Dual-mode laser processing light path device with plane projection and multi-focus parallel direct writing functions

Abstract

The invention discloses a dual-mode laser processing light path device with plane projection and multi-focus parallel direct writing, and belongs to the technical field of laser processing. The system has two working mode light paths, including a surface projection type processing light path based on ultraviolet laser and a multi-focus parallel direct writing processing light path based on ultrashort pulse laser, and the two processing light paths share the same processing objective lens and imaging system through structure optimization. The double advantages of surface projection and multi-focus parallel direct writing are combined, so that the processing device has the characteristics of rapid processing and flexible pattern shaping of a surface projection technology, and also has the capability of rapid processing of a fine structure of a multi-focus two-photon direct writing technology, thereby realizing high-efficiency processing of a complex and high-precision micro-nano structure.

Description

Technical Field

[0001] The present invention relates to the field of laser processing technology, and more particularly to a dual-mode laser processing optical path device with both surface projection and multi-focus parallel direct writing. Background Art

[0002] Laser processing is an important part of the manufacturing industry, and developing new high-efficiency and high-precision laser processing technology has always been a goal pursued by people.

[0003] Surface projection lithography is a processing technology that uses an optical system to project a pattern onto the surface of a photoresist for rapid exposure, triggering a polymerization reaction in a specific area to complete a single-layer process, and then achieve the preparation of a three-dimensional structure through layer-by-layer stacking. It has the characteristics of simple method, rapid processing of large-area patterns, and flexible pattern modulation and shaping. Although surface projection additive manufacturing technology has made many breakthroughs, it is affected by the diffraction limit and has low spatial resolution, making it difficult to achieve high-precision micro-nano structure processing.

[0004] Multi-focus parallel lithography technology is usually based on the principle of two-photon polymerization. It can produce any complex micro-nano structure by precisely controlling the three-dimensional scanning of multiple laser focuses. It has the characteristics of parallel processing capability, improved processing accuracy and breaking the diffraction limit. However, it has problems such as slow processing speed, low efficiency, uneven processing area, and limited applicable materials and processing range.

[0005] Therefore, how to propose a dual-mode laser processing optical path device that combines surface projection and multi-focus parallel direct writing to improve processing flexibility and processing efficiency is an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0006] In view of this, the present invention provides a dual-mode laser processing optical path device with both surface projection and multi-focus parallel direct writing, which can realize efficient processing of complex, high-precision micro-nano structures.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A dual-mode laser processing optical path device with both surface projection and multi-focus parallel direct writing, comprising a surface projection optical path and a multi-focus parallel direct writing optical path; the surface projection optical path adopts an ultraviolet laser light source, and the multi-focus parallel direct writing optical path adopts an ultrashort pulse laser light source;

[0009] The surface projection optical path and the multi-focus parallel direct writing optical path are both provided with a laser power control optical path and a spatial filtering and shaping optical path; the ultraviolet laser light source and the ultrashort pulse laser light source sequentially pass through the laser power control optical path and the spatial filtering and shaping optical path to obtain a TEM00 mode spot, and obtain a beam-expanded parallel light;

[0010] The surface projection optical path and the multi-focus parallel direct writing optical path share a processing objective lens and an imaging system.

[0011] Preferably, the laser power control optical path includes a first half-wave plate and a Glan prism arranged in sequence;

[0012] The spatial filtering and shaping optical path comprises a first convex lens, a pinhole, and a second convex lens which are arranged in sequence.

[0013] Preferably, the light transmission path of the surface projection light path is:

[0014] The expanded parallel light is sequentially transmitted to the processing objective lens through the second half-wave plate, the first total reflection mirror, the first spatial light modulator, the first quarter-wave plate, the polarizer, the second quarter-wave plate, the third convex lens and the first dichroic mirror.

[0015] Preferably, the optical transmission path of the multi-focus parallel direct writing optical path is:

[0016] The expanded parallel light is sequentially transmitted to the processing objective lens through the third half-wave plate, the second total reflection mirror, the second spatial light modulator, the third quarter-wave plate, the fourth convex lens, the fifth convex lens and the second dichroic mirror.

