OPTICAL ELEMENT WITH REMOVABLE PROTECTIVE FILM

Description

[0001] The invention relates to an optical element mounted in a mount.

[0002] Optical elements for a laser processing head or a fiber optic cable that can be connected to it, such as lenses or protective glasses, are usually mounted in a holder or frame and are attached in or to the laser processing head or the fiber optic cable connector using this holding element. The holding element is either inserted into a receptacle or screwed onto the processing head or the connector using a thread. This can cause particles to become loose on the thread and fall onto the optical element or other optical components of the laser processing head. When the optical element is replaced, for example due to contamination, particles from the ambient air can fall onto the newly attached optical element, which can then cause problems during operation of the laser processing head.

[0003] The main goal when replacing an optical element, e.g. when changing the protective glass, is to replace the dirty or defective optical element with a new, clean one. This usually requires opening the sensitive interface between the laser processing head and the fiber optic cable connector. During this process, it is important to prevent particles from falling onto optical components in the laser processing head or connector. Due to the high power density at the optical components, such particles would burn in and thus lead to a deterioration in beam quality and even a failure of the entire system. Due to this problem, it is important to ensure the highest possible cleanliness when replacing an optical element.

[0004] There are already various proposals to facilitate the replacement of optical elements on laser processing heads: WO 2011 / 004084 A1 discloses a laser processing head with a focusing lens held in a cassette that is inserted into the housing of the laser processing head. However, removing the lens from the cassette or inserting a new lens requires a special tool to prevent the lens from being gripped by the hands on the optically active surfaces.

[0005] EP 1 324 093 A1 describes a transport container for an optical component. The component can be removed from the transport container using a slider for insertion into a system. However, the transport container is relatively large and complex and therefore unsuitable for replacing an optical element in the connector of a fiber optic cable.

[0006] DE 10 2013 105 945 A1 also discloses a laser processing head consisting of two rotatably connected housing parts. A protective glass is arranged in one, first housing part and forms an end face of the first housing part facing the other, second housing part. The frame of the protective glass has an interruption so that the protective glass can be gripped by its peripheral surface.

[0007] Finally, DE 20 2014 103 543 U1 describes a packaging for an optical element held in a holder with a flexible base and two lateral wall sections. The optical element can be removed from the packaging using the holder and released from the holder by deforming the flexible base.

[0008] The protection of surfaces using removable protective films is known from US 2017 242455 A1 for a touchscreen, from WO 2003 / 060563 A2 for a face shield, and from DE 10 2014 202 075 A1 for the optics of a camera system for minimally invasive surgery. In these applications, the protected surface is directly touched by the protective film.

[0009] The object of the present invention is to provide an alternative device for the simple and clean replacement of optical elements in a laser processing head or in a connector of a fiber optic cable.

[0010] This object is achieved in an optical element mounted in a mount, which is designed as a protective glass, mirror or lens for a laser processing head or for the plug of a fiber optic cable, in that one side of the optical element is at least partially, in particular completely, covered by a protective film which is adhered to an end face of the mount surrounding the optical element via at least one adhesive surface, and in that the protective film has a lateral projection for handling the optical element and for peeling the protective film off the mount. The film side of the protective film facing the optical element is non-adhesive, at least in the area covering the optical element, in order to ensure that the protective film does not adhere to the optical element.The front of the mount extends higher than the covered side of the optical element to prevent contact between the protective film and the optical element. This prevents particles from the protective film from reaching the optical element.

[0011] According to the invention, the protective film thus serves on the one hand to protect the optical element from contamination and on the other hand as an assembly aid: The optical element can be gripped by the protective film and inserted, for example, into a laser processing head or into the connector of a fiber optic cable. The protective film is then peeled off the mount without leaving any residue. In this way, particles from the ambient air have difficulty falling onto the newly mounted protective glass. The tear resistance of the protective film is selected such that it does not tear either under the weight of the mounted optical element or when peeled off. Advantageously, the holding force of the at least one adhesive surface or all adhesive surfaces together is greater, in particular at least 1.3 times greater, than the combined weight of the optical element and the mount, and the tear resistance of the protective film is greater than the holding force of the at least one adhesive surface per unit area of ​​the adhesive surface.Preferably, the adhesive strength of the at least one adhesive surface is greater than 1.3 N / 25 mm, in particular greater than 5 N / 25 mm, and particularly preferably at least 8 N / 25 mm. In this way, the optical element mounted in the mount can be securely held and supported by means of the protective film.

