阅读说明：本技术 用于从光导纤维耦合输出辐射的设备、光导线缆和加工头 (Device for coupling out radiation from an optical fiber, optical fiber cable and machining head ) 是由 R·胡贝尔 S·富克斯 M·海泽尔 J·黑尔斯特恩 D·迈尔 于 2018-06-04 设计创作，主要内容包括：本发明涉及一种用于从光导纤维(4)耦合输出辐射(2)的设备(1),其包括：壳体(14)以及遮光器(5),所述遮光器具有遮光器开口(6),所述遮光器开口用于将从所述光导纤维(4)的耦合输出侧端部(3)耦合输出的辐射(2)的耦合输出角(α)限制在相对于所述遮光器开口(6)的中轴线(9)的最大耦合输出角(α<Sub>M</Sub>)上,其中,所述遮光器(5)布置在所述壳体(14)中。所述遮光器(5)具有由透明材料制成的遮光器本体(8),其中,所述遮光器本体(8)具有第一全反射面(10),所述第一全反射面用于对以比所述最大耦合输出角(α<Sub>M</Sub>)更大的耦合输出角(α<Sub>G</Sub>)从所述光导纤维(4)的耦合输出侧端部(3)耦合输出的辐射(2)进行反射,其中,所述遮光器本体(8)具有第二全反射面(11),所述第二全反射面用于对与从所述耦合输出侧端部(3)耦合输出的辐射(2)反向地传播的、尤其从工件(22)反射回的辐射(15)进行反射。本发明也涉及一种光导线缆以及一种具有这样的设备(1)的加工头。(The invention relates to a device (1) for coupling out radiation (2) from an optical fiber (4), comprising a housing (14) and a shutter (5) having a shutter opening (6) for limiting a coupling-out angle (α) of the radiation (2) coupled out from a coupling-out-side end (3) of the optical fiber (4) to a maximum coupling-out angle (α) relative to a central axis (9) of the shutter opening (6) M ) Wherein the shutter (5) is arranged in the housing (14). The shutter (5) has a shutter body (8) made of a transparent material, wherein the shutter body (8) has a first total reflection surface (10) which is a reflective surfaceThe reflecting surface is used for comparing the maximum coupling-out angle (α) M ) Larger coupling-out angle (α) G ) The radiation (2) coupled out of the coupling-out end (3) of the optical fiber (4) is reflected, wherein the shutter body (8) has a second total reflection surface (11) for reflecting radiation (15) propagating in the opposite direction to the radiation (2) coupled out of the coupling-out end (3), in particular reflected back from a workpiece (22). The invention also relates to a light-conducting cable and to a machining head having such a device (1).)

1. A device (1, 1a) for coupling out radiation (2) from an optical fiber (4), comprising:

a housing (14);

a shutter (5) having a shutter opening (6) for limiting a coupling-out angle (α) of the radiation (2) coupled out of the coupling-out side end (3) of the optical fiber (4) to a maximum coupling-out angle (α) relative to a central axis (9) of the shutter opening (6)_M) Wherein the shutter (5) is arranged in the housing (14);

wherein the shutter (5) has a shutter body (8) made of a transparent material, wherein the shutter body (8) has a first total reflection surface (10), the first total reflection surface (10) being used for comparing the maximum coupling-out angle (α)_M) Larger coupling-out angle (α)_G) The radiation (2) coupled out of the coupling-out end (3) of the optical fiber (4) is reflected, wherein the shutter body (8) has a second total reflection surface (11) for reflecting radiation (15) propagating in the opposite direction to the radiation (2) coupled out of the coupling-out end (3), in particular reflected back from a workpiece (22).

2. The device according to claim 1, wherein the first total reflection surface (10) of the shutter body (8) forms a beam entrance surface for the counter-propagating radiation (15), wherein the second total reflection surface (11) of the shutter body (8) forms a beam entrance surface for the radiation (2) coupled out of the optical fiber (4).

3. The device according to claim 2, wherein the first and second total reflection surfaces (10, 11) adjoin each other at a tip (7) of the shutter body (8) delimiting the shutter opening (6).

4. The device according to claim 1, wherein the first total reflection surface (10) is arranged in front of the second total reflection surface (11) in the propagation direction (X) of the radiation (2) coupled out of the optical fiber (4).

5. Device according to claim 4, wherein the shutter body (8) has a first beam entry face (10a) opposite the first total reflection face (10) for the radiation (2) coupled out of the coupling-out end of the optical fiber (4) to be incident into the shutter body (8) and a second beam entry face (11a) opposite the second total reflection face (11) for the radiation (15) propagating in the opposite direction to be incident into the shutter body (8), wherein the first beam entry face (10a) and/or the second beam entry face (11a) preferably extend in a plane (E) perpendicular to the central axis (9) of the shutter opening (6).

6. The device according to claim 5, wherein the first total reflection surface (10) and the first beam incidence surface (10a) adjoin each other at a first tip (7a) of the shutter body (8), while the second total reflection surface (11) and the second beam incidence surface (11a) adjoin each other at a second tip (7b) of the shutter body (8).

