A visible light dual optical comb high-resolution ultrafast microscopic imaging device and method

Abstract

This invention discloses a high-resolution ultrafast visible light dual-comb microscopy imaging device and method. The imaging device includes a dual-comb light source, a frequency shifter, a wavelength division multiplexer, a two-dimensional dispersive element, a microscopy imaging system, a dual-comb detector, and a data acquisition and processing section. A dual-comb is used as the light source. The two-dimensional dispersive element expands the optical frequency comb into a wavelength-space-coded lattice light field for illumination. A dual-comb detector performs dual-comb spectral measurements to obtain information contained in the wavelengths. The frequency shifter changes the optical frequency to achieve structured light illumination, thus realizing high-resolution ultrafast microscopy imaging. This invention overcomes the limitations of time-domain stretching in traditional ultrafast measurement techniques on visible light ultrafast microscopy imaging, effectively reducing the spot size of the illumination beam and improving the spatial resolution of the imaging. Utilizing an optical frequency comb to achieve label-free ultra-resolution microscopy imaging with lattice structured light illumination can further improve the resolution of ultrafast microscopy imaging.

Description

Technical Field

[0001] This invention relates to the fields of microscopic imaging and ultrafast lasers, specifically to a microscopic imaging device that uses two visible light optical frequency combs with a certain repetition frequency difference for illumination, and a method for achieving high-resolution microscopic imaging using dual optical combs. Background Technology

[0002] The invention of the microscope opened the door to observing the microscopic world. Every advancement in microscopic imaging technology has propelled the rapid development of materials science, medicine, and life sciences. Compared to other types of microscopes, optical microscopes offer advantages such as non-contact operation, minimal damage, and a rich array of imaging mechanisms, making them an indispensable tool in many research and application fields. Improving the spatial resolution of microscopic imaging has always been the main focus of optical microscopy development. In recent decades, super-resolution microscopy has made significant progress, giving rise to a series of techniques such as stimulated emission depletion microscopy (STED), ground state depletion microscopy (GSD), photoactivated localization microscopy (PALM), stochastic optical reconstruction microscopy (STORM), Fourier layered microscopy (FPM), and structured illumination microscopy (SIM). These techniques have already broken through the optical diffraction limit in terms of spatial resolution, achieving spatial resolution capabilities of 10–100 nm, and have been widely applied in cutting-edge research in biology, medicine, and materials science.

[0003] Improving the temporal resolution of imaging is becoming increasingly important in microscopy. When studying objects at the micrometer to nanometer scale, even slow-moving phenomena require very high temporal resolution for capture. For example, when observing a slowly moving object (v = 1 m / s), a spatial imaging resolution of 1 μm requires a high temporal resolution of 1 μs, corresponding to an imaging frame rate of 1 Mfps. Such phenomena are widespread in fields such as photochemistry, plasma physics, microfluidic biotechnology, semiconductor physics, shockwave therapy, and neuroscience. Therefore, improving both spatial and temporal resolution (imaging speed) is a core issue in microscopic imaging research. Currently, there are very few studies combining dual-optical-comb techniques with microscopic imaging. Reported works have utilized infrared optical frequency combs, significantly improving the speed of microscopic imaging, but without significant improvement in spatial resolution. There are currently no reports on high-resolution ultrafast microscopic imaging based on optical frequency combs. Summary of the Invention

[0004] The purpose of this invention is to address the contradiction between imaging speed and spatial resolution in existing microscopic imaging technologies by proposing a visible light dual-comb microscopic imaging system and method. This method combines optical frequency combs with microscopic imaging, utilizing dual-comb spectroscopy to achieve high-precision spectral measurements in visible light ultrafast microscopic imaging, which can significantly improve the spatial resolution of the imaging. Furthermore, it proposes to shift the phase of the wavelength encoding lattice by frequency shifting the optical frequency comb, and to illuminate the sample from different angles using wavelength and polarization multiplexing, thereby achieving structured light illumination of the optical frequency comb lattice in ultrafast microscopic imaging and realizing microscopic imaging with high temporal and spatial resolution.

[0005] The objective of this invention is achieved through the following technical solution: a visible light dual-comb high-resolution ultrafast microscopic imaging device, characterized in that: the imaging device includes a laser source, an acousto-optic frequency shifter, a wavelength division multiplexer, a two-dimensional dispersion-space unfolding element, a microscopic imaging system, a dual-comb detection device, and a data acquisition and processing device.

