Nonlinear crystal flexible clamping and temperature control device and method

Abstract

A nonlinear crystal flexible clamping and temperature control device comprises a clamping seat, a top face clamping block, a side face clamping block, a stud, a compression spring, a nut, a window mirror pressing ring, a wave spring, a window mirror gasket, a window mirror, a window mirror limiting block, a nonlinear crystal, silicon rubber, a thermistor and a ceramic heating piece. The flexible clamping device exerts pre-tightening force on the nonlinear crystal in the horizontal direction and the vertical direction through the compression spring, and meanwhile flexible clamping of the nonlinear crystal is achieved in a silicone rubber dispensing fixing mode. The temperature control device achieves accurate control over the temperature of the nonlinear crystal in the mode that a thermistor collects temperature signals and a ceramic heating piece heats a clamping base. The flexible clamping and temperature control device disclosed by the invention has the characteristics of performing thermal expansion compensation on the nonlinear crystal, being high in mechanical resistance and temperature control precision, uniform in crystal heat distribution and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of laser nonlinear frequency conversion, and in particular to a nonlinear crystal flexible clamping and temperature control device and method. Background Art

[0002] Laser nonlinear frequency conversion systems utilize the nonlinear optical effect to convert laser light from one frequency to another. They typically consist of a nonlinear crystal, a temperature control device, and a temperature control circuit. To improve the stability and efficiency of laser nonlinear frequency conversion, the temperature of the nonlinear crystal is typically precisely controlled at an optimal temperature matching point. For example, the typical control temperature for a doubled-frequency LBO crystal is 150°C, and for a tripled-frequency LBO crystal is 60°C. However, the laser cavity temperature is typically 25°C. As the nonlinear crystal heats up from its initial room temperature to the optimal matching temperature, it expands and its dimensions gradually change. If the corresponding clamping device cannot compensate for this dimensional change, the laser's operational stability and reliability may be affected. At high temperatures, the different thermal expansion coefficients of the nonlinear crystal and the clamping device can easily cause thermal stress to form between them, affecting the efficiency of nonlinear frequency conversion and, in severe cases, causing the nonlinear crystal to fracture. In the field of aerospace lasers, the clamping device must also be designed to withstand shock and vibration. Therefore, flexible clamping devices that are designed to withstand shock and vibration and compensate for thermal deformation at high temperatures are essential for nonlinear crystals.

[0003] Prior art 1: Invention name: A nonlinear crystal clamping device and its installation method, Publication number: CN114465077 B discloses that the invention uses springs to achieve elastic limiting on the sides and front and back faces of the nonlinear crystal. The invention achieves elastic limiting in two directions, but does not achieve limiting in the other direction. In aerospace-grade applications, it cannot resist impact vibration. The invention uses two springs in both directions to achieve elastic limiting. The two-point support has the problem of uneven clamping force on the crystal, and cannot stably compensate for the problem of excessive thermal stress caused by temperature changes. In addition, the device of the invention does not have a sealing design on the front and back faces of the crystal. It is an open cavity. During the heating process of the crystal, the end face of the crystal will suffer from severe heat radiation leakage, which will cause uneven heat distribution in the crystal.

[0004] Prior Art 2: Invention Title: A Laser Nonlinear Crystal Temperature Control Device, Publication Number: CN205985728U. This invention utilizes indirect lateral spring clamping to achieve uniform force fixation of nonlinear crystals. This invention uses a single spring to clamp the crystal in two directions, with the clamping force being equal in both directions. However, for typical nonlinear crystals, the thermal expansion coefficients in the three directions generally differ, so the clamping force required to address thermal expansion in different directions must also be different to avoid thermal stress on the crystal. This invention cannot guarantee this. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the present invention provides a nonlinear crystal flexible clamping and temperature control device, which can achieve flexible clamping and precise temperature control of nonlinear crystals, and has the advantages of compensating for high temperature thermal deformation, resisting impact vibration, and precise temperature control.

[0006] The present invention is implemented as follows: a nonlinear crystal flexible clamping and temperature control device includes: a clamping seat, a top clamping block, a stud, a compression spring, a nut, a side clamping block, a first window mirror pressure ring, a bottom ceramic heating plate, a bottom ceramic heating plate pressure plate, a screw, a side ceramic heating plate pressure plate, a side ceramic heating plate, a first wave spring, a first window mirror gasket, a first window mirror, a first window mirror limit block, a nonlinear crystal, a second window mirror limit block, a second window mirror, a second window mirror gasket, a second wave spring, a second window mirror pressure ring, a bottom silicone rubber, a side silicone rubber, a first thermistor, and a second thermistor.

