JP4187678B2 - Solid state laser equipment - Google Patents

Description

  The present invention relates to a solid-state laser device that excites a solid-state laser medium with excitation light to output laser light, and more particularly to a solid-state laser device that can uniformly and efficiently excite a solid-state laser medium.

  Conventionally, as this type of solid-state laser device, a cylindrical laser rod made of a solid-state laser medium, an excitation light source that emits excitation light toward the laser rod, and excitation light emitted from the excitation light source are used as laser rods. An apparatus including a pumping optical system for guiding and a cooling mechanism for cooling the laser rod is known.

  By the way, in such a solid-state laser device, it is important to uniformly and efficiently excite the laser rod. As a method for that purpose, Patent Document 1 discloses an outer peripheral surface of a flow tube surrounding the outer peripheral surface of the laser rod. A diffuser with a diffuse reflection surface (diffusion concentrator) is arranged along the, and the excitation light guided from the excitation light source to the diffuse collector is reflected multiple times within the diffuse collector and then laser A method of irradiating the rod has been proposed.

  Further, in Patent Documents 2 to 4, a plurality of excitation light sources are arranged outside the flow tube surrounding the outer peripheral surface of the laser rod, and the laser rod is irradiated with excitation light from a plurality of directions according to the position of the excitation light source. A method has been proposed.

  FIG. 5 is a diagram for explaining a conventional solid-state laser device proposed in Patent Documents 2 to 4. In FIG. As shown in FIG. 5, in a conventional solid-state laser device 100, a cylindrical flow tube 150 is disposed outside a cylindrical laser rod 130 made of a solid-state laser medium so as to surround the outer peripheral surface thereof. . On the outer peripheral surface of the flow tube 150, reflection coating portions 160a, 160b, and 160c are formed in the remaining portions so that optical slits 170a, 170b, and 170c are formed in a part of the outer periphery. Further, on the outside of the flow tube 150, laser diodes 110a, 110b, and 110c as excitation light sources that emit excitation light toward slits 170a, 170b, and 170c formed on the outer peripheral surface of the flow tube 150, and a laser diode Cylindrical lenses 120a, 120b, and 120c are provided as light guiding lenses that guide the excitation light emitted from 110a, 110b, and 110c into the flow tube 150 through the slits 170a, 170b, and 170c.

In the solid-state laser device 100 having such a configuration, most of the excitation light guided from the laser diodes 110a, 110b, and 110c to the inside of the flow tube 150 through the slits 170a, 170b, and 170c is directed to the laser rod 130. Reflected coating portions 160a, 160b, and 160c (for example, excitation light guided through the slit 170a) that are irradiated and the remaining part of the flow tube 150 is positioned on the opposite side of the slits 170a, 170b, and 170c with respect to the flow tube 150 are reflected. After being reflected by the coat portion 160b), the laser rod 130 is irradiated again. Note that cooling water (not shown) flows in the space 140 between the outer peripheral surface of the laser rod 130 and the inner peripheral surface of the flow tube 150, thereby cooling the laser rod 130.
JP-A-8-181368 JP 2000-277837 A JP-A-10-84150 JP 2001-244526 A

  However, in the method described in Patent Document 1, although the laser rod is uniformly excited by irradiating the laser rod with a plurality of directions of excitation light reflected in the diffusion collector, the diffusion collector There is a problem in that the efficiency of the excitation light applied to the laser rod is reduced due to multiple reflections in the interior.

  On the other hand, in the methods described in Patent Documents 2 to 4, since the excitation light emitted from a plurality of directions according to the position of the excitation light source is directly irradiated to the laser rod, the laser rod is efficiently excited. However, in the methods described in Patent Documents 2 to 4, as is clear from FIG. 5, the uniformity of the emission distribution of the excitation light simply depends on the number of excitation light sources. In order to make the light emission distribution uniform, there is a problem that a large number of excitation light sources must be arranged.

  The present invention has been made in consideration of the above points, and an object of the present invention is to provide a solid-state laser device that can uniformly and efficiently excite a laser rod made of a solid-state laser medium with a simple configuration. .

