Non-vision field correlated imaging method based on chaotic optical comb
By using a chaotic optical comb and a second-order correlation imaging mechanism, the problems of slow non-viewpoint imaging speed and stringent requirements on relay wall type are solved, realizing high-speed 3D imaging without mechanical scanning and possessing the potential for real-time imaging.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
- Filing Date
- 2026-01-22
- Publication Date
- 2026-05-08
AI Technical Summary
Existing non-view-of-sight imaging methods require dense laser grid scanning of relay walls, resulting in slow imaging speeds and stringent requirements on the surface shape of the relay walls, which limits their widespread application in practical scenarios.
A chaotic optical comb is used as the illumination source. Multi-point random illumination is formed by a two-dimensional dispersive device. Combined with a single-pixel detector to record the echo timing and construct virtual voxels, non-viewpoint three-dimensional imaging is achieved by using second-order correlation operations.
It achieves high-speed non-viewpoint 3D imaging without mechanical scanning, with significant advantages in terms of system complexity and data acquisition time, and has the potential for real-time imaging.
Smart Images
Figure CN121995398A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of computational imaging technology, and in particular to a non-view-field correlation imaging method based on chaotic optical combs. Background Technology
[0002] Traditional imaging techniques mostly rely on the target being within the direct field of view, acquiring image information through direct reflection of light to the imaging device. However, in many practical applications, such as detecting hidden targets in complex environments or searching for trapped people or objects in disaster rubble, the target is often outside the field of view, rendering conventional imaging methods ineffective.
[0003] Non-line-of-sight imaging (NLOS) technology, also known as corner imaging, is an emerging imaging method dedicated to overcoming the limitations of the field of view to acquire target information. Most existing NLOS imaging methods require dense laser grid scanning of relay walls, which suffers from slow imaging speed and stringent requirements on the surface shape of the relay walls, greatly limiting their widespread application in practical scenarios. Summary of the Invention
[0004] Therefore, it is necessary to provide a non-view-field correlation imaging method based on chaotic optical combs to address the aforementioned technical problems.
[0005] The following technical solution is adopted in this specification: This specification provides a non-line-of-sight correlation imaging method based on chaotic optical combs, including: Obtain a chaotic light comb and use the chaotic light comb as an illumination source; The chaotic light comb is split into N×M chaotic sub-beams by a two-dimensional dispersive device, and N×M random illumination points are formed on the surface of the relay wall in the non-visual scene. The chaotic sub-beam emitted by each illumination point propagates to the target non-visual scene area after diffuse reflection through the relay wall, and the echo timing signal is obtained through a single pixel detector; the echo time of the chaotic sub-beam emitted by the illumination point to the target area is determined; and the original intensity timing signal of the chaotic sub-beam is recorded as the reference light signal. Based on the principle of the constancy of the speed of light, the echo time is mapped to the spatial depth of the chaotic sub-beam, and a virtual voxel is constructed in the space using picosecond-level time slices; based on the distance between the virtual voxel and the relay wall and combined with the reference signal, a three-dimensional time-varying mask of the virtual voxel is obtained. Based on the second-order correlation value between the three-dimensional time-varying mask and the echo signal, a three-dimensional image of the hidden target in the non-view area is obtained.
[0006] Furthermore, the chaotic optical comb is generated by silicon nitride microrings under continuous wave pumping via the Kerr nonlinear effect; Among them, the chaotic optical comb generated by the Kerr nonlinear effect has a time domain fluctuation of <10 ps, a frequency domain broadening of ≥20nm, and a repetition frequency of ≥1 GHz.
[0007] Furthermore, the two-dimensional dispersive device is composed of a VIPA etalon and a reflective grating cascaded orthogonally; wherein the free spectral range of the VIPA etalon is perpendicular to the dispersion direction of the reflective grating.
[0008] Furthermore, the illumination point is equivalent to an independent spherical wave source that uniformly emits light in the direction of the hidden target; the intensity of the illumination point changes with time according to a random sequence of chaotic light combs, and satisfies the Lambertian scattering model on the surface of the hidden target.
