JPS6159787A - Solid laser exciting lamp - Google Patents

Abstract

PURPOSE:To uniformly excite a plate-shaped laser active medium, by providing beltlike facing electrodes within a flat vacuum container and adhering conductive films which can transmit light in the effective absorption band of the laser active medium along the discharge passage between these electrodes. CONSTITUTION:Beltlike facing electrodes 2A and 2B are disposed within a flat vacuum container 1 of quartz glass. A high voltage in the order of 2-3kV is applied between the electrodes 2A and 2B through electrode outlets 3A and 3B so as to cause electric discharge. Transparent conductive films 5A and 5B of indium oxide mixed with tin oxide are adhered on the opposed outer surfaces of the vacuum container 1. These transparent electrodes 5A and 5B are provided such that the ends thereof are superposed on the edges 4A and 4B of the electrodes 2A and 2B to ensure that the discharge passage between the facing electrodes 2A and 2B is completely covered with the transparent electrodes. Thus, an induction passage for electric discharge is provided over the whole discharge passage between the electrodes, whereby generally uniform electric discharge can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lamp for excitation of a solid-state laser, and more particularly to a lamp for excitation of a surface-pumped solid-state laser equipped with a plate-shaped laser active medium.

[Conventional technology]

In a typical conventional solid-state laser device, a laser active medium and an excitation lamp, both of which are cylindrical, are placed at the focal point of an ellipsoidal reflector, and the excitation light from the excitation lamp is reflected by the reflector. The structure was designed to focus light on the laser active medium, but when the laser light output became large, the output became unstable due to the temperature difference between the center and the surface of the laser active medium, and the laser active medium was destroyed. There was a problem.

For this reason, in recent years, a surface-cooled, light-pumped solid-state laser device called a slab type has been developed and used.

In this system, an excitation lamp is placed between a plate-shaped laser active medium, and a cooling medium is flowed between them.The laser light is reflected between the opposing surfaces of the laser active medium facing the excitation lamp. By turning the light, the optical path passes through a p-zigzag path, and at that time, the light travels through the medium with an averaged temperature distribution, alternating between the low-temperature part on the cooled surface and the high-temperature part in the center. It will spread.

However, in this type of conventional solid-state laser device, a cylindrical excitation lamp is used, so although the temperature distribution in the thickness direction of the plate-shaped laser active medium is averaged as described above, the excitation lamp In the width direction, which is perpendicular to the extending direction of the lamp and perpendicular to the above-mentioned thickness direction, the light intensity has a distribution that decreases as the distance from the lamp increases, so the temperature distribution is similarly uneven, and accordingly, the refractive index is also the same. will have a distribution of

For this reason, there has been a limit to increasing the output of laser light.

[Problem that the invention seeks to solve]

The present invention has been made in view of these circumstances, and its object is to provide a solid-state laser excitation lamp that can uniformly excite a plate-shaped laser active medium.

[Means for solving problems]

In order to achieve such an object, the present invention consists of a discharge tube equipped with a band-shaped counter electrode inside a flat vacuum vessel,
and a conductive film that is transparent to at least light in the effective absorption band of the laser active medium is coated on the outer surface of at least one main surface of the vacuum container along the discharge path between the opposing electrodes. .

[Effect]

By arranging flat excitation lamps adjacent to a plate-shaped laser active medium so that their main surfaces and widest surfaces are parallel to each other, the entire main surface of the laser active medium can be uniformly distributed. excite. In addition, since there is a risk of localized discharge due to the band-shaped facing IE electrode, a trigger voltage is applied to the conductive film attached to the outer surface of the main surface of the vacuum container to create a guide path for the discharge. By creating such a structure, it is possible to cause a uniform discharge to occur over the entire band-shaped counter electrode.

〔Example〕

FIG. 1 shows an embodiment of the present invention. The figure (-) is a plan view, the figure (b) is a front view, and the figure (C) is a side view.

In the figure, 1 is a flat empty vessel made of quartz glass and having an external shape of 34 mm wide, 4 mm thick, and 120 mm long, and has a wall thickness of about 1 rIrs. Inside the vacuum container 1, there are long lengths 30 along the width direction at both ends in the longitudinal direction.
A band-shaped opposing electric wire M2A, 2B is arranged. The opposing portions of both electrodes are formed into a knife shape in order to effectively concentrate the electric field and cause efficient discharge.
It does not necessarily have to be this way; for example, it may be a curved surface having a radius of curvature that allows one side to be fitted.

Cocote, l11fii'! K t between ff12A and 2B
Pole extraction part aA.

When a high voltage of about 2 to 3 KV (500 to 900 J in terms of energy) is applied by a power supply not shown in the figure through the electrode 3B to cause a discharge, the electrodes 2A and 2B extend in a band shape, so the extension If a convex portion is present due to the surface condition of the edge portions 4A and 4B in the direction (width direction of the vacuum vessel), the electric field will concentrate only on the convex portion, causing a local discharge, and will spread over the entire width direction of the vacuum vessel. In some cases, it may not be possible to obtain a uniform discharge.

For this reason, in the present invention, transparent conductive films (ITO) 5A and 5B made of indium oxide mixed with tin oxide are deposited on the outer surfaces of the vacuum vessel 10 facing each other in a thickness of about 1 μm. be. A film 5A is applied to this transparent material 4.

5B is provided so that its end overlaps the edge portions 4A, 4B of the electrodes 2A, 2B so as to completely cover the discharge path between the opposing M, N2A, 2B.

Therefore, by connecting a trigger power source 6 to these transparent conductive films 5A and 5B as shown in the figure and applying a trigger voltage of approximately 20 KV, a discharge guiding path is formed over the entire discharge path between the electrodes 2A and 2B. This results in uniform discharge throughout the area. Note that platinum was used for the edge portions 4A and 4B of the electrodes so as to withstand high voltage.

Such an excitation lamp is used, for example, as shown in FIG. That is, FIG. 2 (&) is a perspective view showing a configuration example of a slab-type solid-state laser device using the excitation lamp of the present invention, FIG.
@ side view.

In the figure, the laser active medium 11 is made of phosphate glass (I, KG-8, manufactured by Hoya Glass Co., Ltd.) processed into a flat rhombic cross-sectional shape with an inclination angle of 45.4 mm and a width of 30 mm. In particular, the human exit surface and the parallel upper and lower opposing principal surfaces, where incident light undergoes multiple reflections, are polished smooth to minimize loss.

This laser active medium 11 has supports 12 on both sides thereof.
13 and is supported. Furthermore, partition plates 14 and 15 are arranged parallel to each other at a distance of about 1 to 3 H from the opposing main surfaces, and are firmly supported by supports 16, 17 and 18°19. and on the outside thereof an excitation lamp 20.2 as shown in FIG.
1 are fixedly supported on both longitudinal sides by supports 22, 23 and 24, 25, respectively. Further, an upper cover 26 and a lower cover 27 are arranged outside the excitation lamp 20°21. The partition plates 14.15 are made of a material that transmits the excitation light from the excitation lamps 20.21, and in this embodiment is made of quartz glass. The excitation lamp 20.21 is filled with Xe gas, is spaced from the cutting plate 14.15 by about 2 to 5M, and has both opposing main surfaces covered with transparent conductive films 5A and 5B serving as a laser active medium. 1
They are arranged parallel to the vertically opposing main surfaces of 1.

Further, the inner surfaces of the upper cover 26 and the lower cover 27 are formed parallel to the main surface of the lamp 20.21.
They are placed at a distance of about 1 to 5 squares from each other, and are plated with gold to increase the light reflectance so that they act as reflectors.

In the above configuration, the incident light 28 is transmitted to the laser active medium 11
After being perpendicularly incident on the incident surface, the light propagates while being amplified by multiple reflections and surface excitation on the upper and lower opposing principal surfaces, and is emitted as output light 29 from the output surface. Note that a solid-state laser oscillation device can be constructed by arranging mirrors 30 and 31 perpendicular to the optical axis on both the incident surface and the exit surface side.