[0006] The laser source employs a dual optical comb. The two-dimensional dispersion-space unfolding element is used to unfold the optical frequency comb into a wavelength-space encoded dot matrix light field for illumination. The dual optical comb detection device is used to perform dual optical comb spectral measurements to obtain information contained in the wavelength. The acousto-optic frequency shifter is used to change the optical frequency to achieve structured light illumination. The wavelength division multiplexer is used to achieve multi-angle structured light illumination and realize high-resolution ultrafast microscopic imaging. The data acquisition and processing device is used to obtain high-resolution images.

[0007] The laser source has two visible light frequency combs, serving as signal source L1 and reference source L2, respectively. Signal source L1 enters an acousto-optic frequency shifter, and then is divided into three paths, L1-1, L1-2, and L1-3, by a wavelength division multiplexer. Each path passes through a two-dimensional dispersion-spatial unrolling element with different angles, unfolding into a two-dimensional wavelength-spatial encoded dot matrix illumination field with different angular distributions. After collinear beam combining using a wavelength division multiplexer, the beam is used to illuminate the sample through a microscopic imaging system. The signal light carrying sample information is first converted into a point beam by the two-dimensional dispersion-spatial unrolling element, then combined with the reference light L2, and input into a dual-comb detection device for dual-comb spectral measurement. Finally, a microscopic image with higher temporal and spatial resolution is obtained through a data acquisition and processing device.

[0008] Furthermore, the sample can be reflected to convert the two-dimensional wavelength-space encoded dot matrix illumination field back into a point beam, or the sample can be transmitted to convert the transmitted two-dimensional illumination field into a point beam using another wavelength division multiplexer, a microscopic imaging system, and a two-dimensional dispersion-space unfolding element.

[0009] Furthermore, the laser source is two visible light optical frequency comb sources with a fixed repetition frequency difference. The wavelength is in the visible light band and is achieved by methods such as active reference locking of optical frequency combs, laser resonator multiplexing, microcavity frequency combs, electro-optic frequency combs, and frequency doubling. The repetition frequency and repetition frequency difference of the optical frequency comb sources are selected according to the imaging field size and speed.

[0010] Furthermore, the acousto-optic frequency shifter is composed of an acousto-optic crystal and uses an acousto-optic frequency shifting method to shift the frequency of the optical frequency comb light source. Its operating wavelength range is matched with the wavelength of the laser source used, and the acousto-optic frequency shifting amount is less than the repetition frequency of the optical frequency comb light source.

[0011] Furthermore, the wavelength division multiplexer is used to divide the signal light frequency into three paths, which is achieved by using a dichroic mirror and a reflector with different filtering characteristics.

[0012] Furthermore, the two-dimensional dispersion-space unwrapping element is composed of a cylindrical lens, a virtual imaging phase array, and a grating. The light beam is focused by the cylindrical lens and incident on the virtual imaging phase array, where it is unwrapped in one dimension. Then, it is incident on the grating and unwrapped into a two-dimensional dot array, with each dot corresponding to a different wavelength. It is also used to combine the two-dimensional illumination dot array into a pulse. The spectral freedom range of the virtual imaging phase array is matched with the bandwidth and repetition rate of the optical frequency comb used.

[0013] Furthermore, the microscopic imaging system consists of a beam shaping module and a microscopic imaging objective. The beam shaping module is used to optimize and expand the illumination light field, and the microscopic imaging objective is used to focus the light field onto the sample so that the spot size is close to the diffraction limit.

[0014] Furthermore, the dual-comb detection device is used to acquire the dual-comb beat frequency signal for dual-comb measurement, and employs a balanced photodetector, an avalanche photodetector, or a high-speed photodetector.

[0015] Furthermore, the data acquisition and processing device is used for acquiring photoelectric signal data, image reconstruction, and display.

[0016] The present invention also provides a high-resolution ultrafast microscopic imaging method based on the aforementioned microscopic imaging device using a visible light dual-comb microscope, the method comprising the following steps:

[0017] (1) Two visible light optical frequency combs are used as laser sources, namely signal source L1 and reference source L2. Signal source L1 enters the acousto-optic frequency shifter, and radio frequency signals are loaded on the acousto-optic frequency shifter, so that the comb teeth of the optical frequency comb are frequency shifted, thus realizing structured light illumination.

