JPH08309574A - Laser light source and laser drawing device - Google Patents

Abstract

(57) [Abstract] [Purpose] To generate a laser beam spot with a low directivity. [Configuration] The laser block 1 includes three laser optical systems 6 to
Eight. Condensing lens groups 12 to 14 are housed in the lens barrels 15 to 17, respectively. The laser light generated by each of the semiconductor lasers 9 to 11 corresponds to the condenser lens group 1
2 to 14 focus the light on the irradiation target so that the light is focused and emitted from the emission ends 6a to 8a of the laser optical systems 6 to 8. The laser optical systems 6 to 8 are arranged so as to be inclined by equal angles toward the central axes A of the three optical systems so that the laser beams overlap on the irradiation target. Since the light source is a semiconductor laser, the light spot formed on the irradiation target by the beams from the optical systems 6 to 8 has an elliptical shape. The semiconductor lasers 9 to 11 are arranged so that the long axes of the respective light spots form an angle of 60 degrees with each other.

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, and more particularly to a laser drawing apparatus for drawing an image on an irradiation target with laser light.

[0002]

2. Description of the Related Art A laser drawing apparatus irradiates a recording medium with a beam-shaped laser beam to process or color the recording medium to form an image. This laser drawing apparatus is classified into a system of raster scanning a laser beam and a system of vector scanning a laser beam using a deflector. Conventionally, gas lasers and solid-state lasers have been widely used as laser light sources used in laser drawing devices, but in recent years, with the development of semiconductor lasers, semiconductor lasers of several watts to tens of watts class have come to be used. It's starting. Semiconductor lasers have the great advantages that they are small and inexpensive, and that they are easy to modulate.

However, since the semiconductor laser has a small resonator shape, the coherency of the laser beam and the parallelism of the beam are
Or inferior to other lasers in terms of astigmatism,
Further, there is a drawback that the intensity distribution in the beam cross section orthogonal to the optical axis, that is, the profile has angular anisotropy. The emission pattern of the semiconductor laser is determined by the cross-sectional shape of the laser resonator, and the cross-sectional shape is determined by the width and thickness of the stripe of the active layer forming the laser resonator. In FIG. 5, 101 is a semiconductor laser chip, 1
Reference numeral 02 is an active layer, and 103 is a high-gain stripe. The stripe 103 is extremely small, and the laser light is radiated in a wider spread than the stripe 103. The stripe 103 is not only small in size but also highly asymmetric. That is, the ratio between the width and the thickness of the stripe 103 is usually about 3: 1. Since the radiation of the laser beam is affected by the refractive index of the waveguide, the laser beam is emitted in the stripe 103 in the width direction of the stripe 103.
In the thickness direction of the stripe 103, the light is diffused and emitted from the entire width of the stripe 103 in the X direction. As a result, in the region close to the stripe 103, the shape of the beam cross section orthogonal to the optical axis becomes an ellipse long in the X direction, while in the region far from the stripe 103, the shape of the beam cross section becomes an ellipse long in the Y direction. Become. Therefore, the laser beam emitted from the stripe 103 travels in a shape like an elliptical cone 104.

As a result, as shown in FIG. 6, when such a diffused beam is converged through a condensing optical system and irradiated onto an irradiation target, a light spot 100 generated at that time is generated.
Also becomes elliptical and directional. As shown in FIG. 6A, when the laser beam is raster-scanned, the moving direction of the light spot 100 is constant, so that the light spot 100 having an elliptical shape does not have an adverse effect. Rather, when the width in the sub-scanning direction RS is narrower than the width in the main-scanning direction RM as shown in the figure, the energy efficiency is improved, which is preferable to the circular shape.

On the other hand, when performing vector scanning, since the light spot 100 moves in all directions on the irradiation surface,
When the light spot 100 has directionality and is not correctly circular, the width of the irradiation area varies depending on the moving direction of the light spot 100. For example, as shown in FIG. 6B, when the vertically long light spot 100 is moved horizontally in the drawing, the width of the irradiation region is as wide as a, while when it is moved vertically, the irradiation region is wide. Has a width b that is narrower than a.
If the width of the irradiation area, and thus the width of the drawn line, differs depending on the moving direction of the light spot 100, the quality of the formed image deteriorates.

