JPH11274664A - Multistage amplification laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set the intensity distribution of laser light to be uniform without enlarging a device and increasing cost. SOLUTION: When exciting laser light beams outputted from an exciting laser oscillator are sequentially amplified by respective amplifiers 5 and 6, total reflection coating 22 and reflection prevention coating 23 are given to an optical mirror 20 branching exciting laser light beams to the pre-amplifier 5 in a stage before the main amplifier 6. A part of exciting laser light beams is spatially cut from a beam cross section and it is made incident on the pre- amplifier 5. Thus, exciting laser light beams which have uniform intensity distribution that is not affected by the intensity distribution of the Gaussian type of exciting laser light and whose beam forms are matched with the form of the exciting area of the pre-amplifier 5 are made incident on the pre-amplifier 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-stage amplification laser device for sequentially amplifying a dye laser beam output from a dye laser oscillator by a multi-stage amplifier.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram of a multi-stage amplification laser device. The dye laser oscillator 1 has a dye flow cell 2 in which a dye solution as a laser medium flows, and a high reflection mirror 3 as a laser resonator and an output mirror 4 are arranged with the dye flow cell 2 interposed therebetween.

A preamplifier 5 and a main amplifier 6 are arranged on the laser output optical path of the dye laser oscillator 1. Each of the preamplifier 5 and the main amplifier 6 includes a dye flow cell through which a dye solution flows and a laser resonator.

On the other hand, an excitation laser oscillator 7 is provided,
The partial reflection mirrors 8 and 9 and the total reflection mirror 10 are arranged on the laser output optical path of the excitation laser oscillator 7.

Each of the partial reflection mirrors 8 and 9 splits the excitation laser beam output from the excitation laser oscillator 7 and separates the excitation laser beam from the excitation laser oscillator 7.
And a preamplifier 5.

The total reflection mirror 10 totally reflects the remaining pump laser light transmitted through each of the partial reflection mirrors 8 and 9 and guides it to the preamplifier 6. With such a configuration, the excitation laser light output from the excitation laser oscillator 7 has its excitation energy branched off by the respective partial reflection mirrors 8 and 9, and the dye flow cell 2 of the dye laser oscillator 1 and the preamplifier 5, and the remaining pump laser light is totally reflected by the total reflection mirror 10 and guided to the main amplifier 6.

As described above, when the excitation laser beam is incident on the dye flow cell 2 of the dye laser oscillator 1, the dye solution flowing through the dye flow cell 2 is excited, and between the high reflection mirror 3 as a laser resonator and the output mirror 4. Laser resonance occurs, and dye laser light is output.

The dye laser light first enters the preamplifier 5, but the preamplifier 5 is excited by the excitation laser light to excite the dye solution at the same timing as the dye laser light enters. The dye laser light is amplified and output.

The amplified dye laser light is incident on the next main amplifier 6, and also in this main amplifier 6, the dye solution is excited by the excitation laser light incident in accordance with the incident timing of the dye laser light. Therefore, this main amplifier 6
Further amplifies and outputs the dye laser light.

In such a multi-stage amplification laser device,
Each of the incident laser beams from the partial reflection mirror 9 to the preamplifier 5 and from the total reflection mirror 10 to the main amplifier 6 emits a pump laser beam having a beam diameter of, for example, 200 mm.
The light is focused in accordance with each of the excitation regions 6, specifically, the excitation region of the preamplifier 5 (length 1 mm × width 10 mm) and the excitation region of the main amplifier 6 (length 2 mm × width 20 mm).

However, since the excitation laser beam has a Gaussian intensity distribution, if it is collected as it is,
The intensity distribution of the dye laser light amplified in the preamplifier 5 and the main amplifier 6 is also affected by the intensity distribution of the excitation laser light, and the intensity distribution of the dye laser light finally amplified and output is not uniform. I will.

