JPH118427A - Multiple laser beam generating apparatus and multiple laser beam generating element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multiple laser beam generating apparatus and element which avoids deterioration in beam quality. SOLUTION: An apparatus includes an optical resonator for confining laser beams therein and partial transmission mirrors 4-1 and 4-2 for reflecting laser beams, trapped within the resonator in a multiple manner for taking out part of the beams partially transmitted through the mirrors at the time of the reflection thereof towards outside the resonator. The resonator may be a laser resonator containing a laser medium 1 therein or of a type which receives light from another laser beam generating apparatus provided separately. Or the resonatory may be the so-called Fabry-Perot resonator, in which light is reciprocated between two mirrors or be a ring resonator in which light is propagated along an annular optical path defined by three or more mirrors in one direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex laser beam generating device and a multiplex laser beam generating device for dividing a laser beam into a plurality of beams.

[0002]

2. Description of the Related Art A laser device generates high-intensity coherent light, and its application is wide-ranging, such as information transmission measurement, processing, and medicine. Of these, dividing the laser beam into a plurality of light beams may provide a great effect.
For example, in the processing field, by dividing the laser beam,
In many cases, multipoint processing can be performed efficiently, and in the information field, it is necessary to split laser light in order to input laser light to a large number of optical fibers.

[0003] Diffraction gratings have been widely used for splitting laser light. Diffraction gratings have a fine periodic pattern formed in the light transmitting or reflecting part.
By utilizing the property of scattering light only in a specific direction, a single laser beam can be split into a plurality of beams.

[0004]

However, diffraction gratings are convenient, but require fine processing, so that special manufacturing equipment and techniques are required for manufacturing. Further, as an essential problem, there is a problem to be solved that deterioration of beam quality is inevitable.

For example, when the diameter of the diffraction grating is D and the wavelength of light is λ, the diffraction angle θ of each split beam is:

[0006]

(Equation 1)

The width δθ expressed by When the wavelength width of the incident laser light is δλ,

[0008]

(Equation 2)

[0009] Spreading due to the occurrence of a new phenomenon also occurs. here,
m is the order of diffraction and b is the lattice constant. It is a problem whether these widths are sufficiently small with respect to the beam divergence angle θ of the laser beam before division, and in some cases, δθ cannot be ignored. As can be seen from the above expressions (1) and (2), it is important that D and b are large in order to reduce δθ. Therefore, when a large-diameter diffraction grating is used for light having a large beam diameter, Has few problems,
In the opposite case, δθ increases and satisfactory performance cannot be expected.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a multiplex laser light generating apparatus and a multiplex laser light generating element which have a simple structure and do not cause deterioration in beam quality. It is in.

[0011]

In order to achieve the above object, according to a first aspect of the present invention, there is provided an optical resonator which includes a laser medium and confine laser light emitted from the laser medium. A multi-reflecting unit for multi-reflecting the laser light in the optical resonator by a partially transmitting mirror, and extracting the transmitted light of the partially transmitting mirror out of the optical resonator.

Here, the partial transmission mirror may be a pair of opposed multiple reflection mirrors having a partial transmission surface on the inside and a transmission surface on the outside.

Further, the partially transmitting mirror may be a multiple reflection slab that transmits a part of the oscillation laser light of the laser medium.

In order to achieve the above object, a second aspect of the present invention is provided.
According to a fourth aspect of the present invention, there is provided an optical resonator including a laser medium and a non-linear optical crystal for converting an oscillation laser beam of the laser medium into a harmonic thereof, and confining the oscillation laser; And a multiple reflection unit that transmits the harmonics by multiple reflection, and takes out the harmonics transmitted through the multiple reflection unit out of the optical resonator.

Here, the multiple reflection section is composed of a multiple reflection slab having, on both sides, a partial transmission surface that transmits the harmonic and reflects the fundamental wave, and a transmission surface that transmits the harmonic and the fundamental wave. It can be.

[0016] The multiple reflection section may be composed of a pair of multiple reflection mirrors that face each other with the nonlinear optical crystal interposed therebetween and transmit the harmonic.

In order to achieve the above object, a third aspect of the present invention is provided.
According to a seventh aspect of the present invention, there is provided a first optical resonator including a laser medium and a non-linear optical crystal for converting an oscillated laser beam of the laser medium into its harmonic, and a second optical resonator in which only the harmonic resonates. A multi-reflecting unit that multi-reflects the harmonic and transmits the harmonic in a portion of the second optical resonator through which only the harmonic passes, and transmits the multi-reflecting unit through the multi-reflecting unit. And extracting the higher harmonics out of the second optical resonator.

