Phase retrieval and conjugate image suppression methods for multi-wavelength lensless microscopic cell imaging

Abstract

The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging belongs to the field of cell lensless microscopic imaging technology in the biological and pharmaceutical industries. It solves the problem that the existing technology does not consider the sub-pixel displacement between different holograms, which is not only cumbersome but also affects the effect and accuracy of image processing. The light intensity information under red light irradiation, the light intensity information under green light irradiation, and the light intensity information under blue light irradiation are obtained respectively; the optimal reproduction distance of the holographic microscopic image under the red light wavelength, the optimal reproduction distance of the holographic microscopic image under the green light wavelength, and the optimal reproduction distance of the holographic microscopic image under the blue light wavelength are respectively found; based on the light wave complex amplitude distribution of the reconstructed image plane under red light irradiation, the light wave complex amplitude distribution of the reconstructed image plane under green light irradiation, and the light wave complex amplitude distribution of the reconstructed image plane under blue light irradiation, the phase distribution for suppressing the conjugate image is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of cell lensless microscopic imaging in the fields of biology and medicine, and in particular to a phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging. Background Art

[0002] In the bioengineering and pharmaceutical industries, cells are the fundamental units of life. Imaging studies of cells are crucial for a deeper understanding of their structure and function, as well as for analyzing their state in biopharmaceuticals. Cell imaging techniques enable researchers to observe morphological changes and characteristics of cells under various physiological or pathological conditions, providing crucial information for disease diagnosis, treatment, and drug development. Among numerous cell imaging technologies, lensless holographic microscopy has attracted considerable attention due to its simplicity and low cost. However, this technology faces the challenge of the conjugate image problem. This conjugate image problem stems from phase loss on the recording plane. Due to the high frequency of light waves, only intensity information is recorded on the recording plane, making it difficult to obtain phase information. The presence of the conjugate image affects both amplitude and phase imaging in holography. For amplitude imaging, the conjugate image makes it difficult to distinguish image details, severely impacting imaging resolution. For phase imaging, the conjugate image generates diffraction ripple noise on the phase, which also affects the accuracy of phase imaging. Especially in the coaxial digital holographic structure, the object light and the reference light propagate in the same direction, and the real image and the conjugate image of the holographic reconstruction overlap closely, which is not possible like the off-axis holographic Figure 1 The phase recovery algorithm fully utilizes the advantages of combining the algorithm with the imaging system, and can reconstruct the phase distribution by recording the light intensity information on the surface, which can effectively weaken the influence of the conjugate image.

[0003] In the prior art, Chinese patent CN112098277A discloses a "method for detecting the species and activity of high-concentration microparticles based on three-wavelength lensless holographic imaging." This method can detect and count the species and activity of a variety of high-concentration microparticles, including microplastics, microalgae cells, and cancer cells. It also enables rapid on-site detection and counting of the activity of high-concentration microparticles, with a simple operation process, wide application range, low cost, and stable identification indicators. However, it does not consider sub-pixel displacement between different holograms, which not only complicates the process but also affects the effectiveness and accuracy of image processing.

[0004] In summary, the existing technology does not consider the sub-pixel displacement between different holograms, which not only makes the process cumbersome but also affects the effect and accuracy of image processing. Summary of the Invention

[0005] The present invention solves the problem that the prior art does not consider the sub-pixel displacement between different holograms, which not only makes the process cumbersome but also affects the effect and accuracy of image processing.

[0006] The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging of the present invention comprises the following steps: Step S1: constructing a multi-wavelength lensless microscopic cell imaging device, wherein the multi-wavelength lensless microscopic cell imaging device comprises a three-color LED light source, wherein the three-color LED light source is selected from red light, green light, and blue light;

[0007] Step S2: under the illumination of red light, green light, and blue light, the multi-wavelength lensless microscopic cell imaging device captures a holographic microscopic image under red light illumination, a holographic microscopic image under green light illumination, and a holographic microscopic image under blue light illumination, respectively;

[0008] Step S3: Taking the holographic microscopic image under red light as a reference, the lateral displacements of the holographic microscopic image under green light and the holographic microscopic image under blue light are measured and corrected, respectively, to obtain light intensity information under red light, light intensity information under green light, and light intensity information under blue light;

[0009] Step S4: based on the light intensity information under red light irradiation, the light intensity information under green light irradiation, and the light intensity information under blue light irradiation, respectively finding the optimal reproduction distance of the holographic microscopic image at the red light wavelength, the optimal reproduction distance of the holographic microscopic image at the green light wavelength, and the optimal reproduction distance of the holographic microscopic image at the blue light wavelength;

[0010] Step S5: based on finding the optimal reconstruction distance of the holographic microscopic image at the red light wavelength, the optimal reconstruction distance of the holographic microscopic image at the green light wavelength, and the optimal reconstruction distance of the holographic microscopic image at the blue light wavelength, respectively obtain the light wave complex amplitude distribution of the reconstructed image plane at the red light wavelength, the light wave complex amplitude distribution of the reconstructed image plane at the green light wavelength, and the light wave complex amplitude distribution of the reconstructed image plane at the blue light wavelength;

[0011] Step S6: Obtaining a conjugate image-suppressing phase distribution based on the complex amplitude distribution of light waves on the reconstructed image plane under red light illumination, the complex amplitude distribution of light waves on the reconstructed image plane under green light illumination, and the complex amplitude distribution of light waves on the reconstructed image plane under blue light illumination.

[0012] Furthermore, in one embodiment of the present invention, in the step S1, the multi-wavelength lens-free microscopic cell imaging device removes the micropore device.

[0013] Furthermore, in one embodiment of the present invention, in step S1, the three-color LED light source is evenly arranged in a ring along the center point, the center point of which is located on the optical axis of the multi-wavelength lensless microscopic cell imaging device and is placed 40 meters away from the sample to be tested. Above.

[0014] Furthermore, in one embodiment of the present invention, in step S3, the lateral displacements of the holographic microscopic image under green light irradiation and the holographic microscopic image under blue light irradiation are measured and corrected respectively based on the holographic microscopic image under red light irradiation, specifically as follows:

[0015] Taking the holographic microscopic image under red light as a reference, the lateral displacement of the holographic microscopic image under green light relative to the holographic microscopic image under red light is measured by Fourier transform, and the holographic microscopic image under green light is corrected based on the lateral displacement of the holographic microscopic image under green light relative to the holographic microscopic image under red light.