[0017] Preferably, the distance from the first spatial light modulator to the third convex lens is the focal length of the third convex lens, and the distance from the third convex lens to the rear focal plane of the processing objective lens is the focal length of the third convex lens;

[0018] The first dichroic mirror is highly reflective to the ultraviolet laser band used in the surface projection optical path, and highly transparent to the illumination light of the imaging system and the ultrashort pulse laser band used in the multi-focus parallel direct writing optical path;

[0019] In the surface projection optical path, the third convex lens is coaxial and concentric with the optical axis of the processing objective lens and the ultraviolet laser.

[0020] Preferably, the fourth convex lens and the fifth convex lens have the same focal length; the distance from the second spatial light modulator to the fourth convex lens is equal to the focal length of the fourth convex lens, the distance from the fourth convex lens to the fifth convex lens is equal to twice the focal length of the fourth convex lens, and the distance from the fifth convex lens to the rear focal plane of the processing objective lens is equal to the focal length of the fourth convex lens;

[0021] The second dichroic mirror has high reflection for the ultrashort pulse laser band used in the multi-focus parallel direct writing optical path, and high transmission for the illumination light of the imaging system and the ultraviolet laser band used in the surface projection optical path;

[0022] In the multi-focus parallel direct writing optical path, the convex lens is coaxial and concentric with the optical axis of the processing objective lens and the ultrashort pulse laser.

[0023] Preferably, the information loaded on the second spatial light modulator of the multi-focus parallel direct-writing optical path is a multi-focus array phase diagram, and the phase of the multi-focus array is encoded in the entrance pupil phase on the rear focal plane of the processing objective lens through the optical 4f system composed of a fourth convex lens and a fifth convex lens.

[0024] It can be known from the above technical scheme that, compared with the prior art, the present invention discloses a dual-mode laser processing optical path device with both surface projection and multi-focus parallel direct writing, which has two working mode optical paths, including a surface projection processing optical path based on ultraviolet laser, and a multi-focus parallel direct writing processing optical path based on ultrashort pulse laser. The two processing optical paths share the same processing objective lens and imaging system through structural optimization. The present invention combines the dual advantages of surface projection and multi-focus parallel direct writing, so that the processing device has the characteristics of rapid processing of surface projection technology and flexible pattern shaping, and has the ability to rapidly process fine structures of multi-focus two-photon direct writing technology, thereby realizing efficient processing of complex and high-precision micro-nano structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0026] Figure 1 A schematic diagram of the structure of the laser processing device provided by the present invention;

[0027] Figure 2 The schematic diagram of the surface projection phase modulation provided by the present invention;

[0028] Figure 3 This is a multi-region phase distribution diagram provided by the present invention.

[0029] In the figure, 1-1 linear polarized ultraviolet laser; 1-2 ultrashort pulse near-infrared laser; 2 optical shutter; 3 first half-wave plate; 4 Glan prism; 5 first convex lens; 6-1 pinhole; 6-2 first variable aperture; 6-3 second variable aperture; 7 second convex lens; 8-1 second half-wave plate; 8-2 third half-wave plate; 9-1 first total reflection mirror; 9-2 second total reflection mirror, 10-1 first spatial light modulator; 10-2 second spatial light modulator; 11 first quarter wave plate; 12 polarizer; 13 second quarter wave plate; 14 third convex lens; 15 third quarter wave plate; 16-1 first dichroic mirror; 16-2 second dichroic mirror; 17 fourth convex lens; 18 fifth convex lens; 19 imaging camera; 20 imaging lens; 22 processing objective lens; 23 translation stage; 24 sample; 26 safety lighting source; 25 baffle (the Y-axis direction in the coordinate system shown in the figure is perpendicular to the paper surface). DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The embodiment of the present invention discloses a dual-mode laser processing optical path device with both surface projection and multi-focus parallel direct writing, referring to Figure 1 The device includes a surface projection optical path and a multi-focus parallel direct writing optical path; the surface projection optical path adopts an ultraviolet laser light source, and the multi-focus parallel direct writing optical path adopts an ultrashort pulse laser light source. Figure 1 The laser 1-1 is a linearly polarized ultraviolet laser, and the optional working wavelength is 405nm continuous wave laser; the laser 1-2 is a short pulse visible light laser, and the optional working wavelength is 800nm, and the pulse width is less than 200fs.