Here, the first optical resonator comprises a first total reflection mirror, the nonlinear optical crystal, a harmonic separator for reflecting only the harmonic, the laser medium, a Q switch, and a second total reflection mirror. The second optical resonator includes the first total reflection mirror, the nonlinear optical crystal, the harmonic separator, the first optical axis adjustment mirror, the multiple reflection unit, the second optical axis adjustment mirror, and the third optical resonator.
It may be constituted by a total reflection mirror.

In order to achieve the above object, a fourth aspect of the present invention is provided.
According to a ninth aspect of the present invention, there is provided an optical resonator comprising: an optical resonator for confining a laser beam; and a multiple reflector for multiple-reflecting a laser beam in the optical resonator by a partially transmitting mirror. Laser light from a laser light generator installed separately from the optical resonator is made incident on the optical resonator, and light transmitted through the partially transmitting mirror is taken out of the optical resonator.

Here, measuring means for measuring the light intensity of leaked light of one of the pair of resonator mirrors constituting the optical resonator for performing impedance matching, and a measured value of the measuring means. And control means for adjusting the distance between the pair of resonator mirrors so that the maximum value is obtained.

In order to achieve the above object, a fifth aspect of the present invention is provided.
The eleventh aspect of the present invention is an optical resonator that includes a nonlinear optical crystal that converts incident laser light into its harmonics and confine the laser, and that the laser light in the optical resonator is multiple-reflected to obtain the harmonics. A laser beam from a laser light generator installed separately from the optical resonator including the multiple reflection unit, and the laser beam is transmitted to the partial transmission mirror. Is taken out of the optical resonator.

Here, a Fabry-Perot resonator can be used as the optical resonator.

Also, a ring resonator can be used as the optical resonator.

Further, the ring resonator receives the incident laser light, and performs an AR coating that passes the fundamental wave and the harmonic of the incident laser light at 45 ° and an HR that reflects the harmonic. A first harmonic separator coated, the non-linear optical crystal, a second harmonic separator having substantially the same characteristics as the first harmonic separator, a first optical axis adjusting mirror, the multiple reflection section, The optical axis adjusting mirror and the total reflection mirror may be arranged in a ring shape.

In order to achieve the above object, a sixth aspect of the present invention is provided.
A fifteenth aspect of the present invention is an optical element configured by alternately stacking a first anisotropic uniaxial crystal and a second anisotropic uniaxial crystal, wherein the n-th anisotropic uniaxial crystal is an n-th optical element. The moving distance of the extraordinary light source in one crystal is proportional to ^{n n−1} , and in the second crystal, the main cross section including the wave vector of the second crystal forms an angle of 45 ° with the main cross section including the wave vector in the first crystal. It is a quarter-wave plate.

That is, according to the first to fifth aspects of the present invention, it is an object of the present invention to provide an optical resonator for confining a laser beam and a laser beam partially transmitted through the resonator. This is achieved by a multiplex laser light generating device which is constituted by a portion which is multiply reflected by a mirror, and wherein the transmitted light of the partially transmitting mirror is taken out of the resonator.

Similarly, an object of the present invention is to provide an optical element comprising a first anisotropic uniaxial crystal and a second anisotropic uniaxial crystal alternately stacked according to the sixth embodiment of the present invention. The moving distance of the extraordinary ray in the n-th first crystal from the light incident side is proportional to ^{n n−1} , and the second crystal has a main cross section including the wave number vector in the first crystal. This is achieved by a multi-laser light generating element characterized in that it is a quarter-wave plate which forms an angle of 45 ° with the main section including the wave number vector.

The device according to the first to fifth aspects of the present invention provides a multiple reflection of the light confined therein in the optical resonator, and a part of the light transmitted at each reflection. It is structured to be taken out of the resonator. The resonator may be a laser resonator including a laser medium therein, or may be a so-called external resonator configured to receive light from a separately installed laser light generator. The structure of the resonator may be a so-called Fabry-Perot resonator that reciprocates light between two mirrors, or a ring resonator in which light propagates in one direction through an annular optical path including three or more mirrors. .

