JP2010021486A - Laser oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser oscillator easy to assemble and adjust, and high in output efficiency. <P>SOLUTION: For an excitation region R filled with a laser gas, a resonator is provided with: an output mirror 2 arranged on the optical axis of laser light; a first reflection means 3 arranged on the side opposite to the output mirror 2 by interposing the excitation region, and formed with ring-like first-third reflecting surfaces 3a-3c inclined with respect to the optical axis C; and a second reflection means 4 arranged on the output mirror 2 side in the excitation region, and formed with ring-like fourth and fifth reflecting surfaces 4b and 4c inclined with respect to a through-hole 4a and the optical axis C. When the excitation region R is excited, the laser light L reflected by the output mirror 2 is reflected in the order of the first reflecting surface 3c, the second reflecting surface 3b, the fourth reflecting surface 4b, the fifth reflecting surface 4c, the third reflecting surface 3c, the third reflecting surface 3c, the fifth reflecting surface 4c, the fourth reflecting surface 4b, the second reflecting surface 3b, the first reflecting surface 3a and the output mirror 2. The laser oscillator easy to assemble and adjust and high in output efficiency can be provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser oscillator, and more particularly to a laser oscillator having an excitation region that generates laser light by excitation and a resonator that forms an optical path of the laser light so as to pass through the excitation region.

2. Description of the Related Art Conventionally, there has been known a laser oscillator including an excitation region that generates laser light by excitation and a resonator that forms an optical path of the laser light so as to pass through the excitation region.
As such a laser oscillator, one having an output mirror, a rear mirror, and a plurality of reflecting mirrors as resonators at both ends of an excitation region filled with a laser gas is known (Patent Document 1).
According to the laser oscillator disclosed in Patent Document 1, the optical path of the laser beam formed between the output mirror and the rear mirror is reflected by the reflecting mirror a plurality of times, and the laser beam is reflected a plurality of times. Since it passes through the excitation region, it is possible to obtain a high-power laser beam.
Further, a laser oscillator including a double axicon mirror (waxicon mirror) having two inclined reflecting surfaces formed in a ring shape around the optical axis of laser light is known as a resonator (Patent Document 2). ).
According to the laser oscillator of Patent Document 2, it is possible to output ring-shaped laser light from the output mirror by reflecting the laser light with the double axicon mirror.
Japanese Patent No. 2715744 Japanese Patent Publication No. 7-38471

However, the laser oscillator of Patent Document 1 has a problem that it takes time to perform alignment work when the number of reflecting mirrors is large, and there are many portions where the laser beam does not pass through the excitation region, so that the internal gain can be extracted efficiently. There was also a problem that it was difficult.
The laser oscillator disclosed in Patent Document 2 uses a cylindrical laser medium as a pumping region, and laser light in the resonator passes most of the pumping region. Therefore, although the output efficiency is good, the laser medium is cylindrical. The device cost is increased because it is very difficult to manufacture in a shape, and the intensity distribution of the output laser beam is non-uniform because the optical path in the resonator formed in the excitation region passes only the same part. There was a problem of becoming something.
In view of these problems, the present invention provides a laser oscillator that is easy to assemble and adjust and that has high output efficiency.

That is, the laser oscillator according to claim 1 is a laser oscillator having an excitation region that generates laser light by excitation and a resonator that forms an optical path of the laser light so as to pass through the excitation region.
The resonator is provided on the optical axis of the laser beam, and an output mirror that transmits a part of the laser beam generated in the excitation region, and a first that is provided on the opposite side of the output mirror across the excitation region. The reflecting means and the second reflecting means provided on the output mirror side of the excitation region,
The first reflecting means includes a ring-shaped first reflecting surface inclined to face the outer side of the optical axis, and a ring-shaped first reflecting surface surrounding the first reflecting surface and inclined to face the optical axis side. A ring-like shape surrounding the two reflecting surfaces and at least one pair of the first and second reflecting surfaces, being located closer to the second reflecting means than the first and second reflecting surfaces, and inclined toward the optical axis side A third reflective surface,
The second reflecting means includes a through-hole through which laser light passes, a ring-shaped fourth reflecting surface that surrounds the through-hole and is inclined to face the outside of the optical axis, and surrounds the fourth reflecting surface. And the same number of sets of ring-shaped fifth reflecting surfaces inclined to face the optical axis side as the first and second reflecting surfaces,
A first reflecting surface located at the innermost periphery of the first reflecting means is disposed at a position facing the output mirror, each fourth reflecting surface is disposed at a position facing each second reflecting surface, and third reflecting is performed. A fifth reflecting surface located on the outermost periphery of the second reflecting means is arranged at a position facing the surface.

