JPH0992911A - Slab solid laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce vast time and cost necessary for the high precision polishing of a slab laser crystal, by filling the part between at least one main surface of slab type laser crystal and a transparent plate formed on the main surface, with medium having almost the same refractive index as that of the laser crystal. SOLUTION: A laser crystal 11 is put in a section constituted of a transparent plate 16 and a transparent window 17, and its space is filled with medium 15 having almost the same refractive index as that of the laser crystal 11. The refractive index of the transparent plate 16 is smaller than that of the laser crystal 11. The pumping ligiht sent forth from the pumping lamp 12 is reflected by the peripheral reflecting cylinder 13 and guided to a slab laser 11. As a result, a laser active member in the laser crystal 11 is excited, and laser oscillation is generated. Laser light is totally reflected by the surface of the transparent plate 16, i.e., the surface of the laser crystal 11 side of the transparent 16, propagates zigzag in the laser crystal 11 and the medium 15, and sent forth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high power slab type solid state laser device such as an Nd: YAG laser.

[0002]

2. Description of the Related Art FIG. 4 shows a sectional view of the main part of a conventional high-power slab type solid-state laser device. Excitation light emitted from the excitation lamp 2 is reflected by the reflecting cylinder 3 around the excitation lamp 2 and guided to the slab type laser crystal 1. As a result, the laser activator in the laser crystal 1 is excited and laser oscillation occurs. At this time, in the slab type laser crystal 1, as shown in FIG. 3, a laser beam is generated as shown by its optical axis 8. As shown in the drawing, the laser light propagates in a zigzag manner while being totally reflected on the inner surface thereof. 4 is a filter for blocking ultraviolet rays not involved in excitation,
A cooling medium 9 is flown between the laser crystal 1 and the filter 4.

[0003]

The polishing accuracy of the total reflection surface of the slab type laser crystal 1 is λ, where λ is the wavelength.
A high precision of / 10 is required. With a large polishing area, it reaches approximately 25 x 200 mm and, for example, N
Since the wavelength of the d: YAG laser is 1.06 μm, λ / 1
High precision polishing of 0 not only takes time, but also leads to high price of the solid-state laser device.

It is generally said that the enormous time and cost required for highly accurate polishing of a slab crystal occupy about half the price of a slab type laser crystal. In view of the above problems, an object of the present invention is to provide a low-cost slab-type solid-state laser device that reduces the enormous time and cost required for highly accurate polishing of a slab-type laser crystal.

[0005]

In order to solve the above problems, a slab type solid-state laser device of the present invention comprises a laser crystal between at least one main surface of a slab type laser crystal and a transparent plate provided thereon. It is assumed that the medium having the same refractive index as that of is filled. Further, at least one main surface of the slab type laser crystal may be covered with a medium having substantially the same refractive index as the laser crystal.

By doing so, the total reflection surface of the laser light can be changed to the surface of the medium or the surface of the transparent plate.
If the refractive index of the transparent plate is smaller than that of the laser crystal, total reflection of laser light occurs on the surface of the transparent plate,
If the refractive index of the transparent plate is larger than that of the laser crystal, total reflection of laser light occurs on the back surface of the transparent plate.

[0007]

In order to solve the above problems, a slab-type solid-state laser device of the present invention is a medium having a refractive index substantially the same as that of the laser crystal between at least one main surface of the slab-type laser crystal and the transparent plate. Or by covering at least one main surface of the slab type laser crystal with a medium having almost the same refractive index as that of the laser crystal, the total reflection surface can be more easily obtained from the slab crystal surface. The surface of the substance is changed.

Normal slab crystals have high hardness. For example,
The Mohs hardness of YAG crystals, which is often used, exceeds 8, but that of glass is about 5. Therefore, polishing the glass saves polishing time. Hereinafter, embodiments of the present invention will be described with reference to the drawings. [Embodiment 1] FIG. 1 is a sectional view of a slab type solid-state laser device according to a first embodiment of the present invention.

Excitation lamp 12 and converging reflector 13
Is arranged on both upper and lower surfaces of the slab type laser crystal 11 as in the conventional example of FIG.
Is placed in a space defined by a transparent plate 16 and a transparent window 17, and the space is filled with a medium 15 having substantially the same refractive index as the laser crystal 11. Transparent plate 16
The refractive index of is smaller than that of the laser crystal 11.

