Closed-loop temperature compensation circuit and temperature compensation method for atomic magnetometer laser

Abstract

The application relates to the technical field of deep space exploration precise magnetic field measurement and sensors, and provides a closed-loop temperature compensation circuit and a temperature compensation method for an atomic magnetometer laser. The closed-loop temperature compensation circuit and the temperature compensation algorithm are provided, the shell temperature value of the laser unit is converted into a digital signal by an ADC unit and then transmitted to an FPGA controller unit, then the temperature compensation algorithm process is realized by the FPGA controller unit, the temperature compensation code value corresponding to the current shell temperature value is determined, the temperature compensation code value is added to the reference temperature point code value compensated by temperature to obtain a temperature correction code value, the temperature correction code value is transmitted to the laser unit through a second DAC unit and a TEC controller unit connected in series, and therefore the control parameters of the TEC controller can be dynamically adjusted under different temperature environments, the working parameters of the laser TEC are adjusted, and the output frequency stability of the laser is ensured.

Description

Technical Field

[0001] This application relates to the field of precision magnetic field measurement and sensor technology for deep space exploration, and in particular to a closed-loop temperature compensation circuit and temperature compensation method for an atomic magnetometer laser. Background Technology

[0002] An atomic magnetometer is a precision magnetic field measurement instrument based on quantum optics principles. It inverts the external magnetic field by detecting changes in the spin state of alkali metal atoms (such as rubidium atoms) within a gas chamber in a magnetic field. It boasts advantages such as high sensitivity, zero drift, and small size, and has become a core payload for achieving high-precision magnetic field measurements in fields such as deep space exploration and space physics research. In future deep space exploration missions, accurate observation and early warning of coronal mass ejection (CME) events are crucial scientific objectives. CMEs are among the largest energy release events in the solar system, and the powerful magnetic fields and charged particle streams they carry pose a serious threat to spacecraft safety, space weather, and even the Earth's electromagnetic environment. Accurately tracking the propagation trajectory and evolution of CMEs requires direct and precise measurement of their intrinsic magnetic field. The atomic magnetometer is a key technological means to achieve this goal.

[0003] As a core component in the field of precision magnetic field measurement and sensor technology for deep space exploration, the laser is a key part of the atomic magnetometer payload to achieve high-precision magnetic field detection, and its performance directly determines the measurement accuracy and reliability of the entire system. During the operation of the atomic magnetometer, the output frequency of the laser must be precisely locked near the specific electronic transition resonance line of the working medium (such as alkali metal atoms such as rubidium and cesium). Its frequency stability directly determines the magnetic field measurement accuracy and long-term operational reliability of the atomic magnetometer.

[0004] Currently, precision magnetic field measurement systems typically use distributed feedback lasers (DFB lasers) as the light source. However, the emission wavelength (i.e., output frequency) of these semiconductor lasers drifts with changes in ambient temperature. Specifically, the laser frequency increases as the ambient temperature rises and decreases as the ambient temperature falls. Testing revealed that the laser output frequency drift exhibits a linear relationship with ambient temperature changes, and this temperature sensitivity poses a significant technical challenge in practical applications. For example, in typical space exploration missions, the operating environment temperature may vary between 5°C and 60°C, causing the laser frequency to drift by as much as 20–30 GHz. Atomic magnetometers, on the other hand, require a frequency fluctuation range within ±2 GHz to function properly; otherwise, the system may malfunction. Summary of the Invention

[0005] In view of this, embodiments of this application provide a closed-loop temperature compensation circuit and a temperature compensation method for an atomic magnetometer laser, in order to solve the problems in the prior art where the atomic magnetometer laser may experience frequency drift when the ambient temperature changes, leading to inaccurate measurement results or even affecting the normal operation of the atomic magnetometer.

[0006] A first aspect of this application provides a closed-loop temperature compensation circuit for an atomic magnetometer laser, comprising:

[0007] The system includes a laser unit, an analog-to-digital converter (ADC) unit, a field-programmable gate array (FPGA) controller unit, a first digital-to-analog converter (DAC) unit, a second DAC unit, a thermoelectric cooler (TEC) controller unit, and a constant current source control circuit unit.

[0008] The ADC unit is configured to convert the shell temperature value of the laser unit into a digital signal and transmit it to the FPGA controller unit. The FPGA controller unit determines the temperature compensation code value based on the shell temperature value through a temperature compensation algorithm, and adds the temperature compensation code value to the reference temperature point code value of the temperature compensation correction to obtain the temperature correction code value. The temperature correction code value is then transmitted to the laser unit through the second DAC unit and the TEC controller unit connected in series.

[0009] The FPGA controller unit is also configured to determine the laser operating current code value and transmit the laser operating current code value to the laser unit via a first DAC unit and a constant current source control circuit unit connected in series.

[0010] A second aspect of this application provides a closed-loop temperature compensation method for an atomic magnetometer laser, the method being executed by the circuit in the first aspect; the method includes:

[0011] The ADC unit obtains the case temperature value of the laser unit, converts the case temperature value into a digital signal, and then transmits it to the FPGA controller unit.

[0012] The FPGA controller unit determines the temperature compensation code value based on the case temperature value using a temperature compensation algorithm. It adds the temperature compensation code value to the reference temperature point code value for temperature compensation correction to obtain the temperature correction code value, and transmits the temperature correction code value to the TEC controller unit to control the laser unit to emit light at the target frequency. The target frequency is the output frequency of the laser when the TEC inside the laser unit is operating at the target temperature point.

[0013] A third aspect of this application provides an electronic device including a memory, a ground processor, and an on-orbit processor. The memory stores a computer program, and the ground processor and the on-orbit processor execute the computer program to implement the steps of the above-described method.

