JP2849032B2 - Laser device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention, for example, relates to a laser device such as a solid-state laser apparatus, more particularly, relates to laser equipment which generates a good laser beam quality at high power.

[0002]

2. Description of the Related Art FIG. 29 is, for example, “Laser Handbook” (published by Ohmsha), edited by The Laser Society of Japan, p. FIG. 2 is a cross-sectional configuration diagram showing a conventional solid-state laser device shown at 222.
In this figure, 1 is a total reflection mirror, 2 is a partial reflection mirror, 3 is a solid state element including an active solid medium, and Nd (Neodymium) is used as an active solid medium in the case of a yag laser.
Doped Nd: YAG (Yttrium Aluminum Ga)
rnet) is a laser medium, and 4 is a light source, for example, an arc lamp is applied. Reference numeral 5 denotes a power source for turning on the light source 4, and reference numeral 6 denotes a light collector of the light source 4, which has, for example, an elliptical cross section and an inner surface formed of a light reflecting surface. 7 is a laser beam generated in a laser resonator constituted by mirrors 1 and 2, 70 is a laser beam taken out,
100 is a base.

Next, the operation will be described. The light source 4 and the solid state element 3 are arranged in a light collector 6, and light emitted from the light source 4 is incident on the solid state element 3 in a condensed state. As a result, the active solid medium is excited by the solid-state element 3, and excitation light having a predetermined wavelength is generated. And this solid state device 3
The laser beam 7 generated from the laser medium consisting of
The laser beam is amplified during reciprocation between the laser resonators constituted by the mirrors 1 and 2 and, when reaching a predetermined value or more, becomes a laser beam 70 having good directivity from the partial reflection mirror 2 to the outside of the laser resonator. Released.

In the conventional laser apparatus as described above, when the amount of light incident on the solid state element 3 exceeds an allowable value, the solid state element 3
Destroys. For example, when the Nd: YAG solid state element 3 is used, in order to stably obtain a laser output without destroying the solid state element 3, the length 25.
It is empirically known that it is necessary to suppress the input power to the light source 4 to about 3 kW with an oscillation efficiency of 5% per 4 mm. Therefore, when increasing the input power to the light source 4 to increase the laser output, it is necessary to lengthen the solid-state element 3. For example, to obtain a laser output of 1.5 kW, it is necessary to supply 30 kW of power to the light source 4 with an oscillation efficiency of 5%. In this case, the solid-state element 3 having a length of 254 mm is required to perform a stable operation with an input power of 30 kW.

However, solid-state devices 3 such as Nd: YAG are difficult to grow crystals, and particularly long ones are difficult to produce industrially. For example, a solid element 3 of 20 cm or more
Is extremely difficult to obtain at present, and even if it is available, it is very expensive, so that the solid-state laser device becomes expensive. Further, the quality was not stable in the longitudinal direction, and a high-quality laser beam could not be obtained.

Therefore, in order to obtain a high-output laser beam of, for example, 1.5 kW, it is necessary to use a plurality of inexpensive short solid-state elements 3. As this method, a method using a plurality of solid-state device excitation portions 3A as shown in FIG. 30 and a method shown in FIG.
There is known a method of inserting a plurality of solid state elements 3 into one light collector 6.

On the other hand, FIG. 32 shows a wavelength converted from a laser beam from the photoexcited portion 3A into a harmonic including the second harmonic 8 in a laser resonator and extracted as a high-power laser beam. A laser device including a converter 10 is shown. Such as an apparatus, for example a laser device to which <br/> apply multiple wavelength conversion element described in Japanese Patent Laid-Open No. 2-7487 is known. Wavelength conversion element length in this laser device is different for example KTP (Potassiu
m Titanyl Phosphorate), and is formed on a base 110 so as to be adjustable in angle. The base 110 has nonlinear optical crystals 40a and 43a.
Is provided with a temperature control mechanism such as a heating device capable of controlling the temperature of each.

[0008]

Since the conventional photo-excitation solid-state laser device is constructed as described above, as shown in the above-described device of FIG. 30, the height of the laser beam is increased by using a plurality of photo-excitation portions 3A. When the output is achieved, it is difficult to adjust the solid state elements 3 coaxially, and it is also difficult to stably maintain the solid state elements 3 in the adjusted state for a long time.

Further, as shown in the apparatus of FIG. 31, when a plurality of solid-state elements 3 are arranged in parallel to increase the output of a laser beam,
It is difficult to adjust each solid state element 3 coaxially,
Further, a plurality of return optical systems 11 are required, so that the solid-state laser device is complicated, and further, there is a problem that adjustment of the return optical system 11 is difficult.

Further, in the apparatus shown in FIGS. 30 and 31, each solid element 3 is supported by a through hole formed on both walls of the light collector 6, so that the number of through holes is equal to the number of solid elements 3. Is required twice as many times. Therefore, there is a problem in that light leaking from these through holes is lost and the oscillation efficiency is reduced.

On the other hand, in the apparatus including the wavelength converter shown in FIG. 32, when a plurality of nonlinear optical crystals are actually arranged and tested as wavelength converting elements, a long nonlinear optical crystal having the same length is equivalently used. The generation efficiency of the wavelength-converted laser beam is lower than in the case. In extreme cases, the generation of the wavelength-converted laser beam may not occur. The use of a plurality of nonlinear optical crystals increases the number of end faces, but when performing high-power wavelength conversion, there is a problem in that these end faces are attached to dust and destroy the end faces. Further, there is a problem that the wavelength conversion laser beam generated from the wavelength converter heats the laser medium, for example, the solid-state element 3, and the laser output becomes unstable.

[0012] This invention has been made to solve the above problems, is easy optical adjustment of each other while using a plurality of solid state devices, also not necessary to use a complicated optical system, An object of the present invention is to provide a solid-state laser device capable of stably increasing the output power. To provide a laser device that can oscillate by guiding the laser beam to a solid-state element.

[0013]

According to a first aspect of the present invention, there is provided a laser apparatus in which light emitted from a light source is partially reflected at an inner surface.
Formed with a diffuse reflective surface that reflects so that it does not concentrate on
Including the concentrator, the laser medium has two ends facing each other
Are connected by a sleeve-shaped connecting member that can be inserted coaxially
It is installed in the light collector in a state where
The laser optical system is accessed through a through hole formed in the condenser.
The laser beam excited by the light projected from the light source.
It consists of a plurality of solid-state elements
Between the opposing ends of the solid state elements in the binding member, a wave plate or
Is provided with an optical rotation plate.

According to a second aspect of the present invention, in the laser device, the connecting member is constituted by a light reflecting member, or the connecting member is provided with a light reflecting member for reflecting the light projected from the light source on the surface of the connecting member. Things.

[0015]

According to the first aspect of the present invention, the laser device reflects the light obtained by turning on the light source in the light collector, and converts the light generated from the light source to the solid-state element connected in the light collector. Absorb efficiently. As a result, the plurality of solid-state elements are excited, and excitation light is generated from both ends. Light generated from this laser medium is extracted as a laser beam having good directivity via a laser resonator. Also, expand the inner surface of the light collector.
It is formed by a diffuse reflection surface, and the light from the light source is
The light is diffusely reflected and uniformly guided to the surfaces of the connected solid-state devices.
Insert the end of the solid state element inside the sleeve-shaped connecting member.
To connect multiple solid state devices and coaxially connect multiple solid state devices.
Connects stably without any axial deviation. In addition, in the connecting member
Polarization plate in one solid-state device
The direction is twisted with the polarization direction in the other solid state device
To eliminate polarization anisotropy generated in solid state devices
You.

In the laser apparatus according to the second aspect of the present invention, the connecting member is formed of a light reflecting member, or a light reflecting member from a light source is provided on the surface thereof, and the light from the light source is reflected by the connecting member to collect light again. After being reflected several times in the optical device, the light is incident on the solid state element to excite the solid state element.