[0006]

Therefore, when a semiconductor laser is used as a light source for vector scanning of a laser beam, it is necessary to shape the cross-sectional shape of the beam by an optical system. FIG. 7 shows an example of a conventional optical system for performing such beam shaping, which is used, for example, in a CD player. The laser light emitted from the semiconductor laser 110 is collimated by a collimator 111 and then shaped by an anamorphic prism pair 112 so that the beam has a circular cross-sectional shape. The laser beam is then made into diffuse light by the beam expander 113,
Then, it is converged by the focus lens 114 to form a spot on an irradiation target (not shown). Although an optical spot close to a perfect circle can be obtained by such an optical system, the insertion loss of the prism pair 112 is as large as 50 to 80%, and it is difficult to extract a large power. Further, for example, in a laser printer or the like, beam shaping is performed using an optical system as shown in FIG. In this optical system, a cylindrical lens (cylindrical lens) 115 is used instead of the prism pair, and the beam width in a specific direction is reduced or expanded to match the beam width in other directions. However, it is necessary to use a precise lens in order to make the shape of the obtained light spot close to a perfect circle, which increases the cost. As described above, it is extremely difficult to perform beam shaping by the conventionally used conventional optical system without lowering the laser light intensity, that is, with low loss and at low cost. Therefore, an object of the present invention is to provide a laser light source that generates a light spot having a shape with low directivity and a laser drawing apparatus using the laser light source.

[0007]

To achieve the above object, the present invention provides a laser light source for irradiating a predetermined irradiation target with laser light, and emits laser light to generate light spots on the irradiation target. Equipped with multiple laser light sources,
The light spot has a wide width in a specific direction, the light spots overlap each other on the irradiation target, and the plurality of laser light sources are arranged so that the specific directions of the light spots generated by them do not match. It is characterized by being Further, in order to achieve the above object, the present invention provides a single laser light source for generating a laser beam having a wide width in a specific direction in a laser light source for irradiating a predetermined irradiation target with laser light, and this laser light source A beam splitter that splits the laser beam to generate a plurality of laser beams, and the plurality of laser beams generated by the beam splitter are respectively reflected so that the plurality of laser beams are the same on the irradiation target. A plurality of reflecting mirrors to be incident on the position of, and on the optical path of the plurality of laser beams, is arranged before or after the plurality of reflecting mirrors, each of the plurality of laser beams is optically processed, each laser And an optical system in which the directions of the maximum width of the beams are different from each other.

In order to achieve the above object, the present invention also provides:
In a laser drawing apparatus that irradiates a predetermined irradiation target with laser light and deflects the laser light by an optical deflector to form an image on the irradiation target, the laser light source is provided, and the optical deflector is the laser It is characterized in that the laser light emitted from the light source is deflected.

[0009]

In the laser light source of the present invention, the laser light emitted from each of the plurality of laser light sources produces a light spot having a wide width in a specific direction on the irradiation target while overlapping each other. Then, since each laser light source is appropriately arranged and the specific directions of the respective light spots do not coincide with each other, a combined light spot formed by overlapping a plurality of light spots is more than an individual light spot. The directionality of the shape is relaxed. In another laser light source of the present invention, the beam splitter splits a wide laser beam generated in a specific direction by a single laser light source to generate a plurality of laser beams.
These laser beams are reflected by a reflecting mirror so as to be incident on the same position on the irradiation target, but each laser beam is reflected by an optical system arranged before or after the reflecting mirror before entering the irradiation target. Are optically processed such that the directions of the maximum width of the are different from each other. Therefore, the directions of the light spots formed on the irradiation target by the respective beams are different from each other, and the shape of the synthetic light spot has a relaxed directional property.

Further, the laser drawing apparatus of the present invention is constructed by using the laser light source of the present invention which produces a light spot of which the directionality is relaxed, and the laser light from the laser light source is deflected by the deflector. Therefore, an image can be formed by scanning a light spot having low directivity on the irradiation target.

[0011]

EXAMPLES Next, examples of the present invention will be described. FIG.
FIG. 3 is a schematic plan view showing an example of a laser drawing apparatus of the present invention, which is configured by using an example of the laser light source of the present invention. This laser drawing apparatus 21 is provided with a laser block 1 which is a laser light source of the present invention, and this laser is provided with a plurality of semiconductor lasers and a plurality of focusing optical systems, as will be described later in detail.