In order to eliminate such non-uniform intensity distribution of the dye laser light, as shown in FIG.
On the optical path from the optical amplifier to the preamplifier 5 and on the optical path from the total reflection mirror 10 to the main amplifier 6, callide scopes 11 and 12 for uniformizing the intensity distribution of the pump laser light are arranged.

[0013]

However, in order to make the intensity distribution of the pump laser light incident on the preamplifier 5 and the main amplifier 6 uniform as described above, each kaleidoscope 1
The arrangement of 1 and 12 has a problem that the cost is increased and the size of the apparatus is increased. Therefore, the present invention
It is an object of the present invention to provide a multi-stage amplifying laser device capable of achieving a uniform intensity distribution of laser light without increasing the size and cost of the device.

[0014]

According to the first aspect of the present invention, amplifiers are arranged in multiple stages in a laser output optical path of a laser oscillator, and a laser beam output from the laser oscillator is input to these amplifiers by exciting laser light. In a multi-stage amplifying laser device that sequentially amplifies each amplifier, an optical system that branches the pump laser light to an amplifier in a stage preceding the last stage amplifier is:
This is a multistage amplifying laser device that has a function of spatially cutting out a part of a beam section of the excitation laser beam from the beam cross section.

According to the second aspect of the present invention, in the optical system disposed in the amplifier before the final stage, a predetermined portion of the light-transmitting mirror is provided with a total reflection coating and another portion is provided with an antireflection coating. Things.

According to the third aspect, the total reflection coat is formed so that the beam shape of the branched pump laser light matches the shape of the pump region of the amplifier. According to claim 4, the shape of the total reflection coat is such that the vertical length is made equal to the vertical length of the excitation region of the amplifier and the horizontal length is formed to be ^1/2 times the horizontal length of the excitation region. It is.

According to the fifth aspect, the total reflection coat is formed so as to correspond to the high intensity portion of the excitation laser light having a Gaussian intensity distribution. According to the first aspect, when sequentially amplifying the laser light output from the laser oscillator by each amplifier, the optical system that splits the pump laser light into an amplifier preceding the last amplifier is provided with a beam of the excitation laser light. A part thereof is spatially cut out from the cross section and is incident on the amplifier in the preceding stage. Thus, even if the excitation laser beam has an intensity distribution, an amplified laser beam which is not affected by the intensity distribution can be obtained by cutting out a part of the excitation laser beam.

According to the second aspect, the optical system that spatially cuts a part of the excitation laser light from the beam cross section is as follows:
By applying a total reflection coat to a predetermined portion of the light-transmitting mirror and applying an antireflection coat to the other portion, an excitation laser beam is obtained by spatially cutting out a part of the total reflection coat.

According to the third aspect, the total reflection coat is
The beam shape of the branched pump laser light is made to match the shape of the pumping region of the amplifier, and is incident on the amplifier at the preceding stage. According to the fourth aspect, in order to match the beam shape of the branched pump laser light with the shape of the pumping region of the amplifier, the shape of the total reflection coat, for example, the vertical length matches the vertical length of the pumping region of the amplifier. And the horizontal length is set to 2 of the horizontal length of the excitation region.
Formed ^1/2 times.

According to the fifth aspect, the total reflection coat is
By forming the excitation laser light having a Gaussian intensity distribution corresponding to a high intensity portion of the excitation laser light, an amplified laser light which is not affected by the intensity distribution can be output.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. 4 and 5 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 1 is a configuration diagram of a multi-stage amplification laser device.

A partial reflection mirror 8, an optical mirror 20, and a total reflection mirror 10 are arranged on a laser output optical path of the excitation laser oscillator 7. Of these, the optical mirror 20
Divides the pump laser light into the preamplifier 5 at a stage before the main amplifier 6 at the final stage, and has a function of spatially cutting a part of the beam from the beam cross section of the pump laser light.

As shown in FIG. 2, the specific structure of the optical mirror 20 is such that a total reflection coating 22 is applied to one surface of a light-transmitting mirror main body 21 and an antireflection coating 23 is applied to other portions. It has been given.

