A wavelength conversion laser and a machining device using the same

Wavelength conversion laser device and laser processing device

[Background of the invention]

The present invention relates to a wavelength conversion laser device and a laser processing device, wherein the laser device generates a high-output and high-focus synthetic frequency laser beam in a stable method with high reproducibility.

Figure 15 is a schematic diagram showing the structure of a conventional wavelength conversion laser device, for example, as shown in Japanese Patent Publication No. 148496/1975 (Takukaishou 50-1480961). In Figure 15, reference numeral 1 indicates a laser resonator mirror with high reflectivity for fundamental laser beams, numeral 3 indicates a solid active medium, numeral 6C Represents the second harmonic generation wavelength conversion crystal, 7C represents the synthetic frequency generation (third harmonic generation) conversion crystal, 9 is the laser resonator mirror, which has the effect of the second harmonic laser beam and the fundamental wave laser beam High reflectivity, and 18 is a mirror with high reflectivity for the fundamental wave laser beam and high conductivity for the second harmonic and synthetic frequency laser beam.

In the wavelength conversion laser device shown in Figure 15, part of the fundamental wave laser beam generated by the laser resonator including the laser resonator mirror 1, 9 and the mirror 18 and the solid active medium 3 is used The second-harmonic generation wavelength conversion crystal 6C located in the laser resonator transforms into a second-harmonic laser beam, and part of the second-harmonic laser beam generated by this method and part of the fundamental wave laser The laser beam is converted into a third-harmonic laser beam which is a laser beam with a synthesized frequency by using the synthesized frequency generating wavelength conversion crystal 7C. The second harmonic laser beam (2ω) and the third harmonic laser beam (3ω) without wavelength conversion can be separated from the mirror 18. In the above-mentioned wavelength conversion laser device, the synthesized frequency generation wavelength conversion crystal and the second harmonic generation wavelength conversion crystal are inserted into the laser resonator to generate the synthesized frequency laser beam, and each wavelength conversion crystal is adjusted interactively The angle and temperature can maximize the output of the synthesized frequency laser beam.

In the case shown in Figure 15, by inserting the synthetic frequency generation wavelength conversion crystal and the second harmonic generation wavelength conversion crystal into the laser resonator, a wavelength conversion laser for generating a synthetic frequency laser beam can be constructed. Device. However, the wavelength conversion efficiency will change with the angle and temperature of the wavelength conversion crystal, so it will cause the characteristics of the fundamental wave laser beam in the laser resonator to also change; therefore, it is necessary to construct a highly reproducible one. This device is very difficult. The complexity and difficulty of constructing such a device is far greater than the complexity and difficulty of constructing a basic wave laser beam generating device and a second harmonic laser beam generating device, because there is only a laser resonator. It has a wavelength conversion crystal. Furthermore, Gazette Patent No. 2654728 and others also disclose wavelength conversion laser devices, where the wavelength conversion crystal is placed in the laser resonator; however, as shown in Figure 15, even if these devices are used, It is also difficult to provide devices with high reproducibility.

The above-mentioned complexity in the wavelength conversion laser device where the output power change is determined by the angle and temperature of the wavelength conversion crystal, and the inevitable obstacles in manufacturing the device, such as the difference in parts and the difference in the ability of individual operators , Making it difficult to manufacture and mass-produce wavelength conversion laser devices in factories. Furthermore, the complicated work procedures required for manufacturing and repairing devices also increase production costs. On the other hand, it requires specialized staff.

When the laser beam generated by the above-mentioned wavelength conversion laser device is used for processing, if the components of the laser device (such as semiconductor lasers and bulbs used for pressurized light sources, wavelength conversion crystals and mirrors, etc. When optical parts are damaged and must be replaced, time-consuming adjustments must be made to the optical system and resonator. Therefore, it is sometimes difficult to reproduce the same processing results as before repairs even under the same operating conditions. Because the laser device cannot be reproduced in the same state as before repair.

[Summary of the invention]

The wavelength conversion laser device according to the first item of the patent application of the present invention is to obtain a composite frequency laser beam by putting the second harmonic generation wavelength conversion crystal and the synthesized frequency generation wavelength conversion crystal into a laser resonator The characteristic of the wavelength conversion laser device is that the length of the second harmonic generation wavelength conversion crystal is shorter than the synthetic frequency generation wavelength conversion crystal used.

Furthermore, the laser device according to the second item of the patent application is the same as the laser device of the first item of the patent application. Its characteristic is that the synthetic frequency generation wavelength conversion crystal is used as the third harmonic generation wavelength. Transform the crystal.

Furthermore, the laser device according to item 3 of the scope of patent application is the same as the wavelength conversion laser device of item 1 of the scope of patent application. Its characteristic is that the synthetic frequency generation wavelength conversion crystal is made of multiple wavelength conversion crystals. of.

The laser device according to item 4 of the scope of patent application is the same as the laser device of item 3 in the scope of patent application. Its characteristic is that the synthetic frequency generation wavelength conversion crystal is two wavelength conversion crystals, so it can generate fourth harmonics. Laser beam.

Furthermore, the laser device according to item 5 of the scope of patent application is the same as the laser device of item 1 in the scope of patent application. Its characteristic is that the synthetic frequency generation wavelength conversion crystal is placed in a solid laser active medium and the Harmonics are generated between the wavelength conversion crystals.

Furthermore, the laser device according to item 6 of the scope of patent application is the same as the laser device of item 1 in the scope of patent application, and its characteristic is that the resonant Q modulating element is placed in the laser resonator.

The laser device according to item 7 of the scope of patent application is the same as the laser device of item 1 in the scope of patent application. The angle of a wavelength conversion crystal.

Furthermore, the laser device according to item 8 of the scope of patent application is the same as the wavelength conversion laser device of item 1 in the scope of patent application. Accuracy, fine-tune the temperature of at least one of the wavelength conversion crystals.

Furthermore, the laser device according to item 9 of the scope of patent application is the same as the wavelength conversion laser device of item 1 in the scope of patent application, and its characteristic is to put a polarization control element in the laser resonator.

The laser device according to item 10 of the scope of patent application is the same as the wavelength conversion laser device of item 1 in the scope of patent application, and its characteristics are Nd:YLF or Nd:YAF or Nd:YVO4 as solid-state laser activity medium.

The laser device according to item 11 of the scope of patent application is the same as the laser device of item 1 in the scope of patent application, and its characteristics are at least LBO (LiB₃O₆) The crystal is one of the second harmonic generation wavelength conversion crystal or the synthesized frequency generation wavelength conversion crystal.

Furthermore, the laser device according to item 12 of the scope of patent application is the same as the wavelength conversion laser device of item 1 in the scope of patent application, and its characteristic is that the average output power of the composite frequency laser beam is not less than 1W.

Furthermore, the laser device according to item 13 of the scope of patent application is the same as the wavelength conversion laser device of item 1 in the scope of patent application, and its characteristics are the second harmonic generation wavelength conversion crystal and the synthesized frequency generation wavelength conversion The crystal is integrated into a wavelength conversion element, so the temperature or angle of the second harmonic generation wavelength conversion crystal and the synthesized frequency generation wavelength conversion crystal can be changed as a whole.

The processing device according to item 14 of the scope of patent application is a laser processing device that uses the wavelength conversion laser beam generated by the wavelength conversion laser disclosed in item 1 of the scope of patent application as the light source to process the processed object.

