A method for detecting three-dimensional information of a scene and a radar system

Abstract

The application provides a method for detecting three-dimensional information of a scene and a radar system, wherein the radar system comprises: a quantum light source module, which is used for generating frequency-correlated first and second photons by using a pump light pulse and obtaining an output time of the pump light pulse; a first photon emission and reception module, which is used for emitting the first photons to different spatial directions through spatial dispersion and obtaining a time when a first photon reflected by a to-be-detected scene and returned along the original path is detected; a second photon emission and reception module, which is used for dispersing the second photons through time dispersion and obtaining a time when the second photons dispersed through time dispersion are detected; and a data processing module, which is used for obtaining a three-dimensional image of the to-be-detected scene according to the output time and the times when the first and second photons are detected. The application solves the defect that the optical quantum radar in the prior art needs to be combined with mechanical scanning to realize the radar function, realizes the photon counting radar function without mechanical beam scanning, and improves the detection sensitivity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical quantum technology, and in particular to a method for detecting three-dimensional information of a scene and a radar system. BACKGROUND

[0002] Photon counting radar based on photon time-of-flight (ToF) measurement can obtain three-dimensional scene information of an environment, and is an important means of environmental information perception. After years of development, the photon counting radar technology has gradually encountered bottlenecks in physical implementation, detection sensitivity and system volume, and new technical breakthroughs are needed.

[0003] The optical quantum radar in the photon counting radar uses a photon stream in a specific optical quantum state to irradiate an environment to obtain depth information of the environment. Theoretical analysis shows that the quantum correlation and quantum entanglement characteristics contained in the optical quantum state, combined with effective quantum measurement methods, can greatly improve the detection sensitivity of the photon counting radar. However, although there have been some experimental research reports on using optical quantum states to improve radar performance, they are generally in the stage of theoretical demonstration, and there is still a long way to go before practical application.

[0004] Currently, the optical quantum radar needs to be combined with mechanical scanning to obtain depth information of the environment on the basis of the ranging function. However, mechanical scanning structures are often easily damaged, have a short service life, and have limited scanning accuracy and speed, so this method does not conform to the current trend of full solidification and chip integration of photon counting radars, limiting the application of this technology in many scenarios. SUMMARY

[0005] The present application provides a radar system and method for detecting three-dimensional information of a scene to solve the defect that the optical quantum radar needs to be combined with mechanical scanning to detect three-dimensional information of a scene in the prior art, to realize the function of the photon counting radar without mechanical beam scanning, and to improve the detection sensitivity.

[0006] The present application also provides a radar system for detecting three-dimensional information of a scene, comprising:

[0007] A quantum light source module for generating frequency-correlated first photons and second photons using a pump light pulse, and obtaining the output time of the pump light pulse;

[0008] A first photon emission and reception module for emitting the first photons to different spatial directions through spatial dispersion, and obtaining the time when the first photons reflected by the scene to be detected and returned along the original path are detected by a first single-photon detector as a first detection time;

[0009] a second photon emission and receiving module, configured to time-disperse the second photon, and obtain a time when the time-dispersed second photon is detected by a second single-photon detector as a second detection time;

[0010] a data processing module, configured to obtain a three-dimensional image of the to-be-detected scene according to the output time, the first detection time, and the second detection time.

[0011] According to the radar system for detecting three-dimensional information of a scene provided in the application, the quantum light source module comprises: a pump light pulse, a nonlinear optical material unit, and a frequency distribution unit.

[0012] The pump light pulse is configured to irradiate the nonlinear optical material unit.

[0013] The nonlinear optical material unit is configured to generate a pair of frequency-correlated photons by using the incident pump light pulse.

[0014] The frequency distribution unit is configured to separate the pair of frequency-correlated photons into the first photon and the second photon.

[0015] According to the radar system for detecting three-dimensional information of a scene provided in the application, the quantum light source module further comprises: a photoelectric detection module.

[0016] The photoelectric detection module is configured to generate an electrical signal containing the output time according to a residual pump light pulse, and input the electrical signal into the data processing module.

[0017] The residual pump light pulse is a residual pump light pulse after the nonlinear optical material is excited to generate a pair of frequency-correlated photons.