7. A device according to any of the preceding claims, wherein the shutter body (8) has a first shutter part (8a) with a first total reflection surface (10) and a second shutter part (8b) with a second total reflection surface (11), wherein the two shutter parts (8a, 8b) preferably abut each other.

8. The device according to any one of claims 1 to 6, wherein the shutter body (8) is constructed in one piece.

9. The device according to any of the preceding claims, wherein the first and/or the second total reflection surface (10, 11) extends rotationally symmetrically with respect to a middle axis (9) of the shutter opening (6).

10. The device according to claim 9, wherein the first and/or the second total reflection surface (10, 11) form a conical surface.

11. The device according to claim 10, wherein the first total reflection surface (10) has a first angle (α) with respect to a plane (E) perpendicular to a middle axis (9) of the shutter opening (6)_T1) Between 10 ° and 40 °.

12. Apparatus according to claim 10 or 11, wherein the second total reflection surface (11) has a second angle (α) with respect to a plane (E, E1, E2) perpendicular to a central axis (9) of the shutter opening (6)_T2) Between 20 ° and 60 °.

13. The apparatus of any preceding claim, wherein the maximum coupled output angle (α)_M) Less than 20 °, preferably less than 10 °.

14. The device according to any of the preceding claims, wherein the shutter body (8) has at least one beam exit face (12, 12a, 12b) located radially outside with respect to a central axis (9) of the shutter opening (6) for causing radiation (2, 15) reflected on the first and/or second total reflection faces (10, 11) to exit the shutter body (8).

15. The apparatus of claim 14, wherein the beam exit face (12, 12a, 12b) is at least partially surrounded by an absorber (13) mounted in the housing (14).

16. The apparatus of claim 14 or 15, wherein the beam exit face (12) has a scattering effect on the radiation (2, 15) exiting through the beam exit face (12).

17. An optical cable (24) comprising a device (1a) according to any one of the preceding claims, wherein the housing forms a plug housing (14) of the optical cable (24) in which the coupling-out side end (3) of the optical fibre (4) is arranged at a predefined distance (A) from the shutter (5)₁，A₂)。

18. A processing head (17) for processing a workpiece (22), comprising an apparatus (1) according to one of claims 1 to 16, wherein the housing forms a processing head housing (14) having a plug receptacle (19) for receiving a plug (18) of a light-conducting cable (24), wherein the plug receptacle (19) is designed to place the coupling-out end (3) of the light-conducting fiber (4) at a predefined distance (a) from the shutter (5).

Technical Field

The invention relates to a device for coupling out radiation, in particular laser radiation, from an optical fiber. The invention also relates to a light-guide cable and a machining head with the device.

Background

The radiation, in particular in the form of laser radiation, generally exits divergently from the end of the optical fiber. In order to limit the divergence or coupling-out angle of the radiation coupled out from the end of the optical fibre, a shutter (blend) may be used. If the radiation coupled out from the optical fiber impinges on an obstacle, for example a workpiece to be machined, and is reflected back to the shutter, it is often not possible to easily receive or guide away the entire radiation reflected back in the region of the housing provided for this purpose. Thus, by means of the radiation reflected back, heating can occur and damage to the housing surrounding the coupling-out end of the optical fiber or the shutter or to components arranged in the housing can occur. In the case of the use of a shutter made of a metallic material, undesirable reflections can also occur at the shutter, which also heat the surrounding housing and do not enable precise cutting of the beam profile and therefore precise limitation of the coupled-out laser radiation to the maximum coupling-out angle.

DE 10033785 a1 discloses a device for coupling laser radiation into an optical fiber, wherein a prism-shaped shutter is arranged upstream of the coupling-in end of the optical fiber. The prism body has a first surface, from which a recess is provided in the prism body, and a second surface located on the side opposite to the first surface. The recess of the first surface is designed to extend sharply in the direction of the second surface in such a way that the laser radiation exiting substantially perpendicularly to the second surface and penetrating into the prism undergoes total internal reflection at the boundary surface between the prism and the recess. An opening for the passage of the laser radiation to be coupled in is provided between the recess and the second surface, and an optical fiber is arranged in the recess in the region of the opening.

Disclosure of Invention

The invention is based on the following tasks: a device for coupling out radiation from an optical fiber of the type mentioned at the outset is provided, in which undesired reflections at the shutter are prevented or at least reduced.

The object is achieved by a device of the type mentioned at the outset, comprising: a housing and a shutter having a shutter opening for limiting the coupling-out angle of the radiation coupled out from the coupling-out-side end of the optical fiber to a maximum coupling-out angle with respect to a center axis of the shutter opening, wherein a shutter is arranged in the housing, wherein the shutter has a shutter body made of a material that is transparent (to radiation guided in the optical fiber), wherein the shutter body has a first total reflection surface for reflecting radiation which is coupled out from the coupling-out side end of the optical fiber at a coupling-out angle which is greater than the coupling-out angle, the shutter body has a second total reflection surface for reflecting radiation propagating in the opposite direction to the radiation coupled out of the coupling-out end, in particular reflected back from the workpiece or another obstacle.

