Laser direct writing system for nanoscale spectral depth coding and implementation method thereof

Abstract

The invention discloses a laser direct writing system for nanoscale spectral depth coding and an implementation method of the laser direct writing system, and belongs to the field of laser processing. A series of problems caused by processing and characterization separation in a traditional process are solved, optical axis layered scanning data are collected in real time through a spectrograph, an objective lens light path is shared with laser direct writing, color information of light is coded into sample depth information, nanoscale detection imaging is achieved, and axial sensitivity is remarkably improved; a suppression light source is adopted to realize super-resolution direct writing; phase distribution is calculated by adopting a feedback aberration-free axial scanning algorithm, so that the focus of the objective lens moves along the optical axis; a multi-stage linkage dynamic adjustment mechanism is established, and the static calibration limitation of a traditional direct writing process is broken through; the method is applied to preparation and morphology characterization in the fields of high-precision nano processing and real-time nondestructive testing, microstructure manufacturing of integrated optical chips and the like, and an advanced solution integrating super-resolution processing and in-situ monitoring is provided for leading-edge scientific research and high-end manufacturing.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of laser processing, and particularly relates to a nanoscale spectrum depth coded laser direct writing system and an implementation method thereof. BACKGROUND

[0002] Laser direct writing technology, as an important means of micro-nano processing, has significant advantages in three-dimensional processing flexibility, equipment complexity and energy consumption, and is widely used in the fields of micro-nano photonics, optical information storage, biomedicine (microfluidic chip) and micro-electro-mechanical system. However, the resolution capability of laser direct writing technology is poor, and the line width of single-photon laser direct writing is about several hundred nanometers. Although the line width can be reduced by methods such as focal spot control or direct writing near the threshold power, the line width is greatly affected by the fluctuation of light power, and thus the stability is poor. With the development of ultrafast laser technology, the nonlinear effect in the material can be utilized, which makes three-dimensional processing in the material possible. The two-photon absorption effect compresses the polymerization range to the focal point area, and improves the manufacturing precision to the order of hundreds of nanometers to sub-hundreds of nanometers. However, the nonlinear effect still does not break through the limit of the diffraction limit, and some devices need higher writing precision, so it is necessary to further improve the line width. In recent years, inspired by the stimulated emission annihilation microscopic imaging technology, researchers have found some photo-initiators suitable for super-resolution laser direct writing. The two-photon absorption is initiated by femtosecond laser, and the photo-initiator is pumped to the excited state. The stimulated light is suppressed, and the excited-state molecules are pulled back to the ground state. The suppression light is shaped into a ring-shaped beam, which can compress the point spread function, thereby breaking through the limit of the diffraction limit and obtaining higher precision processing effect.

[0003] However, the super-resolution laser direct writing based on tight focusing usually needs a large numerical aperture (NA) optical system, and the large NA optical system needs a certain immersion medium. The refractive index of the immersion medium is usually different from that of the sample material, and the refractive index mismatch will bring spherical aberration. Such spherical aberration is directly related to the focusing depth, and the spherical aberration will accumulate during beam propagation, so the spherical aberration problem is more prominent when focusing at a deep layer than when focusing at a surface layer. The spherical aberration will affect the focusing spot morphology of the excitation light and the suppression light, reduce the effective light intensity, and cause the axial shift and deformation of the spot. Moreover, the spherical aberration will cause the radial expansion and axial stretching of the focusing spots of the two beams of different wavelengths and different modes, and the axial misalignment of the two beams, which will degrade the line width of the processed structure. In addition, the Laguerre-Gaussian beam used in traditional super-resolution suppression is single-photon excitation, and the axial propagation depth of such a beam is limited under high-NA focusing. Therefore, the super-resolution line width of the super-resolution laser direct writing system based on STED or related principles is usually limited to the surface layer (<10 μm) of the material.

[0004] A fundamental limitation of current laser direct writing technology is that it cannot achieve in-situ, synchronous and real-time deep three-dimensional imaging characterization during the processing. The processed structure must be transferred to an independent optical microscope platform for observation and analysis. This forced separation of processing and characterization in space and time not only seriously disrupts the continuity of the manufacturing process, but also significantly increases the time cost due to sample transfer, repositioning and equipment switching. More importantly, structural abnormalities or defects that occur during processing can only be discovered in the post-processing characterization, completely losing the opportunity for real-time monitoring and immediate correction during processing. This makes the optimization of process parameters highly dependent on time-consuming batch experiments, and unable to perform dynamic closed-loop optimization based on real-time imaging feedback in a single processing. Therefore, the existing technology is essentially an offline, non-in-situ and non-real-time mode of "processing-transferring-observation", which seriously restricts the efficient and high-precision manufacturing and online quality control of complex three-dimensional micro-nano structures.

[0005] To characterize the structures written directly, the most commonly used method is to use a scanning electron microscope. However, scanning electron microscope equipment has relatively high complexity and energy consumption, long shooting time, and requires gold spraying pretreatment. In particular, scanning electron microscopes cannot perform three-dimensional imaging. With the application and promotion of optical microscopic imaging technology, the observation target of optical microscopic imaging has gradually developed from traditional two-dimensional planes to three-dimensional samples with certain thickness, and three-dimensional microscopic imaging technology has gradually become a research hotspot in the field of optical microscopic imaging. However, the three-dimensional imaging capability of traditional optical microscopes is limited, because the microscopic objective lens usually has a limited depth of field, and the in-focus region within the depth of field range can be clearly observed during imaging, while the out-of-focus region outside the depth of field range is difficult to clearly image, and the blurred background and clear in-focus signal in the out-of-focus region are usually difficult to distinguish in the same image, which makes it difficult for traditional optical microscopes to achieve three-dimensional imaging of complex three-dimensional samples. The current way to distinguish in-focus signals and out-of-focus backgrounds is to set a filter device in the optical path to prevent out-of-focus backgrounds from entering the detector. The representative technology is confocal laser scanning microscopic imaging technology. A pinhole is usually placed at the illumination light source of the confocal laser scanning microscope to produce a focused light point to excite the fluorescent sample. A detection pinhole is placed at the conjugate point of the objective lens focal plane before the imaging detector, so that only the in-focus light rays at the objective lens focal plane can pass through the pinhole and enter the camera to participate in imaging, while the fluorescent signals in the out-of-focus region are blocked outside the detection pinhole. Finally, the three-dimensional structure of the sample can be reconstructed by three-dimensional point-by-point scanning. Thanks to the filtering effect of the detection pinhole, the image collected in the imaging detector effectively removes the out-of-focus background, making the imaging contrast and axial resolution of the confocal microscopic system much better than that of traditional wide-field fluorescence microscopes. SUMMARY

[0006] In order to overcome the problem that the spherical aberration is accumulated due to the refractive index mismatch in the deep processing of the existing large numerical aperture (NA) system, the line width is seriously deteriorated, the light propagation depth is limited, and the processing and characterization are separated in space, a nanoscale spectral depth coding laser direct writing system and an implementation method thereof are provided.