[0018] According to the radar system for detecting three-dimensional information of a scene provided in the application, the first photon emission and receiving module specifically comprises: an optical path adjustment unit, a spatial dispersion element, a beam-expanding element, and a first single-photon detector.

[0019] The optical path adjustment unit is configured to collimate the first photon to obtain collimated light, and input the first photon returned by the spatial dispersion element into the first single-photon detector.

[0020] The spatial dispersion element is configured to make the collimated light propagate in different spatial directions according to different wavelengths, and return the first photon returned by the beam-expanding element to the optical path adjustment unit.

[0021] The beam-expanding element is configured to expand the first photon propagating in different spatial directions, and after converging the first photon reflected back due to irradiation of the to-be-detected scene, return the first photon to the spatial dispersion element.

[0022] The first single-photon detector is used to detect the first photon reflected by the to-be-detected scene and returned along the original path to obtain the first detection time.

[0023] The second-photon emission and receiving module specifically comprises a time dispersion element and a second single-photon detector.

[0024] The time dispersion element is used to perform time dispersion on the second photon.

[0025] The second single-photon detector is used to detect the second photon after time dispersion to obtain the second detection time.

[0026] The present application further provides a method for detecting three-dimensional information of a scene, comprising:

[0027] First and second photons in frequency correlation are generated by using a pump light pulse, and an output time of the pump light pulse is obtained.

[0028] The first photon is emitted to different spatial directions after spatial dispersion, and a time when the first photon reflected by a to-be-detected scene and returned along the original path is detected by a first single-photon detector is obtained as a first detection time.

[0029] The second photon is subjected to time dispersion, and a time when the second photon after time dispersion is detected by a second single-photon detector is obtained as a second detection time.

[0030] A three-dimensional image of the to-be-detected scene is obtained according to the output time, the first detection time, and the second detection time.

[0031] The method for detecting three-dimensional information of a scene provided by the present application specifically comprises:

[0032] The nonlinear optical material is excited by using the pump light pulse to generate a frequency-correlated photon pair.

[0033] The frequency-correlated photon pair is separated into the first and second photons by optical filtering.

[0034] The method for detecting three-dimensional information of a scene provided by the present application specifically comprises:

[0035] After the frequency-correlated photon pair is generated by exciting the nonlinear optical material, the remaining pump light pulse is subjected to photoelectric detection to obtain an electric signal containing the output time.

[0036] The output time is obtained from the electric signal.

[0037] The method for detecting three-dimensional information of a scene according to the present application, wherein the three-dimensional image of the scene to be detected is obtained according to the output time, the first detection time, and the second detection time, specifically includes:

[0038] The wavelength of the second photon is obtained according to the output time, the second detection time, and the dispersion amount of the time dispersion;

[0039] The wavelength of the first photon is obtained according to the wavelength of the second photon and the wavelength of the pump light pulse;

[0040] The angle information of the scene to be detected relative to the irradiation direction of the first photon is obtained according to the wavelength of the first photon;

[0041] The depth information of the scene to be detected is obtained according to the wavelength of the first photon, the output time, and the first detection time.

[0042] The method for detecting three-dimensional information of a scene according to the present application, wherein the first photon and the second photon are generated by using a pump light pulse, and the method includes:

[0043] The first photon and the second photon are generated by using a pump light pulse periodically;

[0044] After the three-dimensional image of the scene to be detected is obtained according to the output time, the first detection time, and the second detection time, the method for detecting three-dimensional information of a scene further includes:

[0045] The three-dimensional image of the scene to be detected obtained in the current period is fused with the three-dimensional image of the scene to be detected obtained in at least one historical period.

