translation movement. This translation movement can be managed manually, mechanically and / or electronically.

[0128] In such illustrated embodiments, the opaque means is a parallelepiped rectangle with opaque lateral faces and an aperture in the front face. In FIG. 7 to FIG. 9, this aperture has substantially the size of the face. The shape can depend on the housing.

[0129] The dimensions of the parallelepiped rectangle can depend on the dimensions of the decoating apparatus and / or the angle of reflection.

[0130] The distance between the closed position and the farthest position can depend on the dimensions of the decoating apparatus and / or the angle of reflection.

[0131] In some preferred embodiments, the width of lateral face is about 170 mm and the height is about 180 mm. The distance between the closed position and the farthest position is about 80 mm.

[0132] A soften lips can be added on a part of the edge of the opaque means that can face the window. The lips can be added on the whole edge or on a part such as on the edge / part of the edge of the lateral faces.

[0133] In some embodiments, the position (open, closed) can be blocked by a maintaining means.

[0134] According to some embodiments, as illustrated in FIG. 10 to FIG. 12, the opaque means can comprise at least a first jaw 505, 506. The jaws can be on the top, on the side or on the bottom of the laser device.

[0135] In such embodiments, the opening means comprises a rotating means 71, 72 to displace the first jaw from the open to the closed position.

[0136] In such embodiments, the opening means can comprise a rotating means to displace the first jaw from the open to the closed position.

[0137] Preferably, to balance the weight and limit the lever arm, the opaque means comprises several jaws 505, 506.

[0138] As illustrated in FIG. 10 to FIG. 12, the opaque means can comprises two jaws, a first jaws 505 and a second jaws 506. Said jaws can comprises a gear wheel 507, 508 or any other suitable elements to transmits the movement of the opening means.

[0139] In such illustrated embodiments, the opaque means comprises a first 505 and a second 506 jaws.

[0140] In these illustrated embodiments, jaws have a generic U-shape comprising a top / bottom face and lateral faces. Once the jaws are in the closed position, lateral faces of jaws are against the corresponding lateral face of the other jaw.

[0141] Jaws can comprises a rotation means 507, 508 to position the opaque means (jaws) in the farthest 62, intermediate 63 and / or closed 61 positions.

[0142] In these illustrated embodiments, opaque means comprises a gear wheel on each of the jaws to open / close jaws in the same manner. The decoating device can comprises a rotation means to activate the opening / closing of the jaws.

[0143] A soften lips can be added on a part of the edge of the opaque means that can face the window. The lips can be added on the whole edge or on a part such as on the edge / part of the edge of the lateral faces. A soften lips can also be added between jaws to avoid any damages.

[0144]

[0145] In any of the embodiments, open positions permits to access to the front face of the laser device and / or to position correctly the laser device on the external surface of a window.

[0146] In any of the embodiments, the positioning of the opaque means by the opening means can be performed manually such as by hands, handle, ••• or with a motor or alike. The positioning can be controlled by the control unit. In some preferred embodiments, automating positioning can be used to make operator error impossible. Such automating positioning can be actuator system such as electric cylinder, motor + rack, electromagnet, or alike.

[0147] In some embodiments, a spring-loaded system or alike can be used to press the opaque means against the external surface.

[0148] In some embodiments, a maintaining means to hold the opaque means in an open and / or the closed position. The maintaining means can be a magnetic system or lever, or bal l / spring system or alike.

[0149] In some embodiments, the decoating apparatus can comprise a locking means to lock the opaque means at the desired stroke length. The locking means can be a clamping system; said clamping system can clamp by pressure screw and knob, screws, levers or alike.

[0150] In some embodiments, the decoating apparatus can comprises a security means to check and / or activate / deactivate the generation of the laser beam if the opaque means is not correctly positioned in the closed position just before and / or during a decoating step.<contact element>

[0151] In some embodiments, the laser device can comprise a contact element 52 designed to correctly position the laser device in front a window to decoat and to facilitate the correct positioning substantially parallel to the tangential plane of the zone to be decoated. The contact element is designed to be positioned between the laser device 5 and a window 2 to treat. <decoat>

[0152] In the sense of the invention, the term “decoat” means to modify the continuity of the coating system by removing or by melting for example. The decoating can be a partial decoating.

