JP2013102007A - Fiber laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine the irradiation position of invisible laser light accurately while reducing loss of visible laser light.SOLUTION: A fiber laser device 1 generating invisible laser light and outputting it via a delivery fiber 34 comprises a visible laser light source (visible light LD 40) generating visible laser light, an introduction part (output fiber 33) which introduces the visible laser light generated from the visible laser light source 40 into clads near the joints 51-57 of the output fiber 33 outputting the invisible laser light thus generated and the delivery fiber 34, and a drive section (control section 20) which drives the visible laser light source 40 when positioning the invisible laser light irradiation for a workpiece, so as to emit visible laser light through the clad of the delivery fiber 34, and to irradiate the processing position of the workpiece with visible laser light.

Description

  The present invention relates to a fiber laser device.

  When processing an object using a laser beam, it is necessary to perform positioning for determining a position where a laser is irradiated on the object to be processed.

  Since invisible laser light cannot visually recognize laser light, conventionally, for example, as shown in Patent Documents 1 and 2, using a half mirror, the optical axis of invisible laser light and visible laser light There is a technique in which the optical axes are adjusted so as to coincide with each other, and positioning is performed using visible laser light.

  Further, in Patent Document 3, an optical fiber that guides visible laser light is arranged so as to be parallel to an optical fiber that guides invisible laser light, and laser light output from each fiber is output by a lens at an emission portion. A technique for condensing light and condensing them at the same position at a predetermined distance from the emission part is disclosed.

JP-A-2005-13348 JP 07-116878 A JP-A 62-008748

  By the way, in the techniques disclosed in Patent Documents 1 to 3, since the waveguide routes of the invisible laser light and the visible laser light are different, the irradiation position on the object to be processed is displaced, and as a result, the positioning is accurately performed. There is a problem that cannot be done. Further, when there is an optical element that causes an optical loss in the path of the visible laser light, there is a problem that the visible laser light is attenuated and visibility is deteriorated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fiber laser device that accurately determines the irradiation position of invisible laser light and reduces the loss of visible laser light.

In order to solve the above problems, the present invention provides a fiber laser device that generates invisible laser light and outputs it through a delivery fiber, and a visible laser light source that generates visible laser light, and the generated invisible laser light includes Positioning for introducing the visible laser light generated by the visible laser light source into the cladding in the vicinity of the joint between the output fiber to be output and the delivery fiber, and irradiation of the invisible laser light on the workpiece A driving unit that drives the visible laser light source, emits the visible laser light through the clad of the delivery fiber, and irradiates the processing position of the processing object with the visible laser light. It is characterized by that.
According to such a configuration, it is possible to accurately determine the irradiation position of the invisible laser beam and reduce the loss of the visible laser beam.

In addition to the above-mentioned invention, another invention is characterized in that the delivery fiber is set so that the refractive index of the coating covering the cladding is smaller than the refractive index of the cladding.
According to such a configuration, the visible laser light can be efficiently propagated in the clad by preventing the visible laser light from leaking out of the coating.

According to another invention, in addition to the above invention, the delivery fiber has a refractive index distribution of a clad so as to form a region in which the visible laser light propagates.
According to such a configuration, the visible laser light can be efficiently propagated in the cladding by preventing the visible laser light from leaking out of the cladding.

In addition to the above invention, another invention is characterized in that the introduction part introduces the visible laser light from a clad in the vicinity of the joint part of the delivery fiber.
According to such a configuration, the loss of visible laser light can be reduced by introducing visible laser light into the cladding of the delivery fiber.

According to another aspect of the invention, in addition to the above-mentioned invention, the cladding of the delivery fiber has a larger diameter than the cladding of the output fiber, and the introduction portion is a portion of the delivery fiber that protrudes in the radial direction at the joint portion. The visible laser light is introduced from the end face of the clad.
According to such a configuration, visible laser light can be efficiently introduced into the clad.

In addition to the above invention, another invention is characterized in that the introduction part introduces the visible laser light from an outer peripheral surface of a clad in the vicinity of the joint part of the delivery fiber.
According to such a configuration, it is possible to reduce the return light incident on the visible laser light source, and thus it is possible to prevent the visible laser light source from being shortened or damaged.

According to another aspect of the invention, in addition to the above-described invention, the introduction portion is disposed in contact with an outer peripheral surface of the cladding in the vicinity of the joint portion of the delivery fiber, and the visible laser light propagates through the cladding. The visible laser light that has an optical fiber and propagates through the cladding of the optical fiber is incident on the cladding of the delivery fiber from the contact portion.
According to such a configuration, visible laser light can be efficiently introduced into the clad and return light incident on the visible laser light source can be reduced. Can be prevented.

  According to the present invention, it is possible to accurately determine the irradiation position of the invisible laser light and to provide a fiber laser device with little loss of visible laser light.