[Detailed description]

<u>Example 1</u>

Figure 1 is a schematic diagram showing the structure of Example 1 of the present invention. In Figure 1, reference numeral 1 is a laser resonator mirror with high reflectivity for the fundamental wave laser beam, and 2 indicates a polarizer such as a Brewster plate used to control the polarization of the fundamental wave laser beam in the resonator. 3 is a solid laser active medium, 4 is a mirror with high reflectivity for the fundamental wave laser beam and high penetration for the second harmonic laser beam, 5 is a laser beam with a synthetic frequency It is a mirror with high penetration and high reflectivity for the second harmonic laser beam and the fundamental wave laser beam. 6 is the second harmonic generator used to generate the second harmonic laser beam Wavelength conversion crystal, 2 is the synthesis frequency generation wavelength conversion crystal used to generate the synthesized frequency (or third harmonic) laser beam, 8 is the Q value switching device as the resonator Q modulation element, and 9 is the pair basis A laser resonator mirror with high reflectivity for wave laser beams and second harmonic laser beams. Furthermore, the number 20 indicates the optical axis of the laser oscillation. As shown in the figure, the length of the second harmonic generation wavelength conversion crystal 6 in the direction of the optical axis<i>l</i>_2ωSet the length of the wavelength conversion crystal 7 in the direction of the optical axis compared to the synthesized frequency<i>l</i>_3ωshort.

In the wavelength conversion laser device shown in Figure 1, the laser resonator mirrors 1 and 9 are used as laser resonators, and the mirrors 4 and 5. The solid-state laser active medium 3, the polarizer 2 and the Q-switching device 8 generate a linearly polarized fundamental wave pulsed laser beam, and a part of this beam is placed in the second harmonic of the laser resonator. The wave generating wavelength conversion crystal 6 converts into a second harmonic laser beam. A part of the resulting second harmonic laser beam and a part of the fundamental wave laser beam that has not been converted into a second harmonic laser beam are generated by the synthetic frequency placed in the laser resonator The wavelength conversion crystal 7 is converted into a third-harmonic laser beam which is a synthetic frequency laser beam. Extraction from the mirror 5 thus generates a third-harmonic laser beam (3ω), and extraction from the mirror 4 thus generates a second-harmonic laser beam (2ω).

Here, with the present invention, it is the first time to discover the length of the second harmonic generation wavelength conversion crystal 6 in the optical axis direction<i>l</i>_2ωSet the length of the wavelength conversion crystal 7 in the direction of the optical axis compared to the synthesized frequency<i>l</i>_3ωShort, it can reduce the negative influence of the angle and temperature of the wavelength conversion crystal generated by the second harmonic generation at the synthesis frequency laser beam, thus providing high synthesis frequency generation efficiency. The following description will explain the reason for this achievement.

In order to explain the relationship between the angle of the wavelength conversion crystal and the output power of the laser beam in the internal synthesis frequency generation, first, the wavelength conversion outside the resonator will be explained. In other words, when the wavelength conversion crystal is placed in the resonator The relationship between the angle of the wavelength conversion crystal and the output of the laser beam in the second harmonic generation. Figure 2 shows the output power of the second harmonic laser beam and the phase matching angle θ of the wavelength conversion crystal around₀The relationship diagram of the angle θ can be found in the document "Handbook of Nonlinear Optical Crystals" ("Handbook of Nonlinear Optical Crystals"), (Second Edition, Revised and Updated Edition (Springer Verlag)), etc. The angle of the wavelength conversion crystal on the horizontal axis is deviated from the phase matching angle θ₀The angle difference (θ-θ₀) Means (here the incident condition of the fundamental wave beam is constant). In Figure 2, the relationship between the second harmonic laser beam output I, the number of phase mismatches ΔK, and the length of the second harmonic generation wavelength conversion crystal 1 is the following equation:

<img file="TW453003B_D0001.tif" />

In formula (1), the number of phase mismatches Δk and the angular difference from the phase matching angle (θ-θ₀) Is proportional to

<img file="TW453003B_D0002.tif" />

Here, the phase-matching acceptance angle Δθ is usually used as a numerical value describing the angular relationship characteristics of the wavelength conversion crystal. As shown in Figure 2, Δθ represents the angular width between the angles of the second harmonic laser beam when the output power of the second harmonic laser beam is half of the maximum output power. Here, from the relationship between formula (1) and Δθ, when ΔK1=0.886π, (θ-θ₀)=Δθ. Δθ is an inherent value used in the wavelength conversion crystal and its phase matching method.

Regarding the values of special examples reported in the "Handbook of Nonlinear Optical Crystals" (Second Edition, Revised and Updated Edition (Springer Verlag)), when LBO (LiB₃O₅) Type 1 When the angle phase matches the second harmonic generation, Δθ=0.34 (degree×cm), and when KTP (KTiOPO₄) When the type 2 angle phase matches the second harmonic generation, A8=0.53 (degree×cm).

When the angle of the wavelength conversion crystal changes, when<img file="TW453003B_D0003.tif" />There will be a peak when the wavelength conversion crystal is longer. As shown in Figure 2, the output peak interval of the second harmonic and the width of each peak become narrower. This results in that when the length of the wavelength conversion crystal is longer , In the case that the second harmonic generation wavelength conversion crystal is shifted within a given angle range, the peak number of the second harmonic output power that appears increases.

Here, when the second-harmonic wavelength conversion crystal is placed outside the fundamental wave laser resonator in order to achieve second-harmonic generation, that is, the wavelength conversion outside the cavity, as shown in Figure 2 in the phase matching Angle θ₀(In equation (1), Δk1=0), the second harmonic output is higher than that of other peaks (in equation (1)<img file="TW453003B_D0004.tif" />The second harmonic output of is much larger; therefore, this configuration can be easily implemented without causing difficulties in practical applications.

Based on the above description, the second harmonic generation wavelength conversion crystal will be placed inside the laser resonator to achieve wavelength conversion as an example, that is, the case of wavelength conversion in the cavity. Figure 3 shows that when only the second harmonic generation wavelength conversion crystal is placed in the laser resonator as the wavelength conversion crystal to achieve second harmonic generation, the angle of the wavelength conversion crystal and the second harmonic laser beam The relationship between the output power (line B) and the power of the fundamental wave laser beam in the cavity (line A). For comparison, the dashed line (C) is used to show the angle relationship diagram obtained when the same wavelength conversion crystal is used to achieve the wavelength conversion outside the cavity. The arrow between lines B and C indicates the change of the output power of the second harmonic laser beam when the conversion from outside the cavity to the conversion inside the cavity occurs.

