Super-resolution imaging method and device based on quantum correlated photons

Abstract

The application discloses a kind of super-resolution imaging method and device based on quantum correlation photon parallel collection, the present application uses optical beam splitter to divide the fluorescence detected in microscope into two beams again into parallel detection system, two-way parallel detection can realize more efficient collection to fluorescence correlation photon pair after correction alignment, to reach better image quality.Compared with single parallel detection light path, the present application is used in quantum dot and solid defect with single-photon source characteristics;The present application can realize resolution improvement without improving laser power by using simple beam splitting second-order correlation measurement.Compared with existing quantum correlation imaging technology, the two-way parallel collection mode designed in the present application can perform coincidence measurement in space-time, and more coincidence photon information is retained, the imaging time is shortened, which can be applied in different super-resolution light paths, and the application range of quantum correlation photon detection technology is widened.

Description

Technical Field

[0001] This invention belongs to the field of optics and relates to a quantum correlated photon collection optical path and a correlated imaging scheme for optical super-resolution imaging, and particularly to a super-resolution imaging method and device based on parallel collection of quantum correlated photons. Background Technology

[0002] Due to optical diffraction, the resolution of far-field optical microscopy is limited to Δr = 0.61λ / NA, where λ is the wavelength of light and NA is the numerical aperture of the objective lens. The advent of super-resolution optical microscopy has enabled us to further explore microscopic systems, promoting the development of biomedicine. The most representative super-resolution imaging techniques in recent years include stimulated emission depletion microscopy, structured light illumination microscopy, random optical reconstruction super-resolution microscopy, and quantum correlation super-resolution microscopy.

[0003] Quantum correlation imaging (QCI) is a novel imaging technique that utilizes the High-Order Photon Correlation (HBT) scheme to collect second-order and even higher-order photon correlation information, and then achieves super-resolution images by stripping away this higher-order information. Compared to other super-resolution imaging techniques, this technique does not rely on increased light intensity or complex optical modulation; it only utilizes the intrinsic optical properties of the fluorescent dots and can be well integrated with other techniques to achieve higher imaging resolution. However, common quantum correlation imaging optical paths typically only correlate photons in time or space, and the collection of higher-order photons is extremely time-consuming, making this technique difficult to apply in practical biological imaging. Summary of the Invention

[0004] In view of this, the present invention provides a super-resolution imaging method based on parallel collection of quantum-correlated photons, combining a photon collection optical path for spatiotemporal quantum correlation imaging, photon correlation information extraction, and a quantum-correlation-based super-resolution optical imaging scheme, aiming to at least partially solve the aforementioned technical problems. Compared with traditional photon collection schemes, the present invention can achieve higher resolution. This represents a several-fold improvement and can be extended to other point-scan-based super-resolution imaging systems.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] According to a first aspect of this specification, a super-resolution imaging method based on parallel collection of quantum correlated photons is provided, the method comprising the following steps:

[0007] (1) After the fluorescence passes through the 50:50 optical beam splitter, the two beams are collected by the lens and enter their respective optical fiber bundles. The two optical fiber bundles have the same structure.

[0008] (2) Each fiber in each channel is connected to the same single-photon detector and connected to different channels of the time-correlated single-photon counter (TCSPC). The TCSPC is used to collect photon time-domain data of each channel.

[0009] (3) Correct the fiber positions corresponding to the two beams so that the conjugate positions of the fiber channels on the sample surface correspond one-to-one.

[0010] (4) Second-order correlation measurement is performed on the two photon time-domain data of the corresponding fiber channel to determine the time delay of the two beams;

[0011] (5) After the delay is determined, the time window is set by the second-order correlation function of the fluorescence point, and the correlated photon pairs within the time window are collected;

[0012] (6) For each pixel scanned by the microscope, the total number of photons arriving at the TCSPC from each pair of corresponding fiber channels is collected as the first-order photon number, and the associated photon pairs within the time window are collected as the second-order photon number; the first-order photon image group and the second-order photon image group of all corresponding fiber channels are obtained by scanning, and the final first-order photon image and the second-order photon image are obtained by photon recombination method.

[0013] (7) A higher resolution image is reconstructed from the first-order photon image and the second-order photon image.

[0014] Furthermore, in step (1), the optical beam splitter is a 50:50 non-polarized cubic crystal beam splitter. By building a 4f lens system to select a suitable Airy disk size, the two beams are coupled into the corresponding fiber bundle.

[0015] Furthermore, in step (2), the single-photon detector used must have a dark count of <50 photos per second for weak photon detection, and the TSCPC has a time resolution of ps.

[0016] Furthermore, in step (2), the optical fiber of each channel is connected to the same avalanche diode single-photon detector and connected to different channels of TCSPC.

[0017] Furthermore, in step (3), the spatial light modulator / phase delay plate in the excitation optical path modulates the aberration to correct the rotation angle of the two fiber bundles, so as to achieve the position alignment of the corresponding fiber channels.

[0018] Furthermore, in step (4), the TCSPC records the arrival time of the two photons in the corresponding optical fiber channel. If the photon in channel 1 arrives and the photon in channel 2 is also collected within a set threshold time, it is considered that a pair of photons has been successfully collected, and this is used as the number of second-order correlated photons.

[0019] Furthermore, in step (5), the counting time window τ is set by the second-order correlation function of the corresponding fiber channel. d At this point, the required contrast can be achieved and a sufficient number of photons can be detected; collection The number of photon pairs within the window.

[0020] Further, in step (6), the photon recombination method specifically involves: determining the offset of all images in the obtained first-order photon image group through cross-correlation, and obtaining a first-order photon image by displacement superposition; determining the offset of all images in the obtained second-order photon image group through cross-correlation, and obtaining a second-order photon image by displacement superposition.

[0021] Furthermore, in step (7), considering that M single-photon sources are located on the same object plane, the first-order photon image G (1) The reconstruction of (x) is achieved by photon recombination from K detectors, i.e. Where x is the excitation light scanning position. For the first-order light intensity distribution obtained by detector α, x i Let h(·) be the position of each single-photon source, and h(·) be the optical transfer function. The image plane position of the detector; similarly, the second-order photon image G (2) (x) Intensity distribution of photon pairs obtained from K pairs of detectors Photon recombination is used to obtain the image; the recombination method is the same as that of the first-order image. Finally, the first-order and second-order images are subtracted by ΔG. (2) (x)=G (1) (x)·G (1) (x)-ηG (2) (x) can obtain a higher resolution final image, where η is the ratio of the photon pair measurement time window to the single-pixel photon collection time.

[0022] According to a second aspect of this specification, a super-resolution imaging device for parallel collection of quantum correlated photons is provided, the device comprising a 50:50 optical beam splitter, a first collecting lens, a first fiber bundle and detector array, a second collecting lens, a second fiber bundle and detector array, a time-correlated single-photon counter, and a computer.

[0023] The fluorescence generated by the sample is split into two beams by a 50:50 optical beam splitter. The first beam passes through the first collecting lens and the first fiber bundle and the detector array to generate an electrical signal input time-correlated single-photon counter. The second beam passes through the second collecting lens and the second fiber bundle and the detector array to generate an electrical signal input time-correlated single-photon counter.

[0024] Two sets of fiber bundles form several fiber pairs at the same position on the sample surface. The corresponding electrical signals are analyzed in a time-correlated single-photon counter and a computer using the HBT scheme to form several first-order photon images and second-order photon images. Then, a first-order photon image and a second-order photon image with improved resolution are reconstructed using the photon recombination method. Super-resolution is achieved by stripping second-order information from the first-order image.

[0025] Compared with existing technologies, this invention has the following beneficial technical effects: The quantum correlation imaging method using a single-path parallel detection fiber bundle obtains a second-order image through coupling of different fibers within the same fiber bundle, resulting in poor photon pair collection efficiency and contrast. In this invention, a beam splitter is used to split the fluorescence detected in the microscope into two beams before entering the parallel detection system. Dual-path parallel detection, after alignment correction, achieves more efficient collection of fluorescence-correlated photon pairs, thereby achieving better image quality.

[0026] Compared to a single parallel probe optical path, this invention is used in quantum dots and solid-state defects with single-photon source characteristics. This invention utilizes simple beam-splitting second-order correlation measurements to achieve improved resolution without increasing laser power.

[0027] Compared to existing quantum correlation imaging techniques, the dual-path parallel collection method designed in this invention can perform coincidence measurements in space and time, retain more coincidence photon information, shorten imaging time, and can be applied in different super-resolution optical paths, thus broadening the application scope of quantum correlation photon detection technology. Attached Figure Description

[0028] Figure 1 A flowchart of a super-resolution imaging method based on parallel collection of quantum correlated photons provided in an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the optical path of a super-resolution imaging device based on parallel collection of quantum correlated photons, provided in an embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram of the receiving end of the device provided in an embodiment of the present invention. Detailed Implementation

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0032] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0033] like Figure 1 As shown in the figure, an embodiment of the present invention provides a super-resolution imaging method based on parallel collection of quantum correlated photons, comprising the following steps:

[0034] (1) After the fluorescence passes through the 50:50 optical beam splitter (BS), the two beams are collected by the lens and enter their respective optical fiber bundles. The two optical fiber bundles have the same structure.

[0035] (2) Each fiber optic cable is connected to the same single-photon detector and connected to different channels of a time-correlated single-photon counter (TCSPC). The TCSPC is used to collect photon time-domain data of each channel.

[0036] (3) Correct the fiber positions corresponding to the two beams so that the conjugate positions of the fiber channels on the sample surface correspond one-to-one.

[0037] (4) Second-order correlation measurement is performed on the two photon time-domain data of the corresponding fiber channel to determine the time delay of the two beams;

[0038] (5) After the delay is determined, the time window is set by the second-order correlation function of the fluorescence point, and the correlated photon pairs within the time window are collected;

[0039] (6) For each pixel scanned by the microscope, the total number of photons arriving at the TCSPC from every two corresponding fiber channels is collected as the first-order photon number, and the associated photon pairs within the time window are collected as the second-order photon number; the scanning yields first-order photon image sets and second-order photon image sets for all corresponding fiber channels, and the final first-order photon image is obtained by photon recombination method. <i1>and second-order photon image <i2>;

[0040] (7) From the first-order photon image <i1>and second-order photon image <i2>Reconstruct an image with a higher resolution.

[0041] Furthermore, in step (1), the optical beam splitter adopts a 50:50 (reflectivity R: transmittance T) non-polarized cubic crystal beam splitter, and by building a 4f lens system to select a suitable Airy disk size, the two beams are coupled into the corresponding optical fiber bundle.

[0042] Furthermore, in step (2), the single-photon detector used must have a dark count of <50 photos per second for weak photon detection, and the TSCPC has a time resolution of ps.

[0043] Furthermore, in step (2), the optical fiber of each channel is connected to the same avalanche diode single-photon detector and connected to different channels of TCSPC.

[0044] Furthermore, in step (3), the spatial light modulator / phase delay plate in the excitation optical path modulates the aberration to correct the rotation angle of the two fiber bundles, so as to achieve the position alignment of the corresponding fiber channels.

[0045] Furthermore, in step (4), the TCSPC records the arrival times of the two photons in the corresponding fiber channel. During correlation, if a photon is collected in channel 2 within a set threshold time after the arrival of the photon in channel 1, it is considered that a pair of two photons has been successfully collected, and this is used as the second-order correlation photon count. Considering that fluorescence sources with single-photon characteristics usually have nanosecond-level fluorescence lifetimes, the threshold time can be set to 1 ns.

[0046] Furthermore, in step (5), the second-order correlation function g of the corresponding fiber channel is used. (2) (τ) Set the counting time window τ d At this point, a high contrast can be achieved, and a sufficient number of photons can be detected. With the second-order correlation function delay at zero, i.e., g... (2) (0) as the center, collect The number of photon pairs within the window. In this embodiment, τ d =2ns.

[0047] Further, in step (6), the photon recombination method specifically involves: determining the offset of all images in the obtained first-order photon image group through cross-correlation, and obtaining a first-order photon image through displacement superposition. <i1>The offsets of all images in the obtained second-order photon image group are determined by cross-correlation, and a second-order photon image is obtained by displacement superposition. <i2>The photon recombination method can achieve higher image resolution and signal-to-noise ratio compared to traditional non-parallel detection methods.

[0048] Furthermore, in step (7), considering that M single-photon sources are located on the same object plane, the first-order photon image G (1) The reconstruction of (x) is achieved by photon recombination from K detectors, i.e. Where x is the excitation light scanning position. For the first-order light intensity distribution obtained by detector α, x i Let h(·) be the position of each single-photon source, and h(·) be the optical transfer function. The image plane position of the detector; similarly, the second-order photon image G (2) (x) Intensity distribution of photon pairs obtained from K pairs of detectors Photon recombination is used to obtain the image; the recombination method is the same as that of the first-order image. Finally, the first-order and second-order images are subtracted by ΔG. (2) (x)=G (1) (x)·G (1) (x)-ηG (2 (x) can be used to obtain a higher resolution final image, where η is the ratio of the photon pair measurement time window to the single pixel photon collection time.

[0049] To achieve the above method, the super-resolution imaging device based on parallel collection of quantum correlated photons provided by the present invention includes: a 50:50 optical beam splitter, a first collecting lens, a first fiber bundle and detector array, a second collecting lens, a second fiber bundle and detector array, a time-correlated single-photon counter, and a computer.

[0050] The fluorescence generated by the sample is split into two beams by a 50:50 optical beam splitter. The first beam passes through the first collecting lens and the first fiber bundle and the detector array to generate an electrical signal input time-correlated single-photon counter. The second beam passes through the second collecting lens and the second fiber bundle and the detector array to generate an electrical signal input time-correlated single-photon counter.

[0051] Two sets of fiber bundles form several fiber pairs at the same position on the sample surface. The corresponding electrical signals are analyzed in a time-correlated single-photon counter and a computer using the HBT scheme to form several first-order photon images and second-order photon images. Then, a first-order photon image and a second-order photon image with improved resolution are reconstructed using the photon recombination method. Super-resolution is achieved by stripping second-order information from the first-order image.

[0052] The following is a specific implementation example of the present invention, but it is not limited thereto. Taking the imaging of NV color centers in diamond by confocal microscopy as an example, combined with... Figure 2 , Figure 3 Please provide a detailed explanation.

[0053] The optical path of a super-resolution imaging device based on parallel collection of quantum correlated photons is as follows: Figure 2 As shown, it includes a laser 1, a collimating lens 2, a first reflecting mirror 3, a quarter-wave plate 4, a dichroic mirror 5, a second reflecting mirror 6, an objective lens 7, a displacement stage 8, a third reflecting mirror 9, a fourth reflecting mirror 10, a 50:50 beam splitter 11, a first collecting lens 12, a first fiber bundle and detector array 13, a fifth reflecting mirror 14, a second collecting lens 15, a second fiber bundle and detector array 16, a time-correlated single-photon counter 17, and a computer 18.

[0054] The receiver of a super-resolution imaging device based on parallel collection of quantum correlated photons, such as... Figure 3 As shown, it includes two sets of 19-channel conjugate fiber bundles on the sample surface, with each fiber connected to a detector. The two sets of fiber bundles are paired and input into the time-correlated single-photon counter 17 according to their corresponding positions on the sample surface, forming HBT schemes respectively.

[0055] When the device is working, the laser light generated by laser 1 is collimated by collimating lens 2, becomes circularly polarized by first reflecting mirror 3 and quarter-wave plate 4, and then enters objective lens 7 to illuminate the sample through dichroic mirror 5 and second reflecting mirror 6. Displacement stage 8 is used to scan the sample. The fluorescence generated by the sample is reflected back through objective lens 7 and second reflecting mirror 6, passes through dichroic mirror 5, and then through third reflecting mirror 9 and fourth reflecting mirror 10 before being perpendicularly incident on 50:50 beam splitter 11. Here, it is split into two beams. The first beam passes through first collecting lens 12 and first fiber bundle and detector array 13 to generate an electrical signal, which is input to time-correlated single-photon counter 17. The second beam passes through fifth reflecting mirror 14, second collecting lens 15, and second fiber bundle and detector array 16 with equal optical path length to generate an electrical signal, which is also input to time-correlated single-photon counter 17. At this point, the two sets of fiber bundles form 19 fiber pairs at the same position on the sample surface. The corresponding 19 pairs of electrical signals are analyzed in the time-correlated single-photon counter 17 and computer 18 through the HBT scheme, forming 19 first-order photon images and 19 second-order photon images. The two are reconstructed into a first-order photon image and a second-order photon image with improved resolution through photon recombination, respectively. Super-resolution is then achieved by stripping second-order information from the first-order image.

[0056] The above description is merely a preferred embodiment of the present invention. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the technical solutions of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A super-resolution imaging method based on parallel collection of quantum correlated photons, characterized in that, Includes the following steps: (1) After the fluorescence passes through the 50:50 optical beam splitter, the two beams are collected by the lens and enter their respective optical fiber bundles. The two optical fiber bundles have the same structure. (2) Each fiber in each channel is connected to the same single-photon detector and connected to different channels of the time-correlated single-photon counter (TCSPC). The TCSPC is used to collect photon time-domain data of each channel. (3) Correct the fiber positions corresponding to the two beams so that the conjugate positions of the fiber channels on the sample surface correspond one-to-one. (4) Second-order correlation measurement is performed on the two photon time-domain data of the corresponding fiber channel to determine the time delay of the two beams; (5) After the delay is determined, the time window is set by the second-order correlation function of the fluorescence point, and the correlated photon pairs within the time window are collected; (6) For each pixel scanned by the microscope, the total number of photons arriving at the TCSPC from each pair of corresponding fiber channels is collected as the first-order photon number, and the associated photon pairs within the time window are collected as the second-order photon number; the first-order photon image group and the second-order photon image group of all corresponding fiber channels are obtained by scanning, and the final first-order photon image and the second-order photon image are obtained by photon recombination method. (7) A higher resolution image is reconstructed from the first-order photon image and the second-order photon image.

2. The super-resolution imaging method based on parallel collection of quantum correlated photons according to claim 1, characterized in that, In step (1), the optical beam splitter is a 50:50 non-polarized cubic crystal beam splitter. By building a 4f lens system to select a suitable Airy disk size, the two beams are coupled into the corresponding fiber bundles.

3. The super-resolution imaging method based on parallel collection of quantum correlated photons according to claim 1, characterized in that, In step (2), the single-photon detector used must have a dark count of <50 photos per second for weak photon detection, and the TSCPC has a time resolution of ps.

4. The super-resolution imaging method based on parallel collection of quantum correlated photons according to claim 1, characterized in that, In step (2), the optical fiber of each channel is connected to the same avalanche diode single-photon detector and connected to different channels of TCSPC.

5. The super-resolution imaging method based on parallel collection of quantum correlated photons according to claim 1, characterized in that, In step (3), the spatial light modulator / phase delay plate in the excitation optical path modulates the aberration to correct the rotation angle of the two fiber bundles, so as to achieve the position alignment of the corresponding fiber channels.

6. The super-resolution imaging method based on parallel collection of quantum correlated photons according to claim 1, characterized in that, In step (4), TCSPC records the arrival time of the two photons in the corresponding fiber channel. If, during the association, the photon in channel 1 arrives and the photon in channel 2 is also collected within a set threshold time, it is considered that a pair of photons has been successfully collected, and this is used as the number of second-order associated photons.

7. The super-resolution imaging method based on parallel collection of quantum correlated photons according to claim 1, characterized in that, In step (5), the counting time window τ is set by the second-order correlation function of the corresponding fiber channel. d At this point, the required contrast can be achieved and a sufficient number of photons can be detected; collection The number of photon pairs within the window.

8. The super-resolution imaging method based on parallel collection of quantum correlated photons according to claim 1, characterized in that, In step (6), the photon recombination method specifically involves: determining the offset of all images in the obtained first-order photon image group through cross-correlation, and obtaining a first-order photon image through displacement superposition; determining the offset of all images in the obtained second-order photon image group through cross-correlation, and obtaining a second-order photon image through displacement superposition.

9. The super-resolution imaging method based on parallel collection of quantum correlated photons according to claim 1, characterized in that, In step (7), the specific calculation method for image reconstruction is as follows: Consider M single-photon sources located on the same object plane, and the first-order photon image G. (1) The reconstruction of (x) is achieved by photon recombination from K detectors, i.e. Where x is the excitation light scanning position. For the first-order light intensity distribution obtained by detector α, x i Let h(·) be the position of each single-photon source, and h(·) be the optical transfer function. The image plane position of the detector; similarly, the second-order photon image G (2) (x) Intensity distribution of photon pairs obtained from K pairs of detectors Photon recombination is used to obtain the image; the recombination method is the same as that of the first-order image. Finally, the first-order and second-order images are subtracted by ΔG. (2) (x)=G (1) (x)·G (1) (x)-ηG (2) (x) can obtain a higher resolution final image, where η is the ratio of the photon pair measurement time window to the single pixel photon collection time.

10. A super-resolution imaging device for parallel collection of quantum correlated photons based on the method of any one of claims 1-9, characterized in that, It includes a 50:50 optical beam splitter, a first collecting lens, a first fiber bundle and detector array, a second collecting lens, a second fiber bundle and detector array, a time-correlated single-photon counter, and a computer; The fluorescence generated by the sample is split into two beams by a 50:50 optical beam splitter. The first beam passes through the first collecting lens and the first fiber bundle and the detector array to generate an electrical signal input time-correlated single-photon counter; the second beam passes through the second collecting lens and the second fiber bundle and the detector array to generate an electrical signal input time-correlated single-photon counter. Two sets of fiber bundles form several fiber pairs at the same position on the sample surface. The corresponding electrical signals are analyzed in a time-correlated single-photon counter and a computer using the HBT scheme to form several first-order photon images and second-order photon images. Then, a first-order photon image and a second-order photon image with improved resolution are reconstructed using the photon recombination method. Super-resolution is achieved by stripping second-order information from the first-order image.

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