JPH0388379A - Laser device - Google Patents

Abstract

PURPOSE:To enable the difference in wavelength conversion efficiency to be restricted at a beam sectional surface of a fundamental wave laser light inciding a non-linear optic crystal by providing a laser light source enabling the fundamental wave laser light to be irradiated and a means for transferring light intensity distribution obtained by a regulation means to a non-linear optic crystal similarly. CONSTITUTION:The title item has a laser light source 10 which irradiates a fundamental wave laser light with a regulated light intensity distribution and a transferring means 13 which similarly transfers the light intensity distribution where the light intensity of the fundamental laser light from this laser light source 10 is regulated by a regulating means to the light intensity distribution of the fundamental laser light advancing within non-linear optic crystals 11 and 12. Since it has the laser light source 10 for irradiating the fundamental wave laser light, it is possible to restrict light intensity of a beam section. Also, since it has the means 13 for similarly transferring to the non-linear optic crystals 11 and 12, it is possible to restrict the difference in optic strength at the section. Thus, it is possible to restrict the difference in wavelength conversion efficiency at the beam section.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser device that converts the wavelength of laser beam #tr into a harmonic laser beam using a non-annular optical crystal such as KTP and emits it.

[Prior Art] Generally, when wavelength conversion is performed from a fundamental laser beam to a harmonic laser beam using a nonlinear optical crystal, the conversion efficiency is as follows:
It is widely known that it depends on the optical intensity of the fundamental laser beam incident on a nonlinear optical crystal. Based on this fact,
A laser device has been proposed that aims to improve the light intensity of the fundamental laser beam by focusing it when it is incident on a nonlinear optical crystal, thereby obtaining harmonic laser beams with high conversion efficiency. (For example, JP-A-62
(Refer to Publication No.-189783).

FIG. 4 is a configuration diagram of the laser device according to the above proposal.

In the figure, numeral 1 is a solid laser medium, numeral 2 is a nonlinear optical crystal, numeral 3 is an output mirror, numeral 4.5 is a convex lens, and numeral 6 is an excitation light source consisting of a laser diode.

The solid state laser 1fI body 1 has an opposite end surface 1a1 in the optical axis direction.
1b. A reflective film that cooperates with the output lI3 and forms a resonator for the fundamental laser beam emitted from the solid-state laser medium 1 is disposed on the end face 1a. This resonator, i.e. the output! A nonlinear optical crystal 2 is disposed in a resonant optical path of the fundamental laser beam formed between the laser beam 113 and the reflective film. Since the end face 1b of the solid-state laser medium 1 is formed in the shape of a spherical lens, the resonant light of the laser light becomes focused light within the nonlinear optical crystal 2. The reflective film disposed on the end surface 1a of the solid-state laser medium 1 has an optical property of reflecting the fundamental laser beam, and also transmits the excitation laser beam emitted from the laser diode 6 and has a nonlinear property. It also has the optical property of reflecting harmonic laser light emitted from the optical crystal 2.

Further, as described above, the output 113 serves as a resonator for the fundamental laser beam, but transmits the harmonic laser beam whose wavelength has been partially converted from the fundamental laser beam in the nonlinear optical crystal 2. It has optical properties.

Therefore, the excitation laser beam emitted from the laser diode 6 is focused by the convex lens 4.5, and then made incident on the solid-state laser medium 1 to excite the solid-state laser medium 1, whereby the output lI3 and the reflection film are Between, solid-state laser medium 1
A resonant optical path of the fundamental laser beam emitted from the laser beam is formed.

As a result, the focused fundamental laser beam enters the nonlinear optical crystal disposed in this resonant optical path, so that the harmonic laser beam whose wavelength is converted from the fundamental laser beam is generated in the nonlinear optical crystal 2. ,output! Harmonic laser light can be extracted from 113.

Incidentally, since the excitation laser beam emitted from the laser diode 6 is focused on the optical axis of the solid-state laser medium 1 by the convex lens 4.5, the fundamental wave laser beam emitted from the solid-state laser medium 1 is a TEM.

O mode (Gaussian distribution).For this reason, when this fundamental wave laser beam is focused, a high degree of convergence can be obtained, so the fundamental wave laser beam will show high light intensity in the nonlinear optical crystal and will not be focused. Fundamental laser light can be converted to harmonic laser light with a relatively high wavelength conversion efficiency compared to the conventional case.