[0017]

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG.
FIG. 3 is a sectional view showing a first embodiment of the present invention, and the same reference numerals are given to the corresponding portions in FIGS. In FIG. 1, reference numeral 61 denotes a connecting member formed of a material that reflects the light from the light source 4, for example, white ceramic.
3 is formed of a sleeve-like member capable of coaxially connecting the opposing ends thereof. The solid-state elements 3 and 3 in this embodiment are easily available, for example, 150 m long.
m of Nd: YAG (neodymium-containing yttrium-aluminum-garnet) is applied. The solid-state elements 3 and 3 connected coaxially by the connecting member 61 are arranged such that both ends face the total reflection mirror 1 or the partial reflection mirror 2 through the through holes 81 of the light collector 6. ing. The light collector 6 of this embodiment has an inner surface formed of a reflector such as a white ceramic, for example, and forms a diffuse reflection surface in which reflected light does not concentrate on the solid-state elements 3 and 3.

Next, the operation will be described. First, when a switch (not shown) of the power supply 5 is turned on, the light source 4 is turned on. Light is projected from the light source 4 turned on by the power supply 5, and the projected light is guided to the solid state element 3 directly or indirectly after being reflected in the condenser 6. Part of the light guided to the solid state element 3 is absorbed by the solid state element 3 and
Is excited to generate excitation light. Spontaneous emission light generated from the laser medium is amplified while reciprocating between a resonator constituted by a total reflection mirror 1 and a partial reflection mirror 2, and when reaching a predetermined size or more, a laser beam having good directivity. It is released to the outside as 70.

As described above, the solid element 3 is made of a readily available Nd: YAG having a length of 150 mm, for example, and is a connecting member in which the two solid elements 3 and 3 are formed of a reflecting member such as white ceramic. At 61, they are connected coaxially. In this case, since the connecting member 61 reflects light, the length of the entire light-irradiated portion of the connected solid-state elements 3 and 3 is 2.
It will be set to about 80 mm. Therefore, 30
A laser output of 1 kW can be obtained with the light source 5 having a power of kW or less without destruction of the solid state elements 3 and 3. Further, as described above, by connecting the solid-state elements 3 and 3 in the light collector 6 using the connection member 61,
It is not necessary to increase the number of the through holes 80 and 81.

Incidentally, the inner wall of the condenser 6 used for laser excitation is set to have a high reflectance of about 99%.
Therefore, a part of the light emitted from the light source 4 is absorbed by the solid-state elements 3 and 3 while being repeatedly reflected in the condenser 6. The remaining light leaks to the outside through a through-hole 81 necessary for inserting the solid-state elements 3 and 3 into the light collector 6 and a through-hole 80 into which the light source 4 is inserted. 6 is absorbed by the reflecting surface.

In this case, since the solid-state elements 3 and 3 are connected in the condenser 6 without increasing the number of through holes 80 and 81,
The probability that the light emitted from the light source 4 leaks out of the light collector 6 before being absorbed by the solid state elements 3 is reduced. Therefore, the efficiency of excitation of the solid state devices 3 can be significantly improved.

Next, the pumping efficiency of the solid-state laser device of the first embodiment (see FIG. 1) and the conventional solid-state laser device (see FIG. 30) will be compared. The excitation efficiency is compared and calculated based on a basic formula derived by calculating the probability of collision of the light emitted from the light source 4 with the solid state element 3 in the light collector 6. The calculation results are shown in FIGS. 2 (a) and 2 (b). FIG. 2A shows the pumping efficiency of the solid-state laser device according to the first embodiment, and FIG. 2B shows the pumping efficiency of the conventional solid-state laser device.

As is clear from FIGS. 2A and 2B,
It can be seen that the excitation efficiency of the solid-state laser device of Example 1 is about twice as high as that of the conventional solid-state laser device.
That is, by making the through hole of the first embodiment half of the conventional through hole, the excitation efficiency can be approximately doubled.

FIGS. 3A and 3B are graphs showing laser oscillation characteristics. FIG. 3A shows the laser oscillation characteristics of the solid-state laser device of the first embodiment, and FIG. 3B shows the laser oscillation characteristics of the conventional solid-state laser device. As is clear from FIGS. 3A and 3B, the laser oscillation efficiency of the first embodiment is about twice the conventional laser oscillation efficiency.
That is, according to the solid-state laser device of the first embodiment, a laser output of 1 kW can be obtained with a small input power.

Embodiment 2 FIG. FIG. 4 is a sectional view showing a second embodiment of the present invention.
Between the solid-state element 3 and the partial reflection mirror 2 in the laser resonator, for example, a polarization selection element 90 made of a Brewster plate
Are provided, and the wavelength plate 91 (or the optical rotation plate) is provided in the connecting member 61. In addition, the solid-state device 3 in the present embodiment is a YLF (YLiF ₄ : lithium-yttrium-doped) doped with Nd as an active solid medium.
Fluoride) has been applied.

Next, the operation will be described. When the laser beam is incident, the polarization selection element 90 selects and emits linearly polarized light parallel to the plane of FIG. The wave plate 91 changes the direction of the incident elliptically polarized light by 90 °. Therefore, when the laser beam 7 reflected by the partial reflection mirror 2 enters the polarization selection element 90, the polarization selection element 9
From 0, linearly polarized light in a direction parallel to the plane of FIG. 4 is emitted. The emitted parallel linearly polarized light enters the solid-state element 3 on the right side in FIG. As a result, the parallel linearly polarized light is birefringent by the right solid state element 3 and the right solid state element 3
Is emitted as elliptically polarized light. The elliptically polarized light emitted from the solid-state element 3 on the right enters the wave plate 91, and the direction of the elliptically polarized light is changed by 90 degrees by the wave plate 91.
The light is incident on the left solid element 3 in the upper part.

The elliptically polarized light incident on the left solid state element 3 is:
The light is birefringent in the left solid element 3 and has the opposite sign to that when passing through the right solid element 3. As a result, the solid-state element 3 on the left side emits linearly polarized light whose polarization direction is perpendicular to the plane of FIG. The emitted vertical linearly polarized light is reflected by the total reflection mirror 1 and passes through the left solid element 3 and the right solid element 3 again, thereby being converted into linear polarized light parallel to the plane of FIG. . Then, the converted linearly polarized light passes through the polarization selection element 90 without loss. As described above, according to this embodiment, by using the polarization selection element 90 and the wave plate 91, it is possible to generate stable linearly polarized light without being affected by the birefringence of the left and right solid state elements 3, 3. Can be.

In this case, for example, 1
By providing the 波長 wavelength plate, linearly polarized light generated from the laser resonator is circularly polarized by the 波長 wavelength plate and laser processing without anisotropy can be performed.

In this embodiment, the solid-state device 3 has Nd: YL
When F is used, the birefringence of the solid state element 3 can be removed, and the thermal lens of the solid state element 3 can be removed. That is, the Nd: YLF solid state element generates a thermal lens having a different sign in a direction parallel to a direction perpendicular to the polarization direction. Thereby, the solid-state elements 3 and 3 described on FIG.
As in the case of the birefringence compensation effect of 3, the thermal lens generated in the solid state elements 3 and 3 while the polarized light component passes through the two solid state elements 3 and 3 is canceled out. Accordingly, the operation of the resonator is stabilized because the polarization component is not affected by the lens.

Embodiment 3 FIG. FIG. 5 is a sectional view showing a third embodiment of the present invention. The difference between this embodiment and the first and second embodiments is that a collimated total reflection mirror 21 is used instead of the total reflection mirror 1,
Further, an enlarged reflection mirror 20 is used instead of the partial reflection mirror 2.
This is the point that was used. When the unstable resonator of this embodiment is used, the generated laser beam 7 can have a substantially uniform intensity distribution over the entire cross-sectional area. Therefore, when a part of the laser beam 7 is absorbed by the solid-state element 3 in the high-power region and the solid-state element 3 is heated, the solid-state element 3 is uniformly heated. As a result, the laser beam 7 is
Can be prevented from being locally absorbed into the semiconductor device, thereby preventing the destruction of the solid state device. Further, since the laser beam 7 having this uniform intensity distribution has a uniform phase,
The ring-shaped laser beam 70 emitted to the outside can be focused on a focused spot close to the diffraction limit with some diffraction rings. Therefore, efficient laser processing can be realized using the laser beam 70.

