JPH06250124A - Laser light source - Google Patents

Abstract

PURPOSE:To superpose two laser beams without extending the size of the spot of the laser beam. CONSTITUTION:The first laser beam polarized in a first direction is made incident on a polarization beam splitter 3, and a second laser beam arranged in the direction orthogonally intersecting with the first laser beam polarized in the first direction is rotated in a second direction by an azimuth rotator 4 to be made incident on the polarization beam splitter 3, and the second laser beam is reflected by the polarization splitter 3 to be superposed on the first laser beam, and the laser beam where the first laser beam spot and the second laser spot are superposed is emitted from the polarization beam splitter 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser light source suitable for application to an apparatus for processing using laser light, and more particularly to a laser light source capable of obtaining a small beam spot.

[0002]

2. Description of the Related Art Since laser light has a constant wavelength and is coherent in phase, it is possible to concentrate energy at one point. The high energy concentration of this laser light is incomparably large, unlike mixed light in a wide wavelength band such as sunlight, and when focused with a lens to a minute spot of about 0.2 mm, it is Since the energy density is as high as 1 million to 100 million watts, laser processing has been conventionally performed by utilizing its characteristics.

Since the optical end of the focused high-power laser beam has a high temperature of several thousand to several thousand degrees, heavy processing such as melting, punching or cutting metal or a workpiece is required. I can. As a laser beam for performing such heavy processing, a solid-state laser such as a YAG laser or a gas laser such as a CO ₂ laser is used.

On the other hand, a semiconductor laser is used for light processing such as soldering or digging grooves for characters, images, etc. on a plate for printing, but the output of one semiconductor laser chip is small. Therefore, the required laser output has been obtained by arranging the laser diodes in an array.

An example of the structure of such a conventional laser diode array is shown in FIG. In this figure, 61 is a laser diode array in which laser diodes are integrated, 62 is a laser light emitting end face of the laser diode, and 63 is
Is a substrate of a surface emitting laser diode array, 64 is an arrayed laser diode, 65 and 66 are laser beams emitted from the laser diode 64, and 67 is an active layer 69.
Is a light path of the light oscillated in step 6, 68 is a reflection mirror that reflects the emitted laser light upward, and 69 is an active layer that oscillates the light.

In the laser diode array 61 shown in FIG. 6A, the emission end faces 62 of the laser light are arranged in the lateral direction, and the laser light emitted from each emission end face is condensed to the work piece. Irradiation is performed so that the workpiece is processed. Further, in the laser diode array shown in FIG. 6B, the emission end faces of the laser diode 64 are arranged on the integrated surface, and the laser light 65 emitted from each emission end face is condensed to be processed. Are irradiated onto the workpiece, and the workpiece is processed.

FIG. 6C shows a cross section of one laser diode which constitutes the laser diode array shown in FIG. 6B. In this laser diode, the light oscillated in the active layer 69 is emitted from its end face and reflected. The laser light is reflected by the mirror 68 to emit laser light upward.
Such a laser diode having a laser light emitting end face on the upper surface is integrated to form a surface emitting laser as shown in FIG.

[0008]

Generally, a far field pattern (FFP) of laser light emitted from a semiconductor laser has a pattern as shown in FIG. In (a) of this figure, 71 is a semiconductor laser that emits a laser beam, 72 is a laser beam that is emitted forward from the semiconductor laser 71, and 73 is a laser beam that is emitted backward from the semiconductor laser 71.

The FFP of the laser light emitted from the semiconductor laser 71 is a vertically long ellipse because its emission end face is horizontally long. The beam width in the minor axis direction of this ellipse is shown in FIG.
The beam width in the major axis direction is shown in (b) of FIG. Θ‖ shown in FIGS. 7B and 7C is θ⊥ in the X direction (transverse direction).
Indicates the full width at half maximum of the beam emission angle of the semiconductor laser 71 in the Y direction (longitudinal direction). As shown in FIGS. 7B and 7C, the full angle at half maximum θ‖ is smaller than the full angle at half maximum θ⊥, and the beam of the laser light emitted from the semiconductor laser 71 spreads in the Y direction. The FFP becomes an ellipse.

By the way, in order to increase the precision of laser processing, it is necessary to reduce the spot of laser light. However, if the laser diode array shown in FIGS. Since the emission end faces of the laser diodes are arranged in a row or in a plane, the equivalent area of the emission end faces of the laser light becomes large, making it difficult to focus the laser light from the laser diode array at one point. Becomes Therefore, there is a problem that the spot of the laser beam cannot be reduced.