In principle, the device described here is also suitable for coupling radiation into the end of the optical fiber (in this case the input side). The radiation coupled out from the end of the optical fiber is in this case radiation that undesirably propagates counter to the coupling-in direction, the divergence of the radiation and the divergence of the coupled-in radiation being limited by the shutter.

The shutter according to the invention is made of a transparent material. The deflection of the radiation and thus the shutter effect is produced by total reflection at the respective total reflection surfaces of the shutter body. In order to generate total reflection, it is necessary for the radiation to exceed a limit angle (critical angle θ) for total reflection when it impinges on a total reflection surface, which is formed by the boundary surface of the shutter body with the surroundings_C) The limiting angle being through theta_C＝sin^-1(n_L/n_B) Is defined in which n is_BRefractive index, n, of the (optically dense) material representing the shutter body_LMeaning the (optically thinner) material (typically n) surrounding the shutter body_L1.0 air), maximum (desired) out-coupling angle α of radiation out-coupled from the end of the fiber optic_Gα is obtained from the distance A between the positions of the coupling-out ends of the optical fibers and the half diameter d/2 of the shutter opening_GTan (d/(2A)). for a given maximum coupling-out angle α_GThe angle at which the first or second total reflection surface is oriented relative to a plane perpendicular to the center axis of the shutter opening is determined to be variable depending on the position, such that α is greater than the maximum coupling-out angle_GThe coupling output angle of (1) satisfies the total reflection condition on the first total reflection surface.

Accordingly, the second total reflection surface can also be designed such that radiation which impinges on the opposite side of the shutter and propagates in the opposite direction is reflected at the second total reflection surface, said radiation being incident into the optical fiber at a coupling-in angle which is greater than the coupling-in angle corresponding to the maximum coupling-out angle, so that this part of the reflected radiation cannot be incident into the optical fiber. However, in the case of radiation reflected at obstacles, for example at a workpiece, the following problems may occur: the radiation reflected back has a lateral offset, so that, despite the shutter, it cannot be prevented if necessary: a small portion of the reflected radiation is incident on the fiber. However, the shutter acts in substantially the same manner in both directions.

In the device according to the invention, the shutter has a dual function, since it limits the coupling-out angle and thus the numerical aperture of the coupled-out radiation on the one hand and largely limits the coupling-in of the reflected radiation into the optical fiber on the other hand. Furthermore, since a shutter body made of a transparent material is used instead of a conventional shutter body made of a metallic material, undesired reflections can be reduced, since the radiation on the precisely produced total reflection surface is directed in a targeted manner to the outside to the surrounding housing or to an absorber arranged there. The shutter, or rather the shutter body, can be made of a high-performance material (for example quartz glass) which has only a relatively low absorption for the radiation passing through, even at high radiation powers or radiation intensities.

In one embodiment, the first total reflection surface of the shutter body forms a beam entrance surface for the radiation propagating in the opposite direction, and the second total reflection surface of the shutter body forms a beam entrance surface for the radiation coupled out of the optical fiber. The angle at which the radiation impinges on the respective total reflection surface acting as beam entry surface is selected such that the radiation, when it impinges on the shutter body, is only slightly refracted and impinges on the respectively different total reflection surface. In this way, the two total reflection surfaces of the shutter body perform a dual function in that they serve in one direction for the radiation to be incident into the shutter body and in the other direction as total reflection surfaces.

In one development of this embodiment, the first and second total reflection surfaces adjoin one another at the tip of the shutter body delimiting the shutter opening. In contrast to shutters made of metallic material, the shutter blades (blenenschneide) in the area of the shutter opening can extend very sharply in the case of the transparent shutter described here, since the absorption in the material of the shutter body is relatively low. In particular, the provision of a cylindrically configured shutter section, as described, for example, in the initially cited DE 10033785 a1, can be dispensed with. If desired, the tip can have a (small) rounding (Verrundung) with a radius of less than about 0.3 mm. The angle enclosed by the two total reflection surfaces with each other in the tip region of the shutter body may be, for example, about 80 ° or less. Furthermore, due to the tip in the region of the shutter opening, undesired reflections, which may be encountered, for example, in the case of metal shutters, can be avoided. In contrast, in the case of a metal shutter, a very sharp shutter piece may be damaged due to the high absorption of the shutter material.

In an alternative embodiment, the first total reflection surface is arranged upstream of the second total reflection surface in the propagation direction of the radiation coupled out of the optical fiber. In contrast to the embodiments described further above, in the case of the present embodiment, the beam path of the radiation coupled out from the coupling-out end of the optical fiber does not intersect the beam path of the radiation propagating in the opposite direction in the shutter body. In this way, compared to the case of the specific embodiment described further above, the degree of freedom is greater when selecting the angle of the beam entrance surface to a plane perpendicular to the center axis of the shutter, since the beam entrance surface does not act as a total reflection surface at the same time. However, if necessary, a part of the reflected radiation, which in the above-described embodiment would be shielded by the shutter body, cannot be shielded by the shutter body in this embodiment.

