A terahertz micro-region scanning imaging method, system, terminal and storage medium

Abstract

The application discloses a terahertz micro-area scanning imaging method, system, terminal and storage medium, and belongs to the technical field of terahertz imaging. The method is as follows: a target micro-area determined on a pre-image of a to-be-tested sample is scanned according to a scanning starting position, and a current light path type is acquired in the scanning process; if the light path type is a coaxial light path, the positioning of a current test point is determined based on a visible light reflection intensity value and an image matching algorithm, the target micro-area is identified according to the visible light reflection intensity value and the positioning of the current test point, and the target micro-area is scanned and imaged according to a terahertz transmission intensity value; if the light path type is a non-coaxial light path, the positioning of the current test point is determined in combination with a pre-set shift lens, and a terahertz scanning image of the target micro-area is generated according to a terahertz transmission intensity value or a terahertz reflection intensity value. Therefore, the application can realize the following effects: the pre-scanning link is omitted, different test point synchronous positioning is performed according to different light path characteristics, and the accuracy of a scanning imaging result is improved.

Description

Technical Field

[0001] This invention relates to the field of terahertz imaging technology, and in particular to a terahertz micro-area scanning imaging method, system, terminal, and storage medium. Background Technology

[0002] Terahertz waves, due to their strong penetrating power, low photon energy, and good transmittance through nonpolar materials, have shown broad application prospects in fields such as nondestructive testing, biomedical imaging, and security inspection. Terahertz micro-region imaging (THz Micro-region Imaging) technology focuses a terahertz beam to the micrometer scale, scans the sample point-by-point, and acquires information such as the intensity and phase of transmitted or reflected signals, thereby reconstructing a two-dimensional image of the sample's micro-region. However, in the micro-region imaging process, how to quickly and accurately locate the target micro-region and how to avoid the inefficiency caused by multiple scans remain technical challenges that require further research.

[0003] Currently, most common terahertz micro-area scanning imaging methods employ a multi-scan strategy combining pre-scanning and fine scanning. First, a large area of ​​the sample (the general area) is rapidly pre-scanned with low resolution and large step intervals. Based on the pre-scanned image, the target area is manually selected. Then, a fine scan (the micro-area) is performed with high resolution and small step intervals. This approach, combining general and micro-area scanning, involves multiple scans, resulting in excessively long overall time and low imaging efficiency. Furthermore, the need for multiple manual selections or switching between the low-resolution pre-scanning and high-resolution fine scanning leads to low automation. Additionally, the displacement of the stage introduces positioning errors, causing deviations in the actual coordinate range of the sample's micro-area and resulting in inaccurate final micro-area imaging. Some existing technologies attempt to replace the pre-scanning stage with a stage-shifted "pre-image" to shorten the time, but stage misalignment easily introduces positioning errors, causing deviations between the actual scanned area and the target micro-area. Therefore, current terahertz micro-area scanning imaging technology, which uses multiple scans, lacks synchronous and accurate positioning, resulting in deviations in the scanning imaging results. Summary of the Invention

[0004] This invention proposes a terahertz micro-area scanning imaging method, system, terminal, and storage medium, which solves the problem of deviations in scanning imaging results caused by the lack of synchronous and accurate positioning in existing terahertz micro-area scanning imaging methods that rely on multiple scans. This invention eliminates the pre-scanning step, directly determining the target micro-area and the scanning start position to reduce the number of scans. Then, an image processing automatic matching algorithm is used on the coaxial optical path to synchronously locate test points and identify the target micro-area in real time during the scanning process. On the non-coaxial optical path, test points are synchronously located via the optical axis, improving the accuracy of the scanning imaging results.

[0005] To achieve the above objectives, embodiments of the present invention provide a terahertz micro-area scanning imaging method applied to a coaxial optical path. The method includes: acquiring a pre-image of the sample to be tested; determining a target micro-area and a scanning start position on the pre-image; scanning the target micro-area based on the scanning start position and acquiring the current optical path type; if the current optical path is a coaxial optical path, the incident light wave includes terahertz waves and visible light waves; by acquiring terahertz transmission intensity values ​​and visible light reflection intensity values, and based on the visible light reflection intensity values, the pre-image, and a preset image matching algorithm, determining the target micro-area and the current optical path type; The location of the current test point is determined, and the target micro-area is identified based on the visible light reflection intensity value and the location of the current test point. A preset target scanning mode is started, and the target micro-area is scanned and imaged based on the terahertz transmission intensity value to obtain a terahertz scanning image of the target micro-area. If the current optical path is a non-coaxial optical path, the incident light wave only includes terahertz waves. The location of the current test point is determined based on the preset tilt-shift lens, the pre-shot image, and the preset image matching algorithm, and a terahertz scanning image of the target micro-area is generated based on the terahertz transmission intensity value or the terahertz reflection intensity value.

[0006] This invention proposes a terahertz micro-area scanning imaging method. It identifies the target micro-area on a pre-captured image of the sample under test and determines the scanning start position, eliminating the need for a pre-scanning step. During the target micro-area scanning process, different terahertz scanning imaging procedures are proposed based on different optical path types. Specifically, based on a coaxial optical path design, terahertz transmission intensity and visible light reflection intensity values ​​are acquired. A preset image matching algorithm is then used to perform real-time image feature matching analysis between the image generated from the visible light reflection intensity value and the pre-captured image to accurately locate the current test point, generating a terahertz scanning image of the target micro-area. Based on a non-coaxial optical path design, the optical axis of a tilt-shift lens is combined with a preset image matching algorithm and the pre-captured image to determine the location of the current test point, and a terahertz scanning image of the target micro-area is generated based on the terahertz transmission intensity or terahertz reflection intensity value. Therefore, an image matching algorithm is used in the coaxial optical path to identify the target micro-region in real time during the scanning process, and an optical axis combined with the image matching algorithm is used in the non-coaxial optical path to locate the starting point of the target micro-region scanning. Moreover, the scanning can be started directly without the need for a separate low-resolution pre-scanning process, thus improving the accuracy of the scanning imaging results.

[0007] Furthermore, if the current optical path is a coaxial optical path, the incident light wave includes terahertz waves and visible light waves. By acquiring the terahertz transmission intensity value and the visible light reflection intensity value, the location of the current test point is determined based on the visible light reflection intensity value, the pre-shot image, and a preset image matching algorithm. The target micro-region is identified based on the visible light reflection intensity value and the location of the current test point. A preset target scanning mode is activated, and the target micro-region is scanned and imaged based on the terahertz transmission intensity value to obtain a terahertz scan image of the target micro-region. This includes: combining the terahertz waves and visible light waves during the target micro-region scanning process into a coaxial hybrid. The coaxial hybrid light wave is focused onto the sample to be tested, and the terahertz transmission intensity and visible light reflection intensity from the sample are detected respectively. A real-time scanning image is generated based on the visible light reflection intensity, and the real-time scanning image is matched with the pre-captured image based on a preset image matching algorithm to obtain the location of the current test point. If the location of the current test point is within the coordinate range of the target micro-region, a preset target scanning mode is started, and the target micro-region is scanned and imaged with terahertz transmission and visible light reflection based on the terahertz transmission intensity to obtain the terahertz scanning image of the target micro-region.

[0008] In the above scheme, based on the coaxial optical path design, terahertz waves and visible light waves are combined into a coaxial hybrid light wave. This allows the visible light reflection intensity value to generate a scanned image in real time during the scanning process. A preset image matching algorithm is then used to perform feature matching between this real-time scanned image and a pre-captured image, thereby accurately locating whether the current test point is within the target micro-region. Thus, this scheme achieves real-time identification of the target micro-region during scanning using an image matching algorithm, without requiring a separate low-resolution pre-scan; it automatically switches to target scanning mode when the current test point is detected to have entered the target micro-region, improving scanning imaging efficiency and the accuracy of the scanning results.