In the optical element according to the sixth aspect of the present invention,
The incident light is split into two polarized lights whose vibration directions are orthogonal to each other by birefringence in the first crystal of the first stage, and both of them are converted into circularly polarized light in the subsequent second crystal. First of the second stage
The crystal is again split into two beams by birefringence to form four beams. By repeating this, finally the interval δ ₁ /
Generate 2 ^n-1 n parallel beams. Here, δ ₁ is the distance between the beams divided by the first crystal of the first stage.

[0030]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 shows the configuration of an apparatus according to a first embodiment of the present invention to which the first embodiment of the present invention is applied. In the figure, reference numeral 1 denotes Nd: YAG (Nd
^{3 +} -doped Yttrium Aluminum Garnet), which is excited by an excitation light source (semiconductor laser) not shown in FIG. 1 to generate a laser beam having a wavelength λ = 1046 nm. Numerals 2 and 3 are total reflection mirrors for constituting a resonator, and 4-1 and 4-2 are mirrors for multiple reflection of laser light in the resonator. Reference numeral 5 denotes a partially transmitting surface of the mirrors 4-1 and 4-2. Reference numeral 6 denotes a transmission surface of the mirrors 4-1 and 4-2, which is provided with an anti-reflection (AR) coating.
Reference numerals 7-1 and 7-2 denote optical axis adjusting mirrors.

In this embodiment, the laser light emitted from the laser medium 1 reciprocates between the mirrors 2 and 3 and is reflected 16 times by the mirrors 4-1 and 4-2 for each reciprocation, thereby providing 16 laser light beams. Is divided into

The transmittance T of the partially transmitting surface 5 of the mirrors 4-1 and 4-2 is determined as follows. In the case where T is small, the ratio L of light extracted outside until the light emitted from the laser medium 1 in the right direction in the drawing returns to the laser medium 1 again is as follows.

[0034]

(Equation 3)

Is represented by Here, n is the number of reflections.

In a normal laser resonator configuration, an output mirror (for example, the mirror 3) has an appropriate transmittance instead of a multiple reflection portion, and a laser beam is extracted outside. Therefore, in determining the transmittance T of the partial transmission surface 5,
First, it is necessary to consider that L in the above equation (3) is set to a value close to the optimum transmittance (normally 5 to 10%). The next thing to consider is the uniformity of the intensity of the split beams. In this embodiment, the intensity of the light returning to the laser medium 1 is lower than that of the light exiting the laser medium 1 by L. Therefore, the intensity of the divided beam also has a width corresponding to L at the maximum and the minimum. Therefore, T must be determined so that this width, that is, the uniformity has a predetermined value. In the present embodiment,
In order to set the degree to 5%, T = 5/16 = 0.3%.

(Second Embodiment) FIG. 2 shows the configuration of an apparatus according to a second embodiment of the present invention, which is another example to which the first embodiment of the present invention is applied. Hereinafter, the same numbers in the respective drawings represent the same names. Here, reference numeral 8 denotes a multiple reflection slab for internally reflecting a laser beam, 9 denotes a partial transmission surface of the multiple reflection slab 8, and 10 denotes a transmission surface of the multiple reflection slab 8.
Partial transmission surface 9 and transmission surface 10 are provided on both surfaces of multiple reflection slab 8.
Are provided respectively.

This embodiment is completely the same in function as the first embodiment shown in FIG. 1 except that a multi-reflection slab 8 is used instead of using two mirrors in the multi-reflection section. The partial transmission surface 10 of the multiple reflection slab 8 is coated with the transmittance T determined by the same method as in the first embodiment, and the transmission surface 10 is coated with an AR coating.

(Third Embodiment) FIG. 3 shows the configuration of an apparatus according to a third embodiment of the present invention to which the second embodiment of the present invention is applied. In the first embodiment of the present invention, the laser light (fundamental wave) generated by the laser resonator is divided. On the other hand, in the second embodiment of the present invention, a fundamental wave (λ = 1064 nm) is converted to a second harmonic (λ = 5
32 nm), and the second harmonic is converted into a plurality of beams.

