Method and system for performing imaging correction on particles in transparent hollow tube

Abstract

The invention discloses a method and system for carrying out imaging correction on particles in a transparent hollow tube, and the method comprises the steps: S1, carrying out the preprocessing of a scattered light image of the particles in the transparent hollow tube, and obtaining a denoised airspace image; s2, constructing a correction transmission matrix; and S3, obtaining a corrected image according to the de-noised spatial domain image and the corrected transmission matrix. By adopting the technical scheme of the invention, the correction of the scattering image of the suspended particles in the hollow tube is realized.

Description

Technical Field

[0001] This invention belongs to the field of optical imaging technology, and in particular relates to a method and system for imaging correction of microparticles inside a transparent hollow tube. Background Technology

[0002] Scattered light detection, as a non-invasive and highly sensitive method for particle characterization, can invert the physical properties of particles by analyzing the interaction between the light field and the particles. Specifically, by detecting the scattered light of particles, key parameters such as particle size, refractive index, and mass can be obtained, thereby enabling the measurement and characterization of important particle properties. Traditional open-environment particle scattering light detection technology is relatively mature, and particle characteristics can be inverted by directly acquiring the scattered light field. However, when acquiring scattered light images of particles inside a transparent hollow tube, the refraction and reflection effects of the hollow tube sidewalls introduce changes in the light transmission direction, resulting in distortion of the acquired particle scattering images. Therefore, to achieve high-precision characterization of particles inside transparent hollow tubes, particle scattering images need to be corrected. Existing methods mainly use the transfer matrix method to correct the transmission of the light field in complex structures; however, accurately measuring the transfer matrix of the transmission medium often requires a large number of complex measurements and has high requirements for the measurement environment and calculation accuracy. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method and system for imaging correction of microparticles inside a transparent hollow tube. By simulating the hollow tube structure and the transmission process of scattered light from microparticles within it, the calculation method of the transmission matrix is ​​optimized and improved, and a filtering algorithm is combined to remove noise introduced by the hollow tube structure, thereby realizing the correction of the scattered image of suspended microparticles inside the hollow tube.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for imaging correction of microparticles inside a transparent hollow tube includes:

[0006] Step S1: Preprocess the image of scattered light from particles inside the transparent hollow tube to obtain a denoised spatial image;

[0007] Step S2: Construct the corrected transfer matrix;

[0008] Step S3: Obtain the corrected image based on the denoised spatial image and the corrected transfer matrix.

[0009] Preferably, in step S1, the image of scattered light from particles inside the transparent hollow tube is preprocessed using frequency domain filtering technology.

[0010] As a preferred option, the modified transmission matrix T m For: T m =BA -1Where A and B are the matrix forms of the input and output fields when light passes through the sidewall of the transparent hollow tube.

[0011] Preferably, in step S3, a transparent hollow tube structure model is constructed using finite element software, and the transmission characteristics of the scattered light field are solved by ray tracing; the input field distribution A is set, the output field B is obtained through simulation, and the corrected transmission matrix T is calculated. m The denoised image obtained in step S1 is considered as B', and... The corrected image A' can then be obtained.

[0012] The present invention also provides a system for imaging correction of microparticles inside a transparent hollow tube, comprising:

[0013] The first processing module is used to preprocess the image of scattered light from particles inside the transparent hollow tube to obtain a denoised spatial image.

[0014] The second processing module is used to construct the corrected transmission matrix;

[0015] The third processing module is used to obtain the corrected image based on the denoised spatial domain image and the corrected transfer matrix.

[0016] Preferably, the first processing module preprocesses the image of scattered light from particles inside the transparent hollow tube using frequency domain filtering technology.

[0017] As a preferred option, the modified transmission matrix T m For: T m =BA -1 Where A and B are the matrix forms of the input and output fields when light passes through the sidewall of the transparent hollow tube.

[0018] As a preferred option, the third processing module uses finite element software to construct a transparent hollow tube structure model, and employs ray tracing to solve for the transmission characteristics of the scattered light field; it sets the input field distribution A, simulates the output field B, and calculates the corrected transmission matrix T. m The denoised image obtained in step S1 is considered as B', and... The corrected image A' can then be obtained.