Reference numeral 3 is a folding mirror in which a dielectric multilayer film is coated on the surface of a glass substrate, and the laser beam 2 from the laser block 1 is bent at a right angle on a horizontal plane. The deflection mirrors 4 and 5 constitute a beam deflector for moving a light spot two-dimensionally on a recording medium (not shown) arranged below the deflection mirror 5. Each mirror 4 and 5 is a plane mirror and its deflection actuator (not shown).
And the laser beam 2 from the folding mirror 3 is
First, it is incident on the deflecting mirror 4, and when the mirror 4 is oriented in the neutral direction, the laser beam 2 is bent 90 degrees on the horizontal plane and is incident on the deflecting mirror 5. Then, the mirror 4 swings about the vertical axis by the actuator, the incident position of the laser beam 2 on the deflection mirror 5 changes, and the light spot moves in the X direction on the recording medium. The laser beam 2 incident on the deflecting mirror 5 is bent vertically downward when the mirror 5 is oriented in the neutral direction, and is incident on the recording medium. Then, the mirror 5 swings about the horizontal axis by the actuator,
The laser beam 2 is deflected in the Y direction, the incident position on the recording medium changes, and the light spot moves in the Y direction on the recording medium. The condensing optical system that constitutes the laser block 1 is configured to focus the laser beam 2 on the recording medium after the laser beam 2 is reflected by these mirrors 3 to 5.

Next, the laser block 1 will be described in detail with reference to FIG. 1A is a front view thereof,
(B) is a side view. This laser block 1 has three laser optical systems 6 to 8, which are arranged so that the emission ends 6a to 8a of the laser beam are directed in substantially the same direction and form the vertices of an equilateral triangle. Each of the laser optical systems 6 to 8 has a cylindrical shape, and includes lens barrels 15 to 17 in which semiconductor lasers 9 to 11 are housed at their bottoms, respectively. In each of the lens barrels 15 to 17, there are housed condensing lens groups 12 to 14 each including a general collimator lens, a beam expander lens, and a focusing lens (not shown). . The laser beams generated by the semiconductor lasers 9 to 11 are condensed by the corresponding condenser lens groups 12 to 14 so as to be focused on the recording medium, and emitted by the laser optical systems 6 to 8, respectively. The light is emitted from the ends 6a to 8a.

As shown in FIG. 1B, the laser optical systems 6 to 8 are arranged so as to be inclined at equal angles toward the central axes A of the three optical systems. This tilt angle is set to such an angle that the light spots on the recording medium generated by the laser beams emitted from the optical systems 6 to 8 overlap on the recording medium.

Each laser optical system 6-8 is a semiconductor laser 9-.
Since 11 is used as the light source, the light spot generated on the recording medium by the beams from the optical systems 6 to 8 has a directionality in its shape and is elliptical. The semiconductor lasers 9 to 11, and therefore the optical systems 6 to 8 are arranged so that the major axes of the elliptical light spots form an angle of 60 degrees with each other.

With this structure, the following light spots are formed on the recording medium. That is, the laser beams emitted from the laser optical systems 6 to 8 of the laser block 1 are bent by the mirrors 3 to 5 and enter the recording medium arranged below the mirror 5. The respective laser beams are focused on the recording medium by the condenser lens groups 12 to 14, respectively, and as a result, three light spots 18 to 20 are generated on the recording medium as shown in FIG. Since the light sources of the optical systems 6 to 8 are the semiconductor lasers 9 to 11, all of these spots are elliptical. And since each optical system 6-8 is arrange | positioned as mentioned above, the center of each spot 18-20 corresponds, and each spot 18- is.
The major axes of 20 form an angle of 60 degrees with each other.

Therefore, as can be seen from FIG. 4, the direction of the combined light spot is relaxed, and the width a of the line drawn when the combined light spot is moved laterally in the drawing is , The width b of the line drawn when vertically moved,
The widths c and d of the lines drawn when they are moved diagonally at 45 degrees are substantially the same. Therefore, when the laser beam 2 is deflected by the deflecting mirrors 4 and 5 for vector scanning and the composite light spot having low directivity is moved and drawn on the recording medium, the line width is changed depending on the moving direction of the light spot. Does not change so that the image quality does not deteriorate.

In this embodiment, the number of semiconductor lasers is three, but as the number increases, the shape of the combined light spot approaches a perfect circle and the directionality decreases, resulting in a good drawing result. Is obtained. However, in that case, since the cost increases, the number of laser light sources is determined in consideration of the required performance and the cost. In the case of an ordinary laser drawing apparatus, it is sufficient to set the number of laser light sources to three.

