JPS6043236B2 - Laser processing method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a laser processing method.

A first object of the present invention is to use a first hole provided in one of two parallel flat plates as a reference, and a second hole with a smaller diameter than the first hole in the other flat plate. A more specific example is to precisely machine an aperture of an electron tube or the like coaxially with a hole of a grid, limiter, etc. The second object of the present invention is to
This solution solves the problem of difficulty in determining the processing position by observing the fine structure of the processing surface due to the low magnification and resolution of the condensing lens used for processing when performing fine processing using laser light. It's about making it easier.

The aperture of an electron tube is a microhole with a diameter of about 20 to 80 μm. Conventionally, this is processed by etching or electroforming a thin plate. The flat plate with the aperture hole is adjusted in position while being observed with a microscope, and then attached to the holder. It was spot welded and assembled into an electron gun.

At this time, it is necessary to process and assemble with high precision the coaxiality with the holes drilled in other electrodes, but in the conventional method, the coaxiality of about 30 PTrl was the limit. The method of the present invention can easily process such coaxial holes of different diameters, and embodiments thereof will be described below with reference to the drawings. FIG. 1 is a diagram for explaining one embodiment of the present invention.

In the figure, a workpiece 1 consists of a cylinder 1a, a flat plate 1b having a hole ld, and a flat plate 1c on which a hole is to be made with a laser beam, and a stage 2 such as an X-Y table.
It is placed on.

The laser beam emitted from the laser oscillator 3 is bent by a semi-transparent mirror 4 as shown by a solid line, and is directed to a flat plate 1c by a condensing lens 5.
It is structured to focus on the surface of the For the purpose of the present invention, the laser oscillator 3 needs to be able to focus into a fine beam and use an optical lens, and a ruby laser, a YAG laser, etc. are suitable for this purpose. On the other hand, light emitted from the illumination light source 6 (light source light such as that used in a normal microscope) is bent by a semi-transparent mirror 7 and reaches the workpiece 1.

In other words, the optical path using the hole 1d as a light source is shown by a broken line. When considering a YAG laser as the laser beam, the wavelength is 1.06 μm, and its focal point is set to be above 1c, so the wavelength of the light from the light source 6 is set to 0.06 μm.
If it is represented by 6 μm, the focal point will be at a position closer to the lens 5 than the surface of the flat plate 1c. If the position of the hole 1d is far from the focal point of the illumination light, an image using the hole 1d as the light source will pass through the lens 5 and be obtained as a real image.
Since d is located closer to the lens 5 than the focal point of the illumination light, the light from the hole 1d as a light source passes through the lens 5 and becomes diverging light, so the lens 8 is placed to focus it. In this embodiment, a real image 9a of the hole 1d is formed at the position of the glass plate 9. A reference mark 9b is drawn on the glass plate 9 so that the center of the laser beam can be determined. Real image 9a and reference mark 9
b is magnified by an objective lens 101 and an eyepiece 11, passes through a reflecting mirror 12, reaches an ITV camera 13, and is observed on a television screen. An example is shown in FIGS. 2 and 3.

The reference mark 9b is a circle concentric with the laser beam, and its television image 9b'' is observed.
The real image 9a of d is also observed as a television image 9a'' at the same time.If the table 2 is moved to adjust the misalignment of the images 9a'' and 9b'' as shown in FIG. The center of the laser beam can be made concentric with the center of the hole 1d in the state shown in Fig. 3 by making one circle with a slightly smaller diameter. When the laser beam is irradiated, a hole 1e can be made in the flat plate 1c, resulting in a state as shown in FIG. 4.

What is important here is to match the centers of the laser beam and the reference mark 9b, but it is necessary to do trial processing in advance to make them match.

Once you have done this carefully, you can easily make the hole 1d by simply performing the alignment work as shown in Figures 2 and 3.
It is possible to obtain the coaxiality of the hole 1e. At the experimental stage, the coaxiality was 10 pm. was achieved stably. Next, other embodiments of the present invention will be described.

In FIG. 5, an example is shown in which the surface 14a of the workpiece 14 is subjected to several holes, heat treatment, etc.
4 is positioned by a fixed frame 16 provided on the table 17, and furthermore, a transparent glass plate 1 is mounted on this fixed frame 16.
5 is positioned with its surface kept parallel to the processing surface 14a.