[Problems to be Solved by the Invention] However, in conventional laser devices, the light intensity distribution in the beam diameter direction of the fundamental laser light incident on the nonlinear optical crystal is a Gaussian distribution, so the light intensity varies depending on the beam diameter. It gradually decreases from the center to the periphery. When a fundamental laser beam having such a light intensity distribution is incident on a nonlinear optical crystal, the wavelength conversion efficiency decreases from the center of the beam diameter toward the periphery as the light intensity changes as described above. In other words, as long as Gaussian-distributed fundamental laser light is incident on a nonlinear optical crystal, if the fundamental laser light, which is uniform in the beam radial direction, is focused and incident on the nonlinear optical crystal, the light intensity will be improved near the beam center. However, the non-uniformity of wavelength conversion efficiency in the beam radial direction becomes noticeable. Furthermore, each nonlinear optical crystal has its own destruction threshold depending on the type of crystal, so it is not possible to increase the light intensity of the fundamental laser beam without limit. Therefore, there is a problem in that it is difficult to measure the direction of wavelength conversion efficiency, E, only by increasing the light intensity of the fundamental laser beam, as in conventional laser devices.

The present invention was made in view of the above-mentioned problems, and
It is an object of the present invention to provide a laser device in which the light intensity in a beam cross section is regulated and a fundamental laser beam whose light intensity is amplified is incident on a nonlinear optical crystal, thereby obtaining high wavelength conversion efficiency.

[Means for Solving the Problems] A laser device of the present invention includes a laser light source that emits fundamental laser light having a light intensity distribution in which the light intensity of a beam cross section is made III by a regulating means, and a laser light source that emits fundamental wave laser light that is emitted from the laser light source. an amplifying means for amplifying the light intensity of the fundamental laser beam; a nonlinear optical crystal that inputs the fundamental laser beam sent out from the amplifying means, converts the wavelength into a harmonic laser beam, and emits it; and from the laser light source. Transfer means for transferring the light intensity distribution of the emitted fundamental laser light whose light intensity is regulated by the regulation means to the light intensity distribution of the fundamental laser light traveling within the nonlinear optical crystal. It is characterized by:

Further, another laser device d of the present invention includes a laser light source that emits a fundamental laser beam having a light intensity distribution in which the light intensity of the beam cross section is regulated by a regulating means, and a laser light source that emits a fundamental laser beam having a light intensity distribution in which the light intensity of the beam cross section is regulated by a regulating means, and a laser device that inputs the fundamental laser beam to generate high-frequency harmonics. It is equipped with a nonlinear optical crystal that converts the wavelength into wave laser light and emits it, and has a pair of front and rear imaging points, and the light intensity distribution in the beam cross section of the fundamental wave laser light at the front imaging point is adjusted to A plurality of image relays for transmitting images to an image forming point are interposed in series between the regulating means of the laser light source and the nonlinear optical crystal, and the plurality of image relays are arranged on the front side included in the regulating means. It includes at least an image relay having an imaging point and an image relay having a rear imaging point included in the Xuji nonlinear optical crystal, and adjacent image relays are configured to form images on the front and rear sides of each other. at least one of the adjacent image relays,
The present invention is characterized in that amplifiers including front and rear imaging points are arranged close to each other.

[Function] The laser device of the present invention emits a fundamental laser beam having a light intensity distribution in which the light intensity of the beam cross section is regulated by the M4tI11 means. -, the light intensity of the beam cross section of the fundamental wave laser light can be suppressed by the regulating means. Furthermore, since the light intensity distribution obtained by the regulating means is provided with a means for transferring the light intensity distribution obtained by the regulating means to the nonlinear optical crystal in a similar manner, the light intensity distribution obtained by the regulating means is transmitted to the nonlinear optical crystal. Although the light intensity distribution varies accordingly, it is possible to form a light intensity distribution having similarity to the light intensity distribution described above at least inside the nonlinear optical crystal. Therefore, even in the fundamental laser beam incident on the nonlinear optical crystal, the difference in light intensity in the beam cross section can be suppressed, and as a result, the difference in wavelength conversion efficiency can be suppressed.

