JP3254960B2 - Laser oscillation device - 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 oscillating device that excites a laser medium, amplifies light with an optical amplification mirror, and emits a laser beam using one of the optical amplification mirrors as a partially transmitting mirror.

[0002]

2. Description of the Related Art As shown in FIG. 3A, a conventional laser oscillation device excites a laser medium 1 with a power supply 2 for exciting a laser medium, and oscillates a laser beam with mirrors 3a and 3b for optical amplification. 4 had been generated. The two mirrors 3a and 3b for optical amplification maintain the parallelism required for optical amplification by the mirror holder 5, and the mirrors for optical amplification 3a
Is a partially transmitting mirror, the laser beam 4 can be extracted outside between the optical amplification mirrors 3a and 3b.
The laser beam 4 emitted to the outside between the light amplification mirrors 3a and 3b passes through the inside of the laser beam protection introduction tube 6, and is received by the absorber 7.

When the laser beam 4 is taken out from the laser oscillation device for cutting a sheet metal or the like, since the object that blocks the laser beam 4 is eliminated by moving the absorber 7, the laser beam 4 is taken out of the laser oscillation device. It becomes possible. When the laser beam 4 is not taken out, the absorber 7 receives the laser beam 4 so that the laser beam 4 is not emitted to the outside.

The laser beam 4 taken out of the laser oscillation device is condensed by a condensing lens by a processing head (not shown), and is used for processing. However, dirt adheres to the condensing lens. In order to prevent this and protect the lens, there has been a technique of introducing a gas such as nitrogen into the vicinity of the condenser lens (see JP-A-61-286085 and JP-A-3-60890).

Further, an air guide is provided above the mirror surface of the laser mirror to supply compressed air under pressure, and the compressed air is reflected on the inner wall of the air guide to jet the compressed air to the mirror surface, thereby blowing off dust on the mirror surface. (Japanese Unexamined Patent Publication No. Sho 62-3)
No. 5590).

[0006]

In such a conventional laser oscillator, as shown in FIG. 3B, the periphery of the laser oscillator is surrounded by an atmosphere containing impurities 8 such as oil mist. . For this reason, the phenomenon that impurities adhere to a portion of the laser oscillation device that comes into contact with the air has occurred. That is, since the surface of the partially transmitting mirror 3a on the laser beam output side cannot output the laser beam 4 to the outside between the optical amplification mirrors 3a and 3b, it cannot be sealed and must be exposed to the atmosphere. The impurity 8 approaches the laser beam output surface of the partially transmitting mirror 3a,
Had adhered.

As described above, the impurity 8 is partially transmitted through the partial transmission mirror 3.
The refractive index of the mirror is changed by adhering to the surface a on the laser beam output side. The change in the refractive index of the mirror 3a affects the divergence angle of the laser beam 4, and the divergence angle of the laser beam 4 becomes unstable and the laser beam 4 becomes permanently stable.
Could not get.

In laser processing, the diameter of a focused spot where the laser beam 4 is focused through a focusing lens and the beam focusing profile before and after the spot diameter are important factors that determine the quality of processing. Since the spot diameter and the beam focusing profile generally depend on the diameter determined by the divergence angle of the laser beam 4 incident on the focusing lens, the divergence angle is unstable with the conventional nitrogen introduction technology for protecting the focusing lens. There is a drawback that it is not possible to cope with processing defects that occur when the fluctuations occur.

Further, in the above-mentioned conventional example, when the impurity 8 adheres to the condenser lens, the condenser lens is rapidly deteriorated. Therefore, the prior art is merely intended to prevent the condenser lens from being deteriorated. It was not done with a focus on the light collection profile.

[0010] Further, the apparatus that blows off dust with compressed air merely tries to blow off dust by the flow of wind, and does not always maintain the vicinity of the output surface at a pressure higher than the surrounding atmospheric pressure. .

An object of the present invention is to solve the above-mentioned conventional problems and to provide a laser oscillation device capable of obtaining a stable laser beam.

[0012]

In order to achieve the above object, a laser oscillation device according to the present invention comprises at least one pair of mirrors for amplifying a laser beam, and at least one of the mirrors for amplifying a laser beam is partially mirrored. And
The partially transmitting mirror and an absorber for receiving a laser beam;
The inlet tube of the laser beam provided between the pressure of the inlet tube
The pressure was higher than the atmospheric pressure .

Further, a gas cleaning filter is provided between the introduction pipe and the gas introduction means, and the gas permeated through the filter is introduced into the introduction pipe.

