CN110146898A - A probe trajectory monitoring and control method based on image capture and image analysis - Google Patents

Abstract

The invention relates to a probe trajectory monitoring and control method based on image capturing and image analysis, and belongs to the field of information technology. The method is implemented based on a probe ranging device, which includes a laser, a visible light source, a microscope, a probe, a sample, a sample displacement stage, a motion control system and an analysis and processing system. The method specifically includes: S1: placing the sample on the sample displacement stage; S2: irradiating visible light on the tip of the probe, acquiring a scene near the tip in real time through a microscope combined with a detector, and transmitting it to an analysis and processing system for image processing and features Extraction to obtain the distance S of the probe-sample on the image scale; S3: Calculate the actual distance d of the probe-sample through the relationship between the distance S on the image scale and the actual distance. In the invention, the distance between the probe and the sample is accurately obtained by capturing and analyzing the image, and the distance between the probe and the sample is adjusted by the control system, so as to finally realize the monitoring and control of the movement track of the probe.

Description

A probe trajectory monitoring and control method based on image capture and image analysis

technical field

The invention belongs to the field of information technology, and relates to a probe trajectory monitoring and control method based on image capturing and image analysis.

Background technique

According to the Rayleigh criterion, the traditional far-field imaging system is limited by the diffraction limit, and the highest spatial resolution of imaging can only reach about half of the wavelength. Using near-field scanning imaging technology, the imaging spatial resolution can break through the diffraction limit and can reach the subwavelength scale. Today, scanning near-field optical microscopy has been widely used in important fields such as functional device detection, biological tissue imaging, surface chemical analysis, material molecule detection, and nanodevice analysis. For scanning near-field optical microscopes, the probe is a core component. The monitoring and control of its position relative to the sample can not only ensure the imaging effect, but also avoid the probe or sample damage caused by the collision between the probe and the sample. . At present, although there are probe-sample force feedback mechanisms based on atomic force microscopy or feedback mechanisms based on tuning forks to detect the shear force between the probe and the sample, these methods are not suitable for scanning systems where the probe does not vibrate or the probe cannot Scanning system in contact with the sample; although the x,y position of the probe relative to the sample can be well monitored and controlled using a three-dimensional displacement stage, the distance (z position) of the probe to the sample surface cannot be monitored and controlled in real time and accurately , posing great difficulties for scanning imaging; thus, other methods of detecting and controlling probe motion need to be developed.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a probe trajectory monitoring and control method based on image capture and image analysis, which is used to accurately measure the distance (z direction) between the probe and the sample, combined with the probe automatically obtained by the scanning control system. For the x, y coordinates relative to the sample, the real-time monitoring and control of the probe movement trajectory (x, y, z position) can be realized through the image analysis system and the scanning control system.

To achieve the above object, the present invention provides the following technical solutions:

A probe trajectory monitoring and control method based on image capture and image analysis, which specifically includes the following steps:

S1: place the sample (7) on the sample stage (8);

S2: Turn on the visible light source (4) to illuminate the probe (5) and the sample (7);

S3: turn on the laser (6) and irradiate the laser to the end of the probe (5) and the surface of the sample (7);

S4: acquiring a scene image near the end of the probe (5) in real time by combining the microscope (3) with the detector (2);

S5: transmit the image to the analysis and processing system (1) for image processing and feature extraction to obtain the distance S between the probe and the sample on the image scale;

S6: Calculate the actual distance d between the probe and the sample through the relationship between the distance S on the image scale and the actual distance, and set it as the position of the probe relative to the sample in the z direction;

S7: control the movement of the sample stage (8) or the probe (5) through the motion control system (9) to obtain the position parameters a and b of the probe relative to the sample in the x and y directions;

S8: Through the analysis and processing system (1) and the motion control system (9), monitoring and control of the motion trajectory of the probe are realized according to obtaining a, b, d or adjusting a, b, d.

Further, in the step S3, a laser beam is used to irradiate the end of the probe and the surface of the sample, a part of the laser spot is irradiated on the end of the probe, and a part of the laser spot is irradiated on the surface of the sample below the probe. Using this method, the tip of the probe and the sample surface below the probe are brighter than the surrounding environment, which facilitates the analysis of the probe-to-sample surface distance from the captured images.