In one embodiment, the shutter body has a first beam entry surface opposite the first total reflection surface for the entry of radiation coupled out of the coupling-out end of the optical fiber into the shutter body and a second beam entry surface opposite the second total reflection surface for the entry of the radiation propagating in the opposite direction into the shutter body, wherein the first beam entry surface and/or the second beam entry surface preferably extend in a plane perpendicular to a center axis of the shutter opening. The two beam entry faces can optionally also be inclined at a not too large angle to a plane perpendicular to the central axis. However, it is to be ensured that the incident radiation is only slightly refracted at the respective beam entry surface before it strikes the respective total reflection surface and is reflected at this total reflection surface.

In one embodiment, the first total reflection surface and the first beam entrance surface adjoin one another at a first tip of the shutter body, and the second total reflection surface and the second beam entrance surface adjoin one another at a second tip of the shutter body. As has been described further above, in the case of a transparent shutter or in the present case two shutter plates with corresponding tips can be provided, on which the total reflection surfaces and the corresponding beam entry surfaces adjoin one another. As has been described further above, the tip can have a rounding with a radius of less than 0.3 mm. The two (circumferentially circumferential) tips usually limit the respectively different diameters of the shutter opening, which are coordinated with the respective distances to the exit-side end of the optical fiber in such a way that the outcoupled radiation is limited to the same maximum outcoupling angle at the two diameters.

In a further embodiment, the shutter body has a first shutter part with a first total reflection surface and a second shutter part with a second total reflection surface, wherein the two shutter parts preferably adjoin one another. In this case, the first shutter element can serve to shield radiation exiting from the coupling-out end of the optical fiber, while the second shutter element can serve to shield radiation propagating in the opposite direction, for example reflected on the workpiece. The two shutter parts can optionally be arranged at a distance from one another, but it has proven to be advantageous if the two shutter parts of the shutter body lie against one another in order to optimize the shutter effect in the reverse direction and in order to ensure that only a small amount of scattered light impinges on the second shutter part and is transmitted from the latter to the housing as scattered light.

In an alternative embodiment, the shutter body is constructed in one piece. This is advantageous in particular in the embodiments described further above, in which the total reflection surfaces simultaneously form the beam entry surface, since in the case of two-part or more-part embodiments of the shutter body, in this case additional boundary surfaces would be produced in the beam path between the beam entry surface and the total reflection surfaces, which could lead to undesired reflections when the radiation passes through.

In a further embodiment, the first total reflection surface and/or the second total reflection surface extend rotationally symmetrically with respect to a central axis of the shutter opening. In this case, generally, the entire shutter body is configured rotationally symmetrically with respect to the central axis. The production of the shutter body and the alignment of the shutter are simplified by the rotationally symmetrical implementation.

In one embodiment, the first total reflection surface and/or the second total reflection surface form a conical surface. The use of total reflection surfaces in the form of conical surfaces has proven to be particularly advantageous. In the embodiment described further above, in which the total reflection surface simultaneously forms the beam entrance surface, the shutter body is generally configured as a double cone, in which the conical surfaces are configured on opposite sides of the shutter body. In an embodiment in which the first total reflection surface is arranged in the beam path of the outcoupled radiation upstream of the second total reflection surface, the two conical surfaces face each other. In both cases, the total reflection surface may deviate from a conical shape and have a generally small curvature.

In a further embodiment, the first total reflection surface has a first angle of between 10 ° and 40 ° with respect to a plane perpendicular to a central axis of the shutter opening. The value of the first angle at which the first total reflection surface is oriented relative to a plane perpendicular to the central axis is predetermined by complying with the total reflection condition. The above-mentioned value ranges of the first angle are particularly applicable in the embodiments described further above, in which the total reflection surface simultaneously forms the beam entrance surface, wherein quartz glass is used as the material of the shutter body.

In a further embodiment, the second total reflection surface has a second angle of between 20 ° and 60 °, preferably between 10 ° and 45 °, with respect to a plane perpendicular to the central axis of the shutter opening. The value of the second angle is also particularly suitable for the embodiments described further above, in which the beam entrance face of the shutter body simultaneously forms a total reflection face, for example when quartz glass is used as the material of the shutter body.

In a further embodiment, the maximum coupling-out angle is less than 20 °, preferably less than 10 °, the numerical aperture NA. of the radiation emerging from the coupling-out end of the optical fiber is determined by the maximum coupling-out angle predefined by the shutter to be suitable for the Numerical Aperture (NA) in air, NA ═ sin (α)_M). Limiting the numerical aperture to a low value, e.g., about 0.125rad, or fixing the maximum coupled output angle to a low value, e.g., about 0.125rad, can achieve: the entire housing is prevented from being heated by radiation coupled out from the coupling-out end of the optical fiber.

In a further embodiment, the shutter body has at least one beam exit surface located radially outside with respect to a central axis of the shutter opening for the radiation reflected on the first total reflection surface and/or the second total reflection surface to exit from the shutter body. The beam exit surface is usually formed as a circumferentially encircling shutter edge which extends substantially parallel to the central axis. The beam exit surface can in particular form a cladding surface of a cylinder.

