Dot-assisted focusing digital holographic microscope system and holographic reconstruction method

Abstract

The present application relates to a kind of dot auxiliary focusing digital holographic microscope system and holographic reconstruction method, the system includes digital holographic microscopic optical path part and dot auxiliary focusing optical path part, digital holographic microscopic optical path part is irradiated after the object sample of polarization modulation narrowband laser to be measured with reference mirror reflected polarization orthogonal reference light in polarization camera interference imaging, different phase shift acquisition of single image is realized;Dot auxiliary focusing optical path part utilizes the definition of image to calculate the focus position of the object sample to be measured, can directly obtain the best inverse diffraction distance required in digital holographic reconstruction process.Compared with prior art, the present application has improved the autofocusing efficiency of digital holographic microscope, greatly speed up the speed of digital holographic three-dimensional surface reconstruction, on the premise of guaranteeing the reconstruction measurement precision, improves the efficiency and real-time of reconstruction and the like advantages.

Description

Technical Field

[0001] This invention relates to the field of optical microscopy, and in particular to a dot-matrix-assisted focusing digital holographic microscope system and a holographic reconstruction method. Background Technology

[0002] With the development of micro-nano fabrication technology, more and more functional devices are trending towards high performance and miniaturization. High-precision measurement of the surface morphology of microstructures is crucial for improving the performance and quality of these devices. Currently, various optical measurement techniques are used for measuring the surface morphology of micro-nano structures, including white light interferometers, confocal microscopes, and digital holographic microscopes. Among these, digital holographic microscopes offer advantages such as simple operation, non-contact nature, and high precision, and have wide applications in the fields of biological cells, materials science, and microelectronics.

[0003] In digital holographic systems, especially those incorporating microscopic imaging, precise diffraction distances cannot be obtained through measurement. Obtaining diffraction distances using autofocus algorithms is a common approach, based on the difference between the focused and defocused images and the establishment of a suitable focusing criterion function. However, autofocus algorithms typically require significant computation time, with higher precision demands necessitating even greater computation. Furthermore, autofocus algorithms for single images are more susceptible to noise interference.

[0004] How to achieve high-precision and rapid holographic reconstruction based on a microscope has become a technical problem that needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art by providing a dot-matrix-assisted focusing digital holographic microscope system and a holographic reconstruction method.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] According to one aspect of the present invention, a dot-matrix-assisted focusing digital holographic microscope system is provided, the system comprising a digital holographic microscopy optical path portion and a dot-matrix-assisted focusing optical path portion;

[0008] The structure of the digital holographic microscopic optical path is as follows: the LD digital holographic light source passes sequentially through a spatial pinhole collimating filter, a polarizer, a second focusing lens, and a first semi-transparent mirror. When passing through the beam splitter, it is divided into an object arm and a reference arm. The object arm is equipped with a second microscope objective, and the light is reflected back to the beam splitter by the object sample. The reference arm is equipped with a first filter, a first quarter-wave plate, a third microscope objective, and a plane mirror. The light is reflected back to the beam splitter by the plane mirror and then combined. After beam combining, the beam passes sequentially through a first tube mirror, a dichroic mirror, and a second quarter-wave plate, and finally enters the polarization camera for interference imaging to obtain a digital holographic image.

[0009] The structure of the dot matrix-assisted focusing optical path is as follows: the monochromatic light source passes sequentially through the third focusing lens, the focusing template, and the second tube mirror; the bright field light source passes through the fourth focusing lens and the second filter; the two beams converge through the second semi-transparent mirror; the converged beam passes sequentially through the beam splitter prism, the second microscope objective, and is reflected back to the beam splitter prism by the object sample; after passing through the first tube mirror, it is reflected by the dichroic mirror and finally imaged by the color camera to obtain a dot matrix image and a bright field color image.

[0010] Preferably, the spatial pinhole collimating filter includes a first microscope objective, a pinhole aperture, and a first focusing lens, wherein the pinhole aperture is located at the intersection of the rear focal point of the first microscope objective and the front focal point of the first focusing lens.

[0011] Preferably, adjusting the polarization state in the optical path using a quarter-wave plate includes:

[0012] The first quarter-wave plate is rotated to adjust the angle between its fast axis and the polarization direction of the polarizer; when the angle between the fast axis and the polarizer is 45°, the beam passes through the first quarter-wave plate twice after entering the reference optical arm, and the linearly polarized light of the beam is orthogonal to the linearly polarized light of the object optical arm.

