JPS63154280A - Laser beam machine - Google Patents

Abstract

PURPOSE:To execute laser beam machining at a high speed by providing a higher harmonic generator between a laser light source and a condensing lens, and condensing a laser light of >=two wavelengths containing a fundamental wave and each order higher harmonic onto an object to be worked, by the same condensing lens. CONSTITUTION:A fundamental wave optical pulse 11 emitted from an Nd : YAG laser 1 is made incident on the second higher harmonic generator 7, and converted to an emitting pulse 12 consisting of a fundamental wave and the second higher harmonic. This emitting pulse 12 passes through a reflecting mirror 2 and is condensed by the same condensing lens 3, and in its focus and the vicinity of the focus, a metallic thin film 4 on a glass substrate 5 supported by a moving stage 6 is cut. In such a way, an allowable quantity against a position shift of the object to be worked is increased, and laser beam machining can be executed at a high speed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention utilizes the high optical energy density generated at and around the focal point when laser light is focused by a lens.
Drilling, cutting and welding in various materials.

The present invention relates to a laser processing device that performs processing such as surface treatment.

[Conventional technology]

Laser processing is a non-contact thermal processing that instantly melts or evaporates the material by focusing so-called coherent laser light on a microscopic spot on the processing point to increase the optical power density. It is currently widely used because it has the following features:

(11) A wide variety of processing can be performed, such as micromachining, cutting, welding, 1 surface heat treatment (hardening, amorphization, and 1 alloying).

(2) Metals, nonmetals (semiconductors, ceramics, resins).

Almost all materials (diamond, crystal, etc.) can be processed.

(3) Since no force is applied to the workpiece during machining, machining with high dimensional accuracy is possible.

(4) Suitable for automation of processing using electronic computers, allowing processing of complex shapes.

Figure 2 shows an example of a laser processing device.
: Light pulse 11 emitted from 1 (denoted as YAG laser) 1
is bent by 90 degrees by the reflecting mirror 2, and then the convex lens 3 bends the diameter 0 on the metal 11114 deposited on the glass substrate 5.
．． At this time, the optical power density at the focal point is 10? ~10" W/d, the metal thin film 4 in the area irradiated with the laser beam is instantaneously evaporated and removed. Therefore, each time the light pulse is irradiated, the glass substrate is moved by the moving stage 6. 5 is moved by the diameter of the focal point, the metal thin film 4 can be cut along this moving direction.

[Problem that the invention seeks to solve]

As described above, in the conventional laser processing method, as the focal radius is made smaller, the optical power density at the focal point increases in proportion to the square of the focal radius, and cutting becomes more reliable. therefore,
From this point of view, it is better to condense the laser beam using a condensing lens with a focal length as short as possible, because the focal radius is inversely proportional to the focal length of the condensing lens. However, as the focal length becomes shorter, the depth of focus becomes shallower in proportion to it, so if the position of the gold RS thin film 4 shifts even slightly in the vertical direction, a problem arises in that it is out of focus and cannot be cut.

To solve this problem, the conventional method was to move the condensing lens up and down and adjust the focus so that it was on the thin metal film, but this method had a slow response speed, so laser cutting The disadvantage is that the speed is limited to the focus adjustment speed.

In particular, when the size of the glass substrate is about 3Qcnx3Qcm, the warpage of the substrate becomes larger than the depth of focus, and the processing speed of the metal thin film is limited by the speed of focus adjustment of the condenser lens.

The purpose of the present invention is to solve the above-mentioned problems, to reduce the focal radius by using a condenser lens with a short focal length, and to make focus adjustment necessary even if the distance from the condenser lens to the workpiece is not uniform. An object of the present invention is to provide a laser processing device that can perform laser processing at high speed without any problems.

[Means for solving problems]

In order to achieve the above object, the present invention provides an apparatus for processing a workpiece by condensing laser light with a condensing lens and focusing it on a workpiece. A generator is provided, and a condensing lens is capable of condensing laser light of at least two wavelengths of the fundamental wave and each harmonic onto the workpiece.

[Effect]

By condensing light of two or more wavelengths onto the workpiece using the same condensing lens, the effective depth of focus deepens due to the shifted focal depths of the light of each wavelength. There is no need to adjust the focus even if there is a positional shift.

〔Example〕

FIG. 1 shows an embodiment of the present invention. Parts common to those in FIG.
A wavelength of 532 nm) is condensed by the same condensing lens 3, and the thin metal film 4 on the glass substrate 5 supported by a moving stake is cut at and near the focal point.

First, the fundamental wave light pulse 11 emitted from the NdjYAG laser is transferred to KHtPO4 (KDP) as a nonlinear optical crystal.
), about 50% of which is converted into a second harmonic with a wavelength of 532 nm, which is emitted together with the fundamental wave. This emitted pulse 12 passes through a reflecting mirror 2 and is focused by a convex lens 3 made of optical glass (BI3). The focal length of this lens is approximately 9 points. There is an oc − relationship between the focal length f and the refractive index n, but the refractive index n varies depending on the wavelength even for the same material.
, 064 nm is 1.507. Therefore, the focus of the second harmonic is in front of the focus of the fundamental wave, and the focus of the third harmonic is in front of the focus of the fundamental wave.
The distance d1 shown in the figure is as follows.

d, -9x (1,519-1)/(1,507-
1) -9-0,213 (fl) As shown in FIG. 3, the depth of focus d of the convex lens 3 for single wavelength light! +d,
is about 0.2 tm, so the depth of focus d4, which is the sum of the fundamental wave and the second harmonic, is about 0.4, and in the end, the depth of focus can be doubled without increasing the radius of focus r. Ta. Therefore, the vertical shift due to the warpage of the 30 cm x 30 cm glass substrate can be absorbed within the added depth of focus d4, and the metal thin film can be cut without adjusting the focus. In addition, the beam cross section 31 of the fundamental wave shown in FIG. Since the focal radius of the narrowest part of the second harmonic beam cross section 32 is the same as in the conventional case, the cutting width is also about o, t tm, which is the same as in the conventional case.

The above embodiment was a combination of the fundamental wave and the second harmonic of a Q-switched Nd:YAG laser. It goes without saying that it is possible to combine any two or more wavelengths of the third harmonic (wavelength 355n■) and fourth harmonic (wavelength 266n■), and also for laser oscillators other than Q-switched Nd:YAG lasers. A similar processing method is also possible using .

〔Effect of the invention〕

According to the present invention, since laser beams of two or more wavelengths of each harmonic obtained using a harmonic generator are focused by the same lens, the focal length for each wavelength is different, and the positions are shifted. Since the focal depths can be shifted and overlapped or adjacent to each other, the effective depth of focus that can be used for processing can be increased. Therefore, the tolerance for displacement of the workpiece increases, and even if the substrate is warped, the effort of focus adjustment can be saved, and high-speed laser processing becomes possible.

[Brief explanation of the drawing]

Fig. 1 is a side view conceptually showing the operating state of an embodiment of the present invention, Fig. 2 is a side view conceptually showing the operating state of a conventional device, and Fig. 3 is a side view conceptually showing the operating state of an embodiment of the present invention. FIG. 2 is a cross-sectional view of a laser beam near a focal point in FIG. lid: YAG laser, 3: condenser lens, 4: gold r! A
Thin film, 5 glass substrates, 7: second harmonic generator. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1) In devices that process laser light by condensing it with a condensing lens and focusing it on the workpiece, a harmonic generator is provided between the laser light source and the condensing lens, and the condensing lens is the basic 1. A laser processing device that is capable of condensing laser light of at least two wavelengths of waves and harmonics onto a workpiece.