Single-exposure super-resolution microscopic digital holographic system and method

Abstract

The invention relates to a single-exposure super-resolution microscopic digital holography system and a single-exposure super-resolution microscopic digital holography method, and belongs to the technical field of microscopic digital holography and synthetic aperture. The system is obtained by improving a Mach-Zehnder holographic optical path. The single-exposure super-resolution microscopic digital holographic system comprises an illumination modulation subsystem and a microscopic imaging subsystem. The illumination modulation subsystems are used for dividing the collimated light beam into six inclined light beams with different optical paths, the six inclined light beams with the same inclination angle and different optical paths are used for irradiating an object needing to be observed, and the object light path and the reference light path both comprise the illumination modulation subsystems; the microscopic imaging subsystem is used for amplifying an image formed by an object and finally imaging the image on the charge-coupled device; the reference light beam and the object light beam interfere on the image collector to form interference fringes, the interference fringes comprise amplitude and phase information of a sample, the computer collects the interference fringes, and the interference fringes are reproduced through the computer and further processed to obtain sample information exceeding the diffraction limit of the system.

Description

Technical Field

[0001] The invention relates to a single-exposure super-resolution microscopic digital holographic system and method, belonging to the technical field of microscopic digital holography and synthetic aperture. Background Art

[0002] Digital holographic microscopy is a non-contact imaging method that does not damage the sample. It is suitable for observing cells, microorganisms and other objects that are sensitive to staining. It has the advantage of high resolution and can clearly present tiny details. It can image in real time, which is convenient for dynamic observation. Based on the above advantages, digital holographic microscopy is widely used. When using a digital holographic microscope for observation, the field of view will continue to shrink as the resolution increases. In order to ensure the imaging quality while having a larger field of view, industry insiders use inclined parallel light or structured light illumination to obtain multiple images. Using the synthesized spectrum of multiple images to expand the spectrum of a single image is an important method to achieve super-resolution.

[0003] However, the above method needs to collect multiple images for synthesis. Due to the limitation of multiple acquisitions, it cannot achieve single-frame real-time microscopic super-resolution imaging. Summary of the invention

[0004] The present invention provides a single-exposure super-resolution microscopic digital holographic system and method, which are used to improve the temporal and spatial resolution capability of the microscopic digital holographic system and enable the microscopic digital holography to achieve single-frame observation.

[0005] The technical solution of the present invention is: a single-exposure super-resolution microscopic digital holographic system, comprising an illumination modulation subsystem and a microscopic imaging subsystem;

[0006] The illumination modulation subsystem is used to divide the collimated light beam into six inclined light beams with different optical paths, and illuminate the object to be observed with the six inclined light beams with the same inclination angle and different optical paths. Both the object light path and the reference light path include the illumination modulation subsystem;

[0007] The illumination subsystem includes an illumination modulator I6, an illumination modulator II13 and a tilt generator I1, a tilt generator II14, and the microscopic imaging subsystem includes a microscopic objective lens 9;

[0008] The solid laser 1 emits a laser beam which passes through a beam splitter prism 2 to obtain an object beam and a reference beam;

[0009] One of the beams passes through the beam expander I3 and the lens I4 to generate a parallel beam, which is reflected by the reflector I5 to the illumination modulator I6, and then propagates to the tilt generator I7 to generate 6 tilted beams with the same tilt angle as the optical axis. These 6 beams of light are transmitted through the object to be measured 8, magnified by the microscope objective 9, and then propagated to the image sensor 16 through the beam combiner 15, which is called object light;

[0010] Another light beam passes through the reflector II10, the beam expander II11 and the lens II12 to obtain a parallel light beam. The parallel light beam passes through the illumination modulator II13 and the tilt generator II14 to obtain 6 tilted light beams with the same tilt angle as the optical axis. These 6 tilted light beams pass through the beam combiner 15 and then propagate to the image sensor 16, which are called reference light.

[0011] The laser beam is divided into an object beam and a reference beam by a beam splitter;

[0012] The object beam and the reference beam are modulated by the corresponding illumination modulation subsystem into beams with different illumination angles and the same angle with the optical axis;

[0013] The modulated object light beam is transmitted through the sample;

[0014] The object light penetrating the sample and the modulated reference light are combined by a beam combiner, interfere with each other on the charge coupled device and are collected and recorded in a computer.

[0015] Further, the illumination angles of the six inclined object light beams are 0°, 60°, 120°, 180°, 240°, and 300° respectively;

[0016] The illumination angles of the six tilted reference beams are 10°, 70°, 130°, 190°, 250°, and 310°, respectively.

[0017] Furthermore, six inclined object light beams pass through the sample to be measured. After that, when illuminated from one angle, the complex amplitude information of the sample on the CCD surface is:

[0018]

[0019] represents the complex amplitude information of the sample obtained by the nth inclined plane wave illumination transmitted to the CCD, is the nth object plane light wave field, x n With y n represents the nth object space coordinate, f is the focusing distance of the microscopic imaging subsystem, α is the angle between the parallel light and the X-axis, β is the angle between the parallel light and the Y-axis, λ is the illumination wavelength used, and ∏ is the circumference of a circle;

[0020] The angle between the nth reference beam and the optical axis is θ n When , the complex amplitude distribution of the reference light on the CCD is expressed as:

[0021] R n (x,y)=R0exp(jk sin θ n x)

[0022] These six object beams will form interference fringes with the corresponding reference beams on the CCD, and the interference field intensity collected by the computer is I(x,y);

[0023]

[0024] Where n = 1, 2, ..., 5, 6; n (x,y) represents the nth object light on the recording surface, I represents the conjugate of the nth object light on the recording surface; n (x n ,y n ) represents the interference field intensity formed by the nth object beam and the nth reference beam. These interference fields do not interfere with each other and are eventually collected and recorded by a computer.

[0025] Furthermore, the acquired holographic image is subjected to Fourier transform and then spectral filtering, and the Fourier transform formula is used to obtain the holographic image.

[0026]

[0027] Where u and v are the spatial frequencies in the x and y directions respectively;

[0028] A hologram contains all the information. After Fourier transforming the hologram, a pre-defined filter window is needed to correctly filter the required spectrum information. After extracting the correct spectrum, the spectrum is placed at the exact center of the spectrum, and then the super-resolution information is obtained by synthesizing the spectrum.

[0029] Using tilted plane wave illumination, this illumination method will cause the spectrum position to move by a distance of When the moving distance is equal to the cutoff frequency of the system, there is the greatest resolution improvement for the single-shot exposure system;

[0030]

[0031] d pi is the distance from the exit pupil position of the microscopic imaging system to the image, D is the exit pupil diameter of the microscopic imaging system,

[0032] α is the angle between the parallel light and the X-axis, and β is the angle between the parallel light and the Y-axis. When the above equation is satisfied, the single-shot exposure system can achieve maximum resolution improvement;

[0033] The system lighting mode is a circular distribution, and the resolution improvement in all directions is consistent, so when the spectrum is moved, the movement distance in all directions is the same.

[0034] Furthermore, 6 sub-spectra are obtained using a pre-defined filter window, and these 6 sub-spectra are synthesized into the final spectrum. The synthesized spectrum is represented as U(u,v), and then after inverse Fourier transformation, the complex amplitude information that exceeds the diffraction limit of the system is obtained:

[0035]

[0036] By analyzing the output complex amplitude O(x,y), we can obtain super-resolution information that exceeds the diffraction limit of the system.

[0037] Furthermore, the laser wavelength used is 532 nm (including but not limited to 532 nm, lasers of other wavelengths have the same results; the magnification of the microscope objective is 4, and the pixel size of the image collector is 3.45 um.

[0038] The present invention also provides a single-exposure super-resolution digital holographic microscopy method, which is applied to the single-exposure super-resolution digital holographic microscopy system, and the method comprises:

[0039] The single-exposure super-resolution digital holographic microscopy system divides a single light source beam into an object beam and a reference beam;

[0040] Calculate the cutoff frequency of the microscopic digital holographic system and obtain the corresponding tilt angle;

[0041] The illumination angles of the six object beams are 0°, 60°, 120°, 180°, 240°, and 300°;

[0042] The illumination angles of the six reference beams are 10°, 70°, 130°, 190°, 250°, and 310°;

[0043] The object beam and the reference beam are respectively split into six beams with different optical paths but consistent inclination angles with the optical axis using an illumination modulation subsystem;

[0044] The modulated six oblique object light beams are transmitted through the sample;

[0045] The microscopic imaging subsystem is used to magnify the image of the object and finally image it onto a charge coupled device;

[0046] The object beam passing through the sample passes through the microscopic imaging subsystem and is combined with the reference beam through a beam combiner to form a hologram on a charge-coupled device, which is finally collected and recorded by a computer.

[0047] The collected holographic image is Fourier transformed using a computer and the required spectrum is correctly extracted. After spectrum synthesis processing, super-resolution information of the sample amplitude and phase is finally obtained.

[0048] The beneficial effects of the present invention are:

[0049] 1. The device of the present invention uses an illumination modulation subsystem to modulate illumination light, thereby obtaining six inclined light beams, recording six mutually non-interfering holographic images at a time, and recording the information of the object being measured more quickly;

[0050] 2. The present invention adopts six directions of simultaneous recording, which greatly improves the ability of real-time observation and obtains full-field super-resolution information, which is not limited to horizontal or vertical, and improves the resolution ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A schematic diagram of the structure of a single-exposure super-resolution microscopic digital holographic system provided by an embodiment of the present invention;

[0052] Figure 2 A schematic diagram of a lighting subsystem provided by an embodiment of the present invention;

[0053] Figure 3 A schematic diagram of oblique light illumination provided by an embodiment of the present invention;

[0054] Figure 4 Schematic diagram of spectrum shift caused by tilted light;

[0055] Figure 5 It is a spectrum diagram obtained by Fourier transforming a single-exposure hologram using a computer;

[0056] Figure 6 Schematic diagram of spectrum synthesis;

[0057] Figure 7 Schematic diagram of the object under test (72-period Siemens star pattern) used in the simulation of this experiment;

[0058] Figure 8 Reconstruct amplitude images for diffraction-limited holography;

[0059] Fig. 9 Reconstruct phase images for diffraction-limited holography;

[0060] Fig.10 It is a holographic reconstructed amplitude image after spectrum synthesis in 6 directions;

[0061] Fig.11 It is a holographically reconstructed phase image after spectrum synthesis in 6 directions.

[0062] The numbers in the figure are: 1-solid laser, 2-beam splitter prism, 3-beam expander I, 4-lens I, 5-reflector I, 6-illumination modulator I, 7-tilt generator I, 8-measured object, 9-microscope objective, 10-reflector II, 11-beam expander II, 12-lens II, 13-illumination modulator II, 14-tilt generator II, 15-beam combiner, 16-image collector. DETAILED DESCRIPTION

[0063] Example 1: Figure 1-Figure 11 As shown, Figure 1 A schematic diagram of a single-exposure super-resolution microscopic digital holographic system, a single-exposure super-resolution microscopic digital holographic system and method, including an illumination modulation subsystem and a microscopic imaging subsystem;

[0064] The illumination modulation subsystem is used to divide the collimated light beam into six inclined light beams with different optical paths, and illuminate the object to be observed with the six inclined light beams with the same inclination angle and different optical paths. Both the object light path and the reference light path include the illumination modulation subsystem;

[0065] The illumination subsystem includes an illumination modulator I6, an illumination modulator II13 and a tilt generator I1, a tilt generator II14, and the microscopic imaging subsystem includes a microscopic objective lens 9; Figure 2 A schematic diagram of a lighting subsystem provided by an embodiment of the present invention;

[0066] The solid laser 1 emits a laser beam which is split by a coaxial beam splitter prism 2 into two beams of roughly equal energy, an object beam and a reference beam;

[0067] One of the beams passes through the beam expander I3 and the lens I4 to generate a parallel beam, which is reflected by the reflector I5 to the illumination modulator I6, and then propagates to the tilt generator I7 to generate 6 tilted beams with the same tilt angle as the optical axis but with an optical path difference. These 6 beams of light irradiate the object 8 to be measured, are magnified by the microscope objective 9, and then propagate to the image sensor 16 through the beam combiner 15, which is called object light;

[0068] Another beam passes through the reflector 10, and is collimated into a parallel beam by the beam expander 11 and the lens 12, and then passes through the illumination modulator 13 and the tilt generator 14 to become six tilted beams with the same tilt angle but with optical path difference, and passes through the beam combiner 15 to enter the image collector 16 as reference light. The six object beams and the six reference beams interfere with each other to produce interference fringes that do not interfere with each other. The interference fringes are collected by the image collector 16 and transmitted to the computer. The collected holographic image is Fourier transformed by the computer and the required spectrum is correctly extracted. After spectrum synthesis processing, the super-resolution information of the amplitude and phase of the sample is finally obtained.