[0013] The second quarter-wave plate is rotated to adjust its fast axis direction. When the angle between its fast axis and the object beam and reference beam, which are orthogonal to the polarization direction, is 45°, the beams entering the polarization camera are converted into left-handed circularly polarized light and right-handed circularly polarized light, respectively. The polarization camera simultaneously records multiple polarization states with different polarization directions. The three-dimensional data of the object sample is obtained by resolving the multiple polarization states of the polarization camera through interferometric imaging.

[0014] Preferably, the polarizer is rotated to adjust the linear polarization direction and intensity of the emitted light, so as to maximize the light intensity of the LD digital holographic light source.

[0015] Preferably, each of the light sources is in a different wavelength band, specifically:

[0016] The LD digital holographic light source is a 650nm laser diode monochromatic light source;

[0017] The bright field light source is a white LED light source, and the monochrome light source is a green LED light source.

[0018] Preferably, the first filter is a 650nm±10nm bandpass filter, which can only allow light with wavelengths in the range of 650nm±10nm and absorb light in other wavelength ranges.

[0019] The second filter is a 630nm low-pass filter that absorbs light with wavelengths above 630nm.

[0020] Preferably, the dichroic mirror is a 638nm long-pass dichroic mirror, which is placed at a 45° angle in the optical path, allowing light with a wavelength greater than 638nm to be transmitted and light with a wavelength less than 638nm to be reflected.

[0021] Preferably, the distance from the first tube mirror to the color camera is equal to the distance from the second tube mirror to the focusing template.

[0022] According to another aspect of the present invention, a holographic reconstruction measurement method is provided, the method comprising:

[0023] Perform separation phase-shift interpolation completion and four-step phase-shift operation on the input digital holographic image;

[0024] The sharpness curve of the input raster image is calculated to obtain the defocus distance of the raster image, thereby obtaining the optimal inverse diffraction distance;

[0025] Diffraction reconstruction is performed based on the results of the four-step phase-shifting operation and the optimal inverse diffraction distance;

[0026] Calculate the wrapped phase, unwrap the phase, and output the reconstruction result.

[0027] Preferably, the process of obtaining the optimal inverse diffraction distance is as follows: the sharpness value of the dot matrix image is calculated using the improved grayscale variance, the z-coordinate of the sharpness peak is obtained, and the distance from the object sample to the focal plane in the z-direction is calculated to determine the optimal inverse diffraction distance.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1) This invention integrates a dot-matrix-assisted focusing optical path into a parallel phase-shifting digital holographic microscope. The parallel phase-shifting digital holographic microscope system uses a polarization-modulated narrowband laser to illuminate the sample under test, which becomes the object light. The reference light, which is orthogonally polarized to the reference mirror, interferes with the image in the polarization camera, enabling the acquisition of different phase shifts in a single image and ensuring good accuracy of the measurement results. The dot-matrix-assisted focusing system uses the image sharpness to calculate the focal position of the sample under test, which can directly obtain the optimal inverse diffraction distance required in the digital holographic reconstruction process. This improves the autofocus efficiency of the digital holographic microscope, greatly accelerates the speed of digital holographic three-dimensional surface reconstruction, and improves the efficiency and real-time performance of reconstruction while ensuring the accuracy of reconstruction measurement.

[0030] 2) In this invention, the optimal inverse diffraction distance is calculated directly from the sharpness curve of the dot pattern, without the need for cyclic calculation of diffraction reconstruction, which can speed up the reconstruction of digital holographic three-dimensional surfaces.

[0031] 3) The optimal inverse diffraction distance in this invention is derived from the calculation results of a series of images, which is more robust than the diffraction reconstruction of a single image.

[0032] 4) The present invention uses different wavelengths for each light source, and the optical path is multiplexed by light of different wavelengths, thereby improving the accuracy and efficiency of optical path measurement.

[0033] 5) This invention can improve the real-time performance of digital holographic measurement systems in actual industrial scenarios and has broad application prospects. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the optical path structure of the dot matrix-assisted focusing digital holographic microscope system in this invention;

[0035] Figure 2 This is a schematic diagram illustrating the focusing distance calculation principle based on the sharpness of a dot matrix image in this invention.

