A thermostat circuit suitable for SERF sensor lasers

Abstract

The utility model relates to a kind of constant-temperature circuit suitable for SERF sensor laser, including power supply, laser and FPGA, the output end of the power supply is connected with the input end of SERF sensor laser constant-temperature control unit, the input end of SERF sensor laser constant-temperature control unit is connected with the output end of FPGA, the control end of SERF sensor laser constant-temperature control unit is connected with the controlled end of laser.The utility model has the advantages of convenient debugging, low noise, high integration, temperature control precision and long-term stability, significantly improves the performance and reliability of SERF sensor laser constant-temperature control.

Description

Technical Field

[0001] This utility model relates to a temperature control circuit suitable for SERF sensor lasers. Background Technology

[0002] SERF (Spin Exchange Relaxation Free) sensors are a type of high-sensitivity magnetic field measurement device based on atomic spin characteristics. They have advantages such as high sensitivity under zero magnetic field, low noise, and high resolution, and have been widely used in high-end fields such as precision magnetic measurement, geomagnetic navigation, and medical imaging [1]. In such sensing systems, the operating temperature of the laser directly affects its output power, center wavelength, and spectral linewidth, thereby determining the detection accuracy and stability of the system. Therefore, to ensure the measurement reliability of SERF sensors, it is necessary to implement precise and stable closed-loop control of the laser operating temperature.

[0003] In recent years, researchers have conducted various explorations on temperature control of semiconductor lasers. For example, Zhang et al. proposed a high-precision temperature control system for semiconductor lasers used in atomic magnetometers, achieving milliKelvin-level temperature control [2]. This system uses an operational amplifier combined with a high-precision resistor and capacitor to form a fully analog PID control circuit, which can achieve high temperature control accuracy. However, this pure analog structure has a large number of components, high parameter matching requirements, and a complex debugging process, which is not conducive to system integration and industrial production. In addition, the temperature drift and tolerance between analog components can easily lead to temperature deviation during long-term operation, limiting the ability to further improve the temperature control stability.

[0004] On the other hand, while some control schemes employing digital PID algorithms offer good adjustment flexibility, their dynamic response and stability are still insufficient to meet the stringent requirements of SERF sensor lasers for temperature fluctuations of less than 0.01℃, limited by A / D and D / A conversion resolution and computational delay. Furthermore, such systems often require complex software calculations and multi-channel interfaces, resulting in complex and costly hardware implementation.

[0005] In summary, existing laser temperature control solutions generally suffer from the following problems: 1. High dependence on algorithms – requires the development and debugging of complex software, increasing system cost and complexity; 2. Extremely complex circuitry – Analog PID circuits typically require multi-stage operational amplifier units to implement the proportional, integral, and derivative components, along with numerous precision resistors and capacitors for parameter setting and stability compensation. The number of peripheral circuit components is enormous, and the circuit connections are complex.

[0006] 3. Noise and drift accumulation - Most circuits use DC-DC conversion for power supply, and the output ripple and noise are easily coupled to the TEC drive channel. In addition, the sampling noise of the digital computing system may be superimposed on the control signal, affecting the final control accuracy.

[0007] In view of the above-mentioned shortcomings, the designer actively researched and innovated in order to create a new type of temperature control circuit suitable for SERF sensor lasers, making it more valuable for industrial applications. Utility Model Content

[0008] To solve the above-mentioned technical problems, the purpose of this utility model is to provide a constant temperature circuit suitable for SERF sensor lasers.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A temperature control circuit suitable for SERF sensor lasers includes a power supply, a laser, and an FPGA. The output terminal of the power supply is connected to the input terminal of the SERF sensor laser temperature control unit, the input terminal of the SERF sensor laser temperature control unit is connected to the output terminal of the FPGA, and the control terminal of the SERF sensor laser temperature control unit is connected to the controlled terminal of the laser. The SERF sensor laser temperature control unit includes a DAC module, a voltage follower module, an analog PID temperature control module, and a voltage conversion and regulation module. The output terminal of the power supply is connected to the input terminal of the voltage conversion and regulation module. The output terminal of the voltage conversion and regulation module is connected to the input terminals of the DAC module, the voltage follower module, and the analog PID temperature control module. The input terminal of the DAC module is connected to the output terminal of the FPGA. The output terminal of the DAC module is connected to the input terminal of the voltage follower module. The output terminal of the voltage follower module is connected to the input terminal of the analog PID temperature control module. The output terminal of the analog PID temperature control module is connected to the input terminal of the laser.

