Two-photon lithography 3D printing system based on high-repetition-rate femtosecond laser pulse trains

Abstract

A two-photon lithography 3D printing system based on high-repetition-rate femtosecond laser pulse trains. The system comprises a laser source module (101), a laser transmission system (102), a sample displacement system (103), a monitoring system (104) and a programmable terminal (105). The laser source module (101) outputs laser, and the laser is focused into a photoresist by means of the laser transmission system (102). The programmable terminal (105) is separately connected to the laser source module (101), the laser transmission system (102), the sample displacement system (103) and the monitoring system (104), and is used for controlling the entire printing process. The laser source module (101) has the characteristics of high power, high repetition rate, high stability and the like. In addition to being used for conventional high-resolution small-format two-photon lithography 3D printing, the system can also be used for long-focal-length large-format two-photon lithography 3D printing, and has important application value in the field of micro / nano fabrication.

Description

A high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system Technical Field

[0001] This invention belongs to the field of 3D printing technology, specifically relating to a high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system. Background Technology

[0002] 3D printing technology, as an advanced manufacturing technology, has been widely applied. Among them, two-photon lithography 3D printing technology, due to its high resolution, has significant application value in the field of micro-nano manufacturing. Two-photon lithography 3D printing technology utilizes the two-photon absorption effect, using high-energy laser pulses to initiate a reaction in the photoresist, thereby achieving the curing and shaping of the photoresist. This technology can achieve sub-micron level spatial resolution and is suitable for manufacturing complex 3D micro-nano structures.

[0003] Traditional two-photon lithography 3D printing systems mostly use free-space lasers (such as Ti:sapphire lasers) as the light source, utilizing the characteristics of femtosecond lasers to achieve high-resolution three-dimensional two-photon lithography 3D printing (an integrated two-photon polymerization processing equipment, authorized publication number CN221019124U). These lasers suffer from drawbacks such as low integration, system complexity, environmental sensitivity, low pulse energy, and insufficient stability, and are not suitable for large-format two-photon lithography 3D printing. In recent years, high-power femtosecond fiber lasers have become a research hotspot due to their compactness and anti-interference capabilities. High-repetition-rate femtosecond fiber lasers, with their advantages of high repetition frequency of ultrashort fiber resonators, strong anti-interference capabilities, low phase noise, and the ability to output in pulse train mode through modulation, can effectively solve the light source problem of traditional two-photon lithography 3D printing systems. By adjusting parameters such as pulse train frequency, modulation depth, and duty cycle, these lasers can achieve large-format processing that is difficult to achieve with traditional two-photon lithography 3D printing systems. Summary of the Invention

[0004] The purpose of this invention is to provide a high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system, which can not only realize conventional high-resolution two-photon lithography 3D printing, but also be used for large-format two-photon lithography 3D printing.

[0005] The objective of this invention is achieved by at least one of the following technical solutions.

[0006] A high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system includes a laser source module, a laser transmission system, a sample displacement system, a monitoring system, and a programmable terminal;

[0007] The laser source module outputs pulsed laser light of a set wavelength to the laser transmission system. The laser transmission system focuses the pulsed laser light and controls the scanning of the laser spot. The sample displacement system carries and moves the photoresist. The monitoring system monitors the printing process in real time and determines the position of the laser spot. Based on feedback from the monitoring system, the sample displacement system is adjusted to ensure that the initial position of the laser spot is within the photoresist. A programmable terminal connects to the laser transmission system, sample displacement system, and monitoring system to control the printing process.

[0008] The programmable terminal uses software to pre-slice the required 3D printed model in the horizontal direction and generate the scanning trajectory of each slice.

[0009] During the printing process, the programmable terminal controls the galvanometer in the laser transmission system and the three-dimensional motion platform in the sample displacement system to ensure that the laser spot moves along a predetermined trajectory. After each layer of slices is printed, the three-dimensional motion platform drives the photoresist to move a set distance in the vertical direction before printing the next layer of slices, until all slices are printed.

[0010] Furthermore, the laser source module includes a mode-locked seed laser, a high repetition rate pulse train fiber amplifier, a dispersion compensator, and a frequency doubling module connected in sequence.