Furthermore, 11 the laser device of the present invention is provided with an amplification means for amplifying the light intensity of the fundamental laser light emitted from the laser light source and sending it to the nonlinear optical crystal. It is possible to maintain the optical intensity distribution of the fundamental wave laser beam and amplify its peak intensity to make it incident on the nonlinear optical crystal.

[Embodiment] Hereinafter, an embodiment of the laser device of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a configuration diagram of an embodiment of the laser device of the present invention;
Figure 2 is a configuration diagram of the image relay, and Figures 3 (a) to (
b) is a diagram showing changes in the light intensity distribution when the fundamental wave laser light travels. In FIG. 1, the optical axis ■ behind the image relay 2o is the optical axis ■ in front of the amplifier 27.
is combined with

This laser device first passes a fundamental laser beam emitted from a laser light source 1o to a second nonlinear optical crystal 11.
The wavelength is converted into a harmonic laser beam, and the 2'BM wave laser beam obtained by the first nonlinear optical crystal 11 is further wavelength converted into a fourth harmonic laser beam in the second nonlinear optical crystal 12. . Then, the light intensity distribution of the beam cross section of the fundamental laser light obtained by the laser light source 10 is determined by the first
A transfer means 13 for transferring information to the nonlinear optical crystal 11 and the second nonlinear optical crystal 12 in a similar manner, and an amplification means 14 for amplifying the light intensity of the fundamental wave laser beam are connected to the laser beam 111.
G and the second nonlinear optical crystal 12.

The laser light source 10 includes a laser oscillator 1lls that Q-switch oscillates the fundamental laser beam L1, a beam expander 16 that expands the beam diameter of the fundamental laser beam 1 oscillated from the laser oscillator 15, and this beam expander. 16, and an aperture 17 serving as a JJIIIJ means for adjusting the light intensity of the beam cross section of the fundamental wave laser beam 16 to MtA.

Said laser oscillation! 115, the wavelength of 1.06 was obtained by exciting a laser medium (not shown) made of Nd:YAG and driving a Pockels cell (not shown).
It emits a 4m fundamental wave laser and can cause the blind to Q-switch oscillation. This fundamental laser beam L1 has a transverse mode of TEM00, and the light intensity distribution of the beam cross section at the time of emission (point x in Figure 1) is a Gaussian distribution < t tr as shown in Figure 3 (a). )-106-2'fy)"
However, Io is the peak intensity and ω is the beam radius. ).

Moreover, the peak intensity 1o is 2 Mw/gJ.

The beam expander 16 is composed of a pair of convex lenses 16a and 16b that share a confocal point 16C. The fundamental laser beam L1 incident on the beam expander 16 is converted into the fundamental laser beam L2 whose beam diameter ω is expanded from 1 am to 10 mm, and is emitted from the beam expander 16. The light intensity distribution of the fundamental laser beam 2 at the time of emission (point Y in Figure 1) is the third
As shown in Figure (b), although the peak intensity is reduced to 1100 K/m compared to fundamental wave laser 1, the light intensity distribution has a relaxed change in light intensity from the center of the beam to the periphery. .

Aperture 17 is 16JwI (height) 08 in the center
It consists of a disc-shaped body with a rectangular opening 17a having a width of m (width). The fundamental wave laser beam L2 sent out from the beam expander 16 enters the entrance surface 17b of the aperture 17, and in the incident fundamental wave laser beam 2, the aperture 11h1 and the like enter the opening 17a. Only the fundamental laser beam L3 that has passed is selectively emitted. At this time, the beam cross section of the fundamental laser beam L3 is 16 mg + (height) x 8 am, which corresponds to the outer shape of the aperture 17a.
(width). Moreover, the light intensity distribution of the fundamental laser beam L3 at the entrance surface 17b of the aperture 17 (
1) As shown in Figure 3(C), in the beam width range of 8 layers, the maximum light intensity*1100K/aJ to the minimum light intensity 9
A substantially rectangular light intensity distribution is obtained in which the light intensity is regulated between 7 KW/aj. In addition, for this regulation, the light intensity distribution should be transformed into a super Gaussian distribution 1(r)-1°e-(fr,)", oh...ga-.distribution, that is, II! into an imaginary rectangular shape. It is preferable to do so.

In this way, from the laser light source 10, the aperture 1
7, it is possible to emit the fundamental laser beam L3 having a light intensity distribution (I) in which the light intensity of the beam cross section is controlled within a certain range.