[0046] The radar system and method for detecting three-dimensional information of a scene according to the present application, on one hand, the quantum correlation between the first photon and the second photon is used to filter single-photon detection data, thereby reducing the influence of noise counting events and improving the detection sensitivity; on the other hand, the frequency correlation characteristics between the first photon and the second photon are used to realize the photon counting radar function without mechanical beam scanning. At the same time, since the requirement of mechanical scanning is eliminated, the potential of realizing system chip integration by using chip-integrated quantum light sources and optical quantum chip technology is realized, which provides a feasible solution for the miniaturization of the photon counting radar. In addition, the light intensity of the irradiation space is only at the single-photon level, which is not easy to be discovered by the target during operation, and is particularly suitable for application scenarios with high requirements for system concealment. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0048] Figure 1 is a structural schematic diagram of a radar system for detecting three-dimensional information of a scene provided by the present application;

[0049] Figure 2 is a working principle diagram of a quantum light source module provided by the present application;

[0050] Figure 3 is a working principle diagram of a first photon emission and reception module provided by the present application;

[0051] Figure 4 is a distribution diagram of an object to be imaged in space in an example provided by the present application;

[0052] Figure 5 is a three-dimensional imaging result of an object to be imaged in an example provided by the present application; Figure 4

[0053] Figure 6 is a flowchart of a method for detecting three-dimensional information of a scene provided by the present application. DETAILED DESCRIPTION

[0054] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely in combination with the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, but not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort belong to the protection scope of the present application.

[0055] The present application provides a radar system for detecting three-dimensional information of a scene, and a method for detecting three-dimensional information of a scene. Figure 1 The radar system comprises a quantum light source module 110, a first photon emission and reception module 120, a second photon emission and reception module 130 and a data processing module 140. Figure 1 The quantum light source module 110 is used for generating frequency-correlated first photons and second photons by using a pump light pulse, and obtaining an output time of the pump light pulse.

[0056] The quantum light source module 110 is used for generating frequency-correlated first photons and second photons by using a pump light pulse, and obtaining an output time of the pump light pulse.

[0057] ​It should be noted that the frequencies of the first photon and the second photon generated by the quantum light source module have a symmetrical relationship with respect to the frequency of the pump light pulse, and based on the corresponding relationship between frequency and wavelength, the wavelengths of the first photon and the second photon also have a corresponding relationship. Specifically, if the wavelength of the pump light pulse is 1550 nm, two 1550 nm photons will generate one photon greater than 1550 nm and one photon less than 1550 nm, and the wavelengths of the two photons are equal to the difference from 1550 nm. For example, two 1550 nm photons can generate two photons of 1530 nm and 1570 nm.

[0058] The first photon emission and reception module 120 is configured to emit the first photons to different spatial directions by using spatial dispersion, and obtain the time when the first photon reflected by the to-be-measured scene and returned along the original path is detected by the first single-photon detector as the first detection time.

[0059] It should be noted that the first photon emission and reception module emits the first photons to different spatial directions by using spatial dispersion, which is achieved by using spatial dispersion elements such as a diffraction grating, a blazed grating, an optical prism, or a spatial light modulator. Under the action of the spatial dispersion element, first photons of different wavelengths can be emitted to different spatial directions. The first photons irradiating the to-be-measured scene from different spatial directions are reflected by the to-be-measured scene.

[0060] It can be understood that when the first photons are subjected to spatial dispersion, the first photons are emitted to a specific spatial direction based on frequency. When it is necessary to detect the first photons reflected by the irradiated to-be-measured scene, the first photons returned from different directions also need to be returned along the original path by using spatial dispersion. At this time, the reflected first photons can be detected by using the first single-photon detector, and thus the time when the reflected first photons are detected, i.e., the first detection time, can be obtained.

[0061] The second photon emission and reception module 130 is configured to subject the second photons to time dispersion, and obtain the time when the second photons subjected to time dispersion are detected by the second single-photon detector as the second detection time.

[0062] It should be noted that the second photon emission and reception module subjects the second photons to time dispersion, which can be achieved by using time dispersion elements such as a single-mode fiber with large group velocity dispersion, a long-period grating, a diffraction grating pair, and a dispersion compensation module. Similarly, the second photons subjected to time dispersion can also be detected by using a single-photon detector.

[0063] It can be understood that, after time dispersion, the second photons of different wavelengths also arrive at the single-photon detector at different times, and thus the time at which the second single-photon detector detects the second photon can correspond to the wavelength of the second photon.

[0064] The data processing module 140 is configured to obtain a three-dimensional image of the to-be-detected scene according to the output time, the first detection time, and the second detection time.

