High-resolution one-dimensional range imaging method and system for frequency-stepped radar based on Rydberg atoms

Abstract

The present invention discloses a high-resolution one-dimensional range imaging method and system using a frequency-stepped radar based on Rydberg atoms. This method relates to the field of radar technology. By adding a direct current electric field to a Rydberg atom chamber and dynamically changing the magnitude of the direct current electric field, the DC-Stark effect is applied to control the atomic response to the microwave electric field frequency, thereby achieving real-time reception of stepped frequencies. To address the problem of low ranging resolution, the present invention modulates the Rydberg atom response to the microwave electric field frequency by regulating energy levels, achieving a GHz-level equivalent bandwidth. This method then synthesizes a high-bandwidth pulse signal through pulse synthesis, significantly improving the temporal resolution of the echo delay, thereby further resolving the technical challenge of low resolution in one-dimensional range imaging of Rydberg atoms.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and in particular to a high-resolution one-dimensional range imaging method and system for frequency-stepped radar based on Rydberg atoms. Background Art

[0002] Radar technology is widely used in military, aviation, aerospace, meteorology, and transportation fields. However, traditional radar receiving systems have some shortcomings, such as large size at low frequencies, difficulty in tracing the source, and sensitivity limited by Johnson-Nyquist noise. Quantum effect radar technology is expected to overcome these shortcomings. Rydberg atoms, as a highly excited state of atoms, have advantages such as extremely high sensitivity, ultra-wideband, and small size in precise electric field measurements, and are considered to be the key to future radar technology. However, due to the narrow instantaneous bandwidth of Rydberg atom receivers, their radar ranging resolution is low. This shortcoming greatly limits the development potential of Rydberg atom receivers. For example, the Chinese patent No. CN202110316684.6 processes echo signals within the extremely limited MHz-level instantaneous bandwidth of Rydberg atoms, resulting in low one-dimensional range imaging resolution. Summary of the Invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a high-resolution one-dimensional range imaging method and system for frequency-stepped radar based on Rydberg atoms, which solves the problem of low ranging resolution of existing radars based on Rydberg atom receivers.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0005] A method for high-resolution one-dimensional range imaging using a stepped frequency radar based on Rydberg atoms is provided, comprising the following steps:

[0006] S1. Exciting Rydberg atoms to a preset Rydberg energy level using probe light and coupled light, and experimentally establishing a voltage-response frequency mapping relationship within a Rydberg atomic chamber based on the DC-Stark effect; wherein the Rydberg atomic chamber is equipped with a pair of electrode plates for applying a DC electric field;

[0007] S2. Using a stepped frequency detection signal and a stepped frequency local oscillator signal, calibrate the corresponding relationship between the system response frequency, the detection field strength, and the heterodyne signal amplitude ratio for each frequency point through an experiment; wherein the stepped frequency detection signal and the stepped frequency local oscillator signal are in phase and have a fixed difference frequency;

[0008] S3. At the same time, a stepped frequency detection signal is transmitted toward the target object and a stepped frequency local oscillator signal is transmitted toward the atomic gas chamber, and a stepped voltage is input to the inner plate of the Rydberg atomic gas chamber based on the mapping relationship obtained in step S1, to obtain a signal obtained by mixing the stepped frequency detection signal returned to the Rydberg atomic gas chamber and the stepped frequency local oscillator signal transmitted toward the Rydberg atomic gas chamber;

[0009] S4, filtering out high-frequency components from the mixed signal in step S3 and sampling the mixed signal, processing the sampled signal based on the corresponding relationship obtained in step S2, and normalizing the processed result to obtain a normalized signal;

[0010] S5. Perform inverse Fourier transform on the normalized signals of different frequencies to form a one-dimensional range image of the target, thereby completing high-resolution one-dimensional range imaging.

[0011] Furthermore, the specific method of exciting the Rydberg atoms to the preset Rydberg energy level by using the detection light and the coupling light is as follows:

[0012] The cesium atoms were moved from the ground state 6S to the 1 / 2 Excited to the intermediate state 6P 3 / 2 Then, the cesium atoms are excited to the Rydberg state 62D by coupling light with a wavelength of 509nm. 5 / 2 .

