Double-layer temperature control furnace for laser frequency doubling

Abstract

A double-layer temperature control furnace for laser frequency doubling comprises an inner-layer crystal clamping temperature control assembly, an outer-layer temperature control assembly, a heat insulation layer assembly and a bottom plate. The inner-layer crystal clamping temperature control assembly exerts pretightening force on a nonlinear crystal in the horizontal direction and the vertical direction through a compression spring, meanwhile, flexible clamping of the nonlinear crystal is achieved in a silicone rubber dispensing fixing mode, and temperature signals are collected through a thermistor. And the temperature of the nonlinear crystal is accurately controlled in a manner that the clamping seat is heated by the ceramic heating sheet. The outer layer temperature control assembly achieves closed-loop temperature control of the outer layer through heating of a ceramic heating piece and temperature signal collection of a thermistor. The double-layer temperature control furnace for laser frequency doubling has the characteristics of performing thermal expansion compensation on nonlinear crystals, 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 field of solid laser technology, and particularly to a double-layer temperature-controlled furnace for laser frequency doubling. Background Art

[0002] In the field of optics, frequency doubling is one of the most common nonlinear optical processes. The laser generates second harmonic through a frequency doubling crystal to complete frequency conversion, and the temperature of the frequency doubling crystal has a great influence on its frequency doubling efficiency. The nonlinear optical crystal is affected by the ambient temperature during operation, and at the same time, the crystal will also cause temperature instability due to absorbing part of the laser energy. The change of the crystal temperature will, to a certain extent, destroy the phase matching condition, reducing the nonlinear conversion efficiency and the stability of the output. In order to improve the stability and efficiency of laser nonlinear frequency conversion, generally, the temperature of the frequency doubling crystal is precisely controlled at a certain optimal temperature matching point. The typical control temperature of the second harmonic generation LBO crystal is 150 °C, and usually, the temperature inside the laser cavity is 25 °C. During the process of the LBO crystal rising from the initial normal temperature to the optimal matching temperature, it expands due to heat, and its external dimensions gradually change. If the corresponding clamping device cannot compensate for the change in the external dimensions of the nonlinear crystal, it is very likely to affect the working stability and reliability of the laser.

[0003] At high temperatures, due to the different thermal expansion coefficients of the nonlinear crystal and the laser frequency doubling furnace, it is easy to form thermal stress between the two, affecting the nonlinear frequency conversion efficiency, and in severe cases, it will even cause the nonlinear crystal to rupture. In the field of aerospace lasers, the laser frequency doubling furnace also needs to meet the design requirements of anti-shock and vibration resistance. Therefore, it is necessary to develop a laser frequency doubling furnace for nonlinear crystals with anti-shock and vibration resistance, compensation for high-temperature thermal deformation, and anti-temperature interference.

[0004] Prior Art 1: The invention named "A Nonlinear Crystal Clamping Device and Its Installation Method" with the publication number CN114465077 B discloses that the invention realizes elastic limit on the side, front, and rear surfaces of the nonlinear crystal through springs. The invention realizes elastic limit in two directions, but does not realize limit in the other direction. In aerospace applications, it cannot resist shock and vibration. The invention uses 2 springs in both directions to realize elastic limit, and the 2-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 change. Moreover, the device of the invention does not have a sealing design on the front and rear end faces of the crystal, which is an open cavity. During the heating process of the crystal, the heat radiation leakage from the crystal end face is serious, and there will be a problem of uneven heat distribution of the crystal.

[0005] Prior Art 2: Invention Name: A Temperature Control Device for Laser Nonlinear Crystals, Publication Number: CN205985728U. This invention indirectly laterally clamps through a spring to achieve uniform fixation of the nonlinear crystal under force. This invention uses one spring to clamp the crystal in two directions, and the clamping forces in the two directions are the same. For general nonlinear crystals, the thermal expansion coefficients in the three directions of the crystal are generally different. Therefore, the clamping forces for thermal expansion in different directions should be correspondingly different to avoid the influence of thermal stress on the crystal. However, this invention cannot ensure this situation. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a double-layer temperature control furnace for laser frequency doubling, which can achieve flexible clamping and precise temperature control of the nonlinear crystal, and has the advantages of compensating for high-temperature thermal deformation, resisting impact and vibration, precise temperature control, and strong resistance to external temperature interference.

[0007] The present invention is realized as follows. The double-layer temperature control furnace for laser frequency doubling includes: an inner-layer crystal clamping and temperature control component, an outer-layer temperature control component, a heat insulation layer component, and a bottom plate. Among them, the inner-layer crystal clamping and temperature control component includes: an inner-layer clamping seat, an inner-layer first window mirror retaining ring, an inner-layer first wave spring, an inner-layer first window mirror gasket, an inner-layer first window mirror, an inner-layer first window mirror limiting block, a crystal upper pressing block, a nonlinear crystal, a stud, a nut, a compression spring, an inner-layer second window mirror limiting block, an inner-layer second window mirror, an inner-layer second window mirror gasket, an inner-layer second wave spring, an inner-layer second window mirror retaining ring, a first silicone rubber, an inner-layer lower ceramic heating sheet, an inner-layer lower ceramic heating sheet pressing plate, an inner-layer left ceramic heating sheet pressing plate, an inner-layer left ceramic heating sheet, a second silicone rubber, a crystal side pressing block, an inner-layer first thermistor, and an inner-layer second thermistor. Among them, the outer-layer temperature control component includes: flexible feet, mounting foot heat insulation gaskets, an outer-layer first window mirror retaining ring, an outer-layer first wave spring, an outer-layer first window mirror gasket, an outer-layer first window mirror, an outer-layer temperature control housing, an outer-layer temperature control cover plate, an outer-layer upper ceramic heating cover plate, an outer-layer upper ceramic heating sheet, an outer-layer second window mirror, an outer-layer second window mirror gasket, an outer-layer second wave spring, an outer-layer second window mirror retaining ring, an inner and outer layer heat insulation gasket, an outer-layer lower ceramic heating sheet, an outer-layer lower ceramic heating sheet pressing plate, an outer-layer right ceramic heating sheet cover plate, an outer-layer right ceramic heating sheet, an outer-layer first thermistor, an outer-layer second thermistor, an outer-layer left ceramic heating sheet pressing plate, and an outer-layer left ceramic heating sheet. Among them, the heat insulation layer component includes: a heat insulation layer bottom cover and a heat insulation layer upper cover.

[0008] Preferably, the inner-layer crystal clamping temperature control component, the outer-layer temperature control component, and the heat insulation layer component form a three-level seal for the nonlinear crystal, and the inner-layer crystal clamping temperature control component and the outer-layer temperature control component form a two-layer temperature control for the nonlinear crystal. The inner-layer crystal clamping temperature control component realizes the inner-layer temperature control of the nonlinear crystal, controlling the temperature at 150°C; the outer-layer temperature control component realizes the outer-layer temperature control of the inner-layer component, providing a constant-temperature external environment for the inner-layer component, and the outer-layer temperature control controls the temperature at 100°C.

[0009] Preferably, the left and lower sides of the nonlinear crystal are in contact with the inner clamping seat. The upper and right sides of the nonlinear crystal are fixed by applying a pre-tightening force through compression springs. By turning the position of the nut on the stud, the length of the spring is changed. The other end of the spring contacts the upper crystal pressing block and the side crystal pressing block, and the serrated end faces of the upper and side crystal pressing blocks contact the nonlinear crystal. The left and lower sides of the nonlinear crystal are fixed to the clamping seat by means of dotting glue.

[0010] Preferably, the inner first and second window mirrors are symmetrically distributed on both sides of the nonlinear crystal, and the angle between the window mirror axis and the crystal light-transmitting axis is 3°. The outer first and second window mirrors are also distributed on both sides of the nonlinear crystal, and the angle between the window mirror axis and the crystal light-transmitting axis is 3°.

[0011] Preferably, the inner-layer crystal clamping temperature control component realizes the heating function through 2 ceramic heating sheets and realizes temperature acquisition through 2 thermistors. The outer-layer temperature control component realizes the heating function through 4 ceramic heating sheets and realizes temperature acquisition through 2 thermistors.

[0012] Preferably, the upper crystal pressing block and the side crystal pressing block adopt a "T" configuration design, and the contact surface with the nonlinear crystal adopts a serrated structure design.

[0013] Preferably, the material of the inner clamping seat is copper.

[0014] Preferably, the inner and outer layer window mirrors are fixed by applying a pre-tightening force through the deformation of a corrugated spring.

[0015] Preferably, the nonlinear crystal refers to an LBO optical crystal.

[0016] Preferably, the flexible feet adopt a "Ω" configuration design.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] 1) The double-layer temperature-controlled furnace for laser frequency doubling adopts the method of separately controlling the temperature of the inner and outer layers. The inner layer temperature control provides 150 °C required by the frequency doubling crystal, and the outer layer temperature control provides a constant temperature environment for the inner layer temperature control, controlling the inner layer temperature at about 100 °C. At the same time, the outermost heat insulation layer isolates the interference of external temperature. This three-layer design ensures the stability of crystal temperature control and has the characteristics of strong resistance to external temperature interference.

[0019] 2) The nonlinear crystal is fixed by means of spring flexible clamping and silicone rubber. That is, both sides of the crystal (the left side and the lower side) are positioned on the inner clamping seat and fixed with silicone rubber dots, and the other two sides (the upper side and the right side of the crystal) are fixed by applying a pre-tightening force through a compression spring. During the process of the crystal expanding due to heat, the external dimensions of the crystal will deform, and the deformation of the crystal will exert a reverse force on the spring, causing the spring to deform. Within the deformable range of the spring, the spring undergoes elastic deformation. In this clamping method, the deformation of the spring compensates for the deformation of the crystal, neither generating huge stress on the crystal nor failing to play the role of clamping and fixing. In this way, the glue dots also play a role in resisting impact and vibration, avoiding the influence of impact and vibration on the crystal position. At the same time, two sides of the crystal are in contact with the clamping seat, and when the laser hits the crystal, the heat absorbed by the crystal will be promptly heat-conducted to the inner clamping seat, realizing precise temperature control of the crystal.

[0020] 3) The crystal is installed at the center of the clamping seat, and the clamping seat and the clamping block form a relatively closed cavity for the crystal, which can form a uniform temperature field for the crystal during the heating process of the ceramic heating sheet. The closed cavity is a prerequisite for providing high-precision temperature control for the crystal. The material of the clamping seat is copper, which has higher thermal conductivity.

[0021] 4) The included angle between the axis of the window mirror and the optical axis of the crystal is 3°. When the laser enters from one end of the crystal and exits from the other end, the design of the inclined angle between the axis of the window mirror and the optical axis of the crystal can improve the light transmittance and avoid the influence of partial light reflecting back and forth between the window mirrors on the frequency conversion efficiency.

[0022] 5) The inner layer and the outer layer respectively use ceramic heating sheets to heat the nonlinear crystal and use thermistors to collect temperature. The ceramic heating sheet has the characteristics of high strength, high hardness, low linear expansion coefficient and strong heat resistance.

[0023] 6) The upper pressing block and the side pressing block of the crystal adopt a "T" configuration design, applying a pre-tightening force on the nonlinear crystal through a spring, and a serrated structure design is adopted at the contact surface to increase the friction force and prevent the axial movement of the crystal.

[0024] 7) The window mirror is flexibly fixed by a wave spring, which can also compensate for the dimensional change of the window glass under high-temperature thermal expansion. Description of the Drawings

[0025] Figure 1 It is a front elevation cross-sectional view of a double-layer temperature-controlled furnace for laser frequency doubling in an embodiment of the present invention.

[0026] Figure 2 It is a top plan cross-sectional view of a double-layer temperature-controlled furnace for laser frequency doubling in an embodiment of the present invention.

[0027] Figure 3 It is an orthographic axonometric view of an inner layer crystal clamping temperature control assembly in an embodiment of the present invention.

[0028] Figure 4 It is a side elevation cross-sectional view of an inner layer crystal clamping temperature control assembly in an embodiment of the present invention.

[0029] Figure 5 It is a top plan cross-sectional view of an inner layer crystal clamping temperature control assembly in an embodiment of the present invention.

[0030] Figure 6 It is a front elevation cross-sectional view of an inner layer crystal clamping temperature control assembly in an embodiment of the present invention.

[0031] Figure 7 It is an orthographic axonometric view of an outer layer temperature control assembly in an embodiment of the present invention.

[0032] Figure 8 It is a side elevation cross-sectional view of an outer layer temperature control assembly in an embodiment of the present invention.

[0033] Figure 9 It is a top plan cross-sectional view of an outer layer temperature control assembly in an embodiment of the present invention.

[0034] Figure 10 It is an orthographic axonometric view of a heat insulation layer assembly in an embodiment of the present invention.

[0035] Figure 11 It is a schematic view of a flexible foot structure in an embodiment of the present invention.

[0036] Figure 12 It is a schematic view of a crystal upper pressing block structure in an embodiment of the present invention.

[0037] Numbers in the figure: 1. Inner layer crystal clamping temperature control component; 2. Outer layer temperature control component; 3. Heat insulation layer component; 4. Bottom plate; 1-1. Inner layer clamping seat; 1-2. Inner layer first window mirror retaining ring; 1-3. Inner layer first wave spring; 1-4. Inner layer first window mirror gasket; 1-5. Inner layer first window mirror; 1-6. Inner layer first window mirror limiting block; 1-7. Crystal upper pressing block; 1-8. Nonlinear crystal; 1-9. Stud; 1-10. Nut; 1-11. Compression spring; 1-12. Inner layer second window mirror limiting block; 1-13. Inner layer second window mirror; 1-14. Inner layer second window mirror gasket; 1-15. Inner layer second wave spring; 1-16. Inner layer second window mirror retaining ring; 1-17. First silicone rubber; 1-18. Inner layer lower ceramic heating sheet; 1-19. Inner layer lower ceramic heating sheet pressing plate; 1-20 Inner layer left ceramic heating sheet pressing plate; 1-21. Inner layer left ceramic heating sheet; 1-22. Inner layer second silicone rubber; 1-23. Crystal side pressing block; 1-24. Inner layer first thermistor; 1-25. Inner layer second thermistor; 2-1. Flexible foot; 2-2. Mounting foot heat insulation gasket; 2-3. Outer layer first window mirror retaining ring; 2-4. Outer layer first wave spring; 2-5. Outer layer first window mirror gasket; 2-6. Outer layer first window mirror; 2-7. Outer layer temperature control housing; 2-8. Outer layer temperature control cover plate; 2-9. Outer layer upper ceramic heating cover plate; 2-10. Outer layer upper ceramic heating sheet; 2-11. Outer layer second window mirror; 2-12. Outer layer second window mirror gasket; 2-13. Outer layer second wave spring; 2-14. Outer layer second window mirror retaining ring; 2-15. Inner and outer layer heat insulation gasket; 2-16. Outer layer lower ceramic heating sheet; 2-17. Outer layer lower ceramic heating sheet pressing plate; 2-18. Outer layer right ceramic heating sheet cover plate; 2-19. Outer layer right ceramic heating sheet; 2-20. Outer layer first thermistor; 2-21. Outer layer second thermistor; 2-22. Outer layer left ceramic heating sheet pressing plate; 2-23. Outer layer left ceramic heating sheet; 3-1. Heat insulation layer bottom cover; 3-2. Heat insulation layer upper cover. Detailed implementation manners

[0038] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] The technical solutions of the present invention will be further described in detail below in conjunction with the drawings and embodiments.

[0040] As Figure 1 、 Figure 2 shown, the present invention provides a double-layer temperature control furnace for laser frequency doubling, including an inner layer crystal clamping temperature control component 1, an outer layer temperature control component 2, a heat insulation layer component 3, and a bottom plate 4.

