ULTRA-SHORT PULSE LASER LIGHT GUIDE CABLE

Abstract

A hollow body for light guide cable for ultrashort pulse laser, which is characterized by a spherical shape and a bore for the insertion of an light guide fiber. Hollow body and hollow core fiber can be evacuated prior to bonding and/or filled with a gas at a defined pressure. The two hollow bodies are gas-tightly connected to the optical fiber.

Claims

1. An end cap for light guide cable for ultrashort pulse laser, wherein the at least one end cap is an optical element with at least one curved optical surface.

2. The end cap of claim 1, wherein the radius of curvature of the curved optical surface consists of a partial sphere, wherein the spherical surface is limited at least to the curved optical surface.

3. The end cap of claim 1, wherein the radius of curvature corresponds to a meniscus lens whose respective surface comprises at least the curved optical surface.

4. The end cap of claim 1, wherein the radius of curvature of the curved optical surface is in a range between 2 mm to 30 cm.

5. The end cap of claim 1, wherein the wall thickness of the curved optical surface may be in a range between 0.3 mm to 3 mm.

6. The end cap of claim 1, wherein the curved optical surface consists of an optically transparent material.

7. The end cap of claim 6, wherein the optically transparent material may be quartz glass.

8. A light guide cable for ultra-short pulsed laser, which consists over its entire course of a hollow core fiber and the hollow core is filled with a gas at a defined pressure, and the two ends of the light guide cable are sealed gas-tight by an end cap according to claim 1.

9. The light guide cable of claim 8, wherein the end of the hollow-core fiber is arranged in the center of the circle, which is defined by the radius of the curved optical surface or is arranged on the radius of the circle between the center of the circle and its circumference.

10. The light guide cable of claim 8, wherein end caps have at both ends different radii at the respective curvatures and/or different wall thicknesses of the curved optical surfaces.

11. The light guide cable of claim 8, wherein end caps have at both ends the same radii at the respective curvatures and/or different wall thicknesses of the curved optical surfaces.

12. The light guide cable of claim 8, wherein the end caps at both ends have the same radii at the respective curvatures and/or different wall thicknesses of the curved optical surfaces.

13. A manufacturing method for a light guide cable for ultrashort pulse laser, as described above, comprising the steps; a. providing a hollow core fiber; b. providing two end caps according to claim 1 for each end of the hollow core fiber; and c. gas tight connection of the end caps to the ends of a hollow core fiber.

14. The method of claim 13 wherein the end of the hollow core fiber is arranged in the center of the circle, which is defined by the radius of curvature of the curved optical surface of the end cap or is arranged on the radius of the circle between the center of the circle and its circumference.

15. A method of claim 13, wherein the end caps and the hollow core fiber are evacuated and/or filled with a gas at a defined pressure before joining.

16. The method according to claim 13, wherein end caps and hollow core fiber are connected in an evacuated space.

17. A method of use of an end cap of claim 1 in the laser material processing with an ultrashort pulse laser.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0035] The invention will now be described on the basis of the drawings. It will be understood that the embodiments and aspects of the invention described herein are only examples and do not limit the protective scope of the claims in any way. The invention is defined by the claims and their equivalents. It will be understood that features of one aspect or embodiment of the invention can be combined with a feature of a different aspect or aspects and/or embodiments of the invention. It shows:

[0036] FIG. 1 is a representation of a spherical optical element in the input/output plane.

[0037] FIG. 2 is a representation of an optical element in which the input/output surface is designed spherically.

[0038] FIG. 3 is a representation of an optical element in which the coupling/decoupling surface is designed as a spherical meniscus lens.

[0039] FIG. 4 is a wavefront error plane coupling surface (top), meniscus-shaped coupling surface (lying on the axis) and spherical coupling surface (bottom).

[0040] FIG. 5 is a wavefront error plane coupling surface.

[0041] FIG. 6 is a wavefront error spherical coupling surface.

[0042] FIG. 7 is a wavefront error meniscus lens-shaped coupling surface.

