Image acquisition device, image generation system and method based on terahertz signals

Abstract

An image acquisition device based on terahertz signals, an image generation system and method, the image acquisition device comprising: a swing reflection plate adapted to reflect terahertz wave signals emitted in a sampling area including a target to be measured; a lens assembly adapted to focus the terahertz wave signals reflected by the swing reflection plate; a radiometer array including n rows of radiometers installed on the focal plane of the lens assembly, the n rows of radiometers being configured to sample the terahertz wave signals emitted by the target to be measured and reflected by the swing reflection plate at the same height, wherein n>=2, and the terahertz wave image has both high resolution and contrast.

Description

Technical Field

[0001] At least one embodiment of the present invention relates to an image acquisition device, and more particularly to an image acquisition device, image generation system and method based on terahertz signals. Background Technology

[0002] Because terahertz waves have the ability to penetrate different materials (such as plastic, clothing, etc.), passive imaging technology based on terahertz waves has a wide range of potential applications in security checks at important checkpoints such as airports and scene monitoring.

[0003] In theory, every object radiates electromagnetic waves outwards. Passive terahertz focal plane imaging technology uses a focusing antenna combined with a high-sensitivity radiometer to receive the terahertz wave power radiated by the scene. It achieves imaging based on the difference in radiation power intensity between different preset suspicious objects and the target to be tested, thereby determining whether there are suspicious objects in the target to be tested.

[0004] When terahertz passive imaging systems are applied to security inspection imaging, the target under test is located in the near field region of the receiving antenna (focusing antenna) in the terahertz signal-based image acquisition device. At the same time, in order to improve the imaging speed, multiple radiometers are often placed on the focal plane of the lens assembly in the image acquisition device to form a focal plane array.

[0005] To reduce system cost and complexity, current solutions involve placing a row of radiometers on the focal plane of the lens assembly and using a mechanical scanning method with a wobbling reflector to scan and image the entire field of view of the sampling area containing the target. However, this row of radiometers makes it difficult to achieve high resolution in the resulting terahertz wave image while maintaining high contrast. Summary of the Invention

[0006] To address the aforementioned technical problems, embodiments of the present invention provide an image acquisition device, image generation system, and method based on terahertz signals, enabling the generated terahertz wave image to simultaneously possess high resolution and contrast.

[0007] As a first aspect of the present invention, an image acquisition device based on terahertz signals is provided, comprising:

[0008] A swinging reflector is suitable for reflecting terahertz wave signals emitted within a sampling area that includes the target under test.

[0009] Lens assembly suitable for focusing terahertz wave signals reflected by a wobbling reflector;

[0010] A radiometer array, comprising n rows of radiometers mounted on the focal plane of a lens assembly, is configured to sample terahertz wave signals emitted at the same height at the target and reflected from a wobbling reflector at intervals, where n ≥ 2.

[0011] According to an embodiment of the invention, n-row radiometers are configured to sample uniformly at equal intervals.

[0012] According to an embodiment of the present invention, the receiving surface of the receiving antenna of the (i+1)th row of the n-row radiometers is offset relative to the receiving surface of the receiving antenna of the ith row of the radiometers in the row direction. Where 1≤i≤n-1, and Q is the length of the receiving surface of the radiometer's receiving antenna in the row direction.

[0013] According to an embodiment of the present invention, the sampling frequency of the radiometer array is 2 to 3 times the Nyquist sampling frequency.

[0014] According to an embodiment of the present invention, n is 3 or 4.

[0015] According to an embodiment of the present invention, the size of the receiving surface of the receiving antenna of each radiometer is configured such that the -10 to -13 dB beamwidth of the receiving antenna is equal to the angle subtended by the lens assembly on the receiving antenna.

[0016] According to an embodiment of the present invention, the oscillating reflector is configured to oscillate about a rotation axis, such that the oscillating reflector reflects terahertz waves from different heights of the area to be measured.

[0017] According to an embodiment of the present invention, the rotation axis of the oscillating reflector extends horizontally parallel to the area to be measured;

[0018] The direction of each row of radiometers is parallel to the direction of the rotation axis.