According to a second aspect of the present invention, there is provided a laser oscillator comprising: an excitation region that generates laser light by excitation; and a resonator that forms an optical path of the laser light so as to pass through the excitation region.
The resonator is provided on the optical axis of the laser beam, and an output mirror that transmits a part of the laser beam generated in the excitation region, and a first that is provided on the opposite side of the output mirror across the excitation region. The reflecting means and the second reflecting means provided on the output mirror side of the excitation region,
The first reflecting means includes a ring-shaped first reflecting surface inclined to face the outer side of the optical axis, and a ring-shaped first reflecting surface surrounding the first reflecting surface and inclined to face the optical axis side. Two reflective surfaces,
The second reflecting means includes a through hole through which laser light passes, and a ring-shaped third reflecting surface that surrounds the through hole and is inclined so as to face the optical axis side,
The first reflecting surface is disposed at a position facing the output mirror, and the third reflecting surface is disposed at a position facing the second reflecting surface.

Furthermore, the laser oscillator according to claim 3 is a laser oscillator having an excitation region that generates laser light by excitation and a resonator that forms an optical path of the laser beam so as to pass through the excitation region.
The resonator is provided on the optical axis of the laser beam, and an output mirror that transmits a part of the laser beam generated in the excitation region, and a first that is provided on the opposite side of the output mirror across the excitation region. The reflecting means and the second reflecting means provided on the output mirror side of the excitation region,
The first reflecting means includes a ring-shaped first reflecting surface inclined to face the outer side of the optical axis, and a ring-shaped first reflecting surface surrounding the first reflecting surface and inclined to face the optical axis side. 2 sets of 2 reflective surfaces are provided,
The second reflecting means includes a through-hole through which laser light passes, a ring-shaped third reflecting surface that surrounds the through-hole and is inclined so as to face the outside of the optical axis, and surrounds the third reflecting surface. And surrounding the ring-shaped fourth reflecting surface inclined so as to face the optical axis side, and the third and fourth reflecting surfaces formed by a smaller number than the first and second reflecting surfaces. 3, a ring-shaped fifth reflecting surface that is located closer to the first reflecting means than the fourth reflecting surface and is inclined so as to face the optical axis side,
A first reflecting surface located at the innermost circumference of the first reflecting means is disposed at a position facing the output mirror, each third reflecting surface is disposed at a position facing each second reflecting surface, and a fifth reflecting surface. The second reflecting surface located on the outermost periphery of the first reflecting means is disposed at a position facing the first reflecting means.

According to the laser oscillator of the first to third aspects, the first reflecting means and the second reflecting means forming the optical path of the laser light in the resonator fold the incident light in the direction opposite to the incident direction. This is a so-called retroreflective optical system.
For this reason, the alignment work of the first reflecting means and the second reflecting means is facilitated, and a slight misalignment is allowed.
In addition, the optical path of the laser light in the resonator passes through different parts in the excitation region during one pass until the laser light is reflected by the output mirror and returns to the output mirror again. The internal gain can be taken out efficiently, and a high-power laser beam can be emitted.

The illustrated embodiment will be described below. FIG. 1 shows a gas laser oscillator 1 according to the first embodiment. An output mirror 2 provided at one end of a laser cavity (not shown) filled with a laser gas, and an output mirror 2 of the laser cavity. 1 comprises a first reflecting means 3 provided at the opposite end and a second reflecting means 4 provided at the output mirror 2 side end of the laser cavity.
The laser cavity has a cylindrical shape, and the output mirror 2 and the first and second reflecting means 3 and 4 are attached to the end portions of the laser cavity in a state of being kept airtight.
A laser gas mainly composed of CO ₂ , N ₂ , and He is sealed in the laser cavity, and the laser gas is illustrated to be excited to discharge near the first and second reflecting means 3 and 4 of the laser cavity. Discharge electrodes that are not to be installed are provided, and a discharge space by the discharge electrodes forms an excitation region R indicated by a broken line in the figure.
A resonator is constituted by the output mirror 2 and the first and second reflecting means 3 and 4 so that the optical path of the laser light L passes through the excitation region R a plurality of times.
That is, when the laser gas in the laser cavity is discharged and excited by the discharge electrode, the laser light generated in the excitation region R is repeatedly reflected and amplified between the output mirror 2, the first and second reflecting means 3, 4, It is output from the output mirror 2 which is a partial reflection mirror.
The output mirror 2 is installed coaxially with the center axis of the laser cavity, and the optical axis C of the laser light L output from the output mirror 2 passes through the center of the output mirror 2.