[0013] Furthermore, in step S2, the expression for the corresponding relationship between the ratio of the system response frequency, the detection field strength, and the heterodyne signal amplitude is:

[0014]

[0015] in Indicates the k The detection field strength corresponding to each step frequency point; Indicates the calibration field strength; Indicates the k The calibration signal corresponding to each step frequency point; Indicates the k The detection signal corresponding to the stepped frequency points; N is the total number of stepped frequency points.

[0016] Furthermore, the expression of the mixed signal in step S3 is:

[0017]

[0018] in for t The signal after mixing at each moment; is the amplitude of the stepped frequency detection signal; is the amplitude of the stepped frequency local oscillator signal; , , N is the total number of step frequency points, π is radians, is the initial frequency of the stepped frequency detection signal, is the step size of the stepped frequency detection signal; , is the difference frequency between the stepped frequency detection signal and the stepped frequency local oscillator signal; is the echo delay, , R is the distance from the Rydberg atomic gas cell to the target object, c is the speed of light; is the initial phase of the stepped frequency detection signal; cos represents the cosine function.

[0019] Furthermore, the signal expression after filtering out the high-frequency components in step S4 is:

[0020]

[0021] in is the signal after high-frequency components are filtered out.

[0022] Furthermore, the sampling time point in step S4 , the sampled sequence is recorded as ;in i is the sampling sequence number; is the pulse repetition period; is the pulse width.

[0023] Furthermore, the expression of the processing result in step S4 is:

[0024]

[0025] in For the sequence The result obtained by processing; Indicates the calibration field strength;

[0026] The expression of the normalized signal in step S4 is:

[0027]

[0028] in For The signal obtained after normalization.

[0029] Furthermore, in step S5, the normalized signals of different frequencies are subjected to inverse Fourier transform to form a one-dimensional range image of the target, and the specific method for completing high-resolution one-dimensional range imaging includes the following sub-steps:

[0030] S5-1. Perform inverse Fourier transform on all normalized signals to complete signal synthesis and obtain the target one-dimensional range image. The expression of the target one-dimensional range image is:

[0031]

[0032] in is the one-dimensional range image of the target; is a sine function; l is the step time series index;

[0033] S5-2. Find the step time series index corresponding to the echo maximum in the target one-dimensional range image ;

[0034] S5-3. Index the step time series Substitute the following formula:

[0035]

[0036] The distance R from the Rydberg atomic gas cell to the target object is obtained, that is, high-resolution one-dimensional distance imaging is completed; j is the echo maximum index.

[0037] Provided is a system for implementing a high-resolution one-dimensional range imaging method of a frequency-stepped radar based on Rydberg atoms, comprising a Rydberg atom gas cell, a first microwave transmitter, a second microwave transmitter, a detection light transmitter, a coupled light transmitter, a photodetector, a power supply, and a host computer;

[0038] The Rydberg atomic gas cell comprises a transparent shell, and Rydberg atoms and an electrode plate pair arranged in the transparent shell; the electrode plate pair is connected to the output end of the power supply;

[0039] a detection light emitter, used for emitting detection light into the Rydberg atomic gas cell;

[0040] A coupled light emitter, used for emitting coupled light to the Rydberg atomic gas cell; wherein the coupled light and the detection light are coaxial and in opposite directions;

[0041] a photodetector, for receiving the detection light emitted from the Rydberg atomic gas cell and converting it into an electrical signal;

[0042] The first microwave transmitter is used to directly transmit the stepped frequency detection signal to the outside;

[0043] The second microwave transmitter is used to transmit a stepped-frequency local oscillator signal to the Rydberg atomic gas cell; wherein the frequencies of the stepped-frequency detection signal and the stepped-frequency local oscillator signal are both the transition frequencies of the Rydberg atoms after being excited by the detection light and the coupling light;

[0044] A power supply, used for providing a step voltage to the electrode plate pair, so as to form a step electric field between the electrode plates;

[0045] The electrode plate adjusts the response frequency of the Rydberg atoms by forming a step electric field, so that the photodetector can obtain light signals at different response frequencies;

[0046] The host computer is used to perform high-frequency filtering, sampling and normalization on the electrical signals of different frequencies output by the photodetector, and perform inverse Fourier transform on the normalized electrical signals to form a one-dimensional range image of the target, thereby completing high-resolution one-dimensional range imaging.

