JPH0451495Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a solid-state laser device using a slab-type solid-state laser medium, and particularly relates to a solid-state laser device incorporating a cooling device.

(Summary of the invention) The invention provides a solid-state laser device that uses a slab-type solid-state laser medium and incorporates a cooling device.
By fixing a slab-type solid-state laser medium and a holding case that holds the laser medium with adhesive, external force applied to the laser medium is removed and laser light output with high oscillation efficiency can be obtained. It is.

(Prior Art) The fact that a slab-type solid-state laser medium is often used as a laser medium in solid-state laser devices is as follows.
For example, it is widely known as shown in Japanese Patent Publication No. 48-15599. This is because the laser beam travels through the laser medium while being totally reflected between its two opposing surfaces (main surfaces), which causes a relatively high-temperature center area to be separated from a relatively low-temperature peripheral area. This is because there are various advantages such as being able to reduce the influence of the thermal lens effect and increasing the destruction limit of the laser medium by passing the laser medium alternately.

In such a solid-state laser device, the oscillation efficiency of the laser beam (the ratio of the output energy of the laser beam to the energy input to the excitation light source) is usually as low as 2% or less, so most of the input energy becomes heat. As a result, the laser medium is heated and may be destroyed, so a cooling device is usually required. A liquid cooling type is often used as this cooling device, but a strict seal is required to prevent the liquid from leaking to the outside. As the sealing member, an O-ring made of an elastic material such as rubber is used, and a structure in which the O-ring is brought into contact with the periphery of a slab-shaped solid-state laser medium is often used.

However, since the laser medium is strongly pressed by the O-ring, the flatness of the main surface deteriorates, which changes the angle of incidence for total reflection, causing the laser beam to be totally reflected to pass through the laser medium. There is a problem that the direction of the light transmitted or reflected from the main surface changes, which in turn reduces the oscillation efficiency of the laser light.In particular, in slab-type solid-state laser media, the laser light is most strongly excited at the main surface. Therefore, deterioration of the flatness of the main surface becomes a big problem.

A conventional solid-state laser device will be explained below with reference to FIGS. 5 and 6. FIG. 5a is a vertical cross-sectional view of a conventional solid-state laser device, and FIG. 5b is a vertical cross-sectional view of a conventional solid-state laser device.
It is an arrow view of the X direction. FIG. 6 is a perspective view showing the state in which the slab-type solid-state laser medium is housed in the holding case.

5 and 6, 1 is a slab-type solid-state laser medium, 2 is a lamp as an excitation light source, and 3 is a slab-type solid-state laser medium.
3a is a holding case that accommodates the laser medium; 3a is an opening formed in the case 3 to allow the coolant to enter and exit;
4 is a light source case that accommodates the lamp 2 and has a reflecting mirror 11 formed on its inner surface; 5 is an O-ring that supports the laser medium 1 in the holding case 3 and seals the coolant 15 from leaking to the outside; 6 is a light source case that houses the lamp 2; A holding plate for holding the O-ring; 7 a screw for fixing the holding plate 6 to the holding case 3; 8 a total reflection mirror forming an optical resonator; 9 a semi-transmissive mirror forming an optical resonator; 10 is an oscillated laser beam. Pure water and ethylene glycol are used as the coolant 15, and the laser medium 1 and the lamp 2 are cooled by the coolant 15.

(Problems to be Solved by the Invention) The purpose of the invention is to eliminate the above-mentioned difficulties in solid-state laser devices using conventional slab-type solid-state laser media. That is, the present invention is a solid-state laser device using a slab-type solid-state laser medium suitable for incorporating a cooling device, and which removes external force applied to the slab-type solid-state laser medium to generate laser light output with high oscillation efficiency. The object of the present invention is to provide a solid-state laser device having the following features.

