JPH08279639A - Slab laser and laser marker - Google Patents

Abstract

PURPOSE: To provide a slab laser which is capable of generating laser beams uniform in intensity distribution without lessening exciting light in utilization factor. CONSTITUTION: Light diffusion rods 6a and 6b are arranged close to the stimulation surfaces 1a and 1b of the slab 1 of a slab laser 100. The upper and lower surface of each of the light diffusion rods 1a and 1b are roughened like the sands to serve as diffusing surfaces. Stimulating light rays emitted from stimulating lamps 4a and 4b are made to impinge on the diffusion surfaces of the light diffusion rods 1a and 1b and diffused, whereby the stimulation surfaces 1a and 1b of the slab 1 are uniformly irradiated with stimulation light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser device, and more particularly to a slab laser included in a solid-state laser.

[0002]

2. Description of the Related Art Generally, in a solid-state laser called a slab laser, a slab-shaped solid-state laser medium (hereinafter referred to as a slab) is used as a laser medium like the conventional slab laser 300 shown in FIG. Also, the total reflection mirror 2
The cross section of the slab perpendicular to the direction (Z direction in FIG. 9) in which the laser light emitted from the resonator constituted by 2 and the output mirror 23 travels outward is rectangular. Excitation lamp 24
Excitation light from a and 24b is excited on a surface (hereinafter, referred to as an excitation surface) including the long side of the rectangle (this length is generally called the width of the slab) as shown by a dotted line. Light is emitted.

Regarding the slab laser, for example, Optronics, 1988, No. 6, pp. 94-98.
Page.

A problem with the slab laser is that the excitation light is strongly irradiated only to the central part of the excitation surface of the slab, and the intensity of the excitation light absorbed inside the slab in the cross section perpendicular to the Z direction is Its central part has a high distribution. As a result, the central portion of the laser light emitted from the slab laser may become strong. Therefore, particularly in marking or surface modification, since the laser beam is used as it is without being focused, uniform marking or surface modification may be difficult.

However, conventionally, diffusion plates 43a and 43b as shown in FIG. 10 are arranged between the slab and the excitation lamp, whereby the excitation light emitted from the excitation lamps 42a and 42b is supplied to the entire surface of the slab 41. In some cases, the slab 41 is uniformly excited by diffusing and irradiating.
Incidentally, this is described in, for example, Japanese Patent Application Laid-Open No. 61-23374.

[0006]

According to the conventional method using the diffusion plates 43a and 43b as shown in FIG. 10, the excitation surface of the slab 41 can be irradiated with the excitation light having a substantially uniform intensity distribution, but the resonance actually occurs. If you make a laser and oscillate,
The central part of the laser beam may still be strong.
The reason is considered as follows. The oscillated laser light is strengthened while reciprocating between the resonators, but the laser light passing through the peripheral portion of the cross section of the laser medium is easily separated from the laser medium when reciprocating between the resonators. for that reason,
It cannot be reciprocated many times between the resonators and is taken out from the resonator without being strengthened so much.

On the other hand, the laser light passing through the center of the cross section of the laser medium can be reciprocated between the resonators many times, and therefore is sufficiently strengthened to be extracted from the resonator. Therefore, even if the laser medium is uniformly excited in its cross section, in the intensity distribution of the lasing laser light,
The central part may become strong, and it is difficult to suppress this phenomenon and make the laser light intensity distribution uniform by the conventional method.

An object of the present invention is to provide a slab laser which can generate a laser beam having a uniform intensity distribution.

[0009]

In order to solve the above problems, the slab laser of the present invention is a slab laser which emits laser light from the slab-shaped solid laser medium by irradiating a slab-shaped solid laser medium with an excitation lamp. In the above, the light diffusing means having a function of diffusing a part of the pumping light from the pumping lamp having a width smaller than the width of the laser medium is provided at substantially the center of the laser medium.

[0010]

Function: Only the excitation light traveling from the excitation lamp toward the central portion of the excitation surface of the slab can be diffused, and the peripheral portion of the excitation surface can be directly irradiated with the excitation light. As a result, the intensity of the excitation light with which the central portion of the excitation surface of the slab is irradiated can be made lower than that of the peripheral portion.

Alternatively, the excitation surface of the slab is used as a diffusion surface, and the degree of diffusion of the excitation light in the central portion of the excitation surface is stronger than the degree of diffusion of the excitation light in the peripheral portion of the excitation surface. Then, the excitation light traveling to the central portion in the cross section of the slab can be made smaller than the excitation light traveling to the peripheral portion.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a slab laser 10 which is an embodiment of the present invention.
2 is a sectional view taken along the YZ plane of the slab laser 100. FIG.