In FIG. 3, the same numbers as those in FIGS. 1 and 2 indicate the same names. Numeral 11 denotes a nonlinear optical crystal, in which KTiOPO ₄ (KTP) is used as an example. In addition, β-BaB ₂ O ₄ (BBO), LiB ₃ O ₅
(LBO), or MgO: LiNbO ₃ (MgO: LN) can also be used. The input / output surface 14 of the KTP crystal 11 is provided with an AR coating for the fundamental wave and the second harmonic. Reference numeral 13 denotes a harmonic separator (mirror) for reflecting only the second harmonic, and an AR coating is applied to the fundamental wave, and a high reflection (HR) coating is applied to the second harmonic.

Also, in this embodiment, the partially transmitting surface 9 of the multiple reflection slab 8 has an HR coating for the fundamental wave,
The second harmonic is coated with a transmittance T determined by the same method as in the first embodiment and the second embodiment. The transmission surface 10 is provided with an AR coating for both the fundamental wave and the second harmonic. In this embodiment, a part of the fundamental wave oscillating between the total reflection mirrors 2 and 3 is K
The TP crystal 11 converts the second harmonic into a second harmonic, and the second harmonic is confined between the total reflection mirror 3 and the harmonic separator 13. The second harmonic is repeatedly reflected by the multiple reflection slab 8, and the light transmitted through the multiple reflection slab 8 is extracted outside in four directions as a divided beam.

(Fourth Embodiment) FIG. 4 shows the configuration of an apparatus according to a fourth embodiment of the present invention, which is another example to which the second embodiment of the present invention is applied. In this embodiment, a Q switch 15 for outputting a laser beam as a pulse train is used.
Numeral 11 denotes a KTP crystal for converting a fundamental wave into its second harmonic, similar to the third embodiment shown in FIG. 3. In this embodiment, a crystal processed into a thin wafer is used. This K
The TP crystal 11 is disposed between the pair of multiple reflection mirrors 4-1 and 4-2. The input / output surface 14 of the KTP crystal 11 is provided with an AR coating for the fundamental wave and the second harmonic as in the third embodiment. Multiple reflection mirrors 4-1 and 4-2
The HR coating is applied to the fundamental wave and the AR coating is applied to the second harmonic. Therefore, in this embodiment, only the fundamental wave repeats multiple reflections, and all the second harmonics generated in each path are extracted to the outside. This wavelength conversion is performed by the KTP crystal 11
This is performed efficiently only when the fundamental wave is incident in the specific direction described above. Therefore, in the present embodiment, the divided beam is output only in two directions by adjusting the direction to the direction in which the divided beam is extracted.

(Fifth Embodiment) In the second embodiment of the present invention, the fundamental wave and the second harmonic wave are confined in one resonator, and the coating of each optical component takes into account two wavelengths. Needs to be However, there is a problem in that when characteristics for one wavelength are generally emphasized, characteristics for other wavelengths must be somewhat sacrificed. For example,
Since the first requirement in the embodiment of FIG. 3 is to increase the oscillation efficiency of the laser, the transmittance or reflectance of each optical component with respect to the fundamental wave is desirably as close as possible to 100%. On the other hand, for example, the partial transmission surface 9 of the multiple reflection slab 8 is required to have a predetermined transmittance for the second harmonic. Sometimes it is difficult to achieve.

On the other hand, in the third embodiment of the present invention, an improvement is made such that only the second harmonic passes through the multiple reflection portion. FIG. 5 shows a configuration of an apparatus according to a fifth embodiment of the present invention to which the third embodiment of the present invention is applied. A first resonator is formed by sequentially arranging the total reflection mirror 3, the KTP crystal 11, the harmonic separator 18, the laser medium 1, the Q switch 15, and the total reflection mirror 2 in a line from the top of the figure, and further comprises a total reflection mirror. 3, a second resonator is constituted by the KTP crystal 11, the harmonic separator 18, the first optical axis adjusting mirror 7-1, the multiple reflection slab 8, the second optical axis adjusting mirror 7-2, and the total reflection mirror 21. I have.

In this embodiment, the fundamental wave is transmitted to mirrors 2 and 3
Are confined only in the first resonator composed of on the other hand,
The second harmonic is reflected by the harmonic separator 18, passes through the multiple reflection slab 8, and reaches the total reflection mirror 21. That is, the second harmonic is confined in the second resonator constituted by the mirrors 3 and 21. Therefore, the partially transmitting surface 9 of the multiple reflection slab 8 considers only the second harmonic,
The coating may be performed so that the transmittance becomes a predetermined value. In addition, it goes without saying that the transmission surface 10, the mirrors 7-1 and 7-2, and the mirror 21 of the multiple reflection slab 8 only need to consider only the second harmonic.

