Terahertz gas laser tube wall temperature control system and control method

Abstract

The invention discloses a terahertz gas laser tube wall temperature control system and method. The terahertz gas laser tube wall temperature control system comprises a master control refrigerator ZYNQ, an upper computer and a cooling module. The master control refrigerator ZYNQ is used for acquiring temperature data of a laser tube wall and an environment temperature in real time, and the upper computer is used for setting a target temperature and switching on and off the whole temperature control system; relates to the technical field of lasers, and solves the technical problem that the cooling speed is low when the temperature of a laser tube wall is reduced at present. The temperature of the tube wall of the terahertz gas laser can be rapidly and accurately controlled by controlling refrigeration and heating of the semiconductor refrigeration sheet assembly, the stability of power and frequency of the laser is improved, and miniaturization of the terahertz gas laser tube wall temperature control system is achieved. And automatic feedback control can be realized, so that the terahertz gas laser can continuously and stably operate for a long time in practical application, and the labor cost of operators is saved.

Description

Technical Field

[0001] The invention belongs to the field of temperature control and relates to laser technology, in particular to a terahertz gas laser tube wall temperature control system and a control method. Background Art

[0002] Terahertz waves are a section of the electromagnetic spectrum from part of the millimeter wave band (about 0.1THz) to the far infrared region (about 25THz). Terahertz waves are also called submillimeter waves in the field of electronics and far-infrared light in the field of spectroscopy. The light source that can produce terahertz frequency band lasers is called terahertz lasers. Terahertz lasers are used in many aspects, such as terahertz imaging, terahertz medical treatment, terahertz communication, etc. Terahertz lasers are also important light sources for far-infrared laser interferometers / polarizers in plasma diagnostic technology.

[0003] In the fields of THz imaging, spectroscopy, plasma diagnosis, THz radar imaging, etc., terahertz lasers are required to have high output power and stable frequency. However, a large amount of waste heat is generated during the operation of the laser, causing the laser wavelength to drift, the output power to decrease, and even damage the laser. Therefore, it is of great significance to dissipate heat in a timely and effective manner, ensure the temperature stability of the laser, and realize the stability control of the tube wall temperature of the terahertz gas laser. At present, the cooling control of the tube wall temperature of the terahertz gas laser is mostly based on the existing dual laser resonant cavity structure (such as Figure 4 (As shown) Add a water cooler to cool the pipe wall. This cooling method mainly relies on the heat absorption of the flowing water to reduce the temperature. Not only is the cooling speed slow, but the cooling effect is not obvious enough.

[0004] In recent years, a lot of research has been carried out on laser temperature control technology based on thermoelectric cooling, mainly focusing on semiconductor lasers and solid-state lasers with lower power. Therefore, it is very necessary to design a high-precision stability control system based on the laser tube wall temperature for terahertz gas lasers to promote the integration and miniaturization of terahertz gas lasers. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art; to this end, the present invention proposes a terahertz gas laser tube wall temperature control system and control method, which are used to solve the current technical problem of slow cooling speed when cooling the laser tube wall temperature. The present invention can quickly and accurately control the terahertz gas laser tube wall temperature to solve the above problem by controlling the cooling and heating of the semiconductor refrigeration plate assembly.

[0006] To achieve the above-mentioned object, the first aspect of the present invention provides a terahertz gas laser tube wall temperature control system, comprising: a main control cooler ZYNQ, a host computer and a cooling module;

[0007] The main control cooler ZYNQ is used to obtain the temperature data of the laser tube wall and the ambient temperature in real time, and perform median filtering, averaging processing and PWM output to drive the semiconductor cooling plate assembly; and control the cooling module based on the ambient temperature and temperature data;

[0008] The host computer is used to set the target temperature and switch the entire temperature control system; and to draw a temperature change curve based on the temperature data; and the host computer communicates with the main controller ZYNQ through a serial port.

[0009] The cooling module includes: a plurality of semiconductor refrigeration plate assemblies, a fixing fixture and heat dissipation fins located at the upper and lower ends of the fixing fixture, which are arranged in the tube wall of the terahertz gas laser; the fixing fixture is used to fix the semiconductor refrigeration plate assembly on the laser tube wall; the heat dissipation fins are used to absorb the heat of the laser tube wall and the hot end of the semiconductor refrigeration plate assembly and then dissipate the heat by convection.

[0010] Preferably, a PT1000 temperature sensor is also embedded inside the fixing fixture, and the PT1000 temperature sensor is used to measure the analog signal value of the laser tube wall and convert it into temperature data through an A / D analog-to-digital converter and then send it to the main control cooler ZYNQ.

[0011] Preferably, a plurality of the semiconductor refrigeration plate assemblies are distributed at intervals, and the interval distance is 20 cm.

[0012] Preferably, the semiconductor refrigeration plate assembly adjusts the voltage to the regulated voltage through an H-bridge driving circuit.

[0013] Preferably, the controlling the cooling module based on the ambient temperature and the temperature data comprises:

[0014] Extract the target temperature, temperature data and ambient temperature and mark them as T0, Tn and Tw respectively, adjust the target temperature T0 based on the temperature data Tn and ambient temperature Tw to obtain the target corrected temperature T1;

[0015] The target corrected temperature T1 and the temperature data Tn are input into the voltage adjustment model to obtain the adjustment voltage; the power of the semiconductor refrigeration plate assembly is adjusted based on the adjustment voltage; wherein the voltage adjustment model is obtained based on the neural network model.

[0016] Preferably, the adjusting the target temperature T0 based on the temperature data Tn and the ambient temperature Tw includes:

[0017] Perform linear fitting on the acquired temperature data Tn to obtain a temperature change curve F(T), and calculate the slope k of the temperature data at the current time point in the temperature change curve F(T);

[0018] The target corrected temperature T1 is obtained by the calculation formula T1=T0+u×k×h(Tn-Tw); wherein h is the heat transfer coefficient and u is the correction coefficient.

[0019] It should be noted that the specific value of the correction coefficient k is related to the surface area, material and thickness of the tube wall, and can be confirmed by fitting experimental data.

[0020] Since the fluctuation of ambient temperature will affect the tube wall temperature of the terahertz gas laser, the change of ambient temperature will cause the expansion and contraction of the laser resonant cavity, thereby affecting the working state and output characteristics of the laser. By introducing the target correction temperature, the set target temperature can be adjusted according to the environment in which the terahertz gas laser is located to reduce the impact of the ambient temperature on it.

[0021] Preferably, the voltage adjustment model is obtained based on a neural network model, including:

[0022] The model to be trained is constructed based on a recurrent neural network and an attention mechanism is introduced, and the target temperature, temperature data and adjustment voltage are retrieved from the database;

[0023] The target temperature, temperature data and adjustment voltage are integrated into several groups of training data and test data; the artificial intelligence model is trained using the training data, and the trained model is tested using the test data to obtain the test accuracy; the model is optimized and adjusted according to the test accuracy to obtain a voltage adjustment model whose input is the target temperature and temperature data and whose output is the adjustment voltage.

[0024] The second aspect of the present invention also discloses a method for controlling the tube wall temperature of a terahertz gas laser, comprising:

[0025] Step 1: Set the target temperature through the host computer and start the temperature control system. The main control cooler ZYNQ starts to collect the temperature data of the laser tube wall and the ambient temperature in real time;

[0026] Step 2: Perform median filtering on the collected temperature data to reduce the impact of noise, draw a temperature change curve based on the temperature data, and control the cooling module based on the ambient temperature and the temperature data.

[0027] Compared with the prior art, the beneficial effects of the present invention are: compared with the cooling of the tube wall by the traditional large-scale water chiller, by controlling the cooling and heating of the semiconductor refrigeration plate assembly, the temperature of the tube wall of the terahertz gas laser can be quickly and accurately controlled, the stability of the laser power and frequency is improved, and the miniaturization of the temperature control system of the tube wall of the terahertz gas laser is realized. In addition, automatic feedback control can be realized, so that the terahertz gas laser can continue to operate stably for a long time in practical applications, saving the labor cost of the operating personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is a module connection diagram of a terahertz gas laser tube wall temperature control system in the present invention;

[0030] Figure 2 It is a schematic diagram of the process of an embodiment of the present invention;

[0031] Figure 3 It is a schematic diagram of the cooperation between the laser tube wall and the fixing fixture in the present invention;

[0032] Figure 4 It is a schematic diagram of the structure of a dual laser resonant cavity in the prior art.

[0033] In the figure, 1. Laser tube wall; 2. Fixing fixture. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] See also Figure 1-Figure 4 , the first aspect of the present invention provides a terahertz gas laser tube wall temperature control system, including: a main control cooler ZYNQ, a host computer and a cooling module;

[0036] The main control cooler ZYNQ is used to obtain the temperature data of the laser tube wall 1 and the ambient temperature in real time, and perform median filtering, averaging processing and PWM output to drive the semiconductor cooling plate assembly; and control the cooling module based on the ambient temperature and temperature data;

[0037] The host computer is used to set the target temperature and switch the entire temperature control system; and to draw a temperature change curve based on the temperature data; and the host computer communicates with the main controller ZYNQ through a serial port.

[0038] The cooling module includes: a plurality of semiconductor refrigeration plate assemblies arranged in the terahertz gas laser tube wall 1, a fixing fixture 2 and heat dissipation fins located at the upper and lower ends of the fixing fixture 2; the plurality of semiconductor refrigeration plate assemblies are distributed at intervals, and the interval distance is 20 cm; the fixing fixture 2 is used to fix the semiconductor refrigeration plate assembly on the laser tube wall 1; the heat dissipation fins are used to absorb the heat of the laser tube wall 1 and the hot end of the semiconductor refrigeration plate assembly and then dissipate the heat by convection, and the fixture is made of copper material to improve the heat conduction efficiency.

[0039] The fixing fixture 2 in this embodiment also has a PT1000 temperature sensor embedded inside. The PT1000 reflects the model of temperature change. The PT1000 temperature sensor is used to measure the analog signal value of the laser tube wall 1 and convert it into temperature data through an A / D analog-to-digital converter and then send it to the main control cooler ZYNQ.

[0040] The semiconductor refrigeration plate assembly used in this embodiment adjusts the voltage to the adjustment voltage through the H-bridge driving circuit; and the voltage is regulated and controlled by the semiconductor refrigeration plate assembly driver, and can control the bidirectional current to achieve flexible and rapid temperature changes, with a maximum rated power of up to 360W.

[0041] The key content of the present invention is: controlling the cooling module based on the ambient temperature and temperature data, including:

[0042] Extract the target temperature, temperature data and ambient temperature and mark them as T0, Tn and Tw respectively, adjust the target temperature T0 based on the temperature data Tn and ambient temperature Tw to obtain the target corrected temperature T1;

[0043] Perform linear fitting on the acquired temperature data Tn to obtain a temperature change curve F(T), and calculate the slope k of the temperature data at the current time point in the temperature change curve F(T);

[0044] The target corrected temperature T1 is obtained by calculating the formula T1=T0+u×k×h(Tn-Tw); wherein h is the heat transfer coefficient and u is the correction coefficient;

[0045] The power of the semiconductor refrigeration plate assembly is regulated based on the adjusted voltage; wherein the voltage adjustment model is obtained based on the neural network model.

[0046] It should be noted that the specific value of the correction coefficient k is related to the surface area, material and thickness of the tube wall, and can be confirmed by fitting experimental data.

[0047] Since the fluctuation of ambient temperature will affect the tube wall temperature of the terahertz gas laser, the change of ambient temperature will cause the expansion and contraction of the laser resonant cavity, thereby affecting the working state and output characteristics of the laser. By introducing the target correction temperature, the set target temperature can be adjusted according to the environment in which the terahertz gas laser is located to reduce the impact of the ambient temperature on it.

[0048] Specifically, the voltage adjustment model is obtained based on the neural network model, including:

[0049] The model to be trained is constructed based on a recurrent neural network and an attention mechanism is introduced, and the target temperature, temperature data and adjustment voltage are retrieved from the database;

[0050] The target temperature, temperature data and adjustment voltage are integrated into several groups of training data and test data; the artificial intelligence model is trained using the training data, and the trained model is tested using the test data to obtain the test accuracy; the model is optimized and adjusted according to the test accuracy to obtain a voltage adjustment model whose input is the target temperature and temperature data and whose output is the adjustment voltage.

[0051] This embodiment also discloses a method for controlling the tube wall temperature of a terahertz gas laser, comprising:

[0052] Step 1: Set the target temperature through the host computer and start the temperature control system. The main control cooler ZYNQ starts to collect the temperature data of the laser tube wall 1 and the ambient temperature in real time;

[0053] Step 2: Perform median filtering on the collected temperature data to reduce the impact of noise, perform linear fitting on the temperature data after median filtering to obtain the temperature change curve F(T), and calculate the slope k of the temperature data at the current time point in the temperature change curve F(T).

[0054] Step 3: Obtain the target correction temperature T1 through the formula T1=T0+u×k×h(Tn-Tw), and input the target correction temperature T1 and the current temperature data Tn into the trained voltage adjustment model to obtain the adjustment voltage;

[0055] Step 4: Use the adjustment voltage to drive the H-bridge circuit to adjust the output power of the semiconductor refrigeration element assembly, and the semiconductor refrigeration element assembly is cooled according to the adjustment voltage to control the temperature of the laser tube wall 1;

[0056] Step 5: The main control cooler ZYNQ continuously monitors the temperature data and ambient temperature, makes real-time adjustments based on the actual situation, and jumps to step 2.

[0057] In another embodiment, PID control may be added; specifically, after calculating the target correction temperature T1, the error value is calculated: e(t)=T1-Tn; a PID controller is set to determine the proportional coefficient KP, the integral coefficient Ki and the differential coefficient Kd, and the output of the PID controller is: Among them, u(t) is the control signal, that is, the output voltage, and e(t) is the error value; the output of the PID controller is used as the input of the voltage adjustment model to output the adjustment voltage. At this time, the output voltage u(t) needs to be introduced in the training process of the voltage adjustment model.

[0058] Part of the data in the above formula is calculated by removing the dimension and taking its numerical value. The formula is a formula closest to the actual situation obtained by software simulation of a large amount of collected data; the preset parameters and preset thresholds in the formula are set by technical personnel in this field according to actual conditions or through simulation of a large amount of data.

[0059] The above embodiments are only used to illustrate the technical method of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A terahertz gas laser tube wall temperature control system, characterized in that: include: Main control cooler ZYNQ, host computer and cooling module; The main control cooler ZYNQ is used to obtain temperature data of the laser tube wall (1) and the ambient temperature in real time; and to control the cooling module based on the ambient temperature and the temperature data; The host computer is used to set the target temperature; And, plotting the temperature data into a temperature change curve; The cooling module comprises: a plurality of semiconductor cooling plate assemblies arranged in a terahertz gas laser tube wall (1), a fixing fixture (2), and heat dissipation fins located at the upper and lower ends of the fixing fixture (2); the fixing fixture (2) is used to fix the semiconductor cooling plate assembly on the laser tube wall (1); the heat dissipation fins are used to absorb heat from the laser tube wall (1) and the hot end of the semiconductor cooling plate assembly and then dissipate heat by convection.

2. A terahertz gas laser tube wall temperature control system and control method according to claim 1, characterized in that: A PT1000 temperature sensor is also embedded in the fixing fixture (2). The PT1000 temperature sensor is used to measure the analog signal value of the laser tube wall (1) and convert it into temperature data through an A / D analog-to-digital converter and then send it to the main control cooler ZYNQ.

3. The terahertz gas laser tube wall temperature control system according to claim 1, characterized in that: The plurality of semiconductor refrigeration plate assemblies are distributed at intervals, and the interval distance is 20 cm.

4. The terahertz gas laser tube wall temperature control system according to claim 1, characterized in that: The semiconductor refrigeration plate assembly adjusts the voltage to the adjustment voltage through the H-bridge driving circuit.

5. A terahertz gas laser tube wall temperature control system according to claim 4, characterized in that: The controlling the cooling module based on the ambient temperature and the temperature data comprises: Extract the target temperature, temperature data and ambient temperature and mark them as T0, Tn and Tw respectively, adjust the target temperature T0 based on the temperature data Tn and ambient temperature Tw to obtain the target corrected temperature T1; The target corrected temperature T1 and the temperature data Tn are input into the voltage adjustment model to obtain the adjustment voltage; the power of the semiconductor refrigeration plate assembly is adjusted based on the adjustment voltage; wherein the voltage adjustment model is obtained based on the neural network model.

6. A terahertz gas laser tube wall temperature control system according to claim 5, characterized in that: The adjusting the target temperature T0 based on the temperature data Tn and the ambient temperature Tw includes: Perform linear fitting on the acquired temperature data Tn to obtain a temperature change curve F(T), and calculate the slope k of the temperature data at the current time point in the temperature change curve F(T); The target corrected temperature T1 is obtained by the calculation formula T1=T0+u×k×h(Tn-Tw); wherein h is the heat transfer coefficient and u is the correction coefficient.

7. A method for controlling the tube wall temperature of a terahertz gas laser, characterized in that: include: Step 1: Set the target temperature through the host computer and start the temperature control system. The main control cooler ZYNQ starts to collect the temperature data of the laser tube wall (1) and the ambient temperature in real time; Step 2: Perform median filtering on the collected temperature data to reduce the impact of noise, draw a temperature change curve based on the temperature data, and control the cooling module based on the ambient temperature and the temperature data.

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