Rapid scanning method for optimal working state point of CPT atomic clock and CPT atomic clock

Abstract

The invention belongs to the technical field of gyroscopes, and discloses a CPT atomic clock optimal working state point rapid scanning method and a CPT atomic clock.Radio frequency is set to be 0 through a CPT control circuit, and the temperature of a TEC heating sheet is set to be the lowest working temperature; the working temperature of the TEC heating sheet is raised by T, the number of the absorption peaks is detected, the T is halved, the working temperature of the TEC heating sheet is raised by the current T value, the direct current scanning is carried out again, the working temperature of the TEC heating sheet is raised by the current T value, and the direct current scanning is carried out; detecting whether the direct current value of the double absorption peak center is in a preset range about the median of a direct current scanning range, setting the direct current value as the median of the direct current scanning range, performing radio frequency scanning through a CPT control circuit, and determining a frequency domain image of an optical signal received by a phototube; the radio frequency is set at the absorption peak of the frequency domain image of the optical signal, so that the optimal working state of the CPT atomic clock is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of gyroscopes, and in particular relates to a CPT atomic clock optimum working state point rapid scanning method and a CPT atomic clock. Background Art

[0002] The core sensing part of the CPT atomic clock is its physical part, in which the main control sensor device is the VCSEL laser. The working state of the VCSEL laser is affected by three parameters: DC, RF and temperature. DC and RF are provided by the CPT atomic clock control circuit, while the temperature is controlled by the TEC heater. If the CPT atomic clock wants to reach the best working state, the three parameters of the VCSEL laser, namely DC, RF and TEC temperature control, must all reach the best state. Among the three parameters, the parameter that has the greatest impact on the working state of the CPT atomic clock is the TEC temperature control. For the rapid scanning of the best state of the CPT atomic clock, the focus is on how to find the best TEC temperature control point, DC and RF values. Since the status of multiple parameters needs to be determined, and the operating range of VCSEL lasers is generally 25℃~65℃, with many temperature points, if DC and RF are performed on each temperature point, the scanning time will be extremely long; if the state of the CPT atomic clock is unknown when it is started for the first time, it will take a lot of time to determine its optimal working state for the first time, so a method is needed to achieve rapid scanning of the working state of the CPT atomic clock. Summary of the invention

[0003] In order to solve the problem that the traditional CPT atomic clock takes a long time to determine the working point and is slow to start for the first time, the present invention proposes a CPT atomic clock optimal working state point fast scanning method and a CPT atomic clock.

[0004] The technical solution of the present invention:

[0005] In a first aspect, the present invention provides a method for quickly scanning the optimal working state point of a CPT atomic clock. Determining the working point of the CPT atomic clock requires determining three parameters: direct current, radio frequency, and TEC heater temperature. The method comprises:

[0006] Step 1: Set the radio frequency to 0 through the CPT control circuit and the temperature of the TEC heater to the lowest operating temperature;

[0007] Step 2: Perform a DC scan to check whether the light signal received by the phototube has an absorption peak. If there is an absorption peak, proceed to step 3. Otherwise, increase the operating temperature of the TEC heater by △T and repeat step 2.

[0008] Step 3: Detect the number of absorption peaks. If there is only a single absorption peak, proceed to step 4; if there are double absorption peaks, proceed to step 5;

[0009] Step 4: △T is halved, the operating temperature of the TEC heater is increased by the current △T value, and DC scanning is performed again. If there is only a single absorption peak, repeat step 4;

[0010] Step 5: Raise the working temperature of the TEC heater by the current △T value, perform DC scanning, and detect whether the DC value at the center of the double absorption peak is within the preset range around the median of the DC scanning range. If not, halve the absolute value of △T and repeat step 5. If yes, proceed to step 6.

[0011] Step 6: Set the DC value to the median value of the DC scanning range, perform RF scanning through the CPT control circuit, and determine the frequency domain image of the optical signal received by the photoelectric tube;

[0012] Step 7: Set the radio frequency to the absorption peak of the frequency domain image of the optical signal to achieve the optimal working state of the CPT atomic clock.

[0013] Furthermore,

[0014] In step five, when the absolute value of △T is halved, the positive and negative signs of △T are determined by the positions of the two absorption peaks and the median of the DC scanning range. When the center positions of the two absorption peaks are to the left of the median of the DC scanning range, △T is negative; when the center positions of the two absorption peaks are to the right of the median of the DC scanning range, △T is positive.