Embodiment 4 FIG. FIG. 6 is a sectional view showing a fourth embodiment of the present invention. In place of the magnifying reflection mirror 20 of the third embodiment, the center is a partial reflection mirror 22 and the periphery is an enlarged non-reflection portion 23. An exit mirror 24 is used. Therefore, the resonator according to the present embodiment includes the enlarged exit mirror 24 and the collimated total reflection mirror 21. When the enlarged exit mirror 24 is used, a laser beam 70 having a good condensing property, which is converged in a spot-like shape almost in the middle of a diffraction limit, can be output from the laser resonator. Therefore, efficient laser processing can be realized using the laser beam 70. Further, as compared with the third embodiment, the intensity of the laser beam 7 required to obtain the same light collecting property can be reduced, and the heat generated by the solid state element 3 when the laser beam 7 is absorbed by the solid state element 3 Can be reduced. Therefore, since heat generation can be reduced, a high-quality laser beam 70 can be stably generated even in a high-power range.

Embodiment 5 FIG. FIG. 7 is a sectional view showing a fifth embodiment of the present invention, in which an enlarged exit mirror having a step 25 formed on the outer surface of the enlarged exit mirror 24 used in the fourth embodiment is used. As a result, the phase difference between the laser beam 7 passing through the partial reflection mirror section 22 and the laser beam 7 passing through the non-reflection section 23 is canceled out, so that a middle-packed laser beam 70 having the same phase can be obtained. . in this case,
The focusing property of the laser beam 70 is improved as compared with the fourth embodiment.

In the above-mentioned first to fifth embodiments, the solid elements 3 are connected to the sleeve-shaped connecting member 61 by inserting the ends thereof. However, the present invention is not limited to this. It may be bonded and connected to each other. Further, the wave plate 91 or the optical rotation plate shown in FIG. 4 may be configured to be bonded to the solid-state elements 3 and 3 with an optical adhesive.

In each of the above embodiments, the solid-state element 3 is described as having a circular cross section. However, the present invention is not limited to a circular cross section, and the solid element 3 may have any shape such as a rectangle or an ellipse. It has the same effect as.

Although not particularly described in any of the above embodiments, a non-reflective thin film is applied to a portion of the optical element which is not particularly indicated, and to a portion through which the laser beam 7 passes, thereby forming a resonator. To reduce the loss in
Efficient laser oscillation can be realized.

Although the number of the solid-state elements 3 has been described as being two, the number of the solid-state elements 3 is not limited to two and may be any number. By connecting many rods 3, higher output can be achieved. The connecting member 61 may be provided with a light-reflecting member on its surface, instead of being formed of a light-reflecting member as in the above embodiment.

Embodiment 6 FIG. FIG. 8 is a sectional view showing a sixth embodiment of the present invention. In this embodiment, a point different from the above-described first to fifth embodiments is that a plurality of wavelength conversion elements nonlinear optical crystals accommodated in a dust shielding container 62 are provided. In addition to the transmission mirrors 40 and 43, an optical thin film 191 that reflects the wavelength conversion component of the laser beam wavelength-converted by the wavelength conversion elements 40 and 43 is attached and the transmission mirror 190 is installed so that the angle can be adjusted. Is provided. The dust shielding container 62 includes an exhaust port 161, beam passing windows 62a, 62a,
1 and a filter 102, and the wavelength conversion elements 40 and 43 are provided with optical thin films 41, 42, 44 and 45 for adjusting the phase difference of the laser beam on both end surfaces. Further, the wavelength conversion element 4 of the present embodiment
Non-linear optical crystals of potassium phosphate titanate (hereinafter, referred to as KTP elements) having different lengths formed by different production methods, for example, a flux method and an aqueous solution method, are applied to 0, 43, respectively. Optical thin films 41, 4
2, 44 and 45 are, for example, a normal anti-reflection coat 421 applied to the end face of the wavelength conversion element as shown in FIG. 9 and a KT such as magnesium oxide (MgO).
And a base coat 422 formed by forming a thin film having a refractive index substantially equal to the refractive index of the P crystal to a predetermined thickness.

Next, the operation will be described. First, when a switch (not shown) of the power supply 5 is turned on, the light source 4 is turned on. When light is projected from the light source 4 turned on by the power supply 5, the projected light is guided to the solid-state element 3 directly or indirectly after being reflected in the condenser 6. Solid element 3
Is guided by the solid-state element 3 to excite the active medium of the solid-state element 3 to generate excitation light. Spontaneous emission light generated from the laser medium is reflected directly or by the total reflection mirror 1, and is transmitted by the transmission mirror 190 and the optical thin film 191.
Are transmitted to the wavelength conversion elements 40 and 43. The laser light incident on the wavelength conversion elements 40 and 43 is wavelength-converted into a laser beam including a fundamental wave component (fundamental laser beam) 7a and a wavelength conversion component (wavelength-converted laser beam 8a). Incident.

The partial reflection mirror 2 reflects the fundamental wave component 7a of the laser beam 7 and transmits and outputs the wavelength conversion component 8a. The reflected laser beam 7 is applied to the wavelength conversion element 4
The wavelength is converted again at 0 and 43, and the fundamental wave component therein passes through the transmission mirror 190 and the optical thin film 191 and is reflected again by the total reflection mirror 1 via the solid-state element 30. The reflected laser beam 7 passes through the transmission mirror 190 and the optical thin film 191 together with the laser beam 7 from the solid state element 30, undergoes wavelength conversion by the wavelength conversion elements 40 and 43, enters the partial reflection mirror 2, and performs wavelength conversion. Only the component 8a is transmitted and output. Hereinafter, the fundamental wave component 7a of the laser beam
Is amplified between the total reflection mirrors 1 and 2, further converted by the wavelength conversion elements 40 and 43, and output from the partial reflection mirror 2. The wavelength conversion component 8a is reflected and amplified between the partial reflection mirror 2, the transmission mirror 190, and the optical thin film 191, and is transmitted through the partial reflection mirror 2 and output.

In the above configuration, in order to perform efficient wavelength conversion, the wavelength of the fundamental laser beam 7a generated from the laser medium composed of the solid state element 3 and the wavelength-converted laser beam 8a are converted. Conversion elements 40, 4
It is necessary that the traveling speeds within 3, ie the phase velocities, coincide, and when that condition is met, phase matching is achieved. The phase matching in the solid-state element 3 is performed by using the birefringence of the solid-state element 3. The state of the birefringence depends on the incident angle of the laser beam 7 to the wavelength conversion elements 40 and 43 and the temperature of the crystal. Conversion elements 40, 43
In order to perform efficient wavelength conversion, the angle of the wavelength conversion elements 40 and 43 is generally changed by an angle adjuster,
This can be realized by finely adjusting the temperature of No. 10. Of course, the wavelength conversion elements 40 and 43 of the present embodiment are also provided so as to be adjustable in angle, and the base 110 is provided with a temperature adjustment mechanism.

Further, when the condition that the phase velocities match is satisfied, that is, when phase matching is achieved, the wavelength conversion efficiency is such that the wavelength conversion beams generated in the respective parts of the wavelength conversion elements 40 and 43 strengthen each other. Increases in proportion to the square of the length of the wavelength conversion crystal. Therefore, generally, wavelength conversion can be realized very efficiently by using a long wavelength conversion crystal. However, this wavelength conversion crystal is also difficult to grow as in the case of the solid-state element 3, and a large crystal cannot be obtained. For example, in the case of potassium phosphate titanate (hereinafter, referred to as KTP crystal) used in this embodiment, the maximum length of a crystal that can be used for laser oscillation is about 10 mm, and a longer crystal is more expensive. is there. Therefore, in this embodiment, a plurality of wavelength conversion elements (non-linear optical crystals) 40, 4
3 constitute a wavelength converter for obtaining a substantially long wavelength conversion length.

As a means for increasing the efficiency of wavelength conversion, it is conceivable to increase the intensity of the laser beam 7 incident on the wavelength conversion elements 40 and 43. For example, if the light is focused by a lens or pulsed, the wavelength conversion element 4
The intensity of the beam incident on 0,43 increases, and the wavelength conversion efficiency increases. However, in this case, the wavelength conversion elements 40, 4
Due to an increase in the intensity of the beam incident on the laser beam 3, the end face and the inside of the wavelength conversion element may be damaged by the strong laser beam 7, which is not preferable. In this embodiment, the laser beam 7 is transmitted through the transmission mirror 190. The intensity is softened and supplied to the plurality of wavelength conversion elements 40 and 43 to stabilize the wavelength conversion operation.