The first reflecting means 3 is a substantially disc-shaped waxycon mirror, which is installed coaxially with the optical axis C, which is the central axis of the laser cavity and the output mirror 2, and reflects the laser light L on the excitation region R side. A first reflecting surface 3a, a second reflecting surface 3b, and a third reflecting surface 3c are formed.
The first reflecting surface 3a is a ring-shaped inclined surface formed in the center. The first reflecting surface 3a is disposed at a position facing the output mirror 2 and is 45 ° with respect to the optical axis C. It is formed to face outward at an angle.
The second reflecting surface 3b is a ring-shaped inclined surface formed so as to surround the outer periphery of the first reflecting surface 3a. The second reflecting surface 3b is perpendicular to the first reflecting surface 3a and faces inward in the radial cross section. Is formed.
The third reflecting surface 3c is a ring-shaped inclined surface formed so as to surround the outer periphery of the second reflecting surface 3b.
Further, the third reflecting surface 3c has a configuration in which the second reflecting surface 3b is extended as it is toward the output mirror 2, and the third reflecting surface 3c is more than the first and second reflecting surfaces 3a and 3b. It is formed on the output mirror 2 side.

The second reflecting means 4 is a substantially disc-shaped waxy mirror having a through-hole 4a formed in the center thereof, and is installed coaxially with the optical axis C, which is the central axis of the laser cavity and the output mirror 2, so that the excitation region On the R side, a fourth reflecting surface 4b and a fifth reflecting surface 4c for reflecting the laser beam L are formed.
The through-hole 4a is formed to have a diameter slightly larger than the diameter of the laser beam L emitted from the output mirror 2, and the optical axis direction of the laser beam L with respect to the first reflecting surface 3a of the first reflecting means 3 It is formed in the position which opposes.
The fourth reflecting surface 4b is a ring-shaped inclined surface formed so as to surround the outer periphery of the through hole 4a, and is formed to face outward at an angle of 45 ° with respect to the optical axis C. It is formed at a position facing the second reflecting surface 3 b of the first reflecting means 3.
The fifth reflecting surface 4c is a ring-shaped inclined surface formed so as to surround the outer periphery of the fourth reflecting surface 4b, and faces the inside so as to be orthogonal to the fourth reflecting surface 4b in the radial cross section. And is formed at a position facing the third reflecting surface 3 c of the first reflecting means 3.

The emission of the laser beam L by the laser oscillator 1 having the above configuration will be described.
First, the laser gas in the laser cavity is discharge-excited to generate laser light L from the excitation region R, and the following optical path is formed in the resonator composed of the output mirror 2, the first and second reflecting means 3, 4. It is formed.
The optical path of the laser light L after the laser light L is reflected by the output mirror 2 will be described in order. First, the laser light L passes through the through hole 4a and the excitation region R of the second reflecting means 4 and is first reflected. It proceeds to the first reflecting surface 3a of the means 3 (1).
Here, the laser beam L has a diameter that can pass through the through hole 4a.
Since the first reflective surface 3a is inclined toward the outside of the optical axis C, the laser light L is reflected outward and further reflected in the direction of the optical axis C by the second reflective surface 3b. As a result, the laser light L travels toward the fourth reflecting surface 4b of the second reflecting means 4 (2).
Here, the laser beam L passing through the optical path (2) has a ring shape with a larger diameter than that of the optical path (1), and passes through the outer excitation region R than in the case of (1). It is like that.
Since the fourth reflective surface 4b is inclined toward the outside of the optical axis C, the laser light L is reflected outward and further reflected in the direction of the optical axis C by the fifth reflective surface 4c. As a result, the laser light L travels toward the third reflecting surface 3c of the first reflecting means 3 (3).
Here, the laser beam L that passes through the optical path (3) has a larger ring shape than the optical path (2), and passes through the excitation region R that is outside the case of (2). It is supposed to be.

