CN103996964A - Hollow mirror laser resonant cavity - Google Patents

Abstract

The invention provides a hollow mirror laser resonant cavity. The hollow mirror laser resonant cavity is characterized in that a totally-reflecting mirror, a laser gain medium and a planar output mirror are sequentially arranged on a light path of the hollow mirror laser resonant cavity; the totally-reflecting mirror or the planar output mirror is a totally-reflecting plane mirror, wherein a circular hole with the diameter ranging from 0.5 mm to 5 mm is formed in the center of the totally-reflecting plane mirror, and the totally-reflecting plane mirror is used for obtaining hollow Gaussian beams; the various forms of hollow Gaussian beams are obtained by changing the central pore size or changing the circular hole in the totally-reflecting mirror or the planar output mirror. According to the hollow mirror laser resonant cavity, the hollow Gaussian beams can be obtained, and the beams beneficial to material processing are generated at low cost; usage of the totally-reflecting mirror with the small hole in the center or the planar output mirror with the small hole in the center is determined, so that different types of space light intensity distribution are realized according to actual needs; the size of the hole is changed reasonably to meet the requirement for beam spatial characteristics according to actual needs.

Description

Hollow Mirror Laser Resonator

technical field

The invention belongs to the technical field of lasers, in particular to a laser resonant cavity composed of a hollow mirror, and relates to a hollow mirror laser resonant cavity.

Background technique

The laser beams output by the lasers in the prior art are all Gaussian beams, that is, the light intensity distribution on the cross section of the laser beam is distributed in the form of a Gaussian function. For Gaussian distribution of light intensity, the energy in the center of the spot is strong and the energy in the side is weak. Such light intensity distribution is not conducive to the application of laser cladding and welding. How to adopt a simple, easy and cheap method to obtain relatively uniform laser light intensity distribution is one of the hotspots in laser application research. To obtain a uniform laser beam with light intensity distribution, the traditional laser output is passed through an integrator mirror, π-shaped It can be achieved by shaping and homogenizing the laser beam with devices such as mirrors and microlens arrays. Although this type of method can obtain a laser spot with a relatively uniform light intensity distribution, these special lenses are expensive, and as the light intensity distribution of the laser output changes, the homogenization effect is inconsistent, which affects the stability of the laser in application. sex.

Contents of the invention

The invention overcomes the above-mentioned defects, and aims to effectively control the central light intensity of laser oscillation through the resonator, solve the problem of obtaining a laser beam with a relatively uniform light intensity distribution on the beam cross section directly from the laser, and provide a hollow mirror laser resonant cavity.

Brief description of the content of the hollow mirror laser resonator of the present invention:

The hollow mirror laser resonator of the present invention is characterized in that: the optical path of the hollow mirror laser resonator is followed by a total reflection mirror, a laser gain medium and a plane output mirror; Hollow Gaussian beams can be obtained by the total reflection plane mirror with 5mm round hole, and various forms of hollow Gaussian beams can be obtained by changing the size of the central aperture, or changing the round hole on the total reflection mirror or the output mirror.

On the optical path of the hollow mirror laser resonator, there are total reflection mirror, laser gain medium and planar output mirror in sequence. The center of the total reflection mirror is provided with a circular hole with a diameter of 0.5mm to 5mm, and the planar output mirror is a high reflection without holes in the center. rate flat output mirror.

On the optical path of the hollow mirror laser resonator, there are total reflection mirror, laser gain medium and planar output mirror in sequence. Flat output mirror.

On the optical path of the hollow mirror laser resonator, there are total reflection mirror, laser gain medium and planar output mirror in sequence. The total reflection mirror and the planar output mirror are high-reflectivity planar output with circular holes with a diameter of 0.5 mm to 5 mm in the center. mirror.

The hollow mirror laser cavity of the present invention can obtain a hollow Gaussian beam, which is a low-cost way to produce a beam that is beneficial to material processing; it can be determined to use a total reflection mirror or an output mirror with a small hole in the center according to the needs of the application, so that Realize different spatial light intensity distribution; according to the needs of the application, the size of the aperture can be reasonably changed to meet the needs of the spatial characteristics of the beam.

Description of drawings

Fig. 1 is the structural representation of hollow mirror laser cavity embodiment 1;

Fig. 2 is the axial light intensity distribution diagram that hollow mirror laser cavity embodiment 1 produces;

Fig. 3 is the structural representation of hollow mirror laser cavity embodiment 2;

Fig. 4 is the axial light intensity distribution figure that embodiment 2 of hollow mirror laser resonator produces;

Fig. 5 is the structural representation of hollow mirror laser cavity embodiment 3;

Fig. 6 is the axial light intensity distribution figure that embodiment 3 of hollow mirror laser resonator produces;

Fig. 7 is a diagram of a refractory brick ablation material generated by a laser beam;

Fig. 8 is a Gaussian beam ablation refractory brick material diagram;

In the figure: 1 is a total reflection mirror, 2 is a laser gain medium, and 3 is a plane output mirror.

Detailed ways

The optical path of the hollow mirror laser resonator of the present invention is followed by a total reflection mirror, a laser gain medium, and an output mirror; For the light beam, various forms of hollow Gaussian light beams can be obtained by changing the size of the central aperture, or changing the circular hole on the total reflection mirror or the plane output mirror.

