JP2007072134A - Wavelength conversion laser device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wavelength conversion laser device that is superior in wavelength conversion efficiency and the variance of wavelength conversion efficiency to changes in the fundamental beam of which is small. <P>SOLUTION: The wavelength conversion laser device, which makes a fundamental laser beam travel in one direction and performs wavelength conversion of the fundamental laser beam by non-linear effects, comprises a fundamental wave laser beam source for generating the fundamental laser beam, a wavelength conversion element which is disposed on the optical axis of the fundamental laser beam outputted from the laser beam source, and performs wavelength conversion of the fundamental laser beam by non-linear effects, a plurality of light-collecting means which are disposed between the fundamental laser beam source on the optical axis of the fundamental laser beam and the wavelength conversion element, in such a manner that they can move reciprocatively on the optical axis of the fundamental laser beam for collecting the fundamental laser beam for the wavelength conversion element, and a moving means for moving the light-collecting means in the direction of the optical axis of the fundamental laser beam. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wavelength conversion laser device, and more particularly to a wavelength conversion laser device provided with a nonlinear optical crystal.

  Conventionally, as a wavelength conversion device, a fundamental laser beam is generated from a fundamental laser beam light source, and the fundamental laser beam is condensed on the wavelength conversion element by a condensing element. Wavelength laser beam wavelength conversion is performed. Moreover, in the conventional wavelength converter, the single lens was used with respect to one wavelength conversion crystal as a condensing element (for example, refer patent document 1).

Japanese Examined Patent Publication No. 7-58378 (pages 5-6, Fig. 1)

  However, the conventional wavelength conversion laser device has a problem that the wavelength conversion efficiency changes greatly due to variations in the curvature and beam diameter of the emitted laser beam of the fundamental light source laser device. In addition, when sum frequency generation or difference frequency generation is performed by collecting beams with different wavelengths, sufficient conversion efficiency cannot be obtained, wavelength conversion efficiency varies greatly depending on the change of the fundamental beam, There was a problem. In addition, there is a problem that manufacturing is difficult because high arrangement accuracy is required for a condensing element that condenses laser beams having a plurality of wavelengths in the vicinity of the wavelength conversion crystal.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a wavelength conversion laser device excellent in wavelength conversion efficiency with a small variation in wavelength conversion efficiency with respect to changes in the fundamental wave beam. . Another object of the present invention is to obtain a wavelength conversion laser device excellent in wavelength conversion efficiency that can obtain sufficient conversion efficiency even when beams having different wavelengths are collected to generate sum frequency or difference frequency. And It is another object of the present invention to obtain a wavelength conversion laser device that is easy to manufacture and has a gentle arrangement accuracy of light converging elements.

  In order to solve the above-described problems and achieve the object, a wavelength conversion laser device according to the present invention is a wavelength conversion device that advances a fundamental laser beam in one direction and performs wavelength conversion of the fundamental laser beam by a nonlinear effect. A laser device that is arranged on the optical axis of a fundamental laser beam source that generates a fundamental laser beam and a fundamental laser beam emitted from the laser beam light source, and converts the wavelength of the fundamental laser beam by a non-linear effect. The wavelength conversion element is provided between the fundamental wave laser beam light source and the wavelength conversion element on the optical axis of the fundamental laser beam so as to be capable of reciprocating on the optical axis of the fundamental laser beam. A plurality of condensing means for condensing the fundamental laser beam and a moving means for moving the condensing means in the optical axis direction of the fundamental laser beam. And wherein the Rukoto.

  According to this invention, a plurality of condensing means are used as the condensing means for condensing on the wavelength conversion element. Further, a plurality of lenses are provided with moving means in the optical axis direction. As a result, even when the beam diameter at the waist position of the fundamental wave laser beam changes due to a change in the laser parameters of the fundamental wave light source, by moving the plurality of lenses in the direction of the optical axis, The effect is that the beam diameter can be easily changed without greatly changing the position, and the fluctuation of the beam waist near the wavelength conversion crystal position can be compensated for the fluctuation of the fundamental laser beam. Play.