Next, the fundamental laser beam L3 emitted from the laser light source 10
The transfer means 13 that transfers the light intensity distribution (I) on the incident surface 17b of the 7-perchur 11 to the first nonlinear optical crystal 11 and the second nonlinear optical crystal 12 in a similar manner will be explained.

This transfer means 13 is interposed between the laser beam l110 and the second nonlinear optical crystal 12, and is connected to the image ◆relays 18, 19, . 2G, 21. and 22.

First, a general image relay composed of a pair of convex lenses will be explained with reference to FIG. The image relay 3G shown in FIG. 2 has a focal length f1
a first convex lens 30a and a second convex lens 3 with a focal length f2.
0b and are arranged facing each other on the optical axis.

The ray matrix t of this image relay 30 can be expressed by the following equation (1).

In addition, in the above formula (1), a is the first convex lens 30a.
b is the distance from the main surface of the second convex lens 30b to the rear imaging point B of the image relay 30, and d is the distance from the main surface of the second convex lens 30b to the front imaging point B of the image relay 30. This is the distance between the two surfaces of the second convex lens 30b.

When the first convex lens 30a and the second convex lens 30b are emitted from above, the light intensity distribution of the beam cross section of the laser beam L3° at the forward imaging point A is transferred to the rear imaging point B in a similar manner. I can do it.

The image relays 18 to 22 in this embodiment are also
Like the image relay 30 shown in the figure, each of the first convex lenses 18a to 22a and the second convex lenses 18b to 22b
It is composed of. However, in this embodiment, in order to maintain not only the similar transfer of the light intensity distribution from the front imaging point to the rear imaging point, but also the parallelism of the beam, the first convex lens 18a is 22a and the second convex lenses 18b to 22b are optically coupled to each other so as to share the confocal points 18c to 22c. This results in d-fl + f2 in the above equation (1), so in the end, the image relays 18 to 22 of this embodiment are
) will satisfy the formula.

b-M(f1+f2)-aM' (2) (However,
M−f2/f+) Therefore, in order to satisfy the above equation (2), the image
The focal length f1 of the first convex lenses 18a to 22a and the focal length f2 of the second convex lenses 18b to 22b of the relays 18 to 22
, from the first convex lenses 18a to 22a to the front imaging point AI8 to
^22 and the second convex lenses 18b to 2
The distances from 2b to the rear imaging points 818 to B22 were selected as shown in Table 1.

Margin below Table 1 As shown in Table 1, image relay 21 and image relay 22 have f 2 / f 1 of 1/2.
It is 1/3.

By setting this ratio, the fundamental wave laser beam L7. which is emitted from the image relays 21 and 22. Since the cross-sectional area of L10 is reduced to 1/2 and 1/3, the power density is improved.

As mentioned above, the individual image relays 18 of this embodiment
22 can transfer the light intensity distribution similarly from the front imaging point to the rear imaging point while maintaining the parallelism of the beam. Therefore, the laser beam 1i10 and the second nonlinear optical crystal 1
When image relays 18 to 22 are arranged in series between
The light intensity distribution formed in b can be similarly transferred to the optical axis midpoint G of the first nonlinear optical crystal 11 and the optical axis midpoint H of the second nonlinear optical crystal 12. That is, the image relay group includes an image relay 18 whose front imaging point A18 is aligned with the entrance surface 17b of the aperture 11, and whose rear imaging point B22 is aligned with the second nonlinear optical crystal 22.
The image relays 19 to 21 are sandwiched by the image relay 22 aligned with the center point of the optical axis of the image relay 22, and adjacent image relays have a configuration in which the front and rear imaging points of the image relays 19 to 21 are aligned with each other. have Therefore, adjacent image relays will share a co-image point with each other. In other words, the image relay 19 has its front imaging point A19
The image relay 18 shares a co-imaging point that coincides with the rear imaging point 818 of the image relay 18, and the rear imaging point B19 and the front imaging point A20 of the image relay 20. Image the co-image point E that coincides with
It is shared with Relay 20.

Furthermore, the image relay 21 has its front imaging point A21
The co-imaging point F that coincides with the rear imaging point 82G of the image relay 20 is shared with the image relay 20, and the rear imaging point 821 is the front imaging point A22 of the image relay 22. The matched co-image point G is shared with the image relay 22.