[0153] The coating system 23 generally uses a metal-based layer and infrared light is highly refracted by this type of layer. Such coating system is typically used to achieve a low-energy multi-glazed window.

[0154] In some embodiment, the coating system can be a heatable coating applied on the multi-glazed window to add a defrosting and / or a demisting function for example and / or to reduce the accumulation of heat in the interior of a building or vehicle or to keep the heat inside during cold periods for example. Although coating system are thin and mainly transparent to eyes.

[0155] Usually, the coating system is covering most of the surface of the multiglazed window 2.

[0156] The coating system can be made of layers of different materials and at least one of these layers is electrically conductive. In some embodiments, for example in automotive windshields, the coating system can be electrically conductive over the majority of one major surface of the multi-glazed window. This can causes issues such as heated point if the portion to be decoating is not well designed.

[0157] A suitable coating system is for example, a conductive film. A suitable conductive film, is for example, a laminated film obtained by sequentially laminating a transparent dielectric, a metal film, and a transparent dielectric, ITO, fluorine-added tin oxide (FTO), or the like. A suitable metal film can be , for example, a film containing as a main component at least one selected from the group consisting of Ag, Au, Cu, and Al.

[0158] The coating system may comprise a metal based low emissive coating system. Such coating systems typically are a system of thin layers comprisingone or more, for example two, three or four, functional layers based on an infrared radiation reflecting material and at least two dielectric coatings, wherein each functional layer is surrounded by dielectric coatings. The coating system of the present invention may in particular have an emissivity of at least 0.010. The functional layers are generally layers of silver with a thickness of some nanometers, mostly about 5 to 20nm. The dielectric layers are generally transparent and made from one or more layers of metal oxides and / or nitrides. These different layers are deposited, for example, by means of vacuum deposition techniques such as magnetic field-assisted cathodic sputtering, more commonly referred to as "magnetron sputtering". In addition to the dielectric layers, each functional layer may be protected by barrier layers or improved by deposition on a wetting layer.

[0159] As illustrated in FIG. 15, according to the second aspect, the present invention relates to a decoating method 400 to at least partially decoat a portion of a coating system present on a surface of a window with a decoating apparatus according to the first aspect. The decoating method comprises, for ensuring the uniform quality of the decoating over the portion while protection the environment against the back reflections, a step Bl of placing 410 the opaque means in the closed position with the opening means. The decoating method 400 further comprises, after the step of placing 410, a step B2 of decoating 420 a frequency selective surface on the portion to ensure the uniform quality of the decoating over the portion. Thanks to the step 410, a majority of back reflections of the laser beam are blocked by the opaque means during the decoating step 420.

[0160] An uniform quality corresponds for example to a continuity of lines of the decoating pattern, correct width of lines, absence of holes in the decoating pattern, alignment of the lines of the pattern and of the different pattern one to another, coating well removed of the decoated area, alignment of the pattern with the window, •••

[0161] In some preferred embodiments, the decoating method can comprises, after the step of decoating 420, a step 430 placing the opaque means in an opened position with the opening means.

[0162] Preferably, the opaque means is separated from the closest surface of the window by a distance Dg during a decoating step. A distance Dg equals to zero means that the opaque means is against this external surface.

[0163] In the sense of the invention, the term “against” means that at least a part of the opaque means is in contact with the external surface of the window.

[0164] According to some embodiments, the distance Dg is higher than or equal to 0 mm (0 mm < Dg), preferably higher than or equal to 0.1 mm (0.1 mm < Dg) and more preferably higher than or equal to 0.5 mm (0.5 mm < Dg). The distance can be measured from the soften lips to the external surface in corresponding embodiments.

[0165] In addition to advantages of the present invention, the opaque means permits to the laser apparatus to provide cost-effectiveness by reducing the risk of damage to the equipment and regulatory compliance by meeting strict industry regulations. Furthermore, protective measures such as exhaust systems or filters can help reduce the environmental impact of the process, making the work environment safer and more sustainable.

[0166] Process efficiency is another advantage of the present invention. Back reflections can cause the laser beam to fluctuate or distort, negatively affecting the efficiency of the process. The laser beam may not be optimally focused on the window, leading to uneven or incomplete removal of the coating. The laser beam can be stabilized, ensuring optimal focus and improving the efficiency of the process. This can result in a quicker and more efficient decoating process, saving time and increasing productivity.