A laser beam aiming mark 15a as shown in FIG. 6 is drawn on the glass plate 15. The aiming mark 15a is set in the same manner as the hole 1d in FIG. 1, and the laser beam is focused on the processing surface 14a by the lens 18, but at that time, the observation optical system is focused on this aiming mark 15a. be. Now, move table 17 and
After adjusting the position and irradiating the laser beam according to the steps shown in the figure and FIG. 3, the aiming mark 1 on the glass plate 15
Laser processing is performed at a position on the processing surface 14a corresponding to the center of 5a. The same effect can be obtained by changing the glass plate 15 to a material that is opaque to the laser beam and making a hole in the area of the aiming mark 15a. In this case, the seventh
The lens 21 focuses on the processing surface 19 as shown in the figure.
By making the diameter of the aiming hole 20a (7) smaller than the beam diameter at the position of the reference plate 20, the beam intensity distribution is improved. That is, the intensity distribution of a laser beam having a beam diameter d as shown in FIG. 8 is limited by the hole diameter smaller than d, resulting in an intensity distribution as shown in FIG. 9. Therefore, it is possible to perform sharp processing in a minute area), and the thermal influence on the surrounding area can be minimized. As described above, the present invention is characterized in that a reference object is placed in front of the processing surface to serve as a sight for determining the processing point. Seeing has the following advantages.

Generally, a lens for laser processing is a long focal length, low magnification lens, and its resolution is inferior to that of a normal microscope objective lens.

Therefore, on a surface having a fine structure that requires processing with a beam diameter of about 10 pm, it is extremely difficult to observe the fine structure through a processing lens and position the processing point. In the present invention, the positions of the reference object and the workpiece are observed in advance using an ordinary microscope, etc.
After accurate alignment, the reference object can be viewed through the processing lens and processed. By appropriately setting the aiming mark on the reference object, the processing point can be accurately determined even when observed using the processing lens. Can be positioned. This is especially effective when using a part of the processed object as a reference object. Another advantage is that the flat plate 15 in the embodiment shown in FIG. Can be processed. Further, by flowing gas or creating a vacuum in the space between the flat plate 15 and the workpiece 14, it becomes easy to prevent deterioration of the processed surface or accelerate processing.

[Brief Description of the Drawings] Fig. 1 is a diagram showing the configuration of an apparatus for explaining one embodiment of the processing method of the present invention, and Figs. 2 and 3 are illustrations of the positioning of the workpiece in this embodiment. A diagram for explaining an example of the method, FIG. 4 is a sectional view showing an example of processing according to this embodiment, FIG. 5 is a diagram for explaining another embodiment of the present invention, and FIG. 6 is a diagram for explaining this embodiment. 7 is a cross-sectional view showing the main parts of this embodiment, FIG. 8 is a diagram of the intensity distribution of the laser beam, and FIG. 9 is a diagram of the intensity distribution of the laser beam according to this embodiment. It is. 1... object to be processed, 1b... flat plate with hole 1d, 1c... flat plate to be drilled, 2...
... Stage such as X-Y table, 3 ... Loser oscillator, 4 ... Semi-transparent mirror, 5 ... Condensing lens, 6 ... Light source for illumination, 7・・・・・・Semi-transparent mirror,
8... Luns, 9... Glass plate, 9b.
...Reference mark, 14 ... Processing object, 15
...Glass plate, 15a ... Aiming mark, 16 ... Fixed frame, 17 ... Table,
19... Processed surface, 20... Reference plate, 2
0a...Aiming hole, 21...Luns.

Claims (1)

[Claims] 1. A reference object is placed above the processing surface of the processing object, the relative positions of the processing object and the reference object are fixed, and the laser beam is focused before processing the processing object. The observation optical system is configured to form a real image of the reference object, which is closer to the condensing lens than the focus, when the lens is approximately at the focal point position, and The axis center is set in advance as the center reference,
Observe the real image of the reference object, adjust the relative position of the laser beam and the workpiece so that the real image is at a predetermined position with respect to the center reference, and then irradiate the laser beam and focus it on the workpiece surface. A laser processing method characterized by: 2. The reference object is a flat plate in which the first hole is already provided,
2. The laser processing method according to claim 1, wherein a second hole having a smaller diameter than the first hole is formed coaxially with the first hole in the processing surface of the workpiece. 3. Laser processing according to claim 1, wherein the reference object is a flat plate transparent to the laser beam, an aiming mark is drawn on this flat plate, and the flat plate is arranged parallel to the processing surface. Method. 4. The laser processing method according to claim 1, wherein the reference object is an opaque body with respect to the laser beam, and has a hole having a diameter smaller than the laser beam diameter at that position as an aim.