JP3313623B2 - Gas 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 gas laser oscillating device in which the direction of a tube axis of a discharge tube coincides with the direction of an optical axis, and more particularly to a gas laser oscillating device capable of obtaining a high-quality laser beam.

[0002]

2. Description of the Related Art FIG. 4 is a schematic structural view of a conventional gas laser oscillation device. In this figure, reference numeral 1 denotes a discharge tube made of a dielectric material such as glass, and the discharge tube 1 is filled with a laser gas. Or circulating. Reference numerals 2 and 3 denote electrodes provided at both ends of the discharge tube 1, reference numeral 4 denotes a power source connected to the electrodes 2 and 3, and reference numeral 5 denotes a discharge space in the discharge tube 1 sandwiched between the electrodes 2 and 3.

[0003] Reference numeral 6 denotes a total reflection mirror, 7 denotes a partial reflection mirror, and the total reflection mirror 6 is disposed so as to face one opening of the discharge space 5. They are arranged to face each other, and the total reflection mirror 6 and the partial reflection mirror 7 form an optical resonator. 8 is a partial reflecting mirror 7
Is a laser beam output from

Next, the operation of the conventional gas laser oscillation device configured as described above will be described. First, power supply 4
A discharge is generated in the discharge space 5 from the electrodes 2 and 3 connected to the electrodes. This discharge causes the laser gas in the discharge space 5 to be excited by obtaining discharge energy, and the excited laser gas is brought into a resonance state by the optical resonator formed by the total reflection mirror 6 and the partial reflection mirror 7, thereby causing partial reflection. The mirror 7 outputs a laser beam 8. This laser beam 8 is used for applications such as laser processing.

FIGS. 5A and 5B are diagrams illustrating the operation of an optical resonator in a gas laser oscillation device. In the resonance space 9 formed between the total reflection mirror 6 and the partial reflection mirror 7,
A standing wave 10 is formed by optical resonance. The nature of the standing wave 10 is defined by the curvature of the total reflection mirror 6 and the partial reflection mirror 7 and the size of the resonance space 9. Standing wave 10 here
Is called the mode order, and it is generally known that the lower the mode order, the better the beam focusing property and the higher the processing performance. Specifically, for example, as the inner diameter of the discharge tube 1 becomes smaller, the resonance space 9 becomes narrower and the oscillation of the higher-order mode is suppressed, so that the mode becomes lower-order and the light collecting property is improved, so that the machining performance is improved. A beam is obtained.

[0006]

Here, the mode is reduced to a lower order by reducing the inner diameter of the discharge tube 1 as shown in FIG. 5B with respect to the discharge tube 1 shown in FIG. 5A. However, if the inner diameter of the discharge tube 1 is reduced, the scattered light 8a is likely to be generated, and the scattered light 8a is mixed in a mode as a laser output.

FIG. 6 is a characteristic diagram showing a mode by a conventional gas laser oscillation device. As is clear from FIG.
Scattered light 8a is generated in the peripheral area A of the mode. When laser cutting is performed using the laser beam 8 including such scattered light 8a, the scattered light 8a generated in the peripheral area A causes
The influence of heat around the cut portion is increased, which causes a reduction in cutting quality.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a gas laser oscillation device capable of obtaining a high-quality laser beam while reducing the mode and suppressing scattered light. The purpose is to provide.

[0009]

According to a first aspect of the present invention, there is provided a gas laser oscillating device, wherein a discharge space is filled with a laser gas and at least along a laser beam optical axis. Three or more discharge tubes arranged in series, and disposed opposite to an opening at one end of the discharge space;
A total reflection mirror constituting a final stage mirror, and a partial reflection mirror disposed opposite to the opening at the other end of the discharge space and constituting an output mirror, wherein discharge is generated in the discharge space by the discharge tube. A gas laser oscillator that amplifies light by an optical resonator including the total reflection mirror and the partial reflection mirror and outputs a laser beam in the tube axis direction of the discharge tube through the partial reflection mirror; A spacer through which an opening having a center penetrates is disposed between the partial reflector and the discharge tube disposed at the other end in the optical axis direction, and a pair of spacers are disposed at both ends in the optical axis direction. Is the inner diameter of the discharge tube r ₁ , the sum of the lengths of the pair of discharge tubes in the optical axis direction is L _1, and the inner diameters of the remaining discharge tubes are r ₂ ,
When the sum of the lengths of the remaining discharge tubes is L ₂ and the inner diameter of the opening of the spacer is r ₃ , the relations of the following equations (Equation 4), (Equation 5) and (Equation 6) are simultaneously satisfied. Thus, the discharge tube and the spacer are configured.