  Therefore, according to the present invention, it is possible to realize a wavelength conversion laser device in which fluctuations in wavelength conversion efficiency are small with respect to changes in the fundamental wave beam. In addition, even when the beam diameter of the waist position of the fundamental wave laser beam changes due to a change in the laser parameters of the fundamental wave light source, the adjustment time for correcting this and the labor required for the adjustment can be reduced. There is an effect that it is possible to realize a wavelength conversion laser device with excellent operability that can be easily adjusted by a user other than those skilled in the wavelength conversion laser device.

  Embodiments of a wavelength conversion laser device according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably.

Embodiment 1 FIG.
FIG. 1-1 is a configuration diagram illustrating a main configuration of the wavelength conversion laser device according to the first embodiment of the present invention. As illustrated in FIG. 1A, the wavelength conversion laser device according to the present embodiment includes a fundamental wave light source 1, a first condenser lens 2, a second condenser lens 3, and a wavelength conversion crystal 4. Condensing lens moving means 52 and 53, and a data holding unit 54.

  The fundamental wave light source 1 is fundamental wave laser beam generating means for generating a fundamental wave laser beam. The first condensing lens 2 is a condensing unit that condenses the fundamental laser beam generated from the fundamental light source 1, and the optical axis direction of the fundamental laser beam is on the optical axis of the fundamental laser beam. Are provided so that they can reciprocate within a certain range. The second condensing lens 3 is condensing means for condensing the fundamental laser beam generated from the fundamental light source 1 and condensed by the first condenser lens 2, and the light of the fundamental laser beam. On the axis, a reciprocating motion is provided in a certain range in the optical axis direction of the fundamental laser beam.

  The wavelength conversion crystal 4 is a wavelength conversion element that converts the wavelength of the fundamental laser beam, and a part of the fundamental laser beam condensed by the second condenser lens 3 is ½ of the fundamental laser beam. It consists of a wavelength conversion crystal (nonlinear optical crystal) for generating a second harmonic to be converted into a laser beam having a wavelength, and is disposed on the optical axis of the fundamental laser beam. The condensing lens moving means 52 and 53 are moving means for moving the condensing means in the optical axis direction of the fundamental wave laser beam, and the first condensing lens 2 and the second condensing lens 3, respectively, The fundamental wave laser beam generated from the fundamental wave light source 1 is moved in the optical axis direction. The data holding unit 54 is means for holding correction data to be referred to when the condenser lens moving means 52 and 53 move the first condenser lens 2 and the second condenser lens 3, respectively.

  Further, in the wavelength conversion laser device according to the present embodiment, the fundamental wave so that the outer edge 1a of the fundamental wave laser beam does not protrude from the outer diameter of the first condenser lens 2 as shown in FIG. A fundamental laser beam is emitted from the light source 1 in the direction of arrow A. The beam waist (condensation point) position 6 of the fundamental laser beam is the position of the dotted line B in FIG. 1-1, and the beam waist (condensation point) existing in the vicinity of the wavelength conversion crystal 4 or inside the wavelength conversion crystal 4. The position 7 is the position of the dotted line C in FIG.

  In the wavelength conversion laser device according to the present embodiment, the fundamental laser beam generated from the fundamental light source 1 is generated by the first condenser lens 2 and the second condenser lens 3 as shown in FIG. Due to the action, the condensing point is formed in the wavelength conversion crystal 4 or in the vicinity of the wavelength conversion crystal 4.

  Next, the operation of the wavelength conversion laser device according to this embodiment configured as described above will be described. As shown in FIG. 1-1, the fundamental laser beam generated from the fundamental light source 1 is the same as the fundamental laser beam generated from the fundamental light source 1 generated on the optical axis of the fundamental laser beam 1. The light is condensed by a first condenser lens disposed in the area. Next, the fundamental wave laser beam condensed by the first condenser lens is condensed by the second condenser lens 3 disposed on the optical axis of the fundamental laser beam. The fundamental laser beam condensed by the second condenser lens 3 is condensed so as to have a condensing point inside the wavelength conversion crystal 4 or in the vicinity of the wavelength conversion crystal 4. A part of the fundamental wave laser beam condensed by the second condenser lens 3 is converted by the wavelength conversion crystal 4 into a laser beam having a wavelength half that of the fundamental wave laser beam.