As shown in FIGS. 1 and 2, in the slab laser 100, the total reflection mirrors 2 arranged on both sides of the slab 1 are arranged.
The output mirror 3 and the output mirror 3 form a resonator. Slab 1
Excitation lamps 4 a and 4 b for exciting the are arranged above and below the slab 1. That is, the excitation lamps 4a, 4
The excitation light that is directly incident on the slab 1 from b is incident on the excitation surfaces 1a and 1b of the slab 1 substantially vertically. In this embodiment, both ends of the slab 1 are holders 5.
a and 5b. Excitation surface 1a of slab 1,
Light diffusion rods 6a and 6b, which are members having a function of diffusing a part of the excitation light traveling from the excitation lamps 4a and 4b toward the slab 1, are arranged in the immediate vicinity of 1b.

To be precise, the light diffusing rod 6a is arranged on a straight line connecting the centers of the cross sections of the slab 1 and the excitation lamp 4a taken along the XY plane, and also the light diffusing rod 6b.
As for the above, the slab 1 and the excitation lamp 4b are arranged on a straight line connecting the centers of the cross sections taken along the XY plane. That is, the width of the light diffusion rod 6 a is smaller than the width of the slab 1, and is arranged along the longitudinal direction of the slab 1. That is, regarding these arrangements, A- in FIG.
FIG. 3 shows a cross section taken along line A ′. In FIG. 3, 9 is an excitation cavity for collecting excitation light on the slab 1, and 8 is a cooling tube.

Further, the light diffusion rods 6a and 6b have a function of diffusing a part of the excitation light traveling from the excitation lamps 4a and 4b toward the slab 1. In this embodiment, the light diffusion rods 6a and 6b are used.
The ends of the holders 5a and 5b are fitted and fixed at both ends thereof.

Although not shown in FIGS. 1 and 2, the slab 1 and the light diffusion rods 6a and 6b are made of Pyrex as shown in FIG. 3, which is a sectional view taken along the line AA 'in FIG. The slab 1, the light diffusion rods 6a and 6b, the cooling pipe 8 and the excitation lamps 4a and 4b are inserted into the cooling tube 8 made of glass, and the excitation light from the excitation lamps 4a and 4b is supplied to the slab 1. It is arranged in the excitation cavity 9 for collecting at. The inner surface of the excitation cavity 9 is a double elliptical reflection surface.

Next, the operation of the present invention will be described with reference to FIGS. 2 and 4, particularly showing the excitation lamps 4a and 4b, the slab 1, and the light diffusion rods 6a and 6b. The light diffusing rods 6a and 6b in this embodiment are elongated plate-shaped Pyrex glass, and 10a and 10 in the light diffusing rods 6a and 6b, respectively.
Each of the surfaces b, 10c, and 10d is a surface roughened into a sandy shape (hereinafter referred to as a diffusion surface). Therefore, as shown by the dotted lines in the figure, among the excitation lights emitted from the respective excitation lamps 4a and 4b, only those that are incident on the light diffusion rods 6a and 6b are diffused surfaces 10a, 10b and 10 respectively.
Widely diffused by c and 10d.

According to this, when the light diffusing rods 6a and 6b are not used, the excitation light that will illuminate the central portion of the excitation surface of the slab 1 is applied to a wider area.
That is, when the light diffusion rods 6a and 6b are used, it is possible to reduce the light amount of only the excitation light with which the central portions of the excitation surfaces 1a and 1b of the slab 1 are irradiated, so that the intensity of the excitation light in the central portion is weakened. You can As a result, the central portion of the intensity distribution of the laser light 7 that constitutes the resonator and oscillates does not become high.

The light diffusion rods 6a and 6b in the slab laser 100 may be brought into contact with the excitation surfaces 1a and ab of the slab 1, as shown in FIG. Alternatively, in the case where a slab 1 ′ having a sandy diffusion surface is used in place of the slab 1 in the slab laser 100, FIG.
As shown in FIG. 3, the diffusion state is partially changed so that the degree of diffusion of the excitation light on the diffusion surfaces 20b and 20e at the central portion of the excitation surface is changed to the diffusion surfaces 20a, 20c, 20d at the peripheral portion.
It is also possible to use one that is stronger than the degree of diffusion of the excitation light at 20f.

Further, the slab 1 shown in FIGS.
In 1 ', the greater their thickness (the length of the slab 1, 1'in the Y direction), the light diffusion rod 6a,
6b, or the excitation light diffused by the diffusion surfaces 20b and 20e is diffused widely before reaching the central portion of the slab 1,
The effect of the present invention is great.