The following description will discuss the reasons for the characteristics shown in Figure 3 when the second harmonic generation wavelength conversion crystal is placed inside the laser resonator so as to utilize the high reflectivity of the fundamental wave laser beam. When the laser resonator constructed by the mirror realizes the second harmonic generation, the part of the fundamental wave beam power transformed into the second harmonic beam is extracted from the resonator as the output in the resonator. For this reason, increasing the conversion efficiency of the second harmonic beam is actually like increasing the output coupling rate of the fundamental wave beam. On the contrary, reducing the conversion efficiency is actually like reducing the output coupling rate. Therefore, when the conversion efficiency of the second harmonic beam increases, the power of the fundamental wave beam inside the resonator will decrease, and when the conversion efficiency of the second harmonic beam decreases, the power of the fundamental wave beam inside the resonator will increase. . As shown in Figure 3, when the angle of the second harmonic generation wavelength conversion crystal changes, the fundamental wave power in the resonator is at a certain angle with high wavelength conversion efficiency (for example, the phase matching angle θ₀) Will decrease; conversely, the fundamental wave power in the resonator will increase at a certain angle with low wavelength conversion efficiency. Here, the second harmonic beam output power is equal to the product of (wavelength conversion efficiency) and (basic wave beam power in the cavity); therefore, if compared with the external wavelength conversion shown by the dotted line, when the wavelength is converted in the cavity, The difference between the output power of the second harmonic laser beam at an angle with higher wavelength conversion efficiency and the output power of the second harmonic laser beam at an angle with lower wavelength conversion efficiency becomes smaller. Therefore, as shown in Figure 3, at angles other than the phase matching angle of 0o (in equation (1),<img file="TW453003B_D0005.tif" />And at the phase matching angle of 8o (in the formula (1)<img file="TW453003B_D0006.tif" />), the difference between the peaks of the second harmonic output power becomes smaller. Therefore, as shown in Figure 3, the multiple peaks whose output is not very different are determined by the second harmonic output at the angle of the second harmonic generation wavelength conversion crystal shown in Figure 3 In terms of angle, it is difficult to find the angle that obtains the maximum second harmonic output by changing the angle. In the past, it was not possible to observe in detail the relationship between the second harmonic laser beam output caused by these changes in the beam power in the cavity and the complex wavelength conversion crystal angle.

Furthermore, during the intra-cavity wavelength conversion, the power of the fundamental wave beam determined by the above-mentioned second harmonic generation wavelength conversion crystal angle in the resonator is changed. It becomes obvious when the Q-switched oscillator is implemented inside the device because of its high wavelength conversion efficiency. In this case, the second harmonic output characteristics determined by the above-mentioned wavelength conversion crystal angle will become very complicated.

Next, it will be explained that if the configuration to realize the synthesis frequency generation is to use the intra-cavity wavelength conversion with the above characteristics to generate the second harmonic, at the same time, install a laser resonator to realize the synthesis frequency generation. When the synthesized frequency generates the wavelength conversion crystal, the relationship between the output of the synthesized frequency laser beam and the angle of the second harmonic generation wavelength conversion crystal. Figure 4 shows the changes in the laser beam output (line B) of the combined frequency and the power of the fundamental wave laser beam (line A) in the resonator when the angle of the second harmonic generation wavelength conversion crystal changes. For comparison, the dotted line (C) represents the second harmonic laser beam power in the case of out-of-cavity conversion. Since the second harmonic laser beam output is proportional to (the fundamental wave laser beam at the wavelength conversion crystal)2, and because the composite frequency laser beam output is proportional to (the second harmonic laser beam is in the wavelength conversion crystal The intensity at the position)×(the intensity of the fundamental wave laser beam at the wavelength conversion crystal) is proportional, so when comparing the second harmonic output represented by the dotted line in Figure 3 and Figure 4, the combined frequency laser beam The output is more likely to be affected by changes in the power of the fundamental wave laser beam in the cavity. Therefore, as shown in Figure 4, when the angle of the second harmonic generation wavelength conversion crystal is at the phase matching angle θ₀(Of formula (1)<img file="TW453003B_D0006.tif" />), the matching angle θ₀The surrounding crest (of formula (1)<img file="TW453003B_D0008.tif" />At the time, the difference of the laser beam output of the synthesized frequency becomes smaller than that at the second harmonic generation. Therefore, when compared with the second harmonic output characteristics in Figure 3, the number of crests with similar output increases, making it difficult to find the angle at which the maximum synthesized frequency output can be obtained by changing the angle.

Furthermore, when the length of the second harmonic generation wavelength conversion crystal is set to be longer than the predetermined length, as shown in Figure 4, the second harmonic laser beam intensity at the synthesis frequency generation wavelength conversion crystal is at the second Phase matching angle θ of the highest point of laser harmonic beam output₀And the surrounding area becomes higher, but the intensity of the fundamental wave laser beam decreases. As a result, as shown in part a and b in Figure 4, the phase of the maximum second harmonic output can sometimes be obtained from the deviation Matching angle θ₀Get the maximum synthetic frequency laser beam output. In this case, more similar composite frequency laser beam output peaks can be obtained. Regarding the combination sequence of the wavelength conversion laser device, first, set one of the mirrors constituting the laser resonator as a part of the fundamental wave beam penetrating the mirror, and when a part of the fundamental wave laser beam is extracted When the resonator is used, the configuration of this optical element makes the laser resonator optimal for the fundamental wave output. After that, the partially penetrating mirror is replaced with a total reflection mirror, and the second harmonic is generated. The wavelength conversion crystal is inserted into the laser resonator so that the angle between the optical element and the wavelength conversion crystal is optimized for the second harmonic laser beam output. Then, the synthesized frequency generation wavelength conversion crystal is inserted into the laser resonator Therefore, the wavelength conversion crystal and the optical element can be arranged to realize the round out of the synthesized frequency generation. Here, the optimal angle between the optical element and the wavelength conversion crystal is changed by inserting the synthesized frequency generating wavelength conversion crystal into the laser resonator And because the optimum angle of the second harmonic generation wavelength conversion crystal used for second harmonic generation does not need to be consistent with the optimum angle for stable and high-output synthetic frequency generation, it is constructed in many cases The second harmonic generation wavelength conversion crystal and optical components of the laser resonator must be rearranged. Therefore, when the synthesized frequency laser beam is generated, the angle of the second harmonic wavelength conversion crystal must be changed to find the best Arrangement procedures for optimal angles. Therefore, the angle corresponding to the second harmonic generation wavelength conversion crystal, because there are many peaks of the composite frequency laser output with the same size, it will be a stable wavelength conversion device with high reproducibility. The main obstacle.

Furthermore, when trying to increase the combined frequency laser beam output of the laser beam generator for combining the combined frequency in the cavity wavelength conversion to the maximum, the efficiency of the conversion from the fundamental wave beam to the second harmonic beam has an optimal value. In other words, the higher is not the better. In other words, when the efficiency of the conversion into the second harmonic beam is too high, the fundamental wave beam is reduced, resulting in a reduction in the output power of the combined frequency beam. On the contrary, regarding the efficiency of transforming the fundamental wave beam and the second harmonic beam into a composite frequency beam, if it becomes higher, the generated composite frequency laser beam becomes larger. In this way, in order to suppress the wavelength conversion efficiency of the second harmonic beam and increase the wavelength conversion efficiency of the composite frequency beam, the length of the composite frequency generating wavelength conversion crystal is set to be longer, in other words, the second harmonic The length of the harmonic generation wavelength conversion crystal is set to be shorter than the length of the synthesis frequency generation wavelength conversion crystal; therefore, by increasing the synthesis frequency generation efficiency, a stable wavelength conversion laser device with high reproducibility can be constructed. This fact is first disclosed by the present invention.

