Two-photon volumetric imaging device and method based on phase-controlled ring-shaped airy beam

Abstract

The application provides a kind of two-photon volume imaging device and method based on phase control annular Airy beam, belong to optical microscope imaging and optical control technical field.The device includes laser beam expander module, beam deflection module, annular Airy beam modulation module, beam scanning module and imaging module, the application is based on traditional two-photon microscope, and annular Airy beam modulation module is innovatively introduced, the shape of focus beam is accurately controlled by adjusting phase using spatial light modulator SLM, generating spectrum using Fourier lens;Indirectly generate annular Airy beam and new type vortex annular Airy beam using SLM, can generate smaller focusing focal point and long focal depth light needle, directly improve imaging resolution by improving the scanning accuracy of two-photon microscope, expand axial depth of field, at the same time, axial variation is generated on the basis of annular Airy light needle, through fitting beam shape and axial depth, realize depth analysis to axial three-dimensional information.

Description

Technical Field

[0001] This invention relates to the field of optical microscope imaging and optical manipulation technology, and in particular to a two-photon volumetric imaging device and method based on a phase-controlled annular Airy beam. Background Technology

[0002] In the field of optical microscopy, confocal microscopy stands out for its ability to provide high spatial resolution and contrast with superior scale and depth within scattering tissues, making it an important tool for three-dimensional imaging of thick tissues. Two-photon microscopy (TPM), employing longer wavelength illumination and nonlinear excitation, outperforms traditional confocal microscopy in resisting scattering and improving spatial resolution. In summary, the combination of two-photon and volumetric imaging techniques can achieve greater penetration depth while maintaining acceptable lateral resolution, and can also improve the ability of annular Airy beam-based volumetric microscopy to locate lateral offsets on a two-dimensional projection plane.

[0003] However, since excitation in confocal microscopy only occurs at the focal point of a diffraction-limited microscope, volumetric imaging of thick biological samples is usually achieved by scanning the focal point in three dimensions. This volumetric imaging speed is limited by mechanical Z-axis scanning, and tissue scattering effects restrict the quality of deep-layer imaging. Two-photon microscopy (TPM) utilizes long-wavelength excitation and nonlinear optical effects to significantly improve penetration depth and scattering suppression, but its volumetric imaging efficiency is still limited by the scanning mechanism. To overcome these technical bottlenecks, a ring Airy beam is introduced, enabling axially extended needle-like beams to generate large axial depth-of-field imaging and reducing the time cost of layer-scan volumetric imaging. However, because this method projects all volumetric information onto a compact two-dimensional plane, it cannot provide sample depth information from different layers; that is, this platform lacks axial resolution. Summary of the Invention

[0004] The purpose of this invention is to provide a two-photon volumetric imaging device and method based on a phase-controlled annular Airy beam. By adding additional vortex phase control to the annular Airy beam, the generated needle-shaped beam undergoes axial change. This axial change is then fitted with depth information, and a computational fitting method is used to reconstruct the three-dimensional spatial information, thereby achieving depth information analysis for three-dimensional volumetric imaging.

[0005] To achieve the above objectives, this invention proposes a two-photon volumetric imaging device based on a phase-controlled ring Airy beam, comprising a laser beam expander module, a beam deflection module, a ring Airy beam modulation module, a beam scanning module, and an imaging module. The laser beam expander module includes a laser, a half-wave plate, a polarizing beam splitter, a first lens, and a second lens. The beam deflection module includes a first mirror, a second mirror, and a third mirror. The ring Airy beam modulation module includes a spatial light modulator, a Fourier lens, and an aperture. The beam scanning module includes a third lens, a fourth lens, an XY scanning galvanometer, a scanning lens, a sleeve lens, and a fourth mirror. The imaging module includes a dichroic mirror, an objective lens, a sample, a filter, and a photomultiplier tube.

[0006] Preferably, reflector one, reflector two and reflector three are flip-up reflectors.

[0007] Preferably, the spatial light modulator receives a collimated and expanded illumination beam. The spatial light modulator is preloaded with a designed phase hologram, and the angle is adjusted so that the angle between the incident light and the outgoing light is less than 15°. The spatial light modulator can be replaced by a digital micromirror device (DMD), a custom phase element, or a liquid crystal phase slide. When the spatial light modulator is reflective, it can be replaced by a transmissive spatial light modulator and placed in front of the objective lens.

