Preparation method of light-gathering cavity with high reflectivity

Abstract

The embodiment of the invention discloses a preparation method of a light-gathering cavity with high reflectivity, and the preparation method comprises the following steps: step 1, preparing a quartz column and a shell, transferring 75-85% of BaSO4, 7-12% of Al2O3, 5-8% of MgO and 3-5% of SiO2 powder in percentage by mass into a ball milling tank, carrying out ball milling by adopting a ball mill, and sieving after ball milling to obtain mixed powder; and 2, filling the mixed powder into a gap between the quartz column and the shell, so that the gap is filled with the mixed powder to form a diffuse reflection layer. The light-gathering cavity has the advantages of being high in reflection efficiency, good in pumping uniformity, simple in structure, convenient to machine and easy to produce in batches.

Description

Technical Field

[0001] The invention relates to the technical field of lasers, and in particular to a method for preparing a focusing cavity with high reflectivity. Background Art

[0002] For lamp-pumped solid-state lasers, the function of the focusing cavity is to maximize the concentration of pump light emitted by the pump lamp onto the laser crystal. The efficiency of the focusing cavity directly affects the overall output performance of the laser.

[0003] Due to the low gain of Er:YAG and the low conversion efficiency of lamp pumping, a large amount of pump energy is deposited in the crystal in the form of heat energy, resulting in a strong thermal effect that will cause problems such as thermally induced birefringence and thermal lens effect, seriously affecting the output power of the laser and the quality of the output spot. The thermally induced birefringence of the laser crystal causes thermal depolarization of the linearly polarized laser. When the linearly polarized light passes through the polarization element, it will produce a huge loss, which directly affects the increase in the output power of the laser and the shape of the spot; and the thermal lens effect of the laser crystal will cause the divergence angle of the output laser to increase, resulting in a decrease in the output power and other problems. With the increase of pump power, these thermal effect problems will become more and more serious, and will eventually directly affect the overall performance of the laser.

[0004] In order to obtain 2.94μm laser output with higher energy and repetition rate, it is mainly achieved by improving the electro-optical conversion efficiency of the focusing cavity, so higher requirements are placed on the design of the focusing cavity. At present, the focusing cavities configured for erbium lasers on the market are mostly ceramic cavities, and there are also glass powder cavities with reflective layers filled with barium sulfate or MgO. Ceramics have the advantages of high temperature resistance and long life, but there is a problem of low pumping efficiency. Glass cavities that also use BaSO4 or MgO powder also have the problem of relatively low efficiency. Summary of the invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a method for preparing a focusing cavity with high reflectivity, so as to improve the conversion efficiency of the focusing cavity and realize high-energy, high-repetition-rate 2.94μm laser output.

[0006] In order to solve the above technical problems, the embodiment of the present invention proposes a method for preparing a focusing cavity with high reflectivity, which includes a quartz column and a shell. The cross section of the quartz column is elliptical. Two mounting holes for assembling a pump lamp and a laser rod are respectively provided in the quartz column. The two mounting holes penetrate the quartz column and the axes of the two mounting holes are parallel. A diffuse reflection layer is filled between the quartz column and the shell. The diffuse reflection layer includes the following components by mass percentage: 75-85% BaSO4, 7-12% Al2O3, 5-8% MgO and 3-5% SiO2; The preparation method comprises: Step 1: by mass percentage, 75-85% BaSO4, 7-12% Al2O3, 5-8% MgO and 3-5% SiO2 powders are transferred into a ball mill, ball milled by a ball mill, and sieved after ball milling to obtain a mixed powder; Step 2: Pour the mixed powder into the gap between the quartz column and the shell, so that the mixed powder fills the gap to form a diffuse reflection layer, thereby obtaining a focusing cavity with high reflectivity.

[0007] The beneficial effects of the present invention are as follows: the focusing cavity of the present invention has the characteristics of high reflection efficiency, good pumping uniformity, simple structure, convenient processing, and easy batch production. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 4 is a cross-sectional view of a focusing cavity with high reflectivity according to an embodiment of the present invention.

[0009] Figure 2 It is a partial cross-sectional view of a focusing cavity with high reflectivity according to an embodiment of the present invention.

[0010] Figure 3 It is a three-dimensional structural diagram of a high-reflectivity focusing cavity at one angle according to an embodiment of the present invention.

[0011] Figure 4 It is a three-dimensional structural diagram of another angle of the high reflectivity focusing cavity of an embodiment of the present invention.

[0012] Description of Figure Numbers Quartz column 1, diffuse reflection layer 2, shell 3, end cover 4, water inlet 5, pump lamp pressing sheet 6, laser rod pressing sheet 7, water outlet 8, mounting hole 9. DETAILED DESCRIPTION

[0013] It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0014] In the embodiments of the present invention, if there are directional indications (such as up, down, left, right, front, back, etc.), they are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0015] In addition, in the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0016] Please refer to Figure 1 to Figure 4 A focusing cavity with high reflectivity according to an embodiment of the present invention includes a quartz column and a housing. The cross section of the quartz column is an ellipse. Two mounting holes for mounting a pump lamp and a laser rod are provided at two foci of the ellipse in the quartz column. That is, the axes of the two mounting holes pass through the two foci of the ellipse. The mounting holes are circular holes. The two mounting holes penetrate the quartz column, and the axes of the mounting holes for mounting the pump lamp and the mounting holes for mounting the laser rod are parallel.