[0016] The method for measuring and correcting the lateral displacement of a holographic microscopic image under blue light irradiation is the same as the method for measuring and correcting the lateral displacement of a holographic microscopic image under green light irradiation.

[0017] Furthermore, in one embodiment of the present invention, in step S4, the steps of respectively searching for the optimal reproduction distance of the holographic microscopic image at a red wavelength, the optimal reproduction distance of the holographic microscopic image at a green wavelength, and the optimal reproduction distance of the holographic microscopic image at a blue wavelength are specifically as follows:

[0018] Taking the optimal reproduction distance of the holographic microscopic image under the red light wavelength as a benchmark, the optimal reproduction distance of the holographic microscopic image under the green light wavelength and the optimal reproduction distance of the holographic microscopic image under the blue light wavelength are found respectively.

[0019] Furthermore, in one embodiment of the present invention, the optimal reproduction distance of the holographic microscopic image under the red light wavelength is specifically:

[0020] The phase gradient standard deviation method is used to find the optimal reproduction distance of holographic microscopic images under red light wavelength.

[0021] Furthermore, in one embodiment of the present invention, the method of using the phase gradient standard deviation to find the optimal reproduction distance of the holographic microscopic image at the red wavelength is specifically as follows:

[0022] In 500 ~1000 In the range of 10 Find the maximum value of the phase gradient standard deviation for the step size, redefine the step size near the maximum value, and continue to find the maximum value of the phase gradient standard deviation until the accuracy of finding the phase gradient standard deviation reaches 1 When , the optimal reproduction distance of the holographic microscopic image under the red light wavelength is obtained.

[0023] Furthermore, in one embodiment of the present invention, in step S6, the phase distribution for suppressing the conjugate image is obtained based on the complex amplitude distribution of the light wave of the reconstructed image plane at the red wavelength, the complex amplitude distribution of the light wave of the reconstructed image plane at the green wavelength, and the complex amplitude distribution of the light wave of the reconstructed image plane at the blue wavelength, specifically:

[0024] Based on the complex amplitude distribution of the light wave of the reconstructed image plane at the red light wavelength, the complex amplitude distribution of the light wave of the reconstructed image plane at the green light wavelength and the complex amplitude distribution of the light wave of the reconstructed image plane at the blue light wavelength, with the red light wavelength as the main wavelength, a three-wavelength angular spectrum iterative algorithm is used to obtain the phase distribution for suppressing the conjugate image.

[0025] Furthermore, in one embodiment of the present invention, the phase distribution for suppressing the conjugate image is obtained by using a three-wavelength angular spectrum iterative algorithm based on the red wavelength, including the following steps:

[0026] Step S601: At the red wavelength, the complex amplitude distribution of the light wave is phase compensated on the reconstructed image plane, and the amplitude remains unchanged, thereby obtaining the complex amplitude distribution of the light wave at the red wavelength after the first update;

[0027] The light wave complex amplitude distribution at the red light wavelength after the first update is propagated to the sample to be tested using the angular spectrum diffraction theory to obtain the light wave complex amplitude distribution at the red light wavelength after the second update;

[0028] The complex amplitude distribution of the light wave at the red wavelength after the second update is constrained, and the phase remains unchanged, to obtain the complex amplitude distribution of the light wave at the red wavelength after the third update;

[0029] Step S602: At the green wavelength, the complex amplitude distribution of the light wave at the red wavelength after the third update is propagated to the reconstructed image plane using the angular spectrum diffraction principle to obtain the complex amplitude distribution of the light wave at the green wavelength after the first update;

[0030] The complex amplitude distribution of the light wave at the green wavelength after the first update is phase-compensated on the reconstructed image plane, and the amplitude remains unchanged, thereby obtaining the complex amplitude distribution of the light wave at the green wavelength after the second update;

[0031] The complex amplitude distribution of the light wave at the green light wavelength after the second update is propagated to the sample to be tested using the angular spectrum diffraction theory to obtain the complex amplitude distribution of the light wave at the green light wavelength after the third update;

[0032] The complex amplitude distribution of the light wave at the green wavelength after the third update is constrained, and the phase remains unchanged, to obtain the complex amplitude distribution of the light wave at the green wavelength after the fourth update;

[0033] Step S603: At the blue wavelength, the complex amplitude distribution of the light wave at the green wavelength after the fourth update is propagated to the reconstructed image plane using the angular spectrum diffraction principle to obtain the complex amplitude distribution of the light wave at the blue wavelength after the first update;

[0034] The complex amplitude distribution of the light wave at the blue light wavelength after the first update is phase-compensated on the reconstructed image plane, and the amplitude remains unchanged, thereby obtaining the complex amplitude distribution of the light wave at the blue light wavelength after the second update;

[0035] The light wave complex amplitude distribution at the blue light wavelength after the second update is propagated to the sample to be tested using the angular spectrum diffraction theory to obtain the light wave complex amplitude distribution at the blue light wavelength after the third update;

[0036] The complex amplitude distribution of the light wave at the blue light wavelength after the third update is constrained, and the phase remains unchanged, to obtain the complex amplitude distribution of the light wave at the blue light wavelength after the fourth update;

[0037] Step S604: Repeat steps S601 to S603 until the iteration condition is satisfied, thereby obtaining a phase distribution that suppresses the conjugate image.

[0038] Furthermore, in one embodiment of the present invention, in step S604, the iteration condition is specifically:

[0039] The sum of the mean square error of the complex amplitude distribution of the light wave in two iterations is less than the threshold;

[0040] or reaches the specified number of iterations.

[0041] This invention solves the problem that the existing technology does not consider the sub-pixel displacement between different holograms, which is not only cumbersome but also affects the effect and accuracy of image processing. Specific beneficial effects include:

[0042] 1. The phase recovery and conjugate image suppression methods for multi-wavelength lensless microscopic cell imaging described in the present invention fail to account for sub-pixel shifts between different holograms in the prior art, which is not only cumbersome but also affects the effectiveness and accuracy of image processing. To address these technical issues, the present invention uses the holographic microscopic image under red light as a reference, and measures and corrects the lateral shifts of the holographic microscopic image under green light and the holographic microscopic image under blue light, effectively resolving the related technical issues arising from the prior art's failure to account for sub-pixel shifts between different holograms.