[0008] Preferably, the aperture is placed at the focal point of the Fourier lens.

[0009] Preferably, the excitation light received by the sample is a ring Airy beam or a novel vortex ring Airy beam.

[0010] Preferably, the excitation light is focused onto the sample by the objective lens. After the sample is excited, it generates signal light, which is reflected by a dichroic mirror, filtered by a filter, and then enters the photomultiplier tube.

[0011] This invention also provides a two-photon volumetric imaging method based on a phase-tuned annular Airy beam, comprising the following steps:

[0012] Step S1: A femtosecond laser illumination beam is emitted from the laser. The laser power is adjusted by a half-wave plate and a polarizing beam splitter. Lens 1 and Lens 2 collimate and expand the adjusted illumination beam to match the beam diameter with the spatial light modulator. The optical path is switched by mirror 1, mirror 2 and mirror 3.

[0013] Step S2: Load the designed phase hologram into the spatial light modulator, and send the collimated and expanded beam into the spatial light modulator through the reflector. The spatial light modulator converts the incident beam into a ring Airy beam or a novel vortex ring Airy beam through phase modulation.

[0014] Step S3: Adjust the angle of the spatial light modulator so that the angle between the incident light and the outgoing light is less than 15°. The beam modulated by the spatial light modulator is converted from the spatial domain to the frequency domain by the Fourier lens. An aperture is placed at the focal position of the Fourier lens to filter out the +1 order diffracted light from the two blazed gratings, generating a new type of vortex ring Airy beam carrying a vortex phase. Then, the frequency domain beam is conjugated to the entrance pupil of the objective lens by the third lens, the fourth lens, the scanning lens, and the sleeve lens.

[0015] Step S4: Use lens three and lens four to collimate the modulated beam into an XY scanning galvanometer. By adjusting the reflection angle, scan the sample point by point in the XY plane. Utilize the long focal depth of the beam to cover the axial range of the sample. The spectral plane is transmitted to the entrance pupil of the objective lens through the scanning lens, sleeve lens and mirror four.

[0016] Step S5: The excitation light is focused onto the sample by the objective lens, which excites the sample to generate signal light. The signal light is collected by the objective lens, reflected by the dichroic mirror, processed by the filter, and finally sent into the photomultiplier tube to complete the collection and recording of the imaging signal.

[0017] Step S6: Perform axial depth analysis, record the light intensity distribution or fluorescence intensity distribution at different scanning positions, extract and analyze the sidelobe rotation features and radius changes, and fit and analyze the three-dimensional structure of the sample through the mapping relationship between the rotation angle and the axial depth.

[0018] Preferably, in step S1, the optical path switching includes a Gaussian optical path and a structured optical path.

[0019] Preferably, in step S2, the phase hologram is calculated using a diffraction grating algorithm, and the specific calculation formula is as follows:

[0020] ;

[0021] ;

[0022] ;

[0023] in, Let be a normalized bounded positive function of amplitude. for The inverse function of a function Used to obtain the modulus of complex parameters. For the expression of a ring-shaped Airy beam, Let be the analytic function of the amplitude and phase profile of the desired field. Used to obtain the argument of complex parameters. The phase distribution function, and For pixel coordinates, The imaginary unit, For modulo operation functions, Let be an analytical function of the amplitude and phase distribution of the target field. It is a periodicity.

[0024] Preferably, in step S5, the novel vortex-ring Airy beam is obtained by fitting the beam shape and axial depth. In cylindrical coordinates, the expression for the novel vortex-ring Airy beam is:

[0025] ;

[0026] in, The amplitude index of the ring Airy beam. Represents the Airy function, The radius of the main loop. Radial coordinates, For any scaling factor, The vortex function is expressed as:

[0027] ;

[0028] in, It is the azimuth angle, and its value range is always within... arrive between, Indicates the number of topological loads. The power exponent representing the spiral phase. Represents the modulus function.

[0029] Therefore, this invention proposes a two-photon volumetric imaging device and method based on a phase-controlled annular Airy beam, the advantages of which are as follows:

[0030] (1) The imaging system proposed in this invention uses structured light field to excite the sample, which has a faster volume imaging speed compared with the traditional confocal scanning imaging system.