(Means for Solving the Problems) The solid-state laser device according to the present invention includes a slab-shaped solid-state laser medium, a holding case that holds the slab-shaped solid-state laser medium, and a cooling medium that cools the slab-shaped solid-state laser medium. A portion of the main surface of the slab-type solid-state laser medium that does not participate in the optical path of the laser beam propagating in the slab-type solid-state laser medium, and a portion of the side surface of the slab-type solid-state laser medium that It is characterized in that the slab-shaped solid-state laser medium is fixed to the holding case by applying an adhesive to the portion formed including the portion connecting the portions.

(Function) Since the surface of the slab-shaped solid-state laser medium is fixed to the holding case with an adhesive, no external force is applied to the laser medium, and the flatness of the main surface of the laser medium is maintained. In addition, among the main surfaces,
The portion that is not involved in the optical path of the laser beam propagating in the slab-shaped solid-state laser medium is fixed to the holding case with adhesive, which prevents the laser beam from progressing due to total reflection between the main surfaces of the laser medium. This will be prevented.

A sealing portion having an appropriate width can be formed around the entire circumference of the slab-shaped solid-state laser medium, and the cooling medium can be completely sealed with a relatively small amount of adhesive.

(Example) Hereinafter, a solid-state laser device according to the present invention will be explained using the drawings.

FIG. 1a is a longitudinal cross-sectional view of a solid-state laser device according to the present invention, and FIG. 1b is a view taken along the Y-Y direction. Figure 2a shows the slab-type solid-state laser medium 1.
FIG. 2b is a perspective view showing a state in which the holding member 12 and the connecting rod 13 constituting the holding case are held, and FIG. 2b is a partially cut away plan view.

In these figures, the same reference numerals are used for the same parts as in FIGS. 5 and 6. The difference from FIGS. 5 and 6 is that in the present invention, holding cases 12 and 13 are used instead of holding case 3 to hold laser medium 1. The holding cases 12 and 13 and the light source case 4
O to prevent the coolant 15 from leaking from the boundary between
The ring 5A is used as a sealing member, and the holding plate 6A is fixed to the light source case 4 with screws 7 so as to press the O-ring 5A (not shown in FIG. 1a). Furthermore, instead of the O-ring 5 in the prior art, in the present invention an adhesive 14 is used to fix the laser medium 1 to the holding member 12 as shown in FIG. Note that although a liquid is used as the cooling medium in this embodiment, a gas may also be used.

As the laser medium 1, for example, phosphate-based,
Nd: Glass LHG8 (product name of HOYA Corporation, refractive index 1.52) is used. In addition to this, Nd:
Other solid state laser media such as YAG, Nd:GGG, YLF may also be used. The shape of the laser medium 1 is a slab shape (plate shape), as shown in FIG. That is, the dimensions of the laser medium 1 are 5 mm (H) x 60 mm.
(W) x 185.8mm (L), main surfaces 1a, 1b
and the irradiation surface 1f, 1 where the laser beam enters and exits.
The angle θ formed with e is 33.34°. The flatness of the main surfaces 1a and 1b, which serve as excitation surfaces facing each other in parallel, is approximately λ/4 (λ: wavelength of the laser beam). Note that λ is 633 nm. Side surfaces 1c and 1d are main surfaces 1a,
It is perpendicular to 1b.

As shown in FIG. 4a, the laser beam A incident on the laser medium 1 travels in a zigzag pattern between the opposing main surfaces 1a and 1b due to total reflection. At this time, portions B and C that do not participate in the formation of the optical path of the laser beam A are generated in the main surfaces 1a and 1b. Figure 4b is
This figure shows a state in which the above-mentioned portions B and C that occur on the main surfaces 1a and 1b of the laser medium 1 and the portions D and E that connect the above-mentioned B and C on the side surfaces 1c and 1d are formed in a band shape. Therefore, when holding the laser medium 1 in the holding cases 12 and 13 using the adhesive 14, if the above-mentioned B, C, D, and E are the adhesive parts, the refractive index of the laser medium 1 and the adhesive 14 is It is possible to prevent the progress of the laser beam A from being hindered by total reflection in the laser medium due to the difference.