In one embodiment, the beam exit surface is at least partially surrounded by an absorber mounted in the housing. The absorber can, for example, surround the beam exit surface in a ring shape and be designed in the manner of a sleeve or the like. The radiation is deflected in a targeted manner by means of the total reflection surface in the direction of the absorber and converted into heat at the absorber. For this purpose, the absorber may be formed of a strongly absorbing material. The radiation emerging from the beam exit area may optionally not be absorbed at an absorber in the housing, but may be guided away from the housing in some other way, for example, in that the radiation emerging from the beam exit area is released to the surroundings on a transparent housing part.

Preferably, the beam exit face has a scattering effect on the radiation exiting through the beam exit face. In order to produce a scattering effect, the beam exit surface may be roughened, or scattering centers may be formed on the beam exit surface or in a volume region of the shutter body directly adjoining the beam exit surface. If the beam exit surface is designed as a scattering surface, the power of the exiting radiation can be distributed over a larger spatial angular range and in this way can be absorbed more easily by the surrounding absorber.

The invention also relates to an optical cable having a device as further described above, wherein the housing of the device forms a connector housing of the optical cable, in which connector housing the coupling-out end of the optical fibers is arranged at a predetermined distance from the shutter. The plug of the optical cable can be inserted into a plug receptacle of an optical component, for example a machined optical component. The coupling-out angle of the radiation emerging from the light-conducting cable is limited by means of a shutter, which is advantageous, for example, for subsequent collimation of the radiation in an optical component, for example in a machining head, since heating of the housing of the machining head due to radiation incident into said housing at an excessively large opening angle can be avoided or at least reduced.

A further aspect of the invention relates to a machining head for machining workpieces, wherein a housing of the device in which the shutter is arranged forms a machining head housing having a plug for receiving the optical fiber cable, wherein the plug receptacle is designed to place the coupling-out end of the optical fiber at a predetermined distance (lagerng) from the shutter. In the case of the machining head, the position of the coupling-out end of the optical fiber and thus the distance between the coupling-out end and the shutter in the propagation direction of the laser radiation or in the direction of the center axis of the shutter is predetermined by the plug receptacle, even if the plug is not yet inserted into the plug receptacle.

When machining a workpiece with (laser) radiation coupled out from the coupling-out end, the radiation is usually focused on the workpiece. A portion of the radiation impinging on the workpiece may be reflected from the workpiece back to the processing head. In particular, problems have proven to be problematic with regard to back reflection in the welding process of one workpiece or two workpiece parts to be joined along a fillet weld. In the case of this type of machining, the radiation can be reflected back in the direction of the machining head, laterally offset with respect to the optical axis. In this problematic case, the undesirable incidence of the reflected radiation into the optical fiber can also be largely avoided by means of the light shield described here.

Drawings

Further advantages of the invention emerge from the description and the drawings. The features mentioned above and those yet further listed can likewise be used by themselves, individually or in any combination of a plurality. The embodiments shown and described are not to be understood as exhaustive enumeration but rather have exemplary character for the description of the invention.

Fig. 1a, b show schematic cross-sectional views of an optical fiber and of a shutter made of transparent material for shielding laser radiation coupled out from the optical fiber and for shielding laser radiation propagating in opposite directions due to reflection of the laser radiation on two fully reflective surfaces;

fig. 2a, b are similar to the schematic views of fig. 1a, b, wherein the two total reflection surfaces of the shutter are formed on the sides of the two shutter parts facing each other;

fig. 3a shows a sectional view of a machining head for machining a workpiece, in the machining head housing of which the shutter of fig. 1a, b is mounted;

fig. 3b shows a diagram of the beam path during the welding process of a workpiece by means of the processing head of fig. 3 a;

fig. 4 shows a cross-sectional view of a light-conducting cable with a plug-in connector in which the shutter of fig. 2a, b is mounted.

In the following description of the figures, the same reference numerals are used for identical or functionally identical components.

Detailed Description

Fig. 1a, b show an exemplary configuration of a device 1 for coupling out laser radiation 2 from an output-side (end-side) end 3 of an optical fiber 4, in order to limit a coupling-out angle α of the divergent laser radiation 2 coupled out of the end 3 of the optical fiber 4 to a predefined maximum coupling-out angle α_MIn the above, the device 1 shown in fig. 1a, b has a shutter 5, the shutter 5, more precisely the shutter opening 6 thereof, which defines the (smallest) diameter d of the shutter 5, is arranged at a predefined distance a from the shutter opening 6, the distance a and the diameter d of the shutter opening 6 are according to the formula α_MThe maximum coupling-out angle α is defined as tan (d/(2A))_MAt said maximum coupled output angle α_MThe laser radiation 2 coupled out from the end 3 of the optical fibre 4 can then pass through the shutter opening 6 of the shutter 5 for the application described here, the maximum out-coupling angle α_MLess than about 20 deg. has proven advantageous.