[0009] Furthermore, the coaxial optical path includes a first beam splitter, a second beam splitter, a first axis-shifting parabolic mirror, a second axis-shifting parabolic mirror, a first terahertz detector, and a photodetector; the step of focusing the coaxial mixed light wave onto the sample to be tested and detecting the terahertz transmission intensity and visible light reflection intensity from the sample to be tested includes: based on the first beam splitter, combining the parallel-incident terahertz wave and the parallel-incident visible light wave into a parallel mixed light wave; based on the first axis-shifting parabolic mirror, reflecting the parallel mixed light wave... The light is refracted and focused onto the sample to be tested; based on the second axis-shifting parabolic mirror, the terahertz wave reflected from the sample to be tested is refracted into a parallel terahertz wave, which is then incident on the first terahertz detector, and the terahertz transmission intensity value is detected by the first terahertz detector; based on the first axis-shifting parabolic mirror, the visible light wave reflected from the sample to be tested and returning along the original incident light path is refracted into a parallel visible light wave, which is then split by the second beam splitter and incident on the photodetector, and the visible light reflection intensity value is detected by the photodetector.

[0010] In the above scheme, terahertz waves and visible light waves are combined into a parallel mixed light wave by a first beam splitter, which is then focused onto the sample by a first axis-shifting parabolic mirror. The transmitted terahertz wave enters the first terahertz detector through a second axis-shifting parabolic mirror, while the reflected visible light wave returns along the original path and enters the photodetector through a second beam splitter. Combined with the coaxial optical path structure, the terahertz transmission signal and the visible light reflection signal at the same focused spot are acquired synchronously. This ensures the strict spatial correspondence between the two signals and provides a real-time and coaxial visible light reference image for subsequent image matching, thus providing a reliable data foundation for accurate positioning and helping to improve the accuracy of the scanning imaging results.

[0011] Furthermore, the step of generating a real-time scanned image using the visible light reflection intensity value and matching the real-time scanned image with the pre-captured image based on a preset image matching algorithm to obtain the location of the current test point includes: obtaining point-by-point visible light reflection intensity values; stitching the point-by-point visible light reflection intensity values ​​into a visible light scanned image and using the visible light scanned image as the real-time scanned image; and analyzing the positional relationship between the current test point in the real-time scanned image and the target micro-region in the pre-captured image in real time based on the preset image matching algorithm to obtain the location of the current test point.

[0012] In the above scheme, the visible light reflectance intensity values ​​are acquired point by point and stitched together to form a visible light scan image as a real-time scan image. Then, a preset image matching algorithm is used to analyze the positional relationship between the current test point and the target micro-region in the pre-captured image in real time. Thus, the traditional two-stage process of "pre-scanning followed by fine scanning" is integrated into an online discrimination process of "scanning and matching simultaneously." This allows the system to determine in real time whether it has entered the target micro-region during the scanning process, eliminating the need for manual selection or additional pre-scanning. This improves the degree of automation and positioning response speed, and helps to improve the accuracy of the scanning imaging results.

[0013] Furthermore, if the current optical path is a non-coaxial optical path, then the incident light wave only includes terahertz waves. The location of the current test point is determined based on a preset tilt-shift lens, the pre-captured image, and the preset image matching algorithm. A terahertz scanning image of the target micro-region is generated based on the terahertz transmission intensity value or the terahertz reflection intensity value. This includes: real-time imaging of the sample under test using a preset tilt-shift lens to obtain a real-time captured image; intersecting the optical axis of the incident terahertz wave with the optical axis of the tilt-shift lens at the current test point on the sample under test; and matching the real-time captured image with the pre-captured image using a preset image matching algorithm. The pre-captured image is subjected to real-time image feature matching analysis to determine the location of the current test point; the sample to be tested is moved so that the location of the current test point is consistent with the coordinates of the scanning start position of the target micro-region, and then the target micro-region is scanned according to the preset target scanning mode; if the non-coaxial optical path is the first non-coaxial optical path, the terahertz transmission intensity value of the current test point is collected to generate the terahertz scanning image of the target micro-region; if the non-coaxial optical path is the second non-coaxial optical path, the terahertz transmission intensity value and the terahertz reflection intensity value of the current test point are collected to generate the terahertz scanning image of the target micro-region.

[0014] In the above scheme, the target micro-region on the pre-shot image of the sample to be tested is determined, and the scanning start position is determined, eliminating the pre-scanning step. Then, based on the non-coaxial optical path design, a tilt-shift lens is used to intersect the optical axis of the incident terahertz wave with the optical axis of the lens at the current test point on the sample to be tested. After real-time image feature matching analysis of the real-time captured image obtained by the tilt-shift lens and the pre-shot image through a preset image matching algorithm, the location of the current test point is determined. At the same time, in the first non-coaxial optical path, the terahertz transmission intensity value of the current test point is collected to generate the terahertz scanning image of the target micro-region. In the second non-coaxial optical path, the terahertz transmission intensity value and terahertz reflection intensity value of the current test point are collected to generate the terahertz scanning image of the target micro-region. High-resolution scanning of the target micro-region can be performed directly without low-resolution pre-scanning. During the scanning process, synchronous and accurate positioning is achieved through the tilt-shift lens, which reduces the number of scans. Using different non-coaxial optical paths for scanning imaging avoids the light energy loss introduced by the beam splitter in the coaxial optical path, effectively improving the accuracy of the scanning imaging results.

[0015] Furthermore, the first non-coaxial optical path includes a first tilt-shift parabolic mirror, a second tilt-shift parabolic mirror, and a first terahertz detector; if the non-coaxial optical path is the first non-coaxial optical path, acquiring the terahertz transmission intensity value of the current test point and generating a terahertz scanning image of the target micro-region includes: based on the first tilt-shift parabolic mirror, reflecting, refracting, and focusing the parallel incident terahertz wave onto the sample to be tested; based on the second tilt-shift parabolic mirror, reflecting and refracting the terahertz wave transmitted through the sample to be tested into a parallel terahertz wave, detecting the transmission intensity of the parallel terahertz wave incident on the first terahertz detector, and corresponding the intensity value of the axis center pixel point of the real-time imaging of the tilt-shift lens to the terahertz transmission intensity value of the current test point; stitching the terahertz transmission intensity values ​​point by point to obtain an array image as the terahertz scanning image of the target micro-region.

[0016] In the above scheme, a first axis-shifting parabolic mirror focuses parallel terahertz waves onto the sample, and the transmitted terahertz waves enter the first terahertz detector via a second axis-shifting parabolic mirror. Simultaneously, the intensity value of the axial pixel in the real-time imaging of the axis-shifting lens is directly mapped to the terahertz transmission intensity value of the current test point, thus achieving point-to-point spatial positioning without the need for an additional visible light detector. Therefore, the first non-coaxial optical path simplifies the optical path structure while reducing light energy loss, and the method of stitching the point-by-point intensity values ​​into an array imaging ensures the spatial resolution of the final image, effectively improving the accuracy of the scanning imaging results.

