JPS6148528A - Laser beam scanning and processing device - Google Patents

Abstract

PURPOSE:To decrease the number of laser scanners and to improve the efficiency, reliabiity, performance, etc., of a scanning system by subjecting the relation between the rotating angle of a rotary dividing mirror which divides a laser beam with time and the angle of oscillating mirrors for scanning to phase control, etc. CONSTITUTION:The laser beam 18 is changed over time-dividedly to transmission and reflection by the rotary dividing mirror 3 of an optical path selecting part 2. The transmitted beam 19a is scanned by the oscillating mirror 7a and is scanned at a microspot 9a to the surface of a steel sheet 10 by a lens 8a. The reflected beam 19b is scanned at a spot 9b by the oscillating mirror 7b and a lens 8b. The rotating speed of the mirror 3 is controlled by a rotation control device 12 on the basis of the moving speed of the sheet 10. The rotating angle of the mirror 3 and the oscillating angle of the morrors 7a, 7b are controlled by phase control parts 13a, 13b so as to have the specific phase relation in accordance with the signal from a rotating angle detector 11. The signals of the parts 13a, 13b are controlled with amplitude by amplitude control parts 14a, 14b and further the amplitudes of the mirrors 7a, 7b are controlled as well.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a laser beam scanning processing apparatus that uses a high-power pulsed laser beam to improve the magnetic properties of an object to be processed, such as a magnetic steel sheet.

[Conventional technology]

By irradiating the surface of a grain-oriented electrical steel sheet with a high-power pulsed laser beam such as a YAG laser,
Techniques for improving the magnetic properties of steel sheets (hereinafter referred to as steel sheets) are well known, such as in Japanese Patent Publication No. 57-2252. However, there are various problems to be solved when implementing such conventional techniques on an industrial scale, especially when using an oscillating mirror in the laser scanning mechanism, such as scanning linearity and multiple vibrations. The problem was how to control the scanning length using mirrors and how to reduce the number of laser devices.

[Problems to be solved by the invention]

For example, in order to irradiate a wide steel plate with a laser, a large number of vibrating mirrors are required due to the limited scanning width of the vibrating mirror, and it has been difficult to reduce the number of laser scanners. Further, the vibrating mirror is generally driven in a sine wave as shown in the curve by a sawtooth signal as shown in the curve Q1 in FIG. 5(A). In FIG. 5(A), 0 indicates the vibrating mirror angle, ■ indicates the drive signal voltage, and t indicates the time. When the vibrating mirror is driven as shown in FIG. 5(A), there is a problem that the vibration frequency cannot be increased and that a nonlinear portion always exists due to a transient phenomenon, such as the curve Ω2. Furthermore, in order to increase the vibration frequency, when driving with a sine wave signal as shown in curve Q3 in Figure 5 CB),
There have been problems such as the range in which linearity can be obtained becomes narrow and the scanning trajectories are not parallel. Furthermore, as shown in FIG. 6, there is also a problem in properly adjusting the overlapping degree of the scanning trajectories 15a and 15b on the steel plate lo by the adjacent vibrating mirrors due to the non-linearity of the ends.

[Means to solve the problem]

The present invention solves the above problems by reducing the number of required laser scanners, increasing the linearity of scanning, and
In addition, the degree of overlap between adjacent scans can be freely adjusted, improving the efficiency, reliability, performance, and performance of high-power pulsed laser scanning systems.
The aim is to significantly improve the cost and other aspects. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical path selection section including a rotating splitting mirror for time-sharing a laser beam emitted from a laser light source in a plurality of directions, and a plurality of optical path selection units that scan the laser beam time-divided by the rotating splitting mirror. a laser beam scanning section consisting of a vibrating mirror; a phase control section that controls the relationship between the rotation angle of the rotary split mirror and the angle of the vibrating mirror; an amplitude control unit that controls the amplitude; an optical system that focuses the scanned laser beam onto the object to be processed; This is achieved by a laser beam scanning processing device configured with a control section that controls the frequency, and the object to be processed can be effectively irradiated with a laser beam at an arbitrary pitch and scanning width.