[0015] Furthermore,

[0016] In step 2, the operating temperature of the TEC heater is increased by ΔT, ΔT = 3°C.

[0017] In a second aspect, the present invention further provides a CPT atomic clock, wherein the optimal operating point of the CPT atomic clock is determined by the method described in the first aspect, and the physical part of the CPT atomic clock includes:

[0018] TEC heater, temperature sensor, VCSEL laser, C-field coil, alkali metal gas chamber, photoelectric tube, heating resistor network;

[0019] The VCSEL laser 3 is placed on the TEC heating plate 1, and the temperature sensor 2 is placed next to the VCSEL laser 3; the outside of the alkali metal gas chamber 5 is wrapped with a C field coil 4, and the lower part of the alkali metal gas chamber 5 is heated by a heating resistor network 7;

[0020] The laser is emitted by the VCSEL laser 3 and passes through the alkali metal gas chamber 5 and irradiates the photoelectric tube 10;

[0021] The control of the electrical parameters of the physical part of the CPT atomic clock is performed by the CPT control circuit, and the photoelectric tube feedback signal is also transmitted to the CPT control circuit. The electrical parameters at least include DC, RF and the temperature of the TEC heating plate.

[0022] Furthermore,

[0023] The TEC heating plate is used to heat or cool the VCSEL laser and maintain the temperature of the laser temperature box. The heating or cooling efficiency is determined by the direction and magnitude of the current passing through the TEC heating plate.

[0024] Furthermore,

[0025] The VCSEL laser is used to generate coherent two-color light, and the operating temperature range is 31°C to 65°C, so that the rubidium atoms in the alkali metal gas chamber are in a CPT coherent population trapping state, generating a CPT phenomenon;

[0026] Furthermore,

[0027] The alkali metal gas chamber is the core sensor of the CPT atomic clock, and produces the CPT phenomenon after being irradiated by two-color light of a specific band;

[0028] The photoelectric tube is used to receive the optical signal emitted by the VCSEL laser through the standard gas chamber component, convert it into an electrical signal and transmit it to the CPT control circuit;

[0029] Furthermore,

[0030] The temperature sensor is used to feedback the temperature of the VCSEL laser;

[0031] The C field coil is used to provide a stable magnetic field for the alkali metal gas chamber;

[0032] The heating resistor network is used to heat the alkali metal gas chamber.

[0033] Beneficial effects of the technical solution of the present invention:

[0034] In the traditional scanning method, DC and RF scanning are performed at each temperature point. Since the VCSEL laser has a wide operating range (25°C to 65°C), the CPT-related phenomenon actually only occurs at about ±3°C around the effective operating point. Therefore, the traditional method actually wastes most of the time scanning in an invalid temperature range. The scanning method mentioned in the present invention utilizes the characteristic that the scanning curve corresponding to the DC scanning when the CPT absorption curve has no radio frequency has a double absorption peak. By raising the temperature by 3°C, the effective temperature point range (the optimal temperature point is ±3°C) is quickly found, and the temperature of the optimal operating point is approached within this range. The optimal operating temperature point is considered to be when the center of the double absorption peak coincides with the center of the DC scanning range. By comparing the two, the scanning method mentioned in the present invention saves the scanning time of the invalid temperature range, so that the overall scanning time is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1This is a schematic diagram of the physical structure of the CPT atomic clock;

[0036] Among them, 1-TEC, 2-temperature sensor, 3-VCSEL laser, 4-C field coil, 5-alkali metal gas chamber, 6-phototube, 7-heating resistor network;

[0037] Figure 2 This is the DC absorption peak scanning diagram at the optimal temperature point (RF is 0);

[0038] Figure 3 RF scanning absorption peak diagram after DC direct current and temperature point setting;

[0039] Figure 4 This is the DC scanning absorption peak diagram of the CPT atomic clock in the best working state;

[0040] Figure 5 It is a flowchart of the method for implementing the present invention;

[0041] Figure 6 This is a DC scanning diagram. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is described in detail below with reference to the accompanying drawings.

[0043] like Figure 1 As shown, the physical part of the CPT atomic clock mentioned in the present invention includes a TEC heater, a temperature sensor, a VCSEL laser, a C field coil, an alkali metal gas chamber, a photoelectric tube, and a heating resistor network.

[0044] The TEC mentioned in the CPT atomic clock physics part of the present invention is a TEC heating plate, which is used for heating or cooling the VCSEL laser and maintaining the temperature of the laser temperature box. Its heating or cooling and efficiency are determined by the direction and size of the current passing through the TEC.