And since the 3rd reflective surface 3c inclines toward the inner side of the optical axis C, and is formed in the output mirror 2 side rather than the 1st, 2nd reflective surfaces 3a and 3b, the laser beam L is inside. In addition to being reflected toward the optical axis C, it is reflected again in the direction of the optical axis C by the third reflecting surface 3c beyond the optical axis C. As a result, the laser light L travels toward the fifth reflecting surface 4c of the second reflecting means 4 (4).
At this time, although the laser beam L has a ring shape with the same diameter as the optical path (3), the traveling direction is opposite to that of the optical path (3).
The laser beam L reflected by the fifth reflecting surface 4c is reflected in the direction of the optical axis C by the fourth reflecting surface 4b and proceeds to the second reflecting surface 3b of the first reflecting means 3 (5). At this time, the diameter of the laser beam L is the same as that in the above (2).
The laser beam L reflected by the second reflecting surface 3b is then reflected by the first reflecting surface 3a in the direction of the optical axis C and returns to the output mirror 2 (6). At this time, the diameter of the laser beam L is the same as that in the above (1).
Since the first and second reflecting means 3 and 4 are regressive reflection type optical systems, even if their center lines are slightly inclined with respect to the optical axis C, (1) to (2), In the return of the laser beam L from (2) to (3), (3) to (4), (4) to (5), and (5) to (6), the incident direction and the emission direction are always parallel. Therefore, the laser light L in each optical path has a ring shape coaxial with the optical axis C, and a slight misalignment is allowed.

As described above, according to the resonator including the output mirror 2 and the first and second reflecting means 3 and 4, one pass until the laser light L is reflected by the output mirror 2 and returns to the output mirror 2 again. In the meantime, each of the inside and outside regions of the excitation region R is passed twice for a total of 6 times.
Each time the laser beam L passes through the excitation region R, the gain of the laser beam L is amplified, and the output mirror 2 transmits a part of the laser beam L and emits it. It is designed to reflect on the back.
The first to fifth reflecting surfaces 3a to 4c formed on the first and second reflecting means 3 and 4 are all ring-shaped inclined surfaces formed around the optical axis C of the laser beam L. For this reason, the laser beam L reflected by these reflecting surfaces has a ring shape.
Therefore, the laser beam L emitted from the output mirror 2 has a ring-shaped peak when the intensity distribution immediately after passing through the output mirror 2 is seen. However, by moving away from the output mirror 2, the intensity distribution of the laser light L becomes close to a so-called top hat.
Furthermore, at least one of the first to fifth reflecting surfaces 3a to 4c has a reflectance R _P of a P-polarized component that is the vertical direction of the laser beam in FIG. 1 and a laser beam on the paper surface in FIG. The coating is applied so that the relationship with the reflectance R _S of the S-polarized light component which is an orthogonal direction satisfies R _P > R _S.
Thereby, when the laser beam L repeatedly reflects in the resonator, the reflectance of the S-polarized component can be suppressed, the electric field vector is forced in the radial direction from the optical axis, and the emitted laser beam L is Radially polarized light.
Such a radially polarized laser beam L is more easily absorbed by the workpiece than a circularly polarized laser beam, so that the laser beam L can be processed quickly. It becomes.

Next, the laser oscillator 101 of the second embodiment shown in FIG. 2 will be described. The second embodiment is a solid-state laser oscillator with respect to the gas laser oscillator 1 of the first embodiment.
The laser oscillator 101 of this embodiment is a laser that forms an output mirror 102, first and second reflecting means 103, 104 that constitute a resonator of the same shape as that of the first embodiment, and an excitation region provided therebetween. A disk 105; a semiconductor laser 106 that irradiates the laser disk 105 with excitation light Lr; a cooling means 107 that cools the laser disk 105; and a total reflection mirror 108 provided at a position facing the laser disk 105. Yes.
The shapes of the output mirror 102 and the first and second reflecting means 103 and 104 are the same as those in the first embodiment, and a detailed description thereof will be omitted.
The laser disk 105 has a disk shape, and the semiconductor lasers 106 are provided around the laser disk 105 at equal intervals. For this reason, each semiconductor laser 106 irradiates the excitation light Lr, so that the laser disk 105 is excited almost uniformly, and the laser light L is reflected on the surface of the laser disk 105 on the cooling means 107 side. A coating is applied.
The optical axis C of the laser beam L formed by the resonator is folded back into a substantially Z shape by the laser disk 105 and the reflecting mirror 108. For example, the first reflecting surface of the first reflecting means 103 is used. In the direction of the optical axis C of the laser beam L, 103a is arranged at a position facing the output mirror 102 and the through hole 104a of the second reflecting means 104.