[0031] (2) The present invention can achieve an axial depth of field of 130-150μm without sacrificing its imaging resolution, and can accurately locate the sample depth position based on the side lobes.

[0032] (3) The present invention utilizes structured light field to excite the sample, thereby realizing a two-photon fluorescence imaging system with faster volume imaging speed. It can stably acquire three-dimensional volume imaging of biological samples without labeling and can achieve depth resolution.

[0033] (4) In addition to using a phase-type spatial light modulator to modulate the amplitude and phase of the incident light to generate a novel vortex ring Airy beam with special amplitude and phase, the present invention can also generate other forms of excitation light sources, such as Bessel light and various structured light, by controlling the spatial light modulator, thus forming an imaging system that makes it easier to switch excitation light sources. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a two-photon volumetric imaging device based on a phase-tuned annular Airy beam.

[0035] Figure 2 This is a flowchart of a two-photon volumetric imaging method based on a phase-modulated annular Airy beam;

[0036] Figure 3 The simulated normalized intensity distribution of the novel vortex ring Airy beam in the xz and yz planes is shown.

[0037] Figure 4 This is a schematic diagram of the two-photon fluorescence intensity of a single fluorescent microsphere scanned by a novel vortex-ring Airy beam.

[0038] Figure Labels

[0039] 1. Laser; 2. Half-wave plate; 3. Polarizing beam splitter; 4. Lens 1; 5. Lens 2; 6. Mirror 1; 7. Mirror 2; 8. Spatial light modulator; 9. Fourier lens; 10. Aperture; 11. Mirror 3; 12. Lens 3; 13. Lens 4; 14. XY scanning galvanometer; 15. Scanning lens; 16. Sleeve lens; 17. Mirror 4; 18. Dichroic mirror; 19. Objective lens; 20. Sample; 21. Filter; 22. Photomultiplier tube. Detailed Implementation

[0040] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0041] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0042] Example 1

[0043] like Figure 1As shown, this invention provides a two-photon volumetric imaging device based on a phase-controlled ring Airy beam. This device adopts a compact modular design with a reasonable overall structure, providing a two-photon fluorescence imaging device with faster volumetric imaging speed. It includes a laser beam expander module, a beam deflection module, a ring Airy beam modulation module, a beam scanning module, and an imaging module. The laser beam expander module includes a laser 1, a half-wave plate 2, a polarizing beam splitter 3, a lens 4, and a lens 5. The beam deflection module includes a mirror 6, a mirror 7, and a mirror 11. The ring Airy beam modulation module includes a spatial light modulator 8, a Fourier lens 9, and an aperture 10. The beam scanning module includes a lens 12, a lens 13, an XY scanning galvanometer 14, a scanning lens 15, a sleeve lens 16, and a mirror 17. The imaging module includes a dichroic mirror 18, an objective lens 19, a sample 20, a filter 21, and a photomultiplier tube 22.

[0044] The laser beam expander module is used to expand the laser beam to meet the beam size requirements of subsequent modulation. Laser 1 provides the femtosecond laser illumination beam, which is the light source basis of the entire imaging device. Half-wave plate 2 and polarizing beam splitter 3 are used to adjust the laser power to meet the laser intensity requirements of different sample imaging. Lens 4 and 5 collimate and expand the illumination beam. Finally, the beam diameter is adjusted to match the spatial light modulator 8 to ensure the effectiveness of subsequent phase modulation.

[0045] In the beam deflection module, reflector 6, reflector 7, and reflector 11 are three flip-up reflectors used to switch between the Gaussian optical path and the structured optical path. Meanwhile, reflector 6 and reflector 7 are also used to change the propagation direction of the beam and guide the collimated and expanded beam to accurately enter the spatial light modulator 8.

