JP2013080743A - Laser oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser oscillator capable of efficiently exciting laser gas in a discharge tube from substantially the entire outer peripheral surface of the discharge tube by spirally disposing a waveguide around the discharge tube.SOLUTION: A laser oscillator 1 oscillating laser light L by exciting laser gas with microwaves comprises a cylindrical discharge tube 3 containing laser gas, laser oscillators 31A, 31B each having a resonator consisting of a front mirror and a rear mirror, a microwave generator 15 generating microwaves, and a waveguide 17 which guides the microwaves generated from the microwave generator to the discharge tube. The waveguide 17 is arranged spirally on the outer peripheral surface of the discharge tube 3, and a plurality of slits are provided in the waveguide. The laser gas contained in the discharge tube 3 can be excited efficiently by radiating microwaves radially inward of the discharge tube 3 from substantially the entire outer peripheral surface thereof.

Description

  The present invention relates to a laser oscillation device, and more particularly to a laser oscillation device in which a laser gas in a discharge tube is excited by microwaves generated by a microwave generator to oscillate laser light.

  Conventionally, as a laser oscillation device, a cylindrical discharge tube containing laser gas therein, a laser oscillator having a resonator composed of a front mirror and a rear mirror, a microwave generator for generating a microwave, and the microwave And a waveguide that radiates the microwave generated by the wave generator and radiates into the discharge tube, and excites the laser gas in the discharge tube by the microwave and oscillates the laser beam by the laser oscillator What was made is known (patent document 1).

JP 2007-295003 A

Since the waveguide of the laser oscillation device is arranged on one side of the discharge tube in parallel therewith, the laser gas in the discharge tube is excited only from the one side, and efficient excitation is performed. I could not.
In view of such circumstances, the present invention can efficiently excite the laser gas in the discharge tube from substantially the entire outer peripheral surface of the discharge tube by arranging the waveguide spirally around the discharge tube. A laser oscillation device is provided.

That is, the present invention relates to a cylindrical discharge tube containing laser gas therein, a laser oscillator having a resonator composed of a front mirror and a rear mirror, a microwave generator for generating microwaves, and the microwave generation And a waveguide that radiates into the discharge tube, and excites a laser gas in the discharge tube by the microwave, and oscillates the laser light by the laser oscillator. In the laser oscillation device
The waveguide is spirally arranged on the outer peripheral surface of the discharge tube, and a plurality of slits are provided in the waveguide, and microwaves are emitted from the slits into the discharge tube to excite laser gas. Is.

  According to the present invention, the microwave generated by the microwave generator can be guided along the outer peripheral surface of the discharge tube by the helical waveguide, and provided in the waveguide. Since the laser gas can be excited by emitting microwaves from the outer peripheral surface of the discharge tube to the inside of the discharge tube through the slit, the laser gas can be excited efficiently.

The horizontal sectional view showing the example of the present invention. Sectional drawing which follows the II-II line | wire of FIG. Sectional drawing which follows the III-III line of FIG. Sectional drawing which follows the IV-IV line of FIG. Sectional drawing which follows the VV line of FIG. Sectional drawing which follows the VI-VI line of FIG. Sectional drawing which shows only the cylindrical part 18 of FIG. The expanded view which expands and shows the cylindrical part 18 of FIG. The perspective view which shows 31 A of laser oscillators integrated in the discharge tube 3. FIG. The perspective view which shows the laser oscillator 31B integrated in the discharge tube 3. FIG.

The present invention will be described below with reference to the illustrated embodiment. In FIG. 1, a laser oscillation device 1 includes a horizontally elongated casing 2 (see FIG. 2) a casing 2 and a glass cylinder disposed at the center of the casing 2. And a gas circulation passage 4 that circulates and supplies laser gas into the discharge tube 3 in the casing 2.
In this embodiment, the discharge tube 3 is composed of two discharge tubes 3a and 3b arranged in a line in the axial direction, and each end of the two discharge tubes 3a and 3b is fixed to the casing 2 respectively. The support member 5 is supported.

