JP6485237B2 - Combined laser light source - Google Patents

Description

  The present invention relates to a combined laser light source that combines laser beams from a plurality of independent light sources to achieve high brightness. The present invention also relates to an exposure apparatus, a processing machine, an illumination device, and a medical device using the above-described combined laser light source as a light source.

  Conventionally, as a method for increasing the output of a laser, a method of combining a plurality of laser beams from a plurality of light sources into a single optical fiber (Patent Document 1) or a bundle of fibers combined with a plurality of light sources is bundled. There is a known method of coupling to a single fiber.

  In particular, in order to obtain emitted light with little intensity unevenness from a fiber, (1) a light source in which semiconductor laser chips called semiconductor laser arrays are arranged at high density at intervals of about several hundreds μm as a light source, or a semiconductor laser bar is used. (2) A plurality of laser light sources to be emitted are realized by a series of means such as anamorphic optical system and steering optical system, which are rearranged with high density immediately before the condensing lens for fiber coupling.

JP 2002-202442 A

  However, short-wavelength semiconductor lasers are generally mounted in a windowed semiconductor laser package (TO-Can package) in which dry nitrogen or dry air having a diameter of 5.6 mm or a diameter of 9 mm is enclosed in order to prevent end face deterioration due to foreign matter adhesion. To be used. Therefore, when the package size is specified, it is difficult to arrange the semiconductor lasers with high density. For this reason, the light flux incident on the coupling lens forms a coarse and dense distribution, and the intensity distribution of the light intensity of the fiber output becomes uneven, and uniform irradiation cannot be performed. When the quality of the laser beam is deteriorated as described above, the function is deteriorated for any laser application such as exposure, processing, and illumination, which are the purposes of the combined laser.

  In the case of exposure and illumination, uniform exposure and illumination cannot be performed, and in the case of processing, the focused beam is not practically a single point and fine processing cannot be performed.

  Accordingly, an object of the present invention is to reduce the intensity distribution unevenness of the fiber output light in the case of a light emitting light source having a luminous flux with discrete laser beam intervals for each laser emission size. It is to provide a wave laser light source. Here, the meaning of discrete means that it is equal to or larger than the light emitting point interval of a bar-shaped array laser element having a light emitting portion in a normal array shape, depending on the use of the laser light. The laser here does not necessarily need to be a semiconductor laser, and can target a plurality of laser beams that cannot approach each other.

In order to solve the above problems, a combined laser light source according to the present invention is a light source having discrete light beams with respect to the light emission size of each laser, and is arranged at predetermined intervals from each other. disposed between the plurality of laser light sources but which outputs a laser beam, and a plurality of lenses arranged in a predetermined interval to face the plurality of laser light sources, and an optical waveguide, and the optical waveguide and the plurality of lenses A coupling lens that couples a plurality of laser beams from the plurality of lenses to the optical waveguide, a collimator lens that collimates the light emitted from the optical waveguide, an output fiber, and the output It is disposed between the fiber and the collimating lens, the light emitted from the collimating lens and a recombination lens for recombining into the output fiber, the optical waveguide Wherein the multiplication value of the A diameter as the exit angle is less than the multiplied value of the incident angle and the core diameter of the output fiber.

  According to the present invention, a plurality of laser beams are coupled to an optical waveguide whose multiplication value of the core diameter and the emission angle of the optical waveguide is equal to or less than the multiplication value of the core diameter and the incident angle of the output fiber, When the light emitted from the optical waveguide is recoupled to the output fiber by the recombination lens, the intensity distribution unevenness of the fiber output light can be suppressed.

It is a figure which shows the structure of the combining laser light source of Example 1 of this invention. It is a figure which shows the relationship between an optical waveguide and output fiber in the combined laser light source of Example 1 of this invention. It is a figure which shows the structure of the combining laser light source of Example 2 of this invention. It is a figure which shows the structure of the combining laser light source of Example 3 of this invention.

  Embodiments of a combined laser light source according to the present invention will be described in detail below with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a combined laser light source according to the first embodiment. The combined laser light source of Example 1 shown in FIG. 1 includes semiconductor lasers 1a to 1c, lenses 2a to 2c, a coupling lens 3, an optical waveguide 4, a collimating lens 5, a recombination lens 7, and an output fiber 8. . Here, each element number is assigned as a subscript, and a to c do not mean three, but mean two or more.

