JPH039593A - Laser apparatus - Google Patents

Abstract

PURPOSE:To make intensity distribution uniform by forming a first reflecting film of prescribed transmittivity on the incident surface of a reflector mirror formed of a light-transmitting medium having a prescribed refractive index and by forming a second reflecting film on the reverse surface opposite to said incident surface. CONSTITUTION:A laser output element 11 outputting a laser light P is provided, and a reflector mirror 12 having an incident surface inclined to the optical axis of this laser light P is provided. This reflector mirror 12 is formed of a light-transmitting body having a prescribed refractive index, and a first reflecting film 17 of prescribed transmittivity is formed on the incident surface. On the reverse side of the reflector mirror 12 being opposite to the incident surface, a second reflecting film 18 which reflects, at high reflectivity, a light falling on the first reflecting film 17 and transmitted therethrough and a light reflected on the reverse surface of this first reflecting film 17 is formed. Part of the laser light P is transmitted through the reflecting film 17, while part of it is reflected thereby, and the transmitted light is refracted in accordance with the refractive index of a light-transmitting medium and reflected on the reflecting film 18. This light falls on the reflecting film 17 at a position different from the position of incidence and part of it is transmitted therethrough, while part of it is thereby reflected. At this time, the reflected light and the transmitted light are parallel substantially, respectively. According to this constitution, the laser light reflected by the reflector mirror 12 is made uniform in the spatial distribution of the intensity of light.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a laser device.

(Prior Art) The main parts of a dye laser amplification device will be described below with reference to the drawings. As shown in FIG. 4, the dye laser amplifying device 1 has an excitation laser output section 2 that emits an excitation laser beam p, and there is a laser beam on the optical path of the excitation laser beam p output from the excitation laser output section 2. A reflecting mirror 3 is provided. This reflecting mirror 3 is arranged to be inclined at a predetermined angle with respect to the excitation laser beam p, and is configured to reflect the excitation laser beam p at a predetermined angle.

Further, the reflective surface of the reflective mirror 3 is formed of a dielectric multilayer film 4, and is designed to highly reflect the excitation laser beam p. Further, a cylindrical lens 5 is inserted on the optical path of the excitation laser beam p reflected by the reflection mirror 3. A dye cell 6 in which a dye laser medium is circulated is provided at a position where the laser light p focused by the cylindrical lens 5 is irradiated. This dye cell 6 is provided with a circulation device (not shown) that circulates the dye laser medium in the depth direction of the drawing.

Then, the output of the dye laser light incident from the direction indicated by the arrow is amplified by the dye solution excited by the irradiation with the excitation laser light p.

In the dye laser amplifying device 1 configured as described above, when the light intensity distribution is not uniform in the excitation laser output section 2 that generates the excitation laser light p, the light intensity distribution as shown in FIG. In this case, very strong light is irradiated in a small portion. When trying to sufficiently excite the dye cell 6 with the excitation laser intensity being non-uniform in this way, some of the dye laser medium irradiated with strong excitation light will
S E (AmphNed 5pontaneous
Emission: amplified spontaneous emission light) is emitted, and it has been difficult to output dye laser light with a uniform wavelength.

(Problems to be Solved by the Invention) In a dye laser amplification device, when the light intensity distribution of excited laser light is uneven, if a strong excitation laser light is irradiated on a part, ASE will occur from this part. This makes it difficult to increase the efficiency of laser amplification, and it is also difficult to output a single wavelength dye laser.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a laser device that can bring the intensity distribution of laser light outputted from a laser or light output section closer to a uniform state.

[Structure of the Invention] (Means for Solving the Problems) (1) A laser output section that outputs a laser beam is provided, a reflecting mirror having an incident surface inclined to the optical axis of the laser beam is provided, and this reflecting mirror is A first reflective film made of a transparent material having a predetermined refractive index and having a predetermined transmittance is formed on the incident surface, and the first reflective film is formed on the back side of the reflective mirror facing the incident surface.
The present invention provides a laser device in which a second reflective film is formed to reflect at a high reflectance the light that is incident on and passes through the first reflective film and the light that is reflected on the back surface of the first reflective film.