[0007] One object of the present application is to provide a nanoscale spectral depth coding laser direct writing system and an implementation method thereof.

[0008] The nanoscale spectral depth coding laser direct writing system of the present application comprises: an excitation light source, an excitation light spatial light field modulation system, a dichroic mirror, an inhibition light source, an inhibition light spatial light field modulation system, a first thin film beam splitter, a two-dimensional scanning galvanometer, an excitation objective lens, an illumination system, an electrically tunable focusing lens system, a dispersive confocal detection system, and a control device; wherein the two-dimensional scanning galvanometer, the electrically tunable focusing lens system, and the dispersive confocal detection system are connected to the control device; wherein, The femtosecond pulse excitation light generated by the excitation light source is input to the excitation light spatial light field modulation system, and the phase of the excitation light is regulated by loading the excitation light phase hologram calculated by the feedback type non-diffractive axial scanning algorithm, so as to move the focus point without aberration along the optical axis z axis after the excitation objective lens; the excitation light phase hologram is transmitted to the back focal plane of the excitation objective lens by the two-dimensional scanning galvanometer for high-speed two-dimensional plane optical scanning, and is focused to the surface of the sample by the excitation objective lens; The continuous fundamental mode Gaussian light output by the inhibition light source is input to the inhibition light spatial light field modulation system as inhibition light, and the inhibition light phase hologram superimposed with the annular lens and the vortex phase is loaded to convert the spectrum ring of the first-order Bessel beam, which is combined with the excitation light through the dichroic mirror and transmitted to the back focal plane of the excitation objective lens and focused to the surface of the sample by the excitation objective lens; the first-order Bessel beam has the characteristic of no diffraction, and the spot morphology does not change during long-distance transmission, while the Bessel beam generated by the annular lens significantly improves the length of the non-diffractive zone of the traditional Bessel beam, compresses the effective aggregation area of the excitation light, and improves the deep writing precision; The sample is a photoresist with a photoinitiator, which generates free radicals under the irradiation of the excitation light and combines with monomers to form a solid structure; the excitation light with little spherical aberration initiates two-photon polymerization, the inhibition light maintains a stable and uniform hollow morphology, and the self-healing and anti-scattering ability of the inhibition light ensures that the hollow morphology does not deform during deep super-resolution direct writing, and the excitation light with three-dimensional coincidence of femtosecond pulses cooperates to realize deep super-resolution two-photon direct writing; With the sample direct writing process, the sample surface position along the optical axis changes accordingly; the illumination system emits supercontinuum light which is incident through the second thin film beam splitter and the beam splitter mirror, and is focused by the excitation objective lens at different optical axis positions of the sample, only the light with a wavelength that is just focused on the sample surface will be reflected most strongly, realizing the coding of depth information by the wavelength of light; the reflected light returns to the original path, is reflected by the first thin film beam splitter, and passes through the electrically adjustable focus lens system, which adjusts the focal length according to the change of the excitation light along the optical axis position, to ensure that the signal on the detection surface of the detector always comes from the sample layer co-located with the excitation light focal plane, and the focal length is adjusted without changing the overall magnification of the system; the pinhole in the dispersive confocal detection system is in a conjugate position relative to the focal plane of the sample, only the light on the focal plane can pass through the pinhole, and the out-of-focus signal is filtered out and received by the dispersive confocal detection system, the accurate sample optical axis height is calculated by collecting the wavelength of the light beam, and the real-time surface topography of the sample is obtained. By controlling the system, the two-dimensional scanning mirror performs scanning motion in the xy plane, and the electrically adjustable focus lens system, the excitation light and the suppression light spatial light field modulation system are controlled, the phase distribution generated by the feedback type non-diffractive axial scanning algorithm is used to update the excitation light phase hologram of the spatial light field modulation system and the suppression light phase hologram of the suppression light spatial light field modulation system, and the position of the back focal point of the high numerical aperture excitation objective lens on the optical axis z-axis is adjusted without diffraction; the excitation light spatial light field modulation system is controlled to load the corresponding lens phase, and the excitation light and the suppression light are focused on the optical axis. The dispersive confocal detection system collects the reflected light signals of different wavelengths from the sample surface in real time and inputs them into the spectrometer, the spectrometer converts the wavelength information into optical axis position information, and integrates them into a three-dimensional image, realizing real-time in-situ imaging feedback while laser direct writing.

[0009] The sample is placed on the sample holder. The photodetector is connected to the control device, and the photodetector is a photomultiplier tube.

[0010] The application further comprises a photodetector, before laser direct writing, first perform spot calibration, replace the sample with a high reflectivity nanoprobe, and replace the spectrometer in the dispersive confocal detection system with a photodetector; the high reflectivity nanoprobe strongly reflects light into the photodetector, observes the suppression light topography, synchronously optimizes the suppression light spatial light field modulation system to make the suppression light a perfect hollow and symmetrically distributed first-order Bessel light; perfect co-path of excitation light and suppression light is realized through beam combination adjustment mirror, and strict coaxiality of double beams is verified through photodetector.

[0011] The excitation light beam expansion filter system is arranged before the excitation light spatial light field modulation system, filters out high-order modes, retains the fundamental mode, and completes the collimation and expansion of the light beam; the excitation light beam expansion filter system comprises a large focal length input lens, a spatial filter pinhole, and a small focal length output lens; wherein the large focal length input lens converts the incident collimated light into converging light rays, controls the focal spot size of the light beam on the plane of the spatial filter pinhole, and ensures that the aperture is matched with the spatial filter pinhole; the spatial filter pinhole is placed at the focal point position of the large focal length input lens, physically blocks the high-order modes, allows only the fundamental mode to pass, improves the wavefront flatness, and plays a wavefront correction role; the wavefront-corrected light beam passes through the small focal length output lens, outputs an ideal Gaussian profile, expands the light beam to a target diameter, covers the target surface of the excitation light spatial light modulator, and maximizes the use of the phase modulation area.

[0012] The attenuation and isolation system and the excitation light switch are arranged after the excitation light source; the femtosecond pulse excitation light generated by the excitation light source passes through the attenuation and isolation system, and the exposure time of the excitation light is controlled by the excitation light switch to input into the excitation light beam expansion filter system; the excitation light switch is connected to the control system.

[0013] The suppression light switch is arranged after the suppression light source; the continuous fundamental mode Gaussian light output by the suppression light source is used as the suppression light, and the exposure time of the suppression light is controlled by the suppression light switch; the suppression light switch is connected to the control system.

[0014] The 4F relay system is arranged in front of the dichroic mirror, shrinks and perfectly relays the exiting light of the excitation light spatial light field modulation system and the suppression light spatial light field modulation system, and relays the exiting light field to the sample surface.