The gas circulation passage 4 includes an outlet passage 4a formed between the two discharge tubes 3a and 3b, and the laser gas flowing through the discharge tubes 3a and 3b is discharged from the outlet of each discharge tube to the outlet passage. It flows to 4a, and is divided into right and left (vertical direction in FIG. 1) by this exit passage 4a.
The laser gas that has been split left and right in the outlet passage 4a flows to both ends of the casing 2 through a total of four communication passages 4b formed close to the left and right of the two discharge tubes 3a and 3b. The gas flows into the inlets of the discharge tubes 3a and 3b via the inlet passages 4c formed at both ends of the laser beam 2 so that the laser gas is accommodated inside the discharge tubes 3a and 3b.
Therefore, in this embodiment, the gas circulation passage 4 is constituted by the outlet passage 4a, the communication passage 4b, the inlet passage 4c, and the discharge tubes 3a and 3b, and the gas circulation passage 4 allows the laser gas to circulate. I can do it.
Further, as shown in FIGS. 1 and 5, guide fins 6 for forming a swirl flow are provided at the inlets of the discharge tubes 3 a and 3 b, and swirl flows when the laser gas flows through the guide fins 6. Is provided so as to circulate in each of the discharge tubes 3a and 3b.

The outlet passage 4a is provided with heat exchangers 8 at positions on both sides outside the two discharge tubes 3a and 3b so that the laser gas can be cooled by each heat exchanger 8. is there.
Each communication passage 4b is provided with a cross flow fan (cross flow blower) 9 and a vacuum motor 10 for rotationally driving the cross flow fan 9. By rotating the cross flow fan 9 with each vacuum motor 10, the laser gas is supplied to the communication passage 4b. The communication passage 4b can be made to flow from the outlet passage 4a to the inlet passage 4c.

As shown in FIGS. 2 to 5, each communication passage 4 b has a width in the vertical direction that is slightly larger than the diameter of the cross flow fan 9, but the width in the left and right direction is the cross flow fan. The cross flow fan 9 can be disposed obliquely in each communication passage 4b.
Each crossflow fan 9 is arranged such that the end portion on the side of each inlet passage 4 c protrudes in the axial direction from the inlet of the discharge tube 3, and is separated from the discharge tube 3 on the inlet side of the discharge tube 3. The discharge tube 3 is disposed obliquely so as to be close to the discharge tube 3 on the outlet side. Thereby, an inflow portion 4b-i having a triangular horizontal section defined by the cross flow fan 9 is formed on the upstream side of the cross flow fan 9 in each communication passage 4b, that is, on the outlet passage 4a side.
On the other hand, on the downstream side of the cross flow fan 9 in each communication passage 4b, that is, on the inlet passage 4c side, a horizontal cross section defined by the cross flow fan 9 forms a triangular outflow portion 4b-o, thereby The laser gas can be circulated obliquely in the axial direction from one side to the other side of the crossflow fan 9 from the inflow part 4b-i to the inflow part 4b-o.

As described above, in this embodiment, the communication passage 4b is not formed in a direction orthogonal to the discharge tube 3, but is formed in a parallel direction so as to be close to each other via the outlet passage 4a. Since the fan 9 is arranged obliquely, the laser oscillation device 1 can be manufactured in a small size.
Further, since the cross flow fan 9 does not increase the pressure of the laser gas, the compression does not raise the temperature of the laser gas, and therefore there is no need to provide an auxiliary heat exchanger on the outlet side of the cross flow fan 9. On the other hand, since the cross flow fan 9 can be increased in axial length along the longitudinal direction in each communication passage 4b, a sufficient amount of laser gas blown can be ensured.

Further, the end portion on the inlet passage 4c side of the cross flow fan 9 is arranged so as to protrude in the axial direction from the inlet of the discharge tube 3 as described above, and the outlet passage 4a side is close to the discharge tube 3 so as to be close to the discharge tube 3. Since the inlet passage 4c side is disposed obliquely so as to be separated from the discharge tube 3, the outflow portion 4b-o having a triangular horizontal cross section can be directly communicated with the inlet passage 4c, and the laser oscillation device 1 can be reduced in size. Can be manufactured.
That is, when the cross flow fan 9 is disposed obliquely opposite to the above, the outflow portion 4b-o cannot directly communicate with the inlet passage 4c, so that the position beyond the end of the cross flow fan 9 is reached. In addition, a space for communicating the outflow portion 4b-o and the inlet passage 4c is required, which is not desirable.