The present invention relates to a solid-state laser device that emits laser light by exciting a solid-state laser medium with excitation light, and a cylindrical laser rod made of a solid-state laser medium and a triangle provided so as to surround the outer peripheral surface of the laser rod. A columnar sleeve, a reflecting member provided on the remaining side of the outer peripheral surface of the sleeve so as to form an optical slit at the apex of the triangular cross section, and disposed outside the sleeve; An excitation light source that emits excitation light toward the slit formed on the outer peripheral surface of the sleeve, and is disposed between the sleeve and the excitation light source, and the excitation light emitted from the excitation light source passes through the slit. A light guiding lens that guides the inside of the sleeve, and the light guiding lens has a portion of the excitation light guided inside the sleeve facing the laser rod in a frontal direction. And the rest of the excitation light passes through the laser rod without being irradiated to the laser rod, and the reflection member is not irradiated to the laser rod among the excitation light guided to the inside of the sleeve. The excitation light that has passed through is reflected in order from the part located on the back of the laser rod and the part located on the side of the laser rod, and then the laser rod is irradiated from a direction different from the front direction. The solid-state laser device is characterized in that the light guiding lens is a lens that once collects the excitation light emitted from the excitation light source at the position of the slit and then guides it as diffused light to the inside of the sleeve. I will provide a.

In the present invention, the sleeve is a flow tube having a cylindrical inner peripheral surface corresponding to the outer peripheral surface of the laser rod, and a space between the inner peripheral surface of the sleeve and the outer peripheral surface of the laser rod. It is preferable that the laser rod is cooled by cooling water that is flowed into the chamber .

  According to the present invention, the excitation light emitted from the excitation light source is guided to the inside of the sleeve in a state of being expanded after passing through the slit by the optical action of each light guiding lens, and a part of the excitation light is directed to the laser rod. While irradiating from the direction, the rest passes through without irradiating the laser rod. The excitation light that has passed through the laser rod without being irradiated in this way is reflected at the part located on the back part of the laser rod and the part located on the side part of the laser rod among the reflecting members formed on the outer peripheral surface of the sleeve. After being reflected in order, the laser rod is irradiated from a direction different from the front direction (two lateral directions). Here, since the excitation light emitted from the excitation light source is guided into the sleeve through three slits arranged around the laser rod, the direction of the excitation light irradiated to the laser rod is pseudo. Thus, it becomes possible to irradiate the laser rod with excitation light from many directions (multiple paths). This makes it possible to uniformly excite the laser rod, improve the spread angle of the laser beam finally output from the solid-state laser device, and increase the number of laser heads (arrange multiple solid-state laser devices in series). Large output laser light can be easily extracted.

BEST MODE FOR CARRYING OUT THE INVENTION

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the entire configuration of the solid-state laser device according to the present embodiment will be described with reference to FIGS. 1 is a perspective view showing the overall configuration of the solid-state laser device, and FIG. 2 is a cross-sectional view taken along the line II-II of the solid-state laser device shown in FIG.

  As shown in FIGS. 1 and 2, a solid-state laser device 10 according to the present embodiment is for exciting a solid-state laser medium with excitation light and outputting laser light, and is a cylindrical shape made of a solid-state laser medium. And a triangular prism-shaped flow tube (sleeve) 15 provided so as to surround the outer peripheral surface of the laser rod 13.

  Among these, the flow tube 15 has an outer peripheral surface having a substantially equilateral triangular cross-sectional shape and a cylindrical inner peripheral surface corresponding to the outer peripheral surface of the laser rod 13, and the inner peripheral surface of the flow tube 15 and the laser. The laser rod 13 can be cooled by cooling water (not shown) that flows in the space 14 between the outer peripheral surface of the rod 13.

  Here, very narrow optical slits 17 a, 17 b, and 17 c are formed in the apex angle portion (a portion chamfered flat) of the outer peripheral surface of the flow tube 15. The slits 17a, 17b, and 17c are provided with an antireflection coating (not shown). Further, on the outer peripheral surface of the flow tube 15, reflection coating portions (reflection members) 16a, 16b, and 16c are formed on the remaining side portions other than the apex portion of the triangular cross section. The reflective coating portions (reflective members) 16 a, 16 b, and 16 c have mirror surfaces (reflective surfaces) on the inner surfaces, and reflect the excitation light guided into the flow tube 15.

  Further, on the outside of the flow tube 15, laser diodes (excitation light sources) 11a, 11b, and 11c that emit excitation light toward slits 17a, 17b, and 17c formed on the outer peripheral surface of the flow tube 15; Fan-shaped lenses (light guiding lenses) 12a, 12b, and 12c arranged corresponding to the laser diodes 11a, 11b, and 11c are provided. Note that the fan-shaped lenses 12a, 12b, and 12c are configured so that the excitation light emitted from the laser diodes 11a, 11b, and 11c is once condensed at the positions of the slits 17a, 17b, and 17c and then diffused into the interior of the flow tube 15. It is to lead to.