Further, in the step S5, the image processing includes: performing pseudo-color processing, threshold binarization, erosion and expansion on all the captured images.

Further, in the step S5, the feature extraction includes: extracting the edge of the image and calculating the boundary distance of the edge area.

Further, the step S6 specifically includes: when the motion control system (9) is used to accurately control the displacement L of the three-dimensional sample stage (8) along the z direction, the distance change ΔS between the photoconductive probe and the sample on the image is measured; the known probe - The relationship between the actual distance d of the sample and the distance S measured on the image is d=S sinα, where α is the horizontal angle between the microscope (3) and the sample stage (8), 0<α<360°;

(1) For a sample with a smooth surface, the image and the actual scale k ₁ =ΔS·sinα/L, the actual distance d=k ₁ ·S between the probe and the sample is calculated;

(2) For the sample with rough surface, the image and the actual scale k ₂ =ΔS/L, the actual distance d = k ₂ ·S between the probe and the sample is calculated.

Further, a device suitable for the probe trajectory monitoring and control method includes a laser (6), a visible light source (4), a microscope (3), a detector (2), a probe (5), and a sample displacement stage (8) , a motion control system (9) and an analysis and processing system (1);

The laser (6) is used for radiating detection laser light; the sample displacement stage (8) is placed horizontally for holding the sample (7) and controls the movement of the sample in all directions; the motion control system (9) It is used to accurately control the movement of the sample stage (8) or the probe (5) in the x, y, and z directions, or to respectively control the movement of the probe or the sample stage in a certain or certain spatial orientations.

The beneficial effects of the present invention are: in the process of sample scanning, the present invention can obtain and adjust the distance between the probe and the sample in real time, can accurately measure the distance between the probe and the sample, and can automatically adjust the distance through the motion control system; The x, y position of the probe relative to the sample known by the motion control system can be monitored and controlled by the analysis processing system and the motion control system.

Description of drawings

In order to make the purpose, technical solutions and beneficial effects of the present invention clearer, the present invention provides the following drawings for description:

1 is a schematic diagram of a probe ranging device;

Figure 2 is a schematic diagram of the ranging principle of a smooth surface sample;

Figure 3 is a schematic diagram of the ranging principle of rough surface samples;

Reference numerals are: 1-Analytical Processing System, 2-Detector, 3-Microscope, 4-Visible Light Source, 5-Probe, 6-Laser, 7-Sample, 8-Sample Stage, 9-Motion Control System, 10 - Sample with smooth surface, 11 - Sample with rough surface, 12 - Mirror image of probe.

Detailed ways

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. This preferred example is a terahertz near-field imaging system based on photoconductive microprobes in a sample scanning mode.

As shown in FIGS. 1 to 3 , a probe trajectory monitoring and control method based on image capturing and image analysis according to the present invention, the implementation device includes a laser 6, a visible light source 4, a visible light microscope 3, and a probe 5 (this embodiment The example uses a photoconductive micro), a sample 7, a sample displacement stage 8, a motion control system 9 and an analysis and processing system 1 (a computer is used in this embodiment). The laser is used to radiate the detection laser; the sample stage is placed horizontally to hold the sample and control the movement of the sample in all directions; the motion control system can accurately control the movement step of the sample stage in the Z direction;

The microscope in this embodiment adopts a visible light microscope, which is placed at an angle of α (0<α<90°) with the horizontal direction of the sample stage. The microscope is equipped with a color CCD camera, which works in RGB mode and sends real-time images to the analysis and processing system. .

In the sample test experiment, the detection laser radiated by the laser is irradiated near the needle tip, and the scene near the needle tip is acquired by the CCD camera, and then the acquired image is processed by the analysis and processing system (pseudo-color processing, threshold binarization, corrosion and expansion, etc.) and feature extraction (image edge extraction and calculation of the shortest distance of the boundary area), etc., the distance S between the photoconductive microprobe and the sample on the image scale can be obtained, and there is a certain conversion relationship between the image distance and the actual distance. , that is, through the scale bar between them, the actual distance d between the photoconductive microprobe and the sample can be obtained indirectly.