[0015] The telecentric scanning correction system is arranged between the two-dimensional scanning galvanometer and the excitation objective lens; the light exiting from the excitation light spatial light field modulation system eliminates the vignetting and distortion at the edge of the field of view through the telecentric scanning correction system, and avoids off-axis aberration; the telecentric scanning correction system comprises a telecentric scanning lens and a tube lens; when the incident light beam is angularly deflected relative to the optical axis of the system, the telecentric scanning lens can ensure that the light beam always enters the tube lens in the paraxial condition, maintains the spatial flatness of the imaging plane, and can avoid off-axis aberration; the cooperation of the scanning lens and the tube lens significantly suppresses the f-theta distortion, outputs a geometrically faithful rectangular scanning image, and perfectly adapts to the infinite correction objective lens. If the correction system is missing, the image generated by scanning will present trapezoidal distortion and be accompanied by uneven light field distribution.

[0016] The camera system collects reflected light signals from the sample surface to obtain a macroscopic view of the sample surface, and the macroscopic view of the sample surface is observed by the camera system to assist in observing the position of the laser focal point, so as to ensure that the excitation light and the suppression light are strictly co-axial, and then a lens phase is loaded on the excitation light spatial light modulator to compensate for chromatic aberration caused by the 4F relay system and the telecentric scanning correction system, so that the two light beams are strictly confocal. The camera system comprises a camera and an imaging lens, the camera is a CCD or CMOS camera, and the imaging lens is responsible for converging the incident light to the target surface of the camera for imaging.

[0017] The suppression light is output from the continuous mode Gaussian light source, transmitted to the suppression light polarization maintaining single mode fiber through the suppression light switch, filtered to output only the fundamental mode, corrected for wavefront distortion, and locked for the linear polarization direction of the incident suppression light.

[0018] The excitation light spatial light field modulation system comprises an excitation light half-wave plate, an excitation light quarter-wave plate, an excitation light three-prism and an excitation light spatial light modulator; wherein the excitation light is polarized modulated into left-handed circularly polarized light by the excitation light half-wave plate and the excitation light quarter-wave plate, and then spatial light field modulation is performed by the excitation light three-prism and the excitation light spatial light modulator, so that the polarization state of the incident excitation light spatial light modulator reaches the maximum modulation efficiency; the excitation light spatial light field modulation system is input, the phase of the excitation light is modulated by loading an excitation light phase hologram, and the focusing point is moved without aberration on the optical axis after the excitation objective lens; the required phase distribution is calculated by a feedback type aberration-free axial scanning algorithm, which aims to generate an aberration-free phase that can generate a target optical axis displacement light field. The excitation light spatial light modulator is connected to a control device.

[0019] The suppression light spatial light field modulation system comprises a suppression light half-wave plate, a suppression light quarter-wave plate, a suppression light three-prism and a suppression light spatial light modulator; wherein the suppression light is polarized modulated into left-handed circularly polarized light by the suppression light half-wave plate and the quarter-wave plate, and then converted into a first-order Bessel beam by the suppression light three-prism and the suppression light spatial light modulator, so that the polarization state of the incident suppression light spatial light modulator reaches the maximum modulation efficiency; the suppression light spatial light modulator loads a suppression light phase hologram superimposed with a ring lens and a first-order vortex phase, and the spectrum ring of the first-order Bessel light is emitted and finally relayed to the front focal plane of the excitation objective lens. The suppression light spatial light modulator is connected to a control device.

[0020] The electrically tunable focusing lens system comprises two lenses with the same focal length and an electrically tunable focusing lens; wherein the electrically tunable focusing lens is connected to a control device, and the focal length thereof is dynamically adjusted in real time according to the axial depth of the excitation light in the sample, so as to ensure that the signals on the detection surface of the detector always come from the sample layer co-located with the excitation light focal plane; the electrically tunable focusing lens is arranged between the two lenses with the same focal length, and together forms a Fourier transform system with an equal magnification, so as to ensure that the electrically tunable focusing lens does not change the overall magnification of the system when adjusting the focal length.

[0021] The illumination system comprises a supercontinuum light source, a tuner, a multimode optical fiber and a collimating lens; wherein the supercontinuum light source outputs high-power laser, and the tuner outputs 500-760 nm light to prevent the illumination light from causing polymerization of photoresist; the output light of the tuner enters the collimating lens through the multimode optical fiber, and the collimating lens collimates the white light and then the white light is incident on an excitation objective lens, which focuses light of different wavelengths at different optical axis positions of the sample.

[0022] The dispersive confocal detection system comprises a converging lens, a pinhole and a spectrometer; wherein the pinhole is located in front of the spectrometer, and the spectrometer is connected to a control device; the supercontinuum light output by the illumination system is focused at different optical axis positions of the sample after the excitation objective lens, and only the light with a wavelength that is just focused on the surface of the sample is reflected most strongly, so that the wavelength coding depth information is achieved; the reflected light passes through the pinhole, so that only the in-focus light rays at the focal plane of the excitation objective lens can pass through the pinhole and enter the spectrometer to participate in imaging, while the light in the out-of-focus area is blocked outside the detection pinhole; the spectrometer receives the reflected light signal from the focal point of the excitation objective lens, and transmits the signal to the control device, which converts the wavelength information into optical axis position information, and reconstructs the three-dimensional structure of the sample through three-dimensional point-by-point scanning.

[0023] The control device comprises a data acquisition system (DAQ) and a computer; wherein the computer generates control instructions and transmits the instructions to the DAQ; after receiving the input signals, the DAQ outputs corresponding voltage signals to drive the two-dimensional scanning galvanometer to deflect, so as to accurately control the scanning motion of the focused light spot emitted by the excitation objective lens in the xy plane of the sample; at the same time, the control system calculates the excitation light phase hologram and the annular lens and vortex phase superimposed suppression light phase hologram through a feedback type non-difference axial scanning algorithm, and loads the holograms into the excitation light and suppression light spatial modulators, respectively. This highly synchronized control mechanism enables the system to seamlessly alternate or simultaneously perform photopolymerization and optical imaging operations in situ on the sample, realizes real-time monitoring and feedback of the processing process, and performs in-situ, synchronous and real-time precise processing and high-resolution imaging on the three-dimensional micro-nano structure.

[0024] The photoresist material system comprises a two-photon absorption photoinitiator and a hybrid monomer combination composed of an organic monomer and a metal alkoxide monomer, wherein the molar ratio of the organic monomer to the metal alkoxide monomer ranges from 7:3 to 9:1, and the photoinitiator accounts for 0.5% to 2% of the total weight of the material system. The present application further comprises a phase mask for generating a first-order Bessel light, which can generate a first-order Bessel light with a relatively long non-diffraction zone by loading a ring lens and a vortex phase superimposed on the suppression light phase hologram on the suppression light spatial light modulator, thereby significantly improving the deep processing capability. For the slight distortion of the Bessel light in the deep layer of the sample, the wavefront aberration of the suppression light represented by the Zernike polynomial is measured by an adaptive optical method based on pupil segmentation. Specifically, the entrance pupil of the excitation objective is divided into multiple regions on the suppression light spatial light modulator, and only one region is illuminated at a time, and the isolated fluorescent microspheres are used as probes to scan and record the images formed by the region. By calculating the displacement of the image relative to the reference position, the wavefront gradient is calculated. By repeating this process, the complete wavefront distortion map is reconstructed by calculating and integrating all the gradient information. By calculating the phase pattern conjugate to the wavefront distortion on the suppression light spatial light modulator, the phase pattern is superimposed on the phase mask of the suppression light spatial light modulator. The Bessel light loads the corresponding suppression light phase hologram for modifying the distortion at different depths, and corrects the wavefront distortion on the focal plane of the excitation objective at different depths, thereby completely realizing the same straight writing precision from the surface layer to the deep layer.

