JP3241707B2 - Laser processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus capable of performing efficient and high-quality laser processing.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing a solid-state laser device used in a conventional laser processing device, for example, shown in "Laser Handbook", pp. 222, Ohmsha (1982), edited by The Laser Society of Japan. FIG. In the figure, 1 is a total reflection mirror, 2 is a partial reflection mirror, and these both constitute a laser resonator. Reference numeral 3 denotes a solid-state device serving as a laser medium of a solid-state laser, 4 denotes an excitation light source such as an arc lamp for exciting the solid-state device 3, 5 denotes a power supply for turning on the excitation light source 4, 6 denotes a condenser of the excitation light source 4, 7 Is a sealing material such as an O-ring that seals a contact portion between the peripheral surface of the solid-state element 3 and the condenser 6;
Reference numeral 8 denotes a base, 14 denotes a laser beam generated in the laser resonator, and 15 denotes a laser beam emitted from the laser device.

The solid-state device 3 contains a laser active material,
In the case of G (Yttrium Aluminum Garnet) solid-state laser, Nd: YA doped with Nd ³⁺ as a laser active material
A G crystal is used. The light collector 6 has, for example, an elliptical cross-sectional shape, and the solid-state element 3 and the excitation light source 4
And the inner surface is made to be a light reflecting surface, so that the excitation light source 4
Is collected on the solid-state device 3.

Next, the operation will be described. Solid element 3
When absorbing light of a predetermined wavelength from the excitation light source 4, a laser beam 14 is generated by laser transition.
The laser beam 4 is amplified while reciprocating between the two mirrors 1 and 2 in the laser resonator, and is emitted to the outside through the partially reflecting mirror 2 as a laser beam 15 having good directivity when reaching a certain intensity.

FIG. 3 shows, for example, US Pat.
FIG. 3 is a cross-sectional view showing a solid-state laser device used in the conventional laser processing device shown in No. 3,509. 3, 1, 2, 4, 5, 6, 7, 8, 14, and 15 correspond to FIG.
It is the same as the laser device of the above. Reference numeral 3 denotes a solid-state element including an active solid medium, the surface of which is 5 to prevent parasitic oscillation.
The size is about 0 μm RMS. Where RM
S (Root Mean Square) is a unit of roughness and represents a root mean square value. For example, “50 μ inch RMS” means that the mean square value of roughness during one inch is 50 microns. Reference numerals 9 and 900 denote cylindrical tubes for adjusting the flow of the medium 70 that cools the periphery of the solid-state element 3 including the light source 4 and the active medium. 81 and 82 are an inlet and an outlet of the cooling medium 70.

Next, the operation will be described. In the solid-state laser device having the above-described configuration, the excitation light source 4 and the solid-state element 3 are arranged at the focal point of the concentrator 6 having an elliptical cross section, and the light emitted from the light source 4 turned on by the power supply 5 has the surface thereof. Are diffused at the stage of passing through the exposed cylindrical tube 900 and uniformly enter the solid medium from the surroundings. The solid state element 3 is excited by this light and becomes a laser medium. Spontaneous emission light generated from the laser medium is amplified while reciprocating between the resonators constituted by the mirrors 1 and 2, and when it reaches a certain size or more, is emitted to the outside as a laser beam 15 having good directivity. You. The light source 4 and the solid-state element 3 are separated from the tube
It is cooled from the surroundings by a cooling medium 70 circulating inside.

[0007]

Since the conventional laser processing apparatus is configured as described above, the light (energy) of the excitation light source 4 absorbed by the solid-state element 3 of the solid-state laser device to be used is a specific light. Only the wavelengths are used for the laser output, and the other wavelengths are absorbed by the solid state element 3 and heat the solid state element 3. For this reason, the solid state element 3 needs to be cooled. However, due to the structure of the solid state laser device, the solid state element 3 must be cooled from the periphery. As a result, in the cross section of the solid-state element 3, a temperature distribution is generated in which the temperature is high at the center and lower at the periphery. Then, the refractive index of the solid state element 3 has a distribution corresponding to this temperature distribution in the cross section, and the wavefront of the laser light 14 passing through the solid state element 3 is distorted. Therefore, the laser light 14 in the resonator
Will generally be focused. Such a laser beam focusing action by the solid state element 3 is referred to as “thermal lens action of the solid state element”.
Destabilizes the operation of the laser cavity. As a result, the cross-sectional area of the laser beam 14 in the laser resonator becomes small, and the emitted laser beam 15 diverges irregularly due to the change in the thermal lens difference capacity accompanying the change in the input power in the power supply 5. Become. Therefore, when the laser beam is projected to a processing stage or the like using the transmission mirror using the transmission mirror, the laser beam 15 protrudes from the transmission mirror. Until is stabilized, there has been a problem that the position of the focal point of the laser beam 15 cannot be accurately determined and stable processing cannot be performed.

An object of the present invention is to provide a laser processing apparatus capable of performing efficient and high-quality laser processing using a laser beam generated from a solid-state laser apparatus.

