JPH07193302A - Solid-state laser oscillator - Google Patents

Abstract

(57) [Summary] [Construction] A condenser 2, a laser rod 6 and an excitation light source 7 provided inside the condenser 2, and a pair of reflecting mirrors 8 and 9 arranged on both sides of the laser rod 6. The stationary laser oscillator 1 is constructed, and the exterior body 3 forming the condenser 2 is formed of ceramics, and yellowish glass is baked on the wall surface of the inner hole 5 formed in the exterior body 3. [Effect] Even if the mounting positions of the laser rod 6 and the excitation light source 7 are slightly deviated, the output of the laser light does not decrease, and the laser light of a predetermined output can be emitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state laser oscillator such as an Nd-YAG laser and an Nd-glass laser.

[0002]

2. Description of the Related Art As shown in FIG. 5, a structure of a solid-state laser oscillator conventionally used is such that a metal outer casing 13 constituting a condenser 12 has an inner hole 15 having an elliptical cross section. A cylindrical laser rod 6 made of YAG or glass as a solid-state laser on one focal axis of the inner hole 15 and a krypton arc lamp or the like on the other focal axis. A cylindrical excitation light source 7 such as a tungsten / halogen lamp or a xenon / flash lamp is arranged, and an inner hole 15 of the outer casing 13 is provided.
The wall surface is provided with a condensing reflecting surface 14 for irradiating the laser rod 6 with light from the excitation light source 7, and a pair of reflecting mirrors 8 and 9 is arranged on both sides of the laser rod 6. It was a thing.

In such a solid-state laser oscillator 10, the excitation light source 7 is caused to emit light by applying a trigger voltage to the excitation light source 7, and the light is reflected directly and by the converging / reflecting surface 14 and indirectly by the laser rod. By irradiating the laser rod 6 with YAG or Nd contained in the glass.
After the ions are excited and the light emitted when the Nd ions transit from the excited state to the stable state is extracted as laser light, and the laser light is reciprocated between the output reflecting mirror 8 and the reflecting mirror 9, The laser light was emitted from the output reflecting mirror 8.

By the way, most of the light radiated to the laser rod 6 is reflected by the converging / reflecting surface 14, and the laser rod 6 is not irradiated with light having a wavelength of less than 550 nm, and has a wavelength longer than that. 550 nm to 900 nm
Since it is necessary to irradiate the light of the wavelength (hereinafter referred to as excitation light), gold or silver has been used as a constituent material of the condensing reflection surface 14 (Japanese Utility Model Publication No. 62-186450, Japanese Utility Model Publication No. 2-84354). (See the official gazette).

There are other solid-state laser oscillators in which the cross-sectional shape of the inner hole of the condenser is spectacles, and this solid-state laser oscillator is excited on the focal axis of the substantially circular portion of the cross-section of the inner hole. Light sources are respectively arranged, and a laser rod is arranged at the center connecting these two excitation light sources, and gold or silver was also used as a constituent material of the condensing reflection surface.

[0006]

However, in the solid-state laser oscillator 10 as described above, it is very difficult to dispose the laser rod 6 and the pumping light source 7 on the focal axis with high accuracy. If the mounting position deviates from the focal axis even a little, the amount of excitation light with which the laser rod 6 is irradiated decreases, and the output of the laser light decreases. In some cases, the NAG contained in YAG or glass is reduced.
There is a problem that d ions cannot be excited and laser light cannot be emitted.

That is, the gold or silver constituting the condensing reflecting surface 14 has the characteristics of absorbing light having a wavelength of less than 550 nm and reflecting the exciting light with high efficiency. Although excellent as a constituent material, since the incident light can be reflected only in one direction, all the excitation light reflected by the condensing reflection surface 14 is irradiated onto the focal axis, and is attached with a slight deviation from the focal axis. The obtained laser rod 6 could hardly be irradiated with excitation light.

Further, in the solid-state laser oscillator 10, in order to suppress heat generation of the laser rod 6, the inner hole 1 of the condenser 12 is provided.
5 is filled with cooling water, but the surface of gold or silver that forms the light collecting and reflecting surface 14 is fogged by water stains or dust, and the original brightness cannot be obtained. There was a problem. Therefore, there is also a problem that the efficiency of light reflection on the light collecting and reflecting surface 14 is reduced and the output of laser light is reduced.

On the other hand, the exterior body 13 constituting the condenser 12
However, since it is formed of a metal such as a copper alloy, the trigger voltage applied to the excitation light source 7 is likely to leak, and when this leakage occurs, the excitation light source 7 does not emit light.

An object of the present invention is to provide a solid-state laser oscillator capable of obtaining a predetermined output and stably emitting laser light for a long period of time even if the mounting positions of a laser rod and an excitation light source are slightly deviated. Especially.

[0011]

In view of the above problems, therefore, in the present invention, the exterior body that constitutes the condenser of the solid-state laser oscillator is formed of dense and insulating ceramics, and the exterior body of the exterior body is formed. The light collecting and reflecting surface provided on the wall surface of the inner hole is formed of yellowish glass.

[0012]

According to the present invention, since yellowish glass is used as the constituent material of the light collecting and reflecting surface, it is almost the same as gold which selectively absorbs light having a wavelength of less than 550 nm and reflects excitation light with high efficiency. Equivalent reflection characteristics can be obtained. Moreover, the yellowish glass can diffuse and reflect incident light on the surface, and does not cause clouding on the glass surface.

Further, according to the present invention, since the exterior body of the condenser is made of dense and insulating ceramics, the trigger voltage is not leaked and the cooling water is leaked. Nothing. Moreover, the yellowish glass can be attached by baking.

[0014]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 is a partially cutaway perspective view of a solid-state laser oscillator 1 according to the present invention. The same parts as those in the conventional example are designated by the same reference numerals.

As shown in FIG. 1, an outer body 3 which constitutes the condenser 2 is provided with an inner hole 5 having an elliptical cross section in the longitudinal direction. The inner hole 5 having the elliptical shape is formed. A cylindrical laser rod 6 made of YAG or glass is provided on one focal axis, and a cylindrical excitation light source such as a krypton arc lamp, a tungsten halogen lamp, or a xenon flash lamp is provided on the other focal axis. 7 are arranged respectively, and the condenser reflection surface 4 for irradiating the laser rod 6 with the light from the excitation light source 7 is provided on the wall surface of the inner hole 5 of the condenser 2.
And a pair of reflecting mirrors 8 and 9 are arranged on both sides of the laser rod 6.

Now, when a trigger voltage is applied to the excitation light source 7 to cause the excitation light source 7 to emit light, a part of the light is emitted from the laser rod 6.
And the other light is reflected by the condensing reflection surface 4, and only the excitation light (550 nm to 900 nm) is emitted to the laser rod 6.
Therefore, the laser light is emitted to the output reflecting mirror 8 by exciting Nd ions contained in the YAG and the glass forming the laser rod 6 and emitting the laser light to the output reflecting mirror 8 and the reflecting mirror 9. The laser beam having a predetermined output is emitted from the output reflecting mirror 8 by reciprocating between them.

By the way, the condenser reflection surface 4 of the condenser 2 is described.
Must be a material capable of highly efficiently reflecting light having a wavelength of 550 nm to 900 nm (excitation light) and absorbing light having a wavelength of less than 550 nm. Therefore, various experiments have been conducted on materials satisfying these characteristics. As a result of repetition, they found that yellowish glass was the most suitable.

That is, the yellowish glass absorbs light having a wavelength of less than 550 nm which may damage the laser rod 6,
Moreover, it is possible to highly efficiently reflect the wavelength light (excitation light) of 550 nm to 900 nm that is important for exciting the Nd ions in the laser rod 6. Moreover, since the incident light can be diffused and reflected, the laser rod 6 can be irradiated with the excitation light even if the mounting positions of the laser rod 6 and the excitation light source 7 are slightly displaced from the focal axis.

Further, since the yellowish glass has less adhesion of water stains and the like, it is less likely to cause clouding and does not impair the original color. Therefore, a high reflection efficiency is always obtained.

Therefore, the yellow glass used as the condensing and reflecting surface 4 is a glass material such as borosilicate glass and a coloring pigment such as cadmium yellow, antimony yellow, titanium yellow, chrome yellow, vanadium yellow, or yellow iron oxide. , 2-3% of the total of glass and color pigments
The one added in the ratio of is used.

When the content of the coloring pigment is less than 2%, the glass becomes semi-transparent, the underlying color appears, and light of wavelengths other than the excitation light is also reflected. On the contrary, if the content is more than 3%, a color different from the desired color will be generated, so that the excitation light cannot be reflected with high efficiency, and the wavelength light of less than 550 nm This is because there is a risk that it will also be reflected.