With this configuration, when the laser oscillator 101 is operated and the laser disk 105 is excited by the semiconductor laser 106, the laser light L is generated from the laser disk 105.
Since the optical path of the laser beam L formed at this time is the same as that in the first embodiment except that it is reflected by the laser disk 105 and the reflecting mirror 108, detailed description thereof is omitted.
Even in such a configuration, in the same manner as in the first embodiment, during one pass from when the laser beam L is reflected by the output mirror 102 and returns to the output mirror 102 again, Since each of the inner and outer portions passes twice a total of six times, the gain of the laser beam L is amplified each time.
Furthermore, on at least one of the first to fifth reflecting surfaces 103a to 104c, the relationship between the reflectance R _P of the _P- polarized component and the reflectance R _S of the S-polarized component is R _P > R _S. By applying the coating as described above, the radially polarized laser beam L can be obtained.

Next, a laser oscillator 201 according to the third embodiment shown in FIG. 3 will be described. The laser oscillator 201 includes a laser cavity (not shown) filled with a laser gas, an output mirror 202 provided on the left side of the laser cavity, The first reflecting means 203 provided on the opposite side of the output mirror 202 across the laser cavity and the second reflecting means 204 provided on the output mirror 202 side of the laser cavity are configured.
As in the first embodiment, the laser cavity has a cylindrical shape, and the first reflecting means 203 and the second reflecting means 204 are attached to both ends of the laser cavity in an airtight state. The output mirror 202 is fixed at a position adjacent to the reflecting means 204 in an airtight state.
The output mirror 202, the first reflecting means 203, and the second reflecting means 204 constitute a resonator, and when the laser gas in the laser cavity is excited, the output mirror 202, the first reflecting means 203, and the second reflecting mirror 202 are excited. The laser beam L is resonated between the reflecting means 204, and the laser beam L is output from the output mirror 202.

The first reflecting means 203 is a substantially disc-shaped waxy mirror, which is installed coaxially with the optical axis C, which is the central axis of the laser cavity and output mirror 202, and reflects the laser light L on the excitation region R side. A first reflecting surface 203a and a second reflecting surface 203b are formed.
The first reflecting surface 203a is a ring-shaped inclined surface formed in the center. The first reflecting surface 203a is disposed at a position facing the output mirror 202 and is 45 ° with respect to the optical axis C. It is formed to face outward at an angle.
The second reflecting surface 203b is a ring-shaped inclined surface formed so as to surround the first reflecting surface 203a, and is formed facing inward so as to be orthogonal to the first reflecting surface 203a in the radial cross section. Has been.

The second reflecting means 204 is a substantially disk-shaped axicon mirror having a through-hole 204a formed in the center, and is installed coaxially with the optical axis C, which is the central axis of the laser cavity and the output mirror 202, and is an excitation region. A third reflecting surface 204b that reflects the laser beam L is formed on the R side.
The through hole 204 a is formed to have a diameter slightly larger than the diameter of the laser beam L emitted from the output mirror 2, and the optical axis direction of the laser beam L with respect to the first reflecting surface 203 a of the first reflecting means 203. It is formed in the position which opposes.
The third reflecting surface 204b is a ring-shaped inclined surface formed so as to surround the through hole 204a, and is formed so as to face inward at an angle of 45 ° with respect to the optical axis C. It is provided at a position facing the second reflecting surface 203b of the reflecting means 203.

