JPH01180796A - Laser beam radiation method - Google Patents

Abstract

PURPOSE:To obtain the beam having an uniform energy distribution linearly in the linear direction by stopping the laser beam emitted from a laser oscillator in one direction by a concave circular columnar mirror and superposing the laser beam at the radiation position by the integrating mirror having a convex circular columnar mirror at the segment. CONSTITUTION:The laser beam composed of the integrating mirror 2 having concave circular columnar mirror 1 and convex circular columnar mirror at the segment and emitted from an oscillator is stopped in one direction by the concave circular columnar mirror 1 and then spread in the direction displaced 90 deg. from said direction by the integrating mirror 2 having the convex circular columnar mirror at the segment. The beam shape at the position where it is stopped min. By the circular columnar mirror 1 becomes linear. The energy distribution of the image reflected from each segment 2-2-2-6 on which the beam is made incident is superposed by condensing at one place even if it is inhomogeneous and a homogeneous energy distribution is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a laser beam irradiation method, and particularly to a method of controlling the shape of irradiated light in laser beam irradiation.

(Prior Art) Generally, in laser processing, it is important to control the beam shape at the irradiation part to the optimum shape according to the processing. For example, when modifying the surface layer of a workpiece using a laser, methods shown in FIGS. 2 to 4 have been proposed. Figure 2 shows a method in which a laser beam focused by lens 7 is irradiated at the position of the differential lens, and the processing head *
Although it is possible to process a fixed area by moving the bamboo workpiece, there are two major problems: the energy distribution is not uniform in the irradiation part, and the beam diameter cannot be increased very much because the energy density decreases.

Therefore, the PlfJ3 diagram solves these problems.
This is the optical system shown in FIG. Figure 3 shows a system using integral #t8, each segment making up integral #t8)
The former problem can be solved by converging the light converging direction of the mirror into one direction and making the energy distribution in the irradiation part uniform by the integral effect.
“ocus”.

Nov, 1 9 7 9. p, 6 8 y
”A Convex Bea-Integrat
or''), the latter problem cannot be solved. On the other hand, FIG.
．． 10, the incident light is first
A concave cylindrical mirror 9 focuses the beam in one direction, and a second convex cylindrical mirror 10 widens the beam in a direction perpendicular to this to form a linear beam. By doing so, the beam diameter can be increased without lowering the energy density, and the latter problem can be solved, but the former problem cannot be solved.

(Problems to be Solved by the Invention) As described above, with the conventional techniques, it is not possible to make the energy distribution of the laser beam uniform in the irradiation section and to increase the beam diameter without lowering the energy density of the laser beam.

(Means for solving the problem) The present invention focuses a laser beam emitted from a laser oscillator in one direction using a concave cylindrical mirror, and then directs the laser beam in the above direction using an integral value having a convex cylindrical mirror as a segment. The laser beam is spread out in a direction displaced by 90 degrees from the other hand, and the beams reflected from each segment of the integral value are superimposed at the irradiation position to obtain a laser beam that is linear as a whole and has a uniform energy distribution in the line direction. This is a laser beam irradiation method. By adjusting the focusing direction of each segment that makes up the integral value, the length of the linear beam can be set to a desired value, and the linear beam can be continuously irradiated onto the workpiece to achieve a fixed area of the workpiece. It is also possible to process

(Function) FIG. 1 shows an example of an optical system for carrying out the method of the present invention,
Concave cylinder Ii! 1 and an integral value 2 with a convex cylindrical mirror as a segment. The laser beam emitted from the oscillator is focused in one direction by a concave cylindrical mirror 1, and then expanded in a direction displaced by 90° from the above direction by an integral value 2 having a convex cylindrical mirror as a segment. Then cylindrical mirror 1
The beam shape at the position narrowed down to the smallest is the first
As shown in FIG. 3, it becomes linear.

Here, the energy distribution in the linear direction in the linear beam 3 becomes a problem, but the segment 2-
Even if the energy distribution of the images reflected from each of 2 to 2-6 is non-uniform as shown in Figure 5, by focusing them on one place, they will be superimposed as shown in the figure, resulting in a uniform energy distribution. is obtained.

Also, if the line length at this time is L, then by shifting the condensing positions of the segments or segments 2-5, 2-6 downward by τL and overlapping them, the original length can be reduced as shown in Figure 6. A linear beam of 1.5 times the size can be obtained. In this way, it is possible to create a beam of desired thickness by adjusting each segment. However, if the number of images superimposed on the same part is small, the energy distribution in that part tends to vary, so if you want to increase the length of the line to some extent, it is necessary to make the number of segments sufficiently large.

(Example) FIG. 7 shows an optical system designed to carry out the method of the present invention. The laser beam 6 incident on this optical system is f
= 1210 (mm) concave cylindrical mirror 1 narrows down the field in two directions, and each segment of the integral value of f = 215 (a + m) spreads it in the X direction (normal direction to the plane of the paper) and focuses it on one spot in the irradiation section. By overlapping them, a linear beam with a width of 41111% and a length of 220 m1 (of which a uniform portion was 16016 m) was obtained on the workpiece 5. When hardening was performed using this linear beam under the following conditions, uniform treatment over a width of 160 mm was achieved with one irradiation.

・Material: Cold-rolled thin steel plate (thickness 0.8a+m, carbon 0.
0.004~0.068%, graphite coating on the surface) ・Output: 6km (on the workpiece) ・Processing speed: 1~1.6cm/in (Effect of the invention) The surface layer of the workpiece is coated at once with a laser When processing a large area, it is effective to create a linear beam and run the workpiece in the line width direction, but the following two things have become possible with this invention: ■Laser The energy distribution of the laser beam that enters the optical system varies depending on the difference in the transverse mode of the oscillator, for example, the order in the case of multimode, and the M value in the case of ring mode, but according to the method of the present invention, no matter what energy distribution the beam enters, A linear beam with uniform energy distribution in the linear direction can always be created.

(2) According to the method of the present invention, the length of the beam line can be changed freely without replacing the beam, and the processing width can be changed freely.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of an optical system for carrying out the method of the present invention, Figs. 2 to 4 are diagrams showing conventional optical systems, and Figs.
The figure shows the energy distribution obtained by superimposing the laser beams reflected and emitted by each segment, and FIG. 7 is a cross-sectional view of an optical system for implementing the method of the present invention. 1... Four-sided cylindrical mirror, 2... Integrating mirror, 2-1 to 2-8
... segment, 3 ... linear beam, 4 ... box,
5... Workpiece, 6... Laser beam, 7... Lens, 8... Integrating mirror, 9... Concave cylindrical mirror, 10...
Convex cylindrical mirror.

Claims (3)

[Claims] (1) The laser beam emitted from the laser oscillator is focused in one direction by a concave cylindrical mirror, and then the laser beam is focused by an integrating mirror having convex cylindrical mirrors as segments at a 90° angle in the above direction.
゜A laser characterized by obtaining a laser beam that is linear as a whole and has a uniform energy distribution in the linear direction by overlapping the beams spread in the displaced direction and reflected from each segment of an integrating mirror at the irradiation position. Beam irradiation method. (2) The laser beam irradiation method according to claim 1, in which the length of the linear beam is set to a desired value by adjusting the focusing direction of each segment constituting the integrating mirror. (3) A laser beam irradiation method according to claim 1, wherein a linear beam is continuously irradiated onto a workpiece to process a fixed area of the workpiece.