[0014] The beneficial effects of this application's embodiments compared to the prior art are as follows: The closed-loop temperature compensation circuit provided in this application's embodiments is used to achieve stable control of the laser output frequency. Its operation consists of two stages:

[0015] The first stage involves initial calibration and operating point setting: First, the laser's output frequency is precisely tuned to the target frequency, which can be the target atomic resonance frequency, i.e., the laser's operating frequency. During this process, two core preset parameters are adjusted and ultimately determined: one is a fixed operating current code value to achieve the required optical power, and the other is a reference temperature code value to stabilize the laser temperature at the target frequency. These two code values ​​together define the stable operating point of the laser under standard conditions.

[0016] The second stage involves dynamic temperature compensation during operation: In actual operation, the output frequency of the laser unit is affected by the ambient temperature, meaning the laser output frequency drifts with the ambient temperature. The ADC unit monitors the case temperature of the laser unit in real time and converts it into a digital signal, which is then transmitted to the FPGA controller unit. Based on this digital case temperature signal, the FPGA controller unit calculates a temperature compensation code value at that case temperature (i.e., the ambient temperature). This temperature compensation code value is compared with the reference temperature point code value. The values ​​are added together to form a new temperature correction code value, which is transmitted to the TEC controller unit via a second DAC unit connected in series, dynamically adjusting the heating or cooling power of the TEC. During this process, the laser's operating current code value remains unchanged at the preset fixed value.

[0017] By employing the above methods, this system can effectively counteract the influence of ambient temperature changes on the laser chip temperature by dynamically fine-tuning the target temperature of the TEC while maintaining a constant laser drive current. This ensures that the laser output light frequency remains stable near the initially set target atomic resonance frequency over a long period of time. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the closed-loop temperature compensation circuit of an atomic magnetometer laser provided in an embodiment of this application.

[0020] Figure 2 This is a schematic diagram illustrating the working principle of the TEC controller circuit provided in the embodiments of this application.

[0021] Figure 3 This is a schematic flowchart of a closed-loop temperature compensation method for an atomic magnetometer laser provided in an embodiment of this application.

[0022] Figure 4 This is a flowchart illustrating the method for determining a temperature correction code value based on a case temperature value by an FPGA controller unit according to an embodiment of this application.

[0023] Figure 5 This is a flowchart illustrating the method for determining a piecewise calibration function using a temperature compensation algorithm, as provided in an embodiment of this application.

[0024] Figure 6 This is a schematic diagram of a temperature monitoring circuit provided in an embodiment of this application.

[0025] Figure 7 This is a schematic diagram of the fitting function obtained through software simulation provided in the embodiments of this application.

[0026] Figure 8 This is a schematic diagram showing the test results of the frequency of the first laser unit provided in this application changing with the environment.

[0027] Figure 9 This is a schematic diagram showing the test results of the frequency of the second laser unit provided in this application changing with the environment.

[0028] Figure 10 This is a schematic diagram of the electronic device provided in the embodiments of this application. Detailed Implementation

[0029] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0030] The following will describe in detail, with reference to the accompanying drawings, a closed-loop temperature compensation circuit and a temperature compensation method for an atomic magnetometer laser according to an embodiment of this application.

[0031] As mentioned above, the output frequency of a semiconductor laser will drift with changes in ambient temperature. Traditional temperature control schemes mainly have the following technical limitations: they use open-loop or simple proportional-integral-derivative (PID) feedback control, which can only maintain the laser's operation within a relatively narrow range of ambient temperature; they do not consider the direct impact of ambient temperature changes on the laser frequency; and they lack a dynamic compensation mechanism for ambient temperature fluctuations.

[0032] In extreme temperature environments such as deep space exploration, the shortcomings of this traditional temperature control scheme are particularly evident. When a satellite experiences alternating periods of sunlight and shadow, drastic temperature changes can cause the laser frequency to deviate significantly from its operating point, rendering the atomic magnetometer inoperable. Furthermore, in mobile platform applications such as vehicle-mounted and airborne systems, rapid fluctuations in ambient temperature can also significantly reduce the reliability of the measurement system.

[0033] In summary, to address the shortcomings of existing technologies and ensure the stable operation of atomic magnetometers in complex thermal environments, thereby providing high-precision magnetic field data for the study of key scientific phenomena such as coronal mass ejections in deep space exploration, it is urgent to develop an efficient closed-loop temperature compensation system to provide accurate dynamic environmental temperature compensation for semiconductor lasers.

[0034] The system should have the following key functions:

[0035] 1) Capable of real-time monitoring of ambient temperature changes;

[0036] 2) Capable of dynamically adjusting the control parameters of the laser TEC;

[0037] 3) The laser output frequency can be stably controlled within the typical operating bandwidth (e.g., ±2 GHz) required for the target atomic resonance line (such as the D1 line of rubidium atom, the D1 line of cesium atom, etc.);

[0038] 4) Adaptable to working environments ranging from 5℃ to +60℃ and even wider temperature ranges.

[0039] Therefore, this application provides a closed-loop temperature compensation circuit for an atomic magnetometer laser, used to achieve stable control of the laser output frequency. Its operation consists of two stages:

[0040] The first stage involves initial calibration and operating point setting: First, the laser's output frequency is precisely tuned to the target frequency, which can be the target atomic resonance frequency, i.e., the laser's operating frequency. During this process, two core preset parameters are adjusted and ultimately determined: one is a fixed operating current code value to achieve the required optical power, and the other is a reference temperature code value to stabilize the laser temperature at the target frequency. These two code values ​​together define the stable operating point of the laser under standard conditions.

[0041] The second stage involves dynamic temperature compensation during operation: In actual operation, the output frequency of the laser unit is affected by the ambient temperature, meaning the laser output frequency drifts with the ambient temperature. The ADC unit monitors the case temperature of the laser unit in real time and converts it into a digital signal, which is then transmitted to the FPGA controller unit. Based on this digital case temperature signal, the FPGA controller unit calculates a temperature compensation code value at that case temperature (i.e., the ambient temperature). This temperature compensation code value is compared with the reference temperature point code value. The values ​​are added together to form a new temperature correction code value, which is transmitted to the TEC controller unit via a second DAC unit connected in series, dynamically adjusting the heating or cooling power of the TEC. During this process, the laser's operating current code value remains unchanged at the preset fixed value.

[0042] By employing the above methods, this system can effectively counteract the influence of ambient temperature changes on the laser chip temperature by dynamically fine-tuning the target temperature of the TEC while maintaining a constant laser drive current. This ensures that the laser output light frequency remains stable near the initially set target atomic resonance frequency over a long period of time.

[0043] Figure 1 This is a schematic diagram of the closed-loop temperature compensation circuit of an atomic magnetometer laser provided in an embodiment of this application. Figure 1 As shown, the circuit includes: a laser unit, an ADC unit, an FPGA controller unit, a first DAC unit (DAC1), a second DAC unit (DAC2), a TEC controller unit, and a constant current source control circuit unit.

[0044] In some examples, the laser unit can be a distributed feedback laser whose output wavelength matches the target alkali metal atomic resonance line, for example, a 795nm laser.

[0045] The 795nm laser unit is the core component of the atomic magnetometer sensor. When the working medium is rubidium atoms, its output wavelength is precisely matched to the D1 line of rubidium atoms near 795 nm. The 795nm laser acts as a light source to irradiate the alkali metal atom gas in the atomic magnetometer's chamber, polarizing its electron spin. The polarized alkali metal atoms undergo coherent precession under the influence of an external magnetic field. Photoelectric detection of the macroscopic magnetic moment of the alkali metal atoms extracts information about the magnetic field being measured. In the experimental testing, both domestically packaged and imported 795nm lasers were tested. The tests revealed that the laser's output frequency changes with ambient temperature.

[0046] The ADC unit is configured to convert the case temperature value of the laser unit into a digital signal and transmit it to the FPGA controller unit. The FPGA controller unit determines the temperature compensation code value based on the case temperature value using a temperature compensation algorithm, and compares the temperature compensation code value with the reference temperature point code value for temperature compensation correction. The temperature correction code value is obtained by adding the two values ​​together. The temperature correction code value is then transmitted to the laser unit via the second DAC unit and the TEC controller unit connected in series.

[0047] The FPGA controller unit is also configured to determine the laser operating current code value and transmit the laser operating current code value to the laser unit via a first DAC unit and a constant current source control circuit unit connected in series.

[0048] The laser operating current code value can be determined based on the target frequency of the laser unit. That is, if the laser unit is required to emit light at a target frequency, the corresponding constant current source current can be determined. The FPGA controller unit transmits the current code value corresponding to the determined constant current source current to the constant current source control circuit unit via the first DAC unit. The constant current source control circuit unit then controls the laser unit's LD chip to emit light based on this current code value. Furthermore, when the ambient temperature changes, causing a change in the laser unit's casing temperature, the laser unit's output frequency may drift, meaning the frequency of the emitted light will deviate from the target frequency.

[0049] Therefore, the FPAG controller unit can determine the temperature compensation code based on the real-time acquired shell temperature value, and then use this temperature compensation code and the reference temperature point code value. The sum, which is the temperature correction code value, is transmitted to the laser unit via the second DAC unit and the TEC controller unit connected in series to achieve temperature compensation.

[0050] In other words, the ADC unit, FPGA controller unit, DAC2 unit and TEC controller unit can be connected in sequence, and the FPGA controller unit, DAC1 unit and constant current source control circuit unit can also be connected in sequence.

[0051] The ADC unit converts the acquired real-time laser housing temperature value, i.e., the analog signal reflecting the ambient temperature, into a digital signal and transmits it to the FPGA controller unit. The FPGA controller unit performs feedback calculations based on the laser housing temperature value to obtain a temperature compensation code value for TEC temperature compensation, and then compares this temperature compensation code value with the reference temperature point code value. The sum of these values, which is the temperature correction code value, is transmitted to the DAC2 unit. The DAC2 unit converts the received temperature correction code value into an analog signal and outputs it to the TEC controller unit. The TEC controller unit heats or cools the TEC inside the laser based on the received analog temperature correction code value signal, thereby controlling the laser unit to emit light at the target frequency.

[0052] Simultaneously, the FPGA controller unit transmits the preset laser operating current code value to the DAC1 unit. The DAC1 unit converts the received laser operating current code value into an analog signal and outputs it to the constant current source control circuit. The constant current source control circuit unit outputs current to the laser diode (LD) chip inside the laser based on the received analog signal.

[0053] According to the technical solution provided in the embodiments of this application, the closed-loop temperature compensation circuit of the atomic magnetometer laser can first perform initial calibration and operating point setting to determine the fixed operating current code value that enables the laser to achieve the required optical power and the reference temperature code value that stabilizes the laser temperature at the target frequency. These two code values ​​are used together to define the stable operating point of the laser under standard conditions. Then, dynamic temperature compensation is performed during operation. The ADC unit monitors the laser unit's housing temperature in real time and converts it into a digital signal, which is transmitted to the FPGA controller unit. The FPGA controller unit determines the temperature compensation code value based on the housing temperature value and compares this temperature compensation code value with the reference temperature point code value. The summation results in a temperature correction code value that is transmitted to the laser unit via a second DAC unit and a TEC controller unit connected in series. This enables the laser unit to achieve temperature compensation, thereby realizing the dynamic adjustment of the laser TEC control parameters under different temperature environments and ensuring the stability of the laser output frequency.

[0054] In some embodiments of this application, the laser unit physically integrates an LD, a TEC, and a high-precision temperature sensor; wherein:

[0055] An LD is an active device that generates laser light of a preset wavelength. It achieves stimulated light by injecting a specific driving current into the LD; the frequency of its output light will vary with the temperature of the die and the injected current.

[0056] The TEC is a thermoelectric cooler that is installed close to the LD. Driven by the TEC controller, it can bidirectionally adjust the direction and magnitude of the current flowing through the TEC inside the laser, thereby achieving precise heating or cooling of the LD. It is the core actuator for active temperature control.

[0057] The high-precision temperature sensor is an NTC thermistor, arranged close to the LD, used to monitor the instantaneous temperature of the LD in real time with high precision, and convert the temperature change into a measurable resistance or voltage signal, serving as the key feedback for the closed-loop temperature control system.

[0058] The above three parts are structurally tightly integrated and encapsulated to form a complete laser module capable of active and precise temperature control. Its core working principle is as follows: the temperature of the LD is sensed in real time by an NTC thermistor and fed back to the TEC controller. Based on the deviation between this feedback signal and the preset target temperature, the TEC controller dynamically adjusts the current applied to the TEC using a preset control algorithm to quickly offset the disturbances caused by internal heating and changes in ambient temperature, thereby stabilizing the temperature of the LD within a preset range near the set value. Temperature stability directly ensures the long-term stability of the laser's output light frequency, ensuring that it accurately and continuously acts on the target alkali metal atomic resonance line, providing the necessary light source conditions for the atomic magnetometer to achieve high-precision magnetic field measurement.

[0059] The preset control algorithm can be selected according to actual needs, such as the proportional-integral-derivative (PID) control algorithm.

[0060] In some embodiments of this application, the atomic magnetometer laser internally includes an LD, a TEC thermoelectric cooler, and a negative temperature coefficient (NTC) thermistor. The LD emits light by applying a current; the TEC thermoelectric cooler is controlled by a TEC controller to heat or cool the TEC, thus ensuring a stable TEC temperature; and the NTC thermistor is used to monitor the temperature of the LD inside the laser.

[0061] In some embodiments of this application, the ADC unit can be an ADC acquisition circuit. The analog signal input terminal of the ADC is connected to the thermistor terminal attached to the laser housing, and the digital signal output terminal is connected to one end of the FPGA controller. It is mainly used to acquire the housing temperature of the laser to reflect changes in the ambient temperature.

[0062] The DAC2 unit can be a DAC feedback circuit. DAC2 converts the digital signal transmitted from the FPGA controller unit into an analog signal and transmits it to the TEC controller unit, thereby controlling the temperature of the TEC inside the laser. By changing the temperature of the TEC inside the laser, the output frequency of the laser can be changed.

[0063] In some embodiments of this application, the TEC controller unit is a single-chip temperature controller for controlling the internal TEC temperature of the atomic magnetometer laser, which internally consists of a PID controller composed of a chopper self-stabilizing instrumentation amplifier and a high-precision integrating amplifier.

[0064] Figure 2 This is a schematic diagram illustrating the working principle of the TEC controller unit provided in an embodiment of this application. Figure 2 As shown, the output of the TEC controller unit is connected to the NTC thermistor integrated inside the laser unit and the TEC inside the laser unit, respectively, forming a closed-loop temperature control circuit.

[0065] The TEC controller unit acquires the voltage signal from the NTC thermistor, which characterizes the actual operating temperature of the laser, in real time, and compares it with the target temperature value to obtain a temperature error signal. This target temperature value can be the voltage signal of the target temperature.

[0066] The temperature error signal is input into the control algorithm (such as PID control algorithm) integrated into the TEC controller to generate a real-time dynamic control signal; the dynamic control signal drives the TEC controller unit to precisely adjust the magnitude and direction of the current applied to the TEC, thereby achieving heating or cooling of the LD.

[0067] As the core processing and control unit of the closed-loop temperature compensation circuit, the FPGA controller unit outputs the corresponding temperature correction code value to the TEC controller unit through the second DAC unit connected in series, based on the preset temperature target value.

[0068] In some embodiments of this application, the constant current source control circuit unit is connected to the LD chip inside the laser unit; the constant current source control circuit unit receives the laser operating current code value, controls the current of the LD chip based on the laser operating current code value, and then controls the laser unit to emit light.

[0069] In other words, the DAC1 unit can be a DAC feedback circuit. DAC1 converts the digital signal transmitted by the FPGA controller unit into an analog signal, thereby setting the current of the constant current source control circuit. The output of the constant current source circuit is connected to the input of the LD chip inside the laser, thus controlling the current flowing through the LD chip inside the laser. By working simultaneously with the TEC temperature setting module inside the laser, it ultimately controls the laser to emit a signal of a specific frequency, which is coupled into an optical fiber and transmitted to the atomic magnetometer chamber for operation.

[0070] In some embodiments of this application, the ADC unit can be connected to the FPGA controller unit through the Serial Peripheral Interface (SPI) interface to convert the acquired laser housing temperature into an analog-to-digital value and output it to the FPGA controller unit.

[0071] The DAC2 unit can connect to the FPGA controller unit via the SPI interface, convert the received laser temperature compensation values ​​from digital to analog and output them to the TEC controller unit.

[0072] The DAC1 unit can be connected to the FPGA controller unit via the SPI interface, and convert the code value corresponding to the received laser current into a digital-to-analog converter and output it to the constant current source control circuit unit.

[0073] In some embodiments of this application, the FPGA controller unit is mainly used for controlling peripheral hardware circuits, including the control of DAC1 unit, DAC2 unit, and ADC unit. Specifically, the control of DAC1 unit can be achieved through a DAC1 current control module, and the control of DAC2 unit can be achieved through a DAC2 temperature control module. The control signal of the DAC2 temperature control module is calculated by the FPGA controller based on the output of the ADC acquisition control module using a temperature compensation algorithm control module.

[0074] The temperature compensation algorithm works by sensing changes in ambient temperature when the laser casing changes, thus affecting the temperature of the internal TEC (Thermal Control Unit) and consequently altering the laser's output frequency. This algorithm monitors the ambient temperature using an NTC thermistor attached to the laser casing. When the NTC thermistor detects a temperature change, the algorithm calculates the required compensation temperature for the TEC controller unit, adjusts the DAC2 unit's settings to change the heating or cooling current of the TEC controller, and ultimately compensates the laser's output frequency to the operating frequency of the atomic magnetometer laser.

[0075] The technical solution of this application is mainly used for the laser in an atomic magnetometer, primarily for applications such as deep space exploration and aerospace. Therefore, the temperature difference during on-orbit operation may be significant, causing changes in the laser's output frequency due to variations in ambient temperature. Experimental analysis revealed a linear relationship between the laser's output frequency and ambient temperature. Therefore, this application proposes a temperature compensation algorithm. This algorithm calculates how much the TEC code value needs to be compensated for when the ambient temperature (i.e., the ambient temperature measured from the laser casing) changes, thereby fine-tuning the laser's output frequency and making the atomic magnetometer more stable.

[0076] Figure 3This is a schematic flowchart illustrating a closed-loop temperature compensation method for an atomic magnetometer laser provided in an embodiment of this application. Figure 3 As shown, the method includes the following steps:

[0077] In step S301, the ADC unit obtains the shell temperature value of the laser unit, converts the shell temperature value into a digital signal, and transmits it to the FPGA controller unit.

[0078] In step S302, the FPGA controller unit determines the temperature compensation code value based on the case temperature value through a temperature compensation algorithm, adds the temperature compensation code value to the reference temperature point code value for temperature compensation correction to obtain the temperature correction code value, and transmits the temperature correction code value to the TEC controller unit to control the laser unit to emit light at the target frequency.

[0079] The target frequency is the output frequency of the laser when the TEC inside the laser unit operates at the target temperature point.

[0080] In some embodiments of this application, the method can be... Figure 1 The circuit in the illustrated embodiment is executed.

[0081] In some embodiments of this application, the ADC unit can acquire the case temperature value of the laser unit, convert the case temperature value into a digital signal, and transmit it to the FPGA controller unit. The FPGA controller unit determines a temperature compensation code value based on the case temperature value using a temperature compensation algorithm, adds the temperature compensation code value to the reference temperature point code value for temperature compensation correction to obtain a temperature correction code value, and transmits the temperature correction code value to the TEC controller unit to control the laser unit to emit light at the target frequency.

[0082] Figure 4 This is a flowchart illustrating the method for determining a temperature correction code value based on a case temperature value using an FPGA controller unit according to an embodiment of this application. Figure 4 As shown, the method includes the following steps:

[0083] In step S401, the segmented calibration function is determined by calibrating using a temperature compensation algorithm.

[0084] The segmented calibration function is used to characterize the temperature compensation code value under different temperature ranges.

[0085] In step S402, the temperature range matched in the segmented calibration function is determined based on the shell temperature value, and then the target temperature compensation code value is determined.

[0086] In step S403, the sum of the reference temperature code value and the target temperature compensation code value is determined as the temperature correction code value.

[0087] In some embodiments of this application, when the FPGA controller unit determines the temperature correction code value based on the case temperature value, it can first determine the segmented calibration function through temperature compensation algorithm calibration, then determine the matching temperature range in the segmented calibration function based on the case temperature value, and then determine the target temperature compensation code value. Finally, the sum of the reference temperature point code value and the target temperature compensation code value is determined as the temperature correction code value.

[0088] The reference temperature value for temperature compensation correction is recorded as follows: The target temperature compensation code value is recorded as Then the temperature correction code value for: .

[0089] Figure 5 This is a flowchart illustrating the method for determining a piecewise calibration function using a temperature compensation algorithm, as provided in an embodiment of this application. Figure 5 As shown, the method includes the following steps:

[0090] In step S501, the proportional relationship K1 between the output frequency drift of the laser unit and the change in the shell temperature of the laser unit is calibrated.

[0091] In step S502, the ratio K2 of the laser unit frequency change to the minimum change in the code value of the second DAC unit is calibrated within the range of the preset reference temperature point extension.

[0092] In step S503, the operating frequency of the laser unit is determined, and the reference temperature point for temperature compensation correction and the current reference operating point of the first DAC unit are obtained.

[0093] Among them, the reference temperature point for temperature compensation correction is the operating temperature point of the TEC inside the laser at room temperature, and the current reference operating point of the first DAC unit is the operating current of the LD inside the laser at room temperature.

[0094] In step S504, the case temperature of the laser unit is detected by a temperature monitoring circuit, and the drift of the laser unit is determined based on the case temperature.

[0095] The drift is the difference between the shell temperature value and the ambient temperature reference point. The product of the difference and K1. For example, the ambient temperature reference point. The temperature was 25℃, the temperature collected from the shell was 30℃, the temperature difference was 5℃, and the frequency drift was 5×K1.

[0096] In step S505, the ratio of the drift amount to K2 is determined to be the temperature compensation code value that needs to be compensated.

[0097] In step S506, a function is constructed using the voltage value collected by the ADC unit and converted into a digital signal as the independent variable and the temperature compensation code value as the dependent variable. The function is then piecewise fitted to obtain a piecewise calibration function.

[0098] In some embodiments of this application, the proportional relationship K1 between the output frequency drift of the laser unit and the change in the shell temperature of the laser unit can be calibrated first, and a preset ambient temperature reference point can be used. The ratio K2 between the frequency change of the calibrated laser unit and the minimum change in the code value of the second DAC unit within the extended range. Wherein, the ambient temperature reference point... It is a pre-set temperature reference point based on the current test environment for calculating the shell temperature drift.

[0099] K2 can be achieved by calibrating the ratio of the laser unit frequency change to the ratio of the Least Significant Bit (LSB) of DAC2 set by TEC. Its extended range can be set according to actual needs, for example, it can be set to a range of 25℃±3℃, and there is no limit here.

[0100] The DAC unit code value refers to the digital code value input to the DAC to represent a specific analog output. It is determined based on the DAC's reference voltage, the specific analog output voltage to be output, and the DAC's resolution.

[0101] In some embodiments of this application, it is also necessary to determine the operating frequency of the laser unit, obtain the reference temperature point for temperature compensation correction, and the current reference operating point of the first DAC unit.

[0102] In some examples, once the case temperature of the laser unit is determined to be stable, the operating current value of the LD chip in the laser unit and the operating temperature of the TEC can be adjusted to enable the laser unit to output a target frequency signal, thereby determining the reference temperature point for TEC temperature compensation correction when the target frequency signal is output.

[0103] In some embodiments of this application, determining the reference temperature point for temperature compensation correction of the laser unit may include: in response to determining that the case temperature of the laser unit is stable, that is, under the condition that the ambient temperature remains unchanged, adjusting the operating current value of the LD chip in the laser unit and the operating temperature of the TEC to make the laser unit emit light at the target frequency; and determining the operating temperature of the TEC of the laser unit when emitting light at the target frequency as the reference temperature point for temperature compensation correction.

[0104] In some embodiments of this application, the range of code values ​​for temperature compensation can also be determined based on the digital signal obtained by converting the voltage value collected by the ADC unit. For example, in a test experiment, the ADC unit acquired... The value range is [520: 2400], where The temperature range measured at the thermistor of the corresponding laser housing is [-0.3℃ : +65.5℃]. During use, the ADC code value range can be widened according to the actual ambient temperature range on track.

[0105] In some embodiments of this application, the case temperature of the laser unit can also be detected by a temperature monitoring circuit, and the drift of the laser unit can be determined based on the case temperature.

[0106] Figure 6 This is a schematic diagram of a temperature monitoring circuit provided in an embodiment of this application. It employs, for example... Figure 6 When the temperature monitoring circuit shown detects the case temperature of the laser unit, the resistance value of the thermistor for the case temperature of the laser unit can be obtained as follows:

[0107] ;

[0108] in, The resistance value of the thermistor is the case temperature. This refers to the resistance value of the voltage divider resistor in the temperature monitoring circuit. This is the reference voltage code value for the ADC unit. This is the reference voltage for the temperature monitoring circuit. The number of bits in the ADC unit. This is the code value after the ADC unit converts the acquired voltage value into a digital signal.

[0109] Furthermore, the shell temperature value can be calculated and determined using the B-value method based on the resistance value of the shell temperature thermistor:

[0110] ;

[0111] in, This is the shell temperature value. The temperature coefficient of the thermistor, The resistance value of the thermistor at 25℃ is the laser housing temperature.

[0112] Finally, the drift of the laser unit was determined. for: .

[0113] In some embodiments of this application, it can be based on Determine the target temperature compensation code value that needs to be corrected. for: .

[0114] In some embodiments of this application, a function is constructed using the code value of the voltage value acquired by the ADC unit and converted into a digital signal as the independent variable and the temperature compensation code value as the dependent variable. A piecewise fitting is then performed on this function to obtain a piecewise calibration function. Piecewise fitting can be implemented using simulation software. In one example, if the fitting function obtained through software simulation is as follows... Figure 7 As shown, an example of a piecewise calibration function could be:

[0115] ;

[0116] in, , and The coefficients are those of the fitted function. , and The intercept of the fitted function, and These are the piecewise points for fitting the function.

[0117] Furthermore, the piecewise fitting function described above can be transformed into a multinomial fitting function, which can improve the fitting accuracy and further reduce the compensation error. Moreover, the multinomial fitting function has been applied in actual tests, and the test results show that the laser output frequency is controlled within ±1GHz.

[0118] The reference temperature value for temperature compensation correction is recorded as follows: The target temperature compensation code value is recorded as Then the temperature correction code value for: The temperature correction code value is transmitted through the FPGA control unit. The second DAC unit and the TEC controller unit, connected in series, transmit the data to the laser unit, thereby ultimately correcting the laser's frequency output.

[0119] To verify the effectiveness of the method provided in the embodiments of this application, the frequency changes of the two laser units with ambient temperature were tested respectively.

[0120] Figure 8 This is a schematic diagram illustrating the test results of the frequency of the first laser unit provided in this application changing with the environment. The horizontal axis represents time in minutes (min), the left vertical axis represents laser frequency drift in GHz, and the right vertical axis represents laser housing temperature in degrees Celsius (°C). The curve to the left of the dashed line shows the relationship between laser frequency drift and temperature without temperature compensation, while the curve to the right shows the relationship between laser frequency drift and temperature after temperature compensation. The red curve represents laser frequency drift, and the blue curve represents laser housing temperature.

[0121] like Figure 8As shown, before temperature compensation of the laser housing, the frequency of the first laser changes with ambient temperature by 0.5 GHz / ℃ (26 GHz @ 5~60℃). This frequency change directly causes the atomic magnetometer to malfunction. After temperature compensation algorithm feedback, the frequency of the first laser changes with ambient temperature by less than 2.1 GHz @ 5~60℃ (the ambient temperature change rate during testing was 2℃ / min). The frequency stability is directly improved by an order of magnitude, confirming the effectiveness of the method provided in this application embodiment.

[0122] Figure 9 This is a schematic diagram illustrating the test results of the frequency of the second laser unit provided in this application changing with the environment. The horizontal axis represents time in minutes (min), the left vertical axis represents the laser frequency in GHz, and the right vertical axis represents the laser housing temperature in °C. The solid red line in the figure is the laser frequency compensation curve with a 0-second delay, the dashed black line is the laser frequency compensation curve with a 30-second delay, the blue line represents the laser housing temperature, and the laser frequency corresponding to the red dashed line is 377107.5 GHz.

[0123] like Figure 9 As shown, the test results indicate that the frequency of the second laser changes with ambient temperature by 0.2 GHz / ℃ (11 GHz @ 5~60℃). Furthermore, two tests were conducted on the second laser: 0-second compensation and 30-second delay compensation. A delay compensation design was added in the step of transmitting the temperature compensation code value to the TEC controller unit via the second DAC unit. Specifically, after the ADC unit collects the current laser housing temperature data, it obtains the TEC temperature value that the DAC2 unit needs to feed back through the temperature compensation algorithm, and then activates temperature compensation after 30 seconds. The test results show that without delay compensation (0-second delay, red line), the frequency of the second laser changes with ambient temperature by less than 1.1 GHz @ 5~60℃ (the ambient temperature change rate during the test was 2℃ / min). With delay compensation (30-second delay, black line), the frequency of the second laser changes with ambient temperature by less than 0.72 GHz @ 5~60℃ (the ambient temperature change rate during the test was 2℃ / min). Therefore, in actual operation, the temperature compensation code value can also be delayed so that it is transmitted to the TEC controller unit via the second DAC unit after a preset delay.

[0124] The technical solution provided in this application adopts a closed-loop temperature compensation system and temperature compensation algorithm. A laser shell temperature acquisition module is added to the hardware system, and a temperature compensation algorithm and delay compensation design are added to the FPGA controller to compensate for the laser output frequency. This ensures that the laser output frequency does not change by more than 3GHz@5~60℃ within the ambient temperature range of 5℃~60℃, thereby ensuring that the atomic magnetometer can work stably and effectively in orbit for a long time.

[0125] All of the above-mentioned optional technical solutions can be combined in any way to form the optional embodiments of this application, and will not be described in detail here.

[0126] Figure 10 This is a schematic diagram of the electronic device provided in an embodiment of this application. For example... Figure 10 As shown, the electronic device 10 of this embodiment includes: a processing unit 1001, a storage unit 1002, and a computer program 1003 stored in the storage unit 1002 and executable on the processing unit 1001.

[0127] The processing unit 1001 may include a ground processing unit and an on-orbit processing unit. When the ground processing unit and the on-orbit processing unit execute the computer program 1003, they implement the steps in the various method embodiments described above. Alternatively, when the ground processing unit and the on-orbit processing unit execute the computer program 1003, they implement the functions of each module / unit in the various device embodiments described above.

[0128] In some implementations, the steps of calibrating the closed-loop temperature compensation circuit of the aforementioned atomic magnetometer laser (e.g., calibrating coefficients K1 and K2) and performing piecewise function fitting can be implemented by a computer program executed by a ground processing unit; while the steps of calculating the temperature correction code value based on real-time temperature measurement and transmitting the temperature correction code value to the laser unit through a second DAC unit and a TEC controller unit connected in series to achieve on-orbit real-time temperature compensation can be implemented by a computer program executed by an on-orbit processor.

[0129] Those skilled in the art will understand that Figure 10 This is merely an example of electronic device 10 and does not constitute a limitation on electronic device 10. It may include more or fewer components than shown, or different components.

[0130] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0131] If an integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program may include computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. A computer-readable medium may include: any entity or device capable of carrying computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0132] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A closed-loop temperature compensation circuit for an atomic magnetometer laser, characterized in that, include: Laser unit, ADC unit, FPGA controller unit, first DAC unit, second DAC unit, TEC controller unit, and constant current source control circuit unit; The ADC unit is configured to convert the case temperature value of the laser unit into a digital signal and transmit it to the FPGA controller unit. The FPGA controller unit determines a temperature compensation code value based on the case temperature value using a temperature compensation algorithm, and adds the temperature compensation code value to the reference temperature point code value for temperature compensation correction to obtain a temperature correction code value. The temperature correction code value is then transmitted to the laser unit via a second DAC unit and the TEC controller unit connected in series. The FPGA controller unit is also configured to determine the laser operating current code value and transmit the laser operating current code value to the laser unit via a first DAC unit and a constant current source control circuit unit connected in series. The FPGA controller unit determines the temperature compensation code value based on the case temperature value using a temperature compensation algorithm, including: A segmented calibration function is determined by calibrating using a temperature compensation algorithm; the segmented calibration function is used to characterize the temperature compensation code value under different temperature ranges. Based on the shell temperature value, the matching temperature range in the segmented calibration function is determined, and then the target temperature compensation code value is determined. Determine the reference temperature code value for temperature compensation correction. The sum of the temperature correction code value and the target temperature compensation code value is the temperature correction code value; The piecewise calibration function is determined through temperature compensation algorithm calibration, including: The proportional relationship K1 between the output frequency drift of the laser unit and the change in the shell temperature of the laser unit is calibrated. Within a preset reference temperature range, the ratio K2 between the frequency change of the laser unit and the minimum change in the code value of the second DAC unit is calibrated; wherein, K2 is achieved by calibrating the ratio between the frequency change of the laser unit and the ratio of the least significant bit of the second DAC set by the TEC. The operating frequency of the laser unit is determined, and the reference temperature point for temperature compensation correction and the current reference operating point of the first DAC unit are obtained; wherein, the reference temperature point for temperature compensation correction is the operating temperature point of the TEC inside the laser at room temperature, and the current reference operating point of the first DAC unit is the operating current of the LD inside the laser at room temperature. The case temperature of the laser unit is detected by a temperature monitoring circuit, and the drift of the laser unit is determined based on the case temperature. The drift is calculated by comparing the case temperature with the ambient temperature reference point. The product of the difference and K1; The quotient of the drift amount and K2 is determined to be the temperature compensation code value that needs to be compensated; A function is constructed using the voltage value acquired by the ADC unit and converted into a digital signal as the independent variable and the temperature compensation code value as the dependent variable. The function is then piecewise fitted to obtain the piecewise calibration function.

2. The circuit according to claim 1, characterized in that, The laser unit is a distributed feedback laser whose output wavelength matches the resonance line of the target alkali metal atom; this laser serves as the core light source of the atomic magnetometer, and its output is used to realize the optical pumping, polarization, and magnetic sensitive state detection of the alkali metal atom gas cell. The laser unit physically integrates a laser diode die (LD), a thermoelectric cooler (TEC), and a high-precision temperature sensor; wherein: The LD is an active device that generates laser light of a preset wavelength. Excited light is achieved by injecting a specific driving current into the LD. The frequency of its output light will change with the temperature of the die and the injected current. The TEC is a thermoelectric cooler, installed close to the LD. Driven by the TEC controller, it can bidirectionally adjust the direction and magnitude of the current flowing through the TEC inside the laser, thereby achieving precise heating or cooling of the LD. It is the core actuator for active temperature control. The high-precision temperature sensor is a negative temperature coefficient NTC thermistor, arranged close to the LD, used to monitor the instantaneous temperature of the LD in real time with high precision, and convert the temperature change into a measurable resistance or voltage signal, serving as the key feedback for the closed-loop temperature control system.

3. The circuit according to claim 1, characterized in that, The TEC controller unit is a single-chip temperature controller used to control the TEC temperature inside the atomic magnetometer laser. It consists of a PID controller composed of a chopper self-stabilizing instrumentation amplifier and a high-precision integrating amplifier. The output terminal of the TEC controller unit is connected to the NTC thermistor integrated inside the laser unit and the TEC inside the laser unit, respectively, forming a closed-loop temperature control circuit. The FPGA controller unit, as the core processing and control unit of the closed-loop temperature compensation circuit, outputs a corresponding control reference signal to the TEC controller unit through the second DAC unit connected in series, according to the preset temperature target value. The TEC controller unit acquires the voltage signal fed back by the NTC thermistor, which characterizes the actual operating temperature of the laser, in real time, and compares it with the target temperature value to obtain a temperature error signal; The temperature error signal is input to the control algorithm integrated into the TEC controller to generate a real-time dynamic control signal; the dynamic control signal drives the TEC controller unit to precisely adjust the magnitude and direction of the current applied to the TEC, thereby achieving heating or cooling of the laser chip.

4. The circuit according to claim 1, characterized in that, The constant current source control circuit unit is connected to the LD chip inside the laser unit; The constant current source control circuit unit receives the laser operating current code value, controls the current of the LD chip based on the laser operating current code value, and then controls the laser unit to emit light.

5. A closed-loop temperature compensation method for an atomic magnetometer laser, characterized in that, The method is performed by the circuit described in any one of claims 1 to 4; The method includes: The ADC unit acquires the case temperature value of the laser unit, converts the case temperature value into a digital signal, and transmits it to the FPGA controller unit. The FPGA controller unit determines the temperature compensation code value based on the case temperature value using a temperature compensation algorithm. It adds the temperature compensation code value to the reference temperature point code value for temperature compensation correction to obtain the temperature correction code value, and transmits the temperature correction code value to the TEC controller unit to control the laser unit to emit light at the target frequency. The target frequency is the output frequency of the laser when the TEC inside the laser unit is operating at the target temperature point. The FPGA controller unit determines the temperature correction code value based on the case temperature value, including: A segmented calibration function is determined by calibrating using a temperature compensation algorithm; the segmented calibration function is used to characterize the temperature compensation code value under different temperature ranges. Based on the shell temperature value, the matching temperature range in the segmented calibration function is determined, and then the target temperature compensation code value is determined. Determine the reference temperature code value for temperature compensation correction. The sum of the temperature correction code value and the target temperature compensation code value is the temperature correction code value; The piecewise calibration function is determined through temperature compensation algorithm calibration, including: The proportional relationship K1 between the output frequency drift of the laser unit and the change in the shell temperature of the laser unit is calibrated. Within a preset reference temperature range, the ratio K2 between the frequency change of the laser unit and the minimum change in the code value of the second DAC unit is calibrated; wherein, K2 is achieved by calibrating the ratio between the frequency change of the laser unit and the ratio of the least significant bit of the second DAC set by the TEC. The operating frequency of the laser unit is determined, and the reference temperature point for temperature compensation correction and the current reference operating point of the first DAC unit are obtained; wherein, the reference temperature point for temperature compensation correction is the operating temperature point of the TEC inside the laser at room temperature, and the current reference operating point of the first DAC unit is the operating current of the LD inside the laser at room temperature. The case temperature of the laser unit is detected by a temperature monitoring circuit, and the drift of the laser unit is determined based on the case temperature. The drift is calculated by comparing the case temperature with the ambient temperature reference point. The product of the difference and K1; The quotient of the drift amount and K2 is determined to be the temperature compensation code value that needs to be compensated; A function is constructed using the voltage value acquired by the ADC unit and converted into a digital signal as the independent variable and the temperature compensation code value as the dependent variable. The function is then piecewise fitted to obtain the piecewise calibration function.

6. The method according to claim 5, characterized in that, Determine the reference temperature point for temperature compensation correction of the laser unit, including: In response to determining that the case temperature of the laser unit is stable, the operating current value of the LD chip in the laser unit and the operating temperature of the TEC are adjusted so that the laser unit emits light at the target frequency; The operating temperature of the TEC of the laser unit when emitting light at the target frequency is determined as the reference temperature point for the temperature compensation correction.

7. The method according to claim 6, characterized in that, The temperature of the laser unit's casing is detected by a temperature monitoring circuit, including: The resistance value of the thermistor of the laser unit's casing temperature was determined by the temperature monitoring circuit. ;in, The resistance value of the thermistor for the shell temperature is... The resistance value of the voltage divider resistor in the temperature monitoring circuit. The reference voltage for the ADC unit is... The number of bits in the ADC unit. This is the reference voltage for the temperature monitoring circuit. The code value is the result of the ADC unit converting the acquired voltage value into a digital signal. The shell temperature value is determined based on the resistance value of the shell temperature thermistor. ;in, The shell temperature value. The temperature coefficient of the thermistor, The resistance value of the thermistor at 25℃ is the laser housing temperature.

8. An electronic device, characterized in that, It includes a memory, a ground processor, and an on-orbit processor, wherein the memory stores a computer program, and the ground processor and the on-orbit processor execute the computer program to implement the steps of the method as described in any one of claims 5 to 7.

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