More specifically, the fundamental wave component 7a of the laser beam 7 is transmitted by the transmission mirror 190,
At 1, the wavelength conversion component 8a is totally reflected. When the selection mirror 190 and the optical thin film 191 are not provided, the wavelength-converted laser beam enters the solid-state element 3 and is absorbed by the solid-state element 3 to make the operation of the laser beam 7 unstable. In particular, when a plurality of wavelength conversion elements 40 and 43 are used to generate a high-output wavelength-converted laser beam, for example, 20 W or more, this instability becomes remarkable. In this embodiment, the transmission mirror 19 is used.
By adjusting the angle of 0, the efficiency of wavelength conversion can be increased.

That is, it is difficult to provide the transmission mirror 190 provided with the optical reflection thin film 191 with complete total transmittance, and therefore, some partial reflection occurs. The partially reflected laser beam 7 is applied to mirrors 1 and 2
And goes out of the resonator constituted by the above, resulting in a loss. When a plurality of wavelength conversion elements 40 and 43 are used, the laser beam 7 reflected by the optical thin film 191 also increases by the number of wavelength conversion elements 40 and 43, and the angle of the transmission mirror 190 is adjusted to adjust the transmission mirror 190. By satisfying the resonance condition between the mirror and the total reflection mirror 1 or between the end faces of the wavelength conversion elements 40 and 43 and the transmission mirror 190, the loss due to the optical thin film 191 is eliminated. Completely trapped in the vessel,
The intensity becomes strong and enters the wavelength conversion element 40 so that the wavelength conversion is efficiently performed.

Further, in this embodiment, the wavelength conversion element 4
Since the optical thin films 41, 42, 44, and 45 are provided on 0 and 43, the phase difference between the fundamental wave component 7a and the wavelength conversion component 8a of the laser beam 7 is canceled to realize more efficient phase matching. ing. For example, the KTP crystal applied to the wavelength conversion elements 40 and 43 of the present embodiment has a refractive index of 1.75, and Mg having almost the same refractive index as this.
The O thin film 422 has, for example, a refractive index of 1.7 for a fundamental wave of an Nd: YAG laser and a refractive index of 1.78 for a wavelength conversion component. Therefore, a phase difference of 0.05 wavelength is generated per micron in thickness. In addition, the laser beam 7 caused by the difference in the refractive index of the atmosphere between the wavelength conversion elements 40 and 43.
Assuming that the phase difference between the fundamental wave component 7a and the wavelength conversion component 8a is 0.5 wavelength, the thickness of the MgO thin film 422 is adjusted to 10 microns so that the gap between the wavelength conversion elements 40 and 43 is adjusted. Fundamental component 7a of laser beam 7 at
Phase difference between the wavelength and the wavelength conversion component 8a can be removed. As a result, the fundamental wave component 7a and the wavelength conversion component 8a in the wavelength-converted laser beam 7 act to reinforce each other, so that the wavelength conversion efficiency can be further increased.

That is, the optical thin film 41 for adjusting the phase difference,
In a conventional wavelength converter in which a plurality of wavelength conversion elements not subjected to 42, 44, and 45 are arranged (for example, the example of FIG. 32), the efficiency of wavelength conversion decreases as expected with each increase in the number of crystals. . The reason is that the refractive index of the atmosphere between the wavelength conversion elements is caused by the fundamental wave component 7a of the laser beam 7 and the wavelength conversion component 8
a, a phase difference occurs between the laser beam 7 wavelength-converted by one wavelength conversion element and the laser beam 7 wavelength-converted by the next wavelength conversion element,
They had canceled each other. When only the non-reflection coat 421 is applied to the wavelength conversion element, the refractive index of the film of the non-reflection coat differs between the fundamental wave component 7a and the wavelength conversion component 8a of the laser beam 7, and the wavelength conversion is performed in the same manner as described above. The laser beams thus canceled each other.

In this case, FIG.
In Japanese Patent No. 487, the angles of the wavelength conversion elements 40 and 43 are adjusted such that the polarization directions of the laser beams 7 generated from the two wavelength conversion elements 40 and 43 are orthogonal to each other. In addition, the wavelength conversion elements 40 and 43 become extremely sensitive to temperature conversion, and the operation is not stable, which is not preferable. Further, in this case, the laser beams 7 generated from the two wavelength conversion elements 40 and 43 do not cancel each other, but do not strengthen each other. Therefore, in this case, the wavelength-converted laser beam increases in proportion to the first power of the crystal length, not the square of the crystal length, and the wavelength conversion length is increased by using a plurality of wavelength conversion elements. The effect is not fully exhibited.

Therefore, in this embodiment, as described above, KTP
Base coat 4 of MgO thin film whose refractive index is almost equal to that of crystal
Reference numeral 22 denotes a laser beam between the wavelength conversion elements 40 and 43.
The phase difference is adjusted by making the thickness such that the phase difference is canceled out. In this case, in the present embodiment, the direction of each laser beam 7, that is, each wavelength conversion element 40, 4
Optical thin films 41, 42, 44 and 45 are provided on both end surfaces of the laser beam 3 to adjust the phase difference of the laser beam 7 in each direction. However, in the present invention, any one of them may be provided with an optical thin film for phase adjustment. The point is that the phase difference between the fundamental wave component 7a and the wavelength conversion component 8a of the laser beam 7 when passing through the wavelength conversion elements 40 and 43 including the optical thin film on the end face is canceled out, that is, an integer multiple of those wavelengths is used. The phase may be compensated. Therefore,
In this embodiment, the shape and composition of the wavelength conversion elements 40 and 43, that is, the lengths of the wavelength conversion elements 40 and 43 are changed, and a KTP crystal is produced by a different manufacturing method.

That is, in this embodiment, non-linear optical crystals 40 and 43 having slightly different compositions are formed by different manufacturing methods of the flux method and the water-soluble method, and therefore, between the fundamental wave component 7a of the laser beam 7 and the wavelength conversion component 8a. The magnitude and the direction of the error angle in the traveling direction called the walk-off angle generated by the phase difference between the wavelength conversion elements differ. Since this difference is a phase difference between the wavelength conversion element beams,
The wavelength conversion elements 40 and 43 manufactured by the two manufacturing methods are combined to cancel out the phase difference, or cancel out the phase difference by making it an integral multiple of the wavelength.

Further, the shape of the wavelength conversion elements 40 and 43 also has a difference in phase difference depending on the length.
The configuration is such that nonlinear optical crystals of different lengths are combined to effectively cancel the phase difference. Further, the optical thin film 4
The phase difference also differs depending on the configuration of 1, 42, 44, 45. That is, antireflection coatings 421 are provided on both end surfaces of the wavelength conversion elements 40 and 43, respectively. The configuration of the anti-reflection coating film 421 is innumerable combinations depending on the thin film material to be used and the thickness of the thin film, and each gives a different phase difference between the fundamental wave component 7a and the wavelength conversion component 8a of the laser beam 7 passing therethrough. . Therefore, at least one thin film configuration is made different from the others to cancel the phase difference.

That is, the composition of the wavelength conversion elements 40 and 43,
Each of the wavelength conversion elements is formed by configuring at least one of the shapes, or by configuring the thin film configuration of the anti-reflection coat 421 of the optical thin film to be different from at least one place, and further adjusting the phase difference by the base coat 422. , By canceling the phase difference between the fundamental wave component 7a and the wavelength conversion component 8a of the laser beam 7 passing through 40 and 43, or by making the wavelength an integral multiple of the wavelength, the laser beams 7 that have passed through each other strengthen each other to achieve efficient wavelength conversion. It can be performed.

On the other hand, in this embodiment, the wavelength conversion elements 40, 4
Since 3 is housed in the dust shielding container 62, the efficiency of wavelength conversion can be further increased. That is, when dusts float near the end faces of the wavelength conversion elements 40 and 43, the dusts are heated and burned by the laser beam 7, and a propulsive force is given by the reaction of the dusts. , The end face is destroyed, the efficiency of wavelength conversion is reduced, and in extreme cases, oscillation is stopped. This is particularly noticeable when a high-power wavelength-converted laser beam is obtained using a plurality of wavelength conversion elements. This is because the number of end faces of the wavelength conversion element has increased due to the use of a plurality of wavelength conversion elements, and the probability of dust colliding with the end faces has increased, in addition to the increased output and the increased probability of burning dust. It is. Further, it is expected that the wavelength-converted laser beam is generally visible light and has a high absorptivity to dust.