[0041] As Figure 3 , Figure 4 , Figure 5 shown, the present invention provides an inner layer crystal clamping temperature control component in a double-layer temperature-controlled furnace for laser frequency doubling, including an inner layer clamping seat 1-1, an inner layer first window mirror retaining ring 1-2, an inner layer first wave spring 1-3, an inner layer first window mirror gasket 1-4, an inner layer first window mirror 1-5, an inner layer first window mirror stop block 1-6, a crystal upper pressing block 1-7, a nonlinear crystal 1-8, a stud 1-9, a nut 1-10, a compression spring 1-11, an inner layer second window mirror stop block 1-12, an inner layer second window mirror 1-13, an inner layer second window mirror gasket 1-14, an inner layer second wave spring 1-15, an inner layer second window mirror retaining ring 1-16, a first silicone rubber 1-17, an inner layer lower ceramic heating sheet 1-18, an inner layer lower ceramic heating sheet pressing plate 1-19, an inner layer left ceramic heating sheet pressing plate 1-20, an inner layer left ceramic heating sheet 1-21, an inner layer second silicone rubber 1-22, a crystal side pressing block 1-23, an inner layer first thermistor 1-24, and an inner layer second thermistor 1-25.

[0042] The schematic diagram of the flexible clamping structure of the nonlinear crystal 1-8 is as Figure 6 shown. The left side surface of the crystal contacts the inner layer clamping seat 1-1, and the right side surface of the crystal contacts the serrated plane of the crystal side pressing block 1-23. The crystal side pressing block 1-23 is pressed on 4 compression springs 4 by applying a pre-tightening force through 4 nuts. The compressed spring applies spring elastic force to the crystal side pressing block 1-23, thereby realizing the flexible clamping of the crystal in the horizontal direction. Similarly, in the vertical direction, the lower side surface of the crystal contacts the inner layer clamping seat 1-1, and the upper side surface of the crystal contacts the serrated plane of the crystal upper pressing block 1-7. The crystal upper pressing block 1-7 is pressed on 4 compression springs 4 by applying a pre-tightening force through 4 nuts. The compressed spring applies spring elastic force to the crystal upper pressing block 1-7, thereby realizing the flexible clamping of the crystal in the vertical direction. And a glue dispensing hole design is provided at the contact surface between the inner layer clamping seat 1-1 and the nonlinear crystal 1-8, and silicone rubber is applied at 2 places respectively. Because silicone rubber has certain elasticity, it is also a flexible connection. The glue dispensing design can ensure the complete positioning of the crystal position and also has an anti-impact mechanical design, meeting the aerospace-level design requirements.

[0043] The schematic diagram of the installation of the inner layer ceramic heating sheet and the inner layer thermistor is as Figure 6As shown in the figure, the inner lower ceramic heating sheet 1-18 and the inner left ceramic heating sheet 1-21 are respectively fixed on the inner clamping seat 1-1 through screws, the inner lower ceramic heating sheet pressing plate 1-19, and the inner left ceramic heating sheet pressing plate 1-20. The inner first thermistor 1-24 and the inner second thermistor 1-25 are fixed on the inner clamping seat 1-1 by dispensing. The ceramic heating sheet is powered on through the temperature control circuit to heat the inner clamping seat 1-1. The thermistors 1-24 and 1-25 monitor the temperature of the inner 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.

[0044] The installation schematic diagram of the crystal upper pressing block 1-7 and the crystal side pressing block 1-23 is as Figure 6 shown. The stud 1-9 is screwed onto the inner clamping seat 1-1. The serrated design surfaces of the crystal upper pressing block 1-7 and the crystal side pressing block 1-23 are in contact with the crystal. The compression spring 1-11 is between the nut 1-10 and the crystal upper pressing block 1-7 and the crystal side pressing block 1-23. By adjusting the position of the adjusting nut 1-10 on the stud 1-9, the compression amount of the compression spring 1-11 can be adjusted, and thus the pre-tightening force of the crystal clamping can be adjusted.