Next, another example of the laser light source according to the present invention will be described with reference to FIG. This laser light source 40
In the method, a laser beam generated by one light source is divided into three laser beams, which are then converged at one point to combine light spots and the directionality of the spots is relaxed.
That is, the laser light generated by the semiconductor laser 22 is first made into parallel light by the collimator 23, and then the three laser beams 3 having the same power are made by the beam splitter 24.
It is divided into 2, 33 and 34. This beam splitter 22
Is a diffraction grating that can also perform beam profile shaping, and is specifically configured by a beam splitter coated with a dielectric multilayer film that reflects a part of light, or a cube beam splitter. Since the light source is a semiconductor laser, the sectional shape of the laser beam incident on the beam splitter 24 is elliptical as described above, and the width in the specific direction is wide. Therefore, the laser beams 32-34
The cross sectional shapes of are also elliptical, and their major axis directions are coincident.

The three beams 32 to 34 emitted from the beam splitter 24 are reflected by the reflecting mirrors 25, 26 and 27, respectively, and their directions are changed so as to form a light spot at the same position on the irradiation target 31. To be Beam shaping lenses 28, 29, and 30 are arranged on the irradiation target sides of the reflecting mirrors 25 to 27, respectively. These lenses are specially designed aspherical lenses, which have a condensing function and a beam shaping function. The laser beams 32 to 34 reflected by the reflecting mirrors 25 to 27 are irradiated by the irradiation target 31 by these lenses.
The light is focused so that it is focused on the top and is optically processed so that the directions of the major axes of the beam cross-sectional shapes form an angle of 60 degrees with each other. Therefore, the synthetic light spot formed on the irradiation target 31 has a reduced directional property similarly to the synthetic light spot shown in FIG. This laser light source requires only one light-emitting body such as a semiconductor laser unlike the one shown in FIG. 1, and further requires only one driver and its associated optical system such as a collimator. Therefore, it is advantageous in terms of cost reduction. If the beam splitter is a diffraction grating as in this example, it can be mass-produced and can be manufactured at low cost.

When such a laser light source is used in place of the laser block 1 of the laser drawing apparatus shown in FIG. 3, the line width almost changes depending on the moving direction of the light spot, as in the above case. Therefore, the image quality does not deteriorate.

Although the light source is the semiconductor laser in the above embodiment, the light source is not limited to the semiconductor laser, and any laser light source that cannot obtain a light spot having no directivity by itself can be used.
The present invention is effective for any type of light source. Further, in the embodiment shown in FIG. 2, the laser beam is divided into three by the beam splitter, but even if the laser beam is divided into two or four or more, a light spot whose directionality is eased can be similarly obtained. . Of course, the more beams are divided, the closer the light spot becomes to a perfect circle.

Conventionally, there has been a laser drawing apparatus which uses a plurality of laser light sources or divides a laser beam by a single light source by a beam splitter to form a multi-beam, but in any case, a plurality of lines are used. Are simultaneously drawn to improve the recording speed, and the object and structure thereof are completely different from those of the present invention.

[0024]

As described above, in the laser light source of the present invention, the laser beams emitted from each of the plurality of laser light sources generate light spots having a wide width in a specific direction on the irradiation target while overlapping each other. Then, since each laser light source is appropriately arranged and the specific directions of the respective light spots do not coincide with each other, a combined light spot formed by overlapping a plurality of light spots is more than an individual light spot. The directionality of the shape is relaxed. In another laser light source of the present invention, the beam splitter splits a laser beam generated by a single laser light source and having a wide width in a specific direction to generate a plurality of laser beams. These laser beams are reflected by a reflecting mirror so as to be incident on the same position on the irradiation target, but each laser beam is reflected by an optical system arranged before or after the reflecting mirror before entering the irradiation target. Are optically processed such that the directions of the maximum width of the are different from each other. Therefore, the directions of the light spots formed on the irradiation target by the respective beams are different from each other, and the shape of the synthetic light spot has a relaxed directional property. Therefore, according to the present invention, it is possible to realize a laser light source that forms a light spot having a weak directivity by using a light source that forms a light spot having a strong directivity such as a semiconductor laser. The semiconductor laser has the advantages of being small in size, low in price, and easy to modulate,
The fact that a light spot having a weak directivity can be formed even by using a semiconductor laser leads to expansion of the application range of the semiconductor laser and is extremely significant.