[0047] The beneficial effects of the present invention are:

[0048] 1. This invention adds a DC electric field to the Rydberg atomic chamber and dynamically modulates the DC-Stark effect to control the atomic response to the microwave electric field frequency, achieving real-time stepped frequency reception. To address the issue of low ranging resolution, atomic mixing is employed to modulate the received signal to an intermediate frequency. Pulse synthesis and inverse Fourier transform are then used to generate a one-dimensional range profile of the detected target.

[0049] 2. The present invention changes the frequency of the Rydberg atom's response to the microwave electric field by regulating the energy level, achieving an equivalent bandwidth of the GHz level, thereby synthesizing a large-bandwidth pulse signal through pulse synthesis, greatly improving the time resolution of the echo delay, and further solving the technical problem of low resolution of one-dimensional distance imaging of Rydberg atoms.

[0050] 3. The corresponding relationship between the ratio of the response frequency of the calibration system, the detection field strength and the heterodyne signal amplitude of the present invention can overcome the problem of different pulse comprehensive amplitude benchmarks after the Rydberg atom far-detuned field frequency modulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Schematic diagram of the process of this method;

[0052] Figure 2 is the transition frequency offset and electric field strength (62D 5 / 2 To 63P 3 / 2 ) relationship curve;

[0053] Figure 3 This is the simulation diagram for the system calibration;

[0054] Figure 4 Schematic diagram of the imaging scene of this system. DETAILED DESCRIPTION

[0055] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0056] like Figure 1 As shown, the high-resolution one-dimensional range imaging method based on Rydberg atom-based frequency stepped radar includes the following steps:

[0057] S1. Exciting Rydberg atoms to a preset Rydberg energy level using probe light and coupled light, and experimentally establishing a voltage-response frequency mapping relationship within a Rydberg atomic chamber based on the DC-Stark effect; wherein the Rydberg atomic chamber is equipped with a pair of electrode plates for applying a DC electric field;

[0058] S2. Using a stepped frequency detection signal and a stepped frequency local oscillator signal, calibrate the corresponding relationship between the system response frequency, the detection field strength, and the heterodyne signal amplitude ratio for each frequency point through an experiment; wherein the stepped frequency detection signal and the stepped frequency local oscillator signal are in phase and have a fixed difference frequency;

[0059] S3. At the same time, a stepped frequency detection signal is transmitted toward the target object and a stepped frequency local oscillator signal is transmitted toward the atomic gas chamber, and a stepped voltage is input to the inner plate of the Rydberg atomic gas chamber based on the mapping relationship obtained in step S1, to obtain a signal obtained by mixing the stepped frequency detection signal returned to the Rydberg atomic gas chamber and the stepped frequency local oscillator signal transmitted toward the Rydberg atomic gas chamber;

[0060] S4, filtering out high-frequency components from the mixed signal in step S3 and sampling the mixed signal, processing the sampled signal based on the corresponding relationship obtained in step S2, and normalizing the processed result to obtain a normalized signal;

[0061] S5. Perform inverse Fourier transform on the normalized signals of different frequencies to form a one-dimensional range image of the target, thereby completing high-resolution one-dimensional range imaging.

[0062] In this embodiment, the specific method of exciting the Rydberg atoms to the preset Rydberg energy level by using the detection light and the coupling light is:

[0063] The cesium atoms were moved from the ground state 6S to the 1 / 2 Excited to the intermediate state 6P 3 / 2 Then, the cesium atoms are excited to the Rydberg state 62D by coupling light with a wavelength of 509nm. 5 / 2 The photoelectric signal shows an EIT spectrum line, and one of the microwave electric field frequencies that the cesium atom responds to corresponds to 62D5 / 2 Jump to 63P 3 / 2 The transition frequency is 2.911 GHz. When a microwave electric field with a frequency of 2.911 GHz acts on the atomic gas chamber, the EIT spectrum line peak splits to form two transmission peaks. The electric field intensity of the microwave electric field can be calculated by the following formula:

[0064] (1)

[0065] in, represents the reduced Planck constant; represents the transition dipole moment; The Rabi frequency of the microwave electric field can be determined by the double peak spacing of the detection spectrum. Calculated by the following formula:

[0066] (2)

[0067] Due to the large dipole moment of the Rydberg states, they are highly polarizable. Axial DC electric field The atoms in , the interaction leads to a coupling given by:

[0068] (3)

[0069] in, is the unperturbed energy level in Hamiltonian of spherical basis. At this time, the relationship between the DC electric field strength and the spacing acting on the Rydberg atomic gas cell is similar to (1) and (2).