Next, the excitation means 14 (FIG. 6) for exciting the laser gas flowing through the discharge tube 3 will be described.
As shown in FIG. 6, the excitation means 14 includes a microwave generator 15 for generating a microwave, a high-voltage power supply 16 for the microwave generator 15, and a waveguide 17 connected to the microwave generator 15. These two sets are provided in the casing 2 for each of the discharge tubes 3a and 3b.
Each of the waveguides 17 is made of copper or aluminum, and has a cylindrical cylindrical portion 18 fitted on the outer periphery of each of the two discharge tubes 3a and 3b, and an outer periphery of each cylindrical portion 18 respectively. A spiral portion 19 having a U-shaped cross section wound spirally so as to be in the same direction, and a connection portion 20 having a rectangular cross section for connecting each spiral portion 19 and each microwave generator 15 (see FIG. 1).
A large number of slits 21 are formed in the cylindrical portion 18 at a position inside the spiral portion 19 with a predetermined gap along the spiral direction of the spiral portion 19 (see FIG. 7). The microwave generated by the wave generator 15 can be radiated into the discharge tube 3 from each slit 21 via the waveguide 17.

Further, a large number of permanent magnets 24 as magnetic field generating means are provided on the outer periphery of each cylindrical portion 18, and these permanent magnets 24 are arranged along the spiral direction at an intermediate position of each spiral portion 19. It is.
FIG. 8 shows a developed view of each cylindrical portion 18, and as can be understood from FIG. 8, the plurality of permanent magnets 24 constituting the first thread of the spiral are such that each N pole has a radius of the cylindrical portion 18. The S pole is arranged inward in the direction so that it is radially outward.
Further, the plurality of permanent magnets 24 constituting the second thread of the spiral are separated from the first permanent magnet 24 by a space 25 corresponding to one permanent magnet 24, and each S pole is opposite to the first thread. The N pole is disposed radially inward of the cylindrical portion 18 so as to be radially outward.
In this way, the polarities of the S pole and the N pole are arranged in reverse for each strip, whereby adjacent permanent magnets 24 are arranged along the axial direction of the discharge tube 3 located in each cylindrical portion 18. Are arranged so that the polarities are alternately reversed (see FIG. 1), a magnetic field along the axial direction is generated inside each discharge tube 3a, 3b, thereby causing electrons in the discharge tubes 3a, 3b. Cyclotron resonance can be generated.

Next, the laser oscillator incorporated in the discharge tube 3 will be described. As this laser oscillator, those having various known configurations can be used.
The laser oscillator shown in FIG. 9 is a conventionally known MOPA type laser oscillator 31A, a resonator 32 that resonates and oscillates laser light L between a front mirror and a rear mirror, and is emitted from the resonator 32. And an amplifier 33 for amplifying the laser light L.

The resonator 32 oscillates from the front mirror 35 and the rear mirror 36 provided on the central axis of the discharge tube 3, the Q switch 37 provided between the front mirror 35 and the rear mirror 36, and the front mirror 35. And a first bend mirror 38 for guiding the laser beam L to the amplifying unit 33 to constitute an MO unit (oscillation unit) in the MOPA type laser oscillator 31A.
The front mirror 35 and the rear mirror 36 are arranged so as to sandwich an excitation region formed inside the discharge tube 3. The front mirror 35 transmits only laser light L exceeding a predetermined output, and the rear mirror 36 The laser beam L is totally reflected.
The first bend mirror 38 is provided at the end of the discharge tube 3 on the side of the front mirror 35 and on the central axis of the discharge tube 3, and the laser light L transmitted through the front mirror 35 is transmitted to the outer periphery of the discharge tube 3. Reflected toward the side.