(Sixth Embodiment) In the first, second, and third embodiments of the present invention described above, a laser beam is obtained by multiple-reflecting light confined in a laser resonator or a part thereof. Is to be divided. In these cases, delicate adjustments are required to satisfy two conditions such as oscillating the laser efficiently and optimizing the division of laser light. Therefore, in the fourth and fifth embodiments of the present invention described below, in order to avoid such difficult adjustment, the laser beam splitting resonator is completely separated from the laser resonator.

FIG. 6 shows a configuration of an apparatus according to a sixth embodiment of the present invention to which the fourth embodiment of the present invention is applied. In this example, a pair of resonator mirrors 2 constituting a laser beam splitting resonator
2 and 23, the first optical axis adjusting mirror 7-1, the multiple reflection mirrors 4-1 and 4-2, and the second optical axis adjusting mirror 7
-2, and a power meter 24 and a controller 25 outside the resonator mirror 23.

In the case of this configuration, laser light from a separately installed laser light generator (laser resonator: not shown) is incident on an optical resonator for beam splitting. Therefore,
The incident laser light incident from the resonator mirror 22 may be a fundamental wave or a second harmonic generated by another wavelength converter. Each of the resonator mirrors 22 and 23 is provided with an HR coating for incident laser light.

In this embodiment, the resonator mirrors 22, 2
It is necessary to adjust the interval of No. 3 to perform impedance matching. The impedance matching in this case is
The light enters the resonator, is reflected by the mirror 23, and is returned to the mirror 2 again.
This is a condition in which the phase of the light exiting the resonator from the position 2 cancels each other with a phase difference of exactly 180 ° from the phase of the light directly reflected by the mirror 22, and substantially all of the light is absorbed into the resonator. Under this condition, the energy of the light stored in the resonator becomes maximum, so that the intensity of the light slightly transmitted through the mirror 23 also becomes maximum. Therefore, the power (light intensity) of the leaked light from the mirror 23 is measured by a power meter (photometer) 24, and the mirror 23 is moved so that the measured value is maximized, so that the distance between the mirrors 22 and 23 is reduced. Adjust. The controller 25 adjusts the position of the mirror 23 in response to a signal from the power meter 24 in order to perform the automatic adjustment. The light stored in the resonator in this manner is repeatedly reflected by the multiple reflection portions of the multiple reflection mirrors 4-1 and 4-2, and the light transmitted through the partial transmission surface 5 is extracted to the outside as split laser light. .

(Seventh Embodiment) In the apparatus according to the above-described fourth embodiment of the present invention, the laser beam splitting resonators are completely independent of the laser resonators, and can be individually optimized. This is advantageous. However, there is a problem that impedance matching means (23, 24, 25) for storing the fundamental wave in the resonator as described above is indispensable. In addition, since impedance matching is established for a specific wavelength width, a condition that the wavelength width of the incident laser light must match the specific wavelength width is also required.

On the other hand, the fifth embodiment of the present invention can solve such a problem. FIG. 7 shows the configuration of an apparatus according to a seventh embodiment of the present invention to which the fifth embodiment of the present invention is applied. In the drawing, reference numerals 26 and 27 denote mirrors (harmonic separators) constituting a laser beam splitting resonator. The incident laser light as a fundamental wave is subjected to an AR coating, and the second harmonic is subjected to an HR coating. . The KTP crystal 11, the first optical axis adjusting mirror 7-1, the multiple reflection mirrors 4-1 and 4-2, and the second optical axis adjusting mirror 7-2 are arranged between these mirrors 26 and 27. .

Therefore, in this embodiment, the fundamental wave enters the resonator from the mirror 26 and the second wave
The fundamental wave, which has been converted to a higher harmonic wave and has not been converted, is a multiple reflection mirror
-1, 4-2, out of the resonator through the mirror 27. Therefore, impedance matching for storing the fundamental wave in the resonator is unnecessary. On the other hand, the second harmonic generated in the KTP crystal 11 reciprocates in the resonator and is output as a split beam from the partial transmission surface 5 of the multiple reflection mirrors 4-1 and 4-2.