Here, as mentioned above, since the excitation lamps 20 and 21 produce a uniform discharge over the entire main surface, the laser active medium 11 disposed parallel to the main surface has a uniform distribution over the entire main surface. Receives σ excitation light. As a result,
The temperature and refractive index distributions also become uniform. In particular, in this configuration example, between the laser active medium 11 and the partition plate 14.15, between the partition plate 14.15 and the excitation lamp 20.21, between the excitation lamp 20.21 and the upper cover 26 and the lower cover 27.
By flowing cooling water (pure water) with a cooling body in the space between the two, the above-mentioned uniformity effect becomes even greater, and higher output becomes possible.

Also, if the outer circumference of the excitation lamp is cooled, 7.

This is also effective in preventing aging of the transparent conductive films 5A and 5B.

In the configuration example described above, for example, the laser active medium 11 is made of Nd:YAG.

It may be Nd:GGG or YLF, or it may have a flat rhombic cross-sectional shape with the incident angle set to Brewster's angle so that the incident light and the outgoing light are parallel. In addition, the inner surfaces of the upper cover 26 and lower cover 27 may be silver plated with an oxidation prevention film instead of gold plating, or BIL80
4 or the like may be applied, and these changes do not impair the effect of the flat-shaped excitation lamp provided with the external trigger transparent conductive film of the present invention.

In addition, a structure in which the laser active medium is arranged in a layered manner on the outside of the excitation lamp 20, 21, or in which the excitation lamp and the laser active medium are arranged in multiple layers on the outside thereof, may also be used.
The excitation lamp of the present invention can be similarly applied to obtain similar effects.

The above description has been made using the case where the laser is used in a so-called slab-type solid-state laser device, but the present invention is not limited to this. Although it does not take the optical path of
It can also be effectively used in a disk laser device using a plate-shaped laser active medium.

Further, in the above embodiment, the transparent conductive film was separately provided on each of the opposing main surfaces of the vacuum container, but the two may be connected in a ring shape and coated so as to surround the outer periphery, or the transparent conductive film may be provided on only one surface. Good too.

Furthermore, the transparent conductive film is not limited to an ITO film, but includes, for example, indium oxide (In20B) or a film to which tungsten (W) is added, or tin oxide (S
A conductive film, such as one in which strontium (sb), fluorine (F), etc. are added to nOa), is transparent to at least light in the effective absorption band of the laser active medium, and has a certain degree of corrosion resistance in practical use. That's fine.

〔Effect of the invention〕

As explained above, according to the present invention, the excitation lamp is formed into a flat shape having a main surface substantially parallel to the main surface of the plate-shaped laser active medium, and the strip-shaped opposing electrodes are provided, and the discharge between the opposing electrodes is provided. A light-transmitting conductive film for an external trigger is deposited on the outer surface of at least one main surface of the vacuum container along the path, so that the plate-shaped laser active medium is uniformly excited over the entire main surface of the vacuum container. becomes possible.

[Brief explanation of drawings]

Figure 1 (-) is a plan view of a solid-state laser excitation lamp showing an embodiment of the present invention, Figure 1 (0) is a -4 king side view, Figure 1 (c) is
2 is a side view, FIG. 2(a) is a perspective view of a solid-state laser device using this lamp, FIG. 2(b) is a bbIfr plane view, and FIG. 2(c) is a c-a Ur plane view. 1...Vacuum container, 2A, 2B...Opposing 1!1.
Pole, 4A, 4B...Edge part, 5A, 5B...
・Transparent conductive film, 11...Laser active medium, 20.2
1... Excitation lamp.

Claims (1)

[Claims] In a solid-state laser excitation lamp consisting of a discharge tube equipped with a counter electrode inside a vacuum vessel and placed adjacent to a plate-shaped laser active medium to optically excite the surface of the laser active medium, the vacuum vessel is the laser active medium. a flat-shaped counter electrode having a main surface substantially parallel to the main surface of the vacuum container and extending substantially parallel to the main surface; 1. A solid-state laser excitation lamp, characterized in that a conductive film that transmits at least light in an effective absorption band of a laser active medium is coated on the outer surface of one main surface.