JPH06152021A - Solid-state laser device - Google Patents

Abstract

PURPOSE:To improve a beam quality by suppressing lens effects by absorbing short wavelength component which does not contribute to the excitation and preventing the reflection of long wavelength component. CONSTITUTION:A solid-state laser device is provided with a rod part 1, which outputs laser light beams when it is excited, a lamp part 2, which projects exciting light, a short wavelength light absorbing part 3 arranged to surround the rod part 1 and the lamp part 2 and a wavelength selecting/reflecting part 11, which is arranged around the short wavelength light absorbing part 3 so as to permit harmful long wavelength light component to pass through and permit other exciting light beams to reflect.

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 device, and more particularly to a technique for suppressing the thermal lens effect between rods to improve beam quality.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a conventional structure of a rod type solid-state laser device such as Nd.YAG. In FIG. 4, reference numeral 1 is a rod portion (laser light generating rod), 2 is a lamp portion (excitation lamp), 3 is a short wavelength light absorbing portion, 4 is a casing, 5 is a reflecting surface, 6 is a rod cooling flow path, Reference numeral 7 is a lamp cooling flow path, and 8 is a reflecting cylinder.

Laser light is generated by applying excitation light from the lamp section 2 to the rod section 1, and
In this case, an oscillation state is obtained by reciprocating between a pair of mirrors. In this case, 300 nm to 400 nm of the excitation light is used.
By absorbing the short-wavelength component of not more than nm that does not contribute to the excitation by the short-wavelength light absorber 3 made of Sm (samarium) -doped glass, the temperature rise of the rod portion 1 can be limited.

[0004]

However, the pumping light contains a harmful wavelength component having a long wavelength of, for example, 820 nm or more that does not contribute to the pumping, and is reflected by the reflecting surface 5 to cause rod portion 1 and the like. Accompanying the phenomenon of being absorbed by. Rod part 1
The harmful wavelength component absorbed by the heat energy increases the temperature of the rod portion 1 due to heat energy, and the heat having the property of an optically convex lens is generated based on the occurrence of a difference in thermal expansion and the change in the refractive index due to internal stress. There is a possibility that a phenomenon called a lens effect will occur, and the path of the laser light will be deviated from the optical axis to deteriorate the beam quality.

The present invention has been made in view of these circumstances, and suppresses generation of a thermal lens effect and improves beam quality by absorbing short wavelength components that do not contribute to excitation and preventing reflection of long wavelength components. The purpose is to let.

[0006]

[Means for Solving the Problems] Various means for solving these problems are proposed. The solid-state laser device according to claim 1 has a rod portion that outputs laser light during excitation, a lamp portion that is disposed on a side portion of the rod portion and that emits excitation light, and a state in which the rod portion and the lamp portion are surrounded. A short-wavelength light absorption section that is arranged to absorb harmful short-wavelength light components in the excitation light and a short-wavelength light absorption section that is arranged around the short-wavelength light absorption section to pass harmful long-wavelength light components and reflect other excitation light. A configuration including a wavelength selective reflection section is adopted. In the solid-state laser device according to claim 2, the wavelength selective reflection part is a dielectric coating layer integrally formed on the outer peripheral surface of the short wavelength light absorption part, and the high refractive index in which the dielectric coating layers are alternately stacked. A structure including a refractive index layer and a low refractive index layer is added to the laser device according to claim 1. The solid-state laser device according to claim 3 has a configuration in which a long-wavelength light absorbing portion that absorbs a long-wavelength light component that has passed around the wavelength selective reflection portion is arranged in the laser device according to claim 1 or 2. I am trying to do it.

[0007]

In the solid-state laser device according to the first aspect, the pumping light generated in the lamp section passes through the short-wavelength light absorbing section to absorb and remove harmful short-wavelength light components, and the pumping light is wavelength-selectively reflected. When reaching the area, harmful long-wavelength light components are removed by passing therethrough, and other excitation light is returned by reflection, whereby repeated excitation is performed. In the solid-state laser device according to claim 2, in addition to the function according to claim 1, only the excitation light of the component effective for excitation is reflected at each boundary of the dielectric coating layer on the outer peripheral surface of the short-wavelength light absorption portion and reflected. Keep the surface covered by the dielectric coating layer. In the solid-state laser device according to claim 3, in addition to the function according to claim 2, the long-wavelength light component that has once passed through the wavelength selective reflection part is absorbed by the long-wavelength light absorption part and returns to the inside by reflection or the like. Is prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a solid-state laser device according to the present invention will be described below with reference to FIGS.

In the embodiment, as shown in FIG. 1, the short wavelength light absorbing portion 3 arranged so as to surround the rod portion 1 and the lamp portion 2 is formed to have a cylindrical outer periphery. Around the short-wavelength light absorption unit 3, a wavelength selection reflection unit 11 that allows harmful long-wavelength light components to pass and reflects other excitation light is arranged.

The wavelength selective reflection part 11 is a dielectric coating layer integrally formed on the cylindrical outer peripheral surface of the short wavelength light absorption part 3. More specifically, the dielectric coating layer is, for example, It is formed by alternately stacking high refractive index layers and low refractive index layers containing a dielectric such as MgF _2, and the thickness of both refractive layers is 8 nm at 400 nm or more to be reflected.
It is set to a quarter wavelength optical thickness in the wavelength range of less than 50 nm.