[0025] Another object of the present application is to provide a method for implementing a nanoscale spectral depth coding laser direct writing system.

[0026] The method for implementing the nanoscale spectral depth coding laser direct writing system of the present application comprises the following steps: 1) Excitation light path: The femtosecond pulse excitation light generated by the excitation light source is input into the excitation light spatial light field modulation system, and the excitation light phase hologram obtained by the feedback type non-aberration axial scanning algorithm is loaded, so that the excitation light moves along the optical axis after the excitation objective without aberration, and is optically scanned in two dimensions by a two-dimensional scanning galvanometer, and is focused to the surface of the sample by the excitation objective; 2) Suppression light path: The suppression light source outputs continuous mode Gaussian light as suppression light, which is input into the suppression light spatial light field modulation system, and the suppression light phase hologram superimposed with the ring lens and the vortex phase is loaded, which is converted into the spectral ring of the first-order Bessel beam, and is combined with the excitation light, and is focused to the surface of the sample by the excitation objective; 3) Laser direct writing: The excitation light irradiates the sample, and the sample is a photoresist with a photoinitiator, which initiates two-photon polymerization, and the suppression light maintains the morphology without deformation, and cooperates to perform deep super-resolution two-photon direct writing; 4) Obtain the surface morphology of the sample: The illumination system emits supercontinuum light, different wavelengths of light are focused on different optical axis positions of the sample through the excitation objective lens, only the light with a wavelength focused on the surface of the sample is reflected most strongly, and the depth information is encoded by the wavelength of the light; the reflected light returns to the original path, passes through the electrically adjustable focusing lens system, and is filtered and received by the dispersive confocal detection system, the height of the sample along the optical axis is determined according to the wavelength of the light, the real-time surface topography of the sample is obtained, and a three-dimensional image is integrated; 5) Aberration-free direct writing: The control system controls the two-dimensional scanning mirror to perform two-dimensional plane optical scanning, controls the electrically adjustable focusing lens system to adjust the focal length in real time, controls the excitation light and the spatial light field modulation system to update the phase hologram to move along the optical axis without aberration, and the excitation light and the suppression light are confocal along the optical axis, and the sample is directly written without aberration.

[0027] Advantages of the present application: (1) The three-dimensional dispersive confocal point scanning microscopic imaging technology is innovatively fused, the optical axis layering scanning data are collected in real time through the spectrometer, the excitation objective lens light path is shared with the laser direct writing system, the color information of the light is encoded into the depth information of the sample, the nanoscale detection imaging can be realized, the axial sensitivity is significantly improved, and the time and space synchronization of "direct writing-imaging" is achieved; the sample transfer link is eliminated, a process closed loop is established, dynamic feedback is provided for direct writing parameters, and problems such as process interruption, positioning misalignment and late detection of abnormal structures caused by separation of processing and characterization in the traditional process are solved; (2) The first-order Gaussian-Bessel beam is used as the suppression light source, the spherical aberration limitation of the traditional Gaussian beam is broken through, the wavefront distortion at different depths is measured through adaptive optics, the spatial light modulator of the suppression light is used for correction, the hollow spot morphology stability (distortion rate <5%) is maintained in the 200 mu m deep sample, a aberration-free, diffraction-limited Bessel light is formed at the focal point, and super-resolution direct writing is realized; (3) The feedback type aberration-free axial scanning algorithm is used to calculate the phase distribution, the movement of the focal point of the excitation objective lens along the optical axis is realized, the motion artifacts caused by the traditional displacement table of moving the sample are eliminated, and the imaging effect is improved; (4) The polarization maintaining fiber integrated filtering system is used in the suppression light path, the linear polarization state (extinction ratio >20 dB) is maintained while filtering out high-order modes, and the traditional polarizer + half-wave plate combination is replaced; the wavefront distortion introduced by the optical element is eliminated, the spot ellipticity is controlled within 5%, and a high-quality basic light beam is provided for super-resolution direct writing; (5) The pure phase type spatial light modulator is used to replace the combination of the traditional vortex phase plate and the corner cube mirror, and the annular lens is used to generate the Bessel light, so that the light path integration degree is improved, three groups of separate optical elements (vortex plate + corner cube mirror + adjustment mechanism) are eliminated, the demand of the portable precision machining equipment is met, the length of the non-diffraction zone of the Bessel light is significantly improved, the Zernike polynomial correction algorithm can be loaded in the light spatial light modulator, the spherical aberration is corrected in real time, and the problem that the traditional fixed phase element cannot correct the spot appearance is solved; (6) The system establishes a multi-stage linkage dynamic adjustment mechanism, breaks through the static calibration limitation of the traditional direct writing process, first captures the reflected light of the spot through the photoelectric detector, combines the beam combination adjustment mirror to realize the two-dimensional space rough coincidence of the excitation light and the suppression light, then drives the two-dimensional scanning galvanometer to scan the high reflectivity nano probe, analyzes the spot appearance signal at the focus of the excitation objective lens through the photoelectric detector, adjusts the mirror based on the real-time feedback data, and finely adjusts the double-beam common focus; the lens phase is loaded in the excitation light spatial light modulator to compensate for chromatic aberration, so that the double-beam common focus is strictly three-dimensional; finally, the confocal point scanning microscopic imaging module is used to synchronously collect the processing sample appearance data in the direct writing process, dynamically adjusts the laser power / scanning speed and other parameters, realizes the process closed-loop optimization in single processing.

[0028] The application is applied to the fields of high-precision nanometer processing and real-time nondestructive testing, such as preparation and appearance characterization of micro-nano optical elements (such as waveguides, microlens arrays and the like), microstructure manufacturing of integrated optical chips and the like, and provides an advanced solution integrating super-resolution processing and in-situ monitoring for frontier scientific research and high-end manufacturing. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a schematic diagram of an embodiment one of the nanoscale spectral depth coded laser direct writing system of the application; Figure 2 It is a schematic diagram of an embodiment two of the nanoscale spectral depth coded laser direct writing system of the application; Figure 3 It is a simulation result diagram of the embodiment one of the nanoscale spectral depth coded laser direct writing system of the application. DETAILED DESCRIPTION

[0030] The application will be further described below by specific embodiments in combination with the drawings.

[0031] Embodiment one As Figure 1As shown, the nanoscale spectral depth coding laser direct writing system of the embodiment includes: an excitation light source 1, an attenuation and isolation system 2, an excitation light switch S1, an excitation light beam expansion and filtering system 3, an excitation light spatial light field modulation system 4, a first 4F relay system 5, a second 4F relay system 6, a third 4F relay system 10, an inhibition light source 7, an inhibition light switch S2, an inhibition light polarization maintaining single mode fiber 8, an inhibition light spatial light field modulation system 9, a first to third thin film beam splitter, a beam combination dichroic mirror 12, a two-dimensional scanning galvanometer 13, a telecentric scanning correction system 14, an excitation objective lens 15, a sample holder 16, an illumination system 17, a camera system 18, an electrically tunable focusing lens system 19, a photodetector, a dispersion confocal detection system 20, and a control device; wherein the two-dimensional scanning galvanometer 13, the excitation light switch S1, the inhibition light switch S2, the electrically tunable focusing lens system 19, and the dispersion confocal detection system 20 are connected to the control device.

[0032] The excitation light source 1 generates femtosecond pulse excitation light, which passes through the attenuation and isolation system 2 to the excitation light switch S1; the exposure time of the excitation light is controlled by the excitation light switch S1 and input to the excitation light beam expansion and filtering system 3. The attenuation and isolation system 2 includes an attenuation sheet 2-2 and an optical isolator 2-1.

[0033] The excitation light beam expansion and filtering system 3 filters out high-order modes and retains the fundamental mode, and completes the collimation and expansion of the light beam; the excitation light beam expansion and filtering system 3 includes a large focal length input lens 3-1, a spatial filtering pinhole 3-2, and a small focal length output lens 3-3; wherein the large focal length input lens converts the incident collimated light into convergent light rays, controls the focal spot size of the light beam in the spatial filtering pinhole plane, and ensures that the aperture is matched with the spatial filtering pinhole; the spatial filtering pinhole is placed at the focal point position of the large focal length input lens, physically blocks high-order modes, and only allows the fundamental mode to pass through, improves the wavefront flatness, and plays a wavefront correction role; the wavefront corrected light beam passes through the small focal length output lens, outputs an ideal Gaussian profile, expands the light beam to the target diameter, covers the target surface of the excitation light spatial light modulator, and maximizes the use of the phase modulation area.

[0034] The excitation light spatial light field modulation system 4 comprises an excitation light half-wave plate 4-1, an excitation light quarter-wave plate 4-2, an excitation light triangular prism 4-3 and an excitation light spatial light modulator 4-4; wherein the excitation light is subjected to polarization modulation into left circularly polarized light by the excitation light half-wave plate and the excitation light quarter-wave plate, and then subjected to spatial light field modulation by the excitation light triangular prism and the excitation light spatial light modulator, so that the polarization state of the excitation light incident on the suppression light spatial light modulator reaches the maximum modulation efficiency; the apex angle of the excitation light triangular prism 4-3 is 96°, which is used for folding the light path; the excitation light is input into the excitation light spatial light modulator 4-4, and the phase of the excitation light is modulated by loading an excitation light phase hologram, so that the focal point is moved along the optical axis behind the excitation objective lens 15 without aberration; the excitation light phase hologram is calculated by a feedback type aberration-free axial scanning algorithm, so that the focal point is moved along the optical axis (z-axis) behind the excitation objective lens 15 without aberration. The suppression light spatial light modulator is connected to the control device.

[0035] After being transmitted through the beam-combining dichroic mirror 12, the excitation light is transmitted to the two-dimensional scanning galvanometer 13 to perform optical scanning in a horizontal high-speed two-dimensional plane (xy plane), and the excitation light phase hologram is relayed to the back focal plane of the excitation objective lens 15 through the first 4F relay system 5, the second 4F relay system 6 and the telecentric scanning correction system 14, and is focused to the surface of the sample by the excitation objective lens 15.

[0036] The telecentric scanning correction system 14 is arranged between the two-dimensional scanning galvanometer 13 and the excitation objective lens 15; the light output from the excitation light spatial light modulator is subjected to the telecentric scanning correction system 14 to eliminate the vignetting and distortion at the edge of the field of view, so as to avoid off-axis aberration; the telecentric scanning correction system 14 comprises a telecentric scanning lens 14-1 and a tube lens 14-2; when the incident light beam is angularly deflected relative to the optical axis of the system, the telecentric scanning lens can ensure that the light beam is always incident into the tube lens in the paraxial condition, so as to maintain the spatial flatness of the imaging plane, and at the same time, off-axis aberration can be avoided; the cooperation of the scanning lens and the tube lens significantly suppresses the f-theta distortion, and outputs a geometrically faithful rectangular scanning image, which perfectly adapts to the telecentric correction objective lens. If the telecentric scanning correction system is missing, the image generated by scanning will present trapezoidal distortion, accompanied by uneven light field distribution.

[0037] The sample is placed on the sample holder 16.

[0038] The suppression light source 7 outputs continuous fundamental mode Gaussian light as suppression light, and the exposure time of the suppression light is controlled by the suppression light optical switch; the suppression light is transmitted into the suppression light polarization maintaining single mode optical fiber 8, high-order modes are filtered out and the polarization state is maintained; and the suppression light is input into the suppression light spatial light field modulation system 9.

[0039] The inhibiting light spatial light field modulation system 9 comprises an inhibiting light half-wave plate 9-1, an inhibiting light quarter-wave plate 9-2, an inhibiting light triangular prism 9-3 and an inhibiting light spatial light modulator 9-4; wherein the inhibiting light is polarized modulated into left circularly polarized light by the inhibiting light half-wave plate and the inhibiting light quarter-wave plate, and then is converted into a first-order Bessel beam by the inhibiting light triangular prism and the inhibiting light spatial light modulator; the polarization state of the inhibiting light incident to the inhibiting light spatial light modulator should be adjusted to achieve maximum modulation efficiency; the inhibiting light spatial light modulator is loaded with an inhibiting light phase hologram superimposed with a ring lens and a first-order vortex phase, and a spectral ring of the first-order Bessel light is emitted; the final light field is relayed to the back focal plane of the excitation objective 15, combined with the excitation light after passing through the first thin film beam splitter 11-1 and the beam combining dichroic mirror 12, transmitted to the two-dimensional scanning galvanometer 13, and then relayed to the middle position of the two-dimensional scanning galvanometer 13 through the third 4F relay system 10, and then relayed to the back focal plane of the excitation objective 15 by the telecentric scanning correction system 14, and focused to the surface of the sample by the excitation objective 15; the first-order Bessel light has no diffraction characteristics, and the spot morphology does not change during long-distance transmission; the Bessel light generated by the ring lens compresses the effective aggregation area of the excitation light, significantly improves the length of the non-diffraction area, and improves the deep direct writing precision; and the inhibiting light spatial light modulator is connected to the control device.