[0017] The quartz column is placed inside the shell, and a diffuse reflection layer is filled between the quartz column and the shell. The reflective material of the diffuse reflection layer includes the following components by mass percentage: 75-85% BaSO4, 7-12% Al2O3, 5-8% MgO and 3-5% SiO2.

[0018] As an implementation manner, the diffuse reflection layer has a thickness of 2 to 4 mm.

[0019] As an implementation mode, both ends of the housing are provided with end caps. The two end surfaces of the cavity body of the high reflectivity focusing cavity of the present invention are fixed and sealed by the end caps.

[0020] As an implementation mode, the end caps at both ends of the housing are provided with a pump lamp pressing piece for installing a pump lamp and a laser rod pressing piece for installing a laser rod. When installing the pump lamp and the laser rod, the two ends of the pump lamp and the laser rod extend out of the cavity of the focusing cavity, and the pump lamp and the laser rod are sealed at the two ends of the cavity with an O-ring and a pump lamp pressing piece and an O-ring and a laser rod pressing piece, respectively, and fixed with screws.

[0021] As an implementation mode, a water inlet and a water outlet are respectively provided on the end covers at both ends of the shell, that is, a water inlet is provided on the end cover at one end, and a water outlet is provided on the end cover at the other end.

[0022] As an implementation manner, the housing is a metal housing, preferably made of hard aluminum or stainless steel.

[0023] The method for preparing a light-focusing cavity with high reflectivity according to an embodiment of the present invention comprises steps 1 and 2.

[0024] Step 1: By mass percentage, place 75-85% BaSO4, 7-12% Al2O3, 5-8% MgO and 3-5% SiO2 powders in a ball mill, and use a ball mill for ball milling. The ball milling time is 30-240 minutes. After the ball milling is completed, pass through a 60-mesh sieve to obtain a mixed powder.

[0025] Step 2: Place the quartz column inside the shell, and form a gap of 2 to 4 mm between the outer wall of the quartz column and the inner wall of the shell; pour the mixed powder into the gap between the quartz column and the shell, so that the mixed powder is evenly and densely filled in the gap to form a diffuse reflection layer, and a focusing cavity with high reflectivity is obtained. In the specific implementation, in order to ensure the sealing performance, a sealing ring can be added between the end cover and the shell to compact it and fix it with screws.

[0026] Principle of the present invention: The reflective layer can evenly converge the pump light radiated by the pump lamp onto the laser rod (diffuse reflection). The main material constituting the reflective layer is barium sulfate powder, which is due to its chemical stability and high reflection efficiency. Adding a certain proportion of aluminum dioxide powder can effectively suppress the parasitic oscillation problem and improve the pumping efficiency. At the same time, a certain proportion of magnesium oxide powder is added, because the reflectivity of magnesium oxide in the 400~700nm band exceeds 95%, and this region is near the effective absorption peak of the Er:YAG crystal, so the reflection efficiency can be further improved. Example

[0027] A method for preparing a light-focusing cavity with high reflectivity, comprising: By mass percentage, 90-95% BaSO4 and 3-10% MgO powders are placed in a ball mill, ball milled by a ball mill, and the ball milling time is 30-240 minutes. After the ball milling is completed, the mixed powder is sieved to obtain a mixed powder. The mixed powder is poured into the gap between the quartz column and the shell, so that the mixed powder is evenly and densely filled in the gap to form a diffuse reflection layer, and a focusing cavity with high reflectivity is obtained.

[0028] The laser rod adopts Er:YAG, with the specification of φ4*90mm, the pump lamp adopts pulse xenon lamp, the output mirror R=90%@2940nm, the reflector R≥99%@2940nm, the pulse energy is 2.5J, the repetition frequency is 5Hz, and the pulse width is 200μs. Example

[0029] According to the mass percentage, 75-85% BaSO4, 7-12% Al2O3, 5-8% MgO and 3-5% SiO2 are placed in a ball mill, and ball milled by a ball mill for 30-240 minutes. After ball milling, the mixed powder is sieved to obtain a mixed powder. The mixed powder is poured into the gap between the quartz column and the shell, so that the mixed powder is evenly and densely filled in the gap to form a diffuse reflection layer, and a focusing cavity with high reflectivity is obtained.

[0030] The laser rod adopts Er:YAG, with a specification of 4*90mm, the pump lamp adopts a pulsed xenon lamp, the output mirror R=90%@2940nm, the reflector R≥99%@2940nm, and the pulse energy is 3J, the repetition frequency is 5Hz, and the pulse width is 200μs.

[0031] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a light-focusing cavity with high reflectivity, characterized in that: The high-reflectivity focusing cavity comprises a quartz column and a shell. The cross section of the quartz column is elliptical. Two mounting holes for mounting a pump lamp and a laser rod are respectively arranged in the quartz column. The two mounting holes penetrate the quartz column and the axes of the two mounting holes are parallel. A diffuse reflection layer is filled between the quartz column and the shell. The diffuse reflection layer comprises the following components by mass percentage: 75-85% BaSO4, 7-12% Al2O3, 5-8% MgO and 3-5% SiO2. The preparation method comprises: Step 1: Prepare a quartz column and a shell, transfer 75-85% BaSO4, 7-12% Al2O3, 5-8% MgO and 3-5% SiO2 powders by mass into a ball mill, use a ball mill to mill, and sieve after the ball milling to obtain a mixed powder; Step 2: Pour the mixed powder into the gap between the quartz column and the shell, so that the mixed powder fills the gap to form a diffuse reflection layer.

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