[0011] The mode-locked seed laser outputs a pulsed laser of a set wavelength. The power of the pulsed laser is first amplified by a high repetition rate pulse train fiber amplifier, then the pulse width of the pulsed laser is compressed by a dispersion compensator, and finally the frequency is multiplied by a frequency doubling module to output a high repetition rate pulsed laser of the set wavelength.

[0012] Furthermore, the laser transmission system includes a mirror group, a galvanometer, and a lens group, used to focus the pulsed laser onto the photoresist and control the scanning of the laser spot:

[0013] The pulsed laser output from the laser source module enters the galvanometer through the reflector group of the laser transmission system. The galvanometer controls the laser spot to scan the pattern. Finally, the pulsed laser is focused into the photoresist through the lens group, controlling the laser spot to scan in the photoresist.

[0014] Furthermore, the sample displacement system includes a three-dimensional motion platform for carrying the photoresist and positioning it in the X, Y, and Z directions;

[0015] The sample stage carrying the photoresist is placed on top of the three-dimensional motion platform. The initial coordinate system is set through the programmable terminal. The X-axis translation stage in the three-dimensional motion platform is used to move the sample stage horizontally in the X direction; the Y-axis translation stage in the three-dimensional motion platform is used to move the sample stage horizontally in the Y direction, and the angle between the Y-axis and the X-axis is 90°; the Z-axis lifting stage in the three-dimensional motion platform is used to move the sample stage vertically in the Z direction, and the angle between the Z-axis and the X-axis and Y-axis is 90°. After each layer of slice is printed, the Z-axis lifting stage moves the sample stage vertically a set distance before printing the next layer of slice.

[0016] Furthermore, the monitoring system is coupled to the laser transmission system via a dichroic mirror, and includes a beam splitter, an image sensor, and an illumination source, for real-time monitoring of the printing process.

[0017] Beam splitters are used to deflect the illumination light generated by the illumination source; the illumination source provides the illumination light required for monitoring, ensuring that the image sensor can clearly capture images during the printing process; the image sensor is a CCD or CMOS camera, which is coupled to the optical path of the laser transmission system through a dichroic mirror to capture image information during the printing process in real time.

[0018] Furthermore, the programmable terminal connects to the laser source module, laser transmission system, sample displacement system, and monitoring system to comprehensively control the printing process, as detailed below:

[0019] The programmable terminal controls the mode-locked seed laser in the laser source module, including starting, stopping, intensity adjustment, and pulse train modulation, ensuring stable operation of the mode-locked seed laser during printing. The programmable terminal also controls the scanning of the galvanometer and the switching of the optical path in the laser transmission system, ensuring accurate pulsed laser output when needed. Furthermore, the programmable terminal controls the motion trajectory and speed of the three-dimensional motion platform in the sample displacement system, ensuring high-precision positioning during printing. Finally, the programmable terminal controls the operation of the image sensor and imaging software in the monitoring system, monitoring the printing process in real time to ensure printing accuracy and quality. Based on feedback from the monitoring system, the programmable terminal adjusts the sample displacement system to ensure the initial position of the laser spot is within the photoresist.

[0020] Furthermore, in the laser source module, mode-locking technology based on an ultrashort fiber resonator is used for seed laser mode locking;

[0021] The mode-locked seed laser employs an ultrashort fiber resonator laser and utilizes a semiconductor saturable absorber mirror to achieve passive mode-locking, with a repetition frequency ≥1GHz and a power fluctuation RMS value ≤5%.

[0022] The dispersion compensator is used to compress the pulse width of the pulsed laser to ≤300 fs;

[0023] The high repetition rate pulse train fiber amplifier enables pulsed laser to be output in pulse train mode through modulation, with the frequency of the pulse train being 1kHz-10MHz.

[0024] Furthermore, the laser transmission system can switch between a lens group and a long focal length field lens. When using a lens group, 3D printing with a spatial resolution of ≤500nm can be achieved; when using a long focal length field lens to replace the lens group, large-format 3D printing with a range of ≥10×10mm² can be achieved.

[0025] The lens group includes a scanning lens, a barrel lens, and an objective lens. The scanning lens is responsible for focusing the pulsed laser output from the galvanometer and focusing it on the desired plane. The barrel lens is responsible for relay imaging and extending the length of the laser transmission system. The objective lens is responsible for focusing the pulsed laser into the photoresist.