(2) An excitation laser output section is provided, a reflection mirror is provided with an incident surface inclined with respect to the optical axis of the excitation laser beam, and a dye cell is provided which is irradiated with the excitation laser beam that has passed through the reflection mirror. The mirror becomes a transparent body having a predetermined refractive index, and a first reflective film with a predetermined transmittance is formed on the incident surface,
On the back side of the reflective mirror facing the incident surface, there is a second reflective film that reflects the light that is incident on the first reflective film and reflected on the back surface of the first reflective film of the anti-mirror with a high reflectance of 9. It is in the formed laser device.

Ru.

(Function) (1) A portion of the laser light incident on the first reflective film of the reflecting mirror is reflected with a predetermined reflectance, and a portion of the laser light that is not reflected is transmitted with a predetermined transmittance. . The laser beam that has passed through the first reflective film is refracted according to the refractive index of the reflective mirror, and is reflected by the second reflective film. A portion of the laser light reflected by the second reflective film is emitted from a position different from the incident position of the first reflective film. This emitted light is first transmitted in parallel with the light reflected by the first reflective film.

On the other hand, the light component reflected by the second reflective film and then reflected by the inner surface of the first reflective film is refracted according to the refractive index of the reflective mirror and reflected by the second reflective film, causing the same reflection and reflection as described above. Repeat the transmission.

(2) A portion of the laser light incident on the first reflective film of the reflecting mirror is reflected with a predetermined reflectance, and a portion of the laser light that is not reflected is transmitted with a predetermined transmittance. The laser beam that has passed through the first reflective film is refracted according to the refractive index of the reflective mirror, and is reflected by the second reflective film. A portion of the laser light reflected by the second reflective film is emitted from a position different from the incident position of the first reflective film. This emitted light is first emitted in parallel with the light reflected by the first reflective film.

On the other hand, the light component that is highly reflected by the second reflective film and then reflected by the inner surface of the first reflective film is refracted again according to the refractive index of the reflective mirror and is highly reflected by the second reflective film, as described above. Repeats reflection and transmission.

In this way, the laser light whose light intensity is made uniform in one direction is incident on the dye cell, and uniform excitation can be achieved.

(Embodiment) An embodiment of the present invention will be described with reference to FIGS. 1 to 3. A dye laser amplifying device 10 shown in the figure has an excitation laser output section 11 that outputs an excitation laser beam p. Further, on the optical path of the output light of the excitation laser output section 11, a reflecting mirror 12 configured as described later is arranged. Further, a dye cell 13 is provided on the optical path of the excitation laser beam p reflected by the reflecting mirror 12. Then, the reflecting mirror 12 and the dye cell 13
A cylindrical lens 14 is inserted between the cylindrical lens 14 and the excitation laser beam p, which is adjusted so as to be in a defocus state at the position where it enters the dye cell 13. The laser output is amplified by transmitting the dye laser beam in the direction of the arrow through the dye cell 13 excited by the excitation laser beam p.

The structure of the reflecting mirror 12 will be explained below. This reflecting mirror 12 is made of a light-transmitting medium that can transmit the excitation laser beam p with high efficiency and has a predetermined refractive index, and the incident surface 15 and the back surface 16 facing the same have a certain degree of parallelism to each other. It is formed in parallel planes with. A first reflective film 17 made of a dielectric multilayer film having a predetermined reflectance (for example, 38.2%) is formed on the incident surface 15. A part of the excitation laser light p incident on the first reflective film 17 is reflected, and the excitation laser light component that is not reflected is transmitted.

On the other hand, a second reflective film 18 that substantially totally reflects the excitation laser beam P is formed on the back surface 16 facing the incident surface 15.

The reflecting mirror 12 configured in this way is mounted on a support base 19.
It is rotatably supported. Above reflection mirror 1
2 is supported by a pivot plate 20 rotatably supported on a support base 19. This support plate 2
0 has a hole for the support shaft in the vertical direction, and
A semicircular gear portion 21 is provided concentrically and integrally with this support shaft hole. A pivot shaft 22 is rotatably inserted into the hole for the support shaft. This pivot shaft 22
is provided integrally with the support base 19, and the reflection mirror 12 can rotate around this pivot shaft 22.