In this embodiment, the wavelength conversion elements 40 and 43 are covered with the dust shielding container 62 and the outside air is
1, the dust contained in the outside air is removed by the dust filter 102, and the clean atmosphere is led to the vicinity of the wavelength conversion elements 40 and 43. As a result,
In the present embodiment, a laser device for converting the wavelength of the laser beam 7 from the Nd: YAG solid-state element 3 by the wavelength conversion elements 40 and 43 of the KTP crystal is the world's highest value of 20 at present.
A laser output of W or more can be obtained stably.

In this embodiment, the case where the base thin film 422 for phase adjustment is applied to the wavelength conversion elements 40 and 43 has been described as an example. However, for example, as shown in FIG. The component 46, for example, sapphire may be independently provided between the wavelength conversion elements 40 and 43. In this case, the phase difference between the fundamental wave component 7a of the laser beam 7 and the wavelength conversion component 8a can be easily canceled without changing the configuration of the wavelength conversion elements 40 and 43.

In this embodiment, the transmission mirror 19 is used.
Although the optical thin film 191 for reflection is formed on one end face of the wavelength conversion element 40, the optical thin film 191 may be attached to the end face of the wavelength conversion element 40 instead of the optical thin film 41.

Further, in this embodiment, the case where only the wavelength conversion elements 40 and 43 are accommodated in the dust shielding container 62 has been described as an example, but other optical systems including the solid state element 3 and the mirrors 1 and 2 are used. You may comprise so that it may be accommodated in the dust shielding container 62 which covers. When the apparatus is installed in an atmosphere with a lot of dust, for example, an inert gas such as N2 (nitrogen) or Ar (argon) may be introduced into the dust shielding container 62. In this case, the fan 101 and the filter 10
2 can also be removed. Further, the container may be hermetically closed by removing the exhaust port 161. In this case, the inside of the container may be evacuated.

Embodiment 7 FIG. FIG. 11 is a sectional view showing a seventh embodiment of the present invention.
The present embodiment is different from the sixth embodiment in that a transmissive body 301 that completely transmits the laser beam 7 is provided in each space through which the laser beam 7 passes. These transmitting members 301 are formed of, for example, sapphire, BK-7, quartz, YAG that does not include an active element, and each of the transmitting elements 301 is designed to minimize the space exposed to the atmosphere between the optical elements. Are formed between the optical elements (1) and (2) to form dust adhesion preventing means for preventing damage caused by dust adhering to the end faces of the wavelength conversion elements 40 and 43 and the solid element 3 which are particularly easily damaged.

Next, the operation will be described. Each of the transmission members 301 is much more resistant to light irradiation than the solid-state elements 3 such as Nd: YAG or Nd: YLF doped with an active medium serving as a laser medium or the wavelength conversion elements 40 and 43 such as KTP crystals. It is strong, and damage due to dust attached to the end face does not pose a practical problem. Moreover, the transmitting body 301 can prevent the laser beam 7 having a high intensity from heating the atmosphere on the optical path, thereby preventing the atmosphere from fluctuating, which can fluctuate the optical axis of the laser beam 7 and become unstable. In the present embodiment, the laser beam 7 is stabilized by preventing the fluctuation of the optical axis, so that the efficiency of wavelength conversion is further improved. That is, as described in the sixth embodiment, when the angle of the laser beam 7 incident on the wavelength conversion elements 40 and 43 falls within a certain range, the efficiency of wavelength conversion becomes maximum when so-called phase matching is performed. Become. Therefore, when the optical axis fluctuates and the angle of incidence on the wavelength conversion elements 40 and 43 fluctuates, the output of the wavelength conversion laser beam also fluctuates, and the time-averaged output of the wavelength conversion laser beam decreases.

Therefore, in this embodiment, the transmitting member 30 is placed on the optical path.
1 is arranged, the laser beam 7
And the heat generated at that time is released to the outside to prevent convection due to heating of the atmosphere. Also,
The light absorbed by some of the transmissive bodies 301 also
, The heat is slowly transmitted to a base or the like and dissipated by the small thermal conductivity of the permeable body 301. For example, when the transmitting body 301 is formed of sapphire glass or the like, at a length of 100 mm, about 1 W of a passing laser beam of 1 kW is absorbed, but the heat is sufficiently dissipated even when the side surface is in contact with the atmosphere. Amount.

Furthermore, in addition to the heat generated by the generated laser beam 7, the fluctuation of the atmosphere due to the light of the light source 4 can be prevented. Light from the light source 4 is confined in the condenser 6 and a part of the laser beam 7 is absorbed by the solid state element 3, but the unabsorbed laser beam 7 is emitted from the end face of the solid state element 3 and the atmosphere in the holder 300 is removed. Heat and shake this. In the present embodiment, this can be easily removed by the transmitting body 301 inserted into the holder 300. In particular, when the inner surface of the condenser 6 is made of a ceramic or white resin diffuse reflector having a high reflectance, the light is
The light component which is not diffused into the solid-state element 3 is diffused in a wide range within the light-collecting element 6, and after traveling many times in the concentrator 6, most of the light component is transmitted from the end face through the solid-state element 3 as light of high intensity. Will be emitted. In this case,
The heat dissipation effect of the transmitting body 301 inserted into the holder 300 is particularly remarkable.

In this embodiment, the light from the light source 4 generated from the end face of the solid-state element 3 is transmitted through the transmitting body 301. However, as shown in FIG. The end face of the solid-state element 3 is transparent to the fundamental laser beam 7a so that no light is emitted.
May be applied to the wavelength-selective thin film 49 having reflectivity to the light.

In this embodiment, the wavelength conversion elements 40, 4
Although the description has been given by taking the laser device including the third example as an example, the transmission body 301 and the wavelength selection thin film 49 may be applied to the first to fifth embodiments. That is, it goes without saying that the present invention can be applied to a laser device that generates a laser beam having a high intensity, and the effect can be exhibited.

In the embodiment shown in FIG. 11, the structure in which the transmitting body 301 is arranged between almost all the transparent parts of the optical component is shown. However, it is needless to say that it is not necessary to arrange the transmitting part 301 in all places depending on the structure of the resonator.

Embodiment 8 FIG. FIG. 13 is a sectional view showing an eighth embodiment of the present invention.
This embodiment is different from the sixth and seventh embodiments in that the laser generator 3a and the wavelength converter 40a face each other at a predetermined angle via the reflection mirror 200. The reflection mirror 200 is a laser generating unit 3a.
An optical thin film 191 that totally transmits the wavelength-converted component 8a of the wavelength-converted laser beam 7 from the wavelength converter 40a is applied to the total reflection mirror 1 that performs total reflection with respect to the fundamental laser beam 7a. It has been formed. Also,
The total reflection mirror 1 is provided to face the return reflection mirror 200 via the wavelength converter 40a.

Therefore, according to the present embodiment, the high-output wavelength conversion component 8a that has been wavelength-converted by the wavelength conversion section 40a.
Does not return to the laser generator 3a,
Of the solid state element 3 can be effectively prevented. As a result, in this embodiment, it is possible to omit the transmission mirror 190 provided with the optical thin film 191 used in the above embodiment, and to prevent the loss of the wavelength-converted laser beam 7 due to this. .

Embodiment 8 FIG. FIG. 13 is a sectional view showing an eighth embodiment of the present invention.
This embodiment is different from the above-described embodiment in that the laser generator 3a and the wavelength converter 40a face each other at a predetermined angle via the reflection mirror 200. The return reflection mirror 200 is used for the total reflection mirror 1 that totally reflects the fundamental laser beam 7a from the laser generation unit 3a, and for the wavelength conversion component 8a of the wavelength-converted laser beam 7 from the wavelength conversion unit 40a. The optical thin films 41, 42, 44, and 45, which are totally transparent, are formed. Further, the total reflection mirror 1 is provided to face the return reflection mirror 200 via the wavelength conversion unit 40a.

Therefore, according to the present embodiment, the high-power wavelength conversion component 8a that has been wavelength-converted by the wavelength conversion section 40a.
Does not return to the laser generator 3a,
Of the solid state element 3 can be effectively prevented. As a result, in this embodiment, it is possible to omit the transmission mirror 190 provided with the optical thin film 191 used in the above embodiment, and to prevent the loss of the wavelength-converted laser beam 7 due to this. .