[0026] Furthermore, the step resolution of the X-axis translation stage and the Y-axis translation stage in the three-dimensional motion platform is ≤1μm;

[0027] The stepping resolution of the Z-axis lifting stage in the three-dimensional motion platform is ≤1μm.

[0028] Furthermore, the illumination source of the monitoring system has a wavelength of 600nm~700nm, and the dichroic mirror reflects 780nm laser light and transmits monitoring bands with wavelengths shorter than 780nm.

[0029] Compared with the prior art, the advantages of this invention are:

[0030] This invention innovatively proposes a high-power GHz fundamental frequency mode-locked laser as the laser source module (101) of a two-photon lithography 3D printing system. It adopts an all-fiber integrated ultrashort fiber resonator mode-locked laser, combined with dispersion compensation and nonlinear dynamics control, to achieve femtosecond pulse train output with high repetition rate and high power stability. It has the following core technological breakthroughs:

[0031] (1) Optimize the design of the resonant cavity structure of the GHz fundamental frequency fiber laser and achieve broadband output of the GHz fundamental frequency fiber laser by adjusting the net dispersion in the cavity;

[0032] (2) A fiber resonator net dispersion modulation technique based on dispersion compensation dielectric film is proposed to control the laser spectral width;

[0033] (3) Through modulation, output in pulse train mode can be achieved. The pulse train frequency can be 1kHz-10MHz. By adjusting the pulse train frequency, modulation depth, duty cycle and other parameters, photolithography under different conditions can be satisfied.

[0034] (4) By using a fully polarization-maintaining fiber structure, the sensitivity of the laser source module (101) to polarization is reduced, the anti-disturbance characteristics of the laser to environmental temperature, vibration and other factors are significantly improved, and high-stability laser output is achieved.

[0035] (5) By adopting a compact cavity design and combining it with full polarization-maintaining fiber fusion splicing technology, the repetition frequency of the laser source module (101) of this invention can reach the GHz level.

[0036] (6) The average laser power used in traditional two-photon lithography 3D printing systems is often tens to hundreds of mW. Due to the small pulse energy and low peak power, and the high light intensity requirements of the two-photon absorption effect, it can only be used for high numerical aperture and high resolution two-photon lithography. The working distance is often <1cm and the scanning area is often <1×1mm. 2 This invention is based on a high-power, high-repetition-rate pulse train 780nm fiber laser, with an average output laser power in the W range, high pulse energy, and high peak power. It can be used not only for traditional high-resolution two-photon lithography but also for long-focal-length, large-format two-photon lithography, providing working distances >10cm and >10×10mm. 2 The scanning area helps to achieve larger volume two-photon lithography. Attached Figure Description

[0037] Figure 1 is a schematic diagram of a high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system according to an embodiment of the present invention.

[0038] Figure 2 is a schematic diagram of the structure of the laser source module in an embodiment of the present invention.

[0039] Figure 3 is a schematic diagram of the structure of the ultrashort fiber resonator mode-locked seed laser used in the laser source module of the present invention.

[0040] Figure 4 is a schematic diagram of the two-photon lithography optical path when the laser transmission system uses a lens group in an embodiment of the present invention.

[0041] Figure 5 is a schematic diagram of the two-photon lithography optical path when the laser transmission system uses a long focal length field lens in an embodiment of the present invention. Embodiments of the present invention

[0042] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] A high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system, as shown in Figure 1, includes a laser source module 101, a laser transmission system 102, a sample displacement system 103, a monitoring system 104, and a programmable terminal 105.

[0044] In one embodiment, the laser source module 101 outputs a 780nm wavelength pulsed laser to the laser transmission system 102. The laser transmission system 102 focuses the pulsed laser and controls the laser spot scanning. The sample displacement system 103 carries the photoresist and moves it. The monitoring system 104 monitors the printing process in real time and determines the position of the laser spot. Based on the feedback from the monitoring system 104, the sample displacement system 103 is adjusted to ensure that the initial position of the laser spot is within the photoresist. The programmable terminal 105 connects the laser transmission system 102, the sample displacement system 103, and the monitoring system 104 to control the printing process.

