JPS59223407A - Optical device for laser - Google Patents

Abstract

PURPOSE:To improve the condensing property of a beam condensing device by arranging at least two spherical mirrors between a projected spherical mirror and a substance to be worked so that planes formed by incident light and reflected light intersect with each other at right angles. CONSTITUTION:A beam 3 is folded and contracted by a recessed spherical mirror 4 and the projected spherical mirror 5 and projected as beam 9. The beam 9 is changed upwards at its direction by a plane mirror 20 as a beam 21, reflected by a condensing recessed mirror 22 and condensed like a beam 23. The plane mirror 20 and the recessed spherical mirror 22 are arranged so that a plane constituted of the optical axis of the contracting beam and a plane constituted of the condensing beam, i.e. the plane constituted of the optical axes of the beams 3, 7, 9 and the plane constituted of the optical axes of the beams 9, 21, 23, intersect with each other. In addition, the angle theta3 formed by the beam 23 and the optical axis is set up so that the ratio of the major axis to the minor axis of an ellipse formed by the beam 23 on the basis of the folding spherical aberration of the recessed spherical mirror 22 is almost equal to the ratio of the major axis to the minor axis of the section 17 of the beam 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an optical device for a high-power laser, and more particularly to a laser resonator processing device that generates a small spot suitable for laser processing.

[Background of the invention]

In laser processing, a laser beam generated from a laser resonator is focused onto a minute spot using a special crystal lens or metal fJ1 reflector, and is irradiated onto an object. Is it compatible with conventional high-power laser equipment? However, in the light focusing method using a lens, there is a risk that the lens may be damaged due to thermal damage. The condensing method using a concave reflector made of all steel cannot reduce the incident angle to zero, resulting in large spherical aberrations and cannot be narrowed down to a small spot.

In addition, the condensing method using a metal parabolic reflector has small spherical aberration and can be narrowed down to a small spot, but the manufacturing cost of the emissive reflector is extremely high, and in addition, it is difficult to adjust the installation. Not generally available.

First, a conventional processing apparatus using a lens condensing method will be described with reference to FIG.

In conventional high-power laser devices, in order to increase the laser output, the volume of the laser medium was increased to increase the beam diameter. The structure is designed to generate a small-diameter beam equivalent to a relatively low-power laser device. FIG. 1 shows a processing device that also serves as this beam condenser.

In FIG. 1, a laser beam 3 emitted from a laser resonator 1 in the direction of an arrow 2 passes through a beam 7 in the direction of an arrow 6 through a spherical concave mirror 4 and an original mirror 5, which constitute a beam condenser. It is reduced to a beam 9 in the direction of arrow 8. plane mirror 10
Beam 1 redirected downwards with respect to beam 9 by
1 passes through a meniscus lens 12 and is focused as a beam 13, which is irradiated onto a workpiece 14 for cutting or melting.
Used for processing such as 15, 16, 17. IZ and 19 are cross sections perpendicular to the optical axis at point a of beam 3, point b of beam 7, point 0 of beam 9, point d of beam 11, and point e of beam 13, respectively.

Cross section 1 of the beam 3 first emitted from the laser resonator 1
5 is circular, but when it is folded and reduced by the spherical concave mirror 4 and the spherical convex mirror 5, the folding angle θ1. θ2
As the spherical mirror becomes larger, the spherical aberration due to the spherical mirror becomes larger. As shown in the cross section 17, the beams 9 and 11 gradually take on a severely distorted elliptical shape and have poor convergence.

Although the scathe lens acts to reduce spherical aberration in the process of focusing the beam 13, it cannot correct the spherical aberration caused by the optical path folding of the beam condenser. Therefore, the cross section 19 of the focused beam 13 on the workpiece 14 (e) has a cross section 182 that is an elliptical shape with poor convergence reduced to a similar shape.

As mentioned above, conventionally, the spherical aberration during focusing can be reduced by using a meniscus lens or a parabolic reflector, but the meniscus lens
It cannot be applied to high-output laser devices of W or higher, and parabolic reflectors are difficult to manufacture and expensive. Furthermore, high-power laser devices often have the disadvantage that spherical aberrations caused by the optical path folding of the beam condenser, which is essential, cannot be corrected.

[Purpose of the invention]

An object of the present invention is to provide a laser optical device equipped with a beam focusing device with good focusing properties.

[Summary of the invention]

The present invention utilizes this spherical aberration to reverse the optical path change using the spherical mirror at least twice (5 seconds), and corrects the spherical aberration of the first time with the spherical aberration of the second time. It is. That is, the person facing the spherical mirror for changing the optical path for the first time, the person facing the spherical mirror for changing the optical path for condensing the light for the second time, the plane containing the reflected optical axis, and the plane containing the reflected optical axis are perpendicular to each other, and 1. By selecting the angle between the reflected optical axes, a well-focused circular beam is obtained, and the above objective is achieved.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3. FIGS. 2 and 3, like the above-mentioned FIG.