Further, a worm 23 is provided on the teeth of the gear portion 21 so as to constitute a worm gear. This worm 23 has both ends bearing portions 24 and 24, respectively.
The worm 23 is rotatably supported on a support base 19, and a handle 25 is provided at one end of the worm 23.

By operating the handle 25, the angle of the reflecting mirror 12 can be changed.

Hereinafter, the dye laser amplification device 10 configured as described above will be described.
The state in which the is activated will be explained. The excitation laser beam p outputted from the excitation laser output section 11 is transmitted to the reflection mirror 1.
The light enters the first reflective film 17 formed on the incident surface 15 of No. 2. The incident excitation laser beam p has the above reflectance (for example, 38
．． 2%) and is divided into a light component b1 that is reflected and a light component t1 that is transmitted as is. The reflected light component b1 is specularly reflected according to the arrangement angle of the reflecting mirror 12. Further, the transmitted light component t1 is refracted at a predetermined refractive index and reflected by the second reflective film 18 with high efficiency.

Then, the light component t1 is reflected from the second reflection film to the first reflection [1
7, and 38.2 of this light component t1
% is transmitted and exits from the first reflective film 17 as transmitted light b2. Further, a part of the light component t1 is reflected by the first reflective film 17, and is returned to the reflective mirror 12 as reflected light t2.
It is refracted with a refractive index of , and is incident on and reflected by the second reflective film 18 .

Similarly, b3. ~b6, t3. -Repeat reflection and spectroscopy as in t6. Here, each emitted light t1, ~t
6 are emitted in parallel with a minute interval in the direction in which the dye laser light travels.

The distribution ratio ρ of the light intensity of each of the above output lights bl and ~b6
1. ~ρ6 is the reflectance Rs of the first reflective film 17 of 38.2
When expressed as %, it is expressed as follows.

ρ　1−Rs ρj−Rs” (1−Rs)2 (j≧2).

Reflectance Rs is 38.2%.

(Rs=0.382) ρ1. Calculating up to ρ5 results in the following.

ρ 1-0. 382 ρ2-0.382 ρ B-0,146 ρ4-0. 056 ρ5■0.021 Note that the distribution ratios after ρ6 are all less than 1O-2 (1%), so they are negligible values.

The light bl is thus split into five beams.

~b5 has a minute interval between each beam spot, so that the spatial light intensity distribution can be made uniform. In other words, since the spatial distribution of the five beam spots is defined by the overlap of the respective spatial distributions, the light intensity distribution can be smoothed.

This situation is shown in FIG. The curve indicated by a broken line in the figure is the intensity distribution of the laser beam p incident on the reflection mirror 12, and each light component bl, ~b5 after being reflected on the reflection mirror 12 is a predetermined distance g of the dye laser beam. Shifts in the direction of travel. Then, the light intensity is divided in the L direction, and the light intensity distribution is brought closer to a flat state. At this time, g is the thickness (d) of the reflecting mirror 12 and the refractive index (
n) and the incident angle θ of the laser beam p to the reflecting mirror 12, and is expressed as the following equation.

For example, d=15a+I11. θ-45@n-1,5
Then, it becomes N-7.6ma+.

Note that the overlapping state of these beam spots can be adjusted by changing the angle of the reflecting mirror 12.

As mentioned above, the five beams bl generate an excitation effect on one beam p by the reflecting mirror 12.

By irradiating the dye cell 13 divided into ~b5,
The generation of ASE can be suppressed even with excitation light having a light intensity level that would cause ASE in the conventional structure.

This allows the dye laser light to be amplified to a higher output than the conventional structure while maintaining a single wavelength.

Note that the present invention is not limited to the above embodiment. For example, in the above embodiment, the dye laser amplification device 10 was the object of implementation, but the present invention is not limited to this.

For example, it can also be applied to a dye laser oscillation device.

Furthermore, the excitation laser output unit 11, the reflection mirror 12, and the cylindrical lens 14 are made into an integrated structure, and this integrated structure is attached to, for example, a robot arm, and moved, so that the irradiation position of the laser beam can be adjusted, for example, in the X-Y direction. It is also possible to perform laser processing by moving in the direction. When the above-described structure is utilized for laser processing in this manner, the light intensity distribution of the day-focused beam on the irradiation surface can be kept approximately uniform, so that a homogeneous processing finish can be obtained. Moreover, since the overlapping state of the beams can be adjusted by operating the handle 25, the intensity of the irradiated light can also be changed.