[0045] The programmable terminal 105 uses software to pre-slice the required 3D printed model in the horizontal direction and generate the scanning trajectory of each slice.

[0046] During the printing process, the programmable terminal 105 controls the galvanometer 404 in the laser transmission system 102 and the three-dimensional motion platform in the sample displacement system 103 to ensure that the laser spot moves along a predetermined trajectory. After each layer of slices is printed, the three-dimensional motion platform drives the photoresist to move a set distance in the vertical direction before printing the next layer of slices, until all slices are printed.

[0047] As shown in Figure 2, the laser source module 101 includes a mode-locked seed laser 201, a high repetition rate pulse train fiber amplifier 202, a dispersion compensator 203, and a frequency doubling module 204 connected in sequence.

[0048] In one embodiment, the mode-locked seed laser 201 outputs a pulsed laser with a wavelength of 1.5 μm. The power of the pulsed laser is first amplified by a high repetition rate pulse train fiber amplifier 202, then the pulse width of the pulsed laser is compressed by a dispersion compensator 203, and finally the frequency is multiplied by a frequency doubling module 204 to output a high repetition rate pulsed laser with a wavelength of 780 nm.

[0049] As shown in Figure 4, the laser transmission system 102 includes a mirror group 402, a dichroic mirror 403, a galvanometer 404, and a lens group, used to focus the pulsed laser onto the photoresist and control the scanning of the laser spot:

[0050] The pulsed laser output from the laser source module 101 enters the galvanometer 404 via the reflector group 402 in the laser transmission system 102. The dichroic mirror 403 is used to deflect the pulsed laser output from the laser source module 101 and transmit the illumination light generated by the illumination source 411. The galvanometer 404 controls the laser spot to scan the pattern. Finally, the lens group focuses the pulsed laser onto the photoresist, controlling the laser spot to scan in the photoresist.

[0051] As shown in Figure 4, the sample displacement system 103 includes a three-dimensional motion platform for carrying the photoresist and positioning it in the X, Y, and Z directions.

[0052] The sample stage carrying the photoresist is placed on top of the three-dimensional motion platform. The initial coordinates are set through the programmable terminal 105. The X-axis translation stage 407 in the three-dimensional motion platform is used to move the sample stage horizontally in the X direction; the Y-axis translation stage 408 in the three-dimensional motion platform is used to move the sample stage horizontally in the Y direction, and the angle between the Y-axis and the X-axis is 90°; the Z-axis lifting stage 406 in the three-dimensional motion platform is used to move the sample stage vertically in the Z direction, and the angle between the Z-axis and the X-axis and Y-axis is 90°. After each layer of slice is printed, the Z-axis lifting stage 406 moves the sample stage vertically a set distance before printing the next layer of slice.

[0053] As shown in Figure 4, the monitoring system 104 is optically coupled to the laser transmission system 102 via a dichroic mirror 403, and includes a beam splitter 409, an image sensor 410, and an illumination source 411, for real-time monitoring of the printing process.

[0054] The beam splitter 409 is used to deflect the illumination light generated by the illumination source 411; the illumination source 411 is used to provide the illumination light required for monitoring, ensuring that the image sensor 410 can clearly capture the image during the printing process; the image sensor 410 is a CCD or CMOS camera, which is coupled to the optical path of the laser transmission system 102 through the dichroic mirror 403 to capture image information during the printing process in real time.

[0055] The programmable terminal 105 is connected to the laser source module 101, the laser transmission system 102, the sample displacement system 103, and the monitoring system 104 to comprehensively control the printing process, as detailed below:

[0056] The programmable terminal 105 controls the mode-locked seed laser 201 in the laser source module 101, including starting, stopping, intensity adjustment, and pulse train modulation, to ensure stable operation of the mode-locked seed laser 201 during printing. The programmable terminal 105 controls the scanning of the galvanometer 404 and the switching of the optical path in the laser transmission system 102 to ensure accurate output of the pulsed laser when needed. The programmable terminal 105 controls the motion trajectory and speed of the three-dimensional motion platform in the sample displacement system 103 to ensure high-precision positioning during printing. The programmable terminal 105 controls the operation of the image sensor 410 and imaging software in the monitoring system 104 to monitor the printing process in real time, ensuring printing accuracy and quality. Based on the feedback from the monitoring system 104, the programmable terminal 105 adjusts the sample displacement system 103 to ensure that the initial position of the laser spot is located on the surface of the photoresist.