  Here, in the wavelength conversion laser device according to the present embodiment, the focal lengths of the first condenser lens 2 and the second condenser lens 3 and the beam waist (condensing point) position 6 of the fundamental laser beam are used. Consider the distance to the beam waist (condensing point) position 7 near or inside the wavelength conversion crystal 4, the beam waist diameter at the beam waist (condensing point) position 6 of the fundamental laser beam, etc. Then, the relationship between the positions of the first condenser lens 2 and the second condenser lens 3 and the beam diameter of the condensing point 7 is calculated in advance and collected as a correction data in a table. Are held in the data holding unit 54. Then, the positions of the first condenser lens 2 and the second condenser lens 3 are moved by the condenser lens moving means 52, 53 according to the correction data held in the data holding section 54, thereby Only the beam waist diameter can be continuously changed without changing the beam waist position from the beam waist (condensing point) position 7 as shown in 1-2.

  The first condenser lens 2 and the second condenser lens 3 are provided with fine adjustment means capable of fine adjustment in the vertical and horizontal directions in the direction perpendicular to the optical axis, and position fixing means. Regardless of where the first condenser lens 2 and the second condenser lens 3 are moved on the optical axis, the laser beam that has passed through the first condenser lens 2 and the second condenser lens 3 The configuration is such that the change of the optical axis can be suppressed to such an extent that no practical problem occurs.

  As described above, the wavelength conversion laser device according to the present embodiment uses a plurality of lenses as a condensing element that focuses light on the wavelength conversion element. Further, a plurality of lenses are provided with moving means in the optical axis direction. As a result, even when the beam diameter at the waist position of the fundamental wave laser beam changes due to a change in the laser parameters of the fundamental wave light source, by moving the plurality of lenses in the direction of the optical axis, It is possible to easily change the beam diameter without greatly changing the position. That is, the fluctuation of the beam waist near the wavelength conversion crystal position can be compensated for the fluctuation of the fundamental laser beam.

  Further, the wavelength conversion laser device according to the present embodiment holds, as data, the lens position at which the condensing diameter (beam waist diameter) changes without changing the beam waist (condensing point) position. The lens position can be adjusted accordingly. As a result, even if the beam diameter at the waist position of the fundamental wave laser beam changes due to a change in the laser parameter of the fundamental wave light source, the beam diameter can be easily adjusted without changing the position of the focal point according to the correction data prepared in advance. It is possible to change.

  Therefore, according to the wavelength conversion laser device according to the present embodiment, it is possible to realize a wavelength conversion laser device in which fluctuations in wavelength conversion efficiency are small with respect to changes in the fundamental beam. In addition, even when the beam diameter of the waist position of the fundamental wave laser beam changes due to a change in the laser parameters of the fundamental wave light source, the adjustment time for correcting this and the labor required for the adjustment can be reduced. It is possible to realize a wavelength conversion laser device with excellent operability that can be easily adjusted by a user other than those skilled in the wavelength conversion laser device.

  2 and 3 show specific calculation results for the wavelength conversion laser device according to the first embodiment having the above-described configuration. The calculation results of FIGS. 2 and 3 will be described in detail below. The focal lengths of the first condenser lens 2 and the second condenser lens 3 are f = 250 mm and f = 400 mm, respectively, the distance from the position 6 to the position 7 is 800 mm, and the beam at the position 6 The diameter was calculated as 240 μm (radius).

  In FIG. 2, the horizontal axis is the beam diameter (radius) at position 7, and the plot is made when the beam diameter (radius) at position 7 is changed from 70 μm to 170 μm. The vertical axis is the distance from the position 6 to the first condenser lens 2. Also, in FIG. 3, the horizontal axis is the beam diameter (radius) at position 7 and the beam diameter (radius) at position 7 is changed from 70 μm to 170 μm, from position 6 to the second condenser lens 3. The distance is plotted. The vertical axis represents the distance between the first condenser lens 2 and the second condenser lens 3. By moving the condensing lenses 3 and 4 according to FIGS. 2 and 3, the beam diameter at the position 7 can be easily changed without changing the condensing point position.

  Further, even when the beam waist (focusing point) position 6 of the fundamental laser beam is deviated from the initial position indicated by the dotted line B in FIG. 1-1 for some reason, the distance from the position 6 to the position 7 is changed. It is possible to cope with this by preparing a plurality of correction data and using different correction data corresponding to the current situation.