Fig. 1a, b show a shutter 5, more precisely a shutter body 8 of the shutter 5, which is rotationally symmetrical with respect to a central axis 9 of the shutter opening 6. In the example shown, the shutter body 8 is made of a material transparent to the laser radiation 2. The transparent material may be, for example, quartz glass. The advantage of this material is that it has a low absorption for the laser radiation 2: the laser radiation may for example have a wavelength in the IR wavelength range or in the visible wavelength range of about 1.0 μm, and the material has a high resistance even at high laser powers. It will be appreciated that the shutter body 8, particularly in the case of other wavelengths of laser radiation 2, may be formed of other transparent materials than quartz glass.

In the example shown in fig. 1a, b, the shutter body 8 of the shutter 5 has two total reflection surfaces 10, 11 which extend rotationally symmetrically with respect to the central axis 9 and each form a conical surface. In the example shown, the shutter body 8 is constructed in one piece. In the example shown in fig. 1a, b, the two total reflection surfaces 10, 11 are formed on sides of the shutter body 5 facing away from one another, i.e. the shutter body 8 forms a (rotationally symmetrical) double cone. The two total reflection surfaces 10, 11 intersect at an annularly encircling tip 7 which delimits the shutter opening 6.

To prevent the output angle α from being greater than the maximum coupling angle_MGreater coupled output angle α_GThe laser radiation 2 emerging from the coupling-out end 3 in the optical fiber 4 passes through a shutter 5 and is provided with a first total reflection surface 10, which in the example shown is arranged behind a second total reflection surface 11 in the propagation direction X of the coupled-out laser radiation 2 at a maximum coupling-out angle α_MGreater coupled output angle α_GThe laser radiation 2 coupled out of the coupling-out end 3 of the optical fiber 2 is incident through the second total reflection surface 11 into the shutter body 8 and is refracted slightly here in the normal direction (see fig. 1 a.) as a result, the second total reflection surface 11 is formed at a greater maximum coupling-out angle α than the maximum coupling-out angle_MThe larger coupling-out angle is the beam entrance face of the laser radiation 2 coupled out of the optical fiber 4.

The laser radiation 2 reflected at the first total reflection surface 10 exits the shutter body 8 at a circumferential, cylindrical beam exit surface 12 located radially outside relative to the central axis 9. The beam exit surface 12 forms a circumferential outer edge of the shutter 5, which extends parallel to the central axis 9. The laser radiation 2 emerging from the shutter body 8 through the beam exit area 12 extends substantially perpendicularly to the center axis 9 and can therefore be absorbed by an absorber 13 which surrounds the shutter 5 in the region of the beam exit area 12 in an annular manner, said absorber 13 being fastened to a housing 14 of the device 1. Through the beam exit area 12, the laser radiation 2 shielded by the shutter 5 can be deflected in a targeted manner into the region of the absorber 13 and absorbed by said absorber. The beam exit area 12 can in particular form a scattering area for the laser radiation 2 deflected at the first total reflection area 10, so that said laser radiation can be better absorbed by the absorber 13. In order to function as a scattering surface, the beam exit surface 12 can be roughened or, if necessary, scattering centers can be embedded in the beam exit surface or in a volume of the shutter body 8 located below the beam exit surface.

As can be seen from fig. 1b, the shutter 5 also serves to protect the optical fiber 4 from the incidence of laser radiation 15, which propagates in the opposite direction to the laser radiation 2 emerging from the coupling-out end 3, into the coupling-out end 3. The laser radiation 15 that propagates substantially in the negative X direction of the XYZ coordinate system can be in particular a portion of the laser radiation 15 that is coupled out of the end 3 of the optical fiber 4 and is reflected back at an obstacle, for example at a workpiece.

Similarly to the case of US8,724,945B 2, a truncated cone-shaped stop block 16 made of quartz glass is joined (angelsleisst) to the end 3 of the optical fiber 4, from which the laser radiation 2 is coupled out. In contrast to that described in US8,724,945B 2, in the case of the device 1 shown in fig. 1a, B, the incidence of the reflected laser radiation 15 into the optical fiber 4 is not blocked by a termination block 16(Abschlussblock), but rather by: the reflected laser radiation 15 is reflected at the second total reflection surface 11 of the shutter body 8 in the direction of the beam exit surface 12 and is absorbed by the absorber 13, as is shown in fig. 1 b. It will be appreciated that additionally the termination block 16 is also constructed in the manner described in US8,724,945B 2 and may be provided with a relatively large opening angle.

In the example shown, the laser radiation 15 reflected back from an obstacle, for example a workpiece, impinges convergently on the side of the shutter 5 facing away from the optical fiber 4 (i.e. the rear side) and, in the example shown in fig. 1b, has a slight lateral offset with respect to the laser radiation 2 coupled out of the coupling-out end 3 of the optical fiber 4. A part of the reflected laser radiation 15 is incident into the shutter body 8 at a first total reflection surface 10, which serves as a beam entrance surface for the reflected laser radiation 15, is slightly refracted at the first total reflection surface 10 and impinges on a second total reflection surface 11, is totally reflected at the second total reflection surface to a beam exit surface 12, at which the reflected laser radiation 15 exits from the shutter body 8 and impinges on an absorber 13.