[0012] Ideally, the optical element is glued into the mount so that there are no threaded connections that could cause thread abrasion when mounting the optical element into the mount.

[0013] If a small optical element is to be inserted into a component with limited installation space, e.g. into the connector of a fiber optic cable, the protective film only needs to protrude over the socket on one side, e.g. in the form of a tab, so that the user has one hand free to hold the component into which the optical element is to be inserted when replacing the optical element. With a larger (heavier) optical element, two tabs protruding to the sides serve to accurately insert the optical element into the component, e.g. into the laser processing head. This means that the optical element can be inserted into a tight fit without jamming. It is also possible to insert an optical element according to the invention into a cassette and then peel off the protective film before the cassette is pushed into the laser processing head.

[0014] In particularly preferred embodiments, the protective film is a polyester film and the at least one adhesive surface, in particular silicone-based, can be removed from the frame together with the protective film when the protective film is peeled off, i.e. without leaving any residue.

[0015] In a preferred embodiment, the protective film has at least one exposed adhesive surface exclusively in areas adjacent to the front side of the socket. For example, the protective film can have a local adhesive coating exclusively in these areas, which forms the at least one exposed adhesive surface.

[0016] In another development, the protective film is formed by two film layers glued together by means of an adhesive layer located between them, wherein the adhesive layer is covered by the lower film layer facing the optical element except for the at least one exposed adhesive surface. The lower film layer can, for example, have several individual or separate film sections for covering the adhesive layer or at least one recess through which the adhesive layer is exposed as an adhesive surface. In the latter case, the two film layers can be formed by two film sections of an adhesive film provided with the adhesive layer on one side, which are folded onto one another and each rests against one another with its adhesive sides. In the area of ​​the protective glass, the protective film is therefore folded such that the non-adhesive film side is on the outside and the adhesive sides touch.This ensures that the adhesive side does not touch the optical element. One or more recesses in the lower film layer allow the adhesive side of the upper film layer to come into contact with the frame.

[0017] According to the invention, the front side of the mount projects higher than the covered side of the optical element in order to prevent contact between the protective film and the optical element. Starting from its projecting front side, the mount can extend continuously, in particular conically or concavely, inwards to the optical element. This surface shape facilitates cleaning of the optical element with a cotton swab soaked in cleaning agent: the entire surface can be cleaned without having to put it down and without there being a risk of fibers from the cotton swab becoming loose and getting caught in the mount. If the optical element projects higher than an adjacent inner edge of the mount, no dirt can accumulate on the optical element during cleaning, as would be the case with an optical element that is lower (recessed) than the inner edge.

[0018] Advantageously, the optical element is arranged in a protective packaging enclosing the frame in such a way that it can be removed from the opened protective packaging by means of the lateral projection of the protective film.

[0019] Further advantages and advantageous embodiments of the subject matter of the invention will become apparent from the description, the claims, and the drawings. Likewise, the above-mentioned and further listed features can be used individually or in combination. The embodiments shown and described are not intended to be exhaustive, but rather serve as examples for describing the invention. They show: Figs. 1a, 1b schematically show an optical element according to the invention with a glued-on, single-layer protective film ( Fig. 1a ) and with the protective film removed ( Fig. 1b ); Figs. 2a, 2b the cross-section of a two-layer protective film ( Fig. 2a ) and an underlying foil cut ( Fig. 2b ); Fig. 3 shows the cross-section of the optical element according to the invention; Figs. 4a, 4b show a protective packaging for the optical element according to the invention in the closed state ( Fig. 4a ) and in the open state ( Fig. 4b ); Figs. 5a, 5b show a longitudinal section through an optical element installed in a laser processing head ( Fig. 5a ) and a perspective view of the laser processing head when exchanging the optical element ( Fig. 5b ); and Fig. 6 a perspective view of a laser light cable when replacing the optical element.

