Active thermal control system for optical elements

Abstract

The present application relates to the technical field of optical control, and especially relates to an optical element active thermal control system, two cooling plates are respectively arranged on two sides of the optical element; cooling medium flows in the cooling plates, is used for cooling the optical element, and the flowing direction of the cooling medium in the two cooling plates is opposite; a temperature sensor is used for measuring the measured temperature of the optical element; a piezoelectric micro valve is connected with the two cooling plates, and is used for controlling the flow of the cooling medium in the two cooling plates; a pressure sensor is arranged at two ends of the piezoelectric micro valve, and is used for sensing the pressure difference at the two ends of the piezoelectric micro valve; and a control unit controls the piezoelectric micro valve to adjust the flow of the cooling medium in the two cooling plates according to the measured temperature and the pressure difference. The present application adopts micro-channel reinforced heat transfer and symmetrical design, reduces the vibration interference of the cooling system, adopts the piezoelectric micro valve and the active control system, realizes the precise dynamic regulation and control of the cooling medium flow of the optical element, and thus significantly improves the working efficiency and the performance stability.

Description

Technical Field

[0001] This invention belongs to the field of optical control technology, and in particular relates to an active thermal control system for optical components. Background Technology

[0002] Against the backdrop of the rapid development of fourth-generation synchrotron radiation sources towards extremely high brightness and high flux, the optical components at the beamline front end are facing unprecedented challenges of extreme thermal loads. The continuously increasing heat flux density inevitably induces thermal deformation and thermal stress distribution on the component surface, leading to significant degradation in surface accuracy and optical transfer function, severely restricting the overall beam quality, coherence, and reliability of experimental data. Therefore, developing efficient and precise thermal management and stress relief technologies for extreme high thermal load conditions has become a crucial core engineering technology for breaking through existing performance bottlenecks and fully unleashing the scientific potential of next-generation light sources.

[0003] Research on heat recovery technology for optical components of synchrotron radiation sources, both domestically and internationally, mainly focuses on aspects such as structure, materials, optimization of cooling pipelines, and indirect cooling structures. As the performance of synchrotron radiation sources continues to improve, the thermal load on the surface of optical components is constantly increasing. Therefore, developing precise, efficient, and reliable heat recovery technology for crystal monochromators is of great significance for improving the working performance of synchrotron radiation optical components. Summary of the Invention

[0004] In view of this, the present invention aims to provide an active thermal control system for optical components, which adopts a dual-sided symmetrical cooling architecture. The piezoelectric microvalve effectively enhances the heat transfer process by controlling the cooling flow channel with high precision, ensuring that it is always in the optimal operating temperature range, thereby guaranteeing the thermal stability and surface accuracy of the optical components. This solves the thermal management problem in high-power synchrotron radiation optical systems, provides a key thermal solution for core components such as monochromators and mirrors, and improves the quality of synchrotron radiation beamlines.

[0005] To achieve the above objectives, the technical solution created by this invention is implemented as follows: An active thermal control system for an optical element includes: two cooling plates, respectively placed on both sides of the optical element; a cooling medium flowing in the cooling plates to cool the optical element, wherein the flow direction of the cooling medium in the two cooling plates is opposite; a temperature sensor for measuring the measured temperature of the optical element; a piezoelectric microvalve connected to the two cooling plates for controlling the flow rate of the cooling medium in the two cooling plates; a pressure sensor disposed at both ends of the piezoelectric microvalve for sensing the pressure difference between the two ends of the piezoelectric microvalve; and a control unit for controlling the piezoelectric microvalve to adjust the flow rate of the cooling medium in the two cooling plates based on the measured temperature and pressure difference.

[0006] Furthermore, the control unit includes a temperature control architecture and a flow control architecture. In the temperature control architecture, the temperature deviation between the measured temperature and the preset target temperature is calculated, and the temperature deviation is converted into the desired cooling medium flow rate. In the flow control architecture, based on the actual deviation between the desired cooling medium flow rate and the actual cooling medium flow rate, the adjustment amount of the cooling medium flow rate is calculated, and then the adjustment amount is converted into a control signal for controlling the piezoelectric microvalve. After the piezoelectric microvalve completes the adjustment according to the control signal, it converts the pressure difference across the piezoelectric microvalve into the current flow rate of the cooling medium based on the principle of fluid mechanics and the correspondence between pressure difference and flow rate.

[0007] Furthermore, a feedforward compensation mechanism is introduced into the flow control architecture. In this mechanism: a radial basis function neural network is used to establish a hysteresis nonlinear mapping relationship between the input and output of the piezoelectric microvalve; based on the hysteresis nonlinear mapping relationship, an inverse hysteresis model is established and connected in series to the input of the piezoelectric microvalve to form hysteresis characteristic feedforward compensation; the desired cooling medium flow rate is input into the inverse hysteresis model to generate a pre-hysteresis compensation driving voltage, which is then applied to the input of the piezoelectric microvalve. The piezoelectric microvalve calculates the difference between the pre-hysteresis compensation driving voltage and the control signal, so that the actual cooling medium flow rate output by the piezoelectric microvalve linearly follows the desired cooling medium flow rate.

[0008] Furthermore, the system also includes a base for housing optical components and two cooling plates, and a temperature sensor is mounted on the base via a flexible mechanism to isolate heat transfer between the optical components and the base.

[0009] Furthermore, the system also includes a cooling chip that contacts the optical element; the control unit controls the cooling chip to cool the optical element based on information sensed by the temperature sensor and the piezoelectric microvalve.

[0010] Furthermore, each cooling plate has multiple parallel serpentine cooling channels arranged inside, with a gap between adjacent serpentine cooling channels.

[0011] Furthermore, the system also includes a cooling medium distribution plate, which is connected to the serpentine cooling channel and is used to distribute the cooling medium into the serpentine cooling channel.

[0012] Furthermore, the number of piezoelectric microvalves is the same as the number of serpentine cooling channels. All piezoelectric microvalves are connected to the cooling medium distribution plate, and each piezoelectric microvalves controls the flow rate of the cooling medium in a corresponding serpentine cooling channel.

[0013] Compared with the prior art, the present invention can achieve the following beneficial effects: This invention creates an active thermal control system for optical components, employing a dual-sided opposed serpentine microchannel cooling architecture. Piezoelectric microvalves effectively enhance heat transfer by precisely regulating the flow rate of the cooling channels, thereby ensuring the thermal stability and surface accuracy of the optical components. The control unit, based on data collected from pressure and temperature sensors, dynamically regulates the piezoelectric microvalves through a control algorithm to achieve precise control of the cooling medium flow rate. Ultimately, this precise flow regulation achieves efficient heat release and temperature stability, ensuring the system's thermal management performance under complex operating conditions. Simultaneously, the control unit adopts a hierarchical strategy: the active cooling medium flow control architecture (i.e., temperature control architecture and flow control architecture) serves as the core, performing basic flow regulation at the macroscopic level; the active cooling architecture (i.e., the control unit controlling the cooling chip) acts as a precise supplementary unit, completing the final temperature accuracy calibration and stabilization at the microscopic level. Attached Figure Description

[0014] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the overall structure of the active thermal control system for optical elements described in an embodiment of the present invention; Figure 2 A schematic diagram of the structure of the base described in the embodiment of the present invention; Figure 3 A schematic diagram of the cooling flow channel described in the embodiment of the present invention; Figure 4 A schematic diagram of the control flow of the control unit described in the embodiment of the present invention; Figure 5 A control block diagram of the refrigeration chip described in the embodiments of the present invention; Figure 6 This is a schematic diagram of the internal structure of the cooling medium distribution plate described in an embodiment of the present invention.

[0015] Explanation of reference numerals in the attached figures: 1. Cooling plate; 2. Temperature sensor; 3. Piezoelectric microvalve; 4. Optical element; 5. Base; 6. Flexible mechanism; 7. Cooling chip; 8. Serpentine cooling channel; 9. Cooling medium distribution plate. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0017] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention through specific circumstances.

[0018] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] like Figures 1 to 5 As shown in the embodiment of the present invention, the active thermal control system for optical elements includes two cooling plates 1, a temperature sensor 2, a piezoelectric microvalve 3, and a control unit. The two cooling plates 1 are respectively placed on both sides of the optical element 4; a cooling medium flows in the cooling plates 1 to cool the optical element 4, and the flow directions of the cooling medium in the two cooling plates 1 are opposite. The temperature sensor 2 measures the measured temperature of the optical element 4. The piezoelectric microvalve 3 is connected to the two cooling plates 1 and is used to control the flow rate of the cooling medium in the two cooling plates 1. A pressure sensor is located at both ends of the piezoelectric microvalve 3 to sense the pressure difference between the two ends of the piezoelectric microvalve 3. The control unit controls the piezoelectric microvalve 3 to adjust the flow rate of the cooling medium in the two cooling plates 1 based on the measured temperature and pressure difference. The symmetrical arrangement of the cooling plates 1 provided by the present invention utilizes the vibration vector cancellation effect generated by the oppositely flowing cooling media to ensure the stability of the optical element 4.

[0020] In this invention, a piezoelectric microvalve 3 of model DURAY PV640 is preferably used. The piezoelectric microvalve 3 is an actuator for controlling the flow rate of the cooling medium. Its principle is as follows: the piezoelectric ceramic in the piezoelectric microvalve 3 undergoes corresponding minute deformation, thereby pushing the valve core in the piezoelectric microvalve 3 to move, changing the valve opening, and ultimately adjusting the flow resistance of the cooling medium to achieve flow control of the cooling medium. Furthermore, the active thermal control system for optical components provided in this embodiment mainly controls the temperature of synchrotron radiation mirrors, the first crystal of the dual-crystal monochromator, and other high-power heat-loaded optical components.

[0021] In some embodiments, the control unit includes a temperature control architecture and a flow control architecture. In the temperature control architecture, the temperature deviation between the measured temperature and the preset target temperature is calculated, and the temperature deviation is converted into the desired cooling medium flow rate. In the flow control architecture, based on the actual deviation between the desired cooling medium flow rate and the actual cooling medium flow rate, the adjustment amount of the cooling medium flow rate is calculated, and then the adjustment amount is converted into a control signal for controlling the piezoelectric microvalve 3. After the piezoelectric microvalve 3 completes the adjustment according to the control signal, based on the principles of fluid mechanics, the pressure difference across the piezoelectric microvalve 3 is converted into the current flow rate of the cooling medium through the correspondence between pressure difference and flow rate, thereby characterizing and feeding back the actual flow rate of the cooling medium in the flow path.

[0022] In this embodiment of the invention, an FPGA is specifically used as the core logic control unit of the control unit. The FPGA uses an integrated PID (proportional-integral-derivative) control algorithm to complete the data processing and calculation in the temperature control architecture and flow control architecture. The resulting PWM (Pulse-Width Modulation) control signal is used as the control signal of the piezoelectric microvalve 3. The control signal is converted from digital to analog and amplified by the power drive module. The piezoelectric microvalve 3 is adjusted according to the amplified control signal.

[0023] This invention also introduces a feedforward compensation mechanism into the flow control architecture, constructing a compensation model for the nonlinear hysteresis inverse of the piezoelectric microvalve. This inverse model is then used to preprocess the desired flow rate, actively offsetting the adverse effects of the piezoelectric material's hysteresis effect, thereby significantly reducing or even eliminating control errors caused by hysteresis and enhancing the system's response speed and control accuracy. Specifically, in some embodiments, the feedforward compensation mechanism includes: using a radial basis function (RBF) neural network to establish a hysteresis nonlinear mapping relationship between the input and output of the piezoelectric microvalve; establishing a hysteresis inverse model based on the hysteresis nonlinear mapping relationship, and connecting the hysteresis inverse model in series to the input of the piezoelectric microvalve to form hysteresis characteristic feedforward compensation; inputting the desired cooling medium flow rate into the hysteresis inverse model to generate a pre-hysteresis compensation driving voltage, and then applying the pre-hysteresis compensation driving voltage to the input of the piezoelectric microvalve. The piezoelectric microvalve calculates the difference between the pre-hysteresis compensation driving voltage and the control signal, so that the actual cooling medium flow rate output by the piezoelectric microvalve linearly follows the desired cooling medium flow rate.

[0024] In some embodiments, the system further includes a base 5, which is used to place the optical element 4 and two cooling plates 1, and the temperature sensor 2 is mounted on the base 5 via a flexible mechanism 6. The purpose of the flexible mechanism 6 is to form a mechanical thermal resistance to isolate heat transfer between the optical element 4 and the base 5. In this embodiment, four sets of embedded flexible mechanisms 6 are distributed on the base 5. Each flexible mechanism 6 is a flexible metal sheet with a thickness of 0.2 mm. The arrangement angle between two adjacent flexible mechanisms 6 is 120°. Temperature sensor mounting holes are provided on each flexible mechanism 6, and the fixed ends of four temperature sensors 2 are respectively installed in the four temperature sensor mounting holes. The sensing ends of the four temperature sensors 2 are in contact with the optical element 4, so that the four temperature sensors 2 can sense the temperature at different positions of the optical element 4. Correspondingly, the control unit receives and integrates the temperature information sensed by the four temperature sensors 2, and then controls the piezoelectric microvalve 3 to adjust the flow rate of the cooling medium in the two cooling plates 1 based on the integrated temperature information and pressure difference. In this embodiment, the control unit specifically takes the average value of the temperature sensed by the four temperature sensors 2 to complete the integration of the temperature sensed by the four temperature sensors 2.

[0025] In some embodiments, the system further includes a cooling element 7, which contacts the optical element 4. The control unit controls the cooling element 7 to cool the optical element 4 based on information sensed by the temperature sensor 2 and the piezoelectric microvalve 3. In this embodiment, multiple cooling element mounting seats are evenly distributed on the base 5, and multiple cooling elements 7 are correspondingly mounted in their respective mounting seats. The optical element 4 is then placed on the multiple cooling elements 7, and the multiple cooling elements 7 can cover the optical element 4, allowing for full coverage and uniform cooling of the optical element 4. This invention achieves auxiliary temperature control of the optical element 4 by setting the cooling element 7. Specifically, the control unit controls the cooling element 7 to adjust the temperature of the optical element 4 based on the temperature deviation between the measured temperature and the preset target temperature, using a driver matched with the cooling element 7.

[0026] In some embodiments, each cooling plate 1 has multiple parallel serpentine cooling channels 8 arranged inside, and there is a gap between two adjacent serpentine cooling channels 8. The gap here is the spacing between two parallel serpentine cooling channels 8, and the size of the gap is closely related to the cooling effect. In this embodiment of the invention, the gap is preferably obtained by optimizing the genetic algorithm. The objective function of the genetic algorithm is the temperature gradient, and the constraint condition is that the gap is within the range of [1, 5] mm. In some other embodiments, it can also be set empirically within the range of 1 to 5 mm.

[0027] In other embodiments, the shape of the cooling channel can be modified according to actual conditions, such as spiral, fractal tree, mesh cross-linking, or biomimetic topological flow shape, to adapt to different cooling and vibration requirements.

[0028] In some embodiments, the system also includes, Figure 6 The cooling medium distribution plate 9 shown is connected to the serpentine cooling channel 8. The cooling medium distribution plate 9 distributes the cooling medium into the serpentine cooling channel 8, thereby buffering flow pulsations between the piezoelectric microvalves 3 and the serpentine cooling channel 8, and preventing vibration interference from external piping. The number of piezoelectric microvalves 3 is the same as the number of serpentine cooling channels 8. All piezoelectric microvalves 3 are connected to the cooling medium distribution plate 9, and each piezoelectric microvalves 3 controls the flow rate of the cooling medium in one serpentine cooling channel 8. In this embodiment of the invention, the cooling medium distribution plate 9 and the two cooling plates 1 are obtained using 3D printing technology, and ultra-high vacuum epoxy resin is used to bond the cooling medium distribution plate 9 to the serpentine cooling channel 8.

[0029] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An active thermal control system for optical components, characterized in that, include: Two cooling plates are placed on either side of the optical element; The cooling medium flows in the cooling plates to cool the optical components, and the flow direction of the cooling medium in the two cooling plates is opposite. Temperature sensor, used to measure the actual temperature of optical components; A piezoelectric microvalve, connected to two cooling plates, is used to control the flow rate of the cooling medium between the two cooling plates; A pressure sensor is installed at both ends of the piezoelectric microvalve to sense the pressure difference between the two ends of the piezoelectric microvalve. The control unit adjusts the flow rate of the cooling medium in the two cooling plates by controlling the piezoelectric microvalve based on the measured temperature and pressure difference.

2. The active thermal control system for optical components according to claim 1, characterized in that, The control unit includes a temperature control architecture and a flow control architecture; In the temperature control architecture: calculate the temperature deviation between the measured temperature and the preset target temperature, and convert the temperature deviation into the desired cooling medium flow rate; In the flow control architecture: based on the actual deviation between the desired cooling medium flow rate and the actual cooling medium flow rate, the adjustment amount of the cooling medium flow rate is calculated, and then the adjustment amount is converted into a control signal to control the piezoelectric microvalve. After the piezoelectric microvalve completes the adjustment according to the control signal, it converts the pressure difference between the two ends of the piezoelectric microvalve into the current flow rate of the cooling medium by using the correspondence between pressure difference and flow rate, based on the principles of fluid mechanics.

3. The active thermal control system for optical elements according to claim 2, characterized in that, Furthermore, a feedforward compensation mechanism is introduced into the flow control architecture. In the feedforward compensation mechanism: A radial basis function neural network is used to establish a hysteresis nonlinear mapping relationship between the input and output of the piezoelectric microvalve; Based on the hysteresis nonlinear mapping relationship, a hysteresis inverse model is established and connected in series to the input end of the piezoelectric microvalve to form a hysteresis characteristic feedforward compensation. The desired cooling medium flow rate is input into the hysteresis inverse model to generate a pre-hysteresis compensation drive voltage. This pre-hysteresis compensation drive voltage is then applied to the input of the piezoelectric microvalve. The piezoelectric microvalve calculates the difference between the pre-hysteresis compensation drive voltage and the control signal, so that the actual cooling medium flow rate output by the piezoelectric microvalve linearly follows the desired cooling medium flow rate.

4. The active thermal control system for optical elements according to claim 1, characterized in that, The system also includes a base for housing optical components and two cooling plates, and a temperature sensor is mounted on the base via a flexible mechanism to isolate heat transfer between the optical components and the base.

5. The active thermal control system for optical components according to claim 1, characterized in that, The system also includes a cooling element that contacts the optical components; the control unit controls the cooling element to cool the optical components based on information sensed by the temperature sensor and the piezoelectric microvalve.

6. The active thermal control system for optical components according to claim 1, characterized in that, Each cooling plate has multiple parallel serpentine cooling channels arranged inside, with a gap between adjacent serpentine cooling channels.

7. The active thermal control system for optical elements according to claim 6, characterized in that, The system also includes a cooling medium distribution plate, which is connected to the serpentine cooling channel and is used to distribute the cooling medium into the serpentine cooling channel.

8. The active thermal control system for optical elements according to claim 7, characterized in that, The number of piezoelectric microvalves is the same as the number of serpentine cooling channels. All piezoelectric microvalves are connected to the cooling medium distribution plate, and each piezoelectric microvalves controls the flow rate of the cooling medium in a corresponding serpentine cooling channel.

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