[0065] It should be noted that, the output time, the first detection time, and the second detection time are used to obtain a photon count of depth information of an object causing reflection of the first photon.

[0066] Specifically, in the radar system for detecting three-dimensional information of a scene provided in the application, the first photon is used to detect the to-be-detected scene, the influence of noise counting events is reduced, and the sensitivity of detection is improved, then the time at which the second photon associated with the first photon is detected after time dispersion, the output time of the pump light pulse, and the time at which the first photon is detected after being reflected after irradiating the to-be-detected scene are used to obtain depth information of the to-be-detected scene causing reflection of the first photon, and then a three-dimensional image of the to-be-detected scene is obtained, and a photon counting radar function without mechanical beam scanning is realized. At the same time, since the requirement of mechanical scanning is eliminated, the potential of realizing system chip integration by using chip-integrated quantum light sources and optical quantum chip technology is achieved, and a feasible scheme for miniaturization of the photon counting radar is provided. In addition, the light intensity of the irradiation space is only at a single-photon level, and the system is not easy to be discovered by a target during operation, and is particularly suitable for application scenarios with high requirements for system concealment.

[0067] In an embodiment of the application, the quantum light source module specifically comprises: a pump light pulse, a nonlinear optical material, and a frequency distribution unit.

[0068] The pump light pulse is used to irradiate the nonlinear optical material unit.

[0069] The nonlinear optical material unit is used to generate a frequency-correlated photon pair by using the incident pump light pulse.

[0070] The frequency distribution unit is used to separate the frequency-correlated photon pair into the first photon and the second photon.

[0071] It should be noted that, the frequency-correlated photon pair is generated by exciting a spontaneous nonlinear parametric process in the nonlinear optical material unit by the pump light pulse, and is a wide-spectrum frequency-correlated photon pair. The two photons constituting the photon pair can be separated by the frequency distribution unit, and then the first photon and the second photon are obtained.

[0072] Specifically, the nonlinear optical material unit includes a nonlinear optical crystal generating a second-order parametric down-conversion effect and a nonlinear optical waveguide generating a third-order spontaneous four-wave mixing effect. The nonlinear optical crystal is various nonlinear optical crystals of non-centrosymmetric lattice structures, including but not limited to lithium niobate crystals, lithium niobate waveguides, gallium arsenide, and indium phosphide. The nonlinear optical waveguide includes but is not limited to quartz optical fibers, sulfide glass optical fibers, silicon waveguides, and silicon nitride waveguides.

[0073] In another embodiment of the present application, the quantum light source module further includes a photodetector module;

[0074] The photodetector module is configured to generate an electrical signal containing the output time from the residual pump light pulse and input the electrical signal into the data processing module;

[0075] The residual pump light pulse is the residual pump light pulse after the nonlinear optical material is excited to generate a frequency-correlated photon pair.

[0076] It should be noted that the pump light pulse has the output time information when it is generated, that is, the generation time of the pump light pulse. By detecting the pump light pulse through the photodetector, an electrical signal containing the output time can be obtained, and the output time of the pump light pulse can be easily obtained from the electrical signal.

[0077] Specifically, the principle of generating the first photon, the second photon, and the electrical signal containing the output time through the quantum light source module is as shown in Figure 2 That is, the pump light pulse is input into the nonlinear optical material unit, the generated frequency-correlated photon is input into the frequency distribution unit 2, the first photon and the second photon are generated, and the residual pump light passes through the photodetector 3 to generate an electrical signal containing the output time.

[0078] In another embodiment, the composition of the first photon emission and reception module is specifically described, which includes an optical path adjustment unit, a spatial dispersion element, a beam expander, and a first single-photon detector.

[0079] The optical path adjustment unit is configured to collimate the first photon to obtain collimated light and input the first photon returned by the spatial dispersion element into the first single-photon detector;

[0080] The spatial dispersion element is configured to make the collimated light propagate in different spatial directions according to different wavelengths and return the first photon returned by the beam expander to the optical path adjustment unit;

[0081] The beam expanding element is configured to expand the first photons propagating in different spatial directions, and to converge the first photons reflected back after irradiating the to-be-measured scene, and return the converged first photons to the spatial dispersion element.

[0082] The first single-photon detector is configured to detect the first photons reflected by the to-be-measured scene and returned along the original path to obtain the first detection time.

[0083] It should be noted that, in order to further facilitate the emission of the first photons to the optical path adjusting unit and the collection after returning, a photon emission and collection element can also be arranged in the first photon emission and receiving module, so as to facilitate the reception of the first photons by the quantum light source module, the emission to the optical path adjusting unit, and the sending of the first photons reflected by the to-be-measured scene collected by the optical path adjusting unit to the first single-photon detector.

[0084] Specifically, taking the photon emission and collection element as a circulator 4, the optical path adjusting unit as a fiber collimator 5, the spatial dispersion element as a blazed grating 6, the beam expanding element as a lens 7, and the first single-photon detector as a single-photon detector 8 as an example, the working principle of the first photon emission and receiving module is as shown in Figure 3 that is, the first photons are sent to the space through the circulator 4 and the fiber collimator 5, different wavelengths of light propagate in different spatial directions after the action of the blazed grating 6, are expanded by the lens 7 and irradiate different positions of the to-be-measured target 9, and then the photons with the spatial distribution of the to-be-measured target 9 are reflected, returned along the original path, and then incident to the single-photon detector 8 at the other port of the circulator 4 through the circulator 4 to obtain the time when the first photons are detected.

[0085] In another embodiment, the composition of the second photon emission and receiving module is specifically described, which comprises a time dispersion element and a second single-photon detector.

[0086] The time dispersion element is configured to time-disperse the second photons.

[0087] The second single-photon detector is configured to detect the second photons after time dispersion to obtain the time when the second photons are detected.

[0088] It should be noted that, after the time dispersion element, different wavelengths of the second photons will obtain different time delays, and then the wavelength of the second photons can be obtained through the time delay information, and then the wavelength of the first photons can be obtained based on the correlation between the wavelengths of the first photons and the second photons.

[0089] Specifically, the pulse of the second photons with wide spectrum is broadened by the time dispersion, and the broadened time distribution has a corresponding relationship with the wavelength of the second photons, i.e., the arrival time of the photons has a corresponding relationship with the wavelength of the photons. Based on this, the wavelength of the second photons can be calculated by the difference t2-t0 between the second detection time t2 and the output time t0, in combination with the dispersion amount of the time dispersion element (based on Δτ=D·Δλ, where Δτ is the broadening of the pulse, D is the dispersion amount of the dispersion element, and Δλ is the spectrum width of the generated second photons, i.e., the arrival time of the second photons after the time dispersion element has a linear relationship with the wavelength of the second photons). As described above, the wavelength of the frequency-correlated photon pair has a corresponding relationship, so the wavelength of the first photons emitted by the same pump pulse can be calculated after the wavelength of the second photons is obtained.

[0090] Further, the first photons dispersed in space propagate in different directions in space due to the difference in wavelength, and only the first photons irradiated to the scene to be detected can be detected by the first single-photon detector after being reflected, so in order to realize the detection of the scene to be detected, the angle information of the scene to be detected relative to the irradiation direction of the first photons is obtained according to the wavelength of the detected first photons (based on sinθ=D·λ, where θ is the diffraction angle of the grating, i.e., the outgoing spatial angle, D is the dispersion amount of the grating, and λ is the wavelength of the generated first photons, i.e., the emission angle of the second photons after the grating dispersion has a linear relationship with the wavelength), i.e., the direction of the scene to be detected relative to the detection end, and then the distance information of the reflected first photons can be calculated by the difference t1-t0 between the first detection time t1 and the output time t0 using the principle of photon time-of-flight (ToF) measurement. Thus, the information of the scene to be detected in two dimensions of depth and direction is realized.

[0091] The effect of the radar system for detecting three-dimensional information of a scene according to the above embodiment is verified by a specific example.

[0092] In this example, the frequency-correlated photon pair with wide spectrum is generated by using femtosecond pulse laser to pump the nonlinear nanosilicon line waveguide to excite the spontaneous four-wave mixing effect, wherein the size of the cross section of the nanosilicon line waveguide used is 450×220 nm, and the length is about 11 mm. Then, the wide fluorescence spectrum generated by pumping the nonlinear nanosilicon line with the coarse wavelength division multiplexing device (CWDM) widely used in optical communication is filtered to form signal photons (1530±7 nm), i.e., first photons, and idler photons (1570±7 nm), i.e., second photons, with a spectrum width of about 14 nm, and the frequencies of the first photons and the second photons are correlated.

[0093] Specifically, the first photons are input into the first single-photon detector as described above Figure 3The example structure shown, i.e. first converting the first photon into a spatial light emission by using a fiber collimator, and then converting the frequency degree of freedom into the spatial degree of freedom by using a blazed grating, the obtained object to be imaged is as shown in Figure 4 The two different spatial positions of the corner cube reflectors shown, and the depth positions of the two corner cube reflectors are also different, it can be seen that the first photon converted from the frequency degree of freedom into the spatial degree of freedom propagates in different spatial directions and irradiates different positions of the object.

[0094] It can be understood that since the one-dimensional grating is used for spatial dispersion in the present example, the light spot of the first photon irradiating the object forms a line segment with a span of about 4m, which covers the range of the object to be imaged in the lateral direction.

[0095] The second photon is converted into the arrival time information of the second photon by the dispersion compensation module according to the frequency information of the second photon. It can be known that the dispersion of the dispersion compensation module near 1570nm is 2116ps, and the width of the wave packet after the expansion estimated according to the spectral width of the idler light photon is about 28ns, i.e. the measurement range in the X direction.

[0096] Further, the single-photon detector used in the present example is a superconducting nanowire single-photon detector, and the time recording of the single-photon event uses a time-correlated single-photon counting module with a resolution accuracy of about ps. By analyzing the input time t0, the first detection time t1 and the second detection time t2, the three-dimensional "direction-depth-relative intensity" imaging of the object is realized, and the specific results are as shown in Figure 5 The measurement results of a typical three-dimensional "direction-depth-relative intensity" imaging are shown.

[0097] The following will be combined with Figure 6 A method for detecting three-dimensional information of a scene is described, and the method for detecting three-dimensional information of a scene described below can be correspondingly referred to the radar system for detecting three-dimensional information of a scene described above.

[0098] As Figure 6 The method comprises the following steps:

[0099] 601, generating frequency-correlated first photons and second photons by using pump light pulses, and obtaining the output time of the pump light pulses.

[0100] 602, emitting the first photons to different spatial directions by using spatial dispersion, and obtaining the time when the first photons reflected by the scene to be measured and returned along the original path are detected by the first single-photon detector as the first detection time.

[0101] 603. The second photon undergoes time dispersion, and the time at which the second photon is detected by the second single-photon detector after time dispersion is obtained, which is used as the second detection time.

[0102] 604. Based on the output time, the first detection time, and the second detection time, obtain a three-dimensional image of the scene to be tested.

[0103] This invention provides a method for detecting three-dimensional information of a scene. On one hand, it utilizes the quantum correlation between the first and second photons, which are frequency-correlated, to filter single-photon detection data, thereby reducing the impact of noise counting events and improving detection sensitivity. On the other hand, it leverages the frequency correlation characteristics between the first and second photons to achieve photon counting radar functionality without the need for mechanical beam scanning. Furthermore, by eliminating the requirement for mechanical scanning, it unlocks the potential for system-on-a-chip integration using chip-integrated quantum light sources and optical quantum chip technology, providing a feasible solution for the miniaturization of photon counting radar. Moreover, the light intensity in the irradiated space is only at the single-photon level, making it difficult for targets to detect during operation, making it particularly suitable for applications requiring high system concealment.

[0104] In one embodiment of the present invention, a method for obtaining the frequency-correlated first and second photons is specifically described, comprising:

[0105] The pump light pulse is used to excite the nonlinear optical material to generate frequency-correlated photon pairs;

[0106] The frequency-correlated photon pair is separated into the first photon and the second photon by optical filtering.

[0107] It should be noted that frequency-correlated photon pairs are generated by exciting spontaneous nonlinear parametric processes in nonlinear optical materials with pump light pulses, resulting in wide-spectrum frequency-correlated photon pairs. Then, through optical filtering, i.e. frequency distribution, the two photons that make up the photon pair can be separated to obtain the first photon and the second photon.

[0108] Understandably, the output time of the pump light pulse can be recorded manually or by machine, but obtaining the output time by machine is more convenient and accurate.

[0109] Based on this, in another embodiment of the present invention, after the nonlinear optical material is excited to generate frequency-correlated photon pairs, the remaining pump light pulse is photodetected to obtain an electrical signal containing the output time; and then the output time is obtained from the electrical signal.

[0110] It should be noted that the pump light pulse carries the output time information when it is generated. The output time of the pump light pulse can be obtained by detecting the pump light pulse with the photoelectric detector.

[0111] In another embodiment of the present application, the method of obtaining the three-dimensional image of the scene to be measured according to the output time, the first detection time, and the second detection time further comprises:

[0112] According to the output time, the second detection time, and the dispersion amount of the time dispersion, the wavelength of the second photon is obtained.

[0113] According to the wavelength of the second photon and the wavelength of the pump light pulse, the wavelength of the first photon is obtained.

[0114] According to the wavelength of the first photon, the angle information of the scene to be measured relative to the irradiation direction of the first photon is obtained.

[0115] According to the wavelength of the first photon, the output time, and the first detection time, the depth information of the scene to be measured is obtained.

[0116] It can be understood that the wavelengths of the first photon and the second photon generated will be different with different wavelengths of the pump light pulse. The first photon generated from the same pump light pulse can only obtain the direction and depth information of the scene to be measured irradiated in a specific direction.

[0117] Therefore, in another embodiment of the present application, the first photon and the second photon associated with the generation frequency of the pump light pulse are periodically used to improve the accuracy of the three-dimensional information of the scene to be measured obtained by detection.

[0118] After the three-dimensional image of the scene to be measured is obtained according to the output time, the first detection time, and the second detection time, the method of detecting the three-dimensional information of the scene further comprises:

[0119] The three-dimensional image of the scene to be measured obtained in the current period is fused with the three-dimensional image of the scene to be measured obtained in at least one historical period.

[0120] It should be noted that the first photon irradiation direction and the corresponding depth information obtained in each period are specific. Therefore, by counting the first photon irradiation direction obtained in each period, the photon count of the first photon in different depths in all possible spatial irradiation directions can be obtained, that is, the depth information of the physical reflection surface in different spatial irradiation directions can be obtained, the function of the photon counting radar is improved, and the three-dimensional image of the scene to be measured can be more accurately detected.

[0121] It can be understood that the depth information of the whole to-be-tested scene is obtained according to the depth information of the to-be-tested scene in each period, so it is necessary to ensure that the time information obtained in each period is complete, so before obtaining the three-dimensional image of the to-be-tested scene in a single period according to the output time, the first detection time and the second detection time, it is necessary to first perform data screening, that is, when the output time t0, the first detection time t1 and the second detection time t2 are obtained at the same time in a pump light pulse period, this group of data can be selected and recorded as valid coincidence data, and then the three-dimensional image of the to-be-tested scene in a single period is obtained by processing each group of valid coincidence data.

[0122] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A radar system for probing three-dimensional information of a scene, characterized in that The application relates to a quantum light source module, a first photon emission and receiving module, a second photon emission and receiving module and a data processing module. The quantum light source module is used for generating frequency-correlated first and second photons by using a pump light pulse and obtaining an output time of the pump light pulse. The first photon emission and receiving module is used for emitting the first photons to different spatial directions by spatial dispersion, obtaining a time when the first photons reflected by a to-be-measured scene and returned along the original path are detected by a first single-photon detector as a first detection time. The second photon emission and receiving module is used for time-dispersing the second photons, and obtaining a time when the time-dispersed second photons are detected by a second single-photon detector as a second detection time. The data processing module is used for obtaining a three-dimensional image of the to-be-measured scene according to the output time, the first detection time and the second detection time, comprising the following steps: obtaining the wavelength of the second photons according to the output time, the second detection time and the dispersion amount of the time dispersion; obtaining the wavelength of the first photons according to the wavelength of the second photons and the wavelength of the pump light pulse; obtaining the angle information of the to-be-measured scene relative to the irradiation direction of the first photons according to the wavelength of the first photons; obtaining the depth information of the to-be-measured scene according to the wavelength of the first photons, the output time and the first detection time.

2. The radar system for probing three-dimensional information of a scene according to claim 1, characterized in that, The quantum light source module comprises a pump light pulse, a nonlinear optical material unit and a frequency distribution unit. The pump light pulse is used for irradiating the nonlinear optical material unit. The nonlinear optical material unit is used for generating a frequency-correlated photon pair by using the incident pump light pulse. The frequency distribution unit is used for separating the frequency-correlated photon pair into the first and second photons.

3. The radar system for probing three-dimensional information of a scene according to claim 2, characterized in that, The quantum light source module further comprises a photoelectric detection module. The photoelectric detection module is used for generating an electric signal containing the output time according to a residual pump light pulse, and inputting the electric signal into the data processing module. The residual pump light pulse is the residual pump light pulse after exciting the nonlinear optical material to generate the frequency-correlated photon pair.

4. The radar system for probing three-dimensional information of a scene according to claim 1, characterized in that, The first photon emission and receiving module specifically comprises an optical path adjustment unit, a spatial dispersion element, a beam expanding element and a first single-photon detector. The optical path adjustment unit is used for collimating the first photons to obtain collimated light, and inputting the first photons returned by the spatial dispersion element into the first single-photon detector. The spatial dispersion element is used for making the collimated light propagate to different spatial directions according to the wavelength difference, and returning the first photons returned by the beam expanding element to the optical path adjustment unit. The beam expanding element is used for expanding the first photons propagating to different spatial directions, and converging the first photons reflected back after irradiating the to-be-measured scene, and then returning the first photons to the spatial dispersion element. The first single-photon detector is used for detecting the first photons reflected by the to-be-measured scene and returned along the original path to obtain the first detection time.

5. The radar system for probing three-dimensional information of a scene according to claim 1, characterized in that, The second photon emission and receiving module specifically comprises a time dispersion element and a second single-photon detector. The time dispersion element is used for time-dispersing the second photons. The second single-photon detector is configured to detect the second photon after time dispersion to obtain the second detection time.

6. A method of detecting three-dimensional information of a scene, characterized by, The method comprises: generating a first photon and a second photon that are frequency-correlated by using a pump light pulse, and obtaining an output time of the pump light pulse; performing spatial dispersion on the first photon to different spatial directions, and obtaining a time when the first photon reflected by the scene under test and returned along the same path is detected by a first single-photon detector as a first detection time; performing time dispersion on the second photon, and obtaining a time when the second photon after time dispersion is detected by a second single-photon detector as a second detection time; obtaining a three-dimensional image of the scene under test according to the output time, the first detection time, and the second detection time, comprising: obtaining a wavelength of the second photon according to the output time, the second detection time, and a dispersion amount of the time dispersion; obtaining a wavelength of the first photon according to the wavelength of the second photon and the wavelength of the pump light pulse; obtaining angle information of the scene under test relative to an irradiation direction of the first photon according to the wavelength of the first photon; obtaining depth information of the scene under test according to the wavelength of the first photon, the output time, and the first detection time.

7. The method of claim 6, wherein, The method of generating the first photon and the second photon that are frequency-correlated by using the pump light pulse comprises: generating a pair of frequency-correlated photons by exciting a nonlinear optical material by using the pump light pulse; separating the pair of frequency-correlated photons into the first photon and the second photon by optical filtering.

8. The method of claim 7, wherein, The method of obtaining the output time of the pump light pulse comprises: performing photoelectric detection on the remaining pump light pulse after the pair of frequency-correlated photons is generated by exciting the nonlinear optical material, to obtain an electrical signal containing the output time; obtaining the output time from the electrical signal.

9. The method of claim 6, wherein, The method of generating the first photon and the second photon that are frequency-correlated by using the pump light pulse comprises: periodically generating the first photon and the second photon that are frequency-correlated by using the pump light pulse; After the three-dimensional image of the scene under test is obtained according to the output time, the first detection time, and the second detection time, the method further comprises: fusing the three-dimensional image of the scene under test obtained in a current period with the three-dimensional image of the scene under test obtained in at least one historical period.

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