[0017] Furthermore, the second non-coaxial optical path includes a first axis-shifting parabolic mirror, a second axis-shifting parabolic mirror, a third beam splitter, a first terahertz detector, and a second terahertz detector; if the non-coaxial optical path is the second non-coaxial optical path, acquiring the terahertz transmission intensity value and terahertz reflection intensity value at the current test point to generate a terahertz scanning image of the target micro-region includes: based on the first axis-shifting parabolic mirror, reflecting, refracting, and focusing the parallel incident terahertz wave onto the sample to be tested; based on the second axis-shifting parabolic mirror, reflecting and refracting the terahertz wave transmitted through the sample to be tested into a parallel terahertz wave, and focusing it onto the first terahertz detector. The transmission intensity of the parallel terahertz wave is detected, and the intensity value of the axial center pixel corresponding to the real-time imaging of the tilt-shift lens is used as the terahertz transmission intensity value of the current test point. Based on the first tilt-shift parabolic mirror, the parallel terahertz wave reflected by the sample is reflected and refracted, then split by the third beam splitter and incident on the second terahertz detector. The reflection intensity is detected by the second terahertz detector to obtain the terahertz reflection intensity value of the current test point. The terahertz transmission intensity value and the terahertz reflection intensity value of the current test point are stitched together point by point to obtain the area array imaging as the terahertz scanning image of the target micro-region.

[0018] In the above scheme, the incident terahertz wave is focused onto the sample by a first axis-shifting parabolic mirror. The transmitted component then enters the first terahertz detector via a second axis-shifting parabolic mirror, while the reflected component is refracted by the first axis-shifting parabolic mirror and split by a third beam splitter before entering the second terahertz detector. The axis-shifting lens still provides the location of the axial pixel. Thus, by adding a third beam splitter and a second terahertz detector to the first non-coaxial optical path, both transmitted and reflected terahertz signals can be acquired simultaneously at the same scanning point, enriching the dimensions of imaging information and helping to improve the accuracy of the scanning imaging results.

[0019] This invention also provides a terahertz micro-area scanning imaging system, including a data acquisition module, a light wave type confirmation module, a first scanning imaging module, and a second scanning imaging module; wherein: the data acquisition module is used to acquire a pre-shot image of the sample to be tested, determine the target micro-area on the pre-shot image, and determine the scanning start position; the light wave type confirmation module is used to scan the target micro-area based on the scanning start position and acquire the current optical path type; the first scanning imaging module is used to, if the current optical path is a coaxial optical path, then the incident light wave includes terahertz waves and visible light waves, by acquiring the terahertz transmission intensity value and the visible light reflection intensity value, based on the visible light reflection intensity... The first module determines the location of the current test point based on the intensity value, the pre-captured image, and the preset image matching algorithm. It then identifies the target micro-area based on the visible light reflection intensity value and the location of the current test point. A preset target scanning mode is activated, and the target micro-area is scanned and imaged based on the terahertz transmission intensity value to obtain a terahertz scan image of the target micro-area. The second scanning imaging module is used to determine the location of the current test point based on the preset tilt-shift lens, the pre-captured image, and the preset image matching algorithm if the current optical path is a non-coaxial optical path, meaning the incident light wave only includes terahertz waves. It also generates a terahertz scan image of the target micro-area based on the terahertz transmission intensity value or the terahertz reflection intensity value.

[0020] This invention proposes a terahertz micro-area scanning imaging system. It identifies the target micro-area on a pre-captured image of the sample under test and determines the scanning start position, eliminating the need for a pre-scanning step. During the target micro-area scanning process, different terahertz scanning imaging procedures are proposed based on different optical path types. Specifically, based on a coaxial optical path design, terahertz transmission intensity and visible light reflection intensity values ​​are acquired. A preset image matching algorithm is then used to perform real-time image feature matching analysis between the image generated from the visible light reflection intensity value and the pre-captured image to accurately locate the current test point, generating a terahertz scanning image of the target micro-area. Based on a non-coaxial optical path design, the optical axis of a tilt-shift lens, combined with a preset image matching algorithm and the pre-captured image, determines the location of the current test point, and a terahertz scanning image of the target micro-area is generated based on the terahertz transmission intensity or terahertz reflection intensity value. Therefore, an image matching algorithm is used in the coaxial optical path to identify the target micro-region in real time during the scanning process, and an optical axis combined with the image matching algorithm is used in the non-coaxial optical path to locate the starting point of the target micro-region scanning. Moreover, the scanning can be started directly without the need for a separate low-resolution pre-scanning process, thus improving the accuracy of the scanning imaging results.

[0021] A terahertz micro-area scanning imaging terminal includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the terahertz micro-area scanning imaging method.

[0022] A terahertz micro-area scanning imaging storage medium includes a stored computer program, wherein the computer program, when running, controls the device containing the storage medium to execute the terahertz micro-area scanning imaging method. Attached Figure Description

[0023] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 A schematic flowchart of a terahertz micro-area scanning imaging method provided in a certain embodiment of the present invention; Figure 2 A schematic diagram of the coaxial optical path structure of a terahertz micro-area scanning imaging method provided in a certain embodiment of the present invention; Figure 3 This is a schematic diagram of the first non-coaxial optical path structure of a terahertz micro-area scanning imaging method provided in a certain embodiment of the present invention; Figure 4 A schematic diagram of the second non-coaxial optical path structure of a terahertz micro-area scanning imaging method provided in a certain embodiment of the present invention; Figure 5 A schematic diagram of the module structure of a terahertz micro-area scanning imaging system provided in one embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0027] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0030] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0031] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0032] Example 1 To address the issue of inaccurate and synchronous positioning in existing terahertz micro-area scanning imaging techniques that rely on multiple scans, leading to deviations in the imaging results, see [link to relevant documentation]. Figure 1 , Figure 1 This is one embodiment provided by the present invention. For example... Figure 1 As shown in the figure, an embodiment of the present invention proposes a method for use in a coaxial optical path, the method comprising steps 101 to 104, the specific steps of which are as follows: Step 101: Obtain a pre-shot image of the sample to be tested, determine the target micro-region and the scanning start position on the pre-shot image; Step 102: Scan the target micro-area based on the scan start position and obtain the current optical path type; Step 103: If the current optical path is a coaxial optical path, the incident light wave includes terahertz waves and visible light waves. By obtaining the terahertz transmission intensity value and the visible light reflection intensity value, the location of the current test point is determined based on the visible light reflection intensity value, the pre-shot image and the preset image matching algorithm. The target micro-area is identified according to the visible light reflection intensity value and the location of the current test point. The preset target scanning mode is started and the target micro-area is scanned and imaged according to the terahertz transmission intensity value to obtain the terahertz scanning image of the target micro-area. Step 104: If the current optical path is a non-coaxial optical path, the incident light wave only includes terahertz waves. Based on the preset tilt-shift lens, the pre-shot image and the preset image matching algorithm, the location of the current test point is determined, and the terahertz scanning image of the target micro-area is generated according to the terahertz transmission intensity value or the terahertz reflection intensity value.