[0167] Quality control is another advantage of the present invention. Back reflections can negatively affect the quality of the end product. The fluctuations or distortions in the laser beam can lead to uneven or incomplete removal of the coating, resulting in a subpar end product. The laser beam can be stabilized, ensuring that it is properly focused on the window. This can result in a more precise and uniform removal of the coating, leading to higher quality end products.

[0168] Preferably, before that the step Bl, the decoating method can comprises a step of placing the decoating apparatus to a first working position.

[0169] In the sense of the invention, the term “working position” means a position in which the decoating apparatus is able to decoat the portion of the coatingsystem while the laser device is substantially perpendicular to the tangent at the focal point of the coating system to decoat. That means that the decoating apparatus can stay at a position and only the laser device is moved to a new position.

[0170] In some embodiments, the decoated frequency selective surface can comprise decoated segments creating zones where the coating system is still present. Decoated segments can have a width between 15 pm and 150 pm, preferably between 30 pm and 70 pm, and more preferably substantially 50 pm, forming specific designs, such as lines, polygons, hashtag-like, a grid or a like.

[0171] Decoated designs can depend on wanted visual aspect and / or desired wavelength transparency for example.

[0172] Preferably, at least one coating system is present on one interface, meaning one surface of the window 2. Preferably, the coating system is on one of the internal surfaces of the window, surfaces that are not facing the outside of the window.

[0173] Moreover, if the window presents two coating systems applied on two different interfaces, a first coating needs to be decoated before the second one. For example, the decoating apparatus decoats a portion on the closest coating system and then decoats the second one. The focus point is adapted to be on the correct coating system. Preferably, to avoid to modify the decoating of the closest coating, the decoating apparatus decoats a portion on the farthest coating system and then decoats the closest one. The needed power to decoat the farthest one is higher than the needed power to decoat the closest one and risks to degrade the decoated shape of the portion on the closest one if this one is done before the farthest coating.

[0174] Dimensions and shape of the portion to be decoated or the decoated portion depend on the desire application. Thanks to the decoating apparatus of the invention, the decoating apparatus do not necessary be adapted to the dimension of the portion to be decoated and the same decoating apparatus can be used for a large type of windows and environments.

[0175] The position of the decoated portion 25 on the multi-glazed window depends on the application. Preferably, the portion of the coating system to be decoated represents at least 50% of the surface of the coating system, more preferably, the portion of the coating system to be decoated represents at least70% of the surface of the coating system and even more preferably, the portion of the coating system to be decoated represents at least 80% of the surface of the coating system. It is understood that the portion of the coating system to be decoated and the decoated portion represent a surface of the coating system and not the decoating itself. The present invention permits to decoat a small amount of coating, less than 3%, to improve the transmission of radio waves on a large or not portion of said coating.

[0176] In some preferred embodiments, as illustrated in FIG. 6, to accelerate the time to decoat a large surface, the frequency selective surface FSS1 can be composed of at least a patchwork of sub-frequency selective surfaces FSS11, FSS12, FSS13, FSS14, FSS21, FSS22, FSS23, FSS24, FSS31, FSS32, FSS33, FSS34. Therefore, when laser processing is performed on a region larger than a region that can be processed in one process, a pattern formed in a predetermined size that can be processed in one process is formed a plurality of times and continuously arranged. As a result, a continuous pattern can be formed in the entire desired region by connecting decoated tile-like portions like a so-called patchwork.

[0177] That means that the decoating step 420 can comprises several decoating substeps 421, 422, 423, 424.

[0178] Each of the decoating substeps can be performed by scanning a zone, scanning either via an optical or ultrasonic means for instance, to define the correct shape to the surface to decoat with enough precision, with the laser beam to decoat inside said zone meaning that the orientation of the laser beam is adapted inside said zone. Preferably, the laser device is moving with the articulated arm while the laser beam is scanning to increase the speed of decoating.

[0179] In some embodiments, the laser device can comprises a confocal or any other element designed to scan the surface in front of where the laser beam will be shot, to adjust laser beam position accordingly.

[0180] Preferably, the frequency selective surface is a grid made of decoated segments to form a decoated grid. The grid can be made of a patchwork of subgrids each of the subgrids are connected edge-to-edge.