[0040] The illumination system 17 comprises a supercontinuum light source, a tuner, a multi-mode optical fiber and a collimating lens; wherein the supercontinuum light source outputs a high-power supercontinuum white light, and the tuner outputs 500-760nm light to prevent the illumination light from causing polymerization of the photoresist; the output light of the tuner enters the collimating lens through the multi-mode optical fiber, and the white light is collimated; the collimated light is reflected by the second thin film beam splitter 11-2, and then is incident to the excitation objective 15; and the excitation objective 15 focuses different wavelengths of light at different optical axis positions of the sample.

[0041] The dispersion confocal detection system 20 comprises a collimating lens, a converging lens 20-1, a pinhole 20-2 and a spectrometer 20-3; wherein the excitation objective 15 focuses light of different wavelengths at different optical axis positions of the sample, only the light of the wavelength that is just focused on the surface of the sample is reflected most strongly, realizing the coding of depth information by using the wavelength of light; the reflected light returns to the original path, is split by the beam combiner dichroic mirror 12 and the excitation light, is reflected by the first thin film beam splitter 11-1, enters the pinhole in front of the spectrometer through the electrically tunable focusing lens system 19, the pinhole is at a conjugate position relative to the focal plane of the sample, only the light on the focal plane can pass through the pinhole, so that only the in-focus light at the focal plane of the excitation objective 15 can pass through the pinhole to enter the spectrometer to participate in imaging, while the light in the out-of-focus area is blocked outside the detection pinhole, the spectrometer receives the reflected light signal from the focal point of the excitation objective 15, and converts the wavelength information into optical axis position information, realizing accurate determination of the height of the optical axis of the sample; the electrically tunable focusing lens system 19 adjusts the focal length according to the change of the excitation light along the optical axis position, so that the reflected light of different optical axis positions in the sample can be focused on the detection surface of the dispersion confocal detection system 20; the pinhole in the dispersion confocal detection system 20 receives the reflected light after filtering out the out-of-focus signal, and transmits it to the control device to obtain the real-time surface topography of the sample, and the three-dimensional structure of the sample is reconstructed by three-dimensional point-by-point scanning, and the three-dimensional image of the sample is obtained, realizing in-situ imaging feedback while realizing laser direct writing.

[0042] The camera system 18 comprises a camera 18-2 and an imaging lens 18-1; wherein the reflected light signal of the sample surface is reflected to the camera system 18 through the third thin film beam splitter 11-3, is converged to the camera target surface through the imaging lens, and is received by the camera to obtain the macroscopic field of view of the sample surface; the macroscopic field of view of the sample surface is observed through the camera system 18, the excitation light and the suppression light are strictly co-routed, the lens phase is loaded on the excitation light spatial light modulator to compensate for the chromatic aberration caused by the 4F relay system and the telecentric scanning correction system 14, and the double-beam is strictly confocal. The camera adopts a CCD or CMOS camera, and the imaging lens is responsible for imaging the incident light.

[0043] The electrically tunable focusing lens system 19 comprises two first 4F lenses 19-1 and second 4F lenses 19-3 with the same focal length and an electrically tunable focusing lens 19-2; wherein the electrically tunable focusing lens is connected to the control device, 19-2 is connected to the axial depth of the excitation light in the sample, and adjusts its focal length in real time and dynamically to ensure that the signal on the detection surface of the detector always comes from the sample layer co-located with the focal plane of the excitation light; the electrically tunable focusing lens 19-2 is arranged between the two first 4F lenses 19-1 and second 4F lenses 19-3 with the same focal length, and together forms a Fourier transform system with equal magnification, so as to ensure that the electrically tunable focusing lens does not change the overall magnification of the system when adjusting the focal length.

[0044] Before laser direct writing, first carry out spot calibration: replace the sample with a high reflectivity nanoprobe, and replace the spectrometer in the dispersive confocal detection system 20 with a photodetector connected to a control device, which uses a photomultiplier tube; the high reflectivity nanoprobe strongly reflects light into the photodetector, and the photodetector observes the suppression light pattern; the suppression light is simultaneously optimized by the spatial light field modulation system 9 to make the suppression light a perfect hollow and symmetrically distributed first-order Bessel light; perfect co-routing of the excitation light and the suppression light is achieved by adjusting a pair of beam combining adjustment mirrors M1 and M2 located in front of the beam combining dichroic mirror 12.

[0045] The control device includes a data acquisition system (DAQ) and a computer; the computer generates control instructions and transmits them to the DAQ; after receiving the input signal, the DAQ outputs a corresponding voltage signal to drive the two-dimensional scanning galvanometer 13 to deflect, thereby accurately controlling the scanning motion of the focused light spot emitted by the objective lens in the sample xy plane.

[0046] M in the figure is a mirror. Each 4F relay system includes coaxially arranged input and output lenses.

[0047] In this embodiment, the excitation light source 1 uses a femtosecond pulsed laser with a center wavelength of 780nm, a pulse width of 100fs, and a repetition frequency of 80MHz; the suppression light source 7 uses a 532nm continuous-wave laser. After passing through the beam expanding and filtering system 3, the excitation light source 1 is expanded to a diameter of approximately 12mm, and then through the subsequent 4F relay system 5, the diameter of the light spot incident on the entrance pupil of the excitation objective lens 15 is approximately 110% of the entrance pupil of the objective lens; the excitation light spatial light modulator 4-4 uses a pure phase-type silicon-based liquid device to cyclically display a set of 20 phase holograms. These holograms are generated by a feedback-based aberration-free axial scanning algorithm, and each image corresponds to a specific position of the excitation light on the Z-axis; in terms of optical path layout, in order to maintain the high modulation efficiency of the excitation light spatial light modulator while ensuring spatial separation of the incident light and the reflected light, its maximum incident angle is set to 6°. To this end, prisms 4-3 and 9-3 with a vertex angle of 96° were configured, and the incident light was precisely controlled to form a 6° angle with the surface normals of the excitation light spatial light modulator 4-4 and the suppression light spatial light modulator 9-4. The excitation objective 15 used was a Nikon plan-field apochromatic immersion objective with a magnification of 60x, an NA of 1.27, and a working distance of 0.16mm-0.18mm. In this embodiment, the direct-write photoresist material system uses BIS (tetraethyl Michlechne) as a photoinitiator, MAPTMS (methacryloyloxypropyltrimethoxysilane) and ZPO (n-zirconium propoxide) as monomers, and is formulated in a molar ratio of MAPTMS:ZPO = 8:2, with BIS accounting for 1% of the total weight, to achieve 780nm femtosecond light excitation and 532nm continuous light suppression of photopolymerization reaction; the camera 18-2 is a CCD, and the beam combiner dichroic mirror 12 is a 775nm short-pass dichroic mirror, which reflects the excitation light and transmits the suppression light. This invention employs a pulsed excitation mechanism, which has the advantages of two-photon aggregation effect: it can achieve sub-diffraction-limited linewidth, improve longitudinal resolution, and enhance deep penetration capability.