It is a figure which shows the structural example of 1st Embodiment of this invention. It is a figure which shows the structural example of the control part shown in FIG. It is a figure which shows the detailed structural example of the junction part of the output fiber and delivery fiber shown in FIG. It is a figure which shows the detail of the joining state of the output fiber, delivery fiber, and visible light output fiber which are shown in FIG. It is a figure which shows both relationship in the case of arrange | positioning visible light output fiber substantially parallel to output fiber. It is a figure which shows both relationship in the case of arrange | positioning a visible light output fiber non-parallel to an output fiber. It is a figure which shows the state which has arrange | positioned monitor PD and the visible light cut filter in the junction part. It is a figure which shows the structural example of 2nd Embodiment of this invention. It is a figure which shows the structural example of 3rd Embodiment of this invention. It is a figure which shows an example of the refractive index of the delivery fiber of 3rd Embodiment shown in FIG. It is a figure which shows the structural example of 4th Embodiment of this invention. It is a figure which shows the structural example of 5th Embodiment of this invention.

  Next, an embodiment of the present invention will be described.

(A) 1st Embodiment FIG. 1: is a figure which shows the structural example of 1st Embodiment of this invention. As shown in this figure, the fiber laser device 1 according to the first embodiment includes a laser oscillation device 10 and a laser amplification device 30 as main components, and converts invisible laser light generated by the laser oscillation device 10 into a laser beam. Amplified by the amplifying device 30 and output through the delivery fiber 34.

  Here, the laser oscillation device 10 includes an excitation light multiplexer 11, an HR (High Reflector) 12, an amplification optical fiber 13, an OC (Output Coupler) 14, an excitation LD (Laser Diode) drive power supply 15, and an excitation light source. It has LD16, is controlled by the control part 20, and generates an invisible laser beam. The laser amplifying apparatus 30 includes a pumping light multiplexer 31, an amplification optical fiber 32, an output fiber 33, a delivery fiber 34, a pumping LD drive power supply 35, and a pumping LD 36. Controlled, invisible laser light is amplified and output via the delivery fiber 34. The visible light LD 40 is a single mode LD that generates and outputs visible light. The filter 41 transmits visible light and makes it enter the delivery fiber 34 from the joint portion 57, and attenuates return light returning from the delivery fiber 34.

  The pumping light multiplexer 11 constituting the laser oscillation device 10 is configured by, for example, a TFB (Tapered Fiber Bundle) or the like, and introduces laser light output from the pumping LD 16 into the cladding of the optical fiber as pumping light. The HR 12 is, for example, a high reflection fiber grating (FBG), which is formed by periodically changing the refractive index of the optical fiber, and reflects the laser light from the amplification optical fiber 13 with a reflectance close to 100%. The amplification optical fiber 13 is constituted by a DCF (Double Clad Fiber) having a single mode core to which rare earth ions such as Er (Erbium) and Yb (Ytterbium) are added, for example. For example, an infrared laser beam with a wavelength of 1080 nm is oscillated and output. Note that the DCF in the present embodiment has two clads formed outside the single mode core described above, and the excitation light propagates through the inner clad, but the core is not limited to the single mode. Alternatively, it may be a multi-mode core (for example, propagating a basic mode and several lower-order modes).

  Like the HR 12, the OC 14 is formed by periodically changing the refractive index of the optical fiber, passes a part (for example, 10%) of the laser light from the amplification optical fiber 13, and reflects the rest. . The HR 12, the amplification optical fiber 13, and the OC 14 constitute an optical fiber resonator.

  The excitation LD drive power supply 15 drives the excitation LD 16 under the control of the control unit 20. For example, the excitation LD 16 includes one or a plurality of multimode laser diodes having a wavelength of 915 nm and an output light intensity of several W or more.

  As shown in FIG. 2, the control unit 20 mainly includes a CPU (Central Processing Unit) 21, a ROM (Read Only Memory) 22, a RAM (Random Access Memory) 23, an I / F (Interface) 24, and a bus 25. As a component. Here, the CPU 21 controls each unit based on the program 22 a and data 22 b stored in the ROM 22. The ROM 22 is a nonvolatile semiconductor storage device and stores a program 22a and data 22b. The RAM 23 is a volatile semiconductor storage device, and operates as a work area when the CPU 21 executes a program. The I / F 24 is configured by, for example, a DAC (Digital Analog Converter), an ADC (Analog Digital Converter), and the like. The digital data supplied from the CPU 21 is converted into an analog signal, and the excitation LD drive power supplies 15 and 35 and the visible light are visible. It supplies to optical LD40. The bus 25 is a signal line group for connecting the CPU 21, ROM 22, RAM 23, and I / F 24 to each other and enabling data exchange between them. In this embodiment, a CPU or the like is used as the control unit 20, but the present embodiment is not limited to such a case. For example, a DSP (Digital Signal Processor) may be used, Alternatively, an analog control method may be used instead of the digital control method.

