A heat sink structure for cooling a rod-shaped laser crystal

Abstract

The utility model discloses a kind of heat sink structures for cooling rod-shaped laser crystal, including outer heat sink and the crystal rod being arranged in the inside of outer heat sink, heat conduction layer and temperature control module, the heat conduction layer is set at the outer periphery of crystal rod and is inlayed with the outer wall of crystal rod, the temperature control module is set in the outside of heat conduction layer and crystal rod is along the axis of temperature control module and penetrates temperature control module, the temperature control module includes multiple temperature control units being arranged along the axial interval of crystal rod.The heat sink structure of the utility model, by multiple temperature control units being arranged along the axial interval of crystal rod, different axial position temperature control unit can be applied different temperature control strategy, the temperature gradient of crystal axial can be accurately controlled, it is favorable to compensate and inhibit thermal lens effect;Combined with the setting of heat conduction layer between temperature control module and crystal rod, heat stress distribution can be effectively improved, and light beam quality is improved.

Description

Technical Field

[0001] This invention belongs to the field of solid-state laser technology, specifically relating to a heat sink structure for cooling rod-shaped laser crystals. Background Technology

[0002] In high-power or high-energy rod-shaped crystal lasers, the heat generated by pump absorption within the crystal leads to a significant temperature gradient, which in turn induces thermal lensing (refractive index changes with temperature) and thermal stress birefringence, severely degrading the laser's output power and beam quality. Traditional monolithic heat sinks struggle to precisely control the temperature distribution along the crystal's axis, limiting thermal management efficiency. Although methods employing composite crystal structures or optimizing heat sink materials (such as diamond) exist, the active and precise control of the crystal's axial temperature field remains insufficient.

[0003] In high-power rod-shaped solid-state lasers, the laser crystal (such as Nd:YAG, Yb:YAG, etc.) generates a large amount of heat when absorbing pump light energy. Due to the limitations of the thermal conductivity of the crystal material and the inhomogeneity of the cooling conditions, a significant temperature gradient forms inside the crystal, leading to the following serious problems: 1) Thermal lensing effect: The crystal's refractive index changes with temperature and deformation caused by thermal stress, making the crystal equivalent to a lens, severely affecting the laser beam quality; 2) Thermally induced birefringence: Thermal stress causes birefringence in the crystal, resulting in changes in polarization state and a decrease in beam quality; 3) Thermal stress fracture: Excessive temperature gradients may cause crystal fracture, shortening the laser's lifespan; 4) Mode instability: Thermal effects cause changes in the laser mode, limiting the output power.

[0004] To address the above issues, traditional thermal management solutions mainly employ integrated water cooling or TEC (thermal energy storage) heat sink structures. However, traditional solutions have the following shortcomings: 1) Passive cooling: unable to provide targeted cooling based on the thermal load at different locations of the crystal; 2) Limited axial temperature control capability: difficult to precisely control the axial temperature distribution of the crystal; 3) Poor adaptability: unable to automatically adjust the cooling strategy according to different operating states of the laser; 4) Limited compensation effect: insufficient ability to compensate for thermal lensing effects.

[0005] Therefore, there is an urgent need to provide a new heat sink structure to solve the above problems. Utility Model Content

[0006] In view of this, in order to overcome the shortcomings of the prior art, the purpose of this utility model is to provide an improved heat sink structure for cooling rod-shaped laser crystals.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A heat sink structure for cooling a rod-shaped laser crystal includes an outer heat sink and a crystal rod, a thermally conductive layer, and a temperature control module disposed inside the outer heat sink. The thermally conductive layer is disposed on the outer periphery of the crystal rod and is in contact with the outer wall of the crystal rod. The temperature control module is sleeved on the outside of the thermally conductive layer and the crystal rod passes through the temperature control module along the axis of the temperature control module. The temperature control module includes a plurality of temperature control units spaced apart along the axial direction of the crystal rod.