[0045] As Figure 7 , Figure 8 , Figure 9 shown, the present invention provides an outer layer temperature control component in a double-layer temperature control furnace for laser frequency doubling, including flexible feet 2-1, mounting foot heat insulation gaskets 2-2, outer layer first window mirror retaining rings 2-3, outer layer first wave springs 2-4, outer layer first window mirror gaskets 2-5, outer layer first window mirrors 2-6, outer layer temperature control housings 2-7, outer layer temperature control cover plates 2-8, outer layer upper ceramic heating cover plates 2-9, outer layer upper ceramic heating sheets 2-10, outer layer second window mirrors 2-11, outer layer second window mirror gaskets 2-12, outer layer second wave springs 2-13, outer layer second window mirror retaining rings 2-14, inner and outer layer heat insulation gaskets 2-15, outer layer lower ceramic heating sheets 2-16, outer layer lower ceramic heating sheet pressing plates 2-17, outer layer right ceramic heating cover plates 2-18, outer layer right ceramic heating sheets 2-19, outer layer first thermistors 2-20, outer layer second thermistors 2-21, outer layer left ceramic heating sheet pressing plates 2-22, and outer layer left ceramic heating sheets 2-23. Among them, 4 outer layer ceramic heating sheets are respectively fixed on the outer layer temperature control housing 2-7 and the outer layer temperature control cover plate 2-8 through 4 ceramic heating sheet cover plates. The outer layer first thermistor 2-20 and the outer layer second thermistor 2-21 are respectively fixed on the outer layer temperature control housing 2-7 by dispensing. The ceramic heating sheet is powered on through the temperature control circuit to heat the outer layer temperature control housing 2-7. The thermistors 2-20 and 2-21 monitor the temperature of the outer layer temperature control housing 2-7 in real time. When the temperature reaches the outer layer set temperature, the temperature control circuit is powered off to achieve closed-loop temperature control.

[0046] The structural schematic of the heat insulation layer assembly 3 is as shown in Figure 10 shown. The "Ω" - shaped design of the flexible feet 2 - 1 is as shown in Figure 11 shown. The schematic of the "T" configuration and serrated design of the crystal side pressing block 1 - 23 is as shown in Figure 12 shown.

[0047] The working process of the double - layer temperature - controlled furnace for laser frequency doubling provided by the present invention is as follows:

[0048] In the double - layer temperature - controlled furnace for laser frequency doubling of the present invention, it is installed in the laser cavity. When the non - linear crystal LBO needs to perform frequency conversion on the incident light, the laser system needs to precisely control the temperature of the non - linear crystal at 150 °C. At the same time, in order to ensure that the temperature of the crystal remains stable during the working process, an external stable temperature - controlled environment needs to be provided for the inner - layer crystal clamping temperature - control component, that is, the temperature of the outer - layer temperature - control component needs to be controlled at 100 °C. The system controller issues a target temperature command (the inner - layer temperature is controlled at 150 °C, and the outer - layer temperature is controlled at 100 °C) to the external temperature - control circuit. After receiving the command, the temperature - control circuit supplies power to the inner - layer and outer - layer ceramic heating elements respectively. The ceramic heating elements work to heat the inner - layer clamping seat and the outer - layer temperature - control housing. At the same time, the thermistor real - time feeds back the inner - layer and outer - layer temperature signals to the temperature - control circuit. When the temperature T1 collected by the inner - layer thermistor is less than 150 °C, the ceramic heating element continues to work to heat the clamping seat. When T1 > 150 °C, the external temperature - control circuit is cut off to achieve closed - loop switch control. Similarly, when the temperature T2 collected by the outer - layer thermistor is less than 100 °C, the ceramic heating element continues to work to heat the outer - layer temperature - control housing. When T2 > 100 °C, the external temperature - control circuit is cut off to achieve closed - loop switch control. During the process of the LBO crystal heating up, due to the characteristics of the material itself, the thermal expansion of the crystal in three directions is different, and the external dimensions will deform. For the inner - layer clamping device, the inner - layer clamping device needs to compensate for the changes of the non - linear crystal. In the present invention, a spring design is adopted to achieve this, that is, the deformation of the spring is used to compensate for the change in the size of the non - linear crystal. The outer - layer temperature - control component needs to be controlled at 100 °C during the working process. For the two mounting surfaces of the flexible feet, there is a temperature difference of 80 °C. The flexible feet need to overcome the thermal stress caused by thermal deformation. That is, in the present invention, a "Ω" configuration design is adopted for the flexible feet to achieve this.

