JPS60211990A - Laser oscillator - Google Patents

Abstract

PURPOSE:To obtain linearly polarized laser light as well as the uniform and stable laser cutting property by changing this linearly polarized light to circularly polarized laser light using a phase retarder, by a method wherein a metal grating composed from metal thin lines is provided between a total reflecting mirror and a partly transmitting mirror. CONSTITUTION:A metal grating 6 is secured to a base stand 8 having a hole 9 to pass laser light, thin metal lines 7 being adhered or welded to said base stand, and linearly polarized laser light 5a is generated through the metal grating 6. In the laser cutting, it is asked to output stable circularly polarized laser light to obtain work pieces having uniform cutting property. For this purpose, the generation of linearly polarized laser light is desirable for a laser oscillator, and an adequate polarizing element is provided in the laser oscillating cavity. Accordingly, the metal grating 6 which is composed of, for instance, thin gold line reflecting laser light is provided at the partly transmitting mirror 4 side. Since this metal grating 6 has the characteristics that the attenuation is most few when laser light which has polarized light in the direction right-angled to the grating passes through, laser oscillation will have polarized light in the direction right-angled to the metal grating 6, and linearly polarized laser light 5a can be generated.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to the configuration of a single laser oscillator that produces linearly polarized laser oscillation and circularly polarized laser light. [Prior Art] Conventionally, this type of laser oscillator Is the oscillator shown in Figure 1 r
In the knee diagram, (1) is a vacuum vessel, (2) is a laser medium, (3) is a total reflection mirror, (4) is a partially transmission mirror, and (5) is a laser beam. The total reflection mirror (3) and the partial transmission mirror (4) are arranged facing each other on the optical axis of the laser beam (5). Next, we will explain the operation of the laser medium (
When 2) is excited by an electric discharge or a full-resistance mirror, laser oscillation occurs between the total reflection mirror (3) and the partially transmitting mirror (4), and a laser beam (5) is output from the partially transmitting mirror (4). .

Since the conventional laser oscillator is constructed as described above, there is no one-and-done means for determining the polarization direction of the laser beam (5), and the polarization direction is unstable.

When cutting metals, especially ferrous metals, with this T-cut laser, the cutting performance differs depending on the cutting direction, so the cutting surface becomes slanted, and the workpiece is cut out of the material after the first cut. [Summary of the Invention] This invention eliminates the drawbacks of the conventional products as described above.
This invention provides a laser oscillator that can obtain linearly polarized laser light by providing a metal grating made of thin metal wires between a total reflection mirror and a partially transmission mirror. The purpose is to obtain uniform and stable single-polarity laser cutting characteristics by converting the linearly polarized laser beam obtained above into a circularly polarized laser beam using a phase retarder. [Embodiments of the invention] The following , an embodiment of the first invention is illustrated in FIGS. 2 and 3. In the figures, (1) to (4) are exactly the same as the conventional oscillator described above. , <6) is the 8th
As shown in the figure, there is one hole (9 holes) through which the laser beam passes.
), and a thin metal wire (7) is fixed to the base (8) by gluing or welding, and a metal grid is formed. In laser cutting, which uses a linearly polarized laser beam, it is necessary to output a stable single-circularly polarized laser beam in order to obtain a one-stroke loe material with uniform cutting characteristics. It is desirable for the laser oscillator to generate a linearly polarized laser beam, and for this it is necessary to provide an appropriate polarizing element in the laser oscillation cavity.From the above, it is clear that the metal 1 that reflects the laser beam, e.g. A metal grating (6) made of thin gold wires is provided on the side of the partially transmitting mirror (4) as shown in Figure 2, so that this metal grating (6) can absorb laser light with polarization perpendicular to the grating. The first laser oscillation, which has the characteristic of having the least attenuation when it passes through, has polarization perpendicular to the metal grating (6), and the related polarized laser light (5a)
The above metal lattice (6
) The diameter of the thin gold wire (7) used in the wire (7) should be closer to the wavelength of the laser beam, but if it is less than about 0.1 μ, it will not increase the loss even if it is inserted into the laser oscillator. The closer the distance between the thin lines (7) to the wavelength of the laser light, the thicker the effect.
Therefore, it is ideal to provide as many thin wires (7) as possible as long as the above conditions are satisfied.In addition, in the above embodiment, the metal grid (6) is provided on the partially transmitting mirror (4) side. It goes without saying that between the total reflection mirror (3) and the partial transmission mirror (4), the desired purpose can be achieved no matter where it is placed. (7) is made of gold, and the same effect can be expected even if the material is gold IM that reflects laser light, such as copper, tanksten, molyftene, or aluminum. It is said that the closer the spacing of 7) is to the wavelength of the laser beam, the better, but it is effective even if it is widened.Wouldn't it be ideal to have as many thin lines (7) as shown in Figure 3? It is possible to output even one to several linearly polarized laser beams (5a), and by changing the direction of the metal grating (6), laser oscillation can produce blood-related polarized light in any direction even in this state. Can you get it?

