JPS58154484A - Method for converting laser beam - Google Patents

Abstract

PURPOSE:To obtain a toric laser beam having optional diameters by reflecting a solid laser beam with a reflecting mirror having a circular conical convex face. CONSTITUTION:A solid laser beam 2 is converted to a toric laser beam 4 by the 1st reflecting mirror 8 of a circular conical shape assuming an angle alpha from the point where a plane 7 assuming 45 deg. to the optical axis intersects with the central axis of the beam 2. The selection of the beam 4 is accomplished without changing optical parts by moving the 2nd reflecting mirror 9 parallel in the direction of an arrow 10 in the central axis direction of the beam reflected from the mirror 8. To convert the same to a larger diameter, the mirror 9 is moved in the direction of the arrow 10 on the central axis of the beam reflected from the mirror 8 to condense the beam with a toric codenser lens 11 where the focuses of the lenses intersect, whereby the beam is irradiated to a circumferential joint part and joining such as brazing, soldering, welding or the like is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for converting a solid laser beam into an annular laser beam, and more particularly, a conversion method for obtaining an annular laser beam of an arbitrary diameter using an optical system using a reflecting mirror. Regarding.

A method for converting a solid laser beam into an annular laser beam uses a combination of lenses and prisms as shown in FIG. In FIG. 1, a solid laser beam 2 from a laser beam oscillator 1 passes through a conical transparent plate (prism) 3f and becomes an annular laser beam 4, which is focused onto a circumferential welding part 6 by a condenser lens 5. In this method, a focused laser beam is telefocused to irradiate the circumferential weld with the laser beam, so if the diameter of the circumferential weld increases, the energy density for welding decreases and welding becomes impossible.

Therefore, it is necessary to newly manufacture a transparent plate and a condensing lens that match the diameter of the circumferential weld. When a new optical system is installed, it is necessary to adjust the optical axis alignment of the optical system, which takes time and effort. In addition, an optical system that uses a single lens or prism has a large loss of laser energy due to reflection or absorption from the component surface.When performing circumferential welding with a laser beam focused in an annular shape, high output power is required. Since a laser beam is used, absorption of the laser beam may cause damage to lenses and prisms, causing fluctuations in the irradiation laser power.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for converting a solid laser beam from an oscillator into an annular laser beam having an arbitrary diameter using a reflecting mirror.

In the present invention, the second reflecting mirror that receives the annular laser beam reflected by the first reflecting mirror incorporated in the optical path of the solid laser beam island is arranged so as not to deviate the optical axis of the solid laser beam. This is a method of obtaining an annular laser beam with an arbitrary diameter by moving two reflecting mirrors in parallel on the optical axis of the annular laser beam. In addition, by orthogonalizing the optical axis of the annular laser beam from the first reflecting mirror and the optical axis of the solid laser beam, a concentric annular laser beam parallel to the solid laser beam can be made into a solid laser beam. can be converted in the same direction. Furthermore, by giving the first reflecting mirror or the second □ reflecting mirror a light-condensing property, the annular laser beam 'f: enters through the second reflecting mirror, brazing or soldering the circumferential joint. Can do things like welding.