Embodiment 9 FIG. FIG. 14 is a flow chart showing a ninth embodiment of the present invention, in particular, an embodiment of a laser pattern analyzing method according to the twenty-seventh aspect. For example, in the laser device using the folded resonator shown in FIG. 13, the beam pattern of the laser beam 7 may not be axially symmetric, and in such a case, the inventors of the present invention use computer simulation. Analyzed the laser device with a unique laser pattern analysis method to solve the beam deformation. This beam pattern analysis method basically calculates independent polarization components, for example, orthogonal S-waves and P-waves independently. If there is an optical component having energy transfer between S-waves and P-waves, In this method, the S-wave and the P-wave are corrected based on the conversion amount to obtain an accurate beam pattern.

In FIG. 14, first, at step ST10
Sets the setting conditions of the optical system to be analyzed. For example,
The distance of the mirrors 1, 200, 1 and their reflectivity or angle, the position and excitation efficiency of the solid-state device excitation part 3a, the position of the wavelength converter 40a and its conversion efficiency, and the position of the transmission mirror 190, if any. And reflectivity are set. Next, the first optical zone in the optical system set in step ST12 is set. Next, in steps ST14 and ST16, a noise component is prepared to excite all beam modes existing in the optical system. That is, a beam pattern is prepared as a random pattern for each of the independent two-direction polarization component S wave and P wave components.

Next, the beam pattern, which is the actual intensity distribution of the laser beam, is represented by the sum of the intensity of the independent S-wave and P-wave components.
The random pattern S wave and P wave prepared in steps ST14 and ST16 are combined, and the beam pattern is temporarily recorded in step ST20. Next, in step ST22, it is determined whether or not there is an element for polarizing the beam in the set optical zone. If there is an element for polarizing, the process proceeds to steps ST24 and ST26. Proceeds to steps ST28 and ST30.

In steps ST24 and ST26, the wave components of the S wave and the P wave before being combined in the optical zone are calculated. The S-wave component and the P-wave component are orthogonal polarization components, and do not interfere with each other in normal propagation through an optical element. Therefore, for example, the wave calculation is performed by independently calculating, for example, Fresnel integral. Thereby, the conversion component POnP to the P wave among the P wave components is calculated in step ST32,
In step ST34, a conversion component SOnP of the P wave component to the S wave is calculated. Similarly, the conversion component POnS of the S wave component to the P wave is calculated in step ST36, and the conversion component SOnS of the S wave component to the S wave is calculated in step ST38.

For example, when a wavelength conversion element for exchanging energy between polarized lights or a birefringent element such as a YAG rod excited and thermally distorted exists in the optical system,
Since energy is exchanged between the polarization components, this is calculated. For example, when an S-wave linearly polarized laser beam enters the above-described birefringent element, it is emitted as elliptically polarized light, so that P-waves are reduced and S-waves are generated. The decreasing change of the P wave, the increasing change of the S wave, and the like are calculated by electric field calculation.

When the changes in the S-wave and P-wave components are calculated in this way, the respective components are combined in steps ST40 and ST42, and the electric fields of the S-wave and the P-wave after passing through the polarization conversion optical element are made independent. Then, in step ST44, the sum of these intensities is calculated. Step ST
28 and ST30, since there is no polarizing element, S wave and P
The wave calculation of each wave is performed, and the sum of these intensities is obtained in step ST46. These steps ST4
When the intensities of the S wave and the P wave are obtained in step 4 or ST46, it is determined in step ST48 whether or not the beam patterns for all the optical zones have been obtained. If the calculation has not been completed for all the zones, step S
Proceed to T50 to set the next zone,
Steps 22 to ST46 are repeated.

When the calculation of the laser patterns of all the zones is completed in step ST48, step ST52 is performed.
Then, this is compared with the previously recorded beam pattern. Based on the result, it is determined whether or not the pattern is stable in step ST54. If the pattern is not stable, the process returns to step ST20, and the above calculation is executed again. When the pattern is stabilized, proceed to step ST56,
The combined beam pattern is output and printed or displayed on a display or the like. As a result, based on the output, the respective components of the P wave and the S wave are compared in step ST58 to calculate the polarization state, and the analysis ends.

FIG. 15 shows an example of the beam pattern analyzed as described above. FIG. 15A shows the intensity distribution of the laser beam generated from the resonator shown in FIG. 13, that is, the calculation result of the beam pattern. The symmetry of the beam is lost due to the birefringence of the YAG laser. I understand. This is because birefringence generated by thermal distortion of the solid state element 3, that is, the refractive index of the solid state element differs between the circumferential direction and the radial direction of the solid state element 3. In the experiment, a beam pattern almost equal to this was obtained.

In order to eliminate the collapse of the symmetry, a laser medium in which a plurality of solid-state elements 3 and 3 shown in FIG. Used in place of element 3. As shown in FIG. 16, instead of one solid element 3, a plurality of solid elements 3, 3 are connected by a holder 610, and a polarization rotator 91a is inserted between them. The polarization rotation plate 91a is composed of a half-wave plate and a 90-degree polarization rotation plate made of, for example, quartz.

According to this configuration, as described above, the polarized light component passing through the left solid element 3 in the figure is rotated 90 degrees by the polarization rotating plate 91a, and passes through the right solid element 3 in the figure. In this way, for example, the influence of birefringence caused by the P-wave component passing through the left solid-state element 3 is canceled by the polarization component propagating as an S-wave in the right-side solid state element 3.

In this configuration, the plurality of solid state elements are
Since they are connected and integrated by 10, they can be easily changed from conventional solid-state devices, and have the feature that the optical axes of a plurality of solid-state devices 3 need not be adjusted. Also,
The end of the solid state device is supported by the holder 300. That is, in the present embodiment, by employing the configuration shown in FIG. 16, it is possible to obtain a calculation result that an axially symmetric beam pattern can be stably obtained as shown in FIG. , Almost the same axially symmetric beam pattern could be obtained.

In this embodiment, the laser device including the wavelength conversion element has been described as an example. However, the purpose is related to the generation of a laser beam having a high intensity, and the configuration of the main part is the wavelength conversion. It goes without saying that the same effect can be exhibited even when applied to a laser device that does not include an element.
In particular, a high effect is exhibited even when applied to any of various resonator configurations described later.

Embodiment 10 FIG. FIG. 17 is a sectional view showing a tenth embodiment of the present invention. The present embodiment differs from the above embodiments in that an unstable resonator having a high light-collecting property is used as a laser resonator. . In each of the above embodiments, a so-called stable type resonator is used in which light is confined in a resonator formed by the total reflection mirror 1 and the partial reflection mirror 2. In this embodiment, an open type resonator is used in a region where the output is large. This is, for example, a configuration using an unstable resonator. That is, in FIG. 17, reference numeral 20 denotes an enlarged reflection mirror, and a non-reflection thin film 27 is provided on the inner surface.
A total reflection thin film 26 is provided at the center, and a so-called negative branch type unstable resonator that condenses a laser beam in the resonator by reflection of the total reflection thin film 26 is formed. By arranging this focusing point near the wavelength conversion element, efficient wavelength conversion is performed.

Embodiment 11 FIG. FIG. 18 is a cross-sectional view showing an eleventh embodiment of the present invention. The difference between the eleventh embodiment and the tenth embodiment is that the magnifying reflection mirror 20 is further devised for phase matching. Is that a phase matching mirror 29 is used. The phase matching mirror 29 has a non-reflective thin film 27 on its inner surface and a
0, and the partial reflection thin film 2
At 60, a so-called negative branch type unstable resonator is formed in which only the fundamental wave component 7a of the laser beam 7 is reflected and the laser beam is condensed in the resonator.
By arranging this converging point near the wavelength conversion element, efficient wavelength conversion is performed as described above.

In this case, the laser beam may receive a phase difference due to the difference in the structure of the thin film between the central portion and the peripheral portion of the phase matching mirror 29. In this regard, for example, as shown in the figure, a step 28 is formed on the outer surface of the phase matching mirror 29 to remove the phase difference. As a result, a high-quality laser beam can be obtained in which the fundamental wave component 7a and the wavelength conversion component 8a of the laser beam 7 transmitted through the phase matching mirror 29 do not cancel each other out.