  In the present embodiment as described above, for example, when the generation source of the fundamental wave laser beam is a solid-state laser oscillator and the thermal lens of the laser active medium varies, the beam conversion at the wavelength conversion crystal position is suppressed, and the wavelength conversion is performed. This is effective in suppressing fluctuations in beam parameters and the like. That is, a high-quality wavelength conversion laser device that is not greatly affected by the thermal strain of the solid-state laser crystal can be configured.

  In addition, the fundamental laser beam source as described above includes not only a solid-state laser oscillator but also an amplifier, etc., and when the thermal lens of the laser active medium or thermal distortion varies, the beam fluctuation of the wavelength conversion crystal position is suppressed. It is effective in suppressing fluctuations in the wavelength conversion beam parameter. That is, it is possible to construct a high-quality wavelength conversion laser device that is not greatly affected by the thermal strain of the solid-state laser crystal in the amplifier.

  In the above description, the configuration using two condensing lenses has been described. However, the present invention is not limited to this, and a similar apparatus is configured using three or more condensing lenses. Even in this case, the same effects of the present invention as described above can be obtained. In this case, the condensing lens can be moved so that the position 7 becomes the transfer point of the position 6. With such a configuration, two points of a fundamental wave laser beam passing point and a beam waist in the vicinity of the wavelength conversion crystal position without greatly changing the beam waist position with respect to the fluctuation of the fundamental laser beam, While maintaining the transfer relationship, fluctuations in the beam waist diameter in the vicinity of the wavelength conversion crystal position can be compensated.

Embodiment 2. FIG.
FIG. 4 is a configuration diagram showing the main configuration of the wavelength conversion laser device according to the second embodiment of the present invention. FIG. 5 is a diagram schematically showing a laser beam when the beam waist of the fundamental laser beam is set thick. As shown in FIGS. 4 and 5, the wavelength conversion laser device according to the present embodiment includes a fundamental light source 1, a condenser lens 8, a wavelength conversion crystal 9, an achromatic lens 10, and a sum frequency. A (difference frequency) generating wavelength conversion crystal 11 and a beam splitter mirror 12 are provided.

  The fundamental wave light source 1 is fundamental wave laser beam generating means for generating a fundamental wave laser beam. The condensing lens 8 is a condensing lens that condenses the fundamental laser beam 13 emitted from the fundamental light source 1 in or near the wavelength conversion crystal 9 and is disposed on the optical axis of the fundamental laser beam. Is done. The wavelength conversion crystal 9 is wavelength conversion means for generating a wavelength conversion laser beam 14 by performing wavelength conversion of the fundamental wave laser beam 13, and is disposed on the optical axis of the fundamental wave laser beam 13.

  The achromatic lens 10 reduces the chromatic aberration of the fundamental laser beam 13 and the wavelength conversion laser beam 14 in the vicinity of or inside the wavelength conversion crystal 11 for generating the sum frequency (difference frequency), and the focal length of these laser beams. Are arranged on the optical axis of the fundamental laser beam. The sum frequency (difference frequency) generating wavelength conversion crystal 11 is composed of a wavelength conversion crystal (nonlinear optical crystal) for generating the sum frequency or difference frequency, and is disposed on the optical axis of the fundamental laser beam. A sum frequency (difference frequency) laser beam 15 is generated from the beam 13 and the wavelength converted laser beam 14. The beam splitter mirror 12 is coated so as to exhibit high transmittance with respect to the sum frequency (difference frequency) laser beam and high reflectance with respect to the fundamental laser beam and the wavelength change laser beam. The sum frequency (difference frequency) laser beam is separated from the fundamental laser beam and the wavelength changing laser beam.

  Next, the operation of the wavelength conversion laser device according to this embodiment configured as described above will be described. As shown in FIGS. 4 and 5, the fundamental laser beam 13 generated from the fundamental wave light source 1 is generated by the wavelength conversion crystal 9 by the action of the condenser lens 8 disposed on the optical axis of the fundamental laser beam 13. It is collected in the vicinity or inside. For example, the light is condensed at the position of the solid line 18 in FIG. In the wavelength conversion laser device according to the present embodiment, the fundamental wave light source is arranged so that the outer edge portion 16a of the fundamental wave laser beam 13 does not protrude from the outer diameter of the first condenser lens 2 as shown in FIG. A fundamental laser beam is emitted from 1 in the direction of arrow A.