[0046] The ring Airy beam modulation module is used to generate the ring Airy beam and modulate the excitation focus. The spatial light modulator 8 is preloaded with a designed phase hologram to modulate the phase of the incident beam, converting the beam into the desired ring Airy beam or a novel vortex ring Airy beam. The angle of the spatial light modulator 8 is adjusted so that the angle between the incident and outgoing light is less than 15°. The Fourier lens 9 converts the beam modulated by the spatial light modulator 8 from the spatial domain to the frequency domain, realizing the spectrum conversion of the light field. The aperture 10 is placed at the focal position of the Fourier lens 9 to filter out the +1st order diffracted light from the two blazed gratings to ensure the purity of the beam. Then, the frequency domain beam is conjugated to the entrance pupil of the objective lens through lens 12, lens 13, scanning lens 15, and sleeve lens 16.

[0047] The beam scanning module is used to drive the beam to scan the entire sample. Lens 12 and 13 collimate the modulated beam and send it into the XY scanning galvanometer 14 to ensure that the beam enters the scanning galvanometer with appropriate size and state. The XY scanning galvanometer 14 achieves point-by-point scanning of the XY plane by adjusting the reflection angle, thereby driving the beam to scan the entire sample. The scanning lens 15, the sleeve lens 16 and the fourth mirror 17 transmit the phase plane to the entrance pupil of the objective lens 19 to ensure that the beam can be accurately focused on the sample.

[0048] The imaging module is used to collect sample signals. The dichroic mirror 18 reflects the signal light generated after the sample is activated, allowing the signal light to enter the subsequent filtering and detection stages. The objective lens 19 focuses the ring Airy beam onto the sample 20, exciting the sample 20 to generate signal light and collecting it. The filter 21 filters the signal light, removing stray light interference and improving the purity of the signal light. The photomultiplier tube 22 collects the filtered signal light and converts the optical signal into an electrical signal, completing the recording of the imaging signal.

[0049] Example 2

[0050] like Figure 2 As shown, the present invention also provides a two-photon volumetric imaging method based on a phase-tuned annular Airy beam, comprising the following steps:

[0051] Step S1: A femtosecond laser illumination beam is emitted from laser 1. The half-wave plate 2 and polarizing beam splitter 3 adjust the laser power. Lens 4 and 5 collimate and expand the adjusted illumination beam to match the beam diameter with the spatial light modulator 8. The optical path is switched through mirror 6, mirror 7 and mirror 11. The switched optical path includes a Gaussian optical path and a structured optical path.

[0052] Step S2: Load the designed phase hologram into the spatial light modulator 8, and send the collimated and expanded beam into the spatial light modulator 8 through the reflector 6. The spatial light modulator 8 converts the incident beam into a ring Airy beam or a new type of vortex ring Airy beam through phase modulation.

[0053] Step S3: Adjust the angle of the spatial light modulator 8 so that the angle between the incident light and the outgoing light is less than 15°. The beam modulated by the spatial light modulator 8 is converted from the spatial domain to the frequency domain by the Fourier lens 9. An aperture 10 is placed at the focal position of the Fourier lens 9 to filter out the +1 order diffracted light from the two blazed gratings, generating a new type of vortex ring Airy beam carrying a vortex phase. Then, the frequency domain beam is conjugated to the entrance pupil surface of the objective lens 19 by the lens 12, lens 13, scanning lens 15 and sleeve lens 16.

[0054] The 8-phase hologram of the spatial light modulator is calculated using a diffraction grating algorithm. The specific calculation formula is as follows:

[0055] ;

[0056] ;

[0057] ;

[0058] in, Let be a normalized bounded positive function of amplitude. for The inverse function of a function Used to obtain the modulus of complex parameters. For the expression of a ring-shaped Airy beam, Let be the analytic function of the amplitude and phase profile of the desired field. Used to obtain the argument of complex parameters. The phase distribution function, and For pixel coordinates, The imaginary unit, For modulo operation functions, Let be an analytical function of the amplitude and phase distribution of the target field. For periodicity;

[0059] Step S4: Using lens three 12 and lens four 13, the modulated beam is collimated and XY scanning galvanometer 14 is used to scan the sample point by point in the XY plane by adjusting the reflection angle. The long focal depth of the beam is used to cover the axial range of the sample. The spectrum is transmitted to the entrance pupil of the objective lens through scanning lens 15, sleeve lens 16 and mirror four 17.

[0060] Step S5: The excitation light is focused onto the sample 20 by the objective lens 19, which excites the sample to generate signal light. The signal light is collected by the objective lens 19, reflected by the dichroic mirror 18, processed by the filter 21, and finally sent into the photomultiplier tube 22 to complete the collection and recording of the imaging signal.

