Signal measurement method for terahertz wave transmission system

Abstract

The invention relates to the technical field of terahertz detection, in particular to a signal measurement method for a terahertz wave transmission system. According to the technical scheme, the method comprises the following steps that a terahertz source is used for emitting terahertz waves, and after the terahertz waves are transmitted through one or more optical assemblies, stable transmission light beams are formed; an image of the transmission light beam is collected through a terahertz detector, and an original gray level image is obtained; and carrying out image processing on the original grayscale image, and extracting a light spot area. A complete two-dimensional light spot image is obtained at a time through the area array detector, an effective light spot area is automatically extracted in combination with an image processing algorithm, coordinate mapping is carried out, and efficient and stable measurement of terahertz wave energy distribution is achieved; by calculating light spot center energy and comparing energy changes under different optical assembly configurations, the transmission loss of the assembly can be quantitatively analyzed, and a reliable and quantifiable measurement means is provided for terahertz system debugging, assembly performance evaluation and multi-scene application.

Description

Technical Field

[0001] This invention relates to the field of terahertz detection technology, and in particular to a signal measurement method for terahertz wave transmission systems. Background Technology

[0002] Terahertz waves typically refer to electromagnetic waves with frequencies ranging from 0.1 to 10 THz, and they have significant application potential in fields such as imaging, non-destructive testing, materials analysis, high-speed communication, and security inspection. However, due to the low photon energy of terahertz waves, their susceptibility to absorption by water vapor during transmission in air, and their extreme sensitivity to the position and alignment of optical components, measuring their energy distribution and assessing system losses during transmission have always been technical challenges.

[0003] Currently, terahertz wave signal measurements mainly rely on single-point detectors or linear array scanning systems. Single-point detection methods achieve spatial sampling by moving the detector or mirror point by point. While relatively simple in structure, this method suffers from low measurement efficiency, long processing time, difficulty in obtaining complete two-dimensional spot energy distribution information, and instability in measurement results due to mechanical vibration or alignment errors. Linear array scanning, although improving sampling speed to some extent, still requires mechanical scanning, making true real-time area array imaging impossible, and the system complexity is high.

[0004] Images acquired by terahertz detectors often contain noise, background interference, and non-uniform responses, especially artifacts that easily appear at the edge of the light spot, affecting the accurate extraction of the spot area. Most existing measurement systems lack integrated image processing and energy analysis capabilities, typically relying on manual interpretation or simple grayscale statistics. This makes it difficult to automatically and quantitatively calculate the energy at the center of the light spot, and also hinders the rapid and accurate assessment of the insertion loss of various optical components (such as lenses, beam splitters, and mirrors) within the system. Therefore, this application proposes a signal measurement method for terahertz wave transmission systems. Summary of the Invention

[0005] The purpose of this invention is to address the problem that most existing terahertz wave signal measurements lack integrated image processing and energy analysis functions, and usually rely on manual interpretation or simple grayscale statistics, making it difficult to automatically and quantitatively calculate the energy at the center of the light spot. This invention proposes a signal measurement method for terahertz wave transmission systems.

[0006] The technical solution of the present invention: a signal measurement method for a terahertz wave transmission system, comprising the following steps:

[0007] S1. A terahertz wave is emitted using a terahertz source, and the terahertz wave is transmitted through one or more optical components to form a stable transmission beam;

[0008] S2. Acquire an image of the transmitted beam using a terahertz detector to obtain the original grayscale image;

[0009] S3. Perform image processing on the original grayscale image to extract the spot area;

[0010] S4. Based on the extracted spot area, determine the effective spot area and its grayscale distribution;

[0011] S5. Calculate the energy value of the predetermined center region in the effective light spot area, and use it as the center energy value;

[0012] S6. Calculate the transmission loss of the optical component based on the changes in the center energy value measured under different optical component configurations.

[0013] Optionally, in step S3, the image processing of the original grayscale image includes:

[0014] Threshold segmentation is performed on the original grayscale image to distinguish between the spot area and the background area, and to remove boundary artifacts.

[0015] Optionally, step S3 may also include:

[0016] The binary image obtained after threshold segmentation is subjected to noise removal, which includes removing connected regions with an area smaller than a preset threshold.

[0017] Optionally, in step S3, after noise removal, the light spot area is further smoothed, including Gaussian smoothing or morphological smoothing, to obtain a smooth light spot edge mask.

[0018] Optionally, step S4 includes:

[0019] Apply the spot region mask obtained in step S3 to the original grayscale image to obtain an effective grayscale image containing only the effective spot region;

[0020] Convert the pixel coordinates in the effective grayscale image into actual physical space coordinates.

[0021] Optionally, in step S5, calculating the energy value of the predetermined central region specifically involves:

[0022] Select a neighborhood region centered on the center point of the light spot;

[0023] The average gray value of all pixels within the neighborhood region is calculated and used as the center energy value.

[0024] Optionally, in step S6, calculating the transmission loss of the optical component specifically involves:

[0025] Before and after changing the type, position, or combination of optical components, the energy values ​​of the first center and the second center were measured respectively.

[0026] The energy loss caused by the optical component is determined based on the difference or ratio between the first center energy value and the second center energy value.

[0027] Compared with the prior art, this application includes at least one of the following beneficial technical effects:

[0028] By using a planar array detector to acquire two-dimensional spot images in one go, replacing the traditional single-point or linear array scanning, a rapid and complete measurement of the energy distribution of terahertz waves is achieved.

[0029] The effective area of ​​the light spot is automatically and accurately extracted by image processing algorithms, reducing measurement fluctuations caused by optical path alignment errors and background interference.

[0030] It can accurately calculate the energy at the center of the light spot and quantitatively analyze its insertion loss by changing the configuration of optical components, providing direct data support for system debugging and component evaluation.

[0031] The measurement process is standardized and easy to implement on different terahertz experimental platforms or systems, and is suitable for testing and optimization in various scenarios such as communication and imaging.

[0032] In summary, this invention acquires a complete two-dimensional spot image in one go using an area array detector, and automatically extracts the effective spot area and performs coordinate mapping using image processing algorithms, thus achieving efficient and stable measurement of terahertz wave energy distribution. By calculating the energy at the center of the spot and comparing the energy changes under different optical component configurations, the transmission loss of the components can be quantitatively analyzed, providing a reliable and quantifiable measurement method for terahertz system debugging, component performance evaluation, and multi-scenario applications. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a terahertz wave detection system.

[0034] Figure 2 This is a flowchart of the signal processing procedure.

[0035] Figure 3 This is a diagram showing the energy distribution of terahertz waves. Detailed Implementation

[0036] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0037] Example: Figure 1 As shown, the present invention proposes a signal measurement method for terahertz wave transmission systems. Its core lies in acquiring a two-dimensional grayscale image of the light beam using a planar array terahertz detector, and automatically and accurately extracting the beam spot features using image processing algorithms, thereby quantifying the central energy and system losses. See below for further details. Figure 1 The terahertz wave detection system shown (taking one optical path as an example) and Figure 2 The signal processing flow shown illustrates the implementation of this method.

[0038] In this embodiment, the terahertz wave detection system includes a terahertz source 1, a horn antenna 2, a terahertz plano-convex lens 3, an off-axis parabolic mirror 4, and a terahertz detector 5 arranged sequentially. The terahertz source 1 generates continuous or pulsed terahertz signals. The optical components are arranged according to a predetermined optical path for guiding and shaping the terahertz beam. The terahertz detector 5 is preferably a planar array terahertz imaging chip, which can directly output a two-dimensional grayscale image characterizing the intensity distribution of terahertz waves.

[0039] In this embodiment, the implementation process of a signal measurement method for a terahertz wave transmission system is as follows: Figure 2 As shown, the specific steps include:

[0040] Step 1: Terahertz Wave Generation and Transmission. Terahertz source 1 is activated to emit terahertz waves. The terahertz waves are first output through horn antenna 2, forming a highly directional beam. Subsequently, this beam is transmitted, collimated, or focused sequentially through one or more optical components (such as a terahertz plano-convex lens 3, an off-axis parabolic mirror 4, etc.). The positions of each component are adjusted so that the terahertz waves ultimately form a stable and clear spot on the imaging plane of terahertz detector 5.

[0041] Step 2: Image Acquisition. Terahertz detector 5 receives the terahertz wave signal arriving at its imaging plane and converts it into a digital grayscale image, i.e., the original grayscale image. This image reflects the two-dimensional energy distribution of the terahertz wave on the detector plane.

[0042] Step 3: Spot region extraction and image preprocessing. A series of processes are performed on the acquired raw grayscale image to accurately extract the spot region:

[0043] Gray-scale thresholding: The image is segmented using the gray-scale thresholding method. A threshold is set to distinguish between the spot area (higher gray level) and the background area (lower gray level), generating an initial binary mask image.

[0044] Boundary artifact removal: Identifies and removes false regions connected to the image boundary to prevent interference from image edges from being mistaken for part of the light spot.

[0045] Noise removal: Analyze the binary mask image and remove isolated connected regions with an area smaller than a preset pixel threshold. These are usually caused by detector noise or random interference.

[0046] Mask smoothing: The denoised binary mask is smoothed, for example by using Gaussian smoothing or morphological smoothing algorithms, to make the edges of the spot area smoother and more continuous, thereby improving the stability of subsequent steps.

[0047] Effective region extraction: Apply a smoothed binary mask to the original grayscale image to block out the background area and retain only the effective spot area covered by the mask, thus obtaining the "effective spot grayscale image".

[0048] Step 4: Coordinate Mapping and Physical Quantization. To correlate image information with actual physical dimensions, the system needs to perform coordinate mapping. Based on known parameters such as the detector's pixel size and the imaging system's magnification, a conversion relationship between pixel coordinates and actual physical space (usually in millimeters) is established. The pixel distances in the effective spot grayscale image obtained in Step 3 are converted into physical distances, thereby allowing for the quantification and calculation of physical parameters such as the spot's diameter and center position.

[0049] Step 5: Center Energy Calculation. Determine the center position of the beam in the effective beam grayscale image. Using this center point as the core, select a neighborhood region of a predetermined size (such as a rectangular or circular region). Calculate the average grayscale value of all pixels within this neighborhood and define this average value as the "center energy value" of this measurement. This value characterizes the energy intensity of the terahertz beam's central region.

[0050] Step Six: Transmission Loss Analysis. To evaluate the transmission loss of a specific optical component (such as a lens or mirror) or a section of optical path, comparative measurements can be performed.

[0051] First, under a reference optical path configuration (e.g., without inserting the component under test or using a reference component), perform steps one through five above to measure a center energy value E1.

[0052] Then, change the optical path configuration (e.g., insert the component under test, replace the component, or change the position of the component), keep other conditions unchanged, and repeat steps one through five to obtain another center energy value E2.

[0053] Finally, the energy change is calculated based on the two measured center energy values. Transmission loss can be expressed as the difference (E1 - E2) or a ratio (such as E2 / E1, or 10*log expressed in decibels). 10 The ratio (E2 / E1) is used for characterization. By systematically changing the combination or location of components, the contribution of each component to the total system loss can be analyzed.

[0054] like Figure 3 As shown, in this embodiment, the above method can automatically obtain the complete two-dimensional energy distribution of the terahertz beam from a single acquired image, accurately calculate the energy at the center of the beam spot, and quantitatively analyze the losses introduced by the optical components. This method significantly improves measurement efficiency, reduces human error, and enhances the stability and repeatability of measurement results, making it highly suitable for the debugging, performance calibration, and optimization of terahertz transmission systems.

[0055] This invention addresses the problems of low efficiency and poor stability in existing terahertz wave measurement methods. By using a planar array terahertz detector to acquire a complete two-dimensional spot image in a single operation, replacing traditional single-point or linear array scanning, rapid measurement is achieved. Simultaneously, image processing algorithms such as grayscale thresholding, noise removal, and smoothing are employed to automatically and accurately extract the effective area of ​​the spot, significantly reducing measurement fluctuations caused by optical path alignment errors and background interference, thereby improving the stability and repeatability of the measurement results. This invention also provides automated quantitative analysis capabilities, accurately calculating the energy value of the spot's central region. By mapping pixel coordinates to physical dimensions, the physical spatial quantification of spot characteristics is achieved. Furthermore, by systematically changing the configuration of optical components and comparing changes in the central energy value, the insertion loss of each optical component in the transmission system can be quantitatively calculated, providing direct data for component performance evaluation and system optimization. The method of this invention is easily integrated into different terahertz experimental platforms. It is not only applicable to the debugging and optimization of terahertz optical paths, but also provides an efficient, stable and quantifiable measurement tool for applications such as performance testing of optical components, evaluation of communication links and calibration of imaging systems, which helps to promote the standardization process of terahertz technology-related research and applications.

[0056] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A signal measurement method for a terahertz wave transmission system, characterized in that, Includes the following steps: S1. A terahertz wave is emitted using a terahertz source, and the terahertz wave is transmitted through one or more optical components to form a stable transmission beam; S2. Acquire an image of the transmitted beam using a terahertz detector to obtain the original grayscale image; S3. Perform image processing on the original grayscale image to extract the spot area; S4. Based on the extracted spot area, determine the effective spot area and its grayscale distribution; S5. Calculate the energy value of the predetermined center region in the effective light spot area, and use it as the center energy value; S6. Calculate the transmission loss of the optical component based on the changes in the center energy value measured under different optical component configurations.

2. The signal measurement method for a terahertz wave transmission system according to claim 1, characterized in that, In step S3, the image processing of the original grayscale image includes: Threshold segmentation is performed on the original grayscale image to distinguish between the spot area and the background area, and to remove boundary artifacts.

3. The signal measurement method for a terahertz wave transmission system according to claim 2, characterized in that, Step S3 also includes: The binary image obtained after threshold segmentation is subjected to noise removal, which includes removing connected regions with an area smaller than a preset threshold.

4. The signal measurement method for a terahertz wave transmission system according to claim 3, characterized in that, In step S3, after noise removal, the light spot area is further smoothed. The smoothing process includes Gaussian smoothing or morphological smoothing to obtain a smooth light spot edge mask.

5. A signal measurement method for a terahertz wave transmission system according to claim 1, characterized in that, Step S4 includes: Apply the spot region mask obtained in step S3 to the original grayscale image to obtain an effective grayscale image containing only the effective spot region; Convert the pixel coordinates in the effective grayscale image into actual physical space coordinates.

6. The signal measurement method for a terahertz wave transmission system according to claim 1, characterized in that, In step S5, calculating the energy value of the predetermined central region specifically involves: Select a neighborhood region centered on the center point of the light spot; The average gray value of all pixels within the neighborhood region is calculated and used as the center energy value.

7. The signal measurement method for a terahertz wave transmission system according to claim 1, characterized in that, In step S6, the calculation of the transmission loss of the optical components specifically involves: Before and after changing the type, position, or combination of optical components, the energy values ​​of the first center and the second center were measured respectively. The energy loss caused by the optical component is determined based on the difference or ratio between the first center energy value and the second center energy value.

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