Further, in order to reduce the spot of the laser beam, one semiconductor laser may be used in place of the semiconductor laser array, but the output of a single semiconductor laser is small and it is difficult to process with this output. To use it, it is necessary to increase the output of a single semiconductor laser. However, in order to increase the output of the single semiconductor laser, it is necessary to increase the size and area of the emission end face a of the semiconductor laser shown in FIG. 2. By doing so, the size and area of the emission end face a of the semiconductor laser are increased. Therefore, also in this case, there is a problem that the spot of the laser beam cannot be made small as described above.

Therefore, an object of the present invention is to provide a laser light source capable of obtaining a small laser beam spot by superimposing the laser outputs of two semiconductor lasers without increasing the emission end face of the semiconductor laser. There is.

[0013]

In order to achieve the above object, in the laser light source of the present invention, a laser beam from one of the semiconductor lasers is directly applied to the polarizing beam splitter by using a polarizing beam splitter and an optical rotator. The laser output from the other semiconductor laser arranged orthogonal to the one semiconductor laser is applied to the polarization beam splitter via the optical rotator, and the two laser outputs are superposed on each other in the polarization beam splitter.

[0014]

Since the semiconductor laser generally emits linearly polarized light having an electric field component parallel to the junction surface, the laser light from the other semiconductor laser which is π / 2 rotated by the optical rotator is reflected by the polarization beam splitter. And is superposed on the laser beam from one semiconductor laser which is orthogonally arranged with respect to the other semiconductor laser which transmits the polarization beam splitter. Therefore, since the spots of the laser light from the two semiconductor lasers are superposed on each other, it is possible to obtain the laser light of double output with a small spot without spreading the spots.

[0015]

FIG. 1 shows a first embodiment of the laser light source of the present invention. In this figure, 1 is a first light source consisting of a semiconductor laser, 2 is a collimator lens for collimating the light flux of the laser light from the first light source 1, and 3 is a plane perpendicular to the plane of the drawing. The reflected laser light is reflected and its optical path is changed to 9
A beam splitter 4 which bends the laser light polarized by 0 ° and is polarized in a plane parallel to the paper surface, 4 is an optical rotator that rotates the polarization plane of the laser light by π / 2, and 5 is a laser light from the second light source. Collimator lens for making the light flux of the laser beam parallel, 6 is a second light source composed of a semiconductor laser arranged orthogonally to the first light source, 7 is an objective lens for focusing the laser light on the workpiece 8, and 8 is the laser light To be processed by 9
Is the polarization direction of the laser light from the first light source, 10 is the polarization direction of the laser light from the second light source, and 11 is the polarization direction of the second light source rotated by the optical rotator 4.

In the laser light source shown in FIG. 1, the laser light emitted from the first semiconductor laser 1 is made into a parallel light flux by the collimator lens 2 and is incident on the polarization beam splitter 3. This laser light is shown in FIG. Since it is polarized as described above, it passes through the polarization beam splitter 3 as it is. The transmitted laser light is condensed by the objective lens and is irradiated on the workpiece 8 to process the workpiece 8.

The laser light emitted from the second semiconductor laser 6 is made into a parallel light flux by the collimator lens 5 and enters the optical rotator 4. The laser light emitted from the second semiconductor laser 6 is polarized as shown in FIG. 10 and is rotated by π / 2 by the optical rotator 4 as shown in 11. The π / 2-rotated laser beam is incident on the polarization beam splitter 3, and since it is π / 2-rotated, it is reflected by the polarization beam splitter 3 so as to be incident on the objective lens 7.

The laser light from the second semiconductor laser 6 incident on the objective lens 7 is condensed by the objective lens 7 and irradiated on the workpiece 8 in the same manner as the laser light from the first semiconductor laser 1. It Thus, the first semiconductor laser 1
Laser beam spot from the second semiconductor laser and the spot of the laser beam from the second semiconductor laser are overlapped and irradiated to the workpiece 8, the laser power is doubled, and the beam spot of the overlapped laser beam is It will not spread. Therefore, according to the laser light source shown in FIG. 1, the workpiece 8 can be finely processed with sufficient power.