[0057] In the laser source module 101, mode-locking technology based on ultrashort fiber resonator is used for seed laser mode locking.

[0058] The mode-locked seed laser 201 employs an ultrashort fiber resonant cavity laser and utilizes a semiconductor saturable absorber mirror 301 to achieve passive mode-locking, with a repetition frequency ≥1GHz and a power fluctuation RMS value ≤5%.

[0059] In one embodiment, the mode-locked seed laser 201 includes a semiconductor saturable absorber mirror 301, a gain fiber 302, a dielectric-coated fiber ferrule 303, a laser diode pump source 304, a wavelength division multiplexer 305, and an optical isolator 306. The laser diode pump source 304 is controlled by a programmable terminal 105 to output pump light. The pump light enters the gain fiber 302 through the wavelength division multiplexer 305 and achieves mode-locking in the resonant cavity composed of the semiconductor saturable absorber mirror 301, the gain fiber 302, and the dielectric-coated fiber ferrule 303. Finally, a pulsed laser is output, which is filtered by the wavelength division multiplexer 305 before being output. The optical isolator 306 is used to prevent the return light from affecting the seed mode-locking state.

[0060] The dispersion compensator 203 is used to compress the pulse width of the pulsed laser to ≤300fs;

[0061] The high repetition rate pulse train fiber amplifier 202 achieves pulsed laser output in pulse train mode through modulation, with the pulse train frequency being 1kHz-10MHz.

[0062] In one embodiment, the step resolution of the X-axis translation stage 407 and the Y-axis translation stage 408 in the three-dimensional motion platform is ≤1μm;

[0063] The stepping resolution of the Z-axis lifting stage 406 in the three-dimensional motion platform is ≤1μm.

[0064] In one embodiment, the illumination source 411 of the monitoring system 104 has a wavelength of 600nm~700nm, and the dichroic mirror 403 reflects 780nm laser light and transmits monitoring bands with wavelengths shorter than 780nm.

[0065] The laser transmission system 102 can switch between a lens group and a long focal length field lens 405. When using the lens group, it can achieve 3D printing with a spatial resolution of ≤500nm; when using the long focal length field lens 405 to replace the lens group, it can achieve large-format 3D printing with a range of ≥10×10mm².

[0066] The lens group includes a scanning lens 501, a barrel lens 502, and an objective lens 503. The scanning lens 501 is responsible for focusing the pulsed laser output from the galvanometer 404 and focusing it on the desired plane. The barrel lens 502 is responsible for relaying imaging and extending the length of the laser transmission system 102. The objective lens 503 is responsible for focusing the pulsed laser onto the photoresist.

[0067] In one embodiment, a field lens 405 (SL-780-150-210G) with a focal length of f=160mm is used as the core optical component to achieve a processing area of ​​110×110mm².

[0068] The laser source module 101 outputs a laser repetition frequency of 1 GHz and a pulse width of 300 fs. The mode-locked seed laser 201 is activated and allowed to self-start. Then, the high-repetition-frequency pulse train fiber amplifier 202 is activated stage by stage, setting the pulse train repetition frequency to 1 kHz and the output power to 1 W. After compression by the dispersion compensator 203, the laser enters the frequency doubling module 204, ultimately yielding a pulsed laser with a wavelength of 780 nm and a pulse width of 300 fs. This pulsed laser is incident on the galvanometer 404 via the reflector group 402 and the dichroic mirror 403. The galvanometer 404 scans at a rate of 50 mm / s, and then the laser is focused onto the upper surface of the sample stage by the field lens 405 with a focal length of f=160 mm. The focused laser spot can be scanned within a large area of ​​110 × 110 mm². The desired 3D printing model is imported into the computer. The software then segments the model layer by layer, generating the scanning trajectory for each layer. Following the program, the computer controls the galvanometer 404 and the 3D motion platform, causing the laser spot to scan layer by layer along a predetermined trajectory in a "bow" shaped pattern. After each layer is printed, the Z-axis lifting stage 406 moves the sample stage downwards by a certain position. The printing process is monitored in real time via a computer-connected monitoring system 104.

