BEAM GUIDANCE SYSTEM AND METHOD FOR THE TRANSMISSION OF LASER LIGHT

Abstract

A beam guidance system for the stable transmission of a polarization of laser light and a method for transmitting laser light are provided. The beam guidance system includes an optical fibre, a coupling device with an input and an output and a decoupling device for decoupling the laser light from the optical fibre.

Claims

1. A beam guidance system for the stable transmission of a polarization of laser light, the beam guidance system comprising: an optical fibre; a coupling device with an input and an output; and a decoupling device for decoupling the laser light from the optical fibre, wherein the polarized laser light is coupled into an optical fibre by means of the coupling device, the polarization of the laser light is controlled at the input of the optical fibre, and the optical fibre is a hollow core fibre.

2. A beam guidance system according to claim 1, wherein the beam guidance system further comprises a first converter for changing of the polarization of the laser light emerging from the optical fibre, the beam guidance system comprises a beam source and a second converter to change the polarization of the laser light, and the second converter is positioned between the beam source and the coupling device.

3. A beam guidance system according to claim 2, wherein the first converter and/or the second converter comprise a quarter wave plate.

4. A beam guidance system according to claim 2, wherein the first converter and/or the second converter comprise an electro-optical element.

5. A beam guidance system according to claim 1, wherein the laser light comprises short and/or ultra-short pulses with a pulse duration in the range of nanoseconds to femto seconds.

6. A beam guidance system according to claim 2, wherein the first converter for changing of the polarization of the laser light emerging from the optical fibre is positioned behind the decoupling device.

7. A beam guidance system according to claim 2, wherein a polarization direction of at least one of the first and second converters is adjustable.

8. A beam guidance system according to claim 1, wherein the decoupling device comprises a collimator.

9. A beam guidance system according to claim 2, wherein the beam guidance system comprises of a polarization beam splitter, which is positioned behind the first converter.

10. A beam guidance system according to claim 2, wherein at least one of the first and second converters, combined with the optical fibre, forms a optical fibre cable.

11. A method for the transmission of laser light comprising: providing polarized laser light; coupling the polarized laser light into an optical fibre using a coupling device; transporting the laser light using an optical fibre; decoupling the laser light from the optical fibre using a decoupling device; and changing the polarization of the laser light through a converter, wherein the optical fibre is a hollow core fibre.

12. A method according to claim 11, wherein polarized laser light is generated using a beam source and the polarization of the laser light is adjustable using a second converter, which is positioned between the beam source and the coupling device.

13. A method according to claim 11, wherein a selection of a polarization direction of the laser light is effected using a polarization beam splitter, which is positioned behind the first converter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Certain embodiments are described in more detail with reference to the following FIGURE:

[0067] FIG. 1 shows a schematic representation of certain embodiments of the beam guidance system.

DETAILED DESCRIPTION

[0068] FIG. 1 shows a schematic representation of certain embodiments of the beam guidance system. A beam source (12) is shown, which emits, for example, linearly polarized laser light as a first polarization. For the purposes of certain embodiments, it is preferred that the laser light emitted by the beam source (12) has a high degree of polarization so that it is referred to as essentially polarized in the sense of certain embodiments. The preferably essentially linearly polarized laser light is guided to a first converter (14) within the beam guidance system (10), wherein the light, which essentially has a first polarization, is converted by the first converter (14) to for example circular and/or elliptically polarized light as a second polarization. For example, the first converter (14) and the second converter (26) can be formed by a quarter-wave plate. In particular, the polarization direction of the laser light changes from first polarization to second polarization by a phase delay which occurs at the first converter (14).

[0069] After passing through the first converter (14), the laser light is coupled into an optical fibre (20) by means of a coupling device (16) in the context of certain embodiments shown in FIG. 1. This coupling preferably takes place in the front section (18) of the optical fibre (20), where moreover a monitoring of the polarization of the laser light takes place. For the purposes of certain embodiments, it is preferred if the optical fibre (20) is formed by a hollow core fibre. The use of the second converter (26), and in certain embodiments, a further converter (14) for converting polarization modes of laser light to be transmitted through an optical fibre (20) has proven particularly effective when the optical fibre (20) is moved and/or has a bend (30). The laser light to be transmitted is, for example, linearly polarized laser light, which is usually not suitable for being transported by hollow-core fibres, because an undesirable and uncontrolled change occurs in the polarization direction and the degree of polarization, particularly when the optical fibre (20) is moving and/or being bent (30). This is particularly disadvantageous because no constant polarization parameters of the laser light can be guaranteed due to these undesirable changes in the properties of the laser light to being transmitted, for example when used in dynamic applications. Through the transport of the laser light as preferably elliptical and/or circularly polarized laser light through the optical fibre (20), an unexpectedly stable polarization of the laser light is achieved, wherein performance losses of the laser light are surprisingly effectively avoided and/or reduced.

[0070] At the end (22) of the optical fibre (20), the laser light with the second polarization is decoupled from the optical fibre (20) by means of a decoupling device (24). The second polarization of the laser light is then converted into a third polarization by a second converter (26). For example, laser light, which is transported as essentially circular and/or elliptically polarized laser light through the optical fibre (20), can be converted by the second converter into essentially linearly polarized light, wherein the essentially circular and/or elliptically polarized laser light is the second polarization and the essentially linearly polarized light corresponds to the third polarization. This can preferably take place at the place of use (32) of the laser light, at which the laser light is used, for example, for processing workpieces or for treating patients. Advantageously, polarization of the laser light is monitored at the input (18) of the optical fibre (20).

[0071] In certain embodiments, it may be preferred to provide a polarization beam splitter (28) behind the second converter (26) in the vicinity of the application site (32), which allows a selection of the polarization direction of the laser light, a high extinction ratio can be provided.

REFERENCE LIST

[0072] 10 Beam guidance system [0073] 12 Beam source [0074] 14 first or further converter [0075] 16 Coupling device [0076] 18 Beginning or input of the optical fibre [0077] 20 Optical fibre [0078] 22 End or output of the optical fibre [0079] 24 decoupling device [0080] 26 (second) converter [0081] 28 Polarization beam splitter [0082] 30 bend in the optical fibre [0083] 32 Place of use of the laser light