[0020] Fign. 1a, 1b show one in one version 2 mounted optical element 1, such as a protective glass, a mirror or a lens.

[0021] The top 3 of the optical element 1 is covered by a protective film 4completely covered, the upper end face surrounding the optical element 1 5 the frame 2. For handling the optical element 1 and for removing the protective film 4 from the frame 2, the protective film 4 has a lateral projection in the form of two opposing tabs 6 which protrude laterally beyond the frame 2. The protective film 4 preferably consists of a polyester film, on one side of which an adhesive layer 7 silicone-based adhesive layer 7 can be removed without residue when the protective film 4 is removed from the socket 2, together with the polyester film.

[0022] As in Fig. 1a As shown, the film underside facing the optical element 1 can have such an adhesive layer 7 exclusively in areas that lie against the end face 5 of the mount 2, in order to form here, by way of example, two almost semicircular, local adhesive surfaces 8 with which the protective film 4 is adhered to the end face 5 of the mount 2. The underside of the film is non-adhesive in the area covering the optical element 1 and therefore cannot adhere to the optical element 1. In addition, the end face 5 of the mount 2 projects upwards over the covered top side 3 of the optical element in order to prevent contact between the protective film 4 and the optical element 1.

[0023] Fig. 2a shows the cross-section of a two-layer protective film 4, which has between its two film layers 9a, 9b an adhesive layer 7. The Fig. 2a lower film layer 9b has at least one recess 10through which the adhesive layer 7 is exposed as an adhesive surface 8.

[0024] In Fig. 2b is a one-piece foil cut 11 for the two-layer protective film 4. The Fig. 2b visible top 12 The adhesive layer 7 is applied over the entire surface of the film blank 11. The film blank 11 consists of two congruent film sections 13a, 13b, where the Fig. 2b right film section 11b has two almost semicircular cutouts 10. The two film sections 13a, 13b are folded with their adhesive sides around a central fold line 14 folded together to Fig. 2a to form the two-layer protective film 4 shown.

[0025] Instead of being a single-piece film cut, the protective film 4 can also have a lower film layer formed from several separate film sections in order to cover different areas of the adhesive layer 7 and leave only the required adhesive surfaces 8 exposed. Alternatively, the protective film 4 can be formed as a single layer and have an adhesive coating 7 as the adhesive surface(s) 8.

[0026] Starting from its front side 5 projecting upwards over the optical element 1, the frame 2 extends, as shown in Fig. 3 shown, without steps conically downwards and inwards to an inner edge adjacent to the optical element 1 15.This facilitates cleaning of the optical element 1 with a cotton swab soaked in cleaning agent: The entire surface can be cleaned without having to put it down, without the risk of fibers becoming loose and getting caught. The optical element 1 protrudes upwards beyond the inner edge 15 of the mount 2, so that no dirt can accumulate on the optical element 1 during cleaning, as would be the case with an optical element 1 that is lower (recessed) than the inner edge 15.

[0027] As in Fign. 4a, 4b As shown, the optical element 1, taped on the top, is placed in a hinged protective packaging 16stored, the bottom of which also protects the underside of the optical element 1 from contamination. The optical element 1 is arranged in the protective packaging 16 in a receptacle such that the frame 2 is enclosed by the edge of the receptacle. The optical element 1 can be grasped by the tabs 6 of the protective film 4 arranged outside the receptacle and removed from the protective packaging 16.

[0028] In the following, the replacement of the optical element 1 is described using the example of a protective glass that is arranged in a laser processing head or in the connector of a fiber optic cable.

[0029] As in Fig. 5a shown, the frame 2 of the protective glass 1 is in the (only indicated) laser processing head 17 a laser machine through an elastic ring 18 force-locking in the housing 19held. To replace the protective glass 1, first the connection between a fiber optic cable (not shown) and the laser processing head 17 is disconnected. If the protective glass 1 is to be replaced, the dirty protective glass 1 is removed from the housing 19, for example using a lever tool. A new protective glass 1 is then removed from the protective packaging 16, with the covered side facing upwards so that no particles can fall onto the unprotected side of the protective glass 1. In doing so, the protective glass 1 is grasped with both hands by the two laterally projecting tabs 6 of the protective film 4. With the help of the protective film 4, the protective glass 1 is inserted into the housing 19 ( Fig. 5b ) and finally the protective film 4 is removed from the socket 2. The fiber optic cable can then be reconnected to the laser processing head 17.