[0019] This invention removes noise introduced by the transparent hollow tube structure and stray light through filtering techniques. A simplified method is used to obtain the corrected transfer matrix, enabling the inversion and correction of the image of scattered light from particles inside the transparent hollow tube. This improves the correlation coefficient between the corrected image and the reference image outside the tube to >0.8. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0021] Figure 1 This is a flowchart of a method for imaging correction of microparticles inside a transparent hollow tube according to an embodiment of the present invention;

[0022] Figure 2 The images show scattered images of polystyrene microspheres with a particle size of 6 μm; where (a) is the reference image of the end face; and (b) is an image of suspended particles inside the fiber core.

[0023] Figure 3 To correct the before and after scattered light images;

[0024] Figure 4 Correlation coefficients of scattering images before and after correction for polystyrene microspheres of different particle sizes. Detailed Implementation

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1:

[0028] like Figure 1 As shown, this embodiment of the invention provides a method for imaging correction of microparticles inside a transparent hollow tube, comprising:

[0029] Step S1: Preprocess the image of scattered light from particles inside the transparent hollow tube using frequency domain filtering technology to remove noise introduced by the transparent hollow tube structure and stray light.

[0030] The processing flow is as follows:

[0031] Perform a two-dimensional fast Fourier transform on the original image to convert it to the frequency domain, and then shift the zero frequency point to the center of the frequency spectrum by spectral shift.

[0032] A low-pass filter is applied to the centered spectrum to suppress high-frequency noise components and preserve low-frequency information of the main image subject.

[0033] The filtered spectrum is inversely shifted to restore the original frequency distribution, followed by a two-dimensional inverse fast Fourier transform. The real part of the transform result is then taken to obtain the denoised spatial domain image.

[0034] Step S2: Construct the modified transfer matrix

[0035] When light passes through any transmission medium, the relationship between its input field and output field can be expressed as follows:

[0036] b = Ta (1)

[0037] Where, T∈C N×N The incident field a∈C is described N How is it converted to b∈C after passing through the transmission medium? N Here, a and b are vectorized forms of the two-dimensional input field. When measuring an unknown transmission matrix T, a series of orthogonal 'a's are typically input, and the 'b' obtained by each input field through the medium is recorded. This requires m independent measurements to complete a complete and accurate calculation of T, where m should be greater than the dimension N of the input vector. Analysis of the transparent hollow tube structure reveals that the medium through which the scattered light from the particles inside the tube passes during transmission should be uniformly distributed along the axis of the hollow tube. Ideally, for each column of the input field, since the structure of the medium through which it passes is exactly the same, any column b of the output field... n Its corresponding input a n The transformation relationship between them can be characterized by the same transfer matrix T, a n 、b n This represents the nth column of the input or output matrix. The transformation relationship between the input and output fields can then be simplified to B = T. m A, where A and B are the matrix forms of the input and output fields, T m To correct the transfer matrix, simply select a suitable input field A and measure its corresponding output field B to calculate the corrected transfer matrix T. m .

[0038] T m =BA -1 (2)

[0039] Step S3: Obtain the corrected image based on the denoised spatial domain image and the corrected transfer matrix.

[0040] A transparent hollow tube structure model was constructed using finite element software, and the transmission characteristics of the scattered light field were solved by ray tracing. The input field distribution A was set, and the output field B was obtained by simulation. The modified transmission matrix T was calculated by formula (2). m The denoised image obtained in step S1 is considered as B', and... The corrected image A' can then be obtained.

[0041] The following describes the specific implementation scheme of the method using the imaging of optically suspended particles in hollow-core optical fiber as an example. Hollow-core optical fiber is a hollow optical waveguide with an internal capillary structure. When imaging optically suspended particles within the hollow-core optical fiber, the fiber cladding and capillary structure interfere with light transmission, resulting in inaccurate acquisition of scattered images. Using the scattered light image of 6μm polystyrene microspheres as an example, the process of correcting the scattered light image of suspended particles within the hollow-core optical fiber is introduced. Figure 2 (a) Image of particle scattering captured at the fiber end face. Figure 2 (b) is a scattering image of suspended particles within the fiber core. Specifically, it includes:

[0042] Step 1: Preprocess the original scattered light image of the particles in the fiber core based on the frequency domain filtering algorithm;

[0043] Step 2: Based on the experimental fiber parameters, construct the fiber structure model using finite element software, and solve the transmission characteristics of the scattered light field using ray tracing; set the input field distribution A, simulate the output field B, and construct the transmission matrix T;

[0044] Step 3: Use the calculated transfer matrix T to invert and correct the preprocessed image of scattered light from particles within the fiber core. Treat the preprocessed image as B', and use A' = T -1 B' yields the corrected result A'; during matrix inversion, the truncated singular value method is used to suppress matrix ill-conditionedness and avoid noise amplification; first, singular value decomposition is performed on T, T = UDV. T Let U and V be orthogonal matrices, and D be a diagonal matrix whose diagonal elements are singular values. Larger singular values ​​containing the main information of the matrix are retained, while smaller singular values ​​below a set threshold that are sensitive to noise and perturbations are set to 0, resulting in D'. Finally, T... -1 =VD' -1 U T Complete the inversion of matrix T.