Example 1

As shown in Figure 1, the optical path of the hollow mirror laser resonator consists of a total reflection mirror 1, a laser gain medium 2, and a planar output mirror 3. The center of the total reflection mirror 1 is provided with a circular hole with a diameter of 0.5 mm to 5 mm, and the plane output Mirror 3 is a high reflectivity flat output mirror with no hole in the center.

working principle

During the establishment of the laser in the resonant cavity, since the center of the total reflection mirror 1 contains a circular hole, the central low-order mode part of the original Gaussian beam is partially suppressed, see Figure 2 for the axial light intensity distribution diagram, The resulting hollow Gaussian beam can obtain a uniform temperature field distribution when interacting with the material.

Example 2

As shown in Figure 3, the optical path of the hollow mirror laser resonator is followed by a total reflection mirror 1, a laser gain medium 2 and a plane output mirror 3. The center of the total reflection mirror 1 has no hole, and the center of the plane output mirror 3 is provided with a diameter of 0.5mm. High reflectivity planar output mirror with ~5mm circular aperture.

working principle

See Fig. 4, the axial light intensity distribution of the light beam generated by the resonant cavity of embodiment 2, since the center of the plane output mirror 3 is provided with a circular hole with a diameter of 0.5 mm to 5 mm, it will more effectively suppress the low-order Gaussian beam For the part of the mode, the axial light intensity distribution roadmap is less than that of the embodiment 1, and the part of the fundamental mode oscillates less.

Example 3

As shown in Figure 5, the optical path of the hollow mirror laser resonator is followed by a total reflection mirror 1, a laser gain medium 2 and a plane output mirror 3, and the centers of the total reflection mirror 1 and the plane output mirror 3 are all equipped with a diameter of 0.5mm~ High reflectivity flat output mirror with 5mm circular aperture.

working principle

See Fig. 6, which is the axial light intensity distribution of the light beam generated by the resonant cavity of embodiment 3. Since the centers of the total reflection mirror 1 and the plane output mirror 3 are provided with circular holes with a diameter of 0.5 mm to 5 mm, the fundamental mode Gaussian beam is almost There is no oscillation and the central light intensity is very weak.

See Figure 7 for the beam ablation refractory brick material produced in the present invention, see Figure 8 for the result of general Gaussian beam ablation refractory brick material. It can be clearly seen that the temperature field distribution generated by the hollow Gaussian beam generated by the hollow mirror resonator in the interaction with the material is more uniform, which is more conducive to the processing of the material.

The invention proposes a hollow mirror laser resonant cavity on the basis of the existing parallel plane cavity lamp-pumped solid-state laser. During the process of laser oscillation in the resonant cavity of a plane mirror with a circular hole with a diameter of 0.5 mm to 5 mm in the center, the low-order mode is suppressed to a certain extent, and the output beam intensity distribution is no longer the traditional Gaussian distribution, thereby realizing the center Weak, marginally strong light intensity distribution. Compared with the traditional Gaussian beam, the temperature field distribution formed by the interaction between the beam and the material is more uniform, so it is more conducive to laser welding and other laser surface treatments. The present invention has the following advantages:

(1) By adding a small hole of a certain size to the center of the total reflection mirror or the output mirror, a hollow Gaussian beam is obtained at the cost of sacrificing a small part of the light intensity of the low-order mode. Under the action of the material, a uniform temperature field distribution is formed, and a beam that is beneficial to material processing is generated at a low cost.

(2) According to the needs of different applications, it can be determined to use a total reflection mirror or an output mirror with a small hole in the center, so as to achieve different spatial light intensity distributions.

(3) According to the needs of different applications, the size of the hole can be reasonably changed to meet the needs of the spatial characteristics of the beam in different applications.

Claims (4)

1. a hollow mirror laserresonator, is characterized in that: in the light path of hollow mirror laserresonator, be followed successively by total reflective mirror, gain medium and flat output mirror; Total reflective mirror or flat output mirror are that center is provided with the fully-reflected plane mirror that diameter is 0.5mm～5mm circular hole, obtain hollow Gaussian beam, by changing center bore size, or change circular hole on total reflective mirror or on outgoing mirror, obtain the hollow Gaussian beam of various ways.

2. hollow mirror laserresonator according to claim 1, it is characterized in that: in the light path of hollow mirror laserresonator, be followed successively by total reflective mirror (1), gain medium (2) and flat output mirror (3), the center of total reflective mirror (1) is provided with the circular hole that diameter is 0.5mm～5mm, the high reflectance flat output mirror of atresia centered by flat output mirror (3).

3. hollow mirror laserresonator according to claim 1, it is characterized in that: in the light path of hollow mirror laserresonator, be followed successively by total reflective mirror (1), gain medium (2) and flat output mirror (3), the center atresia of total reflective mirror (1), flat output mirror (3) is that center is provided with the high reflectance flat output mirror that diameter is the circular hole of 0.5mm～5mm.

4. hollow mirror laserresonator according to claim 1, it is characterized in that: in the light path of hollow mirror laserresonator, be followed successively by total reflective mirror (1), gain medium (2) and flat output mirror (3), total reflective mirror (1) and flat output mirror (3) are that center is equipped with the high reflectance flat output mirror that diameter is the circular hole of 0.5mm～5mm.