Further, as another embodiment, as shown in FIG. 7, cooling water for cooling the slab 1 "is slab 1".
When flowing in parallel to the width direction (that is, the X direction), the central portions of the glass plates 31a and 31b arranged for flowing the cooling water may be diffusion surfaces 30a and 30b.

Next, a laser marker 200 using the slab laser 100 of the present invention as a light source will be described with reference to FIG. The laser light extracted from the slab laser 100, which is the light source in the laser marker 300, has its beam cross section expanded by the convex lenses 11 and 12, and the mask 13
For example, the liquid crystal mask is irradiated. At this time, the convex lens 1
1, the laser light at the position immediately after being emitted from the slab laser 100 is transferred to the position of the convex lens 12.
As a result, the intensity distribution of the laser light with which the mask 13 is irradiated becomes substantially the same as the intensity distribution of the laser light at the position immediately after being extracted from the slab laser 100.

Therefore, as described above, the slab laser 100 takes out the laser light having the substantially uniform intensity distribution, so that the mask 13 is irradiated with the laser light having the substantially uniform intensity distribution. .

Further, the image of the mask 13 is reflected downward by the reflecting mirror 14 and is imaged by the convex lens 15 on the IC package 16 which is an object to be marked, and is marked. Although the intensity distribution of the laser light with which the mask 13 is irradiated is directly reflected as the density distribution of the marked characters, since the mask 13 is irradiated with the laser light having a substantially uniform intensity distribution, Characters of various densities will be marked.

[0025]

According to the present invention, since the central portion of the intensity distribution of the excitation light with which the slab is irradiated can be weakened, the intensity distribution of the oscillating laser light can be made substantially uniform. Therefore, the laser marker of the present invention can perform marking with a uniform intensity distribution.

If the slab laser of the present invention is used for surface treatment, a uniform surface treatment can be performed.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a slab laser 100 of the present invention.

FIG. 2 is a sectional view of the slab laser 100 shown in FIG. 1 taken in the Z direction.

FIG. 3 is a sectional view taken along the line AA ′ in FIG.

4 is a cross-sectional view taken along the line AA ′ in FIG.

FIG. 5 is a sectional view showing another embodiment of the present invention.

FIG. 6 is a sectional view showing another embodiment of the present invention.

FIG. 7 is a cross-sectional view showing another embodiment of the present invention.

FIG. 8 is a configuration diagram of a laser marker 200 of the present invention.

FIG. 9 is a configuration diagram showing a conventional slab laser 300.

FIG. 10 is a configuration diagram showing a conventional slab laser 400.

[Explanation of symbols]

1, 1 ', 41 ... Slabs, 1a, 1b, 1a', 1b '
... Excitation plane, 2,22 ... Total reflection mirror, 3,23 ... Output mirror, 4
a, 4b, 24a, 24b, 42a, 42b ... Excitation lamp, 5a, 5b ... Holder, 6a, 6b ... Light diffusion rod, 7
… Laser light, 8… Cooling tube, 9… Excitation cavity, 10
a, 10b, 10c, 10d, 20a, 20b, 20
c, 20d, 20e, 20f, 30a, 30 ... Diffusion surface,
11, 12, 15 ... Convex lens, 13 ... Mask, 14 ... Reflector, 16 ... IC package, 31a, 31b ... Glass plate, 43a, 43b ... Diffuser, 100 ... Slab laser of the present invention, 200 ... Laser marker of the present invention , 300, 40
0 ... Conventional slab laser.

Claims (4)

[Claims] 1. A slab laser which emits laser light from a slab-shaped solid-state laser medium by irradiating a slab-shaped solid-state laser medium with an excitation lamp, and an excitation having a width smaller than the width of the laser medium at substantially the center of the laser medium. A slab laser comprising a light diffusing means having a function of diffusing a part of excitation light from a lamp. 2. The light diffusing means has a width in a cross section perpendicular to the laser light emitted from the laser medium shorter than a long side of a rectangle of a cross section of the laser medium perpendicular to the laser light emitted from the laser medium. 2. The slab laser according to claim 1, wherein the members are arranged on a straight line connecting the centers of the cross sections of the laser medium and the excitation lamp. 3. The light diffusing means has a function of diffusing pumping light from the pumping lamp in a surface of the slab-shaped solid-state laser medium including a long side of a rectangle of a cross section perpendicular to the laser beam emitted from the laser medium. And a degree of diffusion of the excitation light in the central portion of the surface including the long side is stronger than a degree of diffusion of the excitation light in the peripheral portion of the surface including the long side. The slab laser according to claim 1, wherein: 4. The liquid crystal mask is irradiated with laser light emitted from the slab laser.
The laser marker according to any one of 3 above.