On the inner surface of the casing 4, a long wavelength absorbing portion 12 for absorbing a long wavelength light component is arranged. The long-wavelength absorbing portion 12 is formed of a material that easily absorbs infrared light (long-wavelength light), such as a black-painted metal surface or a black ceramic surface. And the wavelength selective reflection part 1
An outer cooling flow path 13 is formed between 1 and the long wavelength absorption portion 12.

In the solid-state laser device having such a structure, a case where laser light is generated by irradiating the rod portion 1 with the excitation light generated in the lamp portion 2 will be described below.

When the lamp unit 2 is, for example, a xenon flash lamp, it has a spectral distribution as shown in FIG. 2, and therefore, the spectral distribution and the excitation light absorption characteristic of the rod unit 1 are consistent with each other. Becomes important.
If the rod portion 1 is, for example, one that is Nd-doped at 1%, as shown in FIG.
In the vicinity of the wavelength of 9 nm, the transmittance is lowered and the absorptivity is increased, and the Nd ions are absorbed to contribute to the emission of laser light.

Therefore, when the excitation light generated in the lamp unit 2 passes through the short wavelength absorption unit 3, the short wavelength component of 300 nm to 400 nm or less contained in the excitation light is absorbed, and the rod. It reaches the section 1 or the wavelength selective reflection section 11.

The excitation light reaching the rod portion 1 excites the laser light, while the excitation light reaching the wavelength selective reflection portion 11 has a short wavelength component of 850 nm or less. The light is reflected at the boundary with the wavelength absorption section 3 and again contributes to laser oscillation by repeatedly irradiating the rod section 1 via the short wavelength absorption section 3 and a wavelength component of 850 nm or more is emitted. After passing through the selective reflection section 11, it reaches the long wavelength absorption section 12 and is absorbed.

The rod portion 1, the lamp portion 2, the short wavelength light absorbing portion 3, the long wavelength absorbing portion 12, or the long wavelength absorbing portion 12, which has become a high temperature by absorbing the excitation light generated in the lamp portion 2, or
The wavelength selective reflection part 11 which has become a high temperature state by absorbing the wavelength component of 850 nm or more is cooled by inserting cooling water into the rod cooling flow path 6, the lamp cooling flow path 7 and the outer cooling flow path 13, etc. It

[0017]

The solid-state laser device according to the present invention has the following excellent effects. (1) A rod portion that outputs laser light when excited, a lamp portion that is arranged on the side portion thereof, a short wavelength light absorbing portion that surrounds the rod portion and the lamp portion, and a wavelength selective reflection portion that is arranged around the rod portion and the lamp portion. By including the excitation light in a state where the short-wavelength light component and the long-wavelength light component are removed, the rod portion is repeatedly irradiated, the laser light is excited, and the harmful short-wavelength light is generated when the laser light is generated. It is possible to reduce the heating amount of the rod portion due to the light component and the long-wavelength light component, suppress the occurrence of the lens effect of the rod portion, and improve the beam quality. (2) The wavelength selective reflection part is integrally formed on the outer peripheral surface of the short wavelength light absorption part, so that a reflection surface is formed at these boundaries to efficiently reflect the excitation light and the excitation effect of the rod part. It is also possible to stabilize the reflection of the excitation light by improving the reflection resistance and covering the reflection surface with a coating layer to protect the reflection surface. (3) By disposing the long-wavelength light absorbing section around the wavelength-selective reflection section, the long-wavelength light that has passed through the wavelength-selective reflection section is absorbed, and the long-wavelength light is again converted into the wavelength-selective reflection section or the short-wavelength light. It is possible to suppress the occurrence of the phenomenon of returning to the absorption section and utilize the effective component of the excitation light to excite the laser.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a solid-state laser device according to the present invention.

FIG. 2 is a relationship curve diagram between a wavelength of excitation light and a normalized spectrum output.

FIG. 3 is a relationship curve diagram between an excitation light wavelength and a transmittance in a laser light generating rod.

FIG. 4 is a cross-sectional view showing a conventional example of a solid-state laser device.

[Explanation of symbols]

 1 Rod Part (Rod Light Generation Rod) 2 Lamp Part (Excitation Lamp) 3 Short Wavelength Light Absorbing Part 4 Casing 5 Reflecting Surface 6 Rod Cooling Flow Path 7 Lamp Cooling Flow Path 11 Wavelength Selective Reflecting Part (Dielectric Coating Layer) 12 Long wavelength absorption part 13 Outside cooling flow path

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichiro Wazumi 3-15-1, Hoshu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Ltd. Toji Technical Center (72) Inventor Akihiro Nishimi Koto-ku, Tokyo Hoshu 3-chome 1-15 Ishikawajima Harima Heavy Industries Co., Ltd. Toji Technical Center

Claims (3)

[Claims] 1. A rod portion that outputs laser light during excitation, a lamp portion that is disposed on a side portion of the rod portion and that emits excitation light, and a rod portion that surrounds the rod portion and the lamp portion. A short-wavelength light-absorbing portion that absorbs harmful short-wavelength light components therein, and a wavelength-selective reflector that is disposed around the short-wavelength light-absorbing portions and that passes harmful long-wavelength light components and reflects other excitation light. A solid-state laser device comprising: 2. The wavelength selective reflection part is a dielectric coating layer integrally formed on the outer peripheral surface of the short wavelength light absorption part,
2. The solid-state laser device according to claim 1, wherein the dielectric coating layer is composed of a high refractive index layer and a low refractive index layer which are alternately laminated. 3. The solid-state laser device according to claim 1, further comprising a long-wavelength light absorbing portion that absorbs a long-wavelength light component that has passed around the wavelength selective reflection portion.