[0070] Since the DC electric field causes the shift of the atomic energy level, which in turn causes the change of the response frequency, the relationship curve between the DC electric field strength and the response frequency is established through experiments. 5 / 2 , m j = 1 / 2 jumps to 63P 3 / 2 , m j =1 / 2 The relationship between the transition frequency offset and the electric field strength is as follows Figure 2 As shown in the figure, it can be seen that by applying a DC electric field of 1.2 V / cm, a response frequency shift of about 5 GHz can be achieved. By designing a lower intermediate state or Rydberg state, a wider adjustable frequency range can be achieved.

[0071] In this embodiment, a cesium atomic gas chamber with a built-in electrode plate pair is used to apply a DC electric field to the Rydberg atoms. The strength of the DC electric field is calculated by applying an external voltage and formula (4):

[0072] (4)

[0073] in is the DC electric field intensity in the gas chamber; is the applied voltage; is the distance between the electrode plates, from which the relationship between the applied voltage outside the Rydberg atom chamber and the Rydberg atom response frequency can be obtained.

[0074] It should be noted that the excitation examples given in this embodiment are only examples and are not the only operation. In addition to the above-mentioned cesium atoms and their excitation process, other Rydberg atoms and other excitation methods can also be used. The Rydberg atom chamber applied voltage-response frequency mapping relationship based on the DC-Stark effect can be established through experiments.

[0075] In step S2, a stepped frequency detection signal is designed in advance according to actual detection requirements. Assuming that the stepped frequency detection signal can be called a SIG field (signal field), it can be expressed as:

[0076] (5)

[0077] in, is the signal transmission time; Indicates the initial phase of the signal; Indicates the amplitude of the transmitted signal; , Indicates the initial frequency, that is, the transmitted signal It is a Sampling points, the frequency is Increasing step frequency SIG field signal. For specific calibration system, see Figure 3 (The red line is the detection light, and the green line is the coupled light). The stepped frequency detection signal of arbitrary power is emitted to the Rydberg atomic gas cell. Based on the electric field strength measurement method of step S1, the double peak spacing of the detection spectrum under the SIG field is measured. According to formulas (1) and (2), the SIG field strength value is obtained. .

[0078] The stepped frequency local oscillator signal designed in advance to be in phase with the stepped frequency detection signal and with a fixed frequency difference can be called the LO field (local oscillator field) and can be expressed as:

[0079] (6)

[0080] in, Expressed as the amplitude of the stepped frequency local oscillator signal; , is the difference frequency between the SIG field and the LO field, which can be set to 10MHz; It is the step frequency index.

[0081] Based on the relationship between the applied voltage outside the Rydberg atom gas chamber and the Rydberg atom response frequency in step S1, the applied step voltage signal corresponding to the SIG field step frequency local oscillator signal is obtained, which is expressed as follows:

[0082] (7)

[0083] in, represents the initial voltage; represents the step voltage; the LO field and the SIG field are co-polarized and emitted to the Rydberg atomic gas cell at the same time. The electric field intensity acting on the Rydberg atomic gas cell can be expressed as:

[0084] (8)

[0085] in, 、 It represents the field strength of SIG and LO fields acting on the atomic gas cell; It represents the phase difference between the LO field and the SIG field reaching the gas cell and does not need to be considered in the calibration process of this step.