[0018] (3) Signal source L1 is divided into three paths L1-1, L1-2 and L1-3 by wavelength division multiplexer. They are then expanded into two-dimensional wavelength-space coded dot matrix illumination light fields with different angle distributions by two-dimensional dispersion-space expansion elements with different angles. The illumination light field illuminates the sample after passing through the microscopic imaging system. The light field transmitted, reflected or diffracted by the sample is converged and received, and then restored into a single-point beam pulse signal by two-dimensional dispersion-space expansion elements. The sample information at the corresponding position is obtained by illuminating each point on the sample.

[0019] (4) After collinear beam combining using a wavelength division multiplexer, the beam is combined with the reference light L2 and input into a dual-comb detector to perform dual-comb spectral measurement. Alternatively, L2 is split into three paths and combined with L1-1, L1-2 and L1-3 respectively, and then input into a dual-comb detector to perform dual-comb spectral measurement to obtain the intensity and phase information of the wavelength of the signal source L1. The accuracy is sufficient to distinguish the wavelength corresponding to each illumination point. Finally, a microscopic image with higher time and space resolution is obtained through a data acquisition and processing device.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention utilizes a dual-comb spectral measurement method to achieve high-precision spectral measurement in the visible light band, overcoming the limitation of time-domain stretching on visible light ultrafast microscopic imaging in traditional ultrafast measurement techniques.

[0022] 2. This invention utilizes visible light ultrashort pulse lasers to achieve ultrafast microscopic imaging, which can effectively reduce the spot size of the illumination beam and improve the spatial resolution of the imaging.

[0023] 3. This invention utilizes an optical frequency comb to achieve a markless super-resolution microscopy imaging with lattice structured light illumination, which can further improve the resolution of ultrafast microscopy imaging.

[0024] 4. This invention combines single-point detection ultrafast microscopy with optical frequency comb research to overcome the contradiction between imaging speed and spatial resolution, and can achieve super-resolution microscopy with an imaging rate of up to MHz. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the light field modulation part and the microscopic imaging part in this invention;

[0027] Figure 3 This is a schematic diagram illustrating the return signal light modulation, dual-comb detection, data acquisition, and processing in this invention;

[0028] Figure 4This is a schematic diagram of the three-path spectral detection structure for the returned signal light in this invention;

[0029] Figure 5 This is a schematic diagram of the two-dimensional dispersion-space expansion element in this invention.

[0030] In the figure, 1—laser source; 2—beam characteristic control device; 3—microscopic imaging system; 4—dual-comb detection device; 5—data acquisition and processing device; 6—acoustic-optic frequency shifter; 7—dichroic mirror; 8—two-dimensional dispersion-spatial unfolding element; 9—mirror; 10—beam shaping module; 11—microscopic imaging objective; 12—sample; 13—photodetector; 14—analog-to-digital converter; 15—data and image processing module; 16—display; 17—semi-transparent mirror; 18—polarization beam combiner; 19—cylindrical lens; 20—virtual imaging phase array; 21—grating. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0032] like Figure 1 As shown, this invention provides a visible light dual-comb high-resolution ultrafast microscopic imaging device, comprising five parts: a laser source 1, a beam characteristic control device 2, a microscopic imaging system 3, a dual-comb detection device 4, and a data acquisition and processing device 5. The laser source 1 is a dual-comb source, with the repetition frequency of the two optical frequency combs being approximately 10 GHz, and the repetition frequency difference adjustable within the range of 10 kHz to 10 MHz. The laser source consists of two visible light optical frequency combs with a fixed repetition frequency difference, using the visible light band. This is achieved through methods such as active reference locking of the optical frequency combs, laser resonant cavity multiplexing, microcavity frequency combs, electro-optic frequency combs, and frequency doubling. The repetition frequency and repetition frequency difference of the optical frequency comb sources are selected based on the imaging field of view and speed. The signal light L1 output by the laser source 1 first passes through the beam characteristic control device 2 to expand the time-domain pulse into a two-dimensional space. Then, it illuminates the sample through the microscopic imaging system 3, which can use either transmission or reflection. The signal light carrying sample information is restored to a time-domain pulse by the beam characteristic control device 2, and the signal light L1 and reference light L2 are combined before entering the dual-comb detection device 4. After passing through the data acquisition and processing device 5, a microscopic image is obtained. The dual-comb detection device is used to acquire the dual-comb beat frequency signal for dual-comb measurement, and employs a balanced photodetector, avalanche photodetector, or high-speed photodetector. The sample can be reflected, converting the two-dimensional wavelength-space encoded dot matrix illumination field back into a point beam, or the sample can be transmitted, using another wavelength division multiplexer, microscopic imaging system, and two-dimensional dispersion-space expansion element to convert the transmitted two-dimensional illumination field into a point beam.

[0033] like Figure 2As shown, the acousto-optic frequency shifter 6 is composed of an acousto-optic crystal and uses an acousto-optic frequency shifting method to shift the frequency of the optical frequency comb light source. Its operating wavelength range matches the wavelength of the laser source used, and the acousto-optic frequency shifting amount is less than the repetition frequency of the optical frequency comb light source. The signal light L1 first passes through the acousto-optic frequency shifter 6 in the beam characteristic control device 2. An radio frequency signal is loaded onto the acousto-optic frequency shifter 6, causing the comb teeth of the optical frequency comb to shift, resulting in a change in the phase of the lattice illuminating the sample, thereby realizing structured light illumination. Then, the signal light L1 is split into three paths using a dichroic mirror 7 and a reflector 9. Each path passes through a two-dimensional dispersion-space unfolding element 8. The three two-dimensional dispersion-space unfolding elements 8 are placed at different angles, and the unfolded two-dimensional lattice light fields have different distribution angles. Finally, the three signal lights are collinearly combined by the dichroic mirror 7 and the reflector 9. The delay of the three signal lights is less than the pulse interval of the signal lights. Then, the combined signal light enters the beam shaping module 10 to shape and collimate the two-dimensional lattice light field, and is then focused to the diffraction limit of the beam by the microscope imaging objective 11, illuminating the sample 12. The wavelength of the laser source 1 is 780nm, and the diffraction limit of its illumination spot is less than 600nm, which is the spatial resolution of the imaging. If a shorter wavelength light source is used, the imaging resolution can be further improved.

[0034] The transmitted or reflected signal light carries sample information, and its beam characteristics control and detection process are as follows: Figure 3 As shown. The three signal beams are separated using a dichroic mirror 7 and a reflecting mirror 9, and then recovered into time-domain pulses by two-dimensional dispersion-spatial unrolling elements 8 placed at different angles. The three pulses are then combined using the dichroic mirror 7 and the reflecting mirror 9. This process can be achieved by returning the signal beam along its original path to recover the time-domain signal, or by using the same beam characteristic control device 2 and microscopic imaging system 3. Sample information is acquired at each point on the sample by illuminating it. This information is measured by the intensity and phase of the wavelength of the signal source L1 corresponding to that position. The accuracy is sufficient to distinguish the wavelength corresponding to each comb tooth, thus achieving a single measurement of the sample. The measurement speed reaches millions of frames per second, depending on the repetition frequency of the optical comb and the repetition rate difference between the two optical combs. For example... Figure 1 As shown in the diagram, the signal light L1 and reference light L2 are combined using a polarization beam combiner 18, converted into an electrical signal by a photodetector 13, and digitally sampled by an analog-to-digital converter 14. The operating bandwidth of the analog-to-digital converter 14 should be matched with the repetition rate and repetition rate difference of the dual optical comb used. The acquired data is processed and the image is restored using a data and image processing module 15, and finally output to a display 16. The speed of the dual optical comb spectral measurement method is limited by the frequency difference between the two optical frequency combs, which is set to about 1 MHz here, thus achieving an imaging speed on the order of MHz. By processing the three-path illumination imaging, label-free illumination super-resolution imaging of the sample structure can be achieved, and its imaging spatial resolution can break through the diffraction limit.

[0035] The above-mentioned beam characteristic control and detection process can also adopt another approach, such as... Figure 4 As shown. The reference light L2 is split into three paths by the semi-transparent mirror 17 and the reflector 9. The three paths are then combined with the polarization beam splitter 18 and input into the photodetector 13 to be converted into electrical signals. The subsequent process is the same as the above process.