[0043] 2. The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging described in this invention uses a three-color LED light source to acquire holographic microscopic images. Combined with frequency-domain sub-pixel displacement correction, the method introduces diffraction angle spectrum theory, global amplitude constraints, and phase compensation to the traditional multi-wavelength iterative algorithm. Furthermore, it employs a multi-wavelength autofocus algorithm and image registration to perform fast and high-precision phase recovery on complex light fields, thereby achieving the goal of suppressing conjugate images in the lensless coaxial holographic optical path.

[0044] 3. The phase retrieval and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging described in the present invention not only suppresses conjugate images by using light sources with red, green, and blue wavelengths, but also covers the three main wavelength bands of visible light. The differences in the response of different wavelengths to the refractive index and absorption characteristics of the sample under test can be used to provide complementary information, thereby improving phase retrieval accuracy.

[0045] 4. The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging of the present invention further simplifies the mechanical device by removing the micropore device in the traditional multi-wavelength lensless microscopic cell imaging device;

[0046] The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging described in the present invention is suitable for high-resolution detection of the three-dimensional morphology of micron-level cells and has the advantages of simplified device and high computational efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0048] Figure 1 is a diagram of a multi-wavelength lensless microscopic cell imaging device described in a specific embodiment;

[0049] Figure 2 1 is a schematic diagram of bilinear interpolation calculation method described in the specific implementation method;

[0050] Figure 3 is the three-wavelength iterative reproduction image after registration as described in the specific embodiment;

[0051] Figure 4 is the unregistered three-wavelength iterative reproduction image described in the specific embodiment;

[0052] Figure 5 is a holographic microscopic image under red light illumination as described in the specific embodiment;

[0053] Figure 6 is a holographic microscopic image under green light illumination as described in the specific embodiment;

[0054] Figure 7 is a holographic microscopic image under blue light illumination as described in the specific embodiment;

[0055] Figure 8 It is a reproduction diagram of the holographic microscopic image under red light illumination by the angular spectrum method described in the specific embodiment;

[0056] Figure 9 It is a reproduction diagram of the holographic microscopic image under green light illumination by the angular spectrum method described in the specific embodiment;

[0057] Figure 10 It is an angular spectrum method reproduction diagram of the holographic microscopic image under blue light irradiation as described in the specific implementation method. DETAILED DESCRIPTION

[0058] The following will clearly and completely describe various embodiments of the present invention in conjunction with the accompanying drawings. The embodiments described with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0059] The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging described in this embodiment includes the following steps: Step S1: constructing a multi-wavelength lensless microscopic cell imaging device, wherein the multi-wavelength lensless microscopic cell imaging device includes a three-color LED light source, and the three-color LED light source selects red light, green light, and blue light;

[0060] Step S2: under the illumination of red light, green light, and blue light, the multi-wavelength lensless microscopic cell imaging device captures a holographic microscopic image under red light illumination, a holographic microscopic image under green light illumination, and a holographic microscopic image under blue light illumination, respectively;

[0061] Step S3: Taking the holographic microscopic image under red light as a reference, the lateral displacements of the holographic microscopic image under green light and the holographic microscopic image under blue light are measured and corrected, respectively, to obtain light intensity information under red light, light intensity information under green light, and light intensity information under blue light;

[0062] Step S4: based on the light intensity information under red light irradiation, the light intensity information under green light irradiation, and the light intensity information under blue light irradiation, respectively finding the optimal reproduction distance of the holographic microscopic image at the red light wavelength, the optimal reproduction distance of the holographic microscopic image at the green light wavelength, and the optimal reproduction distance of the holographic microscopic image at the blue light wavelength;

[0063] Step S5: based on finding the optimal reconstruction distance of the holographic microscopic image at the red light wavelength, the optimal reconstruction distance of the holographic microscopic image at the green light wavelength, and the optimal reconstruction distance of the holographic microscopic image at the blue light wavelength, respectively obtain the light wave complex amplitude distribution of the reconstructed image plane at the red light wavelength, the light wave complex amplitude distribution of the reconstructed image plane at the green light wavelength, and the light wave complex amplitude distribution of the reconstructed image plane at the blue light wavelength;

[0064] Step S6: Obtaining a conjugate image-suppressing phase distribution based on the complex amplitude distribution of light waves on the reconstructed image plane under red light illumination, the complex amplitude distribution of light waves on the reconstructed image plane under green light illumination, and the complex amplitude distribution of light waves on the reconstructed image plane under blue light illumination.

[0065] In this embodiment, in step S1, the multi-wavelength lensless microscopic cell imaging device removes the micropore device.

[0066] In this embodiment, in step S1, the three-color LED light source is evenly arranged in a ring along the center point, the center point of which is located on the optical axis of the multi-wavelength lensless microscopic cell imaging device and is placed 40 meters away from the sample to be tested. Above.

[0067] In this embodiment, in step S3, the lateral displacements of the holographic microscopic image under green light irradiation and the holographic microscopic image under blue light irradiation are measured and corrected respectively based on the holographic microscopic image under red light irradiation, specifically as follows:

[0068] Taking the holographic microscopic image under red light as a reference, the lateral displacement of the holographic microscopic image under green light relative to the holographic microscopic image under red light is measured by Fourier transform, and the holographic microscopic image under green light is corrected based on the lateral displacement of the holographic microscopic image under green light relative to the holographic microscopic image under red light.

[0069] The method for measuring and correcting the lateral displacement of a holographic microscopic image under blue light irradiation is the same as the method for measuring and correcting the lateral displacement of a holographic microscopic image under green light irradiation.