[0069] In one embodiment, a high numerical aperture (NA=1.4) oil immersion objective lens 503 is used as the core optical component, and adaptive power modulation technology is combined to achieve a linewidth of 200nm. The specific technical solution is as follows:

[0070] In this embodiment, the laser source module 101 outputs a repetition frequency of 5 GHz and a pulse width of 100 fs. The mode-locked seed laser 201 is activated and allowed to self-start. Then, the high repetition frequency pulse train fiber amplifier 202 is activated step-by-step, setting the pulse train repetition frequency to 1 MHz and the output power to 25 mW. After compression by the dispersion compensator 203, the laser enters the frequency doubling module 204, ultimately obtaining a pulsed laser with a wavelength of 780 nm and a pulse width of 100 fs. This pulsed laser is incident on the galvanometer 404 via the mirror group 402. The galvanometer scans at a rate of 10 mm / s. After collimation by the scanning lens 501, the beam is transmitted through the barrel lens 502 to the high numerical aperture objective lens 503. The high numerical aperture objective lens 503 focuses the beam onto the photoresist located at the bottom of the glass slide. The glass slide-photoresist interface is positioned using the image sensor 410, and the sample displacement system 103 is axially positioned using commands sent by a computer, achieving an accuracy of 0.1 μm. The desired 3D printing model is imported into the computer. The software then divides the model layer by layer, generating the scanning trajectory for each layer. The computer, according to the program, controls the galvanometer 404 and the 3D motion platform to make the laser spot follow the predetermined trajectory in a "bow" shaped scanning pattern for layer-by-layer printing. After each layer is printed, the Z-axis lifting stage 406 moves the sample stage upwards by a certain position. The printing process is monitored in real time via a computer-connected monitoring system 104.

Claims

1. A high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system, characterized in that, It includes a laser source module (101), a laser transmission system (102), a sample displacement system (103), a monitoring system (104), and a programmable terminal (105). The laser source module (101) outputs a pulsed laser of a set wavelength to the laser transmission system (102). The laser transmission system (102) focuses the pulsed laser and controls the laser spot scanning. The sample displacement system (103) carries the photoresist and moves it. The monitoring system (104) monitors the printing process in real time and determines the position of the laser spot. Based on the feedback from the monitoring system (104), the sample displacement system (103) is adjusted to ensure that the starting position of the laser spot is within the photoresist. The programmable terminal (105) connects the laser transmission system (102), the sample displacement system (103), and the monitoring system (104) to control the printing process. The programmable terminal (105) pre-slices the required 3D printed model in the horizontal direction and generates the scanning trajectory of each slice; During the printing process, the programmable terminal (105) controls the galvanometer (404) in the laser transmission system (102) and the three-dimensional motion platform in the sample displacement system (103) to ensure that the laser spot moves along the predetermined trajectory. After each layer of slices is printed, the three-dimensional motion platform drives the photoresist to move a set distance in the vertical direction, and then prints the next layer of slices until all slices are printed.

2. The high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system according to claim 1, characterized in that, The laser source module (101) includes a mode-locked seed laser (201), a high repetition rate pulse train fiber amplifier (202), a dispersion compensator (203), and a frequency doubling module (204) connected in sequence. The mode-locked seed laser (201) outputs a pulsed laser of a set wavelength. The power of the pulsed laser is first amplified by a high repetition rate pulse train fiber amplifier (202), then the pulse width of the pulsed laser is compressed by a dispersion compensator (203), and finally the frequency is multiplied by a frequency doubling module (204) to output a high repetition rate pulsed laser of the set wavelength.

3. The high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system according to claim 1, characterized in that, The laser transmission system (102) includes a mirror group (402), a galvanometer (404), and a lens group, used to focus the pulsed laser onto the photoresist and control the scanning of the laser spot: The pulsed laser output from the laser source module (101) enters the galvanometer (404) via the reflector group (402) of the laser transmission system (102). The galvanometer (404) controls the laser spot to scan the pattern. Finally, the pulsed laser is focused into the photoresist via the lens group, and the laser spot is controlled to scan in the photoresist.