The amplifying unit 33 includes a second bend mirror 39 for reflecting the laser beam L emitted from the first bend mirror 38 of the resonator 32 in the axial direction and receiving it in the amplifying unit 33, and The first to sixth reflecting mirrors 40A to 40F that reflect the laser beam L, and an output window 41 that is provided at one end of the discharge tube 3 and transmits the laser beam L to the outside, include the PA in the MOPA type laser oscillator 31A. Part (amplifying part).
The first, third, and fifth reflecting mirrors 40A, 40C, and 40E and the output window 41 are provided at the end of the discharge tube 3 on the rear mirror 36 side so as to surround the rear mirror 36, and the second, second, 4. The sixth reflection mirrors 40B, 40D, and 40F are provided at the end portion on the front mirror 35 side so as to surround the front mirror 35.
The first reflection mirror 40A reflects the laser light L guided from the first bend mirror 38 of the resonator 32 through the second bend mirror 39 to the second reflection mirror 40B on the front mirror 35 side, Thereafter, the second to sixth reflection mirrors 40B to 40F also reflect the laser light L toward the opposite end of the discharge tube 3, whereby the laser light L is in the order of the first to sixth reflection mirrors 40A to 40F. The light is guided while being reflected, amplified during this time, and finally transmitted through the output window 41.

The laser oscillator shown in FIG. 10 is a conventionally known multi-pass laser oscillator 31B, which includes a front mirror, a rear mirror, and a plurality of reflecting mirrors, and is provided between the front mirror and the rear mirror via the plurality of reflecting mirrors. The laser beam is oscillated.
That is, the laser oscillator 31B includes a front mirror 43, a rear mirror 44, and three reflecting mirrors 46A to 46C at the left end of the discharge tube 3. These three reflecting mirrors 46A to 46C are arranged at equidistant positions in the circumferential direction along the inner peripheral surface of the discharge tube 3, and the rear mirror 44 is located at the center of these reflecting mirrors 46A to 46C, that is, the discharge tube 3. It is arranged at the axial center.
On the other hand, a bend mirror 47 and a polarizing mirror 48 are provided at the right end of the discharge tube 3, and three reflecting mirrors 46D to 46F are provided. The three reflecting mirrors 46D to 46F are arranged so as to face the three reflecting mirrors 46A to 46C and the front mirror 43, and are arranged at equal intervals in the circumferential direction of the discharge tube 3. The polarizing mirror 48 is disposed at an inclination of 45 degrees on the extension line of the axial center of the discharge tube 3, and the bend mirror 47 is disposed at a position shifted radially outward from the polarizing mirror 48.

In the laser oscillator 31B having such a configuration, the laser beam L excited inside the discharge tube 3 is reflected by the rear mirror 44 and is reflected toward the bend mirror 47 via the polarizing mirror 48. Are reflected toward the left reflecting mirror 46A and then reflected toward the right reflecting mirror 46D.
Thereafter, the laser beam L is alternately and alternately disposed along the inner peripheral surface of the discharge tube 3 between the left reflecting mirrors 46B and 46C and the right reflecting mirrors 46E and 46F provided at substantially opposite positions thereof. The laser beam L that is reflected and reflected to the front mirror 43 is reflected in the opposite direction to the optical path up to that point.
Therefore, the laser beam L is reflected and resonated a plurality of times between the front mirror 43 and the rear mirror 44 via the plurality of reflecting mirrors 46A to 46F, the bend mirror 47 and the polarizing mirror 48, The laser beam L whose output has been raised by the transmission light passes through the front mirror 43 and oscillates outside the discharge tube 3.

According to the above configuration, the microwave generated by the microwave generator 15 is guided into the spiral portion 19 through the connection portion 20 of the waveguide 17, and a large number of the portions provided in the cylindrical portion 18 are provided. It is possible to excite the laser gas accommodated in the discharge tube 3 by radiating microwaves from substantially the entire outer peripheral surface of the discharge tube 3 through the circumferential slit 21 toward the inside in the radial direction of the discharge tube 3. Therefore, the laser gas can be excited efficiently.
In this embodiment, a large number of permanent magnets 24 are arranged along the spiral direction at an intermediate position of each spiral portion 19, so that electron cyclotron resonance can be generated in the discharge tube 3 and more efficiently. The laser gas can be excited.
In particular, when the MOPA type laser oscillator 31A or the multipath type laser oscillator 31B is used as the laser oscillator, the diameter of the discharge tube 3 becomes large, so that it is difficult to uniformly and efficiently excite the laser gas flowing therethrough. However, if the laser gas can be excited from substantially the entire outer peripheral surface of the discharge tube 3, and if electron cyclotron resonance can be further generated, the laser gas can be efficiently excited also in such laser oscillators 31A and 31B. be able to.