The emission of the laser beam L by the laser oscillator 201 having the above configuration will be described.
First, the laser gas in the laser cavity is discharge-excited to generate laser light L in the laser cavity, and the following optical path is entered into the resonator including the output mirror 202, the first reflecting means 203, and the second reflecting means 204. Is formed.
For the sake of explanation, the optical path of the subsequent laser light L when the laser light L is reflected by the output mirror 202 will be described in order. First, the laser light L passes through the through hole 204a and the excitation region R of the second reflecting means 204. Then, it proceeds to the first reflecting surface 203a of the first reflecting means 203 on the right side of the drawing (1).
Since the first reflecting surface 203a is inclined toward the outside of the optical axis C, the laser light L is reflected outward, and the laser light L is inclined toward the optical axis C side. When reflected by 203b, it proceeds toward the third reflecting surface 204b of the second reflecting means 204 (2).
The laser beam L reflected by the third reflecting surface 204b passes the optical axis C and is reflected again by the third reflecting surface 204b, and then the laser beam L travels toward the second reflecting surface 203b of the first reflecting means 203. (3).
The laser beam L reflected by the second reflecting surface 203b is then reflected by the first reflecting surface 203a and returns to the output mirror 202 (4).

Thus, according to the resonator comprising the output mirror 202 and the first and second reflecting means 203 and 204, one pass until the laser light L is reflected by the output mirror 202 and returns to the output mirror 202 again. In the meantime, each region outside the excitation region R is passed twice twice for a total of four times.
The laser beam L emitted from the output mirror 202 has a ring shape, and the reflectance R _P of the P-polarized component and the S-polarized component are formed on at least one of the first to third reflective surfaces 203a to 204b. By applying a coating such that the relationship with the reflectance R _{S of} R _P > R _S is given, the radially polarized laser beam L can be emitted.
In the laser oscillator 201 of the third embodiment, the laser disk 105 and the reflecting mirror 108 as described in the second embodiment are installed in place of the laser cavity, and the laser beam L is emitted from the laser disk 105. May be generated.

Hereinafter, the laser oscillator 301 according to the fourth embodiment shown in FIG. 4 will be described. The laser oscillator 301 includes a laser cavity (not shown) filled with a laser gas, an output mirror 302 provided on the left side of the laser cavity, and a laser. The first reflecting means 303 provided on the opposite side of the output mirror 302 across the cavity and the second reflecting means 304 provided on the output mirror 302 side of the laser cavity are also included.
As in the first embodiment, the laser cavity has a cylindrical shape, and the first reflecting means 303 and the second reflecting means 304 are attached to both ends of the laser cavity in an airtight state. The output mirror 302 is fixed at a position adjacent to the reflecting means 304 in an airtight state.
The output mirror 302, the first reflecting means 303, and the second reflecting means 304 constitute a resonator. When the laser gas in the laser cavity is excited, the output mirror 302, the first reflecting means 303, and the second reflecting means 302 The laser beam L is resonated between the reflecting means 304 so that the laser beam is emitted from the output mirror 302.

The first reflecting means 303 has a substantially disk shape, is installed coaxially with the optical axis C, which is the central axis of the laser cavity and the output mirror 302, and is a set for turning the laser light L back to the excitation region R side. The first reflecting surface 303a and the second reflecting surface 303b are alternately formed in two sets.
The two first reflection surfaces 303a are ring-shaped inclined surfaces formed so as to face the outside at an angle of 45 ° with respect to the optical axis C. Among these, the first reflection surface 303a on the inside is The outer first reflecting surface 303a is provided at a position facing the output mirror 302 so as to surround the inner second reflecting surface 303b.
The two second reflecting surfaces 303b are ring-shaped inclined surfaces formed so as to surround the first reflecting surface 303a, respectively, and are orthogonal to the paired first reflecting surfaces 303a in the radial cross section. It is formed facing the inside.