[0019] According to an embodiment of the present invention, the receiving antenna of each radiometer includes:

[0020] The cone-shaped portion has a flared shape that gradually increases in cross-section towards the lens assembly in the receiving direction, and a receiving surface is formed at the end of the cone-shaped portion facing the lens assembly; and

[0021] A waveguide section is located at the end of the cone-shaped part opposite to the receiving surface to transmit the terahertz wave signal received by the cone-shaped part from the lens assembly.

[0022] According to an embodiment of the present invention, the number of radiometers in each row satisfies the following condition:

[0023] H÷E=P×Q

[0024] Where H represents the width of the sampling area, E represents the magnification of the lens assembly, P represents the number of single-row radiometers, and Q represents the length of the receiving surface of the receiving antenna in the row direction.

[0025] According to an embodiment of the present invention, the above-described image acquisition device further includes:

[0026] A guiding component suitable for guiding a target to be measured into the sampling area of ​​a radiometer array.

[0027] As a second aspect of the present invention, an image generation system is also provided according to an embodiment of the present invention, comprising:

[0028] The aforementioned image acquisition device; and

[0029] The image generation device is configured to construct a terahertz wave image of the target under test based on the terahertz wave signal received by the radiometer array.

[0030] According to an embodiment of the present invention, the image generation apparatus includes:

[0031] The imaging module is configured to image the data acquired by the radiometer array in the j-th row to obtain the j-th sub-image, where 1 ≤ j ≤ n; and

[0032] The processing module is configured to obtain a terahertz wave image of the target under test based on all sub-images.

[0033] According to an embodiment of the present invention, the processing module includes:

[0034] The registration module is configured to align the feature regions of n sub-images to obtain n registered sub-images; and

[0035] The fusion module is configured to take the m-th column pixel of the j-th registration sub-image among n registration sub-images as the j+n(m-1)-th column pixel of the terahertz wave image of the target under test, so as to obtain the terahertz wave image of the target under test.

[0036] According to an embodiment of the present invention, the registration module is further configured to delete pixel rows in the n registration sub-images that were not detected by all radiometers after obtaining n registration sub-images.

[0037] As a third aspect of the present invention, an image generation method based on terahertz signals is also provided, comprising:

[0038] The aforementioned image acquisition device is used to acquire terahertz wave signals emitted from the area under test, including the target under test.

[0039] The j-th sub-image is obtained by imaging the data acquired by the radiometer array in the j-th row, where 1 ≤ j ≤ n; and

[0040] The terahertz wave image of the target under test is obtained from all sub-images.

[0041] According to an embodiment of the present invention, obtaining a terahertz wave image of the target under test based on all sub-images includes:

[0042] Align the feature parts of the target in n sub-images to obtain n registration sub-images;

[0043] The m-th column of pixels in the n registered sub-images is used as the j+n(m-1)-th column of the terahertz wave image of the target under test, thus obtaining the terahertz wave image of the target under test.

[0044] According to an embodiment of the present invention, after obtaining n registration sub-images, the pixel rows in the n registration sub-images that were not detected by all radiometers are deleted.

[0045] According to an embodiment of the present invention, sampling is performed using an n-row radiometer, and the n-row radiometer is configured to sample terahertz wave signals emitted from the same height of the target and reflected from the oscillating reflector at intervals. Compared with the array structure of a single-row radiometer, the sampling rate can be increased. Therefore, the terahertz wave image obtained by sampling data from the n-row radiometer of the present invention has better resolution and can simultaneously meet the requirements of resolution and contrast. Attached Figure Description

[0046] Figure 1 A schematic diagram of the principle of an image acquisition device based on terahertz signals according to an embodiment of the present invention is shown;

[0047] Figure 2 A schematic diagram comparing Rayleigh sampling and Nyquist sampling is shown;

[0048] Figure 3 A schematic diagram of the arrangement of receiving antennas in one row of radiometers in a radiometer array provided according to an embodiment of the present invention is shown.