(Eighth Embodiment) FIG. 8 shows the configuration of an apparatus according to an eighth embodiment of the present invention, which is another example to which the fifth embodiment of the present invention is applied. This embodiment differs from that of FIG. 7 in that the resonator is a ring resonator. Mirror 28,2
Reference numeral 9 denotes an AR coating that passes the fundamental wave and an HR coating that reflects the second harmonic, respectively, for the 45 ° incident fundamental wave and the second harmonic.

With this configuration, the fundamental wave enters the resonator from the mirror 28 and is converted into the second harmonic by the KTP crystal 11, and the unconverted fundamental wave exits the resonator through the mirror 29. On the other hand, the second harmonic generated in the KTP crystal 11 is reflected by the mirror 29, the first optical axis adjusting mirror 7-1, the multiple reflection mirrors 4-1 and 4-2, and the second optical axis adjusting mirror 7-2. , The total reflection mirrors 30-1 and 30-2 and the mirror 28, and are stored in the ring resonator, and the multiple reflection mirrors 4-1 and 4-
The beam is output from the partial transmission surface 5 as a split beam. In this case, since the light propagates in the resonator in one direction (clockwise), the split beam is output in two directions as shown in FIG.

(Ninth Embodiment) FIG. 9 shows the configuration of a multiplex laser generator according to a ninth embodiment of the present invention to which the sixth embodiment of the present invention is applied. In the present embodiment, as an example, calcite is used as the first crystal and quartz is used as the second crystal, and the incoming and outgoing polished surfaces of these crystals are overlapped in a so-called optical contact state. The incident light is preferably linearly polarized,
It may be circularly polarized light or light whose polarization plane changes randomly. In the present embodiment, as an example, the wavelength λ = 532
It is assumed that linearly polarized light of nm is incident.

In FIG. 9, reference numerals 31, 32 and 33 denote the first crystal, 3
Reference numerals 4 and 35 are second crystals. Then, as shown in FIG. 9, the first crystal 31, the second crystal 34, the first crystal 32,
It is formed by connecting the crystal 35 and the first crystal 33 in this order. The direction of the main section including the wave vector of the first crystal (the direction corresponds to the propagation direction of ordinary light) is 0 °, and the direction of the main section including the wave vector of the second crystal is 45 °. The solid line at the top of FIG. 9 shows the directions of these main sections when the element is viewed from the left. The double arrow at the bottom of FIG. 9 indicates the oscillation direction of the linearly polarized light in each part, and the circle indicates circularly polarized light.

The incident light enters the first crystal 31 with the vibration direction set at 45 °. The incident light propagates in the first crystal 31 as ordinary light having a vibration direction of 90 ° and extraordinary light having a vibration direction of 0 °. As the light travels in the crystal, both the ordinary light and the extraordinary light are separated by birefringence. This separation angle ρ is

[0058]

Represented by Equation 4] [rho = arctan ^{_{[(n o / n e) 2}} tan θ c ] - [theta] _c (4). Where n _o and n _e are each ordinary and extraordinary refractive index of, theta _c is the angle ordinary propagation direction with respect to the optical axis. refractive index n _e is 1.662 for ordinary light of calcite in lambda = 532 nm, the refractive index n _e for extraordinary light is 1.
488. When these values are substituted into the above equation (4) and calculated, the separation angle ρ becomes maximum at θ _c = 42 °, and at this time, ρ = 6.32 °.

In order to split light efficiently with a small crystal, in the present embodiment, θ =
This crystal is processed and polished so as to be 42 °. The thickness t ₁ of the first crystal 31 (same for 32 and 33) is

[0060]

Calculated by t ₁ = δ / tan ρ (5) Here, δ is the shift amount of extraordinary light. In this embodiment, since δ of the first stage is set to 4 mm, t
₁ = 36 mm.

The two parallel beams that have exited the first crystal 31 are λ
The light enters the second crystal 34 as a / 4 plate. This λ / 4 plate divides linearly polarized light into ordinary light and extraordinary light, and makes the phase difference between both ordinary light and extraordinary light an odd multiple of π / 2. Also,
In this case, δ = 0 by setting θ _c = 90 °. Since the vibration direction of the light that has exited the λ / 4 plate 34 makes a circular motion, this is called circularly polarized light. Since the light exiting the first crystal 31 is linearly polarized light having a vibration direction of 0 ° and 90 °, the main crystal section of the second crystal 34 has a direction of 45 ° in order to split the linearly polarized light into ordinary light and extraordinary light. And The thickness t ₂ of the λ / 4 plate 34 (same for 35) is

[0062]

(Equation 6)

Is calculated by Here, k is 0 and a positive integer.