[0036] Figure 2 (a) is the present invention Figure 2 A magnified view of part A in the middle;

[0037] Figure 2 (b) is the present invention Figure 2 A magnified view of part B in the middle section;

[0038] Figure 3 A schematic diagram of the traditional digital holographic reconstruction process;

[0039] Figure 4 This is a schematic diagram of the optimized digital holographic reconstruction process in this invention;

[0040] In the attached diagram, B is the focusing template, BS is the beam splitter prism, C1 is the first semi-transparent mirror, C2 is the second semi-transparent mirror, DM is the dichroic mirror, F1 is the first filter, F2 is the second filter, L1 is the first focusing lens, L2 is the second focusing lens, L3 is the third focusing lens, L4 is the fourth focusing lens, M is the plane mirror, O1 is the LD digital holographic light source, O2 is the monochromatic light source, O3 is the bright field light source, OL1 is the first microscope objective, OL2 is the second microscope objective, OL3 is the third microscope objective, P is the polarizer, QWP1 is the first quarter-wave plate, QWP2 is the second quarter-wave plate, S is the object sample, TL1 is the first tube mirror, TL2 is the second tube mirror, X1 is the polarizing camera, X2 is the color camera, and Z is the pinhole aperture. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0042] This invention provides a dot-matrix-assisted focusing digital holographic microscope system and a holographic reconstruction method. The main purpose is to improve the efficiency of image processing and the real-time performance of measurement by using a dot-matrix-assisted system to quickly calculate the diffraction distance while ensuring the good accuracy of the parallel phase-shifting digital holographic microscope system.

[0043] This embodiment relates to a dot-matrix-assisted focusing digital holographic microscope system, which includes a digital holographic microscopy optical path section and a dot-matrix-assisted focusing optical path section.

[0044] The structure of the optical path in a digital holographic microscope is as follows: The LD digital holographic light source sequentially passes through a first microscope objective, a pinhole aperture, a first focusing lens, a polarizer, a second focusing lens, and a semi-transparent mirror. Upon passing through the beam splitter, it splits into an object arm and a reference arm. The object arm houses the second microscope objective, and the light is reflected back to the beam splitter by the highly reflective object sample. The reference arm houses the first filter, a first quarter-wave plate, a third microscope objective, and a plane mirror, and the light is reflected back to the beam splitter for beam combining. After beam combining, the beam sequentially passes through a first tube mirror, a dichroic mirror, and a second quarter-wave plate, finally entering the polarization camera for interference imaging.

[0045] The structure of the dot matrix-assisted focusing optical path is as follows: the monochromatic light source passes through the third focusing lens, the focusing template, and the second tube mirror in sequence, while the bright field light source passes through the fourth focusing lens and the second filter. The two beams are combined by a semi-transparent mirror and then merged into the main optical path. The beams then pass through a beam splitter prism, the second microscope objective, the sample reflection back to the beam splitter prism, the first tube mirror, and the dichroic mirror in sequence, and are finally imaged by the color camera to obtain a dot matrix-assisted focusing image (referred to as a dot matrix image) and a bright field color image.

[0046] Specifically, such as Figure 1The LD digital holographic light source O1 emits a narrowband laser beam of 650nm. After passing through a filtering system consisting of the first microscope objective OL1 and a pinhole aperture, it is collimated into a parallel light source by the first focusing lens L1, and then becomes linearly polarized light by the polarizer P. The parallel linearly polarized light passes through the second focusing lens L2 and the first semi-transparent mirror C1, and then passes through the beam splitter prism BS to be split into object light and reference light. The object light passes through the second microscope objective OL2 and directly illuminates the surface of the highly reflective sample, and is reflected back to the beam splitter prism BS. The reference light passes through the first filter F1, is reflected by the plane mirror M, and passes twice through the first quarter-wave plate QWP1, also returning to the beam splitter prism BS, where it is combined. By adjusting the angle between the first quarter-wave plate QWP1 and the polarizer P, the polarization direction and state of the reflected reference light can be changed. By adjusting and finding a suitable angle, the linear polarization direction of the reflected reference light can be made perpendicular to that of the object light. Two linearly polarized beams pass through the first imaging tube TL1 and are transmitted through the dichroic mirror DM. They then pass through the second quarter-wave plate QWP2 in front of the camera and are transformed into left-handed and right-handed circularly polarized light, which finally enter the polarization camera X1 to record a spatially multiplexed digital holographic image.

[0047] The structure of the dot-matrix-assisted focusing optical path is as follows: Light emitted from monochromatic light source O2 first passes through the third focusing lens L3 to converge, increasing energy concentration. Then, it passes through the focusing template B to become an array of monochromatic dot-matrix focusing light sources. After passing through the second lens TL2, it merges with the bright-field light source O3 in the second semi-transparent mirror C2. The bright-field light source O3 is emitted by a white LED. After passing through the fourth focusing lens L4 and then the second filter F2, it merges with the monochromatic dot-matrix focusing light source. The two converging light sources are split into two beams after passing through the beam splitter BS. The transmitted light is absorbed by the first filter F1, and the reflected light passes through the second microscope objective OL2 and illuminates the object sample, reflecting back to the imaging lens TL1. Then, the beam is reflected by the dichroic mirror DM and enters the color camera X2 for imaging, obtaining the dot-matrix-assisted focusing image and the bright-field color image.

[0048] The LD digital holographic light source O1 is a 650nm laser diode monochromatic light source with a coherence length of up to 85μm.

[0049] The first microscope objective OL2, the pinhole aperture Z, and the first focusing lens L1 form a spatial pinhole collimating filter. The diameter of the pinhole aperture Z is 20 μm, and its position is strictly located at the back focal point of the first microscope objective OL1 and the front focal point of the first focusing lens L1.

[0050] The polarizer P is rotated to adjust the linear polarization direction and intensity of the emitted light. By adjusting the linear polarization direction of the polarizer P, the light intensity of the LD digital holographic light source O1 is maximized.

[0051] The first filter, F1, is a 650nm ± 10nm bandpass filter, allowing only light with wavelengths within the 650nm ± 10nm range to pass through, while absorbing light in other wavelength ranges. This filter allows light emitted from the LD digital holographic light source O1 to pass through and enter the reference optical arm. It absorbs light emitted from the bright-field light source O3 and the monochromatic light source O2, preventing the reference optical arm from interfering with the imaging of the object sample in the color camera X2.

[0052] The first quarter-wave plate QWP1 of the reference optical arm can be rotated to adjust the angle between its fast axis and the polarization direction of the polarizer. Adjusting the angle of the first quarter-wave plate QWP1 so that the angle between its fast axis and the linear polarization is 45°, the beam enters the reference optical arm and passes through the first quarter-wave plate QWP1 twice, resulting in linearly polarized light that is orthogonal to the linearly polarized light of the object optical arm.

[0053] The dichroic mirror DM is a 638nm long-pass dichroic mirror, placed at a 45° angle in the optical path. Light with wavelengths greater than 638nm is transmitted, while light with wavelengths less than 638nm is reflected. Using this dichroic mirror DM, light emitted from the LD digital holographic light source O1 can pass through, allowing it to enter the polarization camera X1; it also reflects light emitted from the bright-field light source O3 and the monochromatic light source O2, allowing it to enter the color camera X2.

[0054] The second quarter-wave plate QWP2 can be rotated to adjust its fast axis direction. Adjusting the angle of QWP2 so that its fast axis forms a 45° angle with both the object beam and the reference beam (orthogonal to the polarization direction) results in the beam entering the polarization camera X1 becoming left-handed and right-handed circularly polarized light, respectively. The polarization camera X1 can simultaneously record four polarization states with different polarization directions. Through interferometric imaging and the analysis of these four polarization states, the three-dimensional data of the object sample can be obtained.

[0055] The distance from the first lens TL1 to the color camera X2 is equal to the distance from the second lens TL2 to the focusing template B. At this point, the focusing template B is conjugate to the CMOS sensor of the color camera X2. Therefore, when the object sample is clearly imaged on the color camera X2, the dot matrix pattern can also be clearly imaged simultaneously.

[0056] The bright field light source O3 is a white LED light source, and the monochromatic light source O2 is a green LED light source.

[0057] The second filter, F2, is a 630nm low-pass filter that can absorb light with wavelengths above 630nm. Using this filter ensures that the emitted light from the bright-field light source O3 is less than 630nm, preventing it from entering the reference arm.