Further, the reflectance of the first reflective film 17 is 38 in the example.
,2%, and this figure is, but not limited to, 3%.
A range of 0 to 70% is desirable. Furthermore, similar effects can be obtained even when the dye laser beam travels in the opposite direction in the embodiment shown in FIG. 4.

[Effects of the Invention] (1) A first reflective film having a predetermined transmittance is formed on the incident surface of a reflective mirror made of a light transmitting medium having a predetermined refractive index, and a first reflective film having a predetermined transmittance is formed on the back surface opposite to the incident surface. By forming the second reflective film, when the laser light output from the laser output section is incident at a predetermined angle, it is partially transmitted and partially reflected by the first reflective film, and the transmitted laser light is transmitted through the light transmission medium. is refracted according to the refractive index of and reflected on the second reflective film,
The light enters the first reflective film at a position different from the incident position, and is partially transmitted and partially reflected. At this time, the reflected light and the transmitted light are each substantially parallel, and the laser light reflected by the reflecting mirror has a uniform spatial light intensity distribution.

(2) A first reflective film with a predetermined transmittance is formed on the incident surface of a reflective mirror made of a light transmitting medium having a predetermined refractive index, and a second reflective film is formed on the back surface opposite to this incident surface. By forming the excitation laser output section, the excitation laser beam output from the excitation laser output section is incident on the above incident surface, and is partially transmitted and partially reflected by the first reflective film, and the transmitted laser beam is refracted by the light transmission medium. The light beam is refracted according to the index, is reflected by the second reflective film, and is incident on the first reflective film at a position different from the incident position, where it is partially transmitted and partially reflected. At this time, the reflected light and the transmitted light are each substantially parallel, and the excitation laser light reflected by the reflection mirror has a uniform spatial light intensity distribution. By exciting the dye cell with this excitation laser beam with uniform light intensity, more stable excitation can be achieved, generation of ASE can be suppressed, and high dye laser output can be obtained.

[Brief explanation of drawings]

FIGS. 1 to 3 show an embodiment of the present invention,
Fig. 1 is a plan view showing a schematic configuration of a dye laser amplification device, Fig. 2 is a plan view showing a state in which incident light is reflected by a reflecting mirror with the spatial light intensity distribution approximately equalized, and Fig. A light intensity distribution diagram showing the light intensity distribution after being reflected on a reflecting mirror. Fig. 4 is a plan view showing the schematic configuration of a conventional dye laser amplification device. Fig. 5 is a diagram showing the light intensity distribution after being reflected on a conventional reflecting mirror. FIG. 3 is a light intensity distribution diagram showing intensity distribution. 11... Excitation laser output section, 12... Reflection mirror 1
3... Dye cell, 17... First reflective film, 18...
-Second reflective film. Figure 1

Claims (2)

[Claims] (1) In a laser device including a laser output section that outputs laser light and a reflecting mirror provided with an incident surface inclined with respect to the optical axis of the laser light, the reflecting mirror has a predetermined refractive index. A first reflective film having a predetermined transmittance is formed on the incident surface of the light-transmitting body, and on the back side of the reflective mirror facing the incident surface, light is incident on the first reflective film and is not reflected. 1. A laser device characterized in that a second reflective film is formed that reflects, with high reflectance, the light transmitted through the first reflective film and the light reflected on the back surface of the first reflective film. (2) An excitation laser output section that outputs an excitation laser beam, a reflection mirror whose incident surface is inclined with respect to the optical axis of the excitation laser beam, and a dye that is irradiated with the excitation laser beam that passes through this reflection mirror. In the laser apparatus, the reflecting mirror is a transparent body having a predetermined refractive index, a first reflecting film having a predetermined transmittance is formed on the incident surface, and the above-mentioned laser cell facing the incident surface is provided with a first reflective film having a predetermined transmittance. On the back side of the reflecting mirror is the above-mentioned No. 1
A laser device characterized in that a second reflective film is formed that reflects at a high reflectance the light that is incident on the reflective film and is transmitted without being reflected, and the light that is reflected on the back surface of the first reflective film. .