【Example】

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG. 1 shows a laser beam scanning processing apparatus according to an embodiment of the present invention, in which 1 is a high-power pulse laser light source such as a YAG laser, and 2 is an optical path selection section.
consists of an optical path switching member, such as a rotating split mirror 3, and a rotation drive unit, such as a motor 4, that rotates the rotating split mirror 3. As shown in FIG. 2, the rotating split mirror 3 includes a rotating plate 31,
The rotating plate 31 is composed of reflective members, for example, plane mirrors 32a to 32d, which are attached to the outer edge of the rotating plate 31 at substantially equal intervals along the circumferential direction. Further, reference numeral 5 denotes a first optical path changing section disposed on the optical path of the laser beam transmitted or reflected by the rotating splitting mirror 3, and this first optical path changing section 5 is connected to a plane mirror 5a disposed on the straight path of the laser beam. , and a plane mirror 5b provided on the reflected optical path reflected by the rotating split mirror 3. Reference numeral 6 denotes a second optical path changing section, which is composed of a plane mirror 6a provided on the optical path reflected by the plane mirror 5a, and a plane mirror 6b provided on the optical path reflected by the plane mirror 5b. Reference numeral 7 denotes a laser beam scanning section, which includes a first vibrating mirror 7a provided on the optical path of the laser beam reflected by the plane mirror 6a of the second optical path changing section 6, and a first vibrating mirror 7a provided on the optical path of the laser beam reflected by the plane mirror 6b. It consists of a second vibrating mirror 7b. On the scanning optical path of the vibrating mirror 7a, there is a first
A second FLL lens 8b is provided on the scanning optical path of the vibrating mirror 7b, and these first f-theta lens 8a and second f-theta lens 8b serve as a focusing section. 8, and the laser beam scans the surface of the steel plate 10, which is the object to be processed, with spots 9a and 9b. Therefore, the plane mirrors 5a, 6a, the vibrating mirror 7a and f-
The θ lens 8a serves as the first optical system, and the plane mirrors 5b and 6
b, the vibrating mirror 7b and the f-0 lens 8b each form a second optical system. Furthermore, 11 is a rotation angle detector for detecting the rotation angle of the motor 4, and 12 is a patented control device characterized by a moving speed signal S□ of the steel plate 10 and a detection signal S2 of the rotation angle detector 11. 13a and 13b are the first. The second phase control section 14a, 14b is connected to the first phase control section 14a, 14b. Phase control signal S48. of the second phase control section 13a, 13b. The first .S4b is input. The first amplitude control section 14a, which is a second amplitude control section, controls the amplitude of the first vibrating mirror 7a using the amplitude control signal S5a.
a controls the amplitude of the second vibrating mirror 7b by the amplitude control signal S5a. In the laser beam scanning processing device having the above configuration, the laser beam 18 emitted from the laser light source 1 is transmitted and reflected in a time-division manner by the rotating splitting mirror 3 of the optical path selection section 2. The laser beam 18 is transmitted to the plane mirror 32a of the rotating split mirror 3.
If it does not hit ~32d, it will pass through, and the plane mirrors 32a~32d
If it hits, it will reflect. If the diameter of the laser beam 18 is sufficiently small, switching between transmission and reflection can be performed efficiently.
If the diameter of the laser beam 18 is not small enough, it is effective to focus it with the lens 16 and make the transmitted beam 19a and the reflected beam 19b parallel again with the lenses 17a and 17b, respectively. In this case, lens 17a. It is also possible to increase the beam diameter after passing through 17b to improve the imaging performance of the subsequent optical system, and it is also possible to combine a parabolic mirror instead of a lens.
Of the laser beams time-divided by the rotating splitting mirror 3, the transmitted beam 19a passes through the plane mirrors 5a and 6a, is scanned by the vibrating mirror 7a, and is scanned with a minute spot 9a on the surface of the steel plate 10 by the f-lens 8a. The reflected beam 19b passes through plane mirrors 5b and 6b and then reaches the vibrating mirror 7.
b, and the steel plate 1 is scanned by the fe lens 8b.
The surface of 0 will be scanned with spot 9b. On the other hand, the rotation speed of the rotating split mirror 3 is controlled by the rotation control device 12 based on the moving speed signal S1 of the steel plate 10, and based on the detection signal S2 of the rotation angle detector 11.
Rotation angle of rotating split mirror 3 and vibrating mirrors 7a and 7b
The phase control unit 13 controls the deflection angle to have a specific phase relationship.