[0058] The focusing template B is an array of circular holes with a diameter of 7μm, and a coating is applied around the holes to prevent light from passing through.

[0059] This invention utilizes light sources of different wavelengths to perform different optical processes, maximizing optical path reuse and compressing structural volume. The specific wavelength division method is as follows:

[0060] The LD digital holographic light source O1 is a 650nm narrowband laser. After being split by the beam splitter (BS), it can pass through the first filter F1 (650nm±10nm bandpass filter) to obtain the light of the reference optical arm. After passing through the 638nm long-pass dichroic mirror (DM), it can pass through into the polarization camera X1.

[0061] The bright field light source O3 is a white LED light source. The light emitted is only light with a wavelength less than 630nm after passing through the second filter F2 (630nm low-pass filter). After the beam is split by the beam splitter BS, the light on the reference arm is absorbed by the first filter F1, so it will not return to the plane mirror M and interfere with the imaging of the object sample. After passing through the 638nm long-pass dichroic mirror DM, it can be reflected into the color camera X2.

[0062] The monochromatic light source O2 is a green LED light source with a wavelength range of around 530nm. After being split by the beam splitter BS, the light on the reference arm is absorbed by the first filter F1. After passing through the 638nm long-pass dichroic mirror DM, it can be reflected into the color camera X2.

[0063] This embodiment also relates to a holographic reconstruction method based on a dot-matrix-assisted focusing digital holographic microscope system, including the following process:

[0064] Perform separation phase-shift interpolation completion and four-step phase-shift operation on the input digital holographic image;

[0065] The sharpness curve is calculated for the input raster image to obtain the defocus distance of the raster image, thereby obtaining the optimal inverse diffraction distance;

[0066] Diffraction reconstruction is performed based on the results of the four-step phase-shifting operation and the optimal inverse diffraction distance;

[0067] Calculate the wrapped phase, unwrap the phase, and output the reconstruction result.

[0068] The dot-matrix assisted focusing method of this invention calculates the focusing distance based on the sharpness of the dot-matrix image, thereby determining the diffraction distance for digital holographic reconstruction, such as... Figure 2 As shown. The specific implementation method is as follows:

[0069] By observing the state of the dot matrix pattern in a color camera, the focal plane of the sample can be located more quickly and accurately. When the sample is located on the focal plane of the microscope, the dot matrix pattern on the color camera is clear, and obvious dark boundaries can be seen between the dots; when the sample deviates from the focal plane of the microscope, the dot matrix pattern is blurred. Based on these characteristics, this invention uses an improved grayscale variance to calculate the sharpness value of the dot matrix image, which is used to solve for the z-coordinate of the sharpness peak and to calculate the distance in the z-direction from the current sample to the focal plane, thereby determining the inverse diffraction distance.

[0070] The acquired dot matrix image has the characteristic of being blurred, then clear, and then blurred again before and after the focal point. By calculating the sharpness operator on the image, the distance value of the focal point position of the dot matrix pattern can be obtained. Figure 2(a) and 2(b) These are schematic diagrams of clear and blurry raster images, respectively.

[0071] In polarization phase-shifting digital holographic reconstruction calculations, the inverse diffraction distance is related to the focal distance of the object sample. Therefore, Figure 3 The traditional digital holographic reconstruction process can be optimized into, for example... Figure 4 The reconstruction process.

[0072] Compared to traditional digital holographic reconstruction, the optimized inverse diffraction distance is calculated directly from the sharpness curve of the dot matrix pattern, without the need for iterative calculations for diffraction reconstruction, thus accelerating the reconstruction of digital holographic 3D surfaces. Furthermore, the optimal inverse diffraction distance calculated with dot matrix assistance is derived from the results of a series of images, making it more robust than diffraction reconstruction from a single image.