[0048] Example 2 like Figure 2 As shown, in this embodiment, the excitation objective 15 is placed in an inverted position. The beam after passing through the telecentric scanning correction system 14 first passes through the second and third thin-film beam splitters 11-2 and 11-3, and then enters the excitation objective 15 through the reflecting mirror M. Above the excitation objective 15 is the sample holder 16 for placing the sample. The camera system 18 and the supercontinuum light source 17 are introduced into the beam combining path through the second thin-film beam splitter 11-2 and the third thin-film beam splitter 11-3, respectively. Other aspects are the same as in Embodiment 1.

[0049] The process of calculating the phase hologram using the feedback-based aberration-free axial scanning algorithm is as follows: According to the vector light field diffraction theory, the process of the incident light field being focused by the objective lens is mainly a diffraction process; the intensity distribution of the incident light field incident on the excitation light spatial light modulator is as follows: The desired intensity distribution of the target light field is as follows: The space-excitation inter-optical modulator is a pure phase type; only the phase distribution to be modulated on the incident light field needs to be obtained to obtain the corresponding target light field. The feedback-type aberration-free axial scanning algorithm of this invention is as follows: First, a random phase distribution is added to the incident light field with a known intensity distribution. Incident light field After one diffraction calculation, the target light field after the first calculation is obtained. , These are the intensity and phase distributions of the target light field calculated in the first diffraction; the intensity distribution of the target light field calculated in the first diffraction... Replace with the desired intensity distribution of the target light field Then, inverse diffraction calculations were performed to obtain the incident light field corresponding to the first inverse diffraction calculation. , and The intensity and phase distributions of the incident light field calculated from the first inverse diffraction are obtained separately; the intensity distribution of the incident light field calculated from the first diffraction is then... Replace with the intensity distribution of the incident light field Then a second diffraction calculation is performed to obtain the target light field. , and The intensity and phase distributions of the target light field calculated in the second diffraction are respectively; the intensity distribution of the target light field calculated in the second diffraction is... Replace with the intensity distribution of the target light field Then, inverse diffraction calculations were performed to obtain the incident light field corresponding to the second inverse diffraction calculation. , and The intensity and phase distributions of the incident light field were calculated separately for the second inverse diffraction; the above steps were repeated for a total of After the operation, we get the first... The target light field calculated by secondary diffraction , and The first The intensity and phase distribution of the target light field calculated by the second diffraction, and the third Incident light field calculated by secondary reverse diffraction , and The first The intensity and phase distribution of the incident light field calculated by the second inverse diffraction. For a natural number ≥ 1, the intensity distribution of the target light field is used as the evaluation criterion for the feedback mechanism. When the th... Intensity distribution of the target light field calculated by secondary diffraction With the target light field the difference between the intensity distribution of the first diffraction calculation and the intensity distribution of the second diffraction calculation is within a set threshold or reaches a set number of iterations the phase distribution of the incident light field of the second diffraction calculation is the phase distribution to be loaded on the spatial light modulator of the excitation light for modulation.

[0050] Figure 3 Theoretical direct writing line width of the present embodiment and conventional STED super-resolution laser direct writing (inhibitory light uses first-order Laguerre-Gaussian LG light) at different depths of the sample is shown. By using the tightly focused Debye vector diffraction integral model and the photopolymerization theoretical model, it can be simulated by matlab that, at the surface layer (depth d=0 μm), the conventional STED system and the deep-layer STED super-resolution system have the same super-resolution direct writing line width under the same inhibitory light power, while at the deep layer of the sample, the deep-layer STED super-resolution system using first-order Bessel light has obviously superior super-resolution direct writing ability. Gaussian excitation light is widened by spherical aberration at the deep layer, so that the direct writing line width increases, and in order to achieve the same direct writing precision, the inhibitory light power needs to be increased. After compensating the inhibitory light power, the deep-layer STED super-resolution system can achieve almost the same direct writing precision as the surface layer, while the conventional STED system using LG light still has serious degradation of super-resolution line width even under large inhibitory light power. Therefore, it is theoretically proved that the deep-layer STED super-resolution system using first-order Bessel light as inhibitory light has more excellent deep-layer super-resolution laser direct writing ability than the conventional STED system.

[0051] Finally, it should be noted that the purpose of the disclosed embodiments is to help further understand the present application, but those skilled in the art can understand that various replacements and modifications are possible without departing from the spirit and scope of the present application and the appended claims. Therefore, the present application should not be limited to the disclosed content of the embodiments, and the scope of the present application claimed is defined by the scope of the claims.

Claims

1. A nanoscale spectrally deep encoded laser direct writing system, characterized in that, The laser direct writing system comprises: an excitation light source, an excitation light spatial light field modulation system, a dichroic mirror, an inhibition light source, an inhibition light spatial light field modulation system, a first thin film beam splitter, a two-dimensional scanning galvanometer, an excitation objective lens, an illumination system, an electrically tunable focusing lens system, a dispersive confocal detection system, and a control device; wherein the two-dimensional scanning galvanometer, the electrically tunable focusing lens system, and the dispersive confocal detection system are connected to the control device; wherein The femtosecond pulse excitation light generated by the excitation light source is input into the excitation light spatial light field modulation system, loaded with the excitation light phase hologram obtained by the feedback-free aberration axial scanning algorithm, so that the excitation light moves along the optical axis after the excitation objective lens without aberration, is two-dimensionally planarly scanned by the two-dimensional scanning galvanometer, and is focused by the excitation objective lens to the surface of the sample; The continuous fundamental mode Gaussian light output by the inhibition light source is input into the inhibition light spatial light field modulation system as inhibition light, loaded with the inhibition light phase hologram superimposed by the annular lens and the vortex phase, converted into the spectral ring of the first-order Bessel beam, combined with the excitation light, and focused by the excitation objective lens to the surface of the sample; The sample is a photoresist with a photoinitiator, the excitation light irradiation initiates two-photon polymerization, and the inhibition light maintains the morphology without deformation, and cooperates with the excitation light to perform deep super-resolution two-photon direct writing; The illumination system emits supercontinuum light, different wavelengths of light are focused at different optical axis positions of the sample through the excitation objective lens, only the light with a wavelength focused on the surface of the sample is reflected most strongly, the depth information is coded by the wavelength of the light, the reflected light returns along the original path, passes through the electrically tunable focusing lens system, and is filtered and received by the dispersive confocal detection system, the height of the sample along the optical axis is determined according to the wavelength of the light, the real-time surface morphology of the sample is obtained, and a three-dimensional image is integrated; The control system controls the two-dimensional scanning galvanometer to perform two-dimensional planar optical scanning, controls the electrically tunable focusing lens system to adjust the focal length in real time, and controls the excitation light and the inhibition light spatial light field modulation system to update the phase hologram to move along the optical axis without aberration, and directly writes the sample without aberration.

