JPS6032653Y2 - Laser light transmission equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser beam transmission device that protects a cladding portion of an optical fiber from laser beams.

Generally, the cross section of an optical fiber (optical fiber) has a core part 1 made of quartz glass in the center, which is surrounded by a cladding part 2 made of silicone resin, and then the cladding part 2 is covered with a nylon covering 3.

By the way, when transmitting a laser beam for laser processing using this optical fiber, the transmission of the laser beam is
Therefore, it is necessary to condense the laser beam to the diameter of the core portion 1 using a condensing optical system, such as a lens.

When a laser beam is focused by a lens, it has a Gaussian intensity distribution on its focal plane, and the focusing diameter d is expressed as a diameter of 1/e, and the focusing diameter d, the spread angle θ of the laser beam, and the lens The relationship with the focal length f is expressed as d=fθ.

For example, when condensing a laser beam of θ=0.75 yn, rad onto an optical fiber with a core diameter of 0.15 mm, if the minimum condensing diameter d=0.15 mm, then f=2−, and the focal length is 2 It is sufficient to use a lens with -.

However, as mentioned above, since the intensity distribution is Gaussian at the focal plane, about 87% of the laser light output from the laser oscillation device is incident on the core part 1, and the remaining 13% of the energy is The area around the core part 1 is irradiated.

Incidentally, it has been demonstrated that a low-loss silica glass fiber has a transmission energy capacity of about 1 Cf3 W/d.

Now, if the laser beam is focused with a pulse width of 1 ms and an energy of 2 joules, the intensity (power density) of the laser beam at the laser beam incident end face of the core part 1 is approximately 107 W/C7+
! The quartz core itself can withstand such light condensing conditions.

However, if the core part 1 is a silica glass fiber,
Silicone resin is used for the cladding part 2 covering the core part 1, and the number of positions where this silicone resin is not damaged by laser light is about 10'W/d.

However, under the laser condensing conditions described above, 1
The cladding portion 2 will be damaged by the irradiation with a laser beam of about σ to 1σW/c11.

If the cladding portion 2 is damaged, the quartz core itself is deformed, resulting in poor transmission of laser light, or in some cases, no transmission at all.

The present invention has been developed in view of the above circumstances, and includes a protective member that protects the cladding part of the optical fiber from the laser beam at the tip of the optical fiber that transmits the laser beam, and the cladding part protects the cladding part from the laser beam. It is an object of the present invention to provide a laser beam transmission device that will not be damaged by laser beams and the transmission of laser beams will not be inhibited.

An embodiment of the present invention will be specifically described below with reference to FIGS. 2 and 3.

In the figure, reference numeral 10 denotes a laser generator, and a processing laser beam outputted from the laser generator 10 is focused through a lens 11 and made to enter the core portion 22 of an optical fiber 21.

At the input end of the optical fiber 21, a predetermined length of the cladding part 23 and the nylon covering part 24 are removed to expose the core part 22.

A cladding portion 2 is provided at the input end of the optical fiber 21.
Dispersion jig 2 as a protective member that protects 3 from laser light
0 is set.

This dispersion jig 20 is made of quartz glass or a transparent material that hardly absorbs laser light, and has a concave portion 20a in the shape of a mortar on its upper surface.

Further, the dispersion jig 20 is placed in the center of the recess 20a.
A through hole 20b is drilled through the through hole 20b.
The core portion 22 of the optical fiber 21 is inserted into the core portion 22 of the optical fiber 21.
The laser beam incident end face 22a of the laser beam incident end face 22a is made to coincide with the bottom of the recess 20a.

Further, the tip of the cladding portion 23 is located on the lower surface of the dispersion jig 20.

With such a structure, approximately 13% of the laser light that is not incident on the laser light incident end face 22a of the core portion 22 enters the dispersion jig 20 through the concave portion 20a, and the refraction effect of the dispersion jig 20 It is dispersed as shown by the chain line.

Therefore, the energy density of the laser beam near the cladding part 23 is significantly reduced, and even if the cladding part 23 is irradiated with the laser beam, it will not be damaged.

Further, since the dispersion jig 20 is made of a transparent material and is not absorbed and heated by laser light, the dispersion jig 20 itself will not be damaged.

Furthermore, since the dispersion jig 20 is made of a glass material such as quartz glass, it can be easily manufactured using conventional processing techniques.

In addition, other embodiments of the dispersion jig 20 are shown in FIGS. 4 to 7.

FIG. 4 shows a dispersion jig 30 in which the upper end surface is treated to have a ground glass shape to diffuse the laser beam, and FIG. 5 shows a dispersion jig 31 in which the center part is shaped like a concave lens. FIG. 6 shows a dispersion jig 32 with slit-shaped recesses 32a and 32b provided on the upper and lower end surfaces, and FIG. Insertion hole 20b
The inner diameter of the optical fiber 21 is made slightly smaller than the outer diameter of the core portion 22, and the optical fiber 21 is disposed directly below the through hole 20b with the tips of the core portion 22 and the cladding portion 23 flush with each other.

As described above, the present invention provides the following advantages:
Since a protective member is provided to disperse the laser beam that has deviated from the core of this optical fiber, the laser beam that has deviated from the core will intensively irradiate a small area of the cladding, damaging the cladding and causing the laser beam to There is no possibility that the transmission cannot be performed properly.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an optical fiber, Fig. 2 is a schematic diagram showing an embodiment of the present invention, Fig. 3 is a sectional view showing a dispersion jig of the same embodiment, and Figs. 4 to 7 are a dispersion jig. FIG. 3 is a sectional view showing another embodiment of the invention. 10... Laser generator, 11... Lens, 20.30, 31, 32... Dispersion jig (
protective member), 22... core part, 23...
・Clad part.

Claims (1)

[Scope of utility model registration request] In devices that condense laser light output from a laser device with a lens and transmit it by entering the core of an optical fiber,
A laser beam transmission device characterized in that a protection member is provided at the input end of the optical fiber to disperse the laser beam that has deviated from the core portion.