  In the above, the laser diodes 11a, 11b, and 11c, the fan-shaped lenses 12a, 12b, and 12c, the laser rod 13, and the flow tube 15 are fixed by a pair of end plates 18a and 18b arranged at their ends. Yes.

  In the solid-state laser device 10 having such a configuration, the excitation light guided to the inside of the flow tube 15 is expanded after passing through the slits 17a, 17b, and 17c by the optical action of the sector-shaped lenses 12a, 12b, and 12c. In this state, the laser rod 13 is guided to the inside of the flow tube 15 from the front direction, while the rest passes through the laser rod 13 without being irradiated. Here, of the excitation light guided to the inside of the flow tube 15, the excitation light that has passed through the laser rod 13 without being irradiated is reflected by the reflective coating portions 16 a, 16 b, and 16 c, and the laser rod 13 has a front direction. Irradiated from different directions.

  Specifically, as shown in FIG. 3A, the excitation light emitted from the laser diode 11a is expanded after passing through the slit 17a by the optical action of the fan-shaped lens 12a. The laser rod 13 is guided to the inside from the front direction. On the other hand, the remainder of the excitation light passes through the laser rod 13 without being irradiated, and a portion (reflection coating) located on the back of the laser rod 13 among the reflection coating portions 16a, 16b, 16c formed on the outer peripheral surface of the flow tube 15. The laser rod 13 is irradiated from a direction different from the front direction (two directions on the side) after being sequentially reflected by the portions 16b) and the portions located on the side of the laser rod 13 (reflection coating portions 16a and 16c). As described above, the excitation light emitted from the laser diode 11a is finally applied to the laser rod 13 from three directions. In addition, when the ratio for each direction of the excitation light irradiated to the laser rod 13 under the arrangement relationship as shown in FIG. 3A is calculated by simulation, the excitation light irradiated from the front direction is 48% on the side. The excitation light irradiated from the two directions was 27%. Here, since the excitation light emitted from the laser diodes 11a, 11b, and 11c is guided to the inside of the flow tube 15 through the three slits 17a, 17b, and 17c arranged around the laser rod 13, the laser rod The direction of the excitation light irradiated to 13 becomes pseudo nine directions, and the laser rod 13 can be uniformly excited.

  On the other hand, in the conventional solid-state laser device 100 shown in FIG. 5, as shown in FIG. 3B, the excitation light emitted from the laser diode 110a is guided into the flow tube 150 by the cylindrical lens 120a. Most of the laser beam 130 is irradiated from only one direction in the front direction. In addition, when the ratio for each direction of the excitation light irradiated to the laser rod 130 under the arrangement relationship as shown in FIG. 3B is calculated by simulation, the excitation light irradiated from the front direction is 69% on the side. The excitation light irradiated from the two directions was 1%. The excitation light emitted from the laser diodes 110a, 110b, and 110c is guided into the flow tube 150 through the three slits 170a, 170b, and 170c arranged around the laser rod 13. Since the irradiation directions of the excitation light by the diodes 110a, 110b, and 110c are almost only in one direction, there are at most three directions as a whole, and the laser rod 130 is uniformly excited as compared with the solid-state laser device 10 shown in FIG. Difficult to do.

  Whether or not the laser rod 13 is uniformly excited can be verified by measuring the spread angle of the laser beam finally output from the solid-state laser device 10. Under the arrangement relationship shown in FIGS. 3A and 3B, the output of the laser beam and the divergence angle in the solid-state laser device 10 shown in FIG. 1 and the conventional solid-state laser device 100 shown in FIG. The experimental results of measuring the relationship are shown in FIG. As shown in FIG. 4, when comparing the spread angles of laser beams with the same output, the solid laser device 10 shown in FIG. 1 is more spread than the conventional solid laser device 100 shown in FIG. It can be seen that the angle is about 20% smaller (note that, when comparing the output of laser light at the same spread angle, the solid-state laser device 10 shown in FIG. This means that the output of the laser beam is about 20% larger than that of the solid-state laser device 100 of FIG. Thereby, it was verified that the laser rod 130 was uniformly excited in the solid-state laser device 10 shown in FIG.