  Here, the wavelength conversion crystal 9 has means for phase matching such as temperature adjustment means and angle adjustment means, and a part of the fundamental wave laser beam 13 is converted by the wavelength conversion crystal 9 into the wavelength conversion laser beam 14. Is converted to In the wavelength conversion laser device according to the present embodiment, the fundamental wave light source is arranged so that the outer edge portion 16a of the fundamental wave laser beam 13 does not protrude from the outer diameter of the first condenser lens 2 as shown in FIG. A fundamental laser beam is emitted from 1. Further, the outer edge portion 14 a of the wavelength conversion laser beam 14 exists inside the outer edge portion 16 a of the fundamental wave laser beam 13.

  Then, the wavelength conversion laser beam 14 and a part of the fundamental laser beam 13 remaining without being wavelength-converted in the wavelength conversion crystal 9 are incident on the achromatic lens 10, and by the action of the achromatic lens 10, For example, the light is condensed at a position indicated by a solid line 19 in FIG. A part of the laser beam is converted into a sum frequency (difference frequency) laser beam 15.

  Next, the wavelength conversion laser beam 14, the fundamental wave laser beam 13, and the sum frequency (difference frequency) laser beam 15 are incident on the beam splitter mirror 12, and the sum frequency (difference frequency) is caused by the action of the beam splitter mirror 12. Only the laser beam 15 is separated from the fundamental laser beam 13 and the wavelength conversion laser beam 14 and extracted.

  In the wavelength conversion laser device according to the present embodiment as described above, means for eliminating the difference in focal length depending on the wavelength is used as means for condensing the fundamental laser beam 13 and the wavelength conversion laser beam 14. Yes. That is, as a means for condensing the fundamental wave laser beam 13 and the wavelength conversion laser beam 14, the chromatic aberration of the fundamental wave laser beam 13 and the wavelength conversion laser beam 14 is reduced, and the focal lengths of these laser beams become substantially equal. An achromatic condenser lens that works like this is used. As a result, the fundamental laser beam 13 and the wavelength conversion laser beam 14 are placed in the vicinity of or inside the wavelength conversion crystal 11 for generating the sum frequency (difference frequency) while the positional deviation of the focusing point between the two wavelengths is reduced. Therefore, highly efficient sum frequency (difference frequency) generation can be realized.

  Therefore, in the wavelength conversion laser device according to the present embodiment, the beam waist is made coincident and wavelength conversion is performed in the vicinity of the sum frequency (difference frequency) generating crystal, so that high wavelength conversion efficiency is effectively obtained. A wavelength conversion laser device that can be used has been realized.

  In the wavelength conversion laser device according to the present embodiment, the configuration described in the first embodiment can be used. That is, the configuration between the fundamental wave light source 1 and the wavelength conversion crystal 9 is the same as that of the first embodiment described above. As a result, the same effect as described above can be obtained.

  Also, in this case, for example, when the source of the fundamental wave laser beam is a solid-state laser oscillator and the thermal lens of the laser active medium varies, the fluctuation of the wavelength-converted crystal parameter is suppressed, and the fluctuation of the wavelength-converted beam parameter, etc. Demonstrates the effect of keeping low. That is, a high-quality wavelength conversion laser device that is not greatly affected by the thermal strain of the solid-state laser crystal can be configured.

  In addition, the fundamental laser beam source as described above includes not only a solid-state laser oscillator but also an amplifier, etc., and when the thermal lens of the laser active medium or thermal distortion varies, the beam fluctuation of the wavelength conversion crystal position is suppressed. It is effective in suppressing fluctuations in the wavelength conversion beam parameter. That is, it is possible to construct a high-quality wavelength conversion laser device that is not greatly affected by the thermal strain of the solid-state laser crystal in the amplifier.