The second reflecting means 304 has a substantially disk shape with a through hole 304a formed in the center, and is installed on the same axis as the optical axis C, which is the central axis of the laser cavity and the output mirror 302. Are formed with a third reflection surface 304b, a fourth reflection surface 304c, and a fifth reflection surface 304d that reflect the laser light L.
The through hole 304a is provided at a position facing the first reflecting surface 303a inside the first reflecting means 303, and is formed to have a diameter slightly larger than the diameter of the laser beam L emitted from the output mirror 302. Has been.
The third reflecting surface 304b is a ring-shaped inclined surface surrounding the through hole 304a, and is formed so as to face inward at an angle of 45 ° with respect to the optical axis C, and the fourth reflecting surface 304c is the first reflecting surface 304c. It is a ring-shaped inclined surface surrounding the third reflecting surface 304b, and is formed facing inward so as to be orthogonal to the third reflecting surface 304a in the radial cross section.
The fifth reflecting surface 304d surrounds the outer periphery of the fourth reflecting surface 304c and is formed so as to face the inside. In the present embodiment, the fourth reflecting surface 304c is extended as it is.
The third reflecting surface 304 b is provided at a position facing the second reflecting surface 303 b inside the first reflecting means 303, and the fourth reflecting surface 304 c is formed on the first reflecting surface 303 a outside the first reflecting means 303. The fifth reflecting surface 304 d is provided at a position facing the second reflecting surface 303 b outside the first reflecting means 303.

The emission of the laser beam L by the laser oscillator 301 having the above configuration will be described.
The optical path of the laser light L after the laser light L is reflected by the output mirror 2 will be described in order. The laser light L reflected by the output mirror 302 first passes through the excitation region R and enters the inside of the first reflecting means 303. The first reflection surface 303a of the second reflection means 304 is reflected in the direction of the optical axis C by the second reflection surface 303b adjacent to the first reflection surface 303a (2).
Thereafter, the laser light L is transferred from the third reflecting surface 304b to the fourth reflecting surface 304c, from the fourth reflecting surface 304c to the first reflecting surface 303a outside the first reflecting means 303 (3), and to the outer first reflecting surface 303a. From the outer second reflecting surface 303b to the fifth reflecting surface 304d of the second reflecting means (4).
The laser light reflected by the fifth reflecting surface 304d passes through the third and fourth reflecting surfaces 304b and 304c and the through-hole 204a, is reflected by the same fifth reflecting surface 304d, and is outside the first reflecting means 303. The second reflection surface 303b is reached (5).
Thereafter, the laser light L is transferred from the outer second reflecting surface 303b to the outer first reflecting surface 303a, and from the first reflecting surface 303a to the fourth reflecting surface 304c of the second reflecting means 304 (6), the fourth reflecting surface. From 304c to the third reflecting surface 304b, from the third reflecting surface 304b to the second reflecting surface 303b inside the first reflecting means 303 (7), from the second reflecting surface 303b to the first reflecting surface 303a, to the first reflecting surface. The light is reflected from the output mirror 302 to the output mirror 302 (8).

Thus, according to the resonator comprising the output mirror 302 and the first and second reflecting means 303 and 304, one pass until the laser light L is reflected by the output mirror 302 and returns to the output mirror 302 again. In the meantime, the excitation region R is passed twice twice in total.
The laser beam L emitted from the output mirror 302 has a ring shape, on at least one surface of the first to fifth reflecting surface 303A～304d, the reflectance _{R P} of the P-polarized light component, S-polarized light component By applying a coating such that the relationship with the reflectance R _{S of} R _P > R _S is given, the radially polarized laser beam L can be emitted.
In the laser oscillator 301 of the fourth embodiment, instead of the laser cavity, the laser disk 105 as described in the second embodiment is installed so that the laser disk 105 generates the laser light L. It may be.
Further, three or more sets of the first and second reflecting surfaces 303a and 303b in the first reflecting means 303 are provided, and the first and second reflecting surfaces 303a, 303b are provided inside the fifth reflecting surface 304d in the second reflecting means 304. The third and fourth reflecting surfaces 304b and 304c may be provided with a set smaller than 303b.
By doing in this way, with respect to the excitation region R formed around the optical axis C of the laser light L, a plurality of optical paths of the ring-shaped laser light L having different diameters can be formed coaxially. It becomes possible to efficiently obtain the output laser beam L.
Similarly, in the first and second embodiments, a plurality of sets of the first reflecting surfaces 3a and 103a and the second reflecting surfaces 3b and 103b of the first reflecting means 3 and 103 are provided, and the first and second reflecting surfaces 3b and 103b are provided on the outer periphery thereof. The third reflection surfaces 3c and 103c may be provided, and the same number of sets of the fourth reflection surfaces 4b and 104b and the fifth reflection surfaces 4c and 104d of the second reflection means 4 and 104 may be provided.