[0181] In fact, the decoated grids placed in a patchwork manner and connected edge-to-edge allow to create a larger frequency selective surface especiallywhen the decoated grids are created by a decoating apparatus using a galvo head to orientate the laser designed to decoat the coating system.

[0182] Dimensions Lml, Lm2, Lm3, Lm4, W3n, W2n, Win of the sub frequency selective surfaces can depends on the size of the maximum surface that the decoating apparatus can decoat at once and also can depends on the radius of curvature around the focal point and the laser parameter such as the scan field, Lmax, and the zone Rayleigh, Za.

[0183] As illustrated in FIG. 5, during a decoating step, the laser beam is localised at a focus point 25 on the coating system 23.

[0184] During a decoating step, the laser device is moving while the laser beam is localised on the coating system to decoat the coating system.

[0185] In order to correctly decoat a coating system, the laser beam must be precisely focused onto the targeted coating system. Therefore, the position of the coating system must be known with a precision at least three times smaller than the depth of field of the decoating device. The depth of field corresponds to the distance around the focal point of a focused laser beam where the laser beam diameter is considered constant. This distance depends greatly of the laser beam characteristics and the optics used for focusing said laser beam. Typically, the depth of field is around 0.5 mm, which means that the precision on the focus position of the decoating device should be around 0.1-0.2 mm.

[0186] To know the position of the coating system, a cofoncal unit can be added to the laser device designed to calculate the position of the coating system.

[0187] According to the invention, the decoating method is performed in a factory meaning before to install the treated window.

[0188] Preferably, the decoating method is performed in situ with the decoating apparatus to avoid removing the window from the object.

[0189] A rapid transit system 100 comprises several windows 201, 202, 203, 204 in a same row or in several rows as illustrated in FIG. 13.

[0190] According to some embodiments, the decoating method according to the invention permits to perform the decoating method from the inside of the stationary or the mobile object as illustrated in FIG. 13. In such embodiments, the decoating apparatus is position on the floor or on a platform to be correctly positioned. The displacing step can be made by the platform once the decoating apparatus is positioned on the platform.

[0191] In some embodiments, the decoating method according to the invention permits to perform the decoating method from the inside of the stationary or the mobile object as illustrated in FIG. 14. The decoating apparatus is moved inside the rapid transit system and positioned near a window to be treated.

[0192] The present invention also relates to a multi windows decoating method to decoat a portion of a coating system present on a surface of each of at least a first window and a second window mounted on a stationary object, for instance a building, or mounted on a mobile object, for instance a vehicle, a rapid transit system to treat multiple windows.

[0193] As illustrated in FIG. 16, the multi windows decoating method comprises a step A of placing 402 a decoating apparatus according to the first aspect near the first window. Preferably, the decoating apparatus is placed in front of the window to be treated.

[0194] In the sense of the present invention, the term “near” means that the decoating apparatus is not fixed to the windows, the frame or the body of the object on which the window is fixed.

[0195] In some embodiments, the body can be around 70 cm from the window to be decoated, preferably placed substantially normal to the window, and with the articulated arm aligned substantially along the main length of the body, or parallelly to the window, with the articulated arm aligned substantially perpendicular to the main body length.

[0196] Preferably, the centre of the articulated arm, which corresponds to the first articulation between the body and the articulated arm, is placed aligned with the centre of the window, the centre along vertical axis, and along the length axis of the window).

[0197] The vertical positioning of the body from the window could be ensured by lifting the body with a lifting equipment, for example a lifting platform, scissor lift platform, “cherry picker” or so on.

[0198] During the decoating step, the articulated arm displaces and orientates the laser device along the portion and keeps the laser beam substantially normal to the surface or to the scanning zone.

[0199] Once the decoating apparatus is placed near the first window, the multi windows decoating method comprises a step B of decoating the first window according to the decoating method of the second aspect of the present invention.

[0200] The multi windows decoating method further comprises a step C of repeating the stap A and step B for the second window.

[0201] These steps are reproduced as many times as the number of windows to treat.

[0202] The multi windows decoating method can comprises a step of moving 403 the decoating apparatus to another location to decoat another window or another row of windows or to be stored. As illustrated in FIG. 13, the decoating apparatus can decoat a first row of windows 201, 202, 203, 204, 205 and then (or the contrary) decoat a second row of windows 211, 212, 213, 214, 215.