[0010]

## EQU4 ## r ₁ / r ₂ > 1.0

[0011]

[Number 5] _{L 2 / (L 1 + L} 2) <0.85

[0012]

R ₃ / r ₂ <1.4 And, according to the gas laser oscillation device according to claim 1,
Since the resonance space formed in the remaining discharge tubes except the pair of discharge tubes arranged at both ends in the optical axis direction is relatively narrowed, the mode of the laser beam is reduced, and one end in the optical axis direction is reduced. Since the scattered light generated in the discharge tube arranged in the portion is blocked by the spacer and is not output to the outside, the scattered light is prevented from being mixed into the laser beam.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a gas laser oscillation device according to an embodiment of the present invention. Members corresponding to the members described based on FIGS. 4 and 5 are denoted by the same reference numerals, and those members are described below. Is omitted. Reference numeral 21 denotes a spacer through which an opening having a predetermined inner diameter passes through the optical axis of the laser beam 8, and a plurality of spacers 22 and 23 arranged in series along the optical axis of the laser beam 8, respectively.
(Six in the figure) discharge tubes, of which a pair of discharge tubes 22 are respectively disposed at one end and the other end in the optical axis direction of the laser beam 8. It is. Further, the spacer 21 is arranged in the middle between the partial reflecting mirror 7 and the discharge tube 22 arranged at the end on the side of the partial reflecting mirror 7.

Here, the inner diameter of a pair of discharge tubes 22 disposed at both ends in the optical axis direction is r ₁ , and the sum of the lengths of the pair of discharge tubes 22 in the optical axis direction is L ₁ (= l _1). + l ₂ ), the inner diameter of the remaining discharge tubes 23 excluding both ends is r ₂ , and the sum of the lengths of these discharge tubes 23 in the optical axis direction is L ₂ (= l ₃ + l ₄
+ l ₅ + l ₆ ) and the inner diameter of the spacer 21 is r ₃ ,
In the gas laser oscillation device of the present embodiment, the following equation (Equation 7) is used.
The discharge tubes 22 and 23 and the spacer 21 are configured so as to simultaneously satisfy the relationship of (Expression 8) and (Expression 9).

[0015]

[Mathematical formula 7] r ₁ / r ₂ > 1.0

[0016]

[Equation 8] _{L 2 / (L 1 + L} 2) <0.85

[0017]

## EQU9 ## r ₃ / r ₂ <1.4 The discharge tubes 22 and 23 and the spacer 21 are expressed by the following equations (7), (8) and
In the case where (Equation 9) is satisfied at the same time, the inner diameter r ₂ of the discharge tube 23 becomes smaller than the inner diameter r ₁ of the discharge tubes 22 arranged at both ends in the optical axis direction of the laser beam 8. Since the resonance space 9 formed in 23 is narrowed relatively to the resonance space 9 in the discharge tube 22, the mode of the laser beam 8 is reduced. on the other hand,
Inner diameter r of discharge tube 22 arranged at both ends in the optical axis direction
_{Since 1} is larger in diameter than the inner diameter r ₂ of the discharge tube 23, when the scattered light 8 a generated in the resonance space 9 in the discharge tube 23 passes through the discharge tube 22, the scattered light 8 a Diverge toward. The scattered light 8a diverging to the outside is
Since it is blocked by the spacer 21 and not output to the outside,
The scattered light 8a is prevented from being mixed into the laser beam. As a result, according to the gas laser oscillating device of the present embodiment, by suppressing the scattered light 8a while reducing the mode, the quality of the laser beam 8 is improved, and the light condensing property when condensed by the condensing lens is improved. Can be significantly improved.

FIG. 2 is a characteristic diagram showing the influence of the inner diameter and length of the discharge tube and the inner diameter of the spacer on the laser beam focusing in this embodiment. In this figure, as a parameter for evaluating the light collecting property, a heat affected width generated from a cut portion when a mild steel is cut was used.

FIG. 2A shows that L ₂ / (L ₁ + L ₂ ) is 0.5, r ₃
The graph shows the correlation between the change in r ₁ / r ₂ and the heat affected width when / r _{2 is set} to 1.0. As is clear from this figure, when the value of r ₁ / r ₂ is larger than 1.0, that is, when the inner diameter r ₁ of the discharge tubes 22 arranged at both ends in the optical axis direction is changed to the inner diameter r ₂ of the remaining discharge tubes 23. It can be seen that, as well as the generation of the scattered light 8a is suppressed, and the width of heat influence in the mild steel is reduced.