[0009] Further, obtaining a 3D image of the hidden target within the non-view area based on the second-order correlation value between the 3D time-varying mask and the echo signal includes: The differential ghost imaging algorithm is used for 3D reconstruction, and the reconstruction formula is as follows: ; in, The reconstruction value of this voxel; It represents the number of time slices; It is the mask value of the corresponding voxel at time i; It is an echo intensity sequence; Indicates time average.
[0010] Furthermore, the single-pixel detector has a bandwidth ≥ 1 GHz, a sampling rate ≥ 128 GSa / s, and a number of sampling points T ≥ 5000.
[0011] Furthermore, before calculating the second-order correlation value between the three-dimensional time-varying mask and the echo signal, background noise is subtracted from the echo timing signal to improve the reconstruction signal-to-noise ratio.
[0012] Further, obtaining the echo timing signal through a single-pixel detector includes: In the non-view area of the target scene, a three-dimensional space composed of multiple voxels is obtained by voxel discretization. Part of the chaotic sub-beam interacts with the target in the voxel and produces scattering; The scattered light returns to the relay wall, based on the coordinates of each voxel. This gives the distance from the voxel to the illumination point; The echo timing signal is obtained by calculating the time it takes for the spherical wave that diverges after the chaotic light signal is reflected by the repeater wall to spread to each voxel. The distance from the voxel to the illumination point is calculated using the following formula: ; The time it takes for the spherical wave of the chaotic light signal to spread to each voxel after being reflected by the relay wall. t The calculation formula is: ; in, d This represents the distance from the voxel to the illumination point; c This indicates the speed at which light travels through the air.
[0013] Furthermore, the process of discretizing voxels to obtain a three-dimensional space composed of multiple voxels includes: The non-view scene is discretized into a three-dimensional mesh with P×Q horizontal pixels and K voxels in the depth direction; Among them, horizontal resolution , ≤5 mm, depth resolution =0.15 mm, time slice width is 1 ps.
[0014] This specification provides a non-line-of-view correlation imaging system based on a chaotic optical comb, including: Chaotic optical comb source module: used to acquire a chaotic optical comb and use the chaotic optical comb as an illumination source; Two-dimensional dispersive projection module: used to split the chaotic light comb into N×M chaotic sub-beams through a two-dimensional dispersive device, and form N×M random illumination points on the surface of the relay wall in the non-view scene; Single-pixel detector module: used to propagate the chaotic sub-beam emitted by each illumination point to the target non-view scene area after diffuse reflection through the relay wall, and obtain the echo timing signal through the single-pixel detector; and determine the echo time of the chaotic sub-beam emitted by the illumination point to the target area; and record the original intensity timing signal of the chaotic sub-beam as the reference light signal; Time-distance correlation module: used to map the echo time to the spatial depth of the chaotic sub-beam according to the principle of constant speed of light, and construct virtual voxels in the space with picosecond time slices; based on the distance between the virtual voxel and the relay wall and combined with the reference signal, a three-dimensional time-varying mask of the virtual voxel is obtained; Second-order correlation reconstruction module: used to obtain a three-dimensional image of a hidden target in a non-view area based on the second-order correlation value between the three-dimensional time-varying mask and the echo signal.
[0015] The above-mentioned technical solutions adopted in this specification can achieve the following beneficial effects: This specification provides a non-line-of-sight correlation imaging method based on a chaotic optical comb. A chaotic optical comb is used as the illumination source, and multi-point random illumination is formed through a two-dimensional dispersive device. Echo timing is recorded by single pixels and combined with time-of-flight to construct virtual voxels. Then, a second-order correlation operation is used to reconstruct the 3D image of the hidden target in one step. Compared to traditional laser scanning methods, this invention, by introducing a chaotic optical comb and a second-order correlation imaging mechanism, achieves high-speed non-line-of-sight 3D imaging without the need for mechanical scanning or spatial light modulators. It has significant advantages in terms of system complexity and data acquisition time, and offers faster non-line-of-sight data acquisition speeds in specific application scenarios. Attached Figure Description
[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:
[0017] Figure 1 This is a schematic diagram of a non-view-of-view correlation imaging system provided in this specification; Figure 2 This is a schematic diagram of a three-dimensional random mask generated at a certain moment as provided in this specification. Figure 3 This is a schematic diagram of the main view of the simulation reconstruction results provided in this manual. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of this specification clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in this specification without creative effort are within the scope of protection of this application.