In this embodiment and the above embodiments,
Light is confined in the resonator, and the wavelength converter 4
In the present invention, the wavelength converter 40a may be disposed outside the resonator. For example, FIG.
9 is a configuration example in which the wavelength converter 40a shown in FIG. 8 is arranged outside the stable resonator composed of the mirrors 1 and 2, and FIG. 20 is composed of the mirrors 1 and 20 shown in FIG. FIG. 21 shows a configuration example in which a wavelength converter 40a is arranged outside the unstable resonator shown in FIG. 21. Further, FIG. 21 shows a wavelength converter 40a outside the unstable resonator formed by the mirrors 1 and 29 shown in FIG. It is a configuration example in which is arranged.

FIGS. 22 and 23 show examples in which the unstable resonator shown in FIGS. 20 and 21 is used, and a transparent body 301 for transmitting a laser beam is provided at the end of the solid-state device 3 facing the mirrors 20 and 29. It is an example of each configuration provided. In these cases, since the mirrors 20 and 29 are resonators in the light collector 6, that is, the light-collecting points are generated in the solid-state device 3,
The intensity of the reflected laser beam incident on the laser beam becomes strong, and air destruction may occur at the focal point. Therefore, FIG.
2 and 23, the transmitting body 301 described in the ninth embodiment is further disposed in the optical path near the exit of the solid state device 3 to form the solid state device 3.
To prevent heating and destruction.

When the wavelength converter 40a is not disposed outside the resonator, for example, in the case of the embodiment shown in FIGS. You may comprise so that it may arrange | position along an optical path. In short, by arranging the transmitting body 301 in a portion where the laser beam can be concentrated in the resonator, destruction of the solid state element 3 or optical elements such as the wavelength conversion elements 40 and 43 is prevented, and laser oscillation and wavelength What is necessary is just to comprise so that conversion efficiency may be improved.

Embodiment 12 FIG. FIGS. 24 and 25 are views showing the structure of a main part of a twelfth embodiment of the present invention. In this embodiment, a case where a semiconductor laser is used as a light source, that is, an excitation source of a laser medium will be described. In FIG. 24A, reference numeral 400 denotes a semiconductor laser, for example, AlGaAs (Aluminum Galium Arsen).
ic) and a laser diode using a semiconductor as an oscillation source. The semiconductor laser 400 is connected to a power supply 5 and fixed on both sides of the light collector 6 with the light emitting portions facing inward. The concentrator 6 includes a semiconductor laser 400
Are formed so as to be vertically splittable along the light-emitting portion where the light-emitting portion is installed, and a plate-like glass member 401 is inserted into the split portion as shown in FIG. This glass member 4
01 is a flat member as shown in FIG.
A laser beam from a light emitting portion of the semiconductor laser 400 enters from one side end of the semiconductor laser 400, transmits light along the surface thereof, and projects light toward the solid state device 3 from the other side end. Forming a road.

FIG. 25A shows a side view of the light collector 6 when the semiconductor laser 400 is removed. In this embodiment, the light collector 6 is configured so as to be able to be further divided into right and left. With this configuration, as shown in FIG. It is configured such that the emission position, angle, and the like thereof can be adjusted so as to correctly enter the member 401 and the solid state element 3.

In this embodiment, in particular, the semiconductor laser 400
Is used, the wavelength range of the laser beam emitted from the condenser 6 through the solid-state element 3 is narrowed. Therefore, the solid-state such as the wavelength-selective thin film 49 on the end face of the solid-state element 3 shown in FIG. The design of the elements around the element 3 is facilitated and can be simplified, so that there is an excellent aspect that each of the above-mentioned effects can be effectively exhibited with an inexpensive configuration.

Embodiment 13 FIG. FIG. 26 is a sectional view showing a fourteenth embodiment of the present invention. This embodiment shows a specific application example of the wavelength conversion laser beam, that is, a laser processor, and more specifically, a holography generator. Things. In this figure, a portion that generates a wavelength-converted laser beam 8 has the same configuration as the laser device described in the eighth embodiment. Here, the laser beam 7 generated by the solid-state element 3 of the Nd: YAG laser is used. An apparatus for generating holography using the green wavelength-converted laser beam 8 that has been wavelength-converted by the wavelength converter 40a composed of a plurality of KTP crystals 40 and 43 will be described.

The wavelength-converted laser beam 8a transmitted through the partial reflection mirror 2 is totally reflected by the total reflection mirrors 1 and 1 and enters the laser mirror 111. The laser mirror 111 is
It is a transmission mirror whose angle can be adjusted freely, and is an angle adjustment mirror that introduces the wavelength-converted laser beam 8a into the prism 32 at a predetermined angle. The prism 32 is a wavelength selection element that selects a wavelength by changing the emission angle according to the incident angle of the wavelength-converted laser beam 8a and emitting the laser beam. The wavelength-converted laser beam 8a from the prism 32
Excites a solid-state element 31 which is a laser medium. The solid state element 31 is, for example, sapphire doped with titanium.
The laser beam 16 generated from the solid state element 31 is emitted through the partial reflection mirror 21. In this example,
The laser beam 16 includes laser mirrors 111 and 21a,
For example, when the laser beam reciprocates in a laser resonator constituted by a wavelength selection element including a prism 32 and is amplified to a certain size or more, the light is emitted from the laser mirror 21a. That is, the laser mirror 111 is provided with a wavelength-selective optical thin film having transparency with respect to the laser beam and total reflectance with respect to the laser beam 16. Similarly, the laser mirror 21
On a, an optical thin film having partial reflectivity to the laser beam 16 and total reflectivity to the wavelength-converted laser beam 8a is provided.

In this embodiment, the solid-state element 31 is a laser medium capable of generating a laser output of a wide range of wavelengths. Since the optical path passing through the prism 32 varies depending on the wavelength, the laser mirror 1 is set to be perpendicular to the optical path of each wavelength.
Adjusting the inclination of 11 reduces the loss of the resonator for a laser beam of that wavelength, and as a result, only that particular wavelength is oscillated.

The wavelength of the laser beam 16 generated by selecting the wavelength is converted by the wavelength conversion element 46. The wavelength conversion element 46 is a non-linear optical crystal made of, for example, BBO (BaB ₂ O ₄ : barium borate) having antireflection thin films 47 and 48 on both surfaces, and converts the incident laser beam 16 into an ultraviolet laser beam 17. I do. The ultraviolet laser beam 17 passes through the transmission mirror 190 and enters the total reflection mirror 1. The transmission mirror 190a is a transmission mirror provided with an optical thin film 192 that totally reflects the laser beam 16. The total reflection mirror 1 is installed at a predetermined angle, and totally reflects the ultraviolet laser beam 17 toward a holography forming unit, a so-called total reflection holography device.

The holography forming unit makes the ultraviolet laser beam 17 incident on the prism 33 and records the holographic interference pattern of the mask 35 on the photosensitive substrate 34 when the ultraviolet laser beam 17 is reflected on the bottom surface. The photosensitive substrate 34 on which the interference pattern is created is called a hologram. Next, as shown in FIG.
Is adhered under the prism 33 and the image of the mask is reproduced on, for example, the semiconductor substrate 36, so-called semiconductor exposure is realized.

In such semiconductor exposure, if a distance between the hologram 34 and the semiconductor substrate 36 is reduced by using a large light source, an extremely fine pattern can be transferred onto the semiconductor substrate 36. This fineness is inversely proportional to the size of the light source, and is proportional to the distance between the hologram 34 and the semiconductor substrate 36.

However, when the degree of fineness is improved and reaches a limit determined by the wavelength, the depth of focus of the optical device becomes extremely shallow, and a three-dimensional pattern having a large aspect ratio cannot be transferred. The distance between the substrates 36 greatly affects the size of the transfer pattern.

In the present embodiment, this is solved by using a tunable laser beam. In holography, using a laser beam with a wavelength different from the wavelength used when creating the hologram, it is theoretically possible that the same pattern as the original pattern is transferred to a space at a different distance from the hologram. I found it.

According to this theory, when the wavelength of the laser beam 17 is changed from, for example, large to small or small to large, as shown in FIG. Light can be incident on the When light of a certain intensity or more is incident on the photosensitive material 37, a narrow portion near the focal point, that is, only a narrow portion and a long portion are exposed due to a feature of being exposed, so that a pattern having a large aspect ratio can be formed. You can do it.