[0086] The transmission power of the detection light passing through the gas cell has the following relationship:

[0087] (9)

[0088] Extracting photodetector signals The frequency component, let its amplitude be , when the applied voltage on the electrode plate of the Rydberg atomic gas cell remains unchanged, it can be considered that:

[0089] (10)

[0090] Therefore, under the condition of applying voltage to the gas cell plates, assuming that the Rydberg atomic gas cell response frequency and the step frequency detection signal The relationship between the amplitudes of the frequency components is:

[0091] (11)

[0092] The ratio of the signal field strength to the measured signal amplitude is a frequency-dependent function. The single-frequency SIG field with a frequency of Single frequency LO field, external voltage Use simultaneous output to record the detection signal corresponding to each step frequency point , the corresponding relationship between the ratio of system response frequency-detection field strength and heterodyne signal amplitude can be expressed as:

[0093] (12)

[0094] in Indicates the k The detection field strength corresponding to each step frequency point; Indicates the calibration field strength; Indicates the k The calibration signal corresponding to each step frequency point; Indicates the k The detection signal corresponding to the stepped frequency points; N is the total number of stepped frequency points.

[0095] In this embodiment, the ranging scenario is as follows Figure 4 As shown, at the same time, a step-frequency detection signal is transmitted toward the target object, a step-frequency local oscillation signal is transmitted toward the atomic gas chamber, and a step voltage is input to the inner plate of the Rydberg atomic gas chamber based on the mapping relationship obtained in step S1. The detection echo signal received by the Rydberg atomic gas cell at time t is:

[0096] (13)

[0097] in, is the echo delay, and its value is , is the distance from the gas chamber to the target; the distances from the SIG field and LO field microwave transmitters to the Rydberg atomic gas chamber are equal.

[0098] The signal field is reflected by the target, and the signal returned to the Rydberg atomic gas cell and mixed with the stepped frequency local oscillator signal emitted toward the Rydberg atomic gas cell is:

[0099] (14)

[0100] in for t The signal after mixing at each moment; is the amplitude of the stepped frequency detection signal; is the amplitude of the stepped frequency local oscillator signal; , , N is the total number of step frequency points, π is radians, is the initial frequency of the stepped frequency detection signal, is the step size of the stepped frequency detection signal; , is the initial phase of the stepped frequency detection signal; cos represents the cosine function.

[0101] The signal expression after filtering out the high-frequency components in step S4 is:

[0102] (15)

[0103] in is the signal after high-frequency components are filtered out.

[0104] The sampling time point of the signal after filtering out the high-frequency components in step S4 , the sampled sequence is recorded as ;in is the sampling sequence number; is the pulse repetition period; is the pulse width.

[0105] In step S4, the sampled signal is processed based on the corresponding relationship obtained in step S2, and the expression of the processing result is:

[0106] (16)

[0107] in For the sequence The result obtained by processing; Indicates the calibration field strength;

[0108] The expression of the normalized signal in step S4 is:

[0109] (17)

[0110] in For The signal obtained after normalization.

[0111] In step S5, the normalized signals of different frequencies are subjected to inverse Fourier transform to form a one-dimensional range image of the target, and the specific method for completing high-resolution one-dimensional range imaging includes the following sub-steps:

[0112] S5-1. Perform inverse Fourier transform on all normalized signals to complete signal synthesis and obtain the target one-dimensional range image. The expression of the target one-dimensional range image is:

[0113] (18)

[0114] in is the one-dimensional range image of the target; is a sine function; is the step time series index;

[0115] S5-2. Find the step time series index corresponding to the echo maximum in the target one-dimensional range image ; where the echo maximum appears at:

[0116] (19)

[0117] S5-3. The result of pulse synthesis is a main lobe with a width of The sinc function type narrow pulse. The horizontal coordinate of the peak position of the one-dimensional range image contains the distance information, that is:

[0118] (20)

[0119] The distance R from the Rydberg atomic gas cell to the target object is obtained, that is, high-resolution one-dimensional distance imaging is completed; j is the echo maximum index.

[0120] It should be noted that although the distance R from the Rydberg atomic cell to the target object can be directly calculated starting from Equation 16, since the propagation speed of microwaves is equal to the speed of light, the round-trip time of the stepped-frequency detection signal is extremely short (usually in the nanosecond range), resulting in low accuracy. Therefore, the sampled signal is processed using the corresponding relationship obtained in step S2, and the processing result is normalized. The normalized signal is then subjected to an inverse Fourier transform to form a one-dimensional range image of the target, achieving high-resolution one-dimensional range imaging.