In FIG. 2, a beam 3 emitted from a laser resonator 1 is folded back and reduced by a spherical concave mirror 4 and a spherical convex mirror 5 to become a beam 9. This beam 9 is redirected upward as a beam 21 by a plane mirror 20, turned back around a condensing spherical concave mirror 22, is condensed as a beam 23, and is irradiated onto the workpiece 14. Here, a plane composed of the optical axis of the reducing beam and a plane composed of the condensing beam, that is, a plane composed of the Te axes of beam 3, beam 7, and beam 9, beam 9, beam 21 and beam 23
A plane mirror 20 and a spherical concave mirror 22 are arranged so as to be orthogonal to each other, and the beam 23
The optical axis opening angle θ3 of the beams 21 and 23 is set so that the ratio of the major axis to the minor axis of the ellipse created by the folded spherical aberration effect is approximately equal to the ratio of the major axis to the minor axis of the cross section 17 (ellipse) of the beam 9. Set.

With such a configuration, the beam 21 that has been reduced by the spherical concave mirror 4 and the spherical convex mirror 5, changed its direction by the plane mirror 20, and has been deformed into an ellipse such as the cross section 24 at point f is transmitted to the condensing spherical concave mirror 22. Due to the effect of folded spherical aberration, the longer axis side of the ellipse becomes shorter υ and the shorter axis side becomes longer, resulting in a well-focused circular beam such as a cross section 25 with equal real images in X-Y on the workpiece 14.

Moreover, FIG. 3 shows an embodiment in which two condensing spherical concave mirrors are combined. The beam 9 emitted by the beam condenser is
It is redirected downward by a plane mirror 10 to become a beam 11. The beam 11 is condensed by a spherical concave mirror 26 and a spherical concave mirror 28 into a beam 27 and a beam 29, and is irradiated onto the workpiece 14.

Here, the plane formed by the reduction beam optical axes of beam 3, beam 7, and beam 9 and the plane formed by the condensing beam optical axes of beam 9, beam 11, beam 27, and beam 29 are orthogonal to each other. , plane mirror 10, spherical concave mirror 26.
28, and the beam 11 is folded twice by the spherical concave mirrors 26 and 28. The ratio of the major axis to the minor axis of the ellipse formed by the spherical aberration action is the ratio of the major axis to the minor axis of the ellipse of the cross section 18 of the beam 11. The optical axis opening angle θ4 of beam 11 and beam 27, beam 27 and beam 29 are approximately equal to
The optical axis opening angle θ6 is set. As described above, by arranging and setting the demagnifying and focusing mirrors, the cross section 17 of the beam 9 emitted by the beam condenser is redirected by the plane mirror lO, and becomes an ellipse like the cross section 18 of the beam 11. The major and minor axes of are reversed (y axis > X axis → X axis > y axis). The beam 11 is folded twice by the spherical concave mirror 26 and the spherical concave mirror 2B, and due to the spherical aberration effect, the long axis side of the ellipse is short and the short axis side is long, so that the beam 11 has a convergence like the cross section 31 in the workpiece 14. Makes a good circular beam.

Even if the beam condenser composed of the spherical concave surface @4 and the original curved mirror 5 in FIGS. 2 and 3 is placed inside the laser resonator 1,
It has the same effect as above.

As described above, according to this embodiment, even if the beam emitted from the beam condenser has an elliptical shape with significant distortion, the arrangement of the condensing spherical concave mirror is set to the above-mentioned conditions, and the spherical aberration is eliminated. If this is corrected, the focused beam spot on the surface of the workpiece can be made smaller.

〔Effect of the invention〕

According to the present invention, it is possible to provide a laser condensing device with good focusing properties, which is composed of a plane mirror and a spherical mirror, so that a high-power laser processing device with good processing performance can be produced at low cost.

[Brief explanation of drawings]

Figure 1 shows the configuration of a conventional laser processing device.
(l □ perspective view, FIG. 2, and FIG. 3 are perspective views showing the configuration of a laser processing apparatus that is an embodiment of the present invention. 1... Laser resonator, 3, 7, 9, 11, 12゜21
．． 23,27.29...Laser beam, 4...Reduction spherical concave mirror, 5...Reduction rigid spherical convex mirror, 10.20...
- Plane mirror, 12... Meniscus lens, 14... Workpiece, 15-19.24, 30.31... Bead stop surface, 22.26.28... Spherical concave mirror for condensing light. Agent Patent Attorney Akio Takahashi ¥1 Figure 72 Figure V3

Claims (1)

[Claims] 1. In a device that irradiates a workpiece with a focused laser beam via a spherical concave mirror and an original screen mirror, a plane formed by the incident light and reflected light between the original screen mirror and the workpiece. 1. A laser optical device characterized in that at least two spherical mirrors are arranged so that the mirrors are perpendicular to each other.