The wavelength conversion described above can be executed by adjusting the angle of the laser mirror 111. Further, the angle or the temperature of the wavelength conversion element 46 is adjusted in accordance with the angle change of the laser mirror, and the ultraviolet laser beam 17 having a constant output is adjusted.
May be generated.

Further, in the above-described embodiment, the method of producing a hologram at one wavelength and performing the reproduction at a plurality of wavelengths has been described. Both creation and reproduction may be performed at a plurality of wavelengths.

The embodiment of the wavelength-converted laser beam described here can be used in combination with the various laser devices described in the present invention. The principle of performing exposure with a high depth of focus by irradiation can be applied to other laser devices not described in the present invention.

Although not particularly described in any of the above embodiments, a non-reflective thin film is applied to a portion of the optical element through which the laser beam passes, unless otherwise specified, as in a normal optical element. If the loss in the resonator is reduced, efficient wavelength conversion can be realized.

Further, in each of the embodiments, the laser device including the wavelength conversion element has been described as an example, but the purpose is related to generation of a laser beam having high intensity, and the configuration of the main part is The present invention may be applied to a laser device that does not include a wavelength conversion element. Also, in all the embodiments, the solid-state laser device has been described as an example, but the purpose is related to the generation of a laser beam having a high intensity, and the configuration of the main part includes other gases, dyes, ion lasers, and the like. The present invention may be applied to a laser device having another laser medium.

As an application example of the laser apparatus shown in the above embodiment, only an application example relating to semiconductor exposure was shown. However, the present invention is not limited to this, and laser processing, dye laser excitation, and display The present invention may be applied to any application field of a normal laser such as a light source.

[0104]

As described above, according to the first aspect of the present invention, a plurality of solid-state elements which are coaxially connected to each other by a connecting member and which are accommodated in a light collector have an inner surface formed of a light reflecting surface. It is stored in a concentrator, which is excited by light emitted from a light source to form a laser medium, and the light generated from this laser medium is taken out as a desired laser beam by a laser resonator.
In this way, by connecting an inexpensive short solid-state element to a long solid-state element, it is configured to be less susceptible to destruction even by irradiation of strong light from a light source. An output laser beam can be obtained.
In addition, since the plurality of solid-state elements are configured to be connected to each other, the arrangement between the solid-state elements is stable, and a high-output laser beam can be stably obtained. Further, since a plurality of solid state elements are provided without increasing the number of holes in the light collector, the light from the light source can be efficiently guided to the solid state elements to excite the solid state elements. Therefore, it is effective to realize high-efficiency laser oscillation. In addition, the inside of the collector
It is composed of a diffuse reflection surface, and the light projected from the light source is collected uniformly.
It is designed so that it spreads inside the optical device and excites the solid-state element uniformly.
Therefore, the solid element may be destroyed due to excessive absorption
To generate stable laser medium even in high power range
High-power laser beam via the laser resonator
Has the effect of being obtained stably. In addition, a sleeve
Insert the end of the solid state element into the binding member to connect multiple solid state elements.
Configuration, so that the arrangement of multiple solid-state
And stable laser oscillation can be compensated.
is there. In addition, a wave plate is provided between a plurality of solid-state elements in the connecting member.
Or, equipped with an optical rotator, and compensates for birefringence by a solid-state element
To counteract the effects of beam deformation
High quality laser beam in the high power range.
Has the effect of being obtained stably.

According to the second aspect of the present invention, the connecting member is constituted by a light reflecting member or the reflecting member is provided on the surface of the connecting member for reflecting the light projected from the light source. As a result, the light of the light source is reflected, and can be reciprocated in the light collector to be guided to the solid-state element, thereby providing an effect that efficient laser oscillation can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a laser device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an operation of the laser device according to the first embodiment of the present invention.

FIG. 3 is an operation explanatory view of the laser device according to the first embodiment of the present invention;

FIG. 4 is a sectional view showing a laser device according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a laser device according to a third embodiment of the present invention.

FIG. 6 is a sectional view showing a laser device according to a fourth embodiment of the present invention.

FIG. 7 is a sectional view showing a laser device according to a fifth embodiment of the present invention.

FIG. 8 is a sectional view showing a laser device according to a sixth embodiment of the present invention.

FIG. 9 is a diagram showing a wavelength conversion element in the embodiment of FIG.

FIG. 10 is a sectional view showing another example of the configuration of the laser device in the embodiment of FIG. 8;

FIG. 11 is a sectional view showing a laser device according to a seventh embodiment of the present invention.

FIG. 12 is a sectional view showing a laser device according to a seventh embodiment of the present invention.

FIG. 13 is a sectional view showing a laser device according to an eighth embodiment of the present invention.

FIG. 14 is a flowchart illustrating a laser pattern analysis method according to a ninth embodiment of the present invention.

FIG. 15 is a diagram showing an analysis result in the embodiment of FIG.

FIG. 16 is a sectional view showing the laser device in the embodiment of FIG.

FIG. 17 is a sectional view showing a laser device according to a tenth embodiment of the present invention.

FIG. 18 is a sectional view showing a solid-state laser device according to Embodiment 11 of the present invention;

FIG. 19 is a sectional view showing another example of the laser device corresponding to the embodiment of FIG. 8;

FIG. 20 is a sectional view showing another example of the laser device corresponding to the embodiment of FIG. 17;

FIG. 21 is a sectional view showing another example of the laser device corresponding to the embodiment of FIG. 18;

FIG. 22 is a sectional view showing a laser device according to another embodiment corresponding to FIG. 20;

FIG. 23 is a sectional view showing a laser apparatus according to another embodiment corresponding to FIG. 21;

24A and 24B are diagrams illustrating a configuration of a main part of a laser device according to a twelfth embodiment of the present invention, wherein FIG. 24A is a side view, FIG. 24B is a front view, and FIG.

FIG. 25 is a partial view of the embodiment of FIG. 12,
(A) is a side view, (b) is a front view.

FIG. 26 is a sectional view showing a solid-state laser device according to Embodiment 5 of the present invention.

FIG. 27 is a sectional view showing a laser processing apparatus according to Embodiment 13 of the present invention;

FIG. 28 is a sectional view showing a laser processing apparatus according to Embodiment 13 of the present invention.

FIG. 29 is a sectional view showing a laser device according to a conventional example.

FIG. 30 is a sectional view showing a laser device according to a conventional example.

FIG. 31 is a sectional view showing a laser device according to a conventional example.

FIG. 32 is a sectional view showing a laser device according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Total reflection mirror 2 Partial reflection mirror 3 Solid-state element 4 Light source 5 Power supply 6 Condenser 7 Laser beam 20 Magnification reflection mirror 21 Collimation total reflection mirror 22 Partial reflection mirror 23 Non-reflection part 24 Expansion exit mirror 25 Step difference 40, 43 Wavelength conversion Element (non-linear optical crystal) 41, 42, 44, 45 Optical thin film 61 Connecting member 62 Dust shielding container 70 Laser beam 80, 81 Through hole 90 Polarization selecting element 91 Wave plate or optical rotation plate

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-51-94791 (JP, A) JP-A-55-62791 (JP, A) JP-A-3-292782 (JP, A) JP-A-1- 222234 (JP, A) JP-A-64-73686 (JP, A) JP-A-5-291654 (JP, A) JP-A-57-130454 (JP, U) JP-A-58-180654 (JP, U) Shokai 62-73568 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01S 3/23 H01S 3/08 H01S 3/092-2/093

Claims (2)

(57) [Claims] 1. A laser apparatus comprising: a laser medium that generates excitation light; an excitation source that excites the laser medium; and a laser optical system that extracts a laser beam from the laser medium that is excited by the excitation source. The source is a light source,
The inner surface does not concentrate the light emitted from the light source in some places
And a concentrator formed of a diffused reflecting surface such that the laser medium has coaxial ends that are opposed to each other.
Along with being provided in the light collector in a state of being connected by a sleeve-like connecting member that can be inserted above , both ends face the laser optical system through through holes formed in the light collector, and Laser excited by light emitted from light source
Ri Do a plurality of solid state devices for generating a beam, and the scan
Opposite ends of the solid state elements in the leave-shaped connecting member
A laser device comprising a wave plate or an optical rotation plate between the sections . 2. The connecting member is formed of a light reflecting member.
Or a light reflecting member on the surface.
The laser device according to claim 1 .