[0070] In this embodiment, in step S4, the steps of respectively finding the optimal reproduction distance of the holographic microscopic image at the red wavelength, the optimal reproduction distance of the holographic microscopic image at the green wavelength, and the optimal reproduction distance of the holographic microscopic image at the blue wavelength are specifically as follows:

[0071] Taking the optimal reproduction distance of the holographic microscopic image under the red light wavelength as a benchmark, the optimal reproduction distance of the holographic microscopic image under the green light wavelength and the optimal reproduction distance of the holographic microscopic image under the blue light wavelength are found respectively.

[0072] In this embodiment, the optimal reproduction distance of the holographic microscopic image under the red light wavelength is specifically:

[0073] The phase gradient standard deviation method is used to find the optimal reproduction distance of holographic microscopic images under red light wavelength.

[0074] In this embodiment, the method of using the phase gradient standard deviation to find the optimal reproduction distance of the holographic microscopic image at the red wavelength is specifically as follows:

[0075] In 500 ~1000 In the range of 10 Find the maximum value of the phase gradient standard deviation for the step size, redefine the step size near the maximum value, and continue to find the maximum value of the phase gradient standard deviation until the accuracy of finding the phase gradient standard deviation reaches 1 When , the optimal reproduction distance of the holographic microscopic image under the red light wavelength is obtained.

[0076] In this embodiment, in step S6, the phase distribution for suppressing the conjugate image is obtained based on the complex amplitude distribution of the light wave of the reconstructed image plane at the red light wavelength, the complex amplitude distribution of the light wave of the reconstructed image plane at the green light wavelength, and the complex amplitude distribution of the light wave of the reconstructed image plane at the blue light wavelength. Specifically,

[0077] Based on the complex amplitude distribution of the light wave of the reconstructed image plane at the red light wavelength, the complex amplitude distribution of the light wave of the reconstructed image plane at the green light wavelength and the complex amplitude distribution of the light wave of the reconstructed image plane at the blue light wavelength, with the red light wavelength as the main wavelength, a three-wavelength angular spectrum iterative algorithm is used to obtain the phase distribution for suppressing the conjugate image.

[0078] In this embodiment, the phase distribution for suppressing the conjugate image is obtained by using a three-wavelength angular spectrum iterative algorithm based on the red wavelength, including the following steps:

[0079] Step S601: At the red wavelength, the complex amplitude distribution of the light wave is phase compensated on the reconstructed image plane, and the amplitude remains unchanged, thereby obtaining the complex amplitude distribution of the light wave at the red wavelength after the first update;

[0080] The light wave complex amplitude distribution at the red light wavelength after the first update is propagated to the sample to be tested using the angular spectrum diffraction theory to obtain the light wave complex amplitude distribution at the red light wavelength after the second update;

[0081] The complex amplitude distribution of the light wave at the red wavelength after the second update is constrained, and the phase remains unchanged, to obtain the complex amplitude distribution of the light wave at the red wavelength after the third update;

[0082] Step S602: At the green wavelength, the complex amplitude distribution of the light wave at the red wavelength after the third update is propagated to the reconstructed image plane using the angular spectrum diffraction principle to obtain the complex amplitude distribution of the light wave at the green wavelength after the first update;

[0083] The complex amplitude distribution of the light wave at the green wavelength after the first update is phase-compensated on the reconstructed image plane, and the amplitude remains unchanged, thereby obtaining the complex amplitude distribution of the light wave at the green wavelength after the second update;

[0084] The complex amplitude distribution of the light wave at the green light wavelength after the second update is propagated to the sample to be tested using the angular spectrum diffraction theory to obtain the complex amplitude distribution of the light wave at the green light wavelength after the third update;

[0085] The complex amplitude distribution of the light wave at the green wavelength after the third update is constrained, and the phase remains unchanged, to obtain the complex amplitude distribution of the light wave at the green wavelength after the fourth update;

[0086] Step S603: At the blue wavelength, the complex amplitude distribution of the light wave at the green wavelength after the fourth update is propagated to the reconstructed image plane using the angular spectrum diffraction principle to obtain the complex amplitude distribution of the light wave at the blue wavelength after the first update;

[0087] The complex amplitude distribution of the light wave at the blue light wavelength after the first update is phase-compensated on the reconstructed image plane, and the amplitude remains unchanged, thereby obtaining the complex amplitude distribution of the light wave at the blue light wavelength after the second update;

[0088] The light wave complex amplitude distribution at the blue light wavelength after the second update is propagated to the sample to be tested using the angular spectrum diffraction theory to obtain the light wave complex amplitude distribution at the blue light wavelength after the third update;

[0089] The complex amplitude distribution of the light wave at the blue light wavelength after the third update is constrained, and the phase remains unchanged, to obtain the complex amplitude distribution of the light wave at the blue light wavelength after the fourth update;

[0090] Step S604: Repeat steps S601 to S603 until the iteration condition is satisfied, thereby obtaining a phase distribution that suppresses the conjugate image.

[0091] In this embodiment, in step S604, the iteration condition is specifically:

[0092] The sum of the mean square error of the complex amplitude distribution of the light wave in two iterations is less than the threshold;

[0093] or reaches the specified number of iterations.

[0094] In the prior art, the sub-pixel displacement between different holograms is not considered, which not only makes the process cumbersome but also affects the effect and accuracy of image processing.

[0095] To solve the above technical problems, this embodiment proposes a phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging, including the following steps:

[0096] Step S1: Build a multi-wavelength lensless microscopic cell imaging device, such as Figure 1 As shown, the multi-wavelength lensless microscopic cell imaging device consists of five parts: a three-color LED (light emitting diode) light source, a sample to be tested, a slide and a cover glass, a CMOS (complementary metal oxide semiconductor) image sensor, and a computer. The CMOS image sensor is controlled by a computer, and the three-color LED light source is controlled by a computer to emit red light of wavelengths. , green light wavelength and blue wavelengths , control its voltage to 3 , the current is 0.1 . The three-color LED light source is used as the illumination light source for multi-wavelength lensless microscopic cell imaging. It is placed directly above the sample to be tested, and the light-emitting center of the three-color LED light source is located on the optical axis of the entire multi-wavelength lensless microscopic cell imaging device. The sample to be tested is a plastic microsphere, because the material is relatively close to conventional human cells in terms of optical properties and physical properties (size, thickness), and the material is easy to store, low in cost, and can also be used by researchers who are not familiar with biological experimental procedures. The diffraction fringes generated by the object light wave passing through the sample to be tested interfere with the light that directly passes through the sample and are transmitted to the computer as the original interference image.