[0045] The temperature sensor mentioned in the CPT atomic clock physics part of the present invention feeds back the temperature of the VCSEL laser.

[0046] The VCSEL laser mentioned in the CPT atomic clock physics part of the present invention is used to generate coherent two-color light, and the operating temperature range is 31°C to 65°C, so that the rubidium atoms in the alkali metal gas chamber are in a CPT coherent population trapping state, generating the CPT phenomenon.

[0047] The C field coil mentioned in the physics part of the CPT atomic clock in the present invention is used to provide a stable magnetic field for the gas chamber.

[0048] The alkali metal gas chamber mentioned in the physics part of the CPT atomic clock in the present invention is the core sensor device of the CPT atomic clock, which produces the CPT phenomenon after being irradiated by two-color light of a specific band.

[0049] The photoelectric tube mentioned in the physics part of the CPT atomic clock in the present invention is used to receive the optical signal emitted by the VCSEL laser through the standard gas chamber component, convert it into an electrical signal and transmit it to the CPT control circuit.

[0050] The heating resistor network mentioned in the CPT atomic clock physics part of the present invention is used to heat the gas chamber.

[0051] According to the attached Figure 1 The physical part of the CPT atomic clock designed in the present invention is described as follows:

[0052] The VCSEL laser 3 is attached to the TEC 1, and the temperature sensor 2 is placed next to the VCSEL laser 3; the C field coil 4 is wrapped outside the alkali metal gas chamber 5, and the lower part is heated by the heating resistor network 7; the laser is emitted by the VCSEL laser 3 through the alkali metal gas chamber 5 and then irradiated on the photoelectric tube 10; the control of the electrical parameters of the entire physical part (at least including DC direct current, RF radio frequency and the temperature of the TEC heating plate) is executed by the CPT control circuit, and the feedback signal of the photoelectric tube is also transmitted to the CPT control circuit.

[0053] Combined with Figure 5 The implementation steps of the present invention are described as follows:

[0054] Step 1: Set the RF frequency to 0 through the CPT control circuit, and set the temperature of TEC to the lowest operating temperature T=T0;

[0055] Step 2: Perform DC scanning. See the scanning method. Figure 6 , check whether the light signal received by the photoelectric tube 10 has an absorption peak. If there is an absorption peak, go to step three, otherwise increase the working temperature by △T (the initial value of △T is 3°C) and repeat step two.

[0056] Step 3: Detect the number of absorption peaks. If there is only a single absorption peak, proceed to step 4; if there are double absorption peaks, proceed to step 5.

[0057] Step 4: △T is halved, the working temperature is increased by △T, and DC scanning is performed again. If there is only a single absorption peak, repeat step 4;

[0058] Step 5: Increase the operating temperature of TEC by △T, perform DC scanning, and detect whether the DC value of the center of the double absorption peak is around the median of the DC scanning range. If not, the absolute value of △T is halved (the positive and negative signs of △T are determined by the positions of the two absorption peaks and the median of the DC scanning range. The center position of the two absorption peaks is on the left side of the median of the DC scanning range. △T is negative, and the center position of the two absorption peaks is on the right side of the median of the DC scanning range. △T is positive). Repeat step 5. If (such as Figure 2 If the display is not displayed, go to step 6.

[0059] Step 6: The DC is set to the median of the DC scanning range, and an RF scan is performed through the CPT control circuit to determine the frequency domain image of the optical signal received by the phototube.

[0060] Step 7: Set RF to the absorption peak of the frequency domain image of the optical signal (such as Figure 3 As shown), the CPT atomic clock reaches its optimal working state.

[0061] After reaching the optimal operating temperature and RF radio frequency, the DC scanning image is as follows Figure 4 shown.

[0062] Beneficial effects of the technical solution of the present invention:

[0063] In the traditional scanning method, DC and RF scanning are performed at each temperature point. Since the VCSEL laser has a wide operating range (25°C to 65°C), the CPT-related phenomenon actually only occurs at about ±3°C around the effective operating point. Therefore, the traditional method actually wastes most of the time scanning in an invalid temperature range. The scanning method mentioned in the present invention utilizes the characteristic that the scanning curve corresponding to the DC scanning when the CPT absorption curve has no radio frequency has a double absorption peak. By raising the temperature by 3°C, the effective temperature point range (the optimal temperature point is ±3°C) is quickly found, and the temperature of the optimal operating point is approached within this range. The optimal operating temperature point is considered to be when the center of the double absorption peak coincides with the center of the DC scanning range. By comparing the two, the scanning method mentioned in the present invention saves the scanning time of the invalid temperature range, so that the overall scanning time is greatly reduced.