In this embodiment, λ = 0.53 in the above equation (5)
As the refractive index of 2 × 10 ^-3 mm and crystal, n _o = l.
5462, n _e = I. By substituting 5553 and setting k = 50, t _{2 was set to} 1.48 mm.

The parallel beam split by the second crystal 34 into circularly polarized light is incident on the first crystal 32 in the second stage.
The circularly polarized light rotates in the direction of oscillation, so that when it enters the crystal 32, it is equally divided into ordinary light and extraordinary light, and each beam is split into two to generate four parallel beams. In order to set the shift amount (ie, beam interval) δ of the extraordinary light in the second stage to の of δ in the first stage, the thickness of the first crystal 32 in the second stage is t
₁ = 36/2 = 18 mm. Four linearly polarized beams emitted from the first crystal 33 in the second stage are similarly converted into circularly polarized light by the second crystal 35 in the second stage.

The third stage is only the first crystal 33 having a thickness of t ₁ = 36/4 = 9 mm, and the parallel beam emitted from the second crystal 35 of the second stage is the first crystal 33 of the third stage. The beam is further divided into two, and finally eight parallel beams of δ = 1 mm are generated.

In the present embodiment, the thickness t ₁ of the first crystal is set to 毎 for each step in order to adjust the shift amount δ of the extraordinary light. In this method, however, t ₁ becomes smaller as δ becomes smaller. Sometimes it is too small to make. In that case, t ₁
It is also possible to adjust δ by changing θ _c instead of (see equations (4) and (5) above). In addition, n _o
It is also possible to use, for example, quartz as the first crystal, for which the difference between n and n _e is small.

[0068]

As described above, according to the present invention,
It is possible to provide a laser beam splitting device having a simple structure and not causing a decrease in beam quality. Among them, the first to fifth embodiments of the present invention are suitable for obtaining a small number of split beams having a relatively large inter-beam distance δ, and the sixth embodiment of the present invention is for splitting light beams having a small δ. Suitable for outbreaks.
Therefore, when generating a multi-segmented beam with a small δ, a great effect can be obtained by combining both.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing an apparatus according to a first embodiment of the present invention to which the first embodiment of the present invention is applied.

FIG. 2 is a configuration diagram schematically showing an apparatus according to a second embodiment of the present invention to which the first embodiment of the present invention is applied.

FIG. 3 is a configuration diagram schematically showing an apparatus according to a third embodiment of the present invention to which the second embodiment of the present invention is applied.

FIG. 4 is a configuration diagram schematically showing an apparatus according to a fourth embodiment of the present invention to which the second embodiment of the present invention is applied.

FIG. 5 is a configuration diagram schematically showing an apparatus according to a fifth embodiment of the present invention to which the third embodiment of the present invention is applied.

FIG. 6 is a configuration diagram schematically showing an apparatus according to a sixth embodiment of the present invention to which the fourth embodiment of the present invention is applied.

FIG. 7 is a configuration diagram schematically showing an apparatus according to a seventh embodiment of the present invention to which the fifth embodiment of the present invention is applied.

FIG. 8 is a configuration diagram schematically showing an apparatus according to an eighth embodiment of the present invention to which the fifth embodiment of the present invention is applied.

FIG. 9 is a configuration diagram schematically showing a multiplex laser generation element according to a ninth embodiment of the present invention to which the sixth embodiment of the present invention is applied.

[Explanation of symbols]

Reference Signs List 1 laser medium 2, 3, 2l total reflection mirror 22, 23 mirror (HR coat mirror) 4-1, 4-2 multiple reflection mirror 5, 9, 19 partial transmission surface 6, 10, 20 transmission surface 7-1, 7-2 Mirror for optical axis adjustment 8 Multiple reflection slab 11 KTP crystal (non-linear optical crystal) 13, 18, 26, 27, 28, 29 Harmonic separator (mirror) 15 Q switch 24 Power meter 25 Controller 30-1, 30 -2 Total reflection mirror 31, 32, 33 First crystal 34, 35 Second crystal

Claims (15)