[0061] Among them, the novel vortex-ring Airy beam is obtained by fitting the beam shape and axial depth. In cylindrical coordinates, the expression of the novel vortex-ring Airy beam is:

[0062] ;

[0063] in, The amplitude index of the ring Airy beam. Represents the Airy function, The radius of the main loop. Radial coordinates, For any scaling factor, The vortex function is expressed as:

[0064] ;

[0065] in, It is the azimuth angle, and its value always ranges from 0 to... between, Indicates the number of topological loads. The power exponent representing the spiral phase. Represents the modulus function.

[0066] Step S6: Perform axial depth analysis, record the light intensity distribution or fluorescence intensity distribution at different scanning positions, extract and analyze the sidelobe rotation features and radius changes, and fit and analyze the three-dimensional structure of the sample through the mapping relationship between the rotation angle and the axial depth.

[0067] The invention will be further illustrated below through specific implementation examples.

[0068] The experimental setup used in the specific implementation of this invention is a depth-resolved volumetric two-photon fluorescence microscope based on a novel vortex-ring Airy beam, which employs a common-path configuration of a 4f system.

[0069] Step S1: The linearly polarized Gaussian beam output from the 920 nm femtosecond laser is split into two beams by a polarizing beam splitter PBS. Lens 4 and 5 collimate and expand the adjusted illumination beams to match the beam diameter with the spatial light modulator. One beam is a Gaussian optical path used for alignment and calibration of the microscope system. The other beam is a structured light path that enters the spatial light modulator SLM (UPOLabs, HDSLM-1080P) to generate a novel vortex ring Airy beam.

[0070] Step S2: Load the designed phase hologram into the spatial light modulator, and send the collimated and expanded beam into the spatial light modulator through the reflector. The spatial light modulator converts the incident beam into a ring Airy beam or a novel vortex ring Airy beam through phase modulation.

[0071] Step S3: Adjust the angle of the spatial light modulator so that the angle between the incident light and the outgoing light is less than 15°. The beam modulated by the spatial light modulator is converted from the spatial domain to the frequency domain by the Fourier lens. An aperture is placed at the focal position of the Fourier lens to filter out the +1 order diffracted light from the two blazed gratings, generating a new type of vortex ring Airy beam carrying a vortex phase. Then, the frequency domain beam is conjugated to the entrance pupil of the objective lens by lens 12, lens 13, scanning lens and sleeve lens.

[0072] The spatial light modulator (SLM) is located on the input plane of the 4f system composed of lens 12 and lens 13. After modulation by the 4f system, the light beam enters the two-photon microscope (in this case, a Nikon Eclipse Ti microscope). The phase mask loaded on the SLM for amplitude modulation is calculated using a diffraction grating algorithm, and the specific calculation formula is as follows:

[0073] ;

[0074] ;

[0075] ;

[0076] in, Let be a normalized bounded positive function of amplitude. for The inverse function of a function Used to obtain the modulus of complex parameters. For the expression of a ring-shaped Airy beam, Let be the analytic function of the amplitude and phase profile of the desired field. Used to obtain the argument of complex parameters. The phase distribution function, and For pixel coordinates, The imaginary unit, For modulo operation functions, Let be an analytical function of the amplitude and phase distribution of the target field. For periodicity;

[0077] Step S4: Using lens three 12 and lens four 13, the modulated novel vortex ring Airy beam is collimated and XY scanned by a galvanometer. By adjusting the reflection angle, the two photons of a single fluorescent microsphere are scanned. The long focal depth of the beam is used to cover the axial range of the sample. The spectral surface is transmitted to the entrance pupil of the objective lens through the scanning lens, the sleeve lens and the four mirrors.

[0078] Step S5: The excitation light is focused onto the sample by the objective lens, exciting the sample to generate signal light. The signal light is collected by the objective lens, reflected by the dichroic mirror, processed by a filter, and finally sent into the photomultiplier tube to complete the collection and recording of the imaging signal. The novel vortex-ring Airy beam is obtained by fitting the beam shape and axial depth. In cylindrical coordinates, the expression for the novel vortex-ring Airy beam is:

[0079] ;

[0080] in, The amplitude index of the ring Airy beam. Represents the Airy function, The radius of the main loop. Radial coordinates, For any scaling factor, The vortex function is expressed as:

[0081] ;

[0082] in, It is the azimuth angle, and its value always ranges from 0 to... between, Indicates the number of topological loads. The power exponent representing the spiral phase. Represents the modulus function.