FIG. 2B shows that r ₁ / r ₂ is 1.11 and r ₃
The graph shows the correlation between the change of L ₂ / (L ₁ + L ₂ ) and the heat affected width when / r _{2 is set} to 1. As is clear from this figure, as the value of L ₂ / (L ₁ + L ₂ ) becomes 0.85 or more, and the heat affected width increases rapidly, L ₂ / (L
It is understood that a range of less than 0.85 is suitable as the value of ( ₁ + L ₂ ).

FIG. 2C shows that r ₁ / r ₂ is 1.11, L ₂
/ In case of the (L ₁ + L ₂₎ 0.5, which shows the correlation between the change in the heat-affected width of r ₃ / r _2, as is apparent from the figure, the r ₃ / r ₂ By setting the value to less than 1.4, the heat affected width can be sufficiently reduced. This is relative to the inner diameter r ₂ of the discharge tube 23, the inner diameter r ₃ of the spacer 21 is too large, presumably because blocking effect of the scattered light 8a by the spacer 21 is reduced.

FIG. 3 is a characteristic diagram for explaining the effect of the gas laser oscillation device according to the present embodiment, and FIG.
Shows the mode of the laser beam 8 output by the gas laser oscillation device of the present embodiment, and FIG. 3B shows the results of comparing the heat affected widths of mild steel cut by the present embodiment and the conventional gas laser oscillation device. ing.

As is apparent from a comparison between FIG. 3A and FIG. 6, in the laser beam 8 output from the gas laser oscillation device of this embodiment, scattered light 8a is generated even in the peripheral region A of the mode. Without high quality. FIG. 3 (b) shows the relative evaluation of the magnitude of the heat affected width generated when mild steel was cut by the conventional gas laser oscillation device and the gas laser oscillation device of the present embodiment, respectively. A comparative example shows a conventional gas laser oscillation device, and an example shows a gas laser oscillation device of the present embodiment. As is clear from FIG. 3B, according to the gas laser oscillation device of the present embodiment, the heat affected width of the mild steel cut by the laser beam 8 can be significantly reduced as compared with the conventional gas laser oscillation device. As a result, it is possible to greatly improve the processing performance.

[0024]

As described above, according to the first aspect of the present invention,
According to the gas laser oscillation device described, while reducing the mode of the laser beam and preventing the occurrence of scattered light, it is possible to output a high-quality laser beam with high light condensing properties. The heat affected zone generated when cutting mild steel or the like can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a gas laser oscillation device according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing an effect of a discharge tube and a spacer on a laser beam focusing property in the embodiment of the present invention.

FIG. 3 is a characteristic diagram for explaining an effect of the gas laser oscillation device according to the embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a conventional gas laser oscillation device.

FIG. 5 is an operation explanatory view of an optical resonator in a conventional gas laser oscillation device.

FIG. 6 is a characteristic diagram showing modes in a conventional gas laser oscillation device.

[Explanation of symbols]

6: Total reflection mirror, 7: Partial reflection mirror, 8: Laser beam, 8a: Scattered light, 9: Resonant space, 10: Standing wave,
22, 23 ... discharge tube.

Continued on the front page (72) Inventor Satoshi Eguchi 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. References JP-A-9-8386 (JP, A) JP-A-5-63277 (JP, A) Jikken 47-31425 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H01S 3/00-3/30

Claims (1)

(57) [Claims] A discharge space is filled with a laser gas, and at least three or more discharge tubes are arranged in series along the optical axis of the laser beam. A total reflection mirror that constitutes a step mirror, and a partial reflection mirror that is arranged opposite to the opening at the other end of the discharge space and constitutes an output mirror, and generates a discharge in the discharge space by the discharge tube, In a gas laser oscillation device that amplifies light by an optical resonator including the total reflection mirror and the partial reflection mirror and outputs a laser beam in a tube axis direction of the discharge tube through the partial reflection mirror, the optical axis of the laser beam is centered. A spacer penetrated by an opening is disposed in the middle between the partial reflecting mirror and the discharge tube disposed at the other end in the optical axis direction, and a pair of spacers respectively disposed at both ends in the optical axis direction. Inside the discharge tube The r _1, and the sum of the length in the optical axis direction of the pair of the discharge tube with the L _1, r ₂ the inner diameter of the remaining discharge tube, the sum of the length of the remaining discharge tube and L _2, and spacers Wherein, when the inner diameter of the opening is r ₃ , the discharge tube and the spacer are configured so as to simultaneously satisfy the following equations (Equation 1), (Equation 2) and (Equation 3). Laser oscillation device. R ₁ / r ₂ > 1.0 L ₂ / (L ₁ + L ₂ ) <0.85 r ₃ / r ₂ <1.4