[0049] The above - mentioned are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A double-layer temperature-controlled furnace for laser frequency doubling, characterized in that, Comprising: An inner-layer crystal clamping temperature control component (1) for flexibly clamping and controlling the temperature of a nonlinear crystal (1-8); An outer-layer temperature control component (2) surrounding the inner-layer crystal clamping temperature control component (1) to provide a constant temperature environment for it; A heat insulation layer component (3) covering the outer-layer temperature control component (2) for isolating external temperature interference; A bottom plate (4) for fixing the outer-layer temperature control component (2) and the heat insulation layer component (3); Wherein, the inner-layer crystal clamping temperature control component (1) is installed in the cavity of the outer-layer temperature control component (2) through inner and outer-layer heat insulation gaskets (2-15) to form a three-layer nested structure.

2. The double-layer temperature-controlled furnace for laser frequency doubling according to claim 1, wherein, The inner-layer crystal clamping temperature control component (1) includes: An inner-layer clamping seat (1-1) made of copper material; At least four compression springs (1-11) applying pre-tightening forces in the horizontal and vertical directions respectively; An inner-layer lower ceramic heating sheet (1-18) and an inner-layer left ceramic heating sheet (1-21) symmetrically arranged on both sides of the clamping seat; An inner-layer first thermistor (1-24) and an inner-layer second thermistor (1-25) symmetrically arranged on both sides of the inner-layer clamping seat (1-1) for inner-layer temperature acquisition.

3. The double-layer temperature-controlled furnace for laser frequency doubling according to claim 1, wherein, The outer-layer temperature control component (2) includes: A closed temperature control housing (2-7) and a temperature control cover plate (2-8) forming a sealed cavity; An outer-layer upper ceramic heating sheet (2-10), an outer-layer lower ceramic heating sheet (2-16), an outer-layer right ceramic heating sheet (2-19), and an outer-layer left ceramic heating sheet (2-23) respectively arranged on the upper, lower, left, and right surfaces of the closed temperature control housing (2-7); An outer-layer first thermistor (2-20) and an outer-layer second thermistor (2-21) symmetrically arranged on both sides of the closed temperature control housing (2-7) for outer-layer temperature monitoring; Flexible feet (2-1) designed in a Ω-shaped structure, symmetrically distributed around the outer-layer temperature control housing (2-7) and installed through heat insulation gaskets (2-2).

4. The double-layer temperature-controlled furnace for laser frequency doubling according to claim 1, wherein, The heat insulation layer component (3) includes: A heat insulation layer bottom cover (3-1) fixedly connected to the bottom plate (4); A heat insulation layer upper cover (3-2) detachably installed.

5. The double-layer temperature-controlled furnace for laser frequency doubling according to claim 1, characterized in that, The left and lower side surfaces of the nonlinear crystal (1-8) are in contact with the inner-layer clamping seat (1-1), and the upper and right side surfaces of the nonlinear crystal (1-8) are fixed by the compression of the compression springs (1-11) applying pre-tightening forces. By turning the position of the nut (1-10) on the stud (1-9), the length of the spring is changed, and the other end of the spring contacts the crystal upper pressing block (1-7) and the crystal side pressing block (1-23). The serrated end faces of the upper and side pressing blocks of the crystal contact the nonlinear crystal.

6. The double-layer temperature-controlled furnace for laser frequency doubling according to claim 1, wherein The included angle between the window mirror axis and the crystal light passing axis is 3°.

7. The double-layer temperature-controlled furnace for laser frequency doubling according to claim 1, characterized in that The inner and outer-layer window mirrors (1-5, 1-13, 2-6, 2-11) are fixed by the deformation of the waveform springs (1-3, 1-15, 2-4, 2-13) applying pre-tightening forces.

8. The double-layer temperature-controlled furnace for laser frequency doubling according to any one of claims 1-7, characterized in that It further includes a temperature control system, and this control system: Adopts a PID control algorithm; Has a dual temperature protection function; The temperature control accuracy reaches ±0.1 °C; Can realize independent control of the inner-layer and outer-layer temperatures.

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