[0007] Preferably, the top surface and the second side surface of the nonlinear crystal are fixed by applying a pre-tightening force by means of a compression spring, and the length of the spring is changed by turning the position of the nut on the stud. The other end of the spring contacts the top surface and the side clamping block, and the serrated end faces of the top surface and the side clamping block contact the nonlinear crystal.

[0008] Preferably, the clamping seat, the window mirror, the clamping block, and the ceramic heating plate form a relatively closed cavity, and the nonlinear crystal is installed in the middle of the cavity.

[0009] Preferably, the first window mirror and the second window mirror are symmetrically distributed on both sides of the nonlinear crystal, and the angle between the axis of the window mirror and the light transmission axis of the crystal is 3°.

[0010] Preferably, the first side surface and the bottom surface of the nonlinear crystal are fixed on the clamping seat by dispensing glue.

[0011] Preferably, the temperature control device heats the clamping seat through two ceramic heating plates and collects temperature through a thermistor.

[0012] Preferably, the top clamping block and the side clamping block are designed in a "T" configuration, and the contact surface with the nonlinear crystal is designed in a serrated structure.

[0013] Preferably, the window mirror is flexibly fixed by compressing a wave spring.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1) The nonlinear crystal is fixed using a flexible spring clamping and silicone rubber method. Two sides of the crystal (the first side and bottom) are positioned on the clamping seat and fixed with silicone rubber. The other two sides (the top and second side) are fixed with a preload applied by a compression spring. As the crystal expands due to heat, its external dimensions deform. This deformation exerts a reverse force on the spring, causing it to deform. Within its deformable range, the spring undergoes elastic deformation. In this clamping method, the spring deformation compensates for the crystal deformation, neither exerting significant stress on the crystal nor providing a clamping and fixing effect. In this method, the glue also acts to resist shock and vibration, preventing the impact of shock and vibration on the crystal's position. At the same time, the two sides of the crystal are in contact with the clamping seat. When the laser strikes the crystal, the heat absorbed by the crystal is promptly transferred to the clamping seat, enabling the device to achieve precise temperature control of the crystal.

[0016] 2) The crystal is mounted in the center of the holder. The holder and the clamping block form a relatively closed cavity around the crystal, creating a uniform temperature field for the crystal during heating by the ceramic heater. This closed cavity is the prerequisite for high-precision temperature control of the crystal. The holder is made of copper, which has higher thermal conductivity.

[0017] 3) The angle between the axis of the window mirror and the optical axis of the crystal is 3°. When the laser enters one end of the crystal and exits from the other end, the axis of the window mirror and the optical axis of the crystal have an oblique angle design, which can improve the transmittance of light and avoid part of the light reflecting back and forth between the window mirrors and affecting the frequency conversion efficiency.

[0018] 4) The temperature control device heats the clamping base through two ceramic heating plates, and the temperature is collected through thermistors. The ceramic heating plates have the characteristics of high strength, high hardness, low linear expansion coefficient and strong heat resistance.

[0019] 5) The top clamping block and the side clamping block adopt a "T" configuration design, and a preload is applied to the nonlinear crystal through a spring. The contact surface adopts a serrated structure design to increase friction and prevent axial movement of the crystal.

[0020] 6) The window mirror adopts a wave spring to achieve flexible fixation, which can also compensate for the dimensional changes of the window glass under high temperature thermal expansion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is an isometric view of a nonlinear crystal flexible clamping and temperature control device according to an embodiment of the present invention.

[0022] Figure 2 This is a front view of a nonlinear crystal flexible clamping and temperature control device in an embodiment of the present invention.

[0023] Figure 3 It is a side sectional view of a nonlinear crystal flexible clamping and temperature control device in an embodiment of the present invention.

[0024] Figure 4 It is a front cross-sectional view of a nonlinear crystal flexible clamping and temperature control device in an embodiment of the present invention.

[0025] Figure 5 This is a rear view of a nonlinear crystal flexible clamping and temperature control device in an embodiment of the present invention.