[0045] Comparison of two-dimensional correlation coefficients between the pre- and post-correction scattered images and the end-face reference image, for example Figure 3 As shown.

[0046] Images of scattered light from polystyrene microspheres of different particle sizes within the fiber core were collected and inverted for correction. These images were then compared with a reference image at the end face to calculate the correlation coefficient. The correlation coefficients before and after correction are shown below. Figure 4 As shown.

[0047] Example 2:

[0048] This invention also provides a system for imaging correction of microparticles inside a transparent hollow tube, comprising:

[0049] The first processing module is used to preprocess the image of scattered light from particles inside the transparent hollow tube to obtain a denoised spatial image.

[0050] The second processing module is used to construct the corrected transmission matrix;

[0051] The third processing module is used to obtain the corrected image based on the denoised spatial domain image and the corrected transfer matrix.

[0052] Preferably, the first processing module preprocesses the image of scattered light from particles inside the transparent hollow tube using frequency domain filtering technology.

[0053] As one embodiment of the present invention, the transmission matrix T is modified. m For: T m =BA -1 Where A and B are the matrix forms of the input and output fields when light passes through the sidewall of the transparent hollow tube.

[0054] As one embodiment of the present invention, the third processing module uses finite element software to construct a transparent hollow tube structure model, and uses ray tracing to solve the transmission characteristics of the scattered light field; it sets the input field distribution A, simulates to obtain the output field B, and calculates the modified transmission matrix T. m The denoised image obtained in step S1 is considered as B', and... The corrected image A' can then be obtained.

[0055] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for imaging correction of microparticles inside a transparent hollow tube, characterized in that, include: Step S1: Preprocess the image of scattered light from particles inside the transparent hollow tube to obtain a denoised spatial image; Step S2: Construct the corrected transfer matrix; Step S3: Obtain the corrected image based on the denoised spatial image and the corrected transfer matrix.

2. The method for imaging correction of microparticles inside a transparent hollow tube as described in claim 1, characterized in that, In step S1, the image of scattered light from particles inside the transparent hollow tube is preprocessed using frequency domain filtering technology.

3. The method for imaging correction of microparticles inside a transparent hollow tube as described in claim 2, characterized in that, Corrected transfer matrix T m For: T m =BA -1 Where A and B are the matrix forms of the input and output fields when light passes through the sidewall of the transparent hollow tube.

4. The method for imaging correction of microparticles inside a transparent hollow tube as described in claim 3, characterized in that, In step S3, a transparent hollow tube structure model is constructed using finite element software, and the transmission characteristics of the scattered light field are solved using ray tracing; the input field distribution A is set, the output field B is obtained through simulation, and the corrected transmission matrix T is calculated. m The denoised image obtained in step S1 is considered as B', and... The corrected image A' can then be obtained.

5. A system for imaging correction of microparticles inside a transparent hollow tube, characterized in that, include: The first processing module is used to preprocess the image of scattered light from particles inside the transparent hollow tube to obtain a denoised spatial image. The second processing module is used to construct the corrected transmission matrix; The third processing module is used to obtain the corrected image based on the denoised spatial domain image and the corrected transfer matrix.

6. The system for imaging correction of microparticles inside a transparent hollow tube as described in claim 5, characterized in that, The first processing module preprocesses the image of light scattered by particles inside the transparent hollow tube using frequency domain filtering technology.

7. The system for imaging correction of microparticles inside a transparent hollow tube as described in claim 6, characterized in that, Corrected transfer matrix T m For: T m =BA -1 Where A and B are the matrix forms of the input and output fields when light passes through the sidewall of the transparent hollow tube.

8. The system for imaging correction of microparticles inside a transparent hollow tube as described in claim 7, characterized in that, The third processing module uses finite element method software to construct a transparent hollow tube structure model and employs ray tracing to solve for the transmission characteristics of the scattered light field. It sets the input field distribution A, simulates the output field B, and calculates the corrected transmission matrix T. m The denoised image obtained in step S1 is considered as B', and... The corrected image A' can then be obtained.

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