[0203] The multi window decoating method can comprise a step 401 before the step Bl to assemble and / or to provide the decoating apparatus inside or outside the object.

[0204] The multi window decoating method can also comprise a step 404 after all decoating steps to disassemble and / or to retrieve from the object the decoating apparatus.

[0205] The invention also relates to the use an opaque means and an opening means of a decoating apparatus according to the first aspect to position the opaque means to a closed position to block a majority of back reflections of the laser beam during a decoating step.

[0206] Thus, the decoating apparatus of the invention can be used to improve the electromagnetic properties of a multi-glazed window already mounted on a stationary object, for instance building, or on a mobile object, for instance a vehicle, a train or alike without dependency to the configuration of the object.

Claims

ClaimsClaim 1. Decoating apparatus (1) designed to decoat a portion of a coating system (23) present on a surface of a window (2), the decoating apparatus comprising- a laser device (5), comprising o an optical laser unit to generate a laser beam (51), o a housing comprising an aperture to let the laser beam going out of the housing- a displacement means (3) designed to displace and / or orientate the laser device especially the laser beam substantially normal to the surface of the window; characterised in that the laser device comprises an opaque means (6) opaque to the laser beam and designed to block a majority of back reflections (511) of the laser beam during a decoating step, in that the decoating apparatus comprises an opening means (7) designed to position the opaque means from an open (61) to a closed position (62) and / or from the closed to the open position, and in that the opaque means is at least partially surrounding the aperture in the closed position.Claim 2. Decoating apparatus (1) according to claim 1, wherein the displacement means comprises an articulated arm and the laser device is mounted on an end of the articulated arm.Claim 3. Decoating apparatus (1) according to any preceding claims, wherein the opaque means surrounds at least 80 % of the perimeter of the aperture in the closed position, preferably the opaque means surrounds at least 90 % of the perimeter of the aperture in the closed position and more preferably the opaque means surrounds at least 95 % of the perimeter of the aperture in the closed position and even more preferably the opaque means surrounds substantially 100 % of the perimeter of the aperture in the closed position.Claim 4. Decoating apparatus according to any preceding claims, wherein the opaque means comprises a soften lips in at least a part of the edge the opaque means and made of a material soften than the material of the opaque means.Claim 5. Decoating apparatus according to claim 4, wherein the soften lips is placed on the whole edge of the opaque means.Claim 6. Decoating apparatus according to any preceding claims, wherein the laser device comprises a F-theta lens.Claim 7. Decoating apparatus according to any preceding claims, wherein the laser device comprises a orientation means designed to orientate the laser beam.Claim 8. Decoating apparatus according to any preceding claims, wherein the decoating apparatus comprises a contact element designed to correctly position the laser device in front a window to decoat.Claim 9. Decoating apparatus according to claim 1 to 8, wherein the opening means comprises a slide (501, 502) to displace the opaque means along the slide from the open to the closed position.Claim 10. Decoating apparatus according to claim 1 to 8, wherein the opaque means comprises at least a first jaw (505, 506) and wherein the opening means comprises a rotating means (71, 72) to displace the first jaw from the open to the closed position.Claim 11. Decoating method (400) to at least partially decoat a portion of a coating system present on a surface of a window (2) with a decoating apparatus according to any preceding claims, the decoating method comprises, for ensuring the protection against back reflection of the laser beam, a step (410) of Bl of placing the opaque means in the closed position with the opening means and a step (420) B2, after the step Bl of decoating a frequency selective surface on the portion.Claim 12. Decoating method according to claim 11, wherein the decoating method is performed in situ.Claim 13. Decoating method according to any claim 11 - 12, wherein the opaque means is separated from the closest surface of the window by a distance Dg during a decoating step.Claim 14. Decoating apparatus (1) according to claim 13, wherein the distance Dg is higher than or equal to 0 mm (0 mm < Dg), preferably higher than or equal to 0.1 mm (0.1 mm < Dg) and more preferably higher than or equal to 0.5 mm (0.5 mm < Dg).Claim 15. Use of an opaque means and an opening means of a decoating apparatus according to claims 1 to 12 to position the opaque means to a closed position to block a majority of back reflections of the laser beam during a decoating step.

Images