Shutter 5 and maximum coupling output angle α_MAre coordinated such that the maximum coupling output angle α is obtained_MGreater coupled output angle α_GThe laser radiation 2 impinging on the first total reflection surface 10 satisfies the total reflection condition. Approximately, a total reflection condition can be fulfilled in the diaphragm 5 shown in fig. 1a if the following applies:

wherein n is_L1.0 denotes the refractive index of (ambient) air, n_B1.46 denotes the refractive index of the silica glass material of the shutter body 8, α_T1Denotes a (first) angle enclosed by the first total reflection surface 10 and a plane E (YZ plane) perpendicular to the central axis 9, and α_T2Denotes the (second) angle enclosed by the second total reflection surface 11 and a plane E perpendicular to the central axis 9, for the first angle α_T1In the present example, a value between about 10 and about 40 has proven advantageous for the second angle α_T2Values between about 20 ° and about 60 ° or values between about 10 ° and about 45 ° have proven advantageous.

For the reflected radiation, i.e. for the maximum coupling-out angle α in a ratio to the central axis 8_MGreater angle α_GRadiation impinging on the shutter 5 in the opposite propagation direction, applies accordingly:

as an alternative to the device 1 shown in fig. 1a, b, a device 1a as shown in fig. 2a, b for coupling out laser radiation 2 from the coupling-out end 3 of the optical fiber 4 can also be used. The device 1a of fig. 2a, b differs from the device 1 of fig. 1a, b in the configuration of the shutter 5, more precisely of the shutter body 8, which has two shutter parts 8a, 8b made of quartz glass, which are each configured rotationally symmetrically with respect to the center axis. The two shutter members 8a, 8b abut each other on two flat faces in a plane perpendicular to the central axis 9 of the shutter 5. The two shutter members 8a, 8b can be connected to each other on a flat face, for example, in such a way that the two shutter members are bonded to each other. However, a material-locking connection between the two shutter parts 8a, 8b is not absolutely necessary, but it is also possible to accommodate the two shutter parts 8a, 8b in a common receptacle (fasung) in such a way that they are fixed in a position abutting against each other. Alternatively, it is also possible, in contrast to the illustration in fig. 2a, b, for the two shutter parts 8a, 8b to be arranged at a distance from one another.

In the light shield 5 shown in fig. 2a, b, the first total reflection surface 10 is arranged upstream of the second total reflection surface 11 in the propagation direction X of the coupled-out laser radiation 2 at a maximum coupling-out angle α_MGreater coupled output angle α_GThe laser radiation 2 emerging from the optical fiber 4 passes through the first beam entry face 10a and is incident on the shutter body 8, specifically on the shutter part 8 a. The first beam entrance surface 10a is in a plane E perpendicular to the central axis 9 of the shutter 5₁And opposite the first total reflection surface 10, said first total reflection surface 10 being opposite the plane E₁Or at an angle α with respect to the first beam entrance face 10a_T1As shown in fig. 2a, at greater than maximum coupled-out angle α_MCoupled output corner α_GThe laser radiation 2 incident in the first shutter part 8a is reflected at the first total reflection surface 10 and exits the first shutter part 8a via a cylindrical beam exit surface 12a and is absorbed by an absorber 13.

Accordingly, the reflected laser radiation 15 is incident on the second shutter part 8b on a flat beam entry surface 11a, which extends in the plane E2 with respect to the center axis 9 of the shutter 5, on the second shutter part 8b and is reflected on a second total reflection surface 11, which is at a (second) angle α, to a radially outer beam exit surface 12b of the second shutter part 8b and is absorbed by the absorber 13 after exiting from the shutter body 8, and is reflected on the second total reflection surface 11_T2Inclined with respect to the beam incident surface 11aAnd (5) inclining.

The first total reflection surface 10 and a plane E perpendicular to the central axis 9₁A first corner α_T1And the second total reflection surface 11 and a plane E perpendicular to the central axis 9₂Enclosed second angle α_T2In the shutter 5 shown in fig. 2a, b is substantially of the same order of magnitude as in the shutter 5 shown in fig. 1a, b, i.e. between about 20 ° and about 60 °.

The first conical total reflection surface 10 and the first beam incidence surface 10a adjoin each other at the first tip 7a of the first shutter member 8a, and the second conical total reflection surface 11 and the second beam incidence surface 11a adjoin each other at the second tip 7b of the second shutter member 8 b. The shutter 5 in fig. 2a, b is thus configured like the shutter 5 shown in fig. 1a, b in the form of a double cone, with the difference that in fig. 2a, b two total reflection surfaces 10, 11 are configured on two flat cone-shaped shutter parts 8a, 8b and face each other, while in the shutter body 8 of fig. 1a, b the two total reflection surfaces 10, 11 face away from each other. The shutter 5 shown in fig. 2a, b does not necessarily have to have two shutter parts 8a, 8b, but can be constructed if necessary in one piece, but this makes the manufacture of the shutter 5 more expensive.