That is, when the optical mirror 20 is viewed from the front, as shown in FIG.
Is provided with a rectangular total reflection coat 22 in almost the center portion thereof, and an antireflection coat 23 in other portions.

The total reflection coat 22 is formed in a shape that matches the beam shape of the branched excitation laser light with the shape of the excitation area (for example, 1 mm long × 10 mm wide) of the preamplifier 5.

More specifically, the shape of the total reflection coat 22 is such that the vertical length matches the vertical length of the excitation region of the preamplifier 5 and the horizontal length is 2 ¹ of the horizontal length of the excitation region of the preamplifier 5. ^{/ 2} times as large.

The total reflection coat 22 is formed at a position corresponding to a high intensity portion in the Gaussian intensity distribution of the excitation laser light as shown in FIG. 3 (b). on the other hand,
The kaleidoscope 11 arranged on the optical path from the partially reflecting mirror 9 to the preamplifier 5 is omitted.

Next, the operation of the above-configured apparatus will be described. Excitation laser light output from the excitation laser oscillator 7 is split in excitation energy by the partial reflection mirror 8 and the optical mirror 20, and the dye laser oscillator 1
, And the remaining pump laser light is totally reflected by the total reflection mirror 10 and guided to the main amplifier 6.

At this time, as shown in FIG. 3B, the optical mirror 20 reflects a portion having a high intensity distribution of the excitation laser beam at a reflection angle of 45 ° by the total reflection coat 22 and guides it to the preamplifier 5. .

At the same time, the total reflection coat 22 of the optical mirror 20 has the vertical length equal to the vertical length of the excitation region of the preamplifier 5 and the horizontal length as described above. because of being formed into two ^half oblong, cut excitation laser beam of the matched beam shape before the shape of the excitation region of the preamplifier 5 leading to a preamplifier 5.

Accordingly, the preamplifier 5 has a uniform intensity distribution which is not affected by the Gaussian intensity distribution of the pump laser light, and has a beam shape which matches the shape of the excitation region of the preamplifier 5. Light enters.

On the other hand, the remaining excitation laser light totally reflected by the total reflection mirror 10 is made uniform in its intensity distribution by the kaleidoscope 12 and enters the main amplifier 6. Thus, when the excitation laser beam is incident on the dye flow cell 2 of the dye laser oscillator 1, the dye solution flowing through the dye flow cell 2 is excited, and laser resonance occurs between the high reflection mirror 3 as a laser resonator and the output mirror 4. Then, a dye laser beam is output.

The dye laser beam is incident on the preamplifier 5, and the preamplifier 5 excites the dye solution by the excitation laser beam incident from the total reflection coat 22 at the same timing as the incident timing of the dye laser beam. Therefore, the dye laser light is amplified and output.

The amplified dye laser light is incident on the next main amplifier 6, and also in this main amplifier 6, the dye solution is excited by the excitation laser light incident in accordance with the incident timing of the dye laser light. Therefore, this main amplifier 6
Further amplifies and outputs the dye laser light.

As described above, in one embodiment,
When the pump laser light output from the pump laser oscillator 7 is sequentially amplified by the amplifiers 5 and 6, the optical mirror 20 that splits the pump laser light into the preamplifier 5 preceding the main amplifier 6 passes through the pump laser light. A part of the laser beam is spatially cut out from the beam cross-section to be incident on the preamplifier 5, so that even if there is an intensity distribution in the pump laser light, the part is cut out to amplify it without being affected by the intensity distribution. Dye laser light can be output.

In this case, the optical mirror 20 has a structure in which a total reflection coat 22 is applied and an antireflection coat 23 is applied to other parts. The length of the excitation region of
In addition, since the horizontal length is formed to be ^21/2 times the horizontal length of the pumping region, the beam shape of the branched pump laser light is adjusted by the preamplifier 5.
Can be matched to the shape of the excitation region.