2. The direct write laser system of claim 1, wherein, Further comprising an excitation light beam expansion filtering system, the excitation light beam expansion filtering system is arranged before the excitation light spatial light field modulation system; the excitation light beam expansion filtering system comprises: a large focal length input lens, a spatial filtering pinhole, and a small focal length output lens; wherein the large focal length input lens converts the incident collimated light into converging light rays, controls the focal spot size of the light beam on the spatial filtering pinhole plane, and ensures that the aperture is matched with the spatial filtering pinhole; the spatial filtering pinhole is placed at the focal point position of the large focal length input lens, physically blocks high-order modes, and only allows the fundamental mode to pass, thereby playing a wavefront correction role; the wavefront-corrected light beam passes through the small focal length output lens, outputs a Gaussian profile, expands the light beam to the target diameter, and covers the target surface of the excitation light spatial light modulator.

3. The direct-write laser system of claim 1 or 2, wherein, Further comprising a camera system, the camera system collects reflected light signals from the surface of the sample, obtains a macroscopic field of view of the surface of the sample, assists in observing the position of the laser focus, ensures that the excitation light and the inhibition light are loaded with lens phases on the excitation light spatial light modulator after being combined, compensates for chromatic aberration, and makes the two beams confocal.

4. The direct write laser system of claim 1, wherein, The suppression light spatial light field modulation system comprises a suppression light half-wave plate, a suppression light quarter-wave plate, a suppression light triangular prism and a suppression light spatial light modulator; wherein the suppression light is subjected to polarization modulation into left circularly polarized light by the suppression light half-wave plate and the suppression light quarter-wave plate, and then is converted into a first-order Bessel beam by the suppression light triangular prism and the suppression light spatial light modulator; the suppression light spatial light modulator is loaded with a suppression light phase hologram superimposed with a ring lens and a first-order vortex phase, and a first-order Bessel light is emitted.

5. The direct write laser system of claim 1, wherein, The excitation light spatial light field modulation system comprises an excitation light half-wave plate, an excitation light quarter-wave plate, an excitation light triangular prism and an excitation light spatial light modulator; wherein the excitation light is subjected to polarization modulation into left circularly polarized light by the excitation light half-wave plate and the excitation light quarter-wave plate, and then is subjected to spatial light field modulation by the excitation light triangular prism and the excitation light spatial light modulator; the excitation light spatial light field modulation system adjusts the phase of the excitation light by loading an excitation light phase hologram, so as to move the focal point along the optical axis after the excitation objective lens without aberration; the excitation light phase hologram is calculated by a feedback type aberration-free axial scanning algorithm.

6. The direct write laser system of claim 1, wherein, The dispersion confocal detection system comprises a converging lens, a pinhole and a spectrometer; wherein the supercontinuum light output by the illumination system is focused on different optical axis positions of the sample after the excitation objective lens, and only the light with a wavelength that is just focused on the surface of the sample is reflected most strongly, so that the wavelength coding depth information of light is utilized; the reflected light passes through the pinhole, so that only the in-focus light rays at the focal plane of the excitation objective lens can pass through the pinhole and enter the spectrometer to participate in imaging, while the signals in the out-of-focus area are blocked outside the detection pinhole; the spectrometer receives the reflected light from the focal point of the excitation objective lens, and converts the wavelength into optical axis position information, so as to reconstruct the three-dimensional structure of the sample.

7. The laser direct writing system of claim 6, wherein, Further comprising a photodetector, before laser direct writing, the sample is replaced with a high-reflectivity nanoprobe, and the spectrometer in the dispersion confocal detection system is replaced with a photodetector; the high-reflectivity nanoprobe strongly reflects light into the photodetector, the morphology of the suppression light is observed, the suppression light phase hologram loaded by the suppression light spatial light field modulation system is optimized synchronously, so that the suppression light becomes a hollow and symmetric first-order Bessel light; the excitation light and the suppression light are made to be in the same path by a beam combination adjusting mirror, and the coaxiality of the two beams is verified by the photodetector.

8. The direct write laser system of claim 1, wherein, The photoresist material comprises a two-photon absorption photoinitiator and a hybrid monomer combination composed of an organic monomer and a metal alkoxide monomer, wherein the molar ratio of the organic monomer to the metal alkoxide monomer ranges from 7:3 to 9:1, and the photoinitiator accounts for 0.5% to 2% of the total weight of the material system.

9. A method of implementing a nanoscale spectrally- deep coded laser direct writing system according to claim 1, characterized in that, The implementation method comprises the following steps: 1) excitation light path: The femtosecond pulse excitation light generated by the excitation light source is input into the excitation light spatial light field modulation system, and the excitation light phase hologram obtained by the feedback type aberration-free axial scanning algorithm is loaded, so that the excitation light moves along the optical axis after the excitation objective lens without aberration, is subjected to two-dimensional plane optical scanning by a two-dimensional scanning galvanometer, and is focused on the surface of the sample by the excitation objective lens; 2) suppression light path: The continuous mode Gaussian light outputted by the suppression light source is inputted into the suppression light spatial light field modulation system as the suppression light, and the annular lens and the suppression light phase hologram with superimposed vortex phase are loaded to convert the frequency spectrum ring of the first-order Bessel beam, and then the first-order Bessel beam is combined with the excitation light and focused on the sample surface by the excitation objective lens; 3) Laser direct writing: The excitation light irradiates the sample, and the sample is a photoresist with a photoinitiator, which initiates two-photon polymerization, and the suppression light maintains the morphology without deformation, and cooperates with the excitation light to perform deep super-resolution two-photon direct writing; 4) Obtain the sample surface morphology: The illumination system emits supercontinuum light, and different wavelengths of light are focused on different optical axis positions of the sample through the excitation objective lens. Only the light with a wavelength focused on the sample surface will be reflected most strongly, and the wavelength coding depth information of the light is used; the reflected light returns to the original path, passes through the electrically adjustable focusing lens system, and is filtered and received by the dispersive confocal detection system. According to the wavelength of the light, the height of the sample along the optical axis is determined, the real-time surface morphology of the sample is obtained, and a three-dimensional image is integrated; 5) Aberration-free direct writing: The control system controls the two-dimensional scanning galvanometer to perform two-dimensional plane optical scanning, controls the electrically adjustable focusing lens system to adjust the focal length in real time, and controls the excitation light and the suppression light spatial light field modulation system to update the phase hologram along the optical axis without aberration. Move to perform aberration-free direct writing on the sample.

10. The implementation method of claim 9, wherein, Before laser direct writing, first perform spot calibration, replace the sample with a high-reflectivity nanoprobe, and replace the spectrometer in the dispersive confocal detection system with a photodetector; the high-reflectivity nanoprobe strongly reflects the light into the photodetector, and the suppression light morphology is observed. Synchronously optimize the suppression light spatial light field modulation system to make the suppression light a hollow and symmetric first-order Bessel beam; through the beam combination adjustment mirror, the excitation light and the suppression light are realized in the same path, and the coaxiality of the two beams is verified through the photodetector.

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