Constant temperature control method and device for optical crystal and laser

Abstract

The invention relates to a constant temperature control method and device for an optical crystal and a laser, and the control method comprises the following steps: S1, collecting the temperatures of at least two different positions of the optical crystal in real time, so as to obtain at least two actually measured temperature values reflecting the internal thermal state of the crystal; s2, acquiring at least one external disturbance parameter influencing the temperature of the optical crystal in real time; s3, based on the at least two actually measured temperature values, the external disturbance parameters and a preset target temperature, a control quantity is calculated through a compound control algorithm; and S4, according to the control quantity, driving a bidirectional temperature control actuator with heating and active refrigeration capabilities to adjust the temperature of the optical crystal. By constructing a double-point feedback-multi-mode feed-forward-bidirectional execution composite control architecture, the internal thermal gradient of the crystal is sensed in real time by utilizing double-point temperature measurement; various thermal disturbances are accurately counteracted in combination with feedforward compensation of laser power and environment temperature, and an actuator for active heating and rapid semiconductor refrigeration is integrated to realize millisecond-level bidirectional temperature control, so that the crystal steady-state temperature control precision is improved to + / -0.01 DEG C, the temperature stabilization time is remarkably shortened when the laser power suddenly changes, the anti-disturbance capability of the system is enhanced, and the service life of the system is prolonged. The crystal can keep extreme temperature stability for a long time under various working conditions, and finally the performance of the optical crystal and the long-term stability of the output power of a laser are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and more specifically, to a method, apparatus, and laser for isothermal control of optical crystals. Background Technology

[0002] In applications involving precision optical systems, especially high-power lasers, the performance of optical crystals, such as nonlinear frequency conversion crystals, electro-optic modulation crystals, and acousto-optic crystals, is closely related to the stability of their operating temperature. These optical crystals are usually extremely sensitive to temperature changes. Even small temperature fluctuations can cause changes in their optical phase matching conditions, refractive index, or internal stress state, leading to a decrease in optical conversion efficiency, deterioration of beam quality, or operating point drift, ultimately severely affecting the output performance and long-term stability of the entire optical system.

[0003] However, existing temperature control schemes for such optical crystals still fall short in terms of overall performance when dealing with the demands of high-precision and fast-response applications. They exhibit hysteresis in responding to complex thermal dynamics, which can easily lead to thermal failure of the optical crystal. In particular, under conditions of high power, high repetition frequency, or rapidly changing environments, it is difficult to maintain stable thermal boundary conditions at the crystal's operating point. Existing solutions lack sufficient sensing and control dimensions when dealing with nonlinear heat conduction and local heat accumulation within the crystal, resulting in a gap between temperature control accuracy and actual requirements. This, in turn, affects the conversion efficiency, beam quality, and long-term service reliability of the optical crystal, thus limiting the performance limits of high-end laser and optoelectronic systems. Summary of the Invention

[0004] Based on this, and in response to the above problems, the present invention provides a method, apparatus and laser for constant temperature control of optical crystals, which greatly improves the conversion efficiency, beam quality and long-term service reliability of optical crystals.

[0005] To achieve the above objectives, the present invention provides a method for constant temperature control of optical crystals, comprising the following steps: S1, acquiring the temperature at at least two different locations of the optical crystal in real time to obtain at least two measured temperature values ​​reflecting the internal thermal state of the crystal; S2, acquiring at least one external disturbance parameter affecting the temperature of the optical crystal in real time; S3, calculating a control quantity based on the at least two measured temperature values, the external disturbance parameter, and a preset target temperature using a composite control algorithm; S4, driving a bidirectional temperature control actuator with heating and active cooling capabilities to adjust the temperature of the optical crystal according to the control quantity.

[0006] In step S2 of one specific embodiment, the external disturbance parameters include the real-time laser power value of the laser in which the optical crystal is located and / or the real-time ambient temperature value of the environment in which the optical crystal is located.

[0007] In step S1 of one specific embodiment, the temperature of the optical crystal is acquired by a three-wire or four-wire temperature sensor; and / or, the temperature sensor signal is synchronously sampled by an analog-to-digital converter with a resolution of not less than 24 bits and a sampling frequency of not less than 100Hz.

[0008] In one specific embodiment, the at least two different locations include a first temperature measuring point located at the bottom of the optical crystal and a second temperature measuring point located at the top or upper part of the optical crystal.

[0009] In step S3 of one specific embodiment, the calculation based on at least two measured temperature values ​​includes: calculating the real-time difference ΔT between the measured temperature values ​​of the first temperature measuring point and the second temperature measuring point; and querying a pre-stored temperature gradient compensation coefficient table according to the real-time difference ΔT to obtain the corresponding temperature gradient compensation coefficient K_ΔT.

[0010] In step S3 of one specific embodiment, the composite control algorithm is an incremental PID algorithm with feedforward compensation; the control quantity is the control increment Δu(t), which is calculated by the following formula: Δu(t)=Kp*[e(t)-e(t-1)]+Ki*e(t)+Kd*[e(t)-2e(t-1)+e(t-2)]+ΣK_comp, where e(t) is the measured temperature value of the first or second temperature measuring point at the current sampling time t. As the deviation between the main feedback and the target temperature; e(t-1) is the measured temperature value of the first or second temperature measuring point at the previous sampling time t-1 as the deviation between the main feedback and the target temperature, and e(t-2) is the measured temperature value of the first or second temperature measuring point at the previous two sampling times t-2 as the deviation between the main feedback and the target temperature; Kp, Ki, and Kd are preset PID parameters; ΣK_comp is the total compensation term, which includes at least the temperature gradient compensation coefficient K_ΔT.

[0011] In one specific embodiment, the total compensation term ΣK_comp further includes: a laser power compensation coefficient K_P obtained by querying a pre-stored laser power-compensation coefficient table based on the real-time laser power value; and / or an ambient temperature compensation coefficient K_env obtained by querying a pre-stored ambient temperature-compensation coefficient table based on the real-time ambient temperature value.

[0012] In step S4 of one specific embodiment, the bidirectional temperature control actuator includes a heating module and a semiconductor refrigeration module that are independent of each other; the step of driving the actuator according to the control quantity includes: when the control quantity indicates that the temperature needs to be increased, outputting a first driving signal to the heating module; and when the control quantity indicates that the temperature needs to be decreased, outputting a second driving signal to the semiconductor refrigeration module.

[0013] In one specific embodiment, the first drive signal and the second drive signal are PWM signals; the heating module is a PTC ceramic heating element, and the semiconductor cooling module is a TEC cooling element.

[0014] In one specific embodiment, a temperature control device for an optical crystal is also provided, comprising: a multi-channel temperature sensing unit for acquiring the temperature at at least two different locations of the optical crystal; a disturbance parameter acquisition unit for acquiring at least one external disturbance parameter affecting the temperature of the optical crystal; a controller connected to the multi-channel temperature sensing unit and the disturbance parameter acquisition unit respectively, for executing the aforementioned temperature control method for the optical crystal; and a bidirectional temperature control execution unit connected to the controller for heating or cooling the optical crystal according to the instructions of the controller.

[0015] In one specific embodiment, the multi-channel temperature sensing unit includes: a first platinum resistance temperature sensor disposed at the bottom of the optical crystal and a second platinum resistance temperature sensor disposed at the top or upper part of the optical crystal; and a high-precision analog-to-digital converter for synchronously converting the signals of the first and second platinum resistance temperature sensors into digital signals.

[0016] In one specific embodiment, the disturbance parameter acquisition unit is communicatively connected to the laser main control board and is used to receive real-time laser power values ​​from the laser main control board; it also includes an ambient temperature sensor for detecting the external ambient temperature of the device.

[0017] In one specific embodiment, the bidirectional temperature control execution unit includes: a heating drive circuit and a heating module driven thereon; a cooling drive circuit and a semiconductor cooling module driven thereon; wherein the heating module and the semiconductor cooling module are coupled to the optical crystal.

[0018] In one specific embodiment, the controller is an ARM controller, which is connected to the heating drive circuit and the cooling drive circuit respectively through two independent PWM output ports.

[0019] In one specific embodiment, a laser is also provided, including a laser generating unit and an optical crystal, and further including the aforementioned temperature control device for the optical crystal, for constantly controlling the temperature of the crystal at a preset target temperature.

[0020] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a method and apparatus for isothermal control of optical crystals. By constructing a composite control architecture of "dual-point feedback - multi-modal feedforward - bidirectional execution," the temperature control performance of optical crystals is significantly improved. Real-time acquisition of internal thermal gradient information of the crystal is achieved through dual-point synchronous temperature measurement, combined with feedforward compensation for external disturbances such as laser power and ambient temperature. This enables the control algorithm to accurately predict and counteract the effects of various thermal disturbances. Simultaneously, a bidirectional temperature control actuator integrating active heating and rapid semiconductor cooling is employed, achieving millisecond-level response and bidirectional temperature adjustment capability. This enhances the temperature control dimension of the optical crystal, improving the steady-state temperature control accuracy to the ±0.01℃ level. During sudden changes in laser power, the temperature recovery time is significantly shortened. Furthermore, the robustness of the system to slow disturbances such as changes in ambient temperature is significantly enhanced, ensuring that the optical crystal maintains long-term, extremely high temperature stability under various harsh operating conditions. This greatly improves the conversion efficiency, beam quality, and long-term service reliability of the optical crystal. The laser provided by this invention can guarantee long-term stability of output power. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the control flow of a constant temperature control method for optical crystals according to the present invention.

[0022] Figure 2 This is a schematic diagram of the principle of a constant temperature control device for optical crystals according to the present invention. Detailed Implementation

[0023] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0024] like Figure 1As shown, this embodiment provides a constant temperature control method for optical crystals, including the following steps: S1, real-time acquisition of the temperature at at least two different locations of the optical crystal to obtain at least two measured temperature values ​​reflecting the internal thermal state of the crystal; S2, real-time acquisition of at least one external disturbance parameter affecting the temperature of the optical crystal; S3, calculation of a control quantity based on the at least two measured temperature values, the external disturbance parameter, and a preset target temperature (e.g., 150°C) using a composite control algorithm; S4, driving a bidirectional temperature control actuator with heating and active cooling capabilities to adjust the temperature of the optical crystal according to the control quantity. This embodiment provides a method for isothermal control of optical crystals, constructing a composite control architecture of "dual-point feedback - multi-modal feedforward - bidirectional execution." Unlike traditional single-point temperature feedback, this method simultaneously acquires the temperature at at least two different locations (e.g., bottom and top) of the optical crystal (such as a frequency doubling crystal) in step S1 to obtain state information reflecting the internal thermal gradient (ΔT) of the optical crystal. This solves the problem that single-point temperature measurement cannot characterize the true internal thermal field. Through dual-point temperature measurement and internal gradient compensation, it effectively eliminates control deviations caused by thermal inhomogeneity within the crystal. In step S2, key external disturbance parameters such as laser power and ambient temperature are actively acquired and used as feedforward. The signal is introduced into the control system; in step S3, the composite control algorithm deeply integrates the above-mentioned dual-point temperature feedback and gradient difference with multi-source feedforward compensation to calculate the precise control quantity. This process essentially transforms the dynamic heat distribution inside the optical crystal and the predicted influence of the main external disturbance sources into control commands; in step S4, a bidirectional actuator with independent active cooling and heating capabilities is driven to achieve bidirectional and rapid adjustment of temperature changes, overcoming the lag problem of traditional methods that only rely on heating and natural cooling. The isostatic control method for optical crystals provided in this embodiment can ensure that optical crystals maintain long-term high stability under various working conditions and environments.

[0025] In one specific embodiment, in step S2, the external disturbance parameters include the real-time laser power value of the laser where the optical crystal is located and / or the real-time ambient temperature value of the environment where the optical crystal is located. The laser power is the most important and fastest disturbance source causing changes in the heat generated inside the optical crystal; the ambient temperature affects the overall heat exchange balance between the temperature-controlled furnace and the outside world and is a slowly changing disturbance source. By using these as feedforward inputs and actively monitoring and compensating for the disturbances of these two core external factors, the system can act in advance when the laser power changes abruptly, suppressing temperature drift; at the same time, it overcomes the temperature drift caused by changes in ambient temperature, significantly improving the stability of the system in all weather conditions and across the entire power range.

[0026] In one specific embodiment, in step S1, the temperature of the optical crystal is acquired by a three-wire or four-wire temperature sensor (such as PT1000); and / or, the temperature sensor signal is synchronously sampled by an analog-to-digital converter with a resolution of not less than 24 bits and a sampling frequency of not less than 100Hz, thus constructing an ultra-high precision temperature sensing path, providing reliable and high-resolution feedback data for the entire control system, and serving as the hardware guarantee for achieving the ±0.01℃ precision temperature control target.

[0027] In one specific embodiment, the at least two different locations include a first temperature measuring point located at the bottom of the optical crystal and a second temperature measuring point located at the top or upper part of the optical crystal. The combination of the two temperature measuring points can more realistically reflect the overall thermal state of the crystal, avoiding control deviations caused by improper selection of a single temperature measuring point, and providing direct data for accurately assessing the actual operating temperature and internal thermal stress of the crystal.

[0028] In one specific embodiment, step S3, the calculation based on at least two measured temperature values, includes: calculating the real-time difference ΔT between the measured temperature values ​​of the first and second temperature measurement points; querying a pre-stored temperature gradient compensation coefficient table based on the real-time difference ΔT to obtain the corresponding temperature gradient compensation coefficient K_ΔT. ΔT is a direct measure of the internal thermal gradient of the crystal. Different ΔT values ​​correspond to different thermal distribution states of the crystal, requiring different compensation amounts to optimize control. By establishing a mapping relationship table between ΔT and the optimal compensation amount K_ΔT through experimental calibration, adaptive compensation for the internal thermal dynamics of the crystal is achieved. This allows the control algorithm to focus not only on the temperature at a certain point but also on the temperature uniformity, further improving the realism and accuracy of temperature control.

[0029] In one specific embodiment, in step S3, the composite control algorithm is an incremental PID algorithm with feedforward compensation; the control quantity is the control increment Δu(t), which is calculated by the following formula: Δu(t)=Kp*[e(t)-e(t-1)]+Ki*e(t)+Kd*[e(t)-2e(t-1)+e(t-2)]+ΣK_comp, where e(t) is the deviation between the measured temperature value of the first or second temperature measurement point at the current sampling time t as the main feedback and the target temperature; e(t-1) is the temperature value at the previous sampling time t. The measured temperature value of the first or second temperature measuring point at time t-1 is used as the deviation between the main feedback and the target temperature. e(t-2) is the measured temperature value of the first or second temperature measuring point at time t-2 in the first two sampling times, used as the deviation between the main feedback and the target temperature. Kp, Ki, and Kd are preset PID parameters. ΣK_comp is the total compensation term, which includes at least the temperature gradient compensation coefficient K_ΔT. This organically combines PID feedback control with targeted feedforward / compensation control, greatly improving the dynamic response speed and anti-interference capability while ensuring system stability.

[0030] In one specific embodiment, the total compensation term ΣK_comp further includes: a laser power compensation coefficient K_P obtained by querying a pre-stored laser power-compensation coefficient table based on the real-time laser power value. K_P enables the system to "predict" changes in laser power, achieving the fastest dynamic response; and / or, an ambient temperature compensation coefficient K_env obtained by querying a pre-stored ambient temperature-compensation coefficient table based on the real-time ambient temperature value. K_env eliminates the influence of ambient temperature drift. Understandably, the temperature gradient compensation coefficient table, laser power-compensation coefficient table, and / or ambient temperature-compensation coefficient table are established as follows: after the optical crystal constant temperature control system is built, near the preset target temperature, the compensation amount required to maintain the stability of the target temperature is measured and recorded under different temperature differences ΔT, different laser power values ​​P_laser, and / or different ambient temperatures T_env; based on the recorded compensation amount data, the compensation coefficient tables are generated using a fitting algorithm.

[0031] In one specific embodiment, in step S4, the bidirectional temperature control actuator includes a heating module and a semiconductor refrigeration module that are independent of each other; driving the bidirectional temperature control actuator according to the control quantity includes: when the control quantity indicates that heating is required, outputting a first drive signal to the heating module; when the control quantity indicates that cooling is required, outputting a second drive signal to the semiconductor refrigeration module. Understandably, when Δu(t) > 0, the heating module is controlled to operate, and the semiconductor refrigeration module is in standby mode; when Δu(t) < 0, the semiconductor refrigeration module is controlled to operate, and the heating module is in standby mode. However, in actual high-precision temperature control, there may be a "dead zone" or "minimum power adjustment range." For example, when the value of |Δu(t)| is very small and insufficient to drive the bidirectional temperature control actuator to operate effectively, keeping both in standby mode may be a better choice. This avoids frequent switching oscillations of the bidirectional temperature control actuator at the critical point, greatly reducing ineffective actions and mechanical / thermal stress of the actuator near the equilibrium point, and improving the long-term stability, energy efficiency ratio, and critical components of the system. The lifespan of components (such as heating modules and semiconductor refrigeration modules) is crucial to the long-term stability and lifespan of the system. To further improve this deficiency, the step of driving the bidirectional temperature control actuator according to the control quantity further includes: preset a control quantity threshold ε; when |Δu(t)|≤ε, controlling both the heating module and the semiconductor refrigeration module to be in a standby state of not working or maintaining a minimum holding power; when Δu(t)>ε, outputting a first driving signal related to (Δu(t)-ε) to the heating module; when Δu(t)<-ε, outputting a second driving signal related to (|Δu(t)|-ε) to the semiconductor refrigeration module.

[0032] In one specific embodiment, the first driving signal and the second driving signal are PWM signals; the heating module is a PTC ceramic heating element, and the semiconductor cooling module is a TEC cooling element, wherein both the PTC ceramic heating element and the TEC cooling element are configured to exchange heat with the optical crystal.

[0033] like Figure 2 As shown, in one specific embodiment, a constant temperature control device for an optical crystal is also provided, comprising: a multi-channel temperature sensing unit 10 for acquiring the temperature of at least two different locations of the optical crystal 100; a disturbance parameter acquisition unit for acquiring at least one external disturbance parameter affecting the temperature of the optical crystal 100; a controller 20 communicatively connected to the multi-channel temperature sensing unit 10 and the disturbance parameter acquisition unit, respectively, for executing the constant temperature control method for the optical crystal 100 as described above; and a bidirectional temperature control execution unit 30 communicatively connected to the controller 20 for heating or cooling the optical crystal 100 according to the instructions of the controller 20.

[0034] In one specific embodiment, the multi-channel temperature sensing unit 10 includes: a first platinum resistance temperature sensor 11 disposed at the bottom of the optical crystal 100 and a second platinum resistance temperature sensor 12 disposed at the top or upper part of the optical crystal 100; and a 24-bit high-precision analog-to-digital converter 13 for synchronously converting the signals of the first and second platinum resistance temperature sensors into digital signals.

[0035] In one specific embodiment, the disturbance parameter acquisition unit is communicatively connected to the laser main control board 40 and is used to receive real-time laser power values ​​from the laser main control board 40; it also includes an ambient temperature sensor 50 for detecting the external ambient temperature of the device.

[0036] In one specific embodiment, the bidirectional temperature control execution unit 30 includes: a heating drive circuit 31 and a heating module 32 driven therefrom; a cooling drive circuit 33 and a semiconductor cooling module 34 driven therefrom; wherein the heating module 32 and the semiconductor cooling module 34 are coupled to the optical crystal 100 to change the temperature of the optical crystal 100.

[0037] In one specific embodiment, the controller 20 is an ARM controller, which is connected to the heating drive circuit 31 and the cooling drive circuit 33 respectively through two independent PWM output ports.

[0038] In one specific embodiment, a laser is also provided, including a laser generating unit (such as an LD pump source and a gain crystal) and an optical crystal (frequency doubling crystal). It also includes a temperature control device for the aforementioned optical crystal, used to maintain the temperature of the crystal at a preset target temperature. Understandably, the optical crystal can be a frequency doubling crystal, and the laser can be a green laser. Taking an LBO crystal as an example, with a target temperature of 150°C, when the laser power suddenly increases from 0W to 1000W, the crystal's heat absorption power increases, and the bottom temperature sensor detects the temperature rise. The ARM controller looks up K_P = −0.05 based on the laser power increment, and combined with ΔT compensation and PID calculation, rapidly increases the power of the TEC cooler, suppressing temperature drift within 100ms and stabilizing the temperature at 150°C ± 0.01°C within 500ms, meeting the frequency doubling requirements of a high-power green laser.

[0039] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0040] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for isothermal control of optical crystals, characterized in that: Includes the following steps: S1. Real-time acquisition of the temperature at at least two different locations of the optical crystal to obtain at least two measured temperature values ​​that reflect the internal thermal state of the optical crystal; S2. Real-time acquisition of at least one external disturbance parameter that affects the temperature of the optical crystal; S3. Based on the at least two measured temperature values, the external disturbance parameters, and the preset target temperature, the control quantity is calculated using a composite control algorithm. S4. Based on the control quantity, drive a bidirectional temperature control actuator with heating and active cooling capabilities to adjust the temperature of the optical crystal.

2. The method for isostatic control of optical crystals according to claim 1, characterized in that: In step S2, the external disturbance parameters include the real-time laser power value of the laser in which the optical crystal is located and / or the real-time ambient temperature value of the environment in which the optical crystal is located.

3. A method for isothermal control of optical crystals according to claim 1 or 2, characterized in that: In step S1, the temperature of the optical crystal is acquired by a three-wire or four-wire temperature sensor; and / or, the temperature sensor signal is synchronously sampled by an analog-to-digital converter with a resolution of not less than 24 bits and a sampling frequency of not less than 100Hz.

4. The method for isostatic control of optical crystals according to claim 1, characterized in that: The at least two different locations include a first temperature measuring point located at the bottom of the optical crystal and a second temperature measuring point located at the top or upper part of the optical crystal.

5. The method for isostatic control of optical crystals according to claim 1, characterized in that: In step S3, the calculation based on at least two measured temperature values ​​includes: calculating the real-time difference ΔT between the measured temperature values ​​of the first temperature measurement point and the second temperature measurement point; and querying a pre-stored temperature gradient compensation coefficient table according to the real-time difference ΔT to obtain the corresponding temperature gradient compensation coefficient K_ΔT.

6. The method for isothermal control of optical crystals according to claim 5, characterized in that: In step S3, the composite control algorithm is an incremental PID algorithm with feedforward compensation; the control quantity is the control increment Δu(t), which is calculated using the following formula: Δu(t) = Kp*[e(t)-e(t-1)] + Ki*e(t) + Kd*[e(t)-2e(t-1) + e(t-2)] + ΣK_comp, where e(t) is the deviation between the measured temperature of the first or second temperature measurement point at the current sampling time t and the target temperature as the main feedback; e(t-1) is the deviation between the measured temperature of the first or second temperature measurement point at the previous sampling time t-1 and the target temperature as the main feedback; e(t-2) is the deviation between the measured temperature of the first or second temperature measurement point at the previous two sampling times t-2 and the target temperature as the main feedback; Kp, Ki, and Kd are preset PID parameters; ΣK_comp is the total compensation term, which includes at least the temperature gradient compensation coefficient K_ΔT.

7. The method for isothermal control of optical crystals according to claim 6, characterized in that: The total compensation item ΣK_comp further includes: a laser power compensation coefficient K_P obtained by querying a pre-stored laser power-compensation coefficient table based on the real-time laser power value; and / or an ambient temperature compensation coefficient K_env obtained by querying a pre-stored ambient temperature-compensation coefficient table based on the real-time ambient temperature value.

8. The method for isothermal control of optical crystals according to claim 1, characterized in that: In step S4, the bidirectional temperature control actuator includes a heating module and a semiconductor refrigeration module that are independent of each other; The actuator driven by the control quantity includes: when the control quantity indicates that heating is required, outputting a first drive signal to the heating module; When the control signal indicates that cooling is required, a second drive signal is output to the semiconductor cooling module.

9. A method for isothermal control of optical crystals according to claim 8, characterized in that: The first drive signal and the second drive signal are PWM signals; the heating module is a PTC ceramic heating element, and the semiconductor refrigeration module is a TEC refrigeration element.

10. A temperature control device for optical crystals, characterized in that: include: A multi-channel temperature sensing unit is used to collect the temperature at at least two different locations of the optical crystal; The disturbance parameter acquisition unit is used to acquire at least one external disturbance parameter that affects the temperature of the optical crystal. The controller is connected to the multi-channel temperature sensing unit and the disturbance parameter acquisition unit respectively, and is used to execute the isothermal control method for optical crystals as described in any one of claims 1 to 9; In addition, a bidirectional temperature control execution unit, connected to the controller, is used to heat or cool the optical crystal according to the instructions of the controller.

11. A temperature control device for optical crystals according to claim 10, characterized in that: The multi-channel temperature sensing unit includes: a first platinum resistance temperature sensor disposed at the bottom of the optical crystal and a second platinum resistance temperature sensor disposed at the top or top of the optical crystal; and a high-precision analog-to-digital converter for synchronously converting the signals of the first and second platinum resistance temperature sensors into digital signals.

12. A temperature control device for optical crystals according to claim 10, characterized in that: The disturbance parameter acquisition unit is communicatively connected to the laser main control board and is used to receive real-time laser power values ​​from the laser main control board; it also includes an ambient temperature sensor for detecting the external ambient temperature of the device.

13. A temperature control device for optical crystals according to claim 10, characterized in that: The bidirectional temperature control execution unit includes: a heating drive circuit and a heating module driven thereon; a cooling drive circuit and a semiconductor cooling module driven thereon; wherein the heating module and the semiconductor cooling module are coupled to the optical crystal.

14. A temperature control device for optical crystals according to claim 13, characterized in that: The controller is an ARM controller, which is connected to the heating drive circuit and the cooling drive circuit respectively through two independent PWM output ports.

15. A laser, comprising a laser generating unit and an optical crystal, characterized in that, It also includes a temperature control device for an optical crystal as described in any one of claims 10 to 14, for keeping the temperature of the crystal constant at a preset target temperature.

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