First, the distance change ΔS between the photoconductive probe and the sample on the image is measured when the sample stage is accurately controlled to move L along the Z direction by the motion control system;

(1) For a sample with a smooth surface, the probe will generate a mirror image through the surface of the sample, and the laser irradiates the needle tip, and the laser spot can also be observed on the mirror image; therefore, the laser spot can be observed on the image collected by the CCD at the same time. On the needle tip and on the mirror image; according to the principle of optical imaging, the relationship between the actual distance d between the photoconductive microprobe and the sample and the distance S measured on the image is d=S·sinα, so as to determine the scale between the image and the actual scale k ₁ =ΔS·sinα /L, the actual distance d=k ₁ ·S between the photoconductive microprobe and the sample is obtained.

(2) For samples with rough surfaces, mirror images cannot be formed, but since the diameter of the probe laser beam used by the terahertz near-field imaging system is about 30 μm, about 10 μm of which is irradiated on the photoconductive microprobe, when the sample is near the tip of 10 μm When , the laser light that is not irradiated on the photoconductive microprobe will irradiate the sample and be diffusely reflected in other directions, so that it will be detected by the CCD on the optical microscope. Therefore, laser spots are observed on the needle tip and the sample in the collected image, so the image and the actual scale k ₂ =ΔS/L are determined, and the actual distance d=k ₂ ·S between the photoconductive microprobe and the sample is obtained.

(1) Measuring the distance between the photoconductive microprobe and the sample

Step 1: Image acquisition and processing

After adjusting the equipment, run the terahertz near-field scanning system, and control the motion control system to move the sample toward the end of the photoconductive microprobe (z direction) (all sample movement operations in this system must be performed so that the sample does not touch the probe. principle), after seeing the mirror image of the needle tip or the laser spot on the sample on the image fed back by the CCD, select micron-level stepping to move a small amount, and then collect the color image transmitted by the CCD on the analysis and processing system, and make an image of the collected image. The distance S ₁ between the probe and the sample on the image is obtained by processing and feature extraction.

Step 2: Measure the image and the actual scale k

Control the motion control system to move the sample to the determined displacement L, collect images and perform image processing and feature extraction to obtain the distance S ₂ , and calculate the change of the distance between the two images △S=|S ₂ -S ₁ |; according to whether the original image produces a mirror image , calculate the image and the actual scale k; for a sample with a smooth surface, due to the effect of specular reflection, laser spots are observed on the needle tip and mirror image in the collected image, so the scale k ₁ =ΔS·sinα/L ; For the sample with rough surface, due to the effect of diffuse reflection of the sample, laser spots are observed on the needle tip and the sample in the collected image, so the scale bar k ₂ =ΔS/L.

Step 3: Ranging and positioning

During the near-field test of the sample, the electric control box is controlled to move the sample to the test position, and then the image is collected, image processing and feature extraction are performed to obtain the distance S between the photoconductive microprobe and the sample on the image; The actual probe-sample spacing is d=k·S.

Example 2: Automatic adjustment of the distance between the measurement photoconductive microprobe and the sample

Step 1: Image acquisition and scale determination

Same as steps 1 and 2 in Example 1, measure the scale bar k (wherein, for a sample with a smooth surface, the image and actual scale are k ₁ , and for a sample with a rough surface, the image and actual scale are k ₂ ).

Step 2: Automatically adjust the spacing system

The safety value d ₀ of the probe-sample distance is preset. During the sample scanning test, the distance S on the image is extracted in real time by the analysis and processing system, the actual distance d is calculated according to the corresponding scale, and the size relationship between d and d ₀ is compared. It is transmitted to the system control center, and the movement of the sample in the Z direction is adjusted through the communication between the control center and the sample stage. Therefore, in the terahertz near-field scanning test process, through the real-time feedback adjustment between the analysis processing system and the sample stage, the distance between the probe and the sample can be kept within a fixed range, so as to achieve the purpose of safe and automatic scanning of the sample.

Step 3: Probe Movement Track Monitoring and Control

During the operation, the x and y positions of the probe relative to the sample can be known through the motion control system of the stage; in addition, the z position of the probe relative to the sample surface can be obtained from steps 1 and 2. Therefore, during the scanning and imaging process of the probe, the x, y, and z positions of the probe relative to the surface of the sample can be obtained, so that the motion trajectory of the probe can be monitored by the image analysis and processing system; accordingly, the motion of the stage can be controlled by The system sets parameters to control the movement track of the probe.

Preferably, the motion control of the scanning can be realized by controlling the sample stage separately, or by controlling the probe module separately, or it can be realized by controlling the sample stage and the probe module at the same time; illumination light and microscope are not necessary, and in In the case of ensuring that the image of the probe tip and the surface of the sample can be captured, one or all of the above components are not necessarily required; the laser can be replaced by other light beams with a certain brightness, as long as it can assist in displaying the probe tip and the probe in the image. The position of the sample surface under the needle; there are various image capturing devices, all of which belong to the scope of the present invention; the method of image processing is not limited to the steps mentioned in the present invention, as long as the image analysis and processing of the distance between the probe tip and the sample surface can be extracted All methods belong to the scope of the present invention.

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should Various changes may be made in details without departing from the scope of the invention as defined by the claims.

Claims (6)

1. a kind of based on image taking and the monitoring of the probe trajectory of image analysis and control method, which is characterized in that this method tool Body the following steps are included:

S1: sample (7) is placed on sample displacement platform (8)；

S2: visible light source (4) illuminator probe (5) and sample (7) are opened；

S3: laser (6) are opened by laser irradiation to probe (5) end and sample (7) surface；

S4: detector (2) are combined to obtain the scene image near probe (5) end in real time by microscope (3)；

S5: image transmitting to analysis process system (1) is subjected to image procossing and feature extraction, obtains probe-sample in image Interval S on scale；

S6: by the relational expression of interval S and practical spacing on graphical rule, being calculated the actual range d of probe-sample, And it is set to position of the probe relative to sample on the direction z；

S7: being moved by kinetic control system (9) control sample displacement platform (8) or probe (5), is obtained probe and is existed relative to sample The location parameter a and b in the direction x and y；

S8: it by analysis process system (1) and kinetic control system (9), realizes to spy according to obtaining a, b, d or adjust a, b, d The monitoring and control of needle movement track.

2. it is according to claim 1 it is a kind of based on image taking and the probe trajectory of image analysis monitoring and control method, It is characterized in that, irradiating probe end in step S3 using beam of laser and sample surfaces, laser spot a part being radiated at probe End, a part are radiated at sample surfaces below probe.

3. it is according to claim 1 it is a kind of based on image taking and the probe trajectory of image analysis monitoring and control method, It is characterized in that, in the step S5, image procossing include: to all shooting images carry out Pseudo Col ored Image, threshold binarization, Corrosion and expansion.

4. it is according to claim 1 it is a kind of based on image taking and the probe trajectory of image analysis monitoring and control method, It is characterized in that, feature extraction includes: the frontier distance for extracting image border and calculating fringe region in the step S5.

5. it is according to claim 1 it is a kind of based on image taking and the probe trajectory of image analysis monitoring and control method, It is characterized in that, the step S6 is specifically included: accurately controlling three-dimensional sample platform (8) in the z-direction by kinetic control system (9) When being displaced L, photoconductive probe-sample spacing changes delta S on the image is measured；The practical spacing d of known probe-sample and image On to measure the relationship of interval S be d=Ssin α, wherein α is microscope (3) and sample displacement platform (8) horizontal direction angle, 0 < 360 ° of α <；

(1) for the sample of smooth surface, image and actual scale bar k₁=Δ Ssin α/L, is calculated probe-sample Practical spacing d=k₁·S；

(2) for the sample of rough surface, image and actual scale bar k₂=Δ S/L, is calculated the reality of probe-sample Spacing d=k₂·S。

6. it is according to claim 1 it is a kind of based on image taking and the probe trajectory of image analysis monitoring and control method, It is characterized in that, the device for being suitable for probe trajectory monitoring and control method includes laser (6), visible light source (4), shows Micro mirror (3), detector (2), probe (5), sample displacement platform (8), kinetic control system (9) and analysis process system (1)；

The laser (6) is for giving off exploring laser light；The sample displacement platform (8) is horizontal positioned, for holding sample (7), and sample is controlled in the movement of all directions；The kinetic control system (9) for accurately control sample displacement platform (8) or Probe (5) is in x, y, the movement in the direction z, or for controlling probe or sample displacement platform respectively in a certain or certain dimensional orientations Movement.