[0019] Ghost imaging theory, as a unique imaging theory, utilizes the second-order correlation property of the light field to achieve imaging, providing a new research approach for non-line-of-sight imaging. However, there are currently few mature and efficient non-line-of-sight imaging methods developed based on ghost imaging theory. Therefore, there is an urgent need to develop an efficient non-line-of-sight imaging method based on ghost imaging theory to address the many shortcomings of existing technologies.
[0020] Based on this, this invention theoretically achieves non-view-of-sight 3D imaging without mechanical scanning by introducing a chaotic optical comb and a second-order correlation imaging mechanism. Simulation results show that this method can reconstruct 3D images with spatial resolution in typical scenarios and possesses potential real-time imaging capabilities. Compared with traditional laser scanning methods, this scheme has significant advantages in terms of system complexity and data acquisition time, and is expected to achieve faster non-view-of-sight data acquisition speeds in specific application scenarios.
[0021] The present invention discloses a non-line-of-sight correlation imaging method based on chaotic optical combs, comprising the following steps: 1. Light source setup: A chaotic light comb is used as the illumination source, which is split into N×M sub-beams by a two-dimensional dispersive device to form N×M random illumination points on the relay wall in the non-view scene; 2. Signal light propagation and scattering: After the chaotic sub-beam emitted from the illumination point is diffusely reflected by the relay wall, some of the light interacts with the hidden target and is scattered. The scattered light returns to the relay wall and is eventually collected by the single-pixel detector. The original intensity time sequence of the chaotic light comb is recorded simultaneously as a reference light signal. 3. Detector detection and data acquisition: The echo timing signal S(t) is continuously acquired by a single-pixel detector, and the reference optical signal R(t) is synchronously recorded at a sampling rate not lower than the optical comb repetition frequency to obtain intensity measurement data; 4. Data Processing and Imaging Reconstruction: Based on the principle of constant speed of light, the echo time is mapped to spatial depth, virtual voxels are constructed, and the second-order correlation value between the three-dimensional time-varying mask corresponding to the voxel and the echo signal is calculated to complete the three-dimensional image reconstruction of the hidden target.
[0022] The technical solutions provided by the various embodiments of this application are described in detail below with reference to the accompanying drawings.
[0023] S101: Light source settings.
[0024] like Figure 1 As shown, the chaotic optical comb is generated by the Kerr nonlinear effect through silicon nitride microrings pumped by continuous wave, with a repetition frequency of 10 GHz, a spectral broadening of approximately 22 nm, and temporal fluctuations of less than 10 ps. After passing through a two-dimensional dispersive device composed of a VIPA etalon and a reflective grating, the optical comb forms 5×5 random illumination points, uniformly distributed on the surface of the relay wall (z = 0 plane), with a spacing of approximately 10 cm between the illumination points.
[0025] S102: Signal light propagation and scattering.
[0026] By estimating the scale of the non-view scene, the entire non-view scene is discretized into voxels. In this patent example, a three-dimensional space with a cross-sectional area of 0.25 m² and a depth range of 1-3 m is discretized into 64×64×100 voxels, and the coordinates of each voxel are as follows: According to the distance formula
[0027] The distance from each voxel to each illumination point can be determined. Then, based on... (Where c = 299792458 m / s), calculate the time it takes for the spherical wave emitted by the chaotic light signal after reflection by the relay wall to diffuse to each voxel. Each illumination point is considered as a spherical wave source, and the chaotic light signal emitted by it propagates to the target area after diffuse reflection by the relay wall. If a target is present in the voxel, Lambertian scattering occurs, and part of the scattered light returns to the relay wall and is received by the single-pixel detector.
[0028] S103: Detector detection and data acquisition.
[0029] The single-pixel detector has a bandwidth of 1 GHz and a sampling rate of 128 GSa / s, collecting data at 10,000 time points, corresponding to 10,000 random masks. The 3D random masks are shown below. Figure 2 As shown. The reference optical signal is directly recorded from the raw output of the chaotic optical comb and used for subsequent second-order correlation calculations. 5% Gaussian noise was added to the simulation to mimic the actual detection environment.
[0030] S104: Data processing and imaging reconstruction.
[0031] 3D reconstruction was performed using the differential ghost imaging algorithm, and the simulation reconstruction results are as follows: Figure 3 As shown, the reconstruction formula is as follows: in, The reconstruction value of this voxel, It is the number of time slices. yes i The mask value of the corresponding voxel at any given time. It is an echo intensity sequence. Indicates time average.
[0032] The above are one or more embodiments of the non-view-field correlation imaging method based on chaotic optical comb provided in this specification. Based on the same idea, this specification also provides a corresponding non-view-field correlation imaging system based on chaotic optical comb.
[0033] The non-view-field correlation imaging system based on chaotic optical comb consists of a chaotic optical comb source, a two-dimensional dispersion projection module, a single-pixel detector, a time-distance correlation module, and a second-order correlation reconstruction module.
[0034] Chaotic optical comb source: A tunable semiconductor laser is used as the pump laser source, injecting continuous pump light into a silicon nitride microring resonator. Due to the sufficient optical nonlinearity and high quality factor of silicon nitride, the pump light energy can generate a large number of chaotic optical comb teeth in the resonant cavity. Each chaotic comb tooth can serve as an independent random intensity wave source.
[0035] Two-dimensional dispersive projection module: The system uses an orthogonally arranged virtual image phased array (VIPA) and diffraction grating as inertial-free dispersive elements to unfold the chaotic light comb in two dimensions and project it onto the relay surface to cause spherical scattering, which is regarded as a spherical wave source with intensity that changes randomly with time.
[0036] Single-pixel detector: Uses a fiber optic collimating lens to couple a photodiode (PD) to detect the intensity of the echo light, which is then converted into a voltage and read out by an oscilloscope.
[0037] The time-distance correlation module divides the space to be reconstructed into voxels, calculates the distance from each voxel to the spherical wave source on the relay surface, and calculates the time required for the random intensity of all wave sources to propagate to the voxel at a given moment based on the distance and the speed of light, thereby determining the superimposed light intensity corresponding to the voxel at that moment. The superimposed light intensity mask at all moments is recorded and saved using an oscilloscope via another reference signal.
[0038] Second-order correlation reconstruction module: At the effective voxel location, light intensity is reflected and detected by the PD (Photodetector), read out by the oscilloscope, forming an intensity distribution that changes over time. By calculating the second-order correlation statistical properties of this intensity distribution and the light intensity mask, correlation reconstruction of the non-viewpoint scene is achieved.
[0039] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
Claims
1. A non-view-of-sight correlation imaging method based on chaotic optical combs, characterized in that, include: Obtain a chaotic light comb and use the chaotic light comb as an illumination source; The chaotic light comb is split into N×M chaotic sub-beams by a two-dimensional dispersive device, and N×M random illumination points are formed on the surface of the relay wall in the non-visual scene. The chaotic sub-beam emitted by each of the illumination points propagates to the target non-visual scene area after diffuse reflection by the relay wall, and the echo timing signal is obtained by a single pixel detector. And determine the echo time of the chaotic sub-beam emitted from the illumination point to the target area; The original intensity timing signal of the chaotic sub-beam is recorded as the reference optical signal; Based on the principle of the constancy of the speed of light, the echo time is mapped to the spatial depth of the chaotic sub-beam, and virtual voxels are constructed in the space using picosecond-level time slices. Based on the distance between the virtual voxel and the relay wall and combined with the reference signal, a three-dimensional time-varying mask of the virtual voxel is obtained; Based on the second-order correlation value between the three-dimensional time-varying mask and the echo signal, a three-dimensional image of the hidden target in the non-view area is obtained.
2. The non-view-of-sight correlation imaging method based on chaotic optical comb as described in claim 1, characterized in that, The chaotic optical comb is generated by silicon nitride microrings under continuous wave pumping via the Kerr nonlinear effect. Among them, the chaotic optical comb generated by the Kerr nonlinear effect has a time domain fluctuation of <10 ps, a frequency domain broadening of ≥20 nm, and a repetition frequency of ≥1 GHz.
3. The non-view-of-sight correlation imaging method based on chaotic optical comb as described in claim 1, characterized in that, The two-dimensional dispersive device is composed of a VIPA etalon and a reflective grating cascaded orthogonally; wherein the free spectral range of the VIPA etalon is perpendicular to the dispersion direction of the reflective grating.
4. The non-view-of-sight correlation imaging method based on chaotic optical comb as described in claim 1, characterized in that, The illumination point is equivalent to an independent spherical wave source that uniformly emits light in the direction of the hidden target; the intensity of the illumination point changes with time according to a random sequence of chaotic light combs, and satisfies the Lambertian scattering model on the surface of the hidden target.
5. The non-view-of-sight correlation imaging method based on chaotic optical comb as described in claim 1, characterized in that, The process of obtaining a 3D image of a hidden target within a non-view area based on the second-order correlation value between the 3D time-varying mask and the echo signal includes: The differential ghost imaging algorithm is used for 3D reconstruction, and the reconstruction formula is as follows: ； in, The reconstruction value of this voxel; It represents the number of time slices; It is the mask value of the corresponding voxel at time i; It is an echo intensity sequence; Indicates time average.
6. The non-view-of-sight correlation imaging method based on chaotic optical comb as described in claim 1, characterized in that, The single-pixel detector has a bandwidth of ≥1 GHz, a sampling rate of ≥128 GSa / s, and a number of sampling points T ≥5000.
7. The non-view-of-sight correlation imaging method based on chaotic optical comb as described in claim 1, characterized in that, Before calculating the second-order correlation value between the three-dimensional time-varying mask and the echo signal, background noise is subtracted from the echo timing signal to improve the reconstruction signal-to-noise ratio.
8. The non-view-of-sight correlation imaging method based on chaotic optical comb as described in claim 1, characterized in that, The process of obtaining the echo timing signal through a single-pixel detector includes: In the non-view area of the target scene, a three-dimensional space composed of multiple voxels is obtained by voxel discretization. Part of the chaotic sub-beam interacts with the target in the voxel and produces scattering; The scattered light returns to the relay wall, based on the coordinates of each voxel. This gives the distance from the voxel to the illumination point; The echo timing signal is obtained by calculating the time it takes for the spherical wave that diverges after the chaotic light signal is reflected by the repeater wall to spread to each voxel. The distance from the voxel to the illumination point is calculated using the following formula: ； The time it takes for the spherical wave of the chaotic light signal to spread to each voxel after being reflected by the relay wall. t The calculation formula is: ； in, d This represents the distance from the voxel to the illumination point; c This indicates the speed at which light travels through the air.
9. The non-view-of-sight correlation imaging method based on chaotic optical comb as described in claim 8, characterized in that, The process of discretizing voxels to obtain a three-dimensional space composed of multiple voxels includes: The non-view scene is discretized into a three-dimensional mesh with P×Q horizontal pixels and K voxels in the depth direction; Among them, horizontal resolution , ≤5 mm, depth resolution =0.15 mm, time slice width is 1 ps.
10. A non-view-of-sight correlation imaging system based on a chaotic optical comb, characterized in that, include: Chaotic optical comb source module: used to acquire a chaotic optical comb and use the chaotic optical comb as an illumination source; Two-dimensional dispersive projection module: used to split the chaotic light comb into N×M chaotic sub-beams through a two-dimensional dispersive device, and form N×M random illumination points on the surface of the relay wall in the non-view scene; Single-pixel detector module: used to propagate the chaotic sub-beam emitted by each illumination point to the target non-view scene area after diffuse reflection through the relay wall, and obtain the echo timing signal through the single-pixel detector; and determine the echo time of the chaotic sub-beam emitted by the illumination point to the target area; and record the original intensity timing signal of the chaotic sub-beam as the reference light signal; Time-distance correlation module: used to map the echo time to the spatial depth of the chaotic sub-beam based on the principle of constant speed of light, and to construct virtual voxels in the space using picosecond-level time slices; Based on the distance between the virtual voxel and the relay wall and combined with the reference signal, a three-dimensional time-varying mask of the virtual voxel is obtained; Second-order correlation reconstruction module: used to obtain a three-dimensional image of a hidden target in a non-view area based on the second-order correlation value between the three-dimensional time-varying mask and the echo signal.