JP4119113B2 - Solid state laser equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solid-state laser device that excites a solid-state laser crystal by entering light and resonates the excitation light with an optical resonator to cause laser oscillation.
[0002]
[Prior art]
The solid-state laser device uses, for example, a semiconductor laser as an excitation light source, and the laser beam from this is incident on a solid-state laser crystal such as an Nd: YAG crystal that is a laser medium to excite this, and the excitation light is output to an output side mirror And an optical resonator formed between the crystal and the incident surface mirror to cause laser oscillation and take out the laser light from the output side mirror. These solid-state laser crystal and output side mirror are fixed on a heat sink to stabilize the temperature, and the laser crystal, output side mirror, semiconductor laser, etc., including this heat sink, are housed in a housing, and the emission A laser beam is emitted from the mouth to the outside.
[0003]
Since all the components are housed in the housing in this way, the solid-state laser device can be used as a component of various devices and systems. When incorporating into other devices, the directivity angle of the laser beam is important, and the mounting position and angle of the housing usually need to be performed with extremely high accuracy. As a premise, the tolerance of the laser beam directivity angle with respect to the casing reference plane (one plane of the casing as the reference plane) is required to be extremely strict.
[0004]
[Problems to be solved by the invention]
However, the conventional solid-state laser device has a problem that it is difficult to meet the required accuracy of the laser beam directivity angle. That is, even if the mechanical dimensional accuracy such as the mounting accuracy of each component in the housing is increased, it is difficult to keep the laser beam directivity angle with respect to the housing reference plane within a predetermined tolerance. It is different if an adjustment mechanism for adjusting the laser beam directing angle is provided. However, if this is done, it becomes weak against aging, and long-term stability is lost, and another problem that it cannot be miniaturized also arises.
[0005]
In view of the above, the present invention has a structure that is relatively simple and does not change with time, and can maintain the laser beam directivity angle with respect to the housing reference plane within a certain tolerance without impairing downsizing. An object of the present invention is to provide a solid-state laser device having excellent stability.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the solid-state laser device according to the present invention, optical resonance occurs between a solid-state laser crystal that is excited by incident light and has a mirror formed on the incident surface, and the incident-surface mirror of the laser crystal. An output side mirror that forms a device, an output beam angle correcting plano-concave lens that is disposed on the output side of the output side mirror, one surface is flat and the other surface is concave, and the output beam angle is corrected A holding plate to which the mounting position of the plano-concave lens is adjusted in a direction perpendicular to the laser beam axis so that the flat surface of the plano-concave lens is bonded and fixed, a holding plate for holding the solid laser crystal, and the output side mirror A holding plate and a heat sink, and all the holding plates have an integral block structure, and the block structure and the heat sink are connected to each other. It is a feature.
[0007]
The laser beam emitted from the output side mirror can be bent by the refraction of the plano-concave lens. The refraction angle is determined according to the position of the plano-concave lens, that is, the position in the direction perpendicular to the beam axis, so that the predetermined beam angle can be obtained by adjusting the mounting position of the plano-concave lens in the direction perpendicular to the beam axis. At that point, the flat surface of the plano-concave lens is adhered and fixed to the holding plate. Since a configuration of adding a plano-concave lens and adhering and fixing the flat surface to the holding plate is sufficient, the structure is simple, resistant to secular change, stable over a long period of time, and does not increase in size.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows a solid-state laser device according to an embodiment of the present invention. In FIG. 1, an optical resonator 10 is formed by a solid-state laser crystal 11 and an output side mirror 12. The solid-state laser crystal 11 is made of, for example, an Nd: YAG crystal and is excited by the incidence of laser light. A reflection coat 13 is applied to the incident surface to form a mirror. As the excitation laser light source, for example, a laser diode 15 is used, and the laser light is incident on the solid-state laser crystal 11 through the optical system 16. The output side mirror 12 is made of optical glass or the like, and its surface is polished to a concave surface, and a reflective coating 14 is formed.
[0009]
The solid-state laser crystal 11 is excited by the excitation light, and the generated light is amplified by resonating between the output-side mirror 12 (the reflection coat 14) and the reflection coat (mirror) 13 itself and resonating. As a result, the light intensity increases and laser oscillation occurs. In this example, the fundamental wave light (infrared light) thus amplified is wavelength-converted by the wavelength conversion crystal 18 inserted in the optical resonator 10 to become green or blue light. The reflection coat 14 of the output side mirror 12 has a wavelength characteristic that totally reflects the fundamental wave and transmits visible light (green, blue) whose wavelength has been converted, and passes through the reflection coat 14. Thus, the light after wavelength conversion is emitted.
[0010]