a and 13b. Phase control section 13a
, 13b output signal S48. S4b is rotating split mirror 3
It becomes a sawtooth wave with a specific phase relationship with the rotation angle of
Furthermore, the first. The amplitude is controlled by the second amplitude control sections 14a, 14b, and the control output signal S5a. 1st by S5b. The amplitude of the second vibrating mirrors 7a, 7b will also be controlled. The intensity of the beam 19a transmitted through the rotating splitting mirror 3 changes as shown by the curve Q4a in FIG. 3(A), and the intensity of the reflected beam 19b changes as shown in FIG. 3(A).
It changes like the curve Ω4b in B). The first vibrating mirror 7a, which has a specific phase relationship with these beam switching timings, receives a sawtooth wave signal Qi shown in FIG. 3(C).
a and is driven as shown by the curve Q2a. The second vibrating mirror 7b corresponds to the curves Q□b and Q2b in FIG. 3(D).
The drive is controlled as follows. Here, the vibrating mirrors 7a, 7 driven by the respective sawtooth wave signals (Qla, Q□b)
b has poor linearity in the early part of each period as shown by curves ρ2a and D2b due to transient characteristics, but since the timing at which the laser beam hits the vibrating mirror is controlled by the rotating splitting mirror 3, the final laser beam For scanning, portions with good linearity such as Q, a, Q, and b in the third @(E) are used. That is, in FIG. 3(E), the straight line Q5a represents the scanning characteristic of the first vibrating mirror 7a, Q,
b is the drive characteristic of the second vibrating mirror 7b. By such scanning, the actual scanning on the steel plate has good linearity and parallelism as shown in the scanning locus 40a in FIG. 4. Furthermore, the amplitude control blocks 14a and 14b are used as shown in FIG. 3(F).
Straight line Q Gat Q , b and scanning locus 4 in Fig. 4
0b, and it becomes possible to optimally combine scanning by a plurality of vibrating mirrors. In the above-described embodiment, the case where two vibrating mirrors are used is described, but the same effect can be obtained even when more vibrating mirrors are used. Effects of the Invention 1 As explained above, according to the present invention, in an apparatus for improving the magnetic properties of an object to be processed, such as an electrical steel sheet, by using a high-power laser beam, the same number of vibrating mirrors can be replaced by half the number of laser beams. In addition to improving the linearity of scanning, it also makes it possible to appropriately adjust the overlap of scanning by adjacent vibrating mirrors, which significantly improves the efficiency, reliability, performance, and cost of high-power laser scanning systems. There are effects that can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention, FIG. 2 is a front view of a rotating split mirror, and FIGS. 3(A) to (F) are a first
Figure 4 is a characteristic diagram of each part of the device shown in the figure, Figure 4 is a scanning processing characteristic diagram of the same device, Figures 5 (A) and CB) are characteristic diagrams of a conventional laser beam scanning processing device, and Figure 6 is a characteristic diagram of a conventional laser beam scanning processing device. It is a scanning processing characteristic diagram of a laser beam scanning processing device. In the figure, 1 is a laser light source, 2 is an optical path selection section, 3 is a rotating splitting mirror, and 5 is a first optical path changing section, 5a. 5b is a plane mirror, 6 is a second optical path changing unit + 6a, 6b is a plane mirror, 7 is a laser beam scanning unit, 7a. 7b is a vibrating mirror, 8 is a focusing unit, 8a and 8b are f-0 lenses, 10 is an electromagnetic steel plate which is an object to be processed, 11 is a rotation angle detector, 12 is a rotation control device, 13a and 13b are phase control units, 14a and 14b are amplitude control sections. Patent applicant: 1 person other than Yamada Kogaku Kogyo Co., Ltd. Figure 4 Figure 5 (A) Negative (B) θ

Claims (1)

[Claims] A laser beam scanning device consisting of an optical path selection unit including a rotating splitting mirror for time-sharing the laser beam emitted from the laser light source in multiple directions, and a plurality of vibrating mirrors for scanning the laser beam time-divided by the rotating splitting mirror. a phase control unit that controls the relationship between the rotation angle of the rotating split mirror and the angle of the vibrating mirror; and an amplitude control unit that controls the amplitude of the vibrating mirror in relation to a control output signal of the phase control unit. , an optical system that focuses the scanned laser beam onto the object to be processed, and a control unit that controls the rotational speed of the rotating split mirror and the vibration frequency of the vibrating mirror in accordance with the moving speed of the object to be processed. A laser beam scanning processing device characterized by comprising: