Control Method and System for Optimal Operating Point of Laser Current in Atomic Magnetometer

Abstract

The present invention provides a method and system for controlling the optimal operating point of the laser current of an atomic magnetometer, including: controlling a current source to perform a current scan from Imin to Imax with a step size of Idelt, and collecting and recording the photocurrent value Ipd corresponding to the current scan points in real time, and storing them in a first array A in sequence; processing the first array A to obtain a second array; discriminating the number of peaks and valleys in the second array B, obtaining the current scan point corresponding to the first valley, and taking the current scan point Iset0 corresponding to the first valley as the initial operating point of the laser, and recording the measured photocurrent value Ipd_set corresponding to the initial operating point; taking Ipd_set as a control point, and timely adjusting the operating current of the laser to make Ipd stable within the range of Ipd_set ± 1uA, thereby completing the control of the optimal operating point of the current. Applying the technical solution of the present invention can solve the technical problem that the method of manually interpreting the required operating current in the prior art takes a long time and cannot meet the production requirements of a large number of products.

Description

Technical Field

[0001] The present invention relates to the technical field of atomic magnetometers, and in particular to a method and system for controlling the optimal operating point of the laser current of an atomic magnetometer. Background Art

[0002] An atomic magnetometer uses atomic spin precession to detect a magnetic field to be measured, is applicable to the geomagnetic field environment, has high detection accuracy, can measure the total magnetic field strength, and is widely used in the field of magnetic exploration. A laser is a main component of an atomic magnetometer, and its stability directly affects the performance of the atomic magnetometer.

[0003] Currently, the main method for obtaining the optimal operating point of a laser is manual debugging, that is, manually changing the operating current of the laser, observing the laser current magnitude after passing through the head of the atomic magnetometer through a photodetector, obtaining a set of continuous data curves, and manually interpreting to obtain the required operating current. This method takes a long time and cannot meet the production requirements of mass products. Summary of the Invention

[0004] The present invention provides a method and system for controlling the optimal operating point of the laser current of an atomic magnetometer, which can solve the technical problem that the method of manually interpreting to obtain the required operating current in the prior art takes a long time and cannot meet the production requirements of mass products.

[0005] According to one aspect of the present invention, there is provided a method for controlling the optimal operating point of the laser current of an atomic magnetometer. The method for controlling the optimal operating point of the laser current of an atomic magnetometer includes: when the atomic magnetometer is powered on, controlling a current source to perform a laser current scan from a minimum current value Imin to a maximum current value Imax with a step size of Idelt, and simultaneously collecting and recording the photocurrent value Ipd measured by a photodetector corresponding to the current scan points in real time; after the current scan is completed, obtaining N = (Imax - Imin) / Idelt photocurrent measurement data, and storing them in a first array A in sequence; performing spectrum calculation, noise identification, and filtering processing on the first array A to obtain a second array, and obtaining the peaks and valleys in the second array B; discriminating the number of peaks and valleys in the second array B. If there are two peaks and two valleys, obtaining the current scan point corresponding to the first valley, and taking the current scan point Iset0 corresponding to the first valley as the initial operating point of the laser, and recording the photocurrent measurement value Ipd_set corresponding to the initial operating point. If the number of peaks is not two and / or the number of valleys is not two, reporting an abnormal situation, and repeating the above steps to start a new round of scanning until there are two peaks and two valleys in the second array B; taking the photocurrent measurement value Ipd_set as a control point, and timely adjusting the operating current of the laser to make the photocurrent value Ipd measured by the photodetector stable within the range of Ipd_set ± 1uA, thus completing the control of the optimal operating point of the laser current of the atomic magnetometer.

[0006] Further, perform spectrum calculation, noise identification, and filtering on the first array A to obtain a second array. Obtaining the peaks and valleys in the second array B specifically includes: performing spectrum calculation on the first array A to obtain the fft spectrum; performing noise identification on the fft spectrum to obtain the noise frequency value; filtering the first array A based on the noise frequency value to obtain a third array A1; grouping and averaging the third array A1 with a set number of points as a window to obtain a second array A2; performing piecewise fitting on the second array A2 to obtain the peaks and valleys in the second array A2.

[0007] Further, performing piecewise fitting on the second array A2 to obtain the peaks in the second array A2 specifically includes: starting from the first point W0 of the second array A2, setting three points (W0, W1, and W2) of the second array A2 as P0 = W0, P1 = W1, P2 = W2, performing linear fitting with P0, P1, and P2 as a window, and calculating to obtain D1 = P1 - P0, D2 = P2 - P1; if both D1 and D2 are greater than zero, record this line segment as an ascending segment, continue traversing and calculating, setting three points (W1, W2, and W3) of the second array A2 as P0 = W1, P1 = W2, P2 = W3, performing linear fitting with P0, P1, and P2 as a window, and calculating to obtain D1 = P1 - P0, D2 = P2 - P1; if both D1 and D2 are greater than zero, record this line segment as an ascending segment, continue traversing and calculating, repeating the above steps until D1 and D2 are not both greater than zero, record this line segment as a turning segment, record the inflection point Pn1 = P1 at this time, P1 = W i , the inflection point Pn1 is the first peak point Ppeak1; starting from Pn1, using three points (W i 、W i+1 and W i+2 ) as a window for linear fitting, setting as P0’ = W i , P1’ = W i+1 , P2’ = W i+2 , performing linear fitting with P0’, P1’, and P2’ as a window, and calculating to obtain D1’ = P1’ - P0’, D2’ = P2’ - P1’; if both D1’ and D2’ are less than zero, record this line segment as a descending segment, continue traversing and calculating, setting three points (W i+1 、W i+2 and W i+3 ) of the second array A2 as P0’ = W i+1 , P1’ = W i+2 , P2’ = W i+3, perform linear fitting with P0’, P1’ and P2’ as the window, and calculate to obtain D1’ = P1’ - P0’, D2’ = P2’ - P1’; if both D1’ and D2’ are less than zero, record this line segment as a descending segment, continue traversing and calculating, and repeat the above steps until D1’ and D2’ are not all greater than zero. Record this line segment as a turning segment, and record the inflection point Pn2 = P1’ at this time. The inflection point Pn2 is the first valley point Ptrough1; repeat the above process to obtain other peak points and valley points in the second array B.

[0008] Further, performing spectrum calculation on the first array A to obtain the fft spectrum specifically includes: adopting the general FFT algorithm, with 1024 sampling points, and performing spectrum calculation on the first array A using the Hanning window to obtain the fft spectrum.

[0009] Further, performing noise identification on the fft spectrum to obtain the noise frequency value specifically includes: performing noise identification on the fft spectrum, obtaining the maximum amplitude Amax and the amplitude average value Aavr, and within the frequency range of 5Hz to 500Hz, recording the frequency values whose amplitude values exceed the set frequency threshold, and taking the frequency values exceeding the set frequency threshold range as the noise frequency values.

[0010] Further, the set frequency threshold Ithreshold can be calculated according to Ithreshold = 0.2 * Amax + 0.8 * Aavr.

[0011] Further, filtering the first array A based on the noise frequency value to obtain the third array A1 specifically includes: adopting the adaptive notch filter design method, automatically calculating the notch filter corresponding to the noise frequency value, and using the notch filter to filter the first array to obtain the third array A1.

[0012] Further, set multiple points to be 10 points.

[0013] According to another aspect of the present invention, an optimal operating point control system for the atom magnetometer laser current is provided. The optimal operating point control system for the atom magnetometer laser current uses the above-mentioned optimal operating point control method for the atom magnetometer laser current to perform current optimal operating point control.

[0014] Furthermore, the optimal working point control system for the atom magnetometer laser current includes a current source, a laser, a meter head sensitive component, a photodetector, and a control circuit connected in sequence. The control circuit includes: a photocurrent value acquisition unit, which is used to control the current source to perform a laser current scan from the minimum current value Imin to the maximum current value Imax with a step size of Idelt, and to collect and record in real time the photocurrent value Ipd measured by the photodetector corresponding to the current scan points; a photocurrent measurement data acquisition unit, which is used to obtain N = (Imax - Imin) / Idelt photocurrent measurement data after the current scan and store them in the first array A in sequence; a second array acquisition unit, which is used to perform spectrum calculation, noise identification, and filtering on the first array A to obtain a second array; a peak and valley calculation unit, which is used to obtain the peaks and valleys in the second array B; a photocurrent measurement value acquisition unit, which is used to determine the number of peaks and valleys in the second array B. If there are two peaks and two valleys, the current scan point corresponding to the first valley is obtained, and the current scan point Iset0 corresponding to the first valley is used as the initial working point of the laser, and the photocurrent measurement value Ipd_set corresponding to the initial working point is recorded. If the number of peaks is not two and / or the number of valleys is not two, an abnormal situation is reported, and the above steps are repeated to start a new round of scanning until there are two peaks and two valleys in the second array B; a current optimal working point control unit, which is used to use the photocurrent measurement value Ipd_set as a control point and adjust the working current of the laser in a timely manner to make the photocurrent value Ipd measured by the photodetector stable within the range of Ipd_set ± 1uA, thereby completing the control of the optimal working point of the atom magnetometer laser current.

[0015] Applying the technical solution of the present invention, a method for controlling the optimal working point of the atom magnetometer laser current is provided. This method performs spectrum calculation, noise identification, filtering, grouped averaging, piecewise fitting, and peak and valley identification on multiple photocurrent value arrays, uses the photocurrent measurement value Ipd_set as a control point, and adjusts the working current of the laser in a timely manner to make the photocurrent value Ipd measured by the photodetector stable within the range of Ipd_set ± 1uA, thereby completing the control of the optimal working point of the atom magnetometer laser current. This method can quickly and automatically obtain the optimal working current of the laser and make the laser always work at the optimal current point through closed-loop control, improving the production test efficiency and performance stability of the atom magnetometer. Description of the Drawings

[0016] The accompanying drawings included are used to provide a further understanding of the embodiments of the present invention, which form a part of the specification, illustrate the embodiments of the present invention, and together with the written description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0017] Figure 1 The structural schematic diagram of the optimal operating point control system for the atom magnetometer laser current provided according to a specific embodiment of the present invention is shown. Detailed implementation manners

[0018] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of the present invention.

[0019] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary implementation manners according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and devices should be regarded as part of the authorized specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0021] AsFigure 1 As shown, according to a specific embodiment of the present invention, a method for controlling the optimal operating point of the laser current of an atomic magnetometer is provided. The method for controlling the optimal operating point of the laser current of the atomic magnetometer includes: when the atomic magnetometer is powered on, controlling the current source to perform a laser current scan from the minimum current value Imin to the maximum current value Imax with a step size of Idelt, and simultaneously collecting and recording the photocurrent value Ipd measured by the photodetector corresponding to the current scan points in real time; after the current scan is completed, N = (Imax - Imin) / Idelt photocurrent measurement data are obtained, and they are sequentially stored in the first array A; performing spectrum calculation, noise identification, and filtering processing on the first array A to obtain a second array, and obtaining the peaks and valleys in the second array B; judging the number of peaks and valleys in the second array B. If there are two peaks and two valleys, obtaining the current scan point corresponding to the first valley, and taking the current scan point Iset0 corresponding to the first valley as the initial operating point of the laser, and recording the photocurrent measurement value Ipd_set corresponding to the initial operating point. If the number of peaks is not two and / or the number of valleys is not two, reporting an abnormal situation, and repeating the above steps to start a new round of scanning until there are two peaks and two valleys in the second array B; taking the photocurrent measurement value Ipd_set as the control point, and timely adjusting the operating current of the laser to make the photocurrent value Ipd measured by the photodetector stable within the range of Ipd_set ± 1uA, thus completing the control of the optimal operating point of the laser current of the atomic magnetometer.

[0022] Applying this configuration method, a method for controlling the optimal operating point of the laser current of an atomic magnetometer is provided. This method performs spectrum calculation, noise identification, filtering, grouped averaging, piecewise fitting, and peak-valley identification on multiple photocurrent value arrays, takes the photocurrent measurement value Ipd_set as the control point, and timely adjusts the operating current of the laser to make the photocurrent value Ipd measured by the photodetector stable within the range of Ipd_set ± 1uA, thus completing the control of the optimal operating point of the laser current of the atomic magnetometer. This method can quickly and automatically obtain the optimal operating current of the laser, and through closed-loop control, make the laser always operate at the optimal current point, improving the production test efficiency and performance stability of the atomic magnetometer.

[0023] Further, in the present invention, in order to achieve the control of the optimal operating point of the laser current of the atomic magnetometer, when the atomic magnetometer is powered on, controlling the current source to perform a laser current scan from the minimum current value Imin to the maximum current value Imax with a step size of Idelt, and simultaneously collecting and recording the photocurrent value Ipd measured by the photodetector corresponding to the current scan points in real time; after the current scan is completed, N = (Imax - Imin) / Idelt photocurrent measurement data are obtained, and they are sequentially stored in the first array A.

[0024] After obtaining the first array A, the first array A can be subjected to spectrum calculation, noise identification, and filtering processing to obtain a second array, and the peaks and valleys in the second array B are obtained. Among them, performing spectrum calculation, noise identification, and filtering processing on the first array A to obtain a second array, and obtaining the peaks and valleys in the second array B specifically includes: performing spectrum calculation on the first array A to obtain an fft spectrum; performing noise identification on the fft spectrum to obtain noise frequency values; filtering the first array A based on the noise frequency values to obtain a third array A1; grouping and averaging the third array A1 with a set number of points as a window to obtain a second array A2; performing piecewise fitting on the second array A2 to obtain the peaks and valleys in the second array A2.

[0025] As a specific embodiment of the present invention, performing spectrum calculation on the first array A to obtain an fft spectrum specifically includes: adopting a general FFT algorithm, with 1024 sampling points, and using a Hanning window to perform spectrum calculation on the first array A to obtain an fft spectrum. Performing noise identification on the fft spectrum to obtain noise frequency values specifically includes: performing noise identification on the fft spectrum, obtaining the maximum amplitude Amax and the amplitude average value Aavr, and within the frequency range of 5 Hz to 500 Hz, recording the frequency values whose amplitude values exceed the set frequency threshold, and taking the frequency values exceeding the set frequency threshold range as noise frequency values. Among them, the set frequency threshold Ithreshold can be calculated and obtained according to Ithreshold = 0.2 * Amax + 0.8 * Aavr. Filtering the first array A based on the noise frequency values to obtain a third array A1 specifically includes: adopting an adaptive notch filter design method, automatically calculating the notch filter corresponding to the noise frequency values, and using the notch filter to filter the first array to obtain a third array A1.

[0026] Among them, performing piecewise fitting on the second array A2 to obtain the peaks and valleys in the second array A2 specifically includes: starting from the first point W0 of the second array A2, setting three points (W0, W1, and W2) of the second array A2 as P0 = W0, P1 = W1, P2 = W2, performing linear fitting with P0, P1, and P2 as a window, and calculating to obtain D1 = P1 - P0, D2 = P2 - P1; if both D1 and D2 are greater than zero, record this line segment as an ascending segment, continue traversing and calculating, set three points (W1, W2, and W3) of the second array A2 as P0 = W1, P1 = W2, P2 = W3, perform linear fitting with P0, P1, and P2 as a window, and calculate to obtain D1 = P1 - P0, D2 = P2 - P1; if both D1 and D2 are greater than zero, record this line segment as an ascending segment, continue traversing and calculating, repeat the above steps until D1 and D2 are not both greater than zero, record this line segment as a turning segment, record the inflection point Pn1 = P1 at this time, P1 = W i and the inflection point Pn1 is the first peak point; starting from Pn1, with three points (W i, W i+1 and W i+2 ) perform a linear fit for the window, and set P0’ = W i , P1’ = W i+1 , P2’ = W i+2 , perform a linear fit with P0’, P1’ and P2’ as the window, calculate and obtain D1’ = P1’ - P0’, D2’ = P2’ - P1’; if both D1’ and D2’ are less than zero, record this line segment as the descending segment, continue traversing and calculating, and for the three points (W i+1 , W i+2 and W i+3 ) in the second array A2, set P0’ = W i+1 , P1’ = W i+2 , P2’ = W i+3 , perform a linear fit with P0’, P1’ and P2’ as the window, calculate and obtain D1’ = P1’ - P0’, D2’ = P2’ - P1’; if both D1’ and D2’ are less than zero, record this line segment as the descending segment, continue traversing and calculating, repeat the above steps until D1’ and D2’ are not all greater than zero, record this line segment as the turning segment, record the inflection point Pn2 = P1’ at this time, and the inflection point Pn2 is the first valley point Ptrough1; repeat the above process to obtain other peak points and valley points in the second array B.

[0027] Furthermore, after obtaining the peak and valley in the second array A2, the number of peaks and valleys in the second array B can be discriminated. If there are two peaks and two valleys, obtain the current scanning point corresponding to the first valley, and use the current scanning point Iset0 corresponding to the first valley as the initial working point of the laser, record the photocurrent measurement value Ipd_set corresponding to the initial working point. If the number of peaks is not two and / or the number of valleys is not two, report an abnormal situation, and repeat the above steps to start a new round of scanning until there are two peaks and two valleys in the second array B.

[0028] After completing the discrimination of the number of peaks and valleys in the second array B, the photocurrent measurement value Ipd_set can be used as the control point to adjust the working current of the laser in a timely manner so that the photocurrent value Ipd measured by the photodetector is stabilized within the range of Ipd_set ± 1uA, and the optimal working point control of the atomic magnetometer laser current is completed.

[0029] According to another aspect of the present invention, there is provided an optimal working point control system for an atomic magnetometer laser current, and this optimal working point control system for an atomic magnetometer laser current uses the above-mentioned optimal working point control method for an atomic magnetometer laser current to perform optimal working point control of the current.

[0030] By applying this configuration, an optimal operating point control system for the laser current of an atomic magnetometer is provided. The system uses the photocurrent measurement value Ipd_set as a control point by performing spectrum calculation, noise identification, filtering, group averaging, segmented fitting, and peak and trough identification on multiple photocurrent value arrays, and timely adjusts the working current of the laser to stabilize the photocurrent value Ipd measured by the photodetector within the range of Ipd_set±1uA, thereby completing the optimal operating point control of the laser current of the atomic magnetometer. The system can quickly and automatically obtain the optimal operating current of the laser, and through closed-loop control, the laser always works at the optimal current point, thereby improving the production test efficiency and performance stability of the atomic magnetometer.

[0031] Furthermore, in order to realize the optimal operating point control of the atomic magnetometer laser current, the atomic magnetometer laser current optimal operating point control system includes a current source, a laser, a meter head sensitive component, a photodetector and a control circuit connected in sequence. The control circuit includes a photocurrent value acquisition unit, a photocurrent measurement data acquisition unit, a second array acquisition unit, a peak and valley calculation unit, a photocurrent measurement value acquisition unit and a current optimal operating point control unit. The photocurrent value acquisition unit is used to control the current source from the minimum current value Imin to the maximum current value Imax, and perform laser current scanning with a step size Idelt, and real-time collect and record the photocurrent value Ipd measured by the photodetector at the corresponding current scanning point. The photocurrent measurement data acquisition unit is used to obtain N = (Imax-Imin) / Idelt photocurrent measurement data after the current scanning is completed, and store them in the first array A in sequence. The second array acquisition unit is used to perform spectrum analysis on the first array A. Calculation, noise identification and filtering are performed to obtain the second array. The peak and trough calculation unit is used to obtain the peaks and troughs in the second array B. The photocurrent measurement value acquisition unit is used to judge the number of peaks and troughs in the second array B. If there are two peaks and two troughs, the current scanning point corresponding to the first trough is obtained, and the current scanning point Iset0 corresponding to the first trough is used as the initial working point of the laser. The photocurrent measurement value Ipd_set corresponding to the initial working point is recorded. If there are not two peaks and / or two troughs, an abnormal situation is reported, and the above steps are repeated to start a new round of scanning until there are two peaks and two troughs in the second array B. The current optimal working point control unit is used to use the photocurrent measurement value Ipd_set as the control point, and timely adjust the working current of the laser to stabilize the photocurrent value Ipd measured by the photodetector within the range of Ipd_set±1uA, thereby completing the optimal current working point control of the atomic magnetometer laser.

[0032] In order to further understand the present invention, the following Figure 1 The optimal operating point control method of the atomic magnetometer laser current provided by the present invention is described in detail.

[0033] As shown Figure 1 in the figure, according to a specific embodiment of the present invention, a method for controlling the optimal operating point of the laser current of an atomic magnetometer is provided, and the method specifically includes the following steps.

[0034] Step 1, when the atomic magnetometer is powered on, the control circuit first controls the current source to scan the laser current from Imin to Imax with a step size of Idelt, and simultaneously collects and records the photocurrent value Ipd measured by the photodetector corresponding to the current scan points in real time;

[0035] Let Imin be 1 mA, Imax be 2 mA, Idelt be 1 μA, and the current setting period be 1 ms;

[0036] Then the scanning completion time is 1000 ms;

[0037] Step 2, after the current scanning is completed, N = (Imax - Imin) / Idelt photocurrent measurement data are obtained, and they are stored in the first array A in sequence;

[0038] Among them: N = 1000, the sampling frequency is 1 kHz, and the sampling time is 1 s;

[0039] Step 3, perform data processing on the first array A, including spectrum calculation, noise identification, filtering, grouped averaging, piecewise fitting, and peak and valley identification; record the identified peaks and valleys in the second array B; among them, each photocurrent data corresponds to a current scan point, and the index value of the first array A corresponds to the number of the scan point. Processing the first array A is to obtain the index values of the peak and valley points, and the corresponding scan points can be found according to the index values.

[0040] Among them: (a) Spectrum calculation: adopt the general FFT algorithm, the number of sampling points is 1024 (padding 24 zeros), and the Hanning window;

[0041] The method of this step is general, use the built-in fft function in matlab, and the Hanning window is a parameter of this function. Use the Hanning window to perform spectrum calculation on the first array A to obtain the fft spectrum.

[0042] (b) Noise identification: perform noise identification on the obtained fft spectrum. First, obtain the maximum amplitude Amax and the amplitude average value Aavr; then in the frequency range of 5 - 500 Hz, record the noise frequency values whose amplitude values exceed Ithreshold = 0.2*Amax + 0.8*Aavr; the result range obtained by the fft operation is half of the sampling frequency.

[0043] (c) Filtering: Using the adaptive notch filter design method, automatically calculate the notch filter corresponding to the frequency in step (b). The notch filter adopts a second-order IIR form; filter the array A to obtain the array A1;

[0044] The calculation formula for the notch filter parameters is:

[0045] Fnotch = frequency value;

[0046] Pi = 3.1415926;

[0047] BW = Fnotch / Q / (Fs / 2)*Pi; (where Q is the attenuation coefficient and Fs is the sampling rate)

[0048] Wo = Fnotch / (Fs / 2)*Pi;

[0049] Gb = 10^(-1 / 20);

[0050] Beta = sqrt(1 - Gb^2) / Gb*tan(BW / 2);

[0051] Gain = 1 / (1 + Beta);

[0052] A0 = Gain;

[0053] A1 = -2*Gain*cos(Wo);

[0054] A2 = Gain;

[0055] B0 = 1;

[0056] B1 = -2*Gain*cos(Wo);

[0057] B2 = 2*Gain - 1;

[0058] The filtering calculation formula is:

[0059] y0 = A0*x0 + A1*x1 + A2*x2 - B1*y1 - B2*y2;

[0060] Where: x0, x1, x2 are the continuous three photocurrent values;

[0061] y1, y2 are the previous two filtering results;

[0062] y0 is the current filtering result;

[0063] (d) Group averaging: Using a 10-point window, group-average A1 to obtain the array A2;

[0064] This is how it is done.

[0065] (e) Piecewise fitting: Starting from the first point W0 of the second array A2, set three points (W0, W1, and W2) of the second array A2 as P0 = W0, P1 = W1, P2 = W2. Perform linear fitting with P0, P1, and P2 as the window, and calculate to obtain D1 = P1 - P0, D2 = P2 - P1;

[0066] If both D1 and D2 are greater than zero, record this line segment as an ascending segment, continue traversing and calculating. Set three points (W1, W2, and W3) of the second array A2 as P0 = W1, P1 = W2, P2 = W3. Perform linear fitting with P0, P1, and P2 as the window, and calculate to obtain D1 = P1 - P0, D2 = P2 - P1;

[0067] If both D1 and D2 are greater than zero, record this line segment as an ascending segment, continue traversing and calculating, and repeat the above steps until D1 and D2 are not both greater than zero. Record this line segment as a turning segment, and record the inflection point Pn1 = P1 at this time, P1 = W i , and the inflection point Pn1 is the first peak point Ppeak1;

[0068] Pn1 takes P1, that is, the second point of every three points is taken as the inflection point index value.

[0069] If both D1' and D2' are less than zero, record this line segment as a descending segment, continue traversing and calculating. Set three points (W i+1 、W i+2 and W i+3 ) of the second array A2 as P0' = W i+1 , P1' = W i+2 , P2' = W i+3 , perform linear fitting with P0', P1', and P2' as the window, and calculate to obtain D1' = P1' - P0', D2' = P2' - P1';

[0070] If both D1' and D2' are less than zero, record this line segment as a descending segment, continue traversing and calculating, and repeat the above steps until D1' and D2' are not both greater than zero. Record this line segment as a turning segment, and record the inflection point Pn2 = P1' at this time. The inflection point Pn2 is the first trough point Ptrough1;

[0071] Starting from this point, repeat the above steps to obtain the second peak point Ppeak2, the second trough point Ptrough2, the third peak point Ppeak3 (if any), and the third trough point Ptrough3 (if any);

[0072] First find the peak and trough points, and find the peak and trough at most three times. Normally, three cannot be found. After finding, make a unified judgment in step 4.

[0073] Record Ptrough1, Ppeak1, Ptrough2, Ppeak2, Ptrough3 (if any), and Ppeak3 (if any) into array B;

[0074] Step 4: Perform result discrimination on array B, including the number of peaks and troughs, corresponding photocurrent values, and corresponding current scan points;

[0075] Under normal circumstances, two peaks and two troughs will be obtained, and the current scan point corresponding to the first trough is approximately located at a position slightly ahead of the middle. At this time, take the current scan point Iset corresponding to the first trough as the initial working point of the laser, and record the measured photocurrent value Ipd_set corresponding to this point; in other cases, report an abnormal situation and start a new round of scanning;

[0076] After determining the initial working current, that is, using Ipd_set as the control point, perform PI control during the subsequent working process to adjust the working current Iset in real time. If the control process is effective (i.e., the photocurrent value is stable within the range of Ipd_set ± 1uA), it is considered that the laser works stably during the working process.

[0077] In summary, the present invention provides a method for controlling the optimal working point of the laser current of an atomic magnetometer. This method performs spectrum calculation, noise identification, filtering, grouped averaging, piecewise fitting, and peak and trough identification on multiple photocurrent value arrays, uses the measured photocurrent value Ipd_set as the control point, and adjusts the working current of the laser in a timely manner to make the photocurrent value Ipd measured by the photodetector stable within the range of Ipd_set ± 1uA, thereby completing the control of the optimal working point of the laser current of the atomic magnetometer. This method can quickly and automatically obtain the best working current of the laser, and through closed-loop control, make the laser always work at the best current point, improving the production test efficiency and performance stability of the atomic magnetometer.

[0078] For ease of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "above" etc. can be used here to describe the spatial position relationship between a device or feature shown in the figure and other devices or features. It should be understood that spatial relative terms are intended to include different orientations in use or operation in addition to the orientation described in the figure for the device. For example, if the device in the drawing is inverted, the device described as "above other devices or structures" or "over other devices or structures" will be positioned as "below other devices or structures" or "under other devices or structures" afterwards. Thus, the exemplary term "above..." can include both the orientations of "above..." and "below...". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding explanations are made for the spatial relative descriptions used here.

[0079] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Without additional declaration, the above terms have no special meaning, so it should not be construed as a limitation on the protection scope of the present invention.

[0080] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A control method for the optimal operating point of the laser current of an atomic magnetometer, characterized in that, The optimal operating point control method for the laser current of the atomic magnetometer includes: When the atomic magnetometer is powered on, control the current source to scan the laser current from the minimum current value Imin to the maximum current value Imax with a step size of Idelt, and simultaneously collect and record the photocurrent value Ipd measured by the photodetector at the corresponding current scan points in real time; After the current scan is completed, N = (Imax - Imin) / Idelt photocurrent measurement data are obtained and stored in the first array A in sequence; Perform spectrum calculation, noise identification, and filtering processing on the first array A to obtain a second array, and obtain the peaks and valleys in the second array B; Judge the number of peaks and valleys in the second array B. If there are two peaks and two valleys, obtain the current scan point corresponding to the first valley, and use the current scan point Iset0 corresponding to the first valley as the initial operating point of the laser, and record the photocurrent measurement value Ipd_set corresponding to the initial operating point. If the number of peaks is not two and / or the number of valleys is not two, report an abnormal situation, and repeat "control the current source to scan the laser current from the minimum current value Imin to the maximum current value Imax with a step size of Idelt, and simultaneously collect and record the photocurrent value Ipd measured by the photodetector at the corresponding current scan points in real time; after the current scan is completed, N = (Imax - Imin) / Idelt photocurrent measurement data are obtained and stored in the first array A in sequence; perform spectrum calculation, noise identification, and filtering processing on the first array A to obtain a second array, and obtain the peaks and valleys in the second array B; judge the number of peaks and valleys in the second array B. If there are two peaks and two valleys, obtain the current scan point corresponding to the first valley, and use the current scan point Iset0 corresponding to the first valley as the initial operating point of the laser, and record the photocurrent measurement value Ipd_set corresponding to the initial operating point. If the number of peaks is not two and / or the number of valleys is not two, report an abnormal situation" to start a new round of scanning until there are two peaks and two valleys in the second array B; Use the photocurrent measurement value Ipd_set as the control point, and adjust the operating current of the laser in a timely manner to make the photocurrent value Ipd measured by the photodetector stable within the range of Ipd_set ± 1uA, thus completing the control of the optimal operating point of the laser current of the atomic magnetometer.

2. The method for controlling the optimal operating point of the laser current of the atomic magnetometer according to claim 1, characterized in that, Performing spectrum calculation, noise identification, and filtering processing on the first array A to obtain a second array, and obtaining the peaks and valleys in the second array B specifically includes: Perform spectrum calculation on the first array A to obtain the fft spectrum; Perform noise identification on the fft spectrum to obtain the noise frequency value; Filter the first array A based on the noise frequency value to obtain a third array A1; Use a set number of points as the window to group and average the third array A1 to obtain a second array A2; Perform piecewise fitting on the second array A2 to obtain the peaks and valleys in the second array A2.

3. The method for controlling the optimal operating point of the laser current of the atomic magnetometer according to claim 2, wherein Performing piecewise fitting on the second array A2 to obtain the peaks and valleys in the second array A2 specifically includes: Starting from the first point W0 of the second array A2, set the three points W0, W1, and W2 of the second array A2 as P0 = W0, P1 = W1, and P2 = W2. Perform linear fitting with P0, P1, and P2 as the window, and calculate to obtain D1 = P1 - P0 and D2 = P2 - P1; If both D1 and D2 are greater than zero, record this line segment as the rising segment, continue traversing and calculating. Set the three points W1, W2, and W3 of the second array A2 as P0 = W1, P1 = W2, and P2 = W3. Perform linear fitting with P0, P1, and P2 as the window, and calculate to obtain D1 = P1 - P0 and D2 = P2 - P1; If both D1 and D2 are greater than zero, record this straight line segment as the rising segment, continue traversing and calculating, and repeat the above steps until D1 and D2 are not all greater than zero. Record this straight line segment as the turning segment, and record the inflection point Pn1 = P1 at this time, where P1 = W i , and the inflection point Pn1 is the first peak point Ppeak1; Starting from Pn1, perform a linear fit for the window with three points W i , W i+1 and W i+2 and set P0’ = W i , P1’ = W i+1 , P2’ = W i+2 . Perform a linear fit for the window with P0’, P1’ and P2’, and calculate to obtain D1’ = P1’ - P0’, D2’ = P2’ - P1’; If both D1’ and D2’ are less than zero, record this line segment as a descending segment and continue traversing and calculating the three points W i+1 , W i+2 and W i+3 Set P0’ = W i+1 , P1’ = W i+2 , P2’ = W i+3 , perform linear fitting with P0’, P1’ and P2’ as the window, and calculate to obtain D1’ = P1’ - P0’, D2’ = P2’ - P1’; If both D1' and D2' are less than zero, record this line segment as the falling segment, continue traversing and calculating. Repeat the above steps until D1' and D2' are not both greater than zero. Record this line segment as the turning segment, and record the inflection point Pn2 = P1' at this time. The inflection point Pn2 is the first valley point Ptrough1; Repeat "starting from the first point W0 of the second array A2, set the three points W0, W1, and W2 of the second array A2 as P0 = W0, P1 = W1, P2 = W2, perform linear fitting with P0, P1, and P2 as the window, calculate and obtain D1 = P1 - P0, D2 = P2 - P1; if both D1 and D2 are greater than zero, record this line segment as the rising segment, continue traversing and calculating, set the three points W1, W2, and W3 of the second array A2 as P0 = W1, P1 = W2, P2 = W3, perform linear fitting with P0, P1, and P2 as the window, calculate and obtain D1 = P1 - P0, D2 = P2 - P1; if both D1 and D2 are greater than zero, record this line segment as the rising segment, continue traversing and calculating, repeat the above steps until D1 and D2 are not both greater than zero, record this line segment as the turning segment, record the inflection point Pn1 = P1 at this time, P1 = W i , the inflection point Pn1 is the first peak point Ppeak1; starting from Pn1, with three points W i 、W i+1 and W i+2 as the window for linear fitting, set as P0’ = W i , P1’ = W i+1 , P2’ = W i+2 , perform linear fitting with P0’, P1’, and P2’ as the window, calculate and obtain D1’ = P1’ - P0’, D2’ = P2’ - P1’; if both D1’ and D2’ are less than zero, record this line segment as the falling segment, continue traversing and calculating, the three points W i+1 、W i+2 and W i+3 of the second array A2 are set as P0’ = W i+1 , P1’ = W i+2 , P2’ = W i+3 , perform linear fitting with P0’, P1’, and P2’ as the window, calculate and obtain D1’ = P1’ - P0’, D2’ = P2’ - P1’; if both D1’ and D2’ are less than zero, record this line segment as the falling segment, continue traversing and calculating, repeat the above steps until D1’ and D2’ are not both greater than zero, record this line segment as the turning segment, record the inflection point Pn2 = P1’ at this time, the inflection point Pn2 is the first trough point Ptrough1", and obtain other peak points and trough points in the second array B.