[0032] The surface projection optical path and the multi-focus parallel direct writing optical path are both provided with a laser power control optical path and a spatial filtering and shaping optical path; the ultraviolet laser light source and the ultrashort pulse laser light source sequentially pass through the laser power control optical path and the spatial filtering and shaping optical path to obtain the TEM00 mode spot, and obtain the beam expansion parallel light;

[0033] The surface projection optical path and the multi-focus parallel direct writing optical path share a processing objective lens 22 and an imaging system.

[0034] Preferably, the laser power control optical path includes a first half-wave plate 3 and a Glan prism 4 which are arranged in sequence;

[0035] The spatial filtering and shaping optical path includes a first convex lens 5, a pinhole 6-1, and a second convex lens 7 which are arranged in sequence.

[0036] Preferably, the light transmission path of the surface projection light path is:

[0037] The expanded parallel light is transmitted to the processing objective lens 22 in sequence through the second half-wave plate 8-1, the first total reflection mirror 9-1, the first spatial light modulator 10-1, the first quarter-wave plate 11, the polarizer 12, the second quarter-wave plate 13, the third convex lens 14 and the first dichroic mirror 16-1.

[0038] Specifically, a linearly polarized ultraviolet light source 1-1 is used, and the optical path of the projection working mode is controlled by the optical gate 2 through the PC end. The laser passes through the half-wave plate 3 and the Glan prism 4 to adjust the laser power (the half-wave plate is used to change the polarization direction of the laser, and the laser energy ratio passing through the Glan prism can be changed to control the laser power in the optical path). The light beam passes through the lens 5 and the pinhole 6-1 in conjunction with the spatial filtering and shaping optical path of the lens 7 to obtain the TEM00 mode spot, and the expanded parallel light is obtained. Subsequently, the second half-wave plate 8-1, the first quarter-wave plate 11, the first spatial light modulator 10-1, the polarizer 12, and the second quarter-wave plate 13 are sequentially arranged along the direction of ultraviolet laser transmission. The expanded parallel ultraviolet laser passes through the second wave plate 8-1, which is 22.5° with the optical axis, and its polarization state direction is 45° with the working direction of the first spatial light modulator 10-1. The reflection angle of the first total reflection mirror 9-1 is 5-10°, and the center of the light beam incident on the first spatial light modulator 10-1 coincides with the center of the liquid crystal chip of the first spatial light modulator 10-1. The phase of the target pattern loaded on the first spatial light modulator 10-1 is always a half-wavelength phase (i.e., π phase), and the first quarter-wave plate 11 can eliminate the light beam depolarization effect caused by the first spatial light modulator 10-1, so that the light reflected from the first spatial light modulator 10-1 to the polarizer 12 is linearly polarized light. The light transmission direction of the polarizer 12 is always parallel to the polarization state of the modulated light of the first spatial light modulator 10-1, and the fast axis direction of the second quarter-wave plate 13 is 45° to the light transmission direction of the polarizer 12 so that the polarization state of the ultraviolet light incident on the objective lens 22 is converted into circular polarization.

[0039] like Figure 2As shown, a is the initial polarization state of the ultraviolet laser at position ①, which is horizontal polarization; b is the setting mode of the half-wave plate, and its fast axis is 22.5° with the polarization direction of the incident light; c is the polarization state direction of the incident light at position ②, which is 45° with the working direction of the first spatial light modulator; the dotted line in d is the working direction of the modulator, and the phase of the target pattern loaded by the first spatial light modulator is always half-wavelength phase (i.e., π phase), and the rest of the area is 0 phase; e is the laser polarization state of the pattern area loaded with π phase at position ③, which will be transformed into a state orthogonal to the polarization state at position ②; f is a schematic diagram of the shape of the transmitted light at position ④ and its polarization state direction; g is a schematic diagram of the polarization state of the transmitted light at position ⑤ being transformed into circular polarization; h is the final expected pattern.

[0040] Furthermore, in the lens shaping system composed of the lens 14 and the first variable aperture 6-2 in cooperation with the processing objective lens 22, the distance from the first spatial light modulator 10-1 to the third convex lens 14 is equal to the distance from the third convex lens 14 to the rear focal plane of the objective lens 22, and these two distances are exactly equal to the focal length of the third convex lens. The third convex lens is coaxial and concentric with the optical axis of the processing objective lens and the ultraviolet laser.