Embodiment 3 FIG.
FIG. 6 is a configuration diagram showing the main configuration of the wavelength conversion laser device according to the third embodiment of the present invention. As shown in FIG. 6, the wavelength conversion laser device according to this embodiment includes a fundamental wave light source 1, a condenser lens 8a, a wavelength conversion crystal 9a, a condenser lens 20, and a sum frequency (difference frequency) generation. The optical wavelength conversion crystal 11a and the beam splitter mirror 12a are provided.

  The fundamental wave light source 1 is fundamental wave laser beam generating means for generating a fundamental wave laser beam. The condensing lens 8a is a condensing lens that condenses the fundamental laser beam emitted from the fundamental wave light source 1 in or near the wavelength conversion crystal 9a, and is disposed on the optical axis of the fundamental laser beam. The The wavelength conversion crystal 9a is wavelength conversion means for performing wavelength conversion of the fundamental wave laser beam, and is disposed on the optical axis of the fundamental wave laser beam.

  The condensing lens 20 is a condensing lens that condenses the fundamental wave laser beam and the wavelength-converted laser beam wavelength-converted by the wavelength conversion crystal 9a, and the focal length is determined by the fundamental wave laser beam and the wavelength-converted laser beam. Have different characteristics and are arranged on the optical axis of the fundamental laser beam. Here, a single lens is used as the condenser lens 20. The sum frequency (difference frequency) generating wavelength conversion crystal 11a is a wavelength conversion crystal for generating a sum frequency or a difference frequency, and is disposed on the optical axis of the fundamental laser beam.

  The beam splitter mirror 12a is coated so as to exhibit a high transmittance with respect to the sum frequency (difference frequency) laser beam and a high reflectance with respect to the fundamental laser beam and the wavelength-change laser beam. The (difference frequency) laser beam 15 is separated from the fundamental laser beam 13 and the wavelength-change laser beam 14.

  Next, the operation of the wavelength conversion laser device according to this embodiment configured as described above will be described. As shown in FIG. 6, the fundamental laser beam 16 generated from the fundamental wave light source 1 is near or near the wavelength conversion crystal 9a by the action of the condenser lens 8a disposed on the optical axis of the fundamental laser beam 16. It is condensed inside. For example, in the vicinity of the wavelength conversion crystal 9a or in the inside thereof, the solid line 18a is focused as the focal point.

  Part of the condensed fundamental wave laser beam 16 is converted into a wavelength conversion laser beam 17 by the wavelength conversion crystal 9a. The wavelength conversion laser beam 17 and a part of the fundamental wave laser beam 16 remaining without being wavelength-converted in the wavelength conversion crystal 9 a are incident on the condenser lens 20. In the wavelength conversion laser device according to the present embodiment, as shown in FIG. 6, the fundamental wave light source 1 fundamentally prevents the outer edge portion 16a of the fundamental wave laser beam 16 from protruding from the outer diameter of the condenser lens 8a. A wave laser beam is emitted. Further, the outer edge portion 17 a of the wavelength conversion laser beam 17 exists inside the outer edge portion 16 a of the fundamental wave laser beam 16.

  Here, since a single lens is used as the condensing lens 20, the condensing points of the wavelength conversion laser beam 17 and the fundamental laser beam 16 are shifted using chromatic aberration. Thereby, the wavelength conversion laser beam 17 is condensed, for example in the wavelength conversion crystal 11a for sum frequency (difference frequency) generation, or near the position of the solid line 19a. The fundamental laser beam 16 is condensed with the position of the solid line 21 as the focal point in or near the wavelength conversion crystal 11a for generating sum frequency (difference frequency), for example.

  When the wavelength conversion laser beam 17 and the fundamental wave laser beam 16 are incident, a sum frequency (difference frequency) laser beam is generated by the action of the wavelength conversion crystal 11a for generating the sum frequency (difference frequency), and the wavelength conversion laser beam is generated. 14, the fundamental laser beam 13, and the sum frequency (difference frequency) laser beam are incident on the beam splitter mirror 12. In the beam splitter mirror 12, only the sum frequency (difference frequency) laser beam is separated from the fundamental laser beam 13 and the wavelength conversion laser beam 14 and extracted.