A correction lens 17 is provided on the output side of the output side mirror 12, that is, in the final stage of the solid-state laser device. The correction lens 17 is configured as a plano-concave lens in which one surface is a flat surface and the other surface is a concave surface. When the optical axis of the plano-concave lens and the optical axis of the output laser beam coincide, the laser beam does not refract and goes straight as shown by the solid line in the figure, but both axes are as shown by the dotted line in the figure. If it is deviated, the laser beam will be refracted and bent as shown by the dotted line in the figure. Therefore, the directivity angle of the output laser beam can be corrected by adjusting the position of the correction lens 17 and the position in the direction perpendicular to the laser beam axis.
[0011]
The solid laser crystal 11 is bonded to and held by a holding plate 21, and the output side mirror 12 is bonded to and held by a holding plate 22. The correction lens 17 is also bonded and held on the holding plate 23. These holding plates 21, 22, and 23 are connected to a heat sink (not shown) to control the temperature. The laser crystal 11, the output side mirror 12, the correction lens 17, the laser diode 14, the optical system 16, and the like held on the holding plates 21 to 23 on the heat sink are housed in the housing 30. The housing 30 is provided with an output window (not shown), and a laser beam is emitted from the output window.
[0012]
The solid-state laser device thus configured is used by being incorporated in another device. When it is necessary to strictly determine the direction of the emitted beam, the solid-state laser device uses one surface of the housing 30 as a reference surface 31 so that the laser beam is emitted at an angle determined with respect to the reference surface 31. Keep it. For example, if the surface on the emission side of the housing 30 is the reference surface 31, the light is emitted at an angle of 90 ° with respect to the reference surface 31. If the solid-state laser device is manufactured so that the angle falls within a certain tolerance, the beam direction can be accurately set by mounting the solid-state laser device with reference to the reference plane 31.
[0013]
In order to make the directivity angle of the emitted laser beam fall within a certain tolerance, it is possible to increase the mechanical dimensional accuracy of the holding plates 21 and 22 and the like. It is almost impossible to keep within tolerances. Therefore, when the angle of the outgoing beam with respect to the reference plane 31 is measured in a state where the individual solid-state laser devices are assembled in the housing 30, the angle is deviated from a predetermined angle (in this case, for example, 90 °). Then, the position of the correction lens 17 is adjusted to find a point where the emission angle becomes a desired angle, and the correction lens 17 is bonded and fixed to the holding plate 23 at the point. Thereby, the outgoing beam angle with respect to the reference plane 31 can be kept within a predetermined tolerance.
[0014]
Once the position of the correction lens 17 is determined and bonded and fixed, there are no movable parts, so that the state can be stably maintained for a long time. Thus, the structure is simple, it is resistant to secular change, is stable over a long period of time, and the correction lens 17 is only added and bonded and fixed, so that the size is not increased.
[0015]
Furthermore, the waist position and waist size of the emitted laser beam may be severely restricted depending on the apparatus incorporating this solid-state laser device, but this can be dealt with by adjusting the lens curvature of the correction planoconcave lens 17. It is. That is, by optimizing the optical lens curvature of the correction lens 17, it is possible to satisfy the specifications regarding the waist position and waist size of the emitted laser beam.
[0016]
The above description relates to one embodiment of the present invention, and it is needless to say that the present invention is not limited to the configuration described above. For example, when a fundamental wave is output instead of visible light, the wavelength conversion crystal 18 inserted into the optical resonator 10 is not necessary. Further, the holding plates 21 to 23 and the like can be made to have an integrated block structure to improve the stability of mechanical dimensional accuracy.
[0017]
【The invention's effect】
As described above, according to the solid-state laser device of the present invention, the directivity angle of the emitted laser beam with respect to the housing reference plane falls within a predetermined tolerance, which is a simple addition of a correction plano-concave lens and its fixing. Can be achieved with structure. In addition, since the structure is simple, there is no possibility of increasing the size, and it is stable over a long period without changing over time.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of an embodiment of the present invention.
[Explanation of symbols]
10 Optical resonator 10
DESCRIPTION OF SYMBOLS 11 Solid laser crystal 12 Output side mirrors 13 and 14 Reflection coat 15 Laser diode 16 Optical system 17 Correction lens 18 Wavelength conversion crystal 21 Crystal holding plate 22 Mirror holding plate 23 Correction lens holding plate 30 Housing 31 Reference plane

Claims (1)

A solid-state laser crystal that is excited by incident light and has a mirror formed on the incident surface, an output-side mirror that forms an optical resonator between the incident-surface mirror of the laser crystal, and an output side from the output-side mirror And a plano-concave lens for correcting the outgoing beam angle in which one surface is flat and the other surface is concave, and the mounting position of the plano-concave lens is perpendicular to the laser beam axis so that the outgoing beam angle is corrected. A holding plate to which the flat surface of the plano-concave lens is adjusted and fixed, a holding plate for holding the solid laser crystal, a holding plate for holding the output side mirror, and a heat sink, and all the holding plates Is a solid block structure, and the block structure and a heat sink are connected to each other .

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