FIG. 2 shows an example of the first semiconductor laser and the second semiconductor laser used for the laser light source shown in FIG.
In FIG. 2, reference numeral 20 denotes a positive electrode for applying a positive voltage, 21
Is a p-type GaAs layer, 22 is a p-type GaAlAs cladding layer, 23 is a p-type GaAs active layer, 24 is an n-type GaAlAs cladding layer, 25 is an n-type GaAs substrate, and a is a laser. This is a region through which an electric current is passed in order to emit light.

The laser diode shown in FIG. 2 has a double hetero structure, in which the active layer 23 as a light emitting portion is sandwiched from both sides by the clad layers 22 and 24 having a wide forbidden band width and a small refractive index. Therefore, the carriers injected into the active layer 23 are confined in the active layer 23 due to the difference in the forbidden band width, and contribute efficiently to light emission.

The light generated from the active layer 23 does not leak to the outer layer due to the difference in the refractive index, and is confined in the active layer 23 functioning as an optical waveguide. In this way
Efficient laser oscillation is possible. Further, in the horizontal direction of the active layer 23, the region a through which a current flows is limited,
By causing laser oscillation only in the portion a, linearly polarized light having an electric field component parallel to the joint surface is emitted from the end face a.

FIG. 3 shows a second embodiment of the laser light source according to the present invention. In this figure, 1 is a first light source consisting of a semiconductor laser, 2 is a collimator lens for collimating the light flux of the laser light from the first light source 1, and 3 is a plane perpendicular to the plane of the drawing. A beam splitter that reflects the laser light that is present, bends its optical path by 90 degrees, and transmits the laser light that is polarized in a plane parallel to the paper surface, and 4 is an optical rotator that rotates the polarization plane of the laser light by π / 2. 5 is a collimator lens for collimating the light flux of the laser light from the second light source,
Reference numeral 6 denotes a second light source formed of a semiconductor laser arranged orthogonally to the first light source 1, 7 denotes an objective lens for focusing laser light on a workpiece, 8 denotes a workpiece processed by the laser light, and 9 denotes The polarization direction of the laser light from the first light source, 10 is the polarization direction of the laser light from the second light source, and 11 is the optical rotator 4.
The polarization direction of the second light source rotatively polarized by 12 is an anamorphic prism pair for shaping an elliptical beam into a circular beam.

In the laser light source shown in FIG. 3, the laser light emitted from the first semiconductor laser 1 is made into a parallel light flux by the collimator lens 2 and is incident on the polarization beam splitter 3. Since the light is polarized as, the light passes through the polarization beam splitter 3 as it is. The laser light emitted from the second semiconductor laser 6 is made into a parallel light flux by the collimator lens 5 and enters the optical rotator 4. The laser light emitted from the second semiconductor laser 6 is polarized as shown by 10 and is rotated by the optical rotator 4.
As shown in 1, the light is rotated by π / 2.

The π / 2-rotated laser beam is incident on the polarization beam splitter 3, and since it is π / 2-rotated, it is reflected by the polarization beam splitter 3 so as to be incident on the anamorphic prism pair 12. Therefore, the polarization beam splitter 3 causes the spots of the laser light emitted from the first semiconductor laser 1 and the second semiconductor laser 6 to be superposed and incident on the anamorphic prism pair 12. Then, the elliptical laser light incident on the anamorphic prism pair 12 is shaped into a substantially circular beam by the anamorphic prism pair 12, is condensed by the objective lens 7, and is irradiated onto the workpiece 8. The workpiece 8 is processed by.

As described above, the spot of the laser light from the first semiconductor laser 1 and the spot of the laser light from the second semiconductor laser 2 are superposed, shaped into a substantially circular shape, and irradiated onto the workpiece 8. Therefore, the power of laser light is 2
In addition, the beam spot of the laser light can be made into a small spot having a substantially circular shape. Therefore, according to the laser light source shown in FIG. 3, the workpiece 8 can be finely processed with sufficient power.

The anamorphic prism pair 12 for shaping the elliptical laser beam into a substantially circular shape is used instead of the anamorphic prism pair 12 shown in FIG.
It can be shaped into a substantially circular shape by using the cylindrical lens shown in. The cylindrical lens shown in FIG. 4 includes a concave lens 41 and a collimator lens 42, and the minor axis of the incident elliptical laser beam is Din.
Then, the incident laser beam in the minor axis Din direction is expanded in the minor axis direction by the concave lens 41 and enters the collimator lens 42. In addition, the beam of the elliptical laser beam in the long axis direction is the concave lens 41 and the collimator lens 4.
The light is emitted from the lenses 41 and 42 without any change even when passing through 2.