1 is a schematic diagram of a laser oscillator according to a first embodiment. The schematic of the laser oscillator concerning 2nd Example. The schematic diagram of the laser oscillator concerning 3rd Example. The schematic of the laser oscillator concerning 4th Example.

Explanation of symbols

1, 101, 201, 301 Laser oscillator 2, 102, 202, 302 Output mirror 3, 103, 203, 303 First reflecting means 4, 104, 204, 304 Second reflecting means

Claims (3)

In a laser oscillator having an excitation region that generates laser light by excitation and a resonator that forms an optical path of the laser light so as to pass through the excitation region,
The resonator is provided on the optical axis of the laser beam, and an output mirror that transmits a part of the laser beam generated in the excitation region, and a first that is provided on the opposite side of the output mirror across the excitation region. The reflecting means and the second reflecting means provided on the output mirror side of the excitation region,
The first reflecting means includes a ring-shaped first reflecting surface inclined to face the outer side of the optical axis, and a ring-shaped first reflecting surface surrounding the first reflecting surface and inclined to face the optical axis side. A ring-like shape surrounding the two reflecting surfaces and at least one pair of the first and second reflecting surfaces, being located closer to the second reflecting means than the first and second reflecting surfaces, and inclined toward the optical axis side A third reflective surface,
The second reflecting means includes a through-hole through which laser light passes, a ring-shaped fourth reflecting surface that surrounds the through-hole and is inclined to face the outside of the optical axis, and surrounds the fourth reflecting surface. And the same number of sets of ring-shaped fifth reflecting surfaces inclined to face the optical axis side as the first and second reflecting surfaces,
A first reflecting surface located at the innermost periphery of the first reflecting means is disposed at a position facing the output mirror, each fourth reflecting surface is disposed at a position facing each second reflecting surface, and third reflecting is performed. A laser oscillator comprising a fifth reflecting surface located on the outermost periphery of the second reflecting means at a position facing the surface. In a laser oscillator having an excitation region that generates laser light by excitation and a resonator that forms an optical path of the laser light so as to pass through the excitation region,
The resonator is provided on the optical axis of the laser beam, and an output mirror that transmits a part of the laser beam generated in the excitation region, and a first that is provided on the opposite side of the output mirror across the excitation region. The reflecting means and the second reflecting means provided on the output mirror side of the excitation region,
The first reflecting means includes a ring-shaped first reflecting surface inclined to face the outer side of the optical axis, and a ring-shaped first reflecting surface surrounding the first reflecting surface and inclined to face the optical axis side. Two reflective surfaces,
The second reflecting means includes a through-hole through which laser light passes, and a ring-shaped third reflecting surface that surrounds the through-hole and is inclined to face the optical axis side,
A laser oscillator comprising: a first reflecting surface disposed at a position facing the output mirror; and a third reflecting surface disposed at a position facing the second reflecting surface. In a laser oscillator having an excitation region that generates laser light by excitation and a resonator that forms an optical path of the laser light so as to pass through the excitation region,
The resonator is provided on the optical axis of the laser beam, and an output mirror that transmits a part of the laser beam generated in the excitation region, and a first that is provided on the opposite side of the output mirror across the excitation region. The reflecting means and the second reflecting means provided on the output mirror side of the excitation region,
The first reflecting means includes a ring-shaped first reflecting surface inclined to face the outer side of the optical axis, and a ring-shaped first reflecting surface surrounding the first reflecting surface and inclined to face the optical axis side. 2 sets of 2 reflective surfaces are provided,
The second reflecting means includes a through-hole through which laser light passes, a ring-shaped third reflecting surface that surrounds the through-hole and is inclined so as to face the outside of the optical axis, and surrounds the third reflecting surface. And surrounding the ring-shaped fourth reflecting surface inclined so as to face the optical axis side, and the third and fourth reflecting surfaces formed by a smaller number than the first and second reflecting surfaces. 3, a ring-shaped fifth reflecting surface that is located closer to the first reflecting means than the fourth reflecting surface and is inclined so as to face the optical axis side,
A first reflecting surface located at the innermost circumference of the first reflecting means is disposed at a position facing the output mirror, each third reflecting surface is disposed at a position facing each second reflecting surface, and a fifth reflecting surface. A laser oscillator characterized by disposing a second reflecting surface located on the outermost periphery of the first reflecting means at a position opposite to the first reflecting means.

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