[0030] As in Fig. 6 shown, the socket 2 of the protective glass 1 in the plug 20a fiber optic cable by means of two grub screws (not shown) which are inserted into an annular groove 21 on the circumference of the socket. To replace the protective glass 1, the grub screws on the plug 20 are loosened and then the socket 2 together with the protective glass 1 is removed from the plug 20, e.g. using an adhesive film. A new protective glass 1 is then removed from the protective packaging 16, with the covered side facing upwards so that no particles can fall onto the unprotected side of the protective glass 1. The protective glass 1 is grasped with one hand by a laterally projecting tab 6 of the protective film 4. With the help of the protective film 4, the protective glass 1 is inserted into the plug 20. Once the protective glass 1 is in the correct position, the socket 2 is fixed in the plug 20 using the grub screws and finally the protective film 4 is removed from the socket 2.

[0031] The advantage of the replacement described is that the protective film 4 is only removed from the protective glass 1 in the final step. This prevents particles from the ambient air from reaching the new protective glass 1.

Claims

1. An optical element (1) mounted in a holder (2), wherein the optical element (1) is a protective glass, a mirror, or a lens for a laser machining head or for a plug of a fiber optic cable, characterized in that, a side (3) of the optical element (1) is covered, at least partially, in particular completely, by a protective film (4), in particular a polyester film that is adhesively attached, via at least one adhesion surface (8), to an end face (5) of the holder (2), said end face surrounding the optical element (1), and that the protective film (4) comprises a lateral overhang (6) for handling the optical element (1) and for pulling off the protective film (4) from the holder (2), and that the side of the protective film (4) facing the optical element (1) is non-adhering at least in the region covering the optical element (1), and that the end face (5) of the holder (2) protrudes vertically above the covered side (3) of the optical element (1) such that contact of the protective film (4) with the optical element (1) is prevented.

2. The optical element according to claim 1, characterized in that, starting from the protruding end face (5), the holder (2) continuously extends inwardly up to the optical element (1), in particular conically or concavely.

3. The optical element according to claim 1 or 2, characterized in that the at least one adhesion surface (8), which in particular is silicone-based, can be removed from the holder (2) together with the protective film (4) when the protective film (4) is pulled off.

4. The optical element according to one of the preceding claims, characterized in that the protective film (4) comprises the at least one exposed adhesion surface (8) only in regions that lie against the end face (5) of the holder (2).

5. The optical element according to claim 4, characterized in that the protective film (4) comprises a local adhesion coating (7) forming the at least one exposed adhesion surface (8) only in regions that lie against the end face (5) of the holder (2).

6. The optical element according to claim 4, characterized in that the protective film (4) is formed by two film layers (9a, 9b) bonded together by means of an adhesion coating (7) located therebetween, wherein the adhesion coating (7) is covered, up to the at least one exposed adhesion surface (8), by the lower film layer (9b) facing the optical element (1), and in particular that the two film layers (9a, 9b) are formed by two film sections (13a, 13b) of an adhesion film provided with the adhesion coating (7) on one side, the two layers being folded onto one another, the adhesion sides of each lying against one another, wherein the lower film layer (9b) comprises at least one cut-out (10), by means of which the adhesion coating (7) is exposed as an adhesion surface (8).

7. The optical element according to one of the preceding claims, characterized in that the optical element (1) protrudes vertically above an adjacent inner edge (15) of the holder (2).

8. The optical element according to one of the preceding claims, characterized in that the lateral overhang of the protective film (4) is formed by one or more tabs (6).

9. The optical element according to one of the preceding claims, characterized by a protective package (16) surrounding the holder (2), the optical element (1) being arranged in said protective package such that it can be removed from the opened protective package (16) using the lateral overhang (6) of the protective film (4).