[0009]

A laser processing apparatus according to the present invention provides a laser beam generated by a laser apparatus.
An optical system for transmitting to the workpiece near a first condensing optical system for condensing the laser beam emitted from the optical system, an opening disposed in the vicinity of the focal point of the first condensing optical system, the opening
Focus the laser beam spread after the mouth on the workpiece
And two condensing optical systems .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1A is a configuration diagram showing a laser processing apparatus according to Embodiment 1 of the present invention, and FIG. 1B is a cross-sectional view of a solid-state laser device. In the figure, 2, 4, 5,
Reference numerals 6, 7, 8, 14, 15, 70, 81, and 82 are the same as those of the conventional apparatus shown in FIG. Also, 9
Is a cylindrical tube for regulating the flow of the medium 70 for cooling the periphery of the solid state element 300 containing the active medium, and is made of transparent glass. 11
Is a total reflection mirror having a radius of curvature R, 11a is a total reflection mirror that guides the laser beam 15 passing through the partial reflection mirror 2 to a condenser lens 12a2, 12 is a condenser lens forming a laser resonator of a solid-state laser device, and 12a1 is A condensing lens (first) for condensing a laser beam emitted from a solid-state laser device.
A condensing lens (second condensing optical system) 12a2 condenses the laser beam that has spread again after passing through the opening 500 and guides the laser beam to a workpiece, and 13a and 13b are total reflection mirrors 11 and 12, respectively. This is a moving stage for moving the condenser lens 12a1 back and forth with respect to the partial reflection mirror 2. Reference numeral 300 denotes a solid-state element having a roughened surface, 500 denotes a metal, ceramic, glass tube, optical fiber, or the like, is disposed on the optical path of the laser beam 15 and cuts off the opening, 800 denotes a workpiece, and 810 denotes a processing object. Nozzle, 82
0 is a processing gas inlet.

Next, the operation will be described. The laser beam 15 generated from the solid-state laser device is transmitted to a place distant from the atmosphere, the direction is changed by the total reflection mirror 11a, and then the light is collected by the condenser lens 12a1. Is passed through an opening 500 made of a metal, ceramic, glass tube, optical fiber, or the like, and cut off, and further condensed by a condensing lens 12a2.
Laser processing.

Further, since the surface of the solid state element 300 is roughened, the aberration in the cross section of the solid state element 300 is small.
The laser beam 15 generated from the solid-state laser device of this embodiment is focused on a small spot. Therefore, the work piece 8 is formed by the small focused laser beam 15.
00 laser processing can be performed.

As described above, according to the first embodiment, the optical system including the partial reflection mirror 2 and the total reflection mirror 11a for transmitting the laser beam 15 generated from the laser device to the vicinity of the workpiece 800 is used. A condenser lens 12a for condensing the laser beam 15 emitted from the optical system.
1, an aperture 500 arranged near the focal point of the condenser lens 12a1, and a condenser lens 12a2 for condensing the laser beam 15 spread again after the aperture 500 and guiding the laser beam 15 to the workpiece 800. The laser beam 15 is condensed on the optical path and passed through the opening 500 at the same time, and the diffraction wave is cut off by the opening 500. Therefore, laser processing can be performed with the laser beam 15 without the diffraction wave.

The first embodiment works particularly effectively when a solid-state laser device having a mirror end in a laser resonator is used.

Although not specifically described in the above embodiment, a non-reflective thin film is applied to a part of the optical element, which is not particularly indicated, and to a part through which the laser beam passes as in a normal optical element. If the loss in the resonator is reduced,
Efficient laser oscillation can be realized.

[0016]

As described above, according to the present invention, an optical system for transmitting a laser beam generated from a laser device to the vicinity of a workpiece and a laser beam for condensing the laser beam emitted from the optical system are provided. (1) a condensing optical system, an opening disposed near the focal point of the first condensing optical system, and an opening extending after the opening.
And a second focusing optical system for focusing the laser beam on the workpiece, so that the peripheral beam, which is the effect of the diffracted wave at the focusing point of the laser beam, is removed, and There is an effect that high-quality laser processing can be realized.

[Brief description of the drawings]

FIGS. 1A and 1B are configuration diagrams of a laser processing apparatus according to Embodiment 1 of the present invention, in which FIG. 1A is a side sectional view, and FIG.

FIG. 2 is a cross-sectional view showing a solid-state laser device used in a conventional laser processing device.

3A and 3B are configuration diagrams illustrating another example of a solid-state laser device used in a conventional laser processing apparatus, where FIG. 3A is a side sectional view, and FIG.

[Explanation of symbols]

2 Partially reflecting mirror, 3,300 solid state device, 4 excitation light source, 5 power supply, 6 condenser, 7 sealing material, 8 bases,
9 tube, 11 total reflection mirror, 12, 12a1, 12
a2 condenser lenses (thermal lens correction optical system, image transfer optical system, first condenser optical system, second condenser optical system), 13a, 13
b Moving stage, 14 laser light, 15, 36 laser beam, 70 cooling medium, 81 inlet, 82 outlet, 500 opening, 800 workpiece, 810 processing nozzle, 820 inlet.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Akira Ishimori 8-1-1 Tsukaguchi Honcho, Amagasaki City Mitsubishi Electric Corporation Central Research Laboratory (72) Inventor Tetsuo Kojima 8-1-1 Honcho Tsukaguchi Amagasaki City Mitsubishi (56) References JP-A-1-313195 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 26/00-26/073 H01S 3 / 00

Claims (1)

(57) [Claims] 1. An optical system for transmitting a laser beam generated from a laser device to a position near a workpiece, and a first system for condensing the laser beam emitted from the optical system.
A condensing optical system, an opening arranged near the focal point of the first condensing optical system, and a laser beam spread after the opening is condensed on a workpiece.
A laser processing apparatus provided with a second focusing optical system .