[0036] This invention employs a two-dimensional dispersion-space expansion element 8, such as... Figure 5 As shown, it consists of a cylindrical lens 19, a virtual imaging phase array 20, and a grating 21. The light beam is focused by the cylindrical lens 19 and incident on the virtual imaging phase array 20, where it is expanded in one dimension. The light beam is then re-incidentally incident on the grating 21 and expanded into a two-dimensional dot matrix.

[0037] The present invention also provides a high-resolution ultrafast microscopic imaging method based on the aforementioned microscopic imaging device using a visible light dual-comb microscope, the method comprising the following steps:

[0038] (1) Two visible light optical frequency combs are used as laser sources, namely signal source L1 and reference source L2. Signal source L1 enters the acousto-optic frequency shifter, and radio frequency signals are loaded on the acousto-optic frequency shifter, so that the comb teeth of the optical frequency comb are frequency shifted, thus realizing structured light illumination.

[0039] (3) Signal source L1 is divided into three paths L1-1, L1-2 and L1-3 by wavelength division multiplexer. They are then expanded into two-dimensional wavelength-space coded dot matrix illumination light fields with different angle distributions by two-dimensional dispersion-space expansion elements with different angles. The illumination light field illuminates the sample after passing through the microscopic imaging system. The light field transmitted, reflected or diffracted by the sample is converged and received, and then restored into a single-point beam pulse signal by two-dimensional dispersion-space expansion elements. The sample information at the corresponding position is obtained by illuminating each point on the sample.

[0040] (4) After collinear beam combining using a wavelength division multiplexer, the beam is combined with the reference light L2 and input into a dual-comb detector to perform dual-comb spectral measurement. Alternatively, L2 is split into three paths and combined with L1-1, L1-2 and L1-3 respectively, and then input into a dual-comb detector to perform dual-comb spectral measurement to obtain the intensity and phase information of the wavelength of the signal source L1. The accuracy is sufficient to distinguish the wavelength corresponding to each illumination point. Finally, a microscopic image with higher time and space resolution is obtained through a data acquisition and processing device.

[0041] The above embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A high-resolution ultrafast visible light dual-comb microscopic imaging device, characterized in that: The imaging device includes a laser light source (1), an acousto-optic frequency shifter (6), a wavelength division multiplexer, a two-dimensional dispersion-space unfolding element (8), a microscopic imaging system (3), a dual-comb detection device (4), and a data acquisition and processing device (5). The laser source (1) uses a dual optical comb. The two-dimensional dispersion-space unfolding element (8) is composed of a cylindrical lens (19), a virtual imaging phase array (20), and a grating (21). The beam is focused by the cylindrical lens (19) and incident on the virtual imaging phase array (20). The beam is unfolded in one dimension and then incident on the grating (21) to unfold into a two-dimensional dot matrix. Each dot corresponds to a different wavelength and is also used to combine the two-dimensional illumination dot matrix into a pulse. The spectral freedom range of the virtual imaging phase array (20) is matched with the bandwidth and repetition rate of the optical frequency comb used. The two-dimensional dispersion-space unfolding element (8) is used to unfold the optical frequency comb into a wavelength-space encoded dot matrix light field for illumination. The dual optical comb detection device (4) is used to carry out dual optical comb spectral measurement to obtain the information contained in the wavelength. The acousto-optic frequency shifter (6) is used to change the optical frequency to realize structured light illumination. The wavelength division multiplexer is used to realize multi-angle structured light illumination and realize high-resolution ultrafast microscopic imaging. The data acquisition and processing device (5) is used to obtain high-resolution images. The laser source (1) has two visible light frequency comb sources, which serve as signal source L1 and reference source L2, respectively. The signal source L1 enters the acousto-optic frequency shifter (6), and then is divided into three paths L1-1, L1-2 and L1-3 by the wavelength division multiplexer. They pass through two-dimensional dispersion-space expansion elements (8) with different angles, and are expanded into two-dimensional wavelength-space encoded dot matrix illumination light fields with different angle distributions. After collinear beam combining by the wavelength division multiplexer, the light is used to illuminate the sample by the microscopic imaging system (3). The signal light carrying the sample information is first converted into a point beam by the two-dimensional dispersion-space expansion element (8), and then combined with the reference light L2. It is input into the dual-comb detection device (4) to carry out dual-comb spectral measurement. Finally, it is processed by the data acquisition and processing device (5) to obtain a microscopic image with higher time and space resolution.