As shown in FIG. 2, the holding case is composed of a pair of holding members 12, 12 and connecting rods 13, 13. The holding member 12 has a gap 12a formed therein for accommodating both ends of the laser medium 1 in the longitudinal direction, and the inner end surfaces of the holding members 12, 12 are formed so as to correspond to the adhesive parts B, C, D, and E. , is machined into a slope as shown in Figure 2. The pair of holding members 12, 12 are connected by a pair of connecting rods 13, 13, and the laser medium 1 is housed in the holding cases 12, 13. The holding members 12, 12 are made of aluminum material, and the surfaces thereof are treated with black alumite. Further, the void 12a is formed by the laser medium 1.
A slightly larger size is sufficient. Connecting rod 1
3 and 13 are made of stainless steel, but since the laser medium 1 and the connecting rod 13 are both heated by the light from the lamp 2, it is desirable to use a material with a coefficient of thermal expansion close to that of the laser medium 1. . The holding case is connected to a pair of holding members 12, 12 and a connecting rod 13,
By dividing the laser medium 1 into 13, it is possible to correct dimensional errors in the longitudinal direction of the laser medium 1.

The adhesive 14 that fixes the laser medium 1 and the holding member 12 may be an vinyl adhesive or an epoxy adhesive, but preferably a silicone adhesive, which has the smallest change in volume when cured. In this example, Bondo was used as a silicone adhesive.
MOS 10 (Konishi Co., Ltd. product name) is used. In Figure 4b, the thickness of the adhesive layer formed in the parts indicated by B, C, D, and E is 2 mm, and the width is 3 mm.
mm.

In the above example, the beam shape of the oscillated laser light was 5 mm (H) x 60 mm (W), and the oscillation efficiency was approximately twice that of the conventional one.

(Effects of the invention) As explained above, according to the invention, since the slab-type solid-state laser medium and the holding case are fixed with adhesive, the external force applied to the laser medium is removed, and the oscillation efficiency is high. Laser light output can be obtained. Furthermore, since the optical path of the laser beam is not affected by the adhesive, it is possible to prevent a decrease in the output of the laser beam.

Furthermore, compared to a seal portion constructed by assembling O-rings and other parts, the number of parts is reduced, the manufacturing process is simplified, and material costs can be reduced.

[Brief explanation of the drawing]

FIG. 1a is a longitudinal cross-sectional view of a solid-state laser device according to the present invention, FIG. 1b is a view taken along the Y-Y direction,
FIG. 2a is a perspective view showing the state in which the slab-type solid-state laser medium is held by the holding case;
Figure b is a partially cut away plan view of Figure 2a, Figure 3a is a perspective view of the slab-type solid-state laser medium, Figure 3b is a plan view of the slab-type solid-state laser medium, Figure 4a Figure 4b shows the state in which laser light travels through a slab-type solid-state laser medium.
FIG. 5a is a vertical cross-sectional view of a conventional solid-state laser device, and FIG. 5b is a view taken in the X-X direction of the solid-state laser device. , and FIG. 6 are perspective views showing a state in which the laser medium in FIG. 5 is accommodated in a holding case. Explanation of reference symbols, 1...Slab type solid laser medium, 1a, 1b, 1c, 1d, 1e, 1f...Surface of slab type solid laser medium, 12, 13...Holding case, 14...Adhesive, 15 ...Cooling liquid, A
...Laser light, B, C, D, E...Adhesive part.

Claims (1)

[Scope of utility model registration request] A slab-type solid-state laser medium 1, holding cases 12 and 13 that hold the slab-type solid-state laser medium,
Cooling medium 1 for cooling the slab-shaped solid-state laser medium
5, of the main surfaces 1a and 1b of the slab-type solid-state laser medium,
Portions B and C that are not involved in the optical path of the laser beam A propagating in the slab-type solid-state laser medium and portions D and E that connect the portions B and C of the side surfaces 1c and 1d of the slab-type solid-state laser medium. A solid-state laser device characterized in that the slab-shaped solid-state laser medium is fixed to the holding case by applying an adhesive 14 to portions B, C, D, and E formed of the solid-state laser medium.