  The semiconductor lasers 1a to 1c are arranged at predetermined intervals, and are excited by carrier injection composed of electrons and holes injected by current drive, and are induced emission generated when the injected electron and hole carrier pairs are annihilated. The laser beam generated by is output. The semiconductor laser may be an array laser having a plurality of laser emission mechanisms in a bar-shaped semiconductor, or a laser having a planar light emission distribution such as a surface emitting laser or a stack laser in which bar-shaped array lasers are stacked.

  In the case of a short wavelength laser with a wavelength of 530 nm or less, since the photon energy of the laser becomes large, foreign matter contamination or adhesion is generated due to adhesion of particles or chemical reaction including the surface material of the semiconductor laser on the laser emission end face. It is known to do. Therefore, the laser is often used by being housed in an airtight package in which an inert gas such as dry nitrogen or dry air is sealed.

  In the case of a single-chip semiconductor laser, as the plurality of semiconductor lasers 1a to 1c, for example, elements individually sealed with a To-Can package with a transparent window such as optical glass or sapphire may be used.

  The lenses 2 a to 2 c are arranged at predetermined intervals so as to face the semiconductor lasers 1 a to 1 c, and guide the laser beams from the semiconductor lasers 1 a to 1 c to the coupling lens 3. When the beam divergence angle is large as in the case of a semiconductor laser, it is preferable to use a collimated arrangement capable of obtaining a certain amount of parallel light. In the case of a laser having a small divergence angle, the lenses 2a to 2c are not necessarily required.

  The coupling lens 3 serves as a condensing lens and condenses a plurality of laser beams from the semiconductor lasers 1a to 1c into the optical waveguide 4 by condensing them.

  The optical waveguide 4 is made of an optical fiber and is disposed between the coupling lens 3 and the collimating lens 5. The relationship between the optical waveguide 4 and the output fiber 8 is shown in FIG. In FIG. 2, the optical waveguide 4 includes a core 4a and a clad 4b disposed outside the core 4a, and the diameter of the core 4a is Φ1. The emission angle of the laser beam from the center of the core 4a to the collimating lens 5 is θ1.

  As a material of the optical waveguide 4, for example, quartz glass can be used. The refractive index of the core 4a is higher than the refractive index of the clad 4b. Thus, each laser beam entering from one end of the optical waveguide 4 travels while being reflected in the core 4a without being leaked from the core 4a to the clad 4b, and is emitted from the other end.

  The output fiber 8 includes a core 8a and a clad 8b disposed outside the core 8a. The diameter of the core 8a is Φ2. The incident angle from the recombination lens 7 to the center of the core 8a is θ2. The optical waveguide 4 is formed of a waveguide in which the multiplication value of the core diameter Φ1 of the optical waveguide 4 and the emission angle θ1 is equal to or less than the multiplication value of the core diameter Φ2 of the output optical fiber 8 and the incident angle θ2.

  That is, since the multiplication value of the core diameter Φ2 of the output optical fiber 8 and the incident angle θ2 is larger than the multiplication value of the core diameter Φ1 of the optical waveguide 4 and the emission angle θ1, each laser beam from the optical waveguide 4 is The light can be guided to the output optical fiber 8.

  Moreover, the refractive index of the core 8a is higher than the refractive index of the clad 8b. Thus, each laser beam entering from one end of the output fiber 8 travels while being reflected in the core 8a without leaking from the core 8a to the cladding 8b, and is emitted from the other end.

  The collimating lens 5 outputs a plurality of laser beams from the optical waveguide 4 as parallel light. In the parallel light from the collimating lens 5, unevenness occurs as shown by the intensity distribution 6 in FIG. The example shown in FIG. 1 is a case where the laser beam density is low.

  However, in the first embodiment, a plurality of parallel lights from the collimating lens 5 are further recombined with the output fiber 8 by the recombination lens 7. As the output fiber 8, for example, a step index type fiber having a pure silica core is used.