[0121] The system for implementing a high-resolution one-dimensional range imaging method of a frequency-stepped radar based on Rydberg atoms includes a Rydberg atom gas chamber, a first microwave transmitter, a second microwave transmitter, a detection light transmitter, a coupled light transmitter, a photodetector, a power supply, and a host computer;

[0122] The Rydberg atomic gas cell comprises a transparent shell, and Rydberg atoms and an electrode plate pair arranged in the transparent shell; the electrode plate pair is connected to the output end of the power supply;

[0123] a detection light emitter, used for emitting detection light into the Rydberg atomic gas cell;

[0124] A coupled light emitter, used for emitting coupled light to the Rydberg atomic gas cell; wherein the coupled light and the detection light are coaxial and in opposite directions;

[0125] a photodetector, for receiving the detection light emitted from the Rydberg atomic gas cell and converting it into an electrical signal;

[0126] The first microwave transmitter is used to directly transmit the stepped frequency detection signal to the outside;

[0127] The second microwave transmitter is used to transmit a stepped-frequency local oscillator signal to the Rydberg atomic gas cell; wherein the frequencies of the stepped-frequency detection signal and the stepped-frequency local oscillator signal are both the transition frequencies of the Rydberg atoms after being excited by the detection light and the coupling light;

[0128] A power supply, used for providing a step voltage to the electrode plate pair, so as to form a step electric field between the electrode plates;

[0129] The electrode plate adjusts the response frequency of the Rydberg atoms by forming a step electric field, so that the photodetector can obtain light signals at different response frequencies;

[0130] The host computer is used to perform high-frequency filtering, sampling and normalization on the electrical signals of different frequencies output by the photodetector, and perform inverse Fourier transform on the normalized electrical signals to form a one-dimensional range image of the target, thereby completing high-resolution one-dimensional range imaging.

[0131] In summary, the present invention achieves real-time reception of stepped frequencies by adding a DC electric field to the Rydberg atomic chamber and dynamically varying the DC electric field's magnitude using the DC-Stark effect to control the atomic response to the microwave electric field. To address the issue of low ranging resolution, an atomic mixing method is employed to modulate the received signal to an intermediate frequency. A one-dimensional range profile of the detected target is then generated through pulse synthesis and inverse Fourier transform.

Claims

1. A high-resolution one-dimensional range imaging method based on Rydberg atom-based frequency-stepped radar, characterized in that: The following steps are involved: S1. Exciting Rydberg atoms to a preset Rydberg energy level using probe light and coupled light, and experimentally establishing a voltage-response frequency mapping relationship within a Rydberg atomic chamber based on the DC-Stark effect; wherein the Rydberg atomic chamber is equipped with a pair of electrode plates for applying a DC electric field; S2. Using a stepped frequency detection signal and a stepped frequency local oscillator signal, calibrate the corresponding relationship between the system response frequency, the detection field strength, and the heterodyne signal amplitude ratio for each frequency point through an experiment; wherein the stepped frequency detection signal and the stepped frequency local oscillator signal are in phase and have a fixed difference frequency; S3. At the same time, a stepped frequency detection signal is transmitted toward the target object and a stepped frequency local oscillator signal is transmitted toward the atomic gas chamber, and a stepped voltage is input to the inner plate of the Rydberg atomic gas chamber based on the mapping relationship obtained in step S1, to obtain a signal obtained by mixing the stepped frequency detection signal returned to the Rydberg atomic gas chamber and the stepped frequency local oscillator signal transmitted toward the Rydberg atomic gas chamber; S4, filtering out high-frequency components from the mixed signal in step S3 and sampling the mixed signal, processing the sampled signal based on the corresponding relationship obtained in step S2, and normalizing the processed result to obtain a normalized signal; S5. Perform inverse Fourier transform on the normalized signals of different frequencies to form a one-dimensional range image of the target, thereby completing high-resolution one-dimensional range imaging; The expression corresponding to the ratio of the system response frequency-detection field strength and the heterodyne signal amplitude in step S2 is: in Indicates the k The detection field strength corresponding to each step frequency point; Indicates the calibration field strength; Indicates the k The calibration signal corresponding to each step frequency point; Indicates the k The detection signal corresponding to the step frequency points; N is the total number of step frequency points; The expression of the mixed signal in step S3 is: in for t The signal after mixing at each moment; is the amplitude of the stepped frequency detection signal; is the amplitude of the stepped frequency local oscillator signal; , , N is the total number of step frequency points, π is radians, is the initial frequency of the stepped frequency detection signal, is the step size of the stepped frequency detection signal; , is the difference frequency between the stepped frequency detection signal and the stepped frequency local oscillator signal; is the echo delay, , R is the distance from the Rydberg atomic gas cell to the target object, c is the speed of light; is the initial phase of the stepped frequency detection signal; cos represents the cosine function.