Next, we will discuss how the angle determined by the composite frequency output of the second harmonic generation wavelength conversion crystal changes according to the length of the second harmonic wavelength conversion crystal. First, Figure 5 and Figure b respectively show the power of the fundamental wave laser beam (line A) and two in the cavity when the second harmonic wavelength conversion crystal has a longer length and when it has a shorter length. The relationship between the power of the sub-harmonic laser beam (line B) and the angle of the second-harmonic generation wavelength conversion crystal, assuming that the synthesized frequency generation wavelength conversion crystal is not inserted at this time. The dotted line (C) represents the power of the second harmonic laser beam when transforming outside the cavity.

Comparing Fig. 5 and Fig. 6, for the same reason as explained in Fig. 2 and Fig. 3, when comparing Fig. 5, if Fig. 6 shows that the length of the second harmonic generation wavelength conversion crystal is longer Short, because the angular width and angular interval between the peaks (and sags) of the second harmonic laser beam output (and the power of the fundamental laser beam) are widened, so the angle of the wavelength conversion crystal is determined by the angle of the wavelength conversion crystal. The output of the sub-harmonic laser beam gradually changes, and the number of crests decreases. Therefore, by using a shorter second harmonic generation wavelength conversion crystal, the relationship between the output of the wavelength conversion laser beam and the angle of the second harmonic generation wavelength conversion crystal can be simplified, and an easily adjustable laser device can be obtained.

Furthermore, Fig. 7 and Fig. 8 respectively show the angle and synthesized frequency output of the second harmonic generation wavelength conversion crystal when the second harmonic wavelength conversion crystal has a longer length and when it has a shorter length. The power (line B) relationship diagram, assuming that the synthesized frequency generation wavelength conversion crystal is inserted into the resonator to generate the synthesized frequency laser beam. For comparison, the dotted line (c) represents the power of the second harmonic laser beam. Comparing Fig. 7 and Fig. 8 we can see that in the same way as the second harmonic generation inside the resonator, if the second harmonic generation wavelength conversion crystal has a shorter length as shown in Fig. 8 , The second harmonic laser beam intensity (and the laser beam power of the fundamental wave in the cavity) of the crest (concave) angular width and the crest (concave) interval are widened, and the number of crests is reduced. Therefore, it is possible to provide a laser device that has a relatively simple second harmonic generation wavelength conversion crystal angle relationship and can be easily operated. For specific values, for example, when using phase matching LBO (LIB₃O₅In the case of type 1, it is known from formula (1) that when the length of the crystal is 15mm, there will be a wave peak about every 8mrad, and when the length of the crystal is 5mm, a wave peak with a wider angle will appear at about 24mrad; and In the actual measurement, the interval between these peaks is substantially the same.

Furthermore, as explained in Figure 4, when a longer second harmonic generation wavelength conversion crystal is used, the intensity of the second harmonic laser beam at the synthesis frequency generation wavelength conversion crystal is lower than the second laser harmonic Phase matching angle θ of the highest point of beam output₀Because the wavelength conversion efficiency of the wavelength conversion from the fundamental wave laser beam to the second harmonic laser beam is too high, the power of the fundamental wave in the resonator is reduced. The result is shown in Figure 7. As shown, other peaks appear on the output characteristics of the laser beam at the synthesized frequency determined by the wavelength conversion angle of the second harmonic generation. Conversely, as shown in Figure 8, by using a shorter second harmonic to generate a wavelength conversion crystal, the phase matching angle θ₀The wavelength conversion efficiency of the wavelength conversion from the fundamental wave laser beam to the second harmonic laser beam in and around it is reduced, so that the intensity of the fundamental wave laser beam increases; therefore, the construction can be changed to the second harmonic laser beam output Maximum phase matching angle θ₀It is possible to obtain a laser device with the highest synthetic frequency laser beam output in and around it.

The following description will discuss how the resulting composite frequency laser beam output changes with the length of the second harmonic generation wavelength conversion crystal. Figure 9 shows the relationship between the laser beam output of the synthesized frequency when the length of the second harmonic generation wavelength conversion crystal changes. At this time, it is used for the intracavity wavelength conversion synthesis frequency generation as shown in Figure 1. In the structure, the synthetic frequency generates the length of the wavelength conversion crystal l_3ωIt is fixed. As shown in Figure 9, compared to the second harmonic generation wavelength conversion crystal, when the length of the second wavelength generation wavelength conversion crystal is changed, when the output of the synthesized frequency is monitored, there is a maximum output that can obtain the synthesized frequency laser beam Peak (with length 1 in figure 9₁Point). And when the length of the second harmonic generation wavelength conversion crystal is set to not less than 1₁In most cases, the synthesized frequency output will decrease slightly, or at least the output will not increase significantly. The main reasons are as follows:

(1) The effect of reducing the power in the cavity of the fundamental wave becomes greater than the effect of increasing the output power of the second harmonic.

(2) Because the wavelength conversion efficiency of the second harmonic generation wavelength conversion crystal increases, the pulse width becomes longer.

In this case, as mentioned earlier, when the length of the second harmonic generation wavelength conversion crystal becomes longer, some peaks appear in the laser beam output at the synthesized frequency determined by the angle of the second harmonic generation wavelength conversion crystal. Therefore, it leads to the problem of difficulty in adjustment.

For the characteristics shown in Figure 9, specific values obtained by actual verification are given. In the same structure as in Figure 1, it will have a length of 10mm._3ω. The third harmonic generation LBO crystal is used as a synthetic frequency generation wavelength conversion crystal, and has a repetitive frequency of several kHz and is about 5 to 10<i>W</i>The length of the second-harmonic generation wavelength conversion crystal in the laser device that outputs the beam of the synthesized frequency is variable; therefore, it generates 1% of the beam power of the maximum synthesized frequency.₁It is substantially equal to 3mm. Furthermore, the length of the second harmonic generation wavelength conversion crystal is not less than 10mm (l_3ωIn the case of ), even if the second harmonic generation wavelength conversion crystal is lengthened as shown in Figure 9, the output does not improve and its characteristics show a slight decrease. Here, it has been experimentally proved that the angle of the second harmonic generation wavelength conversion crystal has a dependence relationship as shown in Figure 7, making the adjustment very complicated. As described above, it has been experimentally determined that when the length of the second harmonic generation wavelength conversion crystal is compared with the length of the synthesized frequency generation wavelength conversion crystal and the former is shortened, sufficient synthesized frequency output power will be obtained and adjustment will also be easy. some.

Furthermore, when the second harmonic generation wavelength conversion crystal is set to be shorter, the wavelength conversion efficiency of converting the fundamental wave laser beam into the second harmonic laser beam is reduced, resulting in a shortened pulse width and the fundamental wave and the second harmonic wave. The intensity of the sub-harmonic wave becomes higher (as shown in the Journal of Applied Physics, Issue 41, page 609, "Pulse elongation generated by the internal second harmonic through over-coupling") (Journal of Applied Physics vol41, p609( Pulse Lengthening via Overcoupled Internal Second-Harmonic Generation)). Since the synthetic frequency generation efficiency is proportional to the intensity of the incident fundamental wave beam and the second harmonic beam, it can be installed to enhance the wavelength conversion efficiency of the fundamental wave beam and the second harmonic beam into the synthetic frequency beam. The device is possible.