4. The high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system according to claim 1, characterized in that, The sample displacement system (103) includes a three-dimensional motion platform for carrying the photoresist and positioning it in the X, Y, and Z directions; The sample stage carrying the photoresist is placed on top of the three-dimensional motion platform. The initial coordinates are set through the programmable terminal (105). The X-axis translation stage (407) in the three-dimensional motion platform is used to move the sample stage horizontally in the X direction. The Y-axis translation stage (408) in the three-dimensional motion platform is used to move the sample stage horizontally in the Y direction. The angle between the Y-axis and the X-axis is 90°. The Z-axis lifting stage (406) in the three-dimensional motion platform is used to move the sample stage vertically in the Z direction. The angle between the Z-axis and the X-axis and Y-axis is 90°. After each layer of slice is printed, the Z-axis lifting stage (406) moves the sample stage vertically a set distance before printing the next layer of slice.

5. The high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system according to claim 1, characterized in that, The monitoring system (104) is optically coupled to the laser transmission system (102) via a dichroic mirror (403), and includes a beam splitter (409), an image sensor (410), and an illumination source (411) for real-time monitoring of the printing process. The beam splitter (409) is used to deflect the illumination light generated by the illumination source (411); the illumination source (411) is used to provide the illumination light required for monitoring, ensuring that the image sensor (410) can clearly capture the image during the printing process; the image sensor (410) is a CCD or CMOS camera, which is coupled to the optical path of the laser transmission system (102) through a dichroic mirror (403) to capture image information during the printing process in real time.

6. A high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system according to any one of claims 1 to 5, characterized in that, The programmable terminal (105) is connected to the laser source module (101), the laser transmission system (102), the sample displacement system (103), and the monitoring system (104) to comprehensively control the printing process, as follows: The programmable terminal (105) controls the mode-locked seed laser (201) in the laser source module (101), including starting, stopping, light intensity adjustment and pulse train modulation; the programmable terminal (105) controls the scanning of the galvanometer (404) and the switching of the optical path in the laser transmission system (102); the programmable terminal (105) controls the motion trajectory and motion speed of the three-dimensional motion platform in the sample displacement system (103); the programmable terminal (105) controls the operation of the image sensor (410) in the monitoring system (104) and monitors the printing process in real time; according to the feedback of the monitoring system (104), the programmable terminal (105) adjusts the sample displacement system (103) to ensure that the starting position of the laser spot is located in the photoresist.

7. The high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system according to claim 2, characterized in that, The mode-locked seed laser (201) employs an ultrashort fiber resonant cavity laser and utilizes a semiconductor saturable absorber mirror (301) to achieve passive mode-locking, with a repetition frequency ≥1GHz and a power fluctuation RMS value ≤5%. The dispersion compensator (203) is used to compress the pulse width of the pulsed laser to ≤300fs; The high repetition rate pulse train fiber amplifier (202) enables pulsed laser to be output in pulse train mode through modulation, with the frequency of the pulse train being 1kHz-10MHz.

8. The high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system according to claim 3, characterized in that, The laser transmission system (102) switches between a lens group and a long focal length field lens (405). When the lens group is used, 3D printing with a spatial resolution of ≤500nm is achieved. When the long focal length field lens (405) is used to replace the lens group, large-format 3D printing with a range of ≥10×10mm² is achieved. The lens group includes a scanning lens (501), a barrel lens (502), and an objective lens (503). The scanning lens (501) is responsible for focusing the pulsed laser output from the galvanometer (404) and focusing it on the desired plane. The barrel lens (502) is responsible for relaying imaging and extending the length of the laser transmission system (102). The objective lens (503) is responsible for focusing the pulsed laser onto the photoresist.

9. A high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system according to claim 4, characterized in that, The step resolution of the X-axis translation stage (407) and Y-axis translation stage (408) in the three-dimensional motion platform is ≤1μm; The step resolution of the Z-axis lifting stage (406) in the three-dimensional motion platform is ≤1μm.

10. A high repetition rate femtosecond laser pulse train two-photon lithography 3D printing system according to claim 5, characterized in that, The monitoring system (104) has an illumination source (411) with a wavelength of 600nm~700nm, and a dichroic mirror (403) reflects 780nm laser light and transmits monitoring bands with wavelengths shorter than 780nm.

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