[0097] The essence of a multi-wavelength lensless microscopic cell imaging device is to record interference patterns. Interference fringe visibility is a key indicator affecting interference fringe visibility. In a multi-wavelength lensless microscopic cell imaging device, the three-color LED light source has the greatest impact on interference fringe visibility. The main influencing factors of interference fringe visibility include the amplitude ratio of the two coherent lights, both of which come from the three-color LED light source, and the amplitude ratio is related to the absorbance of the sample.

[0098] The central wavelength and maximum half slope of the three-color LED light source will affect the non-monochromaticity of the three-color LED light source, and its coherence length Expressed as:

[0099] ;

[0100] Where, is the central wavelength of the three-color LED light source, is the wavelength of red light, Green light wavelength.

[0101] At room temperature (25 ), the maximum half-wave widths of red, green, and blue light are approximately 22 , 38 and 20 , from which we can calculate that the coherence lengths of the three LED light sources are 19.845 , 7.116 and 11.045 The size of the three LED light sources will affect the allowable width, which is the critical value at which interference fringes can be clearly observed. The specific calculation formula is:

[0102] ;

[0103] Where, is the allowable width of the three LED light sources, is the interference aperture angle, , For the largest test sample (diameter 40 ), The distance between the three LED light sources and the sample to be tested is calculated, and the allowable widths of the three LED light sources are 3.15 , 2.6 and 2.35 .

[0104] It can be seen that the greater the distance between the three LED light sources and the sample to be tested, the greater the allowable width of the three LED light sources. Due to the power limitation of the three LED light sources, too far a distance will result in too weak a signal. Therefore, the distance between the three LED light sources and the sample to be tested is set at 40 At this time, the allowable widths of the three LED light sources are 3.15 , 2.6 and 2.35 Therefore, the diameter of the embodiment is selected to be 2 , the central wavelengths are 630 , 520 and 470 This method eliminates the need for additional micropores beneath the three-color LED light source, further simplifying the mechanical structure compared to conventional multi-wavelength lensless microscopic cell imaging devices. By eliminating the micropore structure found in conventional multi-wavelength lensless microscopic cell imaging devices, the present device simplifies the mechanical design while maintaining imaging performance. Although the overall height may increase slightly, the use of a three-color LED light source with a smaller geometric diameter allows for significant optimization of both length, width, and weight, resulting in a more compact and lightweight overall structure, making it easier to carry and integrate into applications.

[0105] Step S2: Take a pair of holographic microscopic images under each color illumination, such as Figures 5 to 7 As shown, a total of three holographic microscopic images were collected, which are respectively recorded as holographic microscopic images under red light illumination , holographic microscopic image under green light Holographic microscopic images under blue light The entire process can be seen as interference between the light scattered by the sample to be tested and the light not modulated by the sample to be tested. The light field carrying the object information will be captured by the CMOS image sensor after propagating a certain distance.

[0106] Step S3: Although red, green, and blue lights are all emitted by the same LED lamp beads, due to the manufacturing process of the LED manufacturer, the light sources emitting red, green, and blue lights are spatially independent and slightly offset. Therefore, when the illumination light emitted by them passes through the sample to be tested and is captured by the CMOS image sensor, there will actually be a sub-pixel displacement between the three frames of images captured. In addition, in order to quickly obtain an accurate reconstructed image, in subsequent image processing, when the captured holographic microscopic image is cropped into a holographic microscopic image of a single cell, a slight difference in lateral displacement will appear between the three images. Therefore, this displacement needs to be measured and corrected.

[0107] Since the method described in this embodiment only has lateral (XY direction) displacement errors, there is no error caused by rotation and scaling. Therefore, it is only necessary to obtain the sub-pixel displacement between the corresponding images to complete the image registration work. This embodiment obtains the displacement between the images to be registered by using the Fourier transform method, so that the holographic microscope image under green light illumination Holographic microscopic images under blue light Holographic microscopic image under red light First, the holographic microscope image under green light is Holographic microscopic image under red light Perform image registration. The specific method is as follows:

[0108] Holographic microscopic image under red light and holographic microscopic images under green light There is only horizontal The displacement is recorded as , then the two images can be represented as:

[0109] .

[0110] Then the relationship between the two images after Fourier transform is:

[0111] ;

[0112] Where, for The Fourier transform of For green light, For red light, and They are respectively in the frequency domain and in the spatial domain and The frequency component of the direction, is an imaginary unit. Then we can obtain the cross power spectrum between the two images in the frequency domain:

[0113] ;

[0114] Where, is the cross power spectrum between two images in the frequency domain, for The complex conjugate of . Then, by performing Fourier transform on the cross power spectrum between the two images in the frequency domain, we can obtain The impulse function at , the process is as follows:

[0115] ;

[0116] Where, is the inverse Fourier transform, For The impulse function at .

[0117] Holographic microscopic images obtained under green light Relative to the holographic microscopy image under red light The relative sub-pixel displacement between Then, the holographic microscopic image under green light irradiation was analyzed using the following method: Perform offset correction to obtain the corrected holographic microscopic image under green light illumination , combined with bilinear interpolation for local fine-tuning to further improve the edge alignment accuracy.

[0118] .

[0119] The principle of bilinear interpolation is to assume that the grayscale change in the area surrounded by four points around the floating point coordinate is linear, so the grayscale value of the floating point coordinate can be calculated based on the grayscale values ​​of the four neighboring pixels using the linear interpolation method. Figure 2 Assume that the floating image is mapped back to a floating point coordinate on the reference image. ,in and are all positive integers, is a pure decimal in the interval [0, 1], then The value of can be obtained from the coordinates in the original image 、 、 and The corresponding four pixel values ​​are jointly determined.

[0120] ;

[0121] ;

[0122] Where, is the light intensity information under the corrected green light.

[0123] Holographic microscopic image under blue light illumination The above operation is also performed, and the light intensity information under the corrected blue light is recorded as The holographic microscopic image under red light remains unchanged, and for the sake of consistency it is recorded as ;

[0124] .