Next, the amplification units 25, 26 and 21, which are arranged on the co-imaging points E and F of the image relay group mentioned above and constitute the amplification means 14, will be explained.

The amplifiers 25, 26, and 21 are arranged on the optical axis with their optical axis midpoints coincident with the co-imaging point, E, and E, respectively. , both made of Nd: YAG, whose shape is inclined with respect to the optical axis, and has an entrance surface and an exit surface that are parallel and opposite to each other, and alternately reflects the fundamental laser beam incident from the entrance surface. As a result, each of the amplifiers 25, 26 and 2 has a so-called slab shape, with opposing reflections and surfaces that propagate to the exit surface.
7 has a rectangular shape with both the incident surfaces having a height of 20 mm and a width of 10 mm, and the length of the reflecting surface is 120 mm, so that the fundamental laser beam passes through each amplifier. The light intensity is amplified approximately 10 times each time.

Next, a first nonlinear lens is placed on the optical axis with the midpoint of the optical axis coincident with the co-imaging point G of the image relay group and the rear imaging point 822 of the image relay 22, respectively. The optical crystal 11 and the second nonlinear optical crystal 12 will be explained.

The first nonlinear optical crystal 11 is KTP (KT i 0PO
a), and the fundamental wave laser beam (
Wavelength: 1.064 m) is propagated inside this crystal along the optical axis and then emitted from the output surface, thereby generating a second wavelength-converted fundamental laser beam inside the crystal.
A harmonic laser beam (wavelength=0.532 m) can be emitted from the emission surface together with the fundamental laser beam. or,
The first nonlinear optical crystal 11 is a cube having both an incident surface and an exit surface as squares with a height of 10 aw and a width of 10 j*, and a length in the optical axis direction of 10 aw I, and its destruction threshold is 400 Mw/a I.

The second nonlinear optical crystal 12 is made of (β-BaB204), and receives the second harmonic laser beam (wavelength = 0.532−) obtained in the first nonlinear optical crystal 11 from the incident surface, and After propagating inside the crystal along the axis, the second
A fourth harmonic laser beam (wavelength=0.266 cm), which is wavelength-converted from the harmonic laser beam, can be emitted from the output surface together with the second harmonic laser beam. Moreover, this second nonlinear optical crystal 12 has both an incident surface and an exit surface with a height of 10
A+X is a square with a width of 10am and the optical axis direction is also 10a
It consists of a cube with w, and its destruction threshold is 13.5Gw.
/d.

Below, the fundamental wave laser beam L3 emitted from the laser light source 10
Amplifying means 14 and transfer means 13 having the above-mentioned configurations
The process of guiding the light to the first nonlinear optical crystal 11 to obtain a second harmonic laser beam, and the process of guiding the light to the first nonlinear optical crystal 11 by
The process in which the second harmonic laser beam obtained in step 1 is guided to the second nonlinear optical crystal 12 to obtain the fourth harmonic laser beam will be described.

The fundamental wave laser beam L3 emitted from the laser light source 10 (beam cross section: rectangular shape with height 19M x width 8 shoes) is shown in Fig. 3(C).
Light intensity distribution (I) with a peak intensity of 100 KW/cd shown in
at the entrance surface 17b of the aperture 17. The fundamental wave laser beam L3 emitted from the laser beam am10 is guided by the image relay 18 and enters the incident surface of the amplifier 25 (rectangular shape of 20 layers in height and 10 layers in width).

The incident fundamental wave laser L3 travels by alternately reflecting the opposing reflecting surfaces of the amplifier, and as a result, the peak intensity increases to I.
Mw/aJ, and at the center of the optical axis, the third
The fundamental wave laser L4 having the light intensity distribution (If) shown in FIG. 3(C) is emitted from the emission surface. This amplification! I25
The fundamental wave laser beam L4 emitted from the is guided to the amplifier 26 by the image relay 19, and in this amplifier 26, the peak intensity is amplified to 10 Mw/aj, and
The light intensity distribution (I
II) becomes the fundamental laser beam L5 and passes it to the amplifier 26.
Emits from. Furthermore, this fundamental wave laser beam L5 is guided to an amplifier 27 by an image relay 20, and in this amplifier 27, the peak intensity is amplified to 100 Mw/cIj, and the peak intensity is amplified to 100 Mw/cIj at the optical axis midpoint F as shown in FIG. 3(C). The fundamental wave laser beam L6 having the light intensity distribution (■) shown in FIG. 2 is output from the amplifier 27.