[0083] Step S6: Perform axial depth analysis;

[0084] Step S61: Record the simulated normalized intensity distribution of the novel vortex-ring Airy beam in the xz and yz planes. The results are as follows: Figure 3 As shown, by extracting the sidelobe rotation feature, it was found that the sidelobes of the beam rotated during propagation.

[0085] Step S62: Record the two-photon fluorescence intensity of a single fluorescent microsphere using the novel vortex ring Airy beam scanning. The results are as follows: Figure 4 As shown, by extracting the changes in sidelobe radius, it was found that sidelobes at different depths have different angles and radii.

[0086] Step S63: Fit and analyze the three-dimensional structure of the sample by the mapping relationship between the rotation angle and the axial depth.

[0087] It is worth noting that all contents not described in detail in this invention are existing technologies and are well known to those skilled in the art.

[0088] Therefore, this invention provides a two-photon volumetric imaging device and method based on a phase-modulated ring Airy beam. By innovatively introducing a ring Airy beam modulation module on the basis of traditional two-photon microscopy, it achieves high-resolution, large depth-of-field imaging of biological samples of equal thickness, such as biological tissues or blood vessels. It causes minimal light damage to biological tissues and can be used for long-term in vivo imaging research. At the same time, compared with the traditional Gaussian beam, the ring Airy beam can achieve a large depth-of-field imaging of more than 100 micrometers. In the field of neuroscience, it can be used for rapid three-dimensional volumetric imaging of cerebral blood vessels and three-dimensional volumetric imaging of deep brain nerve cells. Furthermore, the novel vortex ring Airy beam, through modulation, can also achieve depth resolution in three-dimensional volumetric imaging.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A two-photon volumetric imaging device based on a phase-tuned annular Airy beam, characterized in that: It includes a laser beam expander module, a beam deflection module, a ring Airy beam modulation module, a beam scanning module, and an imaging module. The laser beam expander module includes a laser, a half-wave plate, a polarizing beam splitter, and lenses one and two. The beam deflection module includes mirror one, mirror two, and mirror three. The ring Airy beam modulation module includes a spatial light modulator, a Fourier lens, and an aperture. The beam scanning module includes lens three, lens four, an XY scanning galvanometer, a scanning lens, a sleeve lens, and mirror four. The imaging module includes a dichroic mirror, an objective lens, a sample, a filter, and a photomultiplier tube. The laser beam expander module is used to expand the laser beam to meet the beam size requirements for subsequent modulation; the beam deflection module is used to switch between the Gaussian optical path and the structured optical path. Simultaneously, mirrors one and two in the beam deflection module guide the collimated and expanded beam to accurately enter the spatial light modulator; the spatial light modulator in the ring Airy beam modulation module is pre-loaded with a designed phase hologram to modulate the phase of the incident beam, converting the beam into the desired ring Airy beam or a novel vortex ring Airy beam; the beam scanning module is used to drive the beam to scan the entire sample, and the imaging module is used to collect sample signals. The novel vortex-ring Airy beam is obtained by fitting the beam shape and axial depth. In cylindrical coordinates, the expression for the novel vortex-ring Airy beam is: ； in, The amplitude index of the ring Airy beam. For Airy functions, The radius of the main loop. Radial coordinates, For any scaling factor, The vortex function is expressed as: ； in, It's the azimuth. Indicates the number of topological loads. The power exponent representing the spiral phase. Represents the modulus function.

2. The two-photon volumetric imaging device based on a phase-tuned annular Airy beam according to claim 1, characterized in that: The first, second, and third reflectors are flip-up reflectors.

3. The two-photon volumetric imaging device based on a phase-tuned annular Airy beam according to claim 1, characterized in that: The spatial light modulator receives a collimated and expanded illumination beam. The spatial light modulator is preloaded with a designed phase hologram, and the angle is adjusted so that the angle between the incident light and the outgoing light is less than 15°. The spatial light modulator is replaced with a digital micromirror device (DMD), a custom phase element, or a liquid crystal phase slide.