[0073] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A dot-assisted focusing digital holographic microscope system, characterized in that, The system comprises a digital holographic microscopic optical path part and a dot array auxiliary focusing optical path part; The digital holographic microscopic optical path part comprises an LD digital holographic light source (O1), a spatial pinhole collimation filter, a polarizer (P), a second focusing lens (L2), a first semi-transparent mirror (C1), a beam splitter (BS), a second microscopic objective lens (OL2), a first filter (F1), a first quarter-wave plate (QWP1), a third microscopic objective lens (OL3), a plane mirror (M), a first tube lens (TL1), a dichroic mirror (DM) and a second quarter-wave plate (QWP2). The dot array auxiliary focusing optical path part comprises a monochromatic light source (O2), a third focusing lens (L3), a focusing template (B), a second tube lens (TL2), a bright field light source (O3), a fourth focusing lens (L4), a second filter (F2), a second semi-transparent mirror (C2), the beam splitter (BS), the second microscopic objective lens (OL2), the object sample (S), the first tube lens (TL1) and the dichroic mirror (DM). The focusing template (B) is used for changing the light passing through the third focusing lens (L3) into a single-color dot array focusing light source array, so as to project a dot array image on the surface of the object sample (S). The digital holographic reconstruction based on the dot array image comprises the following steps: calculating the sharpness curve based on the dot array image, calculating the sharpness value of the dot array image by using the improved gray-scale variance, obtaining the z coordinate of the sharpness peak value, and calculating the distance of the object sample (S) to the focal plane in the z direction, so as to determine the optimal inverse diffraction distance. The single diffraction reconstruction based on the optimal inverse diffraction distance and the digital holographic image is performed without the cyclic iteration calculation of the traditional self-focusing algorithm.

2. The dot-assisted focusing digital holographic microscope system according to claim 1, wherein, The spatial pinhole collimation filter comprises a first microscopic objective lens (OL1), a pinhole diaphragm (Z) and a first focusing lens (L1).

3. The dot-assisted focusing digital holographic microscope system according to claim 1, wherein, The first quarter-wave plate (QWP1) is rotated to adjust the angle between the fast axis and the polarization direction of the polarizer. When the angle between the fast axis and the polarization direction of the polarizer is 45°, the linearly polarized light of the light beam and the linearly polarized light of the object light arm are orthogonal after the light beam enters the reference light arm twice through the first quarter-wave plate (QWP1). The second quarter-wave plate (QWP2) is rotated to adjust its fast axis direction, and when its fast axis is orthogonal to the polarization direction, the included angle between the object light and the reference light is 45°, and the light beam entering the polarization camera (X1) becomes left-handed circularly polarized light and right-handed circularly polarized light respectively; the polarization camera (X1) records multiple polarization states of different polarization directions at the same time, and the three-dimensional data of the object sample (S) are analyzed through interference imaging and multiple polarization states of the polarization camera.

4. The dot-assisted focusing digital holographic microscope system according to claim 1, wherein, The polarizer (P) is rotated to adjust the linear polarization direction and intensity of the outgoing light, so that the light intensity of the LD digital holographic light source (O1) is maximum.

5. The dot-assisted focusing digital holographic microscope system according to claim 1, wherein, Each of the above light sources is in a different waveband, specifically: The LD digital holographic light source (O1) is a 650nm laser diode monochromatic light source; The bright field light source (O3) is a white LED light source, and the monochromatic light source (O2) is a green LED light source.

6. The dot-assisted focusing digital holographic microscope system according to claim 1, wherein, The first filter (F1) is a 650nm±10nm band-pass filter, which can only pass light with a wavelength in the range of 650nm±10nm, and absorb light in other wavebands; The second filter (F2) is a 630nm low-pass filter, which absorbs light with a wavelength of 630nm or more.

7. The dot-assisted focusing digital holographic microscope system according to claim 1, wherein, The dichroic mirror (DM) is a 638nm long-wave dichroic mirror, which is placed at an angle of 45° in the optical path, and light with a wavelength greater than 638nm is transmitted, and light with a wavelength less than 638nm is reflected.

8. The dot-assisted focusing digital holographic microscope system according to claim 1, wherein, The distance from the first tube lens (TL1) to the color camera (X2) is equal to the distance from the second tube lens (TL2) to the focusing template (B).

9. A method for holographic reconstruction using the dot-matrix assisted focusing digital holographic microscope system according to any one of claims 1-8, characterized in that, The method comprises: Separate phase shift interpolation completion and four-step phase shift operation are performed on the input digital holographic image; The sharpness curve of the input dot matrix image is calculated to obtain the out-of-focus distance of the dot matrix image, so as to obtain the optimal inverse diffraction distance; Based on the results of the four-step phase shift operation and the optimal inverse diffraction distance, diffraction reconstruction is performed; The wrapped phase is calculated, and phase unwrapping is performed to output the reconstruction result.

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