DETAILED DESCRIPTION OF THE INVENTION

[0043] The invention will now be described on the basis of the drawings. It will be understood that the embodiments and aspects of the invention described herein are only examples and do not limit the protective scope of the claims in any way. The invention is defined by the claims and their equivalents. It will be understood that features of one aspect or embodiment of the invention can be combined with a feature of a different aspect or aspects and/or embodiments of the invention.

[0044] The present invention provides a light guide cable for ultra-short pulse laser available, which consists over its entire course of a hollow core fiber and end caps and the hollow core and the end caps are filled with a gas at a defined pressure, and the two ends of the optical cable are sealed gas-tight by first and second end cap.

[0045] When optimum transmission conditions for ultrashort pulse lasers are known, the essential advantage of the present invention is that the optical fiber cable does not have to be permanently evacuated or filled. Monitoring the gas pressure is also redundant. Rather, the invention makes use of the fact that both the medium for filling the hollow core fiber and the required pressure can be set in relation to the desired transmission properties. This makes it possible to produce preconfigured light guide cables, in which the design complexity is reduced in their use.

[0046] If the pressure drops in gas-filled cables from the prior art, a burning of the optical fiber cable results, so that the production process has to be interrupted, because the cable must be replaced. In addition to the replacement, a new light guide cable from the prior art has to be evacuated and possibly refilled with a gas. Subsequently, the pressure in the hollow core of the optical fiber must be adjusted again as required for the respective production process. All these measures are accompanied by a long production stoppage.

[0047] In addition to the higher process reliability, optical fiber cables according to the present invention also offer the same and constant properties in laser beam transmission. The adjustment can be made prior to the use of the optical fiber cable, so that the production process is independent of this process.

[0048] The risk of light guide cable contamination during monitoring and calibration during the ongoing production process is also reduced through the use of cables that can be preconfigured under clean room conditions.

[0049] FIG. 1 shows the connection of an optical element 1 which is spherical in the input and outcoupling plane with a hollow core fiber 2 as an optical fiber. The joints 3 serve to seal the construct.

[0050] FIG. 2 shows the connection of a cylindrical optical element 4 with a spherical input and output surface 1 and with a hollow core fiber 2 as an optical fiber. The connection points 3 serve to seal the construct.

[0051] FIG. 3 shows the connection of a cylindrical optical element 4 with a spherical input and outcoupling surface (meniscus lens) 5 and with a hollow core fiber 2 as an optical fiber. The joints 3 serve to seal the construct.

[0052] From the results illustrated in FIGS. 4-7, provided that the optimum transmission conditions for ultra-short pulse laser are known, the advantage of the described invention is that the wavefront distortions can be miniaturized by a factor of about 70 by the special shaping of the end cap, which improves the imaging properties and minimizes pulse expansion compared to a planar substrate. This effect is obvious when taking a look to the attached simulation in FIGS. 5-7.

[0053] Another advantage of the invention is that the light guide cable does not have to be permanently evacuated or filled, allowing a durable efficient use. Monitoring the gas pressure is also superfluous. Rather, the invention makes use of the fact that both the medium for filling the hollow core fiber and the required pressure can be set in relation to the desired transmission properties. This makes it possible to produce preconfigured light guide cables, in which the design complexity is reduced in their use.

[0054] The invention relates to a hollow body for optical fiber cable for ultrashort pulse laser, which is characterized by a spherical shape and a hole for inserting an light guide fiber. Hollow body and light guide fiber can be evacuated prior to bonding and/or filled with a gas at a defined pressure. The two hollow bodies are gas-tightly connected to the optical fiber. The connection can be made in an evacuated room.

[0055] The foregoing description of the preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiment was chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. The entirety of each of the aforementioned documents is incorporated by reference herein.

REFERENCE NUMERALS

[0056] 1 spherical optical element, end cap [0057] 2 hollow core fiber [0058] 3 joints [0059] 4 cylindrical optical element [0060] 5 meniscus lens