[0008] When a laser crystal is operating, the central region of the pump incident end experiences a high thermal load, naturally forming a high-temperature zone that generates a thermal lens. By incorporating a temperature control module, which includes multiple temperature control units spaced along the crystal rod's axis, and independently controlling the temperature of each unit, the temperature gradient along the crystal's axis can be precisely controlled. This allows for appropriate cooling or maintaining a low temperature in the pump incident end region, while reducing cooling intensity or even slightly heating in the middle and rear regions. This helps compensate for and suppress the thermal lensing effect, enabling direct control from the heat source without relying on external optical components, resulting in more precise compensation. It also significantly reduces heat-induced wavefront distortion, improves beam quality, extends stable operating time, and improves thermal stress distribution, reducing the risk of crystal breakage.

[0009] According to some preferred embodiments of the present invention, each temperature control unit includes a heat sink block, the heat sink block having a through hole extending through its length, the center of the through hole coinciding with the center of the heat sink block, the through hole being used for a crystal rod to pass through.

[0010] According to some preferred embodiments of the present invention, each of the heat sink blocks is in the shape of a regular prism.

[0011] According to some preferred embodiments of the present invention, each temperature control unit further includes two cooling plates disposed on at least two sides of the heat sink block. One side of each cooling plate is fixedly connected to one side of the heat sink block, and the other side of each cooling plate is fixedly connected to the inner wall of the outer heat sink. In some embodiments of the present invention, the interior of the outer heat sink is provided with a channel for the flow of cooling water. Since the temperature control module is embedded inside the outer heat sink and the side of each cooling plate away from the heat sink block is in close contact with the inner wall of the outer heat sink, when cooling water is introduced into the channel inside the outer heat sink, excess heat generated by the temperature control module can be carried away.

[0012] According to some preferred embodiments of the present invention, there is a gap between the remaining side of each heat sink block that is not provided with a cooling plate and the inner wall of the corresponding outer heat sink.

[0013] According to some preferred embodiments of the present invention, each of the cooling elements at least completely covers one side of the corresponding heat sink block.

[0014] According to some preferred embodiments of the present invention, the distance between the two heat sinks of two adjacent temperature control units is 0.1-2 mm.

[0015] According to some preferred embodiments of this utility model, a heat-conducting medium may be provided between the two heat sinks of two adjacent temperature control units. The heat-conducting medium connects the two adjacent heat sinks, and its thermal conductivity is 0.5-10 W / mK. In some embodiments of this utility model, no heat-conducting medium or a weakly conductive medium may be provided between two adjacent temperature control units to prevent heat crosstalk.

[0016] According to some preferred embodiments of this invention, the heat-conducting layer is made of indium, and its thickness is less than 1 mm. The heat-conducting layer, acting as a heat-conducting medium, connects the temperature control module and the crystal rod, enhancing heat conduction between them and ensuring precise temperature control of the crystal rod by the temperature control module.

[0017] According to some preferred embodiments of this invention, a temperature control system is also included, with each of the cooling chips connected to the temperature control system, which controls the target temperature of each cooling chip. In some embodiments of this invention, the cooling chip is preferably a TEC (thermal condenser), which has independent power supply and temperature feedback capabilities. Connecting the cooling chips of each temperature control unit to the temperature control system allows for programmed setting of target temperatures for each segment, thereby forming a preset axial temperature gradient. Furthermore, by adjusting the axial temperature gradient, the refractive index distribution and thermal expansion behavior can be changed, thereby generating an equivalent negative lens effect at the back end of the crystal to counteract the original positive thermal lens, thus ensuring that parameters such as beam quality remain consistent throughout the laser amplification process. In addition, through the cooperation between the temperature control system and the temperature control module, dynamic temperature adjustment under multiple power conditions can be supported, making it suitable for variable power laser systems.