[0049] Figure 4 It shows Figure 3 A 3D view of the receiving antenna of one of the radiometers;

[0050] Figure 5A A top view of a radiometer array consisting of two rows of radiometers according to an embodiment of the present invention is shown;

[0051] Figure 5B A top view of a radiometer array consisting of two rows of radiometers according to another embodiment of the present invention is shown;

[0052] Figure 6A A top view of a radiometer array consisting of three rows of radiometers according to an embodiment of the present invention is shown;

[0053] Figure 6B A top view of a radiometer array consisting of three rows of radiometers according to another embodiment of the present invention is shown;

[0054] Figure 7A A top view of a radiometer array consisting of four rows of radiometers according to an embodiment of the present invention is shown;

[0055] Figure 7B A top view of a radiometer array consisting of four rows of radiometers according to another embodiment of the present invention is shown;

[0056] Figure 8 A schematic diagram of a sub-image generation process provided according to an embodiment of the present invention is shown;

[0057] Figure 9A A comparison diagram of multiple sub-images generated by the image generation system provided in an embodiment of the present invention for the same target under test is shown;

[0058] Figure 9B The present invention illustrates an embodiment for... Figure 9A A comparison diagram of multiple registered sub-images after registration; and

[0059] Figure 9C It shows that Figure 9B The image obtained by fusing multiple registered sub-images is shown.

[0060] Explanation of reference numerals in the attached figures

[0061] 1: Image acquisition device;

[0062] 11: Swinging reflector;

[0063] 12: Lens assembly;

[0064] 13: Radiometer array;

[0065] 131: Radiometer;

[0066] 1311: Receiving antenna;

[0067] 1311-1: Vertebral body;

[0068] 1311-2: Waveguide section;

[0069] 14 Rotating shafts;

[0070] 2: The area to be tested;

[0071] 3: The target to be tested. Detailed Implementation

[0072] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0073] Figure 1 A schematic diagram of the principle of an image acquisition device based on terahertz signals provided according to an embodiment of the present invention is shown.

[0074] Combination Figure 1 , Figure 5A , Figure 5B , Figure 6A , Figure 6B , Figure 7A and Figure 7B As shown, the image acquisition device 1 based on terahertz signals includes: a swing reflector 11, a lens assembly 12, and a radiometer array 13.

[0075] The oscillating reflector 11 is adapted to reflect terahertz wave signals emitted within a sampling area including the target 3. The lens assembly 12 is adapted to focus the terahertz wave signals reflected by the oscillating reflector 11. The radiometer array 13 includes n rows of radiometers 131 mounted on the focal plane of the lens assembly 12. The n rows of radiometers 131 are configured to sample terahertz wave signals emitted at the same height of the target 3 and reflected from the oscillating reflector 11 at intervals, where n ≥ 2.

[0076] According to an embodiment of the present invention, sampling is performed using an n-row radiometer 131, and the n-row radiometer 131 is configured to sample terahertz wave signals emitted at the same height of the target 3 and reflected from the oscillating reflector 11 at intervals. Compared with an array structure of only one row of radiometers 131, the sampling rate can be increased. Therefore, the terahertz wave image obtained by sampling data from the n-row radiometer 131 of the present invention has better resolution and can simultaneously meet the requirements of resolution and contrast.

[0077] According to an embodiment of the present invention, the oscillating reflector 11 is configured to oscillate about a rotation axis 14, such that the oscillating reflector 11 reflects terahertz waves from different heights of the region to be measured 2. The rotation axis 14 of the oscillating reflector 11 extends horizontally parallel to the region to be measured 2, and the row extension direction of each row of radiometers 131 is parallel to the extension direction of the rotation axis 14, so that each row of radiometers 131 samples the horizontal direction of the region to be measured 2.

[0078] To better understand the technical solutions of the embodiments of the present invention, the following describes the defects in meeting both contrast and resolution requirements when sampling using the array structure of a line radiometer 131.

[0079] Figure 2 A schematic diagram comparing Rayleigh sampling and Nyquist sampling is shown.

[0080] like Figure 2 As shown, the spatial Nyquist sampling theorem describes that at least two sampling points are required for each -10 to -13 dB beamwidth (i.e., half-power beamwidth) to completely record the position information of the target 3. If there is only one sampling point within each -10 to -13 dB beamwidth, it is Rayleigh sampling. When imaging the acquired terahertz wave signal, since Nyquist sampling requires at least two sampling points, the sampling frequency may not necessarily meet the Nyquist sampling frequency. Therefore, when conditions permit, the sampling frequency should be increased as much as possible to achieve sampling of at least two sampling points, thereby improving the image quality of the terahertz wave signal.

[0081] Continue to refer to Figure 1 In the case that the radiometer array 13 of the image acquisition device 1 includes only one row of radiometers, assuming the diameter of the lens is D and the distance between the lens and the receiving surface of the receiving antenna 1311 of the radiometer 13 is S, according to the Rayleigh criterion, the half-power spot diameter σ of the lens is:

[0082]

[0083] Where λ is the wavelength of the terahertz wave signal.

[0084] The angle subtended by the lens of the receiving antenna 1311 of the radiometer is:

[0085]

[0086] According to antenna theory, the aperture of the receiving antenna 1311 is d, and the power beamwidth of the receiving antenna 1311 is -10 to -13 dB. 3dB The estimation formula is as follows

[0087]

[0088] Assuming each spot is sampled w times, then we have

[0089]

[0090] According to equations (1)-(4), in order to achieve high contrast in the image formed by the acquired Hertz wave signal, the image acquisition device needs to have less overflow energy and higher overflow efficiency, that is, more terahertz waves enter the receiving antenna 1311 from the lens assembly 12, and the beamwidth θ of the receiving antenna 1311 is -10 to -13 dB. 3dB The angle θ should be the same as that of the lens facing the receiving antenna 1311. However, in this case, w = 1, which means the Rayleigh sampling number is 1. Rayleigh sampling has a low sampling rate, so the resolution of the image formed by the terahertz wave signal is low, and the imaging effect is poor. If Nyquist sampling is satisfied, i.e., w = 2, then θ 3dB =2θ, at which point the sampling rate is high, but the system overflow efficiency is low, resulting in low contrast of the terahertz wave image.

[0091] From another perspective, in an image acquisition device including a one-dimensional linear radiometer array, since the half-power beam angle of the receiving antenna 1311 is inversely proportional to its aperture d, the higher the contrast of the terahertz wave image, the larger the aperture d of the receiving antenna 1311 is required. Since the receiving antenna 1311 is arranged in the focal plane of the lens assembly 12, the larger the aperture d of the receiving antenna 1311, the fewer the number of receiving antennas 1311 that can be arranged on the focal plane, and the lower the resolution of the terahertz wave image. This is the contradiction between contrast and resolution that occurs when using a linear radiometer 131 to acquire terahertz wave signals.

[0092] According to an embodiment of the present invention, the n-row radiometer 131 is configured to uniformly sample at the same height of the target 3 under test at the same interval, that is, uniformly sample at the same length interval in the row direction. The uniform sampling of the n-row radiometer 131 can reduce distortion in the imaging process, capture the features of the target 3 under test more comprehensively, and make the details of the formed image clearer, thus achieving a higher resolution image.

[0093] The radiometers 131 in any row of the radiometer array 13 are arranged linearly, therefore, the receiving antennas 1311 of any row of radiometers 131 are arranged linearly.

[0094] Figure 3 A schematic diagram of the arrangement of receiving antennas in one row of radiometers in a radiometer array provided according to an embodiment of the present invention is shown.

[0095] Figure 4 It shows Figure 3 A three-dimensional view of the receiving antenna of one of the radiometers.

[0096] like Figure 3 and Figure 4As shown, the receiving antenna 1311 of the radiometer includes a cone-shaped portion 1311-1 and a waveguide portion 1311-2. The cone-shaped portion 1311-1 has a horn shape with a cross-section that gradually increases towards the lens assembly 12 in the receiving direction, and a receiving surface A is formed at the end of the cone-shaped portion 1311-1 facing the lens assembly 12. The waveguide portion 1311-2 is, for example, cuboid in shape, and is disposed at the end of the cone-shaped portion 1311-1 opposite to the receiving surface A, to transmit the terahertz wave signal received by the cone-shaped portion 1311-1 from the lens assembly 12.

[0097] According to an embodiment of the present invention, the cross-section of the waveguide portion 1311-2 of the receiving antenna is a standard waveguide. A standard waveguide includes a circular waveguide or a rectangular waveguide. In the field of terahertz imaging, a standard rectangular waveguide is preferred. For example, a W-waveguide, D-waveguide, or G-waveguide can be used. The dimensions of the W-waveguide are 2.54mm * 1.27mm, the D-waveguide is 1.651mm * 0.8255mm, and the W-waveguide is 1.0922mm * 0.5461mm. The standard rectangular waveguide has a cross-sectional dimension of 2:1 (length L1:width L2 = 2:1). The wavebands of the W-waveguide, D-waveguide, and G-waveguide are also the main operating bands in the terahertz security inspection field. The dimension of the receiving surface A of the receiving antenna 1311 of the radiometer 131 in the horizontal direction ranges from 5mm to 50mm.

[0098] According to an embodiment of the present invention, the receiving surface A of the receiving antenna of the (i+1)th row of the radiometers in the n rows is misaligned in the row direction relative to the receiving surface A of the receiving antenna 1311 of the i-th row radiometer 131. This allows the n-row radiometers to sample uniformly at the same intervals. Here, 1 ≤ i ≤ n-1, and Q is the length of the receiving surface A of the receiving antenna 1311 of the radiometer 131 in the row direction. In some embodiments, the length of the receiving surface A in the row direction can be either the length Q1 or the width Q2 of the receiving surface A.

[0099] Figure 5A A top view of a radiometer array consisting of two rows of radiometers according to an embodiment of the present invention is shown.

[0100] Figure 5B A top view of a radiometer array consisting of two rows of radiometers provided according to another embodiment of the present invention is shown.

[0101] like Figures 5A-5B As shown, when the radiometer array 13 includes only two rows of radiometers 131, the receiving surface A of the receiving antenna 1311 of the second row of radiometers 131 is misaligned in the row direction relative to the receiving surface A of the receiving antenna 1311 of the first row of radiometers 131. exist Figure 5AIn the diagram, the length of the receiving surface A of the receiving antenna 1311 of a single radiometer 131 in the row direction is equal to the length Q1 of the receiving surface A of the receiving antenna 1311. Figure 5B In the process, the length of the receiving surface A of the receiving antenna 1311 of a single radiometer 131 in the row direction is equal to the width Q2 of the receiving surface A of the receiving antenna 1311.

[0102] Figure 6A A top view of a radiometer array consisting of three rows of radiometers according to an embodiment of the present invention is shown.

[0103] Figure 6B A top view of a radiometer array consisting of three rows of radiometers according to another embodiment of the present invention is shown.

[0104] like Figures 6A-6B As shown, when the radiometer array 13 includes only three rows of radiometers 131, the receiving surface A of the receiving antenna 1311 of the second row of radiometers 131 is misaligned in the row direction relative to the receiving surface A of the receiving antenna 1311 of the first row of radiometers 131. The receiving surface A of the receiving antenna 1311 of the third-row radiometer 131 is misaligned in the row direction relative to the receiving surface A of the receiving antenna 1311 of the second-row radiometer 131. exist Figure 6A In the diagram, the length of the receiving surface A of the receiving antenna 1311 of a single radiometer 131 in the row direction is equal to the length Q1 of the receiving surface A of the receiving antenna 1311. Figure 6B In the process, the length of the receiving surface A of the receiving antenna 1311 of a single radiometer 131 in the row direction is equal to the width Q2 of the receiving surface A of the receiving antenna 1311.

[0105] Figure 7A A top view of a radiometer array consisting of four rows of radiometers according to an embodiment of the present invention is shown.

[0106] Figure 7B A top view of a radiometer array consisting of four rows of radiometers according to another embodiment of the present invention is shown.

[0107] like Figures 7A-7B As shown, when the radiometer array 13 includes only four rows of radiometers 131, the receiving surface A of the receiving antenna 1311 of the second row of radiometers 131 is misaligned in the row direction relative to the receiving surface A of the receiving antenna 1311 of the first row of radiometers 131. The receiving surface A of the receiving antenna 1311 of the third-row radiometer 131 is misaligned in the row direction relative to the receiving surface A of the receiving antenna 1311 of the second-row radiometer 131. The receiving surface A of the receiving antenna 1311 of the second-row radiometer 131 is misaligned in the row direction relative to the receiving surface A of the receiving antenna 1311 of the first-row radiometer 131. exist Figure 7A In the diagram, the length of the receiving surface A of the receiving antenna 1311 of a single radiometer 131 in the row direction is equal to the length Q1 of the receiving surface A of the receiving antenna 1311. Figure 7B In the process, the length of the receiving surface A of the receiving antenna 1311 of a single radiometer 131 in the row direction is equal to the width Q2 of the receiving surface A of the receiving antenna 1311.

[0108] According to an embodiment of the present invention, the lens assembly 12 may be a single lens or a lens group comprising multiple lenses.

[0109] Continue to refer to Figure 1 The size of the receiving surface of each radiometer's receiving antenna is configured such that the -10 to -13 dB beamwidth θ of the receiving antenna 1311 is... 3dB The angle θ subtended by lens assembly 12 with respect to the receiving antenna is equal to the angle θ. This is applied to the -10 to -13 dB beamwidth θ of the receiving antenna 1311. 3dB When the angle θ between the lens assembly 12 and the receiving antenna is equal to that of the receiving antenna, the image formed by the acquired Hertz wave signal has high contrast.

[0110] Considering the cost of radiometer 131, it is possible to balance image signal-to-noise ratio and cost while maintaining a sampling frequency that is 2-3 times the Nyquist sampling frequency. For example, the radiometer array 13 has 3-4 rows.

[0111] Continue to refer to Figure 1 According to an embodiment of the present invention, the number of radiometers in each row of 131 satisfies the following condition:

[0112] H÷E=P×Q(5)

[0113] Where H represents the width of the sampling area, E represents the magnification of the lens assembly, P represents the number of radiometers per row, and Q represents the length of the receiving surface of the receiving antenna in the row direction. The number of radiometers per row can be determined based on the actual width of the sampling area; for example, the number of radiometers per row can be 6, 7, 8, or 9.

[0114] According to an embodiment of the present invention, the image acquisition device 1 further includes a guiding component (not shown in the figure) suitable for guiding the target 3 to the sampling area of ​​the radiometer array 13. The guiding component includes an indicator or sign to guide the target 3 to the sampling area. Alternatively, the guiding component includes an automatic conveying device to automatically convey the target 3 to the sampling area. Alternatively, the guiding component includes a voice prompt component, a photographic component, or a display component, wherein the photographic component obtains the position of the target 3, the operator identifies the position of the target 3 on the display component, and the voice prompt component prompts the target 3 to move to the sampling area.

[0115] According to an embodiment of the present invention, an image generation system is also provided, including an image acquisition device 1 and an image generation device (not shown in the figure). The image generation device is configured to construct a terahertz wave image of a target 3 under test based on terahertz wave signals received by a radiometer array 13. The image generation device includes an imaging module and a processing module. The imaging module is configured to image the acquired data obtained by the j-th row of the radiometer array 13 to obtain a j-th sub-image, where 1≤j≤n, thereby generating n sub-images based on a radiometer array 13 including n rows of radiometers. The processing module is configured to obtain a terahertz wave image of the target 3 under test based on all the sub-images. According to an embodiment of the present invention, the processing module includes a registration module and a fusion module. The registration module is configured to align the feature parts of the n sub-images generated by the imaging module to obtain n registered sub-images. The fusion module is configured to take the m-th column pixel of the j-th registration sub-image among the n registration sub-images as the j+n(m-1)-th column pixel of the terahertz wave image of the target 3 under test, so as to obtain the terahertz wave image of the target 3 under test.

[0116] According to an embodiment of the present invention, the registration module is further configured to delete pixel rows in the n registration sub-images that were not detected by all radiometers after obtaining the n registration sub-images (described in detail below).

[0117] As a third aspect of the present invention, an image generation method based on terahertz signals is also provided, comprising: operation S110-operation S130.

[0118] In operation S110, the image acquisition device 1 is used to acquire the terahertz wave signal emitted by the test area 2, which includes the target 3.

[0119] In operation S120, the acquired data collected by the radiometer array 13 in the j-th row is imaged to obtain the j-th sub-image, where 1≤j≤n, thereby generating n sub-images based on the radiometer array 13 including n rows of radiometers.

[0120] In operation S130, the terahertz wave image of the target 3 is obtained based on all sub-images.

[0121] According to an embodiment of the present invention, obtaining the terahertz wave image of the target 3 under test based on all sub-images includes: operation S131-operation S132.

[0122] In operation S131, the feature parts of the target to be tested in the n sub-images are aligned to obtain n registered sub-images.

[0123] Since the position of each row of radiometers 131 in the n-row radiometers 131 on the focal plane is different, and the sampling height of different rows of radiometers 131 is different, the position of the target 3 under test will be slightly different in each sub-image. Therefore, it is necessary to align the feature parts of the target 3 under test in the n sub-images so that the feature parts of the target 3 under test are in the same pixel row in each registered sub-image.

[0124] In operation S132, the m-th column of pixels in the n registered sub-images is taken as the j+n(m-1)-th column of the terahertz wave image of the target 3 to be tested, thus obtaining the terahertz wave image of the target 3 to be tested.

[0125] After aligning the feature parts of the target 3 in the n sub-images, since the radiometer array 13 can achieve uniform sampling at the same interval at the same height of the target 3, the m-th column of the j-th registered sub-image can be used as the j+n(m-1)-th column of the image of the target 3, thus obtaining the terahertz wave image of the target 3.

[0126] According to an embodiment of the present invention, after obtaining n registration sub-images, pixel rows in the n registration sub-images that were not detected by all radiometers are deleted. For example, the pixels in the Xth row of the j-th registration sub-image were not detected by all radiometers in the j-th row. Therefore, the resolution of the pixels in the Xth row is low, and the pixels in the Xth row need to be deleted. At the same time, pixel rows in other registration sub-images corresponding to the pixels in the Xth row of the j-th registration sub-image also need to be deleted.

[0127] Figure 8 A schematic diagram of a sub-image generation process provided according to an embodiment of the present invention is shown.

[0128] like Figure 8 As shown, for example, the device has three rows of radiometers, meaning the radiometer array 13 is arranged in a 3*6 configuration, with 6 radiometers in each row. To achieve complete sampling of the target 3, the oscillating reflector 11 scans once (e.g., from the highest position to the lowest position or vice versa). Each row of radiometers collects R rows of data, where R is typically greater than 1000. After completing the data acquisition for the sampling area, three sub-images P1, P2, and P3 are formed.

[0129] The following example uses a radiometer array consisting of three rows of radiometers, and combines... Figures 9A-9C The process of obtaining the terahertz wave image of target 3 is explained. Figure 9A A comparison diagram of multiple sub-images generated by the image generation system provided in an embodiment of the present invention for the same target under test is shown; Figure 9B The present invention illustrates an embodiment for... Figure 9A A comparison diagram of multiple registered sub-images after registration; Figure 9C It shows that Figure 9B The image obtained by fusing multiple registered sub-images is shown.

[0130] like Figure 9A As shown, Figure 9A The image includes three sub-images P1, P2, and P3, and the target image 3 in each sub-image can be, for example, a person. Figure 9A It can be seen that the position of the target object is different in each sub-image. Therefore, it is necessary to first align the feature parts of the target object to obtain three registered sub-images to ensure that the height of the target object is the same in the three sub-images.

[0131] like Figure 9B As shown, for the registered sub-images P11, P21 and P31, the images formed by the same height of the target 3 under test correspond to the same pixel row in the n registered sub-images. For example, for the images formed by the same height of the target 3 under test, the pixels in the n registered sub-images are all in the h-th row.

[0132] After fusing the three sub-images in 9B, the result is... Figure 9C Image P in the image, combined with Figure 9B and Figure 9C As can be seen from the image, Figure 9C The resolution of image P in the image is significantly higher, especially in the horizontal direction. Figure 9A and Figure 9B The resolution of each image in the dataset.

[0133] because Figure 9C Image P in the image is obtained by fusing the registration sub-images P11, P21, and P31 from image 9B. Figure 9C The number of pixels in the row direction of image P is Figure 9B The sum of the number of pixels in the row direction of the registered sub-images P11, P21, and P31, therefore Figure 9C The resolution of image P in the image is significantly higher, especially in the horizontal direction. Figure 9A and Figure 9B The resolution of each sub-image in the image.

[0134] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An image acquisition device based on terahertz signals, comprising: A swinging reflector is suitable for reflecting terahertz wave signals emitted within a sampling area that includes the target under test. The lens assembly is suitable for focusing the terahertz wave signal reflected by the oscillating reflector. A radiometer array comprising n rows of radiometers mounted on the focal plane of the lens assembly, the n rows of radiometers being configured to sample terahertz wave signals emitted at the same height of the target and reflected from the oscillating reflector at intervals, wherein n ≥ 2.

2. The image acquisition device according to claim 1, wherein, The radiometers described in row n are configured to sample uniformly at equal intervals.

3. The image acquisition device according to claim 2, wherein, The receiving surface of the receiving antenna of the (i+1)th row of the radiometers in row n is offset relative to the receiving surface of the receiving antenna of the ith row of the radiometers in the row direction. Where 1≤i≤n-1, Let be the length of the receiving surface of the radiometer's receiving antenna in the row direction.

4. The image acquisition device according to any one of claims 1-3, wherein, The sampling frequency of the radiometer array is 2 to 3 times the Nyquist sampling frequency.

5. The image acquisition device according to any one of claims 1-3, wherein, n is 3 or 4.

6. The image acquisition device according to any one of claims 1-3, wherein, The receiving surface of each radiometer's receiving antenna is configured such that the -10 to -13 dB beamwidth of the receiving antenna is equal to the angle subtended by the lens assembly on the receiving antenna.

7. The image acquisition device according to claim 1, wherein, The oscillating reflector is configured to oscillate about a rotation axis, so that the oscillating reflector reflects terahertz waves from different heights in the area to be measured.

8. The image acquisition device according to claim 7, wherein, The rotation axis of the oscillating reflector extends horizontally parallel to the area to be measured; The row extension direction of each radiometer is parallel to the extension direction of the rotation axis.

9. The image acquisition device according to claim 1, wherein, Each of the radiometers includes a receiving antenna comprising: The cone-shaped portion has a flared cross-section that gradually increases in the receiving direction toward the lens assembly, and the end of the cone-shaped portion facing the lens assembly forms a receiving surface; and A waveguide section is disposed at one end of the cone-shaped portion opposite to the receiving surface to transmit the terahertz wave signal received by the cone-shaped portion from the lens assembly.

10. The image acquisition device according to claim 3, wherein, The number of radiometers in each row must meet the following condition: Where H represents the width of the sampling area, E represents the magnification of the lens assembly, and P represents the number of single-row radiometers. This indicates the length of the receiving surface of the receiving antenna in the row direction.

11. The image acquisition device according to claim 1, wherein, Also includes: A guiding component suitable for guiding the target under test to the sampling area of ​​a radiometer array.

12. An image generation system, comprising: The image acquisition device as described in any one of claims 1-11; as well as An image generation device is configured to construct a terahertz wave image of the target under test based on the terahertz wave signal received by the radiometer array.

13. The image generation system according to claim 12, wherein, The image generation device includes: The imaging module is configured to image the data acquired by the radiometer array in the j-th row to obtain the j-th sub-image, where 1 ≤ j ≤ n; and The processing module is configured to obtain a terahertz wave image of the target under test based on all sub-images.

14. The image generation system according to claim 13, wherein, The processing module includes: The registration module is configured to align the feature regions of n sub-images to obtain n registered sub-images; and The fusion module is configured to use the m-th column of the j-th registration sub-image among n registration sub-images as the m-th column of the terahertz wave image of the target under test. By analyzing the column of pixels, a terahertz wave image of the target under test is obtained.

15. The image generation system according to claim 14, wherein, The registration module is further configured to delete pixel rows in the n registration sub-images that were not detected by all radiometers after obtaining the n registration sub-images.

16. An image generation method based on terahertz signals, comprising: The terahertz wave signal emitted from the test area, including the target under test, is acquired using the image acquisition device as described in any one of claims 1-11. The j-th sub-image is obtained by imaging the data collected by the radiometer array in the j-th row, where 1≤j≤n; as well as The terahertz wave image of the target under test is obtained from all sub-images.

17. The image generation method according to claim 16, wherein, The terahertz wave image of the target under test obtained from all sub-images includes: Align the feature parts of the target in n sub-images to obtain n registration sub-images; The m-th column of pixels in the n registered sub-images is taken as the m-th column of the terahertz wave image of the target under test. By analyzing the column of pixels, a terahertz wave image of the target under test is obtained.

18. The image generation method according to claim 16, wherein, After obtaining n registration images, delete the pixel rows in the n registration images that were not detected by all radiometers.

Images