The tip 7a of the first shutter member 8a limits the minimum diameter d of the shutter opening 6 on the first shutter member 8a₁. The tip 7b of the second shutter member 8b limits the minimum diameter d of the shutter opening 6 on the second shutter member 8b₂. The spacing A of the first tip 7a of the first shutter member 8a from the end 3 of the optical fiber 4₁A distance A between the tip 7b of the second shutter member 8b and the end 3 of the optical fiber 4₂And two minimum diameters d of the shutter opening 6 at the two tips 7a, 7b₁And d₂Are matched to one another in such a way that the coupling-out angle α of the coupled-out laser radiation 2 passing through the shutter 5 is limited to the same maximum coupling-out angle α at both tips 7a, 7b_MThe above. This also enables a shutter effect for the reflected laser radiation.

The device 1 shown in fig. 1a, b or fig. 2a, b can be used in different optical devices, for example in the following: in the optical component, the laser radiation 2 coupled out of the end 3 of the optical fiber 4 is collimated after the shutter 5.

Fig. 3a shows a machining head 17 with the device 1 according to fig. 1a, b. In the example shown, the machining head 17 is used for welding machining a workpiece 22 shown in fig. 3 b. In this case, the housing for accommodating the shutter 5 forms the processing head housing 14 of the (laser) processing head 17.

The machining head housing 14 has a plug receptacle 19, in which a plug 18 of a light-conducting cable 24 is received in the machining head 17 shown in fig. 3 a. The optical fiber cable 24 with the protective covering for protecting the optical fiber 4 is connected at the entry-side end, not illustrated in fig. 3a, to a laser source for generating the laser radiation 2. The coupling-out end 3 of the optical fiber 4 is fixed in a connector 18 of an optical cable 24, which is placed in a connector receptacle 19 of the machining head housing 14 and is thus fixed in its position relative to the machining head housing 14. In order to receive the coupling-out end 3 of the optical fiber 4, the processing head housing 14, more precisely the plug receptacle 19 of the processing head housing 14, is therefore designed at a predetermined distance a from the light shield 5 fixed in the processing head housing 14.

At greater than maximum coupled output angle α_MIs shielded by the shutter 5 in the machining head 17 shown in fig. 3a, so that no laser radiation 2 is emitted outside the absorber 13 onto the machining head housing 14, the laser radiation 2 coupled out being coupled out at the coupling-out end 3 of the optical fiber 4, so that the laser radiation 2 coupled out is at the desired maximum opening angle or maximum coupling-out angle α_MPasses through the shutter opening 6 and impinges on the collimator lens 20. The coupled-out laser radiation 2 is collimated on a collimator lens 20 and is subsequently focused by a focusing lens 21, which is also arranged in the machining head 17, on a workpiece 22 shown in fig. 3 b.

In the example shown, two workpiece parts which abut one another at right angles at the edges (aneinander sto β en) are welded to one another by means of the focused laser radiation 2 emerging from the machining head 17 along a so-called fillet weld, the welding region 23 during the laser beam welding of the workpiece 22 is indicated in fig. 3b by a dashed circle, as can also be seen in fig. 3b, a part of the coupled-out laser radiation 2 is reflected twice by about 90 ° in the region of the fillet weld on the workpiece 22, so that the laser radiation 2 which impinges on the workpiece 22 is deflected in total by about 180 °, the laser radiation 15 which is reflected back from the workpiece 22 has a lateral offset relative to the laser radiation 2 which impinges on the workpiece 22, the reflected laser radiation 15 is collimated on the focusing lens 21 and focused on the collimating lens 20 during passage through the machining head 17 in the opposite direction, so that it impinges on the rear side of the shutter 5 in a converging and laterally offset manner, as illustrated in fig. 1 b.

Fig. 4 shows an example in which, in contrast to fig. 3a, b, the device 1a of fig. 2a, b is integrated into an optical cable 24, more precisely into a plug-in connector 18 of the optical cable 24, which is used to connect the optical cable 24 with a machining head or other optical means. In contrast to the illustration in fig. 3a, b, in this case the light barrier 5 is integrated into the connector 18 or into the connector housing 14, and the exit-side end 3 of the optical fiber 4 is placed in the connector housing 14 at a predetermined distance a1 from the front side of the light barrier 5 and at a predetermined distance a2 from the rear side of the light barrier 5. The coupled-out laser radiation 2 exits the connector 18 through an optional flat protective glass 25. As already indicated above, in the shutter 5 shown in fig. 4, the two shutter parts 8a, 8b can be arranged, if appropriate, at a distance from one another.

In summary, in the device 1, 1a further illustrated above, back reflections that would occur when using shutters made of metallic material are avoided by using the transparent material of the shutter body 8. Further, the shutter 5 further described above can also realize: the radiation from both propagation directions is shielded without a plurality of components being compulsorily required for this purpose. Furthermore, no or only a small amount of absorption occurs in the shutter body 8 itself, so that deformation and damage at the shutter 5 due to heating of the material of the shutter body 8 by the laser radiation 2, 15 can be prevented. It will be appreciated that the shutter 5 shown in fig. 1a, b may also be integrated in the machining head 17 shown in fig. 3 a. Accordingly, the light shield 5 shown in fig. 2a, b can also be integrated into the connector 18 of the optical fiber 24 shown in fig. 4.