[0018] By adopting the above technical solutions, compared with the prior art, the heat sink structure for cooling rod-shaped laser crystals of this utility model can apply differentiated temperature control strategies to the temperature control units at different axial positions by setting multiple temperature control units at intervals along the crystal rod axis. This can accurately control the temperature gradient along the crystal axis, which is beneficial for compensating for and suppressing the thermal lensing effect. Combined with the setting of the heat-conducting layer between the temperature control module and the crystal rod, it can effectively improve the thermal stress distribution and improve the beam quality. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a side view of the heat sink structure in a preferred embodiment of the present invention. Figure 2 This is a side view of the heat sink structure after the external heat sink is hidden in a preferred embodiment of the present invention. Figure 3 This is a schematic diagram of the main structure of the heat sink structure after the external heat sink is hidden in the preferred embodiment of this utility model; Among them, there are crystal rod-1, heat-conducting layer-2, temperature control unit-3, heat sink block-31, cooling chip-32, external heat sink-4, upper heat sink-41, first groove-411, lower heat sink-42, and second groove-421. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0022] Reference Figures 1 to 3 This embodiment provides a heat sink structure for cooling a rod-shaped laser crystal, including an outer heat sink 4, a temperature control system, and a crystal rod 1, a thermally conductive layer 2, and a temperature control module disposed inside the outer heat sink 4. The thermally conductive layer 2 is disposed on the outer periphery of the crystal rod 1 and is in contact with the outer wall of the crystal rod 1. The temperature control module is sleeved on the outside of the thermally conductive layer 2, and the crystal rod 1 passes through the temperature control module along the axis of the temperature control module. The outer heat sink 4 has a channel for the flow of cooling water. By introducing cooling water into the channel inside the outer heat sink 4, excess heat generated by the temperature control module can be removed.

[0023] Furthermore, such as Figure 1 As shown, the external heat sink 4 in this embodiment includes an upper heat sink 41 and a lower heat sink 42. The upper heat sink 41 has a first groove 411 extending through its length from its bottom surface upwards in the middle. The lower heat sink 42 has a second groove 421 extending through its length from its top surface downwards in the middle. Both the first groove 411 and the second groove 421 are parallel to the length of the crystal rod 1 and are centered. When the upper heat sink 41 and the lower heat sink 42 are fixedly connected, a receiving groove is formed between the first groove 411 and the second groove 421 to accommodate the crystal rod 1, the thermally conductive layer 2, and the entire temperature control module, and the receiving groove precisely holds the temperature control module in place.

[0024] Furthermore, such as Figure 3 As shown, the temperature control module includes multiple temperature control units 3 spaced apart along the axial direction of the crystal rod 1. Each temperature control unit 3 includes a heat sink block 31. A through hole extending through the length of the heat sink block 31 is formed inside the heat sink block 31, with the center of the through hole coinciding with the center of the heat sink block 31. The through hole allows the crystal rod 1 to pass through. When the crystal rod 1 with the heat-conducting layer 2 passes through the heat sink block 31, the outer surface of the heat-conducting layer 2 can be tightly attached to the inner wall of the heat sink block 31. In this embodiment, the heat-conducting layer 2 is made of indium metal, and its thickness is less than 1 mm. The heat-conducting layer 2, acting as a heat-conducting medium, connects the temperature control module and the crystal rod 1, enhancing heat conduction between them and ensuring precise temperature control of the crystal rod 1 by the temperature control module.

[0025] Specifically, each heat sink block 31 is shaped like a regular prism; in this embodiment, each heat sink block 31 is shaped like a regular square prism. Each temperature control unit 3 also includes at least two cooling plates 32 disposed on two of the sides of the heat sink block 31. Figure 2 As shown, in this embodiment, a cooling chip 32 is fixedly disposed on each of the four sides of each heat sink block 31. One side of each cooling chip 32 is fixedly connected to one side of the heat sink block 31, and each cooling chip 32 at least completely covers one side of the corresponding heat sink block 31. The other side of each cooling chip 32 is fixedly connected to the inner wall of the outer heat sink 4 to ensure good thermal conductivity. The remaining sides of each heat sink block 31 without cooling chips 32 have gaps with the inner wall of the corresponding outer heat sink 4.