  The pumping light multiplexer 31 is composed of, for example, TFB, and introduces laser light output from the pumping LD 36 into the cladding of the optical fiber as pumping light. The amplification optical fiber 32 is configured by, for example, a DCF having a single mode core to which rare earth ions such as Er and Yb are added, and is excited by excitation light introduced from the outside into the core. The infrared laser beam of 1080 nm output from the laser oscillation device 10 is amplified and output. The configuration of the DCF in the present embodiment is the same as that of the amplification optical fiber 13 described above. The output fiber 33 outputs the light output from the amplification optical fiber 32 to the delivery fiber 34 via the joint portion 57. The delivery fiber 34 is configured by a multimode fiber or a single mode fiber, and guides the invisible laser light output from the output fiber 33 to the workpiece.

  FIG. 3 is a cross-sectional view illustrating a detailed configuration of the joint portion 57. As shown in FIG. 3, the output fiber 33 and the delivery fiber 34 are joined by a joining portion 57. The output fiber 33 has a core 33a at the center, a clad 33b on the outer side, and a coating 33c on the outermost side. The delivery fiber 34 has a core 34a at the center, a clad 34b on the outer side, and a coating 34c on the outermost side. In the first embodiment, the output fiber 33 and the delivery fiber 34 are both single mode fibers, and the cladding diameter is 200 μm for the output fiber 33 and 330 μm for the delivery fiber 34. The coating 34c of the delivery fiber 34 is made of a material having a refractive index smaller than that of the clad 34b. The cores of the output fiber 33 and the delivery fiber 34 have substantially the same diameter, and are joined so that their optical axes coincide.

  Since the clad 34b is set to have a larger diameter than the clad 33b as described above, the clad 34b protrudes beyond the clad 33b at the joint portion 57 as shown in FIG. It has become. Further, the coating around the joint 57 of the output fiber 33 and the delivery fiber 34 is removed over a certain length. For example, a visible light output fiber 42 having a mode field diameter of 9.2 ± 0.5 μm and a cladding diameter of 125.0 ± 0.7 μm at a wavelength of 1310 nm is connected to the output of the filter 41. For example, as shown in FIG. Thus, the end portion of the visible light output fiber 42 protrudes from the clad 33b after the covering 42c around the joint portion 57 is removed over a certain length in the same manner as the output fiber 33 and the delivery fiber 34. It is attached to the end face of the partial clad 34b.

  The angle formed between the visible light output fiber 42 and the clad 34b is such that the angle θ formed between the visible laser light indicated by the bold line in the drawing and the outer peripheral surface of the clad 34b is larger than the critical angle at which the visible laser light is totally reflected. It is set to be smaller. By doing in this way, visible light from visible light output fiber 42 can be propagated more efficiently in clad 34b. Furthermore, when the NA (Numerical Aperture) of the visible laser light emitted from the visible light output fiber 42 is within the above critical angle range, it is desirable that the coupling loss of the visible laser light can be further reduced. As a method for connecting the visible light output fiber 42 to the end face of the clad 34b at an appropriate angle, for example, the critical angle θ is measured in advance, and the angle between the visible light output fiber 42 and the delivery fiber 34 is the critical angle θ. After the adjustment, the visible light output fiber 42 and the delivery fiber 34 are bonded with a photo-curing resin or the like, or the visible light output fiber 42 is fused to the delivery fiber 34, or the visible light output fiber 42. For example, by bonding the vicinity of the joint portion 57 of each of the delivery fibers 34 and fixing the relative positions thereof. For example, as shown in FIG. 4, an adhesive is not applied to the joining portion 57, but an adhesive is applied to the peripheral portion, for example, the covering portion of the visible light output fiber 42 or the delivery fiber 34 as shown in the figure. The relative position of both is fixed as the agent fixing portion. In addition, the visible light output fiber 42 and the delivery fiber 34 are connected in a state where the visible light LD 40 is turned on instead of adjusting to the critical angle θ so that the output of the visible light laser from the delivery fiber 34 is maximized. You may make it adhere | attach after adjusting an angle. In the example shown in FIG. 3, the optical axis of the visible light output fiber 42 hits the irradiation surface of the clad 34b from the inside of the clad 34b. However, the present invention is limited to such a case. Instead, for example, θ may be approximately 0, that is, visible laser light may be incident substantially parallel to the optical axis direction of the delivery fiber 34. In the present embodiment, the protruding portion in the radial direction of the clad 34b is 65 μm, and the central axis of the visible light output fiber 42 is on the inner side of the outer edge of the clad 34b. Can be propagated in the delivery fiber 34.