  As described above, according to the present embodiment, the excitation light emitted from the laser diodes 11a, 11b, and 11c is expanded after passing through the slits 17a, 17b, and 17c by the optical action of the sector-shaped lenses 12a, 12b, and 12c. In this state, the laser rod 13 is guided to the inside of the flow tube 15 from the front direction, while the rest passes through the laser rod 13 without being irradiated. Then, the excitation light that has passed through the laser rod 13 without being irradiated in this way is a portion (on the back of the laser rod 13) of the reflective coating portions 16 a, 16 b, 16 c formed on the outer peripheral surface of the flow tube 15 ( For example, in the case of the excitation light that has passed through the slit 17a, the reflective coating portion 16b) and in the part located on the side of the laser rod 13 (for example, the reflective coating portions 16a and 16c in the case of the excitation light that has passed through the slit 17a). After being reflected, the laser rod 13 is irradiated from a direction different from the front direction (two lateral directions). Here, since the excitation light emitted from the laser diodes 11a, 11b, and 11c is guided to the inside of the flow tube 15 through the three slits 17a, 17b, and 17c arranged around the laser rod 13, the laser rod The direction of the excitation light irradiated to 13 becomes pseudo nine directions, and it becomes possible to irradiate the laser rod 13 with excitation light from many directions (multiple paths). For this reason, the laser rod 13 can be excited uniformly, the spread angle of the laser beam finally output from the solid-state laser device 10 is improved, and a multi-laser head is formed (a plurality of solid-state laser devices are arranged in series). For example, a high-power laser beam can be easily extracted.

  Further, according to the present embodiment, the excitation light emitted from the laser diodes 11a, 11b, and 11c is once condensed at the positions of the slits 17a, 17b, and 17c by the fan-shaped lenses 12a, 12b, and 12c, and then diffused. Since the light is guided to the inside of the flow tube 15, the excitation light can be taken into the flow tube 15 without any problem even if the widths of the slits 17 a, 17 b, and 17 c of the flow tube 15 are reduced. Here, if the widths of the slits 17a, 17b, and 17c of the flow tube 15 are made as small as possible, leakage of the excitation light guided to the inside of the flow tube 15 to the outside can be minimized. The efficiency of the excitation light irradiated to 13 can be improved.

1 is a perspective view showing an overall configuration of a solid-state laser apparatus according to an embodiment of the present invention. Sectional drawing along the II-II line of the solid-state laser apparatus shown in FIG. The figure for demonstrating the mode of excitation of the laser rod in the solid-state laser apparatus shown in FIG. 1, and the conventional solid-state laser apparatus. The figure which shows the relationship between the output of a laser beam and a divergence angle in the solid-state laser apparatus shown in FIG. 1, and the conventional solid-state laser apparatus. The figure for demonstrating the conventional solid-state laser apparatus.

Explanation of symbols

10 Solid-state laser devices 11a, 11b, 11c Laser diode (excitation light source)
12a, 12b, 12c Fan-shaped lens (light guiding lens)
13 Laser rod 14 Cooling water space 15 Flow tube (sleeve)
16a, 16b, 16c Reflective coating portions 17a, 17b, 17c Slits 18a, 18b End plate 100 Solid-state laser devices 110a, 110b, 110c Laser diode (excitation light source)
120a, 120b, 120c Cylindrical lens (light guiding lens)
130 Laser rod 140 Cooling water space 150 Flow tubes 160a, 160b, 160c Reflective coating portions 170a, 170b, 170c Slit

Claims (2)

In a solid-state laser device that emits laser light by exciting a solid-state laser medium with excitation light,
A cylindrical laser rod made of a solid laser medium;
A triangular prism-shaped sleeve provided so as to surround the outer peripheral surface of the laser rod;
A reflecting member provided on the remaining side of the sleeve so as to form an optical slit in the apex of the triangular cross section of the outer peripheral surface of the sleeve;
An excitation light source disposed outside the sleeve and emitting excitation light toward the slit formed on the outer peripheral surface of the sleeve;
A light guide lens disposed between the sleeve and the excitation light source and guiding the excitation light emitted from the excitation light source to the inside of the sleeve through the slit;
The light guide lens is configured such that a part of the excitation light guided to the inside of the sleeve is irradiated to the laser rod from the front direction and the remainder of the excitation light passes through without being irradiated to the laser rod. The reflecting member is positioned at a portion where the excitation light guided to the inside of the sleeve passes through the laser rod without being irradiated and located at a back portion of the laser rod and at a side portion of the laser rod. the said front direction to the laser rod after being sequentially reflected by the site is configured to be irradiated from different directions,
The solid-state laser device , wherein the light guide lens is a lens that once collects the excitation light emitted from the excitation light source at the position of the slit and then guides the light into the sleeve as diffused light .   The sleeve is a flow tube having a cylindrical inner peripheral surface corresponding to the outer peripheral surface of the laser rod, and is cooled by cooling water flowing in a space between the inner peripheral surface of the sleeve and the outer peripheral surface of the laser rod. The solid-state laser device according to claim 1, wherein the solid-state laser device is configured to cool the laser rod.

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