Thus, amplifiers 25, 26 . The fundamental wave laser beam L6 sequentially amplified in and 27 enters the image relay 21. The fundamental wave laser beam L6 is the image relay 21
, the fundamental laser beam L7 is reduced to a rectangular shape with a height of 8jw x width of 4aw+ so that its beam cross section fits within the incident surface of the first nonlinear optical crystal 11, and is amplified to a peak intensity of 400Mw/1:ll. and is emitted from the image relay 21. The fundamental wave laser beam L7 emitted from this image relay 21 is transmitted to the first nonlinear optical crystal 11.
The light enters the plane of incidence and travels inside the crystal. During this progression, part of the fundamental laser beam L7 is wavelength-converted to the second harmonic laser beam (wavelength: 0.532a) La.
The second harmonic laser beam L8 and the remaining fundamental laser beam L9 are emitted from the emission surface.

The 12th harmonic laser beam L8 and the fundamental laser beam L9 emitted from the first nonlinear optical crystal 11 enter the image relay 22, and in the image relay 22,
In both cases, the cross-sectional shape of the beam is 2.67cm high x 1.33cm wide.
m is reduced to a rectangular shape and the peak intensity is 1.35G.
The second harmonic laser beam L10 amplified to w/d and the fundamental laser beam Ln are emitted from the image◆relay 22.

The second harmonic laser beam L1o and the fundamental laser beam Ln emitted from the image relay 22 enter the incident surface of the second nonlinear optical crystal and travel inside the crystal. During this progression, a part of the second harmonic laser beam L1° (this laser beam becomes the fourth harmonic laser beam and becomes the fundamental laser beam for e) is transferred to the fourth harmonic laser beam L12 (wavelength: 0. 266m
), the second harmonic laser beam Ln remaining from the fourth harmonic laser beam Lt1 and the second fundamental laser beam Ln are emitted from the emission surface. In this way, the second harmonic laser beam L8 and the 4114th wave laser beam L1 are generated in each of the first nonlinear optical crystal 11 and the second nonlinear optical crystal 12.
You can get 2. The fundamental laser beam L7 traveling inside the first nonlinear optical crystal 11 has a light intensity distribution (V) shown in FIG. 3(C) at the optical axis midpoint G of this crystal, and The second harmonic laser beam L1o traveling inside the second nonlinear optical crystal 12 is located at the optical axis midpoint H of this crystal.
It has a light intensity distribution (Vl) shown in FIG. 3(C).

In this way, as is clear from FIG. 3(C), the light intensity distribution (I) formed at the aperture near 17 is transferred by the transfer means 13 to the optical axis midpoint D of the amplifier 25 (light intensity distribution (
I)), the optical axis midpoint E of the amplifier 26 (light intensity distribution (III
)), amplification-1127 optical axis midpoint F (light intensity distribution (IV
)), the optical axis midpoint G (light intensity distribution (V)) of the first nonlinear optical crystal 11, and the optical axis midpoint H (light intensity distribution (Vl)) of the second nonlinear optical crystal 12 are sequentially similar. is being transferred. Therefore, the fundamental wave laser beam L7 incident on the first nonlinear optical crystal 11 and the second harmonic laser beam Lm incident on the second nonlinear optical crystal 12 can have high light intensity in the beam cross-sectional direction. However, since the light intensity of the defined light intensity distribution is amplified by the amplification means, extremely high wavelength conversion efficiency can be obtained.

Furthermore, since the image relays 18 to 22 constituting the transfer means 13 of this embodiment all have the first convex lens and the second convex lens confocal, the fundamental light passing through the first nonlinear optical crystal 11 is The wave laser beam L7 and the second harmonic laser beam L10 passing through the second nonlinear optical crystal 12 both pass through while maintaining the parallelism of the beams, so that they can be While reaching the exit surface,
Wavelength conversion can be performed stably.

In this example, the second harmonic laser beam L8 obtained from the first non-cotton-shaped optical crystal 11 and the second nonlinear optical crystal 12
When each of the fourth harmonic laser beams Lt2 obtained from It was confirmed that it was about 20%.

Both of these wavelength conversion efficiencies are improved by about 30% compared to the conventional laser device.