In order to improve the reflection efficiency, it is important that the surface of the yellowish glass forming the light collecting and reflecting surface 4 has a center line average roughness (Ra) in the range of 0.1 to 3.0 μm. Is. This is a center line average roughness (Ra) of 0.1 μm.
If the center line average roughness (Ra) is larger than 3.0 μm, the glass surface absorbs a large amount of light and a part of the excitation light is also absorbed. There is a risk that

Further, the thickness width h of the yellowish glass is 5 to 3
The range is 0 μm, preferably 7 to 15 μm. This is because if the thickness width h is less than 5 μm, it is too thin and difficult to manufacture, and also the outer casing 1 that forms the base.
This is because the color of 3 appears on the glass surface and the original color, yellow, is lost. On the contrary, if the thickness width h is made too large, the amount of waste becomes too large.
It may be provided in the range of 0 μm or less.

On the other hand, the exterior body 3 which constitutes the condenser 2 is formed of ceramics because it is required to have adhesiveness and insulation with respect to yellowish glass.

As the ceramics, alumina, zirconia, silicon nitride, etc. can be used.
The ceramics are not limited to these ceramics, and may be made of at least insulating ceramics having a water absorption rate of 0%.

As described above, by forming the outer package 3 from the dense and insulating ceramics, the trigger voltage applied to the excitation light source 7 is not leaked and the inner hole 5 is filled. There is no leakage of cooling water.

Further, since the ceramics are fired at a high temperature of 1000 ° C. or higher, the yellowish glass forming the light converging / reflecting surface 4 can be baked, and particularly the exterior body 3 contains SiO ₂ as a sintering aid such as alumina. In the case of ceramics, the bond with the yellowish glass is strengthened and can be firmly fixed. Moreover, the coefficient of thermal expansion of ceramics can be approximated to 3 to 10 × 10 ⁻⁶ / ° C., which is similar to the coefficient of thermal expansion of glass (α = 5 × 10 ⁻⁶ / ° C.). There is no distortion.

Next, as an example, a method of manufacturing the condenser 2 in which the exterior body 3 is made of alumina will be described.

First, in order to manufacture the exterior body 3 which constitutes the condenser 2, a predetermined amount of a sintering aid and an organic binder are added to alumina raw material and pulverized, and then a granulated body is produced by a spray dryer. The obtained granules are molded into a cylindrical body by a known molding method such as a rubber press or an isostatic press, and a cutting process is performed to form a semicircular groove in the longitudinal direction of about 300 × 150 × 30 mm. Form a rectangular parallelepiped. After that, firing temperature 1350 ° C to 1700 ° C
Half of the outer package 3 is obtained by firing at a temperature of about this value. Next, after buffing the groove surface of the rectangular parallelepiped, 2-3%
The glass sheet containing the color pigment in the ratio of is transferred to the groove surface and heated to a temperature of about 800 ° C. to 1150 ° C. to bake the glass.

The concentrator 2 can be manufactured by preparing two rectangular parallelepipeds thus obtained and stacking them so that their grooves face each other.

In the embodiment of the present invention, only the condenser 2 in which the outer package 3 is made of alumina is shown.
When the condenser 2 is made of other ceramics, it is manufactured by manufacturing the ceramic exterior body 3 by a generally known manufacturing method and then baking the glass by the method as described above. be able to.

Experimental Example Next, an experiment was conducted on the reflectance of each wavelength when white light was radiated, using the yellowish glass of the present invention forming the condensing reflecting surface 4 of the condenser 2 and gold as a comparative example. went. The yellow glass of the present invention is borosilicate glass to which 3% of antimony yellow is added.

A self-recording spectrophotometer (Model 330 manufactured by Hitachi, Ltd.) was used for measurement in this experiment, and aluminum oxide was used as a standard sample, and the relative reflectance when the reflectance of this standard sample was set to 100%. The measurement was performed, and the measurement was performed at incident angles of 0 ° and 5 °, respectively.

The self-recording spectrophotometer is one in which a detecting portion is provided on the side of a spherical body called an integrating sphere as shown in FIG. 2 and a light collecting and reflecting surface 4 serving as a sample is arranged on the bottom. Yes, when white light is irradiated onto the condensing reflecting surface 4 from above, the light reflected by the condensing reflecting surface 4 is condensed on the detecting portion in the integrating sphere, and the light amount of each wavelength light is detected. Therefore, for the incident angle of 5 ° of white light, the incident angle is 5 ° by inclining the sample downward by 5 °.

The results are shown in Table 1 and FIG. 3 for the yellowish glass of the present invention, and FIG. 4 for gold as a comparative example.

[0037]

[Table 1]

As can be seen from Table 1 and FIGS.
The yellow glass of the present invention exhibits almost the same reflection characteristics as gold as a comparative example, both of which absorb light having a wavelength of less than 550 nm and reflect 90% or more of light having a wavelength of 550 nm to 900 nm (excitation light). The rate has been obtained.

From these results, it can be seen that even if the yellow glass of the present invention is used as the condensing / reflecting surface 4, a laser beam of a predetermined output can be emitted.

In the yellowish glass of the present invention,
The reflectance decreases when the incident angle is 5 °, because the experiment is performed by tilting the sample yellow glass at 5 ° with respect to the horizontal direction. It is considered that this is because only the part could be detected by the integrating sphere.

Next, looking at the respective reflectances at an incident angle of 0 °, it can be seen that gold as a comparative example hardly reflects light of any wavelength. It is considered that the reason for this is that gold is a simple substance in which gold atoms are uniformly arranged, so that almost all incident light is reflected in a certain direction. Therefore, it is considered that the light incident at the incident angle of 0 ° was reflected vertically and the light reflected on the gold surface was not applied to the integrating sphere.

Therefore, it is understood that in the solid-state laser oscillator 1 using gold as the condensing / reflecting surface 4, the laser rod 6 and the excitation light source 7 must be arranged on the focal axis of the inner hole 5 with high accuracy.

On the other hand, the yellowish glass of the present invention absorbs light having a wavelength of less than 550 nm at an incident angle of 0 ° and is 550
It can be seen that light having a wavelength of 900 nm (excitation light) has a reflectance of 90% or more.

As described above, the yellow glass of the present invention has a reflectance of 90% or more of the wavelength light (excitation light) of 550 to 900 nm even when the incident angle is 0 °, because the incident white light is diffusely reflected. This is probably because Therefore, if the yellowish glass of the present invention is used as the condensing reflecting surface 4, the fixed laser oscillator 1 can emit a laser beam of a predetermined output even if the laser rod 6 and the excitation light source 7 are slightly displaced. Can be provided.

[0045]

As described above, according to the present invention, in a solid-state laser oscillator such as an Nd-YAG laser or an Nd-glass laser, the exterior body is made of dense and insulating ceramics, and the inner hole of the exterior body is formed. 550n on the wall
Absorbs light of wavelength less than m and 550 nm to 900 nm
Since the light concentrator is configured with a yellow-colored glass that diffuses and reflects the wavelength light of as a condensing reflection surface, there was a slight deviation in the mounting position of the laser rod and the excitation light source installed in the inner hole. In this case, the output of the laser light is hardly reduced, and the condensing / reflecting surface is not fogged, so that the laser light having a predetermined output can be emitted.

Moreover, since the trigger voltage is not leaked, it is possible to stably emit laser light for a long period of time.

Furthermore, in the solid-state laser oscillator of the present invention,
Since the laser rod and the excitation light source do not require high mounting accuracy, the manufacturing is simple and the yield can be greatly improved.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a solid-state laser oscillator according to the present invention.

FIG. 2 is a simplified diagram showing a self-recording spectrophotometer.

FIG. 3 shows incident angles of 0 ° and 5 ° on the yellowish glass of the present invention.
3 is a graph showing the reflectance of each wavelength when white light is emitted in FIG.

FIG. 4 is a graph showing reflectance at each wavelength when white light is irradiated on conventional gold at incident angles of 0 ° and 5 °.

FIG. 5 is a partially cutaway perspective view of a conventional solid-state laser oscillator.

[Explanation of symbols]

 1: Solid-state laser oscillator 2: Condenser 3: Outer package 4: Condensing reflection surface 5: Inner hole 6: Laser rod 7: Excitation light source 8: Output reflecting mirror 9: Reflecting mirror

Claims (1)

[Claims] 1. A condenser having a light collecting / reflecting surface on a wall surface of an inner hole of an outer package, an excitation light source and a laser rod provided in the inner hole of the outer package, and a pair arranged on both sides of the laser rod. In the solid-state laser oscillator consisting of the reflecting mirror and the outer body forming the above-mentioned concentrator is made of ceramics,
A solid-state laser oscillator having a light collecting and reflecting surface made of yellowish glass.