Therefore, the spot of the laser beam Dout formed into a parallel light beam by the collimator lens 42 is expanded only in the minor axis direction and shaped into a substantially circular beam. Next, the structure of the anamorphic prism pair 12 for shaping the elliptical laser beam into a circle is shown in FIG.

In FIG. 5, reference numeral 51 is a housing which houses an anamorphic prism pair, 52 is a first prism, 53 is a second prism, 54 is a mount for supporting the first prism, and 55 is a second prism. Mount for supporting the prism, 56 is a recess into which the incident light source unit is inserted, 57 is a screw hole for fixing the incident light source unit so as not to separate from the housing 51, 58 is incident light from the incident light source unit, and 59.
Is the emitted light shaped into a substantially circular beam, Din is the diameter of the minor axis of the elliptical beam incident, and Dout is the diameter of the shaped circular beam.

In the anamorphic prism pair shown in FIG. 5, the elliptical beam 58 incident from the incident light source is incident on the anamorphic prism pair so that its short axis Din is in the direction shown. The incident laser beam 58 is refracted by the first prism 52 and its minor axis is expanded in the axial direction. The laser beam emitted from the first prism 52 is then incident on the second prism 53, and the laser beam in the minor axis direction is refracted to be further expanded in the axial direction to have a width Dout shown in the figure. It

On the other hand, the incident beam of the laser beam 58 in the long axis direction is not affected even when refracted by the first and second prisms 52 and 53, so that the width at the time of incidence is kept to the second level. It is emitted from the prism 53. Therefore, the laser beam 59 emitted from the second prism 53 is expanded only in the minor axis direction, so that it is shaped into a substantially circular shape and emitted from the anamorphic prism pair.

If such a lens or prism for shaping the laser beam into a substantially circular shape is used, the spot of the laser beam for processing the workpiece can be made into a substantially circular shape, and the processing can be facilitated. As the optical rotator, it is possible to use a plurality of 90-degree TN liquid crystal or crystal polarizers.

[0032]

Since the present invention is constructed as described above, according to the laser light source of the present invention, it is possible to obtain double laser output with a small spot of one semiconductor laser. Further, the laser beam can be a circular beam instead of an ellipse, which is convenient when the laser light source of the present invention is used for laser processing.

[Brief description of drawings]

FIG. 1 is a diagram showing a laser light source according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of a laser diode.

FIG. 3 is a diagram showing a laser light source according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a cylindrical lens that shapes an elliptical beam into a circle.

FIG. 5 is a diagram showing an anamorphic prism pair that shapes an elliptical beam into a circle.

FIG. 6 is a diagram showing an example of a laser diode array.

FIG. 7 is a diagram showing characteristics of a beam emitted from a laser diode.

[Explanation of symbols]

 1 First Light Source 2, 5 Collimator Lens 3 Polarizing Beam Splitter 4 Optical Rotator 6 Second Light Source 7 Objective Lens 8 Workpiece 9, 10, 11 Polarization Direction of Laser Light 12 Anamorphic Prism Pair 20 Positive Electrode 21 GaAs Layer 22 Clad layer 23 Active layer 24 Clad layer 25 GaAs substrate 41 Concave lens 42 Collimator lens 51 Housing 52, 53 Prism 54, 55 Mount 56 Recess 57 Screw hole 58 Incident light 59 Emission light 61 Laser diode array 62 Emission end face 63 Laser diode array Substrate 64 Laser diode 65, 66 Emitted light 67 Optical path 68 Reflection mirror 69 Active layer 71 Laser diode 72, 73 Emitted light

Claims (2)

[Claims] 1. A first laser light source for emitting a first laser light polarized in a first direction, and a first laser light source orthogonal to the first laser light source and polarized in the first direction. A second laser light source that emits two laser lights; a polarization beam splitter on which the first laser light and the second laser light are incident; and a polarization beam splitter and the second laser light source. And a rotator that rotates π / 2 so that the plane of polarization of the second laser light is in the second direction, provided from the polarization beam splitter to the first laser light and the second laser light. A laser light source which emits a laser beam in which and are overlapped. 2. A lens or a prism for shaping the elliptical beam shape into a circular beam shape is provided between the beam splitter and the objective lens, and the lens or prism shapes the elliptical beam shape laser light into a substantially circular shape. 2. The laser light source according to claim 1, wherein the laser light is a generated laser light.