[0041] The target pattern on the first spatial light modulator 10-1 is presented on the rear focal plane of the processing objective lens 22, and the single photon polymerization principle of the ultraviolet laser is utilized to realize large-area rapid processing. The dichroic mirror 16-1 is highly reflective to the ultraviolet laser 1-1 band used in the surface projection optical path, and is highly transparent to the illumination light 26 of the imaging system and the laser 1-2 band used in the multi-focus parallel direct writing optical path.

[0042] Preferably, the optical transmission path of the multi-focus parallel direct writing optical path is:

[0043] The expanded parallel light is transmitted to the processing objective lens 22 in sequence through the third half-wave plate 8-2, the second total reflection mirror 9-2, the second spatial light modulator 10-2, the third quarter-wave plate 15, the fourth convex lens 17, the fifth convex lens 18 and the second dichroic mirror 16-2.

[0044] An ultrashort pulse near-infrared light source 1-2 is used, and the optical path of the projection working mode is controlled by the optical gate 2 through the PC end. The laser passes through the first half-wave plate 3 and the Glan prism 4 to adjust the laser power (the half-wave plate is used to change the polarization direction of the laser, and the laser energy ratio passing through the Glan prism can be changed to control the laser power in the optical path). The light beam passes through the first convex lens 5 and the pinhole 6-1 to cooperate with the spatial filtering and shaping optical path of the second convex lens 7 to obtain the TEM00 mode spot, and obtain the expanded parallel light. Subsequently, the third half-wave plate 8-2, the second spatial light modulator 10-2, the fourth convex lens 17, the fifth convex lens 18 and the second dichroic mirror 16-2, and the processing objective lens 22 shared by the two paths of light are sequentially arranged along the direction of ultrashort pulse laser transmission. After the ultrashort pulse laser 1-2 in the optical path passes through the third half-wave plate 8-2, the polarization state direction forms an angle of 0° with the working direction of the second spatial light modulator 10-2.

[0045] According to the expected number of foci, a multi-region phase distribution map is constructed, such as Figure 3 As shown, the incident beam cross section area is equally divided into N areas, and the incident beam cross section area is divided into a circular area with a center and N-1 fan rings around the circular area, where N is an odd number and greater than 1; the radius of the circular area is Where R is the radius of the incident beam; the angle of the fan ring is The area of ​​each sector ring is equal; each sector ring is equally divided into M sub-sector rings, and the angle of each sub-sector ring is The circular area is equally divided into M sub-areas; the number of sub-sector rings and the number of sub-areas are the same as the expected number of focal points; then according to the pure phase distribution formula:

[0046]

[0047] Where (x0, y0) is the rectangular coordinate of the entrance pupil stop, λ is the laser wavelength, R is the radius of the entrance pupil stop, and n t is the refractive index of the lens immersion medium, NA is the numerical aperture of the lens, and (Δx, Δy) are the focal position coordinates. The phase parameters of each focus are obtained to accurately control the position movement of the focus. The expected multi-focus array phase diagram is loaded onto the second spatial light modulator 10-2. During the processing, the corresponding multi-focus array phase diagram is dynamically loaded to control the laser focus processing path. The third quarter-wave plate 15 converts the polarization state of the light passing through the second spatial light modulator 10-2 into circular polarization to ensure its uniformity. Through the 4f system composed of the fourth convex lens 17, the second variable aperture 6-3, the fifth convex lens 18 and the processing objective lens 22, the focal lengths of the two convex lenses are equal, the distance from the second spatial light modulator 10-2 to the fourth convex lens 17 is exactly equal to the focal length of the convex lens, the distance from the fourth convex lens 17 to the fifth convex lens 18 is exactly equal to twice the focal length of the lens, and the distance from the fifth convex lens 18 to the rear focal plane of the processing objective lens 22 is exactly equal to the focal length of the convex lens.

[0048] The phase on the second spatial light modulator 10-2 is accurately projected onto the rear focal plane of the processing objective lens 22 to achieve entrance pupil phase encoding, and a multi-focal array can be obtained on the focal plane of the objective lens. Subsequently, the two-photon polymerization principle of ultrashort pulse laser is used to achieve high-precision processing. The second dichroic mirror 16-2 has high reflectivity for the ultrashort pulse 1-2 laser band used in the optical path, and high transmittance for the illumination light 26 of the imaging system and the laser 1-1 band used in the surface projection optical path. The optical axis of the convex lens and the objective lens 22 is coaxial and concentric with the ultrashort pulse laser 1-2. The transmitted light is imaged to infinity through the imaging lens 20, collected by the camera mirror 19, and the processing interface is observed in real time.