  Here, when the radius of the visible light output fiber 42 is larger than the protruding portion in the radial direction of the clad 34 b of the delivery fiber 34, the center axis of the visible light output fiber 42 is the delivery fiber 34 when both are made substantially parallel. It does not enter the outer edge of the cladding 34b. Even in such a case, as shown in FIG. 3, the optical axis of the visible light output fiber 42 is connected non-parallel to the delivery fiber 34 within a range where the critical angle θ is, and between the end faces of both as required. By providing the distance, the visible laser beam can be incident so that the central axis of the visible light output fiber 42 passes through the end surface of the protruding portion of the cladding 34 b of the delivery fiber 34. At this time, as shown in FIG. 4, the visible laser light is coupled between the end surface of the protruding portion of the clad 34 b of the delivery fiber 34 and the end surface of the visible light output fiber 42 so as to cover the joint portion 57. It is preferable to fill with an adhesive or grease whose refractive index is matched as much as possible.

  With reference to FIGS. 5 and 6, the arrangement of the visible light output fiber 42 with respect to the clad 34b of the delivery fiber 34 will be described more specifically. Both FIG. 5 and FIG. 6 are enlarged views of the vicinity of the joint portion 57. In FIG. 5, the visible light output fiber 42 is disposed substantially parallel to the output fiber 33, and the joint 57 is substantially abutted against the end surface of the protruding portion of the cladding 34 b of the delivery fiber 34. . Here, as shown in FIG. 5A, the core 42a of the visible light output fiber 42 has an outer edge portion on the inner side (a central axis side of the delivery fiber 34) than the outer edge portion of the clad 34b. Therefore, at least part of the core 42a of the visible light output fiber 42 faces the clad 34b of the delivery fiber 34 at the end face, and a part of the transverse mode of visible laser light emitted from the core 42a is coupled to the clad 34b. Visible laser light that has propagated through the core 42 a of the optical output fiber 42 can be incident on the cladding 34 b of the delivery fiber 34. Furthermore, as shown in FIG. 5B, if the central axis of the visible light output fiber 42 is located inside the outer edge of the cladding 34b of the delivery fiber 34, the visible laser light is more efficiently delivered. The clad 34b of 34 can be propagated.

  In FIG. 6, the visible light output fiber 42 is not parallel to the output fiber 33, and visible laser light is incident on the end face of the protruding portion of the cladding 34 b of the delivery fiber 34. Here, as shown in FIG. 6A, in the core 42a of the visible light output fiber 42, the extension line of the outer edge portion is inside the outer edge portion of the clad 34b (the central axis side of the delivery fiber 34). is there. Therefore, at least a part of the transverse mode of the visible laser beam output from the core 42a of the visible light output fiber 42 is coupled to the clad 34b of the delivery fiber 34, so that the visible laser beam propagated through the core 42a of the visible light output fiber 42 is The light can enter the clad 34b of the delivery fiber 34. Further, as shown in FIG. 6B, when the central axis of the visible light output fiber 42 is located inside the outer edge of the cladding 34b of the delivery fiber 34, the visible laser light is more efficiently delivered. The clad 34b of 34 can be propagated.

  Further, as shown in FIG. 7, a monitor PD (Photo PD) is provided in the vicinity of the joint portion 57 so as to receive invisible laser light scattered when coupled from the core 33 a of the output fiber 33 to the core 34 a of the delivery fiber 34. Diode) 70 may be provided. Further, a visible light cut filter 71 may be provided on the front surface of the monitor PD 70, whereby the visible light scattered near the joint 57 can be cut and the output of the invisible laser light can be monitored with higher accuracy.

  In the above embodiment and each of the following embodiments, the visible light LD 40 is in a single mode unless otherwise specified. However, this may be a multimode, and the visible light output fiber 42 is also a single mode at the visible LD wavelength. The effect of the present invention can be obtained in any of the multimodes.

  The visible light LD 40 is composed of, for example, a laser diode that generates red laser light having a wavelength of 638 nm. The visible light LD 40 is not limited to red as in the present embodiment, and green light or the like may be used as long as it is visible light as long as it is visible light. The filter 41 is an optical filter that transmits visible light output from the visible light LD 40 and attenuates return light propagating in the reverse direction from the joint portion 57 during irradiation with invisible laser light (for example, a pass band for visible light). And SWPF (Short Wavelength Pass Filter) or BPF (Band Pass Filter) that uses infrared light as a cutoff band. The return light is mainly composed of an invisible laser light wavelength (1080 nm) described later. In addition, Raman scattered light generated on the long wave side of about 60 nm by invisible laser light and Brillouin scattered light generated close to the wavelength of invisible laser light may be included. The cutoff band of SWPF includes these wavelength ranges. It is desirable to include.