[0014]

With the above arrangement, impurities existing in the atmosphere near the output surface of the partially transmitting mirror are kept at a higher pressure than the surrounding atmosphere because the vicinity of the output surface of the partially transmitting mirror is kept at a higher pressure.
It cannot approach the partially transmitting mirror and does not adhere to the output surface of the partially transmitting mirror.

Further, since the supplied gas itself is clean, no impurities adhere to the output surface of the partially transmitting mirror.

In this way, the laser focusing profile can be stabilized and a permanently stable laser beam can be obtained.

[0017]

【Example】

(Embodiment 1) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a laser oscillation device according to the present invention in which the pressure around the optical amplification mirror is higher than the surrounding atmospheric pressure. Note that the same components as those in the conventional example are assigned the same reference numerals, and a detailed description thereof will be omitted.

The air 9 is supplied from the air supply unit 13 to the introduction pipe 6.
To make the pressure near the laser beam output surface of the partially transmitting mirror 3a higher than the surrounding atmosphere.
The impurity 8 such as oil mist existing in the air near the laser beam output surface of the partially transmitting mirror 3a approaches the mirror because the atmospheric pressure near the laser beam output surface of the partially transmitting mirror 3a is higher than the surroundings. And does not adhere to the surface of the mirror on the laser beam output side.

Since the fluid flows from a place where the pressure is high to a place where the pressure is low, the impurities 8 existing in the atmosphere surrounding the laser oscillation device do not approach the vicinity of the laser beam output surface of the partially transmitting mirror 3a, and the output 8 Since it cannot adhere to the surface, the refractive index of the partial transmission mirror 3a and the divergence angle of the laser beam 4 can be maintained in the initial state.

Further, in this embodiment, before introducing the air 9 near the laser beam output surface, the filter 10 is used.
It is filtered.

By removing the impurities 8 contained in the air 9, the effect of preventing the output surface of the partial transmission mirror 3a from being contaminated can be enhanced.

Embodiment 2 Hereinafter, a second embodiment of the present invention will be described.

FIG. 2 is an external view of a second embodiment of the present invention. In this embodiment, instead of the air 9, an inert gas such as nitrogen 11 is introduced from a cylinder 12 filled with high purity into the vicinity of the laser beam output surface. By filling the vicinity of the mirror with an inert gas such as nitrogen 11 instead of the air 9 as described above, the effect of preventing contamination of the output surface of the partial transmission mirror 3a due to a chemical change can be enhanced.

[0024]

As is apparent from the above description, according to the present invention, since the vicinity of the output surface of the partial transmission mirror is maintained at a higher pressure than the surrounding atmosphere, the vicinity of the output surface of the partial transmission mirror is maintained. Impurities present in the atmosphere cannot approach the partially transmitting mirror and do not adhere to the output surface of the partially transmitting mirror.

Further, since the supplied gas itself is clean, dust and the like do not adhere to the output surface of the partially transmitting mirror.

In this way, the laser focusing profile can be stabilized and a permanently stable laser beam can be obtained.

[Brief description of the drawings]

FIG. 1 is an external view of a laser oscillation device according to a first embodiment of the present invention.

FIG. 2 is an external view of a laser oscillation device according to a second embodiment of the present invention.

FIG. 3 is an external view of a conventional laser oscillation device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser medium 2 Laser medium excitation power supply 3a Partial transmission mirror 3b Optical amplification mirror 4 Laser beam 5 Mirror holder 6 Introductory tube 7 Absorber 8 Impurities 9 Air 10 Filter 11 Nitrogen 12 Bomb 13 Air supply

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-196494 (JP, A) JP-A-61-286085 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01S 3/00-3/30

Claims (4)

(57) [Claims] A mirror for amplifying the laser beam, wherein at least one of the mirrors for amplifying the laser beam is a partially transmissive mirror and
A laser light introduction pipe is provided between the laser beam and the absorber that receives the laser beam, and the pressure in the introduction pipe is set to a pressure higher than the atmospheric pressure.
Laser oscillation device that. 2. The laser oscillation device according to claim 1, further comprising a laser light introducing pipe provided near the output surface of the partially transmitting mirror, and gas introducing means for introducing a gas having a pressure higher than the surrounding atmospheric pressure into the introducing pipe. apparatus. 3. The laser oscillation device according to claim 2, further comprising a filter for purifying gas between the introduction pipe and the gas introduction means, and introducing gas permeated through the filter into the introduction pipe. 4. The laser oscillation device according to claim 1, wherein an inert gas is used as the gas.