2. The high-resolution one-dimensional range imaging method based on Rydberg atom frequency stepped radar according to claim 1, characterized in that: The specific method of exciting Rydberg atoms to a preset Rydberg energy level by using detection light and coupling light is as follows: The cesium atoms were moved from the ground state 6S to the 1 / 2 Excited to the intermediate state 6P 3 / 2 Then, the cesium atoms are excited to the Rydberg state 62D by coupling light with a wavelength of 509nm. 5 / 2 .

3. The high-resolution one-dimensional range imaging method based on Rydberg atom frequency stepped radar according to claim 1, characterized in that: The signal expression after filtering out the high-frequency components in step S4 is: in is the signal after high-frequency components are filtered out.

4. The high-resolution one-dimensional range imaging method based on Rydberg atom frequency stepped radar according to claim 3, characterized in that: Sampling time point in step S4 , the sampled sequence is recorded as ;in i is the sampling sequence number; is the pulse repetition period; is the pulse width.

5. The high-resolution one-dimensional range imaging method based on Rydberg atom frequency stepped radar according to claim 4, characterized in that: The expression of the processing result in step S4 is: in For the sequence The result obtained by processing; Indicates the calibration field strength; The expression of the normalized signal in step S4 is: in For The signal obtained after normalization.

6. The high-resolution one-dimensional range imaging method based on Rydberg atom-based frequency stepped radar according to claim 5, characterized in that: In step S5, the normalized signals of different frequencies are subjected to inverse Fourier transform to form a one-dimensional range image of the target, and the specific method for completing high-resolution one-dimensional range imaging includes the following sub-steps: S5-1. Perform inverse Fourier transform on all normalized signals to complete signal synthesis and obtain the target one-dimensional range image. The expression of the target one-dimensional range image is: in is the one-dimensional range image of the target; is a sine function; l is the step time series index; S5-2. Find the step time series index corresponding to the echo maximum in the target one-dimensional range image ; S5-3. Index the step time series Substitute the following formula: The distance R from the Rydberg atomic gas cell to the target object is obtained, that is, high-resolution one-dimensional distance imaging is completed; j is the echo maximum index.

7. A system for implementing the Rydberg atom-based frequency stepped radar high-resolution one-dimensional range imaging method according to any one of claims 1 to 6, characterized in that: It includes a Rydberg atomic gas chamber, a first microwave transmitter, a second microwave transmitter, a detection light transmitter, a coupled light transmitter, a photodetector, a power supply and a host computer; The Rydberg atomic gas cell comprises a transparent shell, and Rydberg atoms and an electrode plate pair arranged in the transparent shell; the electrode plate pair is connected to the output end of the power supply; a detection light emitter, used for emitting detection light into the Rydberg atomic gas cell; A coupled light emitter, used for emitting coupled light to the Rydberg atomic gas cell; wherein the coupled light and the detection light are coaxial and in opposite directions; a photodetector, for receiving the detection light emitted from the Rydberg atomic gas cell and converting it into an electrical signal; The first microwave transmitter is used to directly transmit the stepped frequency detection signal to the outside; The second microwave transmitter is used to transmit a stepped-frequency local oscillator signal to the Rydberg atomic gas cell; wherein the frequencies of the stepped-frequency detection signal and the stepped-frequency local oscillator signal are both the transition frequencies of the Rydberg atoms after being excited by the detection light and the coupling light; A power supply, used for providing a step voltage to the electrode plate pair, so as to form a step electric field between the electrode plates; The electrode plate adjusts the response frequency of the Rydberg atoms by forming a step electric field, so that the photodetector can obtain light signals at different response frequencies; The host computer is used to perform high-frequency filtering, sampling and normalization on the electrical signals of different frequencies output by the photodetector, and perform inverse Fourier transform on the normalized electrical signals to form a one-dimensional range image of the target, thereby completing high-resolution one-dimensional range imaging.

Images