[0026] Figure 6 It is a front cross-sectional view of a nonlinear crystal flexible clamping and temperature control device in an embodiment of the present invention.

[0027] Figure 7 It is a top cross-sectional view of a nonlinear crystal flexible clamping and temperature control device in an embodiment of the present invention.

[0028] Figure 8 Schematic diagram of the top surface clamping block structure in an embodiment of the present invention.

[0029] Numbers in the figure: 1-clamping seat; 2-top clamping block; 3-stud; 4-compression spring; 5-nut; 6-side clamping block; 7-first window mirror pressure ring; 8-bottom ceramic heating plate; 9-bottom ceramic heating plate pressure plate; 10-screw; 11-side ceramic heating plate pressure plate; 12-side ceramic heating plate; 13-first wave spring; 14-first window mirror gasket; 15-first window mirror; 16-first window mirror limit block; 17-nonlinear crystal; 18-second window mirror limit block; 19-second window mirror; 20-second window mirror gasket; 21-second wave spring; 22-second window mirror pressure ring; 23-bottom silicone rubber; 24-side silicone rubber; 25-first thermistor; 26-second thermistor. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0032] like Figure 1 、 Figure 2 、 Figure 3 As shown, the present invention provides a nonlinear crystal flexible clamping and temperature control device, including a clamping seat 1; a top clamping block 2; a stud 3; a compression spring 4; a nut 5; a side clamping block 6; a first window mirror pressure ring 7; a bottom ceramic heating plate 8; a bottom ceramic heating plate pressure plate 9; a screw 10; a side ceramic heating plate pressure plate 11; a side ceramic heating plate 12; a first wave spring 13; a first window mirror gasket 14; a first window mirror 15; a first window mirror limit block 16; a nonlinear crystal 17; a second window mirror limit block 18; a second window mirror 19; a second window mirror gasket 20; a second wave spring 21; a second window mirror pressure ring 22; a bottom silicone rubber 23; a side silicone rubber 24; a first thermistor 25; and a second thermistor 26.

[0033] The flexible clamping structure of the nonlinear crystal 17 is shown in FIG. Figure 4 As shown, the first side of the crystal contacts the clamping seat 1, and the second side of the crystal contacts the serrated surface of the side clamping block 6. The side clamping block 6 applies a preload force to four compression springs 4 through four nuts. The compressed springs apply a spring force to the side clamping block 6, thereby achieving flexible clamping of the crystal in the horizontal direction. Similarly, in the vertical direction, the bottom surface of the crystal contacts the clamping seat 1, and the top surface of the crystal contacts the serrated surface of the top clamping block 2. The top clamping block 2 applies a preload force to four compression springs 4 through four nuts. The compressed springs apply a spring force to the top clamping block 2, thereby achieving flexible clamping of the crystal in the vertical direction. In addition, a glue-pointing hole design is reserved at the contact surface between the clamping seat 1 and the nonlinear crystal 17. Silicone rubber is applied at two locations. Because silicone rubber has a certain elasticity, it is also a flexible connection. The glue-pointing design can ensure the complete positioning of the crystal position and also has a shock-resistant mechanical design that meets aerospace-grade design requirements.

[0034] The installation diagram of ceramic heater and thermistor is as follows Figure 5 As shown, the bottom ceramic heating plate 8 and the side ceramic heating plate 12 are fixed to the clamping seat 1 by screws, the bottom ceramic heating plate pressing plate 9, and the side ceramic heating plate pressing plate 11 respectively. The first thermistor 25 and the second thermistor 26 are fixed to the clamping seat by glue. The ceramic heating plate is powered on by the temperature control circuit to heat the clamping seat 1. The thermistors 25 and 26 monitor the temperature of the clamping seat in real time. When the temperature reaches the temperature required by the nonlinear crystal, the temperature control circuit is powered off to achieve closed-loop temperature control.

[0035] The installation diagram of the top clamping block 2 and the side clamping block 6 is as follows: Figure 6 、 Figure 7As shown, the stud 3 is screwed onto the clamping seat 1, the serrated design surfaces of the top clamping block 2 and the side clamping block 6 contact the crystal, and the compression spring 4 is between the nut 5 and the top clamping block 2. By adjusting the position of the nut 5 on the stud 3, the compression amount of the compression spring 4 can be adjusted, and then the preload force of the crystal clamping can be adjusted.