4. The two-photon volumetric imaging device based on a phase-tuned annular Airy beam according to claim 1, characterized in that: The aperture is positioned at the focal point of the Fourier lens.

5. A two-photon volumetric imaging device based on a phase-tuned annular Airy beam according to claim 1, characterized in that: The excitation light received by the sample is a ring Airy beam or a novel vortex ring Airy beam.

6. A two-photon volumetric imaging device based on a phase-tuned annular Airy beam according to claim 5, characterized in that: The excitation light is focused onto the sample by the objective lens. After the sample is excited, it generates signal light, which is reflected by a dichroic mirror, filtered by a filter, and then enters the photomultiplier tube.

7. A two-photon volumetric imaging method based on a phase-tuned annular Airy beam, characterized in that, Includes the following steps: Step S1: A femtosecond laser illumination beam is emitted from the laser. The laser power is adjusted by a half-wave plate and a polarizing beam splitter. Lens 1 and Lens 2 collimate and expand the adjusted illumination beam to match the beam diameter with the spatial light modulator. The optical path is switched by mirror 1, mirror 2 and mirror 3. Step S2: Load the designed phase hologram into the spatial light modulator, and send the collimated and expanded beam into the spatial light modulator through the reflector. The spatial light modulator converts the incident beam into a ring Airy beam or a novel vortex ring Airy beam through phase modulation. Step S3: Adjust the angle of the spatial light modulator so that the angle between the incident light and the outgoing light is less than 15°. The beam modulated by the spatial light modulator is converted from the spatial domain to the frequency domain by the Fourier lens. An aperture is placed at the focal position of the Fourier lens to filter out the +1st order diffracted light from the two blazed gratings, generating a new type of vortex ring Airy beam carrying a vortex phase. Then, the frequency domain beam is conjugated to the entrance pupil of the objective lens by the third lens, the fourth lens, the scanning lens, and the sleeve lens. Step S4: Use lens three and lens four to collimate the modulated beam into an XY scanning galvanometer. By adjusting the reflection angle, scan the sample point by point in the XY plane. Utilize the long focal depth of the beam to cover the axial range of the sample. The spectral plane is transmitted to the entrance pupil of the objective lens through the scanning lens, sleeve lens and mirror four. Step S5: The excitation light is focused onto the sample by the objective lens, which excites the sample to generate signal light. The signal light is collected by the objective lens, reflected by the dichroic mirror, processed by the filter, and finally sent into the photomultiplier tube to complete the collection and recording of the imaging signal. Step S6: Perform axial depth analysis, record the light intensity distribution or fluorescence intensity distribution at different scanning positions, extract and analyze the sidelobe rotation features and radius changes, and fit and analyze the three-dimensional structure of the sample through the mapping relationship between the rotation angle and the axial depth. The novel vortex-ring Airy beam is obtained by fitting the beam shape and axial depth. In cylindrical coordinates, the expression for the novel vortex-ring Airy beam is: ； in, The amplitude index of the ring Airy beam. For Airy functions, The radius of the main loop. Radial coordinates, For any scaling factor, The vortex function is expressed as: ； in, It's the azimuth. Indicates the number of topological loads. The power exponent representing the spiral phase. Represents the modulus function.

8. The two-photon volumetric imaging method based on a phase-tuned annular Airy beam according to claim 7, characterized in that: In step S1, switching the optical path includes the Gaussian optical path and the structured optical path.

9. A two-photon volumetric imaging method based on a phase-tuned annular Airy beam according to claim 7, characterized in that: In step S2, the phase hologram is calculated using a diffraction grating algorithm. The specific calculation formula is as follows: ； ； ； in, Let be a normalized bounded positive function of amplitude. for The inverse function of a function Used to obtain the modulus of complex parameters. Let be the expression for a ring-shaped Airy beam. Let be the analytic function of the amplitude and phase profile of the desired field. Used to obtain the argument of complex parameters. The phase distribution function, and For pixel coordinates, The imaginary unit, For modulo operation functions, Let be the analytic function of the amplitude and phase distribution of the target field. It is a periodicity.

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