[0033] In one specific implementation method, under coaxial optical path conditions, the sample to be tested is first moved to the pre-image position by the XZ displacement stage, and then the programmable industrial camera kit completes the pre-image and saves the pre-image. The target micro-area is manually selected on the pre-image, and the coordinates (x, z) of the scanning start position are determined. Subsequently, based on the reference coordinates (x-△, z-△), where "△" represents a small distance close to the starting coordinates (x, z), the sample to be tested is moved to the appropriate scanning position by the XZ displacement stage, and the scanning of the target micro-area is initiated. Then, the current optical path type is obtained. It is worth mentioning that, under non-coaxial optical path conditions, the sample to be tested does not need to be moved to the pre-image position by the XZ displacement stage for pre-image; instead, the pre-image is taken directly in place by the tilt-shift industrial vision kit, which is equipped with a tilt-shift lens. If the current optical path is a coaxial optical path, the incident light wave simultaneously contains terahertz waves and visible light waves. The terahertz transmission intensity value and visible light reflection intensity value are obtained by the THz detector and photodetector in the coaxial optical path, respectively. A preset image matching algorithm is used to perform real-time image feature matching analysis on the image generated based on the visible light reflection intensity value and the pre-captured image to determine the location of the current test point. The preset image matching algorithm can be SIFT, SURF, or ORB corner feature matching algorithm, etc. Then, the location coordinates of the current test point and the coordinate range of the target micro-area are used to identify whether the current test point is within the target micro-area. If so, the preset target scanning mode is started to scan and image the target micro-area, and finally the terahertz scan image of the target micro-area is obtained. The preset target scanning mode can be a high-resolution scanning mode. If the current optical path is a non-coaxial optical path, the incident light wave only contains terahertz waves. In this case, the location of the current test point is directly determined by the intersection of the optical axis of the terahertz wave and the optical axis of the non-coaxial tilt-shift lens. The intersection of the two optical axes is the center pixel of the image captured by the tilt-shift lens. At the same time, a preset image matching algorithm is used to perform real-time image feature matching analysis on the real-time captured image and the pre-captured image of the tilt-shift lens to determine the location of the current test point. Then, the XZ displacement workpiece stage is used to move the sample under test so that the positioning coordinates of the current test point are consistent with the starting position coordinates of the target micro-area. Then, the preset target scanning mode is started to scan and image the target micro-area, and a terahertz scanning image of the target micro-area is generated based on the terahertz transmission intensity value or terahertz reflection intensity value collected by the THz detector.

[0034] This invention proposes a terahertz micro-area scanning imaging method. It identifies the target micro-area on a pre-captured image of the sample under test and determines the scanning start position, eliminating the need for a pre-scanning step. During the target micro-area scanning process, different terahertz scanning imaging procedures are proposed based on different optical path types. Specifically, based on a coaxial optical path design, terahertz transmission intensity and visible light reflection intensity values ​​are acquired. A preset image matching algorithm is then used to perform real-time image feature matching analysis between the image generated from the visible light reflection intensity value and the pre-captured image to accurately locate the current test point, generating a terahertz scanning image of the target micro-area. Based on a non-coaxial optical path design, the optical axis of a tilt-shift lens is combined with a preset image matching algorithm and the pre-captured image to determine the location of the current test point, and a terahertz scanning image of the target micro-area is generated based on the terahertz transmission intensity or terahertz reflection intensity value. Therefore, an image matching algorithm is used in the coaxial optical path to identify the target micro-region in real time during the scanning process, and an optical axis combined with the image matching algorithm is used in the non-coaxial optical path to locate the starting point of the target micro-region scanning. Moreover, the scanning can be started directly without the need for a separate low-resolution pre-scanning process, thus improving the accuracy of the scanning imaging results.

[0035] In a preferred embodiment, if the current optical path is a coaxial optical path, the incident light wave includes terahertz waves and visible light waves. By acquiring terahertz transmission intensity values ​​and visible light reflection intensity values, the location of the current test point is determined based on the visible light reflection intensity value, the pre-captured image, and a preset image matching algorithm. The target micro-region is then identified based on the visible light reflection intensity value and the location of the current test point. A preset target scanning mode is initiated, and the target micro-region is scanned and imaged based on the terahertz transmission intensity value to obtain a terahertz scan image of the target micro-region. This includes: combining the terahertz waves and visible light waves during the target micro-region scanning process into a coaxial hybrid image. The coaxial mixed light wave is focused onto the sample to be tested, and the terahertz transmission intensity and visible light reflection intensity from the sample are detected respectively. A real-time scanning image is generated based on the visible light reflection intensity, and the real-time scanning image is matched with the pre-captured image based on a preset image matching algorithm to obtain the location of the current test point. If the location of the current test point is within the coordinate range of the target micro-region, a preset target scanning mode is started, and the target micro-region is scanned and imaged by terahertz transmission and visible light reflection according to the terahertz transmission intensity, to obtain the terahertz scanning image of the target micro-region.

[0036] For example, when the current optical path is determined to be a coaxial optical path, the terahertz wave and visible light wave during the target micro-area scanning process are first combined into a coaxial mixed light wave. This coaxial mixed light wave is then focused onto the sample under test, and the terahertz transmission intensity and visible light reflection intensity from the sample are detected. Subsequently, a real-time scanning image is generated using the collected point-by-point visible light reflection intensity values. This real-time scanning image is then matched with a pre-captured image using a preset image matching algorithm to obtain the corresponding location of the current test point in the pre-captured image. If the location of the current test point falls within the coordinate range of the pre-selected target micro-area, a preset target scanning mode is immediately activated. The terahertz transmission intensity of the preset target scanning mode is set to be the same as the terahertz transmission intensity value of the sample under test. Then, the target micro-area is simultaneously scanned and imaged using the preset target scanning mode, resulting in a terahertz scanning image of the target micro-area.

[0037] In the above scheme, based on the coaxial optical path design, terahertz waves and visible light waves are combined into a coaxial hybrid light wave. This allows the visible light reflection intensity value to generate a scanned image in real time during the scanning process. A preset image matching algorithm is then used to perform feature matching between this real-time scanned image and a pre-captured image, thereby accurately locating whether the current test point is within the target micro-region. Thus, this scheme achieves real-time identification of the target micro-region during scanning using an image matching algorithm, without requiring a separate low-resolution pre-scan; it automatically switches to target scanning mode when the current test point is detected to have entered the target micro-region, improving scanning imaging efficiency and the accuracy of the scanning results.

[0038] In a preferred embodiment, the coaxial optical path includes a first beam splitter, a second beam splitter, a first axis-shifting parabolic mirror, a second axis-shifting parabolic mirror, a first terahertz detector, and a photodetector; the step of focusing the coaxial mixed light wave onto the sample to be tested and detecting the terahertz transmission intensity and visible light reflection intensity from the sample to be tested includes: based on the first beam splitter, combining the parallel-incident terahertz wave and the parallel-incident visible light wave into a parallel mixed light wave; based on the first axis-shifting parabolic mirror, combining the parallel mixed light wave... The light is reflected, refracted, and focused onto the sample under test. Based on the second axis-shifting parabolic mirror, the terahertz wave transmitted through the sample under test is reflected and refracted into a parallel terahertz wave, which is then incident on the first terahertz detector, and the terahertz transmission intensity value is detected by the first terahertz detector. Based on the first axis-shifting parabolic mirror, the visible light wave reflected from the sample under test and returning along the original incident light path is reflected and refracted into a parallel visible light wave, which is then split by the second beam splitter and incident on the photodetector, and the visible light reflection intensity value is detected by the photodetector.

[0039] For example, see Figure 2 , Figure 2This is a schematic diagram of the coaxial optical path structure of a terahertz micro-area scanning imaging method according to a certain embodiment of the present invention; as shown. Figure 2 As shown, in the coaxial optical path, terahertz wave 1 is the incident light wave, which is a parallel terahertz wave; white light 2 is the incident light wave, which is a parallel visible light wave. The first beam splitter 22 merges terahertz wave 1 and white light 2 into a coaxial mixed light wave 25, which is transmitted through the second beam splitter 23. The first axis-shifting parabolic mirror 12 reflects, refracts, and focuses the parallel coaxial mixed light wave 25 onto the sample 14 to be tested. The focused terahertz wave 1 is transmitted through the sample 14 to the second axis-shifting parabolic mirror 13, where it is refracted into a parallel transmitted terahertz wave 11 and then incident on the transmission THz detector 15. In the coaxial optical path, the transmission THz detector 15 is characterized as the first terahertz detector, completing the single-point terahertz signal transmission intensity detection and obtaining the terahertz transmission intensity value. Simultaneously, the focused white light 2, after being incident on the sample 14, is reflected back along the original incident light path and incident on the first axis-shifting parabolic mirror 12, where it is refracted into a parallel visible light wave, i.e., reflected white light 21. This reflected light is then split by the second beam splitter 23 and finally incident on the photodetector 24, completing the detection of the single-point white light signal reflection intensity and obtaining the visible light reflection intensity value. Furthermore, the white light source 28 emits a white light beam 29, which is used to capture pre-images via the industrial lens 27 and the industrial camera 26.

[0040] In the above scheme, terahertz waves and visible light waves are combined into a parallel mixed light wave by a first beam splitter, which is then focused onto the sample by a first axis-shifting parabolic mirror. The transmitted terahertz wave enters the first terahertz detector through a second axis-shifting parabolic mirror, while the reflected visible light wave returns along the original path and enters the photodetector through a second beam splitter. Combined with the coaxial optical path structure, the terahertz transmission signal and the visible light reflection signal at the same focused spot are acquired synchronously. This ensures the strict spatial correspondence between the two signals and provides a real-time and coaxial visible light reference image for subsequent image matching, thus providing a reliable data foundation for accurate positioning and helping to improve the accuracy of the scanning imaging results.

[0041] In a preferred embodiment, the step of generating a real-time scanning image using the visible light reflectance intensity value and matching the real-time scanning image with the pre-captured image based on a preset image matching algorithm to obtain the location of the current test point includes: obtaining point-by-point visible light reflectance intensity values; stitching the point-by-point visible light reflectance intensity values ​​into a visible light scanning image, and using the visible light scanning image as the real-time scanning image; and analyzing the positional relationship between the current test point in the real-time scanning image and the target micro-region in the pre-captured image in real time based on the preset image matching algorithm to obtain the location of the current test point.

[0042] For example, firstly, point-by-point visible light reflectance intensity values ​​are obtained. Then, these point-by-point intensity values ​​are stitched together in the scanning order to form a complete visible light scan image, which is used as the real-time scan image. Next, based on a preset image matching algorithm, the positional relationship between the current test point in the real-time scan image and the target micro-region in the pre-captured image is analyzed in real time. The preset image matching algorithm can be SIFT, SURF, or ORB corner feature matching algorithms, etc. One implementable example is to perform feature point matching between the imaged area in the real-time scan image and the pre-captured image, thereby deducing the coordinates of the current test point in the coordinate system of the pre-captured image, obtaining the location of the current test point, and then using it to determine whether it falls within the target micro-region.

[0043] In the above scheme, the visible light reflectance intensity values ​​are acquired point by point and stitched together to form a visible light scan image as a real-time scan image. Then, a preset image matching algorithm is used to analyze the positional relationship between the current test point and the target micro-region in the pre-captured image in real time. Thus, the traditional two-stage process of "pre-scanning followed by fine scanning" is integrated into an online discrimination process of "scanning and matching simultaneously." This allows the system to determine in real time whether it has entered the target micro-region during the scanning process, eliminating the need for manual selection or additional pre-scanning. This improves the degree of automation and positioning response speed, and helps to improve the accuracy of the scanning imaging results.

[0044] In a preferred embodiment, if the current optical path is a non-coaxial optical path, then the incident light wave only includes terahertz waves. The location of the current test point is determined based on a preset tilt-shift lens, the pre-captured image, and the preset image matching algorithm. A terahertz scanning image of the target micro-region is generated based on the terahertz transmission intensity value or the terahertz reflection intensity value. This includes: real-time imaging of the sample under test using a preset tilt-shift lens to obtain a real-time captured image; intersecting the optical axis of the incident terahertz wave with the optical axis of the tilt-shift lens at the current test point on the sample under test; and matching the real-time captured image with the pre-captured image using a preset image matching algorithm. The system performs real-time image feature matching analysis on the pre-captured image to determine the location of the current test point; moves the sample to be tested so that the location of the current test point is consistent with the coordinates of the scanning start position of the target micro-region, and then scans the target micro-region according to the preset target scanning mode; if the non-coaxial optical path is the first non-coaxial optical path, the terahertz transmission intensity value of the current test point is collected to generate a terahertz scanning image of the target micro-region; if the non-coaxial optical path is the second non-coaxial optical path, the terahertz transmission intensity value and terahertz reflection intensity value of the current test point are collected to generate a terahertz scanning image of the target micro-region.

[0045] For example, if the current optical path is a non-coaxial optical path, the incident light wave only contains terahertz waves. Real-time imaging of the sample under test is performed using a tilt-shift lens. In this embodiment, the tilt-shift lens can be characterized as a Scherm lens. The optical path between the image plane of the industrial camera, the perpendicular plane of the tilt-shift lens's optical axis, and the object plane of the sample under test satisfies Scherm's law. Simultaneously, the optical axis of the incident terahertz wave intersects the optical axis of the tilt-shift lens at the current test point on the sample under test. Furthermore, the coordinates of the axisymmetric pixel corresponding to the real-time imaging by the tilt-shift lens accurately reflect the position of the current test point. Then, a preset image matching algorithm is used to perform real-time image feature matching analysis between the real-time captured image and the pre-captured image to deduce the coordinates of the current test point in the pre-captured image coordinate system, thereby obtaining the location of the current test point. Furthermore, depending on the different optical path configurations, the non-coaxial optical path is further divided into a first non-coaxial optical path and a second non-coaxial optical path. The first non-coaxial optical path only includes light wave transmission, while the second non-coaxial optical path includes both light wave transmission and light wave reflection. If it is the first non-coaxial optical path, only the terahertz transmission intensity value of the current test point is collected to generate a terahertz scanning image of the target micro-area; if it is the second non-coaxial optical path, both the terahertz transmission intensity value and the terahertz reflection intensity value of the current test point are collected to generate a terahertz scanning image of the target micro-area containing two contrast information.

[0046] In the above scheme, the target micro-region on the pre-shot image of the sample to be tested is determined, and the scanning start position is determined, eliminating the pre-scanning step. Then, based on the non-coaxial optical path design, a tilt-shift lens is used to intersect the optical axis of the incident terahertz wave with the optical axis of the lens at the current test point on the sample to be tested. After real-time image feature matching analysis of the real-time captured image obtained by the tilt-shift lens and the pre-shot image through a preset image matching algorithm, the location of the current test point is determined. At the same time, in the first non-coaxial optical path, the terahertz transmission intensity value of the current test point is collected to generate the terahertz scanning image of the target micro-region. In the second non-coaxial optical path, the terahertz transmission intensity value and terahertz reflection intensity value of the current test point are collected to generate the terahertz scanning image of the target micro-region. High-resolution scanning of the target micro-region can be performed directly without low-resolution pre-scanning. During the scanning process, synchronous and accurate positioning is achieved through the tilt-shift lens, which reduces the number of scans. Using different non-coaxial optical paths for scanning imaging avoids the light energy loss introduced by the beam splitter in the coaxial optical path, effectively improving the accuracy of the scanning imaging results.

[0047] In a preferred embodiment, the first non-coaxial optical path includes a first tilt-shift parabolic mirror, a second tilt-shift parabolic mirror, and a first terahertz detector. If the non-coaxial optical path is the first non-coaxial optical path, acquiring the terahertz transmission intensity value at the current test point and generating a terahertz scanning image of the target micro-region includes: based on the first tilt-shift parabolic mirror, reflecting, refracting, and focusing a parallel incident terahertz wave onto the sample to be tested; based on the second tilt-shift parabolic mirror, reflecting and refracting the terahertz wave transmitted through the sample to be tested into a parallel terahertz wave; detecting the transmission intensity of the parallel terahertz wave incident on the first terahertz detector, and corresponding the intensity value of the axis-centric pixel point to the real-time imaging of the tilt-shift lens as the terahertz transmission intensity value at the current test point; and stitching the terahertz transmission intensity values ​​point-by-point to obtain an array image as the terahertz scanning image of the target micro-region.

[0048] In the coaxial scheme, the terahertz wave needs to pass through the beam splitter twice, with each pass attenuating by approximately 50%, resulting in a total attenuation of at least 75%. This leads to excessively low terahertz energy reaching the sample, affecting image quality. Therefore, this invention proposes a shift-axis micro-area scanning imaging scheme based on Scherm's law, avoiding the use of a beam splitter.

[0049] For example, see Figure 3 , Figure 3 This is a schematic diagram of the first non-coaxial optical path structure of a terahertz micro-area scanning imaging method according to a certain embodiment of the present invention; as shown. Figure 3 As shown, the industrial camera 26 and the tilt-shift lens 4 are connected by the Scham connector 3 to form a tilt-shift industrial vision kit that conforms to Scham's law. Terahertz wave 1 is the incident light wave; it is a parallel terahertz wave, and the angle between its refracted optical axis and the optical axis of the tilt-shift lens 4 is an angle θ. The two axes intersect at the test point of the sample 14 and coincide with the focal point of the incident terahertz wave 1. The first tilt-shift parabolic mirror 12 reflects, refracts, and focuses the parallel terahertz wave onto the sample. The transmitted terahertz wave 11 is reflected and refracted by the second tilt-shift parabolic mirror 13 into a parallel terahertz wave, which is then incident on the transmission THz detector 15 to complete the single-point terahertz signal transmission intensity detection. The transmission THz detector 15 is characterized as the first terahertz detector. White light source 28 emits white light beam 29 for pre-photographing, but no white light is needed for detection during scanning because the intensity value of the axis-shift industrial vision kit in real-time imaging directly corresponds to the transmission intensity of the test point of the sample 14 under test, and the coordinates of the axis-shift pixel are used to accurately locate the position of the test point.

[0050] Specifically, the incident parallel terahertz wave is reflected, refracted, focused, and transmitted through the sample under test by the first axis-shifting parabolic mirror. It is then reflected and refracted again by the second axis-shifting parabolic mirror, becoming a parallel terahertz wave that is incident on the THz detector, completing the single-point terahertz signal transmission intensity detection. The single-point intensity value measured by the THz detector is then stitched together to form an array image. Simultaneously, a displacement stage drives the sample under test to move at controlled intervals in the XZ plane, achieving terahertz transmission micro-area scanning imaging of the sample. This completes high-resolution scanning imaging of the target micro-area of ​​the sample under test.

[0051] In the above scheme, a first axis-shifting parabolic mirror focuses parallel terahertz waves onto the sample, and the transmitted terahertz waves enter the first terahertz detector via a second axis-shifting parabolic mirror. Simultaneously, the intensity value of the axial pixel in the real-time imaging of the axis-shifting lens is directly mapped to the terahertz transmission intensity value of the current test point, thus achieving point-to-point spatial positioning without the need for an additional visible light detector. Therefore, the first non-coaxial optical path simplifies the optical path structure while reducing light energy loss, and the method of stitching the point-by-point intensity values ​​into an array imaging ensures the spatial resolution of the final image, effectively improving the accuracy of the scanning imaging results.

[0052] In a preferred embodiment, the second non-coaxial optical path includes a first axis-shifting parabolic mirror, a second axis-shifting parabolic mirror, a third beam splitter, a first terahertz detector, and a second terahertz detector. If the non-coaxial optical path is the second non-coaxial optical path, acquiring the terahertz transmission intensity value and terahertz reflection intensity value at the current test point to generate a terahertz scanning image of the target micro-region includes: based on the first axis-shifting parabolic mirror, reflecting, refracting, and focusing the parallel incident terahertz wave onto the sample to be tested; based on the second axis-shifting parabolic mirror, reflecting and refracting the terahertz wave transmitted through the sample to be tested into a parallel terahertz wave, and focusing the wave incident on the first terahertz detector. The parallel terahertz wave of the detector is transmitted to detect its intensity, and the intensity value of the axial pixel corresponding to the real-time imaging of the tilt-shift lens is used as the terahertz transmission intensity value of the current test point. Based on the first tilt-shift parabolic mirror, the parallel terahertz wave reflected by the sample is reflected and refracted, then split by the third beam splitter and incident on the second terahertz detector. The reflection intensity is detected by the second terahertz detector to obtain the terahertz reflection intensity value of the current test point. The terahertz transmission intensity value and the terahertz reflection intensity value of the current test point are stitched together point by point to obtain the area array imaging as the terahertz scanning image of the target micro-region.

[0053] For example, see Figure 4 , Figure 4 A schematic diagram of the second non-coaxial optical path structure of a terahertz micro-area scanning imaging method provided in one embodiment of the present invention; as shown. Figure 4As shown, this embodiment of the invention also proposes scanning imaging on a second non-coaxial optical path. The second non-coaxial optical path adds a third beam splitter 212 and a second terahertz detector 16 to the first non-coaxial optical path. Specifically, a third beam splitter 212, which is a terahertz beam splitter, is added to the terahertz incident optical path. After the incident terahertz wave 1 is reflected, refracted, and focused by the first axis-shifting parabolic mirror 12 and incident on the sample 14 under test, a transmitted terahertz wave 11 and a reflected terahertz wave 211 are generated. The transmitted terahertz wave 11 is refracted into a parallel wave by the second tilt-shift parabolic mirror 13 and enters the transmission THz detector 15, which is characterized as the first terahertz detector. The reflected terahertz wave 211 returns along the original incident light path, is reflected and refracted into a parallel terahertz wave by the first tilt-shift parabolic mirror 12, and is then split by the third beam splitter 212 before entering the reflection THz detector 16, which is characterized as the second terahertz detector, thus completing the single-point reflection intensity detection. The tilt-shift industrial vision kit consists of an industrial camera 26, a SAM connector 3, and a tilt-shift lens 4. The angle between the optical axis of the incident terahertz wave 1 after refraction and the optical axis of the tilt-shift lens 4 is an inclination angle θ. The tilt-shift industrial vision kit is used for real-time positioning, and the white light source 28 and the white light beam 29 are used for pre-photographing.

[0054] In this embodiment of the invention, a parallel-incident terahertz wave is reflected and refracted by a first axis-shifting parabolic mirror and focused onto the sample under test. The terahertz wave transmitted through the sample is reflected and refracted into a parallel terahertz wave by a second axis-shifting parabolic mirror and incident on a first terahertz detector to obtain a transmission intensity value. Simultaneously, the terahertz wave reflected by the sample returns along its original path, is reflected and refracted into a parallel terahertz wave by the first axis-shifting parabolic mirror, and is then split by a third beam splitter. One beam is incident on a second terahertz detector to obtain a reflection intensity value. The intensity value of the axisymmetric pixel corresponding to the real-time imaging of the axis-shifting lens is simultaneously correlated with the transmission and reflection signals of the current test point. Finally, the terahertz transmission intensity value and terahertz reflection intensity value acquired point by point are stitched together to obtain two area array images, or fused into a single multi-dimensional information image, serving as the terahertz scanning image of the target micro-area. Specifically, the incident terahertz wave 1 is reflected, refracted, and focused by the first axis-shifting parabolic mirror 12 and incident on the sample 14 to be tested, resulting in transmitted and reflected terahertz waves. The transmitted terahertz wave 11 is then reflected and refracted by the second axis-shifting parabolic mirror 13 into a parallel terahertz wave, which is incident on the transmission THz detector 15 to complete the single-point terahertz signal transmission intensity detection and obtain the terahertz transmission intensity value. At the same time, the reflected terahertz wave 211 is reflected and refracted by the first axis-shifting parabolic mirror 12 into a parallel terahertz wave, which is incident on the third beam splitter 212 and split and refracted into the reflection THz detector 16 to complete the single-point terahertz signal reflection intensity detection and obtain the terahertz reflection intensity value. The terahertz transmission intensity value and terahertz reflection intensity value are then measured by the transmission THz detector 15 and the reflection THz detector 16, respectively. A point-by-point intensity value stitching method is then used to construct a surface array image. Simultaneously, a displacement stage drives the sample under test to perform programmed equidistant displacement in the XZ plane, achieving terahertz transmission and reflection micro-area scanning imaging of the sample under test. This completes the transmission and reflection scanning imaging of the target micro-area of ​​the sample under test 14.

[0055] In the above scheme, the incident terahertz wave is focused onto the sample by a first axis-shifting parabolic mirror. The transmitted component then enters the first terahertz detector via a second axis-shifting parabolic mirror, while the reflected component is refracted by the first axis-shifting parabolic mirror and split by a third beam splitter before entering the second terahertz detector. The axis-shifting lens still provides the location of the axial pixel. Thus, by adding a third beam splitter and a second terahertz detector to the first non-coaxial optical path, both transmitted and reflected terahertz signals can be acquired simultaneously at the same scanning point, enriching the dimensions of imaging information and helping to improve the accuracy of the scanning imaging results.

[0056] Based on the above method embodiments, corresponding apparatus embodiments are provided; see [link to apparatus embodiments]. Figure 5 , Figure 5 A schematic diagram of the module structure of a terahertz micro-area scanning imaging system provided in one embodiment of the present invention. (See diagram below.) Figure 5As shown, this embodiment of the invention also provides a terahertz micro-area scanning imaging system, including a data acquisition module 201, a light wave type confirmation module 202, a first scanning imaging module 203, and a second scanning imaging module 204; wherein; the data acquisition module 201 is used to acquire a pre-shot image of the sample to be tested, determine the target micro-area on the pre-shot image, and determine the scanning start position; the light wave type confirmation module 202 is used to scan the target micro-area based on the scanning start position and acquire the current optical path type; the first scanning imaging module 203 is used to, if the current optical path is a coaxial optical path, then the incident light wave includes terahertz waves and visible light waves, and acquire the terahertz transmission intensity value and the visible light reflection intensity value, The location of the current test point is determined based on the visible light reflection intensity value, the pre-shot image, and the preset image matching algorithm. The target micro-area is identified based on the visible light reflection intensity value and the location of the current test point. A preset target scanning mode is activated, and the target micro-area is scanned and imaged based on the terahertz transmission intensity value to obtain a terahertz scan image of the target micro-area. The second scanning imaging module 204 is used to determine the location of the current test point based on the preset tilt-shift lens, the pre-shot image, and the preset image matching algorithm if the current optical path is a non-coaxial optical path, and the incident light wave only includes terahertz waves. The terahertz scan image of the target micro-area is generated based on the terahertz transmission intensity value or the terahertz reflection intensity value.

[0057] This invention proposes a terahertz micro-area scanning imaging system. It identifies the target micro-area on a pre-captured image of the sample under test and determines the scanning start position, eliminating the need for a pre-scanning step. During the target micro-area scanning process, different terahertz scanning imaging procedures are proposed based on different optical path types. Specifically, based on a coaxial optical path design, terahertz transmission intensity and visible light reflection intensity values ​​are acquired. A preset image matching algorithm is then used to perform real-time image feature matching analysis between the image generated from the visible light reflection intensity value and the pre-captured image to accurately locate the current test point, generating a terahertz scanning image of the target micro-area. Based on a non-coaxial optical path design, the optical axis of a tilt-shift lens, combined with a preset image matching algorithm and the pre-captured image, determines the location of the current test point, and a terahertz scanning image of the target micro-area is generated based on the terahertz transmission intensity or terahertz reflection intensity value. Therefore, an image matching algorithm is used in the coaxial optical path to identify the target micro-region in real time during the scanning process, and an optical axis combined with the image matching algorithm is used in the non-coaxial optical path to locate the starting point of the target micro-region scanning. Moreover, the scanning can be started directly without the need for a separate low-resolution pre-scanning process, thus improving the accuracy of the scanning imaging results.

[0058] It is understood that the above-described device embodiments correspond to the method embodiments of the present invention, and can implement the terahertz micro-area scanning imaging method provided by any of the above-described method embodiments of the present invention.

[0059] It should be noted that the device embodiments described above are merely illustrative, and some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can specifically be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0060] Based on the above-described embodiment of a terahertz micro-area scanning imaging method, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements a terahertz micro-area scanning imaging method according to any embodiment of the present invention.

[0061] For example, in this embodiment, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the terminal device.

[0062] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0063] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0064] Based on the above-described method embodiments, another embodiment of the present invention provides a computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to execute a terahertz micro-area scanning imaging method as described in any of the above-described method embodiments of the present invention.

[0065] The modules / units integrated in the device / terminal equipment, if implemented as software functional units and sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0066] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A terahertz micro-area scanning imaging method, characterized in that, include: Acquire a pre-shot image of the sample to be tested, determine the target micro-region on the pre-shot image, and determine the scanning start position; The target micro-region is scanned based on the scan start position, and the current optical path type is obtained; If the current optical path is a coaxial optical path, the incident light wave includes terahertz waves and visible light waves. By obtaining the terahertz transmission intensity value and the visible light reflection intensity value, the location of the current test point is determined based on the visible light reflection intensity value, the pre-shot image, and the preset image matching algorithm. The target micro-area is identified according to the visible light reflection intensity value and the location of the current test point. The preset target scanning mode is started, and the target micro-area is scanned and imaged according to the terahertz transmission intensity value to obtain the terahertz scanning image of the target micro-area. If the current optical path is a non-coaxial optical path, the incident light wave only includes terahertz waves. The location of the current test point is determined based on the preset tilt-shift lens, the pre-shot image, and the preset image matching algorithm. The terahertz scanning image of the target micro-area is generated according to the terahertz transmission intensity value or the terahertz reflection intensity value.

2. The terahertz micro-area scanning imaging method as described in claim 1, characterized in that, If the current optical path is a coaxial optical path, the incident light wave includes terahertz waves and visible light waves. By acquiring the terahertz transmission intensity value and the visible light reflection intensity value, the location of the current test point is determined based on the visible light reflection intensity value, the pre-shot image, and a preset image matching algorithm. The target micro-region is then identified based on the visible light reflection intensity value and the location of the current test point. A preset target scanning mode is activated, and the target micro-region is scanned and imaged based on the terahertz transmission intensity value to obtain a terahertz scan image of the target micro-region, including: The terahertz wave and visible light wave are combined into a coaxial mixed light wave during the scanning process of the target micro-area; The coaxial hybrid light wave is focused and incident on the sample to be tested, and the terahertz transmission intensity value and visible light reflection intensity value from the sample to be tested are detected respectively. A real-time scanned image is generated using the visible light reflectance value, and the real-time scanned image is matched with the pre-captured image using a preset image matching algorithm to obtain the location of the current test point. If the current test point is located within the coordinate range of the target micro-region, the preset target scanning mode is activated, and the target micro-region is scanned and imaged using terahertz transmission and visible light reflection based on the terahertz transmission intensity value, thereby obtaining the terahertz scan image of the target micro-region.

3. The terahertz micro-area scanning imaging method as described in claim 2, characterized in that, The coaxial optical path includes a first beam splitter, a second beam splitter, a first axis-shifting parabolic mirror, a second axis-shifting parabolic mirror, a first terahertz detector, and a photodetector; the step of focusing the coaxial mixed light wave onto the sample to be tested, and detecting the terahertz transmission intensity and visible light reflection intensity from the sample to be tested, includes: Based on the first beam splitter, parallel incident terahertz waves and parallel incident visible light waves are combined into parallel mixed light waves. Based on the first axis-shifting parabolic mirror, the parallel mixed light wave is reflected, refracted, and focused onto the sample to be tested; Based on the second axis-shifting parabolic mirror, the terahertz wave passing through the sample under test is reflected and refracted into a parallel terahertz wave, which is then incident on the first terahertz detector, and the terahertz transmission intensity value is detected by the first terahertz detector. Based on the first axis-shifting parabolic mirror, the visible light wave reflected from the sample and returning along the original incident light path is reflected and refracted into a parallel visible light wave, which is then split by the second beam splitter and incident on the photodetector. The photodetector detects the visible light reflection intensity value.

4. The terahertz micro-area scanning imaging method as described in claim 2, characterized in that, The step of generating a real-time scanned image based on the visible light reflectance intensity value, and matching the real-time scanned image with the pre-captured image based on a preset image matching algorithm to obtain the location of the current test point includes: Obtain the visible light reflectance intensity value point by point; The visible light reflectance intensity values ​​at each point are stitched together to form a visible light scan image, and the visible light scan image is used as the real-time scan image. Based on a preset image matching algorithm, the positional relationship between the current test point in the real-time scanned image and the target micro-region in the pre-captured image is analyzed in real time to obtain the location of the current test point.

5. The terahertz micro-area scanning imaging method as described in claim 1, characterized in that, If the current optical path is a non-coaxial optical path, the incident light wave only includes terahertz waves. The location of the current test point is determined based on a preset tilt-shift lens, the pre-captured image, and the preset image matching algorithm. A terahertz scanning image of the target micro-region is generated based on the terahertz transmission intensity value or the terahertz reflection intensity value, including: The sample under test is imaged in real time by a preset tilt-shift lens to obtain a real-time captured image. The optical axis of the incident terahertz wave is intersected with the optical axis of the tilt-shift lens at the current test point on the sample under test. The real-time captured image and the pre-captured image are matched and analyzed in real time by a preset image matching algorithm to determine the location of the current test point. The sample to be tested is moved so that the current test point is aligned with the coordinates of the starting position of the target micro-region during scanning, and then the target micro-region is scanned according to the preset target scanning mode. If the non-coaxial optical path is the first non-coaxial optical path, the terahertz transmission intensity value of the current test point is collected, and a terahertz scanning image of the target micro-region is generated. If the non-coaxial optical path is the second non-coaxial optical path, the terahertz transmission intensity value and terahertz reflection intensity value of the current test point are collected to generate a terahertz scanning image of the target micro-region.

6. The terahertz micro-area scanning imaging method as described in claim 5, characterized in that, The first non-coaxial optical path includes a first axis-shifting parabolic mirror, a second axis-shifting parabolic mirror, and a first terahertz detector; if the non-coaxial optical path is the first non-coaxial optical path, acquiring the terahertz transmission intensity value at the current test point and generating a terahertz scanning image of the target micro-region includes: Based on the first axis-shifting parabolic mirror, the parallel-incident terahertz wave is reflected, refracted, and focused onto the sample to be tested. Based on the second tilt-shift parabolic mirror, the terahertz wave transmitted through the sample under test is reflected and refracted into a parallel terahertz wave. The transmission intensity of the parallel terahertz wave incident on the first terahertz detector is detected, and the intensity value of the axis center pixel corresponding to the real-time imaging of the tilt-shift lens is corresponding to the terahertz transmission intensity value of the current test point. The terahertz transmission intensity values ​​are stitched together point by point to obtain a terahertz scanning image of the target micro-region using a planar array imaging technique.

7. The terahertz micro-area scanning imaging method as described in claim 5, characterized in that, The second non-coaxial optical path includes a first axis-shifting parabolic mirror, a second axis-shifting parabolic mirror, a third beam splitter, a first terahertz detector, and a second terahertz detector; if the non-coaxial optical path is the second non-coaxial optical path, acquiring the terahertz transmission intensity value and terahertz reflection intensity value at the current test point to generate a terahertz scanning image of the target micro-region includes: Based on the first axis-shifting parabolic mirror, the parallel-incident terahertz wave is reflected, refracted, and focused onto the sample to be tested. Based on the second tilt-shift parabolic mirror, the terahertz wave transmitted through the sample under test is reflected and refracted into a parallel terahertz wave. The transmission intensity of the parallel terahertz wave incident on the first terahertz detector is detected, and the intensity value of the axis center pixel corresponding to the real-time imaging of the tilt-shift lens is corresponding to the terahertz transmission intensity value of the current test point. Based on the first axis-shifting parabolic mirror, the parallel terahertz wave reflected by the sample under test is reflected and refracted by the third beam splitter and then incident on the second terahertz detector. The reflection intensity is detected by the second terahertz detector to obtain the terahertz reflection intensity value at the current test point. The terahertz transmission intensity value and the terahertz reflection intensity value of the current test point are stitched together point by point to obtain a planar array image as the terahertz scanning image of the target micro-region.

8. A terahertz micro-area scanning imaging system, characterized in that, It includes a data acquisition module, a light wave type confirmation module, a first scanning imaging module, and a second scanning imaging module; in; The data acquisition module is used to acquire a pre-shot image of the sample to be tested, determine the target micro-region on the pre-shot image, and determine the scanning start position; The light wave type confirmation module is used to scan the target micro-area based on the scanning start position and obtain the current optical path type; The first scanning imaging module is used to determine the location of the current test point based on the visible light reflection intensity value, the pre-shot image, and a preset image matching algorithm if the current optical path is a coaxial optical path and the incident light wave includes terahertz wave and visible light wave. It also identifies the target micro-area based on the visible light reflection intensity value and the location of the current test point, starts a preset target scanning mode, and scans and images the target micro-area based on the terahertz transmission intensity value to obtain a terahertz scanning image of the target micro-area. The second scanning imaging module is used to determine the location of the current test point based on a preset tilt-shift lens, the pre-shot image and the preset image matching algorithm if the current optical path is a non-coaxial optical path and the incident light wave only includes terahertz waves, and to generate a terahertz scanning image of the target micro-area according to the terahertz transmission intensity value or the terahertz reflection intensity value.

9. A terahertz micro-area scanning imaging terminal, characterized in that, The terminal includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements a terahertz micro-area scanning imaging method as described in any one of claims 1 to 7.

10. A terahertz micro-area scanning imaging storage medium, characterized in that, The storage medium includes a stored computer program, wherein, when the computer program is executed, it controls the device containing the storage medium to perform a terahertz micro-area scanning imaging method as described in any one of claims 1 to 7.

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