[0036] The "T" configuration and serrated design of the top surface clamping block 2 are shown as follows: Figure 8 shown.

[0037] The flexible clamping and temperature control device for nonlinear crystals provided by the present invention operates as follows: The flexible clamping and temperature control device for nonlinear crystals is installed in a laser cavity. When the nonlinear crystal is required to frequency-convert incident light, the laser system needs to precisely control the temperature of the nonlinear crystal at an optimal temperature point, T°C. A system controller issues a target temperature command (controlling the temperature at T°C) to an external temperature control circuit. Upon receiving the command, the temperature control circuit powers a ceramic heater, which operates to heat the clamping base. Simultaneously, a thermistor provides real-time temperature feedback to the temperature control circuit. When the thermistor detects a temperature T<T, the ceramic heater continues to operate, heating the clamping base. When T>T, the external temperature control circuit shuts off, achieving closed-loop on-off control. If external interference causes temperature fluctuations in the temperature control device, the closed-loop temperature control circuit also performs closed-loop temperature control on the device, maintaining the nonlinear crystal temperature at the optimal point. When the temperature of a nonlinear crystal rises, due to the characteristics of the material itself, the thermal expansion of the crystal in three directions is different, and the external dimensions will be deformed. For the clamping device, the flexible clamping device needs to compensate for the changes of the nonlinear crystal. The spring design used in the present invention is achieved, that is, the change in the size of the nonlinear crystal is compensated by the deformation of the spring.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A nonlinear crystal flexible clamping and temperature control device, characterized in that: include: Clamping base (1) for supporting and positioning the nonlinear crystal (17) The top surface clamping block (2) and the side surface clamping block (6) respectively apply a flexible pre-tightening force to the top surface and the second side surface of the nonlinear crystal (17) through the compression spring (4) and the stud (3); The bottom surface silicone rubber (23) and the side surface silicone rubber (24) are respectively used to flexibly fix the bottom surface and the first side surface of the nonlinear crystal (17) by dispensing glue; The first window mirror (15) and the second window mirror (19) are symmetrically distributed on both sides of the nonlinear crystal (17) and are flexibly fixed by wave springs (13, 21) and window mirror pressure rings (7, 22); A bottom ceramic heating plate (8) and a side ceramic heating plate (12) for heating the clamping seat (1); The first thermistor (25) and the second thermistor (26) are used to monitor the temperature in real time and feed back the temperature to the temperature control circuit.

2. The nonlinear crystal flexible clamping and temperature control device according to claim 1, characterized in that: The clamping seat (1), the first window mirror (15), the second window mirror (19), the top clamping block (2), the side clamping block (6), the bottom ceramic heating plate (8) and the side ceramic heating plate (12) together form a closed cavity, and the nonlinear crystal (17) is located at the center of the cavity.

3. The nonlinear crystal flexible clamping and temperature control device according to claim 1, characterized in that: The top surface clamping block (2) and the side surface clamping block (6) are designed in a "T"-shaped structure, and the contact surfaces with the nonlinear crystal (17) are provided with a serrated texture.

4. The nonlinear crystal flexible clamping and temperature control device according to claim 3, characterized in that: The saw teeth have a spacing of 0.5-1 mm and a depth of 0.2-0.5 mm.

5. The nonlinear crystal flexible clamping and temperature control device according to claim 1, characterized in that: The axes of the first window mirror (15) and the second window mirror (19) form an angle of 3° with the light transmission axis of the nonlinear crystal (17).

6. A temperature control method for the device according to any one of claims 1 to 5, characterized in that: The following steps are involved: Real-time temperature monitoring via a first thermistor (25) and a second thermistor (26); When the temperature is lower than the set value, the bottom ceramic heating plate (8) and the side ceramic heating plate (12) are started to heat; When the temperature reaches the set value, stop heating; PID algorithm is used for closed-loop control to keep the temperature stable.

7. A method for adjusting the clamping force of the device according to any one of claims 1 to 5, characterized in that: The following steps are involved: The preload force of the compression spring (4) is adjusted by rotating the nut (5); Use a torque wrench to control the tightening torque to 0.5-1N·m; The compression amount of the compression spring (4) is detected to be no more than 1.5 mm.

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