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. In FIG. 2, a solid laser beam 2 is transformed into an annular shape by a first reflecting mirror 8 and transformed into the beam 4, and then a toroidal laser beam with a concentric circular cross section is produced by a second reflecting mirror 9 in the same direction as the solid laser beam 2. A method is shown in which a circular Toko beam 12 is transformed into a circular condenser lens 11 to irradiate the circumferential joint portion, and the joint is performed by brazing, soldering, welding, or the like. That is, the solid laser beam 2 lies on a plane 7 that makes a 45 degree angle with the optical axis.
The solid laser beam 2 is converted into an annular laser beam 4 by a conical first reflecting mirror 8 that forms an angle α from the intersection of the solid laser beam 2 and the central axis of the solid laser beam 2. The annular laser beam 4 reflected from the first reflecting mirror 8 is not parallel and the energy adhesion distribution is uneven, so the second reflecting mirror 9 that is paired with the first reflecting mirror 8 is
On the optical axis of the annular laser beam 4 reflected from the reflecting mirror 8, a concave cone is formed on a plane parallel to the 45-degree plane assumed by the first reflecting mirror 8 so as to have the same angle α as the first reflecting mirror. The mirror surface of the second reflecting mirror 9 (parallel to the mirror surface of the first reflecting mirror 8) is provided in opposition to the totally reflected laser beam, so that the reflected beam from the second reflecting mirror 9 is reflected by a parallel circular center circle. Annular laser beam 4
transformed into. The diameter of the annular laser beam 4 is selected in the first step.
By moving the second reflecting mirror 9 in parallel in the direction of the arrow 15, which is the direction of the central axis of the reflected beam from the reflecting mirrors 8, this could be done without completely converting the optical components. The dotted line in FIG. 2 indicates the state of condensing light to a large diameter. The conversion to a larger diameter is performed by moving the second mirror in the direction of the arrow 15 on the central axis of the reflected beam from the first reflecting mirror 8.
By moving the reflecting mirror 9 and condensing the light with the annular condensing lens 11 whose lens focal points intersect, the light was irradiated onto the circumferential joint, and joining by brazing, soldering, welding, etc. was achieved. By integrating the second reflecting mirror 9 and the annular condensing lens 11, alignment of the optical axis when the diameter of the annular laser beam is changed can be performed without adjustment. The angle a between the first reflecting mirror 8 and the second reflecting mirror 9 was preferably within a range of 10 degrees or less. FIG. 3 shows a condenser reflector 14 that receives reflected light from a first reflector 8 having a conical mirror surface that forms an angle β with a plane 15 that is 30 degrees square with the central axis of a solid laser beam, and a toroidal condensed beam. 12 and its circumferential weld 13 are shown. That is, the condensing reflector 14 having a curved surface is arranged at a position outside the optical path of the mid-height laser beam 2, and the circumference is joined only by the combination of the two reflection theory, the first reflector 8 and the condensing reflector 14. This is what I did. The diameter of the annular laser beam 4 that matches the diameter of the circumferential joint is selected by selecting the first reflecting mirror 8 as shown in Figure 2.
This was achieved by adjusting the condensing reflector 14 to move in parallel on the central axis of the annular laser beam 4 reflected by the laser beam. Note that the β angle of the first reflecting mirror 8 was set to 10 degrees or less.

According to the present invention, since a parallel concentric annular laser beam can be obtained from a solid laser beam, there is no restriction on the position of the focusing optical system, and a freely shaped focusing optical system can be used. Furthermore, since the diameter of the annular laser beam can be arbitrarily selected by moving the distance of the optical system, changing the diameter and aligning the optical axis are easy.

An annular condensed beam can also be obtained by providing a curvature to the mirror surface of the first reflecting mirror.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram explaining a conventional laser beam conversion method, and FIGS. 2 and 3 are cross-sectional schematic diagrams explaining an embodiment of the present invention. 2... Solid laser beam, 4... Annular laser beam, 8... First reflecting mirror, 9... Second reflecting mirror, 10...
...Second reflecting mirror movement direction, 11...Annular condensing lens, 13...Fig. 1 Ministry of Fig. 2

Claims (1)

[Claims] 1. A method for converting a solid laser beam into an annular laser beam, which includes converting the solid laser beam into an annular shape by reflecting it on a first reflecting mirror having a convex conical surface, and converting the solid laser beam into an annular laser beam. A method for converting a laser beam, characterized in that the diameter of the annular beam is expanded in the direction in which the beam travels. 2. The V-the-beam conversion method according to claim 1, wherein the annular beam is reflected so as not to straddle the mid-height laser beam. 3. A patent claim in which the apex of the first reflecting mirror is aligned with the central axis of the solid laser beam, and the angle of the mirror surface is equiangular from a plane that is 45 degrees secluded from the solid laser beam at the apex of the mirror surface. The method for converting the V-the-beam according to item 1. 4. The laser beam conversion method according to claim 3, wherein the mirror surface of the first reflecting mirror makes an angle of 10 degrees or less with the central axis of the solid laser beam and a 45 degree plane. 5. The V-the-beam conversion method according to claim 1 or 2, wherein the annular beam is reflected by a second reflecting mirror having a concave conical surface and converted into a straight annular beam. 6. The second reflecting mirror faces the assumed solid laser beam at the apex of the first reflecting mirror and moves in parallel in the direction of the central axis of the solid laser beam reflected from a plane that forms an angle of 45 degrees to form an annular laser. 6. A method of converting a laser beam according to claim 5, wherein the diameter of the beam is adjusted. 7. The laser beam conversion method according to claim 5, wherein the mirror surface of the second reflecting mirror has a curvature having an annular focal point. 8. The method for converting a laser beam according to claim 5, in which the straight annular beam is made to come while maintaining its annular shape.