2. The visible light dual-comb high-resolution ultrafast microscopic imaging device according to claim 1, characterized in that: The sample can be reflected to convert the two-dimensional wavelength-space encoded dot matrix illumination field back into a point beam, or the sample can be transmitted to convert the transmitted two-dimensional illumination field into a point beam using another wavelength division multiplexer, a microscopic imaging system (3) and a two-dimensional dispersion-space unfolding element (8).

3. The visible light dual-comb high-resolution ultrafast microscopic imaging device according to claim 1, characterized in that: The laser source (1) consists of two visible light optical frequency combs with a fixed repetition frequency difference. The wavelength is in the visible light band and is achieved by methods such as active reference locking of optical frequency combs, laser resonator multiplexing, microcavity frequency combs, electro-optic frequency combs, and frequency doubling. The repetition frequency and repetition frequency difference of the optical frequency comb source are selected according to the field size and speed of imaging.

4. The visible light dual-comb high-resolution ultrafast microscopic imaging device according to claim 1, characterized in that: The acousto-optic frequency shifter (6) is composed of an acousto-optic crystal and uses the acousto-optic frequency shifting method to shift the frequency of the optical frequency comb light source. Its operating wavelength range is matched with the wavelength of the laser source used, and the acousto-optic frequency shifting amount is less than the repetition frequency of the optical frequency comb light source.

5. The visible light dual-comb high-resolution ultrafast microscopic imaging device according to claim 1, characterized in that: The wavelength division multiplexer is used to divide the signal light frequency into three paths, which is achieved by using a dichroic mirror and a reflector with different filtering characteristics.

6. The visible light dual-comb high-resolution ultrafast microscopic imaging device according to claim 1, characterized in that: The microscopic imaging system consists of a beam shaping module (10) and a microscopic imaging objective (11). The beam shaping module (10) is used to optimize and expand the illumination field, and the microscopic imaging objective (11) is used to focus the light field onto the sample so that the spot size is close to the diffraction limit.

7. The visible light dual-comb high-resolution ultrafast microscopic imaging device according to claim 1, characterized in that: The dual-comb detection device (4) is used to acquire the dual-comb beat frequency signal and perform dual-comb measurement. It employs a balanced photodetector, an avalanche photodetector, or a high-speed photodetector.

8. The visible light dual-comb high-resolution ultrafast microscopic imaging device according to claim 1, characterized in that: The data acquisition and processing device is used for acquiring photoelectric signal data, image reconstruction, and display.

9. A high-resolution ultrafast microscopic imaging method using a visible light dual-comb microscope based on the microscopic imaging device of claim 1, characterized in that: The method includes the following steps: (1) Two visible light optical frequency combs are used as laser light sources (1), namely signal source L1 and reference source L2; signal source L1 enters the acousto-optic frequency shifter (6), and radio frequency signals are loaded on the acousto-optic frequency shifter (6), so that the comb teeth of the optical frequency comb will generate frequency shift, thus realizing structured light illumination; (3) Signal source L1 is divided into three paths L1-1, L1-2 and L1-3 by wavelength division multiplexer. They are respectively passed through two-dimensional dispersion-space expansion element (8) with different angles and expanded into two-dimensional wavelength-space encoded dot matrix illumination light fields with different angle distributions. After the illumination light field passes through the microscopic imaging system (3), it illuminates the sample. After the light field transmitted, reflected or diffracted by the sample is converged and received, it is restored into a single-point beam pulse signal by two-dimensional dispersion-space expansion element. The sample information at the corresponding position is obtained by illuminating each point on the sample. (4) After collinear beam combining using a wavelength division multiplexer, the beam is combined with the reference light L2 and input into the dual-comb detector to carry out dual-comb spectral measurement. Alternatively, L2 is split into three paths and combined with L1-1, L1-2 and L1-3 respectively, and then input into the dual-comb detector to carry out dual-comb spectral measurement to obtain the intensity and phase information of the wavelength of the signal source L1. Its accuracy is sufficient to distinguish the wavelength corresponding to each illumination point. Finally, after data acquisition and processing device (5), a microscopic image with higher time and space resolution is obtained.

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