Next, an embodiment of the second invention will be explained with reference to FIGS. 4 and 5. In the figure, (1) to (4), (5B).

(6) to (9) are exactly the same as the device of the first invention. The T-column and metal grating (6) are disposed in the propagation path of the laser light, and the one-phase retarder (1(I) The grating is provided so that the angle of the grating is 45° with respect to the inclination of the laser beam, as shown in FIG. , metal grid (
6) is provided at an angle of 45°, and except for 1, it is completely the same as the first invention.

As mentioned above, the total reflection mirror (3) and the partial transmission mirror (4)
The laser beam is oscillated by the metal grating (6) between Ef and keratin, and becomes a linearly polarized laser beam (5a), which is output from the partially transmitting mirror (4). 5a) is arranged in the propagation path of the laser beam, and by setting the angle of the metal grating (6) to 45° with respect to the inclination of the phase retarder αO as shown in FIG. It goes without saying that the closer the angle of the metal grating (6) is to 45°, the closer to optimal circularly polarized laser light can be obtained.

〔Effect of the invention〕

As mentioned above, the present invention rarely requires a single element that generates linearly polarized light within the laser oscillation cavity, that is, a thin metal wire located somewhere between the total reflection mirror and the partial transmission mirror.
By providing this metal grating, it is possible to obtain a stable and linearly polarized laser beam.In addition, a phase retarder is placed in the propagation path of the laser beam, and the inclination of this phase retarder is and set the angle of the above metal grid to 45°1
At this point, the laser beam reflected by the phase retarder t'1T is converted into a circularly polarized laser beam. In cutting with this circularly polarized laser beam, especially in the case of iron-based metals, there is no difference in sharpness, and there is an excellent effect in that uniform and stable cutting characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a conventional laser oscillator, FIG. 82 is a configuration diagram showing an embodiment of this first invention, FIG. 8 is a front view of the same metal grid, and FIG. A configuration diagram showing an embodiment of the invention, and FIG. 5 is a front view of the same metal grating. In the figure, (3) is a total reflection mirror, (4) is a partial transmission mirror,
(5a) is a plane-polarized laser beam, (6) is a metal grating, (
7) is a thin metal wire, αO is a phase retarder, and (b) is a circularly polarized laser beam. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa Figure 1 Figure 2 Figure 3 Figure Otsu Figure 4 Figure 5

Claims (4)

[Claims] (1) In a laser oscillator having a total reflection mirror and a partial transmission mirror, which are provided oppositely on the optical axis of the laser beam, a metal grating made of thin metal wires is installed between the total reflection mirror and the partial transmission mirror. A laser oscillator characterized by: (2) A laser oscillator according to claim 1 JJI, characterized in that the thin metal wire has a diameter of about 0.1 mm or less; (3) In a laser oscillator that has a total reflection mirror and a partial transmission mirror that are arranged opposite to each other on the optical axis of the laser beam, a linearly polarized laser beam is generated between the total reflection mirror and the partial transmission mirror. A metal grid made of thin metal wires is installed in each corner,
A laser oscillator characterized in that a T-face retarder for converting the generated linearly polarized laser light into circularly polarized laser light is disposed in the propagation path of the laser light. (4) A laser oscillator according to claim 8, wherein the thin metal wire has a diameter of about 0.1 mm or less;