In the above embodiment, the spiral portion of the waveguide 17 is composed of the cylindrical portion 18 and the spiral portion 19 having a U-shaped cross section, but the cylindrical portion 18 is omitted and the spiral portion having a U-shaped cross section is omitted. 19 may be constituted by a spiral portion having a square cross section in which the opening portion on the discharge tube 3 side is closed. In this case, what is necessary is just to form the slit 21 in the part which closed the opening part.
In this case, the discharge tube 3 is exposed to the outside between the strips of the spiral portion, and the microwave leaks to the outside from the exposed portion. Therefore, this portion is covered with a metal plate or the like. Alternatively, the exposed portion may be covered with a permanent magnet 24.

  When the discharge tube 3 is made of copper or aluminum, a part of the discharge tube 3 can be used as a part of the cylindrical portion 18. In this case, since the laser gas in the discharge tube 3 flows out into the waveguide 17 through the slit 21 of the cylindrical portion 18 constituting a part of the discharge tube 3, a microwave is applied to prevent this. What is necessary is just to close this slit 21 with closing members, such as glass to let it pass.

Further, the magnetic field generating means is not limited to the permanent magnet 24 but may be an electromagnet, and the electric wire is spirally wound around the discharge tube 3 along the spiral portion 19 of the waveguide 17 so that the electric wire is Alternatively, a magnetic field along the axial direction of the discharge tube 3 may be generated by passing a current through the.
As another example of the laser oscillator incorporated in the discharge tube 3, a multipath laser oscillator may be configured by a resonator in which a front mirror and a rear mirror are axicon mirrors and parabolic mirrors.

DESCRIPTION OF SYMBOLS 1 Laser oscillation apparatus 2 Casing 3, 3a, 3b Discharge tube 4 Gas circulation channel 4a Outlet channel 4b Communication channel 4b-i Inflow part 4b-o Outflow part 9 Crossflow fan 15 Microwave generator 17 Waveguide 18 Cylindrical part 19 Spiral part 20 Connection part 21 Slit 24 Permanent magnet (magnetic field generating means)
31A, 31B Laser oscillator L Laser light

Claims (5)

A cylindrical discharge tube containing laser gas inside, a laser oscillator having a resonator composed of a front mirror and a rear mirror, a microwave generator for generating a microwave, and a microwave generator generated by the microwave generator In a laser oscillation apparatus comprising a waveguide for guiding microwaves and radiating into the discharge tube, wherein the laser gas in the discharge tube is excited by the microwaves and laser light is oscillated by the laser oscillator. ,
The waveguide is spirally arranged on the outer peripheral surface of the discharge tube, and a plurality of slits are provided in the waveguide, and microwaves are emitted from the slits into the discharge tube to excite laser gas. Laser oscillation device.   2. The laser oscillation apparatus according to claim 1, wherein a magnetic field generating means for generating a magnetic field is provided inside the discharge tube to generate electron cyclotron resonance in the discharge tube.   3. The laser oscillation device according to claim 2, wherein the magnetic field generating means is provided in a spiral shape in parallel with the waveguides arranged in a spiral shape.   The laser oscillator includes a resonator composed of the front mirror and the rear mirror, and an amplifier for amplifying the laser beam oscillated from the resonator and amplifying the light by passing it through the discharge tube. The laser oscillation device according to any one of claims 1 to 3, wherein the laser oscillation device is an oscillator.   The laser oscillator includes the front mirror, a rear mirror, and a reflection mirror, and guides laser light between the front mirror and the rear mirror via the reflection mirror and passes the inside of the discharge tube a plurality of times. 4. The laser oscillation apparatus according to claim 1, wherein the laser oscillation apparatus is a multipath laser oscillator that oscillates.

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