CN-116819751-B - White light lens-free single-frame weak conjugate reconstruction method based on difference

Abstract

The invention provides a differential-based white-light lens-free single-frame weak conjugate reconstruction method, which can realize weakening conjugate images and improving single-frame imaging resolution without using additional elements and complex algorithms in a white-light lens-free imaging system. The method comprises the steps of obtaining spectrum distribution information of a system light source by utilizing a spectrometer, carrying out differential processing to obtain a reconstruction wavelength, preprocessing a collected single frame image by utilizing a hologram subtracting average value method, generating light intensity maps of different defocusing planes by utilizing an angular spectrum propagation formula, determining a defocusing distance range based on a definition discrimination factor, and calculating differential distribution on different focal planes in the distance range obtained in the step three based on numerical value differential to obtain a final result preferentially. The invention can reduce the requirement of light source spectrum width in the traditional lens-free microscope and effectively reduce the cost of the system. Under the condition of single-frame image acquisition, the imaging resolution of the white-light lens-free microscope is improved, and the conjugate image is weakened.

Inventors

• ZHANG JIALIN
• YANG YONGJIE
• WANG ZHENGUO
• LIU CHANG
• JIANG RUIRUI

Assignees

• 南通大学

Dates

Publication Date

20260512

Application Date

20230703

Claims (4)

1. 1. The white light lensless single-frame weak conjugate reconstruction method based on the difference is characterized by comprising the following steps of: The method comprises the steps of obtaining spectrum distribution information of a white light source of a lens-free microscopic imaging system, fitting by using a function, and carrying out differential processing on the fitted function to obtain a reconstruction wavelength, wherein the lens-free microscopic imaging system comprises the white light source, a sample to be tested and an imaging sensor which are arranged from top to bottom, and the luminous center position of the light source is positioned on the optical axis of the whole imaging system; preprocessing a single frame image acquired by an imaging sensor to obtain a processed holographic image; generating light intensity maps of different defocus planes based on the original acquired image by utilizing an angular spectrum propagation formula, and determining a defocus distance range based on a definition discrimination factor; Calculating differential distribution on different focal planes in the obtained distance range based on the acquired images after numerical differential processing and preprocessing, and preferentially obtaining a final result; The method comprises the following steps of obtaining spectrum distribution information of a system white light source by utilizing a spectrometer, providing a specified function for fitting, and then carrying out differential processing to obtain a reconstruction wavelength, wherein the method comprises the following steps: Measuring a white light source by using a spectrometer, and deriving wavelength and corresponding relative light intensity data thereof; the relative light intensity data were fitted with the following function: ; In the light wave length of the light wave, For the relative light intensity distribution of the spectrum, 、 、 As the coefficients to be fitted, For the purpose of the order of the marks, 1-3 Times the number of maxima in the data to be fitted; Fitting the resulting pairs of functions And if the distribution function after the deviation is obtained has a plurality of equivalent maximum values, corresponding to the plurality of wavelength values, selecting one as the reconstruction wavelength.
2. 2. The differential white-light lens-free single-frame weak conjugate reconstruction method as defined in claim 1, wherein the method comprises preprocessing the acquired single-frame image by using hologram subtraction average method, and comprises the following steps of directly acquiring a light intensity image by an imaging sensor as follows , The coordinates of the discretized image acquired by the imaging sensor are positive integers, and the formula is utilized A processed holographic image is obtained, wherein, ; And The horizontal pixel number and the vertical pixel number of the discretization map acquired by the imaging sensor are positive integers respectively.
3. 3. The differential-based white-light lensless single-frame weak conjugate reconstruction method of claim 1, wherein the differential distribution on different focal planes within the selected distance range is obtained by using numerical differential and the preprocessed acquired image calculation, and the final result is preferentially obtained, comprising the following steps: To be used for For step length, to Generating defocus distance ranges for reconstructed wavelengths Intensity patterns at different distances in , , Representing a downward rounding; Is that A light intensity pattern is generated at the point, Is that A light intensity map generated thereat; At the position of Differentiating the generated light intensity pattern in the direction, namely The adjacent light intensity distributions are subtracted, and the obtained distribution diagram is recorded as ; At the position of And selecting an optimal result by using the definition discrimination factor or priori knowledge.
4. 4. The differential-based white-light lensless single-frame weak conjugate reconstruction method of claim 1, wherein the distance between the white-light source and the sample to be measured is Distance between sample to be measured and imaging sensor The ratio between them satisfies the following conditions: ; Wherein, the Is the diameter of a white light source, The minimum size that needs to be distinguished for the sample to be measured is the highest resolution to be measured.