Furthermore, the larger the wavelength conversion crystal, the more difficult it is to make it into a uniform crystal. (The longer the wavelength conversion crystal, the higher the price of the crystal.) Therefore, the use of a shorter second-harmonic generation wavelength conversion crystal can reduce the cost and therefore it is possible to construct a wavelength conversion laser device with required performance at low cost. Here, the minimum limit for the length is approximately set at not less than 0.5 mm, and this value is set in consideration of the manufacturing limit of the wavelength conversion crystal and the reduction of the wavelength conversion efficiency.

Furthermore, regarding the position where the wavelength conversion crystal is inserted, in the wavelength conversion laser device shown in Figure 1, the configuration is such that the synthesized frequency generation wavelength conversion crystal 7 is located in the solid laser active medium 3 and the secondary Between the harmonic generation wavelength conversion crystals 6: In this configuration, because the synthesized frequency output power is extracted from the mirror 5, when the fundamental wave and the second harmonic are reflected from the mirror 9 and return, the fundamental wave beam and The second harmonic beam will only pass through the synthetic frequency wavelength conversion crystal 7 once at the same time, which can reduce the negative effect on the synthesis frequency generation efficiency due to the temperature change and angle change of the wavelength conversion crystal, thus making it possible to obtain a stable device . On the contrary, when the positions of the second harmonic generation wavelength conversion crystal and the synthetic frequency wavelength conversion crystal are reversed, that is, the second harmonic generation wavelength conversion crystal is located between the synthetic frequency generation wavelength conversion crystal and the solid laser active medium. When the fundamental wave beam and the second harmonic wave are incident on the second harmonic generation wavelength conversion crystal and reflected by the mirror 9, the number of times that the wavelength conversion crystal is generated by combining the frequency at the same time will increase to second, resulting in the wavelength conversion crystal The negative effect of the temperature and angle on the synthetic frequency generation efficiency becomes larger, and the laser device is unstable. In fact, in the structure shown in Figure 1, by using a Q pulse wavelength conversion laser device with a combined frequency output power of 5 to 10W and a pulse width of ~100ns, a LBO crystal with a length of 10mm is used. As a synthetic frequency (third harmonic) wavelength conversion crystal, and by using an LBO crystal with a length of 5mm as a second harmonic generation wavelength conversion crystal, the wavelength conversion thunder can be found when the temperature of the synthesized frequency is changed to generate the wavelength conversion crystal. The output power of the laser beam and the output power of the fundamental wave laser beam in the cavity change. The results show that the temperature range that allows the synthesized frequency output to become 95% of the maximum output (the temperature difference between the allowable output to become 95% of the maximum output at a higher temperature level and a lower temperature setting) is about 1 to 2 degrees ; And when the position of the wavelength conversion crystal is reversed, the temperature range becomes no more than 0.3 degrees, so it can be determined that the structure of Figure 1 is superior.

<u>Example 2</u>

A device for fine-tuning the angle with an accuracy of ±0.1 degrees can be added to the second harmonic generation wavelength conversion crystal or synthesized frequency generation wavelength conversion crystal shown in Figure 1. Generally, the angle-adjustable phase-matched wavelength conversion crystal (a type of wavelength conversion crystal that achieves phase matching mainly by fine-tuning the angle of the wavelength conversion crystal, and can greatly change the phase matching conditions according to the angle of the wavelength conversion crystal) in the operating device It is often necessary to fine-tune the angle of the wavelength conversion crystal. Therefore, the complicated relationship between the synthesized frequency output and the angle of the wavelength conversion crystal, referring to the description of Figures 2 to 8, will greatly affect the operation of the wavelength conversion device. Therefore, when an angular phase matching type wavelength conversion crystal is used, the effect obtained by shortening the length of the second harmonic generation wavelength conversion crystal compared with the synthetic frequency generation wavelength crystal will become larger. In a wavelength conversion laser device that can complete the fine-tuning angle accuracy within ±0.1 degree as in the previous embodiment, setting the second harmonic generation wavelength conversion crystal to be shorter than the sum frequency generation wavelength conversion crystal is also A laser device that can be easily manipulated and has high reproducibility can be provided.

<u>Example 3</u>

A device for fine-tuning the temperature with an accuracy of ±0.5 degrees (Celsius) can be added to the second harmonic generation wavelength conversion crystal or synthetic frequency generation wavelength conversion crystal shown in Figure 1. Some wavelength conversion crystals have narrow temperature tolerance. For example, when the phase-matched LBO crystal of the third harmonic generation type 2 is used as the synthesis frequency to generate the wavelength conversion crystal, its temperature tolerance is displayed as 3.7 degrees (which is two temperature For the temperature range of the crystal with a length of 1cm, when the conversion efficiency is reduced to half compared with the conversion efficiency at the phase matching temperature) (such as in "Nonlinear Optical Crystals", (Second Edition, revised and updated version) (Springer Verlag), etc.). When using this kind of wavelength conversion crystal with relatively narrow temperature tolerance, sometimes the temperature of the wavelength conversion crystal must be controlled so that a laser device can be constructed, which can suppress the output power so that it will not cause problems in actual use Within the range, it can also avoid the damage of the wavelength conversion crystal caused by the increase of the power of the basic laser beam in the cavity, where the power increase is caused by the deterioration of the phase matching condition caused by the rapid temperature change in the wavelength conversion crystal; And it can be operated stably for a long time. In this embodiment, a mechanism is provided in the wavelength conversion laser device that can control the temperature of the wavelength conversion crystal with an accuracy of no more than ±0.5 degrees, and the second harmonic generation wavelength conversion crystal is set to be shorter than the synthesized frequency generation wavelength conversion crystal. , So it can provide a stable laser device with high reproducibility and easy manipulation.

<u>Example 4</u>

Regarding the solid-state laser active medium used in the wavelength conversion laser device as shown in Figure 1, Nd:YAG can be used. Nd: YAG is a laser material with high thermal conductivity and thermal fragmentation limitation, which is superior in chemical stability and mechanical strength. Furthermore, when compared with other solid laser active media, this material can provide optically high-quality crystals at low cost. The application of Nd:YAG as a solid-state laser active medium makes it possible to construct an easy-to-operate laser device with high reproducibility and flexibility at low cost.

<u>Example 5</u>

Regarding the solid-state laser active medium used in the wavelength conversion laser device as shown in Figure 1, Nd:YLF can be used. Nd: YLF has a small thermal lens effect. Generally, when a solid laser active medium is used to construct a laser device, the output of the laser becomes unstable due to changes in the focal length of the thermal lens of the solid laser active medium. Furthermore, when the Q pulse wave oscillation is performed, the stability of the pulse wave to the pulse wave sometimes decreases. The application of Nd:YLF with such a small thermal lens effect as a solid laser active medium makes it possible to construct a stable laser device that can be easily manipulated with a wide stable operating output range. Furthermore, if the synthetic frequency generation is accomplished by the Q pulse wave oscillation method, it is possible to construct a device with superior pulse wave to pulse wave stability.

<u>Example 6</u>

The wavelength conversion laser device shown in Figure 1 can use Nd: YVO₄As a solid laser active medium. Nd: YVO₄It has a wide wavelength absorption width to pressurize light and a larger lasing cross-sectional area. Application Nd: YVO₄As a solid laser active medium, it can provide a higher tolerance to the change of the wavelength of the pressurized light. Furthermore, because of the wide wavelength absorption width and lasing cross-sectional area, it can provide high fundamental wave beam generation efficiency. Furthermore, when constructing a Q-pulse laser device, since the lasing cross-sectional area is large, even if the Q value switching operation is performed by using a high repetition rate, a wavelength conversion laser beam with a shorter pulse width can be generated. In particular, since the pulse width is narrow, the wavelength conversion efficiency can be increased. Apply Nd with the above characteristics: YVO₄A wavelength conversion laser device that can be manipulated more easily can be provided.