[Claims] 1. An optical resonator including a laser medium, for confining laser light emitted from the laser medium, and a multiple reflection unit for multiple-reflecting the laser light in the optical resonator by a partially transmitting mirror. A multiplex laser light generator, wherein light transmitted through a transmission mirror is extracted outside the optical resonator. 2. The apparatus according to claim 1, wherein said partially transmitting mirror is a pair of opposed multiple reflecting mirrors having a partially transmitting surface inside and a transmitting surface outside. Generator. 3. An apparatus according to claim 1, wherein said partial transmission mirror is a multiple reflection slab that transmits a part of the oscillation laser light of said laser medium. 4. An optical resonator that includes a laser medium and a nonlinear optical crystal that converts an oscillation laser beam of the laser medium into its harmonic, and confine the oscillation laser. A multi-reflecting unit configured to transmit the harmonic, and extracting the harmonic transmitted through the multi-reflecting unit out of the optical resonator. 5. The device according to claim 4, wherein the multiple reflection unit includes a partial transmission surface that transmits the harmonic and reflects a fundamental wave, and a transmission surface that transmits the harmonic and the fundamental wave. A multiple laser light generator comprising a multiple reflection slab on each side. 6. An apparatus according to claim 4, wherein said multiple reflection section comprises a pair of multiple reflection mirrors which face each other with said nonlinear optical crystal therebetween and transmit said harmonic. Laser light generator. 7. A first optical resonator including a laser medium and a non-linear optical crystal for converting an oscillation laser beam of the laser medium into a harmonic thereof, and a second optical resonator that resonates only the harmonic. A multi-reflection unit that multiple-reflects the harmonic and transmits the harmonic in a portion of the second optical resonator where only the harmonic passes, A multiplex laser light generator, wherein the laser light is taken out of the second optical resonator. 8. The device according to claim 7, wherein the first optical resonator includes a first total reflection mirror, the nonlinear optical crystal, a harmonic separator that reflects only the harmonic, the laser medium, a Q switch, and A second total reflection mirror, wherein the second optical resonator includes the first total reflection mirror, the nonlinear optical crystal, the harmonic separator, a first optical axis adjusting mirror, the multiple reflection unit, and a second optical axis. A multiplex laser light generator, comprising: an adjustment mirror and a third total reflection mirror. 9. An optical resonator comprising: an optical resonator for confining a laser beam; and a multiple reflector for multiple-reflecting the laser beam in the optical resonator by a partially transmitting mirror, wherein the optical resonator including the multiple reflector is A multiplex laser light generator, wherein laser light from a laser light generator separately provided is incident on the optical resonator, and light transmitted through the partially transmitting mirror is extracted out of the optical resonator. 10. The measuring device according to claim 9, wherein the light intensity of leaked light of one of the pair of resonator mirrors constituting the optical resonator is measured for impedance matching. And a control means for adjusting the distance between the pair of resonator mirrors so that the measured value of the measuring means is maximized. 11. An optical resonator that includes a nonlinear optical crystal for converting incident laser light into its harmonics and confine the laser, and a multiple reflection that multiple-reflects the laser light in the optical resonator and transmits the harmonics. And a laser beam from a laser light generator installed separately from the optical resonator including the multiple reflection unit. The laser beam is incident on the optical resonator. A multiplex laser light generator characterized by being taken out. 12. The multiplex laser light generator according to claim 11, wherein a Fabry-Perot resonator is used as said optical resonator. 13. The multiplex laser light generating device according to claim 11, wherein a ring resonator is used as said optical resonator. 14. The apparatus according to claim 13, wherein the ring resonator receives the incident laser light and receives the incident laser light.
AR coating that passes the fundamental wave and the harmonic wave of the incident laser beam at an angle of °° and HR that reflects the harmonic wave
A first harmonic separator coated, the non-linear optical crystal, a second harmonic separator having substantially the same characteristics as the first harmonic separator, a first optical axis adjusting mirror, the multiple reflection section,
A multiplex laser light generator, wherein an optical axis adjusting mirror and a total reflection mirror are arranged in a ring shape. 15. An optical element comprising a first anisotropic uniaxial crystal and a second anisotropic uniaxial crystal alternately stacked, wherein the n-th anomalous light source in the first crystal from the light incident side. The second crystal has a moving distance proportional to 移動ⁿ⁻¹ , and the second crystal has a quarter-wave plate whose main cross section including the wave vector forms an angle of 45 ° with the main cross section including the wave vector in the first crystal. A multiplex laser light generating element, characterized in that: