JPS637689A - Laser device using powdered laser medium - Google Patents

Abstract

PURPOSE:To enlarge the extent of selection of a laser medium by a method wherein fine powder such as minute spherical particles and crystals of a substance which acts as a laser medium in solid state are dispersed and suspended into a medium transparent with respect to the oscillating light. CONSTITUTION:Fine powder (YAG powder) 7 which is a laser medium is interposed between mirrors constituting a resonator and the YAG fine powder is floated and dispersed in argon gas which is inactive gas and is turned into a laser oscillation medium. In the forming process of this fine powder, a YAG poly material (YAG poly laser medium) 50 doped with a proper amount of Nd<3+> is turned into fine powder for a laser medium by powdering with a ball mill 51 and so on in such a way as not to change the physical nature other than a form change. As the argon gas is being circulated by an argon gas circulating pump 8, the powdered laser medium 7 being encapsulated in a cylindrical space partitioned by transparent partition plates 14 and 15 are almost uniformly distributed in this space.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides spherical fine particles of a substance that can be used as a solid-state laser medium,
The present invention also relates to a laser device using a powder laser medium configured by dispersing fine powder such as crystal in a medium transparent to oscillation light.

(Prior Art) A YAG laser is a typical solid-state laser, and uses a YAC laser rod as a laser medium.

It is widely used for processing purposes and for measuring laser interference.

(Problems to be solved by the invention) As mentioned above, solid-state lasers represented by YAG lasers have
Although it is widely used, there are some problems in terms of manufacturing and usage.

(1) Since the laser medium must be a large uniform crystal, the selection range becomes narrow.

(2) Crystals such as YAG laser rods have high hardness and require advanced processing techniques such as surface polishing of the medium.

(3) Due to its structure, multiple solid-state laser media can be used simultaneously;
do not have.

(4) When a part of the medium deteriorates, the overall performance deteriorates significantly.

(5) Special care must be taken to cool the medium; an auxiliary device for this purpose is required.

An object of the present invention is to provide a laser device using a powder laser medium that can solve the problems associated with solid-state laser media as described above.

(Means for Solving the Problems) In order to achieve the above object, a laser device using a powder laser medium according to the present invention is a laser device that excites the laser medium with an excitation light source to cause laser oscillation. It is formed by dispersing and suspending fine spherical particles or fine powder such as crystals of a substance that becomes a laser medium in a medium that is transparent to oscillated light.

(Example) The present invention will be described in more detail below with reference to the drawings and the like.

FIG. 1 is a schematic diagram showing the basic structure of a laser device using a powder laser medium according to the present invention.

A powder laser medium is enclosed in a laser tube 1.

An excitation lamp 2 is arranged parallel to the laser tube 1.

The inner surface of the condensing reflector 3 is an elliptical surface, and the excitation lamp 2 and the laser tube 1 are arranged so as to be located at the focal point of the ellipse.

A total reflection mirror 4 and a partial transmission mirror (output mirror) 5 are arranged at both ends of the laser tube 1.
Laser oscillation output is taken out through.

Although not shown in Fig. 1, a glass laser tube 1 is filled with fine powder (powder laser medium), and argon gas is supplied to stir and cool the fine powder. Unlike the above device, if the laser tube 1 is regarded as a single laser rod, the basic structure is not significantly different from that of a normal solid state laser oscillation device.

The resonance condition for the oscillated laser beam is two reflective mirrors 4.5
When a resonator is constructed with a cavity between the two, the resonance conditions that are established are similar to those commonly found in gas lasers, solid-state lasers, and the like.

In the present invention, fine powder serving as a laser medium is interposed between the mirrors constituting the resonator.

In this example, YA was used in argon gas, which is an inert gas.
G fine powder is suspended and dispersed to form a laser oscillation medium.

FIG. 5 shows the manufacturing process of the fine powder.

A YAC polycrystalline material 50 doped with Nd3+ is pulverized using a ball mill 51 or the like so as not to change its physical properties other than a change in shape, to obtain a fine powder for a laser medium.

FIG. 2 is a cross-sectional view showing a laser tube of an embodiment of a laser device using a powder laser medium according to the present invention, partially cut away along a plane including the tube axis.

FIG. 3 is a cross-sectional view of a laser tube of an embodiment of a laser device using a powder laser medium according to the present invention, taken along a plane perpendicular to the tube axis.

The inner wall surface 13 of the laser tube 1 is formed with a reflective surface so that the light emitted from the inside does not dissipate to the outside.

As shown in each figure, a slit-shaped nozzle 12 is provided on the side surface of the laser tube 1, and a fill 11 is arranged on the side surface corresponding to this slit-shaped nozzle 12, and an argon gas i Alicyclic pump 8 (see Figure 3)
Argon gas is circulated.

As a result, the powder laser medium 7 enclosed in a cylindrical space defined by transparent partition plates 14, 15 (see FIG. 2) is distributed approximately evenly within this space.

It is desirable that the concentration of the fine powder be as constant as possible in the dispersed floating state, but a state in which it slowly convects does not pose an obstacle to laser oscillation. As shown in FIG. 4, the resonator of the device according to the present invention satisfies the resonance condition between a set of resonant mirrors 4.5 while repeating optical reflection, refraction, etc. within a very large number of medium fine powders. From a statistical point of view, it can be considered that a sufficient number of optical paths are formed.