Claims

1. A method for rapidly scanning the optimal working state point of a CPT atomic clock, characterized in that: Determining the CPT atomic clock operating point requires determining three parameters: direct current, radio frequency, and TEC heater temperature. The method includes: Step 1: Set the radio frequency to 0 through the CPT control circuit and the temperature of the TEC heater to the lowest operating temperature; Step 2: Perform a DC scan to check whether the light signal received by the phototube has an absorption peak. If there is an absorption peak, proceed to step 3. Otherwise, increase the operating temperature of the TEC heater by △T and repeat step 2. Step 3: Detect the number of absorption peaks. If there is only a single absorption peak, proceed to step 4; if there are double absorption peaks, proceed to step 5; Step 4: △T is halved, the operating temperature of the TEC heater is increased by the current △T value, and DC scanning is performed again. If there is only a single absorption peak, repeat step 4; Step 5: Raise the working temperature of the TEC heater by the current △T value, perform DC scanning, and detect whether the DC value at the center of the double absorption peak is within the preset range around the median of the DC scanning range. If not, halve the absolute value of △T and repeat step 5. If yes, proceed to step 6. Step 6: Set the DC value to the median value of the DC scanning range, perform RF scanning through the CPT control circuit, and determine the frequency domain image of the optical signal received by the photoelectric tube; Step 7: Set the radio frequency to the absorption peak of the frequency domain image of the optical signal to achieve the optimal working state of the CPT atomic clock.

2. A CPT atomic clock optimal working state point rapid scanning method according to claim 1, characterized in that: In step five, when the absolute value of △T is halved, the positive and negative signs of △T are determined by the positions of the two absorption peaks and the median of the DC scanning range. When the center positions of the two absorption peaks are to the left of the median of the DC scanning range, △T is negative; when the center positions of the two absorption peaks are to the right of the median of the DC scanning range, △T is positive.

3. The method for rapidly scanning the optimal working state point of a CPT atomic clock according to claim 1, characterized in that: In step 2, the operating temperature of the TEC heater is increased by ΔT, ΔT = 3°C.

4. A CPT atomic clock, characterized in that: The optimal operating point of the CPT atomic clock is determined by the method according to any one of claims 1 to 3, and the physical part of the CPT atomic clock includes: TEC heater, temperature sensor, VCSEL laser, C-field coil, alkali metal gas chamber, photoelectric tube, heating resistor network; The VCSEL laser (3) is placed on the TEC heating plate (1), and the temperature sensor (2) is placed next to the VCSEL laser (3); the outside of the alkali metal gas chamber (5) is wrapped with a C field coil (4), and the lower part of the alkali metal gas chamber (5) is heated by a heating resistor network (7); Laser light is emitted by a VCSEL laser (3) and passes through an alkali metal gas chamber (5) and then irradiates a photoelectric tube (10); The control of the electrical parameters of the physical part of the CPT atomic clock is performed by the CPT control circuit, and the photoelectric tube feedback signal is also transmitted to the CPT control circuit. The electrical parameters at least include DC, RF and the temperature of the TEC heating plate.

5. A CPT atomic clock according to claim 4, characterized in that: The TEC heating plate is used to heat or cool the VCSEL laser and maintain the temperature of the laser temperature box. The heating or cooling efficiency is determined by the direction and magnitude of the current passing through the TEC heating plate.

6. A CPT atomic clock according to claim 4, characterized in that: The VCSEL laser is used to generate coherent two-color light, and the operating temperature range is 31° C. to 65° C., so that the rubidium atoms in the alkali metal gas chamber are in a CPT coherent population trapping state, thereby generating a CPT phenomenon.

7. A CPT atomic clock according to claim 4, characterized in that: The alkali metal gas chamber is the core sensor of the CPT atomic clock, and produces the CPT phenomenon after being irradiated by two-color light of a specific band; The photoelectric tube is used to receive the optical signal emitted by the VCSEL laser and transmitted through the standard gas chamber component, convert it into an electrical signal and transmit it to the CPT control circuit.

8. The CPT atomic clock according to claim 4, characterized in that: The temperature sensor is used to feedback the temperature of the VCSEL laser; The C field coil is used to provide a stable magnetic field for the alkali metal gas chamber; The heating resistor network is used to heat the alkali metal gas chamber.

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