The excitation light emitted from the excitation lamp 12 is guided to the slab type laser crystal 11 by being reflected by the reflecting cylinder 13 around it. As a result, the laser activator in the laser crystal 11 is excited and laser oscillation occurs. At this time, the laser light is emitted from the laser crystal 11 and the medium 1.
While being totally reflected by the surface of the transparent plate 16, that is, the surface of the transparent plate 16 on the side of the laser crystal 11 inside 5, the light propagates in zigzag as shown by the optical axis 18 and is emitted.

In FIG. 1, for example, when Nd: YLF (yttrium lithium fluoride) having a refractive index of 1.45 is used as the laser crystal 11, as a cooling medium,
By mixing carbon tetrachloride having a refractive index of 1.46 and a liquid having a low refractive index, it is possible to easily match the refractive indexes of the slab crystal and the cooling medium. If CaF ₂ having a refractive index of 1.43 is used as the transparent plate 16,
A configuration in which total reflection is performed on the surface of the transparent body as shown in FIG.

Thus, by changing the total reflection surface from a slab crystal to another material, a highly accurate reflection surface can be easily constructed, and the time and cost required for highly accurate polishing of a slab type laser crystal can be saved. It is possible to use an inexpensive slab crystal. [Embodiment 2] FIG. 2 is a sectional view of a slab type solid-state laser device according to a second embodiment of the present invention.

In this example, the transparent plate 26 is made of a material having a higher refractive index than the slab type laser crystal 21 and the medium 25. The laser light in that case is the laser crystal 21.
Then, it enters the transparent plate 26 through the medium 25, and is totally reflected by the surface of the transparent plate 26 on the lamp 22 side. In FIG. 2, for example, as the laser crystal 21, Nd: Y having a refractive index of 1.45 is used.
When LF (yttrium lithium fluoride) is used, carbon tetrachloride having a refractive index of 1.46 and a liquid having a low refractive index are mixed as a cooling medium to easily form a slab crystal and a cooling medium. The refractive indices can be matched. As the transparent plate 26, for example, a glass having a refractive index of 1.5 or more, and more preferably lead glass having a large refractive index is used, and it may be configured to totally reflect on the back surface of the transparent plate 26 as shown in FIG. it can.

In the embodiment shown in FIGS. 1 and 2, the medium 1 is used.
Although 5 and 25 have a structure which also serves as a cooling medium for the laser crystals 11 and 21, if it is difficult, a separate cooling structure may be provided. In addition to the above, various combinations of the slab type laser crystal, the medium and the transparent plate can be considered. [Third Embodiment] FIG. 3 is a sectional view of a slab type solid-state laser device according to a third embodiment of the present invention.

In this example, a solid medium 35 having the same refractive index as the laser crystal 31 is bonded to the laser crystal 31. The surface of the medium 35 is processed into a highly accurate surface,
It becomes a total reflection surface. Therefore, however, it may be necessary to cool with the cooling medium 39. It is desirable that the medium 35 has not only the same refractive index as that of the laser crystal 31 but also light resistance and high thermal conductivity. In this case, the transparent plate in the first and second embodiments becomes unnecessary.

[0016]

As described above, in the slab type solid-state laser device of the present invention, a medium having substantially the same refractive index as that of the laser crystal is filled between the main surface of the slab type laser crystal and the transparent plate,
Alternatively, by covering at least one main surface of the slab type laser crystal with a medium having substantially the same refractive index as the laser crystal, the total reflection surface can be easily obtained from the surface of the slab type laser crystal with a higher precision surface. It can be changed to the surface of the substance.

For example, by using glass that is easy to process, it is not necessary to perform high-precision processing on the total reflection surface of the slab type laser crystal, which has been absolutely necessary in the past, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a slab type solid-state laser device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a slab type solid state laser device according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a slab type solid state laser device according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a conventional slab type solid-state laser device.

[Explanation of symbols]

 1, 11, 21, 31 Laser crystal 2, 12, 22 Lamp 3, 13 Reflecting tube 4, Filter 8, 18 Optical axis 9, 39 Cooling medium 15, 25, 35 Medium 16, 26 Transparent plate 17 Window

Claims (4)

[Claims] 1. In a solid-state laser device using a slab type crystal, a medium having substantially the same refractive index as that of the laser crystal is filled between at least one main surface of the slab type laser crystal and a transparent plate provided thereon. A slab type solid-state laser device characterized in that 2. A solid-state laser device using a slab-type crystal, wherein at least one main surface of the slab-type laser crystal is covered with a medium having substantially the same refractive index as the laser crystal. 3. The slab type solid-state laser device according to claim 1, wherein the transparent plate has a refractive index smaller than that of the laser crystal. 4. The slab type solid state laser device according to claim 1, wherein the transparent plate has a refractive index higher than that of the laser crystal.