It is also possible to add a temperature control function to the circulation system formed by the aforementioned argon gas circulation pump 8 to keep the argon gas at a constant temperature.

As a result, heat radiation from the laser medium is performed via the argon gas.

(Modifications) Various modifications can be made to the embodiments described in detail above within the scope of the present invention.

Depending on the gas, it is also possible to configure the system so that new gas is constantly supplied from the gas source and discharged to the outside without being circulated.

Here, the gas to be circulated is not limited to argon,
Any stable gas can be selected as long as it does not cause secondary interference such as absorption of laser oscillation light.

Furthermore, the laser medium does not need to be a crystalline material, and the same concept can be applied to an amorphous medium such as glass.

(Effects of the Invention) As explained in detail above, in a laser device using a powder laser medium according to the present invention, in a laser device that excites the laser medium with an excitation light source to oscillate, It is constructed by dispersing fine powder such as spherical particles or crystals in a medium transparent to the excavation light, and forming a turbidity.

Therefore, the following features are obtained.

Conventional solid-state lasers generally require the size of the medium, especially if the medium is a crystal, to obtain a good quality uniform crystal (for example, a single crystal), but it is technically difficult to grow a large single crystal. There are many.

Furthermore, even if it were possible to grow crystals, advanced mechanical processing techniques such as polishing optical end faces and parallelism would be required.

With the device according to the invention, first of all these technical difficulties can be solved.

That is, since the solid material that is the laser medium is made into powder, there are no restrictions on the size of the material.

Even if a crystal is crushed, its crystal structure is generally preserved;
Since the arm-opening surface becomes an optically good smooth surface, no particular problem arises due to a change in shape.

From the above features, it can be said that although large single crystals are difficult to obtain, they are good quality crystal materials (for example, YLF (
L 1YF4 : Nd3+)), laser oscillation becomes possible.

This expands the selection range of media.

For example, new laser oscillations not found in conventional solid-state lasers are expected, such as the use of materials that can only be obtained from polycrystals or the use of a mixture of multiple types of solid-state laser media, which can be used simultaneously within the same resonant mirror. can.

Next, the problem of cooling the laser medium can be solved by the present invention.

Generally, a laser medium is stimulated by external excitation energy.
They tend to reach high temperatures and their original characteristics are impaired by temperature changes, so measures such as water cooling and forced air cooling are taken as a countermeasure.

In the present invention, fine powder, which is a laser medium, is dispersed in a medium that is transparent to the oscillation light, and is arranged so as to be turbid. Therefore, if a gas that can be refluxed as shown in the example is used as a medium transparent to the oscillation light, the gas constantly stirs the powder, so if the argon gas is indirectly cooled by heat radiation, As a result, it is possible to cool the entire system including the powder or to keep it at a constant temperature.

The device according to the invention uses a solid state laser medium. However, the container in which the medium powder is placed (e.g. a glass tube)
Since there are not many dimensional restrictions in the length direction, the output of the laser oscillation device is relatively selective. therefore,
In addition to the cooling effect, a laser oscillation device with high output becomes possible.

Furthermore, it becomes possible to create a composite solid-state laser by combining combinations that could not be achieved with conventional solid-state lasers, and it becomes possible to oscillate multiple wavelengths at the same time.

For example, a composite laser of YAC and YLF containing Nd is possible, and at the same time 1.0641 μm, 1.0-17 μm
oscillation light can be obtained. In addition, alexandrite (B e A 12+ Q 4:
A wavelength tunable laser of 700 to 818 nm can be realized using powder of Cr 3 + ).

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the principle of a laser device using a powder laser medium according to the present invention. FIG. 2 is a cross-sectional view showing a laser tube of an embodiment of a laser device using a powder laser medium according to the present invention, partially cut away along a plane including the tube axis. FIG. 3 is a cross-sectional view of a laser tube of an embodiment of a laser device using a powder laser medium according to the present invention, taken along a plane perpendicular to the tube axis. FIG. 4 is an explanatory diagram for explaining the operating principle of the laser tube of the embodiment of the laser device using the powder laser medium according to the present invention. FIG. 5 is a schematic diagram for explaining a method of manufacturing a powder laser medium. 1...Laser tube 2...Excitation lamp 3...Condensing reflector 4...Total reflection mirror 5...-partial transmission mirror (output mirror) 7...Powder laser medium 8... Circulation pump 11... Laser tube filter 12... Laser tube slit upper spout 14,15...
・Transparent plate 50...YAG polycrystalline 51...Ball mill Patent applicant Hamamatsu Photonics Co., Ltd. Agent Patent attorney Inoro Mizogai 1 Fig. Excitation lamp % 2 Fig. Horse 3 Fig. Easy 4 Fig.

Claims (4)

[Claims] (1) In a laser device that excites a laser medium with an excitation light source to cause laser oscillation, fine spherical particles or fine powder such as crystals of a substance that becomes the laser medium in a solid state are dispersed in a medium transparent to the oscillation light. A laser device using a powder laser medium characterized in that it is formed by suspending the powder laser medium. (2) A laser device using a powder laser medium according to claim 1, wherein the fine powder is a fine powder of YAG polycrystal. (3) A laser device using a powder laser medium according to claim 1, wherein the medium transparent to the oscillation light is gas, liquid, glass, or resin. (4) A laser device using a powder laser medium according to claim 1, wherein the transparent medium is argon gas.