In this embodiment, a Kepler type image relay comprising a pair of convex lenses is used as the image relay constituting the transfer means, but a Galileo type image relay comprising a convex lens and a concave lens may also be used.

Further, adjacent image relays do not necessarily have to share a common imaging point, and there is no practical problem as long as the front and rear imaging points of the image relay area are arranged close to each other. Similarly, the front imaging point A18 of the image relay 18 and the entrance surface 11b of the aperture 17, the rear imaging point B21 of the image relay 21, the optical axis midpoint G1 of the optical axis crystal 12 of the first nonlinear optical crystal 11, and The rear imaging point 822 of the image relay 22 and the second nonlinear optical crystal 12
There is no problem in practical use as long as the optical axis midpoint H and the optical axis midpoint H do not coincide with each other, but as long as they are placed close to each other.

Furthermore, amplifiers 25, 26 . and 27 are placed on the co-imaging points E and F, respectively, but the amplifiers may be placed as appropriate in consideration of damage to the nonlinear optical crystal. For example,
It is also possible to use only the amplifiers 25 and 26 and to arrange other optical elements on the coupling point F.

[Effects of the Invention] The laser device of the present invention includes a laser light source that emits a fundamental laser beam having a light intensity distribution in which the light intensity of the beam cross section is regulated by means of 1Rii11, and a light intensity distribution obtained by the regulating means. and a transfer means for transferring information to the nonlinear optical crystal in a similar manner.

As a result, first, it is possible to form a light intensity distribution in which the difference in light intensity in the cross section of the beam is suppressed in the regulating means. Although the light intensity distribution formed by this #1 control means changes as the fundamental wave laser beam advances after being emitted from the #ll11 means, at least in the nonlinear optical crystal, the light intensity distribution is different from the light intensity distribution. A light intensity distribution having similarity can be formed. Therefore, the difference in wavelength conversion efficiency in the beam cross section of the fundamental laser beam incident on the nonlinear optical crystal can be suppressed.

Furthermore, since the laser device of the present invention is equipped with an amplification means for amplifying the light intensity of the fundamental laser light incident on the nonlinear optical crystal, in addition to suppressing the difference in light intensity in the beam cross section described above, The peak intensity of the incident light intensity distribution can be improved. Therefore, according to the laser l1lF of the present invention, harmonic laser light whose wavelength is converted from the fundamental laser light can be obtained from the nonlinear optical crystal with extremely high wavelength conversion efficiency.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram of an image relay, and Figs. 3 (a) to (C) show the light intensity when the fundamental laser beam travels. FIG. 4, which is a diagram showing changes in distribution, is a configuration diagram of a conventional laser device. DESCRIPTION OF SYMBOLS 10... Laser light source, 11... First nonlinear optical crystal, 12... Second nonlinear optical crystal, 13... Transfer means, 14... Amplification means, 17... Aperture 18 serving as regulating means ~22-...Image Relay, 25-27
···amplifier.

Claims (2)

[Claims] (1) A laser light source that emits fundamental laser light having a light intensity distribution in which the light intensity of a beam cross section is regulated by a regulating means; and an amplification means that amplifies the light intensity of the fundamental laser light emitted from the laser light source. , a nonlinear optical crystal that inputs the fundamental laser beam emitted from the amplification means, converts the wavelength into harmonic laser light, and emits it; 1. A laser device comprising: transfer means for transferring a light intensity distribution whose intensity is regulated in a similar manner to a light intensity distribution of a fundamental laser beam traveling within the nonlinear optical crystal. (2) A laser light source that emits fundamental laser light having a light intensity distribution in which the light intensity of the beam cross section is regulated by a regulating means; An image that has a pair of front and rear imaging points, and transfers the light intensity distribution in the beam cross section of the fundamental laser beam at the front imaging point to the rear imaging point. - A plurality of relays are interposed in series between the regulating means of the laser light source and the nonlinear optical crystal, and the plurality of image relays are configured to transmit an image having a front imaging point included in the regulating means. It includes at least a relay and an image relay having a rear imaging point included in the nonlinear optical crystal, and adjacent image relays are arranged with their front and rear imaging points close to each other. , at least one between the adjacent image relays,
A laser device characterized in that an amplifier is disposed including front and rear imaging points, each of which is disposed in the vicinity of the other.