[0125] Therefore, this embodiment improves the effect and accuracy of image processing by considering the sub-pixel displacement between different images.

[0126] Step S4: Based on the holographic microscopic image under red light illumination, the corrected holographic microscopic image under green light illumination, and the corrected holographic microscopic image under blue light illumination, respectively find the optimal reproduction distance of the holographic microscopic image under red light wavelength, the optimal reproduction distance of the holographic microscopic image under green light wavelength, and the optimal reproduction distance of the holographic microscopic image under blue light wavelength, specifically:

[0127] The multi-wavelength lens-free microscopic cell imaging device does not include an optical magnifying lens as in conventional microscope systems, and due to the protective glass layer (approximately 500 nm) on the surface of the CMOS image sensor, the device can be used to image the cells in a multi-wavelength lens-free microscopic cell imaging device. ), so the CMOS image sensor can only capture the out-of-focus intensity image, and the reproduction of the holographic microscopic image requires an accurate reproduction distance, that is, the distance between the sample to be measured and the CMOS image sensor, which is recorded as Because the phase distribution contains information such as the sample's height and refractive index, the calculation method is:

[0128] ;

[0129] Where, is the phase difference, is the height of the sample to be tested, is the change in refractive index at different locations of the sample.

[0130] From the above formula, we can see that and In other words, the phase distribution can proportionally reflect the height information of the sample to be tested. The best way to determine whether the current distance is the best reproduction distance is to detect the height information of the sample to be tested. Therefore, this embodiment uses the method based on the phase gradient standard deviation to find the optimal reproduction distance. The specific expression of the phase gradient standard deviation is:

[0131] ;

[0132] Where, is the modulus of the gradient, For the coordinates Chuyan The gradient component of the direction, For the coordinates Chuyan Directional gradient component.

[0133] The larger the phase gradient standard deviation, the more prominent and obvious the sample to be tested is, and the better the reproduction effect is. For the convenience of calculation, this embodiment adopts a multi-step iterative method to search, that is, first in 500 ~1000 In the range of 10 The maximum value of the phase gradient standard deviation is found for the step size, and then a new step size is determined near the maximum value obtained by the search. Repeat the above operation, and iterate until the final search accuracy reaches 1 Stop when the final As the optimal reproduction distance, the reproduction distance under red light image is obtained by this method. .

[0134] When using a multi-wavelength lensless microscopic cell imaging device for phase retrieval, the sample to be measured can be considered to be in the paraxial region. The Fresnel diffraction formula in the paraxial region is:

[0135] ;

[0136] Where, is the wave number, is the complex amplitude Spread The complex amplitude information after the distance, is the complex amplitude propagation distance, i.e., the reproduction distance, ( , ) is the coordinate on the object plane, used for integral calculation, is the coordinate on the recording plane.

[0137] It can be seen that the central wavelength of the three-color LED light source and complex amplitude propagation distance They appear in pairs, so we can know the central wavelength of the three-color LED light source The change of complex amplitude propagation distance Therefore, this embodiment uses red light, green light, and blue light as illumination sources, and can use the above formula to map them to three different defocus planes. Here, the light intensity information under the corrected red light is recorded as As the reference image, its reproduction distance is recorded as , the reproduction distance of the image captured under green light and blue light can be and They are:

[0138] ;

[0139] .

[0140] Step S5: Figures 8 to 10 As shown in Figure 2, the angular spectrum method is used to obtain the complex amplitude distribution of the light waves at the reconstructed image plane under three wavelengths: red, green, and blue. The angular spectrum method is expressed as:

[0141] ;

[0142] Where, is the complex amplitude distribution of the output light field, , is the Fourier transform, is the diffraction surface coordinate, is the natural logarithm The exponential operation of is the imaginary unit, is the frequency domain coordinate.

[0143] Extract the amplitude and phase distribution of the reconstructed image plane corresponding to the three-color LED light source respectively: and calculate the average light wave amplitude of the reconstructed image plane at three wavelengths and reconstruction phase , serving as global lightwave complex amplitude constraint and phase compensation, respectively.

[0144] ;

[0145] Where, It is a function for calculating the mean grayscale value of all pixels in multiple images. , and They are respectively the light wave amplitude distribution of the reconstructed image plane under the red light wavelength, the light wave amplitude distribution of the reconstructed image plane under the green light wavelength, and the light wave amplitude distribution of the reconstructed image plane under the blue light wavelength.

[0146] The new phase is calculated based on the reconstructed phase obtained at three wavelengths :

[0147] ;

[0148] Where, and The wavelengths are for three different situations. The phase distribution of the reconstructed image plane under three wavelengths of illumination.

[0149] Step S6: During the iterative reconstruction process, due to the iterative nature of the algorithm, some high-frequency oscillations or interferences may occur. These high-frequency interferences may affect the quality of the reconstructed image. Therefore, during the iterative process, Gaussian filtering is used to smooth the image to reduce these high-frequency interferences. This can not only reduce the influence of the conjugate image, but also make the reconstruction process more stable, and ultimately obtain a better quality reconstructed image. In image processing, a two-dimensional Gaussian function is usually used for filtering operations. The two-dimensional Gaussian function The expression is:

[0150] ;

[0151] Where, is the coordinate on the two-dimensional plane, which also represents the offset from the center position. is the standard deviation, and its size determines the width of the Gaussian distribution function. Adjust according to actual needs during the experiment , but in general It should be slightly larger than the system bandwidth to avoid over-smoothing.