In addition, since the total reflection coat 22 is formed corresponding to the high intensity portion of the excitation laser light having the Gaussian intensity distribution, the amplified dye laser light is not affected by the intensity distribution. Can be output.

Therefore, it is not necessary to provide a means for equalizing the intensity distribution of the excitation laser light such as a kaleidoscope for the amplifier 5 in the preceding stage except for the final stage, so that the apparatus can be prevented from being enlarged and the cost can be reduced. I can do it.

The present invention is not limited to the above embodiment, but may be modified as follows. For example, in the above-described embodiment, in order to reflect the excitation laser light at an incident angle of 45 ° and guide it to the preamplifier 5, the total reflection coat 2
In the shape of No. 2, the vertical length was made equal to the vertical length of the pumping region of the preamplifier 5 and the horizontal length was formed to be ^21/2 times the horizontal length of the pumping region. The adjustment may be made according to the angle of incidence of light on the total reflection coat 22.

The total reflection coat 22 may be a partial reflection coat to adjust the intensity of the branched excitation laser light, that is, the distribution ratio. When adjusting the distribution ratio of the excitation laser light, for example, when increasing the distribution ratio to the preamplifier 5, the area of the total reflection coat 22 is formed large, and the branched excitation laser light is transmitted by an optical system such as a lens. What is necessary is just to form a reduced image.

Further, the above embodiment has been described with respect to a case where the present invention is applied to a two-stage amplifier. However, the present embodiment may be applied to a multi-stage amplified laser device having two or more stages. In this case, the total reflection coat 22 can be coped with by shifting the position to be formed for each step and shifting the position where the excitation laser light is cut out.

[0042]

As described above, according to the present invention, it is possible to provide a multi-stage amplifying laser device capable of achieving a uniform intensity distribution of laser light without increasing the size and cost of the device.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a multi-stage amplification laser device according to the present invention.

FIG. 2 is a configuration diagram of an optical mirror provided with a total reflection coating.

FIG. 3 is a specific configuration diagram of an optical mirror.

FIG. 4 is a configuration diagram of a conventional multi-stage amplification laser device.

FIG. 5 is a configuration diagram of a branch optical system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Dye laser oscillator, 2 ... Dye flow cell, 3 ... High reflection mirror, 4 ... Output mirror, 5 ... Preamplifier, 6 ... Main amplifier, 7 ... Excitation laser oscillator, 8 ... Partial reflection mirror, 10 ... Total reflection Mirror, 20: Optical mirror, 21: Mirror body, 22: Total reflection coating, 23: Anti-reflection coating.

Claims (5)

[Claims] 1. A multi-stage amplified laser in which amplifiers are arranged in multiple stages in a laser output optical path of a laser oscillator, and a laser beam output from the laser oscillator is sequentially amplified by each of the amplifiers by injecting an excitation laser beam into these amplifiers. In the apparatus, an optical system for branching the pump laser light into the amplifier at a stage preceding the amplifier at the final stage has a function of spatially cutting a part of the pump laser beam from a beam cross section thereof. Amplifying laser device. 2. An optical system disposed in an amplifier before a final stage, wherein a predetermined portion of a light-transmitting mirror is provided with a total reflection coating and another portion is provided with an antireflection coating. The multi-stage amplification laser device according to claim 1. 3. The multi-stage amplifying laser device according to claim 1, wherein the total reflection coat is formed so that the beam shape of the branched excitation laser beam matches the shape of the excitation region of the amplifier. 4. The shape of the total reflection coat is such that the vertical length is made to correspond to the vertical length of the excitation region of the amplifier, and the horizontal length is formed to be ^1/2 times the horizontal length of the excitation region. The multi-stage amplifying laser device according to claim 1, wherein: 5. The multi-stage amplifying laser device according to claim 1, wherein the total reflection coat is formed corresponding to a portion having a high intensity in the excitation laser light having a Gaussian intensity distribution.