  Note that the output intensity of visible light output from the delivery fiber 34 to the object to be processed is preferably about 2 μW or more, for example, in order to ensure visibility. In order to make visible light visible when using a laser, it is desirable to set the output of the visible light LD 40 to be 10 μW or more. That is, the visible laser beam emitted from the visible light LD 40 is radiated to the workpiece after being attenuated to some extent in the delivery fiber 34, but 2 μW or more, which is a visible intensity even after attenuation, is secured. To be set. Further, the intensity of the return light incident on the visible light LD 40 when the fiber laser device 1 is irradiating the infrared laser is, for example, 10 mW or less in order to prevent the visible light LD 40 from being damaged or shortened. It is desirable to set the characteristics of the filter 41.

  The joint portions 50 to 57 join optical fibers extending from the optical components to each other. The joining portion 56 joins the amplification optical fiber 32 and the output fiber 33, and the joining portion 57 joins the output fiber 33 and the delivery fiber 34 as described above.

  Note that the light output from the end of the optical fiber is incident on a metal member such as aluminum (Al) at the front end side (left side in the drawing) of the joint portion 50, thereby converting the incident light into heat. May be configured to radiate heat after converting the return light of the high-power invisible laser beam incident on the heat conversion unit. In addition to the above-described heat conversion section, for example, an axis misalignment fusion section may be provided near the end of the optical fiber, and leakage light from it may be transmitted to a metal member or the like to be converted into heat. good.

  In addition, a clad mode removing unit that removes light propagating through the clad of the output fiber 33 may be provided between the joint 56 and the joint 57. The clad mode removing portion is formed, for example, by removing the outer clad of the double clad and applying a material having a higher refractive index than that of the inner clad to the removed clad portion. Of course, other configurations are possible.

  Next, the operation of the first embodiment will be described. In the stage before processing the object to be processed, the control unit 20 stops the operations of the visible light LD 40 and the excitation LDs 16 and 36. In such a state, when an object to be processed is placed on a processing table (not shown) and an operation for determining (positioning) a position to irradiate infrared laser light is performed (for example, a “positioning button” (not shown) is pressed). When operated, the CPU 21 of the control unit 20 detects this operation via the I / F 24. The CPU 21 executes processing for positioning based on the program 22a. Specifically, the CPU 21 acquires control data from the data 22b based on the program 22a, performs D / A conversion by the I / F 24, and then supplies the control data to the visible light LD40. As a result, the visible light LD 40 emits red visible laser light, for example. The laser light emitted from the visible light LD 40 is incident on the clad 34 b of the delivery fiber 34 through the filter 41 and the core of the visible light output fiber 42. As described above, the coating 34c covering the clad 34b has a refractive index smaller than that of the clad 34b, and the incident angle θ of the visible light laser is set to be smaller than the critical angle. Then, after propagating through the clad 34b while being totally reflected, it is emitted from the end face and irradiated onto the object to be processed. Since the center of the optical axis of the visible laser light emitted from the clad 34b and the center of the optical axis of the invisible laser light emitted from the core 34a substantially coincide, refer to the irradiation position of the visible laser light, Position adjustment can be performed by adjusting the irradiation position. Visible laser light is attenuated somewhat in the process of passing through the clad 34b. As described above, visibility can be ensured by setting the output light intensity to be 2 μW or more.

  As described above, the processing position can be accurately positioned by irradiating the visible laser beam irradiated from the visible light LD 40 to the position where the infrared laser beam of the processing object is irradiated prior to processing. .

  When the positioning is completed, the control unit 20 stops the irradiation of the visible light LD40. Thereby, irradiation of the visible laser beam to the workpiece is stopped. Note that the processing may be started by irradiating the object to be processed with infrared laser light without stopping the irradiation with visible laser light. Subsequently, when an instruction to start processing is given, the CPU 21 acquires drive data for the excitation LDs 16 and 36 corresponding to the irradiation intensity from the data 22b and supplies the data to the I / F 24. The I / F 24 performs D / A conversion on the supplied drive data and supplies it to the excitation LD drive power supplies 15 and 35. The excitation LD drive power supplies 15 and 35 drive the excitation LDs 16 and 36 in accordance with the instruction value supplied from the I / F 24. As a result, the pumping LDs 16 and 36 emit pumping light and introduce the pumping light into the cladding of the amplification optical fibers 13 and 32 via the pumping light multiplexers 11 and 31. As a result, in the laser oscillation device 10, laser oscillation occurs in the HR 12, the amplification optical fiber 13, and the OC 14, and infrared laser light is emitted from the OC 14. In the laser amplification device 30, the infrared laser light output from the laser oscillation device 10 is amplified by the amplification optical fiber 32, and the object to be processed is irradiated via the output fiber 33 and the joint 57 through the delivery fiber 34. . Since the position irradiated with the infrared laser light is substantially the same as the position irradiated with the visible laser light, the infrared laser light can be irradiated onto a desired position of the workpiece.

  As described above, in the present embodiment, the visible laser beam is incident from the clad in the vicinity of the junction 57 between the output fiber 33 and the delivery fiber 34. Thus, attenuation of visible laser light can be suppressed. For example, visible laser light can be incident from the front stage of the amplification optical fiber 32 or the front stage of the amplification optical fiber 13, but when entering from such a position, the amplification optical fiber through which the visible laser light passes is provided. 13 and 32 and the joint portions 50 to 57 are attenuated, the intensity of the visible laser beam reaching the object to be processed is greatly attenuated. Such attenuation becomes particularly noticeable when a photodarkening phenomenon occurs in the amplification optical fibers 13 and 32 during irradiation with infrared laser light. On the other hand, in this embodiment, since visible laser light does not pass through the amplification optical fibers 13 and 32, attenuation due to the photodarkening phenomenon does not occur, and thus attenuation of visible laser light can be suppressed.

(B) Second Embodiment Next, a second embodiment will be described. In the second embodiment, since only the configuration of the delivery fiber is different from that of the first embodiment, the description below will focus on the configuration of the delivery fiber. FIG. 8 is a cross-sectional view showing a detailed configuration of the joint portion 57 in the second embodiment. As shown in FIG. 8, in the second embodiment, the output fiber 33 and the delivery fiber 64 are connected by a joint portion 57. The delivery fiber 64 has a core 64a at the center, a clad 64b on the outer side, and a coating 64c on the outermost side. In the second embodiment, the delivery fiber 64 is a multimode fiber, the diameter of the clad 64b is 360 μm, and the diameter of the core 64a is 50 μm. As in the first embodiment, the output fiber 33 is a single mode fiber, the diameter of the clad 33b is 200 μm, and the core 33a is 11 μm. The coating 64c of the delivery fiber 64 is made of a material having a refractive index smaller than that of the clad 64b. The cores of the output fiber 33 and the delivery fiber 64 are joined so that their optical axes coincide. The relationship between the clad 64b and the clad 33b and the method for joining the visible light output fiber 42 are the same as in the case of the first embodiment, so that the description thereof is omitted.

  In the second embodiment, compared to the case of the first embodiment, only the configuration of the delivery fiber 64 is different, and the other configuration is the same as that of the first embodiment, and the operation thereof is also the first embodiment. Since it is the same as the embodiment, the description of the operation of the second embodiment is omitted.

  As described above, according to the second embodiment of the present invention, as in the case of the first embodiment, attenuation of visible laser light in the joint portions 50 to 51 and the amplification optical fibers 13 and 32 is suppressed. Therefore, an element having a low emission intensity can be used as the visible light LD 40, so that the manufacturing cost can be reduced.

(C) Third Embodiment Next, a third embodiment will be described. In the third embodiment, since only the configuration of the delivery fiber is different from that of the first embodiment, the description below will focus on the configuration of the delivery fiber. FIG. 9 is a cross-sectional view showing a detailed configuration of the joint portion 57. As shown in FIG. 9, in the third embodiment, the output fiber 33 and the delivery fiber 74 are connected by a joint portion 57. The delivery fiber 74 has a core 74a at the center, a clad 74b on the outer side, and a coating 74c on the outermost side. In the third embodiment, the refractive index distribution is adjusted so that a region where the visible light laser propagates is formed in the clad 74 b of the delivery fiber 74. FIG. 10 is a diagram illustrating an example of the refractive index distribution of the delivery fiber 74. In the example of FIG. 10A, the region having the highest refractive index located at the center of the fiber corresponds to the core 74a. The cladding 74b outside the core 74a is formed by two regions having different refractive indexes. That is, a region having a refractive index lower than that of the core 74a (a region indicated by an arrow) is provided outside the core 74a, and a region having a lower refractive index is provided outside the core 74a. In the example of FIG. 10B, the region having the highest refractive index located at the center of the fiber corresponds to the core 74a. The clad 74b outside the core 74a is composed of three regions having different refractive indexes. That is, a region (indicated by an arrow) having a refractive index slightly lower than that of the core 74a is provided between the core 74a and a region having a refractive index lower than that of the core 74a. In the delivery fiber 74 of FIG. 10A, visible laser light propagates in the clad 74b around the center axis of the fiber. In addition, in the delivery fiber 74 of FIG. 10B, visible laser light is incident on a region indicated by an arrow, and the visible laser light is propagated around a range surrounded by the arrow. That is, in FIG. 10B, visible laser light is propagated around a ring-shaped region indicated by an arrow. For this reason, in the third embodiment, unlike the first and second embodiments, the refractive index of the coating 34c can be set arbitrarily.