[0152] The specific iterative process of the three-wavelength angular spectrum based on the red wavelength is as follows:

[0153] Step S601: At the red wavelength, the complex amplitude distribution of the light wave is phase compensated on the reconstructed image plane, and the amplitude remains unchanged, obtaining the complex amplitude distribution of the light wave at the red wavelength after the first update. ;

[0154] The complex amplitude distribution of light waves at red wavelength after the first update The angular spectrum diffraction theory is used to propagate to the sample to be tested, and the complex amplitude distribution of the light wave at the red light wavelength after the second update is obtained. , and apply a two-dimensional Gaussian function for filtering;

[0155] The complex amplitude distribution of light waves at red wavelength after the second update Constraints are performed, the phase remains unchanged, and the complex amplitude distribution of the light wave at the red light wavelength after the third update is obtained ;

[0156] Step S602: At the green wavelength, the complex amplitude distribution of the red wavelength after the third update The angular spectrum diffraction principle is used to numerically simulate the propagation to the reconstructed image plane to obtain the complex amplitude distribution of the light wave at the green light wavelength after the first update. ;

[0157] The complex amplitude distribution of light waves at green wavelength after the first update Phase compensation is performed on the reconstructed image plane, and the amplitude remains unchanged, obtaining the complex amplitude distribution of the light wave at the green light wavelength after the second update. ;

[0158] The complex amplitude distribution of light waves at green wavelength after the second update The angular spectrum diffraction theory is used to propagate to the sample to be tested, and the complex amplitude distribution of the light wave at the green light wavelength after the third update is obtained. , and apply a two-dimensional Gaussian function for filtering;

[0159] The complex amplitude distribution of light waves at green wavelengths after the third update Constraints are performed, the phase remains unchanged, and the complex amplitude distribution of the light wave at the green light wavelength after the fourth update is obtained. ;

[0160] Step S603: Under the blue wavelength, the complex amplitude distribution of the green wavelength after the fourth update The angular spectrum diffraction principle is used to numerically simulate the propagation to the reconstructed image plane to obtain the complex amplitude distribution of the light wave at the blue light wavelength after the first update. ;

[0161] The complex amplitude distribution of light waves at blue light wavelengths after the first update Phase compensation is performed on the reconstructed image plane, and the amplitude remains unchanged, obtaining the complex amplitude distribution of the light wave at the blue light wavelength after the second update. ;

[0162] The complex amplitude distribution of light waves at blue light wavelengths after the second update The angular spectrum diffraction theory is used to propagate to the sample to be tested, and the complex amplitude distribution of the light wave at the blue light wavelength after the third update is obtained. , and apply a two-dimensional Gaussian function for filtering;

[0163] The complex amplitude distribution of light waves at blue wavelengths after the third update Constraints are performed, the phase remains unchanged, and the complex amplitude distribution of the light wave at the blue light wavelength after the fourth update is obtained. ;

[0164] Step S604: Repeat steps S601 to S603 until the sum of the mean square error of the complex amplitude distribution of the light wave between the two iterations is Less than a predetermined threshold Or reach the specified number of iterations. The formula for calculating the sum of mean square errors is:

[0165] ;

[0166] Where, For the The complex amplitude distribution of the light wave of the iteration, For the The complex amplitude distribution of the light wave in the iteration.

[0167] The algorithm is based on red wavelengths. Compared to green and blue wavelengths, red wavelengths are longer, and their angular spectrum diffraction phase changes more gradually, leading to faster convergence during iterations. Furthermore, it prioritizes stabilizing the global phase distribution, reducing the number of overall iterations.

[0168] In summary, this embodiment adopts a three-color LED light source to acquire holographic microscopic images, combines frequency-domain sub-pixel displacement correction, introduces diffraction angle spectrum theory, global amplitude constraint and phase compensation on the traditional multi-wavelength iterative algorithm, and adopts a multi-wavelength autofocus algorithm and image registration to perform fast and high-precision phase recovery of complex light fields, thereby achieving the purpose of suppressing conjugate images in the lensless coaxial holographic optical path.

[0169] This method is suitable for high-resolution detection of the three-dimensional morphology of micron-scale cells and has the advantages of simplified equipment and high computational efficiency. For coaxial digital holography, the conjugate image can only be suppressed but not removed. Figure 3 The figure shows the three-wavelength iterative reproduction image using the method described in this embodiment. It can be seen that the reproduction image processed by this method has basically suppressed the interference of the conjugate image. Figure 4 The figure shows the technical effect achieved by directly performing three-wavelength angular spectrum iteration without using an image registration algorithm. As can be seen, there are slight differences in the lateral displacement of the holograms under red, green, and blue light illumination. While the iterative image can somewhat suppress the influence of the conjugate image, the resulting image is distorted.

[0170] The above is a detailed introduction to the phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging proposed in the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core concept. At the same time, for those skilled in the art, according to the concept of the present invention, there may be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging, characterized in that: The following steps are involved: Step S1: constructing a multi-wavelength lensless microscopic cell imaging device, wherein the multi-wavelength lensless microscopic cell imaging device includes a three-color LED light source, and the three-color LED light source is selected from red light, green light, and blue light; Step S2: under the illumination of red light, green light, and blue light, the multi-wavelength lensless microscopic cell imaging device captures a holographic microscopic image under red light illumination, a holographic microscopic image under green light illumination, and a holographic microscopic image under blue light illumination, respectively; Step S3: Taking the holographic microscopic image under red light as a reference, the lateral displacements of the holographic microscopic image under green light and the holographic microscopic image under blue light are measured and corrected, respectively, to obtain light intensity information under red light, light intensity information under green light, and light intensity information under blue light; Step S4: based on the light intensity information under red light irradiation, the light intensity information under green light irradiation, and the light intensity information under blue light irradiation, respectively finding the optimal reproduction distance of the holographic microscopic image at the red light wavelength, the optimal reproduction distance of the holographic microscopic image at the green light wavelength, and the optimal reproduction distance of the holographic microscopic image at the blue light wavelength; Step S5: based on finding the optimal reconstruction distance of the holographic microscopic image at the red light wavelength, the optimal reconstruction distance of the holographic microscopic image at the green light wavelength, and the optimal reconstruction distance of the holographic microscopic image at the blue light wavelength, respectively obtain the light wave complex amplitude distribution of the reconstructed image plane at the red light wavelength, the light wave complex amplitude distribution of the reconstructed image plane at the green light wavelength, and the light wave complex amplitude distribution of the reconstructed image plane at the blue light wavelength; Step S6: Obtaining a conjugate image-suppressing phase distribution based on the complex amplitude distribution of the lightwaves at the reconstructed image plane at the red wavelength, the green wavelength, and the blue wavelength.

2. The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging according to claim 1, characterized in that: In the step S1, the multi-wavelength lens-free microscopic cell imaging device is free of the micropore device.