  In the wavelength conversion laser device according to the present embodiment as described above, a single lens is used as a condensing element to the wavelength conversion crystal for generating the sum frequency (difference frequency), and a plurality of laser beams are used by utilizing chromatic aberration. The focal point is shifted. That is, the condensing points of the fundamental laser beam and the wavelength conversion laser beam do not coincide with each other in the vicinity of or inside the wavelength conversion crystal 11a for generating the sum frequency (difference frequency). For this reason, the relative placement accuracy of the wavelength conversion crystal for generating the sum frequency (difference frequency) in the optical axis method with respect to the condenser lens is relaxed, and the placement accuracy for the wavelength conversion crystal for generating the sum frequency (difference frequency) is set. A wavelength conversion laser device with a wide accuracy tolerance is realized, and a wavelength conversion laser device that is easy to manufacture is realized.

In addition, even when the fundamental laser beam parameter fluctuates for some reason, it is possible to provide an apparatus that can suppress the fluctuation of the sum frequency (difference frequency) generation wavelength conversion efficiency. For example, an infrared solid-state laser such as Nd: YAG or Nd: YVO ₄ is used as a fundamental light source, and a wavelength conversion element such as a type 1 phase matching LBO (LiB ₃ O ₅ ) is shown as a second harmonic shown by a wavelength conversion crystal 9a. When used as a wave generation wavelength conversion element and the wavelength conversion crystal 11a for generating sum frequency (difference frequency) is a type 2 phase matching LBO (LiB ₃ O ₅ ), the wavelength conversion element LBO (LiB ₃ O ₅ ) Therefore, the sum frequency (difference frequency) generation wavelength conversion can be performed even when the focal point is deviated from 1 mm to 10 mm.

  Further, the longer the wavelength conversion crystal length is, and the larger the condensing diameter is, the smaller the influence when the beam waist position is displaced from the center of the wavelength conversion crystal is. Therefore, the wavelength conversion crystal length is about 10 mm. When the waist beam diameter in the vicinity of the crystal position is about 100 μm or more, the effect of the present invention is particularly great.

  FIG. 7 shows the result of calculating the relative value of wavelength converted light (third harmonic output) when third harmonic generation is performed using a calculation code. The parameters used in the calculation of FIG. 7 are: the average power of incident 1064 nm light is 50 W, the repetition frequency is 20 kHz, the pulse width is 50 ns, the SHG crystal length is 15 mm, the condensing diameter at the SHG crystal position is 200 μm, and the THG crystal length is 15 mm. The condensing diameter at the THG crystal position is 200 μm. As can be seen from FIG. 7, even if the waist position is shifted by approximately 10 mm, the output can be reduced to 5% or less when there is no shift of the beam waist position.

  In the wavelength conversion laser device according to the present embodiment, the configuration described in the first embodiment can be used. That is, the configuration between the fundamental wave light source 1 and the wavelength conversion crystal 9a is the same as that of the first embodiment described above. As a result, the same effect as described above can be obtained.

  Also, in this case, for example, when the source of the fundamental wave laser beam is a solid-state laser oscillator and the thermal lens of the laser active medium varies, the fluctuation of the wavelength-converted crystal parameter is suppressed, and the fluctuation of the wavelength-converted beam parameter, etc. Demonstrates the effect of keeping low. That is, a high-quality wavelength conversion laser device that is not greatly affected by the thermal strain of the solid-state laser crystal can be configured.

  In addition, the fundamental laser beam source as described above includes not only a solid-state laser oscillator but also an amplifier, etc., and when the thermal lens of the laser active medium or thermal distortion varies, the beam fluctuation of the wavelength conversion crystal position is suppressed. It is effective in suppressing fluctuations in the wavelength conversion beam parameter. That is, it is possible to construct a high-quality wavelength conversion laser device that is not greatly affected by the thermal strain of the solid-state laser crystal in the amplifier.

  As described above, the wavelength conversion laser device according to the present invention is useful when it is required that the fluctuation of the wavelength conversion efficiency is small even when the fundamental wave beam changes.