  Note that the third embodiment differs from the first embodiment only in the region in which the visible laser beam is propagated in the cladding 74b, and the other operations are the same as those in the first embodiment. Will not be described.

  According to the third embodiment of the present invention, as in the case of the first embodiment, it is possible to suppress the attenuation of visible laser light in the joint portions 50 to 51 and the amplification optical fibers 13 and 32. Further, by providing a region through which the visible laser light propagates, the visible laser light can be propagated to the object to be processed with less attenuation. In the example of FIG. 9, a single mode fiber is used as the delivery fiber 74, but a multimode fiber may be used.

(D) Fourth Embodiment Next, a fourth embodiment will be described. In the fourth embodiment, the position where the visible laser beam is incident is different from that in the first embodiment, and other configurations are the same as those in the first embodiment. A description will be given focusing on the configuration in which light is incident. FIG. 11 is a cross-sectional view showing a detailed configuration of the joint portion 57. As shown in FIG. 11, in the fourth embodiment, the visible light output fiber 42 is not on the end face of the joint portion 57 of the clad 34b but on the outer peripheral surface of the clad 34b at a position away from the joint portion 57 by a predetermined distance. It is connected. In the example of FIG. 11, the visible laser light emitted from the visible light output fiber 42 is propagated while reflecting the inside of the clad 34b. The position where the visible light output fiber 42 is attached is set so that the visible laser beam does not strike the coating 34c and the angle θ formed with the irradiation surface of the clad 34b is smaller than the critical angle. In addition, the incident direction is set so as to hit the irradiation surface of the clad 34b from the inside of the clad 34b, as in the case of the first embodiment.

  Note that the fourth embodiment differs from the first embodiment only in the position where the visible laser beam is incident on the clad 74b, and the other operations are the same as those in the first embodiment. Will not be described.

  According to the fourth embodiment of the present invention, similarly to the first embodiment, attenuation of visible laser light in the joint portions 50 to 51 and the amplification optical fibers 13 and 32 can be suppressed. Moreover, in 4th Embodiment, compared with 1st-3rd embodiment, the influence of the heat which originates in the light scattered in the junction part 57 can be relieve | moderated. That is, in the fourth embodiment, visible laser light generated by the laser light generated by the laser oscillation device 10 or the laser amplification device 30 or the residual excitation light being scattered at the junction 57 and converted into heat to increase the ambient temperature. It is possible to suppress the change in the binding state. In the example of FIG. 11, an adhesive, resin, or grease whose refractive index is substantially matched may be filled from the output end of the visible light output fiber 42 to the incident portion on the side surface of the clad 34 b of the delivery fiber 34. Further, although a single mode fiber is used as the delivery fiber 34, a multimode fiber may be used.

(E) Fifth Embodiment Next, a fifth embodiment will be described. In the fifth embodiment, the configuration for making visible laser light incident is different from that in the first embodiment, and other configurations are the same as those in the first embodiment. A description will be given focusing on the configuration in which the laser light is incident. FIG. 12 shows a detailed configuration of the joint portion 57. As shown in FIG. 12, in the fifth embodiment, one end portion (right end portion in the figure) of the visible light output fiber 82 is the outer peripheral surface of the cladding 64b of the delivery fiber 64 with the coating 82c removed. The clad 82b is disposed so that the outer peripheral surface thereof is in contact therewith. Although not shown in FIG. 12, visible laser light emitted from the filter 41 is incident on the other end (the left end in the figure) of the visible light output fiber 82, and the visible light output fiber 82 is propagated in the cladding 82b. As a method for propagating the visible laser light into the clad, for example, by connecting a single mode fiber, a multimode fiber, and a single mode fiber in this order, the visible laser beam propagating through the core 82a is clad 82b. Can lead in. Alternatively, the visible laser light can be propagated in the clad by using an optical fiber having no core.

  In the fifth embodiment, the visible laser light output from the visible light LD 40 is propagated in the cladding 82b of the visible light output fiber 82 as indicated by the arrows shown in FIG. Such visible laser light propagating in the clad 82b is incident on the clad 64b from the connecting portion with the clad 64b, propagates in the clad 64b, and is irradiated on the object to be processed from the end face of the clad 64b.

  According to the fifth embodiment of the present invention, similarly to the first embodiment, attenuation of visible laser light in the joint portions 50 to 51 and the amplification optical fibers 13 and 32 can be suppressed. Further, as in the case of the fourth embodiment, the return light incident on the visible light LD 40 can be reduced. In the example of FIG. 12, a multimode fiber is used as the delivery fiber 64, but a single mode fiber may be used.

(F) Modified Embodiment Each of the above embodiments is an example, and there are various modified embodiments other than this. For example, in each of the embodiments described above, the fiber laser device 1 including the laser oscillation device 10 and the laser amplification device 30 has been described as an example. . Further, in each of the above embodiments, the case where both the laser oscillation device 10 and the laser amplification device 30 are forward pumped has been described as an example. However, backward pumping or bidirectional pumping can be applied to the present invention. . That is, when only the laser oscillation device 10 is configured, any of forward pumping, backward pumping, or bidirectional pumping can be employed. Further, when the laser oscillation device 10 and the laser amplification device 30 are configured, each of the laser oscillation device 10 and the laser amplification device 30 is selected from forward excitation, backward excitation, and bidirectional excitation. They can be selected and combined as appropriate.

  In each of the above embodiments, visible laser light is incident on the cladding of the delivery fiber, but may be incident on the cladding 33b of the output fiber 33 in the vicinity of the joint 57.

  Further, in each of the above embodiments, the filter 41 is provided on the output side of the visible light LD 40, but the filter 41 may not be provided. For example, when the intensity of the return light is small, the filter 41 can be omitted. In this case, the visible light output fiber 42 is directly connected to the visible light LD 40. Further, as the filter 41, an FBG whose reflection band is substantially the same wavelength band as the wavelength band of the infrared laser light may be used.

  Further, in each of the above embodiments, the laser amplifying apparatus has a single-stage configuration, but two or more stages may be provided.

  In each of the above embodiments, the red laser light is used as the visible light LD 40. However, for example, a green laser light may be used. Since the human eye is more sensitive to green than red, when using green visible light LD, the intensity of the visible laser light applied to the workpiece is set to a value lower than 2 μW. be able to. More specifically, according to the standard relative luminous efficiency curve, the human eye feels the wavelength near the wavelength of 555 nm the brightest, and in the red (for example, wavelength 635-690 nm) longer than that, the sensitivity is, for example, It drops to about 1/5 to 1/10. Therefore, when green visible light LD having a wavelength near 555 nm is used, the intensity of visible laser light irradiated on the object to be processed is set to a value lower than 2 μW (for example, 0.4 to 0.2 μW). be able to.

  In each of the above embodiments, the excitation LD is driven by the excitation LD drive power supply. However, the control unit 20 directly drives each excitation LD, or a control signal from the control unit. The FET (Field Effect Transistor) may be controlled based on the above, and the current flowing through each excitation LD may be controlled by the FET.

DESCRIPTION OF SYMBOLS 1 Fiber laser apparatus 10 Laser oscillation apparatus 11 Excitation light multiplexer 12 HR
13 Amplifying optical fiber 14 OC
15 Excitation LD drive power supply 16 Excitation LD
20 Control unit (drive unit)
DESCRIPTION OF SYMBOLS 30 Laser amplifier 31 Excitation light multiplexer 32 Optical fiber for amplification 33 Output fiber 34 Delivery fiber 35 LD drive power supply for excitation 36 LD for excitation
40 Visible light LD (visible laser light source)
41 Filter 42 Visible light output fiber (introduction section)
51-57 joint

Claims (7)

In a fiber laser device that generates invisible laser light and outputs it through a delivery fiber,
A visible laser light source that generates visible laser light;
An introduction part for introducing the visible laser light generated by the visible laser light source into a cladding in the vicinity of a joint part between the output fiber from which the generated invisible laser light is output and the delivery fiber;
When positioning the irradiation of the invisible laser beam to the workpiece, the visible laser light source is driven, the visible laser beam is emitted through the cladding of the delivery fiber, and the workpiece is processed at the processing position. A drive unit that emits visible laser light;
A fiber laser device comprising:   The fiber laser device according to claim 1, wherein the delivery fiber is set so that a refractive index of a coating covering the clad is smaller than a refractive index of the clad.   2. The fiber laser device according to claim 1, wherein the delivery fiber has a refractive index distribution of a clad so as to form a region in which the visible laser light propagates.   4. The fiber laser device according to claim 1, wherein the introducing portion introduces the visible laser light from a clad in the vicinity of the joint portion of the delivery fiber. 5. The delivery fiber cladding is larger in diameter than the output fiber cladding,
5. The fiber according to claim 1, wherein the introduction portion introduces the visible laser light from an end surface of a clad of the delivery fiber at a portion protruding in a radial direction at the joint portion. Laser device.   The fiber laser device according to claim 1, wherein the introduction part introduces the visible laser light from an outer peripheral surface of a clad in the vicinity of the joint part of the delivery fiber.   The introduction part has an optical fiber in which the clad is in contact with an outer peripheral surface of the clad in the vicinity of the joint part of the delivery fiber, and the visible laser light propagates through the clad, and propagates through the clad of the optical fiber. The fiber laser device according to claim 1, wherein the visible laser beam is incident on the clad of the delivery fiber from the contact portion.

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