Image feature point display method during terahertz near-field system imaging

Abstract

The invention discloses a method for displaying image feature points during imaging of a terahertz near-field system, belongs to the field of terahertz near-field imaging, and mainly solves the problem that the feature points are not clearly displayed due to an overlarge image contrast value during imaging of the terahertz near-field system. The method comprises the following three steps: determining the position of an image feature point through primary scanning, determining the parameter size of the image feature point through secondary scanning, and finally scanning and adjusting the display parameter of the image feature point to enable the image feature point to be displayed clearly. The method has the characteristics of simple operation and clear image feature points.

Description

Technical Field

[0001] The invention belongs to the field of terahertz near-field imaging, and in particular relates to a method for displaying image feature points during terahertz near-field system imaging. Background Art

[0002] The terahertz near-field imaging system is based on the atomic force microscope system, which consists of a terahertz source, a terahertz optical path, a parabolic mirror, a probe platform, etc. The terahertz wave is emitted by the terahertz source, passes through the terahertz optical path, reaches the parabolic mirror and is focused on the probe platform in the atomic force microscope. The probe is above the sample, and the terahertz wave reflected by the probe carries the near-field information of the sample and returns to the terahertz optical path through the parabolic mirror and reaches the signal processing system of the atomic force microscope, realizing the high-resolution imaging function of the terahertz near field. Its imaging accuracy is generally nanometer-level, with an accuracy of tens of nanometers or even a few nanometers.

[0003] The imaging method of the terahertz near-field system is similar to that of the atomic force microscope. It uses a point-by-point scanning method, and a new line of scanning is performed after a line of scanning is completed. The terahertz image is composed of the amplitude value of the terahertz signal received at each point. When scanning the sample, due to the uneven thickness of the sample and the different penetration of the terahertz signal, the amplitude of the received terahertz signal varies greatly, resulting in a large amount of imaging information and unclear display of feature points. If the entire content of the imaging cannot be clearly displayed in one picture at the same time, it is often clear in one part, and the rest of the part is unclear or even blank. It is difficult to image and display the information features that are really needed in the image, let alone a clear display. Frequent multiple operations of invalid imaging, unsatisfactory image feature display results, time-consuming and labor-intensive, are not conducive to the use and promotion of the terahertz near-field system. It is necessary to adjust the specific process to make the image feature points clearly displayed. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for displaying image feature points during imaging of a terahertz near-field system. By using the position and signal value of the image feature point, the position of the feature point is determined by the initial scanning imaging, and the signal value of the feature point is determined by the scanning imaging again. Finally, the position of the image feature point in the oscilloscope is adjusted by scanning imaging to ensure that the upper and lower positions are centered and the amplitude is moderate, so that the feature point is clear and distinct in the entire image during imaging display, and the effective information of the feature point can be observed. The feature points can be displayed quickly and effectively, avoiding multiple invalid, time-consuming and laborious operations.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows: a method for displaying image feature points during imaging of a terahertz near-field system, using a multiple scanning method, comprising: The position of the feature point is determined in the initial imaging, and the position of the feature point is adjusted after the initial imaging so that the feature point is located in the middle of the upper, lower, left, and right sides of the image, so as to facilitate the adjustment of the feature point signal in the next imaging; The signal value of the feature point is determined by the secondary imaging, and the clarity of the image of the feature point is compared to facilitate adjustment during the tertiary imaging; The three imagings adjust the display parameters of the image feature points. The magnification represents the contrast, the upper and lower positions represent the color depth, the feature point signal curve position is centered in the upper and lower average values ​​in the oscilloscope display, and the highest and lowest value ranges occupy half in the oscilloscope display. The final imaging shows a clear picture of the image feature points.

[0006] The beneficial effects of the present invention are: The present invention has the characteristics of simple operation, rapid imaging, and clear image feature points, thus avoiding multiple invalid, time-consuming, and laborious operations with unclear image feature points. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic diagram of the characteristic positions of terahertz imaging; Figure 2 is a schematic diagram of the movement of the characteristic position of terahertz imaging; Figure 3 is a schematic diagram of terahertz imaging signal values; Figure 4 It is a schematic diagram of the amplification of the terahertz imaging signal value; Figure 5 It is a schematic diagram of the movement of the amplified position of the terahertz imaging signal value. DETAILED DESCRIPTION

[0008] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0009] The present invention provides a method for displaying image feature points during imaging of a terahertz near-field system, which adopts a multiple scanning method to adjust the positions of image feature points, signal values ​​of image feature points, and display parameters of image features, etc. The method mainly solves the problem of unclear display of feature points due to excessive image contrast value during imaging of a terahertz near-field system.

[0010] This is done in three steps. The first imaging determines the position of the feature point, and the position is adjusted to ensure that the image feature point is in the center of the image when the image is imaged again. The image feature point is in the center of the picture for the second imaging, and the signal value of the feature point is determined. The position of the image feature point displayed on the oscilloscope is adjusted for the third imaging, and the offset value and magnification are adjusted in the oscilloscope. The upper and lower positions are the depth of the color, and the magnification of the position is the contrast. Adjust the display parameters of the image feature point so that the upper and lower average values ​​of the feature point in the oscilloscope are centered, and the highest and lowest values ​​of the curve are half of the oscilloscope, so that the image feature points are clearly displayed, and the final imaging shows a picture with clear image feature points. Details are as follows: Initial imaging. The terahertz near-field system is used to scan and image the image, mainly to determine the position of the feature point in the imaging, so that the feature point position is in the middle of the image, so as to facilitate the feature point signal adjustment in the next imaging. Figure 1 As shown in the figure, there are three obvious features after the first imaging, namely, feature 1 circle, feature 2 square, and feature 3 triangle. Feature 1 circle is located in the middle and upper left of the image, feature 2 square is located in the upper right of the image, and feature 3 triangle is located in the lower left of the image. After the first imaging, the position of the feature points is adjusted so that the feature 1 circle is in the middle position to ensure that the feature 1 circle is in the middle of the image during the second imaging. The sample to be imaged is moved as a whole, and the position is moved in two directions, such as Figure 2 As shown by the dotted arrow in the middle, it moves downward and then to the right. Figure 2 In the figure, the solid line position of feature 1 is the position before the movement, the dotted line position is the position after the movement. It can be seen that after the movement, the dotted line part of the circle of feature 1 is located in the middle of the upper, lower, left and right sides of the imaging image.

[0011] Secondary imaging. During secondary imaging, the feature points of the image have been adjusted after the initial imaging and are located at the center of the image. Here, the signal value at the feature point is mainly determined and adjusted. Due to terahertz near-field imaging, a point-by-point scanning method is adopted, and the amplitude of the signal values ​​at different scanning points in the same line is used to accumulate the amplitude of multiple lines of curves to form an image. The imaging signal value is small, and after demodulation by the phase-locked amplifier and amplification by the voltage amplifier in the terahertz near-field system, an output of 10mv is obtained. In the same line scan, the signal value of each point is different, forming the following Figure 3 The curve shown. During the second imaging scan, observe the signal value of the point when the feature is scanned. Determine the signal value of the feature point and compare the clarity of the image of the feature point to facilitate adjustment during the third imaging.

[0012] Three-stage imaging. According to the signal value of the feature point determined by the second scan, the parameters are set in combination with the clarity of the feature point image. If the feature point image is not clear and the contrast with the surrounding is not high, the magnification of the signal curve is adjusted, and the magnification of the signal value curve of the same scanning point is increased, such as Figure 4 As shown in Figure 3 The overall magnification is increased based on the curve. Otherwise, the signal curve magnification is reduced. If the color of the feature point image is too bright or too dark, the position of the signal curve is adjusted up or down. Figure 5 As shown, the signal curve moves as a whole, with the center line as the mark. If the center line moves downward, the signal curve moves upward as a whole. Generally speaking, if the signal curve moves upward, the image becomes lighter, and if it moves downward, the image becomes darker. It can also be said that the magnification of the signal curve position is the contrast, and the position up and down is the depth of the color. Adjust the display parameters of the image feature points so that the feature point signal curve is centered in the upper and lower average values ​​of the oscilloscope display, and the highest and lowest values ​​are half of the oscilloscope, so that the image feature points are displayed clearly, and the final imaging shows a picture with clear image feature points. If necessary, if the feature points of the image are not clear after three imaging, the parameters can be corrected for four scans.

[0013] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for displaying image feature points during imaging of a terahertz near-field system, characterized in that: Multiple scans are performed, including: The position of the feature point is determined in the initial imaging, and the position of the feature point is adjusted after the initial imaging so that the feature point is located in the middle of the upper, lower, left, and right sides of the image, so as to facilitate the adjustment of the feature point signal in the next imaging; The signal value of the feature point is determined by the secondary imaging, and the clarity of the image of the feature point is compared to facilitate adjustment during the tertiary imaging; The three imagings adjust the display parameters of the image feature points. The magnification represents the contrast, the upper and lower positions represent the color depth, the feature point signal curve position is centered in the upper and lower average values ​​in the oscilloscope display, and the highest and lowest value ranges occupy half in the oscilloscope display. The final imaging shows a clear picture of the image feature points.

2. The method for displaying image feature points during imaging by a terahertz near-field system according to claim 1, characterized in that: The initial imaging is specifically as follows: determining the characteristic points in the sample to be imaged, selecting one or more characteristic points, moving the image as a whole, and moving the position in one or more directions so that the selected characteristic points are located in the middle of the image. The movement directions include up, down, left, and right.

3. The method for displaying image feature points during imaging of a terahertz near-field system according to claim 1, characterized in that: The determination of the signal value at the position of the feature point during the secondary imaging specifically includes: adopting a point-by-point scanning method, using the amplitude of the signal value of different scanning points in the same line, and accumulating the amplitude of multiple lines of curves to form an image, and then demodulating it through a phase-locked amplifier in the terahertz near-field system and amplifying it through a voltage amplifier to obtain an output image at 10mv. In the same line of scanning, the curve has different signal values ​​at each point. During the secondary imaging scan, the signal value of this point when scanning the feature point is observed to determine the signal value of the feature point, and the clarity of the imaging image of the feature point is compared to facilitate adjustments during the tertiary imaging.

4. The method for displaying image feature points during imaging by a terahertz near-field system according to claim 1, characterized in that: The three-stage imaging adjusts the display parameters of the image feature points as follows: the parameters are set according to the signal values ​​of the feature points determined by the secondary scan and the clarity of the feature point image. If the feature point image is not clear and the contrast with the surrounding is not high, the magnification of the signal curve is adjusted, and the magnification of the signal value curve of the same scanning point is increased. On the basis of the curve, the overall magnification is increased. Otherwise, the signal curve magnification is reduced. If the color of the feature point image is too bright or too dark, the position of the signal curve is adjusted up and down. The signal curve moves as a whole, with the center line as the mark. If the center line moves downward, the signal curve moves upward as a whole.

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