<u>Example 7</u>

The wavelength conversion laser device shown in Figure 1 can use LBO (LiB₃O₅) As the second harmonic generation wavelength conversion crystal or synthesized frequency generation wavelength conversion crystal. Compared with other crystals, the LBO crystal has a higher damage threshold; therefore, it can produce a wavelength conversion laser beam with high output and high peak pulses. Furthermore, if compared with other second-harmonic generation wavelength conversion crystals like KTP crystals, its refractive constant determined by temperature has a smaller change and higher thermal conductivity; therefore, it is not easily affected by heat . What's more, when compared with β-BBO crystals currently used for third harmonic generation, this material has a wider tolerance for phase matching angles, so it can produce a higher cycle ratio (defined as the minimum diameter divided by the maximum (Diameter) composite frequency laser beam. Furthermore, because of its high thermal conductivity, it can generate a composite frequency laser beam with high output power and high efficiency in a stable manner. By using the LBO crystal with the above-mentioned superior characteristics as the second harmonic generation wavelength conversion crystal or the synthesized frequency generation wavelength conversion crystal shown in Figure 1, it is possible to construct a high output power and high efficiency that can be easily manipulated Stable wavelength conversion laser device.

<u>Example 8</u>

The wavelength conversion laser device of the present invention is particularly efficient when the composite frequency laser beam is rounded out at least 1W. When the average output power of the wavelength conversion laser beam extracted by the synthesized frequency generation wavelength conversion crystal and the second harmonic generation wavelength conversion crystal becomes larger, thermal deformation occurs on the wavelength conversion crystal, causing the output power to change. It becomes unstable and the alignment of the optical components becomes more difficult. Furthermore, since the solid laser active medium needs to be strongly pressurized in order to increase the output power, the solid laser active medium is also susceptible to deformation due to the influence of the thermal lens and thermal double radiation, which causes the output power to become unstable and optical Component alignment becomes more complicated. Furthermore, since the average intensity of the laser beam on the optical element increases, the optical element is more likely to be damaged. What's more, the phase matching angle of the wavelength conversion crystal will change due to temperature changes. In particular, when the average output power of the synthesized frequency laser beam becomes close to not less than 1W, the above-mentioned negative effects due to the thermal deformation of the components will appear significantly. In this case, by shortening the second harmonic generation wavelength conversion crystal, the characteristics that change according to the angle of the wavelength conversion crystal can be simplified, and the configuration with high reproducibility can be realized even under the effect of thermal deformation. Furthermore, since the phase matching angle tolerance of the second harmonic generation wavelength conversion crystal is widened, even when the phase matching angle changes due to temperature changes, the change in output power due to changes in phase matching conditions can be reduced. As described above, in the invention of the wavelength conversion laser device of the present invention, it is possible to provide a device which is stable and has high reliability and performance even under high output power operation with a synthesized frequency output power of not less than 1W. Easy to operate.

<u>Example 9</u>

Fig. 10 is a structural diagram showing the 9th embodiment of the present invention. In Figure 10, reference number 4a is a mirror with high reflectivity for the fundamental wave laser beam and high transmittance for the second harmonic laser beam and third harmonic laser beam, and 5a is A mirror with high transmittance for the fourth harmonic laser beam, and high reflectivity for the third harmonic, second harmonic and fundamental wave laser beam. 6a is the second harmonic generation wavelength conversion Crystal, 7a is the first synthesized frequency generating wavelength conversion crystal, and 10 is the second synthesized frequency generating wavelength conversion crystal. The length of the second harmonic generation wavelength conversion crystal 6a is shorter than the lengths of the synthesized frequency generation conversion crystals 7a and 10.

In the wavelength conversion laser device shown in Figure 10, a linearly polarized fundamental wave pulsed laser beam is composed of laser resonator mirrors 1, 9 and mirrors 4a, 5a, solid laser active medium 3, and polarizing elements 2 and Q switching element 8 are generated, and a part of this beam is converted into a second harmonic laser beam by the second harmonic generation wavelength conversion crystal 6a placed in the laser resonator. Part and part of the second harmonic laser beam generated in this way is not transformed into the fundamental wave of the second harmonic laser beam. The laser beam uses the first synthesized frequency placed in the laser resonator to generate wavelength conversion. The crystal 7a is transformed into a third harmonic laser beam. A part of the third harmonic laser beam generated in this way and a part of the fundamental wave laser beam are transformed into a fourth harmonic laser beam by using the second synthesis frequency generating wavelength conversion crystal 10. The fourth harmonic laser beam thus generated is extracted by the mirror 5a. The third harmonic laser beam and the second harmonic laser beam are extracted by the mirror 4a.

In the wavelength conversion laser device shown in Figure 10, in addition to the combined frequency generation wavelength conversion crystal 7a used to generate the third harmonic laser beam from the fundamental wave laser beam and the second harmonic laser beam, the The second synthesized frequency generation wavelength conversion crystal 10 for generating the fourth harmonic laser beam from the fundamental wave laser beam and the third harmonic laser beam is inserted into the laser resonator. In the laser device constructed by the above method, the second harmonic is generated by the length of the wavelength conversion crystal 6a<i>l</i>_2ωSet to be longer than the first synthesized frequency to generate the wavelength conversion crystal 7a<i>l</i>_3ωAnd the second synthesized frequency to generate the length of the wavelength conversion crystal 10<i>l</i>_4ω; Therefore, it is possible to simplify the output change of the composite frequency laser beam determined by the second harmonic generation wavelength conversion crystal angle. Here, Figure 10 shows an example of inserting two synthesized frequency generating wavelength conversion crystals in a laser resonator; however, the number of synthesized frequency generating wavelength conversion crystals is not limited to two.

<u>Example 10</u>

Fig. 11 shows a structure diagram according to the tenth embodiment of the present invention. In Figure 11, reference numerals 3a and 3b are solid laser active media, and 11 is a 900 polarization rotation device as a polarizing element.

In the wavelength conversion laser device with the structure shown in Figure 11, the 90° polarization rotation device 11 is placed between the two solid laser active media 3a and 3b, and is used in the wavelength conversion laser device to eliminate (Compensation) Thermal double refraction is determined by the polarization direction caused by the heat generated by the pressurized light and the oscillating laser beam inside the solid laser active medium. Therefore, it is broadened so that the composite frequency laser beam is It is possible to generate a pressurized area in a stable manner, and it can further improve the stability and reproducibility, and can also increase the oscillation efficiency. Furthermore, in the synthesized frequency generating device shown in Fig. 11, the length of the second harmonic generation wavelength conversion crystal 6 is set to be shorter than that of the synthesized frequency generation wavelength conversion crystal 7, so that it can be constructed with high reproducibility and reliability. A stable laser device that is easy to manipulate.