4. The method for controlling the optimal operating point of the laser current of the atomic magnetometer according to claim 3, characterized in that Performing spectrum calculation on the first array A to obtain the fft spectrum specifically includes: Using the general FFT algorithm with 1024 sampling points, and performing spectrum calculation on the first array A using the Hanning window to obtain the fft spectrum.

5. The method for controlling the optimal operating point of the laser current of the atomic magnetometer according to claim 4, characterized in that, Performing noise identification on the fft spectrum to obtain the noise frequency value specifically includes: Performing noise identification on the fft spectrum to obtain the maximum amplitude Amax and the amplitude average value Aavr. In the frequency range of 5 Hz to 500 Hz, record the frequency values whose amplitude values exceed the set frequency threshold, and use the frequency values exceeding the set frequency threshold range as the noise frequency values.

6. The method for controlling the optimal operating point of the laser current of the atomic magnetometer according to claim 5, wherein The set frequency threshold Ithreshold can be calculated as Ithreshold = 0.2 * Amax + 0.8 * Aavr.

7. The control method for the optimal operating point of the laser current of the atomic magnetometer according to claim 5, characterized in that, Filtering the first array A based on the noise frequency value to obtain the third array A1 specifically includes: Using the adaptive notch filter design method to automatically calculate the notch filter corresponding to the noise frequency value, and using the notch filter to filter the first array to obtain the third array A1.

8. The control method for the optimal operating point of the laser current of the atomic magnetometer according to claim 7, wherein The set number of points is 10 points.

9. An optimal operating point control system for the laser current of an atomic magnetometer, characterized in that, The optimal working point control system for the atomic magnetometer laser current uses the optimal working point control method for the atomic magnetometer laser current as described in any one of claims 1 to 8 to perform current optimal working point control.

10. The optimal operating point control system for the laser current of an atomic magnetometer according to claim 9, characterized in that, The optimal working point control system for the atomic magnetometer laser current includes a current source, a laser, a head sensitive component, a photodetector, and a control circuit connected in sequence. The control circuit includes: A photocurrent value acquisition unit, which is used to control the current source to scan the laser current from the minimum current value Imin to the maximum current value Imax with a step size of Idelt, and to collect and record in real time the photocurrent value Ipd measured by the photodetector corresponding to the current scan point; A photocurrent measurement data acquisition unit, which is used to obtain N = (Imax - Imin) / Idelt photocurrent measurement data after the current scan is completed and store them in the first array A in sequence; A second array acquisition unit, which is used to perform spectrum calculation, noise identification, and filtering processing on the first array A to obtain a second array; A peak and valley calculation unit, which is used to obtain the peaks and valleys in the second array B; A photocurrent measurement value acquisition unit, which is used to determine the number of peaks and valleys in the second array B. If there are two peaks and two valleys, obtain the current scan point corresponding to the first valley, and use the current scan point Iset0 corresponding to the first valley as the initial working point of the laser, and record the photocurrent measurement value Ipd_set corresponding to the initial working point. If the number of peaks is not two and / or the number of valleys is not two, report an abnormal situation, and repeat the above steps to start a new round of scanning until there are two peaks and two valleys in the second array B; A current optimal working point control unit, which is used to use the photocurrent measurement value Ipd_set as a control point and adjust the working current of the laser in a timely manner so that the photocurrent value Ipd measured by the photodetector is stabilized within the range of Ipd_set ± 1uA, and complete the control of the current optimal working point of the atomic magnetometer laser.

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