3. The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging according to claim 1, characterized in that: In step S1, the three-color LED light sources are evenly arranged in a ring along a center point, the center point of which is located on the optical axis of the multi-wavelength lensless microscopic cell imaging device and is placed 40 cm above the sample to be tested.

4. The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging according to claim 1, characterized in that: In step S3, the lateral displacements of the holographic microscopic image under red light irradiation and the holographic microscopic image under blue light irradiation are measured and corrected respectively, with the holographic microscopic image under red light irradiation as a reference. Specifically, Taking the holographic microscopic image under red light as a reference, the lateral displacement of the holographic microscopic image under green light relative to the holographic microscopic image under red light is measured by Fourier transform, and the holographic microscopic image under green light is corrected based on the lateral displacement of the holographic microscopic image under green light relative to the holographic microscopic image under red light. The method for measuring and correcting the lateral displacement of a holographic microscopic image under blue light irradiation is the same as the method for measuring and correcting the lateral displacement of a holographic microscopic image under green light irradiation.

5. The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging according to claim 1, characterized in that: In step S4, the steps of respectively searching for the optimal reproduction distance of the holographic microscopic image at the red wavelength, the optimal reproduction distance of the holographic microscopic image at the green wavelength, and the optimal reproduction distance of the holographic microscopic image at the blue wavelength are specifically as follows: Taking the optimal reproduction distance of the holographic microscopic image under the red light wavelength as a benchmark, the optimal reproduction distance of the holographic microscopic image under the green light wavelength and the optimal reproduction distance of the holographic microscopic image under the blue light wavelength are found respectively.

6. The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging according to claim 5, characterized in that: The optimal reproduction distance of the holographic microscopic image under the red light wavelength is specifically: The phase gradient standard deviation method is used to find the optimal reproduction distance of holographic microscopic images under red light wavelength.

7. The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging according to claim 6, characterized in that: The method of using the phase gradient standard deviation to find the optimal reproduction distance of the holographic microscopic image at the red wavelength is specifically as follows: The maximum value of the phase gradient standard deviation is found in the range of 500μm to 1000μm with a step size of 10μm. After re-determining the step size near the maximum value, the maximum value of the phase gradient standard deviation is continued to be found until the accuracy of the phase gradient standard deviation reaches 1μm. The optimal reproduction distance of the holographic microscopic image under the red light wavelength is obtained.

8. The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging according to claim 1, characterized in that: In step S6, the phase distribution for suppressing the conjugate image is obtained based on the complex amplitude distribution of the light wave of the reconstructed image plane at the red light wavelength, the complex amplitude distribution of the light wave of the reconstructed image plane at the green light wavelength, and the complex amplitude distribution of the light wave of the reconstructed image plane at the blue light wavelength, specifically: Based on the complex amplitude distribution of the light wave of the reconstructed image plane at the red light wavelength, the complex amplitude distribution of the light wave of the reconstructed image plane at the green light wavelength and the complex amplitude distribution of the light wave of the reconstructed image plane at the blue light wavelength, with the red light wavelength as the main wavelength, a three-wavelength angular spectrum iterative algorithm is used to obtain the phase distribution for suppressing the conjugate image.

9. The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging according to claim 8, characterized in that: The method of obtaining the phase distribution for suppressing the conjugate image by using a three-wavelength angular spectrum iterative algorithm based on the red wavelength includes the following steps: Step S601: At the red wavelength, the complex amplitude distribution of the light wave is phase compensated on the reconstructed image plane, and the amplitude remains unchanged, thereby obtaining the complex amplitude distribution of the light wave at the red wavelength after the first update; The light wave complex amplitude distribution at the red light wavelength after the first update is propagated to the sample to be tested using the angular spectrum diffraction theory to obtain the light wave complex amplitude distribution at the red light wavelength after the second update; The complex amplitude distribution of the light wave at the red wavelength after the second update is constrained, and the phase remains unchanged, to obtain the complex amplitude distribution of the light wave at the red wavelength after the third update; Step S602: At the green wavelength, the complex amplitude distribution of the light wave at the red wavelength after the third update is propagated to the reconstructed image plane using the angular spectrum diffraction principle to obtain the complex amplitude distribution of the light wave at the green wavelength after the first update; The complex amplitude distribution of the light wave at the green wavelength after the first update is phase-compensated on the reconstructed image plane, and the amplitude remains unchanged, thereby obtaining the complex amplitude distribution of the light wave at the green wavelength after the second update; The complex amplitude distribution of the light wave at the green light wavelength after the second update is propagated to the sample to be tested using the angular spectrum diffraction theory to obtain the complex amplitude distribution of the light wave at the green light wavelength after the third update; The complex amplitude distribution of the light wave at the green wavelength after the third update is constrained, and the phase remains unchanged, to obtain the complex amplitude distribution of the light wave at the green wavelength after the fourth update; Step S603: At the blue wavelength, the complex amplitude distribution of the light wave at the green wavelength after the fourth update is propagated to the reconstructed image plane using the angular spectrum diffraction principle to obtain the complex amplitude distribution of the light wave at the blue wavelength after the first update; The complex amplitude distribution of the light wave at the blue light wavelength after the first update is phase-compensated on the reconstructed image plane, and the amplitude remains unchanged, thereby obtaining the complex amplitude distribution of the light wave at the blue light wavelength after the second update; The light wave complex amplitude distribution at the blue light wavelength after the second update is propagated to the sample to be tested using the angular spectrum diffraction theory to obtain the light wave complex amplitude distribution at the blue light wavelength after the third update; The complex amplitude distribution of the light wave at the blue light wavelength after the third update is constrained, and the phase remains unchanged, to obtain the complex amplitude distribution of the light wave at the blue light wavelength after the fourth update; Step S604: Repeat steps S601 to S603 until the iteration condition is satisfied, thereby obtaining a phase distribution that suppresses the conjugate image.

10. The phase recovery and conjugate image suppression method for multi-wavelength lensless microscopic cell imaging according to claim 9, characterized in that: In step S604, the iteration condition is specifically: The sum of the mean square error of the complex amplitude distribution of the light wave in two iterations is less than the threshold; or reaches the specified number of iterations.

Images