  According to the above configuration, the laser beam from the plurality of semiconductor lasers 1a to 1c is combined with the coupling lens 3s, and the product of the core diameter Φ1 and the emission angle θ1 of the optical waveguide 4 is the core diameter of the output optical fiber. When the light output from the optical waveguide 4 is coupled to the output optical fiber 8 by the recombination lens 7 when coupled to the optical waveguide 4 which is equal to or less than the product of Φ2 and the incident angle θ2, the intensity distribution of the fiber output light is uneven. Can be suppressed.

  For this reason, it is particularly useful when the number of semiconductor lasers is small or when the semiconductor lasers cannot be arranged with high density due to the size of the semiconductor laser.

  Here, the case of a semiconductor laser as an example of the laser light source has been described. However, a laser light source in which a plurality of ordinary laser devices are installed or a laser beam that bundles a plurality of fibers is shown. Such a laser light source can also be implemented.

  FIG. 3 is a diagram illustrating the relationship between the optical waveguide and the output fiber in the combined laser light source according to the second embodiment of the present invention. In the combined laser light source of the first embodiment shown in FIG. 1, one of the plurality of semiconductor lasers 2b is arranged on the fiber optical axis. However, the combined laser light source of the second embodiment includes a plurality of semiconductor lasers. In this example, 1a to 1d are not arranged on the fiber optical axis.

  A plurality of lenses 2a to 2d are arranged in a direction corresponding to the plurality of semiconductor lasers 1a to 1d. The coupling lens 3 couples a plurality of laser beams from the plurality of lenses 2 a to 2 d to the optical waveguide 4.

  In this case, in the intensity distribution 6a due to a plurality of parallel lights from the collimating lens 5, the vicinity of the optical axis of the fiber becomes dark, but the light emitted from the optical waveguide 4 is recombined to the output optical fiber 8 by the recombination lens 7. Therefore, unevenness in the intensity distribution of the fiber output light can be suppressed.

  FIG. 4 is a diagram showing the configuration of the combined laser light source according to the third embodiment of the present invention. In the embodiment shown in FIGS. 1 and 3, the discrete recombination lens 7 is used as the recombination optical system. However, the combined laser light source of Embodiment 3 is provided between the optical waveguide 4 and the output fiber 8. It is characterized in that the green rod lens 10 is arranged in the above.

  The green rod lens 10 has a cylindrical shape, is formed so that the refractive index changes in the radial direction, and functions as a condensing lens. For this reason, the grind rod lens 10 has a function of the collimating lens 5 and the recombination lens 7.

  Therefore, since the grind rod lens 10 operates like the collimating lens 5 and the recombination lens 7 of the first embodiment, the same effects as those of the first embodiment can be obtained in the third embodiment. Further, by using the grind rod lens 10, the combined laser light source can be reduced in size.

  The combined laser light source according to the present invention is particularly applicable to laser processing apparatus, laser illumination, laser exposure apparatus, fluorescent material excitation, laser measurement, laser medical treatment, and the like.

DESCRIPTION OF SYMBOLS 1a-1d Semiconductor laser 2a-2d Lens 3 Coupling lens 4 Optical waveguide 4a, 8a Core 4b, 8b Cladding 5 Collimating lens 6 Light intensity distribution 7 Recombination lens 8 Output fiber 10 Grinrod lens

Claims (3)

A plurality of laser light sources each having a light beam having a discrete light flux with respect to the emission size of each laser and arranged at predetermined intervals, each of which outputs laser light;
A plurality of lenses disposed at predetermined intervals facing the plurality of laser light sources;
An optical waveguide;
A coupling lens disposed between the plurality of lenses and the optical waveguide, and coupled to the optical waveguide by condensing a plurality of laser beams from the plurality of lenses;
A collimating lens for collimating the light emitted from the optical waveguide;
An output fiber;
A recombination lens disposed between the output fiber and the collimating lens, and recombining light emitted from the collimating lens to the output fiber;
A combined laser light source, wherein a product of a core diameter and an emission angle of the optical waveguide is equal to or less than a product of a core diameter and an incident angle of the output fiber.   2. The combined laser light source according to claim 1, further comprising a sealing package for sealing the plurality of laser light sources. 3. The combined laser light source according to claim 1, wherein the output fiber is a step index type fiber having a pure silica core.

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