Description

White light lens-free single-frame weak conjugate reconstruction method based on difference Technical Field The invention relates to the technical field of lensless microscopic imaging, in particular to a white light lensless single-frame weak conjugate reconstruction method based on difference. Background Optical microscopy has been used for microscopic observation, such as biomedical detection and analysis, microscopic particle observation, etc., since the end of the 16 th century. With the great development of the technological technology of semiconductors and the like, phase contrast microscope, differential interference microscope, confocal microscope and the like are gradually developed, so that the cognition of people on the microscopic world is greatly improved, a powerful influence basis is provided for disease diagnosis, drug research and development and the like, and the microscope is an indispensable important tool for modern clinical medicine, biopharmaceutical and the like. These optical microscopy results have a clear characteristic, namely, the "what you see is what you get" imaging mode, which has a big disadvantage in that it is subject to the bottleneck of development of hardware devices, and the imaging results want to be further improved and will encounter an obstacle. Furthermore, with no innovation in microscopic imaging system functionality and performance, the overall imaging system is increasingly expensive, cumbersome, and complex. Therefore, on the premise of ensuring the imaging quality, a lens-free microscopic imaging system is provided, which has low system cost, small volume and simple and convenient operation, and can provide a quick and cheap instant diagnosis tool for the areas with limited resource conditions. The lens-free microscopic imaging technology can be used as a novel large-view-field high-resolution microscopic imaging technology to break through the contradiction that resolution and view field size are difficult to be simultaneously considered, and rapid development is achieved in the last ten years. One key to enabling low cost and small volume of the overall system is "no lens". The method eliminates an expensive optical lens in a traditional microscopic imaging system, and performs label-free imaging by means of internal absorption or refractive index difference (which can cause phase difference) of the sample, so that the preparation process of the sample can be greatly simplified. In lensless microscopy imaging, one key factor limiting reconstruction quality (e.g., resolution) is the coherence (including temporal coherence and spatial coherence) of the light source in the imaging system. The LED light source has smaller volume, but the temporal and spatial coherence of the LED light source is worse than that of the laser light source, so that in order to obtain a higher imaging result, a certain system volume and cost are generally sacrificed, and the laser is used as the system light source, or the complexity of the system is slightly increased, and the filter is added to the light source of the LED to process. In addition, the lens-free microscope basically adopts a coaxial transmission type structure, namely, object light modulated by an object is coaxial with reference light, and the lens is abandoned by a system structure, so that the acquired image is an unfocused light intensity image. Traditionally, the acquired image is counter-propagated, typically by angular spectrum propagation, to obtain a light intensity map of the object at the focal plane. Since a general image sensor can only record light intensity information and lose phase information of an object, a conjugate image exists in a counter-propagated image, and the image is superimposed on an image of an actual object. In order to remove these conjugate images, i.e. to recover the phase information of the object, a team such as Aydogan Ozcan proposes various methods for removing the conjugate images (recovering the phase), for example, multi-angle illumination, multi-wavelength illumination, multi-height displacement, etc. to obtain multiple diffraction images of the object, so as to achieve the phase recovery of the object by using a corresponding algorithm. However, in the experimental process of the methods, accurate mechanical movement such as a 1 arc second accurate rotary displacement table is required, or a multi-wavelength adjustable light source (a wavelength tunable laser with high accuracy is required), the mechanical structure increases the cost of the system, reduces the robustness, and algorithmically acquires a plurality of light intensity maps and corresponding iterative algorithms, thereby obviously increasing the reconstruction time. Therefore, how to realize the lens-free deconjugated imaging by using a simple algorithm only based on a low-cost lens-free microscopic imaging system (such as a lens-free basic structure based on a white light source) with simple structure and