[0026] Furthermore, the spacing between the two heat sink blocks 31 of two adjacent temperature control units 3 is 0.1-2mm. There may be no connecting medium between the two heat sink blocks 31 of two adjacent temperature control units 3, or a thermally conductive medium with low thermal conductivity may be used to prevent heat crosstalk. When a thermally conductive medium is used, it can be used to connect the two adjacent heat sink blocks 31. In this embodiment, the thermal conductivity of the thermally conductive medium is 1W / mK.

[0027] Furthermore, each cooling element 32 in each temperature control unit 3 is connected to the temperature control system. In this embodiment, the cooling element 32 is preferably a TEC (thermal energy storage device), which has independent power supply and temperature feedback capabilities. This allows the temperature control system to control the target temperature of each cooling element 32, thereby supporting programmed setting of each target temperature segment to form a preset axial temperature gradient. By adjusting the axial temperature gradient, the refractive index distribution and thermal expansion behavior can be changed, thereby generating an equivalent negative lens effect at the back end of the crystal to counteract the original positive thermal lens, thus ensuring that parameters such as beam quality remain consistent throughout the laser amplification process. In addition, through the cooperation between the temperature control system and the temperature control module, dynamic temperature adjustment under multiple power conditions can also be supported, making it suitable for variable power laser systems and expanding the application range of the heat sink structure of this invention.

[0028] The above embodiments are only for illustrating the technical concept and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be used to limit the protection scope of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be included within the protection scope of this utility model.

Claims

1. A heat sink structure for cooling rod-shaped laser crystals, characterized in that, The device includes an external heat sink and a crystal rod, a thermally conductive layer, and a temperature control module disposed inside the external heat sink. The thermally conductive layer is disposed on the outer periphery of the crystal rod and is attached to the outer wall of the crystal rod. The temperature control module is sleeved on the outside of the thermally conductive layer and the crystal rod passes through the temperature control module along the axis of the temperature control module. The temperature control module includes multiple temperature control units spaced apart along the axial direction of the crystal rod.

2. The heat sink structure according to claim 1, characterized in that, Each of the temperature control units includes a heat sink block with a through hole extending through its length. The center of the through hole coincides with the center of the heat sink block, and the through hole is used for the crystal rod to pass through.

3. The heat sink structure according to claim 2, characterized in that, Each of the heat sink blocks is in the shape of a regular prism.

4. The heat sink structure according to claim 3, characterized in that, Each of the temperature control units also includes two cooling plates disposed on at least two sides of the heat sink block, one side of each cooling plate being fixedly connected to one side of the heat sink block, and the other side of each cooling plate being fixedly connected to the inner wall of the outer heat sink.

5. The heat sink structure according to claim 4, characterized in that, There is a gap between the remaining side of each heat sink block that is not fitted with a cooling plate and the inner wall of the corresponding outer heat sink.

6. The heat sink structure according to claim 4, characterized in that, Each of the cooling elements at least completely covers one side of the corresponding heat sink block.

7. The heat sink structure according to claim 2, characterized in that, The distance between the two heat sinks of two adjacent temperature control units is 0.1-2 mm.

8. The heat sink structure according to claim 7, characterized in that, A thermally conductive medium may also be provided between the two heat sinks of two adjacent temperature control units. The thermally conductive medium is used to connect the two adjacent heat sinks and has a thermal conductivity of 0.5-10 W / mK.

9. The heat sink structure according to claim 1, characterized in that, The thermal conductive layer is made of indium and has a thickness of less than 1 mm.

10. The heat sink structure according to claim 4, characterized in that, It also includes a temperature control system, with each of the cooling chips connected to the temperature control system, which is used to control the target temperature of each cooling chip.

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