JPH09152519A - Optical fiber for laser beam transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and diameter of the overall-length range of an optical fiber for multiplexing and improve the economy of a laser beam transmission system by providing the projection optical system connection part of an optical fiber or the beam reception part of the optical fiber for multiplexing with a tapered fiber end part with gnarls. SOLUTION: The optical fiber is constituted by coating the periphery of a reflective coating part 12 with a coating part 13, and the tapered fiber end part 14 with gnarls is formed at the tip part and is connected to a projection optical head 16 by a connector part 15. Further, a converging lens 18 which converges a laser beam 17 is put in the projection optical head 16. Thus, the tip part of the optical fiber 11 is formed into the tapered fiber end part 14 with the boss and becomes wide toward the end, so the area rate of the beam diameter to the fiber exit diameter becomes small and even when the connector part 15 is made thin, sufficient cooling capability is obtained, so that the connector part 15 can be made small in sized and compact.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical fiber for transmitting a laser beam.

[0002]

2. Description of the Related Art In a conventional YAG laser welding head, for example, as shown in the longitudinal sectional view of FIG. 3, a tip of an optical fiber 31 whose base is connected to a laser oscillator is connected to a light emitting optical head 33 by a connector 32. Connected,
A laser beam 34 converged from a converging lens 35 in the emission optical head 33 is irradiated, and a straight quartz glass end face is exposed at the tip of the optical fiber 31. The molten glass is spun by a spinning method. It is formed into a uniform diameter of, for example, 1.0 mmφ which is gradually drawn by a roller. However, since the laser beam tends to spread at the tip of the connection of the optical fiber 31 to the emission optical head 33, and the heat generated by the beam emission is large, it is necessary to control the spread angle of the beam and the connector portion 32. It is necessary to thicken this portion for cooling, and therefore the structure of the connector portion 32 becomes large, which is an obstacle to automation and miniaturization.

Further, in a synthetic optical fiber for synthesizing laser beams transmitted by a plurality of optical fibers, it is necessary to make the fiber diameter on the synthetic optical fiber side a sum of the plural fiber diameters on the sending side. ,
Therefore, there is an inevitable increase in the size of the synthesizing optical fiber and an increase in the diameter of the synthesizing lens.

[0004]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above circumstances, and it is a combination of a single optical fiber for transmitting a laser beam, an outgoing optical system connecting portion, or a combination of a plurality of laser beams. It is an object of the present invention to provide an optical fiber for laser beam transmission, which can reduce the total length of the optical fiber for use in a laser beam and reduce the diameter of the optical fiber, thereby making the laser beam transmission system economical.

[0005]

To this end, the present invention provides a taper-shaped hump in the exit optical system connecting portion of a single optical fiber for transmitting a laser beam or the beam receiving portion of a combining optical fiber for combining a plurality of laser beams. It is characterized in that a fiber end is provided.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical fiber for transmitting a laser beam according to the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a first embodiment applied to a single optical fiber connected to an emission optical system. FIG. 7 is a front view of a second embodiment applied to a combining optical fiber that combines two laser beams. First, in the first embodiment of FIG. 1, the optical fiber 11 has a configuration in which a coating 13 is coated around a reflective coating 12, and a tapered humped fiber end 14 is formed at the tip. The tapered humped fiber end 14 is connected to the output optical head 16 by a connector 15. A converging lens 18 for converging the laser beam 17 is housed in the emitting optical head 16. As described above, since the tip of the optical fiber 11 is formed in the tapered humped fiber end 14 and has an unexpanded shape, the area ratio of the beam diameter to the fiber outlet diameter is small, and the connector portion 15 is thin. Even then, a sufficient cooling capacity can be obtained, so that the connector portion 15 can be made compact and compact.

Next, in the second embodiment of FIG. 2, the laser beams 23 and 24 transmitted by the two parallel optical fibers 21 and 22 are combined by a combining lens 25,
The synthetically converged beam 26 is received by the tapered, humped fiber end 27 of the synthetic optical fiber 28, which has the original divergent shape. In the conventional synthetic optical fiber 28, when the optical fibers 21 and 22 having a diameter of 1.0 mmφ were used, the diameter of the synthetic optical fiber 28 was 1.0 mmφ × 2 = 2.0 mmφ, but the tapered humped fiber end portion 27 was used. With the provision of 2.0, only the inlet of this tapered humped fiber end 27 is 2.0.
mmφ and the total length of the synthesizing optical fiber 28 may be 1.0 mmφ, which is the same as that of the sending optical fibers 21 and 22, and it is economical, and high output beam transmission is possible even if the fiber diameter is small. Further, naturally, the diameter of the synthesizing lens 25 can be reduced.

[0008]

In summary, according to the present invention, a tapered humped fiber end portion is provided at the exit optical system connecting portion of a single optical fiber for transmitting a laser beam or the beam receiving portion of a combining optical fiber for combining a plurality of laser beams. By providing the laser beam transmission system, it is possible to reduce the size and diameter of the output optical system connection part of a single optical fiber that transmits a laser beam or the total length of a synthetic optical fiber that synthesizes multiple laser beams, and to improve the economic efficiency of the laser beam transmission system. The present invention is extremely useful industrially because it can obtain an optical fiber for transmitting a laser beam.

[Brief description of the drawings]

FIG. 1 is a first example in which the laser beam transmission optical fiber of the present invention is applied to a single optical fiber connected to an emission optical system.
It is a longitudinal cross-sectional view of an embodiment.

FIG. 2 is a front view of a second embodiment applied to a combining optical fiber that combines two laser beams.

FIG. 3 is a vertical sectional view of a single optical fiber connected to a conventional output optical system.

[Explanation of symbols]

 11 Optical fiber 12 Reflective coating 13 Cover 14 Fiber end with tapered hump 15 Connector 16 Output optical head 17 Laser beam 18 Converging lens 21, 22 Optical fiber 23, 24 Laser beam 25 Synthetic lens 26 Synthetic beam 27 Taper Fiber end with hump 28 Optical fiber for synthesis

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hozumi Gota 5-717-1, Fukahori-cho, Nagasaki City Mitsubishi Heavy Industries Ltd. Nagasaki Research Institute

Claims (1)

[Claims] 1. A tapered humped fiber end portion is provided at a connecting portion of an emission optical system of a single optical fiber for transmitting a laser beam or a beam receiving portion of a combining optical fiber for combining a plurality of laser beams. Optical fiber for laser beam transmission.