[0049] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0050] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dual-mode laser processing optical path device with both surface projection and multi-focus parallel direct writing, characterized in that: It includes a surface projection optical path and a multi-focus parallel direct writing optical path; the surface projection optical path adopts an ultraviolet laser light source, and the multi-focus parallel direct writing optical path adopts an ultrashort pulse laser light source; The surface projection optical path and the multi-focus parallel direct writing optical path are both provided with a laser power control optical path and a spatial filtering and shaping optical path; the ultraviolet laser light source and the ultrashort pulse laser light source sequentially pass through the laser power control optical path and the spatial filtering and shaping optical path to obtain a TEM00 mode spot, and obtain a beam-expanded parallel light; The surface projection optical path and the multi-focus parallel direct writing optical path share a processing objective lens and an imaging system.

2. According to claim 1, a dual-mode laser processing optical path device with both surface projection and multi-focus parallel direct writing is characterized in that: The laser power control optical path comprises a first half-wave plate and a Glan prism arranged in sequence; The spatial filtering and shaping optical path comprises a first convex lens, a pinhole, and a second convex lens which are arranged in sequence.

3. According to claim 1, a dual-mode laser processing optical path device with both surface projection and multi-focus parallel direct writing is characterized in that: The optical transmission path of the surface projection optical path is: The expanded parallel light is sequentially transmitted to the processing objective lens through the second half-wave plate, the first total reflection mirror, the first spatial light modulator, the first quarter-wave plate, the polarizer, the second quarter-wave plate, the third convex lens and the first dichroic mirror.

4. According to claim 1, a dual-mode laser processing optical path device with both surface projection and multi-focus parallel direct writing is characterized in that: The optical transmission path of the multi-focus parallel direct writing optical path is: The expanded parallel light is sequentially transmitted to the processing objective lens through the third half-wave plate, the second total reflection mirror, the second spatial light modulator, the third quarter-wave plate, the fourth convex lens, the fifth convex lens and the second dichroic mirror.

5. The dual-mode laser processing optical path device with both surface projection and multi-focus parallel direct writing according to claim 3, characterized in that: The distance from the first spatial light modulator to the third convex lens is the focal length of the third convex lens, and the distance from the third convex lens to the rear focal plane of the processing objective lens is the focal length of the third convex lens; The first dichroic mirror is highly reflective to the ultraviolet laser band used in the surface projection optical path, and highly transparent to the illumination light of the imaging system and the ultrashort pulse laser band used in the multi-focus parallel direct writing optical path; In the surface projection optical path, the third convex lens is coaxial and concentric with the optical axis of the processing objective lens and the ultraviolet laser.

6. The dual-mode laser processing optical path device with both surface projection and multi-focus parallel direct writing according to claim 4, characterized in that: The fourth convex lens and the fifth convex lens have the same focal length; the distance from the second spatial light modulator to the fourth convex lens is equal to the focal length of the fourth convex lens, the distance from the fourth convex lens to the fifth convex lens is equal to twice the focal length of the fourth convex lens, and the distance from the fifth convex lens to the rear focal plane of the processing objective lens is equal to the focal length of the fourth convex lens; The second dichroic mirror has high reflection for the ultrashort pulse laser band used in the multi-focus parallel direct writing optical path, and high transmission for the illumination light of the imaging system and the ultraviolet laser band used in the surface projection optical path; In the multi-focus parallel direct writing optical path, the convex lens is coaxial and concentric with the optical axis of the processing objective lens and the ultrashort pulse laser.

7. The dual-mode laser processing optical path device with both surface projection and multi-focus parallel direct writing according to claim 4, characterized in that: The information loaded on the second spatial light modulator of the multi-focus parallel direct writing optical path is a multi-focus array phase diagram, and the phase of the multi-focus array is encoded in the pupil phase on the rear focal plane of the processing objective lens through the optical 4f system composed of the fourth convex lens and the fifth convex lens.

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