[0010] Preferably, in the temperature control circuit suitable for SERF sensor lasers, the output terminal of the SERF sensor laser temperature control unit is connected to the input terminal of the temperature control indicator.

[0011] Preferably, in the temperature control circuit suitable for SERF sensor lasers, a thermistor for detecting the temperature inside the laser is connected inside the laser, and the thermistor of the laser is connected to the feedback terminal of the analog PID temperature control module.

[0012] Preferably, in the temperature control circuit suitable for SERF sensor lasers, the DAC module uses a DAC8552IDGKT chip.

[0013] Preferably, in the temperature control circuit suitable for SERF sensor lasers, the voltage follower module uses an OPA140 chip.

[0014] Preferably, in the constant temperature circuit suitable for SERF sensor lasers, the analog PID temperature control module uses a MAX1978ETM+T chip.

[0015] Preferably, in the temperature control circuit suitable for SERF sensor lasers, the voltage conversion and regulation module uses chip models including LT1963AES8#TRPBF and LT1963AEST-1.5#PBF. Among them, chip LT1963AES8#TRPBF outputs DC5V to the DAC module, voltage follower module, analog PID temperature control module, voltage conversion and regulation module, and chip LT1963AEST-1.5#PBF.

[0016] Preferably, in the aforementioned temperature control circuit suitable for SERF sensor lasers, the chip LT1963AEST-1.5#PBF is a fixed output DC1.5V LDO, which is connected to the DAC module as a reference voltage source.

[0017] Preferably, in the constant temperature circuit suitable for SERF sensor lasers, the output terminal of the analog PID temperature control module is connected to two indicator lights used to determine whether the temperature is high or low.

[0018] By means of the above solution, this utility model has at least the following advantages: 1. This utility model features a simplified circuit structure, small size, convenient debugging, and easy integration. By employing a highly integrated dedicated chip, this utility model replaces all the multi-stage operational amplifiers and numerous precision passive components required by traditional discrete analog PID controllers with internal modules. The number of external components is significantly reduced, wiring is simplified, and the circuit board area is greatly reduced, making it particularly suitable for installation in space-constrained magnetically shielded chambers. Parameter adjustment only requires setting an external resistor, making debugging simple and repeatable, which is beneficial for mass production and industrial application.

[0019] 2. This invention features low system noise, high temperature control accuracy, and high long-term stability. It optimizes the internal power supply filtering and current control loop of the chip, effectively suppressing power supply ripple and high-frequency noise. The control signal is processed entirely in the analog domain, eliminating the need for multiple analog-to-digital (ADC) / digital-to-analog (DAC) conversions and fundamentally eliminating quantization errors and asynchronous jitter caused by digital sampling. Internal integration shortens the signal path, reducing external interference and drift accumulation, enabling the temperature control system to maintain extremely low temperature fluctuations and high repeatability stability during long-term operation.

[0020] 3. This invention utilizes a highly integrated temperature control chip to replace the traditional digital PID and discrete analog PID control structures, avoiding technical problems such as high dependence on complex algorithms, complex circuit structures, and the impact of noise and drift on accuracy. This invention features simple circuitry, convenient debugging, low noise, high integration, high temperature control accuracy, and long-term stability, significantly improving the performance and reliability of SERF sensor laser temperature control.

[0021] The above description is only an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, the preferred embodiments of this utility model are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the principle of this utility model; Figure 2 This is the actual circuit diagram of the analog PID temperature control module of this utility model; Figure 3 This is the actual circuit diagram of the DAC module of this utility model; Figure 4 This is the actual circuit diagram of the voltage follower module of this utility model; Figure 5 This is the actual circuit diagram of the LT1963AES8 chip in the voltage conversion and regulation module of this utility model; Figure 6 This is the actual circuit diagram of the LT1963AEST chip in the voltage conversion and regulation module of this utility model. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0026] Example like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, a temperature control circuit suitable for SERF sensor lasers includes a power supply 1, a laser 2, and an FPGA 3. The output terminal of the power supply 1 is connected to the input terminal of the SERF sensor laser temperature control unit 4, the input terminal of the SERF sensor laser temperature control unit 4 is connected to the output terminal of the FPGA 3, and the control terminal of the SERF sensor laser temperature control unit 4 is connected to the controlled terminal of the laser 2. The SERF sensor laser temperature control unit 4 includes a DAC module 21, a voltage follower module 22, an analog PID temperature control module 23, and a voltage conversion and regulation module 24. The output terminal of the power supply 1 is connected to the input terminal of the voltage conversion and regulation module 24. The output terminal of the voltage conversion and regulation module 24 is connected to the input terminals of the DAC module 21, the voltage follower module 22, and the analog PID temperature control module 23. The input terminal of the DAC module 21 is connected to the output terminal of the FPGA 3. The output terminal of the DAC module 21 is connected to the input terminal of the voltage follower module 22. The output terminal of the voltage follower module 22 is connected to the input terminal of the analog PID temperature control module 23. The output terminal of the analog PID temperature control module 23 is connected to the input terminal of the laser 2.

[0027] In this embodiment, the output terminal of the SERF sensor laser temperature control unit 4 is connected to the input terminal of the temperature indicator light 5, which facilitates observation by the operator. Additionally, the analog PID temperature control module 23 is also connected to two indicator light output terminals. When the actual temperature is approximately 1°C higher or lower than the set temperature, the corresponding indicator light is illuminated, allowing the operator to easily assess the temperature status in real time.

[0028] In this embodiment, the DAC module 21 uses a DAC8552IDGKT chip; the voltage follower module 22 uses an OPA140 chip. This chip has the advantages of low cost and bandwidth that meets the system design requirements. It can maintain the stability and accuracy of the temperature setting signal during signal buffering and isolation, and provide a reliable voltage reference for subsequent driving and feedback circuits.

[0029] The analog PID temperature control module 23 uses a MAX1978ETM+T chip; the voltage conversion and regulation module 24 uses chips including LT1963AES8#TRPBF and LT1963AEST-1.5#PBF. The LT1963AES8#TRPBF chip outputs DC5V and outputs it to the DAC module 21, voltage follower module 22, analog PID temperature control module 23, voltage conversion and regulation module 24, and the LT1963AEST-1.5#PBF chip. The LT1963AEST-1.5#PBF chip is a fixed output DC1.5V LDO and is connected to the DAC module 21 as a reference voltage source.

[0030] In this embodiment, a thermistor for detecting the temperature inside the laser is connected inside the laser 2, and the thermistor of the laser 2 is connected to the feedback terminal of the analog PID temperature control module 23.

[0031] The working principle of this utility model is as follows: In the analog PID temperature control unit, the target temperature is set by an externally input adjustable voltage Vset, and the temperature detection signal from the thermistor inside the laser drives the internal TEC of the laser to achieve precise temperature regulation. The aforementioned Vset voltage is generated by a high-precision DAC unit controlled by an external FPGA (Field Programmable Gate Array), and buffered by a voltage follower module to ensure the stability of the set signal.

[0032] The DAC module uses the DAC8552IDGKT chip. This chip is a 16-bit digital-to-analog converter, which can fully guarantee the resolution and accuracy of the temperature setting signal, thereby achieving precise and reliable temperature control. The relationship between its output voltage Vset and the preset value X given to the DAC can be determined by formula (1).

[0033] Vset=X V DREF / (2 16 -1) (1) Among them, V DREF This refers to the reference voltage of the DAC module, which is set to 1.5V in this utility model.

[0034] The analog PID temperature control unit uses the MAX1978ETM+T chip. This chip has extremely high temperature control accuracy, with a control resolution of up to 0.001℃ and a maximum output current of ±3A. Furthermore, the output voltage and current limits can be flexibly configured via external circuitry, thereby improving the system's safety and adjustability.

[0035] like Figure 2 As shown, the maximum output voltage of this unit can be calculated by formula (2).

[0036] Vmax=4 V REF R5 / (R4+R5) (2) Vmax is the maximum output voltage set, and VREF is provided by the chip itself at 1.5V, which is set to 1.5V in this invention; The maximum output current is obtained from formula 3: Imax=V REF R2 / (R1+R2) / 10 / R8 (3) Imax is the maximum output current set, which is set to 735mA in this invention.

[0037] The analog PID controller is composed of capacitors C8, C9, and C15, resistors R17, R18, and R19, and an internal operational amplifier. The specific size is determined through debugging (those skilled in the art can debug it according to their needs).

[0038] During operation, the MAX1978ETM+T always maintains the same voltage levels at the FB+ and FB- pins. The FB+ pin receives the externally input temperature setting voltage Vset; the voltage VFB- at the FB- pin is obtained by a preset voltage divider structure using resistor R13 and the thermistor. The chip's operating logic is as follows: by adjusting the magnitude and direction of the output current, the temperature of the TEC is controlled, thereby changing the resistance of the thermistor, ultimately balancing the voltages at the FB+ and FB- pins. The value of VFB- can be obtained from Equation 4. V FB -= V REF RT / (R13+RT) (4) RT represents the magnitude of the thermistor, which is related to temperature T and determined by formula 5. RT = 10000 exp{3950 [1 / (T+273.15)-1 / 298.15]} (5) On the other hand, as explained earlier, the voltages of the FB+ and FB− pins remain consistent during normal chip operation, i.e., VFB−=Vset. Combining formulas (1), (4), and (5), the target temperature can be set and controlled by adjusting the value output by the FPGA. This eliminates the need for external MCU or FPGA to perform digital PID calculations, and also eliminates the need to write or debug temperature control software. Users can complete closed-loop temperature control through simple external parameter settings. This structure reduces the logical complexity and development time of the control system, and lowers costs.

[0039] The voltage conversion and regulation module includes the chips LT1963AES8#TRPBF and LT1963AEST-1.5#PBF. The LT1963AES8#TRPBF is an adjustable output LDO linear regulator. In this invention, the input voltage is 9V and the output voltage is 5V, providing a reliable and stable power supply for the MAX1978ETM+T chip, the DAC chip, the LT1963AEST-1.5#PBF chip, and the voltage follower module. The LT1963AEST-1.5#PBF is a fixed output 1.5V LDO, serving as the reference voltage source for the DAC chip. LDOs are chosen for their low output ripple, simple circuit structure, and ability to meet the stringent requirements of high-precision circuits for power supply noise and stability.

[0040] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0041] In the description of this application, it should be noted that the terms "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for 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. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0042] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or vertical, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0043] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" 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 connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0044] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A temperature control circuit suitable for SERF sensor lasers, comprising a power supply (1), a laser (2), and an FPGA (3), characterized in that: The output terminal of the power supply (1) is connected to the input terminal of the SERF sensor laser thermostatic control unit (4), the input terminal of the SERF sensor laser thermostatic control unit (4) is connected to the output terminal of the FPGA (3), and the control terminal of the SERF sensor laser thermostatic control unit (4) is connected to the controlled terminal of the laser (2). The SERF sensor laser temperature control unit (4) includes a DAC module (21), a voltage follower module (22), an analog PID temperature control module (23), and a voltage conversion and regulation module (24). The output terminal of the power supply (1) is connected to the input terminal of the voltage conversion and regulation module (24). The output terminal of the voltage conversion and regulation module (24) is connected to the input terminals of the DAC module (21), the voltage follower module (22), and the analog PID temperature control module (23). The input terminal of the DAC module (21) is connected to the output terminal of the FPGA (3). The output terminal of the DAC module (21) is connected to the input terminal of the voltage follower module (22). The output terminal of the voltage follower module (22) is connected to the input terminal of the analog PID temperature control module (23). The output terminal of the analog PID temperature control module (23) is connected to the input terminal of the laser (2).

2. The temperature control circuit for SERF sensor lasers according to claim 1, characterized in that: The output terminal of the SERF sensor laser thermostat control unit (4) is connected to the input terminal of the thermostat indicator (5).

3. The temperature control circuit for SERF sensor lasers according to claim 1, characterized in that: The laser (2) is internally connected to a thermistor for detecting the temperature inside the laser, and the thermistor of the laser (2) is connected to the feedback terminal of the analog PID temperature control module (23).

4. The temperature control circuit for SERF sensor lasers according to claim 1, characterized in that: The DAC module (21) uses a DAC8552IDGKT chip.

5. The temperature control circuit for SERF sensor lasers according to claim 1, characterized in that: The voltage follower module (22) uses an OPA140 chip.

6. The temperature control circuit for SERF sensor lasers according to claim 1, characterized in that: The analog PID temperature control module (23) uses a chip model of MAX1978ETM+T.

7. The temperature control circuit for SERF sensor lasers according to claim 1, characterized in that: The voltage conversion and regulation module (24) uses chips including LT1963AES8#TRPBF and LT1963AEST-1.5#PBF. Among them, chip LT1963AES8#TRPBF outputs DC5V to DAC module (21), voltage follower module (22), analog PID temperature control module (23), voltage conversion and regulation module (24), and chip LT1963AEST-1.5#PBF.

8. A temperature control circuit suitable for SERF sensor lasers according to claim 7, characterized in that: The chip LT1963AEST-1.5#PBF is a fixed output DC1.5V LDO and is connected to the DAC module (21) as a reference voltage source.

9. A temperature control circuit suitable for SERF sensor lasers according to claim 1, characterized in that: The output of the analog PID temperature control module (23) is connected to two indicator lights used to determine whether the temperature is high or low.

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