[0069] The laser used in the above optical path is a solid-state laser with a wavelength of 532.8nm, and the image collector is a CCD (pixel size is 3.45um); the illumination modulator and the tilt generator generate six tilted light beams with the same angle as the optical axis but inconsistent optical path, which are used to expand the system numerical aperture in different directions, so that high-frequency information in multiple directions can enter the image sensor. Figure 3 A schematic diagram of oblique light illumination provided by an embodiment of the present invention;

[0070] The hologram is obtained by the above-mentioned single-exposure super-resolution microscopic digital holographic system, and the required spectrum is obtained by Fourier transform, and the spectrum is synthesized, and then the super-resolution complex amplitude information of the object under test is obtained by inverse Fourier transform. The system must meet the requirements of single exposure, and the interference fringes of multiple object lights must not interfere with each other, and the angles of the object light and the reference light must meet the following requirements;

[0071] Further, the illumination angles of the six inclined object light beams are 0°, 60°, 120°, 180°, 240°, and 300° respectively;

[0072] The illumination angles of the six tilted reference beams are 10°, 70°, 130°, 190°, 250°, and 310°, respectively.

[0073] Let six inclined object light beams with a certain angle pass through the sample to be tested After that, when illuminated from one angle, the complex amplitude information of the sample on the CCD surface is:

[0074]

[0075] represents the complex amplitude information of the sample obtained by the nth inclined plane wave illumination transmitted to the CCD, is the nth object plane light wave field, x n With y n represents the nth object space coordinate, f is the focusing distance of the microscopic imaging subsystem, α is the angle between the parallel light and the X-axis, β is the angle between the parallel light and the Y-axis, λ is the illumination wavelength used, and ∏ is the circumference of a circle;

[0076] The angle between the nth reference beam and the optical axis is θ n When , the complex amplitude distribution of the reference light on the CCD is expressed as:

[0077] R n (x,y)=R0exp(jk sin θ n x)

[0078] These six object beams will form interference fringes with the corresponding reference beams on the CCD, and the interference field intensity collected by the computer is I(x,y);

[0079]

[0080] Where n = 1, 2, ..., 5, 6; n (x,y) represents the nth object light on the recording surface, I represents the conjugate of the nth object light on the recording surface; n (x n ,y n ) represents the interference field intensity formed by the nth object beam and the nth reference beam. These interference fields do not interfere with each other and are eventually collected and recorded by a computer.

[0081] Furthermore, after the hologram is acquired by the image collector, the acquired hologram is subjected to Fourier transform to obtain a spectrum diagram, and then the spectrum is filtered to obtain the required spectrum. The Fourier transform formula is used

[0082]

[0083] Where u and v are the spatial frequencies in the x and y directions respectively; Figure 5 This is the spectrum diagram obtained by Fourier transforming a single-exposure hologram using a computer.

[0084] Using a single-exposure super-resolution microscopic digital holographic system, a hologram contains all the information. After the hologram is Fourier transformed, a pre-defined filter window is needed to correctly filter the required spectrum information. After the correct spectrum is extracted, the spectrum is placed at the exact center of the spectrum, and then the super-resolution information is obtained by synthesizing the spectrum.

[0085] Using tilted plane wave illumination, this illumination method will cause the spectrum position to shift. Figure 4 This is a schematic diagram of the spectrum movement caused by the tilted light of the present invention, and the moving distance is When the moving distance is equal to the cutoff frequency of the system, there is the greatest resolution improvement for the single-shot exposure system;

[0086]

[0087] d pi is the distance from the exit pupil position of the microscopic imaging system to the image, D is the exit pupil diameter of the microscopic imaging system,

[0088] α is the angle between the parallel light and the X-axis, and β is the angle between the parallel light and the Y-axis. When the above equation is satisfied, the single-shot exposure system can achieve maximum resolution improvement;

[0089] The system lighting mode is a circular distribution, and the resolution improvement in all directions is consistent, so when the spectrum is moved, the movement distance in all directions is the same.

[0090] Furthermore, 6 sub-spectra are obtained using a pre-defined filter window, and these 6 sub-spectra are synthesized into the final spectrum. The synthesized spectrum is represented as U(u,v), and then after inverse Fourier transformation, the complex amplitude information that exceeds the diffraction limit of the system is obtained:

[0091]

[0092] By analyzing the output complex amplitude o(x,y), we can obtain super-resolution information that exceeds the diffraction limit of the system. Figure 6 Schematic diagram of spectrum synthesis.

[0093] Furthermore, the laser wavelength used is 532 nm; the magnification of the microscope objective is 4, and the pixel size of the image collector is 3.45 um.

[0094] The present invention also provides a single-exposure super-resolution digital holographic microscopy method, which is applied to the single-exposure super-resolution digital holographic microscopy system, and the method comprises:

[0095] The single-exposure super-resolution digital holographic microscopy system divides a single light source beam into an object beam and a reference beam; Figure 7 Schematic diagram of the object under test (72-period Siemens star pattern) used in the simulation of this experiment;

[0096] Calculate the cutoff frequency of the microscopic digital holographic system and obtain the corresponding tilt angle;

[0097] The illumination angles of the six object beams are 0°, 60°, 120°, 180°, 240°, and 300°;

[0098] The illumination angles of the six reference beams are 10°, 70°, 130°, 190°, 250°, and 310°;

[0099] The object beam and the reference beam are respectively split into six beams with different optical paths but consistent inclination angles with the optical axis using an illumination modulation subsystem;

[0100] The modulated six oblique object light beams are transmitted through the sample;

[0101] The microscopic imaging subsystem is used to magnify the image of the object and finally image it onto a charge coupled device;

[0102] The object beam passing through the sample passes through the microscopic imaging subsystem and is combined with the reference beam through a beam combiner to form a hologram on a charge-coupled device, which is finally collected and recorded by a computer. Figure 8Reconstruct the amplitude image for diffraction limited holography, Fig. 9 Reconstruct phase images for diffraction-limited holography;

[0103] The collected holographic image is Fourier transformed by a computer and the required spectrum is correctly extracted. After spectrum synthesis processing, the super-resolution information of the amplitude and phase of the sample is finally obtained. Fig.10 It is a holographic reconstructed amplitude image after spectrum synthesis in 6 directions; Fig.11 It is a holographically reconstructed phase image after spectrum synthesis in 6 directions.

[0104] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A single-exposure super-resolution microscopic digital holographic system, characterized in that: It includes an illumination modulation subsystem and a microscopic imaging subsystem; The illumination modulation subsystem is used to divide the collimated light beam into six inclined light beams with different optical paths, and illuminate the object to be observed with the six inclined light beams with the same inclination angle and different optical paths. Both the object light path and the reference light path include the illumination modulation subsystem; The illumination subsystem comprises an illumination modulator I (6), an illumination modulator II (13) and a tilt generator I (1), a tilt generator II (14), and the microscopic imaging subsystem comprises a microscopic objective lens (9); The solid laser (1) emits a laser beam which passes through a beam splitter prism (2) to obtain an object light beam and a reference light beam; One of the beams passes through the beam expander I (3) and the lens I (4) to generate a parallel beam. This parallel beam is reflected by the reflector I (5) to the illumination modulator I (6), and then propagates to the tilt generator I (7) to generate 6 tilted beams with the same tilt angle as the optical axis. These 6 beams of light are transmitted through the object to be measured (8), magnified by the microscope objective (9), and then propagated to the image sensor (16) through the beam combiner (15), which is called object light. Another light beam passes through a reflector II (10), a beam expander II (11) and a lens II (12) to obtain a parallel light beam. The parallel light beam passes through an illumination modulator II (13) and a tilt generator II (14) to obtain six tilted light beams with the same tilt angle as the optical axis. These six tilted light beams pass through a beam combiner (15) and are transmitted to an image sensor (16), which are called reference light.

2. The single-exposure super-resolution microscopic digital holographic system according to claim 1, characterized in that: The illumination angles of the six inclined object beams are 0°, 60°, 120°, 180°, 240°, and 300°; The illumination angles of the six tilted reference beams are 10°, 70°, 130°, 190°, 250°, and 310°, respectively.

3. The single-exposure super-resolution microscopic digital holographic system according to claim 1, characterized in that: Six inclined object beams pass through the sample under test After that, when illuminated from one angle, the complex amplitude information of the sample on the CCD surface is: represents the complex amplitude information of the sample obtained by the nth inclined plane wave illumination transmitted to the CCD, is the nth object plane light wave field, x n With y n represents the nth object space coordinate, f is the focusing distance of the microscopic imaging subsystem, α is the angle between the parallel light and the X-axis, β is the angle between the parallel light and the Y-axis, λ is the illumination wavelength used, and ∏ is the circumference of a circle; The angle between the nth reference beam and the optical axis is θ n When , the complex amplitude distribution of the reference light on the CCD is expressed as: R n (x,y)=R0exp(jk sinθ n x) These six object beams will form interference fringes with the corresponding reference beams on the CCD, and the interference field intensity collected by the computer is I(x,y); Where n = 1, 2, ..., 5, 6; n (x,y) represents the nth object light on the recording surface, I represents the conjugate of the nth object light on the recording surface; n (x n ,y n ) represents the interference field intensity formed by the nth object beam and the nth reference beam. These interference fields do not interfere with each other and are eventually collected and recorded by a computer.

4. The single-exposure super-resolution microscopic digital holographic system according to claim 1, characterized in that: The acquired holographic image is subjected to Fourier transform, and then spectral filtering is performed. The Fourier transform formula is used to Where u and v are the spatial frequencies in the x and y directions respectively; A hologram contains all the information. After Fourier transforming the hologram, a pre-defined filter window is needed to correctly filter the required spectrum information. After extracting the correct spectrum, the spectrum is placed at the exact center of the spectrum, and then the super-resolution information is obtained by synthesizing the spectrum. Using tilted plane wave illumination, this illumination method will cause the spectrum position to move by a distance of When the moving distance is equal to the cutoff frequency of the system, there is the greatest resolution improvement for the single-shot exposure system; d pi is the distance from the exit pupil position of the microscopic imaging system to the image, D is the exit pupil diameter of the microscopic imaging system, α is the angle between the parallel light and the X-axis, and β is the angle between the parallel light and the Y-axis. When the above equation is satisfied, the single-shot exposure system can achieve maximum resolution improvement; The system lighting mode is a ring distribution, and the resolution improvement in all directions is consistent, so when the spectrum is moved, the movement distance in all directions is the same.

5. The single-exposure super-resolution microscopic digital holographic system according to claim 1, characterized in that: Using a pre-defined filter window, we get six sub-spectra, which are synthesized into the final spectrum. The synthesized spectrum is represented as u(u,v), and then after inverse Fourier transform, we get the complex amplitude information that exceeds the diffraction limit of the system: By analyzing the output complex amplitude O(x,y), we can obtain super-resolution information that exceeds the diffraction limit of the system.

6. The single-exposure super-resolution microscopic digital holographic system according to claim 1, characterized in that: The laser wavelength used is 532nm; the magnification of the microscope objective is 4, and the pixel size of the image collector is 3.45um.

7. A single-exposure super-resolution digital holographic microscopy method, characterized in that: The single-exposure super-resolution digital holographic microscopy system applied to any one of claims 1 to 6, the method comprising: The single-exposure super-resolution digital holographic microscopy system divides a single light source beam into an object beam and a reference beam; Calculate the cutoff frequency of the microscopic digital holographic system and obtain the corresponding tilt angle; The illumination angles of the six object beams are 0°, 60°, 120°, 180°, 240°, and 300°; The illumination angles of the six reference beams are 10°, 70°, 130°, 190°, 250°, and 310°; The object beam and the reference beam are respectively split into six beams with different optical paths but consistent inclination angles with the optical axis using an illumination modulation subsystem; The modulated six oblique object light beams are transmitted through the sample; The microscopic imaging subsystem is used to magnify the image of the object and finally image it onto a charge coupled device; The object beam passing through the sample passes through the microscopic imaging subsystem and is combined with the reference beam through a beam combiner to form a hologram on a charge-coupled device, which is finally collected and recorded by a computer. The collected holographic image is Fourier transformed using a computer and the required spectrum is correctly extracted. After spectrum synthesis processing, super-resolution information of the sample amplitude and phase is finally obtained.

Images