It is a block diagram which shows the main structures of the wavelength conversion laser apparatus concerning Embodiment 1 of this invention. It is a block diagram which shows the main structures of the wavelength conversion laser apparatus concerning Embodiment 1 of this invention. It is a characteristic view which shows the example of design calculation about the wavelength conversion laser apparatus concerning Embodiment 1 of this invention. It is a characteristic view which shows the example of design calculation about the wavelength conversion laser apparatus concerning Embodiment 1 of this invention. It is a block diagram which shows the main structures of the wavelength conversion laser apparatus concerning Embodiment 2 of this invention. It is a block diagram which shows the main structures of the wavelength conversion laser apparatus concerning Embodiment 2 of this invention. It is a block diagram which shows the main structures of the wavelength conversion laser apparatus concerning Embodiment 3 of this invention. It is a characteristic view which shows the calculation result of the relative value of the wavelength conversion efficiency of the wavelength conversion laser apparatus concerning Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Condensing lens 3 Condensing lens 4 Wavelength conversion crystal 7 Condensing point 9 Wavelength conversion crystal 9a Wavelength conversion crystal 10 Achromatic lens 11 Generation wavelength conversion crystal 11a Generation wavelength conversion crystal 12 Beam splitter mirror 12a Beam splitter mirror 13 Basic Wave laser beam 13a Outer edge of fundamental wave laser beam 14 Wavelength change laser beam 14a Outer edge of wavelength change laser beam 15 Sum frequency (difference frequency) laser beam 16 Fundamental laser beam 17 Wavelength conversion laser beam 20 Condensing lens 52 Condensing Lens moving means 53 Condensing lens moving means 54 Data holding unit

Claims (11)

A wavelength conversion laser device that advances a fundamental wave laser beam in one direction and performs wavelength conversion of the fundamental wave laser beam by a nonlinear effect,
A fundamental laser beam source for generating the fundamental laser beam;
A wavelength conversion element that is disposed on the optical axis of the fundamental laser beam emitted from the laser beam light source and performs wavelength conversion of the fundamental laser beam by a nonlinear effect;
Provided between the fundamental laser beam light source on the optical axis of the fundamental laser beam and the wavelength conversion element so as to be able to reciprocate on the optical axis of the fundamental laser beam, with respect to the wavelength conversion element A plurality of condensing means for condensing the fundamental laser beam;
Moving means for moving the condensing means in the optical axis direction of the fundamental laser beam;
A wavelength conversion laser device comprising:   The wavelength conversion laser device according to claim 1, comprising two condensing means.   The wavelength conversion laser device according to claim 1, comprising three condensing means.   3. The wavelength conversion laser device according to claim 1, wherein the condensing unit is a condensing lens. The correction data for moving the plurality of condensing means is provided, and the plurality of condensing means are moved in the optical axis direction of the fundamental laser beam based on the correction data. The wavelength conversion laser device described in 1. The wavelength conversion laser device according to claim 1, wherein the fundamental laser beam light source is a solid-state laser device. The wavelength conversion laser device according to claim 1, wherein the fundamental laser beam light source is a solid-state laser device including an amplifier. A wavelength conversion laser device that generates a laser beam of another wavelength from a plurality of laser beams having different wavelengths by a non-linear effect,
A laser beam light source for generating a plurality of laser beams having different wavelengths;
A wavelength conversion element that is arranged on an optical axis of a laser beam emitted from the laser beam light source and generates laser beams of other wavelengths from the plurality of laser beams having different wavelengths by a non-linear effect;
A wavelength conversion laser comprising: a plurality of optical members, wherein the plurality of laser beams are focused on the wavelength conversion element or the vicinity thereof so that the focal points of the plurality of laser beams are substantially the same. apparatus. A wavelength conversion laser device that generates a laser beam of another wavelength from a plurality of laser beams having different wavelengths by a non-linear effect,
A laser beam light source for generating a plurality of laser beams having different wavelengths;
A wavelength conversion element that is arranged on an optical axis of a laser beam emitted from the laser beam light source and generates laser beams of other wavelengths from the plurality of laser beams having different wavelengths by a non-linear effect;
The wavelength conversion laser device characterized in that the plurality of laser beams are condensed on the wavelength conversion element or the vicinity thereof so that the condensing points of the plurality of laser beams are different. The wavelength conversion laser device according to claim 8 or 9, wherein the laser beam light source is a solid-state laser device. The wavelength conversion laser device according to claim 8 or 9, wherein the laser beam light source is a solid-state laser device including an amplifier.

Images