Further, the laser drawing apparatus of the present invention is constructed by using the laser light source of the present invention which produces a light spot of which the directionality is relaxed, and the laser light from the laser light source is deflected by the deflector. Therefore, an image can be formed by scanning a light spot having low directivity on the irradiation target. As a result, even when the laser beam is vector-scanned to draw on the recording medium, the image quality is not deteriorated.

[Brief description of drawings]

1A is a front view showing an example of a laser light source according to the present invention, and FIG. 1B is a side view.

FIG. 2 is a side view showing another example of the laser light source according to the present invention.

3 is a schematic plan view showing an example of a laser drawing apparatus according to the present invention using the laser light source of FIG.

FIG. 4 is an explanatory diagram showing a light spot generated by the laser light source of FIG.

FIG. 5 is an explanatory diagram showing generation of a laser beam by a semiconductor laser.

FIG. 6 is an explanatory diagram showing an influence when the shape of the light spot has directionality.

FIG. 7 is a configuration diagram showing a conventional beam shaping optical system.

FIG. 8 is a configuration diagram showing another conventional beam shaping optical system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 laser block 2 laser beam 3 folding mirror 4, 5 deflection mirror 6, 7, 8 laser optical system 6a-8a emission end 9, 10, 11, 22 semiconductor laser 12, 13, 14 condensing lens group 15, 16, 17 Lens barrel 18, 19, 20, 100 Light spot 21 Laser drawing device 23 Collimator 24 Beam splitter 25, 26, 27 Reflector 28, 29, 30 Beam shaping lens 31 Irradiation target 101 Laser chip 102 Active layer 103 Stripe

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H01S 3/101 H01S 3/18 3/18 B41J 3/00 D

Claims (17)

[Claims] 1. A laser light source for irradiating a predetermined irradiation target with laser light, comprising: a plurality of laser light sources that emit laser light to generate light spots on the irradiation target, respectively. A width in a direction is wide, the light spots overlap each other on the irradiation target, and the plurality of laser light sources are arranged so that the specific directions of the light spots generated by the respective laser light sources do not match. Laser light source. 2. The plurality of laser light sources are arranged such that adjacent ones of the light spots in the specific direction form an equal angle with each other.
The laser light source described. 3. The laser light source according to claim 1, wherein the number of the plurality of laser light sources is three. 4. The laser light source according to claim 3, wherein the plurality of laser light sources are arranged so that each of the specific directions of the light spots forms an angle of 60 degrees with each other. 5. The laser light source according to claim 1, wherein the plurality of laser light sources include a semiconductor laser. 6. A laser light source for irradiating a predetermined irradiation object with laser light, wherein a single laser light source for generating a laser beam having a wide width in a specific direction and the laser beam generated by this laser light source are divided. A plurality of beam splitters that generate a plurality of laser beams, and a plurality of laser beams that are generated by the beam splitters are reflected to cause the plurality of laser beams to enter the same position on the irradiation target. Reflecting mirrors, on the optical path of the plurality of laser beams, arranged in front of or after the plurality of reflecting mirrors, optically processing each of the plurality of laser beams to determine the direction of the maximum width of each laser beam. A laser light source comprising: an optical system that is different from each other. 7. The optical system optically processes the laser beams such that the directions of the maximum width of each of the plurality of laser beams are adjacent to each other at an equal angle. 6. The laser light source according to 6. 8. The laser light source according to claim 6, wherein the beam splitter generates three laser beams. 9. The laser light source according to claim 8, wherein the optical system optically processes the three laser beams so that the directions of the respective maximum widths form an angle of 60 degrees with each other. 10. The laser light source according to claim 6, wherein the single laser light source includes a semiconductor laser. 11. The laser light source according to claim 6, wherein the beam splitter is configured by using a beam splitter coated with a dielectric multilayer film or a cube beam splitter. 12. The laser light source according to claim 6, wherein the optical system is composed of an aspherical lens. 13. The laser light source according to claim 12, wherein the aspherical lens has a condensing function. 14. Irradiating a predetermined irradiation target with laser light,
A laser drawing apparatus for forming an image on the irradiation target by deflecting the laser light with an optical deflector, comprising the laser light source according to any one of claims 1 to 13, wherein the optical deflector comprises: A laser drawing apparatus which deflects laser light emitted from a laser light source. 15. The laser drawing apparatus according to claim 14, wherein the laser beam is vector-scanned by the optical deflector. 16. The laser drawing apparatus according to claim 14, wherein the irradiation target is processed by the laser light. 17. The laser drawing apparatus according to claim 14, wherein the irradiation target is colored by the laser light.