<u>Example 11</u>

Fig. 12 is a diagram showing the structure of the eleventh embodiment of the present invention. In Fig. 12, reference numeral 12 is a wavelength conversion element including two wavelength conversion crystals, that is, the synthesized frequency generation wavelength conversion crystal 7b and the second harmonic generation wavelength conversion crystal 6b are bonded or fixed in The methods on the same wavelength conversion crystal support are integrated. The wavelength conversion element 12 in which the second harmonic generation wavelength conversion crystal and the synthetic frequency generation wavelength conversion crystal are integrally placed together can provide a mechanism 19, which can perform such as changing the temperature as a whole and setting the refractive index of the wavelength conversion crystal ( (Varies according to temperature) phase matching program set to a predetermined value and fine-tuning angle. Furthermore, the length of the second harmonic generation wavelength conversion crystal 6b constituting the integrated wavelength conversion element 12 is set to be shorter than the synthetic frequency wavelength conversion crystal 7b.

In the wavelength conversion laser device shown in Figure 12, the linearly polarized fundamental wave pulsed laser beam consists of laser resonator mirrors 1, 4 and mirrors 5, 9, solid laser active medium 3, polarizing element 2 and Q A part of this beam is converted into a second harmonic laser beam by the second harmonic generation wavelength conversion crystal 6b that is formed by the wavelength conversion element 12 placed in the laser resonator and is generated by the switching element 8. A part of the second-harmonic laser beam generated in this way and part of the fundamental wave laser beam that have not been converted into a second-harmonic laser beam are converted by the synthetic frequency in the wavelength conversion element 12 to generate a wavelength conversion crystal 7b. Into a synthetic frequency laser beam. The laser beam of synthesized frequency thus generated is extracted from the mirror 5, and the second harmonic laser beam is extracted from the mirror 4.

In the wavelength conversion laser device shown in Fig. 12, when the second harmonic generation wavelength conversion crystal 6b and the synthesized frequency generation wavelength conversion crystal 7b are integrated into the wavelength conversion element 12, the second harmonic must be set. The wave-generating wavelength conversion crystal 6b and the synthesized frequency-generating wavelength conversion crystal 7b increase the overlap of their phase matching angle tolerance. Here, it is known that the phase matching angle of the wavelength conversion crystal changes with the temperature of the crystal. However, generally, the method of changing the angle between the second harmonic generation wavelength conversion crystal 6b and the synthesized frequency generation wavelength conversion crystal 7b is different (the direction of the phase matching angle change, and the magnitude of the change); therefore, when When the configuration shown in Fig. 12 is used to construct a high output power synthesis frequency generating laser device, the temperature change caused by the high average output power will occur on the wavelength conversion element 12, resulting in the second harmonic generation wavelength conversion crystal 6a and Variations in different amplitudes and different directions between the synthesized frequency generating wavelength conversion crystals 7b will cause the phase matching angle to change. In order to provide an appropriate phase matching procedure even in this case, the tolerance of the phase matching angle must be widened to a level that will not cause problems in practical applications. As illustrated in Figure 12, in this embodiment, since the length of the second harmonic generation wavelength conversion crystal 6b is set to be shorter than the length of the synthetic frequency wavelength conversion crystal 7b, the second harmonic generation wavelength can be converted The phase matching angle tolerance of the crystal is set relatively wide, so the wavelength conversion element 12 can be easily manufactured. Furthermore, it is possible to construct a device that has sufficient tolerance for the change of the phase matching angle, where the change is due to the temperature change caused by the high-output laser light rate.

<u>Example 12</u>

Figure 13 is a diagram showing the structure of Embodiment 12 of the present invention. Here, in order to replace the mirrors 4 and 5 in the first figure, a laser beam splitting optical element 5b that disperses the wavelength by refraction is adopted, and by using the laser beam splitting element, it can be implemented as The separation of the fundamental wave of the synthetic frequency laser beam, the second harmonic laser beam (2ω in Figure 13) and the third harmonic laser beam (3ω in Figure 13). In this configuration, the same operation as in Figure 1 can be achieved, and a stable laser device with high reproducibility can be provided.

<u>Example 13</u>

Figure 14 is a diagram showing the structure of Embodiment 13 of the present invention. In Fig. 14, reference numeral 17 is a laser processing device composed of any of the wavelength conversion laser devices shown in Figs. 1, 10, 11, 12 and 13. Reference numeral 13 is a laser beam refracting mirror, 14 is a laser beam shaping and polymerizing element such as a lens, 15 is a laser beam used for processing, and 16 is a processing object.

In the laser processing device with the configuration shown in Figure 14, the laser beam generated by any one of the wavelength conversion lasers 17 shown in Figures 1, 10, 11, 12 and 13 is produced by the refracting mirror 13. The split shot is shaped and focused by the element 14 and incident on the processed object 16 for processing.

In the laser processing device with the structure shown in Fig. 14, any of the wavelength conversion lasers 17 with high reproducibility shown in Figs. 1, 10, 11, 12 and 13 are used to stably generate laser beams. , So a stable processing program with high reproducibility can be realized. Moreover, when any of the components of the wavelength conversion laser 17 (optical parts such as semiconductor lasers and bulbs in pressurized light sources, wavelength conversion crystals, and reflectors) are damaged and need to be replaced, this configuration can be easily achieved And the adjustment of the optical system and the resonator can be completed in a very short time; therefore, the laser device can be easily restored to the state before the repair and the same operating conditions as before the repair can be used to produce the processing before the repair. In this way, the laser processing device using any of the wavelength conversion laser devices 17 shown in Figures 1, 10, 11, 12, and 13 has superior stability and can provide high-reproducibility processing.

The present invention having the above configuration exhibits the following effects.

According to the first item of the patent application of the present invention, the laser device has a second harmonic generation wavelength conversion crystal and a synthetic frequency wavelength generation wavelength conversion crystal placed in a laser resonator containing a solid laser active medium. The wavelength conversion laser device on the optical axis sets the length of the second harmonic generation wavelength conversion crystal on the optical axis to be shorter than the length of the synthetic frequency generation wavelength conversion crystal on the optical axis; therefore, it can The output power characteristic of the composite frequency laser beam determined by the second harmonic generation wavelength conversion crystal angle is simplified, and therefore, a wavelength conversion laser device with high reproducibility and easy manipulation can be constructed.

The laser device according to the second item of the scope of patent application, which is the same as the laser device of the first item in the scope of patent application, is designed so that the synthesized frequency generation wavelength conversion crystal can be used as the wavelength conversion crystal for generating the third-harmonic laser beam; Therefore, it can simplify the output power characteristics of the third harmonic laser beam determined by the second harmonic generation wavelength conversion crystal angle, and thus can construct a wavelength conversion laser device with high reproducibility and easy manipulation.

The laser device according to item 3 of the scope of patent application is the same as the wavelength conversion laser device of item 1 in the scope of patent application. Its design makes the synthetic frequency generating wavelength conversion element made of multiple wavelength conversion crystals; therefore, It can simplify the output power characteristics of the composite frequency laser beam determined by the second harmonic generation wavelength conversion crystal angle, and therefore can construct a wavelength conversion laser device with high reproducibility and easy manipulation.

According to the laser device of item 4 of the scope of patent application, it is the same as the wavelength conversion laser device of item 3 of the scope of patent application. Subharmonic laser beam; therefore, it can simplify the output power characteristics of the fourth harmonic beam determined by the second harmonic generation wavelength conversion crystal angle, and thus can construct a wavelength conversion with high reproducibility and easy manipulation Laser device.

The laser device according to item 5 of the scope of patent application is the same as the wavelength conversion laser device of item 1 in the scope of patent application. The wave generates the position between the wavelength conversion crystals, therefore, a stable device with high reproducibility can be provided.

Whats more, according to the laser device of item 6 of the scope of patent application, which is the same as the wavelength conversion laser device of item 1 of the scope of patent application, it is designed as a resonator. Therefore, the wavelength conversion efficiency becomes higher than that of continuous wave operation. In this case, it can also smooth and simplify the second harmonic output power determined by the wavelength conversion crystal angle and the fundamental wave power change in the resonator, so it can simplify the synthesis frequency laser beam output power to the second harmonic generation The dependence of the angle of the wavelength conversion crystal; therefore, it is possible to construct a wavelength conversion laser device that is easy to manipulate.

The laser device according to item 7 of the scope of patent application is the same as the wavelength conversion laser device of item 1 of the scope of patent application, and its design makes it possible to install at least one of the wavelength conversion crystals with an accuracy of not more than ±0.1 degrees. The mechanism of the angle; therefore, the processing of the wavelength conversion laser device can be easily performed, which traditionally makes this control difficult due to the complicated angle relationship.

The laser device according to item 8 of the scope of patent application is the same as the wavelength conversion laser device of item 1 of the scope of patent application, and its design makes it possible to install at least one of the wavelength conversion crystals with an accuracy of not more than ±0.5 degrees. Temperature mechanism; therefore, the processing of the wavelength conversion laser device can be easily performed, which traditionally requires the temperature control of the wavelength conversion crystal and the complicated angle relationship of the wavelength conversion crystal makes this control difficult.

According to the laser device of item 9 of the scope of patent application, it is the same as the wavelength conversion laser device of item 1 of the scope of patent application. Its design enables the polarization control element to be placed in the laser resonator, therefore, stable wavelength conversion can be achieved The laser device is improved to have high reproducibility and high efficiency, so that it can have higher reproducibility and easier operation.

The laser device according to the tenth item of the patent application is the same as the wavelength conversion laser device of the first item of the patent application, and it is designed to use Nd: YAG or Nd: YLF or Nd: YVO₄As a solid active medium; therefore, the stable wavelength conversion laser device can be improved to have high reproducibility, high efficiency and short pulse width, so that it can have higher reproducibility and easier operation.

According to the laser device of the 11th patent application, it is the same as the wavelength conversion laser device of the 1st patent application, and it is designed to use at least LBO (LiB₃O₅) The crystal is used as one of the second harmonic generation conversion crystal or the synthesized frequency generation wavelength conversion crystal; therefore, the stable wavelength conversion laser device can be improved to have high reproducibility and high generation efficiency, so that it can have a higher High reproducibility and easy operation.

According to the laser device of item 12 of the scope of patent application, which is the same as the wavelength conversion laser device of item 1 of the scope of patent application, it is designed to synthesize the frequency conversion laser beam with an average output power of not less than 1W. In this device, even if the phase matching angle is deviated due to thermal deformation, damage to the optical element and temperature change in the wavelength conversion crystal, the second harmonic generation wavelength conversion crystal is short and the phase The matching angle tolerance is wide, so it is possible to construct an easy-to-operate and stable wavelength conversion laser device with high reproducibility and high generation efficiency even when the average output power is high.

According to the laser device of item 13 of the scope of patent application, which is the same as the wavelength conversion laser device of item 1 of the scope of patent application, it is designed to integrate the second harmonic generation wavelength conversion crystal and the synthetic frequency generation wavelength conversion crystal It is a wavelength conversion element so that the temperature or angle of the second harmonic generation wavelength conversion crystal and the synthesized frequency wavelength conversion crystal can be changed as a whole. In this device, even if the second harmonic generation wavelength conversion crystal and the synthetic frequency generation wavelength conversion crystal are formed in one piece, even if the wavelength conversion crystal has a different phase matching angle tolerance caused by temperature changes, the second harmonic generation wavelength conversion crystal is integrally formed. When the wave-generating wavelength conversion crystal and the synthetic frequency-generating wavelength conversion crystal are subjected to temperature changes, their configuration can allow the phase matching angle tolerance of the two crystals to overlap to a level that will not cause problems in actual use; therefore, It constitutes a stable laser device.

The processing device according to item 14 of the scope of patent application is a laser processing device that uses the wavelength conversion laser beam generated by the wavelength conversion laser device disclosed in item 1 of the scope of patent application as a light source for processing objects; therefore; , It can provide a cheap processing device that can be stable for a long time, perform processing with high reproducibility and high precision, and this device is also easy to maintain.

<p>1, 9 Laser resonator mirror</p><p>2 Polarizer</p><p>2ω, 3ω, 15 laser beam</p><p>3, 3a, 3b solid active medium</p><p>4, 4a, 5, 5a mirror</p><p>5b Laser beam splitting optics</p><p>6, 6a, 6b, 6c, 7, 7a, 7b, 7c, 10 crystal</p><p>8 Q value switching device</p><p>11 90° polarized light slewing device</p><p>12 Wavelength conversion element</p><p>13 Refracting mirror</p><p>14 Laser shaping and polymerizing components</p><p>16 Processing objects</p><p>17 Wavelength conversion laser</p><p>18 Reflector</p><p>20 Laser oscillation optical axis</p>

Figure 1 shows the configuration of the wavelength conversion laser device according to Embodiments 1 to 8 of the present invention.

Figure 2 is a schematic diagram showing the relationship between the average output power of the second harmonic laser beam and the angle of the wavelength conversion body crystal when the frequency conversion crystal is placed outside the resonator and the frequency is converted outside the resonator.

Figure 3 is a schematic diagram showing the relationship between the output power of the second harmonic laser beam and the crystal angle when the frequency conversion crystal is placed inside the resonator and the frequency is converted in the resonator.

Figure 4 is a schematic diagram showing the relationship between the average output power of the composite frequency laser beam and the crystal angle generated by the second harmonic generation wavelength conversion crystal and the composite frequency generation wavelength conversion crystal placed in the laser resonator .

Figure 5 is a schematic diagram showing the relationship between the average output power of the second harmonic laser beam and the crystal angle when a long second harmonic generation frequency conversion crystal is used.

Figure 6 is a schematic diagram showing the relationship between the power of the second harmonic laser beam and the crystal angle when a short second harmonic generation frequency conversion crystal is used.

Figure 7 is a schematic diagram showing the relationship between the average output power of the synthesized frequency laser beam and the crystal angle when a long second harmonic generation wavelength conversion crystal is used.

Figure 8 is a schematic diagram showing the relationship between the average output power of the synthesized frequency laser beam and the crystal angle when a short second harmonic generation wavelength conversion crystal is used.

Figure 9 is a simplified diagram showing the power change of the laser beam of the synthesized frequency according to the length of the second harmonic generation wavelength conversion crystal.

Fig. 10 is a configuration diagram of Embodiment 9 according to the present invention.

Fig. 11 is a configuration diagram of Embodiment 10 according to the present invention.

Fig. 12 is a configuration diagram of Embodiment 11 according to the present invention.

Fig. 13 is a configuration diagram of Embodiment 12 according to the present invention.

Fig. 14 is a configuration diagram of Embodiment 13 according to the present invention.

Figure 15 shows the configuration of a conventional wavelength conversion laser device.